Novel Pyrazole Derivatives and their Dyes; Synthesis and ...

Novel Pyrazole Derivatives and their Dyes; Synthesis

and Applications

A dissertation submitted to the Institute of Chemistry,

University of the Punjab, Lahore, in fulfillment

of the requirements for the degree of

Doctor of Philosophy

in

Chemistry

by

Ghulam Hussain

Institute of Chemistry

University of the Punjab

Lahore

2017

i

ACKNOWLEDGEMENT

All praises for the most merciful Almighty ALLAH, Who enabled me with the blessings of His

Prophet Hazrat Muhammad (PBUH),Whose teachings inspired me to wider my thoughts and

deliberate the things deeply and to complete this dissertation.

I am obliged to pay my heartiest thanks and gratitude to my learned Supervisors Prof. Dr.

Muhammad Makshoof Athar, Director Institute of Chemistry, University of the Punjab Lahore

and Dr Misbahul Ain Khan, Professor Emeritus Islamia University Bahawalpur for their

enthusiastic guidance and inspiration for the submition of this dissertation.

I feel it a great pleasure to express my thanks to all of the respected teachers of the Institute of

Chemistry, University of the Punjab, Lahore for their cooperation and continuous moral support

during my research.

From the core of my heart I am thankful to Prof. Dr. Aamir Saeed, Department of Chemistry,

Quid-e-Azam University Islamabad and Dr. Ghulam Shabir Assistant Professor of Chemistry,

Govt. Gorden College, Rawalpindi for their help in my publications and the completion of my

thesis.

I am very great full to Mr. Abrar Ahmad Chief Executive Officer SRC Pvt. Ltd. and Mr.

Muhammad Faheem Chief of Operations SRC Pvt. Ltd., Lahore Pakistan for providing me

financial and technical assistance for the evaluation of my novel Dyes. I am also very thankful to

all the technical Staff of SRC Pvt. Ltd. especially Mr. Mohammad Naveed Ashraf and Dr.

Rashid Saleem, Managers R&D for their thorough help in the completion of my task.

It is also my fortune to pay my thanks to all my friends especially Prof. Dr. Tahir Nawaz, Prof.

Dr. Zafar Iqbal, University of Sargodha and Dr. Hazoor Ahmad Shad Associate Professor of

Chemistry, Govt. College Jhang for their technical assistance to achieve my this goal.

At the last but not the least, I am thankful to all my family members for their cooperation and

prayers to complete my dissertation.

GHULAM HUSSAIN

ii

List of Figures

S.No. Figure Captions Page No.

Figure 1.1 Tautomeric forms of hydroxypyrazoles (1-3) 1

Figure 1.2 Phenazone (2,3-dimethyl-1-phenyl-5-pyrazolone) as Antipyretic and

Analgesic 1

Figure 1.3 Pyrimidon, 4-Dimethylamino-1,5-dimethyl-2-phenylpyrazol-3-one 2

Figure 1.4 Pyrazole derivative, Butazolidin 4-butyl-1,2-diphenyl-pyrazolidine-3,5-

dione as rheumatoid arthritis 2

Figure 1.5 Sodium1-phenyl-2,3-dimethyl-5-pyrazolone-4-methylamino-

methylsulfonate 2

Figure 1.6 Pyrazolone derivatives as anti-inflammetry drugs 3

Figure 1.7 pyrazole C-glycoside pyrazofurin; 4-hydroxy-3-β-D-ribofuranosyl 1H-

pyrazole-5-carboxamide 3

Figure 1.8 Thiadiazole substituted pyrazole -5-one as anti-cancer drug 4

Figure 1.9 Pyrazole derivative, 4,4-dichloro-1-(2,4dichlorophenyl)-3methyl-5-one

as anti-cancer drug 4

Figure 1.10 Tartarzine, pyrazolone based dye 5

Figure 1.11 sheet diagram for classification of dyes based on their Application 6

Figure 1.12 Flow sheet diagram for classification of dyes based on their Application 6

Figure 1.13 Acidic Metal complex 7

Figure 1.14 Basic Yellow 2, a diarylmethane dye 7

Figure 1.15 C.I. Direct Black 78 8

Figure 1.16 Anthraquinone dye; C.I. Disperse Blue 19 8

Figure 1.17 Fluorescent Brighteners. imidazoline derivative 9

Figure 1.18 C.I. Food Red 3 9

Figure 1.19 C.I. Mordant Red 7 9

Figure 1.20 Oxidation base, Indamine Blue Hair Dye 10

Figure 1.21 H-acid base Reactive Dye 10

Figure 1.22 Anthraquinone type Solvent dye 10

Figure 1.23 Anthraquinone type Vat dye 11

Figure 1.24 Pyrazole based Acid Dye 11

Figure 1.25 Pyrazole based Disperse Dye 12

Figure 1.26 Pyrazole based Mordant Dye 12

Figure 1.27 Pyrazolone based Reactive Dye 13

Figure 1.28 Pyrazolone based Metal Complex Dye 13

Figure 1.29 Pyrazole based Vat Dyes 13

Figure 1.30 Pyrazolone based cationic dyes used for polyamide fibers 14

Figure 1.31 Oxanol and oxanol derivatized dyes used in Photography 15

Figure 1.32 Pyrazolone and Triazole based Dyes 16

iii

Figure 1.33 Pyrazole based Hair Dyes 16

Figure 1.34 Neutral Fluorescence Whitening Agents 17

Figure 1.35 Anionic Fluorescence Whitening Agents 17

Figure 1.36 Cationic Fluorescence Whitening Agents 17

Figure 2.1 Different Tautomeric forms of Pyrazolones 23

Figure 2.2 Four Tautomeric forms of substituted Pyrazolones 24

Figure 2.3 Antidepressant pyrazoles 35

Figure 2.4 Antidepressant and antituberclosis pyrazoles 35

Figure 2.5 Antimicrobial pyrazole derivatives 35

Figure 2.6 Antiamoebic pyrazole derivatives 36

Figure 2.7 Antioxidant pyrazole derivatives 36

Figure 2.8 Cholesterol inhibiting pyrazole derivative 37

Figure 2.9 Insecticidal pyrazole derivative 37

Figure 2.10 Antibacterial pyrazole derivative 38

Figure 2.11 Antitubercular pyrazole derivative 38

Figure 2.12 Anticancer pyrazole derivative 38

Figure 2.13 Amine oxidase inhibitor pyrazole derivative 39

Figure 2.14 Antihypertensive pyrazole derivative 39

Figure 2.15 Metal complexes of 1-phenyl-3-methyl-4-benzoyl pyrazole-5-ones 41

Figure 2.16 Pyrazole cyanine dye 41

Figure 2.17 Pyrazole based Disperse Dyes 42

Figure 2.18 Disazo disperse dyes based on 3(2-hydroxyphenyl) 2-pyrazolin-5-ones 42

Figure 2.19 4-arylhydrazono-3(2-hydroxyphenyl) 2-pyrazolin-5-ones based

disperse dyes 43

Figure 2.20 Pyrazoline based tetrakisazo Calix-[4] resorcinarene dyes 44

Figure 2.21 pyrazole and thiadiazole based heterocyclic dyes 44

Figure 2.22 Copper complexes of pyrazole derivatives

44

Figure2.23 Pyrazole based dyes 44

Figure 2.24 Pyrazoles based disperse dyes 45

Figure 2.25 Pyrazoles based Tetrakisazo dyes 45

Figure 2.26 Pyrazoles based Pigments Orange13 (157),

Orange 34 (158) and Red

38(159). 46

Figure 2.27 Pyranopyrazoles based dyes 46

Figure 2.28 Disazo pyrazolo[1,5-a] pyrimidine reactive dyes 47

Figure 2.29 Bifunctional pyrazolo[1,5-a]pyrimidine reactive dyes 47

Figure 4.1 ORTEP diagram of SPMP diazonium Salt 78

Figure 4.2 Crystal packing with hydrogen bonding pattern as dotted lines. H-atoms

not involved are omitted 79

Figure 4.3 FTIR spectrum of 4-sulphophenyl-3-methyl-5-pyrazolone 82

iv

Figure 4.4 FTIR spectrum of oxime of 4-sulphophenyl-3-methyl-5-pyrazolone. 82

Figure 4.5 FTIR spectrum of diazo-4-sulphophenyl-3-methyl-5-pyrazolone 83

Figure 4.6 UV-Visible Spectra-1 of dyes 201-204 87



Figure 4.9 UV-Visible Spectra-4 of dyes 213-216

93


Figure4.11 UV-Visible Spectra-6 of dyes 221-224 97


Figure 4.13 1H-NMR Spectrum of Acid Dye 3c 101

Figure 4.14 13

C-NMR Spectrum of Acid Dye 3c 102



Figure 4.17 UV-Visible Spectra of dyes 237-240 118





Figure 4.22 FTIR Spectrum of Pyrazolone Acid Dye 8g 127

Figure 4.23 FTIR Spectrum Cu (II) complex (7g) of pyrazolone acid dye 8g 127

Figure 4.24 1H-NMR Spectrum of Pyrazolone Acid Dye 8g 129

Figure 4.25 13

C-NMR Spectrum of Pyrazolone Acid Dye 8g 130






Figure 4.31 FTIR spectrum of Iron complex of dye 18b 161

Figure 4.32 1H-NMR spectrum of ligand acid dye 18b 162

Figure 4.33 13

C-NMR spectrum of ligand acid dye 18b 162








v

List of Schemes

S.No. Title of Scheme Page No.

Scheme 2.1 Synthesis of 1-Phenyl-3-methyl-2-pyrazoline-5-one from Phenyl

hydrazine and acetoacetic ester 18

Scheme 2.2 Synthesis of 2-pyrazolin-5-ones from substituted hydrazine and β-

ketoester 20

Scheme 2.3 Synthesis of 3-pyrazolin-5-ones from substituted Acetyl phenyl

hydrazine also reacts with β-ketoester and β-ketoester

20

Scheme 2.4

Alkylation of 2-pyrazolin-5-ones with methyl iodide Similarly

symmetrical hydrazines produce 1,2-disubstitued 3-pyrazolin-5-

ones77

21

Scheme 2.5 Synthesis of pyrazolidinones from hydrazines, and ɑ, β-unsaturated

carboxylic acids, esters and amides 21

Scheme 2.6 Synthesis of 5-pyrazolidinediones from hydrazines, and malonic ester

or its acid chlorides 21

Scheme 2.7 Synthesis of pyrazolones from hydrazines, and acetoacetic ester or its

amides 22

Scheme 2.8 Synthesis of pyrazolones from diethyl oxalacetate

90 and aryl

hydrazines 22

Scheme 2.9 Synthesis pyrazolone from acetyl succinic acid or its esters with aryl

diazonium chloride 23

Scheme 2.10 Reaction between Pyrazolones and Ketones 24

Scheme 2.11 Reaction between Pyrazolones and activated aldehyde 25

Scheme 2.12 Reaction between Pyrazolones and Aldehyde 25

Scheme 2.13 Bispyrazolones formation from aryl aldehydes condensation with 1-

phenyl-3-methyl-2-pyrazolin-5-one 26

Scheme 2.14 Aldol condensation reaction of Pyrazolenes with Aldehydes 26

Scheme2.15 C-4 Alkylation of Pyrazolones with Methyl Iodide 27

Scheme2.16 C-4 Alkylation of Pyrazolones with triaryl carbinols 27

Scheme2.17 Synthesis of merocyanine from C-4 Alkylation of Pyrazolones 28

Scheme2.18 C-4 Alkylation of Pyrazolones with acrylonitrile 28

Scheme2.19 N-2 Cyanoethylation of Pyrazolones with Methyl Iodide 29

Scheme2.20 C-4 Acylation of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Acetyl

chloride 29

Scheme2.21 C-4 Acylation of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Phthalic

anhydride 30

vi

Scheme2.22 O-Acylation of -pyrazolin-5-ones with benzoyl chloride 30

Scheme2.23 Condensation of 1-Aryl-3-methyl-2-pyrazolin-5-ones with primary

amines 31

Scheme2.24 C-4 nitration of 1-Aryl-3-methyl-2-pyrazolin-5-ones 31

Scheme2.25 C-4 Dinitration of 1-Aryl-3-methyl-2-pyrazolin-5-ones with

Conc.HNO3 32

Scheme2.26 C-4 Sulphonation of 1-Aryl-3-methyl-2-pyrazolin-5-ones 32

Scheme2.27 C-4 Diclorination of 1-Aryl-3-methyl-2-pyrazolin-5-ones 33

Scheme2.28 C-4 Dibromination of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Br2

and NBS 33

Scheme2.29 C-4 nitrosation of 1-Aryl-3-methyl-2-pyrazolin-5-ones 34

Scheme2.30 Oxidative coupling of 3-methyl-1-phenyl-2-pyrazolin-5-one 40

Scheme 2.31 Synthesis of pyrazolone derivative dye, Tartrazine 40

G.Scheme-1 General Scheme-1 for the synthesis of naphthol-AS series of dyes 50

G.Scheme-2 General Scheme-2 for the synthesis of pyrazolone series of dyes 57

G.Scheme-3 General Scheme-3 for the synthesis of naphthol series of dyes 64

G.Scheme-

4a

General Scheme-4a the synthesis of p-subsrtituted Phenol, Resorcinol

and Bisphenol series of dyes(Iron and Copper complexes)

69

G.Scheme-

4b

General Scheme-4b the synthesis of p-subsrtituted Phenol,

Resorcinol and Bisphenol series of dyes(Chromium complexes)

70

Scheme4.1 Synthesis of 4-amino-p-sulphophenyl-3-methyl-5-pyrazolone and its

diazonium salt 77

Scheme 4.2 Synthesis of acid dyes 3a-g and their Fe (II, 5a-g), Cu (II, 6a-g) and

Cr (III, 7a-g) complexes (201-228). 84

Scheme 4.3 Synthesis of acid dyes 8a-g and their Fe (II, 9a-f) and Cu (II, 10a-f)

(229-256). 111

Scheme 4.4 Synthesis of pyrazolone acid dyes 8a-g and their Cr (III, 7a-f)

complex Dyes (229-254). 139

Scheme 4.5 Synthesis of pyrazolone acid dyes 3a-g and their Fe (II, 6a-g), Cu (II,

7a-g) complexes 257-276 159

Scheme 4.6 Synthesis of ligand acid dyes 18a-g and their Fe (II) and Cu (II)

complexes (19a-n, 277-304) 158

Scheme 4.7 Synthesis of ligand acid dyes 18a-g and their Cr (III) complexes

(19o-u, 277-302) 159

G. Scheme General Synthetic Scheme for the synthesis of all dyes

vii

List of Tables

S.No. Title of Tables Page No.

Table-4.1 X-Ray Crystallographic data of SPMP diazonium Salt Table-4.1 80

Table-4.2 geometric parameters (A

o) of 1-(p-sulphophenyl)-3-methyl-4-

azo-5- pyrazoleoxide 81

Table-4.3 Physical properties of dyes 201-204 86







Table-4.10 Dyeing properties of naphthol-AS series 103








Table-4.18 Dyeing properties of pyrazolone dye 131






Table-4.24 Dyeing properties of naphthol series 150






Table-4.30 Dyeing properties of p-substituted phenols and resorcinol dyes 173



Table-4.33 Dyeing properties of bis-phenols dyes 184

Table-4.34 Comparison of the naphthol-AS dye shades with PMS numbers 188

Table-4.35 Comparison of the pyrazolone-pyrazolone dye shades with PMS

number 189

viii

Table-4.36 Comparison of the naphthol dye shades with PMS numbers. 189

Table-4.37 Comparison of thep-substituted phenol & resorcinol dye shades

with PMS numbers 190

Table-4.38 Comparison of the Bisphenol dye shades with PMS numbers. 190

Table-4.39 Comparison of the dyes with well known National &

International leather dyes. 192

Table-4.40 Comparison of my dyes with well known National &

International leather dyes 193

List of Shade Cards

Shade Card-1 part-a Naphthol-AS Dyes 104

Shade Card-1 part-b Naphthol-AS Dyes 105

Shade Card-2 part-a Pyrazolone dyes 132

Shade Card-2 part-b Pyrazolone dyes 133

Shade Card-3 part-a Naphthol-AS Dyes 151

Shade Card-3 part-b Naphthol-AS Dyes 152

Shade Card-4 part-a p-Substituted Phenol and Resorcinol Dyes 174

Shade Card-4 part-b p-Substituted Phenol and Resorcinol Dyes 175

Shade Card-5 Bis-Phenol Dyes 185

ix

List of Abbreviations

Abbreviation IUPAC Name

PTMP 3-methyl-1-(4-methylphenyl)-1H-pyrazol-5-ol

PMP 3-methyl-1-(phenyl)-1H-pyrazol-5-ol

Naphthol-ASE 3-hydroxy-N(4-chlorophenyl) naphthalene-2-carboxamide

Naphthol-ASLC 3-hydroxy-N-(4-chloro-2,5-dimethoxyphenyl) naphthalene-

2-carboxamide

H-Acid 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid

Bisphenol-S 4,4'-sulfonyldiphenol

β-Naphthol naphthalen-2-ol

Resorcinol benzene-1,3-diol

SPCP 5-hydroxy-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylic acid

4-nap 2-amino-4-nitrophenol

SPMP 4-(5-hydroxy-3-methyl-1H-pyrazol-1-yl)benzenesulfonic

acid

2,5-diClSPMP 2,5-dichloro-4-(5-hydroxy-3-methyl-1H-pyrazol-1-

yl)benzenesulfonic acid

Naphthol-ASA 3-hydroxy-N-phenylnaphthalene-2-carboxamide

Naphthol-ASD 3-hydroxy-N(2-methylphenyl) naphthalene-2-carboxamide

4-cap 2-amino-4-chlorophenol

4-sap 3-amino-4-hydroxybenzenesulfonic acid

BPA 4,4'-propane-2,2-diyldiphenol

Naphthol-ASPH 3-hydroxy-N(2-ethoxyphenyl) naphthalene-2-carboxamide

Naphthol-ASBS 3-hydroxy-N-(3-nitrophenyl) naphthalene-2-carboxamide

6-napsa 3-amino-4-hydroxy-5-nitrobenzenesulfonic acid

NPJ 4-hydroxy-7-(phenylamino) naphthalene-2-sulfonic acid

PMS Pantone Matching System numbers

Calc. Calculated

C.I. Color Index

CHN Anal. Carbon, Hydrogen and Nitrogen analysis

umd unmetallized dye

Ph Phenyl

Ar Aryl

Conc. concentrated

x

List of Contents

Chapter 1 INTRODUCTION

1.0 Pyrazoles 1

1.1 Applications of Pyrazoles 1

1.1.1 Pharmaceutical Uses 1

1.1.1a Antipyretic and Analgesic 1

1.1.1b Anti-inflammatory action 3

1.1.1C Antimicrobial and Antitubercular Drugs 3

1.1.1d Pyrazole Based Anticancer Agents 4

1.1.1e Antioxidant Drugs 4

1.1.2 Application as Dyes and Pigments 4

1.1.3 Classification of dyes 5

1.1.3a- Classification of dyes by application method 5

1.1.3b Chemical nature based classification of dyes 6

1.1.4 Important classes of dyes based on chemical composition and applications 7

1.1.4a Acid Dyes 7

1.1.4b Azoic Components and compositions 7

1.1.4c- Basic Dyes 7

1.1.4d- Direct Dyes 8

1.1.4e -Disperse Dyes 8

1.1.4f- Fluorescent Brighteners. 8

1.1.4g- Food, Drugs or Cosmetic Dyes. 9

1.1.4h Mordant Dyes 9

1.1.4i Oxidation Bases 10

1.1.4j- Reactive Dyes 10

1.1.4k- Solvent Dyes 10

1.1.4l- Sulfur Dyes 11

1.1.4m- Vat Dyes 11

1.1.5 Pyrazolone Based dyes 11

1.1.5a Pyrazole acid dyes 11

1.1.5b Pyazole disperse dyes 12

1.1.5c Pyrazole Mordant dyes 12

1.1.5d Pyrazole Reactive dyes 12

1.1.5e Pyrazole Metal complex dyes 13

1.1.5f Pyrazole Vat dyes 13

1.1.5g Cationic pyrazole dyes for polyamide fibers 13

1.1.5h Pyrazole dyes used in Color Photography 14

1.1.5j Pyrazole OBAs/FWAs 16

1.1.5i Pyrazole hair dyes 16

xi

1.1.5j Pyrazole OBAs/FWAs 16

i) Neutral pyrazole OBAs/FWAs 17

ii) Anionic pyrazole OBAs/FWAs 17

iii) Cationic pyrazole OBAs/FWAs 17

Objective of Research 18

Chapter 2 LITERATURE REVIEW

2 Synthesis of pyrazoles 19

2.1 Pyrazoles from hydrazines. 19

2.2 Synthesis of 2-pyrazolin-5-ones. 19

2.3 Synthesis of 3-pyrazolin-5-ones. 20

2.4 Synthesis of pyrazolidinones. 21

2.5 Synthesis of 3, 5-pyrazolidinediones. 21

2.6 Industrial and recent methods of pyrazolones synthesis. 21

2.7 Aryl-3-methyl-2-pyrazolin-5-one. 21

2.8 Aryl-3-corboxy-2-pyrazolin-5-one. 22

2.9 Structure and reactivity of pyrazolones. 23

2.9.1 Tautomerim studies. 23

2.9.2 Condensation reaction of 2-pyrazolin-5-ones. 24

2.9.3 Alkylation reactions of 1-aryl-2-pyrazolin-5-ones. 26

I- Alkylation at C-4. 26

II- Alkylation at N-2 28

2.9.4 Acylation of 1-aryl-2-pyrazoli-5-ones 29

2.9.4a C-4 Acylation. 29

2.9.4b O-Acylation. 30

2.10 Reactions of 2-pyrazolin-5-ones with amines. 30

2.11 Nitration of 1-aryl-2-pyrazolin-5-ones. 31

2.12 Sulphonation of 1-aryl-2-pyrazolin-5–ones. 32

2.13 Halogenation of 1-aryl-2-pyrazolin-5–ones. 33

2.14 Nitrosation of 1-aryl-2-pyrazolin-5–ones. 34

2.15 Synthesis of Pharmacologically active pyrazole derivatives. 34

2.15a Antidepressant Activity. 34

2.15b Antimicrobial pyrazole derivatives. 35

2.15c Antiamoebic pyrazoles. 36

2.15d Antioxidant pyrazole derivatives. 36

2.15e Cholesterol inhibiting pyrazoles. 36

2.15f Insecticidal pyrazole compouds. 37

2.15g Antibacterial pyrazoles. 37

2.15h Antitubercular pyrazole derivatives. 38

2.15i Anticancer pyrazole compounds. 38

xii

2.15j Amine Oxidase Inhibiting pyrazoles. 39

2.15k Antihypertensive pyrazole derivatives. 39

2.15l Oxidation of pyrazoles. 39

2.16 Synthesis of 1-aryl-2-pyrazolin-5–ones dyes. 40

2.17 Synthesis of 1-aryl-2-pyrazolin-5–one Pigments. 45

2.18 Condensed pyrazoles with other heterocyclics and their dyes. 46

2.18a Pyranopyrazoles and their dyes. 46

2.18b Pyrazolopyrimidines and their dyes. 47

Chapter 3 EXPERIMENTAL

3.1 Equipment used: 48

3.2 Instruments used: 48

3.3 Synthesis of diazonium compound of SPMP 49

3.3.1 Nitrosation of SPMP 49

3.3.2 Reduction of Nitroso derivative to amine 49

3.3.3 Diazotization 49

3.4 General Scheme-1 for the Synthesis of naphthol-AS series of dyes 50

3.4.1 Nitrosation of p-Sulphophenyl-3-methyl-5-pyrazolone (SPMP) 50

3.4.2 Diazotization and Coupling with Naphthol AS Couplers 51

3.4.3 Metallization of naphthol-AS Acid Dyes 51

3.5 General Scheme-2 for the Synthesis of pyrazolone series of dyes 57


3.5.2 Diazotization and Coupling with Pyrazolones: 57

3.5.3 Metallization of Pyrazolone Acid Dyes 58

3.6 General Scheme-3 for the Synthesis of Naphthol series of dyes 63


3.6.2 Reduction 64

3.6.3 Diazotization 64

3.6.4 Coupling 65

3.6.5 Metallization of naphthol acid dyes 65

3.7 General Scheme-4 for the Synthesis of p-substituted-Phenol, Resorcinol

and Bisphenol Dyes. 69


3.7.2 Diazotization and Coupling with Phenol Derivatives 71

3.7.3 Metallization of phenolic Acid Dyes. 71

Chapter 4 RESULTS AND DISCUSSION

4.1 Synthesis of 4-amino-1-(p-Sulphophenyl)-3-methyl-5-pyrazolone and its

diazonium Salt 77

4.2 Nitrosation, Reduction and Diazotization of SPMP 77

4.3 Synthesis of Naphthol-AS Series of Dyes 83

xiii

4.3.1 Naphthol-ASA dyes 85

4.3.2 Naphthol-ASBS dyes. 87

4.3.3 Naphthol-ASD Dyes. 89

4.3.4 Naphthol-ASE Dyes. 91

4.3.5 Naphthol-ASLC Dyes 93

4.3.6 Naphthol-ASOL Dyes. 95

4.3.7 Naphthol-ASPH dyes. 97

4.4 Spectral properties of Naphthol-AS dyes 99

4.5. Dyeing properties of Naphthol-AS dyes. 102

4.6 Synthesis of Pyrazolone series of dyes. 110

4.6.1 SPMP dyes. 112

4.6.2 SPCP Dyes. 114

4.6.3 PMP Dyes. 116

4.6.4 4.5.4 PTMP dyes. 118

4.6.5 3-SPMP dyes. 120

4.6.6 3-ClPMP Dyes. 122

4.6.7 2,5-diClSPMP Dyes 124

4.7 Spectral Properties of Pyrazolone Dyes 126

4.8 The Dyeing Properties of Pyrazolone Dyes. 130

4.9 Synthesis of Naphthol Series of Dyes. 138

4.9.1 β-Naphthol dyes. 139

4.9.2 Schaeffer’s acid Dyes. 141

4.9.3 R-Acid dyes. 143

4.9.4 H-Acid Dye. 145

4.9.5 N-Phenyl J. Acid dyes. 147

4.10 The Dyeing Properties of Naphthol Dyes 149

4.11 Synthesis of p- Substituted-Phenols, Resorcinol and Bis-Phenol series of

dyes. 157

4.11.1 p-Chlorophenol dyes. 162

4.11.2 p-Nitrophenol dyes. 164

4.11.3 Phenol-4-sulphonic acid dyes. 166

4.11.4 2-Nitro-4-sulphophenol dyes. 168

4.11.5 Disazo Resorcinol Dyes. 170

4.12 The Dyeing Properties of p-Substituted Phenols and Resorcinol Dyes 172

4.13 Synthesis of Bisphenol Dyes. 179

4.13.1 Bisphenol-S Dyes. 180

4.13.2 Bisphenol-A Dyes. 182

4.14 The Dyeing Properties of Bis-Phenol Dyes 183

xiv

4.15 Comparison of Shades of Present Work Dyes With National and

International Standards. 188

4.15A- Comparison with Pantone Matching System. 188

4.15B- Comparison with well known Leather Dyes. 190

SUMMARY 194

i- naphthol-AS series 194

ii- pyrazolone series 194

iii- naphthol series 194

iv- p-substituted phenol series 195

v- bisphenol series(BPS-dye shown, where Ar- is( p-sulfophenyl group) 195

FUTURE PROSPECTS. 198

1

Chapter 1 INTRODUCTION

1. Pyrazoles

Among heterocyclic compounds pyrazole and its derivatives have a unique part of utilization.

Their applications revolve around their consumption in Pharmaceutical, Agricultural, Dyes and

Pigments, Photography, Analytical Chemistry and even personal care utilities also contain some

sort of pyrazole based additives. Pyrazolones, the hydroxypyrazoles are of three major classes,

each having several Tautomeric forms: 3-pyrazolin-5-one (1); 2-pyrazolin-5-one (2); and. 4-

pyrazolone, also called 2-pyrazolin-4-one (3) Within each class of pyrazolones many tautomers

are possible; for simplicity only one form is shown below.

Figure 1.1; Tautomeric forms of hydroxypyrazoles (1-3)

1.1 Applications of Pyrazoles

1.1.1 Pharmaceutical Uses

Pyrazoles and their derivatives have eminent position regarding pharmaceutical applications

including their usage as antipyretics, analgesics, anti-inflammatory, antifungal, anticancer,

antibacterial and anti-tubercular drugs which are discussed as

1.1.1a Antipyretic and Analgesic

Several compounds with these activities are known. A few are mentioned here with their

Chemical, Medicinal name (Trade name) and structures. Antipyrin (Phenazone) 2, 3-dimethyl-

1-phenyl-5-pyrazolone (Figure1.2), has both Antipyretic and Analgesic activities

1,2.

Figure 1.2; Phenazone; an Antipyretic and Analgesic.

2

Another Antipyrin analogue known as Aminopyrin (Pyrimidon), 4-Dimethylamino-1,5-

dimethyl-2-phenylpyrazol-3-one (Figure 1.3) has been found to be more active than the parent

compound.3

Figure 1.3; Pyrimidon, 4-Dimethylamino-1,5-dimethyl-2-phenylpyrazol-3-one.

The activity of Aminopyrin in Rheumatic fever has been found to be equal to

Salicylates4.Similarly among pyrazole derivatives, Butazolidin (Phenylbutazone) 4-butyl-1,2-

diphenyl-pyrazolidine-3,5-dione2 (Figure 1.4)

has been extensively used as for a long time to

cure various rheumatoid arthritis conditions and in this regards Hemming and Kuzell5 have

published a review.

Figure 1.4; Pyrazole derivative, Butazolidin, used to cure rheumatoid arthritis.

Recently Tulunay et al6., have studied the Efficacy and Safety of Dipyrone

and found to be very

effective in migraine treatment. Dipyrone (Novalgin), which is, Sodium 1-phenyl-2,3-dimethyl-

5-pyrazolone-4-methylamino-methylsulfonate (Figure 1.5).

Figure 1.5; Sodium 1-phenyl-2,3-dimethyl-5-pyrazolone-4-methylamino-methylsulfonate.

3

1.1.1b Anti-inflammatory action

A large literature exists about Anti-inflammatory activity of various pyrazolones, however ,

Amir and Kumar 8 have synthesized different pyrazoles for anti-inflammatory and other

biological activities. Moreover Samir et al.9 have recently reported synthesis of 4-[5-(4-

methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene sulfonamide (4) and 4-[5-(4-

bromophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene sulfonamide (5) as potential anti-

inflammatory agents (Figure 1.6).

Figure 1.6; Pyrazolone derivatives used as anti-inflammetry drugs.

1.1.1d Antimicrobial and Antitubercular Drugs

Several pyrazole derivatives have been found to possess antimicrobial and antitubecular activity

(Figure 1.7). A vast literature exists, however, work by Shelke et al10

., Joshi et.al11

and

Sammaiah et al12

is of particular interest.

O

N NH

OH

OH

OHNH3

+

O

O

CF3

-O

Figure 1.7; Pyrazole C-glycoside pyrazofurin; 4-hydroxy-3-β-D-ribofuranosyl 1H-pyrazole-5-

carboxamide.

4

1.1.1d Pyrazole Based Anticancer Agents

Many pyrazole derivatives, especially pyrazole 5-ones derivatives have found utilization as

Cancer controlling agents and possess anti-tumor activity for example, thiadiazole substituted

pyrazole -5-one (Figure1.8)13

.

Figure 1.8; Thiadiazole substituted pyrazole -5-one as anti-cancer drug.

Similarly another pyrazole derivative, 4,4-dichloro-1-(2,4dichlorophenyl)-3methyl-5-one

(Figure 1.9)14

and many other have been found to be a very effective Cancer treatment

agent15-16

.

Figure 1.9; Pyrazole derivative, 4,4-dichloro-1-(2,4dichlorophenyl)-3methyl-5-one an anti-

cancer drug.

1.1.1e Antioxidant Drugs

Several pyrazole derivatives have been found to be good antioxidants. Umesha et al.17

have

synthesized and characterized many pyrazole compounds for their antioxidant and antimicrobial

activity.

1.1.2 Application as Dyes and Pigments

A large number of pyrazole derivatives are utilized as Dye Intermediates for the synthesis of

several types of Dyes and Pigments; hence it will be better to discuss in detail.

Dyes are intensely colored materials used for coloration of substrates like cotton, paper, nylon,

leather, plastics, hair, foods and many other human utilities. In fact a dye is a colour that

5

distributes itself up to molecular level in its substrate. These may be retained in the substrate by

various phenomena like adsorption, salt formation and metal complex formation or even

sometimes by covalent bond formation.

A dye usually consists of two types of groups which are chromophores (– NO, -NO2, -N=N, -

C=C-, -C=O) and auxochromes (-OH, -SO3H, -NH2, -NHR, -NR2. –SO2NH2, -CO-CH3, -CH=O)

The most comprehensive information source about dyes is Color Index18

, which is a joint

venture of American Association of Textile Chemists and Colorists (AATCC) and Society of

Dyers and Colorists (SDC) UK. Color index is a 10 volume monograph published annually with

several supplement volumes published periodically. As an example of information from this

source, Tartrazine (Figure 1.10)19

is presented which is a pyrazolone dye.

Figure 1.10; Tartrazine, pyrazolone based dye.

1.1.3 Classification of dyes

Dyes are classified in two ways depending upon their application method and chemical

composition (Constitution).

1.1.3a- Classification of Dyes by Application Method

This type of classification of dyes is favorite for end users and includes the dyes which are

represented in Figure 1.11.

6

Figure 1.11; Flow sheet diagram for classification of dyes based on their Application.

1.1.3b-Chemical Nature Based Classification of Dyes

This classification system is favourite for dye manufacturers and scientist21

. According to the

chemical nature/chemical structure dyes are;

Dyes Chemical Constitution

Nitroso Dyes

Nitro Dyes

Azo Dyes

Azoic Dyes

Stilbene Dyes

Diphenyl methane Dyes

Triaryl methane Dyes

Xanthene Dyes

Acridine Dyes

Quinoline Dyes

Methine Dyes

Thaizole Dyes

Indaine Dyes

Azine Dyes

Oxazine Dyes

Thaizine Dyes

Anthraquinone DyesIndigo Dyes

PhthalocyanineAminoketone Dyes

Figure 1.12; Flow sheet diagram for classification of dyes based on their constitution.

7

1.1.4 Important Classes of Dyes Based on Chemical Composition and Applications

1.1.4a-Acid Dyes

Acid dyes are mainly used for nylon, wool, silk, paper, inks and leather. They are usually applied

from neutral to acidic bath. These may be azo, azometal complex, anthraquinone, nitro & nitroso

etc. An example of acid dye of nitroso type is C. I. Acid Green 1(Figure1.13)22

.

Figure 1.13; Acid Metal complex

1.1.4b-Azoic Components and compositions

The word Azoic is derived from [Azo + ice], as these dyes are formed inside the substrate on

molecular level. Substrates are cotton, rayon, cellulose acetate and polyester. Fiber is

impregnated with a coupler and later on treated with a solution of stabilized diazonium salt to

develop color.

1.1.4c-Basic Dyes

Basic dyes find their application in paper, polyacrylic, polyacrylonitrile, polyester and inks

etc.They are applied from acidic dye bath. Chemically these may be cyanine, diarylmethane, azo,

azine, acridine, oxazine and anthraquinone etc. These are also called cationic dyes for example

C.I. Basic Yellow 2 (Figure1.14)23

, a diarylmethane type dye.

Figure 1.14; Basic Yellow 2, a diarylmethane dye.

8

1.1.4d-Direct Dyes

As the name indicates these dyes are applied to substrates directly from their bath. The most

common substrates are cotton, paper, leather and nylon etc. Chemically these may be Azo,

phthalocyanine, Stilbene and oxazine etc. An example of this type is C.I. Direct Black 78

(Figure 1.15)24

, a trisazo dye.

Figure 1.15; C.I. Direct Black 78

1.1.4e-Disperse Dyes

These dyes are applied as fine aqueous dispersions from their bath at an elevated temperature or

at a lower temperature with the help of carriers. The usual substrates are polyester, polyamide,

acrylics, acetate and plastic. Chemically these may be azo, anthraquinone, nitro, styril etc. C.I.

Disperse Blue 19 (Figure 1.16)25

is an example of Anthraquinone dyes.

Figure 1.16; Anthraquinone dye; C.I. Disperse Blue 19

1.1.4f- Fluorescent Brighteners.

These are also called Fluorescent Whitening Agents (FWA’s), Optical Brightening Agents

(OBA’s) and find their application in a variety of substrates like oils, paints, plastics, soaps,

detergents and all fibers. They are applied from their solutions, dispersions or suspentions in a

process. Chemically they may be stilbene, pyrazolones, coumarins, naphthalimides and

imidazoline etc. Brightener Ultraphore WT (Figure 1.17)26

is an example of imidazoline

derivative.

9

Figure 1.17; Fluorescent Brighteners imidazoline derivative.

1.1.4g- Food, Drugs or Cosmetic Dyes.

As the name indicates, these dyes are produced under very strict vigilance and control.

Chemically these may be azo, anthraquinone, carotenoids, and triaryl methane type. C.I. Food

Red 3 (Figure 1.18)27

is an example of azo dye.

Na+

N NS

O

O

-O

OH

SO3

- Na

+

Figure 1.18; C.I. Food Red 3.

1.1.4h-Mordant Dyes

These dyes are applied to wool, leather and anodized aluminum with the help of a mordant like

Al, Cr Salts. Chemically they may be azo and anthraquinone type. C.I. Mordant Red 7

(Figure1.19)28

is an example of azo dye obtained by after chroming process.

N

N

OH

N N SO3

- Na

+

OH

CH3

Figure 1.19; C.I. Mordant Red 7.

1.1.4i-Oxidation Bases

These find application on hair, fur and cotton. The process consists of oxidation of aromatic

amine and phenols on the substrate. Chemically these may be anilines, phenylenediamines,

10

amino phenols reacted (oxidized) with primary intermediate to impart color. Following reaction

is an example of Oxidation base, Indamine Blue (8) 29

dye (Figure 1.20).

Figure 1.20; Oxidation base, Indamine Blue Hair Dye

1.1.4j-Reactive Dyes

These dyes are applied to cotton, wool, silk and nylon. They react with functional group

substrate to form covalent bond. The process requires higher pH (8.5-9.5) and heat (temperature

65-125°C). Chemically these may be azo, anthraquinone, phthallocyanine, formazan, basic and

oxazine. Color Index Reactive Red 130

is an example of azo reactive dye (Figure1.21).

Figure 1.21; H-acid based Reactive Dye.

1.1.4k-Solvent Dyes

Solvent dyes find their application in plastics, gasoline, varnishes, lacquers, inks, fat oils and

waxes. They form solution in the substrate. Chemically they may be azo, triphenylmethane,

anthraquinone and phthalocyanine C.I. Solvent Violet 1331

is an example of anthraquinone type

solvent dye (Figure 1.22).

Figure 1.22; Anthraquinone type Solvent dye.

11

1.1.4l-Sulfur Dyes

These are the derivative of sulfur applied to cotton and rayon. They are usually produced on the

substrate by padding with aromatic components and sodium sulfide, oxidation of the padded

substrate result into color formation. However due to environmental problem the sulfur dyes are

being obsolete.

1.1.4m-Vat Dyes

As the name indicates, these dyes are produced in vats and applied to cotton, wool and rayon.

These are water insoluble and are reduced to soluble Leuco vats with sodium sulfite and oxidized

to original color by oxidation. Chemically these may be anthraquinone and indigoids. C. I. Vat

Orange 332

is an example of Anthraquinone type dye (Figure1.23).

Figure 1.23; Anthraquinone type Vat dye

1.1.5 Pyrazolone Based dyes

Pyrazolone dyes are of great industrial importance. A vast literature exists however a few are

exemplified as under.

1.1.5a Pyrazole acid dyes

As an example of Prazolone acid dyes, C.I. Acid yellow 2733

(Constitution #19130) is shown

in Figure 1.24.

Figure 1.24; Pyrazole based Acid Dye.

12

1.1.5b Pyazole disperse dyes

Out of Prazolone disperse dyes, Disperse Yellow 60 (10)34

(Constitution #12714) is shown

below. Among Food Dyes pyrazolone yellow are well known. As an example Food Yellow

4(11)35

(constitution #19140) is presented in figure 1.25.

Figure 1.25; Pyrazole based Disperse Dye.

1.1.5c Pyrazole Mordant dyes

Pyrazolones also find their application in Mordant dye preparation. C. I. Mordant Orange 3736

(constitution #18730) is an example of pyrazole based mordant dyes (Figure 1.26)

Figure 1.26; Pyrazole based Mordant Dye.

1.1.5d Pyrazole Reactive dyes

Many pyrazolone reactive dyes are being used industrially. Most of these are patented. Reactive

Yellow 237

(constitution #18972) is an example of this type (Figure 1.27)

Figure 1.27; Pyrazolone based Reactive Dye.

N

N

COO- Na

+

OH

N N SO3

- Na

+

-O3SNa

+

N

N

OH

N N

O

O

CH3CH3

10 11

13

1.1.5e Pyrazole Metal complex dyes

Among the pyrazolone dyes perhaps metal complex dyes are of the most interest due to their

light fastness and levelness. C.I. Acid Orange 9238

(constitution #12714) being a 2:1 chromium

complex is presented as an example of this type dye (Figure 1.28).

Figure 1.28; Pyrazolone based Metal Complex Dye.

1.1.5f Pyrazole Vat dyes

Pyrazole has found utilization in vat dyes as well. C. I. Vat Blue 25 (constitution # 70500)

(12)38

is an example of a vat dye derived from 3-pyrazoloanthronylbenzanthrone. Similarly

C.I.Vat Red 13 (constitution#70320) (13)39

is another example of a Vat dye obtained from

anthrapyrazole (Figure 1.29).

N

O

N

O CH3CH3

NNH

O

N

O

NH

1312

Figure 1.29; Pyrazole based Vat Dyes.

1.1.5g Cationic pyrazole dyes for polyamide fibers

Several cationic pyrazole dyes are commercially important. The major use of these is in acrylic

fibers, leather and paper as well. Dye (14)40

is applied to leather and paper to get a clear orange

shade. Similarly brilliant and clear yellow shade are obtained with Cationic dye (15)41

when

applied to leather and paper. Still another interesting light fast blue shade is obtained on

14

Acrylonitrile with Cationic Dye (16)42

and clear Reddish Orange shade is obtained by Cationic

Dye (17)43

on the same substrate (Figure 1.30).

Figure 1.30; Pyrazolone based cationic dyes used for polyamide fibers.

1.1.5h Pyrazole dyes used in Color Photography

Perhaps the latest and most frequent use of pyrazole dyes is in Color photography. In this field

pyrazole dyes are used in several ways including filters, photo sensitizers and photodvelopers or

simply as couplers. Dye (18)44

is an example of a photo sensitizer and chemically it is an Oxanol

type of a pyrazole dye. Similarly a combination of Oxanol type dye (19)45

and (20)45

is used as a

filter that absorbs the visible light completely (Figure 1.31).

15

Figure 1.31; Oxanol and oxanol derivatized dyes used in Photography.

Another achievement was made by the synthesis of 1-Aryl-5-pyrazolone Magenta couplers

having a special Photographically Useful Leaving Groups (PULG) at the coupling position of

pyrazolone as shown below (21)46

. Later on many modifications have been done in this field

having pyrazole moiety for example 1-H (3, 2-C)1,2,4-triazole Couplers as shown below

(22) 47-51

(Figure 1.32).

16

Figure 1.32; Pyrazolone and Triazole based dyes with PULG.

1.1.5i Pyrazole hair dyes

For the preparation of hair dyes many pyrazole derivatives have been frequently used. Among

these 4,5-diamino-1-methyl pyrazole (23) is the most commonly used as an Oxidation Base with

various Couplers (24-26) to produce different colours as shown below52-54

(Figure 1.33)

Figure 1.33; Pyrazole based Hair Dyes.

1.1.5j pyrazole OBAs/FWAs

Pyrazole based Optical Brightening Agents (OBAs) and Fluorescent Whitening Agents (FWAs)

are materials of special interest for Industrial use. Depending upon their ionic character these are

classified into neutral, anionic and cationic types.

17

i) Neutral pyrazole OBAs/FWAs

These OBAs are commonly used for brightening Polyamide fibers and have very high brilliancy;

however these have moderate light and Bleach fastness properties. Fluorescent Whitening Agent

121 (27)55

and Fluorescent Whitening Agent 51 (28)56

are presented as examples of neutral

pyrazoline OBAs/ FWAs (Figure 1.34).

Figure 1.34; Neutral Fluorescence Whitening Agents.

ii) Anionic pyrazole OBAs/FWAs

These OBAs can be used for whitening of cellulosic and polyamide materials .Fluorescent

Whitening Agent 52 (29)57


are examples of Anionic

Pyrazoline OBAs/FWAs (Figure 1.35).

Figure 1.35; Anionic Fluorescence Whitening Agents.

iii) Cationic pyrazole OBAs/FWAs

Like neutral and anionic pyrazole OBAs, cationic OBAs are also frequently used for

Polyacrylonitrile and cellulose acetate. These OBAs are very bright with moderate light fastness.

Fluorescent Whitening Agent 56 (31)59


are shown as

examples here (Figure 1.36)..

Figure 1.36; Cationic Fluorescence Whitening Agents.

18

Objectives of Research

It is well known fact that dyes have very economical and commercial importance. Dyes

manufacturing industries are not well developed in our country due to the fact, most of the

industrial products are concealed and patented. The purpose of this research work is to

synthesize new derivatives of pyrazole and their dyes, having a commercial importance. This

illustrative work will be beneficial for the development of new industrial products and this will

help in import substitution and save foreign exchange. This indigenous development of new

pyrazole based dyes will also open a new era of research work for the growth of countries

economy and industrialization. Keeping in view the importance of dyes our objectives include

The synthesis of a series of new pyrazole derivatives capable of forming dyes including

amine components (active components) as well as new coupling components.

Application of dyes on suitable substrates and evaluation of their substantive properties.

Comparative study of dyes with existing standards of unknown chemistry.

Study of new pyrazole dyes for their chemical structures and stability against the

environmental factors.

19

Chapter 2 LITERATURE REVIEW

Pyrazole was synthesized by Knorr61

in 1833 by the reaction of acetoacetic ester (33) and

phenylhydrazine (34) although at that time the correct structure was not known. The exact

structure was also determined by Knorr62

in 1887 and the name ―Pyrazole‖ was suggested by

Ruhemann63

. Actually this product was 1-Phenyl-3-methyl-2-pyrazoline-5-one (35) as shown

below (Scheme 2.1).

Scheme 2.1; Synthesis of 1-Phenyl-3-methyl-2-pyrazoline-5-one from Phenyl hydrazine and

acetoacetic ester

2 Synthesis of pyrazoles

The synthesis of pyrazole and its derivatives is a very vast field. The details can be found in

literature64

.A few methods showing the synthesis of various pyrazoles, are presented here.

2.1 Pyrazoles from hydrazines.

This is the most primitive method of pyrazoles synthesis and is still being used by many

scientists. The nature of hydrazine and 2nd

component to be used depends on the nature of the

product needed. Hence the methods given here are based on the nature of pyrazole needed as the

product.

2.2 Synthesis of 2-pyrazolin-5-ones.

These have been synthesized by the reaction of appropriate hydrazines with β-ketoester65-68

or

amides 69-71

to give 2-pyrazolin-5-ones as shown by following general reaction Scheme 2.2.

20

Scheme 2.2; Synthesis of 2-pyrazolin-5-ones from substituted hydrazine and β-ketoester.

2.3 Synthesis of 3-pyrazolin-5-ones.

Acetyl phenyl hydrazine also reacts with β-ketoester72-74

to form 3-pyrazolin-5-ones by the loss

of acetyl group as shown below (Scheme 2.3).

Scheme 2.3; Synthesis of 3-pyrazolin-5-ones from substituted Acetyl phenyl hydrazine also

reacts with β-ketoester and β-ketoester.

Similarly 3-pyrazolin-5-ones have been made by Alkylation of 2-pyrazolin-5-ones using methyl

iodide75

or dimethylsulfate76

as an alkylating agent especially to produce Antipyrine as shown

below (Scheme 2.4).

Antipyrine

N

NCH3

O

+ CH3 I N

NCH3

O

CH3

Scheme 2.4; Alkylation of 2-pyrazolin-5-ones with methyl iodide.

Similarly symmetrical hydrazines produce 1, 2-disubstitued 3-pyrazolin-5-ones77

.

21

2.4 Synthesis of pyrazolidinones.

Hydrazines have been also used to produce pyrazolidinones from a number of reactants like

α, β-unsaturated carboxylic acids78

, esters79-80

and amides81

to get the requisite products as shown

below (Scheme 2.5).

R1

R2

R3

O

NH

R4 +NH

R5NH2 NNH

R5

R1

R2 R3

O

43

3744

Scheme 2.5; Synthesis of pyrazolidinones from hydrazines, and α,β-unsaturated carboxylic

acids, esters and amides.

2.5 Synthesis of 3, 5-pyrazolidinediones.

Reactions of malonic ester or its acid chlorides82-84

with hydrazines were used to synthesize 3,5-

pyrazolidinediones shown as under (Scheme 2.6).

O

X

R1

O

X+ NH

R3NHR2

NN

R3

R1

O

O

R2

45

46

47

Scheme 2.6; Synthesis of 5-pyrazolidinediones from hydrazines, and malonic ester or its acid

chlorides.

2.6 Industrial and recent methods of pyrazolones synthesis.

Several pyrazolones have been synthesized industrially. Synthesis of a few is discussed as under

2.7 Aryl-3-methyl-2-pyrazolin-5-one.

In industrial processes these pyrazolones are being synthesized by the reaction of aryl hydrazines

and acetoacetic ester or its amides in solvents like acetic acid85-87

, glycerin88

or even ehtanol89

22

has been used as shown below (Scheme 2.7).

X

O

CH3

O

+ NH

NH2Ar-H2O, -HX

H

NN

OH

Ar

CH3

Where X= OR, NH2

48 49

50

Scheme 2.7; Synthesis of pyrazolones from hydrazines, and acetoacetic ester or its amides.

2.8 Aryl-3-corboxy-2-pyrazolin-5-one.

Recently these pyrazolones are being manufactured by the reaction of diethyl oxalacetate90

and

aryl hydrazines, indicated as under (Scheme 2.8).

H5C2OOC2H5

O

O O

+ NH2

NH

Ar N

N

HOOC

O

Ar

After hydrolysis

49

51 52

Scheme 2.8; Synthesis of pyrazolones from diethyl oxalacetate90

and aryl hydrazines.

Similarly another route of this synthesis is the use of acetyl succinic acid91

or its esters with aryl

diazonium chloride as shown below (Scheme 2.9).

OHOC2H5

O

OCH3 O

+ NN+

Ar NN

HOOC

O

Ar

Cl-

NaOH

5253

54

Scheme 2.9; Synthesis of pyrazolone from acetyl succinic acid or its esters with aryl diazonium

chloride.

23

2.9 Structure and reactivity of pyrazolones.

It has been found since long that pyrazolones are very reactive64

.This is mainly due to the

presence of two hydrogens at C-4 position. Manny studies have been conducted on pyrazolones

especially on 1-aryl-2-pyrazolin-5-ones; a brief review is given here.

2.9.1 Tautomerism studies.

Tautomerism of pyrazolones is a very interesting and challenging aspect of pyrazolone

structure. Several scientists have worked to reveal the tautomeric structures by the application of

latest instrumental techniques. This interesting structural field was even elaborated by Knorr

himself and he synthesized three types of tautomeric pyrazolones as early as 189592

. These are

enol-form (OH form), keto-hydrazone (CH form) and Keto-hydrazine (NH form) as depicted

below (Figure 2.1).

NN

OH

R

X Y

NN

O

R

X Y

NHN

O

R

X Y

Enol form(OH form) Ketohydrazone form(CH form) Ketohydrazine form(NH form)

55 56 57

Figure 2.1; Different Tautomeric forms of Pyrazolones.

Later on extensive studies were conducted by Katritzky93-96

and Elguero97-100

using U.V, I.R.

and NMR spectroscopic techniques to determine tautomerism of pyrazolones. Similarly Hawkes

et al101

. and Elguero et al102

have also studied pyrazolone tautomerism using13

C and 15

N for

NMR Spectroscopy. Among tautomeric forms of pyrazolones, 4-arylazo dyes and pigments

(Figure 2.2) offer the most interesting 4- tautomeric forms 58A-D. Among these, B and C forms

have been found to be the dominant ones as investigated by several scientists103-111

.

24

N

NPh

R

N

N Ar

O H

N

N

O

Ph

R

NH

N Ar

H

H

NN

O

Ph R

N

N

Ar

H

H

58 - B 58 - C 58 - D

----- ----

58 - A

N

N Ar

N

N

O

Ph

R

Figure 2.2; Four Tautomeric forms of substituted Pyrazolones.

2.9.2 Condensation reaction of 2-pyrazolin-5-ones.

This molecule readily reacts by its hydrogen at C4 with several reactants especially aldehydes

and ketones113

. As a result of this condensation a mixture of mono and bis-pyrazolone products

were found to be formed as studied by a number of scientists114-119

and is illustrated below

(Scheme 2.10).

NN

O

R2

R1

R3

R4

O

NN

O

R2

R1

R3

R4N

N

O

R2

R1R3

R4

N

N

O

R2

R1

+ +

59 60 6162

Scheme 2.10; Reaction between Pyrazolones and Ketones.

Many scientists have found that very reactive aldehydes like formaldehyde120

and chloral121-122

on condensation with pyrazolones do not afford dehydration products but only methylols are

formed as shown in Scheme 2.11.

25

NN O

R1

OHR2

NN

O

R1

R2

+H

H

O

NN

O

R1

R2

+OCl

Cl

ClH

NN O

R1

R2

OH

Cl

Cl

Cl

59

59

6364

65 66

Scheme 2.11; Reaction between Pyrazolones and activated aldehyde.

Similarly initially it had been found that aryl aldehydes did not give bispyrazolone as a

condensation product123

but this is contrary to the recent research. Several scientists have found

Knoevengel type condensation of aryl aldehydes with 1-phenyl-3-methyl-2-pyrazolin-5-one,

using MgO124

, LiBr125

and triethanolamine126

in ethanol as a catalyst as shown below (Scheme

2.12).

NN

Ph

CH3

O + Ar

O

H

NN

Ph

CH3

O

H

ArCatalyst

6768

35

Scheme 2.12; Reaction between Pyrazolones and Aldehyde.

Another approach for above reaction was the use of microwave irradiation by Li et al127

., and

Dandia et al128

.

In a more recent research by a number of scientists non catalytic129-133

long time and catalytic

experiments134-139

have supported the primitive idea of bispyrazolones formationas a result of

aryl aldehydes with 1-phenyl-3-methyl-2-pyrazolin-5-one as expressed below (Scheme 2.13).

26

NN

Ph

CH3

O + Ar

O

H

N

NPh

CH3

O

Ar

H

N

NPh

CH3

O

No Catalyst, 27 - 36 h

35

67

69

Catalyst, 2 - 3 h

Scheme 2.13; Bispyrazolones formation from aryl aldehydes condensation with 1-phenyl-3-

methyl-2-pyrazolin-5-one.

Another interesting reaction of 1-aryl-2-pyrazolin-5-ones is condensation with amides especially

Formamide140-142

at C-4 position. This is an aldol condensation followed by dehydration step as

well. The reaction proceeds at an elevated temperature143

as shown below (Scheme 2.14).

NN

R2

O

R1

H

NH

O

R3

+160 - 220 oC

NN

R2

O

R1

NHR3

59

70

71

Scheme 2.14; Aldol condensation reaction of Pyrazolines with Aldehydes.

2.9.3 Alkylation reactions of 1-aryl-2-pyrazolin-5-ones.

Alkylation reactions of 1-aryl-2-pyrazoli-5-ones take place easily at C-4 and N-2 as well with

various alkylating agents like alkyl halides. These alkylation reactions also proved its tautomeric

strucres indicating two types of tautomerism.

I- Alkylation at C-4 indicates CH form.

II- Alkylation at N-2 indicates NH form.

I- Alkylation at C-4.

C-4 Alkylation of pyrazolones depends on the nature of alkylating agent and the reaction

conditions as well, as indicated by 3-methyl-1-phenyl-2-pyrazolin-5-one. Knorr62

found the

27

formation of dialkyl derivative proceeding through a mono substituent as indicated below. This

is alkoxide dependant, hence called Alkoxide effect62

(Scheme 2.15).

CH3I

NaOCH3

CH3I

NaOCH3

NN

CH3

O

Ph

NN

CH3

O

CH3

Ph

NN

CH3

O

CH3

CH3

Ph

35 72 73

Scheme 2.15; C-4 Alkylation of Pyrazolones with Methyl Iodide.

It has been found that many triaryl carbinols and ethers of these carbinols react with 3-methyl-1-

phenyl-2-pyrazolin-5-one to give C-4 alkylation145-146

products. More over orthoesters147-148

also

furnish the same derivatives as shown below (Scheme 2.16).

NN

CH3

O

Ph

+ R1C(OR2)3 NN

CH3

O

Ph

R1

OR2

35

74

75

Scheme 2.16; C-4 Alkylation of Pyrazolones with triaryl carbinols.

The most important feature of C-4 alkylation is the synthesis of countless number of

merocyanine149-151

dyes. Dyes 77 and 79 are two examples of such dyes formed by two different

condensing agents with 3-methyl-1-phenyl-2-pyrazolin-5-one as shown in Scheme 2.17.

28

NN

CH3

O

Ph

+S

N+

S

Ph

C2H5

X-

N

N

O

PhN

S

CH3

C2H5

77

NN

CH3

O

Ph

+S

N+

R1

S

R2

X-

79

35

35

76

78

N

N

O

Ph

R2

S

N

R1

CH3

Scheme 2.17; Synthesis of merocyanine from C-4 Alkylation of Pyrazolones.

In the same way 3-methyl-1-phenyl-2-pyrazolin-5-one undergoes cyanoethylaion at C-4 by the

reaction of acrylonitrile152

as shown below (Scheme 2.18).

NN

CH3

O

Ph

+CH2

CN

N

N

O

Ph

CH3

CN

CN

2

35

80

81

Scheme 2.18; C-4 Alkylation of Pyrazolones with acrylonitrile.

II- Alkylation at N-2

In the absence of NaOCH3, alkylation of 3-methyl-1-phenyl-2-pyrazolin-5-one with R-I results

in the formation of N-2 alkylation product as pointed out by Knorr75

especially with CH3I in

methanol at 100-130 ºC as shown in the reaction below (Scheme 2.19).

29

NN

CH3

O

Ph

+ NN

O

Ph

CH3

CH3

CH3 I + NN

O

Ph

CH3

CH3

CH3CH3100 -130 oC

CH3OH

82435

42

Scheme 2.19; N-2 Cyanoethylation of Pyrazolones with Methyl Iodide.

The product 4 being the major one while 82 is the minor.

2.9.4 Acylation of 1-aryl-2-pyrazoli-5-ones

Acylation reactions of 2-pyrazolin-5-ones are mainly of two types.

I- C-4 Acylation.

II- O-Acylation.

2.9.4a C-4 Acylation.

1-Aryl-3-methyl-2-pyrazolin-5-ones react with various acylating agents to form C-4 acylation

products in good yield. Acylating agents like acid halides153-154

, esters155

and anhydrides156

can

be used easily as was worked initially by many scientists. The reaction with acetyl chloride is

shown below (Scheme 2.20).

NN

CH3

O

Ph

+ CH3 Cl

O

NN O

Ph

CH3

O

CH3

35

83

84

Scheme 2.20; C-4 Acylation of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Acetyl chloride.

C-4 acylation reaction of 1-phenyl-3-methyl-2-pyrazolin-5-one with phthalic anhydride is of

special interest. Phthalic anhydride (85) react with two mole of pyrazolone to produce a

substituted methylidene bis (3-methyl-1-phenyl-5-pyrazlone (86)157-158

(Scheme 2.21).

30

NN

CH3

O

Ph

+ O

O

O N

N

N

N PhPh

OO

COOH

CH3 CH3

86

2

3585

Scheme 2.21; C-4 Acylation of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Phthalic anhydride.

2.9.4b O-Acylation.

O-acylation of 2-pyrazolin-5-ones can be carried out with benzoyl chloride159

in CHCl3 using

triethylamine as an acid binding agent as given in the reaction below (Scheme 2.22).

NN

O

CH3

Ph

+O

Cl

CHCl3

TriethylamineN

NO

CH3

Ph

O

Ph

88

87

35

Scheme 2.22; O-Acylation of -pyrazolin-5-ones with benzoyl chloride.

Similarly O-acylation products of 1-phenyl-3-methyl-2-pyrazolin-5-one have also been obtained

by Bai et al160

using micro wave irradiation.

2.10 Reactions of 2-pyrazolin-5-ones with amines.

It has been found that 2-pyrazolin-5-ones readily react with several aromatic amines to form

imino derivatives under oxidizing catalytic conditions. The most favorite catalyst for this

reaction is Ag2O. Reaction of N, N-diethyl-3-methyl benzene-1,4-diamine161-162

is presented here

(Scheme 2.23).

31

NN O

CH3

Ph

+

NH2

N

CH3

CH3 CH3

Ag2O

NN

CH3

Ph

O

N N

CH3

CH3CH3

8990

35

Scheme 2.23; Condensation of 1-Aryl-3-methyl-2-pyrazolin-5-ones with primary amines.

2.11 Nitration of 1-aryl-2-pyrazolin-5-ones.

Nitration of 1-aryl-2-pyrazolin-5-ones is of special interest. It has been found to depend on the

nature of nitrating agent, its concentration and temperature as well. Dilute HNO3 on reaction

with1-aryl-2-pyrazolin-5-ones gave 4-nitro product75

.This have also been produced by the

oxidation of 4-oximino derivative163

, shown as under (Scheme 2.24).

NN

O

CH3

Ph

NN

O

CH3

Ph

N+

O-

O

NN

O

CH3

Ph

N OH

O3

91 9235

dil. HNO3

Scheme 2.24; C-4 nitration of 1-Aryl-3-methyl-2-pyrazolin-5-ones.

Similarly nitration of 1-phenyl-3-methyl-2-pyrazolin-5-one with concentrated HNO3 resulted

into the formation of 4,4-dinitro derivative(93).This dinitro derivative may even be further

nitrated on phenyl ring to produce (94) and (95) as was found by Bergman et al.164

presented as

under (Scheme 2.25).

32

NN

O

CH3

NN O

CH3O2N

NO2

Conc.HNO3 Conc.HNO3

NN

O

CH3O2N

NO2

O2N

N

N

O

CH3

O2N

NO2

NO2

NO2Nitrating mixture excess

Nitrating mixture excess

95

9493

35

Scheme 2.25; C-4 Dinitration of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Conc.HNO3.

Recently many nitro and pyrazolone derivatives have synthesized by Ruoqun et al165

by

microwave irradiation.

2.12 Sulphonation of 1-aryl-2-pyrazolin-5–ones.

Sulphonation of 1-aryl-2-pyrazolin-5–ones with H2SO4 gave 4-suphonated product as was

investigated by Kufmann166

. Similarly 1-phenyl-3-methyl-2-pyrazolin-5-one afforded the same

product by the use of 20% oleum at 15-20 ºC as found by Ioffe and Khavin167

(Scheme 2.26).

NN

Ph

O

CH3

NN

Ph

O

CH3 SO3H

9635

H2SO4 or

20% Oleum ,15 -20 oC

Scheme 2.26; C-4 Sulphonation of 1-Aryl-3-methyl-2-pyrazolin-5-ones.

33

2.13 Halogenation of 1-aryl-2-pyrazolin-5–ones.

Almost all pyrazolones especially 1-phenyl-3-methyl-2-pyrazolin-5-one (35), are very easily

halogenated at C-4 position. Thus perching Cl2 gas in a solution of (35) in CHCl3 results in the

formation of 4,4-dichloroderivative (97)75,163

as presented below. The same product is obtained

by the reaction of 1-phenyl-3-methyl-5-pyrazolone with phosphorous pentachloride163,168

(Scheme 2.27)

NN

O

CH3

Ph

NN

O

CH3

Ph

ClCl

NN

O

CH3

Ph

3597

PCl5

35

+Cl2 in Chloroform

Scheme 2.27; C-4 Diclorination of 1-Aryl-3-methyl-2-pyrazolin-5-ones.

Bromination of 35 gave monobromo75

(98) and then dibromo derivatives75,163,168

(99) if excess of

bromine was used. Similarly N-bromobenzamide in THF at room temperature gave only

dibromo62,85

product (99) as indicated below (Scheme 2.28).

NN

O

CH3

Ph

NN

O

CH3

Ph

Br

NN

O

CH3

Ph

BrBr

3598

99

Br2 excess

N-bromobenzamide

Br2 equimolar

THF, room temperature

Scheme 2.28; C-4 Dibromination of 1-Aryl-3-methyl-2-pyrazolin-5-ones with Br2 and NBS.

Iodo derivatives of 1-phenyl-3-methyl-2-pyrazolin-5-one have been obtained by reacting the

pyrazolone with KI in KOH. However the product being unstable were difficult yo get in pure

form169

.

34

2.14 Nitrosation of 1-aryl-2-pyrazolin-5–ones.

1-Aryl-3-methyl-2-pyrazolin-5-ones are very easily nitrosated at C-4 position as have been

studied by many scientists62,163,168

. The nitroso derivatives have been found to exist mainly as an

oxime tautomer (93) shown as under (Scheme 2.29).

NN

O

CH3

Ph

NN

O

CH3

Ph

N OH

NaNO2 +HCl

0 - 5 oC

9335

Scheme 2.29; C-4 nitrosation of 1-Aryl-3-methyl-2-pyrazolin-5-ones.

Metwally et al170

have prepared several nitroso derivatives of 2-pyrazolin5-ones and studied their

condensation reactions with active methylene compounds. These condensation products were

evaluated for their pharmaceutical activities. Bilmar et al171

have also prepared nitroso

derivatives of 1-phenyl-2-pyrazolin-5-ones and studied their tautomerism. Similarly 1-phenyl-2-

pyrazolin-5-ones have also been nitrosated at C-4 by Seo et al172

to get oximo derivative of

biological activity. Recently Samir et al173

have synthesized various 4-nitroso derivatives of 1-

phenyl-2-pyrazolin-5-ones and also studied their Physico-Chemical characteristics.

2.15 Synthesis of Pharmacologically active pyrazole derivatives.

Numerous pyrazole derivatives possess many pharmacological activities. Their synthesis and

study is of special interest. A few modern synthetic approaches of pyrazole derivatives with

pharmacological activities are discussed here.

2.15a Antidepressant Activity.

Several scientists have worked in this field recently. Palaskaa et al174

., have synthesized and

evaluated anti-depressant activity of about ten pyrazole derivatives like compound 100-102

shown as under (Figure 2.3).

35

100

O

H3C NNH

O CH3

O CH3

Cl

NNH

OCH3

OCH3Cl 101

102

H3CO

NNH

OCH3

OCH3

Cl

Figure 2.3; Antidepressant pyrazoles.

Kelekci et al175

., have also worked a lot in this field. Similarly Jayaprakash et al176

., have

synthesized several antidepressant and antituberclosis pyrazole derivatives like 103 (Figure 2.4).

103

NN

OH

OH

OH NH S

Figure 2.4; Antidepressant and antituberclosis pyrazoles.

2.15b Antimicrobial pyrazole derivatives.

Many antimicrobial pyrazole derivatives have been synthesized by different scientists. Ozdemir

et al177

., and Abdelwahab et al178

., have recently synthesized pyrazole antimicrobial compounds

like 104 and 105 respectively (Figure 2.5).

104 105

N

S

R

NN

Ar

S

O

NN N

S

Ar

Ar1

Figure 2.5; Antimicrobial pyrazole derivatives.

36

2.15c Antiamoebic pyrazoles.

Several pyrazole compounds have been found to show antiamoebic properties. Budakoti et al179

synthesized many bromo/chloro pyrazole derivatives of such activity. Compound 106 is a

selected example from their work.

Similarly Abid et al180

., have also worked in this field and synthesized several compounds,out of

these compound 107 had a marked antiamoebic properties (Figure 2.6).

106

Br

Cl

NN

S

N

N

N

Where X= Cl/Br

107

XN

N

S

HN

Figure 2.6; Antiamoebic pyrazole derivatives (106 and107).

2.15d Antioxidant pyrazole derivatives.

Recently Babu et al181

., have worked to produce several pyrazole antioxidants. Compound 108

and 109 have been selected as examples from their work (Figure 2.7).

108

NN

SO2NH2

F3C

NH

109

CH3

N N

O

O

O O

OH

Figure 2.7; Antioxidant pyrazole derivatives.

37

2.15e Cholesterol inhibiting pyrazoles.

Jeong et al182

., have prepared pyrazole compounds having Cholesterol inhibiting characteristics.

Compound 110 is an example from this work (Figure 2.8).

110

OCH3

N

N

S

NH OCH3

OH

Figure 2.8; Cholesterol inhibiting pyrazole derivative

2.15f Insecticidal pyrazole compouds.

Several pyrazole derivatives with insecticidal properties have been synthesized by Silver et al183

.

The mechanism of this activity was also studied by these scientists. Compound 111 has been

selected as an example from this work (Figure 2.9).

111

Cl

Cl

NN

NH O

Figure 2.9; Insecticidal pyrazole derivative

2.15g Antibacterial pyrazoles.

A large number of antibacterial pyrazole derivatives have been synthesized by different

scientists. The work of Chimneti et al184

and Vijavergiya et al185

in this field is of special

interest. Compounds 112 and 113 are the examples of their respective work (Figure 2.10).

38

NN

CH3O

OCH3

NN

CH3O

CH3

ClClH3CO

112 113

Figure 2.10; Antibacterial pyrazole derivative.

2.15h Antitubercular pyrazole derivatives.

Pyrazoles with antitubercular activity have been synthesized by many scientists. The work of

Kini et al186

and Ali et al187

is of special appreciation. Compound 114 and 115 are selected

examples from their respective work (Figure 2.11).

N NN

O

O

114 115

CH3

H3CO

Cl

Cl

NH

NN

S

Figure 2.11; Antitubercular pyrazole derivative.

2.15i Anticancer pyrazole compounds.

Several pyrazole derivatives with anticancer properties have been synthesized by many

scientists. Havrylyuk et al188

., have made a very good attempt in this field. Compound 116 is an

example selected from their work. Similar synthetic work has been done by Bhat et al189

.Compound 117 has been shown as an example from this work (Figure 2.12).

116

HO

H3CO

H3CO

NN

HO

NS

O 117

H3CO

OCH3

H3CO

H3CO

N NH

F

`

Figure 2.12; Anticancer pyrazole derivative

39

2.15j Amine Oxidase Inhibiting pyrazoles.

A large number of pyrazole derivatives have Amine Oxidase inhibition properties. Manna et al190

have synthesized several such compounds. Compound 118 is an example from their valuable

work (Figure 2.13).

118

OH

OH

N N

O

CH3

CH3

Figure 2.13; Amine oxidase inhibitor pyrazole derivative.

2.15k Antihypertensive pyrazole derivatives.

Manny pyrazole derivatives have been found to be antihypertensive. Compound 119 is one of the

several compounds of this category synthesized by Turan-Zatouni et al191

(Figure 2.14).

119

H3CO

OH

NN

NS

OCH3

Figure 2.14; Antihypertensive pyrazole derivative.

2.15l Oxidation of pyrazoles.

Pyrazole are very sensitive to Oxidation depending on the nature of oxidizing agent. Mild

oxidizing agents like Nitrous acid62

, phenylhydrazine192-193

and even ferric chloride194

in small

amounts convert 3-methyl-1-phenyl-2-pyrazolin-5-one to a 4,4'-bipyrazole derivative (120)

shown as under (Scheme 2.30).

40

N

N

CH3

O

N

N

CH3

OH

N

N

CH3

OHNitrous acid

Ferric Chloride

Phenylhydrazine

2

12035

Scheme 2.30; Oxidative coupling of 3-methyl-1-phenyl-2-pyrazolin-5-one.

However strong oxidizing agents like KMnO4 completely destroy the whole ring system forming

water, nitrogen, CO2 and pyruvic acid194-195

etc.

2.16 Synthesis of 1-aryl-2-pyrazolin-5-one dyes.

Perhaps the most important and wide use of the pyrazolones especially 2-pyrazolin-5-ones, is

their use as couplers for dyes synthesis. The synthetic history of pyrzole dyes is as old as the

discovery of pyrazole itself. Tartarzine was the Ist dye to be synthesized by Zeigler and

Locher174a

in 1884. The coupling takes place at C-4 in 2-pyrazolin-5-ones producing a monoazo

dye as indicated below for the synthesis of Tartrazine (Scheme 2.31).

Tartrazine

Na+

Na+

Na+ -OOC

NN

O

SO3

-

+

SO3

-

N+

N

0 - 5 oC

Na2CO3

Na+

121

122

Na+ -OOC

NN OH

SO3

-

N N

SO3

-

Scheme 2.31; Synthesis of pyrazolone derivative dye, Tartrazine.

41

Liu and Jia196

have prepared many Transition metal complexes of 1-phenyl-3-methyl-4-benzoyl

pyrazole-5-ones after forming the semicarbazones of pyrazole shown as below for dye (123)

(Figure 2.15).

Where M+ is a transition metal with i t's positive charge.

123

NN

CH3

O

N

N

NH2

O

NN

CH3

O

N

N

NH2

O

M+

Ph

Ph

Figure 2.15; Metal complexes of 1-phenyl-3-methyl-4-benzoyl pyrazole-5-ones.

Shindy et al197

., have prepared several pyrazole based cyanine dyes and have also done the

spectral studies of their dyes. Dye (124) as shown below is a selected example of this research

work (Figure 2.16).

I-

I-

124

N+

CH3

O

NH

NH

O

N

N

N

N

O

O

CH3

CH3

N+

CH3

Figure 2.16; Pyrazole cyanine dye.

Similarly Rizk et al198

have synthesized many new dyes of pyrazole origin. These scientists also

studied the fastness properties of their dyes after application on wool, polyester and blends of

polyester. Most of their dyes were of disperse type. Dyes 125 and 126 are selected examples

from this work (Figure 2.17).

42

N N

NN

NH2

COOHN N

NN

NH2

OCH3

Cl

125 126

Figure 2.17; Pyrazole based Disperse Dyes.

In the same way Mohamed et al199

., have synthesized three new series of pyrazole based

bifuncntioal reactive dyes. Several properties of these dyes like color strength, light fastness,

Molar Extinction Coefficient and washing fastness etc. were studied after the application of these

dyes on cotton and wool.

Abdou et al200

., have also synthesized many new disazo disperse dyes based on

3(2-hydroxyphenyl) 2-pyrazolin-5-ones. These disperse dyes were applied to polyester. The

fastness properties of the dyes were evaluated along with the position of color in CIE LAB

coordinates. The possible tautomeric structures were also screened using proton NMR and FTIR

spectroscopy. Dye 127 is an example selected from this work (Figure 2.18).

127

N+

O-

O

OH

N N

NN

OHNN

Figure 2.18; Disazo disperse dyes based on 3(2-hydroxyphenyl) 2-pyrazolin-5-ones.

43

Metwally et al201

have also synthesized novel 4-arylhydrazono-3(2-hydroxyphenyl) 2-pyrazolin-

5-ones and applied these as disperse dyes for dying polyester. The fastness properties of these

dyes were also studied in detail. Dye 128 is a representative example of this work (Figure 2.19).

128

OH

NN O

N N

H

Figure 2.19; 4-arylhydrazono-3(2-hydroxyphenyl) 2-pyrazolin-5-ones based disperse dyes.

Recently Şener and Şarkaya202

have synthesized 2-pyrazoline based tetrakisazo Calix-[4]

resorcinarene dyes. The dyes were evaluated for their tautomerism by proton NMR& FT-IR.

Moreover the chromophoric shifts depending on pH were also determined. Dye 129 has been

selected as a representative example of this work (Figure 2.20).

129

N N

NNH

CH3

NN

NH

NCH3

NN

NH

N

N N

CH3

OH

OH

OH

OH

N N

CH3

N NCH3

CH3

CH3

OH

OH

OH

OH

N N

NH

N

N N

CH3

Figure 2.20; Pyrazoline based tetrakisazo Calix-[4] resorcinarene dyes.

Similarly Otutu203

has also synthesized pyrazole and thiadiazole based dyes for polyester. The

dyes were evaluated by spectroscopic techniques like 1HNMR,

13CNMR and FTIR. These dyes

showed very good fastness properties. Moreover these dyes were also found to be good

photoconductors as well. Dye 130 and 131 are the selected examples from this work (Figure

2.21).

44

N N

NNH

NH2

NN

S

SH

N N

NNH

NH2

CH3N

N

S

SH

130 131

Figure 2.21; pyrazole and thiadiazole based heterocyclic dyes.

Jiang et al204

have prepared ten Copper complexes of pyrazole derivatives and elucidated their

structures by FTIR, 1HNMR and MS spectroscopic techniques. These complexes were found to

be active catalysts in the degradation of Methyl Orange and Methylene Blue. Complex 132 is a

selected example from this work (Figure 2.22).

OH2

Cl

N NN+

O-

O

S

NHCu

132

Figure 2.22; Copper complexes of pyrazole derivatives.

Similarly Abdelgawad et al205

., have prepared numerous pyrazole dyes of amino sites and linked

these with benzimidazole, benzoxazole and benzothiazole . These derivatives were tested for

anticancer activities. Compound 133 is a selected example from this research work (Figure

2.23).

133

N

N

NH2

NH2

N N

NH

NH

Figure 2.23.; Pyrazole based dye with anticancer activity.

45

Recently Elmaaty et al206

have also synthesized pyrazole disperse dyes and applied these to

ultrasound treated PET fabric. The color strength was measured in Absorbance and CIELAB

coordinates. Dye properties like washing, rubbing and light fastness were evaluated. Moreover

Antibacterial properties of these dyes were also determined. Dye 134 and 135 are two selected

examples (Figure 2.24).

N

N

NH2

NH2

N

N N+

O-

O

N

N

NH2

NH2

N

N Cl

134135

Figure 2.24; Pyrazoles based disperse dyes.

In the same way Şener and Aydin207

have synthesized nine novel tetrakisazo dyes of pyrazole

origin. The dyes were characterized by FTIR, 1HNMR and MS techniques. The synthetic scheme

consisted of tetrazotization of Benzedine, coupling with 5-amino-pyrazoles, then diazotizing the

amine and re-coupling with new couplers. Dye 136 is a representative example of this research

scheme (Figure 2.25).

OH

NNH

NN

N

N

N

NNH

N

NN

HO

CH3H3C

136

Figure 2.25; Pyrazoles based Tetrakisazo dyes.

2.17 Synthesis of 1-aryl-2-pyrazolin-5-one Pigments.

Several pyrazole pigments have been synthesized by many research scientists. Among these

pigments the most favorite and widely used are Pigment Orange13 (137)208

Pigment Orange 34

(138)208

and Pigment Red 38(139)209

(Figure 2.26).

46

NN

NN N N

NN

OH HO

H3C CH3

ClCl

137

NN

NN N N

NN

OH HO

H3C CH3

ClCl

CH3 CH3

138

139

NN

NN N N

NN

OH HO

C2H5OOC COOC2H5

ClCl

Figure 2.26; Pyrazoles based Pigments Orange13 (137), Orange 34 (138) and Red 38(139).

2.18 Condensed pyrazoles with other heterocyclics and their dyes.

This is another vast field of research. Pyrazole have been condensed with several other

heterocyclics like pyrazole itself, pyridine, pyrimidines and pyranes etc. Several condensation

schemes are possible with the same heterocyclic including 1,2-a, 1,2-b, 1,2-c, 1,2-d, 2,3-a 2, 3-b,

2,3-c, 2,3-d etc. Syntheses of a few condensed systems are presented here.

2.18a Pyranopyrazoles and their dyes.

There are several types of pyranopyrazole condensation products. Khan and Cosenza210

have

synthesized and evaluated the reactivity of several pyranopyrazoles. Moreover the structures of

the synthesized compounds were elucidated using IR and NMR spectroscopy. Recently Al-

Amiery et al211

have synthesized series of novel pyranopyrazoles and their dyes as well. These

have been characterized by UV-VIS., FT-IR, 1HNMR and

13CNMR.Moreover theoretical studies

based on ―Density Function Theory‖ were also carried out by these scientists. Dye 140 is

presented as an example from this work (Figure 2.27).

N N

N

NH

CH3

O O

CH3 O

OC2H5

140

Figure 2.27; Pyranopyrazoles based dyes.

47

2.18b Pyrazolopyrimidines and their dyes.

Pyrazolopyrimidines are also of a large variety regarding the condensation schemes. Recently

Youssef et al212

have synthesized disazo pyrazolo[1,5-a] pyrimidine reactive dyes. The dyes were

applied on cotton, wool and silk and evaluated for the dyeing properties. Most of these dyes had

very good light fastness, washing fastness rubbing fastness and perspiration fastness. Dye 141 is

a selected example from this work (Figure 2.28).

141N

N

N

OH OH

NNN N

HO3S

S

O

O

O

SO

OOH

CH3

Figure 2.28; Disazo pyrazolo [1,5-a] pyrimidine reactive dyes.

Similarly Kamel et al213

., have also synthesized bifunctional pyrazolo[1,5-a]pyrimidine reactive

dyes. These dyes were applied to cotton, wool and silk. The fastness properties like light

fastness, washing fastness, rubbing fastness and perspiration fastness were found to be very

good. Dyes 142 and 143 are two selected examples from this work (Figure 2.29).

142N

N

N

OH OH

NNN N S

O

O

O

SO3

- Na

+

NH2

H

Na+ -O3S

.

2

143

2

Na+ -O3S

.

H

NN

Na+ -O3S

N

N

N

OH OH

N N

NH2

NH

N

N

N

Cl

Na+ -O3S NH

Figure 2.29; Bifunctional pyrazolo [1, 5-a] pyrimidine reactive dyes.

48

Chapter 3 EXPERIMENTAL

The present thesis deals with pyrazole derivatives and dyes: synthesis and their applications.

Hence for this purpose various pyrazole dyes were prepared. The main reactions were conducted

by the use of different raw materials like pyrazolones, phenols, naphthols, resorcinol,

aminonaphthols, naphthol-sulphonic acids and bis-phenols etc. Almost all of the chemicals used

were of laboratory grade and used as such. However a few of these were purified by the common

methods given in the literature. The equipment and instruments used were as under.

3.1 Equipment used:

Various types of equipments used were:

i - Melting Point apparatus, Gallenkamp, UK.

ii - Oven, Model # UN75, Memmert, GmbH, Germany.

iii - Multiple Mixer (Falcon Faisalabad Pak.)

iv - Leather Dying Drum Machine = Jiangsu Lianyungang Leather Machinery Factory China,

Model # R-350-6

v- Light Fastness by Xenon Fad-o-meter Model# XF-15N,Shimudzu Corporation Kyoto Japan.

vi- pH Meter = Model = Eutech pH 5+, Eutech Instruments ,USA.

3.2 Instruments used:

i - FTIR, Agilent Cary 630, Agilent Technologies USA.

ii - NMR Bruker DPX 400-Operating at 300/75-13

C M Hz.

iii - Single Crystal X-Ray Machine = Bruker AXS Smart APEX II Single Crystal Diffractometer,

Bruker, USA.

iv - UV-Visible Spectrophotometer = Spectra Flash SF 550,Datacolor Inc.,USA.

49

v - CHN-analyzer = Flash EA 1112 elemental analyzer, Thermo-Fisher Inc. Walthman,

Massachusetts, USA.

3.3 SYNTHESIS OF DIAZONIUM COMPOUND OF SPMP.

This research work consisted of steps like nitrosation of SPMP [1(4-sulphophenyl) 3-methyl-2-

pyrazolin-5-one], reduction of nitroso derivative, diazotization and isolation of diazonium

compound.

3.3.1 Nitrosation of SPMP

In this step SPMP was nitrosated at 0-5ºC using NaNO2 and HCl as described by Knorr1.For this

purpose 25.4g(0.1mole)SPMP was dissolved in 250mL water containing 5.0g(0.125mole)

NaOH. Then 50mL HCl (32%) was added to precipitate SPMP as a very fine paste. The beaker

was jacketed and 100g ice was also added in the paste. A solution of 7.2g (0.104mole) Sodium

nitrite was added drop wise in a period of one hour .The nitrosation was conducted for further

one hour at 0-5ºC.The nitrosated product was a clear solution. The nitroso compound was

filtered to remove some terry material. The clarified nitroso derivative was isolated by salting out

at 15% salt concentration .The nitrosated product yield was 26.0g = 92.1%.

3.3.2 Reduction of Nitroso derivative to amine

In this process reduction of nitroso derivative of SPMP was carried at 100-105ºC using Zinc and

HCl. A mixture of 400mL water and HCl (3:1) was heated to boiling. Then 32.6g (0.1molee

nitroso containing 15% salt) nitroso derivative of SPMP and 30g zinc metal were added

alternatively in small portions at boil. The reduction was completed as the solution became

colorless. A small amount of additional zinc was added and the resultant Amine hydrochloride

was quenched to -7ºC. The excess un-reacted zinc was removed by filtration. The amine being

unstable, cannot be isolated, hence next step diazotization was carried out.

3.3.3 Diazotization

In this step, the amine hydrochloride of SPMP was diazotized using an aqueous solution of

NaNO2 (6.9g dissolved in 250mL of solution) at -5 to -2ºC.The diazotization was completed in

about 3.30hours. It was almost a clear solution with some flocculants which were removed by

50

filtration. The diazonium compound was isolated by the addition of common salt @28% and

keeping the same for 18-20h at 0-5ºC. Filteration afforded yellow diazonium compound. This

was crystallized from rectified sprit to get yellow needles of diazonium compound which was

dried to give the desired product.

Yield: 29.5g (87%)

3.4 General Scheme-1 for the Synthesis of Naphthol-AS Series of Dyes

Dyes = 3a-g

N

N

CH3

O

N

N

O

NHO R1

R2

R3R4

HO3S

N

N

CH3

O

N

N

O

NH OR1

R2

R3 R4

SO3HCr

-

OH2OH2

OH2

N

N

CH3

O

N

N

O

NHO R1

R2

R3R4

M

HO3S

65 -75 oC

Cr(CH3COO-)3

100 - 105 oC

2a R1 =R2= R3 =R4=H

2c R2= R3 =R4=H,R4=CH32b R1 = R3 =R4=H,R2=NO22d R1= R2 =R4=H,R3=Cl

2e R1= R4 = OCH3,R2=H,R3=Cl 2f R1= OCH3,R2=R3,R4=H 2g R1= OC2H5,R2=R3,R4=H

3a-g Dyes = 201,205,209,213,217,221,225

5a-g Dyes = 203,207,211,215,219,223,227

6a-g Dyes = 204,208,212,216,220,224,228

7a-g Dyes = 202,206,210,214,218,222,2267a-g Dyes

5a-g,6a-g Dyes

Metal Salts 4a-b

4a= FeSO4 .7H2O

4b= CuSO4 .5H2O

N

N

CH3

OH

HO3S

N

N

O

NHOH R1

R2

R3R4

3.4.1 Nitrosation of p-Sulphophenyl-3-methyl-5-pyrazolone (SPMP)

1-(p-sulphophenyl)-3-methyl-5-pyrazolone (144) (25.4 g, 0.1 mol) was suspended in H2O (250

mL). Hydrochloric acid (45 mL) was added to this well stirred suspension. The reaction mixture

was cooled to 0-5°C in an ice bath. A solution of NaNO2 (6.9 g, 0.1 mol) in H2O (25 mL)

previously cooled to 0°C, was then added over a period of 35 minutes with stirring. The stirring

was continued for an hour maintaining the same temperature, with a positive test for nitrous acid.

Later on the excess of nitrous acid was destroyed with required amount of sulphamic acid. The

Nitroso (Oxime) was filtered after salting out. The nitroso was reduced by stirring in 200mL

water containing 85mL HCl and 23g Zinc metal(added in small portions) at boil for 4 hours to

complete the reduction (reaction contents became colorless).

51

3.4.2 Diazotization and Coupling with Naphthol AS Couplers

To the well stirred ice jacketed aqueous suspention (2.69 g) of 1( p-sulphophenyl)-3-methyl-4-

amino pyrazolone at 0-5 oC was added sodium nitrite solution (0.7 g) and to it 3.5 mL conc. HCl

was added. The reaction mixture was vigorously stirred for 3h at the above low temperature to

achieve the diazonium salt of 1-(p-sulphophenyl)-3-methyl-4-amino pyrazolone. After the

synthesis of diazonium compound, it was coupled with 0.010 mol (2.780 g) coupler Naphthol-

ASA (2a) dissolved in 200 mL water containing 0.45 g NaOH. The coupling was facilitated

using sodium carbonate as acid binding agent. The reaction mixture was given 4.50 h to

complete the coupling at 0-5 oC. The dye was brought to room temperature; pH was reduced

upto 4.5 by HCl, filtered and dried in oven at 70-75 oC till constant weight was obtained with

percentage yield of 85%. By adopting the same procedure other dyes 3b-g were prepared from

couplers 2b-g (General Scheme-1).

3.4.3 Metallization of Acid Dyes

For the synthesis of metal complexes (Iron complex), pH of 25mL of dye 3a (0.005M) was

reduced to 6.5 with HCl. Then it was heated to 70oC and to it 5 mL (0.005mol Fe

+2) solution of

ferrous sulfate (FeSO4.7H2O) was added drop wise. Mixing and heating at this temperature was

continued for further 1.0 hours till the metallization was completed as shown by the comparative

TLC. The dye was cooled to room temperature; its pH was reduced to 1.0 with conc. HCl. The

dye was salted out with sodium chloride, which was subsequently filtered and dried in oven at

80oC till constant weight.

Similarly Chromium (III) and Copper (II) complexes of dye 3a were prepared by treating dye

with Cr (CH3COO-)3 and CuSO4.5H2O at 100-105

oC and 65-70

oC for chromium and copper

respectively. In this way complexes 5a-g, 6a-g and 7a-g were synthesized from respective dye

ligands.

201 (C27H21N5O6S)

Orange, (76.11%) λmax in nm (log ε): 614 (3.54), 396 (3.82), 355 (3.54). FTIR (KBr, cm-1

) νmax:

3298 (NH, str), 3050 (C=C-H), 2924(CH2)1675 (C=O), 1619, 1559 (C=C aromatic), DMSO-

d61448 (N=N, str), 1343(CH2), 1209 (S=O, str), 1174(C-O), 872 (Ar-H). 1H NMR (300 MHz,) δ:

12.03 (1H, s, O-H), 9.98 (1H, s, N-H), 8.36 (1H, d), 8.14 (2H, d), 7.89 (1H, s), 7.84 (1H, s,

52

SO3H), 7.77 (2H, d), 7.75 (1H, d), 7.61 (1H, t), 7.40 (2H, d), 7.32 (2H, t), 7.29 (1H, t), 7.08(1H,

t), 4.81 (1H,s), 2.47(3H, s).13

C NMR (75 MHz, DMSO-d6) δ: 167.91, 165.19, 160.80, 159.86,

140.53, 137.94, 136.68, 135.45, 131.75, 130.73, 129.03, 129.03, 128.86, 128.49, 128.21, 126.58,

126.58, 126.33, 124.91, 123.89, 122.49, 122.49, 120.14, 118.16, 70.40, 13.12. Anal. Calcd. For

C27H21N5O6S: C, 59.66; H, 3.89; N, 12.88; S, 5.90; Found: 59.66; H, 3.89; N, 12.88; S, 5.90.

205 (C27H20N6O8S)

Brown, (75.65%) λmax in nm (log ε): 608 (3.67), 396 (3.49), 355 (3.48). FTIR (KBr, cm-1

) νmax:

3293 (NH, str), 3065 (C=C-H), 2924 (C-H, str), 1670 (C=O), 1620, 1526 (C=C aromatic), 1445

(N=N, str), 1317(CH2), 1209 (S=O, str), 1050 (C-O), 875 (Ar-H). 1HNMR (300 MHz, DMSO-

d6) δ: 10.03 (1H, s, N-H), 8.56 (1H, s), 8.33 (1H, s), 8.19 (1H, d), 8.16 (2H, d), 8.02 (1H, d), 7.87

(1H, s, SO3H), 7.83 (2H, d), 7.78 -7.59 (3H, m), 7.41-7.24 (2H, m), 6.35(1H, s, O-H), 4.84 (1H,

s), 2.44 (3H, s).13

C-NMR (75 MHz DMSO-d6) δ (ppm) : 167.91, 165.19, 160.80, 159.86, 148.41,

140.53, 138.96, 137.94, 135.45, 131.75, 130.73, 128.67, 128.49, 128.21, 127.81, 126.58, 126.33,

123.89, 120.85, 120.14, 118.16, 116.67, 68.95, 13.12. Anal. Calcd. For C27H20N6O8S: C, 55.10;

H, 3.43; N, 14.28; S, 5.45, Found: C, 55.10; H, 3.43; N, 14.28; S, 5.45.

209 (C28H23N5O6S)

Tan, (81.15%) λmax in nm (log ε): 643 (3.65), 396 (3.60), 355 (3.44). FTIR (KBr, cm-1

) νmax:

3315 (NH, str), 3049 (C=C-H), 2920 (CH2), 1675 (C=O), 1623, 1545 (C=C aromatic), 1459

(N=N), 1343(C-H, bend), 1159 (S=O), 883 (Ar-H). 1H-NMR (300 MHz, DMSO-d6) δ: 9.78

(1H, s, N-H), 8.32 (1H, s), 8.17 (2H, d), 7.83 (2H, d), 7.81 (1H, s, SO3H), 7.80 (1H, d), 7.54 (1H,

d), 7.52-7.38 (2H, m), 7.27-7.03 (4H, m), 4.89 (1H, s), 2.41 (3H, s), 2.32 (3H, s). 13

C-NMR (75

MHz, DMSO-d6) δ (ppm): 166.74, 165.19, 160.80, 159.86, 140.53, 137.94, 136.28, 135.45,

131.75, 131.42, 130.73, 129.83, 128.86, 128.49, 128.21, 127.66, 126.58, 126.33, 126.22, 123.89,


H, 4.16; N, 12.56; S, 5.75; Found: C, 60.32; H, 4.16; N, 12.56; S, 5.75.

213 (C27H20ClN5O6S)

Tan, (80.72%).λmax (nm) (log ε): 635 (3.72), 455 (3.61), 396 (3.60), 355 (3.52). FTIR (KBr, cm-

1) νmax: 3448 (OH, NH), 3054 (C-H, str), 2920 (C-H. aliphatic), 1680 (C=O, str), 1660, 1597,

1539 (C=C aromatic), 1489 (N=N, str), 1325(C-H, bend), 1159 (S=O str), 1070, C-O), 827

(C=C, bend). 1HNMR (300 MHz, DMSO-d6) δ: 10.16 (1H, s, N-H), 8.31(1H,s), 8.17(2H, d),

7.95 (1H, s, SO3H), 7.83(1H, d), 7.52- 7.38(2H, m), 7.41(2H, d), 7.35 (2H, d), 7.27(1H, t), 4.89

53

(1H, s), 2.41(3H, s). 13

CNMR (75 MHz, DMSO-d6) δ (ppm) : 167.91, 165.19, 160.80, 159.86,

140.53, 137.94, 136.21, 135.45, 131.75, 130.73, 129.97, 128.99, 128.86, 128.49, 128.21, 126.58,

126.33, 123.89, 123.04, 120.14, 118.16, 70.54, 13.12. Anal. Calcd. For C27H20ClN5O6S: C,

56.11; H, 3.49; N, 12.12; O, 16.61; S, 5.55; Found: C, 56.11; H, 3.49; N, 12.12; S, 5.55.

217 (C28H23N5O7S)

Orange, (80.72%). λmax in nm (log ε): 635 (3.72), 455 (3.61), 396 (3.60), 355 (3.52). FTIR (KBr,

cm-1

) νmax: 3305 (NH, s), 3054 (C-H, str), 2925 (C-H. aliphatic), 1673 (C=O, str), 1635, 1560

(C=C aromatic), 1453 (N=N, str), 1320 (C-H, bend), 1240 (S=O str), 1056, C-O), 880 (C=C,

bend). 1HNMR (300 MHz, DMSO-d6) δ: 12.65 (1H, s, O-H), 10.32 (1H, s, N-H), 8.15 (2H, d),

7.85 (2H, d), 7.80 (1H, s, SO3H), 7.73(1H, s), 7.83-7.75 (2H, m), 7.71 (1H, d), 7.65 (1H, d),

7.05- 6.72 (4H, m), 4.81(1H, s), 3.82 (3H, s), 2.34 (3H, s). 13

C-NMR (75 MHz, DMSO-d6) δ

(ppm) : 166.74, 165.19, 160.80, 159.86, 149.93, 140.53, 137.94, 135.45, 131.75, 130.73, 128.86,

128.49, 128.26, 128.21, 126.58, 126.33, 126.07, 123.89, 122.81, 121.32, 120.14, 118.16, 112.38,

69.52, 56.79, 13.12. Anal. Calcd. For C28H23N5O7S: C, 58.63; H, 4.04; N, 12.21; S, 5.59; Found:

C, 58.63; H, 4.04; N, 12.21; S, 5.59.

225 (C29H24Cl N5O8S)

Bordeaux, (83.22%). λmax in nm (log ε): 609 (3.49), 455 (3.72), 396 (3.67), 355 (3.47). FTIR

(KBr, cm-1

) νmax: 3311 (NH, s), 3050 (C-H, str), 2924 (C-H. aliphatic), 1685 (C=O, str), 1654,

1541 (C=C aromatic), 1451 (N=N, str), 1332(C-H, bend), 1260 (S=O str), 1030, C-O), 850

(C=C, bend). 1H-NMR (300 MHz, DMSO) δ: 9.14 (1H, s, N-H), 8.34 (1H, d), 8.30 (1H, s), 8.15

(2H,d), 7.96 (1H, s, SO3H), 7.82 (2H,d), 7.80-7.70 (m, 2H), 6.75 (2H, s), 6.45(1H, s, O-H),

4.26(1H, s), 3.82(6H, s), 2.43(3H, s).13

C-NMR (75 MHz, DMSO-d6) δ (ppm) : 165.65, 165.19,

160.80, 159.86, 154.30, 154.30, 140.53, 137.94, 135.45, 131.88, 131.75, 130.73, 128.86, 128.49,

128.21, 126.58, 126.33, 126.07, 123.89, 120.14, 118.16, 105.57, 68.78, 56.79, 56.79, 13.12.

Anal. Calcd. For C29H24Cl N5O8S: C, 54.59; H, 3.79; N, 10.98; O, S, 5.02; Found: C, 54.59; H,

3.79; N, 10.98; S, 5.02.

203 C27H25FeN5O9S

Brown, λmax in nm (log ε): 480, 3274.5 (NH, str), 3021(C=C-H), 2922(CH2), 2851, 1593, 1541,

1489 (C=C aromatic), 1438 (N=N), 1382 (C-H, bend), 1309 (S=O), 1151 (C-O), 915(C=C-H,

bend), 590 (Fe-N, str). Anal. Calcd. For C27H25FeN5O9S; C, 49.78; H, 3.87; N, 10.75; S, 4.92.

Found: C, 49.67; H, 3.93; N, 10.70; S, 4.98

54

207 C27H24FeN6O11S

Dark Brown, λmax in nm (log ε): 475, 3274(NH, str), 3021(C=C-H), 2922(CH2), 2851, 1593,

1541, 1489 (C=C aromatic), 1436(N=N), 1382 (C-H, bend), 1151 (C-O), 827 (C=C-H, bend),

743(C=C-H, bend), 585 (Fe-N, str). Anal. Calcd. For C27H24FeN6O11S; C, 46.57; H, 3.47; Fe,

8.02; N, 12.07; S, 4.60. Found: C, 46.51; H, 3.50; N, 12.00; S, 4.68.

211 C27H24ClFeN5O9S

Dark Brown, λmax in nm (log ε): 493, 3289 (NH, str), 3050(C=C-H), 1689 (C=O), 1559(C=C

aromatic), 1448(N=N), 1343 (C-H), 1209 (S=O), 1174 (C-O), 887, 870, 708 (C=C-H, bend), 589

(Fe-N, str). Anal. Calcd. For C27H24ClFeN5O9S; C, 47.28; H, 3.53; Fe, 8.14; N, 10.21; S, 4.67. ;

Found: C, 47.36; H, 3.59; Fe, 8.10; N, 10.16; S, 4.70.

215 C28H27FeN5O9S

Brown, λmax in nm (log ε): 480, 3296(NH, str), 3050(C=C-H), 1593, 1559(C=C aromatic),

1448(N=N), 1343 (C-H), 1209 (S=O), 1174 (C-O), 870, 708, 687 (C=C-H, bend), 578 (Fe-N,

str). Anal. Calcd. For C28H27FeN5O9S; C, 50.54; H, 4.09; N, 10.52; S, 4.82; Found: C, 50.50; H,

4.19; Fe, 8.30; N, 10.43; S, 4.86.

219 C29H29FeN5O10S

Brown, λmax in nm (log ε): 479, 3296 (N-H, str), 3052(C=C-H), 1619, 1559 (C=C aromatic),

1448 (N=N), 1343 (C-H), 1209 (S=O), 1174 (C-O), 870,739,708,687(C=C-H, bend), 583 (Fe-N,

str). Anal. Calcd. For C29H29FeN5O10S ; C, 50.08; H, 4.20; N, 10.07; S, 4.61; Found: C, 50.00;

H, 4.28; N, 10.00; S, 4.67

227 C29H28 ClFeN5O11S

Grey, λmax in nm (log ε): 482, 3276 (NH, str), 3170 (C=C-H), 3054 (C=C-H), 2950 (CH2), 2853

(C-H), 1595, 1541(C=C, Aromatic), 1489(N=N), 1330 (C-H, bend), 1157(C-O), 827 (C=C-H,

bend), 586 (Fe-N, str). Anal. Calcd. For C29H28 ClFeN5O11S; C, 46.70; H, 3.78; N, 9.39; S, 4.30;

Found: C, 46.61; H, 3.84; N, 9.30; S, 4.37.

204 C27H25CuN5O9S

Tan, λmax in nm (log ε): 509, 3315 (NH, str), 3127(C=C-H), 1623, 1587, 1541(C=C, Aromatic),

1459 (N=N), 1343 (C-H), 1200 (S=O),1174 (C-O), 884(C=C-H, bend), 530 (Cu-N). Anal. Calcd.

For C27H25CuN5O9S; C, 49.20; H, 3.82; N, 10.63; S, 4.86; Found: C, 49.11; H, 3.86; N, 10.54;

S, 4.89.

55

208 C27H24CuN6O11S

Violet, λmax in nm (log ε): 525, 3315(NH, str), 3123(C=C-H), 1541, 1489 (C=C, Aromatic),

1457(N=N), 1340 (C-H, bend), 1202 (S=O),1159 (C-O), 918,827,741 (C=C-H, bend), 536 (Cu-

N). Anal. Calcd. For C27H24CuN6O11S; C, 46.06; H, 3.44; N, 11.94; S, 4.55; Found: C, 45.90;

H, 3.50; N, 11.81; S, 4.65.

212 C27H24ClCuN5O9S

Violet, λmax in nm (log ε): 524, 3313(NH, str), 3052(C=C-H), 2927 (C-H, str), 1654, 1555, 1541

(C=C, Aromatic), 1449 (N=N), 1332(C-H, bend), 1118(C-O), 997,834,732 (C=C-H, bend), 529

(Cu-N). Anal. Calcd. For C27H24ClCuN5O9S; C, 46.76; H, 3.49; N, 10.10; S, 4.62; Found: C,

46.65; H, 3.54; N, 10.01; S, 4.68.

216 C28H27CuN5O9S

Dark Brown, λmax in nm (log ε): 525, 3380 (NH, str), 2924(C-H, str), 1597, 1526(C=C), 1425

(N=N), 1340(C-H, bend), 1157(C-O), 1120(C-O), 834,788,741(C=C-H, bend), 526 (Cu-N).

Anal. Calcd. For C28H27CuN5O9S; C, 49.96; H, 4.04; N, 10.40; S, 4.76; Found: C, 49.88; H,

4.09; N, 10.32; S, 4.85.

220 C29H29CuN5O10S

Tan, λmax in nm (log ε): 510, 3423 (OH, str), 3315 (N-H), 3054 (C=C-H), 2981 (C-H), 1533,

1490 (C=C, Aromatic), 1431(N=N), 1338 (C-H, bend),1157 (C-O) , 833, 788, 730 (C=C-H,

bend), 533 (Cu-N). Anal. Calcd. For C29H29CuN5O10S; C, 49.53; H, 4.16; N, 9.96; S, 4.56.

Found: C, 49.47; H, 4.22; N, 9.81; S, 4.61.

228 C29H28 ClCuN5O11S

Dark Brown, λmax in nm (log ε): 509, 3319 (N-H), 3087(C=C-H), 1597, 1522 (C=C, Aromatic),

1429 (N=N), 1340 (C-H, bend), 1157(C-O), 889,734 (C=C-H, bend), 525 (Cu-N). Anal. Calcd.

For C, 46.22; H, 3.75; N, 9.29; S, 4.25; Found: C, 46.10; H, 3.78; N, 9.20; S, 4.30.

202 C54H38CrN10O12S2

Pink, λmax in nm (log ε): 511, 3311(N-H), 3088 (C=C-H), 1595, 1524 (C=C, Aromatic), 1423

(N=N), 1317 (C-H, bend), 1209 (S=O), 1148 (C-O), 998, 732 (C=C-H, bend), 618 (Cr-N). Anal.

Calcd. For C54H38CrN10O12S2; C, 57.14; H, 3.37; N, 12.34; S, 5.65; Found: C, 57.10; H, 3.40;

N, 12.26; S, 5.71.

56

206 C54H36CrN12O16S2

Violet Brown, λmax in nm (log ε): 522, 3305 (N-H), 3084(C=C-H), 2955 (C-H), 1599, 1522

(C=C, Aromatic), 1429 (N=N), 1340 (C-H, bend), 1123(C-O), 831,734 (C=C-H, bend), 629 (Cr-

N). Anal. Calcd. For C54H36CrN12O16S2; C, 52.94; H, 2.96; N, 13.72; O, 20.90; S, 5.23; Found:

C, 52.83; H, 3.04; N, 13.60; S, 5.26.

210 C54H36 Cl2CrN10O12S2

Violet, λmax in nm (log ε): 524, 3309(N-H), 3087 (C=C-H), 1593, 1527 (C=C, Aromatic), 1434

(N=N), 1345 (C-H, bend), 1152 (C-O), 889, 734 (C=C-H, bend), 626 (Cr-N). Anal. Calcd. For

C54H36 Cl2CrN10O12S2; C, 53.87; H, 3.01; N, 11.63; S, 5.33; Found: C, 53.80; H, 3.14; N, 11.40;

S, 5.41.

214 C56H42CrN10O12S2

Dark Brown, λmax in nm (log ε): 522, 3313 (NH, str), 3047 (C=C-H), 2931 (C-H, str), 1650,

1565, 1544 (C=C, Aromatic), 1443 (N=N), 1332 (C-H, bend), 1118(C-O), 997, 834, 732 (C=C-

H, bend), 631(Cr-N). Anal. Calcd. For C56H42CrN10O12S2; C, 57.83; H, 3.64; N, 12.04; S, 5.51;

Found: C, 57.65; H, 3.76; N, 11.93; S, 5.56.

218 C58H46CrN10O14S2

Light pink, λmax in nm (log ε): 510, 3293 (NH, str), 3168 (C=C-H), 3051 (C=C-H), 2954 (CH2),

2863 (C-H), 1590, 1531(C=C, Aromatic), 1439 (N=N), 1337 (C-H, bend), 1148 (C-O), 828

(C=C-H, bend), 621(Cr-N). Anal. Calcd. For C58H46CrN10O14S2; C, 56.95; H, 3.79; N, 11.45; S,

5.24; Found: C, 56.80; H, 3.85; N, 11.10; S, 5.35.

226 C58H44Cl2CrN10O16S2

Dark Brown, λmax in nm (log ε): 510, 3299(NH, str), 3058(C=C-H), 1590, 1547 (C=C aromatic),

1444(N=N), 1340 (C-H), 1220 (S=O), 1162 (C-O), 868, 708, 683 (C=C-H, bend), 616(Cr-N).

Anal. Calcd. For C58H44Cl2CrN10O16S2; C, 52.61; H, 3.35; N, 10.58; S, 4.84; Found: C, 52.30; H,

3.41; N, 10.18; S, 4.88.

57

3.5 General Scheme-2 for the Synthesis of Pyrazolone Series of Dyes


1-(p-sulphophenyl-3-methyl-5-pyrazolone (1) (25.4 g, 0.1 mol) was suspended in H2O (250 mL).

Hydrochloric acid (45 mL) was added to this well stirred suspension. The reaction mixture was

cooled to 0-5°C in an ice bath. A solution of NaNO2 (6.9 g, 0.1 mol) in H2O (25 mL) previously

cooled to 0°C, was then added over a period of 35 minutes with stirring. The stirring was

continued for an hour maintaining the same temperature, with a positive test for nitrous acid.


Nitroso (Oxime) was filtered after salting out. The nitroso was reduced by stirring in 200mL

water containing 85mL HCl and 23g Zinc metal at boil for 4h. At the completion of reaction, pH

of the reaction was reduced to zero with conc.HCl, and precipitated the 1(p-sulphophenyl) -3-

methyl-4-amino pyrazolone was processed further for diazotization.

3.5.2 Diazotization and Coupling with Pyrazolones:

To a well stirred ice jacketed aqueous suspention of 3.05g 1-(p-sulfophenyl)-3-methyl-4-amino -

5-pyrazolone hydrochloride at 0-5 oC, was added 0.7g sodium nitrite and 3.5 mL Conc.HCl. The

reaction mixture was vigorously stirred for 4h at the above temperature to achieve the requisite

diazonium salt.

For the synthesis of dye from diazonium compound of 1-(p-sulfophenyl)-3-methyl-4-amino-5-

pyrazolones, it was coupled at 15-25 oC with 0.010 mol (1.74g) 1-phenyl-3-methyl-5-

pyrazolone (2a) aqueous solution (200mL) containing 0.45g NaOH. The coupling was facilitated

using sodium carbonate as acid binding agent. The reaction mixture was given 4.5h to complete

the coupling at 0-5o

C. The dye was brought to room temperature; pH was reduced upto 4.5 by

HCl, filtered and dried in oven at 70-75o

C till constant weight was obtained with percentage

yield of 87%. By adopting the same procedure other dyes 3b-g were prepared from couplers 2b-g

(scheme 1, scheme 2).

58

3.5.3 Metallization of Pyrazolone Acid Dyes

For the synthesis of metal complex (Chromium complex), pH of 12.5mL of dye 3a was reduced

to 6.5 with HCl. Then it was heated to 100oC and to it 2.5mL solution of Chromium triacetate

containing 0.00125mol Cr+3

was added drop wise. Mixing and heating at this temperature was

continued for further 1.0 hour till the metallization was completed as shown by the comparative

TLC. The dye was cooled to room temperature; its pH was reduced to 1.0 with conc. HCl. The

dye was salted out with sodium chloride which was subsequently filtered and dried in oven at 80

oC till constant weight.

Similarly Iron (II) and Copper (II) complexes of dye 3a were prepared by treating them with

FeSO4.7H2O and CuSO4.5H2O at temperature 55-70 oC with mole ratio 1:1 (Iron and Copper

complexes). In this way complexes 5a-g, 6a-g and 7a-g were synthesized from respective dye

ligands.

229 (C20H18N6O8S2)

Orange, (82%). λmax in nm (log ε): 450. FTIR (KBr, cm-1

) νmax: 3473 (OH, NH), 3060 (C-H, str),

2932 (C-H. aliphatic), 1665, 1591, 1535 (C=C aromatic), 1469 (N=N, str), 1325(C-H, bend),

1159 (S=O str), 1070, C-O), 827 (C=C, bend). 1H-NMR (300 MHz, DMSO-d6) δ: 10.00 (s, 1H,

OH), 9.13 (s, 1H), 8.67 (s, 1H, OH), 7.98 (d, 1H), 7.90 (t, 1H), 7.84 (d, 2H), 7.73 (s, 1H, SO3H),

7.59 (d, 1H), 7.45 (s, 1H), 7.23 (d, 2H), 6.60 (s, 1H, SO3H), 2.64 (s, 3H), 2.60 (s, 3H). 13

C-NMR

(75 MHz, DMSO-d6) δ (ppm): 153.01, 145.60, 145.60, 142.86, 141.25, 137.98, 137.10, 130.32,


H, 3.39; N, 15.72; S, 12.00; Found: C, 44.86; H, 3.45; N, 15.47; S, 12.06.

233 C21H20N6O5S

Orange, (93%) λmax in nm (log ε): 450. FTIR (KBr, cm-1

) νmax: 3464 (OH, str), 3062 (C=C-H),

2924 (C-H, str, aliphatic), 1632, 1546 (C=C aromatic), 1447 (N=N, str), 1317 (C-H, bending),

1209 (S=O, str), 1050 (C-O), 875 (Ar-H). 1H-NMR (300 MHz, DMSO-d6 ) δ: 9.75 (s, 1H, OH),

9.66 (s, 1H, OH), 8.08 (d, 2H), 7.98 (d, 2H), 7.71 (d, 1H), 7.58 (s, 1H), 7.24 (t, 1H), 7.00 (d,

1H), 6.68 (s, 1H, SO3H), 2.65 (s, 6H), 2.35 (s, 3H). 13

C-NMR (75 MHz, DMSO-d6) δ (ppm):

153.01, 145.60, 145.60, 141.25, 139.18, 138.29, 137.10, 129.82, 128.63, 125.56, 120.90, 119.17,

118.63, 118.24, 21.21, 13.47. Anal. Calcd. For C21H20N6O5S: C, 53.84; H, 4.30; N, 17.94; O,

17.08; S, 6.84, Found: C, 53.55; H, 4.38; N, 17.70.

59

237 C20H18N6O5S

Reddish Orange, (87%) λmax in nm (log ε): 438. FTIR (KBr, cm-1

) νmax: 3460 (OH, str), 3055

(C=C-H), 2924 (CH2), 1619, 1559 (C=C aromatic), 1448 (N=N, str), 1343(CH2), 1209 (S=O,

str), 1174(C-O), 872 (Ar-H). 1H NMR (300 MHz, DMSO-d6) δ: 9.70 (s, 1H, OH), 8.60 (s, 1H,

OH), 8.01 (d, 2H), 7.60 (d, 2H), 7.33 – 7.28 (m, 5H), 7.17 (s, 1H), 6.67 (s, 1H, SO3H), 2.60 (s,

6H).13

C NMR (75 MHz, DMSO-d6) δ: 153.01, 145.60, 141.25, 138.12, 137.10, 131.28, 129.55,

126.41, 125.56, 122.03, 118.34, 13.19. Anal. Calcd. For C20H18N6O5S: C, 52.86; H, 3.99; N,

18.49; O, 17.60; S, 7.05, Found: C, 52.42; H, 3.95; N, 18.30; S, 7.100.

241 (C20H18N6O8S2)

Tan, (93%) λmax in nm (log ε): 454. FTIR (KBr, cm-1

) νmax: 3468 (OH, str), 3055 (C=C-H), 2926

(C-H, aliphatic), 1629, 1543 (C=C aromatic), 1465 (N=N), 1343(C-H, bend), 1159 (S=O), 883

(Ar-H). 1H-NMR (300 MHz, DMSO-d6) δ: 9.70(s, 2H, OH), 7.90 (d, 4H), 7.65 (d, 4H), 6.69 (s,

1H, SO3H), 2.68 (s, 6H). 13

C-NMR (75 MHz, DMSO-d6) δ (ppm): δ 153.01, 153.01, 145.60,

145.60, 141.25, 137.10, 125.56, 118.81, 118.22, 13.65. Anal. Calcd. For C20H18N6O8S2: C,

44.94; H, 3.39; N, 15.72; S, 12.00, Found: C, 44.85; H, 3.43; N, 15.45; S, 12.09.

245 (C20H17ClN6O5S)

Reddish Orange, (83%). λmax in nm (log ε): 434. FTIR (KBr, cm-1

) νmax: 3476 (OH, str), 3059 (C-

H, str), 2936 (C-H. aliphatic), 1642, 1563 (C=C aromatic), 1441 (N=N, str), 1328 (C-H, bend),

1265 (S=O str), 1050 (C-O), 880 (C=C, bend), 780 (C-Cl). 1H-NMR (300 MHz, DMSO-d6) δ:

9.66 (s, 2H), 9.60 (s, 1H, OH), 8.08 (d, 2H), 7.93 (d, 2H), 7.78 (d, 2H), 7.37 (d, 2H), 6.65 (s, 1H,

SO3H), 2.61 (s, 6H). 13

C-NMR (75 MHz, DMSO-d6) δ (ppm): 153.01, 145.60, 141.25, 137.10,

136.87, 132.39, 129.30, 125.56, 123.55, 118.76, 118.10, 13.67. Anal. Calcd. For

C20H17ClN6O5S: C, 49.13; H, 3.50; Cl, 7.25; N, 17.19; S, 6.56; Found: C, 48.95; H, 3.42; Cl,

7.16; N, 17.10; S, 6.67;

249 (C20H16Cl2N6O8S2)


) νmax: 3474 (OH, str), 3050 (C-H, str),

2924 (C-H. aliphatic), 1660, 1538 (C=C aromatic), 1445 (N=N, str), 1328 (C-H, bend), 1272

(S=O str), 1040 (C-O), 865 (C=C, bend), 783 (C-Cl). 1H-NMR (300 MHz, DMSO-d6) δ: 9.72 (s,

1H, OH), 9.57 (s, 1H, OH), 8.17 (d, 2H), 8.15 (d, 2H), 7.81 (d, 1H), 7.68 (s, 1H, SO3H), 7.35 (d,

1H), 6.69 (s, 1H, SO3H), 2.60 (m, 6H). 13C-NMR (75 MHz, DMSO-d6) δ (ppm): δ 153.01,

150.76, 145.60, 143.96, 141.25, 138.89, 138.10, 137.10, 134.81, 130.76, 129.92, 125.56, 121.76,

60

119.10, 118.45, 118.15, 13.53. Anal. Calcd. For C20H16Cl2N6O8S2: C, 39.81; H, 2.67; Cl, 11.75;

N, 13.93; S, 10.63; Found: C, 39.70 H, 2.63; Cl, 11.68; N, 13.75; S, 10.72.

253 (C20H16N6O10S2)


) νmax: 3565, 3485 (COOH, OH, str),

3058 (C-H, str), 2930 (C-H, aliphatic), 1657, 1547 (C=C aromatic), 1447 (N=N, str), 1325(C-H,

bend), 1264 (S=O str), 1035 (C-O), 853 (C=C, bend). 1H-NMR (300 MHz, DMSO-d6) δ: 12.18

(s, 1H, COOH), 10.30 (s, 1H, OH), 7.89 (d, 2H), 7.71-7.76 (m, 4H), 7.68 (d, 1H), 5.95 (s, 1H),

2.29 (s, 3H).13

C-NMR (75 MHz, DMSO-d6) δ (ppm) : 163.73, 163.36, 154.02, 146.80, 144.76,

143.54, 138.65, 126.88, 126.78, 122.42, 121.55, 121.48, 117.06, 89.85, 12.25. Anal. Calcd. For

C20H16N6O10S2: C, 42.55; H, 2.86; N, 14.89; S, 11.36; Found: C, 42.30; H, 2.80; N, 14.73; S,

11.43.

231- C20H22FeN6O11S2

Brown, λmax in nm (log ε): 480, 3274.5 (NH, str), 3021(C=C-H), 2922(CH2), 2851, 1593, 1541,

1489 (C=C aromatic), 1438 (N=N), 1382 (C-H, bend), 1309 (S=O), 1151 (C-O), 915(C=C-H,

bend), 590 (Fe-N, str). Anal. Calcd. For C20H22FeN6O11S2; C, 49.78; H, 3.87; N, 10.75; S, 4.92.

Found: C, 49.67; H, 3.93; N, 10.70; S, 4.98

235- C20H20FeN6O13S2

Dark Brown, λmax in nm (log ε): 475, 3274(NH, str), 3021(C=C-H), 2922(CH2), 2851, 1593,

1541, 1489 (C=C aromatic), 1436(N=N), 1382 (C-H, bend), 1151 (C-O), 827 (C=C-H, bend),

743(C=C-H, bend), 585 (Fe-N, str). Anal. Calcd. For C27H24FeN6O11S; C, 46.57; H, 3.47; Fe,

8.02; N, 12.07; S, 4.60. Found: C, 46.51; H, 3.50; N, 12.00; S, 4.68.

239 C20H22FeN6O8S

Dark Brown, λmax in nm (log ε): 493, 3289 (NH, str), 3050(C=C-H), 1689 (C=O), 1559(C=C

aromatic), 1448(N=N), 1343 (C-H), 1209 (S=O), 1174 (C-O), 887, 870, 708 (C=C-H, bend), 589

(Fe-N, str). Anal. Calcd. For C20H22FeN6O8S; C, 47.28; H, 3.53; Fe, 8.14; N, 10.21; S, 4.67. ;

Found: C, 47.36; H, 3.59; Fe, 8.10; N, 10.16; S, 4.70.

243 C21H24FeN6O8S

Brown, λmax in nm (log ε): 480, 3296(NH, str), 3050(C=C-H), 1593, 1559(C=C aromatic),

1448(N=N), 1343 (C-H), 1209 (S=O), 1174 (C-O), 870, 708, 687 (C=C-H, bend), 578 (Fe-N,

str). Anal. Calcd. For C21H24FeN6O8S; C, 50.54; H, 4.09; N, 10.52; S, 4.82; Found: C, 50.50; H,

4.19; Fe, 8.30; N, 10.43; S, 4.86.

61

247 C20H22FeN6O11S2

Brown, λmax in nm (log ε): 479, 3296 (N-H, str), 3052(C=C-H), 1619, 1559 (C=C aromatic),

1448 (N=N), 1343 (C-H), 1209 (S=O), 1174 (C-O), 870,739,708,687(C=C-H, bend), 583 (Fe-N,

str). Anal. Calcd. For C20H22FeN6O11S2 ; C, 50.08; H, 4.20; N, 10.07; S, 4.61; Found: C, 50.00;

H, 4.28; N, 10.00; S, 4.67

251 C20H21ClFeN6O8S

Grey, λmax in nm (log ε): 482, 3276 (NH, str), 3170 (C=C-H), 3054 (C=C-H), 2950 (CH2), 2853

(C-H), 1595, 1541(C=C, Aromatic), 1489 (N=N), 1330 (C-H, bend), 1157(C-O), 827 (C=C-H,

bend), 586 (Fe-N, str). Anal. Calcd. For C20H21ClFeN6O8S; C, 46.70; H, 3.78; N, 9.39; S, 4.30;

Found: C, 46.61; H, 3.84; N, 9.30; S, 4.37.

232 C20H18CuN6O9S2

Tan, λmax in nm (log ε): 509, 3315 (NH, str), 3127(C=C-H), 1623, 1587, 1541(C=C, Aromatic),

1459 (N=N), 1343 (C-H), 1200 (S=O),1174 (C-O), 884(C=C-H, bend), 530 (Cu-N). Anal. Calcd.

For C20H18CuN6O9S2; C, 49.20; H, 3.82; N, 10.63; S, 4.86; Found: C, 49.11; H, 3.86; N, 10.54;

S, 4.89.

236 C20H16CuN6O11S2

Violet, λmax in nm (log ε): 525, 3315(NH, str), 3123(C=C-H), 1541, 1489 (C=C, Aromatic),

1457(N=N), 1340 (C-H, bend), 1202 (S=O),1159 (C-O), 918,827,741 (C=C-H, bend), 536 (Cu-

N). Anal. Calcd. For C20H16CuN6O11S2; C, 46.06; H, 3.44; N, 11.94; S, 4.55; Found: C, 45.90;

H, 3.50; N, 11.81; S, 4.65.

240 C20H18CuN6O6S

Violet, λmax in nm (log ε): 524, 3313(NH, str), 3052(C=C-H), 2927 (C-H, str), 1654, 1555, 1541

(C=C, Aromatic), 1449 (N=N), 1332(C-H, bend), 1118(C-O), 997,834,732 (C=C-H, bend), 529

(Cu-N). Anal. Calcd. For C20H18CuN6O6S; C, 46.76; H, 3.49; N, 10.10; S, 4.62; Found: C,

46.65; H, 3.54; N, 10.01; S, 4.68.

244 C21H20CuN6O6S

Dark Brown, λmax in nm (log ε): 525, 3380 (NH, str), 2924(C-H, str), 1597, 1526(C=C), 1425

(N=N), 1340(C-H, bend), 1157(C-O), 1120(C-O), 834,788,741(C=C-H, bend), 526 (Cu-N).

Anal. Calcd. For C21H20CuN6O6S; C, 49.96; H, 4.04; N, 10.40; S, 4.76; Found: C, 49.88; H,

4.09; N, 10.32; S, 4.85.

62

248 C20H18CuN6O9S2

Tan, λmax in nm (log ε): 510, 3423 (OH, str), 3315 (N-H), 3054 (C=C-H), 2981 (C-H), 1533,

1490 (C=C, Aromatic), 1431(N=N), 1338 (C-H, bend),1157 (C-O) , 833, 788, 730 (C=C-H,

bend), 533 (Cu-N). Anal. Calcd. For C20H18CuN6O9S2; C, 49.53; H, 4.16; N, 9.96; S, 4.56.

Found: C, 49.47; H, 4.22; N, 9.81; S, 4.61.

252 C20H17ClCuN6O6S

Dark Brown, λmax in nm (log ε): 509, 3319 (N-H), 3087(C=C-H), 1597, 1522 (C=C, Aromatic),

1429 (N=N), 1340 (C-H, bend), 1157(C-O), 889,734 (C=C-H, bend), 525 (Cu-N). Anal. Calcd.

For C20H17ClCuN6O6S C, 46.22; H, 3.75; N, 9.29; S, 4.25; Found: C, 46.10; H, 3.78; N, 9.20; S,

4.30.

230 C40H32CrN12O16S4

Pink, λmax in nm (log ε): 511, 3311(N-H), 3088 (C=C-H), 1595, 1524 (C=C, Aromatic), 1423

(N=N), 1317 (C-H, bend), 1209 (S=O), 1148 (C-O), 998, 732 (C=C-H, bend), 618 (Cr-N). Anal.

Calcd. For C40H32CrN12O16S4; C, 57.14; H, 3.37; N, 12.34; S, 5.65; Found: C, 57.10; H, 3.40;

N, 12.26; S, 5.71.

234 C40H29CrN12O20S4

Violet Brown, λmax in nm (log ε): 522, 3305 (N-H), 3084(C=C-H), 2955 (C-H), 1599, 1522

(C=C, Aromatic), 1429 (N=N), 1340 (C-H, bend), 1123(C-O), 831,734 (C=C-H, bend), 629 (Cr-

N). Anal. Calcd. For C40H29CrN12O20S4; C, 52.94; H, 2.96; N, 13.72; O, 20.90; S, 5.23; Found:

C, 52.83; H, 3.04; N, 13.60; S, 5.26.

238 C40H33CrN12O10S2

Violet, λmax in nm (log ε): 524, 3309(N-H), 3087 (C=C-H), 1593, 1527 (C=C, Aromatic), 1434

(N=N), 1345 (C-H, bend), 1152 (C-O), 889, 734 (C=C-H, bend), 626 (Cr-N). Anal. Calcd. For

C40H33CrN12O10S2; C, 53.87; H, 3.01; N, 11.63; S, 5.33; Found: C, 53.80; H, 3.14; N, 11.40; S,

5.41.

242 C42H37CrN12O10S2

Dark Brown, λmax in nm (log ε): 522, 3313 (NH, str), 3047 (C=C-H), 2931 (C-H, str), 1650,

1565, 1544 (C=C, Aromatic), 1443 (N=N), 1332 (C-H, bend), 1118(C-O), 997, 834, 732 (C=C-

H, bend), 631(Cr-N). Anal. Calcd. For C42H37CrN12O10S2; C, 57.83; H, 3.64; N, 12.04; S, 5.51;

Found: C, 57.65; H, 3.76; N, 11.93; S, 5.56.

63

246- C40H33CrN12O16S4

Light pink, λmax in nm (log ε): 510, 3293 (NH, str), 3168 (C=C-H), 3051 (C=C-H), 2954 (CH2),

2863 (C-H), 1590, 1531(C=C, Aromatic), 1439 (N=N), 1337 (C-H, bend), 1148 (C-O), 828

(C=C-H, bend), 621(Cr-N). Anal. Calcd. For C40H33CrN12O16S4; C, 56.95; H, 3.79; N, 11.45; S,

5.24; Found: C, 56.80; H, 3.85; N, 11.10; S, 5.35.

250 C40H31Cl2CrN12O10S2

Dark Brown, λmax in nm (log ε): 510, 3299(NH, str), 3058(C=C-H), 1590, 1547 (C=C aromatic),

1444(N=N), 1340 (C-H), 1220 (S=O), 1162 (C-O), 868, 708, 683 (C=C-H, bend), 616(Cr-N).

Anal. Calcd. For C40H31Cl2CrN12O10S2; C, 52.61; H, 3.35; N, 10.58; S, 4.84; Found: C, 52.30; H,

3.41; N, 10.18; S, 4.88.

3.6 General Scheme-3 for the Synthesis of Naphthol Series of Dyes

In this series of dyes, 20 dyes were synthesized from five different naphthols.The naphthols were

β-naphthol, Schaeffer’s acid, R-acid, H-acid and N-phenyl-J-acid. Four dyes were prepared with

each naphthol. The first dye was un-metalized one, while other three were chromium, iron and

copper complexes respectively. The chromium complexes were of 2:1 type. The detail of

metallization for naphthol dyes synthesis is given in General Scheme-3.

OH2OH2

H2O

HO3S

N

N

CH3

O

N N

M O R3

R1

R2

R1=R2=R3=H, Dye=257,

R1=R3=H, R2=SO3H, Dye=261

R1=H, R2=R3=SO3H, Dye=265

R1=NH2, R2=R3=SO3H, Dye=269

R1=H, R3=SO3H, R2=NHC6H5, Dye=273,

M= Fe+2,259, 263, 267, 271, 275

M=Cu+2, 260, 264, 268, 272, 276

HO3S

N

N

CH3

OH

N N

HO R3

R1

R2

NN

CH3

O

HO3SN N

O

NN

CH3

O

HO3SN N

OCr-

R2

R2

R3

R3

R1

R1

M= Cr+3, 258, 262, 266, 270, 274

General Scheme-3; The synthesis of naphthol series of dyes (metallization step only).

64


SPMP [1(4-sulphophenyl)3-methyl-2-pyrazoline-5- one] (25.4g, 0.1 mole) was taken in 250mL

H2O. Hydrochloric acid (45 mL) was added to this well stirred suspension. The reaction mixture

was cooled to 0°C in an ice bath. A solution of NaNO2 (6.9g, 0.1mol) in 25mL water, previously

cooled to 0°C, was then added over a period of 35 minutes with stirring. Mixing was continued

for one hour at the same temperature, keeping an excess of nitrous acid. Later on the excess of

nitrous acid was destroyed with the requisite amount of sulphamic acid. The Nitroso (Oxime)

was salted out with 15% salt and filtered.

3.6.2 Reduction

The Nitroso (Oxime) derivative was reduced in 200mL water containing 85mL HCl and 23g

Zinc metal at the boil (103-105°C) to form SPMP amine hydrochloride.

3.6.3 Diazotization

SPMP amine hydrochloride was diazotized by adding an aqueous solution of NaNO2 (6.9g

dissolved in 250mL of water) at -5 to -2°C.The nitrous acid formed in situ converted the SPMP

amine hydrochloride to the diazonium compound.

3.6.4 Coupling

The diazonium salt formed above was coupled with a cold solution of β-naphthol (14.4g=0.1mol

previously dissolved in 200mL boiling water containing 4.5g=0.1125mol NaOH). The coupling

of β-naphthol with the diazonium compound was done at 15-20°C using NaOH as an acid

binding agent. H-acid was used as an external indicator to check the completion of coupling

reaction. By adopting the same procedure other dyes (3b-g) were prepared from couplers

(Schaeffer’s Acid, R-acid, H-acid and N-phenyl J-acid) (General Reaction Scheme-3 above).

3.6.5 Metallization of naphthol acid dyes

For the preparation of metal complex dye (chromium based complex), the pH of 125mL of dye

1a was lowered to 6.5 with HCl (37%) and heated to 100°C. 2.5mL solution of chromium

triacetate (0.00125mol Cr3+

) was added slowly drop-wise. Mixing with heating at 100°C was

continued for 1.0 hour till metallization was completed as confirmed by comparative TLC. The

dye solution was cooled to 30°C; its pH was lowered to 1.0 with HCl (37%). The dye was

separated by salting out with sodium chloride, filtered and oven dried at 80°C to constant weight.

Similarly iron (II) and copper (II) metal complexes of dye 3a were synthesized by treating them

with appropriate solutions of FeSO4.7H2O and CuSO4.5H2O at 55-70°C with a mole ratio 1:1

65

1:1(iron and copper complexes). In this way complexes 1b-d, 2b-d, 3b-d, 4b-d and 5a-d were

prepared from the respective dye ligands. Four dye samples were prepared with each coupler.

The first being an un-metallized dye and the other three being chromium, iron and copper

complexes respectively. The chromium complexes were of the 2:1 type. In case of chromium,

three water molecules are replaced with one molecule of the same dye to form a 2:1 metal

complex.

257 C20H16N4O5S


) νmax: 3429 (H2O, OH str.), 3336(NH

str.), 3050(C=C-H str.), 1597(C=C aromatic), 1431(N=N str.), 1243(CH2str.), 1170(C-O str.),

1008(S=O), 836(Ar-H).

258 C40H29CrN8O10S2


) νmax: 3430(H2O, OH str.), 3220(NH

str.), 3050 (C=C-H str.), 2924 (CH2 str.), 1675(C=O str.), 1589 (C=C aromatic), 1500 (N=N

str.), 1418 (C-H bend.), 1369 (CH2 str.), 1123 (C-O str.), 1004(S=O), 812(Ar-H).

259 C20H20FeN4O8S


) νmax: 3350 (H2O, OH str.), 3235 (NH

str.), 3052 (C=C-H str.), 1619, 1559 (C=C aromatic, C=N, N=N str.), 1431 (CH. bend.), 1121

(C-O str.), 1004 (S=O), 738(Ar-H).

260 C20H20CuN4O8S


) νmax: 3397 (H2O, OH, NH str.), 3050

(C=C-H str.), 2924 (CH2 str.), 1619, 1559 (C=C aromatic), 1435 (N=N str.), 1367 (CH2str.),

1123 (C-O str.) 1006 (S=O), 814(Ar-H).

261-C20H16N4O8S2

3431(H2O, OH, NH str.), 2931(CH2 str.), 1597 (C=C aromatic, C=N, N=N str.), 1179 (C-O-C

str.), 1006 (S=O), 810(Ar-H).

262 C40H29CrN8O16S4


) νmax: 3337(H2O, OH, NH str.), 2924

(CH2 str.), 1616, 1578(C=C aromatic, N=N str.), 1399 (O H bend.), 1036 (S=O), 810(Ar-H).

66

263 C20H20FeN4O11S2


) νmax: 3400 (H2O, OH str.), 3172 (NH

str.), 1619, 1557 (C=C aromatic, C=N, N=N str.), 1157 (C-O str.), 1036 (S=O), 872 (Ar-H).

264 C20H20CuN4O11S2


) νmax: 3283(H2O, OH, NH str.), 1597

(C=C aromatic), 1496 (N=N str.), 1062 (S=O), 1164 (C-O str.), 882 (Ar-H).

265 C20H16N4O11S3


) νmax: 3391 (H2O, OH, NH str.), 3015

(C=C-H str.), 1619, 1552 (C=C aromatic, C=N), 1498 (N=N str.), 1125 (C-O str.), 1004 (S=O),

827(Ar-H).

266 C40H29CrN8 O22S6


) νmax: 3328 (H2O, OH, NH str.), 2922

(CH2 str.), 1590(C=C aromatic, C=N, N=N str.), 1399 (OH bend.), 1179 (C-O str.), 1006 (S=O),

838(Ar-H).

267 C20H20FeN4O14S3


) νmax: 3399 (H2O, OH, NH str.),

2920(CH2 str.), 1619, 1559 (C=C aromatic, C=N), 1483(N=N str.), 1121 (C-O-C str.), 1004

(S=O), 829(Ar-H).

268 C20H20CuN4O14S3


) νmax: 3365(H2O, OH str.), 3202 (NH

str.), 3050 (C=C-H str.), 1619, 1559 (C=C aromatic, C=N,N=N str.), 1174 (C-O str.), 1034

(S=O), 872(Ar-H).

269 C20H17N5O11S3


) νmax: 3449(H2O, OH str.), 3298(NH

str.), 3049 (C=C-H str.), 2879(CH2 str.), 1619, 1595 (C=C aromatic, C=N), 1498 (N=N str.),

1174 (C-O str.), 1041 (S=O), 872(Ar-H).

67

270 C40H31CrN10O22S6



3071(C=C-H str.), 2881(CH2 str.), 1619, 1597(C=C aromatic, C=N), 1500 (N=N str.), 1369

(CH2 str.), 1166 (C-O str.), 1148 (C-C str.), 1041(S=O), 890 (Ar-H)

271 C20H21FeN5O14S3


) νmax: 3505 (H2O, OH str.), 3298(NH

str.), 3050 (C=C-H str.), 1619, 1559 (C=C aromatic, C=N, N=N str.), 1165 (C-O str.),

1038(S=O), 872 (Ar-H).

272 C20H21CuN5O14S3


) νmax: 3505 (H2O, OH str.), 3298(NH

str.),3050 (C=C-H str.), 2924 (CH2 str.), 1619, 1559 (C=C aromatic, C=N,N=N str.), 1166(C-O

str.), 1038 (S=O), 838 (Ar-H).

273 C26H21N5O8S2


) νmax: 3304 (H2O, OH str.), 3155 (NH

str.), 3050 (C=C-H str.), 2924 (CH2 str.), 1586 (C=C aromatic, C=N), 1495 (N=Nstr.), 1394

(CH2 str.), 1155 (C-O str.), 1036 (S=O), 898 (Ar-H).

274 C52H39CrN10O16S4


) νmax: 3586(H2O, OH, NH str.),

3050(C=C-H str.), 1619, 1578 (C=C aromatic, C=N), 1498 (N=N str.), 1399 (CH2str.), 1177(C-

O str.), 1041 (S=O), 881 (Ar-H).

275-C26H25FeN5O11S2


) νmax: 3363 (H2O, OH, NH str.), 2924

(CH2 str.), 1619, 1578 (C=C aromatic, C=N),1494(N=N str.), 1310 (CH2str.), 1176 (C-O str.),

1038(S=O), 834 (Ar-H).

276 C26H25CuN5O11S2



2924(CH2 str.), 1619, 1559 (C=C aromatic, C=N), 1492(N=N str), 1308(CH2str.), 1177 (C-O

str.), 1038 (S=O), 838 (Ar-H).

68

3.7 General Scheme-4; The Synthesis of p-substituted-Phenol, Resorcinol and Bisphenol

Dyes

Synthesis of these acid dyes and their metal complexes involved three step procedure including

synthesis of diazo of SPMP, its coupling with desired couplers and metallization which is as

follows:

General Scheme-4a; Synthesis of p-substituted-Phenol, Resorcinol and Bisphenol Dyes, their

Iron and Copper complexes (Metallization step only).

69

General Scheme-4b; Synthesis of p-substituted-Phenol, Resorcinol and Bisphenol Dyes and

their Chromium complexes (Metallization step only).


1-(p-sulphophenyl-3-methyl-5-pyrazolone (144) (25.4 g, 0.1 mol) was suspended in H2O (250

mL). Hydrochloric acid (45 mL) was added to this well stirred suspension. The reaction mixture

was cooled to 0-5°C in an ice bath. A solution of NaNO2 (6.9 g, 0.1 mol) in H2O (25 mL)

previously cooled to 0°C, was then added over a period of 35 minutes with stirring. The stirring

was continued for an hour maintaining the same temperature, with a positive test for nitrous acid.


Nitroso (Oxime) was filtered after salting out. Then oxime was reduced by stirring in 200mL

water containing 85mL HCl and 23g Zinc metal at boil for 4hours till the reaction mass was

colorless.

70

3.7.2 Diazotization of SPMP and Coupling with Phenol Derivatives

To the well stirred ice jacketed aqueous solution (2.69 g) of 1-(p-sulphophenyl-3-methyl-4-

amino pyrazolone (at 0-5 oC) was added Conc. HCl (3.5 mL) and sodium nitrite solution (0.7 g

in 2mL H2O). The reaction mixture was vigorously stirred for 1h at the above mentioned

temperature to obtain the diazonium salt of 1-(p-sulphophenyl)-3-methyl-4-amino pyrazolone.

The diazonium compound formed in this way was coupled to various coupler mentioned

previously to synthesize our dyes. Thus 1.285 g (0.010 mol) 4-Chlorophenol (5a) was dissolved

in 200 mL water containing 0.45 g NaOH and coupled with prepared diazo. The coupling was

facilitated using sodium carbonate as an acid binding agent. The reaction mixture was given 4-5

hour to complete the coupling at 30-35 oC. The dye was cooled to room temperature. Its pH was

reduced to 4.5 by HCl and filtered. The cake was dried in oven at 70-75 oC till constant weight.

By adopting the same procedure other dyes 6b-f were prepared from couplers 5b-f as shown in

(Scheme-4a and 4b).

3.7.3 Metallization of Phenolic Acid Dyes.

For the synthesis of metal complexes (Iron complex), pH of 25 mL (0.005mole) of dye 6a was

reduced to 6.5 with HCl. Then it was heated to 70oC and to it 5 mL (0.005 mole Fe

2+) solution of

ferrous sulfate (FeSO4.7H2O) was added drop wise. Mixing and heating at this temperature was

continued for further 1.0 hour till the metallization was completed, as shown by the comparative

TLC. The dye was cooled to room temperature; its pH was reduced to 1.0 with conc. HCl. Then

it was salted out with sodium chloride, filtered and dried in oven at 80 oC till constant weight.

Similarly copper (II) complexes of dye 6a were prepared by treating dye with CuSO4.5H2O at

65-70 oC with metal to ligand mole ratio 1:1. In this way complexes 7a-l were synthesized from

respective dye ligands.

277 (C16H13ClN4O5S)

Orange, (76%) λmax (nm): 460. FTIR (KBr, cm-1

) νmax: 3255 (OH str.), 3050 (C=C-H str.), 2927

(CH2 str.), 1653 (C=O str.), 1595, 1541 (C=C aromatic, C=N), 1498 (N=N str.),1422, 1340

(SO3H str., CH2 bend.), 1236, 1155 (C-C, C-O str.), 1000 (S=O str.), 833 (Ar-H), 790(C-Cl str.).

1HNMR (300 MHz, DMSO-d6) δ: 8.07 (1H, d J=2.35 Hz), 7.95 (2H, d J=8.6 Hz), 7.83-7.90 (1H,

71

m), 7.68 (2H, d J=8.6 Hz), 6.65 (1H, d, J=9.1 Hz), 2.20 (3H, s).13

C-NMR (75 MHz DMSO-d6) δ

(ppm) : 158.54, 156.64, 147.93, 147.37, 143.21, 139.93, 125.43, 124.41, 119.45, 118.06, 116.22

12.45. Anal. Calcd. For C16H13ClN4O5S: C, 47.01; H, 3.21; N, 13.71; S, 7.84 Found: C, 47.05;

H, 3.30; N, 13.59; S, 7.79.

281 (C16H13N5O7S)

Dark Brown, (83%). λmax (nm): 480. FTIR (KBr, cm-1

) νmax: 3388 (OH str.), 2924 (CH2 str.),

1666 (C=C str.), 1593 (C=C aromatic, C=C), 1498, 1476 (N=N, NO2str.), 1267, 1172 (C-O str.),

1034 (C-OC str.), 821 (Ar-H). 1HNMR (300 MHz, DMSO-d6) δ: 8.15 (1H, d J=2.4 Hz), 7.942

(2H, d J=8.7 Hz), 7.81-7.92 (1H, m), 7.65 (2H, d J=8.7 Hz), 6.38 (1H, d, J=9.3 Hz), 2.27 (3H,

s).13

C-NMR (75 MHz DMSO-d6) δ (ppm): 158.0, 155.28, 148.32, 147.57, 144.58, 138.72,

128.18 126.86, 126.24, 118.19, 117.06, 116.17, 12.14. Anal. Calcd. For C16H13N5O7S: C, 45.83;

H, 3.12; N, 16.70, S, 7.64; Found: C, 45.78; H, 3.20; N, 16.58, S, 7.57.

285 (C16H14N4O8S2)

Orange, (84%). λmax (nm): 460. FTIR (KBr, cm-1

) νmax: 3389 (OH str), 3086 (C=C-H str.), 1638

(N-H bend.), 1619, 1597 (C=C aromatic), 1541 (N=N str.), 1500 (N-H bend.), 1340 (SO3H, CH2

str.), 1185 (C-O str.), 818 (Ar-H). 1HNMR (300 MHz, DMSO-d6) δ: 11.87 (1H, s, O-H), 8.10

(1H, d J=2.6 Hz), 7.93 (2H, d J=8.6 Hz), 7.79-7.90 (1H, m), 7.67 (2H, d J=8.6 Hz), 6.90 (1H, s,

SO3H), 6.58 (1H, d, J=9.5 Hz), 2.27 (3H, s).13

C-NMR (75 MHz DMSO-d6) δ (ppm) : 159.12,

156.48, 147.72, 147.17, 145.23, 141.33, 138.62, 125.68, 124.42, 117.19, 116.96, 116.43 11.81.

Anal. Calcd. For C16H14N4O8S2: C, 42.29; H, 3.11; N, 12.33, S: 14.11 Found: C, 42.24; H, 3.20;

N, 12.21, S: 14.04.

289 (C16H13N5O10S2)


) νmax: 3449 (OH str.), 3050 (C=C-H str.), 1653

(C=C str. NH bend), 1619, 1541 (C=C aromatic), 1498 (N=N str.), 1338 (SO3H, CH2 str.), 1183

(C-O str.), 1008 (S=O), 840 (Ar-H). 1HNMR (300 MHz, DMSO-d6) δ: 11.33 (1H, s, O-H), 8.15

(1H, d J=2.4 Hz), 7.99 (1H, d J=2.4 Hz), 7.922 (2H, d J=8.7 Hz), 7.63 (2H, d J=8.7 Hz), 2.23

(3H, s).13

C-NMR (75 MHz DMSO-d6) δ (ppm) : 157.05, 156.28, 149.25, 147.63, 144.28, 142.76,

140.92, 127.16, 125.54, 119.19, 116.56, 115.20 12.14. Anal. Calcd. For C16H13N5O10S2: C,

38.48; H, 2.62; N, 14.02; S, 12.84; Found: C, 38.37; H, 2.69; N, 13.96; S, 12.88.

72

297 (C32H26N8O12S3)


) νmax: 3395 (, OH , NH str.), 3050 (C=C-H str.),

2926 (CH2 str.), 1619, 1586 (C=C aromatic, C=N), 1498 (N=N str.), 1125 (C-O str.), 1008

(S=O), 872 (Ar-H). 1HNMR (300 MHz, DMSO-d6) δ: 11.67 (1H, s, O-H), 7.91 (2H, d J=8.7

Hz), 7.81-7.92 (1H, m), 7.69 (2H, d J=8.7 Hz), 6.90 (1H, d, J=9.4 Hz), 6.78 (1H, s), 6.62 (1H, s,

SO3H), 6.59 (1H, d, J=9.4 Hz), 2.51(3H, s), 1.469 (6H, s).13

C-NMR (75 MHz, DMSO-d6) δ

(ppm) : 157.56, 154.89, 148.97, 154.64, 144.47, 143.44, 142.29, 141.31, 138.88, 137.90, 129.96,

128.05, 127.74, 126.78, 119.85, 118.63, 117.64, 115.79, 115.64, 115.13, 115.02, 41.19, 30.83,

11.59. Anal. Calcd. For C32H26N8O12S3: C, 47.40; H, 3.23; N, 13.82; S, 11.86; Found: C, 47.46;

H, 3.31; N, 13.56; S, 11.80.

301 (C35H32N8O10S2)

Brown, (83%). λmax (nm): 450. FTIR (KBr, cm-1

) νmax: 3464 (OH, NH str.), 2963 (CH2 str.),

1653, 1593 (C=C aromatic), 1490(N=N str.), 1338 (SO3H str.), 1213, 1153, 1120 (C-C str.),

1002 (S=O), 872 (Ar-H). 1H-NMR (300 MHz, DMSO-d6) δ: 11.30 (1H, s, O-H), 7.94 (2H, d

J=8.7 Hz), 7.82-7.93 (1H, m), 7.67 (2H, d J=8.7 Hz), 6.98 (1H, d, J=9.4 Hz), 6.81 (1H, s), 6.58

(1H, d, J=9.4 Hz), 6.42 (1H, s, SO3H), 2.47 (3H, s).13

C-NMR (75 MHz, DMSO-d6) δ (ppm) :

158.77, 155.9, 147.61, 145.61, 143.86, 143.25, 141.63, 139.81, 136.75, 130.25, 127.91, 125.78,

119.80, 118.31, 116.73, 115.94, 115.23, 11.59. Anal. Calcd. For C35H32N8O10S2: C, 53.29; H,

4.09; N, 14.21; S, 8.13; Found: C, 53.35; H, 4.13; N, 14.04; S, 8.20.

278- (C32H23Cl2CrN8O10S2)

Maroon/Yellowish Red, (66%) λmax (nm):464. FTIR (KBr, cm-1

) νmax: 3050 (C=C-H str.), 1642

(C=O str.), 1583, 1537 (C=C aromatic, C=N), 1485 (N=N str.), 1417, 1335 (SO3H str., CH2

bend.), 1226, 1145 (C-C, C-O str.), 1012 (S=O str.), 830 (Ar-H), 785(C-Cl str.). Anal. Calcd. For

C16H13ClN4O5S: C, 44.35; H, 2.68; N, 12.93; S, 7.40; Found: C, 44.43; H, 2.58; N, 12.83; S,

7.50.

279-C16H17ClFeN4O8S (7a)

3440 (OH str.), 3287 (NH str.), 3050 (C=C-H str.), 2924 (CH2 str.), 1653 (C=O str.), 1597, 1545

(C=C aromatic), 1466 (N=N str.), 1300 (N=O str.), 1418, 1334 (CH2str.), 1166 (C-O str.), 1004

73

(S=O), 833 (Ar-H) ,739 (C-Cl str.). Anal. Calcd. For C16H17ClFeN4O8S: C, 37.19; H, 3.32; N,

10.84; S, 6.20; Found: C, 37.13; H, 3.26; N, 10.70; S, 6.25.

280-C16H17ClCuN4O8S (7b)

3418 (OH str.), 3298 (NH str.), 3050 (C=C-H str.), 2928 (CH2 str.), 1653 (C=O str.), 1598, 1541

(C=C aromatic), 1466 (N=N str.), 1343 (CH2str.), 1172, 1125 (C-O str.), 812 (Ar-H),739 (C-Cl

str.). Anal. Calcd. For C16H17ClCuN4O8S: C, 36.65; H, 3.27; N, 10.68; S, 6.11; Found: C, 36.63;

H, 3.22; N, 10.60; S, 6.18.

282-(C32H23CrN10O14S2)

Reddish orange, (73%). λmax (nm):483. FTIR (KBr, cm-1

) νmax: 1676 (C=C str.), 1587 (C=C

aromatic, C=C), 1495, 1471 (N=N, NO2str.), 1267, 1172 (C-O str.), 1039 (C-OC str.), 829 (Ar-

H). Anal. Calcd. For C16H13N5O7S: C, 43.30; H, 2.61; N, 15.78; S, 7.22. Found: C, 43.20; H,

2.70; N, 15.89; S, 7.34.

283-C16H17FeN5O10S (7c)

3399 (NH str.), 3050 (C=C-H str.), 2926 (CH2 str.), 1550 (C=C aromatic), 1472 (N=N, NO2 str.),

1272, 1164 (C-O str.), 1004 (S=O), 834 (Ar-H). Anal. Calcd. For C16H17FeN5O10S C, 36.45; H,

3.25; N, 13.28; S, 6.08; Found: C, 36.48; H, 3.21; N, 13.19; S, 6.16.

284-C16H17CuN5O10S (7d)

3524 (OH str.), 3298 (NH str.), 3050 (C=C-H str.), 2924 (CH2 str.), 1619, 1584 (C=C aromatic,

C=N), 1474 (N=N), 1321 (NO2 bend.), 1284 (C-H bend.), 1123(C-O str.), 1004 (S=O), 840 (Ar-

H). Anal. Calcd. For C16H17CuN5O10S C, 35.92; H, 3.20; N, 13.09; S, 5.99; Found: C, 35.86; H,

3.14; N, 13.04; S, 6.10.

286- (C32H25CrN8O16S4)

Brown/Reddish orange, (74%). λmax (nm):489. FTIR (KBr, cm-1

) νmax: 3076 (C=C-H str.), 1623

(N-H bend.), 1621, 1599 (C=C aromatic), 1539 (N=N str.), 1498 (N-Hbend.), 1354 (SO3H, CH2

str.), 1174 (C-O str.), 814 (Ar-H). Anal. Calcd. For C16H14N4O8S2: C, 40.13; H, 2.63; N, 11.70;

S, 13.39; Found: C, 40.33; H, 2.54; N, 11.73; S, 13.41.

74

287-C16H18FeN4O11S2 (7e)

3383(NH str.), 3050 (C=C-H str.), 1638, 1568 (C=C str.), 1548 (NH bend.), 1474 (N=N str.),

1429 (CH bend), 1343 (CH2str.), 1276, 1162 (C-O str.), 1004 (S=O), 833 (Ar-H). Anal. Calcd.

For C16H18FeN4O11S2 C, 34.18; H, 3.23; N, 9.96; S, 11.40; Found: C, 34.14; H, 3.16; N, 9.86; S,

11.49.

288-C16H18CuN4O11S2 (7f)

3418 (OH), 1597 (C=C aromatic, C=N str.), 1528, 1474 (N=N str.), 1343 (CH2str.), 1272, 1209,

1174 (C-O str.), 1183(C-O str.), 1008 (S=O), 831(Ar-H). Anal. Calcd. For C16H18CuN4O11S2 :

C, 33.71; H, 3.18; N, 9.83; S, 11.25; Found: C, 33.75; H, 3.16; N, 9.77; S, 11.31.

290- (C32H23CrN10O20S4)

Brown/Reddish orange, (81%). λmax (nm):505. FTIR (KBr, cm-1

) νmax: 3056 (C=C-H str.), 1648

(C=C str. NH bend), 1622, 1539 (C=C aromatic), 1492 (N=N str.), 1343 (SO3H.), 1173 (C-O

str.), 1010 (S=O), 856 (Ar-H). Anal. Calcd. C32H23CrN10O20S4 C, 36.68; H, 2.21; N, 13.37; S,

12.24; Found: C, 36.73; H, 2.27; N, 13.39; S, 12.20.

291-C16H17FeN5O13S2 (7g)

3478 (OH str.), 3198 (NH str.), 3050 (C=C-H str.), 2928 (CH2 str.), 1619, 1586 (C=C aromatic,

C=N), 1541, 1436 (N=N str.), 1300 (N=O str.), 1343 (CH2str.), 1159(C-O str.), 1002(S=O), 833

(Ar-H). Anal. Calcd. For C16H17FeN5O13S2: C, 31.64; H, 2.82; N, 11.53; S, 10.56; Found: C,

31.60; H, 2.76; N, 11.44; S, 10.58.

292-C16H17CuN5O13S2 (7h)

3444 (OH), 3050 (C=C-H str.), 1600, 1559(C=C aromatic), 1489 (N=N str.), 1343 (CH2str.),

1179 (C-O str.), 1006 (S=O), 838 (Ar-H). Anal. Calcd. For C16H17CuN5O13S2: C, 31.25; H,

2.79; N, 11.39; S, 10.43; Found: C, 31.29; H, 2.74; N, 11.31; S, 10.50.

298 (C64H46Cr2N16O24S6)

Beige/Yellowish orange, (70%). λmax (nm):584. FTIR (KBr, cm-1

) νmax: 3048 (C=C-H str.), 1621,

1574 (C=C aromatic, C=N), 1496 (N=N str.), 1122 (C-O str.), 1011 (S=O), 869 (Ar-H). Anal.

75

Calcd. For C32H26N8O12S3:C, 47.48; H, 3.27; N, 13.86; S, 11.85; Found: C, 47.44; H, 3.33; N,

13.52; S, 11.81.

299-C32H34Fe2N8O18S3 (7i)

3184 (OH), 3050 (C=C-H str.), 2924 (CH2 str.), 1619, 1586 (C=C aromatic, C=N), 1498 (N=N

str.), 1006 (S=O), 829 (Ar-H). Anal. Calcd. For C32H34Fe2N8O18S3: C, 37.44; H, 3.34; N, 10.92;

S, 9.37; Found: C, 37.42; H, 3.30; N, 10.85; S, 9.42.

300-C32H34Cu2N8O18S3 (7j)

3352(OH str.), 3298 (NH str.), 3050 (C=C-H str.), 1559 (C=C aromatic, C=N), 1541 (N=N str.),

1205, 1103 (C-C str.), 997 (S=O), 836 (Ar-H). Anal. Calcd. For C32H34Cu2N8O18S3 : C, 36.89;

H, 3.29; N, 10.75; S, 9.23; Found: C, 36.85; H, 3.33; N, 10.66; S, 9.18.

302- (C70H58Cr2N16O20S4)

Tan/Reddish orange, (73%). λmax (nm):479. FTIR (KBr, cm-1

) νmax: 1645, 1589 (C=C aromatic),

1485(N=N str.), 1341 (SO3H str.), 1210, 1150, 1118 (C-C str.), 999 (S=O), 875 (Ar-H). Anal.

Calcd. For C35H32N8O10S2: C, 45.81; H, 3.02; N, 18.53; S, 12.34. Found: C, 45.85; H, 3.09; N,

18.56; S, 12.38.

303-C35H40Fe2N8O16S2 (7k)

3440 (OH str.), 3220 (NH str.), 2967 (C=C-H str, CH2 str.), 1675(C=Ostr.), 1653, 1593(C=C

aromatic), 1541, 1507 (N=N str.), 1340 (CH2), 1161 (C-O str.), 1004 (S=O), 829 (Ar-H). Anal.

Calcd. For C35H40Fe2N8O16S2: C, 41.85; H, 4.01; N, 11.15; S, 6.38; Found: C, 41.81; H, 4.00;

11.10; S, 6.44.

304-C35H40Fe2N8O16S2 (7l)

3440 (OH str.), 3231 (NH str.), 3050 (C=C-H str.), 2967 (CH2 str.), 1653 (C=Ostr.), 1541 (C=C

aromatic), 1498 (N=N str.), 1364, 1340 (SO3Hstr.), 1161 (C-O str.), 1004 (S=O), 829 (Ar-H).

Anal. Calcd. For C35H40Cu2N8O16S2 : C, 41.22; H, 3.95; N, 10.99; S, 6.29; Found: C, 41.19; H,

3.90; N, 10.92; S, 6.34.

76

Chapter 4 RESULTS AND DISCUSSION

4.1 Synthesis of 4-amino-1-(p-sulphophenyl)-3-methyl-5-pyrazolone and its diazonium Salt

Synthesis of diazonium salt of SPMP was achieved according to Scheme 4.1, which involve

nitrosation, reduction and diazotization in a stepwise manner as shown below.

NN

CH3

OH

SO3

- Na

+

NaNo2,HCl

-5 - 0 oC

NN

CH3

O

SO3

- Na

+

N OH

NN

CH3

O

SO3

- Na

+

NH3Cl-

NN

CH3

O-

SO3

- Na

+

N+

N

Zn + HCl

100 - 105 oC

NaNo2,HCl

-5 - 0 oC

(144) (145) (146) (147)

+

Scheme 4.1; Synthesis of 4-amino-1(p-sulphophenyl)-3-methyl-5-pyrazolone and its diazonium

salt.

4.2 Nitrosation, Reduction and Diazotization of SPMP

The initial step of the reaction series was nitrosation of SPMP [1(4-sulphohenyl)-3-methyl-5-

pyrazolone] (144). 1(4-sulphophenyl) 3-methyl-2-pyrazolin-5-one (SPMP) was nitrosated at 0-

5ºC using NaNO2 and HCl as described by Knorr1. The nitroso compound was filtered to remove

some terry material. The clarified nitroso derivative that usually exists in an oxime form (as

indicated by its FTIR), was salted out by common salt and dried after filtration. Reduction of

Nitrso/Oxime of SPMP was carried at 100-105ºC using Zinc and HCl. The oxime of SPMP and

zinc metal were added in small portions at boil. The reduction was completed as the solution

became colorless. A small amount of additional zinc was added and the resultant amine

hydrochloride was quenched to -7 ºC. The excessive un-reacted zinc was removed by filtration.

The amine hydrochloride of SPMP was diazotized using an aqueous solution of NaNO2 (6.9g

dissolved in 250mL of solution) and HCl at -5 to -2ºC to avoid the formation of rubazoic acid,

which is automatically formed during this reaction with increasing temperature due to oxidizing

action of nitrous acid formed in situ.

In the crystal structure of diazonium salt the phenyl as well as the pyrazolone-ring lie almost in

plane, the relevant torsion angle C1-N1-C5-C6 measures 3.3(5)°. Essential bonding parameters

of the pyrazolone moiety are N1-N2 1.407(3), C1-O1 1.230(3), C2-N3 1.325(4), N3-N4 1.110(3)

77

Å, and C2-N3-N4 177.3(3)°. These are in close agreement with those of 4-Diazonio-2-methyl-5-

nitro-3-oxo-2,3-dihydropyrazol-1-ide (WETGEJ)x1

with N-N 1.362, C-N2 1.323, (C)N-N 1.116

Å and C-N-N 177.7°. The crystal structure (Figure 2) shows various hydrogen bonding pattern

with the solvent water molecules. Strongest interactions are O10-H11…O11(-x+1, -y+1, -z+2)

with H…O of 1.939 Å, O20-H21…O12(x, y+1, z) with 1.979 Å, O10-H12…O12(x-1, y+1, z)

with 2.005 Å and O20-H22…N2 with 2.139 Å. An intramolecular C6-H…O1 bond is connected

with the planar arrangement of both the aromatic ring planes. The molecular structure of

diazonium salt is depicted in Figure 4.1; the unit cell with intermolecular H-bonding pattern is

shown in Figure 4.2.

Figure 4.1; ORTEP diagram of SPMP diazonium Salt.

78

Figure 4.2. Crystal packing with hydrogen bonding pattern as dotted lines.

The parent compound exists mainly as an enol form as indicated by its FTIR spectra (Figure-

4.3) (enolic OH = 3166cm-1

,C=C =1591cm-1

,S=O =1183cm-1

).while the nitroso derivative

existed in the form of a keto-oxime as indicated by it FTIR spectra (Figure-4.4) (appearance of a

C=O at 1716cm-1

,C=N at 1595cm-1

,S=O at 1194cm-1

). The oxime was in turn reduced to an

amine which was difficult to be isolated, hence the crude reaction product was diazotized to get

its diazonium salt which existed as an internal salt as indicated by its FTIR (Figure-4.5) (HOH

=3416cm-1

, N+

NAr-

at 2124cm-1

, C=C at 1595cm-1

,S=O at 1354cm-1

). The diazonium

oxide was isolated by salting out at 30% per volume and at 0-3oC after cooling for 18-20 hours.

The filtered diazonium compound (167) was yellow in color. It was dried in vacuum dessicator

at 25-30oC to get it in dry form for coupling with desired couplers. The yield of diazonium

compound was about 95% as found by its coupling with β-naphthol. The diazonium compound

was crystallized from ethanol and subjected to X-ray analysis. The physical data obtained from

X-ray analysis is presented in Tables 4.1 and 4.2.

79

Table-4.1; X-Ray Crystallographic data of SPMP diazonium Salt

Crystal data

Chemical formula C10H12N4NaO6S

Mr 339.29

Temperature (K) 296

a, b, c (Å) 7.3243 (5), 9.8930 (7), 10.5934 (8)

102.563 (4), 105.564 (4), 92.096 (4)

V (Å3) 718.05 (9)

Z 2

Radiation type Mo K

-1) 0.29

Crystal size (mm) 0.36 × 0.28 × 0.24

Absorption correction –

No. of measured, independent and

observed [I I)] reflections 10943, 3135, 2480

Rint 0.028

max (Å-1

) 0.640

Refinement

R[F2 F

2)], wR(F

2), S 0.036, 0.096, 1.04

No. of reflections 3135

No. of parameters 212

H-atom treatment H atoms treated by a mixture of independent

and constrained refinement

max min (e Å-3

) 0.28, -0.34

80

Table-4.2; Selected geometric parameters (Ao) of 1-(p-sulphophenyl)-3-methyl-4-azo-5-

pyrazolone

Na—O1i 2.2763 (15) N1—C6 1.417 (2)

Na—O5 2.2907 (17) N2—C9 1.303 (2)

Na—O6 2.3630 (16) N3—N4 1.109 (2)

Na—O4 2.3733 (15) N3—C8 1.328 (2)

Na—O6ii 2.4951 (16) C1—C2 1.382 (3)

Na—S1 3.3338 (9) C1—C6 1.387 (3)

Na—Naii 3.6887 (14) C1—H1 0.9300

S1—O2 1.4387 (16) C2—C3 1.380 (3)

S1—O4 1.4439 (14) C2—H2 0.9300

S1—O3 1.4543 (16) C3—C4 1.385 (3)

S1—C3 1.7720 (18) C4—C5 1.383 (3)

O1—C7 1.225 (2) C4—H4 0.9300

O1—Naiii

2.2763 (15) C5—C6 1.386 (2)

O5—H1 0.79 (3) C5—H5 0.9300

O5—H2 0.75 (3) C7—C8 1.433 (2)

O6—Naii 2.4951 (16) C8—C9 1.413 (3)

O6—H3 0.80 (3) C9—C10 1.488 (3)

O6—H4 0.84 (3) C10—H10A 0.9600

N1—C7 1.385 (2) C10—H10B 0.9600

N1—N2 1.405 (2) C10—H10C 0.9600

Symmetry code(s): (i) x-1, y, z-1; (ii) -x-1, -y+1, -z; (iii) x+1, y, z+1.

81

The above X-ray data revealed that it was a diazoxide sodium salt with two water molecules as

presented in its X-ray ORTEP diagram.

Note: Although the diazonium salts are generally unstable and often, at higher temperatures

decompose violently, however the present salt was very stable up to 750C and could be

recrystallized without explosion or decomposition. This could be kept in dry crystalline form for

several months without losing its stability.

Figure 4.3; FTIR spectrum of 1(p-sulphophenyl)-3-methyl-5-pyrazolone

Figure 4.4; FTIR spectrum of oxime of 1(p-sulphophenyl)-3-methyl-5-pyrazolone.

82

Figure 4.5; FTIR spectrum of diazo-1(p-sulphophenyl)-3-methyl-5-pyrazolone

4.3 Synthesis of Naphthol-AS Series of Dyes

In this series a total number of 28 dye samples were prepared with 7 different naphthols namely

naphthol-ASA, naphthol-AS BS, naphthol-AS D, naphthol-AS E, naphthol-AS LC, naphthol-

ASOL and naphthol-ASPH were used as couplers. Four dye samples were prepared with each

coupler. The first being an un-metalized dye and the three being chromium, iron and copper

complexes respectively. Chromium complexes were 2:1 type. For chromium dyes all three of the

water molecules being replaced by another molecule of the same dye to form a 2:1 complex.

It is note worthy to mention here that UV-Visible Spectra are screen prints of Spectra-flash

SF-550.The un-metalized dyes were used as standards and are shown as RED Spectrum. The

overall synthesis of these dyes is given in the Scheme-4.2.

83

NN

CH3

OH

SO3

- Na

+

NaNo2,HCl

-5 - 0 oC

NN

CH3

O

SO3

- Na

+

N OH

NN

CH3

O

SO3

- Na

+

NH3Cl-

NN

CH3

O-

SO3

- Na

+

N+

N

Zn + HCl

100 - 105 oC

NaNo2,HCl

-5 - 0 oC

(144) (145) (146) (147)

+

NN

CH3

O-

SO3

- Na

+

N+

N

Diazo

+

O

NHOH R1

R2

R3R4

Naphthol-AS Couplers(2a-g)

Na2CO3/NaOHN

N

CH3

OH

SO3H

N

N

O

NHOH R1

R2

R3R4

Dyes = 3a-g

N

N

CH3

O

N

N

O

NHO R1

R2

R3R4

HO3S

N

N

CH3

O

N

N

O

NH OR1

R2

R3 R4

SO3HCr

-

OH2OH2

OH2

N

N

CH3

O

N

N

O

NHO R1

R2

R3R4

M

HO3S

65 -75 oCCr(CH3COO-)3

100 - 105 oC

2a R1 =R2= R3 =R4=H

2c R2= R3 =R4=H,R4=CH3

2b R1 = R3 =R4=H,R2=NO2

2d R1= R2 =R4=H,R3=Cl

2e R1= R4 = OCH3,R2=H,R3=Cl

2f R1= OCH3,R2=R3,R4=H

2g R1= OC2H5,R2=R3,R4=H

3a-g Dyes = 201,205,209,213,217,221,225

5a-g Dyes = 203,207,211,215,219,223,227

6a-g Dyes = 204,208,212,216,220,224,228

7a-g Dyes = 202,206,210,214,218,222,226

7a-g Dyes

5a-g,6a-g Dyes

Metal Salts 4a-b

4a= FeSO4 .7H2O

4b= CuSO4 .5H2O

Scheme 4.2, Synthesis of acid dyes 3a-g and their Fe (II, 5a-g), Cu (II, 6a-g) and Cr (III, 7a-g)

complexes (201-228).

The synthesis of acid dyes 3a-g (201, 205, 209, 213, 217, 221, 225), based on 1-(p-

sulphophenyl)-3-methyl-5- pyrazolone and their iron (II), copper (II) and chromium (III)

complexes (5a-g, 6a-g and 7a-g) was achieved by following a four step procedure involving

synthesis of 1-(p-sulphophenyl)-3-methyl-4-amino-5- pyrazolone, diazotization, coupling with

different naphthol AS series couplers (2a-g) and their metal complex formation according to

84

scheme 4.2. The rational for selection of these dyes for synthesis, is to acquire various scaffolds

of this nature by metallization and to observe their shade and dyeing properties on leather.

Synthesis of this diazo intermediate has been confirmed from X-ray structure of its crystal

(Figure 4.1). Coupling was made in alkaline medium to do the reaction at ortho position to the

hydroxyl group of naphthol AS series and was accomplished in 2.5h with continuous stirring.

Synthesized dyes 3a-g (201, 205, 209, 213, 217, 221, 225) were precipitated on completion of

reaction by changing the pH of solution to acidic at 4.0 with HCl. Dyes were dried and purified

in ethanol. Metallization of above synthesized dyes was done by treating the alkaline solution of

dyes with FeSO4.7H2O, CuSO4.5H2O and Cr (CH3COO-)3 with continuous stirring and heating

the reaction mixture at 55-70oC for 4-5 h until the confirmation about completion of reaction was

observed by taking the TLC of reaction mixture in 9:1 chloroform and methanol. Dyes (3a-g)

were precipitated with addition of HCl, filtered and dried in oven at 80 oC. Dyes were again

purified from ethanol, dried, weighed and determined the percentage yield. Dyes 3a-g were

further processed for metallization. These unmetallized dyes 3a-g were tridentate ligands which

formed complexes with Iron (Fe, II) and Copper (Cu, II) through 1:1 metal and ligand

stoichiometric ratio and Chromium (Cr, III) formed complexes by 2:1 fashion. In case of Fe2+

and Cu2+

complexes lone pairs of electrons are donated by two oxygen atoms and one nitrogen

atom of the diazo linkage, while the other three coordination numbers of these metals have been

satisfied by three water molecules. The chromium complexes were octahedral and six

coordination number of Cr3+

was fulfilled by two ligand molecules. The complex formation

pattern has been verified by the UV. Visible Spectrophotometric studies of complex formation of

3a-g (201, 205, 209, 213, 217, 221, and 225) dyes.

4.3.1 Naphthol-ASA dyes

Four dye samples were prepared with naphthol-AS. The first being an un-metalized dye and the

three were chromium, iron and copper complexes respectively. Chromium complex was a 2:1

type. The detailed properties are shown in Table-4.3

85

Table-4.3 Physical properties of dyes 201-204

The UV-Visible data presented in table 4.3 are supported by UV-Visible Spectra-1 (Figure

4.6).The un-metallized dye (3a) 201 was a reddish orange dye with λmax 510 nm and absorbance

3.3.Its metallization with chromium had changed its λmax to 520 nm and absorbance 2.8 (dye

202), showing a bathochromic shift of 10 nm with a hypochromic effect of 0.5.

On the other hand metallization of dye 201 with iron produced a yellowish brown dye (dye 203)

with λmax 480 nm and absorbance 3.6, showing a hypsochromic shift of 30 nm with a

hyperchromic effect of 0.3.While metallization of dye (3a) 201 with copper resulted in the

formation of a reddish violet dye (dye 204) with λmax 520 nm and absorbance 3.5, showing a

bathoochromic shift of 10 nm with a hyperchromic effect of 0.2.

Dye # Dye Structure Molecular

formula

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

201 HO3S

N

N

CH3

OH

N N

OH

O

NH

C27H21N5

O6S

Orange/

Reddish

Orange

510/3.3 Ethanol

202

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

H+

C54H39Cr

N10 O12S2

Pink/

Violet 520/2.8 Ethanol

203

OH2 OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NHFe

C27H25Fe

N5O9S

Brown/

Yellowish

Brown

480/3.6 Ethanol

204

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu

C27H21Cu

N5O7S

Tan/

Reddish

Violet

520/3.5 Ethanol

86

Figure 4.6; UV-Visible Spectra-1 of dyes 201-204 (4851-umd = dye 201,

4851-Cr = dye 202, 4851-Fe = dye 203 and 4851-Cu = dye 204)

4.3.2 Naphthol-ASBS dyes.

Four dye samples were prepared with naphthol-ASBS. The first being an un-metalized dye and

the three were chromium, iron and copper complexes respectively. Chromium complex was a 2:1

type.The detailed properties are shown in Table-4.4

87


The UV-Visible data presented in Table-4.4 is supported by UV-Visible Spectra-2 (Figure 4.7).

The un-metallized dye 205 (3b) was a reddish orange dye with λmax 510 nm and absorbance

2.8.Its metallization with chromium produced a Bordeaux dye. It had changed its λmax to 520 nm

and absorbance 1.65 (dye 206), showing a bathochromic shift of 10 nm with a hypochromic

effect of 0.53.

On the other hand metallization of dye 205 (3b) with iron also produced a Bordeaux dye (dye

207) with λmax 500 nm and absorbance 1.66, showing a hypsochromic shift of 20 nm with a

hyperchromic effect of 0.52.

While metallization of dye 205 (3b) with copper resulted in the formation of a reddish orange

dye (dye 208) with λmax 510nm and absorbance 2.1, showing a hypsochromic shift of 20 nm with

a hyperchromic effect of 0.7.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

205 HO3S

N

N

CH3

OH

N N

OH

O

NH

O2N

C27H20N6

O8S

Brown/

Reddish

Orange

510/2.18 Ethanol

206 H+

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

NO2

NO2

C54H36Cr

N12 O16S2

Violet

Brown/

Bordeaux

520/1.65 Ethanol

207

OH2 OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NHFe

O2N

C27H24Fe

N6 O11S

Dark

Brown/

Bordeaux

500/1.66 Ethanol

208

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu

O2N

C27H20Cu

N6 O9S

Violet/

Reddish

Orange

510/2.1 Ethanol

88



4.3.3 Naphthol-ASD Dyes.

Four dye samples were prepared with naphthol-ASD. The first being an un-metalized dye and

the other three were chromium, iron and copper complexes respectively. Chromium complex

was a 2:1 type. The detailed properties are shown in Table-4.5

89

Table-4.5; Physical properties of dyes 209-212

The UV-Visible data presented in Table-4.5 is supported by UV-Visible Spectra-3 (Figure

4.8).The un-metallized dye 209 (3c) was an orange dye with λmax 510 nm and absorbance 2.1. Its

metallization with chromium changed its λmax to 520 nm (a pink dye) with absorbance 1.5 (dye

210), showing a bathochromic shift of 10 nm with hypochromic effect of 0.6.

On the other hand metallization of dye 209 (3c) with iron produced an olive brown dye (dye 211)

with λmax 510 nm and absorbance 1.1, showing a hypsochromic shift of 10nm with a

hypochromic effect of 1.0.While metallization of dye 209 (3c) with copper resulted in the

formation of a reddish orange dye (dye 212) with λmax 510 nm and absorbance 1.5, with no

change of color but a hyperchromic effect of 0.6.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

209 HO3S

N

N

CH3

OH

N N

OH

O

NH CH3

C28H23N5O6S

Tan/

Reddish

Orange

400/1.1,

510/2.1 Ethanol

210 H+

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

CH3

CH3

C56H42Cr

N10O12S2

Violet/

Pink

400/0.9

520/1.5 Ethanol

211

OH2 OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NHFe CH3

C28H27Fe

N5 O9S

Dark

Brown/

Olive

Brown

400/0.8

510/1.1 Ethanol

212

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu CH3

C28H23Cu

N5O7S

Violet/

Reddish

Orange

400/0.9

510/1.5 Ethanol

90



4.3.4 Naphthol-ASE Dyes.

Four dye samples were prepared with naphthol-ASE. The first being an un-metallized dye and



91


The UV-Visible data presented in Table-4.6 are supported by UV-Visible Spectra-4 (Figure

4.9).The un-metalized dye 213 (3d) was an orange dye with λmax 510 nm and absorbance 2.8. Its

metallization with chromium had changed its λmax to 520 nm and absorbance 1.8 (dye 214),

showing a bathochromic shift of 10 nm with a hypochromic effect of 1.0. On the other hand

metallization of dye 213 with iron produced a yellowish brown dye (dye 215) with λmax 480 nm

and absorbance 1.8, showing a hypsochromic shift of 30 nm with a hypochromic effect of 1.3.

While metallization of dye 213 (3d) with copper resulted in the formation of a Bordeaux dye

(dye 216) with λmax 510 nm and absorbance 1.5, showing no change of color but a hyperchromic

effect of 1.3.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

213 HO3S

N

N

CH3

OH

N N

OH

O

NH

Cl

C27H20Cl

N5O6S

Tan/

Reddish

Orange

400/1.05,

510/2.8 Ethanol

214

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

Cl

Cl

H+

C54H36Cl2Cr

N10O12S2

Dark

Brown/

Bordeaux

400/0.9,

520/1.8 Ethanol

215 OH2 OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NHFe

Cl

C27H24ClFe

N5O9S

Brown/

Yellowish

Brown

480/1.8 Ethanol

216

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu

Cl

C27H20ClCu

N5O7S

Dark

Brown/

Bordeaux

400/0.8

510/1.5 Ethanol

92



4.3.5 Naphthol-ASLC Dyes

Four dye samples were prepared with naphthol-ASLC. The un-metallized dye 217 (3e) was

metallized with chromium (III), iron (II) and copper (II) respectively. Chromium complex was a

2:1 type. The Physicochemical properties are shown in Table-4.7.

93


Table-4.7 presents the λmax and absorbance of dyes 217-220 that is supported by UV-Visible

Spectra-5 (Figure 4.10). The un-metallized dye 217 (3e) was a reddish orange dye with λmax 500

nm and absorbance 1.3.Its metallization with chromium had changed its color to violet with λmax

520 nm and absorbance 0.8 (dye 218), showing a bathochromic shift of 20 nm with a

hyperchromic effect of 0.5.On the other hand metallization of dye 217 (3e) with iron produced a

yellowish brown dye (dye 219) with λmax 500 nm and absorbance 1.4, showing a hyperchromic

effect of 0.1 with almost no change in color.While metallization of dye 217 (3e) with copper

resulted in the formation of a reddish orange dye (dye 220) with λmax 520 nm and absorbance 1.0

, showing a bathochromic shift of 20 nm with a hypochromic effect of 0.3.

Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax

(nm)/

Absorba-

nce

Solubility

217 HO3S

N

N

CH3

OH

N N

OH

O

NH

Cl

OCH3

H3CO

C29H24Cl

N5O8S

Orange/

Reddish

Orange

360/1.3,

500/1.3 Ethanol

218 H+

Cl

Cl

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

OCH3

H3CO

OCH3

H3CO

C58H45Cl2

CrN10O16S2

Light

Pink/

Violet

360/1.0,5

20/0.8 Ethanol

219 OH2

OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NH

Cl

OCH3

H3CO

Fe

C29H28ClFe

N5O11S

Brown/

Yellowish

Brown

360/1.85

00/1.4 Ethanol

220

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu

ClH3CO

OCH3

C29H24Cl

CuN5O9S

Tan/

Reddish

Orange

360/1.05

20/1.0 Ethanol

94


4813-Cr = dye 218, 4813-Fe = dye 219 and 4813- Cu = dye 220)

4.3.6 Naphthol-ASOL Dyes.

Four dye samples were prepared with naphthol-ASOL. The first being an un-metalized dye and



95


UV-Visible data presented in Table-4.8 are supported by UV-Visible Spectra-6 (Figure 4.11).

The un-metallized dye 221 (3f) was an orange dye with λmax510 nm and absorbance 2.1. Its

metallization with chromium had changed its color to maroon with λmax520 nm and absorbance

1.6 (dye 222), showing a bathochromic shift of 10 nm with a hypochromic effect of 0.5.On the

other hand metallization of dye 121 with iron produced a Bordeaux dye (dye 223) with λmax500

nm and absorbance 1.6, showing a hypsochromic shift of 10 nm with a hyperchromic effect of

0.5.While metallization of dye 221 with copper resulted in the formation of a maroon dye(dye

224) with λmax510 nm and absorbance 0.9, with a hypsochromic effect of 0.2.

Dye# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λ max (nm)/

Absorbance Solubility

221 HO3S

N

N

CH3

OH

N N

OH

O

NH OCH3

C28H23N5

O7S

Orange/

Reddish

Orange

400/1.1

510/2.1 Ethanol

222 H+

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

OCH3

OCH3

C56H43Cr

N10O14S2

Dark

Brown/

Maroon

400/0.9

520/1.6 Ethanol

223

OH2 OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NHFe OCH3

C28H27Fe

N5O10S

Brown/

Bordeaux 500/1.6 Ethanol

224

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu OCH3

C28H23Cu

N5O8S

Tan/

Maroon 510/0.9 Ethanol

96

Figure 4.11; UV-Visible Spectra-6 of dyes 221-224 (48OL-umd = dye 221,

48OL-Cr = dye 222, 48OL-Fe = dye 223 and 48OL- Cu = dye 224)

4.3.7 Naphthol-ASPH dyes.

Four dye samples were prepared with naphthol-ASPH. The first being an un-metallized dye and

other dyes were chromium, iron and copper complexes respectively. Chromium complex was a

2:1 type. The detailed properties are shown in Table-4.9

97

Table-4.9 Phsical properties of dyes 225-228


4.12). The un-metallized dye 225 (3g) was an scarlet dye with λmax510 nm and absorbance

2.2.Its metallization with chromium had not changed its color ( λmax510 nm) but absorbance 1.9

(dye 226), showing a hypochromic effect of 0.2.On the other hand metallization of dye 225 (3g)

with iron produced an olive brown dye (dye 227) with λmax 490 nm and absorbance 1.8, showing

a hypsochromic shift of 20 nm with a hypochromic effect of 0.4.While metallization of dye

225(3g) with copper resulted in the formation of a pink dye (dye 228) with λmax 510 nm and

absorbance 2.0, with a minor change being a hypochromic effect of 0.20.

Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorb-

ance

Solubility

225 HO3S

N

N

CH3

OH

N N

OH

O

NH OC2H5

C29H25N5

O7S

Bordeaux/

Scarlet 510/2.2 Ethanol

226 H+

HO3S

N

N

CH3

O

N N

O O

NH

HO3S

N

N

CH3

O

N N

O O

NH

Cr-

OC2H5

OC2H5

C58H47Cr

N10O14S2

Dark

brown/

Scarlet

510/1.9 Ethanol

227

OH2 OH2OH2

HO3S

N

N

CH3

O

N N

O

O

NHFe OC2H5

C28H27Fe

N5O10S

Gray/

Olive

Brown

490/1.85 Ethanol

228

OH2

HO3S

N

N

CH3

O

N N

O

O

NHCu OC2H5

C29H25Cu

N5O8S

Dark

Brown/

Pink

510/2.0 Ethanol

98


4898-Cr = dye 226, 4898-Fe = dye 227 and 4898- Cu = dye 228).

4.4 Spectral properties of naphthol-AS dyes

The infrared spectra of the synthesized acid dyes and their metal complexes exhibited absorption

peaks due to O-H,N-H, Ar-H, C-H, C=O, C=C, N=N, SO3H, C-O and O-M stretching and

bending vibrations at 3292-3315, 3045-3065, 2920-2931, 1675-1685, 1620-1660, 1526-1590,

99

1440-1455, 1160-1215, 1050-1130, 840-885 and 540-560 cm-1

as depicted from their FTIR

spectra. Specifically speaking, using FTIR spectrum of dyes 3a-g, a broad band is observed in

the range 2500-3500 cm-1

which is due to H-bonding of OH and N-H groups in close proximity

to each other in couplers which are masking the N-H peaks in some cases while in other cases

small single peak is present which shows that 2o amine group is present. Aromatic benzene and

naphthalene rings are evidenced by presence of peaks in the range 3045-3065 cm-1

due to C-H

stretching of unsaturated carbon atoms which are further confirmed by their peaks at 1620-1660

and 1526-1590 cm-1

. A peak is observed in the range 1675-1685 cm-1

which is due to amide

carbonyl functionality of dyes. The absorption bands at 1428-1455 cm-1

depicted the presence of

N=N stretching vibrations of dyes and this peak is common in all dyes. Synthesis of dyes 3a-g

has been confirmed by their FTIR spectra. The metal complexes of dyes 3a-g (201, 205, 209,

213, 217, 221, 225) have been inveterated by the presence of peaks at low frequency region at

525-540, 580-590 and 618-630 cm-1

because of large masses of metal atoms and these peaks are

absent in their respective FTIR spectra.

The 1H-NMR spectra of all dyes 3a-g (201, 205, 209, 213, 217, 221, 225) showed signals

down field at 9.82-12.03 ppm and 8.32-10.32 due to OH and N-H groups present in the coupling

components of dyes and were highly deshielded due to H-bonding. Similarly symmetrical

doublet peaks at 7.21-7.30 and 7.72 -7.80 ppm with same coupling constants were observed in

all dyes having benzene ring containing SO3H group. Methyl group singlet peak and methylenic

proton singlet was also common in all dyes and was present in the range 2.20-2.47 and 4.81-4.89

ppm (Figure 4.13). All these dyes 3a-g(201, 205, 209, 213, 217, 221, 225) were compounds of a

series where difference arises in case coupling component containing different substituents.

Naphthalene ring 4H multiplet peaks and 1H singlet peak at positions 7.82-7.75 and 7.38-7.45

ppm were common in all dyes. Difference in the H1-NMR spectrum of all dyes lies in the phenyl

group present at amide position of coupler. Multiplicity of these peaks is different in different

dyes. In case of C13

-NMR of all dyes showed the two carbonyl peaks at 165 and 169 ppm as

were present (Figure 4.14).

100

Figure 4.13, 1H-NMR Spectrum of Acid Dye 209 (3c)

101

Figure 4.14, 13

C-NMR Spectrum of Acid Dye 209 (3c)

4.5. DYEING PROPERTIES OF NAPHTHOL-AS DYES.

Dyeing properties of naphthol-AS dyes have been found to be very good. Almost all properties

have been found to be of very high values (4-5).However, chromium complexes were found to

be the best ones. The un-metallized dye-ligands owned low values as per expectations, due to the

presence of free hydroxyl groups. The results of the dyeing experiments are summarized in

table-4.10 which presents the dyeing properties of naphthol-AS series of dye. The applied dyes

samples on leather pieces are illustrated in Shade Card 1 part-a and part-b.

102

Table-4.10; Dyeing properties of naphthol-AS series

The data presented in Table-4.10 are supported by Shade card-1 part a-b.

Dye

#

2%Shade on

Leather

5%Shade on

Leather Penetration

Washing

Fastness

Light

Fastness

Perspiration

Fastness

201 Very Light Pink Light Pink 2 2-3 2-3 3-4

202 Light pink Pink 4 3-4 4-5 4-5

203 Light Beige Dark Beige 5 4-5 5 5

204 Light Pink Tea Pink 3 3-4 3-4 4-5

205 Light Orange Dark Orange 2 2-3 2-3 3-4

206 Reddish Violet Bordeaux 4 3-4 4-5 4-5

207 Yellowish Brown Dark Brown 5 4-5 5 5

208 Bluish Red Dark Bluish Red 3 3-4 3-4 4-5

209 Orange Reddish Orange 2 2-3 2-3 3-4

210 Bluish Red Bordeaux 4 3-4 4-5 4-5

211 Tan Dark Tan 5 4-5 5 5

212 Tea Pink Bluish Red 3 3-4 3-4 4-5

213 Reddish Beige Orange 2 2-3 2-3 3-4

214 Pink Bordeaux 4 3-4 4-5 4-5

215 Yellowish Brown Olive Brown 5 4-5 5 5

216 Light Pink Dark Pink 3 3-4 3-4 4-5

217 Light Beige Reddish Beige 2 2-3 2-3 3-4

218 Pink Dark Pink 4 3-4 4-5 4-5

219 Brown Dark Brown 5 4-5 5 5


221 Reddish Beige Dark Reddish Beige 2 2-3 2-3 3-4


223 Yellowish Beige Dark Yellowish

Beige 5 4-5 5 5


225 Beige Reddish beige 2 2-3 2-3 3-4

226 Reddish Violet Dark Violet 4 3-4 4-5 4-5

227 Yellowish Brown Reddish Brown 5 4-5 5 5

228 Light Pink Bluish Red 3 3-4 3-4 4-5

103

Shade Card 1 part-a

104

Shade Card 1 part b

A mutual comparison of shades of naphthol-AS series is presented in Shade Comparison 1-4 for

un-metallized, chromium, iron and copper complexes respectively.

105

Shade comparison-1

COMPARISON OF NAPHTHOL-AS BASED UN-METALLIZED DYES

Dye # Naphthol-AS 2% shade 5% shade

201 A

205 BS

209 D

213 E

217 LC

221 OL

225 PH

106

As it is clear from Shade comparison-1 (un-metallized), almost all of the dyes had similar

shades with a variation of only depth of shades. This may be attributed to the fact that the main

chromophoric system remained the same in all dyes. The variation of the depth can also be

attributed to the participation of peripheral group’s variation in naphthol-AS types.

Shade comparison-2

COMPARISON OF CHROMIUM METALLIZED NAPHTHOL-AS DYES

Dye # Naphthol-AS 2% Shade 5% Shade

202 A

206 BS

210 D

214 E

218 LC

222 OL

226 PH

107

As it is clear from Shade comparison-2 (chromium-metalized dyes) almost all of the dyes had

similar shades with a variation of only depth of the shades. This can be attributed to the fact that

the main chromophoric system remained the same in all un-metallized dyes. These dyes are very

bluish (Violet) than un-metallized parent dyes. However chromium complexes of naphthol-

ASBS, ASD, ASE, ASLC and ASPH were much darker in shades as compared to naphtol ASA

and ASOL. This variation of the depth can be attributed due to the participation of peripheral

group’s variation of difference of naphthol-AS moieties.

Shade comparison -3

COMPARISON OF IRON METALLIZED NAPHTHOL-AS DYES

As it is clear from Shade comparison-3 (iron-metallized dyes), almost all of the dyes had

different shades as compared with their parent dyes or chromium complexes.These were olive to

reddish brown in color with a variation of depth of shades. This can be attributed to the fact that

Dye # Naphtol-AS 2% Shade 5% Shade

203 A

207 BS

211 D

215 E

219 LC

223 OL

227 PH

108

the main chromophoric system remained the same in all iron-metallized dyes. However like

chromium, iron complexes of naphthol-ASBS, ASD, ASE, ASLC and ASPH were much darker

in shades as compared to naphthol-ASA and ASOL. This variation of the depth canbe attributed

to the participation of peripheral groups variation of naphthol-AS moieties.

Shade comparison -4

COMPARISON OF NAPHTHOL-AS COPPER COMPLEX DYES

Dye # Naphthol-AS 2% Shade 5% Shade

204 A

208 BS

212 D

216 E

220 LC

224 OL

228 PH

It is clear from Shade comparison-4 (copper-metallized dyes) almost all of the dyes had similar

shades with a variation of only depth of shades. This can be attributed to the fact that the main

chromophoric system remained the same in all copper-metallized dyes. These dyes are reddish

blue (violet) than un-metallized parent dyes. However copper complexes of naphthol-ASBS and

109

ASE are similar with deep shades, while that of ASLC and ASPH are lighter than these and

comparable in shades. In the same way shades of naphthol-ASA and ASOL are very similar to

parent dye ligands except a much bluish tone. This variation of the depth can be attributed to the

dye ligands by the participation of peripheral group’s variation of different of naphthol-AS types.

4.6 SYNTHESIS OF PYRAZOLONE SERIES OF DYES.

In this series a total number of 28 dye samples were prepared using 7 different pyrazolones.

These included1(4-sulfophenyl)-3-methyl-5-pyrazolone (SPMP), 1(4-sulfophenyl)-3-carboxy-5-

pyrazolone (SPCP), 1-Phenyl-3-methyl-5-pyrazolone (PMP), 1(4-tolyl)-3-methyl-5-pyrazolone

(PTMP), 1(2-chlorophenyl)-3-methyl-5-pyrazolone [2ClPMP], 1(3-chlorophenyl)-3-methyl-5-

pyrazolone [3-ClPMP] and 1(2,5-dichloro-4-sulfophenyl)-3-methyl-5-pyrazolone [2,5-

diClSPMP] were used as couplers. Four dye samples were prepared with each coupler. The first

being an un-metallized dye and the three were chromium, iron and copper complexes

respectively. Chromium complexes were 2:1 type. A synthetic scheme for coupling and

metallization is presented on page 111 (Scheme 4.3).

The synthesis of pyrazolone acid dyes 8a-g (229, 233, 237, 241, 245, 249, 253) involving 1-(p-

sulphophenyl)-3-methyl-5- pyrazolone as diazo component and their chromium (III), iron (II)

and copper (II) complexes (9a-g, 10a-g and 11a-g) was achieved by following a four step

procedure consisting of synthesis of 4-amino-1-(p-sulphophenyl)-3-methyl-5-pyrazolone,

diazotization, coupling with different pyrazolone couplers and their metal complex formation

(Scheme 4.3 and 4.4). The rational for selection of these dyes for synthesis, is to acquire various

scaffolds of this nature by metallization and to observe their shade and dyeing properties on

leather. Accordingly, 4-amino-1-(p-sulphophenyl)-3-methyl-5-pyrazolone was synthesized by

nitrosation of 1-(p-sulphophenyl)-3-methyl-5- pyrazolone (1) with NaNO2 and HCl at low

temperature 0-5oC. Nitroso derivative of 1-(p-sulphophenyl)-3-methyl-5- pyrazolone was

reduced with acetic acid and zinc dust at room temperature to 4-amino-1-(p-sulphophenyl)-3-

methyl-5-pyrazolone which was diazotized with NaNO2 and HCl, and coupled with couplers 2a-

g at low temperature to afford 8a-g (229, 233, 237, 241, 245, 249, 253). Synthesis of this diazo

intermediate has been confirmed from X-ray of its crystal. Coupling was made in alkaline

medium to do the reaction at C-four position of pyrazolone derivatives which is active methylene

position having acidic hydrogens sensitive to alkali and alkaline medium increases the

110

nucleophilicity of carbon which attacks on nitrogen of diazo component. Coupling was achieved

at room temperature with continuous stirring for 2.5h. Synthesized dyes 8a-g were precipitated

on completion of reaction by changing the pH of solution to acidic at 4.0 with HCl. Dyes were

dried and purified in ethanol. Metallization of above synthesized dyes was done by treating the

alkaline solution of dyes with Cr(OOCCH3)3, FeSO4.7H2O and, CuSO4.5H2O with continuous

stirring and heating the reaction mixture at 55-70oC for 4-5 h until the confirmation about

completion of reaction was observed by taking the TLC of reaction mixture in 9:1 chloroform

and methanol. Dyes were precipitated with addition of HCl, filtered and dried in oven at 70 oC.

Dyes were again recrystallized from ethanol, dried, weighed and determined the percentage

yield.

NN

CH3

OH

SO3H

NN

CH3

O

SO3H

N OH

NaNO2 + HCl

0 - 5 oC

NN

CH3

OH

SO3H

NH3 Cl

Zn + HCl

100 - 105 oC

+ -

NN

CH3

O-

SO3H

N+

N

NaNO2 + HCl

0 - 5 oC

NN

R1

OH

R3

R2

R4R5

NN

CH3

O-

SO3H

N+

N

+

NN

R1

OH

R3

R2

R4

NN

CH3

OH

SO3H

NN

R5

pH 8.0 - 8.5

15 - 25 oC8a-g

9,10 a-g

8a,R2,R4,R5=H,R1=CH3,R3=SO3H

8b,R2,R4,R5=H,R1=COOH,R3=SO3H

8c,R2, R3 ,R4,R5=H,R1=CH3

8d,R2,R4,R5=H,R1,R 3=CH3

8e,R2, R3 =H,R1=CH3,R4=SO3H,R5=H

8f,R2, R3 =H,R1=CH3,R4=Cl,R5=H

8g,R2,R5=Cl,R1=CH3,,R 3=SO3H,R4=H

9a-g dyes = 231,235,239,243,247,251,255

8a-g dyes = 229,233,237,241,245,249,253

OH2

OH2OH2

HO3S

N

N

CH3

O

NN

N

N

R1

O

R3

R2 R4

R5

M

10a-g dyes = 232,236,240,244,248,252,256

4a-b Metal Salts 55-70 oC

4a = FeSO4.7H2O

4b = CuSO4.5H2O

Scheme 4.3; Synthesis of acid dyes 8a-g, their Fe2+

(9a-g) and Cu2+

(10a-g) dyes (229-256).

111

NN

CH3

OH

SO3H

NN

CH3

O

SO3H

N OH

NaNO2 + HCl

0 - 5 oC

NN

CH3

OH

SO3H

NH3 Cl

Zn + HCl

100 - 105 oC

+ -

NN

CH3

O-

SO3H

N+

N

NaNO2 + HCl

0 - 5 oC

NN

R1

OH

R3

R2

R4R5

NN

CH3

O-

SO3H

N+

N

+

NN

R1

OH

R3

R2

R4

NN

CH3

OH

SO3H

NN

R5

pH 8.0 - 8.5

15 - 25 oC

HO3S

N

N

CH3

O

NN

N

N

R1

O

R3

R2 R4

SO3H

N

N

CH3

O

NN

N

N

R1

O

R3

R2R4

Cr-

R5

R5

Cr(CH3COO)3100 - 105 oC

8a-g

11a-g

8a,R2,R4,R5=H,R1=CH3,R3=SO3H

8b,R2,R4,R5=H,R1=COOH,R3=SO3H

8c,R2, R3 ,R4,R5=H,R1=CH3

8d,R2,R4,R5=H,R1,R 3=CH3

8e,R2, R3 =H,R1=CH3,R4=SO3H,R5=H

8f,R2, R3 =H,R1=CH3,R4=Cl,R5=H

8g,R2,R5=Cl,R1=CH3,,R 3=SO3H,R4=H

11a-g dyes = 230,234,238,242,246,250,254

8a-g dyes = 229,233,237,241,245,249,253

Scheme 4.4; Synthesis of pyrazolone dyes 8a-g and their Cr3+

(11a-g) complex dyes (229-254).

4.6.1 SPMP dyes.

Four dye samples were prepared with 1(4-sulfophenyl)-3-methyl-5-pyrazolone (SPMP). The first

being an un-metallized dye and the three were chromium, iron and copper complexes

respectively. Chromium complex was 2:1 type. The detailed properties of SPMP dyes are given

in table 4.11.

112


UV-Visible data presented in Table-4.11 is supported by UV-Visible Spectra-8(Figure 4.15).

The un-metallized dye 229 (8a) was a yellow dye with λmax 430 nm and absorbance 2.1. Its

metallization with chromium had changed its color to olive brown and λmax to 480 nm with

absorbance 3.2 (dye 230), showing a bathochromic shift of 50 nm with a hyperchromic effect of

1.1.

On the other hand metallization of dye 229 (8a) with iron also produced an olive brown dye (dye

231) with λmax 440 nm and absorbance 2.8, showing a bathochromic shift of 10 nm with a


While metallization of dye 229 (8a) with copper resulted in the formation of a yellow dye 232

(10a) with λmax 460 nm and absorbance 3.0, showing a bathochromic shift of 30 nm with a


Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

229 N

N

CH3

OH

HO3SN N

N

N

CH3

OH

SO3H

C20H18N6

O8S2

Orange/

Yellow 430/2.1 Water

230

N

N

CH3

O

HO3SN N

N

N

CH3

O

SO3H

N

N

CH3

O

HO3SN N

N

N

CH3

O

SO3H

Cr-H

+

C40H32Cr

N12O16S4

Brown/

Olive

Brown

480/3.2 Water

231

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

CH3

O

SO3H

Fe

C20H22Fe

N6O11S2

Olive/

Olive

Brown

440/2.8 Water

232

OH2

N

N

CH3

O

HO3SN N

N

N

CH3

O

SO3H

Cu-

C20H18Cu

N6O9S2

Olive /


113



4.6.2 SPCP Dyes.

Four dye samples were prepared with 1(4-sulfophenyl)-3-carboxyl-5-pyrazolone (SPCP). The

first dye was an un-metallized one and the other three were chromium, iron and copper

complexes respectively. Chromium complex was 2:1 type. The detailed properties of SPCP dyes

are given in Table-4.12

114



4.15). The un-metallized dye 233 (8b) was a yellow dye with λmax 500 nm and absorbance 3.0.It

had three absorptions owing to π → π* and n → n

*. Its metallization with chromium had changed

its color to Bordeaux, λmax to 490 nm and absorbance 2.7 (dye 234), showing a hypsochromic

shift of 10 nm with a hypochromic effect of 0.3.

On the other hand metallization of dye 233 with iron produced a yellowish brown dye (dye 235)

with λmax 450 nm and absorbance 3.7, showing a hypsochromic shift of 50 nm with a

hyperchromic effect of 0.7.While metallization of dye 233 with copper resulted in the formation

of a yellowish orange dye (dye 236) with λmax 460 nm and absorbance 3.1, showing a

hypsochromic shift of 40 nm with a hyperchromic effect of 0.1.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

233 N

N

CH3

OH

HO3SN N

N

N

HOOC

OH

SO3H

C20H16N6

O10S2

Orange/

Yellow

360/1.2,

460/3.2,

500/3.0

Water

234

N

N

CH3

O

HO3SN N

N

N

HOOC

O

SO3H

N

N

CH3

O

HO3SN N

N

N

HOOC

O

SO3H

Cr-H

+

C40H29Cr

N12O20S4

Reddish

Brown/

Bordeaux

370/1.7,

490/2.7 Water

235

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

HOOC

O

SO3H

Fe

C20H20Fe

N6O13S2

Black/

Yellowish

Brown

360/3.6,

450/3.7 Water

236

OH2

N

N

CH3

O

HO3SN N

N

N

HOOC

O

SO3H

Cu-

C20H16Cu

N6O11S2

Grey /

Yellowish

Orange

360/1.5,

460/3.1 Water

115



4.6.3 PMP Dyes.

Four dye samples were prepared with 1-Phenyl-3-methyl-5-pyrazolone (PMP). The first dye

being an un-metallized one and the other three were chromium, iron and copper complexes

respectively. Chromium complex was 2:1 type. The detailed properties of PMP dyes are given in

table 4.13.

116



4.17).The un-metallized dye 237 (8c) was an orange dye with λmax 440 nm and absorbance 1.6.Its

metallization with chromium had changed its color to yellow with λmax 450 nm and absorbance

1.3 (dye 238), showing a hyperchromic shift of 10 nm with a hypochromic effect of 0.3.

On the other hand metallization of dye 237 (8c) with iron produced a Yellowish Brown dye (dye


hypsochromic effect of 0.5. While metallization of dye 237 (8c) with copper resulted in the

formation of a reddish violet dye (dye 240) with λmax 440 nm and absorbance 0.4 , showing no

change of λmax but a hypsochromic effect of 1.2.

Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

237 N

N

CH3

OH

HO3SN N

N

N

CH3

OH

C20H18N6

O5S

Reddish

Orange/

Reddish

Orange

440/1.6 Water

238

N

N

CH3

O

HO3SN N

N

N

CH3

O

N

N

CH3

O

HO3SN N

N

N

CH3

OCr

-H+

C40H33Cr

N12O10S2

Olive/


239

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OFe

C20H22Fe

N6O8S

Olive

Brown/

Yellowish

Brown

430/0.9 Water

240

OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OCu-

C20H18Cu

N6O6S

Tan/

Reddish

Violet

440/0.4 Water

117



4.6.4 PTMP dyes.

Four dye samples were prepared with 1(p-Tolyl)-3-methyl-5-pyrazolone (PTMP). The first dye

was an un-metallized one and the other three were chromium, iron and copper complexes

respectively. Chromium complex was 2:1 type. The detailed properties of PTMP dyes are given

in Table 4.14.

118



4.17). The un-metallized dye 241 (8d) was an orange dye with λmax 440 nm and absorbance 1.7.

Its metallization with chromium had changed its color to greenish yellow with λmax 460 nm and

absorbance 1.6 (dye 242), with a bathochromic shift of 10nm and a hypochromic effect of 0.1.

On the other hand metallization of dye 241 with iron produced a reddish yellow dye (dye 243)

with λmax 430 nm and absorbance 1.6, showing a hypsochromic shift of 10 nm. While

metallization of dye 241 (8d) with copper resulted in the formation of a greenish yellow dye (dye

244) with λmax 440 nm and absorbance 2.3 , showing a hyperchromic effect of 0.6.

Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

241 N

N

CH3

OH

HO3SN N

N

N

CH3

OH

CH3

C21H20N6

O5S

Orange/

Reddish

Orange

440/1.7 Water

242

N

N

CH3

O

HO3SN N

N

N

CH3

O

N

N

CH3

O

HO3SN N

N

N

CH3

OCr

-

CH3

CH3

H+

C42H37Cr

N12O10S2

Olive/

Greenish

Yellow

460/1.6 Water

243

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OFe

CH3

C21H24Fe

N6O8S

Olive/

Reddish

Yellow

430/1.6 Water

244

OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OCu-

CH3

C21H20Cu

N6O6S

Olive/

Greenish

Yellow

440/2.3 Water

119



4.6.5 3-SPMP dyes.

Four dye samples were prepared with 1(3-sulphophenyl)-3-methyl-5-pyrazolone (3-SPMP). The

first dye being an un-metallized one and the other three were chromium, iron and copper

complexes respectively. Chromium complex was 2:1 type. The detailed properties of 3-SPMP

dyes are given in Table-4.15.

120



4.18).The un-metallized dye 245 (8e) was an orange dye with λmax 430 nm and absorbance 1.3.Its

metallization with chromium had changed its color to yellow with λmax 460 nm and absorbance

1.1 (dye 246), showing a bathochromic shift of 30 nm with a hypochromic effect of 0.2.

On the other hand metallization of dye 245 (8e) with iron also produced a yellowish dye (dye


hyperchromic effect of 0.55. While metallization of dye 245 (8e) with copper resulted in the

formation of a greenish yellow dye(dye 246) with λmax 430 nm and absorbance 1.85, that showed


Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

245 N

N

CH3

OH

HO3SN N

N

N

CH3

OH SO3H

C20H18N6

O8S2

Tan/

Reddish

Orange

430/1.3 Water

246

N

N

CH3

O

HO3SN N

N

N

CH3

O

N

N

CH3

O

HO3SN N

N

N

CH3

OCr

-

SO3H

SO3HH

+

C40H33Cr

N12O16S4

Dark

Brown/

Yellow

360/0.8,

460/1.1 Water

247

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OFe SO3H

C20H22Fe

N6O11S2

Gray/


248

OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OCu-

SO3H

C20H18Cu

N6O9S2

Yellowish

Brown/

Greenish

Yellow

430/1.85 Water

121

Figure 4.19; UV-Visible Spectra-12 of dyes 245-248 (8-3SPMP-umd = dye 245,

48-3SPMP-Cr = dye 246, 48-3SPMP-Fe = dye 247 and 48-3SPMP- Cu = dye 248).

4.6.6 3-ClPMP Dyes.

Four dye samples were prepared with 1(3-chlorophenyl)-3-methyl-5-pyrazolone (3-ClPMP). The

first dye being an un-metallized one and the other three were chromium, iron and copper

complexes respectively. Chromium complex was 2:1 type. The detailed properties of 3-ClPMP


122



4.19). The un-metallized dye 249 (8f) was an orange dye with λmax 440 nm and absorbance

2.7.Its metallization with chromium had changed its color to yellowish brown with λmax 450 nm

and absorbance 1.9 (dye 250), showing a bathochromic shift of 10 nm with a hypochromic effect

of 0.6.

On the other hand metallization of dye 249 (8f) with iron produced a yellowish brown dye (dye


hyperchromic effect of 0.3.While metallization of dye 249 (8f) with copper resulted in the

Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λ

max(nm)/

Absorba-

nce

Solublity

249 N

N

CH3

OH

HO3SN N

N

N

CH3

OH Cl

C20H17Cl

N6O5S

Reddish

Orange/

Reddish

Orange

440/2.7 Water

250

N

N

CH3

O

HO3SN N

N

N

CH3

O

N

N

CH3

O

HO3SN N

N

N

CH3

OCr

-

Cl

ClH

+

C40H31Cl2

CrN12O10S2

Yellowish

Brown/

Yellowish

Brown

450/1.9 Water

251

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OFe Cl

C20H21Cl

FeN6O8S

Dark

Brown/

Yellowish

Brown

420/3.0 Water

252

OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OCu-

Cl

C20H17Cl

CuN6O6S

Pale/

Greenish

Yellow

440/2.5 Water

123

formation of a greenish yellow dye(dye 252) with same λmax 440 nm and absorbance 2.5, that

showed a hypochromic effect of 0.2.

Figure 4.20; UV-Visible Spectra-13 of dyes 249-252 (48-3ClPMP -umd = dye 249,

48-3ClPMP -Cr = dye 250, 48-3ClPMP -Fe = dye 251 and

48-3ClPMP - Cu = dye 252).

4.6.7 2,5-diClSPMP Dyes

Four dye samples were prepared with 1-(2,5-dichloro-4-sulphophenyl)-3-methyl-5-pyrazolone

(2,5-diClSPMP). The first dye being an un-metallized one and the other three were chromium,

iron and copper complexes respectively. Chromium complexes were of 2:1 type. The detailed

properties of 2,5-diClSPMP dyes are given in Table-4.17.

124



4.20).The un-metallized dye 253 (8g) was an orange dye with λmax 440 nm and absorbance 2.65.

Its metallization with chromium had changed its color to reddish yellow with λmax 460 nm and

absorbance 2.3 (dye 254), showing a bathochromic shift of 20 nm with a hypochromic effect of

0.35.

On the other hand metallization of dye 253 (8g) with iron produced a reddish yellowish dye (dye

255) with λmax 420 nm and absorbance 1.8, it showed a hypsochromic shift of 20 nm with a

hypochromic effect of 0.85. While metallization of dye 253 with copper resulted in the formation

of a greenish yellow dye (dye 256) with λmax 450 nm and absorbance 2.6, showing a

bathochromic shift of 10 nm.

Dye

# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

253 N

N

CH3

OH

HO3SN N

N

N

CH3

OH Cl

Cl

SO3H

C20H16Cl2

O8S2

Orange/

Reddish

Orange

440/2.65 Water

254

N

N

CH3

O

HO3SN N

N

N

CH3

O

N

N

CH3

O

HO3SN N

N

N

CH3

OCr

-

Cl

Cl

Cl

SO3H

SO3H

Cl

H+

C40H29Cl4

CrN12O16S4

Olive /

Reddish

Yellow

460/2.3 Water

255

OH2OH2OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OFe Cl

Cl

SO3H

C20H20Cl2

FeN6O11S2

Olive /

Reddish

Yellow

420/1.8 Water

256

OH2

N

N

CH3

O

HO3SN N

N

N

CH3

OCu-

Cl

Cl

SO3H

C20H16Cl2

CuN6O9S2

Olive /

Greenish

Yellow

450/2.6 Water

125

Figure 4.21; UV-Visible Spectra-14 of dyes 253-256 (4849 -umd = dye 253,

4849-Cr = dye 254, 4849 -Fe = dye 255 and 4849 - Cu = dye 256)

4.7 Spectral Properties of Pyrazolone Dyes

The infrared spectra of the synthesized acid dyes and their metal complexes exhibited absorption

peaks due to COOH, O-H, Ar-H, C-H, C=O, C=C, N=N, SO3H, C-O, C-Cl and O-M stretching

and bending vibrations at 3565, 3460-3485, 3050-3062, 2920-2932, 1720, 1619-1665, 1531-

1591, 1441-1469, 1209-1272, 1040-1085, 853-885 770-772 and 520-560 cm-1

as depicted from

their FTIR spectra in Figure 4.22 and 4.23.

Specifically speaking, using FTIR spectrum of dyes 8g, a broad band is observed in the range

3200-3550 cm-1

which was due to H-bonding of COOH and O-H groups in close proximity to

each other in dyes. Aromatic (benzene) rings are evidenced by presence of peaks in the range

3460-3485 cm-1

due to C-H stretching of unsaturated carbon atoms which are further confirmed

by their peaks at 1619-1665 and 1531-1591 cm-1

.

A peak is observed in the range 1720cm-1

which is due to carbonyl functionality of dye 8g. The

absorption bands at 1428-1455 cm-1

depicted the presence of N=N stretching vibrations of dyes

and this peak is common in all dyes. Synthesis of dyes 8a-g has been confirmed by their FTIR

spectra. The metal complexes of dyes 8a-f have been inveterated by the presence of peaks at low

126

frequency region at 520-565cm-1

because of large masses of metal atoms and these peaks are

absent in their respective FTIR spectra.

Figure 4.22; FTIR Spectrum of Pyrazolone Acid Dye 253 (8g)

Figure 4.23; FTIR Spectrum Cu (II) complex 256 (10g) of pyrazolone acid dye 253 (8g)

The 1H-NMR spectrum of all dyes 8a-g (229, 233, 237, 241, 245, 249, 253) showed signals

down field at 9.19-10.00 ppm due to OH groups present in the coupling and diazo components of

dyes, and are highly deshielded due to H-bonding.

127

Similarly symmetrical doublet peaks at 7.71-7.92 and 8.03 -8.15 with same coupling constant

are observed in all dyes having benzene ring containing SO3H group and SO3H is evidenced

from its peak at range 6.65-7.70 ppm. Methyl group singlet peak is also common in all dyes and

is present in the range 2.61-2.68 ppm, which is further evidenced from their 13

C-NMR spectra

and is present at range 13.25-15.33 ppm. All these dyes 8a-g (229, 233, 237, 241, 245, 249, 253)

are compounds of a series where difference arises in case coupling component containing

different substituents. Benzene ring proton peaks are present at positions 7.59-7.93 and 7.38-7.45

ppm are common in all dyes. Multiplicity of these peaks is different in different dyes. Methyl

group in spectrum of dye 8g (253) has exhibited peak at 2.29 ppm while methine hydrogen is at

5.95 ppm and this highly deshielded. Mutually coupled hydrogens in the diazo component

showed doublet peaks at 7.68 and 7.89 ppm having coupling constant J = 8.7Hz which

confirmed their o-position, while hydroxyl and carboxyl group peaks are at 10.30 and 12.18 ppm

respectively (Figure 4.24).

The coupling component of dye showed multiplet peak at 7.71-7.76 ppm was due to aromatic

protons. 13

C-NMR of all dyes showed aromatic peaks in range 117-154 ppm. Peak at 163.73 ppm

in 13

C-NMR spectrum of dye 8g (253) was due to COOH group and CH3 group peak was at 12

ppm. Methine carbon was found at 89 ppm, as this hydrogen was involved in keto enol

tautomerism (Figure 4.25). The presence of peaks for respective carbons in spectrum is in favour

of synthesized dye 8g (253). Similarly other dyes have been confirmed from 1H and

13C-NMR

spectra.

128

Figure 4.24; 1H-NMR Spectrum of Pyrazolone Acid Dye 8g (253)

129

Figure 4.25; 13

C-NMR Spectrum of Pyrazolone Acid Dye 8g (253)

4.8 The Dyeing Properties of Pyrazolone Dyes.

The dyeing properties of pyrazolone dyes have been found to be very good. Almost all properties

have been found to be of very high value (4-5).However, chromium complexes were the best

ones. The un-metalized dye-ligands had low values as per expectation due to the presence of free

hydroxyl groups. The detail of dyeing properties of pyrazolone dyes is given in Table-4.18

130

Table -4.18 Dyeing properties of pyrazolone dyes (229-256)

The data presented in Table-4.18 are supported by Shade Card-2 (part-a and part-b).

Dye

#

2%Shade on

Leather

5%hade on

Leather

Penetr-

ation

Washing

Fastness

Light

Fastness

Perspiration

Fastness

229 Beige Yellowish

Orange 3 3-4 2-3 3-4

230 Dark Yellowish

Beige

Yellowish

Orange 4 3-4 4-5 4-5

231 Yellowish Beige Dark Beige 5 4-5 5 5

232 Greenish Yellow Greenish Yellow 4 3-4 3-4 4-5

233 Pink Reddish Orange 3 3-4 3-4 3-4

234 Reddish Beige Reddish Orange 4 3-4 4-5 4-5

235 Reddish Beige Olive 5 4-5 5 5

236 Yellowish Beige Dark Yellowish

Beige 3 3-4 3-4 4-5

237 Yellowish Orange Dark Yellowish

Orange 2 2-3 2-3 3-4


Orange 4 3-4 4-5 4-5

239 Beige Yellowish Brown 5 4-5 5 5

240 Light greenish

Yellow Yellowish Beige 3 3-4 3-4 4-5

241 Yellowish Orange Reddish Orange 2 2-3 2-3 3-4


Orange 4 3-4 4-5 4-5

243 Greenish Olive Yellowish Brown 5 4-5 5 5

244 Yellow Greenish Yellow 3 3-4 3-4 4-5

245 Dark Yellowish

Beige

Yellowish

Orange 2 2-3 2-3 3-4

246 Yellowish Beige Yellowish

Orange 4 3-4 4-5 4-5

247 Olive Reddish Beige 5 4-5 5 5

248 Greenish Yellow Dark Greenish

Yellow 3 3-4 3-4 4-5


250 Yellowish Orange Reddish Brown 4 3-4 4-5 4-5

251 Olive Brown 5 4-5 5 5

252 Yellow Dark Yellow 3 3-4 3-4 4-5

253 Yellowish Beige Yellowish Olive 2 2-3 2-3 3-4

254 Beige Dark Beige 4 3-4 4-5 4-5

255 Light Beige Dark Beige 5 4-5 5 5

256 Greenish Yellow Deep Yellow 3 3-4 3-4 4-5

132

A mutual comparison of shades of all pyrazolone dyes is presented in shade comparison 5-8 for


133

Shade comparison -5

COMPARISON OF UN-METALIZED DYES OF PYRAZOLONE SERIES

Dye # Pyrazolone 2% Shade 5% Shade

229 SPMP

233 SPCP

237 PMP

241 PTMP

245 3SPMP

249 3Cl PMP

253 2,5-DiClSPMP

As it is clear from Shade comparison-5 (un-metallized pyrazolone dyes) almost all of the dyes

had similar shades in 5%dyed leathers, with a variation of only depth of shades. This can be

attributed to the fact that again the main chromophoric system remained the same in all dyes.

The variation of the depth can be attributed to the participation of peripheral group’s variation of

difference of pyrazole moieties.The dye of SPCP (1-sulphophenyl-3-carboxypyrazol-5-one)has

been found to be much redder; this can be due to the presence of 3-carboxy group.Similarly the

dye with 1-(2,5-dichloro-4-sulphophenyl)-3-methyl pyrazol-5-one have been found to be much

greener in tone this can be attributed to the presence of two chlorine atoms on the benzene ring.

134

Shade comparison -6

COMPARISON OF CHROMIUM METALLIZED DYES OF PYRAZOLONE SERIES


230 SPMP

234 SPCP

238 PMP

242 PTMP

246 3-SPMP

250 3-Cl PMP

254 2,5-diClSPMP

As it is clear from Shade comparison-6 (chromium-metallized dyes), almost all of the dyes had

same shades like their parent dyes but with a much yellower tone. These were olive to reddish

brown in color with a variation of depth of shades. This can be attributed to the fact that the main

chromophoric system remained the same in all chromium-metallized dyes. However the

chromium complexes of SPCP, PMP and 3ClPMP were much darker in shades as compared to

3SPMP,4SPMP and 2,5-diClSPMP. This variation of the depth can be attributed to the

participation of peripheral group’s variation of different pyrazolones.

135

Shade comparison -7

COMPARISON OF IRON METALIZED DYES OF PYRAZOLONE SERIES

Dye

# Pyrazolone 2% Shade 5% Shade

231 SPMP

235 SPCP

239 PMP

243 PTMP

247 3SPMP

251 3Cl PMP

255 2,5-diClSPMP

As it is clear from Shade comparison-7 (iron-metallized pyrazolone dyes), almost all of the

dyes had different shades as compared to their un-metallized parent dyes. Most of the shades are

much greener in tone. These were olive to reddish brown in color with a variation of depth of

shades. This can be attributed to the fact that, as with the other dyes in the series, the main

chromophoric system remained the same in all iron-metalized dyes. However the iron complexes

of PMP and 3ClPMP were much darker in shades as compared to 3SPMP, 4SPMP and

2, 5-diClSPMP.

136

Shade comparison -8

COMPARISON OF COPPER METALLIZED DYES OF PYRAZOLONE SERIES

As it is clear from Shade comparison-8 (copper-metallized pyrazolone dyes), almost all of the

dyes had different shades as compared with their parent dye ligands. Copper complexes were

very greenish yellow as per our expectation. These were olive to greenish yellow except for

SPCP with reddish brown in color. This can be attributed to the fact that the main chromophoric

system remained the same in all copper-metalized dyes. However chromium complex of 2,5-

diClSPMP was the most greenish due to the presence of two chlorine atoms in the coupler.


232 4SPMP

236 SPCP

240 PMP

244 PTMP

248 3-SPMP

252 3-Cl PMP

256 2,5-diClSPMP

137

4.9 Synthesis of Naphthol Series of Dyes

In this series a total number of 20 dye samples were prepared. A total number of 5 different

naphthols namely β-naphthol, Schaeffer’s Acid, R-Acid, H-Acid and N-phenyl J-Acid were used

as couplers. Four dye samples were prepared with each coupler. The first being un-metallized

dye and the three were chromium, iron and copper complexes respectively. Chromium

complexes were of 2:1 type. A scheme of coupling and metallization for the synthesis of β-

naphthol type dyes is given in scheme 4.5.

The synthesis of pyrazolone naphthol acid dyes 13a-e (257, 261, 265, 269, 273) involving 4-

amino-1(p-sulphophenyl)-3-methyl-5-pyrazolone as diazo component and their chromium (III),

iron (II) and copper (II) complexes was achieved by following a five step procedure. It consisted

of nitrosation of SPMP, reduction to 4-amino-1-(p-sulphophenyl)-3-methyl-5-pyrazolone,

diazotization, coupling with different naphthol derivatives and their metal complex formation.

The objective for selection of these dyes for synthesis was to acquire various scaffolds of this

nature by metallization and to observe their shade and dyeing properties on leather.

Accordingly, 4-amino-1-(p-sulphophenyl)-3-methyl-5-pyrazolone was synthesized by nitrosation

of 1-(p-sulphophenyl)-3-methyl-5-pyrazolone (144) with NaNO2 and HCl at low temperature 0-

5°C. The nitroso derivative of 1-(p-sulphophenyl)-3-methyl-5- pyrazolone was reduced with zinc

and HCl at high temperature(100-105°C) to give 4-amino-1-(p-sulphophenyl)-3-methyl-5-

pyrazolone hydrochloride. It was diazotized with NaNO2 and HCl, and coupled with napthol

derivatives at 15-25°C. The Synthesis of diazo intermediate has been confirmed from X-ray of

its crystal. Dyes were purified in ethanol. Metallization of above synthesized dyes was done by

treating the alkaline solution of dye with Cr(CH3COO-)3, FeSO4.7H2O and CuSO4.5H2O with

continuous stirring and heating of the reaction mixture at 100-105°C for chromium and 55-70°C

for iron and copper.It took 4-5h to complete of metallization, as was observed by checking the

TLC of reaction mixture in 9:1 chloroform and methanol. Dyes were precipitated at low pH and

temperature by the addition of HCl and salt, filtered and dried in an oven at 70°C. Dyes were

again purified from ethanol, dried, weighed and the percentage yield was determined. The yields

ranged from 83-96%.

138

N

NCH3

N+

O-

Na+ -O3S

N

R1

R2R3

OH

Couplers (12a-e)Diazo of SPMP

15 - 25 oC Na2CO3/NaOH

+

N

N

CH3

N

OH

HO3S

N

R1

R2

R3OH

OH2OH2 OH2

N

N

CH3

N

O

HO3S

N

R1

R3OM

R2

FeSO4/CuSO4

65 - 70 oCCr(CH3COO-)3

100 - 105 oC

Dyes(13a-e)

Dyes(14a-e)

M = Fe2+

/Cu 2+

Dyes 15,16a-e

Dyes(14a-e) Cr3+

Dyes= Dyes 258,262,266,270,274

Dyes(13a-e) = Dyes 257,261,265,269,273

Dyes(15a-e) Fe 2+

Dyes= Dyes 259,263,267,271,275

Dyes(16a-e) Cu 2+

Dyes= Dyes 260,264,268,272,276

N

N

CH3

NO

HO3S

N

R1

R3O

R2

N

N

CH3

NO

SO3H

N

R1

R3 OCr

-

R2

Where ; R1=H, R2=R3 = H/SO3H

Scheme-4.5; Synthesis of Naphthol dyes 13a-e and their Fe (15a-e), Cu (16a-e) complexes (dyes

257-276)

4.9.1 β-Naphthol dyes.

Four dye samples were prepared with β-naphthol. The first dye being an un-metallized one and


was of 2:1type. The detailed properties of β-naphthol dyes are given in Table-4.19.

139



4.26). The un-metallized dye 257 was a yellowish orange dye with λmax 490 nm and absorbance

2.2.Its metallization with chromium had changed its color to pink with λmax 520 nm and

absorbance 1.35 (dye 258), showed a bathochromic shift of 30 nm with a hypochromic effect of

0.85. On the other hand metallization of dye 257 with iron produced an olive brown dye (dye


hypochromic effect of 1.4.

While metallization of dye 257 with copper resulted in the formation of a reddish brown dye(dye

260) with λmax 470 nm and absorbance 0.85 , showing a hypsochromic shift of 20 nm with a


Dye# Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λ max (nm)/

Absorba-

nce

Solubility

257 N

N

CH3

OH

HO3SN N

OH

C20H16N4

O5S

Orange/

Yellowish

Orange

360/0.9 ,

490/2.2 Water

258

N

N

CH3

O

HO3SN N

O

N

N

CH3

O

HO3SN N

OCr

-H

+

C40H29Cr

N8O10S2

Dark

Brown/

Pink

360/0.9 ,

520/1.35 Water

259

OH2OH2 OH2

N

N

CH3

O

HO3SN N

OFe

C20H20Fe

N4O8S

Dark

Brown/

Olive

Brown

360/0.8 Water

260

OH2

N

N

CH3

O

HO3SN N

OCu-

C20H16Cu

N4O6S

Dark

Brown/

Reddish

Brown

360/1.85 ,

470/0.85 Water

140



4.9.2 Schaeffer’s acid Dyes.

Four dye samples were prepared with Schaeffer’s Acid (2-naphthol-6-sulphonic acid). The first

dye being an un-metallized one and the other three were chromium, iron and copper complexes

respectively. Chromium complex was of 2:1 type. The detailed properties of Schaeffer’s Acid


141



4.27).The un-metallized dye 261 was a yellowish orange dye with λmax 480 nm and absorbance

1.05.Its metallization with chromium changed its color to pink with λmax 510 nm and absorbance

1.09 (dye 262), showing a bathochromic shift of 30 nm with a hyperchromic effect of 0.04.

On the other hand metallization of dye 261 (13b) with iron produced a beige dye (dye 263) with

λmax 450 nm and absorbance 1.59, showing a bathochromic shift of 30 nm with a hyperchromic

effect of 0.54.While metallization of dye 261 (13b) with copper resulted in the formation of a

reddish orange dye (dye 264) with λmax 470 nm and absorbance 1.5, showing a hypsochromic

shift of 10 nm with a hyperchromic effect of 0.45.

Dye# Dye Structure

Molecular

Formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorb-

ance

Solubiity

261 N

N

CH3

OH

HO3SN N

OH

SO3H

C20H16N4

O8S2

Tan/

Yellowish

Orange

360/0.55,

480/1.1 Water

262

N

N

CH3

O

HO3SN N

O

N

N

CH3

O

HO3SN N

OCr

-

SO3H

SO3H

H+

C40H29Cr

N8O16S4 Tan/Pink

360/1.05,

510/1.09 Water

263

OH2OH2 OH2

N

N

CH3

O

HO3SN N

OFe

SO3H

C20H20Fe

N4O11S2

Olive

Brown/

Beige

360/1.7,

450/1.59 Water

264

OH2

N

N

CH3

O

HO3SN N

OCu-

SO3H

C20H16Cu

N4O9S2

Tan/

Reddish

Orange

360/0.55,

470/1.5 Water

142



4.9.3 R-Acid dyes.

Four dye samples were prepared with R-Acid (2-naphthol-3,6-disulphonic acid). The 1st

dye

being un-metallized one and the other three were chromium, iron and copper complexes

respectively. Chromium complex was of 2:1 type. The detailed properties of R-Acid dyes are

given in Table-4.21.

143


The UV-Visible data presented in Table-4.21.is supported by UV-Visible Spectra-17 (Figure

4.28).The un-metallized dye 265 (13c) was a reddish orange dye with λmax 470 nm and

absorbance 2.3. Its metallization with chromium changed its color to pink with λmax 540 nm and


1.8.On the other hand metallization of dye 265 (13c) with iron produced an olive brown dye (dye



While metallization of dye 265 (13c) with copper resulted in the formation of a yellowish orange

dye (dye 268) with λmax 490 nm and absorbance 0.75, showed a bathochromic shift of 20 nm

with a hypochromic effect of 1.55.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

265 N

N

CH3

OH

HO3SN N

OH

SO3H

SO3H

C20H16N4

O11S3

Dark

Brown/

Reddish

Orange

360/1.1 ,

470/2.3 Water

266

N

N

CH3

O

HO3SN N

O

N

N

CH3

O

HO3SN N

OCr

-

SO3H

SO3H

SO3H

SO3H

H+

C40H29Cr

N8O22S6

Dark Tan/

Pink

360/0.55,

540/0.5 Water

267

OH2OH2 OH2

N

N

CH3

O

HO3SN N

OFe

SO3H

SO3H

C20H20Fe

N4O14S3

Dark

Brown/

Olive

Brown

360/0.7,

460/0.82 Water

268

OH2

N

N

CH3

O

HO3SN N

OCu-

SO3H

SO3H

C20H16Cu

N4O12S3

Yellowish

brown/

Yellowish

Orange

360/0.82,

490/0.75 Water

144

Figure 4.28; UV-Visible Spectra-17 of dyes 265-268 (48RA-umd = dye 265,

48RA-Cr = dye 266, 48RA -Fe = dye 267 and 48RA - Cu = dye 268).

4.9.4 H-Acid Dyes.

Four dye samples were prepared with H-Acid (1-amino-8-naphthol-3,6-disulphonic acid) in

basic coupling. The 1st

dye was un-metallized one and the other three were chromium, iron and

copper complexes respectively. Chromium complex was 2:1 type. The detailed properties of H-

Acid dyes are given in Table-4.22.

145



4.29). The un-metallized dye 269 (13d) was an orange dye with λmax 520 nm and absorbance 0.7.

Its metallization with chromium changed its color to Violet with λmax 560 nm and absorbance 0.8

(dye 270), showing a bathochromic shift of 40 nm with a hyperchromic effect of 0.1.

On the other hand metallization of dye 269 (13d) with iron produced a yellowish brown dye (dye


hyperchromic effect of 0.1. While metallization of dye 269 (13d) with copper resulted in the

formation of a reddish violet dye (dye 272) with λmax 440 nm and absorbance 1.1, showing a

hypsochromic shift of 80 nm with a hyperchromic effect of 0.4.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

269 N

N

CH3

OH

HO3SN N

SO3HHO3S

NH2OH

C20H17N5

O11S3

Brown/

Reddish

Orange

360/0.7,

520/0.7 Water

270

N

N

CH3

O

HO3SN N

SO3HHO3S

NH2O

N

N

CH3

O

HO3SN N

SO3HHO3S

NH2OCr

-H

+

C40H31Cr

N10O22S6

Violet/

Violet

360/1.5,

560/0.8 Water

271

OH2OH2OH2

N

N

CH3

O

HO3SN N

SO3HHO3S

NH2OFe

C20H21Fe

N5O14S3

Brown/

Yellowish

Brown

360/1.6,

500/0.6 Water

272

OH2

N

N

CH3

O

HO3SN N

SO3HHO3S

NH2OCu-

C20H17Cu

N5O12S3

Tan/

Reddish

Violet

360/1.5,

440/1.1 Water

146


4824-Cr = dye 270, 4824 -Fe = dye 271 and 4824 - Cu = dye 272).

4.9.5 N-Phenyl J. Acid dyes.

Four dye samples were prepared with N-phenyl-J-Acid (6-anilino-1-naphthol-3-sulphonic acid).

The first dye was un-metallized one and the other three were chromium, iron and copper

complexes respectively. Chromium complex was 2:1 type. The detailed properties of NPJ-Acid


147


Dye # Dye Structure Molecular

Formula(Calc.)

Powder/

Solution

Color

λmax(nm)

Absorba-

nce

Solubility

273 N

N

CH3

OH

HO3SN N

NHHO3S

OH

C26H21N5

O8S2

Orange/

Reddish

Orange

360/0.9,

480/1.2 water

274

N

N

CH3

O

HO3SN N

NHHO3S

O

N

N

CH3

O

HO3SN N

NHHO3S

OCr

-H+

C52H39Cr

N10O16S4

Violet/

Violet

360/0.7,

530/0.5 water

275

OH2OH2

OH2

N

N

CH3

O

HO3SN N

NHHO3S

OFe

C26H25Fe

N5O11S2

Black/

Reddish

brown

360/1.8,

490/1.3 water

276

OH2

N

N

CH3

O

HO3SN N

NHHO3S

OCu-

C26H21Cu

N5O9S2

Black/

Violet

Brown

360/1.1,

500/0.7 water


4.30).The un-metallized dye 273 (13d) was a reddish orange dye with λmax 480 nm and

absorbance 1.2. Its metallization with chromium changed its color to violet with λmax 530 nm and


0.7. On the other hand metallization of dye 273 with iron produced a reddish brown dye (dye

275) with λmax 490 nm and absorbance 1.3, showed a bathochromic shift of 10 nm with a

hyperchromic effect of 0.1.While metallization of dye 273 with copper resulted in the formation

of a violet brown dye (dye 276) with λmax 500 nm and absorbance 0.7, showing a bathochromic

shift of 20 nm with a hypochromic effect of 0.5.

148



4.10 The Dyeing Properties of Naphthol Dyes

The naphthol dyes were found to have very good dyeing properties. Almost all properties have

been found to be of very high value (4-5).However, chromium complexes have been found to be

the best ones. The un-metallized dye-ligands with low values were as per expectation due to the

presence of free hydroxyl groups. The dyeing properties of naphthol dyes are given in

149

Table-4.24

Table 4.24 Dyeing properties of Naphthol Series of Dyes.

The data presented in Table-4.31 are supported by Shade Card-3 part-a and part-b.

Dye

#

2%Shade on

Leather

5%Shade on

Leather Penetration

Washing

Fastness

Light

Fastness

Perspiration

Fastness


258 Violet Bordeaux 4 3-4 4-5 4-5

259 Olive Brown Reddish Brown 5 4-5 5 5

260 Light Orange Reddish Orange 4 3-4 3-4 4-5

261 Light Orange Dark Yellowish

Orange 3 3-4 3-4 3-4


263 Olive Dark Olive 5 4-5 5 5

264 Yellowish

Orange Reddish Orange 3 3-4 3-4 4-5

265 Light Pink Reddish Orange 2 2-3 2-3 3-4

266 Pink Dark Pink 4 3-4 4-5 4-5


268 Reddish Beige Reddish Orange 3 3-4 3-4 4-5

269 Tan Dark Brown 2 2-3 2-3 3-4

270 Violet Brown Dark Violet

Brown 4 3-4 4-5 4-5


272 Olive Dark Olive 3 3-4 3-4 4-5

273 Tan Maroon 2 2-3 2-3 3-4

274 Light Violet Dark Violet 4 3-4 4-5 4-5


276 Light Brown Dark Brown 3 3-4 3-4 4-5

151

A mutual comparison of shades of naphthol dyes is presented in Shade Comparisons 9-12, for


152

Shade comparison-9

COMPARISON OF UN-METALLIZED DYES OF NAPHTHOL SERIES

Dye # Naphthol 2% Shade 5% Shade

257 β- Naphthol

261 Schaeffer’s Acid

265 R.Acid

269 H.Acid

273 N-Phenyl-J.Acid

As it is clear from Shade comparison-9 (un-metallized naphthol dyes) almost all of the dyes had

different shades both in 2% and 5% dyed leathers, along with a variation of depth of shades. This

can be attributed to the difference of chromophoric systems in all the dyes.The dyes of β-

naphthol homologues (Schaeffer’s Acid and R. Acid) are lighter and redder. The variation of the

depth can be attributed to the participation of peripheral group’s variation of different naphthols.

The α-naphthol homologue, the dye of H.Acid (1-amino-8-naphthol-3,6-disulphonic acid) and

NPJ (N-Phenyl –J. Acid)(2-aminophenyl-5-naphthol-7-sulfonic Acid)has been found to be much

darker, this can be due to presence of free NH2 and NH groups in these dyes.

153

Shade comparison-10

COMPARISON OF CHROMIUM METALLIZED DYES OF NAPHTHOL SERIES


258 β-Naphthol

262 Schaeffer’s

Acid

266 R.Acid

270 H.Acid

274 N-Phenyl-

J. Acid

As it is clear from Shade comparison-10 (chromium-metallized naphthol dyes) almost all of the

dyes had bluer shades both in 2% and 5% dyed leathers, along with a variation of depth of

shades as compared to their parent dye-ligands. The dyes of β-naphthol homologues (Schaeffer’s

Acid and R. Acid)are lighter and redder. This can be attributed to the difference of chromophoric

systems in the couplers of all dyes. The variation of the depth can be attributed to the

participation of peripheral group’s variation of difference of naphthol moieties. The dye of

H.Acid (1-amino-8-naphthol-3,6-disulphonic Acid) has been found to be much darker like its

parent dye-ligand. This can be due to the presence of free amino group in it. Similarly the dye

with NPJ (N-Phenyl –J. Acid) (2-aminophenyl-5-naphthol-7-sulfonic Acid) have also been found

to be much darker and bluer as these are α-naphthol homologues.

154

Shade comparison-11

COMPARISON OF IRON METALLIZED DYES OF NAPHTHOL SERIES


259 β-Naphthol


267 R.Acid

271 H.Acid

275 N-Phenyl-

J.Acid

As it is clear from Shade comparison -11 (iron-metallized naphthol dyes) almost all of the dyes

had different shades both in 2% and 5% dyed leathers, along with a variation of depth of shades.

This can be attributed to the difference of chromophoric systems in all dyes. However, it is clear

from shades that this difference is due to the difference of α-naphthol and β-Naphthol

differences. It is clear that α-naphthol homologues (H. Acid and NPJ) have similar dark shades

and β-naphthol homologues (Schaeffer’s Acid and R. Acid) have similar light shades(olive

shades. The variation of the depth can be attributed to the participation of peripheral group’s

variation of difference of naphthol moieties. The dye of H.Acid (1-amino-8-naphthol-3,6-

disulphonic acid) has been found to be much darker, this can be due to the presence of its free

155

amino group. Similarly the dye with NPJ (N-Phenyl–J.Acid) (2-aminophenyl-5-naphthol-7-

sulfonic acid) have been also found to be much darker.

Shade comparison -12

COMPARISON OF COPPER METALIZED DYES OF NAPHTHOL SERIES


260 β -Naphthol


268 R.Acid

272 H. Acid

276 N-Phenyl-J. Acid

Almost all copper-metallized naphthol dyes (Shade comparison-12) had been found to be

different; both in 2% and 5% dyed leathers, along with a variation of depth of shades. This can

be attributed to the difference of chromophoric systems in all these dyes. However, it is clear

from shades that this difference is due to the difference of α-naphthol and β-naphthol differences.

The α-naphthol homologues (H. Acid and NPJ) have similar dark shades and β-naphthol

homologues (Schaeffer’s Acid and R. Acid) have similar light and redder shades like their parent

un-metallized dyes.

The variation of the depth can be attributed to the participation of peripheral group’s variation in

different naphthols. The dye of H.Acid (1-amino-8-naphthol-3,6-disulphonic acid) and NPJ (N-

156

Phenyl-J. Acid) (2-aminophenyl-5-naphthol-7-sulfonicacid) has been found to be much darker,

this can be due to the presence of free NH2 and NH groups in H Acid and NPJ respectively.

4.11 Synthesis of p-Substituted-Phenols, Resorcinol and Bis-Phenol series of dyes.

In this series a total number of 20 dye samples were prepared and for this purpose 3 different

para substituted phenols, namely, p-chlorophenol, p-nitrophenol and phenol-4-suphonicAcid, 2-

nitrophenol-4-suphonic acid, resorcinol and bisphenols were used as couplers. Four dye samples

were prepared with each coupler. The first being un-metallized dye and the three were

chromium, iron and copper complexes respectively. Chromium complexes were of 2:1 type. The

synthetic schemes for the preparation of p-substituted phenols, resorcinol and bisphenol dyes are

presented as Scheme-4.6 and 4.7.

SPMP [1-(4-sulphophenyl)3-methyl-2-pyrazolin-5-one] was nitrosated at 0-5ºC using NaNO2

and HCl as described by Knorr1. The nitroso compound was filtered to remove some terry

material. The clarified nitroso derivative [that usually exists in an oxime form (as indicated by its

FTIR)], was salted out by common salt. It was dried after filtration. Reduction of oxime was

carried at 100-105ºC using Zinc and HCl. The oxime and Zinc were alternatively added in small

portions in boiling HCl solution. The reduction was completed as the solution became colorless.

A small amount of additional zinc dust was also added to prevent aerial oxidation on cooling.

The resultant amine hydrochloride was quenched to -7 ºC. The excessive un-reacted zinc was

removed by filtration.

The amine hydrochloride was diazotized using an aqueous solution of NaNO2 (6.9g dissolved in

250mL of solution) and HCl at -5 to -2ºC to avoid the formation of Rubazoic acid, which is

automatically formed during this reaction with increasing temperature due to oxidizing action of

nitrous acid, formed in situ.

The diazonium salt prepared in this way was coupled with different para substituted phenols,

like, p-Chlorophenol, p-Nitrophenol, phenol-4-suphonic acid, 2-Nitrophenol-4-suphonic acid and

bisphenols (Bisphenol S and Bisphenol A). The coupling was carried out in alkaline medium at

pH 8-9. The synthesis of this diazo has been confirmed from X-ray of its crystal. Coupling in

alkaline medium occurred at ortho position to the hydroxyl groups of phenols and bisphenols as

para position was blocked. The synthesized dyes (18a-g) were precipitated on completion of

157

reaction by reducing the pH of solution to 1.0 with HCl. The filtered dyes were dried and

purified in ethanol. Metallization of these dyes was done by treating their alkaline solution with

FeSO4.7H2O, CuSO4.5H2O and Cr(CH3COO)3 at 65-70oC and 100-105

oC. It took about 4-5h to

complete the metallization as was observed by taking the TLC of reaction mixture in 9:1

chloroform and methanol.

Dyes (19a-u) were precipitated with addition of HCl, filtered and dried in oven at 80oC. These

dyes were again purified from ethanol, dried, weighed and determined the percentage yield.

These unmetallized dyes 18a-g were tridentate ligands which formed complexes with Iron (Fe,

II), Copper (Cu, II) and Cr (III) through 1:1 metal and 2:1 ligand stoichiometric ratio. In case of

Fe2+

and Cu2+

complexes lone pairs of electrons were donated by two oxygen atoms and one

nitrogen atom of the diazo linkage, while the other three coordination numbers of these metals

have been satisfied by three water molecules. The complex formation pattern has been verified

by the UV-visible spectrophotometric studies of these dyes 19a-u.

In case of IR spectra of compounds different functional moieties showed stretching and bending

bands characteristic of the synthesized compounds. The infrared spectra of the synthesized acid

dyes and their metal complexes exhibited absorption peaks due to O-H, Ar-H, C-H, C=O, C=C,

N=N, SO3H, C-O and O-M stretching and bending vibrations at 3399, 3050, 2926, 1550, 1472,

1272, 1164, 1004, 834 and 610 cm-1

as depicted from their FTIR spectra (Figure 4.31). Similarly

other metal complexes have been confirmed from their respective IR spectra.

158

NN

SO3H

H3C

OHNaNO2, HCl

-2 -(-5) oC

NN

SO3H

H3C

OH

N O

Zn + HClN

N

SO3H

H3C

OH

NH3

NaNO2, HCl

25-30 oC

NN

SO3H

H3C

O

N N

OH

R3

R2

12 3 4

17a-d

NaO3S

N

N

CH3

OH

N N

HO

R3

R2

Na2CO3/NaOH

10 -15 oC

Metalization60 -65 oC

OH2OH2

H2O

HO3S

N

N

CH3

O

N N

M+2 O

R3

R2

18a-d

19a-h

R1

R1

R1

17e-g

Na2CO3/NaOH

10 -15 oC

N

N

H3C

HO

NN

N

N

CH3

OH

NN

SO3HHO3S

O

N

N

H3C

O

NN

N

N

CH3

O

NN

O

SO3HHO3S

M+2

M+2

H2OH2O

H2OH2OH2O

H2O

60 -65 oC Metalization

18e-g

19i-n

Cl

17-18a R1=R2=H, R3=Cl, Dye=277,

17-18b R1=R2=H, R3=NO2,Dye=281

17-18c R1=R2=H, R3=SO3H, Dye=285,

17-18d R1=H, R2=NO2, R3=SO3H, Dye=289,

17-18e Ar= Resorcinol, Dye=293,

17-18f Ar= Bis-Phenol S, Dye =297,

17-18g Ar= Bis-Phenol A, Dye= 301

19a R1=R2=H, R3=Cl, M= Fe (II), Dye= 279 19b R1=R2=H, R3=Cl, M= Cu (II), Dye= 280

19c R1=R2=H, R3=NO2, M= Fe (II), Dye= 283 19d R1=R2=H, R3=NO2, M= Cu (II), Dye= 284

19e R1=R2=H, R3=SO3H, M= Fe (II), Dye= 287 19f R1=R2=H, R3=SO3H, M= Cu (II), Dye= 288

19g R1=H, R2=NO2, R3=SO3H, M= Fe (II), Dye= 291 19h R1=H, R2=NO2, R3=SO3H, M= Cu (II), Dye= 292

19i Ar= Resorcinol, M= Fe (II), Dye=295, 19j Ar= Resorcinol, M= Cu (II), Dye=296,

19k Ar= Bis-Phenol S, M= Fe (II), Dye= 299 19l Ar= Bis-Phenol S, M= Cu (II), Dye= 300

19m Ar= Bis-Phenol A, M= Fe (II), Dye= 303 19n Ar= Bis-Phenol A,M= Cu (II), Dye= 304

Ar

OHHO

Ar

HO OH

Ar

Scheme 4.6, Synthesis of ligand acid dyes 18a-g and their Fe (II) and Cu (II) complexes (19a-n,

277-304)

159

NN

SO3H

H3C

OHNaNO2, HCl

-2 -(-5) oC

NN

SO3H

H3C

OH

N O

Zn + HClN

N

SO3H

H3C

OH

NH3

NaNO2, HCl

25-30 oC

NN

SO3H

H3C

O

N N

OH

R3

R2

12 3 4

17a-d

NaO3S

N

N

CH3

OH

N N

HO

R3

R2

Na2CO3/NaOH

10 -15 oC

Metalization60 -65 oC

HO3S

N

N

CH3

O

N N

Cr+3O

R3

R2

18a-dR1

R1

R1

17e-gNa2CO3/NaOH

10 -15 oC

N

N

H3C

HO

NN

N

N

CH3

OH

NN

SO3HHO3S

O

N

N

H3C

O

NNN

N

CH3

O

NN

O

SO3HHO3S

Cr+3Cr+3

60 -65 oC Metalization

18e-g

Cl

17-18a R1=R2=H, R3=Cl, Dye=277,

17-18b R1=R2=H, R3=NO2,Dye=281

17-18c R1=R2=H, R3=SO3H, Dye=285,

17-18d R1=H, R2=NO2, R3=SO3H, Dye=289,

17-18e Ar= Resorcinol, ,Dye=293,

17-18f Ar= Bis-Phenol S, Dye=297,

17-18g Ar= Bis-Phenol A, Dye=301,

19o R1=R2=H, R3=Cl, Dye= 278 19p R1=R2=H, R3=Cl, Dye= 282

19q R1=R2=H, R3=NO2, Dye= 286 19r R1=R2=H, R3=NO2, Dye= 290

19s Ar= Resorcinol, Dye=294, 19t Ar= Bis-Phenol S, Dye=298,

19u Ar= Bis-Phenol A, Dye=302

HO3S

N

N

CH3

O

N N

O

R3

R2

R1

O

N

N

CH3

O

NN N

N

H3C

O

NN

O

HO3S

SO3H

19o-r

19s-u

OHHO

Ar

Ar

Ar

HO OH

Ar

Scheme 4.7, Synthesis of ligand acid dyes 18a-g and their Cr (III) complexes (19o-u, 277-302)

160

Figure 4.31, FTIR spectrum of Iron complex of dye 18b (281).

1H-NMR and

13C-NMR spectra were taken for ligand dyes which showed characteristic signals

for different protons and carbons at different positions which evidenced the synthesis of dyes. In

case of compounds 18b (281) signal for hydroxyl group was absent due to exchangeable proton

with DMSO. The doublet signal of mutually coupled set of four protons of phenyl group

substituted with sulfonic group at present 7.95 and 7.68 ppm having coupling constant

respectively signals 8.6 Hz. The multiplet signal for one proton of aromatic ring of coupling

moiety is present at 7.83-7.90 ppm while the same ring bearing another single proton shows

signal at 8.07 ppm with coupling constant 2.35 Hz which evidenced the meta relationship with

another proton at the same ring. The methyl group present at pyrazolone ring exhibited singlet

signal at 2.20 ppm (Figure 4.32).

In 13

C-NMR spectrum the signal for methyl group is present at 12.14 ppm. There are ten signals

in the range 117.06-158.00 ppm for different carbon nuclei in the compound (Figure 4.33). In

this way other ligand acid dyes were confirmed from their respective 1H-NMR and

13C-NMR

spectra. When the 1H-NMR spectra of metal complex dyes were conducted they showed very

broad and distorted signals due to paramagnetic nature of metals used for complexation and the

so the NMR study of complexes was not fruitful for structure elucidation but in other words the

distorted broad signals proved the complexation when the 1H-NMR of ligands acid dyes and

complexes were compared.

161

Figure 4.32, 1H-NMR spectrum of ligand acid dye 18b (281).

Figure 4.33, 13

C-NMR spectrum of ligand acid dye 18b (281).

4.11.1 p-Chlorophenol dyes.

Four dye samples were prepared with p-chlorophenol. The first dye being un-metallized one and


was of 2:1 type. The detailed physical properties of p-chlorophenol dyes are given in Table-4.25.

162



4.34).The un-metallized dye 277 (18a) was an orange dye with λmax 460 nm and absorbance 2.3.

Its metallization with chromium had changed its color to yellowish red with λmax 470 nm and


0.3. On the other hand metallization of dye 277 (18a) with iron produced an olive brown dye

(dye 279) with λmax 440 nm and absorbance 1.1, showing a hypsochromic shift of 30 nm with a


While metallization of dye 277 (18a) with copper resulted in the formation of a reddish violet

dye (dye 280) with λmax 490 nm and absorbance 1.3. It showed a bathochromic shift of 30 nm


Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

277 HO3S

N

N

CH3

OH

N N

OH

Cl

C16H13Cl

N4O5S

Orange/

Reddish

Orange

360/0.9,

460/2.3 Water

278

HO3S

N

N

CH3

O

N N

O

Cl

HO3S

N

N

CH3

O

N N

O

Cl

Cr-

H+

C32H23Cl2

CrN8O10S2

Maroon/

Yellowish

Red

360/0.9,

470/2.0 Water

279

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

Fe O

Cl

C16H17Cl

FeN4O8S

Olive/

Olive

Brown

360/1.8,

440/1.1 Water

280

OH2

HO3S

N

N

CH3

O

N N

Cu-

O

Cl

C16H13Cl

CuN4O6S

Tan/

Reddish

Violet

360/1.1,

490/1.3 Water

163



4.11.2 p-Nitrophenol dyes.

Four dye samples were prepared with p-nitrophenol. The first dye was un-metallized one and the

other three were chromium, iron and copper complexes respectively. Chromium complex was of

2:1type. The detailed properties of p-nitrophenol dyes are given in Table-4.26.

164



4.34). The un-metallized dye 281 (18b) was an orange dye with λmax 480 nm and absorbance 3.1.

Its metallization with chromium had not changed its color but λmax to 470 nm and absorbance 1.8

(dye 282), showing a hypsochromic shift of 10 nm with a hypochromic effect of 1.3.

On the other hand metallization of dye 281(18b) with iron produced a yellowish brown dye (dye

283) with λmax 440 nm and absorbance 1.3, that showed a hypsochromic shift of 40 nm with a

hyperchromic effect of 1.8. While metallization of dye 281(18b) with copper resulted in the

formation of a reddish yellow dye (19d,dye 284) with λmax 460 nm and absorbance 2.3 , showing

a hypsochromic shift of 20 nm with a hypochromic effect of 0.8.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

281 HO3S

N

N

CH3

OH

N N

OH

NO2

C16H13N5

O7S

Dark

Brown /

Reddish

Orange

480/3.1 Water

282

HO3S

N

N

CH3

O

N N

O

NO2

HO3S

N

N

CH3

O

N N

O

NO2

Cr-

H+

C32H23Cr

N10O14S2

Dark

Brown/

Reddish

Orange

470/1.8 Water

283

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

Fe O

NO2

C16H17Fe

N5O10S

Gray/

Yellowish

Brown

440/1.3 Water

284

OH2

HO3S

N

N

CH3

O

N N

Cu-

O

Cl

C16H13Cu

N5O8S

Tan/

Reddish

Yellow

460/2.3 Water

165



4.11.3 Phenol-4-sulphonic acid dyes.

Four dyes were prepared with phenol-4-sulphonic acid. The first dye was un-metallized one and


was 2:1 type. The detailed properties of phenol-4-sulphonic acid dyes are given in Table-4.27.

166

Table-4.27, Physical properties of dyes 285-288


4.25). The un-metalized dye 285 (18c) was a yellowish orange dye with λmax 460 nm and

absorbance 2.7. Its metallization with chromium had changed its color to reddish orange with

λmax 480 nm and absorbance 1.0 (dye 286, 19q). It showed a bathochromic shift of 20 nm with a


On the other hand metallization of dye 285 (18c) with iron produced a yellowish brown dye (dye

287, 19e) with λmax 430 nm and absorbance 1.58, showing a hypsochromic shift of 30 nm with a

hypochromic effect of 1.12. While metallization of dye 285 (18c) with copper resulted in the

formation of a reddish orange dye (dye 288, 19f) with λmax 460 nm and absorbance 2.05,

showing a hypochromic effect of 0.65.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubility

285 HO3S

N

N

CH3

OH

N N

OH

SO3H

C16H14N4

O8S2

Orange/

Yellowish

Orange

460/2.7 Water

286

HO3S

N

N

CH3

O

N N

O

SO3H

HO3S

N

N

CH3

O

N N

O

SO3H

Cr-

H+

C32H25Cr

N8O16S4

Tan/

Reddish

Orange

480/1.0 Water

287

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

Fe O

SO3H

C16H18Fe

N4O11S2

Olive

Brown/

Yellowish

Brown

430/1.58 Water

288

OH2

HO3S

N

N

CH3

O

N N

Cu-

O

SO3H

C16H14Cu

N4O9S2

Brown/

Yellowish

Orange

460/2.05 Water

167

Figure 4.36; UV-Visible Spectra-22 of dyes 285-288(7648-umd = dye 285,


4.11.4 2-Nitro-4-sulphophenol dyes.

Four dyes were prepared with 2-nitro-4-sulphophenol. The first dye was un-metallized one and


was 2:1 type. The detailed properties of 2-nitro-4-sulphophenol dyes are given in Table-4.28.

168



4.36). The un-metallized dye 289 (18d) was a reddish orange dye with λmax 520 nm and

absorbance 3.3. Its metallization with chromium had changed its λmax to 490 nm and absorbance

5.7 (dye 290, 19r), showing a hypsochromic shift of 30 nm with a hyperchromic effect of 2.4.On

the other hand metallization of dye 289 (18d) with iron produced a yellowish brown dye (dye



While metallization of dye 289 (18d) with copper resulted in the formation of a reddish brown

dye 292 (19h) with λmax 500 nm and absorbance 3.0. It showed a hypsochromic shift of 20 nm


Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax(nm)/

Absorba-

nce

Solubiliity

289 HO3S

N

N

CH3

OH

N N

OH NO2

SO3H

C16H13N5

O10S2

Orange/

Reddish

Orange

520/3.3 Water

290

HO3S

N

N

CH3

O

N N

O

HO3S

N

N

CH3

O

N N

OCr-

NO2

SO3H

NO2

SO3H

H+

C32H23Cr

N10O20S4

Brown/

Reddish

Orange

490/5.7 Water

291

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

Fe O NO2

SO3H

C16H17Fe

N5O13S2

Gray/

Yellowish

Orange

470/3.4 Water

292

OH2

HO3S

N

N

CH3

O

N N

Cu-

O NO2

SO3H

C16H13Cu

N5O11S2

Tan/

Reddish

Brown

500/3.0 Water

169

Figure 4.37; UV-Visible Spectra-23 of dyes 289-292(11948 -umd = dye 289,


4.11.5 Disazo Resorcinol Dyes.

Four disazo dyes were prepared with resorcinol. The first dye was un-metallized one and the

other three were chromium, iron and copper complexes respectively. Chromium complex was of

bis 2:1 type. The schemes for the preparation of resorcinol disazo dyes had already been given as

schemes 4.6 and 4.7. The detailed properties of disazo resorcinol dyes are given in Table-4.29

170


Here Ar – represents benzene-4-sulphonic acid.


4.39). The un-metallized dye 293(18e) was a reddish orange dye with λmax 460 nm and

absorbance 1.03. Its metallization with chromium had changed its λmax to 500 nm and absorbance

0.36 (dye 294, 19s). It showed a bathochromic shift of 40 nm with a hypochromic effect of 0.67.

On the other hand metallization of dye 293 (18e) with iron produced a yellowish orange dye 295

(19i) with λmax 440 nm and absorbance 0.45, showing a hpsochromic shift of 20 nm with a


While metallization of dye 293 (18e) with copper resulted in the formation of a yellowish brown

dye 296 (19j) with λmax 480 nm and absorbance 0.3, showing a bathochromic shift of 20 nm with


Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

293 Ar-

N

N

CH3

OH

N N

OH OH

Ar-

N

N

CH3

OH

NN

C26H22N8

O10S2

Orange/

Reddish

Orange

460/1.03 Water

294

Ar-

N

N

CH3

O

N N

O O

Ar-

N

N

CH3

O

NN

Ar-

N

N

CH3

O

N N

O O

Ar-

N

N

CH3

O

NN

Cr-

Cr-

H+

2

C52H37Cr2

N16O20S4

Brown/

Reddish

Orange

360/0.5,

500/0.36 Water

295

OH2

Ar-

N

N

CH3

O

N N

O O

Ar-

N

N

CH3

O

NN

OH2OH2

OH2

Fe

OH2OH2

Fe

C26H30Fe2

N8O16S2

Brown/

Yellowish

Orange

440/0.45 Water

296

OH2

Ar-

N

N

CH3

O

N N

O O

Ar-

N

N

CH3

O

NN

OH2

Cu-Cu

-

C26H22Cu2

N8O12S2

Tan/

Yellowish

Brown

480/0.31 Water

171

Figure 4.38; UV-Visible Spectra-24 of dyes 293-296 (4841 umd = dye 293,


4.12 The Dyeing Properties of p-Substituted Phenols and Resorcinol Dyes

The dyeing properties of p-substituted phenols and resorcinol dyes have been found to be very

attractive. Almost all properties have been found to be of very high value (4-5). However,

chromium complexes have found to be the best ones and un-metallized dye-ligands with low

values as per expectation due to the presence of free hydroxyl groups. The dyeing properties of

these dyes are given in Table-4.30.

172

Table-4.30; The Dyeing Properties of p-Substituted Phenols and Resorcinol Dyes.

Dye

#

2%Shade on

Leather

5%Shade on

Leather Penetration

Washing

Fastness

Light

Fastness

Perspiration

Fastness


278 Reddish Orange Maroon 4 3-4 4-5 4-5


280 Yellowish Orange Reddish Brown 3 3-4 3-4 4-5

281 Orange Yellowish Orange 2 2-3 2-3 3-4

282 Reddish Orange Tan 4 3-4 4-5 4-5


284 Yellowish Orange Yellowish Brown 3 3-4 3-4 4-5


Orange 3 3-4 2-3 3-4

286 Light yellowish Red Dark Yellowish

Red 4 3-4 4-5 4-5

287 Light Olive Dark Olive 5 4-5 5 5

288 Light Yellowish

Orange Yellowish Orange 4 3-4 3-4 4-5

289 Tan Yellowish Brown 3 3-4 3-4 3-4

290 Pink Reddish Tan 4 3-4 4-5 4-5

291 Olive Brown Dark Olive 5 4-5 5 5


293 Light Brown Dark Reddish Brown 2 2-3 2-3 3-4

294 Light Tea Pink Tea pink 4 3-4 4-5 4-5

295 Olive brown Brown 5 4-5 5 5

296 Beige Tan 3 3-4 3-4 4-5

The data given in Table -4.30 are supported by Shade-Card-4a and b

173

Shade Card-4, part-a

174

Shade Card-4, part-b

A mutual comparison of shades of p-substituted phenols and resorcinol dyes is presented in

Shade Comparison 13-16, for un-metallized, chromium, iron and copper complexes

respectively.

175

Shade comparison-13

Comparison of Un-Metallized Dyes of p-Substituted Phenols and Resorcinol Dyes

Dye # Phenol 2% Shade 5% Shade

277 p-Chloro-Phenol

281 p-Nitro Phenol

285 p-Sulpho-Phenol

289 o-Nitro-p-Sulpho-Phenol

293 Resorcinol

Almost all the un-metallized p-substituted phenols and resorcinol dyes (Shade comparison-13)

have been found to be different; both in 2% and 5% dyed leathers, along with a variation of

depth of shades. This can be attributed to the difference of chromophoric systems in all these

dyes. However, it is clear from shades that this difference is due to the difference of p-

substituents in different phenols. All of the phenol homologue shades were dark and redder

except p-sulphophenol. The variation of the depth can be attributed to the participation of

peripheral group’s variation in different phenols. Resorcinol dyes were disazo ones; hence these

were clearly different from the other phenolic ones.

176

Shade comparison-14

Comparison of Chromium Metalliezd Dyes of p-Substituted Phenols and Resorcinol.


278 p-Chloro-Phenol

282 p-Nitro Phenol

286 p-Sulpho-Phenol

290 o-Nitro-p-Sulpho-

Phenol

294 Resorcinol

All chromium-metallized p-substituted phenols and resorcinol dyes (Shade comparison-14)

have been found to be different; both in 2% and 5% dyed leathers, along with a variation of

depth of shades. This can be attributed to the difference of chromophoric systems in all such

dyes. However, it is clear from shades that this difference is due to the difference of p-substitu-

ents in different phenols. All of the phenol homologues had dark and redder shades except p-sul-

phophenol. The variation of the depth can be attributed to the participation of peripheral groups

variation in different phenols. Both nitrophenols had similar shades with yellowish red tone.

Resorcinol dyes are disazo ones, hence these are clearly different from other phenolic ones as

these are bis-metal complexes.

177

Shade comparison-15

Comparison of Iron Metaliezd Dyes of p-Substituted Phenols and Resorcinol.


279 p-Chloro-Phenol

283 p-Nitro Phenol

287 p-Sulpho-Phenol

291 o-Nitro-p-Sulpho-

Phenol

295 Resorcinol

Almost all iron-metalized phenol and resorcinol dyes (Shade comparison-15) are found to be

similar (olive); both in 2% and 5% dyed leathers, along with a variation of depth of shades.

However, it is clear from shades that the depth difference is due to the difference of p-

substituents in different phenols. All the phenol homologues had dark and redder shades except

p-sulphophenol. Both nitro phenols had similar shades with yellowish tone. Resorcinol dyes are

disazo ones hence, these are clearly different from phenolic ones as these being Bis-metal

complexes.

178

Shade comparison-16

Comparison of Copper Metaliezd p-Substituted Phenols and Resorcinol Dyes.


280 p-Chloro-Phenol

284 p-Nitro Phenol

288 p-Sulpho-Phenol

292 o-Nitro-p-Sulpho

Phenol

296 Resorcinol

Almost all copper-metalized phenolic and resorcinol dyes (Shade comparison-16) have been

found to be different; both in 2% and 5% dyed leathers, along with a variation of depth of

shades. This can be attributed to the difference of chromophoric systems in all these dyes.

However, it is clear from shades that this difference is due to the difference of p-substituents in

different phenols. All of the phenol homologues had dark and redder shades except p-sulph-

ophenol. Both nitro phenols had similar shades with yellowish red tone. Resorcinol dyes were

disazo dyes, hence these were clearly different from phenolic ones as these were bis-metal

complexes.

4.13 Synthesis of Bisphenol Dyes.

In this series a total number of 8 dyes were prepared and for this purpose two different

bisphenol-S (BPS) and bisphenol-A (BPA) were used as couplers.

179

4.13.1 Bisphenol-S Dyes.

Four dyes were prepared with bisphenol-S (4,4־-dihydroxy biphenyl sulfone). The first dye was

un-metallized one and the three were bis chromium, iron and copper complexes respectively.

Chromium complex was 2:1 type. The synthesis of bisphenol dyes was given in Schemes-4.6

and 4.7. The physical properties of bisphenol-S are presented in Table-4.31.


Here Ar –

represents phenyl-4-sulphonic acid

The UV-Visible data presented inTable-4.31 are supported by UV-Visible Spectra-25 (Figure

4.40).

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

297 OH

N

N

CH3

OH

NN Ar-

N

N

CH3

OH

N N

OH

SO

Ar-

O

C32H26N8

O12S3

Orange/

Reddish

Orange

420/2.3 Water

298 O

N

N

CH3

O

N NAr-

N

N

CH3

O

NN

O

SO

Ar-

O

O

N

N

CH3

O

NN Ar-

N

N

CH3

O

N N

O

SO

Ar-

O

Cr-

Cr-

H+

2

C64H46Cr2

N16O24S6

Beige/

Yellowish

Orange

410/2.5 Water

299 OH2

OH2

OH2

OH2OH2OH2

O

N

N

CH3

O

NN Ar-

N

N

CH3

O

N N

O

SO

Ar-

O

Fe

Fe

C32H34Fe2

N8O18S3

Brown/

Reddish

Brown

360/2.8,

410/3.6 Water

300 OH2

OH2

O

N

N

CH3

O

NNN

N

CH3

O

N N

O

SO

O

Cu-

Cu-Ar

-

Ar-

C32H29Cu2

N8O14S3

Tan/


180



The un-metallized dye 297 was a reddish orange dye with λmax 420 nm and absorbance 2.3. Its

metallization with chromium had changed its color to yellowish orange with λmax 410 nm and

absorbance 2.5 (dye 298), showing a hypsochromic shift of 10 nm with a hyperchromic effect of

0.5.On the other hand metallization of dye 297 (18f) with iron produced a reddish brown dye

(dye 299,19k) with λmax 410 nm and absorbance 3.6, showing a hypsochromic shift of 10 nm

with a hyperchromic effect of 1.1.

While metallization of dye 297 (18f) with copper resulted in the formation of a yellow dye (dye

300,19l) with λmax 370 nm and absorbance 1.6, showing a hypsochromic shift of 50 nm with a


181

4.13.2 Bisphenol-A Dyes.

Four disazo dyes were prepared with Bisphenol-A (4, 4־-dihydroxy biphenyl propane). The first

dye was un-metallized one and the other three were chromium, iron and copper bis-metal

complexes respectively. Chromium complex was of 2:1 type. The detailed properties of disazo

BPA dyes are given in Table-4.32.



4.41). The un-metallized dye 301(18g) was a yellowish orange dye with λmax 450 nm and

absorbance 2.7. Its metallization with chromium had changed its color to yellowish orange with

λmax 480 nm and absorbance 1.5 (dye 302, 19u). It showed a bathochromic shift of 30 nm with a

hypochromic effect of 1.2. On the other hand metallization of dye 301 (18g) with iron produced

a reddish brown dye 303 (19m) with λmax 440 nm and absorbance 2.3, showing a hypsochromic

shift of 10 nm with a hyochromic effect of 0.4.

Dye # Dye Structure

Molecular

formula

(Calc.)

Powder/

Solution

Color

λmax (nm)/

Absorba-

nce

Solubility

301 OH

N

N

CH3

OH

NN Ar-

N

N

CH3

OH

N N

OH

Ar-

CH3CH3

C35H32N8

O10S2

Brown/

Yellowish

Orange

450/2.7 Water

302 O

N

N

CH3

O

N NAr-

N

N

CH3

O

NN

O

Ar-

CH3CH3

O

N

N

CH3

O

NN Ar-

N

N

CH3

O

N N

O

Ar-

CH3CH3

Cr-

Cr-

H+

2

C70H58Cr2

N16O20S4

Tan/

Reddish

Orange

360/1.4,

480/1.5 Water

303 O

N

N

CH3

O

NNN

N

CH3

O

N N

O

CH3CH3

OH2

OH2OH2

Fe

OH2OH2

OH2

Fe

Ar-

Ar-

C35H40Fe2

N8O16S2

Grey/

Reddish

brown

370/1.7,

440/2.3 Water

304 OH2

OH2

O

N

N

CH3

O

NN Ar-

N

N

CH3

O

N N

O

Ar-

Cu-

Cu-

CH3CH3

C35H32Cu2

N8O12S2

Dark

Brown /

Yellowish

Orange

450/1.5 Water

182

While metallization of dye (dye 301,18g) with copper resulted in the formation of a yellowish

orange dye (dye 304,19n) with same λmax 450 nm and absorbance 1.5, showing a hypochromic

effect of 0.2.

Figure 4.40; UV-Visible Spectra-26 of dyes 301-304 (48BPA-umd = dye 301,

48BPA-Cr = dye 302, 48BPA-Fe = dye 303 and 48BPA-Cu = dye 304)

4.14 The Dyeing Properties of Bis-Phenol Dyes

The dyeing properties of bisphenols dyes have been found to be very good. Almost all properties

have been found to be of very high value (4-5).The dyes with bisphenol-A has been found to be

much darker as compared to the dyes of bisphenol-S. This can be attributed to the

n→п*electronic transitions occurring in sulphone group of Bisphenol-S. However, chromium

and copper complexes were found to be the best ones and un-metallized dye-ligands with low

values as per our expectation due to the presence of free hydroxyl groups. The dyeing properties

of these dyes are presented in Table -4.33.

183

Table-4.33; Dyeing Properties of Bis-Phenol Dyes

The data presented in Table-4.33 are supported by Shade Card-5.

Dye

#

Shade on

Leather

5%Shade on

Leather Penetration

Washing

Fastness

Light

Fastness

Perspiration

Fastness

297 Greenish Beige Reddish Beige 2 2-3 2-3 3-4

298 Beige Dark Beige 5 4-5 4-5 4-5

299 Beige Dark Reddish

Beige 4 3-4 4-5 4-5

300 Greenish Beige Reddish Beige 5 4-5 5 5

301 Golden Yellow Yellowish Orange 3 3-4 3-4 4-5

302 Reddish Brown Maroon 2 2-3 2-3 3-4

303 Olive Yellowish Brown 4 3-4 4-5 4-5

204 Yellowish

Orange Reddish orange 5 4-5 5 5

184

Shade Card-5.

A mutual comparison of shades of bis-phenol dyes is presented in Shade Comparisons 17-20,

for un-metallized dyes, chromium, iron and copper complexes respectively.

185

Shade Comparison -17

COMPARISON OF UN-METALLIZED BISPHENOLS DYES

Dye # Bisphenol 2% Shade 5% Shade

297 Bisphenol-S

301 Bisphenol-A

As it is clear from Shade-Comparison-17, among the un-metallized Bisphenol dyes, the dye

with Bisphenol-A had a high color value while Bisphenol-S dye gave a low color yield on

leather. This difference can be attributed to the participation of sulphone group present in

Bisphenol-S.

Shade Comparison-18

COMPARISON OF CHROMIUM METALLIZED BIS-PHENOLS DYES.


298 Bisphenol-S

302 Bisphenol-A

It is very interesting that chromium metallized bisphenol dyes had greater color value than their

parent un-metallized bisphenol dyes (Shade Comparison-18), The dye with bisphenol-A had a

high color value while bisphenol-S dye gave a lighter and low color yield on leather along with

much redder effect. This difference can be attributed to the participation of sulphone group in

Bisphenol-S.

186

Shade Comparison-19

COMPARISON OF IRON METALLIZED BIS-PHENOL DYES.


299 Bisphenol-S

303 Bisphenol-A

It is clear from Shade Comparison-19 that iron metalized bisphenol dyes had greater color

value than their parent un-metallized bisphenol dyes. These dyes are much greener as per our

expectation. The iron dye with bisphenol-S had a low color value while bisphenol-A dye gave a

darker and high color yield on leather along with a much redder effect. This difference can be

attributed to the participation of sulphone group in bisphenol-S.

Shade Comparison-20

COMPARISON OF COPPER METALLIZED BIS-PHENOLS DYES.


300 Bisphenol-S

304 Bisphenol-A

Shade Comparison-20 shows that copper metallized bisphenol dyes had greater color value than

their parent un-metalized bisphenol dyes. These dyes are much redder as per our expectation.

The copper dye with bisphenol-A had a high color value while bisphenol-S dye gave a lighter

187

and low color yield on leather along with a much redder effect. This difference can be attributed

to the participation of sulphone group in bisphenol-S.

4.15 Comparison of Shades of Present Work Dyes With National and International

Standards.

This part of my research work is related to the comparison of shades of the dyed leather swatches

with shades of national and international standards. These include two types of matchings which

are , comparison with pantone matching system and comparison with well known leather dyes.

4.15 A- Comparison with Pantone Matching System.

This comparison included matching of our 2% and 5% dyed leather swatch shades with Pantone

Matching System (PMS)215

numbers. The results are presented in Tables-4.34-4.38 for each

series of dyes with their relevant matching PMS numbers.

Table-4.34 Comparison of the naphthol-AS dyes shades with PMS numbers.

Dye #

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

Of the dye Dye #

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

of the dye

201 488 489 202 501 515

203 4525 465 204 692 694

205 1525 154 206 1535 1545

207 464 462 208 1935 201

209 1605 160 210 1685 1815

211 168 175 212 176 202

213 187 730 214 696 697

215 4495 463 216 194 195

217 692 693 218 696 704

219 140 1265 220 1805 1815

221 691 693 222 182 183

223 4525 4515 224 488 489

225 480 723 226 187 188

227 455 4485 228 1767 1765

188

Table-4.35; Comparison of the pyrazolone-pyrazolone dyes shades with PMS numbers.

Table-4.36; Comparison of the naphthol dyes shades with PMS numbers.

Dye #

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

of the dye Dye #

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

of the dye

257 1625 157 258 1815 168

259 1265 159 260 158 174

261 488 161 262 672 1955

263 111 163 264 163 167

265 182 165 266 217 204

267 5875 167 268 489 487

269 410 169 270 409 411

271 408 171 272 431 425

273 209 173 274 257 229

275 161 175 276 409 411

Dye #

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

of the dye Dye #

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

of the dye

229 5875 159 230 1205 139

231 581 5835 232 602 617

233 698 718 234 726 167

235 614 617 236 461 124

237 135 1505 238 143 144

239 155 1255 240 1205 155

241 141 1525 242 110 124

243 1265 1255 244 3975 399

245 141 167 246 1205 146

247 4515 465 248 611 125

249 124 1525 250 139 154

251 133 161 252 152 612

253 607 4515 254 607 602

255 5875 5855 256 587 393

189

Table-4.37 Comparison of p-substituted phenol & resorcinol dyes shades with PMS numbers.

Dye#

PMS # for

2%Shade

of the dye

PMS # for

5%Shade

of the dye Dye#

PMS # for

2% Shade

of the dye

PMS # for

5% Shade

of the dye

277 157 1595 278 717 168

279 455 4485 280 157 1675

281 157 150 282 804 180

283 1255 4485 284 143 1525

285 148 142 286 163 164

287 155 157 288 600 145

289 486 167 290 1625 159

291 146 147 292 153 471 2x

293 154 1685 294 435 437

295 4515 1265 296 Cool Grey-2 479

Table-4.38 Comparison of the bisphenol dyes shades with PMS numbers.

Dye #

PMS # for

2%Shade

of the dye

PMS#for,5%

Shade

of the dye

Dye#

PMS # for

2%Shade

of the dye

PMS # for

5%Shade

of the dye

297 155 1205 298 607 458

299 5875 5855 300 427 Warm Grey-2

301 157 716 302 173 174

303 456 146 304 157 167

4.15 B- Comparison with well known Leather Dyes.

The comparison of the synthesized dyes with famous leather dyes manufacturers like Clariant

Dyes216

(Melioderm Dyes/Derma Dyes), Chika Dyes217

(Dermacron Dyes), Colortech dyes218

and

a local leather dye manufacturer Sardar Dyes219

(Leatherol Dyes) has been attempted. It is a

matter of interest to mention here that the dyes of above mentioned companies are mixtures of

several dyes (usually 3 to 5 components mixture). The requisite dyes have been formulated either

in very high or low ratios to get a typical/desired shade. The mixing ratio of a three component

dye may be very high as 45:30:25 or as low as 95:4:1. The dyes used in very small ratio are

usually termed toners. However dyes obtained during the present work were single components.

Several of these have exactly the same shade while others are nearest to the dyes of the above

190

mentioned manufacturers. However the new dyes may also be easily formulated to get the

desired shades. A few of these are presented in Table-4.39 and 4.40.

Table-4.39 Comparison of my dyes with well known National & International leather dyes.

Sr.# Dye # Nearest International Dye Nearest Local Dye

1

203,223,231,

232,240,247,

252,253,254,

255,268,268,

297,299,300

MeliodermHFBeigeDp,

Dermacron Beige 2401,

Dermacron Beige ET,

Dermacron Beige EY,

Dermacron Beige KR,

Colortech Beige ET

Leatherol Beige 2401

2

229,230,236,

237,241,242,

249,250,254,

261,281,284,

285,288

Melioderm Yellow GLp,

Dermacron FastYellowRL,

Dermacron Fast YellowGL,

Dermacron FastYellow4R ,

Colortech Yellow GR

Leatherol Yellow 2F

3 211,,219,227,

250,251,283,

303

Melioderm Brown 2GLp,

Dermacron Brown HGT,

Dermacron Brown J,

Dermacron Brown RD,

Colortech Brown NG

Leatherol Brown 2G

4

205,209,220,

237,241,249,

260,261,264,

286,292,293,

304

Melioderm Brown HGTp,

Dermacron Brown HNR,

Dermacron Brown NR,

Dermacron Brown EB,

Colortech Brown NK

Leatherol Brown HGP

5

206,207,210,

215,216,219,

227,258,259,

269,271,272,

273,275,276,

278,279,282,

283,291,295

Melioderm Brown HF,

Melioderm Deep Brown Fp,

Dermacron Brown HRS,

Dermacron Brown HG,

Dermacron Brown FBT,

Dermacron Brown SRH/C,

Colortech Brown DG

Colortech Brown SG

Leatherol Brown 1288,

Leatherol Brown 1289

6

203,215,227,

235,243,255,

259,263,267,

272,279,287,

303

Melioderm Olive GBp,

Melioderm Green HFp,

Dermacron Olive Brown K,

Dermacron Olive Brown GB,

Dermacron Brown HGT,

Colortech Olive Brown GB

Leatherol Olive 2402

7

206,210,214,

216,226,258,

277,278,293,

202

Melioderm Bordeaux Vp,

Dermacron Bordeaux NB,

Dermacron Bodeaux R,

Dermacron Brown B2C,

Colortech Red E

Leatherol Bordeaux 2430

191

Table-4.40 Comparison of my dyes with well known National & International leather dyes.

Sr.# Dye # Nearest International Dye Nearest Local Dye

1 206,214,218,

226,262,266,

274

Derma Violet 2B,

Derma Violet 3B,

Dermacron Violet 4BS,

Colortech Violet 4BN

Leatherol Violet 3B

2 202,214,222,

226,228,262,

274,302

Derma Violet 6677,

Dermacron Violet 3R,

Dermacron Violet L,

Colortech Violet RB

Leatherol Violet 3R

3

204,205,209,

213,219,237,

238,242,245,

246,250,261,

264,268,281,

284,292,301,

304

Melioderm Orange 2GLp,

Dermacron Fast Orange 2GL,

Dermacron Fast Orange TGL,

Dermacron Fast Orange G,

Colortech Orange 2G

Leatherol Orange 2G

4

237,241,249,

261,264,282,

286,289,290,

292,201,304

Derma Orange RSN,

Dermacron Orange GS,

Dermacron Orange PR,

Dermacron Orange RL,

Coloetech Orange GS

Leatherol Orange RSN

5

208,212,216,

233,257,261,

264,281,282,

286,289,290,

292,201,302,

304

Derma Red 2201,

Melioderm Red HF Gp,

Dermacron Red HF,

Dermacron Red RSR,

Dermacron Red 2R,

Colortech Red NG

Leatherol Red 2201

6 261,264,282,

286,289,290,

292,304

Melioderm Brilliant Red MFp,

Dermacron Scarlet GL,

Dermacron Scarlet GLS,

Colortech Red EN

Leatherol Scarlet GLS

7 269,270,272,

276

Melioderm Grey GBp,

Melioderm Grey LLp,

Dermacron Grey N2B,

Dermacron Navy C 200%,

Dermacron Grey BL,

Colortech Grey LNG

Colortech Grey EGL

Leatherol Grey BL

192

SUMMARY

The main aim of the present work was to synthesize novel pyrazole derivatives and their dyes.

This was achieved by conducting multistep synthesis, including reactions like nitrosation,

reduction, diazotization, coulpling and metallization. Thus 1(p-sulfophenyl)-3-methyl-2-

pyrazoline-5-one was nitrosated and then reduced to an amine hydrochloride. The hydrochloride

was diazotized to produce a novel diazonium compound. The exact structure of the diazonium

compound was confirmed through its XRD and was found to be a diazoxide. This diazo

compound was coupled with various well known couplers to produce new dyes capable of

metallization. It is noteworthy to mention here that all the couplers selected were blocked at

position para so as to facilitate coupling of diazo at position ortho to the hydroxyl groups of

couplers.

In this work five series of dyes were prepared. These included:

i - Naphthol-AS series

ii - Pyrazolone series

iii - Naphthol series

iv - p-Substituted phenol and Resorcinol series

v - Bisphenol series

Each series is presented with a general structure in ―H‖ form as below:

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

O

O

NHM

R1 R2

R3

i-Naphthol-AS series

193

N

N

CH3

O

HO3SN N

N

N

R

O

R2

R1

R3

OH2OH2

OH2

M

ii- Pyrazolone series

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

M O R3

R1

R2

iii- Naphthol series

OH2OH2

OH2

HO3S

N

N

CH3

O

N N

M O

R1

R

iv- p-Substituted phenol series

OH2OH2

OH2

OH2OH2OH2

O

N

N

CH3

O

NN Ar-

N

N

CH3

O

N N

O

SO

Ar-

O

M

M

v- Bisphenol series (BPS-dye shown, where Ar- is p-sulfophenyl group)

194

The first series included naphthol-ASA, naphthol-ASBS, naphthol-ASD, naphthol-AS E,

naphthol-ASLC, naphthol-ASOL and naphthol-ASPH as couplers. In the 2nd

series pyrazolones

like 4-SPMP, SPCP, PMP, PTMP, 3-ClPMP, 3-SPMP and 2,5diClSPMP were used as couplers.

In the 3rd

series 5 different naphthols namely β-naphthol, Schaeffer’s Acid, R-Acid, H-Acid and

N-phenyl J-Acid were used as couplers. While the 4th

series included p-chlorophenol,

p-nitrophenol, phenol-4-suphonicAcid, 2-nitrophenol-4-suphonic Acid and resorcinol as

couplers. Similarly the couplers used in bisphenol series were bisphenol-S and bisphenol-A. The

general synthetic scheme was as under:

195

+ Na NO2 HCl+ + NaCl H2O+

+ Zn HCl+ + ZnCl2 H2O+

+ NaCl H2O+N

+

N

N

N

CH3

O-

O3S

N

N

CH3

ON

OH

HO3S

-Na

+

0 - 5 oC

(Nitrosation)

(Reduction)

(Diazotization)

144155

145146

146 147

HO3SN

N

CH3

OH

HO3SN

N

CH3

ON

OH

100 - 105 oCHO3S

N

N

CH3

OHNH3Cl

-

HO3S

N

N

CH3

OHNH3Cl

-+

+

NaNO2 + HCl

- 5 - 0 oC

N+

N

N

N

CH3

O-

O3S-

Na+

+

CH2

CH2OH N

N

N

N

CH3

OH

O3SCH2

CH2OHnaphtholic/phenolic coupler

(Coupling)

Na+ -

-Na

+

N

N

N

N

CH3

OH

O3SCH2

CH2OH

(Metallization) -Na

+

OH2

OH2

OH2

N

N

N

N

CH3

O

O3SCH2

CH2O

M

General Scheme; General synthetic scheme for the preparation of all dyes.

In the present work a total number of 104 dyes were synthesized and their fastness properties

were evaluated by application on cow crust. Most of the dyes had very good properties.Several

of these dyes had exactly the same shade as that of commercial dyes while other can be easily

formulated to get the desired shades as mentioned in National and International shade

comparisons. Although in this work 104 new dyes had been synthesized yet it is the opening of a

new era of scientific research and a lot work can be done in future.

196

FUTURE PROSPECTS

In the present work, as mentioned earlier, 2-pyrazoline-5-one have been used first time as a diazo

component containing an azo group at position 4 of pyrazoline ring. For this purpose the diazo of

SPMP has been synthesized and used as active component (amine component). Similarly other

pyrazolones like PMP, PTMP and SPCP may also be employed in the same manner. Several

other pyrazolones can also be exploited in the future.

The components used as couplers were various types of naphthols and phenols. Several other

naphthols, phenols and other couplers like acetoacetanilides and amines may also be used in the

future projects.

In this research work only chromium, iron and copper metal complexes has been prepared and

used as leather dyes. In future other metals can also be checked for their metallization (complex

formation).

While in the present work only acid dyes has been synthesized but in the future work other types

of dyes like azoic, reactive, disperse, substantive and even food dyes can also be synthesized and

evaluated.

In short there are tremendous opportunities to utilize these scaffolds for the custom build a vast

numer of dyes (metallized or not).

197

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