The hydrolysis of a series of aryl sulfinyl sulfones (11) has been investigated under a variety of reaction conditions in acidic aqueous dioxane. The results are compared where appropriate to the hydrolytic behavior of the corresponding carboxylic anhydrides and/or sulfite esters. In the absence of nucleophilic additives, the hydrolysis of I1 occurs almost exclusively by a spontaneous (or uncatalyzed) pathway, even in quite acidic aqueous dioxane. This contrasts with the hydrolysis of I1 in acetic acid-water and also with the hydrolysis of the corresponding sulfite esters in aqueous dioxane, where, in both cases, an acid-catalyzed pathway accounts for virtually the entire rate. Reasons for these differences in behavior are outlined. The spontaneous hydrolysis of I1 exhibits a large solvent isotope effect, k H I O / k D r O = 2.7, and is markedly accelerated by both an increase in the percentage water in the solvent and by the presence of electron-withdrawing substituents in the aryl groups. A mechanism consistent with all the experimental facts is shown in eq 6. The hydrolysis of I1 can be catalyzed by such nucleophilic additives as halide ions or alkyl sulfides. The halide ion catalyzed hydrolysis has been studied and a mechanism proposed (eq 9 and lo), and the results are compared with the halide ion catalyzed hydrolysis of sulfite esters. The alkyl sulfide catalyzed hydrolysis of I1 has also been studied, and the results are compared with those previously obtained for the same reaction in acetic acid-1 water. The comparison indicates that eq 11 is the correct mechanism for the sulfide-catalyzed reaction.he anhydrides of aromatic sulfinic acids do not T have a structure (I) analogous to a carboxylic anhydride but rather possess the sulfinyl sulfone structure 9 acid concentrations employed.
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