Amines TEXTBOOK Solution

Question 1.

Classify the following amines as primary, secondary and tertiary :

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 1

Solutions:

(a) Primary
(b) Tertiary
(c) Primary
(d) Secondary

Question 2.

(a) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N.
(b) Write IUPAC names of all the isomers.
(c) What type of isomerism is exhibited by different pairs of amines?

Solutions:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 2
NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 3

Question 3.

How will you convert:

  • (i) Benzene into aniline,
  • (ii) Benzene into N,N-dimethylaniline,
  • (iii) Cl(CH2)4Cl into hexan-1,6-diamine?

Solution:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 4
NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 5

Question 4.

Arrange the following in increasing order of their basic strength.

(a) C2H5NH2, C6H5NH2, NH3, C6H5CH2NH2 and (C2H5)2NH
(b) C2H5NH2, (C2H5)2NH, (C2H5)3N, C6H5NH2
(c) CH3NH2< (CH3)2NH, (CH3)3N, C6H5NH2> C6H5CH2NH2.

Solutions:

(a) The order of basicity is C6H5NH2 < NH3 < C6H5CH2NH2 < C2H5NH2 < (C2H5)2NH
The basic nature of amine arises from their ability to donate the lone pair of electrons on N to electrophiles. The availability of this l.p. depends on two factors :

(i) Electron donating/withdrawing effect of the alkyl groups attached to the N atom.

(ii) Steric hindrance posed by alkyl groups around N.
The presence of alkyl groups on the N atom increases the electron density and makes the l.p. more available for electrophiles. This happens due to the +1 effect of the alkyl groups. But, if the alkyl groups are too bulky or too many in number, they tend to sterically hinder the incoming proton and the basic strength decreases. These two factors working in opposing directions, tend to balance out each other in 2° amines, making them most basic and the basic strength follows the order :

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 6

Question 5.

Complete the following acid-base reactions and name the products :

  1. CH3CH2CH2NH2 + HCl →
  2. (C2H5)3N + HCl →

Solution:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 7

Question 6.

Write the reactions of the final alkylation product of aniline with excess of methyl iodide in the presence of sodium carbonate solution.

Solution:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 8

Question 7.

Write the chemical reaction of aniline with benzoyl chloride and write the name of the product obtained.

Solution:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 9

Question 8.

Write structures of different isomers corresponding to the molecular formula, C3H9N. Write IUPAC name of the isomers which will liberate nitrogen gas on treatment with nitrous acid.

Solution:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 10
NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 11

Question 9.

Convert

  1. 3-Methylaniline into 3-nitrotoluene
  2. Aniline into 1,3,5-tribromobenzene.

Solution:

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 12
NCERT Solutions for Class 12 Chemistry Chapter 13 Amines 13