CHEMISTRY TEXTBOOK

alkyl chain , regardless of its length, is oxidized

to a carboxyl group. (Tertiary alkyl substituent

on benzene, however, is not oxidized).

For example,

12.5.5 From alkenes : Carboxylic acids can

also be prepared by the oxidation of alkenes

by KMnO 4 in dilute H 2 SO 4.

H 5 C 6 - CH = CH 2

KMnO 4 .dil.H 2 SO 4

∆ H 5 C 6 - COOH

(Phenyl ethene) (Benzoic acid)

COOH

COOH

(Cyclohexene) (Adipic acid)

KMnO 4 .dil.H 2 SO 4

∆

12.5.6 From Grignard reagent : Grignard

reagent in dry ether solvent is added to solid

carbon dioxide (dry ice) to give a complex

which on acid hydrolysis gives corresponding

carboxylic acid.

R - Mg - X + O = C = O dry ether R - COOMgX

(Alkyl (dry ice) (complex)

magnesium halide)

(carboxylic acid)

(^) dil.HClHOH R - COOH + Mg(X)OH
12.6 Physical properties :
12.6.1 Nature of intermolecular forces :
The carbonyl bond ( C=O) in aldehydes and
ketones is a polar covalent bond. As a result,
these compounds contain dipole-dipole forces
of attraction. (Fig. 12.1) The molecules orient
in such a way as to have oppositely polarized
atoms facing each other.
Use your brain power
Predict the products (name and
structure) in the following reactions.
CH 3 CH 2 CN
∆
dil. HCl?
CH 3 -CONH 2 dil. HCl∆?
C 6 H 5 -CH 2 -CH 3
alk.KMnO 4
∆?
C 6 H 5 -COO-C 2 H 5 dil. H∆ 2 SO 4?
CH 3 MgBr
(i) dry ice/dry ether
(ii) dil. HCl?
Internet my friend
Collect information of dry ice and
ice from internet. Draw chemical
structures of dry ice and regular ice.
Prepare a chart of uses of dry ice.
(^) O
(^) C
δ⊕
δ⊕ δ
δ
C
(^) O
Fig. 12.1 Dipole-dipole attraction in carbonyl
compounds
Carboxyl group of carboxylic acid contains
O-H bond which is responsible for formation
of hydrogen bonding. Thus, carboxylic acids
have the strongest intermolecular forces of
attraction. (Fig.12.3 in section 12.6.4).
C
H
H
H KMnO 4 .KOH
∆
COOK
⊕
COOH
H 3 O⊕
(Toluene)
(Benzoic acid)
(Potassium benzoate)
C
CH 3
H 3 C
H KMnO 4 .KOH
∆
COOK
⊕
COOH
H 3 O⊕
(Cumene)
(Benzoic acid)
(Potassium benzoate)