1 of 214

12C12

​

Aldehydes, Ketones

and

Carboxylic Acids

2 of 214

Vanillin

|

 

Acetone

Benzaldehyde

Acetic Acid

The world of tastes and fragrances

3 of 214

Aldehyde

Ketone

Carboxylic Acid

Acid Anhydride

Acyl halide

Ester

Amide

4 of 214

12C12.1

​

Preparation of

Aldehydes and Ketones

5 of 214

12C12.1 Preparation of Aldehydes and Ketones

Learning Objectives

​

Nomenclature of Aldehydes and Ketones

​

Preparation of Aldehydes

​

Preparation of Ketones

6 of 214

12C12.1

​

CV 1

​

Nomenclature of

Aldehydes and Ketones

7 of 214

Common Names of Aldehydes

 

Acetaldehyde

Benzaldehyde

Salicyldehyde

 

 

 

 

 

 

 

 

8 of 214

IUPAC Names of Aldehydes

Suffix -al

Ethanal

Cyclohexanecarbaldehyde

Pent-2-enal

2-Hydroxybenzaldehyde

4-Hydroxy-3-methoxybenzaldehyde

9 of 214

Common Names of Ketones

 

Acetone

Acetophenone

Benzophenone

 

 

 

 

 

 

10 of 214

IUPAC Names of Ketones

 

 

Propanone

1-Phenylpropan-1-one

3-Methylcyclopentanone

5-Bromo-4-methyloctan-2-one

Suffix -one

11 of 214

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12 of 214

Q. Write the IUPAC names of following compounds:

Pause the video

Time duration: 3 minutes

 

 

 

 

 

 

 

 

 

 

 

 

a.

b.

c.

13 of 214

Q. Write the IUPAC names of following compounds:

 

 

 

 

 

 

 

 

 

 

 

 

a.

b.

c.

1

2

3

4

5

6

1

2

3

4

1

2

3

4

5

2-Methylhexan-3-one

3-Methyl-4-phenylbutan-1-al

4-Methyl-3-oxopentan-1-al

Sol.

14 of 214

12C12.1

​

CV 2

​

Preparation of Aldehydes-I

15 of 214

Rosenmund Reaction

 

Mechanism:

1. From Acyl chlorides:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Preparation of Aldehydes

 

Pd-Complex

 

16 of 214

Preparation of Aldehydes

 

Example:

 

 

 

 

 

 

Propanoyl chloride

Benzoyl chloride

Propanal

Benzaldehyde

 

17 of 214

2. From Nitriles and Esters:

 

Stephens Reactions

Mechanism:

 

 

 

 

 

Preparation of Aldehydes

Carbanion

 

18 of 214

2. From Nitriles and Esters:

 

Stephens Reactions

Mechanism:

 

 

 

 

 

 

 

 

Preparation of Aldehydes

Carbanion

  • Carbanions are highly unstable
  • Acid-base reaction

Imine

19 of 214

2. From Nitriles and Esters:

 

Stephens Reactions

Mechanism:

 

 

 

Preparation of Aldehydes

  • Acid-base reaction

20 of 214

2. From Nitriles and Esters:

 

Stephens Reactions

Mechanism:

 

 

 

 

 

Aldehyde

Preparation of Aldehydes

 

 

 

 

 

H

H

 

 

 

 

H

 

 

 

 

 

 

21 of 214

2. From Nitriles and Esters:

Stephens Reactions

Imine

 

 

 

 

Aldehyde

Preparation of Aldehydes

 

 

 

 

  • Esters are also reduced to aldehydes with DIBAL-H

 

22 of 214

Examples:

 

 

Preparation of Aldehydes

 

 

Benzonitrile

Benzaldehyde

Methylpropanoate

Propanal

23 of 214

3. From Alcohols:

Preparation of Aldehydes

 

 

 

Examples:

24 of 214

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25 of 214

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Time duration: 3 minutes

Q. How will you bring about the following conversions:

  1. Propylchloride to Butanal
  2. Ethene to Ethanal

26 of 214

Q. How will you bring about the following conversions:

  1. Propylchloride to Butanal
  2. Ethene to Ethanal

Sol.

  1. Propylchloride to Butanal

 

 

 

 

 

  1. Ethene to Ethanal

 

 

 

 

 

 

Nucleophilic Substitution

Stephen Reaction

Acidic Hydrolysis

Controlled Oxidation

27 of 214

12C12.1

​

CV 3

​

Preparation of Aldehydes-II

28 of 214

Preparation of Aldehydes

4. From Hydrocarbons:

a. Reductive Ozonolysis of Alkenes

Mechanism:

Ozonoid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Molo-ozonoid

 

 

 

29 of 214

Preparation of Aldehydes

4. From Hydrocarbons:

a. Reductive Ozonolysis of Alkenes

Mechanism:

Ozonoid

+ ZnO

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

+

 

 

 

 

 

 

 

Aldehydes

30 of 214

Preparation of Aldehydes

Examples:

 

 

 

 

 

 

 

 

2-Butene

Ethanal

2-Pentene

Ethanal

Propanal

31 of 214

4. From Hydrocarbons:

b. Etard Reaction

|

 

|

 

 

 

|

 

|

 

 

 

|

 

Mechanism:

Preparation of Aldehydes

Toluene

Benzaldehyde

Chromium Complex

32 of 214

 

 

|

 

 

 

 

|

 

 

 

 

 

4. From Hydrocarbons:

c. Gatterman-Koch Reaction

Mechanism:

Preparation of Aldehydes

Proton Transfer

Aromaticity regained

Fast

Slow

33 of 214

4. From Hydrocarbons:

d. Side Chain Chlorination followed by Hydrolysis:

|

 

|

 

 

 

|

 

This is the commercial method for the preparation of Benzaldehyde.

Preparation of Aldehydes

Benzal chloride

34 of 214

12C12.1

​

CV 4

​

Preparation of Ketones

35 of 214

Preparation of Ketones

1. From Acyl chlorides:

 

 

 

 

 

 

 

 

 

 

Acyl Chloride

Dialkylcadmium

Cadmium chloride

 

 

Mechanism:

 

Dialkylcadmium

 

36 of 214

Preparation of Ketones

1. From Acyl chlorides:

 

 

 

 

 

 

 

 

 

 

Acyl Chloride

Dialkylcadmium

Cadmium chloride

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mechanism:

Example:

 

Butan-2-one

Ethanoylchloride

Ethanemagnesiumchloride

 

37 of 214

Preparation of Ketones

2. From Nitriles and Esters:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mechanism:

Similarly, Esters react with Grignard’s reagent followed by hydrolysis to produce ketones:

1-Phenylbutanone

Methylbutanoate

38 of 214

Preparation of Ketones

3. From Benzene and its derivatives:

 

 

 

 

 

 

 

 

Friedel-Crafts Acylation Reaction

Example:

 

 

 

 

 

 

 

 

 

 

 

 

Toluene

o-substituted

(Major product)

(Minor product)

p-substituted

39 of 214

4. From Alcohols:

Preparation of Ketones

 

Examples:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Prop-2-ol

Propanone

40 of 214

Summary

 

 

 

 

 

 

 

 

 

|

 

|

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Preparation of Aldehydes

Preparation of Ketones

41 of 214

12C12.1 Preparation of Aldehydes and Ketones

Reference Questions

​

NCERT In-Text Questions: 12.1, 12.2

​

NCERT Exercise Questions: 12.2, 12.3, 12.4, 12.5

​

Workbook Questions: 2, 6, 7

42 of 214

12C12.2

​

Properties of

Aldehydes and Ketones

43 of 214

12C12.2 Properties of Aldehydes and Ketones

Learning Objectives

​

Physical Properties of Aldehydes and Ketones

​

Nucleophilic Addition Reactions

​

Reduction of Aldehydes and Ketones

​

Oxidation of Aldehydes and Ketones

44 of 214

12C12.2

​

CV 1

​

Physical Properties of

Aldehydes and Ketones

45 of 214

  • Methanal is a gas at room temperature whereas Ethanal is a volatile liquid.
  • Ketones up to carbon number 13 are volatile liquids.
  • Higher members of both aldehydes and Ketones are solids.
  • Lower aldehydes have unpleasant smell whereas ketones and higher aldehydes have fruity smells.

Physical Properties of Aldehydes and Ketones

46 of 214

 

 

 

 

 

 

 

 

 

 

 

 

Physical Properties of Aldehydes and Ketones

47 of 214

Structure of Carbonyl Group

 

 

 

 

 

 

p-orbitals

 

 

 

 

Polar bond

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nucleophiles prefer to attack

48 of 214

12C12.2

​

CV 2

​

Nucleophilic Addition Reactions-I

49 of 214

 

 

 

O

C

Nucleophilic Addition Reactions

 

Trigonal Planar

50 of 214

 

 

 

O

C

Nucleophilic Addition Reactions

51 of 214

C

 

Nu

Nucleophilic Addition Reactions

 

52 of 214

C

 

Nu

 

Nucleophilic Addition Reactions

Tetrahedral

Counter part of attacking agent or proton from water

53 of 214

H

C

O

Nu

Nucleophilic Addition Reactions

Nucleophilic Addition Product

54 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Aldehydes are generally more reactive than ketones in nucleophilic addition reactions.

 

 

 

 

 

 

 

 

Less hindrance

More hindrance

More electron deficiency at carbon

Less electron deficiency at carbon

Nucleophilic Addition Reactions

55 of 214

a. Addition of hydrogen cyanide (HCN):

Nucleophilic Addition Reactions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cyanohydrin

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2-Hdroxycarboxylic acid

2-Hdroxy amine

56 of 214

 

Nucleophilic Addition Reactions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Due to steric hindrance rate of reaction in case of ketones is very slow.
  • Used for separation and purification of aldehydes.

Hydrogensulphite addition compound (crystalline)

 

 

 

 

 

 

 

 

 

57 of 214

 

 

 

 

c. Addition of Grignard Reagents:

Nucleophilic Addition Reactions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

58 of 214

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59 of 214

Q. Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions.

(i) Ethanal, Propanal, Propanone, Butanone.

(ii) Benzaldehyde, p-Tolualdehyde, p-Nitrobenzaldehyde, Acetophenone.

Hint: Consider steric effect and electronic effect.

Pause the video

Time duration: 2 minutes

60 of 214

Q. Arrange the following compounds in increasing order of their reactivity in nucleophilic addition reactions.

(i) Ethanal, Propanal, Propanone, Butanone.

(ii) Benzaldehyde, p-Tolualdehyde, p-Nitrobenzaldehyde, Acetophenone.

Hint: Consider steric effect and electronic effect.

Sol.

(i)

(ii)

-M/-I

+M/+I

Ethanal > Propanal > Propanone > Butanone

p-Nitrobenzaldehyde > Benzaldehyde > p-Tolualdehyde > Acetophenone

>

61 of 214

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62 of 214

Q. Identify the final product of following reaction:

 

 

 

 

 

 

 

 

Pause the video

Time duration: 3 minutes

 

 

63 of 214

Q. Identify the final product of following reaction:

 

 

 

 

 

 

 

 

Sol.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cyclic ether

2-Methyltetrahydrofuran

64 of 214

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65 of 214

Pause the video

Time duration: 2 minutes

Q. Ethereal solution of an organic compound ‘A’ when heated with magnesium gave ‘B’ on treatment with ethanal followed by acid hydrolysis gave 2‐propanol. Identify the compound ‘A’. What is ‘B’ known as?

66 of 214

Q. Ethereal solution of an organic compound ‘A’ when heated with magnesium gave ‘B’ on treatment with ethanal followed by acid hydrolysis gave 2‐propanol. Identify the compound ‘A’. What is ‘B’ known as?

 

 

 

 

 

 

 

 

 

Grignard’s reagents are formed when alkyl bromide is treated with Mg

A

Methylbromide

Sol.

B

Methylmagnesiumbromide

67 of 214

12C12.2

​

CV 3

​

Nucleophilic Addition Reactions-II

68 of 214

d. Addition of Alcohols:

Nucleophilic Addition Reactions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hemiacetal

Acetal

gem-dialkoxy compound

  • Dry hydrogen chloride protonates the oxygen of the carbonyl group.
  • Similarly ketones react with alcohols to give ketals.
  • Acetals/ketals are hydrolysed with aqueous mineral acids to yield corresponding aldehydes and ketones respectively,

 

 

 

 

 

 

69 of 214

d. Addition of Alcohols:

Nucleophilic Addition Reactions

  • Acetals/ketals are less reactive towards oxidation/reduction, Hence these are used as protecting group for carbonyl compounds.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Ethylene glycol is commonly used as protecting reagent.

70 of 214

d. Reaction with Ammonia and its derivatives:

Nucleophilic Addition Reactions

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Imine

 

71 of 214

 

 

 

 

 

 

Nucleophilic Addition Reactions

i. Reaction with amine:

 

 

 

 

 

 

ii. Reaction with Hydroxylamine:

Substituted imine

(Schiff’s base)

 

 

 

 

 

 

Oxime

Hydroxylamine

Amine

 

 

 

 

 

 

 

 

 

 

 

 

72 of 214

Nucleophilic Addition Reactions

iii. Reaction with Hydrazine:

 

 

 

 

 

 

Hydrazone

Hydrazine

iv. Reaction with Phenylhydrazine:

 

Phenylhydrazone

Phenylhydrazine

 

 

 

 

 

 

 

 

 

 

 

 

 

73 of 214

Nucleophilic Addition Reactions

v. Reaction with 2,4-Dinitrophenylhydrazine:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Orange-red precipitate

2,4-Dinitrophenylhydrazine

2,4-Dinitrophenylhydrazone

  • Used for test of the carbonyl group, also know as 2,4-DNP Test

74 of 214

Nucleophilic Addition Reactions

vi. Reaction with Semicarbazide:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Semicarbazide

Semicarbazone

 

 

 

 

1

2

3

Q. Why does N-1 attack on the carbonyl group not N-2 or N-3?

Pause the video

Time duration: 2 minutes

75 of 214

 

 

 

 

1

2

3

Sol.

 

 

 

 

1

2

3

 

76 of 214

12C12.2

​

CV 4

​

Reduction of Aldehydes and Ketones

77 of 214

Reduction of Aldehydes and Ketones

1. Reduction to alcohols

 

 

 

 

 

 

 

 

 

 

 

  • Aldehydes form 1° alcohols
  • Ketones form 2° alcohols

78 of 214

Reduction of Aldehydes and Ketones

Example:

 

 

 

 

 

 

Pent-3-enal

Pent-1-ol

Pent-3-en-1-ol

79 of 214

Reduction of Aldehydes and Ketones

2. Reduction to hydrocarbons

a. Clemmensen Reduction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Zinc amalgam and HCl are used

80 of 214

Clemmensen Reduction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

`

 

  • Reaction occurs at zinc surface
  • Zinc being a metal has tendency to donate electrons
  • Clemmensen reduction is not applicable to keto alcohols, unsaturated cyclic ketones as these contain acid sensitive groups.

Mechanism:

81 of 214

b. Wolff-Kishner Reduction

Reduction of Aldehydes and Ketones

 

 

 

 

 

 

 

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Carbanion

82 of 214

b. Wolff-Kishner Reduction

Reduction of Aldehydes and Ketones

 

 

 

 

 

 

 

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

83 of 214

12C12.2

​

CV 5

​

Oxidation of Aldehydes and Ketones

84 of 214

Oxidation of Aldehydes and Ketones

 

 

 

 

 

 

 

 

 

 

  • Ketones are generally oxidised under vigorous conditions, i.e. strong oxidising agents and at elevated temperatures.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Popoff's Rule according to which carbonyl group of the unsymmetrical ketone remains with the smaller alkyl group preferentially.

85 of 214

Oxidation of Aldehydes and Ketones

  • Mild oxidising agents like tollen’s reagent and fehling solution can oxidise only aldehydes, hence used for the test of aldehydes.

a. Tollen’s Test (Silver Mirror Test)

 

Ammonical solution of Silver Nitrate

 

Tollen’s Reagent

Silver Mirror

  • Both aliphatic and aromatic aldehydes give Tollen’s Test.

86 of 214

Oxidation of Aldehydes and Ketones

 

 

 

 

 

 

 

 

 

 

 

 

 

b. Fehling Solution

 

 

 

 

 

 

 

 

 

 

 

 

Deep Blue complex

Red-Brown

  • Aromatic aldehydes do not respond to this test.

87 of 214

12C12.2

​

PSV 1

88 of 214

 

A

 

Tollen’s test

Aldehyde or Ketone

Ketone

 

 

 

 

 

 

 

 

 

 

 

 

 

Pentan-2-one

Pentan-3-one

Sol. 

89 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Kolbe’s Electrolysis

 

 

 

 

 

Butane

D

Propanoic Acid

Ethanoic Acid

Sol. 

 

Sodiumpropanoate

  • On Kolbe’s electrolysis salts of acids give alkanes

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92 of 214

 

Sol. 

A

Oxidation

Reduction

B

 

A is Ketone

  • Ketone on reduction give 2° Alcohol. So B is 2-Propanol

 

 

 

 

 

 

 

 

 

 

B

C

D

2-Bromopropane

Propene

 

 

 

93 of 214

Summary

  • The boiling points of aldehydes and ketones are higher than the hydrocarbons and ethers of comparable molecular masses.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Reaction with ammonia
  • Catalytic Reduction

94 of 214

Summary

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • Clemmensen Reduction
  • Wolff-Kishner Reduction
  • Oxidation Reaction

 

 

 

 

 

 

 

 

 

 

  • Tollen’s Test

 

Red-Brown

  • Fehling Solution Test

Silver Mirror

95 of 214

Reference Questions

​

NCERT In-Text Questions: 12.4, 12.5

​

NCERT Exercise Questions: 12.1, 12.5, 12.8, 12.18 (i & ii), 12.13 (i), 12.12 (i)

​

Workbook Questions: 4, 14, 20

12C12.2 Properties of Aldehydes and Ketones

96 of 214

 

97 of 214

 

 

98 of 214

 

99 of 214

C

O

R

C

H

H

H

 

 

100 of 214

C

O

R

C

H

H

H

Hyperconjugation

 

101 of 214

C

O

R

C

H

H

H

Hyperconjugation

 

102 of 214

C

 

R

 

 

H

H

Hyperconjugation

 

Enolate ion

103 of 214

C

O

R

C

H

H

H

Hyperconjugation

 

104 of 214

C

O

R

C

H

H

H

 

 

 

  • Aldehydes are more acidic than Ketones

 

 

 

 

 

 

 

 

+I

Less Acidic

105 of 214

 

Iodoform Reaction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mechanism:

 

Iodoform

Enolate ion

 

106 of 214

 

Iodoform Reaction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mechanism:

 

Iodoform

Enolate ion

107 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Iodoform

(Yellow Precipitate)

Iodoform Reaction

 

108 of 214

12C12.3

​

PSV 1

​

​

109 of 214

Q. Give simple chemical tests to distinguish between the following pairs of compounds.

  1. Propanal and Propanone
  2. Pentan-2-one and Pentan-3-one

110 of 214

 

Yellow ppt.

 

(ii) By iodoform test

 

 

 

 

 

 

 

 

Yellow ppt.

Pentan-2-one is a methyl ketone thus it responds to this test while Pentan-3-one not being a methyl ketone does not respond to this test

Sol.

 

111 of 214

12C12.3

​

CV 2

​

Aldol Condensation

112 of 214

Aldol Condensation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Aldol

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

113 of 214

Aldol Condensation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Aldol

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Aldol

 

114 of 214

Aldol Condensation

  • Aldols on heating undergo condensation to form unsaturated carbonyl compounds

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Trick to form direct aldol condensation product

 

Aldol condensation product

115 of 214

Cross-Aldol Condensation

 

 

 

 

 

 

 

 

 

 

 

Self condensation products

116 of 214

Cross-Aldol Condensation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • In case of cross-aldol, self condensation products are formed in major quantity.

Self condensation products

Cross condensation products

117 of 214

12C12.3

​

PSV 2

​

​

118 of 214

 

 

Major Product

 

 

 

 

 

 

Q.

A.

B.

C.

D.

Which of the following will the major product of above reaction:

119 of 214

 

 

Major Product

 

 

 

 

1

2

Q.

Sol.

 

 

 

 

 

 

 

 

 

 

 

 

More acidic

Less acidic

More Stable

Less Stable

 

 

Option D is correct

Option D is correct

120 of 214

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121 of 214

 

 

 

 

 

Major Product

A)

B)

C) Both will be formed in equal amount.

D) Need more information to predict major product.

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Time duration: 3 minutes

Q.

122 of 214

 

 

 

Major Product

Q.

 

 

Sol.

1

2

 

 

 

 

More stable

Less stable

 

 

 

 

Option A is correct

 

123 of 214

12C12.3

​

CV 3

​

Cannizzaro Reaction

124 of 214

Cannizzaro Reaction

 

Mechanism

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alcohol

Carboxylic Acid

125 of 214

Cannizzaro Reaction

Mechanism

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Benzyl alcohol

Benzoic acid

 

 

 

Alcohol

Carboxylic Acid

 

 

 

 

 

  • Usually, less hindered aldehyde gives oxidised product.

126 of 214

Q. During crossed-cannizzaro reaction less hindered aldehyde gives oxidised product. Explain why?

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127 of 214

Q. During crossed-cannizzaro reaction less hindered aldehyde gives oxidised product. Explain why?

Sol.

 

 

 

 

 

 

 

 

 

 

 

128 of 214

Electrophilic Aromatic Substitution Reaction

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

`

 

 

 

 

 

 

 

 

 

 

 

 

  • m-position is relatively less electron deficient hence electrophile prefer m-position

129 of 214

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130 of 214

Q. How will you bring about the following conversions in not more than two steps?

  1. Propanone to Propene
  2. Benzaldehyde to 3-Phenylpropan-1-ol

Pause the video

Time duration: 2 minutes

131 of 214

Q. How will you bring about the following conversions in not more than two steps?

  1. Propanone to Propene
  2. Benzaldehyde to 3-Phenylpropan-1-ol

Sol.

 

 

 

 

 

 

 

 

 

 

 

(ii)

(i)

Aldol condensation

132 of 214

12C12.3

​

CV 4

​

Uses of Aldehydes and Ketones

133 of 214

Uses of Aldehyde and Ketone

Aldehydes and ketones are used as

Biological specimen preservative

Solvent

To prepare Bakelite

Urea-Formaldehyde glues

134 of 214

Acetaldehyde is used primarily as a starting material in the manufacture

Uses of Aldehyde and Ketone

Acetic acid

Ethyl acetate

Vinyl acetate

Polymers

Drugs

135 of 214

Uses of Aldehyde and Ketone

Benzaldehyde is used in

Dye industries

Perfumery industries

Many aldehydes and ketones like butyraldehyde, vanillin, acetophenone, camphor etc. are well known for their odours and flavours

136 of 214

Summary

 

Iodoform Reaction:

Aldol Condensation:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Cannizzaro Reaction:

 

Electrophilic Aromatic Substitution Reaction:

 

 

 

 

 

 

 

 

 

137 of 214

Reference Questions

​

NCERT Exercise Questions: 12.7, 12.10, 12.13, 12.15 (i to vii), 12.16 (i, ii,iii), 12.19

​

Workbook Questions: 13, 19

 

138 of 214

12C12.4

​

Carboxylic Acid

&

It’s Preparation

139 of 214

12C12.4 Carboxylic Acid & It’s Preparation

Learning Objectives

​

Nomenclature of Carboxylic Acids

​

Preparation of Carboxylic Acids-I

​

Preparation of Carboxylic Acids-II

140 of 214

12C12.4

​

CV 1

​

Nomenclature of Carboxylic Acids

​

141 of 214

Nomenclature of Carboxylic Acids

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Formic Acid

Acetic Acid

Butyric Acid

Valeric Acid

Ant sting

Ant: Formica

Vinegar

Vinegar: Acetum

Butter

Butter: Butyrum

Valerian Plant

Common Names

142 of 214

Nomenclature of Carboxylic Acids

IUPAC Names

Suffix- oic acid

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Methanoic acid

Ethanoic acid

Butanoic acid

Pentanoic acid

 

 

 

 

 

 

 

 

 

 

 

 

2-Aminobutanoic acid

2,4-Dimethyl-3-oxopentanoic acid

4-Bromo-2-chlorobenzoic acid

3-Isopropylbenzoic acid

143 of 214

 

 

 

 

 

Nomenclature of Carboxylic Acids

 

 

 

 

 

 

 

 

 

Oxalic Acid

Ethanedioic acid

Propane-1,3-dioic acid

Butane-1,4-dioic acid

Pentane-1,5-dioic acid

Hexane-1,6-dioic acid

Propane-1,2,3-tricarboxylic acid

Malonic acid

Succinic acid

Gluteric acid

Adepic acid

144 of 214

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145 of 214

Q. Draw the structures of following compounds:

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Time duration: 2 minutes

  1. 4-Methoxy-2-isopropylpentanoic acid
  2. 3,5-Dihydroxybenzoic acid
  3. 3-Ethyl-6-oxohexanoic acid

146 of 214

Q. Draw the structures of following compounds:

  1. 4-Methoxy-2-isopropylpentanoic acid
  2. 3,5-Dihydroxybenzoic acid
  3. 3-Ethyl-6-oxohexanoic acid

Sol.

  1. 4-Methoxy-2-isopropylpentanoic acid

O

OH

 

147 of 214

Q. Draw the structures of following compounds:

  1. 4-Methoxy-2-isopropylpentanoic acid
  2. 3,5-Dihydroxybenzoic acid
  3. 3-Ethyl-6-oxohexanoic acid

Sol.

  1. 3,5-Dihydroxybenzoic acid

O

OH

OH

HO

  1. 3-Ethyl-6-oxohexanoic acid

OH

O

O

148 of 214

12C12.4

​

CV 2

​

Preparation of Carboxylic Acids-I

149 of 214

Preparation of Carboxylic Acids

1. From Primary Alcohols and Aldehydes

 

 

 

  • Carboxylic acids are also prepared from aldehydes by the use of mild oxidising agents like Tollen’s reagent or Fehling solution.

Example:

 

150 of 214

Preparation of Carboxylic Acids

2. From Alkylbenzenes

 

  • Primary and secondary alkyl groups are oxidised in this manner while tertiary group is not affected.

 

 

 

 

 

 

 

 

 

 

 

 

151 of 214

Preparation of Carboxylic Acids

3. From Nitriles and Amides

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

|

 

|

|

 

 

|

 

 

 

|

|

 

|

Mechanism

 

Amide

Carboxylic acid

Amide

152 of 214

Preparation of Carboxylic Acids

3. From Nitriles and Amides

 

 

 

 

 

 

 

 

 

 

 

 

|

|

 

 

|

 

|

|

 

|

 

 

|

 

|

|

 

|

 

|

 

 

|

|

 

Mechanism

Example:

 

 

 

 

 

 

 

Ethane nitrile

Ethanamide

Ethanoic acid

153 of 214

12C12.4

​

CV 3

​

Preparation of Carboxylic Acids-II

154 of 214

Preparation of Carboxylic Acids

4. From Acyl halides, Acid Anhydrides and Esters:

Acidic Hydrolysis

 

 

Examples:

 

 

Ethyl benzoate

Benzoic acid

Ethanol

  • Basic hydrolysis gives alcohol and carboxylate ion.

155 of 214

Preparation of Carboxylic Acids

5. From Grignard Reagents

 

 

 

|

|

 

 

 

 

|

|

 

 

Mechanism:

  • Step up reaction as number of C-atom increases in product.

Example:

 

Ethane magnesium chloride

Propanoic acid

156 of 214

6. From Alkenes and Alkynes

Preparation of Carboxylic Acids

 

 

 

  • C-atom with double bond must have atleast one hydrogen atom.
  • In case of unsymmetrical alkenes two carboxylic acids are formed.

Example:

 

 

 

 

157 of 214

6. From Alkenes and Alkynes

Preparation of Carboxylic Acids

b. Oxidative Ozonolysis

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Example:

 

 

 

 

 

 

 

 

 

 

 

2-Butene

Ethanoic acid

158 of 214

12C12.4

​

PSV 1

159 of 214

Q. Show how each of the following compounds can be converted to benzoic acid.

  1. Ethylbenzene
  2. Acetophenone

(iii) Bromobenzene

(iv) Phenylethene (Styrene)

Sol.

(i) Benzoic acid from Ethylbenzene

(ii) Benzoic acid from Acetophenone

 

 

160 of 214

(iii) Benzoic acid from Bromobenzene

 

 

(iv) Benzoic acid from Phenylethene (Styrene)

161 of 214

Summary

 

 

 

 

 

 

 

 

 

 

Carboxylic Acid & It’s Preparation

 

 

 

 

 

 

 

 

 

162 of 214

Reference Questions

​

NCERT In-Text Questions: 12.6

​

NCERT Exercise Questions: 12.14, 12.17 (i & ix)

​

Workbook Questions: 17 (i), 18 (i & ii)

12C12.4 Carboxylic Acid & It’s Preparation

163 of 214

12C12.5

​

Properties of Carboxylic Acids

164 of 214

12C12.5 Properties of Carboxylic Acids

Learning Objectives

​

Physical Properties of Carboxylic Acids

​

Acidic Nature of Carboxylic Acids

​

Reactions involving Breaking of C-OH bond

​

Reactions involving –COOH Group

​

Substitution Reaction of Carboxylic Acids

​

Uses of Carboxylic Acids

165 of 214

12C12.5

​

CV 1

​

Physical Properties of Carboxylic Acids

​

166 of 214

  • Lower fatty acids upto C-1O are colourless liquids but the higher ones are colourless waxy solids.
  • First 3 members have a sharp pungent odour, C-4-C-9, have an odour of rancid butter whereas higher members do not possess any smell.
  • Lower members are highly soluble in water but the solubility decreases with the rise of molecular mass.
  • Boiling points of carboxylic acids are higher than those of alcohols of same molecular mass due to the intermolecular H-bonding.

Physical Properties of Carboxylic Acids

 

 

 

 

 

 

 

 

167 of 214

 

 

 

 

 

 

 

 

 

 

120°

 

 

 

 

 

Structure of Carboxylic Acids

 

 

Note: B.L. mentioned is for formic acid, it varies with the attached alkyl group and substituents.

168 of 214

12C12.5

​

PSV 1

​

​

169 of 214

 

O

OH

OH

OH

O

OH

OH

O

OH

OH

O

A

B

C

D

Sol.

 

 

 

 

 

 

 

 

`

 

 

 

 

 

 

 

 

 

 

 

 

170 of 214

O

OH

OH

OH

O

OH

OH

O

OH

OH

O

A

B

C

D

Sol.

 

 

 

 

OH

OH

O

OH

OH

O

D <

A <

B

< C

Ortho effect

Sterically Inhibited Resonance

(SIR-effect)

 

Steric Hindrance

171 of 214

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172 of 214

Q. Arrange following molecule in increasing order of their acidity:

Pause the video

Time duration: 1 minute

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A

B

C

D

173 of 214

Q. Arrange following molecule in increasing order of their acidity:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A

B

C

D

Sol.

 

 

A <

C <

B <

D

Order of acidic nature:

174 of 214

12C12.5

​

CV 2

​

Acidic Nature of Carboxylic Acids

​

175 of 214

Acidic Nature of Carboxylic Acids

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Less Acidic

More Acidic

176 of 214

Acidic Nature of Carboxylic Acids

Reactions due to Acidity of Carboxylic Acids

 

 

 

Example:

Example:

 

177 of 214

Acidic Nature of Carboxylic Acids

Reactions due to Acidity of Carboxylic Acids

 

 

Example:

 

178 of 214

12C12.5

​

CV 3

​

Reactions involving Breaking of

C-OH Bond

179 of 214

Reactions involving Breaking of C-OH Bond

1. Formation of Anhydride

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acid Anhydride

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • O-atom on carbonyl carbon is nucleophilic due –ve charge in its resonating structure

180 of 214

 

 

 

 

 

 

 

 

 

Reactions involving Breaking of C-OH Bond

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note: Anhydride of formic acid cannot be obtained by this method.

  • We can also obtain acid anhydrides by heating sodium salt of acid with acid chloride.

 

 

 

181 of 214

Reactions involving Breaking of C-OH Bond

2. Esterification

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

182 of 214

3. Reaction with Phosphorus Chlorides or Thionyl Chlorides:

Reactions involving Breaking of C-OH Bond

 

 

 

 

 

 

 

 

 

 

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Acid Chloride

Acid Chloride

183 of 214

4. Reaction with Ammonia:

Reactions involving Breaking of C-OH Bond

 

 

 

Ammonium Salt

Amide

  • Acid-Base Reaction.
  • Heated at High Temperature.

 

 

 

 

 

 

Example:

 

Benzamide

Benzoic acid

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185 of 214

 

 

 

 

 

 

 

 

Q. Identify A,B and C in following reaction:

Pause the video

Time duration: 2 minutes

186 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Q. Identify A,B and C in following reaction:

Sol.

 

 

 

 

|

|

Phthalimide

Phthalic Acid

  • Phthalimide is used to prepare primary amines.

187 of 214

12C12.5

​

CV 4

​

Reactions involving –COOH Group

188 of 214

Reduction of –COOH Group

 

 

 

 

 

Primary Alcohol

 

Example:

 

 

 

 

Propanoic acid

Propanol

189 of 214

Decarboxylation Reaction

 

 

 

Soda Lime Process

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alkane

Mechanism:

Alkane

  • Carbanion is formed as intermediate.
  • Step down reaction as number of C-atoms in product decreases.

190 of 214

Decarboxylation Reaction

 

 

 

Methane

Example:

Ethanoic Acid

 

 

 

Benzene

Benzoic Acid

191 of 214

Kolbe’s Electrolysis

Acid Salt Solution

Anode

Cathode

 

 

 

Alkane

 

Mechanism:

At Anode:

 

 

 

 

 

 

 

 

 

 

 

 

192 of 214

Acid Salt Solution

Anode

Cathode

 

 

 

Mechanism:

At Anode:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alkane

Alkane

  • Alkyl radicals undergo dimerisation to form alkane.
  • Alkane has twice the number of carbon atoms present in the alkyl group of the acid.

Kolbe’s Electrolysis

193 of 214

Acid Salt Solution

Anode

Cathode

 

 

 

Mechanism:

At Anode:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Alkane

Alkane

At Cathode:

 

 

Kolbe’s Electrolysis

194 of 214

12C12.5

​

CV 5

​

Substitution Reactions of Carboxylic Acids

195 of 214

Substitution Reaction of Carboxylic Acids

 

 

 

|

 

 

 

 

Hell-Volhard-Zelinsky Reaction

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tautomerisation

 

 

 

 

 

196 of 214

Substitution Reaction of Carboxylic Acids

 

 

 

|

 

 

 

 

Hell-Volhard-Zelinsky Reaction

 

Mechanism:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Tautomerisation

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

197 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

`

 

 

 

 

 

 

 

 

 

 

 

 

  • m-position is relatively less electron deficient hence electrophile prefer m-position

Substitution Reaction of Carboxylic Acids

2. Electrophilic Aromatic Substitution Reaction:

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199 of 214

Q. How will you convert Benzoic acid to m- Nitrobenzyl alcohol in not more than three steps?

​

Pause the video

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200 of 214

Q. How will you convert Benzoic acid to m- Nitrobenzyl alcohol in not more than three steps?

​

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

201 of 214

12C12.5

​

CV 6

​

Uses of Carboxylic Acid

202 of 214

Uses of Carboxylic Acid

  • Methanoic acid is used in

Electroplating industries

Leather industries

Rubber industries

Dye industries

Textile industries

203 of 214

Uses of Carboxylic Acid

  • Ethanoic acid is used as

Solvent

Vinegar

  • Sodium benzoate is used as a food preservative
  • Higher fatty acids are used for the manufacture

Soaps

Detergent

  • Esters of benzoic acid are used in perfume industry

204 of 214

Summary

  • Carboxylic acids are weaker than mineral acids, but they are stronger acids than alcohols and simple phenols.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

|

 

 

 

 

205 of 214

Reference Questions

​

NCERT In-Text Questions: 12.7, 12.8

​

NCERT Exercise Questions: 12.10, 12.12, 12.16, 12.19 (i to viii), 12.19, 12.20

​

Workbook Questions: 15, 16 (i), 17

12C12.5 Properties of Carboxylic Acids

206 of 214

207 of 214

 

 

 

 

 

 

 

 

 

 

 

208 of 214

12C12.1

​

PSV 1

209 of 214

12C12.1

​

PSV 1

 

 

 

 

 

 

 

 

210 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

211 of 214

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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213 of 214

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214 of 214