A theoretical study of styrene and sulfenyl chloride reaction mechanism

The classical description of sulfenyl halides additions to olefins proposes the formation of an episulfonium ion intermediate during the reaction path. However, a careful analysis of experiments performed in the past suggests that there should not be a single mechanistic picture of sulfenyl halide additions to substituted olefins. Our work is the first theoretical study of detailed insights into the mechanism of methylsulfenchloride addition to styrene. The reaction potential energy profile has been calculated by means of the B3LYP functional with the 6-31++G(d, p) basis set. Mixing of the molecular orbital shapes of reaction stationary points has been described. The addition proceeds as a single step reaction from the methylsulfenchloride and styrene reactants via the concerted transition state (TS) to the final product along the reaction path estimated by the calculation of the intrinsic reaction coordinate. The reaction intermediate was not detected by calculations. The polar solvent has a significant effect on the decrease of reaction activation energy barriers. The large charge separation of the S–Cl bond in TS implies that the addition reaction should proceed through the ionic TS.