A kinetic–electron spin resonance study of the self-reactions of some aromatic and aliphatic sulphonyl radicals and aromatic sulphinyl radicals

Abstract

A variety of aromatic and aliphatic sulphonyl radicals (RSO₂˙) have been found to undergo diffusion-controlled self-reaction in solution (with 2k_t typically ca. 10⁹ dm³ mol^–1 s^–1); reaction proceeds somewhat slower for some sterically hindered arenesulphonyl radicals (ArSO₂˙) and for some arenesulphinyl analogues (ArSO˙). The observation of curved Arrhenius plots for some ArSO₂˙ radicals, as well as the detection of ArSO˙ from sulphonyl precursors under steady-state conditions, is attributed to the thermal decomposition of an unstable intermediate formed by dimerisation (sulphur-to-oxygen) of ArSO₂˙. A thermodynamic and kinetic analysis is presented.