The reaction mechanism of polyamide synthesis by phosphorylation

Abstract

The reaction mechanism of the polyamide synthesis by phosphorylation with triaryl phosphite and imidazole was investigated in terms of the amidation reaction of model compounds and the polycondensation of various nylon salts. Triphenyl phosphite formed a complex with imidazole which reacted easily either with amine or carboxylic acid to form acyloxy phosphite or phosphoramide complexes. The electron-donating substituent of phenol of aryl phosphites retarded the amidation and polycondensation reactions, and, among various tertiary amines, only imidazole had a cocatalytic effect. The low molecular weight of the resulting polyamide was ascribed to the many competitive reactions of the phosphite—imidazole complex between amine and carboxylic acid, which resulted in the molar balance loss of amine or carboxylic acid. The reaction mechanism for the polycondensation of nylon salt by phosphorylation was again discussed in this paper. © 1974, The Society of Polymer Science, Japan. All rights reserved.