Process for producing isatoic anhydrides

摘要

A process for producing isatoic anhydrides of the formula (II): which comprises reacting an anthranilic acid of formula (I): or a salt thereof with phosgene using a mixed solvent of water and an organic solvent miscible with water and inert to the reaction; conducting the reaction in the coexistence of an alkylpyridinium salt in an aqueous solvent; or using a mixed solvent of water and a specific amount of an organic solvent substantially immiscible with water and inert to the reaction.