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NCERT Solutions for Class 12 Chemistry Chapter 13 - Amines

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NCERT Class 12 Chemistry Chapter 13: Complete Resource for Amines

Amine is an organic compound that contains nitrogen. These are the derivatives of ammonia and are obtained when one or more hydrogen atoms from ammonia are replaced by alkyl and aryl functional groups. Vital amines are amino acids, biogenic amines, trimethylamine, and aniline. While studying this chapter, students can refer to the Amines class 12 NCERT Solutions. This will help them to understand the structure, classification, properties of it in an easier way. Besides, they will also get to learn the process of its preparation and other properties in detail.


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Class:

NCERT Solutions for Class 12

Subject:

Class 12 Chemistry

Chapter Name:

Chapter 13 - Amines

Content-Type:

Text, Videos, Images and PDF Format

Academic Year:

2024-25

Medium:

English and Hindi

Available Materials:

  • Chapter Wise

  • Exercise Wise

Other Materials

  • Important Questions

  • Revision Notes



Important Points to Remember

A few of the important points that are associated with the Chapter, Amines can be given as follows:

  • Amines are ammonia derivatives.

  • They're made by substituting an alkyl or aryl group for hydrogen atoms.

  • Amines are divided into three categories based on the number of hydrogen atoms replaced: primary, secondary, and tertiary amines.


Amines Chapter at a Glance - Class 12 NCERT Solutions


Preparation and Properties of Amines


Preparation and Properties of Amines


Reaction of Diazonium Salt


Reaction of Diazonium Salt

Competitive Exams after 12th Science
More Free Study Material for Amines
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Important questions
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Practice and Master the Concepts of Amines with NCERT Solutions Exercises for Class 12 Maths Chapter 13

Intext Questions:

1. Classify the Following Amines as Primary, Secondary and Tertiary:

i.


${{1}^{0}}$


Ans: ${{1}^{0}}$ 


ii.


${{3}^{0}}$


Ans: ${{3}^{0}}$ 


iii. \[{{({{C}_{2}}{{H}_{5}})}_{2}}CHN{{H}_{2}}\] 

Ans: ${{1}^{0}}$


iv. ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$ 

Ans: ${{2}^{0}}$ 


2.i. Write the structures of different isomers corresponding to the molecular formula, ${{C}_{4}}{{H}_{11}}N$ and write IUPAC names of all the isomers.

Ans: The structures and their IUPAC names of different isomeric amines corresponding to the molecular formula ${{C}_{4}}{{H}_{11}}N$ are given below:

a. $C{{H}_{3}}-C{{H}_{2}}-C{{H}_{2}}-C{{H}_{2}}-N{{H}_{2}}$  Butanamine (${{1}^{0}}$)

b.  (Image will be uploaded soon)Butan-2-amine (${{1}^{0}}$)

c. (Image will be uploaded soon) 2-methyl propanamine (${{1}^{0}}$)

d. (Image will be uploaded soon) 2-methylpropan-2-amine (${{1}^{0}}$)

e. $C{{H}_{3}}-C{{H}_{2}}-C{{H}_{2}}-NH-C{{H}_{3}}$ N-ethylethanamine (${{2}^{0}}$)

f. $C{{H}_{3}}-C{{H}_{2}}-NH-C{{H}_{2}}-C{{H}_{3}}$ N- methylpropananmine (${{2}^{0}}$)

g. (Image will be uploaded soon) N-methylpropan-2-amine (${{2}^{0}}$)

h. (Image will be uploaded soon) N,N, Dimethylethanamine (${{3}^{0}}$ )


ii. What type of isomerism is exhibited by different pairs of amines?

Ans: 

Position Isomers:

Butanamine (${{1}^{0}}$) and Butan-2-amine (${{1}^{0}}$);

N-ethylethanamine (${{2}^{0}}$) and N-methylpropan-2-amine (${{2}^{0}}$)

Chain Isomers:

Butanamine (${{1}^{0}}$) and 2-methyl propanamine (${{1}^{0}}$);

Butanamine (${{1}^{0}}$) and 2-methylpropan-2-amine (${{1}^{0}}$);

Butan-2-amine (${{1}^{0}}$) and 2-methyl propanamine (${{1}^{0}}$)

Butan-2-amine (${{1}^{0}}$) and 2-methylpropan-2-amine (${{1}^{0}}$)

Metamers:

N-ethylethanamine (${{2}^{0}}$) and N- methylpropananmine (${{2}^{0}}$)

N- methylpropananmine (${{2}^{0}}$) and N-methylpropan-2-amine (${{2}^{0}}$)

Functional Isomers: All ${{1}^{0}}$ amines are functional isomers of ${{2}^{0}}$ and ${{3}^{0}}$ amines and vice-versa


3. How Will You Convert,

a. Benzene into aniline

Ans:


Benzene into aniline


b. Benzene into N,N- dimethylaniline

Ans:


Benzene into N,N- dimethylaniline


c. $Cl-{{(C{{H}_{2}})}_{4}}-Cl$ into Hexane-1,6-diamine

Ans:


$Cl-{{(C{{H}_{2}})}_{4}}-Cl$ into Hexane-1,6-diamine


4. Arrange the following in increasing order of their basic strength:

i. ${{C}_{2}}{{H}_{5}}N{{H}_{2}},{{C}_{6}}{{H}_{5}}N{{H}_{2}},N{{H}_{3}},{{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}\And {{({{C}_{2}}{{H}_{5}})}_{2}}NH$ 

Ans: Considering the inductive effect of alkyl groups $N{{H}_{3}}$, ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$  and ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$  can be arranged in the increasing order of their basic strengths as:

\[N{{H}_{3}} < {{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{2}}{{H}_{5}})}_{2}}NH\] 

Again, ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$has proton acceptability less than $N{{H}_{3}}$. Thus, we have:

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < N{{H}_{3}} < {{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{2}}{{H}_{5}})}_{2}}NH\] 

Due to the −I effect of ${{C}_{6}}{{H}_{5}}-$  group, the electron density on the N-atom in ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$ is lower than that on the N-atom in${{C}_{2}}{{H}_{5}}N{{H}_{2}}$, but more than that in $N{{H}_{3}}$. Therefore, the given compounds can be arranged in the order of their basic strengths as:

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < N{{H}_{3}} < {{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}} < {{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{2}}{{H}_{5}})}_{2}}NH\] 


ii. ${{C}_{2}}{{H}_{5}}N{{H}_{2}},{{({{C}_{2}}{{H}_{5}})}_{2}}NH,{{({{C}_{2}}{{H}_{5}})}_{3}}N,{{C}_{6}}{{H}_{5}}N{{H}_{2}},$ 

Ans: Considering the inductive effect and the steric hindrance of the alkyl groups, ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$  

${{({{C}_{2}}{{H}_{5}})}_{2}}NH$, and their basic strengths as follows:

\[{{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{2}}{{H}_{5}})}_{3}}N < {{({{C}_{2}}{{H}_{5}})}_{2}}NH\]

Again, due to the −R effect of ${{C}_{6}}{{H}_{5}}-$  group, the electron density on the N atom in ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$  is lower than that on the N atom in ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$ . Therefore, the basicity of ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ is lower than that of ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$. Hence, the given compounds can be arranged in the increasing order of their basic strengths as follows:

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < {{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{2}}{{H}_{5}})}_{3}}N < {{({{C}_{2}}{{H}_{5}})}_{2}}NH\] 


iii. $C{{H}_{3}}N{{H}_{2}},{{(C{{H}_{3}})}_{2}}NH,{{(C{{H}_{3}})}_{3}}N,{{C}_{6}}{{H}_{5}}N{{H}_{2}},{{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$ 

Ans: Considering the inductive effect and the steric hindrance of alkyl groups, $C{{H}_{3}}N{{H}_{2}}$ , ${{(C{{H}_{3}})}_{2}}NH$ , and ${{(C{{H}_{3}})}_{3}}N$  can be arranged in the increasing order of their basic strengths as:

\[{{(C{{H}_{3}})}_{3}}N < {{(C{{H}_{3}})}_{2}}NH < C{{H}_{3}}N{{H}_{2}}\] 

In${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ , N is directly attached to the benzene ring. Thus, the lone pair of electrons on the N−atom is delocalized over the benzene ring. In ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$, N is not directly attached to the 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 ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$ than in ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ i.e., ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$ is more basic than ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$. Again, due to the −I effect of ${{C}_{6}}{{H}_{5}}$  group, the electron density on the N−atom in ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$ is lower than that on the N−atom in ${{(C{{H}_{3}})}_{3}}N$. Therefore, ${{(C{{H}_{3}})}_{3}}N$ is more basic than ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$. Thus, the given compounds can be arranged in the increasing order of their basic strengths as follows.

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < {{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}} < {{(C{{H}_{3}})}_{3}}N<{{(C{{H}_{3}})}_{2}}NH < C{{H}_{3}}N{{H}_{2}}\]


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

i. $C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}}+HCl\to $ 

Ans:


$C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}}+HCl\to $


ii. ${{({{C}_{2}}{{H}_{5}})}_{3}}N+HCl\to $ 

Ans:


${{({{C}_{2}}{{H}_{5}})}_{3}}N+HCl\to $


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

Ans: Aniline reacts with methyl iodide to produce N, N-dimethylaniline.


Aniline reacts with methyl iodide to produce N, N-dimethylaniline


With excess methyl iodide, in the presence of $N{{a}_{2}}C{{O}_{3}}$ solution, N, N-dimethylaniline produces N, N, N−trimethylanilinium carbonate.


N, N, N−trimethylanilinium carbonate


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

Ans:


Chemical reaction of aniline with benzoyl chloride


8. Write structures of different isomers corresponding to the molecular formula, ${{C}_{3}}{{H}_{9}}N$ . Write IUPAC names of the isomers which will liberate ${{N}_{2}}$  gas on treatment with nitrous acid.

Ans: In all, four structural isomers are possible. These are:

only ${{1}^{0}}$  amines react with $HN{{O}_{2}}$ to liberate ${{N}_{2}}$  gas

only ${{1}^{0}}$  amines react with $HN{{O}_{2}}$ to liberate ${{N}_{2}}$  gas

\[\underset{Propan-1-a\min e}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}}}}\,+HN{{O}_{2}}\to \underset{Propan-1-ol}{\mathop{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}OH}}\,+{{N}_{2}}+{{H}_{2}}O\] 


Structures of different isomers


9. Convert:

i. 3-Methylaniline into 3-nitrotoluene

Ans:


3-Methylaniline into 3-nitrotoluene


ii. Aniline into 1, 3, 5- Tribromo benzene

Ans:


Aniline into 1, 3, 5- Tribromo benzene


NCERT Exercises

1. Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines.

a.  ${{(C{{H}_{3}})}_{2}}CHN{{H}_{2}}$ 

Ans: 1-Methylethanamine (${{1}^{0}}$  amine)

b. $C{{H}_{3}}-{{(C{{H}_{2}})}_{2}}N{{H}_{2}}$ 

Ans: Propan-1-amine (${{1}^{0}}$amine)

c. $C{{H}_{3}}NHCH{{(C{{H}_{3}})}_{2}}$ 

Ans: N−Methyl-2-methylethanamine (${{2}^{0}}$  amine)

d. ${{(C{{H}_{3}})}_{3}}CNH$ 

Ans: 2-Methylpropan-2-amine (${{1}^{0}}$ amine)

e. ${{C}_{6}}{{H}_{5}}NHCH$ 

Ans: N−Methylbenzamine or N-methylaniline (${{2}^{0}}$ amine)

f. ${{(C{{H}_{3}}C{{H}_{2}})}_{2}}NC{{H}_{3}}$ 

Ans: N-Ethyl-N-methylethanamine (${{3}^{0}}$  amine)

g. $m-Br{{C}_{6}}{{H}_{4}}N{{H}_{2}}$ 

Ans: 3- bromobenzamine or 3- bromoaniline (${{1}^{0}}$ amine)

 

2. Give one chemical test to distinguish between the following pairs of compounds:

i. Methylamine and dimethylamine

Ans: Methylamine and methylamine can be distinguished by carbylamine test.

\[\underset{{}}{\mathop{C{{H}_{3}}N{{H}_{2}}}}\,+CHC{{l}_{3}}+3KOH\xrightarrow{\Delta }\underset{{}}{\mathop{C{{H}_{3}}NC}}\,+2KCl+3{{H}_{2}}O\]

\[{{(C{{H}_{3}})}_{2}}NH\xrightarrow{CHC{{l}_{3}}/KOH(alc)}\text{No reaction}\]

 

ii. Secondary and Tertiary Amines

Ans: Secondary and tertiary amine can be distinguished by Liebermann’s nitrosamine test. Secondary amines give Liebermann nitroamine tests while tertiary amines do not.

\[{{(C{{H}_{3}}C{{H}_{2}})}_{2}}NH+HO-N=O\xrightarrow{HCl+NaN{{O}_{2}}}\underset{\text{Yellow colour}}{\mathop{{{(C{{H}_{3}}C{{H}_{2}})}_{2}}N-N=O}}\,+{{H}_{2}}O\]

\[{{(C{{H}_{3}}C{{H}_{2}})}_{3}}N+HN{{O}_{2}}\to \underset{\text{Triethylammonium nitrate (soluble)}}{\mathop{[{{(C{{H}_{3}}C{{H}_{{{)}_{3}}}}NH]}^{+}}N{{O}_{2}}^{-}}}\,\] 


iii. Ethylamine and Aniline

Ans: Ethylamine and aniline can be distinguished by azo test:

\[{{C}_{2}}{{H}_{5}}N{{H}_{2}}+HONO+HCl\xrightarrow{273-278K}{{C}_{2}}{{H}_{5}}OH+C{{H}_{2}}=C{{H}_{2}}+C{{H}_{3}}C{{H}_{2}}Cl+{{N}_{2}}\] 


Ethylamine and aniline


iv. Aniline and Benzylamine

Ans: Aniline and benzylamine can be distinguished by nitrous acid test:

\[{{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}\underset{HCl}{\mathop{\xrightarrow{HONO}}}\,[{{C}_{6}}{{H}_{5}}C{{H}_{2}}N_{2}^{+}C{{l}^{-}}]\xrightarrow[Decompose]{{{H}_{2}}O}{{C}_{6}}{{H}_{5}}C{{H}_{2}}OH+{{N}_{2}}\uparrow +HCl\] 


Aniline and Benzylamine


v. Aniline and N-Methylaniline.

Ans: Aniline and N-methylaniline can be distinguished by carbylamine test:

\[\underset{Aniline}{\mathop{{{C}_{6}}{{H}_{5}}N{{H}_{2}}}}\,+CHC{{l}_{3}}+3KOH\xrightarrow{\Delta }\underset{\text{Offensive smell}}{\mathop{{{C}_{6}}{{H}_{5}}NC}}\,+3KCl+3{{H}_{2}}O\] 

\[{{C}_{6}}{{H}_{5}}-NH-C{{H}_{3}}\xrightarrow{CHC{{l}_{3}}+3KOH}\text{No reaction}\] 


3. Account for the Following

a. ${{p}^{{{K}_{b}}}}$ of aniline is more than that of methylamine

Ans: In aniline, the lone pair of electrons on the N-atom is delocalized over the benzene ring. As a result, electron density on the nitrogen atom decreases. Whereas in $C{{H}_{3}}N{{H}_{2}}$ ,+ I-effect of $-C{{H}_{3}}$  group increases the electron density on the N-atom. Therefore, aniline is a weaker base than methylamine and hence its ${{p}^{{{K}_{b}}}}$ value is higher than that of methylamine.


b. Ethylamine is soluble in water whereas aniline is not.

Ans: Ethylamine dissolves in water due to intermolecular H-bonding. However, in case of aniline, due to the large hydrophobic part, i.e., hydrocarbon part, the extent of H-bonding is very less therefore aniline is insoluble in water.


Ethylamine is soluble in water whereas aniline is not


c. Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.

Ans: Methylamine being more basic than water, accepts a proton from water liberating $O{{H}^{-}}$ ions.


Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide


These $O{{H}^{-}}$ ions combine with $F{{e}^{+3}}$  ions present in ${{H}_{2}}O$ to form brown precipitate of hydrated ferric oxide.

\[FeC{{l}_{3}}\to F{{e}^{+3}}+3C{{l}^{-}}\] 

\[2F{{e}^{+3}}+6OH\underset{\text{Brown ppt}}{\mathop{^{-}\to 2Fe{{(OH)}_{3}}orF{{e}_{2}}{{O}_{3}}.3{{H}_{2}}O}}\,\] 


d. Although amino group is o and p — directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.

Ans: Nitration is usually carried out with a mixture of conc $HN{{O}_{3}}$ + conc ${{H}_{2}}S{{O}_{4}}$ . In presence of these acids, most of aniline gets protonated to form anilinium ion. Therefore, in the presence of acids, the reaction mixture consists of aniline and anilinium ion. Now, $-N{{H}_{2}}$  group in aniline is activating and o, p-directing while the $N{{H}_{3}}^{+}$  group in anilinium ion is deactivating and m-directing: Nitration of aniline (due to steric hindrance at o-position) mainly gives p-nitroaniline, the nitration of anilinium ion gives m-nitroaniline. In actual practice, approx a 1:1 mixture of p-nitroaniline and m-nitroaniline is obtained. Thus, nitration of aniline gives a substantial amount of m-nitroaniline due to protonation of the amino group.


Amino group is o and p — directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline


e. Aniline does not undergo Friedel-Crafts reaction.

Ans: Aniline being a Lewis base reacts with Lewis acid $AlC{{l}_{3}}$ to form a salt.

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}}+AlC{{l}_{3}}\to {{C}_{6}}{{H}_{5}}N{{H}_{2}}^{+}AlC{{l}_{3}}^{-}\] 

As a result, N of aniline acquires positive charge and hence it acts as a strong deactivating group for electrophilic substitution reactions. Consequently, aniline does not undergo Friedel Crafts reaction.


f. Diazonium salts of aromatic amines are more stable than those of aliphatic amines.

Ans: The diazonium salts of aromatic amines are more stable than those of aliphatic amines due to dispersal of the positive charge on benzene ring as a result of resonance


Diazonium salts of aromatic amines are more stable than those of aliphatic amines


g. Gabriel phthalimide synthesis is preferred for synthesizing primary amines.

Ans: Gabriel phthalimide reaction gives pure primary amines without any contamination of secondary and tertiary amines. Therefore, it is preferred for synthesizing primary amines.


4. Arrange the Following.

i. In Decreasing Order of ${{p}^{{{K}_{b}}}}$Values:

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}},{{C}_{6}}{{H}_{5}}NHC{{H}_{3}},{{({{C}_{2}}{{H}_{5}})}_{2}}NH\And {{C}_{2}}{{H}_{5}}N{{H}_{2}}\] 

Ans: In ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$ , only one $-{{C}_{2}}{{H}_{5}}$ group is present while in ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$, two $-{{C}_{2}}{{H}_{5}}$ groups are present. Thus, the +I effect is more in ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$ than in ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$. Therefore, the electron density over the N-atom is more in ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$ than in ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$. Hence, ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$  is more basic than ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$. Also, both ${{C}_{6}}{{H}_{5}}NHC{{H}_{3}}$ and ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ are less basic than ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$ and ${{C}_{2}}{{H}_{5}}N{{H}_{2}}$ due to the delocalization of the lone pair in the former two. Further, among ${{C}_{6}}{{H}_{5}}NHC{{H}_{3}}$ and${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ , the former will be more basic due to the +I effect of $-C{{H}_{3}}$  group. Hence, the order of increasing basicity of the given compounds is as follows:

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < {{C}_{6}}{{H}_{5}}NHC{{H}_{3}} < {{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{2}}{{H}_{5}})}_{2}}NH\] 

We know that the higher the basic strength, the lower is the ${{p}^{{{K}_{b}}}}$ values

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} > {{C}_{6}}{{H}_{5}}NHC{{H}_{3}} > {{C}_{2}}{{H}_{5}}N{{H}_{2}} > {{({{C}_{2}}{{H}_{5}})}_{2}}NH\] 


ii. In Increasing Order of Basic Strength 

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}},{{C}_{6}}{{H}_{5}}N{{(C{{H}_{3}})}_{2}},{{({{C}_{2}}{{H}_{5}})}_{2}}NH\And C{{H}_{3}}N{{H}_{2}}\] 

Ans: Among $C{{H}_{3}}N{{H}_{2}}$  and ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$, primarily due to the greater +I-effect of the two $-{{C}_{2}}{{H}_{5}}$ groups over one $-C{{H}_{3}}$ group, ${{({{C}_{2}}{{H}_{5}})}_{2}}NH$ is more basic than $C{{H}_{3}}N{{H}_{2}}$. In both ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ and ${{C}_{6}}{{H}_{5}}N{{(C{{H}_{3}})}_{2}}$ lone pair of electrons present on N-atom is delocalized over the benzene ring but ${{C}_{6}}{{H}_{5}}N{{(C{{H}_{3}})}_{2}}$is more basic due to +I effect of two $-C{{H}_{3}}$groups.

\[{{({{C}_{2}}{{H}_{5}})}_{2}}NH > C{{H}_{3}}N{{H}_{2}} > {{C}_{6}}{{H}_{5}}N{{(C{{H}_{3}})}_{2}} > {{C}_{6}}{{H}_{5}}N{{H}_{2}}\] 

Decreasing basic strength 

iii. In Increasing Order of Basic Strength 

(a) Aniline, P-Nitroaniline and P-Toluidine

Ans: The presence of electron donating  $-C{{H}_{3}}$group increases while the presence of electron withdrawing $N{{O}_{2}}$  group decreases the basic strength of amines. 

\[\therefore p-nitroaniline < \text{ }aniline\text{ } < \text{ }p-toluidine\] 

Increasing basic strength 


(b) \[{{C}_{6}}{{H}_{5}}N{{H}_{2}},{{C}_{6}}{{H}_{5}}NHC{{H}_{3}},{{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}\] 

Ans: In ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ and ${{C}_{6}}{{H}_{5}}NHC{{H}_{3}}$, Nitrogen is directly attached to the benzene ring. As a result, the lone pair of electrons on the N-atom is delocalized over the benzene ring. Therefore, both ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ and ${{C}_{6}}{{H}_{5}}NHC{{H}_{3}}$ are weaker base in comparison to ${{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}$. Among ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$ and ${{C}_{6}}{{H}_{5}}NHC{{H}_{3}}$, due to +1 effect of $-C{{H}_{3}}$group ${{C}_{6}}{{H}_{5}}NHC{{H}_{3}}$ is more basic.

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < {{C}_{6}}{{H}_{5}}NHC{{H}_{3}} < {{C}_{6}}{{H}_{5}}C{{H}_{2}}N{{H}_{2}}\]

Increasing basic strength 


iv. In Decreasing Order of Basic Strength in Gas Phase

\[{{C}_{2}}{{H}_{5}}N{{H}_{2}},{{({{C}_{2}}{{H}_{5}})}_{2}}NH,{{({{C}_{2}}{{H}_{5}})}_{3}}N\And N{{H}_{3}}\] 

Ans: In gas phase or in non-aqueous solvents such as chlorobenzene etc, the solvation effects 

i. e. the stabilization of the conjugate acid due to H-bonding is absent. Therefore, basic strength depends only upon the +I-effect of the alkyl groups. The +I-effect increases with increase in the number of alkyl groups. Thus, correct order of decreasing basic strength in gas phase is,

\[\therefore {{({{C}_{2}}{{H}_{5}})}_{3}}N > {{({{C}_{2}}{{H}_{5}})}_{2}}N > {{C}_{2}}{{H}_{5}}N{{H}_{2}} > N{{H}_{3}}\] 

Decreasing basic strength


v. In Increasing Order of Boiling Point

\[{{C}_{2}}{{H}_{5}}OH,(C{{H}_{3}})NH,{{C}_{2}}{{H}_{5}}N{{H}_{2}}\] 

Ans: Since the electronegativity of Oxygen is higher than that of Nitrogen, therefore, alcohols form stronger H-bonds than amines. Also, the extent of H-bonding depends upon the number of H-atoms on the N-atom, thus the extent of H-bonding is greater in primary amine than secondary amine.

\[{{(C{{H}_{3}})}_{2}}N{{H}_{2}} < {{C}_{2}}{{H}_{5}}N{{H}_{2}} < {{C}_{2}}{{H}_{5}}OH\] 

Increasing boiling point

vi. In Increasing Order of Solubility in Water

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}},{{({{C}_{5}}{{H}_{5}})}_{2}}NH,{{C}_{2}}{{H}_{5}}N{{H}_{2}}\] 

Ans: Solubility decreases with increase in molecular mass of amines due to increase in the size of the hydrophobic hydrocarbon part and with decrease in the number of H-atoms on the N-atom which undergo H-bonding.

\[{{C}_{6}}{{H}_{5}}N{{H}_{2}} < {{({{C}_{6}}{{H}_{5}})}_{2}}NH < {{C}_{2}}{{H}_{5}}N{{H}_{2}}\] 

Increasing solubility 


5. How Will You Convert?

i. Ethanoic Acid into Methanamine

Ans: 

\[C{{H}_{3}}COOH\xrightarrow[-S{{O}_{2}},-HCl]{SOC{{l}_{2}}}C{{H}_{3}}COCl\xrightarrow[N{{H}_{4}}Cl]{N{{H}_{3}}(excess)}C{{H}_{3}}CON{{H}_{2}}\xrightarrow[{}]{B{{r}_{2}}/NaOH}C{{H}_{3}}N{{H}_{2}}\] 


ii. Hexanenitrile into 1-Aminopentane.

Ans: 

\[C{{H}_{3}}{{(C{{H}_{2}})}_{4}}CN\xrightarrow{{{H}_{3}}{{O}^{+}}}C{{H}_{3}}{{(C{{H}_{2}})}_{4}}COOH\xrightarrow[-S{{O}_{2}},-HCl]{SOC{{l}_{2}}}C{{H}_{3}}{{(C{{H}_{2}})}_{4}}COCl\xrightarrow[-N{{H}_{4}}Cl]{N{{H}_{3}}(excess)}C{{H}_{3}}{{(C{{H}_{2}})}_{4}}CON{{H}_{2}}\xrightarrow[{}]{B{{r}_{2}}/NaOH}C{{H}_{3}}{{(C{{H}_{2}})}_{4}}N{{H}_{2}}\]

 

iii. Methanol to Ethanoic Acid.

Ans: 

\[C{{H}_{3}}OH\xrightarrow[-POC{{l}_{5}}]{PC{{l}_{5}}}C{{H}_{3}}Cl\xrightarrow{KCN(alc)}C{{H}_{3}}CN\xrightarrow{{{H}_{3}}{{O}^{+}}}C{{H}_{3}}COOH\] 


iv. Ethanamine into Methanamine

Ans:

\[C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}\xrightarrow[-{{N}_{2}},-{{H}_{2}}O]{HONO}C{{H}_{3}}C{{H}_{2}}OH\xrightarrow[{}]{{{K}_{2}}C{{r}_{2}}{{O}_{7}}/{{H}_{2}}S{{O}_{4}}}C{{H}_{3}}CHO\xrightarrow{{{K}_{2}}C{{r}_{2}}{{O}_{7}}/{{H}_{2}}S{{O}_{4}}}C{{H}_{3}}COOH\]

\[C{{H}_{3}}COOH\xrightarrow{N{{H}_{3}}}C{{H}_{3}}COON{{H}_{4}}\xrightarrow[-{{H}_{2}}O]{}C{{H}_{3}}CON{{H}_{2}}\xrightarrow{B{{r}_{2}}/NaOH}C{{H}_{3}}N{{H}_{2}}\]  


v. Ethanoic Acid into Propanoic Acid 

Ans:

\[C{{H}_{3}}COOH\xrightarrow{LiAl{{H}_{4}}}C{{H}_{3}}C{{H}_{2}}OH\xrightarrow[orP{{I}_{3}}]{P+{{I}_{2}}}C{{H}_{3}}C{{H}_{2}}I\xrightarrow[-KI]{KCN}C{{H}_{3}}C{{H}_{2}}CN\] 


vi. Methanamine into Ethanamine

Ans:

\[C{{H}_{3}}N{{H}_{2}}\xrightarrow[-{{N}_{2}},-{{H}_{2}}O]{HONO}C{{H}_{3}}OH\xrightarrow{P{{I}_{2}}}C{{H}_{3}}I\xrightarrow[-KI]{KCN}C{{H}_{3}}CN\xrightarrow[{}]{Na/{{C}_{2}}{{H}_{5}}OH}C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}\] 


vii. Nitromethane into Dimethylamine 

Ans: 

\[C{{H}_{3}}N{{O}_{2}}\xrightarrow{Sn/HCl}C{{H}_{3}}N{{H}_{2}}\xrightarrow{CHC{{l}_{3}},KOH\Delta }C{{H}_{3}}NC\xrightarrow{LiAl{{H}_{4}}}C{{H}_{3}}NHC{{H}_{3}}\] 


viii. Propanoic Acid into Ethanoic Acid

Ans: 

\[C{{H}_{3}}C{{H}_{2}}COOH\xrightarrow[\Delta ]{N{{H}_{3}}}C{{H}_{3}}C{{H}_{2}}CON{{H}_{2}}\xrightarrow{B{{r}_{2}}/NaOH}C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}\xrightarrow{HN{{O}_{2}}}C{{H}_{3}}C{{H}_{2}}OH\xrightarrow{Alk.KMn{{O}_{4}}}C{{H}_{3}}COOH\]


6. Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.

Ans: The three types of amines can be distinguished by Heinsberg test. In this test, the amine is shaken with benzene sulphonyl chloride (${{C}_{6}}{{H}_{5}}S{{O}_{2}}Cl$ ) in the presence of excess of aqueous NaOH or KOH. A primary amine reacts to give a clear solution, which on acidification yields an insoluble compound.

\[RN{{H}_{2}}+{{C}_{6}}{{H}_{5}}S{{O}_{2}}Cl\xrightarrow[-HCl]{O{{H}^{-}}}{{C}_{6}}{{H}_{5}}S{{O}_{2}}NHR\xrightarrow{KOH}{{C}_{6}}{{H}_{5}}S{{O}_{2}}{{N}^{-}}R{{K}^{+}}\underset{\text{Insoluble}}{\mathop{\xrightarrow{{{H}^{+}}}{{C}_{6}}{{H}_{5}}S{{O}_{2}}NHR}}\,\] 

A secondary amine forms an insoluble compound, which remains insoluble even on acidification.

\[{{R}_{2}}NH+{{C}_{6}}{{H}_{5}}S{{O}_{2}}Cl\xrightarrow[-HCl]{O{{H}^{-}}}\underset{\text{Insoluble}}{\mathop{{{C}_{6}}{{H}_{5}}S{{O}_{2}}N{{R}_{2}}}}\,\xrightarrow{{{H}^{+}}}No\text{ }reaction\] 

A tertiary amine does not react with the reagent, but dissolves as acid.

\[{{C}_{6}}{{H}_{5}}S{{O}_{2}}Cl+{{R}_{3}}N\xrightarrow{O{{H}^{+}}}\text{No reaction}\] 

\[{{R}_{3}}N+{{H}^{+}}\to\underset{\text{clear solution}}{\mathop{{{[{{R}_{3}}NH]}^{+}}}}\,\] 


7. Write a short note on the following.

i. Carbylamine reaction

Ans: Both aliphatic and aromatic primary amines when warmed with chloroform and an alcoholic solution of KOH, produces isocyanides or carbylamines which have a very unpleasant odour. This reaction is called carbylamine reaction.

\[R-N{{H}_{2}}+CHC{{l}_{3}}+3KOH(alc)\to R-N\equiv C+3KCl+3{{H}_{2}}O\]


ii. Diazotization

Ans: The process of conversion of a primary aromatic amino compound into a diazonium salt, is known as diazotization. This process is carried out by adding an aqueous solution of sodium nitrite to a solution of primary aromatic amine (e.g., aniline) in excess of at a temperature below ${{5}^{0}}C$ . HCl

\[\underset{{{1}^{0}}\text{amine}}{\mathop{ArN{{H}_{2}}}}\,+NaO{{H}_{2}}+2HX\xrightarrow{273-278K}\underset{\text{Arene Diazonium salt}}{\mathop{Ar{{N}_{2}}^{+}{{X}^{-}}}}\,+NaX+2{{H}_{2}}O\] 


iii. Hofmann’s Bromamide Reaction 

Ans: When an amide is treated with bromine in alkali solution, it is converted to a primary amine that has one carbon atom less than the starting amide. This reaction is known as Hoffmann’s bromamide degradation reaction.

\[{{C}_{6}}{{H}_{5}}CON{{H}_{2}}\xrightarrow{B{{r}_{2}}+NaOH}{{C}_{6}}{{H}_{5}}N{{H}_{2}}\] 


iv. Coupling Reaction 

Ans: In this reaction, arenediazonium salt reacts with aromatic amino compounds (in acidic medium) or a phenol (in alkaline medium) to form brightly coloured azo compounds. The reaction generally takes place at para position to the hydroxyl or amino group. If para position is blocked, it occurs at ortho position and if both ortho and para positions are occupied, then no coupling takes place. 


Coupling Reaction


v. Ammonolysis 

Ans: It is a process of replacement of either halogen atom in alkyl halides (or aryl halides) or hydroxyl group in alcohols (or phenols) by amino group. The reagent used for ammonolysis is alcoholic ammonia. Generally, a mixture of primary, secondary and tertiary amine is formed.

\[ROH+N{{H}_{3}}\xrightarrow[\text{Hightemp}\text{., Pressure}]{A{{l}_{2}}{{O}_{3}},\Delta }RN{{H}_{2}}+{{H}_{2}}O\] 

\[\underset{{{1}^{0}}}{\mathop{R-N{{H}_{2}}}}\,\xrightarrow[-{{H}_{2}}O]{ROH}\underset{{{2}^{0}}}{\mathop{{{R}_{2}}NH}}\,\xrightarrow[-{{H}_{2}}O]{ROH}\underset{{{3}^{0}}}{\mathop{{{R}_{3}}N}}\,\xrightarrow[{}]{ROH}{{R}_{4}}{{N}^{+}}O{{H}^{-}}\]

 

vi. Acetylation 

Ans: The process of introducing an acetyl $(C{{H}_{3}}CO-)$  group into a molecule using acetyl chloride or acetic anhydride is called acetylation.


vii. Gabriel Phthalimide Synthesis

Ans: It is a method of preparation of pure aliphatic and aralkyl primary amines. Phthalimide on treatment with ethanolic KOH gives potassium phthalimide which on heating with a suitable alkyl or aralkyl halides gives N-substituted phthalimides, which on hydrolysis with dil HCl or with alkali give primary amines.


Gabriel Phthalimide Synthesis


8. Accomplish the following conversations:

i. Nitrobenzene to Benzoic Acid

Ans:


Nitrobenzene to Benzoic Acid


ii. Benzene to M-Bromophenol

Ans:


Benzene to M-Bromophenol


iii. Benzoic Acid to Aniline

Ans: 


Benzoic Acid to Aniline


iv. Aniline to 2,4,6-Tribromofluorobenzene

Ans: 


Aniline to 2,4,6-Tribromofluorobenzene


v. Benzyl chloride to 2-phenylethanamine

Ans:


Benzyl chloride to 2-phenylethanamine


vi. Chlorobenzene to P-Chloroaniline

Ans:


Chlorobenzene to P-Chloroaniline


vii. Aniline to p-bromoaniline

Ans:


Aniline to p-bromoaniline
 


viii. Benzamide to Toluene 

Ans:


Benzamide to Toluene


ix. Aniline to Benzyl Alcohol.

Ans:


Aniline to Benzyl Alcohol


9. Give the structures of A, B and C in the following reaction:

i. \[C{{H}_{3}}C{{H}_{2}}I\xrightarrow{NaCN}A\xrightarrow[\text{Partial hydrolysis}]{O{{H}^{-}}}B\xrightarrow{NaOH+B{{r}_{2}}}C\]

Ans: 

$A=C{{H}_{3}}C{{H}_{2}}CN,B=C{{H}_{3}}C{{H}_{2}}CON{{H}_{2}},C=C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}$ 


ii. ${{C}_{6}}{{H}_{5}}Cl\xrightarrow{CuCN}A\xrightarrow{{{H}_{2}}O/{{H}^{+}}}B\underset{\Delta }{\mathop{\xrightarrow{N{{H}_{3}}}}}\,C$ 

Ans: 

$A={{C}_{6}}{{H}_{5}}CN,B={{C}_{6}}{{H}_{5}}COOH,C={{C}_{6}}{{H}_{5}}CON{{H}_{2}}$ 


iii. $C{{H}_{3}}C{{H}_{2}}Br\xrightarrow{KCN}A\xrightarrow{LiAl{{H}_{4}}}B\underset{{{0}^{o}}C}{\mathop{\xrightarrow{HN{{O}_{2}}}}}\,C$ 

Ans:

$A=C{{H}_{3}}C{{H}_{2}}CN,B=C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}N{{H}_{2}},C=C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}OH$ 


iv. ${{C}_{6}}{{H}_{5}}N{{O}_{2}}\xrightarrow{Fe/HCl}A\xrightarrow[273K]{NaN{{O}_{2}}+HCl}B\xrightarrow[\Delta ]{{{H}_{2}}O/{{H}^{+}}}C$ 

Ans:

$A={{C}_{6}}{{H}_{5}}N{{H}_{2}},B={{C}_{6}}{{H}_{5}}{{N}_{2}}C{{l}^{-}},C={{C}_{6}}{{H}_{5}}OH$ 


v. $C{{H}_{3}}COOH\xrightarrow[\Delta ]{N{{H}_{3}}}A\xrightarrow{NaOBr}B\xrightarrow[HCl]{NaN{{O}_{2}}}C$ 

Ans: $A=C{{H}_{3}}CON{{H}_{2}},B=C{{H}_{3}}N{{H}_{2}},C=C{{H}_{3}}OH$ 


vi. ${{C}_{6}}{{H}_{5}}N{{O}_{2}}\xrightarrow{Fe/HCl}A\underset{273K}{\mathop{\xrightarrow{HN{{O}_{2}}}}}\,B\xrightarrow{{{C}_{6}}{{H}_{5}}OH}C$ 

Ans: $A={{C}_{6}}{{H}_{5}}N{{H}_{2}},B={{C}_{6}}{{H}_{5}}{{N}_{2}}^{+}C{{l}^{-}}$ and C =


$A={{C}_{6}}{{H}_{5}}N{{H}_{2}},B={{C}_{6}}{{H}_{5}}{{N}_{2}}^{+}C{{l}^{-}}$ and C



10. An aromatic compound ‘A’ on treatment with aqueous ammonia and heating forms compound ‘B’ which on heating with $B{{r}_{2}}$ and KOH forms a compound ‘C. of molecular formula ${{C}_{6}}{{H}_{7}}N$. Write the structures and IUPAC names of compounds A, B and C.

Ans: Since the compound C with molecular formula ${{C}_{6}}{{H}_{7}}N$  is formed from compound B on treatment with $B{{r}_{2}}$ and KOH, therefore, compound ‘B’ must be an amide and ‘C’ must be an amine. The only amine having the molecular formula ${{C}_{6}}{{H}_{7}}N$, i.e., ${{C}_{6}}{{H}_{5}}N{{H}_{2}}$  is aniline. Since ‘C is aniline, therefore, the amide from which it is formed must be benzamide (${{C}_{6}}{{H}_{5}}CON{{H}_{2}}$). Thus, compound ’B’ is benzamide. Since compound 'B' is formed from a compound with aqueous ammonia and heating, therefore, compound ‘A’ must be benzoic acid.


11. Complete the following reaction:

i. ${{C}_{6}}{{H}_{5}}N{{H}_{2}}+CHC{{l}_{3}}+alcKOH\to $ 

Ans: 

${{C}_{6}}{{H}_{5}}N{{H}_{2}}+CHC{{l}_{3}}+alc.KOH\overset{\Delta }{\mathop{\to }}\,{{C}_{6}}{{H}_{5}}NC+3KCl+3{{H}_{2}}O$


ii. ${{C}_{6}}{{H}_{5}}{{N}_{2}}Cl+{{H}_{3}}P{{O}_{2}}+{{H}_{2}}O\to $ 

Ans: ${{C}_{6}}{{H}_{5}}{{N}_{2}}Cl+{{H}_{3}}P{{O}_{2}}+{{H}_{2}}O\xrightarrow{C{{u}^{+}}}{{C}_{6}}{{H}_{6}}+{{N}_{2}}+{{H}_{3}}P{{O}_{3}}+HCl$


iii. ${{C}_{6}}{{H}_{5}}N{{H}_{2}}+{{H}_{2}}S{{O}_{4}}(conc)\to $ 

Ans: 


${{C}_{6}}{{H}_{5}}N{{H}_{2}}+{{H}_{2}}S{{O}_{4}}(conc)\to $


iv. ${{C}_{6}}{{H}_{5}}{{N}_{2}}Cl+{{C}_{2}}{{H}_{5}}OH\to $ 

Ans: 

${{C}_{6}}{{H}_{5}}{{N}_{2}}Cl+{{C}_{2}}{{H}_{5}}OH\to {{C}_{6}}{{H}_{6}}+C{{H}_{3}}CHO+{{N}_{2}}+HCl$ 


v. ${{C}_{6}}{{H}_{5}}N{{H}_{2}}+B{{r}_{2}}(aq)\to $ 

Ans: 

${{C}_{6}}{{H}_{5}}N{{H}_{2}}+B{{r}_{2}}(aq)\to $



vi. ${{C}_{6}}{{H}_{5}}N{{H}_{2}}+{{(C{{H}_{3}}CO)}_{2}}O\to $ 

Ans: ${{C}_{6}}{{H}_{5}}N{{H}_{2}}+{{(C{{H}_{3}}CO)}_{2}}O\xrightarrow{C{{H}_{3}}COOH}{{C}_{6}}{{H}_{5}}NHCOC{{H}_{3}}+C{{H}_{3}}COOH$


vii. ${{C}_{6}}{{H}_{5}}{{N}_{2}}Cl\xrightarrow[(ii)NaN{{O}_{2}}/Cu.\Delta ]{(i)HB{{F}_{4}}}$

Ans: 

${{C}_{6}}{{H}_{5}}{{N}_{2}}Cl\xrightarrow[(ii)NaN{{O}_{2}}/Cu.\Delta ]{(i)HB{{F}_{4}}}{{C}_{6}}{{H}_{5}}N{{O}_{2}}+{{N}_{2}}+NaB{{F}_{4}}$ 


12. Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?

Ans: The success of Gabriel phthalimide reaction depends upon the nucleophilic attack by the phthalimide anion on the organic halogen compound. Since aryl halides do not undergo nucleophilic substitution reactions easily, therefore, arylamines, i.e. aromatic, primary amines cannot be prepared by Gabriel phthalimide reaction.


Aromatic primary amines be prepared by Gabriel phthalimide synthesis


No reaction


13. Write the reactions of aromatic and aliphatic primary amines with nitrous acid.

Ans: Both aromatic and aliphatic primary amines react with $HN{{O}_{2}}$  at 273-278 K to form aromatic and aliphatic diazonium salts respectively. But aliphatic diazonium salts are unstable even at this low temperature and thus decompose readily to form a mixture of compounds. Aromatic and aliphatic primary amines react with $HN{{O}_{2}}$ as follows


The reactions of aromatic and aliphatic primary amines with nitrous acid


\[C{{H}_{3}}C{{H}_{2}}N{{H}_{2}}+HONO+HCl\xrightarrow[-{{H}_{2}}O]{273-278K}[C{{H}_{3}}C{{H}_{2}}-{{N}^{+}}_{2}C{{l}^{-}}]\xrightarrow[273-278K]{\text{Decomposes}}C{{H}_{3}}C{{H}_{2}}OH+C{{H}_{2}}=C{{H}_{2}}+C{{H}_{3}}C{{H}_{2}}Cl+{{N}_{2}}\]


14. Give plausible explanation for each of the following:

i. Why are amines less acidic than alcohols of comparable molecular masses?

Ans: Loss of proton from an amine gives an amide ion while loss of a proton from alcohol gives an alkoxide ion.

\[R-N{{H}_{2}}\to R-N{{H}^{-}}+{{H}^{+}}\] 

\[R-O-H\to R-{{O}^{-}}+{{H}^{+}}\] 

Since O is more electronegative than N, it will attract positive species more strongly in comparison to N. Thus, RO is more stable than$RN{{H}^{-}}$ . Thus, alcohols are more acidic than amines. Conversely, amines are less acidic than alcohols.

ii. Why do primary amines have higher boiling point than tertiary amines?

Ans: Since O is more electronegative than N, it will attract positive species more strongly in comparison to N. Thus, RO is more stable than RNH-. Thus, alcohols are more acidic than amines. Conversely, amines are less acidic than alcohols.

iii.  Why aliphatic amines stronger bases than aromatic amines?

Ans: Aromatic amines are far less basic than ammonia and aliphatic amines because of following reasons: 

(a) Due to resonance in aniline and other aromatic amines, the lone pair of electrons on the nitrogen atom gets delocalized over the benzene ring and thus it is less easily available for protonation. Therefore, aromatic amines are weaker bases than ammonia and aliphatic amines. 

(b) Aromatic amines are more stable than corresponding protonated ion; Hence, they have very less tendency to combine with a proton to form corresponding protonated ion, and thus they are less basic.

 

Access NCERT solutions for Class 12 Chemistry Chapter – 13 Amines

Amines Class 12 NCERT Solutions PDF

Students may often face trouble understanding a chapter like this, and without proper understanding, they will not be able to formulate an appropriate strategy to solve the questions form this chapter in their exams. They can download the NCERT Solutions for class 12 Chemistry chapter 13 from Vedantu for free and refer to them for a better understanding of the concepts covered in this chapter.

 

These NCERT Solutions are accurate and are prepared with reference to the CBSE guidelines. These Solutions are easily accessible as all students can download and refer to it as per their convenience. Also, these CBSE NCERT Solutions are available on our mobile application.

 

Chapter 13 Chemistry Class 12

Besides being an essential chapter for boards, Amines class 12 NCERT is crucial for other competitive exams. Thereby, the students who want to appear for various competitive exams should make it a point to study this chapter thoroughly.

 

Important Topics Covered in NCERT Solutions Class 12 Chemistry Chapter 13 Amines 

The important topics and sub-topics covered in NCERT Class 12 Chemistry Chapter 13 Amines are listed below.

  • Nomenclature of Amines

  • Classification of Amines

  • Structure of Amines

  • Physical Properties of Amines

  • Preparation of Amines

  • Chemical Reactions

  • Methods of Preparation for Diazonium Salts

  • Physical Properties of Diazonium Salts

  • Chemical Reactions of Diazonium Salts

  • Importance of Diazonium Salts in the Synthesis of Aromatic Compounds

 

However, it is not always possible for students to find Solutions to every question on their own. They need professional help to guide them. The Amines class 12 NCERT Solutions on Vedantu come handy for students when it comes to finding answers for difficult questions. These NCERT Solutions consist of the following in-text answers written descriptively. 

  • Ch 13 Chemistry class 12 NCERT Solutions: Question 1

The answer to this question will help students to get an idea about the classification of amines. After they have solved this, they will be able to categorize amines as primary, secondary, and tertiary.

  • Amine class 12 NCERT Solutions: Question 2

After going through the elaborate explanation in their Solutions, students will learn about the structures and the IUPAC names of different isomeric amines.

  • NCERT Solutions for Class 12 Chemistry Chapter Amines: Question 3 and 4

The third answer uses elaborate diagrams to explain to students the conversion of Benzene. While in the fourth answer, students will learn how to arrange alkyl groups in the order of their basic strength.

  • NCERT Solution of Amine Class 12: Question 5, 6, and 7

In the fifth and sixth questions, students will have to complete certain chemical reactions and find the product. Students often mistake while writing the reactions. In such a case, these Solutions can be beneficial. Even if they are writing the answers on their own, they can refer to the Solutions to see if they are correct.

  • Chemistry Chapter 13 Class 12 NCERT Solutions: Question 8 and 9

The answer to question 8 will help students to enhance their knowledge about the structures of isomers. The next answer deals with the process of conversion.

Apart from this, Amines class 12 NCERT Solutions also contain answers to the 14 exercise questions which will help students to learn about the following.

  • Classification of Amines into the Following Category:

(Image Will Be Updated Soon)

  • IUPAC names of compounds.

  • Chemical properties.

  • Arranging according to pKb values.

  • Conversion.

  • Chemical reactions.

In class 12 CBSE, 4 marks come from Amines. The following table shows the marks distribution.

 

Amines Class 12 NCERT PDF: Marks Distribution

Very Short Answer (1 Mark)

Short Answer (II) (3 Marks)

Total Marks

1

3

4

 

Although the marks allotted to this chapter is less, students should not neglect this section. They can refer to NCERT Solutions of class 12 Chemistry chapter Amines while preparing.

 

Related Study Materials for Class 12 Chemistry Chapter 13 Amines

 

Advantages of NCERT Solutions for Class 12 Chemistry Chapter 13 Amines

The NCERT Solutions for Class 12 Chemistry Chapter 13 Amines has the following advantages.

  • Easy-to-understand language.

  • Elaborate explanation of topics as well as reactions.

  • Diagrams to help understand better.

  • Solutions framed by experienced faculty.

  • Solutions according to the CBSE norms


NCERT Solutions for Class 12 Chemistry 

 

Hence, students should download and refer to the Amines class 12 NCERT Solutions for a better understanding of the topics. The comprehensive knowledge acquired by them will help them to score well in their exams.


Conclusion

NCERT Solutions for Class 12 Chemistry Chapter 13 Amines covers a wide range of questions, answers and explanations that help students to learn and revise this chapter. The topics and sub-topics covered in this chapter provide a thorough knowledge base of the structure, types, and basicity of amines. Also, the preparation and several other important aspects of Amines are explained in detail in the NCERT Solutions for this Chapter on Vedantu. Students are suggested to download and prepare all the relevant study resources on NCERT Class 12 Chemistry Chapter 13 from Vedantu to ace their exams. 

FAQs on NCERT Solutions for Class 12 Chemistry Chapter 13 - Amines

1. What are the Three Categories of Amines?

Ans. Amines can be classified into primary, secondary, and tertiary depending on the number of hydrogen atoms replaced from ammonia by organic groups when a single hydrogen atom is replaced, a primary amine is formed.


When two or three hydrogen atoms are replaced, secondary and tertiary amines are formed, respectively. Students who will appear for their boards can expect multiple questions on this classification. Therefore, students should have a clear understanding of it.


Moreover, they can take the help of NCERT Solutions for class 12 Chemistry chapter 13 PDF to get a comprehensive knowledge of this topic. The elaborate explanation, along with the diagrams, will help them to understand it in a hassle-free way.

2. How Should I Study Amines for my Boards?

Ans. Amines are a crucial topic for boards and other competitive exams. Moreover, while preparing for this, students should focus on the categories of amines. They should also learn the IUPAC names of the various compounds. Apart from this, conversion and reactions have a significant share in this chapter. They should have an understanding of the chemical properties of Amines. However, studying all these topics without proper guidance may be difficult. Therefore, students can opt for NCERT Solutions for class 12 Chemistry chapter 13 PDF, which will help them to develop a clear understanding of these topics.

3. Why Should I Refer to NCERT Solutions for class 12 Chemistry Amines PDF?

Ans. Amine is a topic that demands conceptual clarity. To score well, students must have comprehensive knowledge about every subtopic. However, doing this without proper guidance may be difficult.  In this case, students can opt for NCERT Solutions for class 12 Chemistry chapter 13 PDF download. They can easily access these Solutions anywhere. All the questions are explained elaborately. Multiple diagrams are also used for better understanding, and the language used in these Solutions is straightforward.


Moreover, it will help them to study a topic as per their convenience. Also, these Solutions can be downloaded free of cost. After completing the exercises on their own, students can refer to the Solutions to verify their answers.

4.  How can I access the free PDF download of NCERT Solutions for Class 12 Chemistry Chapter 13 on Vedantu?

Ans: You can access the free PDF download of NCERT Solutions for Class 12 Chemistry Chapter 13 on Vedantu's website. Simply visit the website, locate the chapter, and click on the download link to get the solutions in PDF format.

5.  Are the NCERT Solutions for Class 12 Chemistry Chapter 13 accurate and reliable?

Ans: Yes, the NCERT Solutions provided by Vedantu are prepared by experienced subject experts. They are accurate, reliable, and follow the guidelines and syllabus provided by NCERT. Students can rely on these solutions for their exam preparation.

6. Can NCERT Solutions for Class 12 Chemistry Chapter 13 help me score better in exams?

Ans: Yes, NCERT Solutions for Class 12 Chemistry Chapter 13 are designed to help you understand the concepts thoroughly. By practising the solutions and solving the questions, you can improve your understanding and problem-solving skills, which can ultimately help you score better in your exams.