Formation of Acid Anhydrides From Carboxylic Acids

Since the carboxylic acid anhydrides are formally derived from carboxylic acids by loss of water, their names are derived from the corresponding acids by using the word anhydride in place of the acid. This method is used for the preparation of symmetrical anhydrides.

Carboxylic acid also react with acyl chlorides in the presence of pyridine to give carboxylic acid anhydrides. Unsymmetrical anhydrides can be prepared by this method.