The desulphurisation of thionesters

The mercury salt desulpliixri sat ions of the thiono esters were found to be dependent on the anion of the mercury salt, in a similar manner to the previously reported thioamide desulphurisations. Mercuric acetate reacts rapidly to give the corresponding ester and acetic anhydride. The reaction of mercuric chloride was much slower, giving a mixture of products. A mechanism is proposed for the mercuric acetate desulphurisation which predicts the formation of acetic anhydride. This mechanism is supported by the isolation of acetic anhydride in approximately the amount predicted. Desulphurisation of thiono esters with mercury carboxylates may be a useful synthesis of acid anhydrides.