Organic reactions in melts and solids. Part V. Transacylation reactions of amides with acids and anhydrides

The reaction of amides with various acids and anhydrides in the presence and absence of catalysts has been studied in molten reaction mixtures. The reaction yielded exclusively transacylation products and as a rule no ring-acylation was observed. With monocarboxylic acids the reaction is reversible and an equilibrium mixture was obtained; with dicarboxylic acids the primary transacylation product gave the corresponding cyclic imide in almost quantitative yields. Transacylation with anhydrides occurs only in the presence of acid catalysts. Possible mechanisms for the reaction are discussed.