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NCERT Solutions for Class 12 Chemistry Part 1 Chapter 13
Amines Class 12
Chapter 13 Amines Exercise Solutions
In text : Solutions of Questions on Page Number : 384
Q1 :
(i) Write structures of different isomeric amines corresponding to the molecular formula,
CH N
4 11
(ii) Write IUPAC names of all the isomers.
(iii) What type of isomerism is exhibited by different pairs of amines?
Answer :
(i), (ii) The structures and their IUPAC names of different isomeric amines corresponding to the
molecular formula, C H N are given below:
4 11
(a) CH -CH -CH -CH -NH
3 2 2 2 2
Butanamine (1 ) 0
(b)
Butan-2-amine (1 ) 0
(c)
2-Methylpropanamine (1 ) 0
(d)
2-Methylpropan-2-amine (1 ) 0
(e) CH -CH -CH -NH-CH
3 2 2 3
N-Methylpropanamine (2 ) 0
(f) CH -CH -NH-CH -CH
3 2 2 3
N-Ethylethanamine (2 ) 0
(g)
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N-Methylpropan-2-amine (2 ) 0
(h)
N,N-Dimethylethanamine (3°)
(iii) The pairs (a) and (b) and (e) and (g) exhibit position isomerism.
The pairs (a) and (c); (a) and (d); (b) and (c); (b) and (d) exhibit chain isomerism.
The pairs (e) and (f) and (f) and (g) exhibit metamerism.
All primary amines exhibit functional isomerism with secondary and tertiary amines and vice-
versa.
Q2 :
Classify the following amines as primary, secondary or tertiary:
(i)
(ii)
(iii) (C H ) CHNH
2 5 2 2
(iv) (C H ) NH
2 5 2
Answer :
Primary: (i) and (iii)
Secondary: (iv)
Tertiary: (ii)
Q3 :
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(i) Benzene into aniline
(ii) Benzene into N, N-dimethylaniline
(iii) Cl-(CH ) -Cl into hexan-1, 6-diamine?
2 4
Answer :
(i)
(ii)
(iii)
Q4 :
Arrange the following in increasing order of their basic strength:
(i) C H NH , C H NH , NH , C H CH NH and (C H ) NH
2 5 2 6 5 2 3 6 5 2 2 2 5 2
(ii) C H NH , (C H ) NH, (C H ) N, C H NH
2 5 2 2 5 2 2 5 3 6 5 2
(iii) CH NH , (CH ) NH, (CH ) N, C H NH , C H CH NH .
3 2 3 2 3 3 6 5 2 6 5 2 2
Answer :
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(i) Considering the inductive effect of alkyl groups, NH , C H NH and (C H ) NH can be 3 2 5 2, 2 5 2
arranged in the increasing order of their basic strengths as:
Again, C H NH has proton acceptability less than NH . Thus, we have:
6 5 2 3
Due to the - I effect of C H group, the electron density on the N-atom in C H CH NH is lower
6 5 6 5 2 2
than that on the N-atom in C H NH but more than that in NH . Therefore, the given compounds
2 5 2, 3
can be arranged in the order of their basic strengths as:
(ii) Considering the inductive effect and the steric hindrance of the alkyl groups, C H NH , 2 5 2
(C H ) NH and their basic strengths as follows:
2 5 2 2,
Again, due to the - R effect of C H group, the electron density on the N atom in C H NH is
6 5 6 5 2
lower than that on the N atom in C H NH . Therefore, the basicity of C H NH is lower than that
2 5 2 6 5 2
of C H NH . Hence, the given compounds can be arranged in the increasing order of their basic
2 5 2
strengths as follows:
(iii) Considering the inductive effect and the steric hindrance of alkyl groups, CH NH , 3 2
(CH ) NH, and (CH ) N can be arranged in the increasing order of their basic strengths as:
3 2 3 3
In C H NH , N is directly attached to the benzene ring. Thus, the lone pair of electrons on the N -
6 5 2
atom is delocalized over the benzene ring. In C H CH NH , N is not directly attached to the 6 5 2 2
benzene ring. Thus, its lone pair is not delocalized over the benzene ring. Therefore, the
electrons on the N atom are more easily available for protonation in C H CH NH than in 6 5 2 2
C H NH i.e., C H CH NH is more basic than C H NH .
6 5 2 6 5 2 2 6 5 2
Again, due to the - I effect of C H group, the electron density on the N - atom in C H CH NH is
6 5 6 5 2 2
lower than that on the N - atom in (CH ) N. Therefore, (CH ) N is more basic than C H CH NH . 3 3 3 3 6 5 2 2
Thus, the given compounds can be arranged in the increasing order of their basic strengths as
follows.
Q5 :
Complete the following acid-base reactions and name the products:
(i) CH CH CH NH + HCl
3 2 2 2
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NCERT Solutions for Class 12 Chemistry Part 1 Chapter 13
Amines Class 12
Chapter 13 Amines Exercise Solutions
In text : Solutions of Questions on Page Number : 384
Q1 :
(i) Write structures of different isomeric amines corresponding to the molecular formula,
CH N
4 11
(ii) Write IUPAC names of all the isomers.
(iii) What type of isomerism is exhibited by different pairs of amines?
Answer :
(i), (ii) The structures and their IUPAC names of different isomeric amines corresponding to the
molecular formula, C H N are given below:
4 11
(a) CH -CH -CH -CH -NH
3 2 2 2 2
Butanamine (1 ) 0
(b)
Butan-2-amine (1 ) 0
(c)
2-Methylpropanamine (1 ) 0
(d)
2-Methylpropan-2-amine (1 ) 0
(e) CH -CH -CH -NH-CH
3 2 2 3
N-Methylpropanamine (2 ) 0
(f) CH -CH -NH-CH -CH
3 2 2 3
N-Ethylethanamine (2 ) 0
(g)
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N-Methylpropan-2-amine (2 ) 0
(h)
N,N-Dimethylethanamine (3°)
(iii) The pairs (a) and (b) and (e) and (g) exhibit position isomerism.
The pairs (a) and (c); (a) and (d); (b) and (c); (b) and (d) exhibit chain isomerism.
The pairs (e) and (f) and (f) and (g) exhibit metamerism.
All primary amines exhibit functional isomerism with secondary and tertiary amines and vice-
versa.
Q2 :
Classify the following amines as primary, secondary or tertiary:
(i)
(ii)
(iii) (C H ) CHNH
2 5 2 2
(iv) (C H ) NH
2 5 2
Answer :
Primary: (i) and (iii)
Secondary: (iv)
Tertiary: (ii)
Q3 :
How will you convert?
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(i) Benzene into aniline
(ii) Benzene into N, N-dimethylaniline
(iii) Cl-(CH ) -Cl into hexan-1, 6-diamine?
2 4
Answer :
(i)
(ii)
(iii)
Q4 :
Arrange the following in increasing order of their basic strength:
(i) C H NH , C H NH , NH , C H CH NH and (C H ) NH
2 5 2 6 5 2 3 6 5 2 2 2 5 2
(ii) C H NH , (C H ) NH, (C H ) N, C H NH
2 5 2 2 5 2 2 5 3 6 5 2
(iii) CH NH , (CH ) NH, (CH ) N, C H NH , C H CH NH .
3 2 3 2 3 3 6 5 2 6 5 2 2
Answer :
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(i) Considering the inductive effect of alkyl groups, NH , C H NH and (C H ) NH can be 3 2 5 2, 2 5 2
arranged in the increasing order of their basic strengths as:
Again, C H NH has proton acceptability less than NH . Thus, we have:
6 5 2 3
Due to the - I effect of C H group, the electron density on the N-atom in C H CH NH is lower
6 5 6 5 2 2
than that on the N-atom in C H NH but more than that in NH . Therefore, the given compounds
2 5 2, 3
can be arranged in the order of their basic strengths as:
(ii) Considering the inductive effect and the steric hindrance of the alkyl groups, C H NH , 2 5 2
(C H ) NH and their basic strengths as follows:
2 5 2 2,
Again, due to the - R effect of C H group, the electron density on the N atom in C H NH is
6 5 6 5 2
lower than that on the N atom in C H NH . Therefore, the basicity of C H NH is lower than that
2 5 2 6 5 2
of C H NH . Hence, the given compounds can be arranged in the increasing order of their basic
2 5 2
strengths as follows:
(iii) Considering the inductive effect and the steric hindrance of alkyl groups, CH NH , 3 2
(CH ) NH, and (CH ) N can be arranged in the increasing order of their basic strengths as:
3 2 3 3
In C H NH , N is directly attached to the benzene ring. Thus, the lone pair of electrons on the N -
6 5 2
atom is delocalized over the benzene ring. In C H CH NH , N is not directly attached to the 6 5 2 2
benzene ring. Thus, its lone pair is not delocalized over the benzene ring. Therefore, the
electrons on the N atom are more easily available for protonation in C H CH NH than in 6 5 2 2
C H NH i.e., C H CH NH is more basic than C H NH .
6 5 2 6 5 2 2 6 5 2
Again, due to the - I effect of C H group, the electron density on the N - atom in C H CH NH is
6 5 6 5 2 2
lower than that on the N - atom in (CH ) N. Therefore, (CH ) N is more basic than C H CH NH . 3 3 3 3 6 5 2 2
Thus, the given compounds can be arranged in the increasing order of their basic strengths as
follows.
Q5 :
Complete the following acid-base reactions and name the products:
(i) CH CH CH NH + HCl
3 2 2 2
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