Gas-phase thermolyses. Part 8. Gas-phase thermolysis of methyl and ethyl monothioacetates

Abstract

The unimolecular gas-phase thermolyses of the four methyl and ethyl monothioacetates (5)–(8) have been studied by the flash vacuum thermolysis–field ionization mass spectrometry technique in the temperature range 883–1 404 K. The types of reactions verified were keten formation, thiono–thiolo rearrangement, and, in the case of the ethyl esters, ethylene elimination. The possible mechanisms for keten formation are discussed, and it is concluded that the thiono-carboxylates eliminates the mercaptan via an enethiolized structure, whereas the decomposition of the thiolo-esters apparently proceeds via direct 1,2-elimination of the thiols.