Question

How could you synthesize the following compounds starting with a carboxylic acid?

Short answer

The reaction followed as:

b.

Step-by-step solution

Formation of ether from carboxylic acid

Carboxylic acid directly does not lead to ether formation of carboxylic acid derivate is formed that is acyl chloride on the reaction of a carboxylic acid with the thionyl chloride or phosphorous trichloride after abstraction of proton of carboxylic acid they attached to it and make a good leave group and form acyl chloride which on reaction with alcohol from the ether.

Mechanism

Mechanism followed as:

1. Reaction of a carboxylic acid with thionyl chloride

2. Formation of acyl chloride occur

3. Reaction of an acyl chloride with alcohol

4. Removal of HCl occur

5. Formation of ether occurred

Formation of amide from carboxylic acid

Similarly, a carboxylic acid forms its derivative acyl chloride on reaction with thionyl chloride, and the reaction followed by reacting with two equivalent amines and amide formation occurs followed by removal of HCl as followed: