Synthesis of 4,4'-diaminobenzil

4,4'-Diaminobenzil was synthesized from benzoin,through esterification with acetic anhydride,followed by oxazole formation with ammonium acetate,nitration with mixed sulfuric and nitric acids,oxazole ring-opening with bromine and finally reduction with ferrous sulfate and ammonia.The overall product yield was up to 61%.Parameters which could influence the synthetic reactions were briefly investigated.