Formation of acyldisulfide ions from the reaction of sulfur with thiocarboxylate ions, and reactivity towards acyl chlorides in N,N-dimethylacetamide

Abstract

The reactivity of sulfur towards thiocarboxylate ions RC(O)S^- a (R = Ph 1, Me 2, Bu^t 3) has been studied by spectroelectrochemistry in N,N-dimethylacetamide. For 2a–3a, two parallel and partial reactions, for which equilibrium constants have been determined, led to: (i) [RC(O)]₂S₂^- b species and S₃^·-/S₈^2- polysulfide ions and (ii) RC(O)S₂ ions c; only traces of 1c were detected by voltammetry. As previously observed with thiolate ions, our results are consistent with an initial monoelectronic transfer between RC(O)S^- ions and S₂ molecules in equilibrium with S₈, followed by concurrent couplings of RC(O)S˙ and S₂^·- radicals. On a preparative scale, when sulfur was added to RC(O)S^- ions 1a,3a the enhanced reactivity of RC(O)S₂^- ions towards acyl chlorides RC(O)Cl (R = C₆H₅ and Bu^t, respectively) only yielded diacyl disulfides 1b,3b.