Intramolecular participation by an amide group in ester hydrolysis

Abstract

The rate coefficient for hydrolysis of 1-acetoxy-8-acetylaminonaphthalene to 1-hydroxy-8-acetylaminonaphthalene in aqueous sodium hydroxide shows a curved dependence on hydroxide ion concentration. Similar results are observed for the 3,6-disulphonate and five substituted 1-benzoyloxy-8-benzoylamino-3,6-disulphonates. In the proposed mechanism the ester group undergoes intermolecular attack by hydroxide ion in competition with intramolecular attack by the amide group. The latter generates an imide intermediate in equilibrium with the ester via a rapid acyl transfer, and since the imide is hydrolysed slowly to product its formation inhibits the ester hydrolysis.