The preparation of (Methylthio)- and (Methylseleno)-tri(alkyl or aryl)phosphonium salts and their reactions with carboxylic acids and alcohols

Abstract

A series of (methylthio)- and (methylseleno)-triphenylphosphonium salts and the analogous tributylphosphonium salts have been prepared by methylation of the corresponding tertiary phosphine sulfides and selenides. Details of their ¹H, ¹³C and ³¹P n.m.r. spectra are given. Whereas the (methylthio)- and (methylseleno)-triphenylphosphonium salts undergo rapid decomposition in the presence of tertiary ammonium carboxylates or tertiary amines, the (methy1thio)- and (methylseleno)-tributylphosphonium salts convert such carboxylates into methanethiol and methaneselenol esters in acceptable yields. A tris(dimethylamino)(methylthio)phosphonium salt, on the other hand, converts benzoate into methyl benzoate in quantitative yield. Inferior yields of (methy1thio)- and (methylseleno)-alkanes are obtained from two primary alcohols and the tributylphosphonium salts.