Osmium(VIII)-catalyzed oxidation of pentamethylene sulfide

Although pentamethylene sulfide (tetrahydrothiopyran) lacks acidic hydrogen, OsVIII has been found to catalyze its oxidation by alkaline K3Fe(CN)6 to produce 3-hydroxypentamethylene sulfide as the only product. The kinetics reveal first-order dependence on ferricyanide and OsVIII, and zero order on pentamethylene sulfide and OH−. The effects of introduced electrolytes, K4Fe(CN)6, relative permittivity and temperature have also been studied. On the basis of kinetic evidence, a mechanism that involves anation of the osmium catalyst (sulfide/water interchange) followed by intramolecular proton abstraction, followed by an electron transfer step has been proposed and discussed.