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Unit

11
Objectives
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
...


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
...
These
classes of compounds find wide applications in industry
as well as in day-to-day life
...
The sugar we eat, the cotton
used for fabrics, the paper we use for writing, are all
made up of compounds containing –OH groups
...
The
magazines carrying beautiful photographs and
interesting stories would disappear from our life
...

An alcohol contains one or more hydroxyl (OH)
group(s) directly attached to carbon atom(s), of an
aliphatic system (CH3OH) while a phenol contains –OH
group(s) directly attached to carbon atom(s) of an
aromatic system (C6H5OH)
...
You
may also visualise ethers as compounds formed by

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substituting the hydrogen atom of hydroxyl group of an alcohol or
phenol by an alkyl or aryl group
...


11
...
Therefore, let us first learn how are alcohols, phenols
and ethers classified?

11
...
1 Mono, Di,
Tri or
Polyhydric
Compounds

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:

Monohydric alcohols may be further classified according to the
hybridisation of the carbon atom to which the hydroxyl group is
attached
...
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
3
a sp hybridised carbon next to the carbon-carbon double bond,
that is to an allylic carbon
...
For example

Allylic and benzylic alcohols may be primary, secondary or tertiary
...
e
...
These alcohols are also known
as vinylic alcohols
...
1
...
Diethyl ether,
C2H5OC2H5, is a symmetrical ether whereas C2H 5OCH3 and C2H5OC6H5
are unsymmetrical ethers
...
1

Classify the following as primary, secondary and tertiary alcohols:
CH3
(i) CH3

CH2OH

C

(ii) H2C

CH3

CH

CH2OH

OH
CH CH3

(iii) CH3

CH2 CH2 OH

(iv)
CH3

(v)
11
...


11
...

For example, CH3OH is methyl alcohol
...
The position of
substituents are indicated by numerals
...
The positions of the –OH group and other substituents
are indicated by using the numbers of carbon atoms to which these are
attached
...
The number of –OH groups is indicated by
adding the multiplicative prefix, di, tri, etc
...
The positions of
–OH groups are indicated by appropriate locants e
...
, HO–CH2–CH2–OH
is named as ethane–1, 2-diol
...
1 gives common and IUPAC
names of a few alcohols as examples
...
1: Common and IUPAC Names of Some Alcohols
Compound
CH3 – OH
CH3 – CH2 – CH2 – OH

CH3 – CH2 – CH2 – CH2 – OH

Common name

IUPAC name

Methyl alcohol
n-Propyl alcohol

Methanol
Propan-1-ol

Isopropyl alcohol

Propan-2-ol

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

Cyclic alcohols are named using the prefix cyclo and considering
the —OH group attached to C–1
...

It is its common name and also an accepted IUPAC name
...

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OH

CH3

CH3

CH3

OH
OH
OH
Common name
IUPAC name

Phenol
Phenol

o-Cresol
2-Methylphenol

m-Cresol
3-Methylphenol

p-Cresol
4-Methylphenol

Dihydroxy derivatives of benzene are known as 1, 2-, 1, 3- and
1, 4-benzenediol
...
For example, CH3OC2H5 is ethylmethyl ether
...
2: Common and IUPAC Names of Some Ethers
Compound

Common name

IUPAC name

CH3OCH3

Dimethyl ether

Methoxymethane

C2 H5OC2H5

Diethyl ether

Ethoxyethane

CH3OCH2 CH2 CH3

Methyl n-propyl ether

1-Methoxypropane

C6 H5OCH3

Methyl phenyl ether
(Anisole)

Methoxybenzene
(Anisole)

C6 H5 OCH2CH3

Ethyl phenyl ether
(Phenetole)

Ethoxybenzene

C6 H5 O(CH2 )6 – CH3

Heptyl phenyl ether

1-Phenoxyheptane

CH3O CH

Methyl isopropyl ether

2-Methoxypropane

Phenyl isopentyl ether

3- Methylbutoxybenzene

CH3

CH3

CH3– O – CH2 – CH2 – OCH3

—

1,2-Dimethoxyethane

—

2-Ethoxy-1,1-dimethylcyclohexane

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If both the alkyl groups are the same, the prefix ‘di’ is added before the alkyl
group
...

According to IUPAC system of nomenclature, ethers are regarded as
hydrocarbon derivatives in which a hydrogen atom is replaced by an
–OR or –OAr group, where R and Ar represent alkyl and aryl groups,
respectively
...

The names of a few ethers are given as examples in Table 11
...


Example 11
...
3 Name the following compounds according to IUPAC system
...
3 Structures of
Functional
Groups

(ii)

(iv)

(v)

In alcohols, the oxygen of the –OH group is attached to carbon by a
3
sigma (σ ) bond formed by the overlap of a sp hybridised orbital of
3
carbon with a sp hybridised orbital of oxygen
...
11
...


Fig
...
1: Structures of methanol, phenol and methoxymethane
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The bond angle

in alcohols is slightly less than the tetrahedral

angle (109°-28′)
...
In phenols, the –OH group is attached to sp2
hybridised carbon of an aromatic ring
...
This
is due to (i) partial double bond character on account of the conjugation
of unshared electron pair of oxygen with the aromatic ring (Section
11
...
4) and (ii) sp2 hybridised state of carbon to which oxygen is
attached
...
e
...
The bond angle is slightly greater than the
tetrahedral angle due to the repulsive interaction between the two
bulky (–R) groups
...


11
...
4
...
From alkenes
(i) By acid catalysed hydration: Alkenes react with water in the
presence of acid as catalyst to form alcohols
...


Mechanism
The mechanism of the reaction involves the following three steps:
Step 1: Protonation of alkene to form carbocation by electrophilic
attack of H3O+
...


Step 3: Deprotonation to form an alcohol
...
C
...
For
his studies on boron
containing organic
compounds, Brown
shared the 1979 Nobel
prize in Chemistry
with G
...


(ii) By hydroboration–oxidation: Diborane (BH3)2 reacts with alkenes
to give trialkyl boranes as addition product
...


The addition of borane to the double bond takes place in such
2
a manner that the boron atom gets attached to the sp carbon
carrying greater number of hydrogen atoms
...
In this reaction,
alcohol is obtained in excellent yield
...
From carbonyl compounds
(i) By reduction of aldehydes and ketones: Aldehydes and ketones
are reduced to the corresponding alcohols by addition of
hydrogen in the presence of catalysts (catalytic hydrogenation)
...
It is also prepared by treating aldehydes
and ketones with sodium borohydride (NaBH4) or lithium
aluminium hydride (LiAlH4)
...


The numbers in front
of the reagents along
the arrow indicate
that the second
reagent is added only
when the reaction
with first is complete
...

(i) LiAlH4

RCOOH
(ii) H2O

RCH2OH

However, LiAlH4 is an expensive reagent, and therefore, used
for preparing special chemicals only
...
4
...

R'OH
H+

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3
...

The first step of the reaction is the nucleophilic addition of Grignard
reagent to the carbonyl group to form an adduct
...



...
(ii)

The reaction of
Grignard reagents
with methanal
produces a primary
alcohol, with other
aldehydes, secondary
alcohols and with
ketones, tertiary
alcohols
...

Give the structures and IUPAC names of the products expected from
the following reactions:

Example 11
...

3
(b) Hydration of propene in the presence of dilute sulphuric
acid
...

CH3
(c)
(a) CH–CH
(b) CH–CH–CH
(c)
CH3 C OH
3
33
2–CH2–CH2–OH
3
3
3
OH
Butan-1-ol
CH3

Propan-2-ol

Solution

2-Methylpropan-2-ol

3

3
3

3

3

3
3
11
...
2 Preparation
of Phenols

Phenol, also known as carbolic acid, was first isolated in the early
nineteenth century from coal tar
...
In the laboratory, phenols are prepared from
benzene derivatives by any of the following methods:
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3

1
...
Phenol is obtained by acidification of sodium phenoxide so
produced (Unit 10, Class XII)
...
From benzenesulphonic acid
Benzene is sulphonated with oleum and benzene sulphonic acid so
formed is converted to sodium phenoxide on heating with molten
sodium hydroxide
...


3
...
Diazonium salts are
hydrolysed to phenols by warming with water or by treating with
dilute acids (Unit 13, Class XII)
...


OH
H2O
Warm

+ N2 + HCl

Benzene diazonium
chloride

4
...
Cumene
(isopropylbenzene) is oxidised in the presence of air to cumene
hydroperoxide
...
Acetone, a by-product of this reaction, is also
obtained in large quantities by this method
...
4 Show how are the following alcohols prepared by the reaction of a suitable
Grignard reagent on methanal ?

11
...
4
...
The properties of alcohols and phenols are chiefly due
to the hydroxyl group
...

Boiling Points
The boiling points of alcohols and phenols increase with increase in the
number of carbon atoms (increase in van der Waals forces)
...

The –OH group in alcohols and phenols is involved in intermolecular
hydrogen bonding as shown below:

It is interesting to note that boiling points of alcohols and phenols
are higher in comparison to other classes of compounds, namely
hydrocarbons, ethers, haloalkanes and haloarenes of comparable
molecular masses
...
The boiling
point of methoxymethane is intermediate of the two boiling points
...

Solubility
Solubility of alcohols and phenols in
water is due to their ability to form
hydrogen bonds with water molecules
as shown
...
Several of the lower
molecular mass alcohols are miscible
with water in all proportions
...
3 Arrange the following sets of compounds in order of their increasing
boiling points:
(a) Pentan-1-ol, butan-1-ol, butan-2-ol, ethanol, propan-1-ol, methanol
...


Solution (a) Methanol, ethanol, propan-1-ol, butan-2-ol, butan-1-ol, pentan-1-ol
...

11
...
4 Chemical
Reactions

Alcohols are versatile compounds
...
The bond between O–H is broken when alcohols react as
nucleophiles
...
Protonated alcohols react in this manner
...
Acidity of alcohols and phenols

(i) Reaction with metals: Alcohols and phenols react with active
metals such as sodium, potassium and aluminium to yield
corresponding alkoxides/phenoxides and hydrogen
...


OH

ONa
+ NaOH

+ H 2O
Sodium phenoxide

The above reactions show that alcohols and phenols are
acidic in nature
...
e
...


(ii) Acidity of alcohols: The acidic character of alcohols is due to
the polar nature of O–H bond
...
This decreases the acid
strength
...
This can be
illustrated by the reaction of water with an alkoxide
...
e
...
Also, in the above reaction, we note
that an alkoxide ion is a better proton acceptor than hydroxide
ion, which suggests that alkoxides are stronger bases (sodium
ethoxide is a stronger base than sodium hydroxide)
...
It is due to the
presence of unshared electron pairs on oxygen, which makes
them proton acceptors
...
g
...
The hydroxyl group, in phenol is directly attached to
the sp2 hybridised carbon of benzene ring which acts as an
electron withdrawing group
...


The reaction of phenol with aqueous sodium hydroxide
indicates that phenols are stronger acids than alcohols and water
...

The ionisation of an alcohol and a phenol takes place as follows:

Due to the higher electronegativity of sp2 hybridised carbon
of phenol to which –OH is attached, electron density decreases
on oxygen
...

Now let us examine the stabilities of alkoxide and phenoxide
ions
...

The delocalisation of negative charge (structures I-V) makes
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phenoxide ion more stable and favours the ionisation of phenol
...


In substituted phenols, the presence of electron withdrawing
groups such as nitro group, enhances the acidic strength of
phenol
...
It is due to the effective
delocalisation of negative charge in phenoxide ion
...
Cresols, for example, are less acidic
than phenol
...


Table 11
...
2

m-Nitrophenol

m–O 2N–C6 H4 –OH

8
...
1

Phenol

C6H 5–OH

10
...
2

m-Cresol

m-CH3 C6H 4–OH

10
...
2

Ethanol

C2H5 OH

15
...

Arrange the following compounds in increasing order of their acid strength:
Propan-1-ol, 2,4,6-trinitrophenol, 3-nitrophenol, 3,5-dinitrophenol,
phenol, 4-methylphenol
...
4

Propan-1-ol, 4-methylphenol, phenol, 3-nitrophenol, 3,5-dinitrophenol,
2,4, 6-trinitrophenol
...
Esterification
Alcohols and phenols react with carboxylic acids, acid chlorides and
acid anhydrides to form esters
...


Pyridine

Ar/ROCOR’+R’COOH
R/ArOCOR’ + HCl

The reaction with carboxylic acid and acid anhydride is carried
out in the presence of a small amount of concentrated sulphuric
acid
...
The reaction with acid chloride is carried out in
the presence of a base (pyridine) so as to neutralise HCl which is
formed during the reaction
...
The introduction of acetyl (CH3CO) group in alcohols or
phenols is known as acetylation
...


(b) Reactions involving cleavage of carbon – oxygen (C–O) bond in
alcohols
The reactions involving cleavage of C–O bond take place only in
alcohols
...

1
...

ROH + HX → R–X + H2O
The difference in reactivity of three classes of alcohols with HCl
distinguishes them from one another (Lucas test)
...
HCl and ZnCl2) while their halides are immiscible
and produce turbidity in solution
...
Primary
alcohols do not produce turbidity at room temperature
...
Reaction with phosphorus trihalides: Alcohols are converted to
alkyl bromides by reaction with phosphorus tribromide (Refer Unit
10, Class XII)
...
Dehydration: Alcohols undergo dehydration (removal of a molecule
of water) to form alkenes on treating with a protic acid e
...
,
concentrated H2SO4 or H3PO4, or catalysts such as anhydrous zinc
chloride or alumina (Unit 13, Class XI)
...


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Secondary and tertiary alcohols are dehydrated under milder
conditions
...


Mechanism

Step 1: Formation of protonated alcohol
...


Step 3: Formation of ethene by elimination of a proton
...
To drive the equilibrium
to the right, ethene is removed as it is formed
...
Oxidation: Oxidation of alcohols involves the formation of a carbonoxygen double bond with cleavage of an O-H and C-H bonds
...
These are also known as dehydrogenation reactions as
these involve loss of dihydrogen from an alcohol molecule
...


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Strong oxidising agents such as acidified potassium permanganate
are used for getting carboxylic acids from alcohols directly
...

CrO

3 → RCHO
RCH 2OH 

A better reagent for oxidation of primary alcohols to aldehydes in
good yield is pyridinium chlorochromate (PCC), a complex of
chromium trioxide with pyridine and HCl
...


Tertiary alcohols do not undergo oxidation reaction
...

When the vapours of a
primary or a secondary alcohol
are passed over heated copper
at 573 K, dehydrogenation
takes place and an aldehyde or
a ketone is formed while tertiary
alcohols undergo dehydration
...
At times the alcoholics, by mistake, drink ethanol,
mixed with methanol also called denatured alcohol
...
A methanol poisoned patient is treated by giving intravenous infusions of
diluted ethanol
...


(c) Reactions of phenols
Following reactions are shown by phenols only
...
Electrophilic aromatic substitution
In phenols, the reactions that take place on the aromatic ring are
electrophilic substitution reactions (Unit 13, Class XI)
...
Also, it directs the incoming group to ortho and para
positions in the ring as these positions become electron rich due to
the resonance effect caused by –OH group
...

Common electrophilic aromatic substitution reactions taking place
in phenol are as follows:
(i) Nitration: With dilute nitric acid at low temperature (298 K),
phenol yields a mixture of ortho and para nitrophenols
...
o-Nitrophenol is steam volatile due to intramolecular
hydrogen bonding while p-nitrophenol is less volatile due to
intermolecular hydrogen bonding which causes the association
of molecules
...


With concentrated nitric acid, phenol is converted to
2,4,6-trinitrophenol
...
The yield of the reaction product is poor
...
Can you write the equations of
the reactions involved?
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(ii) Halogenation: On treating phenol with bromine, different reaction
products are formed under different experimental conditions
...


The usual halogenation of benzene takes place in the
presence of a Lewis acid, such as FeBr3 (Unit 10, Class XII),
which polarises the halogen molecule
...
It is due to the highly activating
effect of –OH group attached to the benzene ring
...


OH

Br

OH
Br

+ 3 Br2
Br
2,4,6- Tribromophenol

Example 11
...


Solution The combined influence of –OH and –CH3 groups determine the
position of the incoming group
...
Kolbe’s reaction

Phenoxide ion generated by treating phenol with sodium hydroxide
is even more reactive than phenol towards electrophilic aromatic
substitution
...
Ortho hydroxybenzoic acid is
formed as the main reaction product
...
Reimer-Tiemann reaction
On treating phenol with chloroform in the presence of sodium
hydroxide, a –CHO group is introduced at ortho position of benzene
ring
...

The intermediate substituted benzal chloride is hydrolysed in the
presence of alkali to produce salicylaldehyde
...
Reaction of phenol with zinc dust
Phenol is converted to benzene on heating with zinc dust
...
Oxidation
Oxidation of phenol with chromic
acid produces a conjugated diketone
known as benzoquinone
...


Intext Questions
11
...

(i) Butan-1-ol
(ii) 2-Methylbutan-2-ol
11
...
8 Ortho and para nitrophenols are more acidic than phenol
...

11
...
5 Some
Commercially
Important
Alcohols

Methanol and ethanol are among the two commercially important
alcohols
...
Methanol
Methanol, CH3OH, also known as ‘wood spirit’, was produced by
destructive distillation of wood
...


Methanol is a colourless liquid and boils at 337 K
...
Ingestion of even small quantities of methanol
can cause blindness and large quantities causes even death
...

2
...
The sugar in molasses, sugarcane
or fruits such as grapes is converted to glucose and fructose, (both
of which have the formula C6H12O 6), in the presence of an enzyme,
invertase
...


Ingestion of ethanol acts
on the central nervous
system
...
Higher
concentrations cause
nausea and loss of
consciousness
...


In wine making, grapes are the source of sugars and yeast
...
When grapes are crushed, sugar and the enzyme come in
contact and fermentation starts
...
e
...
Carbon dioxide is released
during fermentation
...
If air gets into fermentation mixture, the
oxygen of air oxidises ethanol to ethanoic acid which in turn destroys
the taste of alcoholic drinks
...
It is used
as a solvent in paint industry and in the preparation of a number of
carbon compounds
...
It is known as denaturation of alcohol
...
4)
...
6 Ethers
11
...
1 Preparation
of Ethers

Diethyl ether has been
used widely as an
inhalation anaesthetic
...


1
...
The formation of the reaction product, alkene or ether
depends on the reaction conditions
...

At 413 K, ethoxyethane is the main product
...

The method is suitable for the preparation of ethers having primary
alkyl groups only
...
Otherwise the reaction favours the formation
of alkene
...

However, the dehydration of secondary and tertiary alcohols to give
corresponding ethers is unsuccessful as elimination competes over
substitution and as a consequence, alkenes are easily formed
...
Williamson synthesis
Alexander William
Williamson (1824–1904)
was born in London of
Scottish parents
...


It is an important laboratory method for the preparation of
symmetrical and unsymmetrical ethers
...

–

+

R– X + R’–O Na

R–O–R’ + Na X

Ethers containing substituted alkyl groups (secondary or tertiary)
may also be prepared by this method
...

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O Na + CH3–Br

Better results are obtained if the alkyl halide is primary
...
If a tertiary alkyl halide is used, an alkene is the only
reaction product and no ether is formed
...


It is because alkoxides are not only nucleophiles but strong bases
as well
...


Example 11
...


(i) What would be the major product of this reaction ?
(ii) Write a suitable reaction for the preparation of t-butylethyl ether
...

It is because sodium ethoxide is a strong nucleophile as well as
a strong base
...


(ii)

Phenols are also converted to ethers by this method
...


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11
...
2 Physical
Properties

The C-O bonds in ethers are polar and thus, ethers have a net dipole
moment
...
p
...
1

307
...

The miscibility of ethers with water resembles those of alcohols of
the same molecular mass
...
e
...
5 and 9 g per 100 mL water,
respectively while pentane is essentially immiscible with water
...
6
...
Cleavage of C–O bond in ethers
Ethers are the least reactive of the functional groups
...
The reaction of dialkyl ether gives two alkyl
halide molecules
...
The reaction yields phenol and alkyl
halide
...

The order of reactivity of hydrogen halides is as follows:
HI > HBr > HCl
...


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Mechanism
The reaction of an ether with concentrated HI starts with protonation of ether molecule
...

Step 2:
Iodide is a good nucleophile
...

Thus, in the cleavage of mixed ethers with two different alkyl groups, the alcohol
and alkyl iodide formed, depend on the nature of alkyl groups
...


When HI is in excess and the reaction is carried out at high temperature,
ethanol reacts with another molecule of HI and is converted to ethyl iodide
...

CH3

CH3

CH3 C

O CH3 + HI

CH3OH +CH3 C I

CH3

CH3

It is because in step 2 of the reaction, the departure of leaving group
+
(HO–CH3) creates a more stable carbocation [(CH3)3C ], and the reaction
follows SN1 mechanism
...
The
bond between O–CH 3 is weaker
than the bond between O–C 6H5
because the carbon of phenyl
group is sp2 hybridised and there
is a partial double bond character
...
Phenols
do not react further to give halides because the sp2 hybridised carbon
of phenol cannot undergo nucleophilic substitution reaction needed
for conversion to the halide
...


(i)

Example 11
...
Electrophilic substitution
The alkoxy group (-OR) is ortho, para directing and activates the
aromatic ring towards electrophilic substitution in the same way as
in phenol
...
g
...
It is due to the activation of benzene ring by the methoxy
group
...


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(ii) Friedel-Crafts reaction: Anisole undergoes Friedel-Crafts reaction,
i
...
, the alkyl and acyl groups are introduced at ortho and para
positions by reaction with alkyl halide and acyl halide in the
presence of anhydrous aluminium chloride (a Lewis acid) as catalyst
...


Intext Questions
11
...

11
...
12 Predict the products of the following reactions:
(i) CH3 − CH2 − CH2 − O – CH3 + HBr →
(ii)

(iii)

(iv)

HI
→
( CH 3 ) 3 C − OC2H 5 

Summary
Alcohols and phenols are classified (i) on the basis of the number of hydroxyl
groups and (ii) according to the hybridisation of the carbon atom, sp3 or sp2 to
which the –OH group is attached
...

Alcohols may be prepared (1) by hydration of alkenes (i) in presence of an
acid and (ii) by hydroboration-oxidation reaction (2) from carbonyl compounds by
(i) catalytic reduction and (ii) the action of Grignard reagents
...

Alcohols are higher boiling than other classes of compounds, namely
hydrocarbons, ethers and haloalkanes of comparable molecular masses
...

Alcohols and phenols are acidic in nature
...

Alcohols undergo nucleophilic substitution with hydrogen halides to yield
alkyl halides
...
On oxidation, primary alcohols
yield aldehydes with mild oxidising agents and carboxylic acids with strong
oxidising agents while secondary alcohols yield ketones
...

The presence of –OH group in phenols activates the aromatic ring towards
electrophilic substitution and directs the incoming group to ortho and para
positions due to resonance effect
...
In presence of sodium hydroxide, phenol generates phenoxide
ion which is even more reactive than phenol
...

Ethers may be prepared by (i) dehydration of alcohols and (ii) Williamson
synthesis
...
The
C–O bond in ethers can be cleaved by hydrogen halides
...


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Exercises
11
...
2 Write structures of the compounds whose IUPAC names are as follows:
(i) 2-Methylbutan-2-ol
(ii) 1-Phenylpropan-2-ol
(iii) 3,5-Dimethylhexane –1, 3, 5-triol
(iv) 2,3 – Diethylphenol
(v) 1 – Ethoxypropane
(vi) 2-Ethoxy-3-methylpentane
(vii) Cyclohexylmethanol
(viii) 3-Cyclohexylpentan-3-ol
(ix) Cyclopent-3-en-1-ol
(x) 4-Chloro-3-ethylbutan-1-ol
...
3 (i) Draw the structures of all isomeric alcohols of molecular formula C5H 12O
and give their IUPAC names
...
3 (i) as primary, secondary
and tertiary alcohols
...
4 Explain why propanol has higher boiling point than that of the hydrocarbon,
butane?
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Explain this fact
...
6 What is meant by hydroboration-oxidation reaction? Illustrate it with an example
...
7 Give the structures and IUPAC names of monohydric phenols of molecular
formula, C7H 8O
...
8 While separating a mixture of ortho and para nitrophenols by steam
distillation, name the isomer which will be steam volatile
...

11
...

11
...

11
...

11
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H2 SO4 and NaOH
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(ii) cyclohexylmethanol using an alkyl halide by an SN2 reaction
...
14 Give two reactions that show the acidic nature of phenol
...

11
...
16 Explain how does the –OH group attached to a carbon of benzene ring
activate it towards electrophilic substitution?
11
...

(ii) Bromine in CS 2 with phenol
...

(iv) Treating phenol wih chloroform in presence of aqueous NaOH
...
18 Explain the following with an example
...

(ii) Reimer-Tiemann reaction
...

(iv) Unsymmetrical ether
...
19 Write the mechanism of acid dehydration of ethanol to yield ethene
...
20 How are the following conversions carried out?
(i) Propene →

Propan-2-ol
...

(iii) Ethyl magnesium chloride → Propan-1-ol
...

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...

(ii) Oxidation of a primary alcohol to aldehyde
...

(iv) Benzyl alcohol to benzoic acid
...

(vi) Butan-2-one to butan-2-ol
...
22 Give reason for the higher boiling point of ethanol in comparison to
methoxymethane
...
23 Give IUPAC names of the following ethers:

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25 Illustrate with examples the limitations of Williamson synthesis for the
preparation of certain types of ethers
...
26 How is 1-propoxypropane synthesised from propan-1-ol? Write mechanism
of this reaction
...
27 Preparation of ethers by acid dehydration of secondary or tertiary alcohols
is not a suitable method
...

11
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11
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11
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(ii) Nitration of anisole
...

(iv) Friedel-Craft’s acetylation of anisole
...
32 Show how would you synthesise the following alcohols from appropriate
alkenes?
CH3
(i)

OH

OH
(ii)

OH
(iii)

(iv)

OH

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(Hint : The secondary carbocation formed in step II rearranges to a more
stable tertiary carbocation by a hydride ion shift from 3rd carbon atom
...
1 Primary alcohols

(i), (ii), (iii)

Secondary alcohols

(iv) and (v)

Tertiary alcohols

(vi)

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3

(ii) and (vi)

(i) 4-Chloro-3-ethyl-2-(1-methylethyl)-butan-1-ol
(ii) 2, 5-Dimethylhexane-1,3-diol
(iii) 3-Bromocyclohexanol
(iv) Hex-1-en-3-ol
(v) 2-Bromo-3-methylbut-2-en-1-ol

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5

(i) CH3

CH

CH3

(ii)

OCH3

O

OH
(iii) CH3

CH2

CH

CH2OH

CH3

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But-2-ene is the major product
formed due to rearrangement to give secondary carbocation
...
10

C2H5OH

HBr

C2H5Br

CH3 – CH2 – CH – CH – ONa + C2H5Br

CH3 – CH2 – CH – CH – OC2H5

CH3 CH3

CH3 CH3
2-Ethoxy-3-methylpentane

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12 (i)

(iii)

CH 3CH2CH 2OH + CH 3Br

(ii)

(iv)

(CH3 ) 3 C − I + C2 H5OH

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