Studies on Reactions of the N-Phosphonium Salts of Pyridines. I. A New Method for the Activation of Carboxylic Acids via the N-Phosphonium Salts by Means of the Oxidation of Tri- and Di-esters of Phosphorous Acid in the Presence of Tertiary Amines

Abstract

Abstract Carboxylic acids were found to be activated by an oxidation mixture prepared from tri- and di-esters of phosphorous acid and mercuric chloride in a pyridine solution; they yielded the corresponding anilides upon treatment with aniline, together with a nearly quantitative yield of metallic mercury. The yield of the anilides was affected by the alkyl groups in the esters and by the tertiary amines. Only a small effect of the steric factor of carboxylic acids upon the reaction was seen in the cases of the diesters, and none at all was observed in the triesters. The reaction was proposed to proceed via the N-phosphonium salts of pyridines, which were not purely isolated, but which were assumed on the basis of the IR spectra.