Derivatives of carboxylic acid

Some of the derivatives of carboxylic acid are acid halide, acid amide, ester, acid anhydride.

A. Acid halides (R-COCl):

Nomenclature (IUPAC name- Alkanoyl chloride):

Preparation:

1. From carboxylic acid: Carboxylic acid reacts with PCl3, PCl5 or SOCl2 to give acid chloride.

Physical Properties:

1. Lower members are colorless liquids having irritating odour and higher members are colorless solid.
2. Acid chlorides are insoluble in water due to a lack of intermolecular hydrogen bonding with water.
3. The boiling point of acid chloride is less than parent acid due to the absence of hydrogen bonding. Formyl chloride (HCOCl) is unstable.

Chemical Properties:

1. Action with air:

2. Action with ammonia

3. Action with alcohol:

4. Rosenmund reaction:

5. Reduction to alcohol:

6. Action with Grignard’s reagent:

B. Acid Amide (R-CONH₂):

Nomenclature (IUPAC name- Alkanamide):

Preparation:

1. From carboxylic acid:

2. From partial hydrolysis of alkanenitrile:

Physical Properties:

1. Almost all amides are colorless, odourless, and crystalline solid. Formamide is a liquid.
2. Lower members are soluble in water due to hydrogen bond formation.
3. They have a higher boiling point than corresponding acids.

Chemical Properties:

1. Amphoteric Nature:

2. Hydrolysis:

3. Reduction:

4. Dehydration:

5. Action with nitrous acid:

6. Hoffman Hypobromide reaction (decarbonylation):

C. Ester (RCOOR):

Nomenclature (IUPAC name- Alkyl alkanoate):

Preparation:

1. From carboxylic acid (Esterification):

2. From haloalkane:

Physical Properties:

1. Esters are colorless oily liquids with a fruity odour.
2. They are sparingly soluble in water.
3. The boiling points of esters are always less than corresponding carboxylic acids.

Chemical Properties:

1. Hydrolysis:

2. Reduction:

3. Ammonolysis:

4. Action with PCl₅:

5. Claisen condensation: Esters having -hydrogen reacts with a base like sodium ethoxide to form ethyl acetoacetate (EAA).

6. Action with Grignard’s reagent:

D. Acid anhydride:

Nomenclature (IUPAC name- Alkanoic anhydride):

Preparation:

1. From carboxylic acid:

Physical Properties:

1. Lower members are colorless liquid having a sharp irritating smell. Higher members are colorless solids.
2. Lower members are soluble in water.
3. They have a higher boiling point than parent carboxylic acid.

Chemical Properties:

1. Hydrolysis:

2. Ammonolysis:

3. Alcoholysis:

4. Reduction:

5. Action with PCl₅