Question

How can a carboxylic acid be converted to a carboxylic acid chloride using different reagents? How will you convert the acid chlorides to

i) other halides, and

ii) the starting carboxylic acid?

Answer 1

Carboxylic acids react with Thionyl Chloride ($SOCl_2$ ) to form acid chlorides. During the reaction, the hydroxyl group of the carboxylic acid is converted to a chlorosulfite intermediate making it a better leaving group. The chloride anion produced during the reaction acts as a nucleophile.

Or, we can use methods that do not form HCl, such as the Appel reaction:

and the use of cyanuric chloride ($C_3N_3Cl_3$)

(i)Acid Chloride to other halides by nucleophilic substitution.

(ii)Acid chloride to carboxylic acid:

Acid chlorides react with water to form carboxylic acids.