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1 | 6105-6108 | Esterification
Alcohols and phenols react with carboxylic acids, acid chlorides and
acid anhydrides to form esters In substituted phenols, the presence of electron withdrawing
groups such as nitro group, enhances the acidic strength of
phenol This effect is more pronounced when such a group is
present at ortho and para positions It is due to the effective
delocalisation of negative charge in phenoxide ion when
substituent is at ortho or para position |
1 | 6106-6109 | In substituted phenols, the presence of electron withdrawing
groups such as nitro group, enhances the acidic strength of
phenol This effect is more pronounced when such a group is
present at ortho and para positions It is due to the effective
delocalisation of negative charge in phenoxide ion when
substituent is at ortho or para position On the other hand,
electron releasing groups, such as alkyl groups, in general, do
not favour the formation of phenoxide ion resulting in decrease
in acid strength |
1 | 6107-6110 | This effect is more pronounced when such a group is
present at ortho and para positions It is due to the effective
delocalisation of negative charge in phenoxide ion when
substituent is at ortho or para position On the other hand,
electron releasing groups, such as alkyl groups, in general, do
not favour the formation of phenoxide ion resulting in decrease
in acid strength Cresols, for example, are less acidic than phenol |
1 | 6108-6111 | It is due to the effective
delocalisation of negative charge in phenoxide ion when
substituent is at ortho or para position On the other hand,
electron releasing groups, such as alkyl groups, in general, do
not favour the formation of phenoxide ion resulting in decrease
in acid strength Cresols, for example, are less acidic than phenol The greater the pKa
value, the weaker the
acid |
1 | 6109-6112 | On the other hand,
electron releasing groups, such as alkyl groups, in general, do
not favour the formation of phenoxide ion resulting in decrease
in acid strength Cresols, for example, are less acidic than phenol The greater the pKa
value, the weaker the
acid Rationalised 2023-24
208
Chemistry
Pyridine
R/Ar
+R’
l
OH
COC
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 |
1 | 6110-6113 | Cresols, for example, are less acidic than phenol The greater the pKa
value, the weaker the
acid Rationalised 2023-24
208
Chemistry
Pyridine
R/Ar
+R’
l
OH
COC
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 is reversible, and therefore, water is removed as
soon as it is formed |
1 | 6111-6114 | The greater the pKa
value, the weaker the
acid Rationalised 2023-24
208
Chemistry
Pyridine
R/Ar
+R’
l
OH
COC
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 is reversible, and therefore, water is removed as
soon as it is formed 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 |
1 | 6112-6115 | Rationalised 2023-24
208
Chemistry
Pyridine
R/Ar
+R’
l
OH
COC
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 is reversible, and therefore, water is removed as
soon as it is formed 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 It shifts the equilibrium to the right
hand side |
1 | 6113-6116 | The reaction is reversible, and therefore, water is removed as
soon as it is formed 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 It shifts the equilibrium to the right
hand side The introduction of acetyl (CH3CO) group in alcohols or
phenols is known as acetylation |
1 | 6114-6117 | 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 It shifts the equilibrium to the right
hand side The introduction of acetyl (CH3CO) group in alcohols or
phenols is known as acetylation Acetylation of salicylic acid
produces aspirin |
1 | 6115-6118 | It shifts the equilibrium to the right
hand side The introduction of acetyl (CH3CO) group in alcohols or
phenols is known as acetylation Acetylation of salicylic acid
produces aspirin (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 | 6116-6119 | The introduction of acetyl (CH3CO) group in alcohols or
phenols is known as acetylation Acetylation of salicylic acid
produces aspirin (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 Phenols show this type of reaction only with zinc |
1 | 6117-6120 | Acetylation of salicylic acid
produces aspirin (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 Phenols show this type of reaction only with zinc 1 |
1 | 6118-6121 | (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 Phenols show this type of reaction only with zinc 1 Reaction with hydrogen halides: Alcohols react with hydrogen
halides to form alkyl halides (Refer Unit 6, Class XII) |
1 | 6119-6122 | Phenols show this type of reaction only with zinc 1 Reaction with hydrogen halides: Alcohols react with hydrogen
halides to form alkyl halides (Refer Unit 6, Class XII) ROH + HX ® R–X + H2O
The difference in reactivity of three classes of alcohols with HCl
distinguishes them from one another (Lucas test) |
1 | 6120-6123 | 1 Reaction with hydrogen halides: Alcohols react with hydrogen
halides to form alkyl halides (Refer Unit 6, Class XII) ROH + HX ® R–X + H2O
The difference in reactivity of three classes of alcohols with HCl
distinguishes them from one another (Lucas test) Alcohols are soluble
in Lucas reagent (conc |
1 | 6121-6124 | Reaction with hydrogen halides: Alcohols react with hydrogen
halides to form alkyl halides (Refer Unit 6, Class XII) ROH + HX ® R–X + H2O
The difference in reactivity of three classes of alcohols with HCl
distinguishes them from one another (Lucas test) Alcohols are soluble
in Lucas reagent (conc HCl and ZnCl2) while their halides are immiscible
and produce turbidity in solution |
1 | 6122-6125 | ROH + HX ® R–X + H2O
The difference in reactivity of three classes of alcohols with HCl
distinguishes them from one another (Lucas test) Alcohols are soluble
in Lucas reagent (conc HCl and ZnCl2) while their halides are immiscible
and produce turbidity in solution In case of tertiary alcohols, turbidity
is produced immediately as they form the halides easily |
1 | 6123-6126 | Alcohols are soluble
in Lucas reagent (conc HCl and ZnCl2) while their halides are immiscible
and produce turbidity in solution In case of tertiary alcohols, turbidity
is produced immediately as they form the halides easily Primary
alcohols do not produce turbidity at room temperature |
1 | 6124-6127 | HCl and ZnCl2) while their halides are immiscible
and produce turbidity in solution In case of tertiary alcohols, turbidity
is produced immediately as they form the halides easily Primary
alcohols do not produce turbidity at room temperature 2 |
1 | 6125-6128 | In case of tertiary alcohols, turbidity
is produced immediately as they form the halides easily Primary
alcohols do not produce turbidity at room temperature 2 Reaction with phosphorus trihalides: Alcohols are converted to
alkyl bromides by reaction with phosphorus tribromide (Refer
Unit 6, Class XII) |
1 | 6126-6129 | Primary
alcohols do not produce turbidity at room temperature 2 Reaction with phosphorus trihalides: Alcohols are converted to
alkyl bromides by reaction with phosphorus tribromide (Refer
Unit 6, Class XII) 3 |
1 | 6127-6130 | 2 Reaction with phosphorus trihalides: Alcohols are converted to
alkyl bromides by reaction with phosphorus tribromide (Refer
Unit 6, Class XII) 3 Dehydration: Alcohols undergo dehydration (removal of a molecule
of water) to form alkenes on treating with a protic acid e |
1 | 6128-6131 | Reaction with phosphorus trihalides: Alcohols are converted to
alkyl bromides by reaction with phosphorus tribromide (Refer
Unit 6, Class XII) 3 Dehydration: Alcohols undergo dehydration (removal of a molecule
of water) to form alkenes on treating with a protic acid e g |
1 | 6129-6132 | 3 Dehydration: Alcohols undergo dehydration (removal of a molecule
of water) to form alkenes on treating with a protic acid e g ,
concentrated H2SO4 or H3PO4, or catalysts such as anhydrous zinc
chloride or alumina |
1 | 6130-6133 | Dehydration: Alcohols undergo dehydration (removal of a molecule
of water) to form alkenes on treating with a protic acid e g ,
concentrated H2SO4 or H3PO4, or catalysts such as anhydrous zinc
chloride or alumina Ethanol undergoes dehydration by heating it with concentrated
H2SO4 at 443 K |
1 | 6131-6134 | g ,
concentrated H2SO4 or H3PO4, or catalysts such as anhydrous zinc
chloride or alumina Ethanol undergoes dehydration by heating it with concentrated
H2SO4 at 443 K Aspirin possesses
analgesic, anti-
inflammatory and
antipyretic properties |
1 | 6132-6135 | ,
concentrated H2SO4 or H3PO4, or catalysts such as anhydrous zinc
chloride or alumina Ethanol undergoes dehydration by heating it with concentrated
H2SO4 at 443 K Aspirin possesses
analgesic, anti-
inflammatory and
antipyretic properties Rationalised 2023-24
209
Alcohols, Phenols and Ethers
Secondary and tertiary alcohols are dehydrated under milder
conditions |
1 | 6133-6136 | Ethanol undergoes dehydration by heating it with concentrated
H2SO4 at 443 K Aspirin possesses
analgesic, anti-
inflammatory and
antipyretic properties Rationalised 2023-24
209
Alcohols, Phenols and Ethers
Secondary and tertiary alcohols are dehydrated under milder
conditions For example
Thus, the relative ease of dehydration of alcohols follows the
following order:
Tertiary
Secondary
Primary
>
>
The mechanism of dehydration of ethanol involves the following steps:
Mechanism
Step 1: Formation of protonated alcohol |
1 | 6134-6137 | Aspirin possesses
analgesic, anti-
inflammatory and
antipyretic properties Rationalised 2023-24
209
Alcohols, Phenols and Ethers
Secondary and tertiary alcohols are dehydrated under milder
conditions For example
Thus, the relative ease of dehydration of alcohols follows the
following order:
Tertiary
Secondary
Primary
>
>
The mechanism of dehydration of ethanol involves the following steps:
Mechanism
Step 1: Formation of protonated alcohol Step 2: Formation of carbocation: It is the slowest step and hence, the
rate determining step of the reaction |
1 | 6135-6138 | Rationalised 2023-24
209
Alcohols, Phenols and Ethers
Secondary and tertiary alcohols are dehydrated under milder
conditions For example
Thus, the relative ease of dehydration of alcohols follows the
following order:
Tertiary
Secondary
Primary
>
>
The mechanism of dehydration of ethanol involves the following steps:
Mechanism
Step 1: Formation of protonated alcohol Step 2: Formation of carbocation: It is the slowest step and hence, the
rate determining step of the reaction Step 3: Formation of ethene by elimination of a proton |
1 | 6136-6139 | For example
Thus, the relative ease of dehydration of alcohols follows the
following order:
Tertiary
Secondary
Primary
>
>
The mechanism of dehydration of ethanol involves the following steps:
Mechanism
Step 1: Formation of protonated alcohol Step 2: Formation of carbocation: It is the slowest step and hence, the
rate determining step of the reaction Step 3: Formation of ethene by elimination of a proton The acid used in step 1 is released in step 3 |
1 | 6137-6140 | Step 2: Formation of carbocation: It is the slowest step and hence, the
rate determining step of the reaction Step 3: Formation of ethene by elimination of a proton The acid used in step 1 is released in step 3 To drive the equilibrium
to the right, ethene is removed as it is formed |
1 | 6138-6141 | Step 3: Formation of ethene by elimination of a proton The acid used in step 1 is released in step 3 To drive the equilibrium
to the right, ethene is removed as it is formed 4 |
1 | 6139-6142 | The acid used in step 1 is released in step 3 To drive the equilibrium
to the right, ethene is removed as it is formed 4 Oxidation: Oxidation of alcohols involves the formation of a carbon-
oxygen double bond with cleavage of an O-H and C-H bonds |
1 | 6140-6143 | To drive the equilibrium
to the right, ethene is removed as it is formed 4 Oxidation: Oxidation of alcohols involves the formation of a carbon-
oxygen double bond with cleavage of an O-H and C-H bonds Such a cleavage and formation of bonds occur in oxidation
reactions |
1 | 6141-6144 | 4 Oxidation: Oxidation of alcohols involves the formation of a carbon-
oxygen double bond with cleavage of an O-H and C-H bonds Such a cleavage and formation of bonds occur in oxidation
reactions These are also known as dehydrogenation reactions as
these involve loss of dihydrogen from an alcohol molecule |
1 | 6142-6145 | Oxidation: Oxidation of alcohols involves the formation of a carbon-
oxygen double bond with cleavage of an O-H and C-H bonds Such a cleavage and formation of bonds occur in oxidation
reactions These are also known as dehydrogenation reactions as
these involve loss of dihydrogen from an alcohol molecule Depending
on the oxidising agent used, a primary alcohol is oxidised to an
aldehyde which in turn is oxidised to a carboxylic acid |
1 | 6143-6146 | Such a cleavage and formation of bonds occur in oxidation
reactions These are also known as dehydrogenation reactions as
these involve loss of dihydrogen from an alcohol molecule Depending
on the oxidising agent used, a primary alcohol is oxidised to an
aldehyde which in turn is oxidised to a carboxylic acid Tertiary carbocations
are more stable and
therefore are easier to
form than secondary
and primary
carbocations; tertiary
alcohols are the easiest
to dehydrate |
1 | 6144-6147 | These are also known as dehydrogenation reactions as
these involve loss of dihydrogen from an alcohol molecule Depending
on the oxidising agent used, a primary alcohol is oxidised to an
aldehyde which in turn is oxidised to a carboxylic acid Tertiary carbocations
are more stable and
therefore are easier to
form than secondary
and primary
carbocations; tertiary
alcohols are the easiest
to dehydrate Rationalised 2023-24
210
Chemistry
Strong oxidising agents such as acidified potassium
permanganate are used for getting carboxylic acids from alcohols
directly |
1 | 6145-6148 | Depending
on the oxidising agent used, a primary alcohol is oxidised to an
aldehyde which in turn is oxidised to a carboxylic acid Tertiary carbocations
are more stable and
therefore are easier to
form than secondary
and primary
carbocations; tertiary
alcohols are the easiest
to dehydrate Rationalised 2023-24
210
Chemistry
Strong oxidising agents such as acidified potassium
permanganate are used for getting carboxylic acids from alcohols
directly CrO3 in anhydrous medium is used as the oxidising agent
for the isolation of aldehydes |
1 | 6146-6149 | Tertiary carbocations
are more stable and
therefore are easier to
form than secondary
and primary
carbocations; tertiary
alcohols are the easiest
to dehydrate Rationalised 2023-24
210
Chemistry
Strong oxidising agents such as acidified potassium
permanganate are used for getting carboxylic acids from alcohols
directly CrO3 in anhydrous medium is used as the oxidising agent
for the isolation of aldehydes 3
2
CrO
R H
R
C
OH
CHO
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 |
1 | 6147-6150 | Rationalised 2023-24
210
Chemistry
Strong oxidising agents such as acidified potassium
permanganate are used for getting carboxylic acids from alcohols
directly CrO3 in anhydrous medium is used as the oxidising agent
for the isolation of aldehydes 3
2
CrO
R H
R
C
OH
CHO
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 3
2
3
PCC
O
CH
CH
CH
H
CH
CH
O
CH
CH
CH
Secondary alcohols are oxidised to ketones by chromic anhyride
(CrO3) |
1 | 6148-6151 | CrO3 in anhydrous medium is used as the oxidising agent
for the isolation of aldehydes 3
2
CrO
R H
R
C
OH
CHO
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 3
2
3
PCC
O
CH
CH
CH
H
CH
CH
O
CH
CH
CH
Secondary alcohols are oxidised to ketones by chromic anhyride
(CrO3) Tertiary alcohols do not undergo oxidation reaction |
1 | 6149-6152 | 3
2
CrO
R H
R
C
OH
CHO
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 3
2
3
PCC
O
CH
CH
CH
H
CH
CH
O
CH
CH
CH
Secondary alcohols are oxidised to ketones by chromic anhyride
(CrO3) Tertiary alcohols do not undergo oxidation reaction Under strong
reaction conditions such as strong oxidising agents (KMnO4) and
elevated temperatures, cleavage of various C-C bonds takes place
and a mixture of carboxylic
acids containing lesser number
of carbon atoms is formed |
1 | 6150-6153 | 3
2
3
PCC
O
CH
CH
CH
H
CH
CH
O
CH
CH
CH
Secondary alcohols are oxidised to ketones by chromic anhyride
(CrO3) Tertiary alcohols do not undergo oxidation reaction Under strong
reaction conditions such as strong oxidising agents (KMnO4) and
elevated temperatures, cleavage of various C-C bonds takes place
and a mixture of carboxylic
acids containing lesser number
of carbon atoms is formed 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 |
1 | 6151-6154 | Tertiary alcohols do not undergo oxidation reaction Under strong
reaction conditions such as strong oxidising agents (KMnO4) and
elevated temperatures, cleavage of various C-C bonds takes place
and a mixture of carboxylic
acids containing lesser number
of carbon atoms is formed 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 Biological oxidation of methanol and ethanol in the body produces the corresponding
aldehyde followed by the acid |
1 | 6152-6155 | Under strong
reaction conditions such as strong oxidising agents (KMnO4) and
elevated temperatures, cleavage of various C-C bonds takes place
and a mixture of carboxylic
acids containing lesser number
of carbon atoms is formed 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 Biological oxidation of methanol and ethanol in the body produces the corresponding
aldehyde followed by the acid At times the alcoholics, by mistake, drink ethanol,
mixed with methanol also called denatured alcohol |
1 | 6153-6156 | 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 Biological oxidation of methanol and ethanol in the body produces the corresponding
aldehyde followed by the acid At times the alcoholics, by mistake, drink ethanol,
mixed with methanol also called denatured alcohol In the body, methanol is oxidised
first to methanal and then to methanoic acid, which may cause blindness and
death |
1 | 6154-6157 | Biological oxidation of methanol and ethanol in the body produces the corresponding
aldehyde followed by the acid At times the alcoholics, by mistake, drink ethanol,
mixed with methanol also called denatured alcohol In the body, methanol is oxidised
first to methanal and then to methanoic acid, which may cause blindness and
death A methanol poisoned patient is treated by giving intravenous infusions of
diluted ethanol |
1 | 6155-6158 | At times the alcoholics, by mistake, drink ethanol,
mixed with methanol also called denatured alcohol In the body, methanol is oxidised
first to methanal and then to methanoic acid, which may cause blindness and
death A methanol poisoned patient is treated by giving intravenous infusions of
diluted ethanol The enzyme responsible for oxidation of aldehyde (HCHO) to acid
is swamped allowing time for kidneys to excrete methanol |
1 | 6156-6159 | In the body, methanol is oxidised
first to methanal and then to methanoic acid, which may cause blindness and
death A methanol poisoned patient is treated by giving intravenous infusions of
diluted ethanol The enzyme responsible for oxidation of aldehyde (HCHO) to acid
is swamped allowing time for kidneys to excrete methanol (c) Reactions of phenols
Following reactions are shown by phenols only |
1 | 6157-6160 | A methanol poisoned patient is treated by giving intravenous infusions of
diluted ethanol The enzyme responsible for oxidation of aldehyde (HCHO) to acid
is swamped allowing time for kidneys to excrete methanol (c) Reactions of phenols
Following reactions are shown by phenols only Rationalised 2023-24
211
Alcohols, Phenols and Ethers
1 |
1 | 6158-6161 | The enzyme responsible for oxidation of aldehyde (HCHO) to acid
is swamped allowing time for kidneys to excrete methanol (c) Reactions of phenols
Following reactions are shown by phenols only Rationalised 2023-24
211
Alcohols, Phenols and Ethers
1 Electrophilic aromatic substitution
In phenols, the reactions that take place on the aromatic ring are
electrophilic substitution reactions (Unit 9, Class XI) |
1 | 6159-6162 | (c) Reactions of phenols
Following reactions are shown by phenols only Rationalised 2023-24
211
Alcohols, Phenols and Ethers
1 Electrophilic aromatic substitution
In phenols, the reactions that take place on the aromatic ring are
electrophilic substitution reactions (Unit 9, Class XI) The –OH group
attached to the benzene ring activates it towards electrophilic
substitution |
1 | 6160-6163 | Rationalised 2023-24
211
Alcohols, Phenols and Ethers
1 Electrophilic aromatic substitution
In phenols, the reactions that take place on the aromatic ring are
electrophilic substitution reactions (Unit 9, Class XI) The –OH group
attached to the benzene ring activates it towards electrophilic
substitution 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 |
1 | 6161-6164 | Electrophilic aromatic substitution
In phenols, the reactions that take place on the aromatic ring are
electrophilic substitution reactions (Unit 9, Class XI) The –OH group
attached to the benzene ring activates it towards electrophilic
substitution 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 The resonance structures
are shown under acidity of phenols |
1 | 6162-6165 | The –OH group
attached to the benzene ring activates it towards electrophilic
substitution 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 The resonance structures
are shown under acidity of phenols 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 |
1 | 6163-6166 | 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 The resonance structures
are shown under acidity of phenols 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 The ortho and para isomers can be separated by steam
distillation |
1 | 6164-6167 | The resonance structures
are shown under acidity of phenols 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 The ortho and para isomers can be separated by steam
distillation 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 |
1 | 6165-6168 | 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 The ortho and para isomers can be separated by steam
distillation 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 |
1 | 6166-6169 | The ortho and para isomers can be separated by steam
distillation 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 product is commonly known as picric
acid |
1 | 6167-6170 | 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 product is commonly known as picric
acid The yield of the reaction product is poor |
1 | 6168-6171 | With concentrated nitric acid, phenol is converted to
2,4,6-trinitrophenol The product is commonly known as picric
acid The yield of the reaction product is poor Nowadays picric acid is prepared by treating phenol first
with concentrated sulphuric acid which converts it to
phenol-2,4-disulphonic acid, and then with concentrated nitric
acid to get 2,4,6-trinitrophenol |
1 | 6169-6172 | The product is commonly known as picric
acid The yield of the reaction product is poor Nowadays picric acid is prepared by treating phenol first
with concentrated sulphuric acid which converts it to
phenol-2,4-disulphonic acid, and then with concentrated nitric
acid to get 2,4,6-trinitrophenol Can you write the equations of
the reactions involved |
1 | 6170-6173 | The yield of the reaction product is poor Nowadays picric acid is prepared by treating phenol first
with concentrated sulphuric acid which converts it to
phenol-2,4-disulphonic acid, and then with concentrated nitric
acid to get 2,4,6-trinitrophenol Can you write the equations of
the reactions involved 2, 4, 6 - Trinitrophenol
is a strong acid due to
the presence of three
electron withdrawing
–NO2 groups which
facilitate the release of
hydrogen ion |
1 | 6171-6174 | Nowadays picric acid is prepared by treating phenol first
with concentrated sulphuric acid which converts it to
phenol-2,4-disulphonic acid, and then with concentrated nitric
acid to get 2,4,6-trinitrophenol Can you write the equations of
the reactions involved 2, 4, 6 - Trinitrophenol
is a strong acid due to
the presence of three
electron withdrawing
–NO2 groups which
facilitate the release of
hydrogen ion Rationalised 2023-24
212
Chemistry
(ii) Halogenation: On treating phenol with bromine, different reaction
products are formed under different experimental conditions |
1 | 6172-6175 | Can you write the equations of
the reactions involved 2, 4, 6 - Trinitrophenol
is a strong acid due to
the presence of three
electron withdrawing
–NO2 groups which
facilitate the release of
hydrogen ion Rationalised 2023-24
212
Chemistry
(ii) Halogenation: On treating phenol with bromine, different reaction
products are formed under different experimental conditions (a) When the reaction is carried out in solvents of low polarity
such as CHCl3 or CS2 and at low temperature,
monobromophenols are formed |
1 | 6173-6176 | 2, 4, 6 - Trinitrophenol
is a strong acid due to
the presence of three
electron withdrawing
–NO2 groups which
facilitate the release of
hydrogen ion Rationalised 2023-24
212
Chemistry
(ii) Halogenation: On treating phenol with bromine, different reaction
products are formed under different experimental conditions (a) When the reaction is carried out in solvents of low polarity
such as CHCl3 or CS2 and at low temperature,
monobromophenols are formed The usual halogenation of benzene takes place in the
presence of a Lewis acid, such as FeBr3 (Unit 6, Class XII),
which polarises the halogen molecule |
1 | 6174-6177 | Rationalised 2023-24
212
Chemistry
(ii) Halogenation: On treating phenol with bromine, different reaction
products are formed under different experimental conditions (a) When the reaction is carried out in solvents of low polarity
such as CHCl3 or CS2 and at low temperature,
monobromophenols are formed The usual halogenation of benzene takes place in the
presence of a Lewis acid, such as FeBr3 (Unit 6, Class XII),
which polarises the halogen molecule In case of phenol, the
polarisation of bromine molecule takes place even in the
absence of Lewis acid |
1 | 6175-6178 | (a) When the reaction is carried out in solvents of low polarity
such as CHCl3 or CS2 and at low temperature,
monobromophenols are formed The usual halogenation of benzene takes place in the
presence of a Lewis acid, such as FeBr3 (Unit 6, Class XII),
which polarises the halogen molecule In case of phenol, the
polarisation of bromine molecule takes place even in the
absence of Lewis acid It is due to the highly activating
effect of –OH group attached to the benzene ring |
1 | 6176-6179 | The usual halogenation of benzene takes place in the
presence of a Lewis acid, such as FeBr3 (Unit 6, Class XII),
which polarises the halogen molecule In case of phenol, the
polarisation of bromine molecule takes place even in the
absence of Lewis acid It is due to the highly activating
effect of –OH group attached to the benzene ring (b) When
phenol
is
treated
with
bromine
water,
2,4,6-tribromophenol is formed as white precipitate |
1 | 6177-6180 | In case of phenol, the
polarisation of bromine molecule takes place even in the
absence of Lewis acid It is due to the highly activating
effect of –OH group attached to the benzene ring (b) When
phenol
is
treated
with
bromine
water,
2,4,6-tribromophenol is formed as white precipitate Write the structures of the major products expected from the following
reactions:
(a) Mononitration of 3-methylphenol
(b) Dinitration of 3-methylphenol
(c) Mononitration of phenyl methanoate |
1 | 6178-6181 | It is due to the highly activating
effect of –OH group attached to the benzene ring (b) When
phenol
is
treated
with
bromine
water,
2,4,6-tribromophenol is formed as white precipitate Write the structures of the major products expected from the following
reactions:
(a) Mononitration of 3-methylphenol
(b) Dinitration of 3-methylphenol
(c) Mononitration of phenyl methanoate The combined influence of –OH and –CH3 groups determine the
position of the incoming group |
1 | 6179-6182 | (b) When
phenol
is
treated
with
bromine
water,
2,4,6-tribromophenol is formed as white precipitate Write the structures of the major products expected from the following
reactions:
(a) Mononitration of 3-methylphenol
(b) Dinitration of 3-methylphenol
(c) Mononitration of phenyl methanoate The combined influence of –OH and –CH3 groups determine the
position of the incoming group Example 7 |
1 | 6180-6183 | Write the structures of the major products expected from the following
reactions:
(a) Mononitration of 3-methylphenol
(b) Dinitration of 3-methylphenol
(c) Mononitration of phenyl methanoate The combined influence of –OH and –CH3 groups determine the
position of the incoming group Example 7 5
Example 7 |
1 | 6181-6184 | The combined influence of –OH and –CH3 groups determine the
position of the incoming group Example 7 5
Example 7 5
Example 7 |
1 | 6182-6185 | Example 7 5
Example 7 5
Example 7 5
Example 7 |
1 | 6183-6186 | 5
Example 7 5
Example 7 5
Example 7 5
Example 7 |
1 | 6184-6187 | 5
Example 7 5
Example 7 5
Example 7 5
Solution
Solution
Solution
Solution
Solution
2 |
1 | 6185-6188 | 5
Example 7 5
Example 7 5
Solution
Solution
Solution
Solution
Solution
2 Kolbe’s reaction
Phenoxide ion generated by treating phenol with sodium hydroxide
is even more reactive than phenol towards electrophilic aromatic
substitution |
1 | 6186-6189 | 5
Example 7 5
Solution
Solution
Solution
Solution
Solution
2 Kolbe’s reaction
Phenoxide ion generated by treating phenol with sodium hydroxide
is even more reactive than phenol towards electrophilic aromatic
substitution Hence, it undergoes electrophilic substitution with
carbon dioxide, a weak electrophile |
1 | 6187-6190 | 5
Solution
Solution
Solution
Solution
Solution
2 Kolbe’s reaction
Phenoxide ion generated by treating phenol with sodium hydroxide
is even more reactive than phenol towards electrophilic aromatic
substitution Hence, it undergoes electrophilic substitution with
carbon dioxide, a weak electrophile Ortho hydroxybenzoic acid is
formed as the main reaction product |
1 | 6188-6191 | Kolbe’s reaction
Phenoxide ion generated by treating phenol with sodium hydroxide
is even more reactive than phenol towards electrophilic aromatic
substitution Hence, it undergoes electrophilic substitution with
carbon dioxide, a weak electrophile Ortho hydroxybenzoic acid is
formed as the main reaction product Rationalised 2023-24
213
Alcohols, Phenols and Ethers
3 |
1 | 6189-6192 | Hence, it undergoes electrophilic substitution with
carbon dioxide, a weak electrophile Ortho hydroxybenzoic acid is
formed as the main reaction product Rationalised 2023-24
213
Alcohols, Phenols and Ethers
3 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 |
1 | 6190-6193 | Ortho hydroxybenzoic acid is
formed as the main reaction product Rationalised 2023-24
213
Alcohols, Phenols and Ethers
3 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 This reaction is known as Reimer - Tiemann reaction |
1 | 6191-6194 | Rationalised 2023-24
213
Alcohols, Phenols and Ethers
3 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 This reaction is known as Reimer - Tiemann reaction The intermediate substituted benzal chloride is hydrolysed in the
presence of alkali to produce salicylaldehyde |
1 | 6192-6195 | 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 This reaction is known as Reimer - Tiemann reaction The intermediate substituted benzal chloride is hydrolysed in the
presence of alkali to produce salicylaldehyde 4 |
1 | 6193-6196 | This reaction is known as Reimer - Tiemann reaction The intermediate substituted benzal chloride is hydrolysed in the
presence of alkali to produce salicylaldehyde 4 Reaction of phenol with zinc dust
Phenol is converted to benzene on heating with zinc dust |
1 | 6194-6197 | The intermediate substituted benzal chloride is hydrolysed in the
presence of alkali to produce salicylaldehyde 4 Reaction of phenol with zinc dust
Phenol is converted to benzene on heating with zinc dust 5 |
1 | 6195-6198 | 4 Reaction of phenol with zinc dust
Phenol is converted to benzene on heating with zinc dust 5 Oxidation
Oxidation of phenol with chromic
acid produces a conjugated diketone
known as benzoquinone |
1 | 6196-6199 | Reaction of phenol with zinc dust
Phenol is converted to benzene on heating with zinc dust 5 Oxidation
Oxidation of phenol with chromic
acid produces a conjugated diketone
known as benzoquinone In the
presence of air, phenols are slowly
oxidised to dark coloured mixtures
containing quinones |
1 | 6197-6200 | 5 Oxidation
Oxidation of phenol with chromic
acid produces a conjugated diketone
known as benzoquinone In the
presence of air, phenols are slowly
oxidised to dark coloured mixtures
containing quinones 7 |
1 | 6198-6201 | Oxidation
Oxidation of phenol with chromic
acid produces a conjugated diketone
known as benzoquinone In the
presence of air, phenols are slowly
oxidised to dark coloured mixtures
containing quinones 7 6
Give structures of the products you would expect when each of the
following alcohol reacts with (a) HCl –ZnCl2 (b) HBr and (c) SOCl2 |
1 | 6199-6202 | In the
presence of air, phenols are slowly
oxidised to dark coloured mixtures
containing quinones 7 6
Give structures of the products you would expect when each of the
following alcohol reacts with (a) HCl –ZnCl2 (b) HBr and (c) SOCl2 (i) Butan-1-ol
(ii) 2-Methylbutan-2-ol
7 |
1 | 6200-6203 | 7 6
Give structures of the products you would expect when each of the
following alcohol reacts with (a) HCl –ZnCl2 (b) HBr and (c) SOCl2 (i) Butan-1-ol
(ii) 2-Methylbutan-2-ol
7 7
Predict the major product of acid catalysed dehydration of
(i) 1-methylcyclohexanol and
(ii) butan-1-ol
7 |
1 | 6201-6204 | 6
Give structures of the products you would expect when each of the
following alcohol reacts with (a) HCl –ZnCl2 (b) HBr and (c) SOCl2 (i) Butan-1-ol
(ii) 2-Methylbutan-2-ol
7 7
Predict the major product of acid catalysed dehydration of
(i) 1-methylcyclohexanol and
(ii) butan-1-ol
7 8
Ortho and para nitrophenols are more acidic than phenol |
1 | 6202-6205 | (i) Butan-1-ol
(ii) 2-Methylbutan-2-ol
7 7
Predict the major product of acid catalysed dehydration of
(i) 1-methylcyclohexanol and
(ii) butan-1-ol
7 8
Ortho and para nitrophenols are more acidic than phenol Draw the
resonance structures of the corresponding phenoxide ions |
1 | 6203-6206 | 7
Predict the major product of acid catalysed dehydration of
(i) 1-methylcyclohexanol and
(ii) butan-1-ol
7 8
Ortho and para nitrophenols are more acidic than phenol Draw the
resonance structures of the corresponding phenoxide ions 7 |
1 | 6204-6207 | 8
Ortho and para nitrophenols are more acidic than phenol Draw the
resonance structures of the corresponding phenoxide ions 7 9
Write the equations involved in the following reactions:
(i) Reimer - Tiemann reaction
(ii) Kolbe’s reaction
Intext Questions
Intext Questions
Intext Questions
Intext Questions
Intext Questions
Rationalised 2023-24
214
Chemistry
Methanol and ethanol are among the two commercially important
alcohols |
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