METHANESULFENYL CHLORIDE .V. SPONTANEOUS DECOMPOSITION OF METHANESULFENYL CHLORIDE AND METHYLSULFUR TRICHLORIDE

Methanesulfenyl chloride, CH3SC1, on standing for a few hours at room temperature begins to decompose into methyl chloride, methyldisulfur chloride, methyl disulfide, methyl trisulfide, and methyl tetrasulfide as major products as indicated by the nmr spectra of decomposition mixtures. Minor peaks in the spectrum correspond to the 5 chemical shifts of methyl chloromethyl disulfide and dichloromethyl methyl sulfide. Other products were hydrogen chloride, sulfur dichloride, elementary sulfur, and, in some cases, on long standing an unidentified solid. Methylsulfur trichloride decomposes rapidly when the crystalline solid is heated a few degrees above room temperature. The nmr spectrum of the decomposition mixture indicates that the principal products are chloromethanesulfenyl chloride (ca. 60%) and methanesulfenyl chloride (ca. 20%). Other products identified by their peaks in the nmr spectrum are methyldisulfur chloride, methyltrisulfur chloride, methyltetrasulfur chloride, bischloromethyl disulfide, and dichloromethanesulfenyl chloride. In addition, hydrogen chloride and sulfur dichloride were also products of the decomposition. Uncertainty exists as to whether the decomposition of CH3SCl takes place by an ionic or free-radical mechanism. An esr study of the decomposition showed no signals to indicate an appreciable concentration of free radicals. Methyl disulfide, irradiated at liquid nitrogen temperature, produced an esr spectrum with clearly defined signals believed to indicate the CH3S· radical. This radical appears to be highly reactive and cannot be stabilized on Vycor glass at room temperature. The failure to observe esr signals in decomposing CH3SCI may possibly be due to the high reactivity of radical intermediates resulting in a low steady state concentration. © 1969, American Chemical Society. All rights reserved.