Derivatives of Carboxylic Acids and Nucleophilic Acyl Substitution

1
Derivatives of Carboxylic Acids and Nucleophilic
Acyl Substitution
32.1 Introduction 32.2 Nomenclature of Carboxylic
Acids and their Derivatives 32.3 Physical
Properties of Carboxylic Acids 32.4 Preparation
of Carboxylic Acids 32.5 Reactions of Carboxylic
Acids 32.6 Reactions of the Derivatives of
Carboxylic Acids
2
Introduction
3
32.1 Introduction (SB p.22)
Carboxylic Acids

• A class of organic compounds containing the
  carboxyl group

4
32.1 Introduction (SB p.22)
Carboxylic Acids

• Carboxyl group
• ? combination of the carbonyl group and the
  hydroxyl group

5
32.1 Introduction (SB p.22)
Carboxylic Acids

• Examples of carboxylic acids

6
32.1 Introduction (SB p.23)
Carboxylic Acids

• The carboxyl group is the parent group of a large
  family of compounds
• ? called carboxylic acid derivatives

7
32.1 Introduction (SB p.23)
Carboxylic acid derivatives
8
Nomenclature of Carboxylic Acids and their
Derivatives
9
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.23)
Carboxylic Acids

• Carboxylic acids are named by
• ? replacing the final letter -e of the name
  of the corresponding alkane with -oic acid
• The carboxyl group must be located at the end of
  the carbon chain
• ? no need to indicate its position

10
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.23)
Carboxylic Acids

• e.g.

11
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.24)
Acid Anhydrides

• Acid anhydrides are named by
• ? dropping the word acid from the name of the
  parent carboxylic acid
• ? then adding the word anhydride

12
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.24)
Acid Anhydrides

• e.g.

13
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.24)
Acyl Chlorides

• Acyl chlorides are also called acid chlorides
• They are named by
• ? dropping -ic acid from the name of the
  parent carboxylic acid
• ? then adding -yl chloride

14
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.24)
Acyl Chlorides

• e.g.

15
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.24)
Esters

• The names of esters are derived from
• ? the names of the alcohol (with the ending
  -anol replaced by -yl) and the carboxylic
  acid (with the ending -oic acid replaced by
  -oate)
• The portion of the name derived from the alcohol
  comes first

16
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.24)
Esters

• e.g.

17
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.25)
Amides

• Amides that have no substituent on the nitrogen
  atom
• ? named by dropping -oic acid from the name
  of the parent carboxylic acid
• ? then adding the word -amide

18
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.25)
Amides

• Substituents on the nitrogen atom of amides are
  named
• The name of the substituent is preceded by N-, or
  N, N-

19
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.25)
Amides

• e.g.

20
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.25)
21
Physical Properties of Carboxylic Acids
22
32.3 Physical Properties of Carboxylic Acids (SB
p.27)
Physical Properties of Carboxylic Acids

• Carboxylic acids have a characteristic pungent
  smell and sour taste
• e.g.
• ? ethanoic acid has the smell of vinegar
• ? butanoic acid has the smell of rancid oil

23
32.3 Physical Properties of Carboxylic Acids (SB
p.27)
Physical properties of some carboxylic acids
24
32.3 Physical Properties of Carboxylic Acids (SB
p.27)
Physical properties of some carboxylic acids
25
32.3 Physical Properties of Carboxylic Acids (SB
p.27)
Physical properties of some carboxylic acids
26
32.3 Physical Properties of Carboxylic Acids (SB
p.27)
Physical properties of some carboxylic acids
27
32.3 Physical Properties of Carboxylic Acids (SB
p.28)
Boiling Point and Melting Point

• Like alcohols, molecules of carboxylic acids are
  capable of forming intermolecular hydrogen bonds
  with each other
• ? both alcohols and carboxylic acids have
  relatively high b.p. and m.p.

28
32.3 Physical Properties of Carboxylic Acids (SB
p.28)
Boiling Point and Melting Point

• Molecules of carboxylic acids can form more
  extensive intermolecular hydrogen bonds than
  those of alcohols

29
32.3 Physical Properties of Carboxylic Acids (SB
p.28)
Boiling Point and Melting Point

• The b.p. and m.p. of carboxylic acids are higher
  than those of alcohols of similar relative
  molecular masses

30
32.3 Physical Properties of Carboxylic Acids (SB
p.28)
Variations of boiling points with the number of
carbon atoms of straight-chain carboxylic acids,
alcohols, aldehydes and alkanes
31
32.3 Physical Properties of Carboxylic Acids (SB
p.28)
Density

• The densities of carboxylic acids generally
  decrease with increasing relative molecular
  masses
• Only the first two members are denser than water
  at 20C
• ? due to the closer packing of the smaller
  molecules in the liquid phase

32
32.3 Physical Properties of Carboxylic Acids (SB
p.29)
Solubility

• Carboxylic acids of low molecular masses show
  appreciable solubilities in water
• ? Carboxylic acids are polar and their
  molecules can form strong hydrogen bonds with
  water molecules

33
32.3 Physical Properties of Carboxylic Acids (SB
p.29)
Solubility

• The first four members of carboxylic acids are
  miscible with water in all proportions
• When the length of the hydrocarbon portion
  increases
• ? the solubility of the carboxylic acids in
  water declines

34
Preparation of Carboxylic Acids
35
32.4 Preparation of Carboxylic Acids (SB p.30)
Hydrolysis of Nitriles

• Aldehydes and ketones can be converted to
  2-hydroxyalkanenitriles
• ? by the nucleophilic addition reaction of
  hydrogen cyanide

36
32.4 Preparation of Carboxylic Acids (SB p.30)
Hydrolysis of Nitriles

• On hydrolysis of the nitrile, a carboxylic acid
  or a carboxylate ion is produced
• ? depending on whether the hydrolysis occurs in
  an acidic or a basic medium

37
32.4 Preparation of Carboxylic Acids (SB p.30)
Hydrolysis of Nitriles
38
32.4 Preparation of Carboxylic Acids (SB p.30)
Hydrolysis of Nitriles

• Nitriles can also be prepared by the nucleophilic
  substitution reaction of haloalkanes with sodium
  cyanide
• Acid hydrolysis of the nitrile yields a
  carboxylic acid with one carbon atom more than
  the starting haloalkane

39
32.4 Preparation of Carboxylic Acids (SB p.30)
Hydrolysis of Nitriles

• The general equation is

40
32.4 Preparation of Carboxylic Acids (SB p.30)
Hydrolysis of Nitriles

• e.g.

41
32.4 Preparation of Carboxylic Acids (SB p.31)
Hydrolysis of Esters

• Boiling the esters under reflux with dilute HCl
  or dilute H2SO4 give the parent carboxylic acids

42
32.4 Preparation of Carboxylic Acids (SB p.31)
Hydrolysis of Esters

• All carboxylic acid derivatives including acyl
  chlorides, acid anhydrides, esters and amides can
  be hydrolyzed
• ? give the corresponding carboxylic acids
• They undergo the hydrolysis under different
  conditions

43
32.4 Preparation of Carboxylic Acids (SB p.31)
Hydrolysis of Esters

• The more reactive derivatives like acyl chlorides
  react vigorously with water to give the
  corresponding carboxylic acids
• The less reactive derivatives like amides require
  more severe conditions for the reaction to occur

44
32.4 Preparation of Carboxylic Acids (SB p.31)
Oxidation of Alcohols and Aldehydes

• Aldehydes and 1o alcohols can be oxidized to
  carboxylic acids
• ? by strong oxidizing agents such as potassium
  manganate(VII)

45
32.4 Preparation of Carboxylic Acids (SB p.31)
Oxidation of Alcohols and Aldehydes
46
32.4 Preparation of Carboxylic Acids (SB p.31)
Oxidation of Alcohols and Aldehydes

• e.g.

47
32.4 Preparation of Carboxylic Acids (SB p.32)
Oxidation of Alkylbenzenes

• 1o and 2o alkyl groups (but not 3o alkyl groups)
  directly attached to a benzene ring are oxidized
  by hot alkaline KMnO4 to the carboxyl group

48
32.4 Preparation of Carboxylic Acids (SB p.32)
Oxidation of Alkylbenzenes

• e.g.

49
32.4 Preparation of Carboxylic Acids (SB p.32)
Oxidation of Alkylbenzenes

• Alkylbenzenes with alkyl groups other than methyl
  group are also oxidized to benzoic acid by hot
  alkaline KMnO4

50
Reactions of Carboxylic Acids
51
32.5 Reactions of Carboxylic Acids (SB p.32)
Acidity of Carboxylic Acids

• Carboxylic acids are weak acids
• The acidic properties of carboxylic acids are due
  to
• ? the presence of the ionizable hydrogen atom
  in the carboxyl group

52
32.5 Reactions of Carboxylic Acids (SB p.32)
Acidity of Carboxylic Acids

• e.g. In water, ethanoic acid molecules
  dissociate into ions

53
32.5 Reactions of Carboxylic Acids (SB p.32)
Acidity of Carboxylic Acids

• The acid strength of ethanoic acid is shown by
  the value of its acid dissociation constant (Ka)

54
32.5 Reactions of Carboxylic Acids (SB p.33)
Acidity of Carboxylic Acids

• For weak acids such as ethanoic acid
• ? the Ka values are very small
• It is more convenient to express the Ka by pKa
• ? pKa log Ka
• The smaller the value of pKa, the stronger the
  acid

55
32.5 Reactions of Carboxylic Acids (SB p.33)
Acidity of Carboxylic Acids

• Carboxylic acids are much more acidic than
  alcohols
• Unsubstituted carboxylic acids have pKa values in
  the range of 3 to 5
• Alcohols have pKa values in the range of 15 to 18

56
32.5 Reactions of Carboxylic Acids (SB p.33)
Acidity of Carboxylic Acids
pKa values of some common carboxylic acids
57
32.5 Reactions of Carboxylic Acids (SB p.33)
Formation of Salts
1. Reaction with Reactive Metals

• Carboxylic acids react with reactive metals such
  as Na or Mg
• ? form the corresponding metal carboxylates and
  hydrogen gas

58
32.5 Reactions of Carboxylic Acids (SB p.33)
1. Reaction with Reactive Metals
59
32.5 Reactions of Carboxylic Acids (SB p.33)
1. Reaction with Reactive Metals

• e.g.

60
32.5 Reactions of Carboxylic Acids (SB p.34)
2. Reaction with Bases

• Carboxylic acids react with strong alkalis such
  as NaOH
• ? form sodium carboxylates and water

61
32.5 Reactions of Carboxylic Acids (SB p.34)
2. Reaction with Bases

• e.g.

62
32.5 Reactions of Carboxylic Acids (SB p.34)
2. Reaction with Bases

• Carboxylic acids also react with weak alkalis
  such as Na2CO3 or NaHCO3
• ? form sodium carboxylates, carbon dioxide and
  water

63
32.5 Reactions of Carboxylic Acids (SB p.34)
2. Reaction with Bases

• e.g.

64
32.5 Reactions of Carboxylic Acids (SB p.35)
2. Reaction with Bases

• This reaction provides an important test to
  distinguish between carboxylic acids and other
  acidic organic compounds such as phenols
• Phenols are weaker acids than carboxylic acids

65
32.5 Reactions of Carboxylic Acids (SB p.35)
2. Reaction with Bases

• Phenols react with NaOH, but they do not react
  with NaHCO3

66
32.5 Reactions of Carboxylic Acids (SB p.35)
Reaction with Thionyl Chloride/Phosphorus
Trichloride/Phosphorus Pentachloride

• Carboxylic acids react with SOCl2, PCl3 or PCl5
• ? give acyl chlorides in good yield
• ? one of the methods for preparing acyl
  chlorides

67
32.5 Reactions of Carboxylic Acids (SB p.35)
Reaction with Thionyl Chloride/Phosphorus
Trichloride/Phosphorus Pentachloride
68
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Thionyl Chloride/Phosphorus
Trichloride/Phosphorus Pentachloride

• Acyl chlorides can be used to prepare aldehydes,
  ketones, esters, amides and acid anhydrides

69
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Thionyl Chloride/Phosphorus
Trichloride/Phosphorus Pentachloride

• Acyl chlorides must be stored in anhydrous
  conditions
• ? they hydrolyze rapidly in the presence of
  even a trace amount of water to form carboxylic
  acids

70
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Alcohols

• Carboxylic acids react with alcohols to form
  esters through a condensation reaction
• ? known as esterification

71
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Alcohols

• Esterification reactions are
• ? acid-catalyzed
• ? reversible
• Proceed slowly in the absence of acids
• Addition of a small amount of conc. H2SO4
• ? the reaction can reach equilibrium within a
  few hours

72
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Alcohols

• The yield of the ester can be increased by
• ? using excess carboxylic acid or alcohol
• ? removing water from the reaction mixture

73
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Ammonia

• Carboxylic acids react with aqueous ammonia
• ? form ammonium salts

74
32.5 Reactions of Carboxylic Acids (SB p.36)
Reaction with Ammonia

• When we evaporate the water and subsequently heat
  the dry salt
• ? dehydration occurs
• ? an amide is formed

75
32.5 Reactions of Carboxylic Acids (SB p.37)
Reaction with Ammonia

• A poor method for preparing amides
• A much better method is to
• ? convert the carboxylic acid to an acyl
  chloride
• ? treat the acyl chloride with ammonia or an
  amine

76
32.5 Reactions of Carboxylic Acids (SB p.37)
Reaction with Acyl Chlorides

• Carboxylic acids react with acyl chlorides in the
  presence of pyridine
• ? give acid anhydrides

• Frequently used in the laboratory for the
  preparation of acid anhydrides

77
32.5 Reactions of Carboxylic Acids (SB p.37)
Reaction with Acyl Chlorides

• Sodium salts of carboxylic acids also react with
  acyl chlorides
• ? give acid anhydrides

78
Reactions of the Derivatives of Carboxylic Acids
79
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.38)
Reaction of Acyl Chlorides

• The acyl carbon atom is a good nucleophilic site
• ? both O and Cl atoms are electron- withdrawing
  groups
• ? makes the acyl carbon atom electron- deficient

80
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.38)
Reaction of Acyl Chlorides

• The most characteristic reaction of acyl
  chlorides is nucleophilic substitution reactions
  that take place at the acyl carbon atom

81
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.39)
1. Reaction with Water

• Acyl chlorides are hydrolyzed by water
• ? form the parent carboxylic acids and HCl

82
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.39)
1. Reaction with Water

• e.g.
• Ethanoyl chloride is readily hydrolyzed by water
  to give ethanoic acid

83
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.39)
General Mechanism of Nucleophilic Acyl
Substitution

• Take the hydrolysis of acyl chlorides as an
  example

84
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.39)
2. Reaction with Alcohols

• Acyl chlorides react with alcohols
• ? form esters and HCl

85
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.39)
2. Reaction with Alcohols

• e.g.
• Ethanoyl chloride reacts with methanol to form
  methyl ethanoate and HCl

86
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.40)
2. Reaction with Alcohols

• Phenols also react with acyl chlorides to form
  esters
• ? a base is required as a catalyst
• ? in an alkaline medium, phenol converts to a
  more powerful nucleophilic ion

87
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.40)
2. Reaction with Alcohols

• e.g.

88
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.40)
3. Reactions with Ammonia and Amines

• Acyl chlorides react with ammonia
• ? form amides rapidly

89
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.40)
3. Reactions with Ammonia and Amines

• e.g.
• Ethanoyl chloride reacts with ammonia to form
  ethanamide

90
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.40)
3. Reactions with Ammonia and Amines

• Acyl chlorides also react rapidly with 1o and 2o
  amines
• ? give N- and N, N-substituted amides
  respectively

91
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.40)
3. Reactions with Ammonia and Amines
92
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.41)
3. Reactions with Ammonia and Amines

• The reaction between acyl chlorides and amines
  (or ammonia)
• ? usually takes place at room temperature
• ? produces amides in high yields
• ? one of the most widely used laboratory
  methods for the synthesis of amides

93
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.41)
Hydrolysis of Acid Anhydrides

• Reactions of acid anhydrides are similar to those
  of acyl chlorides
• ? they are less reactive than acyl chlorides
• The reactions of acyl chlorides often produce
  hydrogen chloride
• The reactions of acid anhydrides often produce
  carboxylic acids

94
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.41)
Hydrolysis of Acid Anhydrides

• Acid anhydrides undergo hydrolysis
• ? form carboxylic acids

95
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.41)
Hydrolysis of Acid Anhydrides

• e.g.
• Ethanoic anhydride is hydrolyzed by water to
  form ethanoic acid

96
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.41)
Reactions of Esters
1. Acid-catalyzed Hydrolysis

• Reverse reaction of esterification
• Esters are hydrolyzed to form the corresponding
  carboxylic acids and alcohols

97
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
1. Acid-catalyzed Hydrolysis

• e.g.
• Propyl methanoate undergoes acid-catalyzed
  hydrolysis
• ? form methanoic acid and propan-1-ol

98
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
2. Alkali-catalyzed Hydrolysis

• When an ester is refluxed with an alkali such as
  NaOH(aq)
• ? the sodium salt of the carboxylic acid and
  the corresponding alcohol are produced

99
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
2. Alkali-catalyzed Hydrolysis

• e.g.
• Ethyl ethanoate undergoes hydrolysis in sodium
  hydroxide solution
• ? form sodium ethanoate and ethanol

100
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
2. Alkali-catalyzed Hydrolysis

• The reaction is used to make soap
• Fats or oils are triesters
• ? hydrolyzed by alkalis
• ? produce sodium carboxylates (i.e. soap)
• Sometimes called saponification

101
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
2. Alkali-catalyzed Hydrolysis
102
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
2. Alkali-catalyzed Hydrolysis

• Alkali-catalyzed hydrolysis is an irreversible
  reaction

103
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.43)
3. Reactions with Ammonia and Amines

• Esters react with ammonia to form amides

104
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.43)
3. Reactions with Ammonia and Amines

• e.g.
• Methyl ethanoate reacts with ammonia
• ? form ethanamide and methanol

105
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.43)
3. Reactions with Ammonia and Amines

• Esters react with 1o or 2o amines in a similar
  way
• ? form N-substituted and N, N- disubstituted
  amides respectively

106
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.43)
3. Reactions with Ammonia and Amines

• e.g.
• Methyl ethanoate reacts with propylamine (a 1o
  amine)
• ? give N-propylethanamide (a 2o amide)

107
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.44)
Reactions of Amides

• Amides are the least reactive carboxylic acid
  derivative towards nucleophilic substitution
  reactions
• ? NH2 ion (NHR or NR2 ion) is a strong base
• ? thus a poor leaving group

108
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.44)
1. Hydrolysis of Amides

• When amides are heated with an aqueous acid or an
  aqueous base
• ? undergo hydrolysis
• ? form carboxylic acids and carboxylates
  respectively

109
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.44)
Acid-catalyzed Hydrolysis
110
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.44)
Alkali-catalyzed Hydrolysis
111
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.44)
2. Dehydration of Amides

• Amides are dehydrated by
• ? heating with phosphorus(V) oxide (P4O10)
• ? form nitriles

112
The END
113
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.25)
Back
Example 32-2A
Give the IUPAC names for the following
compounds (a) (b) (c) (d)
(a) 3-Methylbutanoic acid (b) N-Methylethanamide (
c) Ethyl benzoate (d) Benzoic anhydride
Answer
114
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.26)
Example 32-2B
An ester is formed by reacting an alcohol with a
carboxylic acid. Draw the structural formulae of
the following esters and in each case, give the
names of the alcohol and the carboxylic acid that
form the ester. (a) Methyl ethanoate
Answer
115
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.26)
Back
Example 32-2B
An ester is formed by reacting an alcohol with a
carboxylic acid. Draw the structural formulae of
the following esters and in each case, give the
names of the alcohol and the carboxylic acid that
form the ester. (b) Ethyl methanoate
Answer
116
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.26)
Check Point 32-2
Answer
Complete the following table.
117
32.2 Nomenclature of Carboxylic Acids and their
Derivatives (SB p.26)
Check Point 32-2
Back
118
32.3 Physical Properties of Carboxylic Acids (SB
p.29)
Example 32-3
(a) Propanoic acid has a boiling point of 141C
which is considerably higher than that of
butan-1-ol (117C), although they have the same
molecular mass. Explain why.
Answer
119
32.3 Physical Properties of Carboxylic Acids (SB
p.29)
Example 32-3
120
32.3 Physical Properties of Carboxylic Acids (SB
p.29)
Example 32-3
(b) Arrange the following compounds in decreasing
order of solubility in water CH3CH2CH2COOH,
CH3CH2COOCH3, CH3COOH
Answer
(b) The solubility of the compounds in water
decreases in the order CH3COOH gt CH3CH2CH2COOH
gt CH3CH2COOCH3
121
32.3 Physical Properties of Carboxylic Acids (SB
p.29)
Example 32-3
(c) Propanedioic acid forms intramolecular
hydrogen bonds. Draw its structural formula,
showing clearly the formation of intramolecular
hydrogen bonds.
Answer
Back
122
32.4 Preparation of Carboxylic Acids (SB p.32)
Check Point 32-4
Write the chemical equations for the
acid-catalyzed and alkali-catalyzed hydrolyses of
each of the following compounds (a) Ethyl
butanoate
Answer
123
32.4 Preparation of Carboxylic Acids (SB p.32)
Check Point 32-4
Write the chemical equations for the
acid-catalyzed and alkali-catalyzed hydrolyses of
each of the following compounds (b) Propanamide
Answer
124
32.4 Preparation of Carboxylic Acids (SB p.32)
Back
Check Point 32-4
Write the chemical equations for the
acid-catalyzed and alkali-catalyzed hydrolyses of
each of the following compounds (c) Benzoyl
chloride
Answer
125
32.5 Reactions of Carboxylic Acids (SB p.35)
Check Point 32-5
Outline how a mixture of butanone and ethanoic
acid can be separated in the laboratory.
Answer
Back
126
32.5 Reactions of Carboxylic Acids (SB p.37)
Example 32-5
Answer
127
32.5 Reactions of Carboxylic Acids (SB p.37)
Example 32-5
128
32.5 Reactions of Carboxylic Acids (SB p.37)
Example 32-5
Answer
129
32.5 Reactions of Carboxylic Acids (SB p.37)
Example 32-5
Back
130
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.41)
Check Point 32-6
Explain why ethanoyl chloride must be protected
from atmospheric moisture during storage.
Answer
This is because ethanoyl chloride reacts readily
with water (from atmospheric moisture) to form
ethanoic acid.
Back
131
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.42)
Let's Think 1
The characteristic reaction of the derivatives of
carboxylic acids is nucleophilic acyl
substitution. Arrange the derivatives of
carboxylic acids in decreasing order of
reactivity towards nucleophilic acyl substitution.
Answer
Acyl chlorides gt acid anhydrides gt esters gt amides
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132
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.45)
Example 32-6
Draw the structural formulae of the missing
compounds A to H (a) (b) (c)
Answer
133
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.45)
Example 32-6
134
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.45)
Example 32-6
Draw the structural formulae of the missing
compounds A to H (d) (e) (f)
Answer
135
32.6 Reactions of the Derivatives of Carboxylic
Acids (SB p.45)
Back
Example 32-6