Thermal decomposition of thiirane and 2-methylthiirane: an experimental and theoretical study

Abstract

The thermal decomposition of thiirane and 2-methylthiirane was investigated in a flow system by following the changes in their photoelectron spectra at various temperatures. Similar decomposition patterns were observed in both cases. Thus at 600 °C, formation of sulfur and an alkene was detected. At higher temperatures, conversion of thiirane into ethenethiol and thioacetaldehyde, and of 2-methylthiirane into cis- and trans-prop-1-ene-1-thiol was observed. Hydrogen sulfide, alkynes, carbon disulfide and thiophene were detected as products of secondary reactions. The experimental data pertaining to the rearrangement processes are compared with potential energy profiles, calculated by using the MNDO/CHAIN procedure. A mechanism involving initial C–S bond breaking, followed by 1,2-hydrogen shift, is suggested by the results.