Reaction between chlorodiphenylacetic acid and thiourea

Abstract

The reaction between chlorodiphenylacetic acid and thiourea has been studied, using the former as such, as ethyl ester and the acid chloride, with or without the use of ethanol as solvent. The experimental conditions for the preparation of 5,s-diphenylpseudothiohydantoin and the formation of 2-(diphenylmethyl)imino-4-0~0-5,5-dip henyl t hiazolidine and/or bis(dipheny1-methyl) disulfide as secondary products involving decarboxylation of chlorodiphenylacetic acid have been discussed.In connection with our work on a novel degradation of pseudothiohydantoins 1 , 5 , 5-diphenyl-pseudothiohydantoin (I) was prepared from chlorodiphenylacetic acid 2 (II), from its ethyl ester 3 (111) and from its acid chloride 3 (IV), each in reaction with thiourea (V), under different experimental conditions. Moreover, the study of the reaction between chlorodiphenylacetic acid and thiourea gains significance because of the diversity of the compounds which have been reported 4 in a thermal reaction between benzilic acid -the parent compound of I1 -and thiourea, although neither 5,5-diphenylthiohydantoin nor I was formed in this reaction 4 , comparable to one between benzilic acid and urea 5 in which 5,5-diphenylhydantoin was the main product.mention the preparation of I in N 33% yield of the crude product but make no mention of the formation of any secondary compound.In addition to I , obtained in different yields depending on the experimental conditions and the particular derivative of I1 employed in the reaction, bis(diphenylmethy1) disulfide 4 9 % 7 (VI) was formed as an additional product in the present work.