NCERT Textbook: Alcohols, Phenols and Ethers | NCERT Textbooks (Class 6 to Class 12) - CTET & State TET PDF Download

 Page 1


After studying this Unit, you will be
able to
• name alcohols, phenols and
ethers according to the IUPAC
system of nomenclature;
• discuss the reactions involved in
the preparation of alcohols from
(i) alkenes (ii) aldehydes, ketones
and carboxylic acids;
• discuss the reactions involved in
the preparation of phenols from
(i) haloarenes (ii) benzene
sulphonic acids (iii) diazonium
salts and (iv) cumene;
• discuss the reactions for
preparation of ethers from
(i) alcohols and (ii) alkyl halides
and sodium alkoxides/aryloxides;
• correlate physical properties of
alcohols, phenols and ethers with
their structures;
• discuss chemical reactions of the
three classes of compounds on
the basis of their functional
groups.
Objectives
Alcohols, phenols and ethers are the basic compounds for the
formation of detergents, antiseptics and fragrances, respectively.
11
Unit Unit Unit Unit Unit
11
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers s s s s
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers ss ss
You have learnt that substitution of one or more
hydrogen atom(s) from a hydrocarbon by another atom
or a group of atoms result in the formation of an entirely
new compound having altogether different properties
and applications. Alcohols and phenols are formed
when a hydrogen atom in a hydrocarbon, aliphatic and
aromatic respectively, is replaced by –OH group. These
classes of compounds find wide applications in industry
as well as in day-to-day life. For instance, have you
ever noticed that ordinary spirit used for polishing
wooden furniture is chiefly a compound containing
hydroxyl group, ethanol. The sugar we eat, the cotton
used for fabrics, the paper we use for writing, are all
made up of compounds containing –OH groups. Just
think of life without paper; no note-books, books, news-
papers, currency notes, cheques, certificates, etc. The
magazines carrying beautiful photographs and
interesting stories would disappear from our life. It
would have been really a different world.
An alcohol contains one or more hydroxyl (OH)
group(s) directly attached to carbon atom(s), of an
aliphatic system (CH
3
OH) while a phenol contains –OH
group(s) directly attached to carbon atom(s) of an
aromatic system (C
6
H
5
OH).
The subsitution of a hydrogen atom in a
hydrocarbon by an alkoxy or aryloxy group
(R–O/Ar–O) yields another class of compounds known
as ‘ethers’, for example, CH
3
OCH
3
 (dimethyl ether). You
may also visualise ethers as compounds formed by
2015-16
Page 2


After studying this Unit, you will be
able to
• name alcohols, phenols and
ethers according to the IUPAC
system of nomenclature;
• discuss the reactions involved in
the preparation of alcohols from
(i) alkenes (ii) aldehydes, ketones
and carboxylic acids;
• discuss the reactions involved in
the preparation of phenols from
(i) haloarenes (ii) benzene
sulphonic acids (iii) diazonium
salts and (iv) cumene;
• discuss the reactions for
preparation of ethers from
(i) alcohols and (ii) alkyl halides
and sodium alkoxides/aryloxides;
• correlate physical properties of
alcohols, phenols and ethers with
their structures;
• discuss chemical reactions of the
three classes of compounds on
the basis of their functional
groups.
Objectives
Alcohols, phenols and ethers are the basic compounds for the
formation of detergents, antiseptics and fragrances, respectively.
11
Unit Unit Unit Unit Unit
11
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers s s s s
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers ss ss
You have learnt that substitution of one or more
hydrogen atom(s) from a hydrocarbon by another atom
or a group of atoms result in the formation of an entirely
new compound having altogether different properties
and applications. Alcohols and phenols are formed
when a hydrogen atom in a hydrocarbon, aliphatic and
aromatic respectively, is replaced by –OH group. These
classes of compounds find wide applications in industry
as well as in day-to-day life. For instance, have you
ever noticed that ordinary spirit used for polishing
wooden furniture is chiefly a compound containing
hydroxyl group, ethanol. The sugar we eat, the cotton
used for fabrics, the paper we use for writing, are all
made up of compounds containing –OH groups. Just
think of life without paper; no note-books, books, news-
papers, currency notes, cheques, certificates, etc. The
magazines carrying beautiful photographs and
interesting stories would disappear from our life. It
would have been really a different world.
An alcohol contains one or more hydroxyl (OH)
group(s) directly attached to carbon atom(s), of an
aliphatic system (CH
3
OH) while a phenol contains –OH
group(s) directly attached to carbon atom(s) of an
aromatic system (C
6
H
5
OH).
The subsitution of a hydrogen atom in a
hydrocarbon by an alkoxy or aryloxy group
(R–O/Ar–O) yields another class of compounds known
as ‘ethers’, for example, CH
3
OCH
3
 (dimethyl ether). You
may also visualise ethers as compounds formed by
2015-16
316 Chemistry
The classification of compounds makes their study systematic and
hence simpler. Therefore, let us first learn how are alcohols, phenols
and ethers classified?
Alcohols and phenols may be classified as mono–, di–, tri- or
polyhydric compounds depending on whether they contain one, two,
three or many hydroxyl groups respectively in their structures as
given below:
substituting the hydrogen atom of hydroxyl group of an alcohol or
phenol by an alkyl or aryl group.
In this unit, we shall discuss the chemistry of three classes of
compounds, namely — alcohols, phenols and ethers.
11.1 11.1 11.1 11.1 11.1 Classification Classification Classification Classification Classification
11.1.1 Mono, Di,
Tri or
Polyhydric
Compounds
Monohydric alcohols may be further classified according to the
hybridisation of the carbon atom to which the hydroxyl group is
attached.
(i) Compounds containing 3 C OH -
sp
bond: In this class of alcohols,
the –OH group is attached to an sp
3
 hybridised carbon atom of an
alkyl group. They are further classified as follows:
Primary, secondary and tertiary alcohols: In these three types of
alcohols, the –OH group is attached to primary, secondary and
tertiary carbon atom, respectively as depicted below:
Allylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
 hybridised carbon next to the carbon-carbon double bond,
that is to an allylic carbon. For example
2015-16
Page 3


After studying this Unit, you will be
able to
• name alcohols, phenols and
ethers according to the IUPAC
system of nomenclature;
• discuss the reactions involved in
the preparation of alcohols from
(i) alkenes (ii) aldehydes, ketones
and carboxylic acids;
• discuss the reactions involved in
the preparation of phenols from
(i) haloarenes (ii) benzene
sulphonic acids (iii) diazonium
salts and (iv) cumene;
• discuss the reactions for
preparation of ethers from
(i) alcohols and (ii) alkyl halides
and sodium alkoxides/aryloxides;
• correlate physical properties of
alcohols, phenols and ethers with
their structures;
• discuss chemical reactions of the
three classes of compounds on
the basis of their functional
groups.
Objectives
Alcohols, phenols and ethers are the basic compounds for the
formation of detergents, antiseptics and fragrances, respectively.
11
Unit Unit Unit Unit Unit
11
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers s s s s
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers ss ss
You have learnt that substitution of one or more
hydrogen atom(s) from a hydrocarbon by another atom
or a group of atoms result in the formation of an entirely
new compound having altogether different properties
and applications. Alcohols and phenols are formed
when a hydrogen atom in a hydrocarbon, aliphatic and
aromatic respectively, is replaced by –OH group. These
classes of compounds find wide applications in industry
as well as in day-to-day life. For instance, have you
ever noticed that ordinary spirit used for polishing
wooden furniture is chiefly a compound containing
hydroxyl group, ethanol. The sugar we eat, the cotton
used for fabrics, the paper we use for writing, are all
made up of compounds containing –OH groups. Just
think of life without paper; no note-books, books, news-
papers, currency notes, cheques, certificates, etc. The
magazines carrying beautiful photographs and
interesting stories would disappear from our life. It
would have been really a different world.
An alcohol contains one or more hydroxyl (OH)
group(s) directly attached to carbon atom(s), of an
aliphatic system (CH
3
OH) while a phenol contains –OH
group(s) directly attached to carbon atom(s) of an
aromatic system (C
6
H
5
OH).
The subsitution of a hydrogen atom in a
hydrocarbon by an alkoxy or aryloxy group
(R–O/Ar–O) yields another class of compounds known
as ‘ethers’, for example, CH
3
OCH
3
 (dimethyl ether). You
may also visualise ethers as compounds formed by
2015-16
316 Chemistry
The classification of compounds makes their study systematic and
hence simpler. Therefore, let us first learn how are alcohols, phenols
and ethers classified?
Alcohols and phenols may be classified as mono–, di–, tri- or
polyhydric compounds depending on whether they contain one, two,
three or many hydroxyl groups respectively in their structures as
given below:
substituting the hydrogen atom of hydroxyl group of an alcohol or
phenol by an alkyl or aryl group.
In this unit, we shall discuss the chemistry of three classes of
compounds, namely — alcohols, phenols and ethers.
11.1 11.1 11.1 11.1 11.1 Classification Classification Classification Classification Classification
11.1.1 Mono, Di,
Tri or
Polyhydric
Compounds
Monohydric alcohols may be further classified according to the
hybridisation of the carbon atom to which the hydroxyl group is
attached.
(i) Compounds containing 3 C OH -
sp
bond: In this class of alcohols,
the –OH group is attached to an sp
3
 hybridised carbon atom of an
alkyl group. They are further classified as follows:
Primary, secondary and tertiary alcohols: In these three types of
alcohols, the –OH group is attached to primary, secondary and
tertiary carbon atom, respectively as depicted below:
Allylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
 hybridised carbon next to the carbon-carbon double bond,
that is to an allylic carbon. For example
2015-16
317 Alcohols, Phenols and Ethers
Allylic and benzylic alcohols may be primary, secondary or tertiary.
(ii) Compounds containing 2 C OH -
sp
 bond: These alcohols contain
—OH group bonded to a carbon-carbon double bond i.e., to a
vinylic carbon or to an aryl carbon. These alcohols are also known
as vinylic alcohols.
Vinylic alcohol: CH
2
 = CH – OH
Phenols: 
Ethers are classified as simple or symmetrical, if the alkyl or aryl
groups attached to the oxygen atom are the same, and mixed or
unsymmetrical, if the two groups are different. Diethyl ether,
C
2
H
5
OC
2
H
5
, is a symmetrical ether whereas C
2
H
5
OCH
3
 and C
2
H
5
OC
6
H
5
are unsymmetrical ethers.
11.1.2 Ethers
CH
3
C CH OH
2
CH
3
CH
3
(i) H C
2
CH CH OH
2
(ii)
CH
3
CH
2
CH OH
2
(iii)
CH
OH
CH
3
(iv)
CH
2
OH
CH CH
3
(v)
CH
OH CH C
CH
3
CH
3
(vi)
11.1 Classify the following as primary, secondary and tertiary alcohols:
11.2 Identify allylic alcohols in the above examples.
Intext Questions Intext Questions Intext Questions Intext Questions Intext Questions
11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature (a) Alcohols: The common name of an alcohol is derived from the
common name of the alkyl group and adding the word alcohol to it.
For example, CH
3
OH is methyl alcohol.
Benzylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
—hybridised carbon atom next to an aromatic ring. For example
2015-16
Page 4


After studying this Unit, you will be
able to
• name alcohols, phenols and
ethers according to the IUPAC
system of nomenclature;
• discuss the reactions involved in
the preparation of alcohols from
(i) alkenes (ii) aldehydes, ketones
and carboxylic acids;
• discuss the reactions involved in
the preparation of phenols from
(i) haloarenes (ii) benzene
sulphonic acids (iii) diazonium
salts and (iv) cumene;
• discuss the reactions for
preparation of ethers from
(i) alcohols and (ii) alkyl halides
and sodium alkoxides/aryloxides;
• correlate physical properties of
alcohols, phenols and ethers with
their structures;
• discuss chemical reactions of the
three classes of compounds on
the basis of their functional
groups.
Objectives
Alcohols, phenols and ethers are the basic compounds for the
formation of detergents, antiseptics and fragrances, respectively.
11
Unit Unit Unit Unit Unit
11
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers s s s s
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers ss ss
You have learnt that substitution of one or more
hydrogen atom(s) from a hydrocarbon by another atom
or a group of atoms result in the formation of an entirely
new compound having altogether different properties
and applications. Alcohols and phenols are formed
when a hydrogen atom in a hydrocarbon, aliphatic and
aromatic respectively, is replaced by –OH group. These
classes of compounds find wide applications in industry
as well as in day-to-day life. For instance, have you
ever noticed that ordinary spirit used for polishing
wooden furniture is chiefly a compound containing
hydroxyl group, ethanol. The sugar we eat, the cotton
used for fabrics, the paper we use for writing, are all
made up of compounds containing –OH groups. Just
think of life without paper; no note-books, books, news-
papers, currency notes, cheques, certificates, etc. The
magazines carrying beautiful photographs and
interesting stories would disappear from our life. It
would have been really a different world.
An alcohol contains one or more hydroxyl (OH)
group(s) directly attached to carbon atom(s), of an
aliphatic system (CH
3
OH) while a phenol contains –OH
group(s) directly attached to carbon atom(s) of an
aromatic system (C
6
H
5
OH).
The subsitution of a hydrogen atom in a
hydrocarbon by an alkoxy or aryloxy group
(R–O/Ar–O) yields another class of compounds known
as ‘ethers’, for example, CH
3
OCH
3
 (dimethyl ether). You
may also visualise ethers as compounds formed by
2015-16
316 Chemistry
The classification of compounds makes their study systematic and
hence simpler. Therefore, let us first learn how are alcohols, phenols
and ethers classified?
Alcohols and phenols may be classified as mono–, di–, tri- or
polyhydric compounds depending on whether they contain one, two,
three or many hydroxyl groups respectively in their structures as
given below:
substituting the hydrogen atom of hydroxyl group of an alcohol or
phenol by an alkyl or aryl group.
In this unit, we shall discuss the chemistry of three classes of
compounds, namely — alcohols, phenols and ethers.
11.1 11.1 11.1 11.1 11.1 Classification Classification Classification Classification Classification
11.1.1 Mono, Di,
Tri or
Polyhydric
Compounds
Monohydric alcohols may be further classified according to the
hybridisation of the carbon atom to which the hydroxyl group is
attached.
(i) Compounds containing 3 C OH -
sp
bond: In this class of alcohols,
the –OH group is attached to an sp
3
 hybridised carbon atom of an
alkyl group. They are further classified as follows:
Primary, secondary and tertiary alcohols: In these three types of
alcohols, the –OH group is attached to primary, secondary and
tertiary carbon atom, respectively as depicted below:
Allylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
 hybridised carbon next to the carbon-carbon double bond,
that is to an allylic carbon. For example
2015-16
317 Alcohols, Phenols and Ethers
Allylic and benzylic alcohols may be primary, secondary or tertiary.
(ii) Compounds containing 2 C OH -
sp
 bond: These alcohols contain
—OH group bonded to a carbon-carbon double bond i.e., to a
vinylic carbon or to an aryl carbon. These alcohols are also known
as vinylic alcohols.
Vinylic alcohol: CH
2
 = CH – OH
Phenols: 
Ethers are classified as simple or symmetrical, if the alkyl or aryl
groups attached to the oxygen atom are the same, and mixed or
unsymmetrical, if the two groups are different. Diethyl ether,
C
2
H
5
OC
2
H
5
, is a symmetrical ether whereas C
2
H
5
OCH
3
 and C
2
H
5
OC
6
H
5
are unsymmetrical ethers.
11.1.2 Ethers
CH
3
C CH OH
2
CH
3
CH
3
(i) H C
2
CH CH OH
2
(ii)
CH
3
CH
2
CH OH
2
(iii)
CH
OH
CH
3
(iv)
CH
2
OH
CH CH
3
(v)
CH
OH CH C
CH
3
CH
3
(vi)
11.1 Classify the following as primary, secondary and tertiary alcohols:
11.2 Identify allylic alcohols in the above examples.
Intext Questions Intext Questions Intext Questions Intext Questions Intext Questions
11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature (a) Alcohols: The common name of an alcohol is derived from the
common name of the alkyl group and adding the word alcohol to it.
For example, CH
3
OH is methyl alcohol.
Benzylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
—hybridised carbon atom next to an aromatic ring. For example
2015-16
318 Chemistry
According to IUPAC system (Unit 12, Class XI), the name of an alcohol
is derived from the name of the alkane from which the alcohol is derived,
by substituting ‘e’ of alkane with the suffix ‘ol’. The position of
substituents are indicated by numerals. For this, the longest carbon
chain (parent chain) is numbered starting at the end nearest to the
hydroxyl group. The positions of the –OH group and other substituents
are indicated by using the numbers of carbon atoms to which these are
attached. For naming polyhydric alcohols, the ‘e’ of alkane is retained
and the ending ‘ol’ is added. The number of –OH groups is indicated by
adding the multiplicative prefix, di, tri, etc., before ‘ol’. The positions of
–OH groups are indicated by appropriate locants e.g., HO–CH
2
–CH
2
–OH
is named as ethane–1, 2-diol. Table 11.1 gives common and IUPAC
names of a few alcohols as examples.
Table 11.1: Common and IUPAC Names of Some Alcohols
CH3 – OH Methyl alcohol Methanol
CH
3 
– CH
2 
– CH
2 
– OH n-Propyl alcohol Propan-1-ol
Isopropyl alcohol Propan-2-ol
CH
3 
– CH
2 
– CH
2 
– CH
2 
– OH n-Butyl alcohol Butan-1-ol
sec-Butyl alcohol Butan-2-ol
Isobutyl alcohol 2-Methylpropan-1-ol
tert-Butyl alcohol 2-Methylpropan-2-ol
Glycerol Propane -1, 2, 3-triol
Compound Common name IUPAC name
Cyclic alcohols are named using the prefix cyclo and considering
the —OH group attached to C–1.
OH
OH
CH
3
Cyclohexanol 2-Methylcyclopentanol
(b) Phenols: The simplest hydroxy derivative of benzene is phenol.
It is its common name and also an accepted IUPAC name. As structure
of phenol involves a benzene ring, in its substituted compounds the
terms ortho (1,2- disubstituted), meta (1,3-disubstituted) and para
(1,4-disubstituted) are often used in the common names.
2015-16
Page 5


After studying this Unit, you will be
able to
• name alcohols, phenols and
ethers according to the IUPAC
system of nomenclature;
• discuss the reactions involved in
the preparation of alcohols from
(i) alkenes (ii) aldehydes, ketones
and carboxylic acids;
• discuss the reactions involved in
the preparation of phenols from
(i) haloarenes (ii) benzene
sulphonic acids (iii) diazonium
salts and (iv) cumene;
• discuss the reactions for
preparation of ethers from
(i) alcohols and (ii) alkyl halides
and sodium alkoxides/aryloxides;
• correlate physical properties of
alcohols, phenols and ethers with
their structures;
• discuss chemical reactions of the
three classes of compounds on
the basis of their functional
groups.
Objectives
Alcohols, phenols and ethers are the basic compounds for the
formation of detergents, antiseptics and fragrances, respectively.
11
Unit Unit Unit Unit Unit
11
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers s s s s
Alcohols Alcohols Alcohols Alcohols Alcohols, Phenols , Phenols , Phenols , Phenols , Phenols
and E and E and E and E and Ether ther ther ther thers ss ss
You have learnt that substitution of one or more
hydrogen atom(s) from a hydrocarbon by another atom
or a group of atoms result in the formation of an entirely
new compound having altogether different properties
and applications. Alcohols and phenols are formed
when a hydrogen atom in a hydrocarbon, aliphatic and
aromatic respectively, is replaced by –OH group. These
classes of compounds find wide applications in industry
as well as in day-to-day life. For instance, have you
ever noticed that ordinary spirit used for polishing
wooden furniture is chiefly a compound containing
hydroxyl group, ethanol. The sugar we eat, the cotton
used for fabrics, the paper we use for writing, are all
made up of compounds containing –OH groups. Just
think of life without paper; no note-books, books, news-
papers, currency notes, cheques, certificates, etc. The
magazines carrying beautiful photographs and
interesting stories would disappear from our life. It
would have been really a different world.
An alcohol contains one or more hydroxyl (OH)
group(s) directly attached to carbon atom(s), of an
aliphatic system (CH
3
OH) while a phenol contains –OH
group(s) directly attached to carbon atom(s) of an
aromatic system (C
6
H
5
OH).
The subsitution of a hydrogen atom in a
hydrocarbon by an alkoxy or aryloxy group
(R–O/Ar–O) yields another class of compounds known
as ‘ethers’, for example, CH
3
OCH
3
 (dimethyl ether). You
may also visualise ethers as compounds formed by
2015-16
316 Chemistry
The classification of compounds makes their study systematic and
hence simpler. Therefore, let us first learn how are alcohols, phenols
and ethers classified?
Alcohols and phenols may be classified as mono–, di–, tri- or
polyhydric compounds depending on whether they contain one, two,
three or many hydroxyl groups respectively in their structures as
given below:
substituting the hydrogen atom of hydroxyl group of an alcohol or
phenol by an alkyl or aryl group.
In this unit, we shall discuss the chemistry of three classes of
compounds, namely — alcohols, phenols and ethers.
11.1 11.1 11.1 11.1 11.1 Classification Classification Classification Classification Classification
11.1.1 Mono, Di,
Tri or
Polyhydric
Compounds
Monohydric alcohols may be further classified according to the
hybridisation of the carbon atom to which the hydroxyl group is
attached.
(i) Compounds containing 3 C OH -
sp
bond: In this class of alcohols,
the –OH group is attached to an sp
3
 hybridised carbon atom of an
alkyl group. They are further classified as follows:
Primary, secondary and tertiary alcohols: In these three types of
alcohols, the –OH group is attached to primary, secondary and
tertiary carbon atom, respectively as depicted below:
Allylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
 hybridised carbon next to the carbon-carbon double bond,
that is to an allylic carbon. For example
2015-16
317 Alcohols, Phenols and Ethers
Allylic and benzylic alcohols may be primary, secondary or tertiary.
(ii) Compounds containing 2 C OH -
sp
 bond: These alcohols contain
—OH group bonded to a carbon-carbon double bond i.e., to a
vinylic carbon or to an aryl carbon. These alcohols are also known
as vinylic alcohols.
Vinylic alcohol: CH
2
 = CH – OH
Phenols: 
Ethers are classified as simple or symmetrical, if the alkyl or aryl
groups attached to the oxygen atom are the same, and mixed or
unsymmetrical, if the two groups are different. Diethyl ether,
C
2
H
5
OC
2
H
5
, is a symmetrical ether whereas C
2
H
5
OCH
3
 and C
2
H
5
OC
6
H
5
are unsymmetrical ethers.
11.1.2 Ethers
CH
3
C CH OH
2
CH
3
CH
3
(i) H C
2
CH CH OH
2
(ii)
CH
3
CH
2
CH OH
2
(iii)
CH
OH
CH
3
(iv)
CH
2
OH
CH CH
3
(v)
CH
OH CH C
CH
3
CH
3
(vi)
11.1 Classify the following as primary, secondary and tertiary alcohols:
11.2 Identify allylic alcohols in the above examples.
Intext Questions Intext Questions Intext Questions Intext Questions Intext Questions
11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature 11.2 Nomenclature (a) Alcohols: The common name of an alcohol is derived from the
common name of the alkyl group and adding the word alcohol to it.
For example, CH
3
OH is methyl alcohol.
Benzylic alcohols: In these alcohols, the —OH group is attached to
a sp
3
—hybridised carbon atom next to an aromatic ring. For example
2015-16
318 Chemistry
According to IUPAC system (Unit 12, Class XI), the name of an alcohol
is derived from the name of the alkane from which the alcohol is derived,
by substituting ‘e’ of alkane with the suffix ‘ol’. The position of
substituents are indicated by numerals. For this, the longest carbon
chain (parent chain) is numbered starting at the end nearest to the
hydroxyl group. The positions of the –OH group and other substituents
are indicated by using the numbers of carbon atoms to which these are
attached. For naming polyhydric alcohols, the ‘e’ of alkane is retained
and the ending ‘ol’ is added. The number of –OH groups is indicated by
adding the multiplicative prefix, di, tri, etc., before ‘ol’. The positions of
–OH groups are indicated by appropriate locants e.g., HO–CH
2
–CH
2
–OH
is named as ethane–1, 2-diol. Table 11.1 gives common and IUPAC
names of a few alcohols as examples.
Table 11.1: Common and IUPAC Names of Some Alcohols
CH3 – OH Methyl alcohol Methanol
CH
3 
– CH
2 
– CH
2 
– OH n-Propyl alcohol Propan-1-ol
Isopropyl alcohol Propan-2-ol
CH
3 
– CH
2 
– CH
2 
– CH
2 
– OH n-Butyl alcohol Butan-1-ol
sec-Butyl alcohol Butan-2-ol
Isobutyl alcohol 2-Methylpropan-1-ol
tert-Butyl alcohol 2-Methylpropan-2-ol
Glycerol Propane -1, 2, 3-triol
Compound Common name IUPAC name
Cyclic alcohols are named using the prefix cyclo and considering
the —OH group attached to C–1.
OH
OH
CH
3
Cyclohexanol 2-Methylcyclopentanol
(b) Phenols: The simplest hydroxy derivative of benzene is phenol.
It is its common name and also an accepted IUPAC name. As structure
of phenol involves a benzene ring, in its substituted compounds the
terms ortho (1,2- disubstituted), meta (1,3-disubstituted) and para
(1,4-disubstituted) are often used in the common names.
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319 Alcohols, Phenols and Ethers
Common name Phenol o-Cresol m-Cresol p-Cresol
IUPAC name Phenol 2-Methylphenol 3-Methylphenol 4-Methylphenol
Dihydroxy derivatives of benzene are known as 1, 2-, 1, 3- and
1, 4-benzenediol.
OH CH
3
OH
CH
3
OH
CH
3
OH
OH
OH
OH
OH
OH
OH
Common name Catechol
Benzene- diol 1,2-
Resorcinol
Benzene- diol 1,3-
Hydroquinone or quinol
Benzene- diol 1,4- IUPAC name
(c) Ethers: Common names of ethers are derived from the names of alkyl/
aryl groups written as separate words in alphabetical order and adding the
word ‘ether’ at the end. For example, CH
3
OC
2
H
5
 is ethylmethyl ether.
Table 11.2: Common and IUPAC Names of Some Ethers
Compound Common name IUPAC name
CH 3OCH 3 Dimethyl ether Methoxymethane
C
2
H
5
OC
2
H
5
Diethyl ether Ethoxyethane
CH3OCH2CH2CH3 Methyl n-propyl ether 1-Methoxypropane
C
6
H
5
OCH
3
Methyl phenyl ether Methoxybenzene
(Anisole) (Anisole)
C6H5OCH2CH3 Ethyl phenyl ether Ethoxybenzene
(Phenetole)
C6H5O(CH2)6 – CH3 Heptyl phenyl ether 1-Phenoxyheptane
CH
3
CH O
3
CH
CH
3
Methyl isopropyl ether 2-Methoxypropane
Phenyl isopentyl ether 3- Methylbutoxybenzene
CH
3
– O – CH
2 
– CH
2
 – OCH
3
— 1,2-Dimethoxyethane
—
2-Ethoxy-
-1,1-dimethylcyclohexane
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