Formation of stable aryldisulphide ions in dimethylacetamide from the reaction of sulphur with thiolate ions
Abstract
The conditions for the formation of aryldisulphide ions, RS2– during the direct reaction of sulphur with thiolate ions RS– have been studied by the use of spectroelectrochemistry in dimethylacetamide. The series of derivatives examined was R =p-tolyl (1), phenyl (2), 8-quinolyl (3), 2- and 4-pyridyl (4), (5), N-oxido 4-pyridyl (6), 2- and 4-nitrophenyl (7), (8), and 2-(5-nitropyridyl)(9). Sulphur reaction leads to RS2– ions and precedes the oxidation to diaryldisulphide RS2R and polysulphide ions Sx2–. With derivatives (1)–(3), both reactions are successive and practically stoicheiometric, while for derivatives containing electron-withdrawing groups (6)–(9), the equilibrium constants have been measured. Analysis of the reaction products by methylation of several solutions of thiolate ions [(2), (7), (8)] in the presence of sulphur confirmed the possibility of obtaining aryldisulphide ions stabilized in aprotic dipolar media.