Effect of Ring Substituent on the Stability of the Epoxide Derived from Phenyl Vinyl Ether

Ring-substituted and unsubstituted phenoxyoxiranes were synthesized from phenyl vinyl ether derivatives by perbenzoic acid oxidation in CHCl3. The epoxides isolated from the reaction mixture were stable in aprotic solvents. On the other hand, all of the epoxides decomposed rapidly to glycolaldehyde and the corresponding phenol in 0.1 M phosphate buffer, pH 7.4, at 37°C. Under these conditions, the hydrolytic decomposition followed first-order kinetics.Phenoxyoxiranes with an electron-withdrawing substituent in the benzene ring were relatively stable under aqueous conditions. The rate of decomposition was well correlated with the Hammett constant (σ) of the substituent in the benzene ring.