Kinetics of the hydrolysis of diaryldiacyloxyspirosulfuranes leading t
o 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 deuteriu
m 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 spirori
ng (from 5 to 7) in the sulfurane. Kinetic data suggest a dissociative
reaction mechanism.