NCERT Textbook - Amines | NCERT Textbooks (Class 6 to Class 12) - CTET & State TET PDF Download

Download, print and study this document offline
Please wait while the PDF view is loading
 Page 1


Amines constitute an important class of organic
compounds derived by replacing one or more hydrogen
atoms of ammonia molecule by alkyl/aryl group(s). In
nature, they occur among proteins, vitamins, alkaloids
and hormones. Synthetic examples include polymers,
dyestuffs and drugs. Two biologically active compounds,
namely adrenaline and ephedrine, both containing
secondary amino group, are used to increase blood
pressure. Novocain, a synthetic amino compound, is
used as an anaesthetic in dentistry. Benadryl, a well
known antihistaminic drug also contains tertiary amino
group. Quaternary ammonium salts are used as
surfactants. Diazonium salts are intermediates in the
preparation of a  variety of aromatic compounds
including dyes. In this Unit, you will learn about amines
and diazonium salts.
I. AMINES
Amines can be considered as derivatives of ammonia,
obtained by replacement of one, two or all the three
hydrogen atoms by alkyl and/or aryl groups.
For example:
Like ammonia, nitrogen atom of amines is trivalent and
carries an unshared pair of electrons.  Nitrogen orbitals
in amines are therefore, sp
3
 hybridised and the geometry
of amines is pyramidal. Each of  the three sp
3
 hybridised
orbitals of nitrogen overlap with orbitals of hydrogen or
carbon depending upon the composition of the amines.
The fourth orbital of nitrogen in all amines contains an
unshared pair of electrons.  Due to the presence of
unshared pair of electrons, the angle C–N–E, (where E is
After studying this Unit, you will be
able to
• describe amines as derivatives of
ammonia having a pyramidal
structure;
• classify amines as primary,
secondary and tertiary;
• name amines by common names
and IUPAC system;
• describe some of the important
methods of preparation of amines;
• explain the properties of amines;
• distinguish between primary,
secondary and tertiary amines;
• describe the method of prepara-
tion of diazonium salts and their
importance in the synthesis of a
series of aromatic compounds
including azo dyes.
Objectives
“The chief commercial use of amines is as intermediates in the
synthesis of medicines and fibres” .
Unit Unit Unit Unit Unit
13
A A A A Amines mines mines mines mines
13
A A A A Amines mines mines mines mines
13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines
2015-16
Page 2


Amines constitute an important class of organic
compounds derived by replacing one or more hydrogen
atoms of ammonia molecule by alkyl/aryl group(s). In
nature, they occur among proteins, vitamins, alkaloids
and hormones. Synthetic examples include polymers,
dyestuffs and drugs. Two biologically active compounds,
namely adrenaline and ephedrine, both containing
secondary amino group, are used to increase blood
pressure. Novocain, a synthetic amino compound, is
used as an anaesthetic in dentistry. Benadryl, a well
known antihistaminic drug also contains tertiary amino
group. Quaternary ammonium salts are used as
surfactants. Diazonium salts are intermediates in the
preparation of a  variety of aromatic compounds
including dyes. In this Unit, you will learn about amines
and diazonium salts.
I. AMINES
Amines can be considered as derivatives of ammonia,
obtained by replacement of one, two or all the three
hydrogen atoms by alkyl and/or aryl groups.
For example:
Like ammonia, nitrogen atom of amines is trivalent and
carries an unshared pair of electrons.  Nitrogen orbitals
in amines are therefore, sp
3
 hybridised and the geometry
of amines is pyramidal. Each of  the three sp
3
 hybridised
orbitals of nitrogen overlap with orbitals of hydrogen or
carbon depending upon the composition of the amines.
The fourth orbital of nitrogen in all amines contains an
unshared pair of electrons.  Due to the presence of
unshared pair of electrons, the angle C–N–E, (where E is
After studying this Unit, you will be
able to
• describe amines as derivatives of
ammonia having a pyramidal
structure;
• classify amines as primary,
secondary and tertiary;
• name amines by common names
and IUPAC system;
• describe some of the important
methods of preparation of amines;
• explain the properties of amines;
• distinguish between primary,
secondary and tertiary amines;
• describe the method of prepara-
tion of diazonium salts and their
importance in the synthesis of a
series of aromatic compounds
including azo dyes.
Objectives
“The chief commercial use of amines is as intermediates in the
synthesis of medicines and fibres” .
Unit Unit Unit Unit Unit
13
A A A A Amines mines mines mines mines
13
A A A A Amines mines mines mines mines
13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines
2015-16
382 Chemistry
C or H) is less than 109.5°; for instance, it is 108
o
 in case of
trimethylamine as shown in Fig. 13.1.
Amines are classified as primary (1
o
), secondary (2
o
) and tertiary (3
o
)
depending upon the number of hydrogen atoms replaced by alkyl or
aryl groups in ammonia molecule.  If one hydrogen atom of ammonia
is replaced by R or Ar , we get RNH
2 
or ArNH
2
, a primary amine (1
o
).
If two hydrogen atoms of ammonia or one hydrogen atom of R-NH
2
 are
replaced by another alkyl/aryl(R’) group,  what would you get? You
get R-NHR’, secondary amine.  The second alkyl/aryl group may be
same or different. Replacement of another hydrogen atom by alkyl/aryl
group leads to the formation of tertiary amine. Amines are said to be
‘simple’ when all the alkyl or aryl groups are the same, and ‘mixed’
when they are different.
In common system, an aliphatic amine is named by prefixing alkyl
group to amine, i.e., alkylamine as one word (e.g., methylamine).  In
secondary and tertiary amines, when two or more groups are the same,
the prefix di or tri is appended before the name of alkyl group.  In
IUPAC system, amines are named as alkanamines, derived by
replacement of ‘e’ of alkane by the word amine. For example, CH
3
NH
2
is named as methanamine. In case, more than one amino group is
present at different positions in the parent chain, their positions are
specified by giving numbers to the carbon atoms bearing –NH
2
 groups
and suitable prefix such as di, tri, etc. is attached to the amine. The
letter ‘e’ of the suffix of the hydrocarbon part is retained. For example,
H
2
N–CH
2
–CH
2
–NH
2
 is named as ethane-1, 2-diamine.
13.2 13.2 13.2 13.2 13.2 Classification Classification Classification Classification Classification
Fig. 13.1 Pyramidal shape of trimethylamine
13.3 13.3 13.3 13.3 13.3 Nomenclature Nomenclature Nomenclature Nomenclature Nomenclature
2015-16
Page 3


Amines constitute an important class of organic
compounds derived by replacing one or more hydrogen
atoms of ammonia molecule by alkyl/aryl group(s). In
nature, they occur among proteins, vitamins, alkaloids
and hormones. Synthetic examples include polymers,
dyestuffs and drugs. Two biologically active compounds,
namely adrenaline and ephedrine, both containing
secondary amino group, are used to increase blood
pressure. Novocain, a synthetic amino compound, is
used as an anaesthetic in dentistry. Benadryl, a well
known antihistaminic drug also contains tertiary amino
group. Quaternary ammonium salts are used as
surfactants. Diazonium salts are intermediates in the
preparation of a  variety of aromatic compounds
including dyes. In this Unit, you will learn about amines
and diazonium salts.
I. AMINES
Amines can be considered as derivatives of ammonia,
obtained by replacement of one, two or all the three
hydrogen atoms by alkyl and/or aryl groups.
For example:
Like ammonia, nitrogen atom of amines is trivalent and
carries an unshared pair of electrons.  Nitrogen orbitals
in amines are therefore, sp
3
 hybridised and the geometry
of amines is pyramidal. Each of  the three sp
3
 hybridised
orbitals of nitrogen overlap with orbitals of hydrogen or
carbon depending upon the composition of the amines.
The fourth orbital of nitrogen in all amines contains an
unshared pair of electrons.  Due to the presence of
unshared pair of electrons, the angle C–N–E, (where E is
After studying this Unit, you will be
able to
• describe amines as derivatives of
ammonia having a pyramidal
structure;
• classify amines as primary,
secondary and tertiary;
• name amines by common names
and IUPAC system;
• describe some of the important
methods of preparation of amines;
• explain the properties of amines;
• distinguish between primary,
secondary and tertiary amines;
• describe the method of prepara-
tion of diazonium salts and their
importance in the synthesis of a
series of aromatic compounds
including azo dyes.
Objectives
“The chief commercial use of amines is as intermediates in the
synthesis of medicines and fibres” .
Unit Unit Unit Unit Unit
13
A A A A Amines mines mines mines mines
13
A A A A Amines mines mines mines mines
13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines
2015-16
382 Chemistry
C or H) is less than 109.5°; for instance, it is 108
o
 in case of
trimethylamine as shown in Fig. 13.1.
Amines are classified as primary (1
o
), secondary (2
o
) and tertiary (3
o
)
depending upon the number of hydrogen atoms replaced by alkyl or
aryl groups in ammonia molecule.  If one hydrogen atom of ammonia
is replaced by R or Ar , we get RNH
2 
or ArNH
2
, a primary amine (1
o
).
If two hydrogen atoms of ammonia or one hydrogen atom of R-NH
2
 are
replaced by another alkyl/aryl(R’) group,  what would you get? You
get R-NHR’, secondary amine.  The second alkyl/aryl group may be
same or different. Replacement of another hydrogen atom by alkyl/aryl
group leads to the formation of tertiary amine. Amines are said to be
‘simple’ when all the alkyl or aryl groups are the same, and ‘mixed’
when they are different.
In common system, an aliphatic amine is named by prefixing alkyl
group to amine, i.e., alkylamine as one word (e.g., methylamine).  In
secondary and tertiary amines, when two or more groups are the same,
the prefix di or tri is appended before the name of alkyl group.  In
IUPAC system, amines are named as alkanamines, derived by
replacement of ‘e’ of alkane by the word amine. For example, CH
3
NH
2
is named as methanamine. In case, more than one amino group is
present at different positions in the parent chain, their positions are
specified by giving numbers to the carbon atoms bearing –NH
2
 groups
and suitable prefix such as di, tri, etc. is attached to the amine. The
letter ‘e’ of the suffix of the hydrocarbon part is retained. For example,
H
2
N–CH
2
–CH
2
–NH
2
 is named as ethane-1, 2-diamine.
13.2 13.2 13.2 13.2 13.2 Classification Classification Classification Classification Classification
Fig. 13.1 Pyramidal shape of trimethylamine
13.3 13.3 13.3 13.3 13.3 Nomenclature Nomenclature Nomenclature Nomenclature Nomenclature
2015-16
383 Amines
In arylamines, –NH
2
 group is directly attached to the benzene ring.
C
6
H
5
NH
2
 is the simplest example of arylamine.  In common system, it
is known as aniline. It is also an accepted IUPAC name. While naming
arylamines according to IUPAC system, suffix ‘e’ of arene is replaced by
‘amine’. Thus in IUPAC system, C
6
H
5
–NH
2
 is named as benzenamine.
Common and IUPAC names of some alkylamines and arylamines are
given in Table 13.1.
Amine Common name IUPAC name
CH
3-
–CH
2
–NH
2
Ethylamine Ethanamine
CH
3
–CH
2
–CH
2
–NH
2
n-Propylamine Propan-1-amine
Isopropylamine Propan-2-amine
Ethylmethylamine N-Methylethanamine
Trimethylamine N,N-Dimethylmethanamine
N,N-Diethylbutylamine N,N-Diethylbutan-1-amine
Allylamine Prop-2-en-1-amine
Hexamethylenediamine Hexane-1,6-diamine
Aniline Aniline or Benzenamine
o-Toluidine 2-Methylaniline
p-Bromoaniline 4-Bromobenzenamine
or
4-Bromoaniline
N,N-Dimethylaniline N,N-Dimethylbenzenamine
Table 13.1: Nomenclature of Some Alkylamines and Arylamines
2015-16
Page 4


Amines constitute an important class of organic
compounds derived by replacing one or more hydrogen
atoms of ammonia molecule by alkyl/aryl group(s). In
nature, they occur among proteins, vitamins, alkaloids
and hormones. Synthetic examples include polymers,
dyestuffs and drugs. Two biologically active compounds,
namely adrenaline and ephedrine, both containing
secondary amino group, are used to increase blood
pressure. Novocain, a synthetic amino compound, is
used as an anaesthetic in dentistry. Benadryl, a well
known antihistaminic drug also contains tertiary amino
group. Quaternary ammonium salts are used as
surfactants. Diazonium salts are intermediates in the
preparation of a  variety of aromatic compounds
including dyes. In this Unit, you will learn about amines
and diazonium salts.
I. AMINES
Amines can be considered as derivatives of ammonia,
obtained by replacement of one, two or all the three
hydrogen atoms by alkyl and/or aryl groups.
For example:
Like ammonia, nitrogen atom of amines is trivalent and
carries an unshared pair of electrons.  Nitrogen orbitals
in amines are therefore, sp
3
 hybridised and the geometry
of amines is pyramidal. Each of  the three sp
3
 hybridised
orbitals of nitrogen overlap with orbitals of hydrogen or
carbon depending upon the composition of the amines.
The fourth orbital of nitrogen in all amines contains an
unshared pair of electrons.  Due to the presence of
unshared pair of electrons, the angle C–N–E, (where E is
After studying this Unit, you will be
able to
• describe amines as derivatives of
ammonia having a pyramidal
structure;
• classify amines as primary,
secondary and tertiary;
• name amines by common names
and IUPAC system;
• describe some of the important
methods of preparation of amines;
• explain the properties of amines;
• distinguish between primary,
secondary and tertiary amines;
• describe the method of prepara-
tion of diazonium salts and their
importance in the synthesis of a
series of aromatic compounds
including azo dyes.
Objectives
“The chief commercial use of amines is as intermediates in the
synthesis of medicines and fibres” .
Unit Unit Unit Unit Unit
13
A A A A Amines mines mines mines mines
13
A A A A Amines mines mines mines mines
13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines
2015-16
382 Chemistry
C or H) is less than 109.5°; for instance, it is 108
o
 in case of
trimethylamine as shown in Fig. 13.1.
Amines are classified as primary (1
o
), secondary (2
o
) and tertiary (3
o
)
depending upon the number of hydrogen atoms replaced by alkyl or
aryl groups in ammonia molecule.  If one hydrogen atom of ammonia
is replaced by R or Ar , we get RNH
2 
or ArNH
2
, a primary amine (1
o
).
If two hydrogen atoms of ammonia or one hydrogen atom of R-NH
2
 are
replaced by another alkyl/aryl(R’) group,  what would you get? You
get R-NHR’, secondary amine.  The second alkyl/aryl group may be
same or different. Replacement of another hydrogen atom by alkyl/aryl
group leads to the formation of tertiary amine. Amines are said to be
‘simple’ when all the alkyl or aryl groups are the same, and ‘mixed’
when they are different.
In common system, an aliphatic amine is named by prefixing alkyl
group to amine, i.e., alkylamine as one word (e.g., methylamine).  In
secondary and tertiary amines, when two or more groups are the same,
the prefix di or tri is appended before the name of alkyl group.  In
IUPAC system, amines are named as alkanamines, derived by
replacement of ‘e’ of alkane by the word amine. For example, CH
3
NH
2
is named as methanamine. In case, more than one amino group is
present at different positions in the parent chain, their positions are
specified by giving numbers to the carbon atoms bearing –NH
2
 groups
and suitable prefix such as di, tri, etc. is attached to the amine. The
letter ‘e’ of the suffix of the hydrocarbon part is retained. For example,
H
2
N–CH
2
–CH
2
–NH
2
 is named as ethane-1, 2-diamine.
13.2 13.2 13.2 13.2 13.2 Classification Classification Classification Classification Classification
Fig. 13.1 Pyramidal shape of trimethylamine
13.3 13.3 13.3 13.3 13.3 Nomenclature Nomenclature Nomenclature Nomenclature Nomenclature
2015-16
383 Amines
In arylamines, –NH
2
 group is directly attached to the benzene ring.
C
6
H
5
NH
2
 is the simplest example of arylamine.  In common system, it
is known as aniline. It is also an accepted IUPAC name. While naming
arylamines according to IUPAC system, suffix ‘e’ of arene is replaced by
‘amine’. Thus in IUPAC system, C
6
H
5
–NH
2
 is named as benzenamine.
Common and IUPAC names of some alkylamines and arylamines are
given in Table 13.1.
Amine Common name IUPAC name
CH
3-
–CH
2
–NH
2
Ethylamine Ethanamine
CH
3
–CH
2
–CH
2
–NH
2
n-Propylamine Propan-1-amine
Isopropylamine Propan-2-amine
Ethylmethylamine N-Methylethanamine
Trimethylamine N,N-Dimethylmethanamine
N,N-Diethylbutylamine N,N-Diethylbutan-1-amine
Allylamine Prop-2-en-1-amine
Hexamethylenediamine Hexane-1,6-diamine
Aniline Aniline or Benzenamine
o-Toluidine 2-Methylaniline
p-Bromoaniline 4-Bromobenzenamine
or
4-Bromoaniline
N,N-Dimethylaniline N,N-Dimethylbenzenamine
Table 13.1: Nomenclature of Some Alkylamines and Arylamines
2015-16
384 Chemistry
Amines are prepared by the following methods:
1. Reduction of nitro compounds
Nitro compounds are reduced to amines by passing hydrogen gas
in the presence of finely divided nickel, palladium or platinum and
also by reduction with metals in acidic medium. Nitroalkanes can
also be similarly reduced to the corresponding alkanamines.
Reduction with iron scrap and hydrochloric acid is preferred because
FeCl
2
 formed gets hydrolysed to release hydrochloric acid during the
reaction. Thus, only a small amount of hydrochloric acid is required
to initiate the reaction.
2. Ammonolysis of alkyl halides
You have read (Unit 10, Class XII) that the carbon - halogen bond
in alkyl or benzyl halides can be easily cleaved by a nucleophile.
Hence, an alkyl or benzyl halide on reaction with an ethanolic
solution of ammonia undergoes nucleophilic substitution reaction
in which the halogen atom is replaced by an amino (–NH
2
) group.
This process of cleavage of the C–X bond by ammonia molecule is
known as ammonolysis.  The reaction is carried out in a sealed
tube at 373 K.  The primary amine thus obtained behaves as a
nucleophile and can further react with alkyl halide to form secondary
and tertiary amines, and finally quaternary ammonium salt.
13.4 13.4 13.4 13.4 13.4 Preparation Preparation Preparation Preparation Preparation
of Amines of Amines of Amines of Amines of Amines
13.1 Classify the following amines as primary, secondary or tertiary:
13.2 (i) Write structures of different isomeric amines corresponding to the molecular
formula, C
4
H
11
N.
(ii) Write IUPAC names of all the isomers.
(iii) What type of isomerism is exhibited by different pairs of amines?
Intext Questions Intext Questions Intext Questions Intext Questions Intext Questions
2015-16
Page 5


Amines constitute an important class of organic
compounds derived by replacing one or more hydrogen
atoms of ammonia molecule by alkyl/aryl group(s). In
nature, they occur among proteins, vitamins, alkaloids
and hormones. Synthetic examples include polymers,
dyestuffs and drugs. Two biologically active compounds,
namely adrenaline and ephedrine, both containing
secondary amino group, are used to increase blood
pressure. Novocain, a synthetic amino compound, is
used as an anaesthetic in dentistry. Benadryl, a well
known antihistaminic drug also contains tertiary amino
group. Quaternary ammonium salts are used as
surfactants. Diazonium salts are intermediates in the
preparation of a  variety of aromatic compounds
including dyes. In this Unit, you will learn about amines
and diazonium salts.
I. AMINES
Amines can be considered as derivatives of ammonia,
obtained by replacement of one, two or all the three
hydrogen atoms by alkyl and/or aryl groups.
For example:
Like ammonia, nitrogen atom of amines is trivalent and
carries an unshared pair of electrons.  Nitrogen orbitals
in amines are therefore, sp
3
 hybridised and the geometry
of amines is pyramidal. Each of  the three sp
3
 hybridised
orbitals of nitrogen overlap with orbitals of hydrogen or
carbon depending upon the composition of the amines.
The fourth orbital of nitrogen in all amines contains an
unshared pair of electrons.  Due to the presence of
unshared pair of electrons, the angle C–N–E, (where E is
After studying this Unit, you will be
able to
• describe amines as derivatives of
ammonia having a pyramidal
structure;
• classify amines as primary,
secondary and tertiary;
• name amines by common names
and IUPAC system;
• describe some of the important
methods of preparation of amines;
• explain the properties of amines;
• distinguish between primary,
secondary and tertiary amines;
• describe the method of prepara-
tion of diazonium salts and their
importance in the synthesis of a
series of aromatic compounds
including azo dyes.
Objectives
“The chief commercial use of amines is as intermediates in the
synthesis of medicines and fibres” .
Unit Unit Unit Unit Unit
13
A A A A Amines mines mines mines mines
13
A A A A Amines mines mines mines mines
13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines 13.1 Structure of Amines
2015-16
382 Chemistry
C or H) is less than 109.5°; for instance, it is 108
o
 in case of
trimethylamine as shown in Fig. 13.1.
Amines are classified as primary (1
o
), secondary (2
o
) and tertiary (3
o
)
depending upon the number of hydrogen atoms replaced by alkyl or
aryl groups in ammonia molecule.  If one hydrogen atom of ammonia
is replaced by R or Ar , we get RNH
2 
or ArNH
2
, a primary amine (1
o
).
If two hydrogen atoms of ammonia or one hydrogen atom of R-NH
2
 are
replaced by another alkyl/aryl(R’) group,  what would you get? You
get R-NHR’, secondary amine.  The second alkyl/aryl group may be
same or different. Replacement of another hydrogen atom by alkyl/aryl
group leads to the formation of tertiary amine. Amines are said to be
‘simple’ when all the alkyl or aryl groups are the same, and ‘mixed’
when they are different.
In common system, an aliphatic amine is named by prefixing alkyl
group to amine, i.e., alkylamine as one word (e.g., methylamine).  In
secondary and tertiary amines, when two or more groups are the same,
the prefix di or tri is appended before the name of alkyl group.  In
IUPAC system, amines are named as alkanamines, derived by
replacement of ‘e’ of alkane by the word amine. For example, CH
3
NH
2
is named as methanamine. In case, more than one amino group is
present at different positions in the parent chain, their positions are
specified by giving numbers to the carbon atoms bearing –NH
2
 groups
and suitable prefix such as di, tri, etc. is attached to the amine. The
letter ‘e’ of the suffix of the hydrocarbon part is retained. For example,
H
2
N–CH
2
–CH
2
–NH
2
 is named as ethane-1, 2-diamine.
13.2 13.2 13.2 13.2 13.2 Classification Classification Classification Classification Classification
Fig. 13.1 Pyramidal shape of trimethylamine
13.3 13.3 13.3 13.3 13.3 Nomenclature Nomenclature Nomenclature Nomenclature Nomenclature
2015-16
383 Amines
In arylamines, –NH
2
 group is directly attached to the benzene ring.
C
6
H
5
NH
2
 is the simplest example of arylamine.  In common system, it
is known as aniline. It is also an accepted IUPAC name. While naming
arylamines according to IUPAC system, suffix ‘e’ of arene is replaced by
‘amine’. Thus in IUPAC system, C
6
H
5
–NH
2
 is named as benzenamine.
Common and IUPAC names of some alkylamines and arylamines are
given in Table 13.1.
Amine Common name IUPAC name
CH
3-
–CH
2
–NH
2
Ethylamine Ethanamine
CH
3
–CH
2
–CH
2
–NH
2
n-Propylamine Propan-1-amine
Isopropylamine Propan-2-amine
Ethylmethylamine N-Methylethanamine
Trimethylamine N,N-Dimethylmethanamine
N,N-Diethylbutylamine N,N-Diethylbutan-1-amine
Allylamine Prop-2-en-1-amine
Hexamethylenediamine Hexane-1,6-diamine
Aniline Aniline or Benzenamine
o-Toluidine 2-Methylaniline
p-Bromoaniline 4-Bromobenzenamine
or
4-Bromoaniline
N,N-Dimethylaniline N,N-Dimethylbenzenamine
Table 13.1: Nomenclature of Some Alkylamines and Arylamines
2015-16
384 Chemistry
Amines are prepared by the following methods:
1. Reduction of nitro compounds
Nitro compounds are reduced to amines by passing hydrogen gas
in the presence of finely divided nickel, palladium or platinum and
also by reduction with metals in acidic medium. Nitroalkanes can
also be similarly reduced to the corresponding alkanamines.
Reduction with iron scrap and hydrochloric acid is preferred because
FeCl
2
 formed gets hydrolysed to release hydrochloric acid during the
reaction. Thus, only a small amount of hydrochloric acid is required
to initiate the reaction.
2. Ammonolysis of alkyl halides
You have read (Unit 10, Class XII) that the carbon - halogen bond
in alkyl or benzyl halides can be easily cleaved by a nucleophile.
Hence, an alkyl or benzyl halide on reaction with an ethanolic
solution of ammonia undergoes nucleophilic substitution reaction
in which the halogen atom is replaced by an amino (–NH
2
) group.
This process of cleavage of the C–X bond by ammonia molecule is
known as ammonolysis.  The reaction is carried out in a sealed
tube at 373 K.  The primary amine thus obtained behaves as a
nucleophile and can further react with alkyl halide to form secondary
and tertiary amines, and finally quaternary ammonium salt.
13.4 13.4 13.4 13.4 13.4 Preparation Preparation Preparation Preparation Preparation
of Amines of Amines of Amines of Amines of Amines
13.1 Classify the following amines as primary, secondary or tertiary:
13.2 (i) Write structures of different isomeric amines corresponding to the molecular
formula, C
4
H
11
N.
(ii) Write IUPAC names of all the isomers.
(iii) What type of isomerism is exhibited by different pairs of amines?
Intext Questions Intext Questions Intext Questions Intext Questions Intext Questions
2015-16
385 Amines
The free amine can be obtained from the ammonium salt by treatment
with a strong base:
Ammonolysis has the disadvantage of yielding a mixture of primary,
secondary and tertiary amines and also a quaternary ammonium salt.
However, primary amine is obtained as a major product by taking
large excess of ammonia.
The order of reactivity of halides with amines is RI > RBr >RCl.
3. Reduction of nitriles
Nitriles on reduction with lithium aluminium hydride (LiAlH
4
) or
catalytic hydrogenation produce primary amines. This reaction is
used for ascent of amine series, i.e., for preparation of amines
containing one carbon atom more than the starting amine.
4. Reduction of amides
The amides on reduction with lithium aluminium hydride yield
amines.
Example 13.1 Example 13.1 Example 13.1 Example 13.1 Example 13.1
Solution Solution Solution Solution Solution
Write chemical equations for the following reactions:
(i) Reaction of ethanolic NH
3
 with C
2
H
5
Cl.
(ii) Ammonolysis of benzyl chloride and reaction of amine so formed
with two moles of CH
3
Cl.
2015-16
Read More
3 videos|687 docs|659 tests

Top Courses for CTET & State TET

FAQs on NCERT Textbook - Amines - NCERT Textbooks (Class 6 to Class 12) - CTET & State TET

1. What are amines?
Ans. Amines are organic compounds derived from ammonia (NH3) by replacing one or more hydrogen atoms with alkyl or aryl groups. They are characterized by the presence of a nitrogen atom bonded to carbon atoms. Amines can be classified as primary, secondary, or tertiary, depending on the number of alkyl or aryl groups attached to the nitrogen atom.
2. How are amines prepared?
Ans. Amines can be prepared by various methods. Some common methods include: - Alkylation of ammonia: In this method, alkyl halides react with ammonia to form primary amines. Further alkylation of primary amines can lead to the formation of secondary and tertiary amines. - Reductive amination: This method involves the reaction of a carbonyl compound (aldehyde or ketone) with ammonia or a primary amine in the presence of a reducing agent, such as sodium cyanoborohydride. This results in the formation of primary or secondary amines, respectively. - Gabriel synthesis: This method involves the reaction of phthalimide with alkyl halides, followed by hydrolysis and decarboxylation to obtain primary amines.
3. What are the properties of amines?
Ans. Amines exhibit various properties based on their structure. Some important properties of amines include: - Basicity: Amines act as bases due to the presence of a lone pair of electrons on the nitrogen atom. They can accept a proton (H+) to form a positively charged ammonium ion. - Solubility: Small amines are soluble in water due to their ability to form hydrogen bonds with water molecules. However, the solubility decreases with increasing size of the alkyl or aryl groups attached to the nitrogen atom. - Odor: Amines often possess a strong and characteristic odor. For example, the odor of fish is due to the presence of certain amines like trimethylamine. - Boiling points: Amines have higher boiling points compared to hydrocarbons of similar molecular weight. This is because amines can form hydrogen bonds with each other, increasing the intermolecular forces.
4. What are some important uses of amines?
Ans. Amines find several applications in various fields. Some important uses of amines include: - Pharmaceuticals: Amines serve as building blocks for the synthesis of many pharmaceutical drugs. They can act as functional groups in drug molecules, contributing to their biological activity. - Dyes: Amines are used in the production of dyes and pigments. They can form colored complexes with metal ions, resulting in vibrant and long-lasting colors. - Rubber industry: Amines are used as accelerators in the vulcanization process of rubber. They help in improving the mechanical properties and stability of rubber products. - Corrosion inhibitors: Certain amines are employed as corrosion inhibitors in various industries, including oil and gas, to protect metal surfaces from corrosion.
5. What are the potential health hazards associated with amines?
Ans. Amines, especially aromatic amines, can pose health hazards under certain conditions. Some potential health hazards associated with amines include: - Skin and eye irritation: Direct contact with certain amines can cause skin and eye irritation. It is important to handle amines with care and use appropriate protective measures. - Toxicity: Some amines, such as aromatic amines, can be toxic and may cause adverse effects on human health. Prolonged exposure to high concentrations of aromatic amines has been linked to the development of cancer. - Sensitization: Certain individuals may develop allergies or sensitization to specific amines, leading to allergic reactions upon exposure. It is crucial to follow safety guidelines and handle amines responsibly to minimize any potential health risks.
3 videos|687 docs|659 tests
Download as PDF
Explore Courses for CTET & State TET exam

Top Courses for CTET & State TET

Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Related Searches

Objective type Questions

,

MCQs

,

NCERT Textbook - Amines | NCERT Textbooks (Class 6 to Class 12) - CTET & State TET

,

Semester Notes

,

mock tests for examination

,

past year papers

,

video lectures

,

Sample Paper

,

Exam

,

Summary

,

Extra Questions

,

study material

,

Important questions

,

Free

,

pdf

,

NCERT Textbook - Amines | NCERT Textbooks (Class 6 to Class 12) - CTET & State TET

,

ppt

,

NCERT Textbook - Amines | NCERT Textbooks (Class 6 to Class 12) - CTET & State TET

,

Previous Year Questions with Solutions

,

Viva Questions

,

shortcuts and tricks

,

practice quizzes

;