Chapter 21, Problem 21.8P

Interpretation Introduction

Interpretation:

It is to be proposed how to carry out the given synthesis, in which an amide isconverted into an acid anhydride.

Concept introduction:

An acyl substitution that converts an acid derivative from a higher rung onthe stability ladder to one on a lower rung of the ladder is energeticallyfavorable. Therefore, the conversion of the more stable acid derivative to a less stable acid derivative is cannot proceeds in a single step. Thus for the conversion of an amide to an acid anhydride first amide must be converted to acid chloride. Amide on base hydrolysis produces corresponding carboxylic acid. Carboxylic acid on treatment either ${\text{PCl}}_{\text{3}}$ or ${\text{SOCl}}_{\text{2}}$ corresponding acid chloride is formed.