King Saud University
Chemistry Department
Alcohols and Phenols
145 Chem
1
King Saud University
Chemistry Department
Alcohols and Phenols
- Alcohols and phenols may be viewed as organic derivatives of water.
H-O-H
Water
R-O-H
Alcohol
Ar-O-H
Phenol
- 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 attached to an aromatic ring, Ar.
145 Chem
2
King Saud University
Chemistry Department
Classification and Nomenclature of Alcohols
Alcohols are classified into:
145 Chem
3
King Saud University
Chemistry Department
IUPAC Name:
In the IUPAC system, alcohols are named according to the
following rules:
1. Select the longest continuous carbon chain that contains the -OH
group. Replace the ending e of the alkane by the suffix –ol
2. If a molecule contains both an -OH group and a C=C or C-C
triple bond,
- The name should include both the hydroxyl and the unsaturated
groups.
-The -OH group takes preference before the double or triple
bonds in getting the lower number.
- If a compound contains both OH and a double or triple
bond, choose the chain that include them both even if this is
not the longest chain.
145 Chem
4
King Saud University
Chemistry Department
3. In the IUPAC system
- The suffix diol is added to the name of the parent hydrocarbon
when there are two OH groups.
- The suffix triol is added when there are three OH groups.
Common name
- listing the alkyl substitutents attached to the hydroxyl group,
followed by the word alcohol.
- Two OH groups on adjacent carbons are known as 1,2glycols.
145 Chem
5
King Saud University
Chemistry Department
- Primary alcohol
CH3OH
CH3CH2OH
Common
Methyl alcohol
Ethyl alcohol
IUPAC
Methanol
Ethanol
145 Chem
CH2=CHCH2OH
Allyl alcohol
2-Propen-1-ol
6
King Saud University
Chemistry Department
- Secondary and tertiary alcohol
OH
OH
CH3
OH
Common Isopropyl alcohol
IUPAC
145 Chem
2-Propanol
Cyclopentyl alcohol
Cyclopentanol
Methylcyclohexyl alcohol
1-Methyl-1-cyclohexanol
7
King Saud University
Chemistry Department
OH
OH
Phenol
OH
1-Phenylmethanol
Benzyl alcohol (common name)
2-Phenylethanol
OH
OH
OH
4-Methyl-2-cyclohexen-1-ol
145 Chem
Ethan-1,2-diol
Ethelene glycol (common name)
8
King Saud University
Chemistry Department
Physical Properties of Alcohols
Diols and triols are more soluble in water than monohydroxyalcohols.
As the number of carbons in the alcohol increases, the solubility in
water decreases.
The boiling points increase with increase in molecular weights.
145 Chem
9
King Saud University
Chemistry Department
The presence of the hydrogen bonding between alcohol molecules
as a result of the high b.p. of alcohol.
Alcohols are week acids.
145 Chem
10
King Saud University
Chemistry Department
Homework
H2C
H
C
CH2
OH
OH
IUPAC
Nomenclature
OH
145 Chem
Commen
11
King Saud University
Chemistry Department
Synthesis (Preparation) of Alcohols
1. From alkene
H3O+
OH
+
major
minor
OH
OH
KMnO4
OH-/H2O
OH
cis glycol
2. From – alkyl halid
alcohol,KOH
heat
H3C C CH2
H
CH3CH2CH2Cl
dil OH-
CH3CH2CH2OH
145 Chem
12
King Saud University
Chemistry Department
3. Reduction of aldehyde, ketone and carboxylic acid.
O
H
LiAlH4
H
C
C CH3
3
CH3CCH3 or NaBH
4
OH
or H2/Pt
O
LiAlH4
CH3COH
H2
H3C C OH
4. Addition of Grignard compounds to aldehyde and ketone.
Tertiary alcohol
Secondary alcohol
Primary alcohol
145 Chem
13
King Saud University
Chemistry Department
Reactions of Alcohols
1.
Reaction as acids (Breaking of oxygen- Hydrogen bond CO ‫ـــــ‬H)
A. Salt Formation
CH3CH2OH
Na
H2
H3C C ONa
Sodium ethoxide
B. Ester Formation
2. Reaction with C‫ــــ‬OH bond cleavage
A. Elimination Reactions
CH3CH2OH
conc.H2SO4
H2C CH2
B. Substitution Reaction
CH3CH2OH
HCl
or SOCl2
or PCl3
or PCl5
H3C CH2Cl
14
King Saud University
Chemistry Department
3. Oxidation Reactions
CH3CH2OH
145 Chem
Cu/
or CrO3
O
H3C CH
15
King Saud University
Chemistry Department
Nomenclature and acidity of Phenols
Phenols are generally named as derivatives of the simplest member of the
family, phenol (hydroxyl group attached directly to a benzene ring are called
phenols).
145 Chem
16
King Saud University
Chemistry Department
-
Introduction of electron-withdrawing groups, such as NO2 or CN,
on the ring increases the acidity of phenols.
-
Alcohols and phenols have weak acidic properties.
-
Phenols are much stronger acids than alcohols.
145 Chem
17
King Saud University
Chemistry Department
Synthesis of Phenols
145 Chem
18
King Saud University
Chemistry Department
Reactions of Phenols
145 Chem
19
King Saud University
Chemistry Department
Electrophilic Substitution Reaction
145 Chem
20
King Saud University
Chemistry Department
Home Work
KMnO4
OH-/H2O
MgCl
O
HCH +
O
H3O+
H2C MgBr
H3O+
+
145 Chem
21
King Saud University
Chemistry Department
4) The IUPAC name of
is:
A) 4-Ethyl-5-heptyn-3-ol
B) 4-Ethyl-5-heptan-3-ol
C) 4-Ethyl-5-hepten-3-ol
D) 4-Etyl-2-hepten-5-ol
OH
5) The IUPAC name of
is:
A) 3-Methyl-1-bromocyclohexanol
B) 2-Bromo-3-methylcyclohexanol
C) 4-Bromo-2-methylcyclohexanol
D) 3-Bromo-1-methylcyclohxanol
145 Chem
22
King Saud University
Chemistry Department
6) The common name of 2-methyl-2-propanol is:
A) Allyl alcohol
B) Isopropyl alcohol
C) tert-Butyl alcohol
D) Benzyl alcohol
7) The following reaction gives
A) 4-Ethylphenol
B) 2-Ethylphenol
C) Ethylphenyl ether
D) Ethylphenyl ketone
145 Chem
23