1 Dr Nahed Elsayed. Learning Objectives Chapter six concerns alcohols and phenols and by the end of...
-
Upload
alberta-fowler -
Category
Documents
-
view
224 -
download
0
Transcript of 1 Dr Nahed Elsayed. Learning Objectives Chapter six concerns alcohols and phenols and by the end of...
1
Dr Nahed Elsayed
Learning ObjectivesLearning ObjectivesChapter six concerns alcohols and phenols and by the end of this chapter the student Chapter six concerns alcohols and phenols and by the end of this chapter the student will:will: know the difference in structure between alcohols and phenolsknow the difference in structure between alcohols and phenolsKnow the different classes of alcoholsKnow the different classes of alcohols Know how to name alcohols and phenolsKnow how to name alcohols and phenols Know the physical properties (solubility, boiling and melting points) Know the physical properties (solubility, boiling and melting points) Know how hydrogen bonds are formed and its effect on boiling points of Know how hydrogen bonds are formed and its effect on boiling points of alcoholsalcoholsKnow the acidic properties of alcohols and phenolsKnow the acidic properties of alcohols and phenolsknow the different methods that can be used to prepare alcohols and know the different methods that can be used to prepare alcohols and phenols.phenols. Know the chemical reactions of these compounds ( some reactions are Know the chemical reactions of these compounds ( some reactions are review, others are extensions of the chemistry that will be discussed on review, others are extensions of the chemistry that will be discussed on chapters 8, 9 & 10 chapters 8, 9 & 10
145 Chem.
145 Chem. 3
King Saud University Chemistry Department
Alcohols and phenols may be viewed as organic derivatives of water.
Alcohols and phenols have a common functional group, the hydroxyl group, —OH.
- In alcohols the hydroxyl group is attached to an alkyl group, —R.
- In phenols the hydroxyl function is directly attached to benzene
ring
H-O-H R-O-H or PhCH2OH Ph-O-H Water Alcohol Phenol
Structure Of Alcohols and PhenolsStructure Of Alcohols and Phenols
OHOH
Phenol Benzyl alcohol
OH
Cyclohexanol
Alcohols are classified according to the type of the according to the type of the carbon atom connected to the hydroxyl group (carbinol carbon atom connected to the hydroxyl group (carbinol carbon) carbon) into:
4
King Saud University Chemistry Department
Classification and Nomenclature of Alcohols
145 Chem.
1.1. Select the Select the longest continuous longest continuous carbon chain that carbon chain that contains the -OH groupcontains the -OH group. Replace . Replace the the ending ending ee of the alkane by the suffix of the alkane by the suffix –ol–ol
22. . If a molecule contains both an -OH group and a C=C or cIf a molecule contains both an -OH group and a C=C or cΞΞc bond; c bond; Choose the chain that include both of them even if this is not the longest chain. Choose the chain that include both of them even if this is not the longest chain.
The name should include suffixes indicate presence of both the OH group and the The name should include suffixes indicate presence of both the OH group and the unsaturated groups. unsaturated groups.
The The OH group takes precedence over the double or triple bonds in getting the OH group takes precedence over the double or triple bonds in getting the lower number.lower number.
Cyclic alcohols Cyclic alcohols are named using the prefixare named using the prefix cyclo-, cyclo-, the carbon bearing the hydroxyl the carbon bearing the hydroxyl group is assumed to take group is assumed to take number 1.number 1.
3. 3. The suffix The suffix dioldiol or or trioltriol is added to the name of the parent hydrocarbon when there are is added to the name of the parent hydrocarbon when there are two OH or three OH groups respectively.two OH or three OH groups respectively.
145 Chem. 5
King Saud University Chemistry Department
NOMENCLATURE OF ALCOHOLSNOMENCLATURE OF ALCOHOLSIUPAC Nomenclature Of Alcohols IUPAC Nomenclature Of Alcohols
Alcohols are named according to the following rules:
6
Common Nomenclature Of AlcoholsCommon Nomenclature Of Alcohols
List the names of alkyl substituents attached to the hydroxyl group, followed by the word alcohol.
If two OH groups present on two adjacent carbons these known as glycols
King Saud University Chemistry Department
Primary alcoholsPrimary alcohols
CH3OH CH3CH2OH CH2=CHCH2OH
Common
Methyl alcohol Ethyl alcohol Allyl alcohol
IUPAC Methanol Ethanol 2-Propen-1-ol
145 Chem.
7
Secondary and tertiary alcoholsSecondary and tertiary alcohols
Common
Isopropyl alcohol
Cyclopentyl alcohol
Methylcyclohexyl alcohol
IUPAC 2-Propanol Cyclopentanol1-Methyl-1-cyclohexanol
CH3
OH
OHOH
King Saud University Chemistry Department
145 Chem.
8
OH
OHOH
OH
OH4-Methyl-2-cyclohexen-1-ol
1-PhenylmethanolBenzyl alcohol (common
name)
2-Phenylethanol
Ethan-1,2-diolEthylene glycol (common name)
King Saud University Chemistry Department
ExamplesExamples
(CH3)2C=CHCH(OH)CH3
12345
4- Methyl-3-penten-2-ol
145 Chem.
ExamplesExamples
CH3
OH
OH
Propylene glycol
OHHO
Ethylene glycol
Ethane-1,2-diol Propane-1,2-diolor 1,2-Propanediol
OH
OH
OH
Propane-1,2,3-triolor 1,2,3,-Propantriol
IUPAC
Common Glycerol or Glycerin
King Saud University Chemistry Department
145 Chem.
OH OH
But-3-en-2-ol
OH
Pent-4-yn-1-ol 5-Ethyl-hex-5-en-3-olOH
Cl
4-Chloro-2-methyl-1-penten-3-ol
10
Alcohol and water contain Alcohol and water contain hydroxyl group hydroxyl group that can form that can form hydrogen bonds.hydrogen bonds.The hydroxyl group isThe hydroxyl group is hydrophilic “water loving” hydrophilic “water loving”The alkyl group of alcohols isThe alkyl group of alcohols is hydrophobic “ water hating” hydrophobic “ water hating”As the number of the –OH group in alcoholAs the number of the –OH group in alcohol increases, the solubility increases, the solubility in water in water increases.increases.The lower The lower alcohols are alcohols are completely miscible completely miscible with waterwith water
Diols and triols are Diols and triols are moremore soluble in water than monohydroxyalcohols. soluble in water than monohydroxyalcohols.
As the number of carbons in the alcohol increases, As the number of carbons in the alcohol increases, the solubility in water decreases.the solubility in water decreases.
King Saud University Chemistry Department
Physical Properties of AlcoholsPhysical Properties of Alcohols1) Solubility Of Alcohols and 1) Solubility Of Alcohols and
PhenolsPhenols
145 Chem. 11
King Saud University Chemistry Department
Physical Properties of AlcoholsPhysical Properties of Alcohols2) Boiling Points of Alcohols2) Boiling Points of Alcohols
The boiling points increase with increase in molecular weights.The boiling points increase with increase in molecular weights.
Alcohols have higher boiling points(b .p.) than alkanes of similar weight Alcohols have higher boiling points(b .p.) than alkanes of similar weight this is due to the presence of this is due to the presence of hydrogen bondshydrogen bonds between molecules of between molecules of alcohols.alcohols.
hydrogen bond
OH
OH
OH> >
OHOH
OH> > > Br >Melting & boiling points
Increases in this direction
12
King Saud University Chemistry Department
3)3)Acidic Properties of AlcoholsAcidic Properties of Alcohols Alcohols are Alcohols are very weak acidsvery weak acidsThe hydroxyl proton of an alcohol is weakly acidicThe hydroxyl proton of an alcohol is weakly acidicA strong base can abstract the hydroxyl proton to give an alkoxide ionA strong base can abstract the hydroxyl proton to give an alkoxide ion
Electron-withdrawing group (-I) Electron-withdrawing group (-I) increase acidityincrease acidityElectron-releasing group (+I)Electron-releasing group (+I) decrease acidity decrease acidity
145 Chem.
R-O-H B+ B-H
CH3CH2OH CH3OH ClCH2CH2OH
PKa= 15.9 15.5 15.3less acidic most acidic
R-O
Cl
Cl
Cl
OH
Cl
OH OH
H3CO
OH> >>
145 Chem. 13
H3O+ OH+
OHmajor minor
KMnO4
OH-/H2O
OH
OHcis glycol
alcohol,KOH
CH3CH2CH2Cl
heat
dil OH-
CH3CH2CH2OH
H3C CH
CH2
King Saud University Chemistry Department
Synthesis (Preparation) of Synthesis (Preparation) of AlcoholsAlcohols1- From Alkenes (Hydration and oxidation of alkenes)1- From Alkenes (Hydration and oxidation of alkenes)
2- From alkyl halide by nucleophilic substitution2- From alkyl halide by nucleophilic substitution (N.B. elimination of HX using base gives alkene(N.B. elimination of HX using base gives alkene
i) i) Hydration of alkenesHydration of alkenes
ii) ii) Oxidation of alkenesOxidation of alkenes
145 Chem. 14
LiAlH4CH3CCH3 or NaBH4
or H2/Pt
H3CHC CH3
O
OH
CH3 MgBrCH3CH H3C
HC CH3
O
OMgBr
H3O+
H3CHC CH3
OH
LiAlH4CH3COH H3C
H2C OH
O
King Saud University Chemistry Department
3- Reduction of aldehydes, ketones and carboxylic 3- Reduction of aldehydes, ketones and carboxylic acidsacids
145 Chem. 15
CH3CCH3
O
OMgBr
H3O++
MgCl C CH3H3C
OH
C CH3H3C
King Saud University Chemistry Department
4- Addition of Grignard compounds to aldehydes 4- Addition of Grignard compounds to aldehydes & ketones& ketones
Tertiary alcohol
Ketone
CH3 MgBrCH3CH H3C
HC CH3
O
OMgBr
H3O+
H3CHC CH3
OH
CH3 MgBrH
HC CH3
OMgBr
H3O+
HHC CH3
OHH H
O
Secondary alcohol
Primary alcohol
Methanalformaldehyde
A. Formation of Salt
145 Chem.16
1. Dissociation of O-H Bond
NaCH3CH2OH H3C
H2C ONa
Sodium ethoxide
King Saud University Chemistry Department
Reaction of AlcoholsReaction of Alcohols
B. Formation of Esters
R OH
O
+ R- OHR OR
OH+
H+/ H2O
A. Elimination Reactions
145 Chem.17
conc.H2SO4CH3CH2OH H2C CH2
King Saud University Chemistry Department
B. Substitution Reaction
2. Dissociation of C-O Bond i.e. cleavage of CــــOH bond
HCl/ ZnCl2CH3CH2OH H3C CH2Clor SOCl2or PCl3or PCl5
145 Chem18
King Saud University Chemistry Department
C. Oxidation Reactions
CH3CH2OH H3C C-OH
OKMnO4
PCC =N
, CrO3. HCl Pridinium Chloro chromate
Cu /CH3CH2OH H3C CH
or PCC
O
Cu /CH3CHCH3 H3C C-CH3
or KMnO4
OOH
or PCC
145 Chem. 19
Phenols (compounds having hydroxyl group directly attached to a benzene ring ) are generally named as derivatives of the simplest member of the family, phenol
Acidity :
Alcohols and phenols have weak acidic properties.
Phenols are much stronger acids than alcohols.
Introduction of electron-withdrawing groups, such as NO2 or
CN, on the ring increases the acidity of phenols.
Nomenclature and acidity of Phenols
King Saud University Chemistry Department
20
OH OH OH OH OH
CH3 NO2
NO2
NO2NO2
NO2O2N
< < < <
2,4,6-TrinitrophenolPicric acid
Cresol Phenol p-Nitrophenol 2,4,-DinitrophenolpH > 10 pH= 10 pH= 7 pH=4
pH= 0.25
King Saud University Chemistry Department
OH
CHO
OH
COOH
OH
Cl NH22-Hydroxy-benzaldehydeo-Hydroxybenzaldehyde
Salicylaldehyde2-Hydroxy-benzoic acido-Hydroxybenzoic acid
Salicylic acid
3-Amino-5-chloro-phenol
145 Chem. 21
Synthesis of PhenolsSynthesis of Phenols
King Saud University Chemistry Department
145 Chem. 22
Reactions PhenolsReactions Phenols
King Saud University Chemistry Department
Ethers formationEthers formation
CrO3 / H+
O
O
p-Benzoquinone
145 Chem. 23
King Saud University Chemistry Department
2. Electrophilic Substitution Reactions
145 Chem. 24
Home Work
KMnO4
OH-/H2O
HCH
OH3O+
+
MgCl
MgBr
H3O+
+
O H2C
King Saud University Chemistry Department
4) The IUPAC name of is:
A) 4-Ethyl-5-heptyn-3-ol B) 4-Ethyl-5-heptan-3-olC) 4-Ethyl-5-hepten-3-olD) 4-Etyl-2-hepten-5-ol
OH
5) The IUPAC name of is:
A) 3-Methyl-1-bromocyclohexanolB) 2-Bromo-3-methylcyclohexanolC) 4-Bromo-2-methylcyclohexanolD) 3-Bromo-1-methylcyclohxanol
HO
H3C Br
145 Chem. 25
King Saud University Chemistry Department
OH OH
OCH3 NO2
OH
A) B) C) D)CH3CH2OH
6) The most acidic compound is
7) The common name of 2-methyl-2-propanol is:A) Allyl alcoholB) Isopropyl alcoholC) tert-Butyl alcoholD) Benzyl alcohol
8) The following reaction gives
A) 4-EthylphenolB) 2-EthylphenolC) Ethylphenyl etherD) Ethylphenyl ketone
NaOHOH
1)
CH3-CH2-Br2)
145 Chem. 26
King Saud University Chemistry Department
27
CH3
OH
Conc. H2SO4
a) b) c) d)
KMnO4/OH-
OH
HOH
OH
OH
H
H
H
OH
OH
H
H
OH
H
a) b) c) d)
10) The product of the reaction shown below is
O
H
O OH OCH3A) B) C) D)
11) Which of the following compounds has the highest boiling point?
9) The major product for the following reaction is
Questions?