KINETICS AND MECHANISM OF REACTION OF ARYL OXIRANES WITH DINITROGEN PENTOXIDE IN DICHLOROMETHANE

4-X-Phenyloxiranes (X = H, Cl, CF3, NO2) in dichloromethane react with N2O5 to give 1-(4-X-phenyl)ethane-1,2-diol dinitrates and with HNO3 to give 2-(4-X-phenyl)-2-nitroethanols. Both reactions give quantitative yields. Kinetics of both reactions, mostly at reduced temperatures, have been investigated. The former reaction is second order in N2O5 and the latter reaction is between second and third order in HNO3. Both reactions are retarded strongly by electron-withdrawing substituents and show large and negative entropies of activation. Mechanisms are discussed.