Process for the manufacture of 2-phenyl-4,5-oxazoledione 4-phenylhydrazone derivatives

摘要

A process for manufacturing derivatives of 2-phenyl-4,5-oxazoledione 4-phenylhyrazone is disclosed. The process comprises reacting a derivative of a benezenediazonium salt, a hippuric acid derivative, and acetic anhydride in the presence of a neutralizing agent to effect the cyclization reaction for the formation of the oxazolone ring and the succeeding diazo-coupling reaction. The process does not require the conventional separate, independent step for the preparation of a solution of a hippuric acid derivative and acetic anhydride, thus eliminating the quick heating and quenching procedures and further avoiding the loss of the hippuric acid derivative due to decomposition of the oxazolone derivative. There is thus obtained a high yield of the desired product in a short period of time.