DIARYLDIACYLOXYSPIROSULFURANES .4. A KINETIC-STUDY ON THE MECHANISM OF HYDROLYSIS

Kinetics of the hydrolysis of diaryldiacyloxyspirosulfuranes leading to sulfoxides have been studied under pseudo-first-order conditions in dioxane-water mixtures. It has been found that high solvent polarities and ionic strengths increase the reaction rate. The reaction is also promoted by electron-donating substituents (rho - 0.52). Strong acids have a catalytic effect on the reaction in which case the substituent effect is more pronounced (rho - 1.55). In neutral medium the deuterium solvent isotope effect is k(H2O)/k(D2O) 1.66, while in acidic medium the ratio of catalytic constants is found to be 0.56. The rate of the reaction is greatly increased with the increasing size of the spiroring (from 5 to 7) in the sulfurane. Kinetic data suggest a dissociative reaction mechanism.