Chapter 21, Problem 21.57P

Interpretation Introduction

(a)

Interpretation:

The detailed mechanism for the given reaction is to be drawn.

Concept introduction:

The acid anhydride can be prepared by reacting an ester and carboxylic acid in an acidic condition. The ester gets activated by protonation at carbonyl oxygen, and the carboxylic acid acts as a nucleophile.

Interpretation Introduction

(b)

Interpretation:

In general, the equilibrium of the given reaction favors reactants. However, if the ester used is replaced by another given ester, then equilibrium favors the products. It is to be explained why.

Concept introduction:

The ketones are more stable forms than enols; thus, enol tautomerizes to ketone. According to Le Châtelier’s principle, if the reactant concentration increases or the concentration of product decreases, the reaction equilibrium will be more towards the product side.