Oxidation of thiols and disulphides with the ammoniumyl radical-cation, +˙NH3: an e.s.r. investigation

Abstract

E.s.r. spectroscopy has been employed to demonstrate that the reaction of ⁺˙NH₃(from Ti^III and ⁺NH₃OH) with thiols (RSH) proceeds via the initial formation of thiyl radicals (RS·); these react further to give disulphides as well as oxygen-containing radicals RSO· and RSO₂·, formed by a series of one-electron oxidation reactions, and both SO₂^–˙ and SO₃^–˙(which arise via sulphur dioxide formed in the decomposition of RSO₂˙). Reaction with disulphides, which leads to the detection of sulphinyl radicals and disulphide-conjugated radicals, is thought to involve both radical-cations (RSSR⁺˙) and ammoniumyl adducts [RS([graphic omitted]H₃)SR] whose further reactions have been described.