Std.XII 2022 : Chemistry Vidyalankar

XII.22/Chem/Set II/Ch.12/Pg.129

CH3 C

H

OCH3 C CH3

O

C O

C O( )

Syllabus : 12.1 Introduction 12.2 Classification of aldehydes, ketones and

carboxylic acids 12.3 Nomenclature of aldehydes, ketones and

carboxylic acids 12.4 Preparation of aldehydes and ketones

12.5 Preparation of carboxylic acids 12.6 Physical properties 12.7 Polarity of carbonyl group 12.8 Chemical properties of aldehydes and ketones 12.9 Chemical properties of carboxylic acids

MODULE 1 MODULE OVERVIEW

12.1 Introduction

12.2 Classification of aldehydes, ketones and carboxylic acids 12.2.1 Classification of aldehydes 12.2.2 Classification of ketones 12.2.3 Classification of carboxylic acids

12.3 Nomenclature of aldehydes, ketones and carboxylic acids 12.3.1 Nomenclature of aldehydes and carboxylic acids 12.3.2 Trivial and IUPAC names of ketones

12.4 Preparation of aldehydes and ketones 12.4.1 General methods of preparation of aldehydes and ketones

a. From alcoholsi. By oxidation of alcoholsii. By dehydrogenation of alcohols

b. From hydrocarbonsi. By ozonolysisii. By hydration of alkynes

1. What is a carbonyl group? [1M] A. Carbonyl group: A functional group in which a carbon atom is attached to an oxygen

atom by a double bond and remaining two valencies of carbon atom are free is called

a carbonyl group and represented as .

Carbonyl group is present in aldehydes and ketones.

2. What are carbonyl compounds? [1M]

A. The organic compounds containing a carbonyl group are called carbonyl

compounds. For example, (acetaldehyde) , (acetone)

As carbonyl group is common in aldehydes and ketones, their methods of preparation and properties show similarities.

Std.XII - 2022 : Chemistry

Ch.12:Aldehydes, Ketones & Carboxylic Acids

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(130) Vidyalankar : Std. XII - Chemistry


C O

C

O

OH

3. What are carboxylic acids? [1M]

A. The organic compounds containing as the functional group are called

carboxylic acids. The COOH group which itself is made up of a carbonyl group

and a hydroxyl group (OH) is called carboxyl group (carbo from carbonyl

and xyl from hydroxyl).

4. Explain the classification of aldehydes. [3 M]

A. Aldehydes are classified on the basis of nature of carbon skeleton bonded to ( ) group into aliphatic and aromatic aldehydes.

i. Aliphatic aldehydes: a. The compounds in which the CHO group (formyl group) is attached directly

to sp3 hybridized carbon atom, that is saturated carbon atom are called aliphatic aldehydes.

b. Formaldehyde, HCHO is also classified as aliphatic aldehyde though CHO group is not attached to any carbon.

e.g. CH3 CHO CH3CH2CHO Acetaldehyde Propionaldehyde c. General formula: , where R = H or alkyl group.

ii. Aromatic aldehydes: The compounds in which CHO group is attached directly

to an aromatic ring are called aromatic aldehydes. e.g.

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Notes on Aldehydes, Ketones & Carboxylic Acids (131)


3CH CH CHO

CH3

3 2 2 2CH CH CH CH C H

O

3 2 2CH CH CH CH C

H

O

CH3

3 2CH CH CH C

H

O

OH

3CH CH C

H

O

Cl

Nomenclature of Aldehydes :

(A) Common System : (1) The names of aldehydes are derived from the common names of acids. (2) The suffix ‘ic acid’ of an acid is replaced by ‘aldehyde’. (3) The positions of the substituents in the molecule are indicated by Greek letters , , , etc. starting

from the carbon atom attached to the carbonyl group. E.g. O || C C C C C

(B) IUPAC System : (1) The longest carbon atoms chain containing aldehyde carbon atom is selected as a parent

hydrocarbon. (2) ‘e’ of the alkane is replaced by ‘al’. (3) The position (locant) of aldehyde group need not be mentioned since it is always at the end position. (4) The substituents in the alkyl group are prefixed in an alphabetical order by appropriate locants. (5) When two CHO groups are present at the two ends of the chain, the ending ‘e’ of alkane is retained

and the suffix ‘dial’ is added to the name of parent aldehyde. (6) In IUPAC nomenclature an alicyclic compound in which CHO group is attached directly to the ring

is named as a carbaldehyde. The suffix ‘carbaldehyde’ is added after the full name of parent cycloalkane structure.

5. Give the common names and IUPAC names of the following aldehydes: [1M each] A.

Aldehyde Common name IUPAC name (1) HCHO Formaldehyde Methanal (2) CH3 CHO Acetaldehyde Ethanal (3) CH3 CH2 CHO Propionaldehyde Propanal (4) CH3 CH2 CH2 CHO n-Butyraldehyde Butanal (5)

Isobutyraldehyde 2-Methylpropanal

(6) CH2 = CH CHO Acrolein Prop-2-enal

(7) CH3 CH = CH CHO Crotonaldehyde But-2-enal

(8) CHO CHO Oxaldehyde (Glyoxal) Ethanedial (9)

Valeraldehyde Pentanal

(10)

-Methyl valeraldehyde 3-Methylpentanal

(11)

-Hydroxybutyraldehyde 3-Hydroxy butanal

(12)

Chloro propionaldehyde 2Chloropropanal Vidy

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CHO

CHO

OHCHO

CH3

CHO1

2

34

6

5

3 2 1

2HO CH CH CHO

OH

CHO

HO3OCH

61

2

34

5

Aldehyde Common name IUPAC name (13)

Benzaldehyde Benzaldehyde (Benzenecarbaldehyde)

(14)

Phthaldehyde Benzene-1, 2-dicarbaldehyde

(15)

Salicylaldehyde 2-Hydroxybenzaldehyde

(16)

Glyceraldehyde 2,3-Dihydroxypropanal

(17)

Vanillin 4-Hydroxy-3-Methoxy- benzaldehyde

(18)

p-Tolualdehyde 4-Methylbenzaldehyde

(19)

Cyclohexane aldehyde Cyclohexanecarbaldehyde

6. Explain the classification of ketones. [Feb. 2016, 3 M] A. Ketones are classified on the basis of nature of carbon skeleton bonded to ( )

group into aliphatic and aromatic ketones. i. Aliphatic ketones:

a. The compounds in which group is attached to two alkyl groups are called aliphatic ketones.

b. General formula: Oxo or ketonic carbonyl group

(where R, R = alkyl group, identical or different.)

c. On the basis of types of alkyl groups bonded to carbonyl carbon, aliphatic ketones are further classified as simple and mixed ketones.

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(1) Simple or symmetrical ketone : The ketone in which the carbonyl carbon is attached to two identical alkyl groups is called a simple or symmetrical ketone.

(2) Mixed or unsymmetrical ketone : The ketone in which the carbonyl carbon is attached to two different alkyl groups is called a mixed or unsymmetrical ketone.

ii. Aromatic ketones: a. The compounds in which a group is attached to either two aryl groups

or one aryl and one alkyl group are called aromatic ketones.

b. On the basis of types of aryl/alkyl groups bonded to carbonyl carbon, aromatic ketones are also further classified as simple and mixed ketones.

*7. What are aromatic ketones? [1 M] A. Refer Q.6 (iia) Nomenclature of ketones:

(A) Common System: (1) Ketones are named according to the alkyl groups attached to the carbonyl carbon atom followed by

the word ketone. (2) The substituents in the alkyl groups are indicated by Greek letters , , , etc. starting from the

carbon atom attached to the carbonyl group. (B) IUPAC system: (1) The longest continuous chain containing carbonyl carbon atom is selected as a parent hydrocarbon. (2) ‘e’ of the alkane is replaced by ‘one’. (3) The position of carbonyl group is represented by the lowest locant. (4) The substituents in the alkyl groups are prefixed in the alphabetical order along with their positions by

appropriate locants. (5) When two groups are present, then ending ‘e’ of alkane is retained and the suffix ‘dione’ is

added to the name of parent ketone indicating the locants of ketonic carbonyl groups. (6) In case of polyfunctional ketones, higher priority group is given lower number. When ketonic carbonyl

is a lower priority group, it is named as ‘oxo’, preceded by the locant. In alicyclic ketones, carbonyl carbon is numbered as 1.

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8. Give the common names and IUPAC names of the following ketones: [1M each] A.

Ketone Common name IUPAC name

Acetone Propanone

Ethyl methyl ketone Butan-2-one

Diethyl ketone Pentan-3-one

Methyl isopropyl ketone 3-Methylbutan-2-one

Methyl n-propyl ketone Pentan-2-one

-Bromoethyl-n-propyl ketone

2-Bromohexan-3-one

Mesityl oxide 4-Methylpent-3-en-2-

one

Benzyl ethyl ketone 1-Phenylbutan-2-one

(9) Diphenyl ketone

(Benzophenone) Benzophenone

(10)

Methyl phenyl ketone (Acetophenone) Acetophenone

(11)

2Chloro4methyl cyclohexanone

(12)

Diisopropyl ketone 2, 4-Dimethylpentan-3-one

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i. Aldehydes and ketones are responsible for many flavours and odours that you will readily recognize:

ii. Structures of many important biological compound contain carbonyl moiety. For example, progesterone and testosterone, the female and male sex hormones respectively.

iii. Butyraldehyde is used in margarine and food for its buttery odour.

iv. Acetophenone has smell of pistachio and is used in ice-cream. Muscone has musky aroma and is used in perfumes. Popcorn has flavour which contains butane2, 3dione.

9. Explain the classification of carboxylic acids. [3 M] A. Carboxylic acids are classified on the basis of nature of carbon skeleton bonded to

( ) group into aliphatic and aromatic carboxylic acids.

i) Aliphatic carboxylic acids: a. The organic compounds in which carboxyl (COOH) group is bonded to an

alkyl group are called aliphatic carboxylic acids or fatty acids. b. Formic acid, HCOOH is also classified as aliphatic carboxylic acid though

COOH group is not attached to any carbon. e.g.: 3

Acetic acidH C COOH

3 2

Pr opionic acidH C CH COOH

c. General formula:

d. Depending on the number of COOH groups present carboxylic acids are classified as mono, di, tri carboxylic acids and so on.

e.g.

ii) Aromatic carboxylic acids: These are the compounds in which one or more carboxyl groups (COOH) are attached directly to the aromatic ring.

e.g.

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Note: The aromatic compounds in which the COOH group is not attached directly to the ring are called side-chain aromatic acids. e.g.

Nomenclature of Carboxylic Acids : A) Common or trivial names : 1) The common name of a carboxylic acid is derived from the source from which it was first isolated. The following table gives common names and the source or origin of name.

Carboxylic acid Common name Origin of name i) HCOOH Formic acid formica (ant) ii) CH3COOH Acetic acid acetum (vinegar) iii) CH3CH2COOH Propionic acid ‘propion’ (first fat) iv) CH3CH2CH2COOH nbutyric acid butyrum (butter) v) CH3CH2CH2CH2COOH nvaleric acid valerian (a perennial plant) vi) CH3CH2CH2CH2CH2COOH ncaproic acid Caper (goat)

2) In branched carboxylic acids, the position of substituents are indicated by Greek alphabet.

For example : C C C C COOH

B) IUPAC system of nomenclature : (1) The longest continuous chain of carbon atoms including the carbon atom of COOH group is

selected. The carboxylic acid is considered as a derivative of the corresponding parent alkane. (2) The name of carboxylic acid is obtained by replacing ‘e’ from the name of parent alkane by ‘oic

acid’. Thus carboxylic acids are called alkanoic acids. (3) The carbon atom of the COOH group is always at terminal position, hence need not to be indicated

while writing IUPAC name. (4) The position of the other substituents are indicated by the appropriate locants in alphabetical order. (5) In case of dicarboxylic acids, ‘dioic acid’ is added to parent alkane. (6) In an alicyclic compound having a carboxyl group directly attached to alicyclic ring is named as

cycloalkane carboxylic acid.

10. Write common name and IUPAC name for the following carboxylic acids. A. [1M each] Carboxylic acid Common name IUPAC name 1) HCOOH Formic acid Methanoic acid 2) CH3COOH Acetic acid Ethanoic acid 3) CH3CH2COOH Propionic acid Propanoic acid 4) CH3CH2CH2COOH nButyric acid Butanoic acid 5)

Isobutyric acid or methyl propionic acid

2Methylpropanoic acid

6) CH3CH2CH2CH2CH2COOH nValeric acid Pentanoic acid 7)

Isovaleric acid or methylbutyric acid

3Methylbutanoic acid

8)

,Dimethylbutyric acid

2,3Dimethylbutanoic acid

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Carboxylic acid Common name IUPAC name

9) HOOCCOOH Oxalic acid Ethanedioic acid

10) HOOCCH2COOH Malonic acid Propanedioic acid

11) HOOC(CH2)2COOH Succinic acid Butanedioic acid

12) HOOC(CH2)3COOH Glutaric acid Pentanedioic acid

13) HOOC(CH2)4COOH Adipic acid Hexanedioic acid

14)

Lactic acid 2Hydroxypropanoic acid

15) CH2 = CHCOOH Acrylic acid Propenoic acid

16)

Malic acid 2Hydroxypropanoic acid

17)

Benzoic acid (Benzenecarboxylic acid)

Benzoic acid

18)

Phthalic acid Benzene1,2dicarboxylic acid

19)

Salicylic acid 2Hydroxybenzoic acid (2Hydroxybenzene carboxylic acid)

20)

mToluic acid 3Methylbenzoic acid

21) Cyclohexylcarboxylic acid

Cyclohexanecarboxylic acid

11. Write the structure and give IUPAC names of the following compounds. [1M each] (1) chloropropionaldehyde (2) hydroxybutyraldehyde (3) isobutyraldehyde (4) -methyl valeraldehyde (5) isopropyl methyl ketone (6) diisopropyl ketone (7) m-bromo benzaldehyde (8) dibenzyl ketone (9) divinyl ketone (10) allyl methyl ketone (11) ethyl phenyl ketone (12) nbutyrophenone

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A. Structure IUPAC names

(1) 3CH CH CHO

Cl

2-Chloropropanal

(2) 3 2CH CH CH CHO

OH

3-Hydroxybutanal

(3) 3CH CH CHO

CH3 2-Methylpropanal

(4) 3 2 2CH CH CH CH CHO

CH3

3-Methylpentanal

(5) 3 3CH CH C CH

CH3 O

3-Methylbut-2-one

(6) 3 3

1 2 3 4 5CH CH C CH CH

CH3O CH3

2, 4-Dimethylpentan-3-one

(7)

Br

CHO

3-Bromo benzaldelyde

(8) 2 2CH C CH

O

1,3-Diphenylpropan-2-one

(9) 2 2CH CH C CH CH

O

Pent1,4-diene-3-one

(10) 2 2 2 3CH CH CH C CH CH

O15 234

Pent-5-en-3-one

(11) 3 2CH CH C

O

1-phenyl propan-1-one

(12) 2 2 3C CH CH CH

O

1phenyl butan-1-one

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12. Write the structure and give IUPAC names of following carboxylic acids. i) , Dimethylbutanoic acid ii) Phenylbutyric acid

iii) Choromethylvaleric acid. [1M each]

A. i)

2, 3Dimethyl butanoic acid

ii)

3Phenyl butanoic acid

iii)

4Chloro2methyl pentanoic acid

13. Give example of common carboxylic acids which are used in daily life. [2 M] A. Common carboxylic acids are widely distributed in nature, they are found in both the

plants and animals. i. Acetic acid is main constituent of vinegar. ii. Butyric acid of butter which is responsible for odour of rancid butter. iii. L-lactic acid is present in curd. iv. Citric acid is found in citrus fruits.

v. Higher carboxylic acids such as palmitic acid, stearic acid and oleic acid are the components of animal fats and vegetable oils.

14. How is an aldehyde obtained from an alcohol ? [2M] A. When a primary alcohol is oxidized with potassium dichromate and dil. H2SO4 under

controlled conditions, an aldehyde is obtained.

2 2 7

2 4

K Cr O2 2H SO

AldehydeAlcoholR CH OH (O) R CHO H O

For example, when ethanol is oxidized with potassium dichromate and dil. H2SO4 under controlled conditions, acetaldehyde (ethanal) is obtained.

2 2 7

2 4

K Cr O3 2 3 2H SO

Ethanol AcetaldehydeCH CH OH ( ) CH CHO H O

15. How is ketone obtained from an alcohol ? [2M] A. When a secondary alcohol is oxidized with potassium dichromate and dil. H2SO4

under controlled conditions, a ketone is obtained.

2 2 7

2 4

K Cr O2H SO

Sec. alcohol Ketone

OH O| ||

R CH R [O] R C R H O

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For example, when 2-propanol is oxidized with potassium dichromate and dil. H2SO4 under controlled conditions, acetone (propanone) is obtained.

2 2 7

2 4

K Cr O3 3 3 3 2H SO

Acetone2 Propanol

OH O| ||

CH CH CH (O) CH C CH H O

16. How will you prepare aldehydes and ketones by dehydrogenation of alcohols?

[2 M] A. Aldehydes and ketones are prepared by passing the vapours of primary and

secondary alcohols respectively over hot copper powder. This method has industrial application.

i. Cu/573K2 Oxidation Aldehyde1 Alcohol

R CH OH R CHO

ii. Cu/573KOxidation

2 Alcohol Ketone

R CH R' R C R'| ||OH O

17. How are the following compounds obtained from alcohol : [1M each] (1) Methanal (2) Propanal (3) Butanal (4) 3-Methylpentanal ?

A. (1) Methanol on controlled oxidation with K2Cr2O7 and dilute H2SO4 forms methanal.

(2) Propan-1-ol on controlled oxidation with K2Cr2O7 and dilute H2SO4 forms

propanal.

(3) Butan-1-ol on controlled oxidation with K2Cr2O7 and dilute H2SO4 forms butanal.

(4) 3-Methylpentan-1-ol on controlled oxidation with K2Cr2O7 and dilute H2SO4 gives

3-Methylpentanal.

18. How are the following compounds obtained from alkene : [3M] (1) Formaldehyde (2) Acetadehyde (3) Acetone ? A. When a stream of ozonised oxygen is passed through a solution of an alkene, in

organic solvent, an unstable addition cyclocompound, ozonide is formed which on reduction with zinc dust and water forms an aldehyde or a ketone or a mixture of both.

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(1) Formaldehyde : Under these conditions ethylene gives formaldehyde.

(2) Acetaldehyde : Symmetrically disubstituted alkene like but-2-ene gives acetaldehyde.

(3) Acetone : Tetrasubstituted alkene like 2,3-dimethyl but-2-ene gives acetone.

19. How are the following compounds obtained from alkynes : [2M] (1) Acetaldehyde (2) Acetone ? A. (1) Acetaldehyde : On passing acetylene through warm 40% H2SO4 in the

presence of 1 % HgSO4, vinyl alcohol is obtained which tautomerises and forms acetaldehyde. It is a hydration reaction.

(2) Acetone : On passing propyne through warm 40% H2SO4 in the presence of 1% HgSO4, alkenol is obtained which on tautomerisation form acetone.

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.Solved Problems.

Problem 1 Write the structures and give common names and IUPAC names of the carbonyl

compounds represented by formula C5H10O.

Solution: Compound Common name IUPAC name

n-Valeraldehyde Pentanal

-Methyl butyraldehyde 2-Methylbutanal

Methyl n-propyl ketone Pentan-2-one

Diethyl ketone Pentan-3-one

Problem 2 Write the structures of aldehydes and ketones obtained by ozonolysis.

(i)

(ii) Solution: (i)

(ii)

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Problem 3 Write ozonolysis reaction for (1) Propylene and (2) Isobutylene.

Solution : (1) Propylene on reaction with ozonised oxygen in the organic solvent forms

propylene ozonide which on reduction with zinc dust and water forms acetaldehyde and formaldehyde.

Problem 4 Why does skin has burning sensation, when an ant bites?

Solution : When an ant bites, formic acid is released from an ant which gives burning sensation

as the acid comes in contact with the skin. Problem 5 Write the structures and IUPAC names of all isomers of carboxylic acids having

molecular formula C5H10O2. How many of them are chiral?

Solution :

Structures IUPAC names i) CH3CH2CH2CH2COOH Pentanoic acid

ii)


iii)


iv)

2, 2Dimethylpropanoic acid

Structures (ii) and (iii) are chiral structures.

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3 3CH CH C CH CH

CH3CH3

O

3 2 2 2 3

O||

CH CH CH C CH CH CH

CH3

3CH CH CHO

CH3

3 3CH CH CO CH

CH3

3CH C CHO

CH3

CH3

.Classwork Problems.

1. Classify the following ketones :

(i) 3 2 3

O||

CH CH C CH (ii)

(iii) (iv)

O||

C H C C H2 5 2 5

2. Give the IUPAC names of the following compound: (i) HCHO (ii) CH3CHO (iii) CH3COCH3 (iv) CH3CH2CHO (v) CH3COCH2CH3 (vi)

(vii) (viii) 3 2 2CH CH CH CHO (ix) 3 2 2 3CH CO CH CH CH (x) 3. Give IUPAC names of following compounds.

(1) (2) (3) (4) 4. Write the structure of following compounds. (1) 4Methyl3nitrobenzophenone (2) 2Methyl4oxopentanal (3) 3Oxopentanoic acid (4) 4chloropropiophenone (5) 3Methoxy butanal (6) 4Hydroxycyclohexane carbaldehyde 5. Write the structure and IUPAC names of isomeric aldehydes having molecular

formula C5H10O. [Oct.-2015, 4M] 6. Write IUPAC names of the following compounds : [July-2016, 2M]

(a) (b) 3 3

O O|| ||

CH C C CH

CH3

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7. Draw the structures of following compounds. 1) 2, 3Dimethylhexanoic acid 2) Nonanedioic acid 3) Hex2en4ynoic acid 4) 3Bromo4phenylpentanoic acid 5) 1, 4Cyclopentanedicarboxylic acid 6) Cyclohex3encarboxylic acid.

8. Give IUPAC names of following carboxylic acids.

1) COOH

CH3

2)

CH-COOH

OH

3) COOH

4)

O2N 2CH CH COOH

CH3

5)

3 2CH CH C CH COOH

CH3 6) CH3(CH2)6 COOH

7) 8 7 6 5 4 3 2 1

2 2HOOC CH CH CH CH CH CH COOH

CH3 C2H5

9. Predict the products when (i) dimethyl acetylene (ii) ethyl acetylene and (iii) diethyl acetylene are treated with mercuric sulphate in dilute sulphuric acid.

.Homework Problems.

1. Give the structures of the following compounds : i) Pentan-2-one ii) Propanal iii) Butan-2-one iv) 2-Methylpropanal v) Pentan-3-one vi) Methanal vii) 4-Methylpentanal viii) Ethanal ix) 2-Methylpentan-3-one x) Propanone xi) 3-Methylbutanal xii) Propionaldehyde xiii) 2-Methylbutanal xiv) 3-Methylbutanone xv) Butanal xvi) 3-Methylpentan-2-one.

2. Predict the structures of ketones produced by hydration of but-1-yne and but-2-yne.

3. Classify the following as aliphatic and aromatic aldehydes.

4. Classify the followings as simple and mixed ketones. Benzophenone, acetone, butanone, acetophenone.

i)

iii)

iv)

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*5. Is phenyl acetic acid an aromatic carboxylic acid?

*6. Write the IUPAC names of the following structures: i) ii)

7. Write IUPAC names for the following compounds.

8. Draw structures for the following. i) 2Methylpentanal ii) Hexan2one 9. How are the following compounds prepared from alcohol : i) Butanone ii) Pentan-3-one iii) 2,2-Dimethylpropanal Classwork Problems

1. (i) Mixed (unsymmetrical) ketone (ii) Simple ketone (iii) Mixed (unsymmetrical) ketone (iv) Simple ketone

2. (i) Methanal (ii) Ethanal (iii) Propanone (iv) Propanal (v) Butanone (vi) 2-Methylpropanal (vii) 3-Methylbutanone (viii) Butanal (ix) Pentan-2-one (x) 2,2-Dimethylpropanal.

3. IUPAC name of the compounds are : (1) 3-Hydroxy butanal (2) 4-Methylhex-3-en-2-one (3) 3-Phenylprop-2-enal (4) Cyclohex-2-en-1-one

4. Structure of the compounds are :

(1)

(2)

i) ii)

v) iv) iii)

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(3)

(4)

(5)

(6)

5. Four isomeric aldehyde having molecular formula C5H10O are CH3CH2CH2CH2CHO Pentanal 3 2

3

CH CH CH CHO|CH

2Methyl butanal

3 2

3

CH CH CH CHO|CH

3Methyl butanal

3

3

3

CH|

CH C CHO|CH

2,2Dimethyl propanal

6. (a) 3-Methyl cyclohexanone (b) Butanedione

7.

1) 3 2 2CH CH CH CH CH COOH

CH3 CH3

2) 1 2 3 4 5 6 7 8 9

2 2 2 2 2 2 2HOOC CH CH CH CH CH CH CH COOH or HOOC(CH2)7COOH

3) 4 3 2 1

3H C C C CH CH COOH

4)

5)

6)

8. 1) 4Methylcyclohexane carboxylic acid 2) 2Hydroxy2phenyl ethanoic acid 3) 1Cyclopentene1carboxylic acid 4) 3(4Nitro phenyl) butanoic acid

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3CH CH CHO

CH3

3 2 2CH CH CH CH CHO

CH3

3 2 3CH CH CO CH CH

CH3

3 2CH CH CH CHO

CH3

3 2CH CH CH CHO

CH3

3 3CH CO CH CH

CH3

3 2 3CH CO CH CH CH

CH3

5) 3Methyl3pentenoic acid 6) Octanoic acid 7) 3Ethyl6methyl4octene1, 8dioic acid

9. (i) 3 2 3

Ethyl methyl ketone

CH CH C CH||O

(ii) 2 5 3

Butan 2 one

C H C CH||O

(iii) 2 5 2 2 5

Hexan 3 one

C H C CH C H||O

Homework Problems

1. i) 3 2 2 3CH CO CH CH CH ii) 3 2CH CH CHO

iii) 3 2 3CH CO CH CH iv) v) 3 2 2 3CH CH CO CH CH vi) HCHO vii) viii) CH3CHO ix) x) CH3COCH3

xi) xii) CH3CH2CHO xiii) xiv) xv) CH3CH2CH2CHO (xvi)

2.

3. i) Aliphatic aldehyde ii) Aliphatic aldehyde iii) Aliphatic aldehyde iv) Aromatic aldehyde

4. Simple ketones : Benzophenone, acetone. Mixed ketones : Butanone, acetophenone.

tautomerism3 2 3CH C CH CH

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5. Yes, phenyl acetic acid is a side-chain aromatic carboxylic acid.

6. i) 3Methylcyclohexanone ii) Ethanedioic acid

7. i) 5, 5-Dibromo2, 2-dimethylhexanal ii) 7Ethyl5, 5dimethyldecane3, 4dione iii) Pentanal iv) 3, 4Dimethylbenzaldehyde v) 2, 4Dimethylcyclohexanone

8. i) \\

ii) 9. i) Butan-2-ol on controlled oxidation with K2Cr2O7 and dilute H2SO4 forms

butanone.

ii) Pentan-3-ol on oxidation with K2Cr2O7 and dilute H2SO4 forms Pentan-3-one.

iii) 2,2-Dimethylpropan-1-ol on oxidation with K2Cr2O7 or KMnO4 and dilute H2SO4

forms 2,2-Dimethylpropanal.

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MODULE 2

MODULE OVERVIEW 12.4.2 Other methods of preparation of aldehydes and ketones a. From acyl chlorides (Acid chlorides) Preparation of aldehyde from acyl chloride Preparation of ketone from acyl chloride i. Preparation of aliphatic ketones from acyl chloride ii. Preparation of aromatic ketones from acyl chloride b. From nitriles Preparation of aldehyde from nitriles Preparation of ketone from nitriles c. From aromatic hydrocarbons Preparation of aromatic aldehydes from hydrocarbons i. Etard reaction ii. By oxidation of methyl arene using CrO3

iii. By side chain chlorination of toluene iv. Gatterman Koch formylation of arene Preparation of aromatic ketones from hydrocarbons : By Friedelcrafts acylation of arene 12.4.3 Preparation of aldehydes from esters

12.5 Preparation of carboxylic acids 12.5.1 From nitriles and amides 12.5.2 From acyl chloride and anhydrides 12.5.3 From esters 12.5.4 From alkyl benzene 12.5.5 From alkenes 12.5.6 From Grignard reagent 1. How are aldehydes prepared by Rosenmund reduction? [2 M] A. Acyl chloride is reduced to corresponding aldehyde by hydrogen using a palladium

catalyst poisoned with barium sulfate. This reaction is known as Rosenmund reduction.

2. Write the structure of the product formed on Rosenmund reduction of ethanoyl

chloride and benzoyl chloride. [1 M each] A. i. Rosenmund reduction of ethanoyl chloride:

ii. Rosenmund reduction of benzoyl chloride: [March 2013, Feb.-2019]

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3. Explain the preparation of aliphatic and aromatic ketones from acyl chloride using dialkyl cadmium. [3 M]

A. Ketones are obtained from acyl chloride by reaction with dialkyl cadmium which is prepared by the treatment of cadmium chloride with Grignard reagent. The reaction can be represented as,

2 2Grignard cadmium Dialkylreagent chloride cadmium

2R MgX CdCl R Cd 2Mg(X)Cl

2 2Acyl chloride Ketone2R' COCl R Cd 2R' CO R CdCl

e.g. i. Ethanoyl chloride to propanone 3 3 2 3 3 2

Ethanoyl chloride Dimethyl Pr opanone(Acetone)cadmium

2CH COCl (CH ) Cd 2CH CO CH CdCl

ii. Benzoyl chloride to acetophenone 6 5 3 2 6 3 3 2

Benzoyl chloride Dimethyl Acetophenonecadmium

2C H COCl (CH ) Cd C H CO CH CdCl

4. Explain the preparation of aromatic ketones by Friedel Craft’s acylation

reaction. [2 M] A. Aromatic ketones can be prepared by Friedel Craft’s acylation reaction.

5. *Write a note on Stephen reaction. [Oct. 2015, 2 M]

OR How is an aldehyde obtained from alkyl nitrile?

OR *Write reaction showing conversion of ethanenitrile into ethanal.

A. Nitriles are reduced to imine hydrochloride by stannous chloride in presence of hydrochloric acid which on acid hydrolysis give corresponding aldehydes. This reaction is called Stephen reaction.

32 H OSnCl .HCl4Iminehydrochloride AldehydeAlkanenitrile

R C N 2[H] R HC NH.HCl R CHO NH Cl

e.g. 32 H OSnCl ;HCl3 3 3 4(reduction)Ethanenitrile Ethanimine hydrochloride Ethanal

H C C N 2[H] CH HC NH.HCl CH CHO NH Cl

6. Explain the preparation of aldehydes from nitriles using diisobutylaluminium

hydride. [2 M] A. Nitriles are reduced by diisobutylaluminium hydride (DIBAIH) or AIH(iBu)2 to

imines followed by acid hydrolysis to aldehydes. An advantage of this method is that double or triple bond present in the same

molecule is not reduced.

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3

(DIBAI H)H O

Alkyl nitrile Aldehyde

H|

R C N R C O

3

5 4 3 2 1 5 4 3 2 1DIBAl H

3 2 3 2H OPent 3 en 1 nitrile Pent 3 enal

H|

CH CH CH CH CN CH CH CH CH C O

7. How will you prepare ketones from nitriles? [2 M] A. Ketones are prepared by reacting nitriles with Grignard reagent in dry ether as

solvent followed by acid hydrolysis. e.g. Ethanenitrile to acetone:

8. Write the reactions for the preparation of benzophenone from benzonitrile. [Oct.-2013, July-2016, Feb-2018, 2M]

A. 9. How are the following preparations carried out ? [1M each] A. (1) Benzaldehyde from toluene : When toluene is treated with solution of chromyl

chloride (CrO2Cl2) in CS2, brown chrominum complex is obtained, which on acid hydrolysis gives benzaldehyde. This reaction is called Etard reaction.

(2) By oxidation of methyl arene using CrO3:

Toluene (i.e. methylarene) is converted to benzylidene diacetate on treating with chromic oxide in acetic anhydride at 273-283 K. Acid hydrolysis of benzylidene diacetate gives benzaldehyde.

+ NH3

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(3) Benzaldehyde from toluene (commercial method) : Side chain chlorination of toluene gives benzal chloride which on hydrolysis gives

benzaldehyde.

(4) Benzaldehyde from benzene (Gattermann-Koch synthesis) :

[March 2013, Feb.-2019] When benzene is treated with vapours of carbon monoxide and hydrogen

chloride in the presence of a catalyst mixture of AlCl3 and CuCl under high pressure benzaldehyde is obtained.

(5) 4-Nitrobenzaldehyde from 4-nitrotoluene.

When 4-nitrotoluene is treated with chromium oxide in acetic anhydride, a diacetate derivative is obtained which on acid hydrolysis produces 4-nitrobenzaldehyde.

(6) Acetophenone from benzene (FriedelCrafts acylation). [March 2013]

When benzene is treated with acetyl chloride in the presence of anhydrous aluminium chloride, acetophenone is obtained. This reaction is known as Friedel Crafts acylation.

10. How will you prepare : [1M each] i) Propiophenone from propanenitrile ii) 4chlorobenzaldehyde from 4chlorotoluene iii) Cyclohexanecarbaldehyde from cyclohexylmethanol iv) 4methoxyacetophenone from anisole v) 4methylbenzaldehyde from toluene.

A. i) Propiophenone from propanenitrile : A propane nitrile reacts with Grignard reagent in the presence of dry ether to give a complex which on acid hydrolysis gives a propiphenone.

4-Nitrotoluene 4-Nitrobenzaldehyde

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ii) 4chlorobenzaldehyde from 4chlorotoluene

When 4-chloro toluene is treated with acetic anhydride in the presence of anhydrous aluminium chloride, 4-chloro benzaldehyde is obtained.

iii) Cyclohexane carbaldehyde from cyclohexyl methanol

When cyclohexyl methanol is heated with acid dichromate cyclohexane carbaldehyde is obtained.

iv) 4methoxyacetophenone from anisole : When anisole is treated with acetyl chloride in the presence of anhydrous AlCl3, 4-methoxy acetophenone is obtained as major product.

v) 4methylbenzaldehyde from toluene.

Cyclohexyl methanol Cyclohexane carbaldehyde

H3O+

+ NH3

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11. Explain the preparation of aldehydes from esters. [2 M] A. Aliphatic or aromatic esters are reduced to aldehydes by using diisobutylaluminium

hydride (DIBAIH) or AIH(iBu)2. The reaction is usually carried out at 195 K to prevent further reduction of aldehyde produced.

*12. Predict the product of the following reaction: [1 M] 2

3

i) AIH(i Bu)3 2 3 ii)H O

CH CH COOCH ?

A. 2

3

i) AIH(i Bu)3 2 3 3 2ii)H O

Methylpropionate Pr opanalCH CH COOCH CH CH CHO

13. How will you prepare carboxylic acids by the hydrolysis of nitriles and amides?

[2 M] A. i) Alkyl nitriles or aryl nitriles on acid hydrolysis give amides. ii) Amides on further acid hydrolysis give corresponding carboxylic acids.

iii) Hydrolysis is carried out by using dilute mineral acids like dilute sulfuric acid or dilute hydrochloric acid.

Or the final equation becomes

14. How is ethanoic acid obtained from methyl cyanide by acid hydrolysis? [2 M] A. When methyl cyanide is heated with dilute hydrochloric acid or dilute sulphuric acid,

ethanoic acid is obtained.

15. How is benzoic acid obtained from benzamide? [2 M] A. When benzamide is heated with dil. HCl, benzoic acid is obtained.

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*16. Write reaction showing conversion of p-bromoisopropylbenzene into p-isopropylbenzoic acid (3 steps). [3 M]

A. Step 1: Converting Br group to CN:

Step 2: Converting CN group to CONH2:

Step 3: Converting CONH2 group to COOH:

17. How will you prepare carboxylic acids by hydrolysis of the following ? [4 M] i) Acyl chlorides ii) Anhydrides iii) Esters A. i) By hydrolysis of Acyl chlorides: Acyl chlorides on hydrolysis with water give carboxylic acids. This method is

useful for preparation of aliphatic as well as aromatic acid. 2Acyl chloride Carboxylic acid

R COCl H O R COOH H Cl

ii) By hydrolysis of Anhydrides: Anhydrides on hydrolysis with water give carboxylic acids.

iii) By hydrolysis of Esters: Carboxylic acids can be obtained from esters either by acid hydrolysis or alkaline

hydrolysis. a. Acid hydrolysis of ester: Esters on hydrolysis with dilute mineral acid like

dilute HCl or dilute H2SO4 give the corresponding carboxylic acid.

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b. Alkaline hydrolysis of ester using dilute alkali like dilute NaOH or dilute KOH form solution of water soluble sodium or potassium salt of the acid (carboxylate). On acidification with concentrated HCl, free acid is formed.

e.g.

18. How is benzoic acid obtained from ethyl benzoate? [2 M] A. When an ethyl benzoated is heated with dil. H2SO4, undergoes hydrolysis to form

benzoic acid and ethyl alcohol.

19. Write a note on oxidation of alkyl benzene. [2 M] A. i) Aromatic carboxylic acids can be prepared by oxidation of alkyl benzene with

dilute HNO3 or alkaline/acidic KMnO4 or chromic acid.

ii) The entire alkyl chain, regardless of its length, is oxidized to a carboxyl group. However, tertiary alkyl substituent on benzene is not oxidized.

e.g.

20. How will you convert the following: i) nbutyl benzene to benzoic acid ii) Toluene to benzoic acid ? [2M]

A. i)

ii) Vidy

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21. *What is the action of the following reagent on toluene? [1 M] Alkaline KMnO4, dil.HCl and heat A. Refer Q. No. 20(ii) 22. How is benzoic acid obtained from phenyl ethene? [1M, July 2016] A. When phenyl ethene is heated with strong oxidising agents like acidic KMnO4 or

acidic K2Cr2O7, benzoic acid is obtained.

23. How is adipic acid obtained from cyclohexene? [1M] A. When cyclohexene is heated with acidified KMnO4, adipic acid

(Hexane1,6dioic acid) is obtained.

24. What is carboxylation of Grignard reagent? How is acetic acid prepared by this

reaction? OR [2M] How is ethanoic acid prepared from dry ice? [M-2017, 2M] A. Addition reaction of carbon dioxide (O = C = O) to Grignard reagent, forming a

complex and further formation of carboxylic acid is called carboxylation of Grignard reagent.

Example: When methyl magnesium iodide is added to solid carbon dioxide, a

complex is formed which on acid hydrolysis forms acetic acid.

25. Identify A and B in the following reaction: [July-2017, 2M] dry ether

3CH Br Mg A

2

dry ether2 H /H O

A CO B Mg(Br)OH

A. dry ether3 3

Methyl Bromide Methylmagnesiumbromide(A)

CH Br Mg CH MgBr

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2|| ||

H /H Odry ether3 2 3 3

Acetic acid (B)

O O

CH MgBr CO CH C OMgBr CH C OH Mg(Br)OH

26. How is benzoic acid prepared from Grignard reagent? [2M] A. When phenyl magnesium bromide is treated with dry ice (solid carbon dioxide) in the

presence dry ether, complex is obtained which on acidification gives benzoic acid.

.Solved Problems.

Problem 1 Write the structures and IUPAC names of ketones produced by Friedel-Crafts

acylation of benzene with (i) C2H5COCl (ii) C6H5COCl Solution :

Problem 2 Predict the products of the following conversions.

Solution:

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Problem 3

How is butanoic acid prepared starting from (1) an alkene (2) an alcohol (3) an alkyl halide?

Solution: Preparation of butanoic acid.

1) From an alkene : When an alkene like propene reacts with HBr in presence of peroxide it gives npropyl bromide. Next, npropyl bromide when heated with alcoholic KCN gives npropyl cyanide. Acid hydrolysis of npropyl cyanide gives butanoic acid. The reactionsequence is:

i) Peroxide3 2 3 2 2

Propene n Propyl bromideCH CH CH HBr CH CH CH Br

ii) 3 2 2 3 2 2Alcoholn Propyl bromide n Propyl cyanideCH CH CH Br KCN CH CH CH CN KBr

iii) 3 2 2 2 3 2 2 4Butanoic acidn Propyl cyanide

O||

CH CH CH C N 2H O HCl CH CH CH C OH NH Cl

2) From an alcohol : An alcohol like nbutyl alcohol on oxidation with acidified

K2Cr2O7 forms an aldehyde (butyraldehyde) which on further oxidation forms butanoic acid.

i) 2 2 7 2 4K Cr O dil.H SO3 2 2 2 3 2 2 2

n Butyl alcohol Butyraldehyde

O||

CH CH CH CH OH [O] CH CH CH C H H O

ii) 2 2 7 2 4K Cr O dil.H SO3 2 2 3 2 2

Butyraldehyde Butanoic acid

O O|| ||

CH CH CH C H [O] CH CH CH C OH

3) From an alkyl halide : An alkyl halide like nbutyl iodide on boiling with aqueous

KOH forms nbutyl alcohol which on oxidation with acidified K2Cr2O7 forms butyraldehyde and on further oxidation forms butanoic acid.

i) boil3 2 2 2 3 2 2 2(aq)n Butyl iodide n Butyl alcohol

CH CH CH CH I KOH CH CH CH CH OH KI

ii) 2 2 7 2 4K Cr O dil.H SO3 2 2 2 3 2 2 2

n Butyl alcohol Butyraldehyde

O||

CH CH CH CH OH [O] CH CH CH C H H O

iii) 2 2 7 2 4K Cr O dil.H SO3 2 2 3 2 2

Butyraldehyde Butanoic acid

O O|| ||

CH CH CH C H [O] CH CH CH C OH

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1. How will you bring about the following conversions? i) Acetonitrile to acetaldehyde. ii) Benzene to benzaldehyde.

iii) Toluene to benzaldehyde. iv) Benzoyl chloride to benzaldehyde.

*2. What is the action of the following reagents on toluene? i) CrO2Cl2 in CS2 ii) Acetyl chloride in presence of anhydrous AICl3.

3. Identify the reagents necessary to achieve each of the following transformation.

*4. Write reaction showing the action of the following reagent on propanenitrile: i) Dilute NaOH ii) Dilute HCl

5. Predict the products (name and structure) in the following reactions. i) CH3CH2CN dil.HCl

? ii) 3 2 dil.HClCH CONH ?

iii) 4alk.KMnO6 5 2 3C H CH CH ? iv)

2 46 5 2 5 dil.H SOC H COO C H ?

v) i.dry ice/dry ether3 ii. dil.HClCH MgBr

? .Homework Problems.

1. How will you bring about the following conversions? i) Benzonitrile to benzophenone ii) Benzene to acetophenone

*2. Write reaction showing conversion of benzonitrile into benzoic acid.

*3. Name the product obtained by reacting toluene with carbon monoxide and hydrogen chloride in presence of anhydrous aluminium chloride.

*4. Acetic acid is prepared from methyl magnesium bromide and dry ice in presence of dry ether. Name the compound which serves not only as reagent but also as cooling agent in the reaction.

5. What is the alcohol formed when benzoyl chloride is reduced with pure palladium as the catalyst?

*6. Name the product obtained by the oxidation of 1, 2, 3, 4tetrahydronaphthalene with acidified potassium permanganate.

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Classwork Problems

1.

i)

ii)

iii)

iv)

2. i)

ii) 3. i) H2/PdBaSO4 (Rosenmund reaction) ii) 40% H2SO4 and 1% HgSO4 iii) DIBAIH or AIH(iBu)2 4. i) Dilute NaOH

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ii) Dilute HCl

5. i) 3 2 3 2 4dil.HCl

Ethanenitrile Ethanoic acidCH CH CN CH CH COOH NH Cl

ii) 3 2 3 3dil.HClAcetamide Acetic acid

CH CONH CH COOH NH

iii) 4alk.KMnO6 5 2 3 6 5

Ethylbenzene Benzoic acid(Phenylethane)

C H CH CH C H COOH

iv) 2 46 5 2 5 6 5 2 5dil.H SO

Ethyl enzoate Beenzoic acid EthanolC H COO C H C H COOH C H OH

v) i.dry ice/dry ether ii. dil.HCl3 3 3

Methylmagnesium [complex] Acetic acidbromide

CH MgBr CH COOMgBr CH COOH Mg(OH)Br

Homework Problems

1. i)

ii)

2.

6 5 2 6 5 4

Benzonitrile Benzoic acidC H C N 2H O dil.HCl C H COOH NH Cl

3. The product obtained by reacting toluene with carbon monoxide and hydrogen chloride in presence of anhydrous aluminium chloride is 4-Methylbenzaldehyde.

4. Dry ice (Solid carbon dioxide) 5.

6. The product obtained by the oxidation of 1, 2, 3, 4tetrahydronaphthalene with acidified potassium permanganate is Phthalic acid or benzene 1, 2dicarboxylic acid.

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(164) Vidyalankar : Std. XII Chemistry


MODULE 3

MODULE OVERVIEW

12.6 Physical properties 12.6.1 Nature of intermolecular forces 12.6.2 Physical state and boiling points of aldehydes and ketones 12.6.3 Solubility of aldehydes and ketones 12.6.4 Physical state, boiling points and solubilities of carboxylic acids 12.7 Polarity of carbonyl group 12.7.1 Reactivity of aldehydes and ketones 12.8 Chemical properties of aldehydes and ketones 12.8.1 Laboratory tests for aldehydes and ketones 12.8.2 Chemical reactions of aldehydes and ketones with nucleophile a. Addition of hydrogen cyanide (HCN) b. Addition of NaHSO3 (Sodium bisulphite) c. Addition of alcohols d. Addition of Grignard reagent e. Nucleophilic addition elimination of aldehydes and ketones with ammonia f. Haloform reaction

1. Write a note on dipole-dipole attraction in carbonyl compounds. [2 M]

A. i) The carbonyl bond ( ) in aldehydes and ketones is a polar covalent bond. ii) As a result, these compounds contain dipole-dipole forces of attraction. iii) The molecules orient in such a way as to have oppositely polarized atoms facing

each other. This can be represented as,

2. Write a note on physical state of aldehydes and ketones. [2 M] A. i) Formaldehyde is a gas at room temperature and has irritating odour.

ii) Acetaldehyde is extremely volatile, colourless liquid.

iii) Higher aldehydes have pleasant odour.

iv) Acetone is a liquid at room temperature and has pleasant odour but most of the highest ketones have bland odours.

3. Arrange the following in increasing order of their boiling points. Justify. [2 M] i) Pentanal, Ethanal, Butanal, Propanal ii) Propanone, Hexan2one, Pentan2one

A. i) Boiling point of aldehydes increases in the homologous series as the number of Catoms increases. Therefore, the increasing order of boiling point is:

Ethanal < Propanal < Butanal < Pentanal

ii) Boiling point of ketones increases in the homologous series as the number of C-atoms increases. Therefore, the increasing order of boiling point is :

Propanone < Pentan2one < Hexan2one

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Note: Boiling points of aldehydes and ketones: Number of carbon

atoms Aldehyde Boiling point Ketone Boiling point

1 Methanal 252 K 2 Ethanal 294 K 3 Propanal 319 K Propanone 329 K 4 Butanal 348 K Butan2one 353 K 5 Pentanal 376 K Pentan2one 375 K 6 Hexanal 392 K Hexan2one 400 K

4. Justify. Lower aldehydes and ketones are water soluble as compared to higher aldehydes and ketones. [2 M]

A. i) The oxygen atom of (>C = O) group can involve in hydrogen bonding with water molecule.

Hydrogen bonding in carbonyl compound and water

ii) As a result of this, the lower aldehydes and ketones are water soluble (e.g. acetaldehyde, acetone).

iii) As the molecular mass increases, the proportion of hydrocarbon part of the molecule increases which cannot form hydrogen bond; and the water solubility decreases.

Commercially available formaldehyde and acetaldehyde: i) Formaldehyde is available commercially as solid polymer called paraformaldehyde

2 nHO [ CH O ] H and trioxane (CH2O)3 (Trioxane has cyclic structure). These are convenient for use in chemical reactions as source of formaldehyde.

ii) Aqueous solution of formaldehyde gas is called formalin, which is used for preservation of biological and anatomical specimens.

iii) When dry formaldehyde is required, it is obtained by heating paraformaldehyde or trioxane.

iv) Acetaldehyde is also conveniently used as solid trimer (paraldehyde) and tetramer (metaldehyde).

5. Explain the following physical properties of carboxylic acids: [3 M] i) Physical state ii) Boiling point A. i) Physical state: a. Lower aliphatic carboxylic acids upto nine carbon atoms are colourless

liquids with irritating odours. b. The higher homologues are colourless, odourless wax like solids and have

low volatility. ii) Boiling point: a. Carboxylic acids have higher boiling points than those of alkanes, ethers,

alcohols aldehydes and ketones of comparable mass. b. This because in liquid phase, carboxylic acids form dimer in which two

molecules are held by two hydrogen bonds.

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c. Acidic hydrogen of one molecule form hydrogen bond with carbonyl oxygen of the other molecule.

e.g.

Dimer of acetic acid (Two molecules

held by two hydrogen bonds)

d. This doubles the size of the molecule resulting in increase in intermolecular van der Waals forces which in turn results in high boiling point. In case of acetic acid, dimers exist even in the gas phase.

Note: Increasing boiling points of carboxylic acids:

Name Formula Boiling point in KFormic acid HCOOH 373 KAcetic acid CH3COOH 391 KPropionic acid CH2CH2COOH 414 KButyric acid CH3CH2CH2COOH 437 KValeric acid CH3CH2CH2CH2COOH 460 K

Note: Variation of boiling point with functional group:

Compound Family Molecular mass

Boiling point

Strength of intermolecular

forces CH3 CH2 CH2 CH3 Alkane 58 272 K CH3 O CH2 CH3 Ether 60 281 K CH3 CH2 CHO Aldehyde 58 322 K CH3 CO CH3 Ketone 58 329 K CH3 CH2 CH2 OH Alcohol 60 370 K CH3 COOH Carboxylic acid 60 391 K

6. Lower aliphatic carboxylic acids are miscible with water while higher

carboxylic acids are immiscible. Explain. [2M]

A. Lower aliphatic carboxylic acids are miscible with water due to the formation hydrogen bonding with water molecules.

Hydrogen bonding between acid and water. As the molecular mass increases the solubility of carboxylic acids in water decreases. The insolubility of carboxylic acids is due to increased hydrophobic interaction of hydrocarbon part.

increases

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7. Explain why carboxylic acids are much weaker acids than mineral acids? [3M] A. Carboxylic acids are the organic compounds which are acidic in nature. However,

compared to mineral acids like HCl, or H2SO4, the carboxylic acids are weaker acids. The strength of acidity depends upon their ability to release H+ ions. Greater the ease with which they release H+ ions, stronger is the acid. Carboxylic acids when dissolved in water, produce H+ due to its dissociation. (It does not dissociate completely.)

+

Hydrogen ionCarboxylic acid Carboxylic acid

O O|| ||

R C OH R C O H

The mineral acids like HCl, H2SO4 release H+ ion to a larger extent as they dissociate

almost completely in aqueous solution for e.g. HCl

H + Cl thus carboxylic acids are weaker than mineral acids.

The equilibrium exists in aqueous solution of carboxylic acid as

+2 3

Carboxylate ion

O O|| ||

R C OH H O R C O H O

K =

3

2

[RCOO ] [H O ][RCOOH] [H O]

Since concentration of water practically remains constant

Ka = K [H2O] = 3[RCOO ] [H O ]

[RCOOH]

where Ka is acidity constant

Larger the value of Ka, greater is the extent of ionization and stronger is the acid. But strength of acids is expressed in terms of their pKa values. Smaller the value of pKa, the stronger is the carboxylic acid. Here pKa value of carboxylic acids is higher than mineral acids. Hence, carboxylic acids are weaker than mineral acids.

8. Carbonyl carbon atom is susceptible to attack by a nucleophile. Justify. [2 M] A. i) The carbonyl bond (>C = O) is polar in nature. ii) The polarity of a carbonyl group originates from higher electronegativity of

oxygen relative to carbon as well as resonance effects. iii) This can be represented as,

iv) The carbonyl carbon has positive polarity (as shown in structures (I) and (IV)).

Therefore, it is electron deficient. v) As a result, this carbon atom is electrophilic (electron loving) and is susceptible to

attack by a nucleophile (Nu:).

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*9. Aldehydes are more reactive towards nucleophilic addition reactions than ketones. Explain. [3 M]

A. Reactivity of aldehydes and ketones is due to the polarity of carbonyl group which results in electrophilicity of carbon. In general, aldehydes are more reactive than ketones toward nucleophilic attack. This can be well explained in terms of both the electronic effects and steric effect.

i) Influence of electronic effects: a. Alkyl groups have electron donating inductive effect (+I). A ketone has two

electron donating alkyl groups bonded to carbonyl carbon which are responsible for decreasing its positive polarity and electrophilicity.

b. In contrast, aldehydes have only one electron donating group bonded to carbonyl carbon. This makes aldehydes more electrophilic than ketones.

ii) Steric effects:

a. Two bulky alkyl groups in ketone come in the way of incoming nucleophile. This is called steric hindrance to nucleophilic attack.

b. On the other hand, nucleophile can easily attack the carbonyl carbon in aldehyde because it has one alkyl group and is less crowded or sterically less hindered. Hence, aldehydes are more easily attacked by nucleophiles.

10. Explain Schiff’s reagent test OR What is a Schiff’s reagent? How is it used to detect aldehydes? [2M]

A. Schiff’s reagent is a dilute solution of pararosaaniline hydrochloride whose red colour has been discharged by passing SO2 gas. Aldehyde when treated with Schiff’s reagent (magenta solution in sulphurous acid) restores pink colour. This test is not given by ketones, hence to distinguish between aldehyde and ketone.

11. Explain Tollen’s reagent test OR Explain silver mirror test. [2M] A. Tollens’ Test

On warming an aldehyde with freshly prepared ammoniacal silver nitrate solution (Tollens’ reagent), a bright silver mirror is produced due to the formation of silver metal. The aldehydes are oxidised to corresponding carboxylate anion. The reaction occurs in alkaline medium.

3 2 2 3RCHO 2[Ag(NH ) ] 3OH R COO 2Ag 2H O 4NH

12. Explain Fehling’s solution test. [2M] A. Fehling’s Test

Fehling reagent comprises of two solutions, Fehling solution A and Fehling solution B. Fehling solution A is aqueous copper sulphate and Fehling solution B is alkaline sodium potassium tartarate (Rochelle salt). These two solutions are mixed in equal amounts before test. On heating an aldehyde with Fehling’s reagent, a reddish brown precipitate is obtained. Aldehydes are oxidised to corresponding carboxylate anion. Aromatic aldehydes do not respond to this test.

2

2 2Red brownppt

R CHO 2Cu 5OH R COO Cu O 3H O

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For example,

CH3 CO

H

22 Cu 4OH CH3 CO

OH 2 2Cu O 2H O

AcetaldehydeFehling's solution

Acetic acidRed ppt.

Note: Hydroxy ketone also gives this test positive. 13. Explain the laboratory test for ketonic group. [2 M]

OR Write a note on : Sodium nitroprusside test. A. i) A freshly prepared sodium nitroprusside solution is added to a ketone.

ii) The mixture is shaken well and then basified by adding sodium hydroxide solution drop by drop.

iii) If the colour of the solution becomes red, it indicates the presence of ketonic group.

iv) The anion of ketone formed by alkali reacts with nitroprusside ion to form a red coloured complex which indicates the presence of ketonic group.

e.g. Sodium nitroprusside test for acetone : 3 3 3 2 2

AcetoneCH CO CH OH CH CO CH H O

2 35 3 2 5 3 2

Nitroprusside ion Re d coluration[Fe(CN) NO] CH CO CH [Fe(CN) NO(CH CO CH )]

14. What is the action of hydrogen cyanide (HCN) on aldehydes and ketones? [3 M]

OR Explain cyanohydrin formation. A. i) Hydrogen cyanide (weak acid) adds across the carbon-oxygen double bond in

aldehydes and ketones to produce compounds called cyanohydrins. ii) The negative part of the reagent (CN) attacks the electrophilic carbon of

carbonyl group. iii) The reaction requires either acid or base as catalyst.

(a) When acetaldehyde is treated with hydrogen cyanide, acetaldehyde cyanohydrin is formed.

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(b) When acetone is treated with hydrogen cyanide, acetone cyanohydrin is formed.

(c) When benzaldehyde is treated with hydrogen cyanide, benzaldehyde cyanohydrin is formed.

HCN C

H

CN

OHC

H

O

Benzaldehyde cyanohydrinBenzaldehyde

15. Give reason: Cyanohydrins are used as intermediate in step up synthesis. [2M] A. i) Hydrogen cyanide (weak acid) adds across the carbon oxygen double bond in

aldehydes and ketones to produce compounds called cyanohydrins. ii) Cyanohydrin formation is a ‘stepup’ reaction as a new carboncarbon single

bond is formed. iii) The C N group can be converted to COOH, CH2NH2 and so on.

Therefore, cyanohydrins are used as intermediate in step up synthesis. 16. What is the action of hydrogen cyanide in basic medium on (1) butanone

(2) 2,4-dichlorobenzaldehyde ? [2M]

A. (1) Action of hydrogen cyanide on butanone: When butanone is treated with hydrogen cyanide, butanone cyanohydrin is obtained.

(2) Action of hydrogen cyanide on 2,4-dichlorobenzaldehyde: When

2, 4-dichloro benzaldehyde is treated with hydrogen cyanide, cyanohydrin of 2,4-dichloro benzaldehyde is obtained.

HCN

Cl

CHO

Cl

Cl

Cl

H COH

CN

2H O

2, 4-Dichlorobenzaldehyde Cyanohydrin of 2,4-Dichloro benzaldehyde

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17. What is the action of sodium bisulphate on : [2M] i) Acetaldehyde ii) Acetone [July 2017]

A. Most of the aldehydes and aliphatic methyl ketones (which are not sterically hindered) when treated with saturated sodium bisulphite solution add a molecule of sodium bisulphite to form bisulphite addition compounds Amongst aromatic aldehydes and ketones, benzaldehyde forms a sodium bisulphite adduct but acetophenone does not.

The driving force for the proton transfer from I to II is due to the resonance

stabilization of the 3SO group. Thus,

i) Acetaldehyde reacts with saturated aqueous solution of sodium bisulphite (NaHSO3) and forms crystalline acetaldehyde sodium bisulphite.

ii) Acetone reacts with saturated aqueous solution of sodium bisulphite (NaHSO3)

and forms crystalline acetone sodium bisulphite.

18. What is the action of alcohols on aldehydes? [2M] A. i) Aldehyde reacts with one molecule of anhydrous monohydric alcohol in presence

of dry hydrogen chloride to give alkoxyalcohol known as hemiacetal. ii) This further reacts with one more molecule of anhydrous monohydric alcohol to

give a germinal dialkoxy compound known as acetal. iii) Acetals can be hydrolysed with aqueous mineral acids to give corresponding

aldehydes. iv) The reaction can be represented into following steps: Step 1:

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Step 2: 19. Convert: Acetaldehyde into 1, 1diethoxyethane. [2M] A. Acetaldehyde into 1, 1diethoxyethane:

Step 1 : Step 2 : 20. What is the action of alcohols on ketones ? [2 M] A. i) Ketones react with alcohol in presence of acid catalyst to form hemiketal and

ketal. ii) Ketals can be hydrolysed with aqueous mineral acids to give corresponding

aldehydes. iii) The reaction can be represented as follows :

21. What is the action of 1, 2 or 1, 3diols on ketones in presence of dry hydrogen chloride? [2 M] A. Ketones react with 1, 2 or 1, 3 diols in presence of dry hydrogen chloride to give

five or six membered cyclic ketals.

The reaction can be reversed by treating the cyclic ketal with aqueous HCl to

regenerate the ketone.

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22. What is the action of following compounds on cyclohexanone in presence of dry hydrogen chloride? [2M]

i) Ethyl alcohol ii) Ethylene glycol A. i) With Ethyl alcohol : Cyclohexanone reacts with one equivalent of monohydric

ethyl alcohol to form hemi ketal, which further adds another molecule of alcohol to form a gem-dialkoxy compound known as ketal.

ii) With ethylene glycol : Cyclohexanone reacts with ethylene glycol to form cyclic ketal.

23. How does Grignard reagent react with the carbonyl compounds: [2M] (or aldehydes and ketones) ? A. Aldehydes and ketones add on Grignard reagents to form addition products which

upon hydrolysis with water or dil. Mineral acids give alcohols 24. What is the action of Grignard reagent, CH3 MgI on : [2M] i) formaldehyde ii) acetone ? A. i) Grignard reagent with formaldehyde gives a primary alcohol.

Formaldehyde on reaction with Grignard reagent, CH3MgI in dry ether forms a complex which on hydrolysis with dilute HCl forms ethyl alcohol.

Secondary alcohol

Tertiary alcohol

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ii) Acetone on reaction with Grignard reagent, CH3MgI in dry ether forms a complex

which on hydrolysis with dilute HCl forms tert-butyl alcohol.

25. Explain the mechanism of addition reactions of ammonia derivatives H2NZ

with carbonyl compounds (aldehydes or ketones). [2 M] A. Derivatives of ammonia H2NZ reacts with carbonyl compounds (aldehydes or

ketones) in acidic medium to give addition products, which loses a water molecule to give a final product imine derivatives. A substituted imine is called a Schiff base. Schiff bases are solids and have sharp melting points.

General Reactions :

General Mechanism:

These reactions are useful for characterization of the original aldehydes and ketones.

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C N OH

26. What is the action of ethylamine on: i) acetaldehyde ii) acetone? [2M] A. i) Acetaldehyde on reaction with ethyl amine forms imine (Schiff base).

ii) Acetone on reaction with ethyl amine forms imine (Schiff base).

27. What are oximes? Which functional group do they contain? [1M] A. Oximes : These are the compounds obtained by the reaction of carbonyl compounds

namely aldehydes and ketones with hydroxyl amine NH2OH.

The oximes contain as a functional group. Example :

28. What is the action of hydroxyl amine (NH2OH) on : [3M] i) Formaldehyde (methanal) ii) Acetaldehyde (ethanal) iii) Acetone (propanone) A. i) Methanal on reaction with hydroxyl amine forms crystalline methanal oxime.

ii) Ethanal on reaction with hydroxyl amine forms ethanal oxime. iii) Propanone on reaction with hydroxyl amine forms propanone oxime.

Acetaldehyde (Ethanal)

Acetone (Propanone)

Formaldehyde (Methanal)

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29. What are hydrazones? [1M] A. Carbonyl compounds like aldehydes and ketones react with hydrazine forming

compounds like hydrazones. For example, acetaldehyde on reaction with hydrazine gives acetaldehyde hydrazone.

30. What is the action of hydrazine on : [3M] i) Formaldehyde (methanal) ii) Acetaldehyde (ethanal) iii) Acetone (propanone) A. i) Formaldehyde on reaction with hydrazine forms formaldehyde hydrazone. ii) Acetaldehyde (ethanal) on reaction with hydrazine acetaldehyde hydrazone. iii) Acetone with hydrazine forms acetone hydrazone

31. What are phenylhydrazones? [1M] A. The carbonyl compounds like aldehydes and ketones on reaction with

phenylhydrazine form hydrazones. For example, acetaldehyde on reaction with phenylhydrazine forms acetaldehyde phenylhydrazone.

32. What is the action of phenylhydrazine on : [3M] i) Formaldehyde ii) Acetaldehyde iii) Acetone [July 2017] A. i) Formaldehyde on reaction with phenylhydrazine forms formaldehyde

phenylhydrazone.

Formaldehyde(Methanal)

Hydrazine Formaldehyde hydrazone

(Methanal hydrazone)


Acetaldehyde hydrazone (Ethanal hydrazone)

Hydrazine

Acetone (Propanone)

Hydrazine Acetone hydrazine

(Propanone hydrazone)

Formaldehyde (Methanal)

Phenylhydrazine Formaldehyde phenylhydrazone

(Methanal phenylhydrazone)

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Acetone (Propanone)

ii) Acetaldehyde on reaction with phenylhydrazine forms acetaldehyde phenylhydrazone.

iii) Acetone on reaction with phenylhydrazine forms acetone phenylhydrazone.

33. What is the action of 2,4-dinitrophenyl hydrazine on : [3M] i) Acetaldehyde ii) Acetone iii) Butanone [Feb 2018] A. i) Acetaldehyde on reaction with 2,4-dinitrophenyl hydrazine forms

2,4-dinitrophenyl hydrazone. ii) Acetone on reaction with 2,4-dinitrophenyl hydrazine forms 2,4-dinitrophenyl

hydrazone.

iii)

Butanone on reaction with 2,4-dinitrophenyl hydrazine forms 2,4-dinitrophenyl hydrazone.

34. What is the action of semicarbazide on : [2M] i) Acetaldehyde ii) Acetone A. i) Acetaldehyde on reaction with semicarbazide forms semicarbazone derivative.


Acetaldehyde phenylhydrazone (Ethanal phenylhydrazone)

Phenylhydrazine

Acetone (Propanone)

Propanone phenylhydrazone Phenylhydrazine

Acetaldehyde(Ethanal)


NO2

NO2NHNH2H3 2 3CH CH C CH

ONO2

NO2NHNC

CH3

CH2CH3

2, 4-Dinitrophenylhydrazine

+

Butanone

Butanone 2,4-Dinitrophenyl hydrazone + H2OVidyala

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ii) Acetone on reaction with semicarbazide forms semicarbazone derivative. 35. Write a note on the haloform reaction. [2M] A. i) This reaction is given by acetaldehyde, all methyl ketones (CH3 CO R) and all

alcohols containing CH3(CHOH) group. ii) When an alcohol or methyl ketone is warmed with sodium hydroxide and iodine, a

yellow precipitate is formed. Here the reagent sodium hypoiodite is produced in situ. iii) During the reaction, sodium salt of carboxylic acid is formed which contains one

carbon atom less than the substrate. iv) The methyl group is converted into haloform (CHX3)

e.g. Acetone is oxidized by sodium hypoiodite to give sodium salt of acetic acid and yellow precipitate of iodoform.

Note: This reaction can be used to distinguish methyl ketones (CH3CO ) from ketones.

36. Explain the principles of distinction between aldehydes and ketones. [2M] A. i) The principles of distinction between aldehydes and ketones is the stronger

reducing property of aldehydes.

ii) Due to the presence of hydrogen atom in aldehyde group |

H

( C O), an aldehyde

is oxidised to carboxylic acid |

OH

( C O) which is not easily possible in case of ketones.

iii) Hence aldehydes reduce Fehling’s solution, Tollen’s reagent, Schiff’s reagent etc. giving characteristic colours, but ketones do not give these tests.

37. Give a chemical test to distinguish between following pairs of compounds. [3M] i) Ethanal and propanone ii) Propanal and propanone iii) Pentan2one and Pentan3one A. i) Ethanal and propanone

Test Ethanal (CH3CHO) Propanone (CH3COCH3) 1) Add Fehling solution to both and warm 2) Add few drops of ammoniacal AgNO3 to both and heat (Tollen’s reagent Test)

It reduces FehlingSolution, red ppt. of Cu2O is formed silver mirror is formed

No change No change

Acetone (Propanone)

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ii) Propanal and Propanone

Test Propanal (CH3CH2CHO) Propanone (CH3COCH3) 1) Add NaOH and I2 to both, shake and warm. 2) Fehling solution test

No characteristic ppt. It reduces Fehling solution and red ppt. of Cu2O is formed.

Yellow ppt. of CHI3 formed. No change

iii) Pentan2one and Pentan3one

Test Pentan-2-one Pentan-3-one Add NaOH and I2 to both, shake and warm

Yellow ppt. of Iodoform No reaction (The reaction does not occur because CH3C=O group is absent)

.Solved Problems.

Problem 1 Write the structure of the product in the following conversions :

Solution :

Problem 2 Write the structure of the products obtained from the following ketones by action of

hydrazine in presence of (1) slightly acidic medium (2) strong base KOH.

(a) (b)

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Solution :

Problem 3 Predict the major products in the following reactions.

i)

ii)

iii)

iv)

v)

Solution: i)

ii)

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iii)

iv)

v) Problem 4 Arrange the following compounds in increasing order of their reactivity in nucleophilic

addition reactions : a) Ethanal, Propanal, Propanone, Butanone b) Benzaldehyde, pTolualdehy de, pNitrobenzaldehyde, Acetophenone

The reactivity of carbonyl compounds depends upon i) inductive effect ii) steric effect. Solution:

a) We know that when alkyl group increase on the carbon of the carbonyl group due to (+I) inductive effect, the +ve charge on the carbon atom of the carbonyl group progressively decreases and hence attack by nucleophile become slower.

Thus, the reactivity increases in the order Butanone < Propanone < Propanal < Ethanal

b) Acetophenone is a ketone, therefore it is least reactive in among these compounds. In ptolualdehyde, methyl group attach at the para position. So electron density increases or positive charge decreases on the carbon of carbonyl group by hyper conjugation effect, thereby making less reactive than benzaldehyde.

In pnitro benzaldehyde, the nitro group has an opposing effect. I is electron withdrawing in nature due toinductive effect as well as resonance effect. So the electron density on the carbon of carbonyl group decrease and thus favours the nucleophilic attack. Thus, the reactivity increases in the order.

Acetophenone < p-Tolualdehyde < Benzaldehyde <pNitrobenzaldehyde.

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1. Identify the compounds, amongst the following, that give positive iodoform test. (CH3)2CHOH, (CH3)3COH, CH3COCH2CH2CH3, CH3CH2CHO, CH3CH2CH(OH)CH2CH3, CH3CH2OH, C6H5COCH2CH3, CH3CHO, C6H5CH2CH2OH and CH3CH(OH)CH2CH2CH3.

2. How will you convert benzaldehyde into following compounds ? More than one step may be required.

i) Benzophenone ii) Benzoic acid iii) 3-Phenyl propan-1-ol iv) -Hydroxyphenyl acetic acid.

3. What is the action of the following reagents on ethanal : i) Fehling’s solution, ii) Tollen’s reagent or Ammonical silver nitrate

4. Draw the structures of, i) the semicarbazone of cyclohexanone ii) the imine formed in the reaction between 2methylhexanal and ethylamine.

5. Draw the structures of carbonyl compounds and ammonia derivatives that combine to give following imines :

6. Write chemical reactions taking place when propan2ol is treated with iodine and

sodium hydroxide.

7. Arrange the following compounds in the increasing order of their boiling points: i) Dimethyl ether, ethyl alcohol, propane, acetaldehyde. ii) Acetone, n-propyl alcohol, ethyl methyl ether and n-butane.

8. Arrange the following carbonyl compounds in the decreasing order towards the addition of hydrogen cyanide.

Benzaldehyde, formaldehyde, acetone, acetaldehyde. .Homework Problems.

1. How will you effect following two-step conversions? i) Propanal into butanone ii) Butanone into but2ene iii) Benzene into m- bromoacetophenone iv) Hex3yne into Hexan3one v) Benzoic acid into m-nitrobenzylalcohol. 2. Identify A and B in the following :

i) H C N 3CH MgI 2HOH3HCl

A B NH MgIOH

ii) CH3 Mg Br 3CH CN HOH3H

A B NH MgBrOH

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Δ 2 3|

dil. Na CO3 2

|

H

A CH C CH

OHC

O

HΔ

H

2B H O

3. Identify A and B in the following :

i)

ii) Dry ether dil. HCl3 3 2CH CHO CH MgCl A B MgCl

iii) H Na

3 2CH CHO A B H

*4. What is formalin?

*5. Arrange the following compounds in the increasing order of their boiling points: Formaldehyde, ethane, methyl alcohol.

*6. Observe the following equation of reaction of Tollen’s reagent with aldehyde. How do we know that a redox reaction has taken place? Explain.

R CHO + 2Ag(NH3)2+ + OH R COO + 2Ag + 4NH3 + 2H2O

*7. Write reaction showing conversion of acetaldehyde into acetaldehyde dimethyl acetal.

8. Predict the product of the following reaction ?

Classwork Problems

1. (CH3)2CHOH, CH3CH2OH, CH3CH(OH) CH2CH2CH3, CH3COCH2CH2CH3, CH3CHO.

2. i) Benzophenone :

OR

ii) Benzoic acid :

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iii) 3-Phenyl propan-1-ol :

iv) -Hydroxyphenyl acetic acid. 3. i) When ethanal is heated with Fehling’s solution, the deep blue colour of the

solution disappears and a red precipitate of Cu2O is obtained.

ii) When ethanal is heated with Tollen’s reagent a greyish black precipitate or

deposition of silver is obtained.

4. i) Semicarbazone of cyclohexanone :

ii) Imine formed in the reaction between 2methylhexanal and ethylamine.

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Note : Secondary alcohols having CH3 CHOH group give positive iodoform test because the reagent first oxidizes it to a CH3 CO group which subsequently forms iodoform.

7. i) Propane < dimethyl ether < acetaldehyde < ethanol (Among all compounds ethanol undergoes intermolecular hydrogen bonding,

therefore its boiling point is highest. Acetaldehyde is more polar than dimethyl ether, therefore, acetaldehyde has higher boiling point than dimethyl ether. In propane, there are weak van der Waals forces and hence it has lowest boiling point.)

ii) n-butane < Ethyl methyl ether < Acetone < n-propyl alcohol.

8. Formaldehyde > Acetaldehyde > Acetone > Benzaldehyde Homework Problems

1. i)

ii)

5.

6.

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iii)

iv)

v)

2. i)

|

3

A) H C NMgl

CH

|

3

OB)H C

CH

ii) 3 |

3

A)CH C NMgBr

CH

3 |

3

B) CH C O

CH

3. i) 3 ||A) 2 CH C H

O

||

3 | |

O

B)CH C C C H

H H

ii) |

3 |

3

H

A)CH C OMgCl

CH

3|

B)CH CH OH

CH3

iii) 3 2A)CH CH OH 3 2B)CH CH ONa 4. Aqueous solution of formaldehyde gas is called formalin. 5. Ethane < Formaldehyde < Methyl alcohol 6. When an aldehyde is boiled with Tollen’s reagent, it gets oxidized to carboxylate ion

and Ag+ ion is reduced to silver (Ag). The oxidation number of carbon in aldehyde increases while oxidation number of Ag decreases. Hence, this is a redox reaction.

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7. Acetaldehyde into acetaldehyde dimethyl acetal.

8.

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MODULE 4

MODULE OVERVIEW 12.8.2 Chemical reactions of aldehydes and ketones with nucleophile g. Aldol condensation h. Cannizzaro reaction 12.8.3 Oxidation and reduction reactions of aldehydes and ketones a. Oxidation of aldehydes and ketones by dilute HNO3, KMnO4 and K2Cr2O7 b. Clemmensen and WolfKishner reduction 12.8.4 Electrophilic substitution reactions

12.9 Chemical properties of carboxylic acids 12.9.1 Acidic character of carboxylic acids 12.9.2 Laboratory tests for carboxyl (COOH) group 12.9.3 Formation of acyl chloride 12.9.4 Reaction with ammonia 12.9.5 Formation of acid anhydride 12.9.6 Decarboxylation of carboxylic acids 12.9.7 Reduction of carboxylic acids

1. Explain aldol condensation with suitable examples. [3 M] A. Aldol condensation:

i. Aldehydes containing at least one hydrogen atom undergo a reaction in presence of dilute alkali (dilute NaOH, KOH or Na2CO3) as catalyst to form hydroxy aldehydes (aldol). This reaction is known as aldol reaction.

ii. Formation of aldol is an addition reaction. iii. Aldol formed from aldehyde having hydrogens undergoes subsequent

elimination of water molecule on warming. This gives rise to , unsaturated aldehyde.

iv. The overall reaction is called aldol condensation. It is a nucleophilic addition elimination reaction.

v. The reaction can be given as,

vi. Ketones containing at least two hydrogen also undergo aldol condensation

reaction and give an , -unsaturated ketone. e.g.

e.g.

e.g.

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:OH

2. How is 4-methylpent-3-en-2-one obtained from propan2one.[March 2013, 1M] A. Refer answer to Q.1. The Mechanism of aldol condensation reaction:

Step 1 : Base (OH) abstracts a hydrogen atom from -carbon of aldehyde to form carbanion.

Step 2 : The nucleophilic carbanion (enolate ion) attacks electrophilic carbonyl carbon of second aldehyde molecule.

Step 3 : Alkoxide ion abstracts a hydrogen ion from water to form -hydroxy aldehyde. Base OH ion is regenerated.

3. Explain crossed aldol condensation. [3 M] A. Crossed aldol condensation :

i. It refers to the aldol condensation that takes place in between two different aldehydes or ketones.

ii. If both aldehydes or ketones contain two hydrogen atoms each, then a mixture of four products, is formed.

iii. For example, a mixture of ethanol and propanal on reaction with dilute alkali followed by heating gives a mixture of four products.

iv. Ketones can also be used as one of the components in cross aldol condensation. Self Condensation :

+ H2O

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Cross aldol condensation :

* 4. Write a note on Cannizzaro reaction. [3M] OR

Write a note on self oxidation-reduction reaction of aldehyde with suitable example. [M-2014, July 2017, 2M]

A. 1) Aldehydes which do not have -hydrogen atom, on heating with concentrated alkali (50% aqueous or ethanolic solution of NaOH or KOH) undergo self oxidation and reduction reaction or redox reaction.

2) This self-redox reaction or disproportionation reaction is called Cannizzaro reaction.

3) In this reaction one molecule of the aldehyde is oxidized to carboxylic acid while the second molecule of the aldehyde is reduced to alcohol (carboxylic acid formed, reacts with alkali, NaOH and forms a salt R COONa).

4) When formaldehyde (methanal) is heated with 50% NaOH solution, methanol, (reduction product) and sodium formate (oxidation product) are formed.

Similarly, benzaldehyde gives Cannizzaro reaction.

5) Ketones and aldehydes like acetaldehyde, propionaldehyde, etc. having H atom do not give Cannizzaro reaction.

6) Crossed Cannizzaro Reaction : The reaction between two different aldehydes, not having -hydrogen atom is called cross Cannizzaro reaction. These two aldehydes undergo disproportionation in presence of concentrated alkali to give four products. However, if one of the aldehydes is formaldehyde, the reaction yields exclusively formate and alcohol to corresponding aldehyde.

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5. Complete and rewrite the balanced chemical equations : 50% KOHIsobutyraldehyde ? [Feb-2018, 1M] A.

6. Differentiate between Cannizzaro reaction and Aldol reaction. [2M] A.

Cannizzaro reaction Aldol reaction 1. It is given by aldehydes not having alpha hydrogen atom.

It is given by aldehydes and ketones possessing alpha hydrogen atom.

2. In this reaction an aldehyde is converted to the corresponding acid and an alcohol.

In this reaction aldehydes and ketones are converted into aldol and ketols, respectively.

3. It is a disproportionate ion reaction. It is an addition reaction 4. It requires concentrated alkali as a catalyst.

It requires dilute alkali as a catalyst.

7. Explain oxidation of aldehydes and ketones to carboxylic acids. [3 M] A. i. Aldehydes : They are oxidized to the corresponding carboxylic acids by oxidant

such as dilute nitric acid, potassium permanganate and sodium or potassium dichromate in acidic medium.

2 2 7

2 4

K Cr Odil.H SOAldehyde Carboxylic acid

R CHO R COOH

ii. Ketones :They resist oxidation due to strong CO C, but they are oxidized by strong oxidizing agents such as CrO3, alkaline KMnO4 or hot concentrated HNO3 to a mixture of carboxylic acids having less number of carbon atoms than the starting ketone. Thus, the oxidation of ketones is accompanied by breaking of C C bond.

e.g

8. Explain the reduction of aldehydes and ketones with zinc amalgam and conc. HCl. [2 M]

OR Write a note on Clemmensen reduction.

A. Clemmensen reduction: i. The carbonyl group of aldehydes and ketones is reduced to methylene group

( CH2 ) on treatment with zinc amalgam and concentrated hydrochloric acid. This reaction is known as Clemmensen reduction.

50%KOH3 3 3 22 CH CH C H CH CH C OK CH CH CH OH

CH3

O

CH3

O

CH3

Isobutyraldehyde K-Isobutyrate 2-Methylpropanol

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e.g a. Acetone on Clemmensen reduction gives propane. Zn Hg conc.HCl

3 3 3 2 3 2Acetone Propane

CH CO CH 4[H] CH CH CH H O

b. Propanal on Clemmensen reduction gives propane. Zn Hg conc.HCl

3 2 3 2 3 2Propanal Propane

CH CH CHO 4[H] CH CH CH H O

9. Explain WolffKishner reduction. [2 M] A. Wolff Kishner reduction :

i. The carbonyl group of aldehydes and ketones is reduced to methylene group ( CH2 ) on treatment with hydrazine followed by heating with sodium or potassium hydroxide in high boiling solvent like ethylene glycol. This reaction is known as WolffKishner reduction.

ii. In this reaction, oxygen is replaced by two hydrogen atoms.

e.g.

iii. WolfKishner reduction is used to synthesize straight chain alkyl substituted

benzenes which is not possible by Friedel Crafts alkylation reaction. 10. Explain electrophilic substitution reaction of aromatic aldehydes and ketones.

[2 M] A. i. Aromatic aldehydes and ketones undergo electrophilic substitution reactions

such as nitration , sulfonation and halogenation. ii. The aldehydic ( CHO) and ketonic groups are electron withdrawing by inductive

as well as resonance effects. iii. They deactivate the benzene ring at ortho and para positions. This results in the

formation of metaproduct. e.g. When benzaldehyde is treated with concentrated nitric acid in presence of conc. sulphuric acid, m-nitrobenzaldehyde is obtained.

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11. Explain the acidic character of carboxylic acids. [2 M] A. i. The carboxyl group (COOH) imparts acidic character to carboxylic acids.

ii. A carboxyl group is made of OH group bonded to a carbonyl group.

iii. In aqueous solution, the H atom in OH of carboxyl group dissociates as proton and carboxylate ion is formed as the conjugate base,

iv. Carboxylate ion is resonance stabilized by two equivalent resonance structures as shown below.

v. Carboxylate ion has two resonance structures (I) and (II) and both of them are

equivalent to each other.

vi. This gives good resonance stabilization to carboxylate ion, which in turn gives acidic character to carboxylic acids.

12. Discuss the acidic nature of haloacetic acid. [3 M]

OR Explain the influence of electronic effects on acidity of haloacetic acid.

A. i. All the carboxylic acids do not have the same pKa value. The structure of ‘R’ in RCOOH has influence on the acid strength of carboxylic acids.

ii. Halogens are electronegative atoms and exert electron withdrawing inductive effect (I effect).

iii. The negatively charged carboxylate ion in the conjugate base of haloacetic and gets stabilized by the I effect of halogen which is responsible to diffuse the negative charge.

iv. Higher the electronegativity of halogen, greater is the stabilization of the

conjugate base, stronger is the acid and smaller is the pKa value. For example, increasing order of acid strength is: CH3 COOH < I CH2 COOH < Br CH2 COOH < Cl CH2 COOH < F

CH2 COOH

v. Also, more the number of electron withdrawing substituents, higher is the acid strength.

For example, increasing order of acid strength is: Monochloroacetic acid < Dichloroacetic acid< Trichloroacetic acid.

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Note: i. pKa values of haloacetic acids:

Acid pKa Acid strength FCH2COOH 2.56

Decreases

ClCH2COOH 2.86 BrCH2COOH 2.90 ICH2COOH 3.18 CH3COOH 4.76

ii. pKa values of chloroacetic acids: Acid Structure pKa Acid strength

Monochloroacetic acid ClCH2COOH 2.86 increases

Dichloroacetic acid

1.26

Trichloroacetic acid

0.6

13. Carboxylic acids are more acidic than phenols and alcohols. Explain why? [3M]

A. 1) Carboxylic acid loses a proton as compared to phenol. Consider the ionization of carboxylic acid and phenol

Alc ohol Alkoxide ion

R OH R O H

+2 2

Carboxylate ion

O O|| ||

R C OH H O R C O H O

Due to delocalization the negative charge over the ortho and para positions of aromatic ring phenoxide anion is more stable than phenol. Thus phenol easily undergoes ionization.

However, alcohol and alkoxide ion are single structures. In an alkoxide anion the

negative charge is localized on a single oxygen atom. Hence, phenols are more acidic than alcohols.

2) Carboxylic acid has two resonance hybride non equivalent structures (I & II) while carboxylate anion has two resonance hybrid equivalent structures (III & IV). The carboxylate ion is more stable than carboxylic acid and equilibrium is shifted towards the direction of increased ionization.

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Carboxylate ion has two equivalent resonance structures with negative charge is delocalized over two electronegative oxygen atoms. Phenoxide anion has nonequivalent resonance structures in which negative charge is delocalized over one oxygen atom and less electronegative carbon atom. As a result carboxylate anion is more stable than phenoxide ion. Hence carboxylic acids ionize to the greater extent than phenol furnishing higher concentration of H+ ions. Therefore, carboxylic acids are more acidic than phenols and alcohols.

*14. Formic acid is stronger than acetic acid. Explain. [2 M]

A. i. The negatively charged acetate ion (i.e. conjugate base of acetic acid) gets destabilized by +I effect of CH3 group.

ii. Lesser is the stabilization of the conjugate base, weaker is the acid. iii. In format ion, there is no such destabilization effect. Thus, formic acid is stronger than acetic acid.

*15. Arrange the following carboxylic acids with increasing order of their acidic strength and justify your answer. [2 M]

(i) (ii) (iii)

A. i. Increasing order of their acidic strength: ii > iii > i. ii. Oxygen atom is electronegative and exerts electron withdrawing inductive effect

(I effect). iii. Thus, compound (ii) and (iii) are more acidic as compared to (i). iv. However, the inductive effect decreases as the oxygen in the ring moves away

from the carboxyl group. Therefore, compound (iii) is less acidic than compound (ii).

16. Discuss the acidity of aromatic carboxylic acids. [2 M] A. i. Benzoic acid is the simplest aromatic acid. Benzoic acid (pKa = 4.2) is stronger

than acetic acid (pKa = 4.76). ii. The sp2 hybrid carbon of aromatic ring exerts electron withdrawing inductive

effect (I effect) which stabilizes the conjugate base and increases the acid strength of aromatic acids.

iii. Electron withdrawing groups like Cl, CN, and NO2 increases the acidity of substituted benzoic acids while electron donating groups like CH3, OH, OCH3 and NH2 decrease the acidity of substituted benzoic acids.

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17. Explain the laboratory tests for carboxyl group. [3 M] OR

How will you detect the presence of COOH group. A. Laboratory tests for carboxyl (COOH) group: The presence of COOH group in carboxylic acids is identified by the following tests: i. Litmus test: This test is valid for water soluble substances.

Aqueous solution of organic compound containing COOH group turns blue litmus red which indicates the presence of acidic functional group.

Note: The aqueous solutions of water soluble phenols also turn blue litmus red.

ii. Sodium bicarbonate test: a. When sodium bicarbonate is added to an organic compound containing

COOH group, a brisk effervescence of carbon dioxide gas is evolved. b. Water insoluble acid goes in solution and gives precipitate on acidification

with conc. HCl. This indicates the presence of COOH group. 2

2

CO HCl3(aq) (aq) (aq)H OWater insoluble

R COOH NaHCO R COONa R COOH NaCl

c. Phenol does not evolve CO2 gas with sodium bicarbonate. Hence, carboxylic acid and phenol are distinguished by this test.

iii. Ester test: a. One drop of concentrated sulfuric acid is added to a mixture of given organic

compound containing COOH group and one mL of ethanol. b. The reaction mixture is heated for 5 minutes in hot water bath. c. After this hot solution is poured in a beaker containing water. d. Fruity smell of ester confirms the presence of carboxylic acid. H

2 5 2 5 2warm EsterR COOH C H OH R COO C H H O

18. How is acid chloride obtained from carboxylic acid? [3 M] A. Carboxylic acid on heating with thionyl chloride (SOCl2), phosphorus trichloride (PCl3)

or phosphorus pentachloride (PCl5) give corresponding acid chlorides. In this reaction OH of carboxyl group is replaced by Cl.

The reactions are :

1) Action of SOCl2 on carboxylic acid :

2 2Carboxylic acid Acid chloride

O O|| ||

R C OH SOCl R C Cl HCl SO

Example : Acetic acid reacts with thionyl chloride to give acetyl chloride.

3 2 3 2Acetic acid Acetyl chloride

O O|| ||

CH C OH SOCl CH C Cl HCl SO

2) Action of PCl3 on carboxylic acid :

3 3 3Carboxylic acid Acid chloride

O O|| ||

3R C OH PCl 3R C Cl H PO

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Example: Action of phosphorus trichloride on acetic acid gives acetyl chloride.

Heat3 3 3 3 3

Acetic acid Acetyl chloride(Ethanoic acid)

O O|| ||

3CH C OH PCl 3 CH C Cl H PO

[Feb-2018]

3) Action of PCl5 on carboxylic acid:

5 3

O O|| ||

R C OH PCl R C Cl POCl HCl

3 5 3 3Acetic acid Acetyl chloride

O O|| ||

CH C OH PCl CH C Cl POCl HCl

19. How is acid amide obtained from carboxylic acid? [2M] A. Carboxylic acid or acid chloride with ammonia salts, which on heating decompose to

give amides.

3 4 2 2AmideAmmonium salt of acidCarboxylic acid

O O O|| || ||

R C OH NH R C O NH R C NH H O

When acetic acid is treated with ammonia, ammonium acetate is obtained. Ammonium acetate on heating decomposes to form acetamide.

3 3 3 4 3 2 2Acetic acid Ammonium acetate Acetamide

O O O|| || ||

CH C OH NH CH C ONH CH C NH H O

When acetyl chloride is treated with ammonia, acetamide is obtained

3 3 3 2

Acetyl chloride Acetamide

O O|| ||

CH C Cl NH CH C NH HCl

When phthalic acid is treated with ammonia, ammonium phthalate is obtained. Ammonium phthalate on heating decomposes to give phthalimide.

20. How will you convert 3, 5Dinitrobenzoic acid to 3, 5Dinitrobenzoyl chloride? [1M] A. When 3,5Dinitrobenzoic acid is heated with phosphorus pentachloride,

3, 5Dinitrobenzoyl chloride is obtained.

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21. How is acid anhydride obtained from carboxylic acid? [2M] A. When carboxylic acid is heated with strong dehydrating agent like phosphorus

pentoxide or concentrated sulphuric acid, an acid anhydride is obtained,

2 5P O2

Acid anhydride

O O O O|| || || ||

R C O H HO C R R C O C R H O

(i) With acetic acid (Ethanoic acid) [Feb-2018, 1M]

2 5P O3 3 3 3 2

Acetic acid (Ethanoic acid) Acetic anhydride

O O O O|| || || ||

CH C O H HO C CH CH C O C CH H O

The reaction is reversible and anhydride is hydrolysed back to acid.

(ii) Alternatively, when sodium acetate is heated with acetyl chloride, acetic anhydride is obtained. This reactions is irreversible.

3 3 3 3Acetyl chloride Sodium acetate Acetic anhydride

O O O O|| || || ||

CH C Cl CH C ONa CH C O C CH NaCl

(CH3 COOH + SOCl2 CH3COCl; CH3 COOH + NaOH CH3 COONa + H2O)

22. How is alcohol obtained from carboxylic acid? [2M] A. Carboxylic acids are reduced to primary alcohols using powerful reducing agent

lithium aluminium hydride.

4

3

1.LiAIH ,ether22.H O

O||

R C OH R CH OH

(i) With acetic acid (Ethanoic acid) [Feb-2018, 1M] When acetic acid (ethanoic acid) is reduced in the presence of lithium aluminium hydride in ether, forms ethanol.

4

3

||LiAlH ,ether

3 3 2H O

O

CH C OH CH CH OH

Ethanoic acid Ethanol

(ii) When cyclopropane carboxylic acid is reduced in the presence of lithium aluminium hydride in ether, forms cyclopropyl methanol.

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Note: i. Diborane does not reduce COOR, NO2, X. ii. Sodium borohydride (NaBH4) does not reduce COOH group. 23. How is hydrocarbon obtained from carboxylic acid? OR

Explain decarboxylation. OR How will you convert sodium acetate to methane? [Feb.-2019, 2M]

A. When anhydrous sodium salt of carboxylic acid is fused with soda lime (sodium hydroxide and calcium oxide in the ratio 3:1), a hdydrocarbon is obtained. A hydrocarbon formed contains one carbon atom less than carboxylic acid.

CaO2 3AlkaneSodium salt of carboxylic acid

O|| _

R C ONa NaOH R H Na CO

When sodium acetate is heated with soda lime, methane is obtained.

CaO3 4 2 3

Sodium acetate Methane

O|| _

CH C ONa NaOH CH Na CO

24. How are the following compounds obtained from benzoic acid? [2M] 1) mNitrobenzoic acid [July 2016] 2) mBromobenzoic acid [Feb.-2019]

A. 1) When benzoic acid is treated with conc. nitric acid in the presence of small amount of conc. H2SO4, it undergoes electrophilic substitution to form mnitrobenzoic acid

2) When benzoic acid is treated with bromine in the presence of FeBr3, mBromobenzoic acid is obtained.

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.Solved Problems.

Problem 1 Alkyl halides are converted into nitriles by the action of aqueous or aqueous-alcoholic KCN. The reaction follows SN2 mechanism and works best with primary and secondary alkyl halides. Aryl halides are extremely less reactive towards nucleophilic substitutions. Identify the correct procedure for the following conversions.

(i) 3-Nitrochlorobenzene into 3-Nitrobenzoic acid. (ii) 2-Chlorobutane into 2-Methylbutanoic acid. (iii) tert-butyl bromide into 2, 2-Dimethylpropanoic acid. (iv) 2-Chloroethanol into 3-Hydroxypropanoic acid.

Solution : (i) 3-Nitrochlorobenzene into 3-Nitrobenzoic acid.

(ii) 2-Chlorobutane into 2-Methylbutanoic acid. (iii) tert-butyl bromide into 2,2-Dimethyl propanoic acid.

(iv) 2-Chloro ethanol into 3-Hydroxy propanoic acid.

Problem 2 How will you convert Bromo ethane into (i) ethanoic acid (ii) propanoic acid ? Solution : (i) Bromo ethane to ethanoic acid. (ii) Bromo ethane to propanoic acid.

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Problem 3 Arrange the following acids in their increasing order of acidic strength. (i) Acetic acid, chloroacetic acid, propionic acid, formic acid. (ii) Bromoacetic acid, chloroacetic acid, fluoroacetic acid, iodoacetic acid. (iii) Acetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid. (iv) n-butyric acid, 3-chlorobutyric acid, 2-chlorobutyric acid, 3-chlorobutyric acid. (v) Acetic acid, benzoic acid, p-methoxy benzoic acid, p-nitrobenzoic acid. (vi) Acetic acid, phenyl acetic acid, p-nitro phenyl acetic acid. (vii) Benzoic acid, p-toluic acid, p-chlorobenzoic acid.

Solution : (i) Propionic acid < acetic acid < formic acid < chloroacetic acid (ii) Iodoacetic acid < bromoacetic acid < chloroacetic acid < fluoroacetic acid. (iii) Acetic acid < chloroacetic acid < dichloroacetic acid < trichloroacetic acid. (iv) n-Butyric acid < 3-chlorobutyric acid < 2-chlorobutyric acid < 1-chlorobutyric acid (v) Acetic acid < benzoic acid < p-methoxy benzoic acid < p-nitrobenzoic acid. (vi) Acetic acid < phenyl acetic acid < p-nitro phenyl acetic acid. (vii) p-toluic acid < benzoic acid < p-chlorobenzoic acid. Problem 4 Plan a route for the conversion of benzyl chloride into phenylethanoic acid.

Solution :

Problem 5 A nitrile on acid hydrolysis gives compound A, which reacts with thionyl chloride to give

compound B. Benzene reacts with compound B in presence of anhydrous AlCl3 to give compound C. Identify the compound A, B and C and write the equations.

Solution:

3

Acetic acidA CH COOH

3

Acetyl chlorideB CH COCl

6 5 3

AcetophenoneC C H COCH

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3F C COOH d)

COOH

COCl

Problem 6 Identify ‘A’ and ‘B’ in the following reaction : [Oct.-2014, 2M] 5

2

PClDry ether6 5 2 H /H O

C H MgBr CO 'A ' 'B'

Solution :

MgBr

2

Dry ether

H /H O

COOH5

3

PClPOCl ,HCl

COCl

MgBrOH

+ O = C = O

'A' 'B'Benzoic acid Benzoyl chloride

Phenyl magnesium bromide

Solid carbon dioxide

A = Benzoic acid B = Benzoyl chloride Problem 7 Which acid of each pair shown here would you expect to be stronger? a) CH3COOH or CH2FCOOH b) CH2FCOOH or CH2ClCOOH c) CH2FCH2CH2COOH or CH3CHFCH2COOH

3 3F C COOH or H C COOH d)

Solution : a) CH2FCOOH b) CH2FCOOH

c) CH3CHFCH2COOH

Among the pairs a), b) and d) more acidic strength may be attributed to the presence of Fatom with strongI effect. In the pair of c) more acidic strength due to relative position of Fatom in the two acids.

Problem 8 Carboxylic acids do not give the characteristic reactions of carbonyl group.

Solution : Due to the presence of lone pairs of electrons on the oxygen atom of the OH group,

the carboxylic acids are stabilized by resonance.

As a result, the double bond character of the C = O bond in carboxylic acids is greatly reduced as compared to that in aldehydes and ketones. In other words, the carbonyl group in carboxylic acids is not a true carbonyl group as in aldehydes and ketones and hence does not give some of the characteristic reactions of the carbonyl group.

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For example, unlike aldehydes and ketones, carboxylic acids do not form oximes, hydrazones, semicarbazones atc.

Problem 9 Arrange the following compounds in increasing order of their property as indicated :

a) CH3CH2CH(Br)COOH,CH3CH(Br)CH2COOH,(CH3)2CHCOOH,CH3CH2CH2COOH (acid strength)

b) Benzoic acid, 4Nitrobenzoic acid, 3, 4Dinitrobenzoic acid, 4Methoxybenzoic acid (acid strength)

Solution : a) The acidic strength depends upon (i) nature of + I effect (ii) nature of atom/group

attached (iii) position of substituent on the chain. Hence, (CH3)2 CHCOOH < CH3CH2CH2COOH < CH3CH(Br)CH2COOH < CH3CH2CH(Br)COOH

b) 4Methoxy benzoic acid < Benzoic acid < 4Nitrobenzoic acid < 3, 4Dinitrobenzoic acid

Problem 10 Write the structures of carbonyl compounds that produce following crossed aldol

condensation products. Solution :

CH3

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Problem 11 Draw and complete the following reaction scheme which starts with acetaldehyde. In each empty box, write the structural formula of the organic compound that would be formed.

Solution :

Problem 12 Identify ‘A’ and ‘B’ in the following reaction: [March 2020, 2M]

3AlCl Zn Hg3 2HCl Conc.HClCH COCl A B H O

Solution :

3AlCl3 HClCH C Cl

OC - CH3

Zn HgConc.HCl

O

(Acetophenone)(A)

CH2 - CH3

2H O

Ethylbenzene(B)

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1. Write the structure and IUPAC name of the products formed in following conversions.

i) 4

3

(1) AlkalineKMnO /(2)H O

CH3

NO2

3OCH

ii) 2 2 7 2 4K Cr O /dil.H SO2 2 2 2HO CH CH CH CH Cl

iii) 2H O

3C O O C CH

O O

2. Predict the products in following reactions.

ii) 3 2 2CH CH CH CH CH COOH

4

3

1.LiAIH ,ether

2.H O

iii) 2H /Ni2 2CH CH CH COOH iv) 2

3

1.Br ,P3 2 2 2. aq.NHCH CH CH COOH

3. Which is the stronger acid in each of the following pairs? a) CH3COOH and CH2=CHCOOH b) C6H5COOH and C6H5CH2COOH

3 2 3CH CH COOHand CH CH COOH

OH

c)

d) CH3CH2COOH and NCCH2COOH e) (CH3)2CHCH2COOH and (CH3)2 N

+HCH2COOH f) O2NCH2COOH and ClCH2COOH

4. Write the structure of the ester formed in each of the following reactions.

a) CH3CH2CH2CH2OH+CH3CH2COOH 2 4conc.H SO /

2 4conc.H SO /32CH OH HOOC COOH b)

2 4conc.H SO /2 2 2 2 5CH CH CH COOH C H OH c)

i)

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5. Indicate by equations, what happens when a mixture of acetaldehyde and acetone are treated with alkali.

*6. Write reaction showing aldol condensation of cyclohexanone.

*7. What is the action of hydrazine on cyclopentanone in presence of KOH in ethylene glycol ?

8. Arrange the following carboxylic acids in order of increasing acidity. mNitro benzoic acid, trichloroacetic acid, benzoic acid, chlorobutyric acid.

9. Arrange the following acids in order of their decreasing acidity. i) ii) CCl3 CH2 COOH iiiI CH3COOH .Homework Problems.

1. How is propanoic acid obtained from phenyl propanoate?

2. How will you convert acetic acid to i) Ethyl acetate ii) Acetyl chloride iii) Acetic anhydride [Oct.-2009, 1M] iv) Acetamide [Oct.-2009, 1M]

3. What happens when i) Acetic acid is treated with ammonia and the product is heated. ii) Methyl magnesium iodide is treated with solid CO2 in dry ether and the product is hydrolysed with dilute HCl ? [Feb.-2007, 2M]

4. How will you bring about following conversions ? [Oct.-2008, 4M] i) Acetic acid to acetyl chloride ii) Methyl cyanide to acetic acid iii) Acetyl chloride to ethyl acetate iv) Ethyl iodide to ethyl acetate

5. If a mixture of formaldehyde and acetaldehyde is subjected to aldol condensation, predict the products formed and draw their structures.

6. Write the chemical equations for aldol condensation or Cannizzaro reaction that following compounds undergo :

i) Propanal ii) 2-Methyl propanal iii) Pentanal iv) 3-Methylbutanal v) Acetophenone vi) p-Methoxybenzaldehyde vii) 2-Methyl cyclohexanone viii) Chloral ix) Cyclopentanone x) Phenyl acetaldehyde xi) 1-Phenyl propan-1-one.

7. How is carbonyl group converted into:

(i) 2CH OH (ii) \CHOH/ (iii) 2CH (iv) |C OH|

[Oct.-2009, 4M]

8. Fill in the blanks and rewrite the balanced equations.

i) CH3COOH + thionyl chloride ________ + ________ + ________

ii) CH3 CH2 COOH + ________ ________ + H3PO3

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iii) C6H5 COOH + ________ _______ + phosphorous oxylchloride + HCl

iv) CH3 COOH + phosphorous trichloride ________ + ________

v) CH3 COOH 3NH ________ ________

vi) ________ 3NH ________ C6H5 CONH2

Classwork Problems

1. i)

ii) 2 2 24 Chloro butanal

OHC CH CH CH Cl

iii)

2. i)

ii) 3 2 2 2CH CH CH CH CH CH OH

iii) 3 2 2CH CH CH COOH iv)

3. a) CH2 = CHCOOH is the stronger acid than CH3COOH b) C6H5COOH is the stronger acid than C6H5CH2COOH

3 3 2CH CH COOHis the stonger acid than CH CH COOH

OH

c)

d) NCCH2COOH is the stronger acid than CH3CH2COOH

e) (CH3)2NHCH2COOH is the stronger acid than (CH3)2CHCH2COOH

f) NO2CH2COOH is the stronger acid than ClCH2COOH 4. a) CH3CH2COOCH2CH2CH2CH3

3 3H COOC COOCHb)

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3 2 3CH C CH COCH

OH

H

3 2CH C CH CHO

CH3

OH

2 2 2 2 5CH CH CH COOC H c)

5. (i) Self aldol condensation of acetaldehyde, CH3CHOHCH2CHO (ii) Self aldol condensation of acetone, 3 2 3

3

CH COH CH COCH|CH

(iii) Cross aldol condensation,

(iv) Cross aldol condensation

6.

8. Benzoic acid < mnitrobenzoic acid < chlorobutyric acid < trichloroacetic acid.

9. ii) > i) > iiiI

Homework Problems

1. When phenyl propanoate is heated with dil. NaOH, sodium salt is obtained, which on hydrolysis gives propanoic acid.

2. i) 2 4Con.H SO3 2 5 3 2 5 2CH COOH C H OH CH COOC H H O

ii) CH3COOH + PCl5 CH3COCl + POCl3 + HCl

7.

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dry ether dil.HCl3 H

O C O CH MgI O C OMgI O C OH Mg(I)OH

CH3 CH3

3 2CH C CH C O

H

OH H

2H C CH C O

H

OH H

3-Hydroxybutanal 3-Hydroxypropanal

iii) 2CH3COOH 2 5P O (CH3CO)2O + H2O

iv) 3 3 3 4 3 2 2CH COOH NH CH COONH CH CONH H O

3. i) 3 3 3 4 3 2 2CH COOH NH CH COONH CH CONH H O

ii)

4. i) CH3COOH + SOCl2 CH3COCl + SO2 + HCl

ii) 3 2 3 4CH C N 2H O HCl CH COOH NH Cl

iii) CH3COCl + C2H5OH CH3COOC2H5 + HCl

iv) CH3COOAg + C2H5I CH3COOC2H5 + AgI

5. 6. i) Aldol condensation

ii) Cannizzaro reaction

iii) Aldol condensation

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iv) Aldol condensation

v) Aldol condensation

vi) Cannizzaro reaction

vii) Aldol condensation

viii) Cannizzaros reaction

3 3 3 2

Trichloroacetaldehyde Sodium 2,2,1 Trichloroethanoltrichloroacetate

2CCl CHO NaOH CCl COONa CCl CH OH

ix) Aldol condensation

x) Aldol condensation

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xi) Aldol condensation

7. i) By Reduction of aldehyde (using Ni or LiAlH4 or NaBH4) or by allowing reaction between formaldehyde with R-Mg-X.

ii) By reduction of kerone or by allowing reaction between aldehyde (except formaldehyde) with R-Mg-X

iii) By wolfkichner or clemmenssen reaction

iv) By allowing reaction between Ketone with RMgX

8. i) 3 2 3 2Thionyl chlorideAcetic acid Acetyl chloride

CH COOH SOCl CH COCl HCl SO

ii) 3CH3CH2COOH + PCl3 3CH3CH2COCl + H3PO3

iii) 6 5 5 6 5 3

Phosphorous oxychlorideC H COOH PCl C H COCl POCl HCl

iv) 3 3 3 3 3

Acetic acid Phosphorous Acetyl chloridetrichloride

3CH COOH PCl 3CH COCl H PO

v) vi)

dil. NaOH

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General methods of preparation of Aldehydes:

General methods of preparation of Ketones:

AT A GLANCE

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Preparation of Aromatic aldehydes and Ketones:

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Preparation of Carboxylic acids:

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The general reactions of Aldehydes and Ketones:

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Reactions of Carboxylic acids:

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H

O

MODULE 5

Select the correct answer from each of the following questions : i) Each question is allocated 1 mark for each correct response. ii) No marks will be deducted for incorrect response of each question or if no answer is given. iii) There is only one correct answer for each question.


1. A dilute solution of prosaniline hydrochloride in water, whose pink colour has been discharged by passing sulphur dioxide, does not restore its colour by

(A) HCHO (B) CH3CHO (C) (CH3)COCH3 (D) CCl3CHO 2. The IUPAC name of (CH3)2 C(OH)CH2COCH3 is (A) 4Hydroxy4methylpentan2one (B) 2Hydroxy2methylpentan4one (C) Diacetone alcohol (D) 4Hydroxy4methyl2oxopentane 3. The reagent with which both acetaldehyde and acetone reacts easily is (A) Fehling’s solution (B) Tollens reagent (C) Grignard reagent (D) Schiff’s reagent

4. Isopropyl methyl ketone when treated with ZnHg and concentrated hydrochloric acid give

(A) Isobutane (B) isoPentane (C) nPentane (D) Neopentane

5. The formation of acetone cyanohydrin from acetone is an example of (A) Nucleophilic addition (B) Nucleophilic substitution (C) Electrophilic addition (D) Electrophilic substitution 6. Which of the following is Fehling solution ‘A’? (A) CuSO4 solution (B) CaSO4 solution (C) NaOH solution (D) Sodium potassium tartarate solution 7. Acetone is prepared by oxidation of (A) Acetic acid (B) Methyl alcohol (C) Propan1ol (D) Propan2ol 8. An aldehyde group can be present (A) in between carbon chain

(B) at any position in carbon atom (C) only at the end of carbon chain

(D) at the second carbon atom of the carbon chain 9. IUPAC name of the following compound is

(A) 2(2propenyl) Butanal (B) 2(1 propenyl) Butanal (C) 4Formyl4ethylbut2ene (D) 2Ethylpent3en1al

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Cl

Cl

CH3

O

X

O

OH

O

O O OH

OH

10. What is IUPAC name of compound when ketone group is attached to one isopropyl group and one t butyl group ?

(A) 2, 4, 4Trimethyl3pentanone (B) 2, 2, 4Trimethyl3pentanone (C) 2, 4Dimethyl3pentanone (D) 2, 2Dimethyl3pentanone 11. Benzaldehyde is obtained from Rosenmund’s reduction of

(A) (B)

(C) (D) 12. Product formed when but 1 yne is reacted with dil. H2SO4 and HgSO4 (A) (B) (C) (D) 13. Oxidising agent in Etard oxidation is (A) K2Cr2O7 + dil.H2SO4 (B) KOH + KMnO4 (C) dil. HNO3 (D) CrO2Cl2 in CS2 14. Acetone on treatment with CH3MgI on further hydrolysis gives, (A) (CH3)2CHCH2OH (B) (CH3)3COH (C) CH3CH(OH)CH2CH3 (D) CH3CH2CH(OH)CH2CH3 15. Which of the following is not correctly matched ?

(A) Clemmenson's2reduction

C O CH (B) Wolff Kishnerreduction

C O CH OH

(C) Rosenmund'sreduction

COCl CHO (D) Stephen'sreduction

C N CHO

16. Clemmensen’s reduction is carried out with (A) H2 / Pd

(B) NH2NH2, followed by treatment with glycolic KOH (C) LiAlH4 in ether (D) Zn (Hg) / HCl 17. Ketones can be prepared by : (A) Rosenmund’s reduction (B) Stephen’s reduction (C) Both (A) and (B) (D) None of the above 18. Which of the following aldehyde will respond to Cannizzaro’s reaction when treated

with strong alkali solution? (A) Benzaldehye (B) Acetaldehyde

(C) Propionaldehyde (D) All of these

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3 2CH MgI H O

3 Dry etherH C C O A X

CH3

19. Ethane can be obtained from ethanal in one step by : (A) NaHg + water

(B) ZnHg + conc. HCl (C) Aluminium isopropoxide and isopropyl alcohol (D) LiAlH4 + ether

20. Identify X ; (A) CH3OH (B) CH3CH2OH (C) CH3CHOHCH3 (D) CH3C(OH)(CH3)2 21. Which is obtained by the oxidation of propionaldehyde ? (A) Acetic acid (B) Formic acid and acetic acid (C) Propanoic acid (D) nPropyl alcohol 22. Compound A is reacted with KCN and followed by reduction using SnCl2 + HCl and

successive hydrolysis gives propanal. The compound A is (A) C2H5X (B) C2H5OH

(C) CH3CH2CH2X (D) C2H5CN

23. p nitro toluene convert p nitro benzaldehyde by using (A) KOH + KMnO4 (B) CrO3 in (CH3CO)2O (C) SnCl2 + HCl (D) Pd BaSO4 + quinoline 24. The formation of cyanohydrin from a ketone is an example of : (A) Electrophilic addition (B) Nucleophilic addition (C) Nucleophilic substitution (D) Electrophilic substitution 25. An organic compound ‘X’ having molecular formula C5H10O yields phenyl hydrazone

and gives negative response to the Iodoform test and Tollens test. It produces n-pentane on reduction. ‘X’ could be :

(A) n-Amyl alcohol (B) Pentanal (C) 2-Pentanone (D) 3-Pentanone

26. The common name of carboxylic fatty acids is derived from (A) the name of parent alkanes

(B) the name of corresponding aldehydes (C) from their original sources

(D) the name of alkyl group present in them

27. The IUPAC name of methylpropionic acid is (A) Propanoic acid (B) Butanoic acid (C) 2Methylpropanoic acid (D) 2Methylbutanoic acid 28. Propionic acid can be prepared by the (A) action of propyl magnesium chloride on dry ice (B) alkaline hydrolysis of propyl cyanide (C) acid hydrolysis of ethyl cyanide (D) oxidation of Propanone

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29. The intermediate compound formed during hydrolysis of acetonitrile to acetic acid is (A) Acetone (B) Acetamide (C) Ammonium acetate (D) Ethyl ammonium chloride

30. The acid that cannot be prepared by the action of Grignard reagent on dry ice is (A) Methanoic acid (B) Ethanoic acid (C) Propanoic acid (D) Butanoic acid

31. A carboxylic acid resembles an alcohol with respect to its reaction with (A) acidified K2Cr2O7 (B) washing soda (C) caustic soda (D) sodium metal

32. Acetic acid can be converted into acetic anhydride on heating with (A) POCl3 (B) PCl3 (C) PCl5 (D) P2O5

33. Acetyl chloride reacts with ammonia to give (A) Ammonium acetate (B) Ethylammonium chloride (C) Ethylamine (D) Acetamide

34. The reagent that reacts with acetic acid to give sodium acetate with liberation of carbon dioxide gas is

(A) sodium metal (B) caustic soda (C) caustic potash (D) baking soda

35. Ethyl acetate cannot be prepared by the reaction of ethyl alcohol with (A) Acetic acid (B) Acetyl chloride (C) Acetic anhydride (D) Silver acetate

36. Both the compounds ‘A’ and ‘B’ react with sodium metal to liberate hydrogen gas and react with each other to give Methylethanoate. The compounds ‘A’ and ‘B’ are

(A) C2H5COOH and CH3OH (B) C2H5COOH and C2H5OH (C) CH3COOH and C2H5OH (D) CH3COOH and CH3OH

37. Orange flavour of fruits is due to (A) Octyl acetate (B) Methyl butyrate (C) Isoamyl acetate (D) Isoamyl valerate

38. Compounds ‘A’ and ‘B’ are the isomers of each other. ‘A’ gives effervescence due to a colourless gas on treatment with washing soda, while ‘B’ reacts with Grignard reagent to give an aldehyde. The compounds ‘A’ and ‘B’ are respectively

(A) nButyric acid and ethyl acetate (B) Isobutyric acid and methyl propionate (C) Propionic acid and methyl formate (D) Acetic acid and methyl formate

39. The compound which on acid hydrolysis followed by oxidation gives acetic acid is (A) CH3I (B) CH2Cl2 (C) ClCH2CH2Cl (D) CH3CHCl2

40. Identify the product ‘D’ in the following series of reactions.

2 5 2 5P O C H OHdil.NaOH dil.HCl3 3CH C N 'A ' 'B' 'C' 'D' CH COOH

(A) CH3COOCH3 (B) CH3COOC2H5 (C) C2H5COOCH3 (D) C2H5COOC2H5

41. Lemon is sour due to : (A) Citric acid (B) Tartaric acid (C) Oxalic acid (D) Acetic acid

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C2H5

CH3

CHCOOH

42. Which of the following acids is present in vinegar? (A) Hydrochloric acid (B) Acetic acid (C) Tartaric acid (D) Citric acid 43. Monocarboxylic acids (saturated) are regarded as ________ oxidation products of

paraffins. (A) first (B) second (C) third (D) fourth 44. Monocarboxylic acids show functional isomerism with : (A) esters (B) alcohols (C) ethers (D) aldehydes 45. Acetic acid is obtained when : (A) Methyl alcohol is oxidised with KMnO4 (B) calcium acetate is distilled in presence of calcium formate (C) acetaldehyde is oxidised with K2Cr2O7 and H2SO4 (D) glycerol is heated with H2SO4 46. Which of the following is isobutyric acid? (A) CH3CH2CH2COOH (B) (CH3)2CHCOOH (C) CH3CH2CH2CH2COOH (D) 47. Formic acid is not a representative member of the carboxylic acids because : (A) It is the first member of the series

(B) It does not contain an alkyl group (C) It is a gas (D) It contains an aldehydic group while the other acids do not have the aldehydic

group 48. The IUPAC name of caproic acid is: (A) Pentanoic acid (B) Hexanoic acid (C) Heptanoic acid (D) Octanoic acid 49. The reaction of CH3MgBr on dry ice followed by acid hydrolysis gives : (A) acetic acid (B) formic acid (C) acetone (D) acetaldehyde 50. The acidic character of fatty acids ________ with an increase in molecular mass. (A) sometimes increases sometimes decreases (B) decreases (C) increases (D) none of these 51. Some carboxylic acids and their IUPAC names are given below. Which of the

following is not correctly matched? (A) Formic acid Methanoic acid (B) Acetic acid Ethanoic acid (C) Isobutyric acid 2Methyl butanoic acid (D) nButyric acid Butanoic acid

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CH3 CHCOOH

OH

CH2 CH2COOH

OH

52. Formic acid and formaldehyde can be distinguished by treating with: (A) Benedict’s solution (B) Tollens’ reagent (C) Fehling’s solution (D) NaHCO3

53. 2Cl Alc.KOH3 2 Red P

CH CH COOH A B

The compound (B) is : (A) (B)

(C) H2C = CHCOOH (D) ClCH2CH2COOH 54. Benzaldehyde when treated with alkaline KMnO4 yields (A) Benzyl alcohol (B) Benzoic acid (C) CO2 and H2O (D) Salicylic acid 55. Acetonitrile on acidic hydrolysis gives. (A) HCOOH (B) CH3NC (C) CH3COONa (D) CH3COOH

56. The organic compounds A and B reacts with sodium metal and liberates hydrogen

gas. A and B reacts together to give ethyl acetate. The A and B are (A) CH3COOH and C2H5OH (B) HCOOH and C2H5OH (C) CH3COOH and HCOOH (D) CH3COOH and CH3OH

57. The compound used as synthetic lemonade is (A) Tartaric acid (B) Benzoic acid (C) Acetic acid (D) Citric acid 58. The strongest acid is

COOH

NO2

COOH

NO2

COOH

NO2

COOH

CH3

(A) (B) (C) (D)

59. The enolic form of ethyl acetoacetate as below has :

(A) 9 sigma bonds and 1 pi - bond (B) 18 sigma bonds and 2 pi - bonds (C) 16 sigma bonds and 1 pi-bond (D) 9 sigma bonds and 2 pi - bonds *60. In the following resonating structures A and B, the number of unshared electrons in

valence shell present on oxygen respectively are

(A) 2, 4 (B) 2, 6 (C) 4, 6 (D) 6, 4

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2CH CH CHOCH3

CH3

*61. In the Wolf-Kishner reduction, alkyl aryl ketones are reduced to alkyl benzenes. During this change, ketones are first converted into

(A) acids (B) alcohols (C) hydrazones (D) alkenes *62. Aldol condensation is (A) electrophilic substitution reaction (B) nucleophilic substitution reaction (C) elimination reaction (D) addition-elimination reaction *63. Which one of the following has lowest acidity ?

(A) (B)

(C) (D) *64. Diborane reduces (A) ester group (B) nitro group (C) halo group (D) acid group *65. Benzaldehyde does not show positive test with (A) Schiff reagent (B) Tollen’s reagent

(C) Sodium bisulphite solution (D) Fehling solution 66. In the reaction, 54 PClLiAlH Alc.KOH

3CH COOH A B C, the product C is : [JEE Main 2014]

(A) Ethylene (B) Acetyl chloride (C) Acetaldehyde (D) Acetylene

67. In the following sequence of reactions: 4 2 2

4

KMnO SOCl H /PdBaSOToluene A B C, the

product C is : [JEE Main 2015] (A) C6H5COOH (B) C6H5CH3 (C) C6H5CH2OH (D) C6H5CHO 68. Which of the following pairs of compounds are positional isomers? [JEE Main 2015]

(A) 3 2 2 2CH CH CH CH CHO and ||

3 2 2 3

OCH CH CH C CH

(B) 3 2 2 3||CH CH CH C CH

O

and 3 2|CH CH CH CHO

CH3

(C) 3 2 2 3||CH CH CH C CH

O

and 3 2 2 3||CH CH C CH CH

O

(D) 3 2 2 3||CH CH C CH CH

O

and

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69. The increasing order of the acidity of the following carboxylic acids is : [JEE Main 2018]

I. II. III. IV. (A) I < III < II < IV (B) IV < II < III < I (C) II < IV < III < I (D) III < II < IV < I 70. The correct match between item I (starting material) and Item II (reagent) for the

preparation of benzaldehyde is: [JEE Main 2020]

Item I Item II (I) Benzene (P) HCl and SnCl2, H3O

+

(II) Benzonitrile (Q) H2, PdBaSO4, S and quinolone (III) Benzoyl chloride (R) CO, HCl and AlCl3

(A) (I) (R) (II) (P) (III) (Q) (B) (I) (P) (II) (Q) (III) (R) (C) (I) (Q) (II) (R) (III) (P) (D) (I) (R) (II) (Q) (III) (P) 71. Mesityl oxide is a common name of [JEE Main 2021] (A) 3Methyl cyclohexane carbaldehyde (B) 4Methylpent 3 en 2 one (C) 2, 4 Dimethylpentan 3 one (D) 2Methyl cyclohexanone 72. 4Alkaline MnO

H"X"

[JEE Main 2021] Considering the above chemical reaction, identify the product “X”.

(A) (B) (C) (D)

O

CHO

CH3 O

CH2OH

CH3 O

COOH

CH3 OH

CH3

NO2

CO2H CO2H

OH

CO2H

Cl

CO2H

CH3

OCH3

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3 2CH CH CH CH

OH O

3 2CH CCH COOH

O

3 2CH CCH CH

O O

3 2CH CHCH CH

OH O

C6H5 CH2 C CH2 CH2 CH2 CH3

O

CORR

H OR

.MCQs from Board Examination.

1. Compound having general formula is called : [March-2013] (A) Diester (B) Acid anhydride (C) Hemiacetal (D) Acetal

2. IUPAC name of [Oct.2013]

(A) 1Phenylhexane2one (B) 6Phenylhexan5one (C) 1Benzylhexan5one (D) Dodecan5one

3. Formalin is 40% aqueous solution of : [March-2014] (A) Methanol (B) Methanoic acid (C) Methanol (D) Methanomine

4. Identify the strongest acid amongst the followings : [March-2015] (A) Chloroacetic acid (B) Acetic acid (C) Trichloroacetic acid (D) Dichloroacetic acid

5. On acid hydrolysis, propane nitrile gives [Feb.-2016] (A) propanal (B) acetic acid (C) propionamide (D) propanoic acid

6. Which of the following is the first oxidation product of secondary alcohol ? [March-2017] (A) Alkene (B) Aldehyde (C) Ketone (D) Carboxylic acid

7. A compound used as pistachio flavor in ice cream is ________. [Feb.-2019] (A) vanillin (B) acetophenone (C) muscone (D) butyraldehyde .Homework Problems.

1. The compound that can be formed by aldol condensation of acetaldehyde : (A) (B) (C) (D) 2. 2 pentanone and 3 pentanone can be distinguished by (A) Cannizzaro’s reaction (B) Aldol condensation (C) Iodoform reaction (D) Clemmensen’s reduction 3. Aldol condensation does not occur between (A) two different aldehydes (B) two different ketones (C) an aldehyde and a ketone (D) an aldehyde and an ester 4. The carbon atom of the carbonyl group is : (A) sp hybridized (B) sp2 hybridized (C) sp3 hybridized (D) dsp2 hybridized

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C

R

R'

O

5. Which of the following compounds is oxidised to prepare ethyl methyl ketone ? (A) Propan 2 ol (B) butan 1 ol

(C) Butan 2 ol (D) Tert. Butyl alcohol

6. When but 2 yne is treated with dil. H2SO4 / HgSO4 , the product formed is : (A) Butan 1 ol (B) Butan 2 ol (C) Acetone (D) Butanone 7. The reagent with which both acetaldehyde and acetone react easily is : (A) Fehling’s solution (B) Grignard reagent (C) Schiff’s reagent (D) Tollen’s reagent 8. Which statement is incorrect in the case of acetaldehyde and acetone ? (A) Both react with hydroxylamine (B) Both react with NaHSO3 (C) Both react with hydrazine (D) Both reduce ammoniacal silver nitrate 9. In the following sequence of reactions, the end product is :

2

32 4

2

CH MgXHg /H SO [O][H O]

HC CH (A) (B) (C)º

(A) Acetaldehyde (B) Isopropyl alcohol (C) Acetone (D) Ethyl alcohol

10. Which of the following is an example of aldol condensation ? (A) NaOH(dil.)

3 3 22CH CHO CH CHOHCH CHO

(B) NaOH(dil.)3HCHO CH OH

(C) NaOH(dil.)6 5 6 5 2C H CHO HCHO C H CH OH

(D) NaOH(conc.)6 5 6 5 2C H CHO C H CH OH

11. Ethyl methyl ketone on treatment with a solution of sodium hypochlorite gives chloroform and : (A) Sodium methanoate (B) Sodium ethanoate (C) Sodium propanoate (D) Sodium ethoxide 12. In the group, , the carbonyl carbon is joined to other atoms by : (A) two sigma and one pi bond (B) three sigma and one pi bond (C) two sigma and two pi bonds (D) three sigma and two pi bonds 13. Dialkyl cadmium reacts with a compound to form a ketone. The compound is : (A) an acid (B) an acid chloride

(C) an ester (D) carbon monoxide 14. Aldol condensation between which of the following compounds followed by dehydration gives mesityl oxide ? (A) Two molecules of CH3COCH3 (B) Two molecules of CH3CHO (C) CH3CHO and HCHO (D) CH3CHO and CH3COCH3

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COR

OR

3 3CH C CH

O

15. Compounds of general formula, are called: (A) Diesters (B) Acid anhydrides (C) Hemiacetals (D) Acetals 16. Which of the following compounds give a ketone with Grignard reagent? (A) HCHO (B) CH3CH2OH (C) CH3CN (D) CH3I 17. Acetone, formaldehyde and acetaldehyde can be distinguished when treated with: (A) H2NNH2 (B) NH3 (C) NH2OH (D) C6H5NHNH2

18. A mixture of benzaldehyde and formaldehyde on heating with aqueous NaOH gives: (A) benzyl alcohol and sodium formate

(B) sodium benzoate and methyl alcohol (C) sodium benzoate and sodium formate

(D) benzyl alcohol and methyl alcohol

19. In the reaction,

2

(i) X3 3 3 3(ii) H O/ZnCH C C CH CH C C CH

O O X is : (A) HNO3 (B) O2 (C) O3 (D) KMnO4

20. Which one of the following on treatment with 50% aqueous sodium hydroxide yields the corresponding alcohol and acid ?

(A) CH3CH2CH2CHO (B) (C) C6H5CH2CHO (D) C6H5CHO

21. Aldehyde with NH2NH2 forms : (A) aniline (B) hydrazones (C) nitrobenzene (D) none of these

22. Base catalyzed aldol condensation occurs with (A) propanal (B) butanal (C) ethanal (D) all of these

23. Match the following

The correct matching is : 1 2 3 4 1 2 3 4 (A) (iv) (v) (i) (ii) (B) (v) (i) (ii) (iii) (C) (v) (iii) (ii) (i) (D) (iv) (ii) (iii) (i)

List I (Reaction) List II (Name of reactions)

1. 6 5 6 5 6 5 2C H CHO NaOH C H COOH C H CH OH (i) Rosenmund reduction

2. 3Anhyd.AlCl6 6 3 6 5 3C H CH Cl C H CH (ii) Kolbe’s reaction

3. 4Pd/BaSO2ROCl H RCHO (iii) Claisen reaction

4. 1.heat, 2.H6 5 2C H OH NaOH CO

(iv) Cannizzaro reaction

(v) Friedal Craft’s reaction Vidyala

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CH3 CH2 CH CN

OH

CH3 CH

OH

CN

CH3

CH3

CH3

C CHO

24. Which of the following compounds is obtained when acetone is reacted with HCN? (A) (CH3)2C(OH)NC (B)

(C) (D) (CH3)2C(OH)CN 25. does not show aldol condensation because : (A) carbon is bonded by 3heavy methyl groups (B) due to the absence of hydrogen (C) it is a neutral molecule (D) due to hindrance created by methyl group for carbanion 26. Which of the following statements is not correct? (A) Aldehydes and ketones contain polar carbonyl group (B) Aldehydes and ketones undergo nucleophilic addition (C) Aldehydes and ketones undergo electrophilic substitution (D) Lower members of aldehydes and ketones are soluble in water due to hydrogen bonding 27. Reaction of Grignard reagent with ______ gives acid. (A) carbon dioxide (B) formaldehyde (C) acetaldehyde (D) acetone 28. Which one of the following undergoes reaction with 50% sodium hydroxide solution to give the corresponding alcohol and acid ? (A) phenol (B) benzaldehyde (C) butanal (D) benzoic acid 29. Which of the following gives ketone on oxidation ? (A) CH3CH2CH2OH (B) CH3CHOHCH3

(C) (CH3)2CHCH2OH (D) (CH3)3COH 30. Which of the following is not correctly matched ? (A) Clemmenson's

2reductionC O CH (B) Wolff Kishner

reductionC O CH OH

(C) Rosenmund'sreduction

COCl CHO (D) Stephen'sreduction

C N CHO 31. Which compound does not give cannizzaro’s reaction ? (A) trichloro acetaldehyde (B) benzaldehyde (C) formaldehyde (D) acetaldehyde 32. Which of the following products is formed when benzaldehyde is treated CH3MgBr

and the addition product so obtained is subjected to acid hydrolysis? (A) a primary alcohol (B) phenol

(C) secondary alcohol (D) tert butyl alcohol

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C = O

33. The compound which react with hydroxyl amine but does not react with Tollen’s reagent is (A) CH3CHO (B) HCHO (C) C2H5OH (D) CH3COCH3

34. A compound does not react with 2, 4dinitrophenyl hydrazine compound is : (A) acetone (B) acetaldehyde (C) CH3OH (D) CH3CH2COCH3

35. Acetone reacts with Grignard reagent to form : (A) 3° alcohol (B) 2° alcohol (C) ether (D) no reaction

36. Acetone reacts with iodine to form iodoform in the presence of : (A) CaCO3 (B) MgCO3 (C) KOH alc. (D) NaOH

37. In a reaction RCHO is reduced to RCH3 using amalgamated zinc acid concentrated HCl and warming the solution. The reaction is known as : (A) MeerweinPonndorf reaction (B) Clemmensen’s reaction (C) WolffKishner reduction (D) Schiff’s reaction 38. Which factor/s will increase the reactivity of group?

(i) Presence of a group with positive inductive effect (ii) Presence of a group with negative inductive effect (iii) Presence of large alkyl group (A) only (i) (B) only (ii) (C) (i) and (ii) (D) (ii) and (iii)

39. Oxalic acid on treatment with conc. H2SO4 gives : (A) CO only (B) CO2 only (C) CO2 + H2O (D) H2O + CO + CO2

40. Acetic acid does not form acetyl chloride with : (A) PCl5 (B) PCl3 (C) SOCl2 (D) Cl2

41. The product (C) in the following reaction is :

3 2 5NH P OHeatHeat

RCOOH A B C

(A) RNH2 (B) RCN (C) RNC (D) RCONH2

42. The compound insoluble in acetic acid is : (A) Calcium oxide (B) Calcium carbonate (C) Calcium oxalate (D) Calcium hydroxide

43. Which of the following cannot reduce Fehling’s solution? (A) Formic acid (B) Acetic acid (C) Formaldehyde (D) Acetaldehyde

44. The carboxylic acid which reduces Tollens’ reagent is : (A) CH3CH2CH2COOH (B) CH3CH2COOH (C) CH3COOH (D) HCOOH

45. What is the main reason for fact that carboxylic acids can undergo ionisation? (A) Absence of alphahydrogen

(B) Resonance stabilization of the carboxylate ion (C) High reactivity of alphahydrogen (D) Hydrogen bonding

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3 2CH C O PCl

O

3CH C O Cl

O

3CH C Cl

O

2Cl CH C

O

46. Between CH3COOH and HCOOH, the HCOOH will be : (A) less acidic (B) equally acidic (C) more acidic (D) nonacidic 47. Adipic acid is a : (A) Dibasic acid (B) Tribasic acid (C) Monobasic acid (D) Tetrabasic acid 48. Hydrated oxalic acid contains : (A) two water molecules (B) three water molecules (C) four water molecules (D) five water molecules 49. Which of the following compound does not react with NaOH? (A) CH3COOH (B) CH3CONH2 (C) C6H5OH (D) CH3CH2OH 50. Identify A and B in the following reaction :

B A3 3 3 3 2CH CH CH COOH CH CH OH

A B (A) HI + Red P LiAlH4 (B) Ni / LiAlH4 (C) Pd BaSO4 Zn + HCl (D) LiAlH4 HI + Red P 51. Two mole of acetic acid are heated with P2O5. The product formed is : (A) 2 mole of ethyl alcohol (B) Formic anhydride (C) Acetic anhydride (D) 2 mole of methyl cyanide 52. The product obtained when acetic acid is treated with phosphorus trichloride is :

(A) (B)

(C) (D)

53. Which on oxidation will not give a carboxylic acid with the same number of carbon

atoms ? (A) CH3COCH3 (B) CCl3CH2CHO (C) CH3CH2CH2OH (D) CH3CH2CHO 54. Which of the following is least acidic ? (A) C2H5OH (B) CH3COOH (C) C6H5OH (D) ClCH2COOH 55. When propanoic acid is treated with aqueous NaHCO3, CO2 is liberated. The carbon of carbon dioxide comes from : (A) methyl group (B) carboxylic group

(C) methylene group (D) bicarbonate

56. The name of the compound having the structure ClCH2CH2COOH is (A) 3 chloropropanoic acid (B) 2 chloropropanoic acid (C) 2 chloroethanoic acid (D) chlorosuccinic acid

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57. Which one is called ethanoic acid? (A) HCOOH (B) CH3COOH (C) CH3CH2COOH (D) CH3CH2CH2COOH 58. Which of the following contains acetic acid ? (A) Vinegar (B) Molasses (C) Coal tar (D) Butter

59. The reaction 2

3

CO6 5 H O

C H MgBr gives

(A) 6 5C H OH (B) 6 5C H COOH (C) 6 5C H CHO (D) 6 5 6 5C H COC H

60. When CH2 = CH COOH is reduced with LiAIH4, the compound obtained will be (A) CH3 CH2 CH2OH (B) CH3 CH2 CHO (C) CH3 CH2 COOH (D) CH2 = CH CH2OH 61. On mixing ethyl acetate with aqueous sodium chloride, the composition of the

resultant solution is (A) CH3Cl + C2H5COONa (B) CH3COONa + C2H5OH (C) CH3COCl + C2H5OH + NaOH (D) CH3COOC2H5 + NaCl 62. Choose the weakest acid among the following : (A) F3CCOOH (B) FCH2COOH

(C) (CH3)2CHCOOH (D) CH3COOH 63. Which of the following is most effective for the hydrolysis of an ester? (A) Dilute alkali (B) Dilute acid (C) Water (D) Acid or alkali

64. The reaction of C6H5CH=CHCHO with LiAlH4 gives (A) C6H5CH2CH2CH2OH (B) C6H5CH2CH2CHO (C) C6H5CH=CHCH2OH (D) C6H5CH2CHOHCH3

65. Which of the following carbonyl compounds undergoes aldol condensation? (A) Benzaldehyde (B) Benzophenone (C) Acetophenone (D) tertButyl phenyl ketone

66. Which of the following carbonyl compounds undergoes self redox reaction in presence of concentrated base?

(A) 3Methylpentanal (B) 2Chlorobutanal (C) 2, 2Dimethylpropanal (D) tertButyl methyl ketone 67. Which of the following will not give yellow precipitate when treated with NaOH and I2? (A) 3Methylbutan2one (B) 2Methylpentan3one (C) Propanone (D) Hexan2one

68. A hydroxyl carbonyl compound is obtained by the action of NaOH on (A) HCHO (B) C6H5CHO (C) CR3CHO (D) CH3CHO

69. Para aldehyde is obtained by polymerization of (A) HCHO (B) CH3CHO (C) CH3OH (D) CH3CH2CHO

70. Schiff’s reagent gives pink color with (A) Acetone (B) Acetic acid (C) Acetaldehyde (D) Methylacetate

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71. Metaldehyde is a (A) tetramer of acetaldehyde (B) dimer of acetone (C) trimer of acetaldehyde (D) trimer of formaldehyde 72. A mixture of sodium benzoate and sodalime on heating yields (A) Methane (B) Benzene (C) Sodium benzoate (D) Calcium benzoate 73. Which is the strongest acid? (A) CH3COOH (B) CH3CH2COOH (C) (CH3)3CCOOH (D) ClCH2COOH

Classwork Problems

1. (C) 2. (A) 3. (C) 4. (B) 5. (A) 6. (A) 7. (D) 8 (C) 9. (D) 10. (B) 11. (B) 12. (B) 13. (D) 14. (B) 15. (B) 16. (D) 17. (D) 18. (A) 19. (B) 20. (D) 21. (C) 22. (A) 23. (B) 24. (B) 25. (D) 26. (C) 27. (C) 28. (C) 29. (B) 30. (A) 31. (D) 32. (D) 33. (D) 34. (D) 35. (D) 36. (D) 37. (A) 38. (D) 39. (D) 40. (B) 41. (A) 42. (B) 43. (C) 44. (A) 45. (C) 46. (B) 47. (D) 48. (B) 49. (A) 50. (B) 51. (C) 52. (D) 53. (C) 54. (A) 55. (D) 56. (A) 57. (D) 58. (B) 59. (B) 60. (C) 61. (C) 62. (D) 63. (C) 64. (D) 65. (D) 66. (A) 67. (D) 68. (C) 69. (D) 70. (A) 71. (B) 72. (C)

MCQs from Board Examination

1. (D) 2. (A) 3. (A) 4. (C) 5. (D) 6. (C) 7. (B) Homework Problems

1. (C) 2. (C) 3. (D) 4. (B) 5. (C) 6. (D) 7. (B) 8. (D) 9. (C) 10. (A) 11. (C) 12. (B) 13. (B) 14. (A) 15. (D) 16. (C) 17. (B) 18. (A) 19. (C) 20. (D) 21. (B)

22. (D) 23. (A) 24. (D) 25. (B) 26. (C) 27. (A) 28. (B) 29. (B) 30. (B) 31. (D) 32. (C) 33. (D) 34. (C) 35. (A) 36. (D) 37. (B) 38. (B) 39. (D) 40. (D) 41. (B) 42. (C) 43. (B) 44. (D) 45. (B) 46. (C) 47. (A) 48. (A) 49. (D) 50. (D) 51. (C) 52. (C) 53. (A) 54. (A) 55. (D) 56. (A) 57. (B) 58. (A) 59. (B) 60. (D) 61. (D) 62. (C) 63. (A) 64. (C) 65. (C) 66. (C) 67. (B) 68. (D) 69. (B) 70. (C) 71. (A) 72. (B) 73. (D)

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.Previous Year Examination Questions. MHT-CET 2004 1. Which of the acids cannot be prepared by Grignard reagent? (A) Acetic acid (B) Succinic acid (C) Formic acid (D) All of these MHT-CET 2006 2. Compound A (molecular formula C3H8O) is treated with acidified potassium

dichromate to form a product B (molecular formula C3H6O). B forms a shining silver mirror on warming with ammoniacal silver nitrate. B when treated with an aqueous solution of H2NCONHNH2. HCl and sodium acetate gives a product C. Identify the structure of C.

(A) CH3CH2CH = NNHCONH2 (B) (CH3)2C = NNHCONH2 (C) (CH3)2C = NCONHNH2 (D) CH3CH2CH = NCONHNH2 MHT-CET 2007

3. Which does not react with Fehling’s solution? (A) CH3CHO (B) C6H5CHO (C) C6H12O6 (D) HCOOH MHT-CET 2009 4. The IUPAC name of crotonaldehyde is (A) butenaldehyde (B) butanal1 (C) but2en1al (D) prop2en1ol MHT-CET 2011 5. Aldol condensation product acetone on dehydration gives (A) but2enal (B) 2methylpent3en4one (C) 4hydroxy4methylpentan2one (D) 4methylpent3en2one MHT-CET 2013 6. Structure of the compound whose IUPAC name is 3ethyl2hydroxy4mehtylhex3en5ynoic acid is (A) (B) (C) (D)

7. The order of stability of the following tautomeric compound is

2 2 3

OH O| ||

CH C CH C CH 3 2 3

O O|| ||

CH C CH C CH I II

3 3

OH O| ||

CH C CH C CH III

(A) I > II > III (B) III > II > I (C) II > I > III (D) II > III > I

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MHT-CET 2014

8. Write the IUPAC name of following compound.

(A) 2amino4hydroxybenzoic acid (B) 6amino4hydroxybenzoic acid (C) 3amino4carboxyphenol (D) 2carboxy4hydroxyaniline

MHT-CET 2015

9. R C N + 2 (H) 2

3

(i) SnCl / dil HCl(ii) H O

RCHO + NH4Cl this reaction is known as

(A) Etard reaction (B) Stephen reaction (C) Hell-Vohlard-Zelinsky reaction (D) Balz-Schiemann reaction 10. The correct order of reactivity of aldehydes and ketones towards hydrogen cyanide is (A) CH3COCH3 > CH3CHO > HCHO (B) CH3COCH3 > HCHO > CH3CHO (C) CH3CHO > CH3COCH3 > HCHO (D) HCHO > CH3CHO > CH3COCH3 11. A mixture of benzaldehyde and formaldehyde when treated with 50 % NaOH yields (A) Sodium benzoate and sodium formate (B) Sodium formate and benzyl alcohol (C) Sodium benzoate and methyl alcohol (D) Benzyl alcohol and methyl alcohol 12. Which of the following compounds is most acidic in nature? (A) 4-Chlorobutanoic acid (B) 3-Chlorobutanoic acid (C) 2-Chlorobutanoic acid (D) Butanoic acid

MHT-CET 2016 13. Which of the following compounds when treated with dibenzyl cadmium yields benzyl

methyl ketone? (A) Acetone (B) Acetaldehyde (C) Acetic acid (D) Acetyl chloride 14. The reagent used in Wolf-Kishner reduction is (A) Zn – Hg/conc. HCl (B) NH2 – NH2 and KOH in ethylene glycol (C) NaBH4 (D) Na – Hg/H2O 15. What is the reagent used in Etard reaction? (A) Chromyl chloride (B) Ethanoyl chloride

(C) SnCl2 and HCl (D) Cadmium chloride 16. Which of the following carboxylic acids is a tricarboxylic acid? (A) Oxalic acid (B) Citric acid (C) Succinic acid (D) Adipic acid

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MHT-CET 2017 17. The acid which contains both OH and COOH groups is (A) phthalic acid (B) adipic acid (C) glutaric acid (D) salicylic acid 18. Aldehydes or ketones when treated with C6H5NHNH2, the product formed is (A) semicarbazone (B) phenylhydrazone

(C) hydrazone (D) oxime 19. Which of the following compound will give positive iodoform test? (A) Isopropyl alcohol (B) Propionaldehyde

(C) Ethylphenyl ketone (D) Benzyl alcohol MHT-CET 2018 20. Which of the following is a tricarboxylic acid? (A) Citric acid (B) Malonic acid (C) Succinic acid (D) Malic acid 21. Which of the followings is most reactive towards addition reaction of hydrogen

cyanide to form corresponding cyanohydrin? (A) Acetone (B) Formaldehyde (C) Acetaldehyde (D) Diethylketone 22. Which of the following compounds does NOT undergo haloform reaction?

3 3CH CH CH

OH

(A)

3 3CH C CH

O

(B)

2 5 2 5C H CH C H

OH

(C)

3 2 5CH C C H

O

(D)

MHT-CET 2019 23. Which among the following compounds is obtained when ethanenitrile is acid

hydrolysed? (A) Acetic acid (B) Formamide (C) Acetamide (D) Formic acid 24. Which of the following does not give yellow solid on treatment with sodium

hypoiodite? (A) Pentan2one (B) Pentan3one (C) Acetophenone (D) Ethanal 25. The order of reactivity for addition of hydrogen cyanide to carbonyl compounds is (A) propanone > methanal > ethanal (B) ethanal > propanone > methanal (C) methanal > ethanal > propanone (D) methanal > propanone > ethanal 26. Which of the following compounds undergoes aldol condensation reaction? (A) Benzophenone (B) Benzaldehyde

(C) 2,2-Dimethylpropanal (D) Propanone

27. The reducing agent preferred to convert carboxylic acids and esters to primary alcohols is

(A) H2/Ni (B) NaHg/H2O (C) NaBH4 (D) LiAlH4

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28. The correct IUPAC name of Glyceraldehyde is (A) 2, 3 Dihydroxypropanal (B) 2, 3 Dihydroxybutanal (C) 3Hydroxypropanal (D) Hydroxy ethanal

29. In the reaction, C6H5COCH3

[H] XZn Hg / conc.HCl

, X is

(A) benzylalcohol (B) methylbenzene (C) toluene (D) ethylbenzene 30. In salicylaldehyde benzene ring is attached with (A) oneOH group and oneCHO group (B) twoOH groups and twoCHO groups (C) twoOH groups and one CHO group (D) one OH group and twoCHO group

MHT-CET 2020 31. Which of the following carbonyl compounds does NOT undergo aldol condensation? (A) Benzophenone (B) Acetone (C) Acetaldehyde (D) Acetophenone 32. Which of the following is Rosenmund reduction? (A) 2

4

HPd BaSOAr CO Cl Ar CHO HCl

(B) Zn Hg/con.HCl

2 2R CO R [H] R CH R H O

(C)

3H OSnCl4dil HClR C N 2[H] R CH NH HCl R CHO NH Cl

(D) 2 2

2

H N NH KOH/ethylene glycol2 3 2H OR CHO R CH N NH RCH N

33. Which of the following is a solid trimer of formaldehyde? (A) Paraformaldehyde (B) Metaldehyde

(C) Paraldehyde (D) Trioxane 34. Which of the following compounds on heating with potassium permanganate and

dilute sulphuric acid forms adipic acid? (A) Cyclohexene (B) Phenylethene (C) Methylbenzene (D) n-Butylbenzene 35. Which among the following substituent group decreases the acidic strength of

aromatic carboxylic acid? (A) Cl (B) NH2 (C) CN (D) NO2 36. Which of the following is obtained by hydrogenation of benzoyl chloride in presence

of Pd on BaSO4? (A) Benzoic acid (B) Benzene (C) Benzaldehyde (D) Benzyl alcohol 37. Identify the compound A and B in following reaction 2KCN(alc) 2H O

3 4HClCH Cl A B NH Cl (A) A = Methyl cyanide, B = Methanoic acid (B) A = Ethanenitrile, B = Ethanoic acid (C) A = Methylisocyanide, B = Methanoic acid (D) A = Ethanenitrile, B = Methanoic acid

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38. Which among the following compounds is treated with benzonitrile to obtain benzophenone in dry ether and then acid hydrolysis?

(A) C6H5ONa (B) CH3COCH3 (C) C6H5MgBr (D) CH3MgBr 39. Identify the product C in following reaction.

3HNONaOH NaOH3 2 CaO.CH CH COOH A B C

(A) CH3CH2CH3 (B) CH3CH2CH2OH (C) CH2 = CH2 (D) CH3CH2NO2 40. Identify product ‘A’ in the following reaction.

3

i) DIBAI Hii) H O

R C N A

(A) RCONH2 (B) RCOOH (C) RCH2NH2 (D) RCHO 41. What is IUPAC name of mesityl oxide? (A) 1Phenylbutan-2-one (B) 4-Methylpent-3-en-2-one (C) 4-Methylbenzaldehyde (D) 2-Bromohexan-3-one 42. What is IUPAC name of acrolein? (A) 3-methylbut2enal (B) 2methybut-2enal (C) Prop2enal (D) But2enal 43. Identify ‘A’ and ‘B’ respectively in following reaction 2 2Cl H O

hToluene A B (A) Benzyl chloride and benzaldehyde (B) Benzyl chloride and benzoic acid (C) Benzoyl chloride and benzoic acid (D) Benzoyl chloride and benzaldehyde 44. Chromyl chloride converts methyl group to a chromium complex, which on acid

hydrolysis gives corresponding aldehyde. This reaction is called (A) Etard reaction (B) Wolf-Kishner reaction (C) Stephen reaction (D) Rosenmund reaction 45. Which of the following is NOT dicarboxylic acid? (A) Succinic acid (B) Acrylic acid (C) Malonic acid (D) Phthalic acid 46. Identify ‘A’ in the following reaction, A 2

4

H6 5Pd BaSO C H CHO HCl

(A) Benzoic acid (B) Chlorobenzene (C) Benzyl chloride (D) Benzoyl chloride 47. Identify product A in the following reaction. 6 5 2 2C H C NH H O HCl A

||O

(A) 6 5C H C H||O

(B) C6H5NH2

(C) 6 5C H C Cl||O

(D) 6 5C H C OH||O

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48. Identify ‘A’ in the following reaction :

6 5 2 3 2 6 5 22

O||

2A C H CH Cd 2CH C CH C H CdCl

(A) CH3COCl (B) CH3MgCl (C) C6H5COCl (D) C6H5CH2Cl 49. Which among the following compounds has highest boiling point? (A) CH3CH2COCH3 (B) CH3CH2CH2CHO (C) CH3CH2COOH (D) CH3CH2CH2CH2OH 50. Which of the following statements is true for carbonyl group? (A) Carbon atom is sp3 hybridised. (B) CCO bond angle is 90. (C) Carbon atom forms three sigma bonds. (D) The carbonyl bond is weaker as compared to double bond in alkene. 51. What is the type of hybridization of carbon atom in carbonyl group? (A) sp2 (B) sp3 (C) sp (D) sp3d 52. A reaction in which chromyl chloride in presence of CS2 converts methyl group of

toluene to aldehydic group on acid hydrolysis is called (A) Stephen reaction (B) Etard reaction

(C) Rosenmund reduction (D) Gatterman Koch formylation 53. An acylchloride is hydrogenated over catalyst palladium on barium sulphate to form

an aldehyde. This reaction is called as (A) Wolff-Kishner reduction (B) Rosenmund reduction (C) Etard reaction (D) Stephen reaction 54. Propane nitrile on reaction with ethyl magnesium iodide in presence of dry ether

gives complex. This imine complex on acid hydrolysis forms. (A) 3Pentanone (B) Propanone (C) Butanone (D) 2Pentanone 55. Which of the following is a tricarboxylic acid? (A) Caproic acid (B) Valeric acid (C) Citric acid (D) Oxalic acid 56. Which of the following reagents is used for the following conversion?

CH3CH = CHCHO CH3CH = CHCH2OH (A) H3O

+ (B) H2/Ni (C) LiAlH4 (D) Zn-Hg/HCl 57. Identify A in the following reaction

3H Oether3 3 3A CH MgBr complex (CH ) C OH

(A) Acetyl chloride (B) Acetone (C) Propionaldehyde (D) Acetaldehyde 58. Which of the following compounds is obtained when phenol react with bromine

water? (A) 2Bromophenol (B) 3Bromphenol

(C) 2,4,6Tribromphenol (D) 4Bromophenol

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59. Which of the following compound is highly reactive towards HCN? (A) HCHO (B) C6H5CHO (C) CH3COCH3 (D) CH3CHO

60. Which of the following is a Stephen reaction? (A) 2

4

HPd BaSOR COCl R CHO HCl

(B) 2 2

2

H N NH KOH/ethylene glycol2 3 2H OR CH O R CH N NH R CH N

(C) Zn Hg/conc. HCl

2 2R C R 4[H] R CH R H O||O

(D)

32|

H OSnCl4dil.HCl

H

R C N 2[H] R CH NH.HCl R C O NH Cl

61. Identify ‘B’ in the following reaction

(A) Benzaldehyde (B) Aniline (C) Diphenyl (D) Benzophenone

62. Which of the following is Clemmensen reduction?

(A)

32|

H OSnCl4dil HCl

H

C N 2[H] .CH NH.HCl C O NH Cl

(B) 2 2

2

H N NH KOH/ethyleneglycol2 3 2H OCH O R CH N NH CH N

(C) Zn Hg/conc.HCl

2 2CO 4[H] CH H O

(D) 2

4

HPd BaSOCO Cl CHO HCl

63. Identify the product Y in the following series of reactions.

3 2 3 3(CH CO) O/CrO H O273 278K4 Nitrotoluene X Y

(A) Benzaldehyde (B) 4Nitrobenzoic acid (C) Acetophenone (D) 4Nitrobenzaldehyde 64. What is the final product obtained when benzonitrile react with phenyl magnesium

bromide in equimolar proportion? (A) Dicyclohexane (B) Diphenyl magnesium bromide (C) Benzene (D) Benzophenone 65. The reaction in which methyl group on benzene ring is converted to aldehydic group

is called (A) Etard reaction (B) Fridel Craft reaction (C) Rosenmund reaction (D) Gatterman Koch reaction 66. Which of the following catalyst is used in Rosenmund reaction? (A) Pd BaSO4 (B) CS2 (C) Cu2Cl2 (D) V2O5

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67. Which of the following is a Wolf - Kishner reduction? (A)

32 H OSnCl4dilHClC N 2 H CH NH.HCl CHO NH Cl

(B) 2

4

Hpd BaSOCOCl CHO HCl

(C) Zn Hg/conc.HCl

2 2CO 4 H CH H O

(D)

68. Identify B in the following reaction

32 H OSnCl /HCl dil.4R C N A B NH Cl

(A) R C O|H

(B)

R C OH||O

(C) RCH2 NH2 (D)

2

R C O|NH

69. Identify the product B in the following reaction.

2

2

HH3 2 5 H O NiCH COOH C H OH A B

(A) Ethanol (B) Ethanol and propionic acid (C) Ethanol and propanol (D) Ethanol and ethanoic acid

70. Which of the following compounds is obtained when benzene reacts with benzoyl chloride in presence of anhydrous AlCl3?

(A) Acetophenone (B) Benzophenone (C) Benzaldehyde (D) Chlorobenzene 71. Which of the following compounds is obtained when Butan-2-one is treated with

CH3MgI in dry ether and then acid hydrolysed? (A) Butan-1-ol (B) 2-Methylbutan-2-ol (C) Propan-1-ol (D) 2-Methylpropan-2-ol 72. Which of following compounds is obtained when ethanoic anhydride is treated with

water? (A) Ethanoic acid (B) Ethanal (C) Ethanol (D) Ethyl ethanoate 73. Identify the compound obtained by side chain chlorination of toluene and hydrolysed

further. (A) Acetophenone (B) Benzyl alcohol (C) Benzophenone (D) Benzaldehyde 74. Which of the following does NOT give yellow precipitate when reacted with (NaOH +

I2) mixture? (A) Acetaldehyde (B) Benzaldehyde (C) Acetophenone (D) Acetone 75. Which among the following compound on treatment with DIBAL-H yields dodecanal

at 195 K? (A) CH3CH = CH CH2 CN (B) C2H5CN (C) CH3(CH2)10COOCH3 (D) C6 H5CN

76. Which of the following compounds is obtained on ozonolysis of followed by

reduction with Zn dust and water? (A) Butanal (B) Butanone (C) Propanone (D) Propanal

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77. Which of the following is obtained on alkaline hydrolysis of 1, 1-dichlorocyclohexane? (A) Cyclohexane carbaldehyde (B) Benzaldehyde (C) Cyclohexanol (D) Cyclohexanone 78. Which among the following reactions explain the acidic property of carboxylic acid?

(A) R - C - OH + SOCl2 R - C - Cl + SO2 + HCl

(B) R - C- OH + R - OH 2 4conc.H SO R - C – OR + H2O (C) R - C – OH + 2 Na

2 R - C – ONa + H2

(D) 2 R - C - OH 2 5P O

(R – CO)2O + H2O 79. What is the molecular formula of glyceraldehyde? (A) C2H2O4 (B) C4H6O4 (C) C3H6O3 (D) C3H4O2 80. What is IUPAC name of succinic acid ? (A) Ethanedioic acid (B) Propanedioic acid

(C) Butanedioic acid (D) Pentanedioic acid

81. Identify the product B in following reaction dry ice HOH

6 5 dry ether dil.HClC H MgBr A B .

(A) C6H5COCl (B) C6H5COOH (C) C6H5OH (D) C6H5CH3 82. Which among the following compounds does NOT undergo aldol condensation?

(A) Formaldehyde (B) Butyraldehyde (C) Acetaldehyde (D) Propionaldehyde 83. Which among the following aromatic acids is a strongest acid? (A) onitrobenzoic acid (B) mnitrobenzoic acid (C) pnitrobenzoic acid (D) pmethoxybenzoic acid 84. Which of the following functional groups is reduced by diborane? (A) Carboxyl group (B) Halo group (C) Nitro group (D) Ester group 85. Which of the following compounds is not isomeric with diethyl ether? (A) nPropyl methyl ether (B) Butanone (C) Butan1ol (D) 2Methylpropan2ol 86. Identify A in the following reaction.

dry ether HOHDry ice A B Isobutyric acid Mg(Cl)OHH

(A) Isobutyl magnesium chloride (B) Isopropyl magnesium chloride (C) nPropyl magnesium chloride (D) nButyl magnesium chloride 87. Aspirin is an acetylation product of

(A) 2-hydroxy benzoic acid (B) 1,4-dihydroxy benzene (C) 3-hydroxy benzoic acid (D) 1,2-dihydroxy benzene

88. Which of the following carboxylic acids has highest acidic strength? (A) Chloroacetic acid (B) Trichloroacetic acid (C) Dichloroacetic acid (D) Acetic acid

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89. What is the correct order of reactivity of HCN towards aldehydes and ketones? (A) ketones < other aldehydes < formaldehyde (B) formaldehyde < ketones < other aldehydes (C) other aldehydes < formaldehyde < ketones (D) formaldehyde < other aldehydes < ketones 90. Aldehydes and ketones those are not sensitive to acids when heated with zinc

amalgam and concentrated hydrochloric acid give alkane. This reaction is known as (A) Clemmensen reduction (B) Rosenmund reduction (C) Wolf - Kishner reduction (D) Stephen reaction 91. Which of the following compounds yields 3Ethylpentan3ol by using ethyl

magnesium iodide followed by acid hydrolysis? (A) Propanone (B) Pentan2one (C) Butanone (D) Pentan3one 92. Which of the following compounds does NOT undergo Friedel – Crafts reaction? (A) Chlorobenzene (B) Benzoic acid

(C) Benzene (D) Toluene 93. How many carbon atoms are present in a molecule of benzylmethyl ketone? (A) Ten (B) Seven (C) Nine (D) Eight 94. Which of the following has highest boiling point? (A) CH3-CH2-O-CH3 (B) CH3-CH2-CHO

(C) 3 3CH C CH

O

(D) CH3-CH2-CH2-OH

95. Which of following reagents is used to avoid further oxidation of aldehydes? (A) K2Cr2O7 / dil. H2SO4 (B) C5H5NH+CrO3Cl (C) dil. HNO3 (D) CrO3 96. Which among the following compounds is obtained when benzene is treated with CO

and HCl in presence of catalyst anhydrous AlCl3 and Cu2Cl2 under high pressure? (A) Acetophenone (B) Toluene (C) Benzoic acid (D) Benzaldehyde 97. Which among the following substituent groups increases the acidic strength of

aromatic carboxylic acids? (A) OH (B) NH2 (C) NO2 (D) CH3 98. Which among the following compounds has highest boiling point?

(A) Butan2ol (B) Butan2one (C) Propanoic acid (D) 2Methylbut1ene

99. Identify the product A in following reaction : Acetyl chloride + Dibenzylcadmium A (A) Acetophenone (B) Benzyl methyl ketone (C) Benzophenone (D) Benzoic acid

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100. Which reagent from following is used to prepare aldehydes from alkyl cyanides by Stephen reaction?

(A) Cl2/hv, H2O (B) DIBAI H, H3O+

(C) SnCl2/dil. HCl, H3O+ (D) CO, HCl (anhydrous AlCl3)

101. Which of the following aromatic acids has less acidic strength than benzoic acid?

(A) o chlorobenzoic acid (B) o nitrobenzoic acid (C) m nitrobenzoic acid (D) p methoxy benzoic acid

102. Identify the product obtained when 3, 5 dinitrobenzoic acid is heated with thionyl chloride ? (A) 3,5Dinitrobenzoyl chloride (B) 3Chloro 5nitrobenzoic acid (C) 3,5Dichlorobenzyl chloride (D) 3,5Dinitrobenzyl chloride

103. Which of the following compounds is NOT a carbonyl compound? (A) Acetyl chloride (B) Propanamide (C) Acetamide (D) Ethoxy ethane Answer of Previous Year Examination Questions

1. (C) 2. (A) 3. (B) 4. (C) 5. (D) 6. (B) 7. (B) 8. (A) 9. (B) 10. (D) 11. (B) 12. (C) 13. (D) 14. (B) 15. (A) 16. (B) 17. (D) 18. (B) 19. (A) 20. (A) 21. (B) 22. (C) 23. (A) 24. (B) 25. (C) 26. (D) 27. (D) 28. (A) 29. (D) 30. (A) 31. (A) 32. (A) 33. (D) 34. (A) 35. (B) 36. (C) 37. (B) 38. (C) 39. (D) 40. (D) 41. (B) 42. (C) 43. (A) 44. (A) 45. (B) 46. (D) 47. (D) 48. (A) 49. (C) 50. (C) 51. (A) 52. (B) 53. (B) 54. (A) 55. (C) 56. (C) 57. (B) 58. (C) 59. (A) 60. (D) 61. (D) 62. (C) 63. (D) 64. (D) 65. (A) 66. (A) 67. (D) 68. (A) 69. (A) 70. (B) 71. (B) 72. (A) 73. (D) 74. (B) 75. (C) 76. (C) 77. (D) 78. (C) 79. (C) 80. (C) 81. (B) 82. (A) 83. (A) 84. (A) 85. (B) 86. (B) 87. (A) 88. (B) 89. (A) 90. (A) 91. (D) 92. (B) 93. (C) 94. (D) 95. (B) 96. (D) 97. (C) 98. (C) 99. (B) 100.(C) 101.(D) 102. (A) 103. (D)

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Std.XII 2022 : Chemistry Vidyalankar

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