MECHANISM OF THE DIMETHYLDIOXIRANE OXIDATION OF N,N-DIMETHYLANILINES

Relative rates of dimethyldioxirane oxidation of a number of para-subs tituted N,N-dimethylanilines in acetone at 5 degrees C are compared wi th those of reactions with methyl iodide and other oxidants, The react ions with dimethyldioxirane followed the Hammett relationship with ap value of -1.0. Measurement of the second order rate constants for the dimethyldioxirane reactions in aqueous acetonitrile containing potassi um nitrate at 21 degrees C, showed better correlation with the Hammett relationship (rho = 0.89) than with the Okamoto-Brown model (rho(+) = 0.56). The reaction rates are accelerated greatly in the presence of water such that the respective pseudo first order rate constants for t he oxidation of N,N-dimethyl-4-nitroaniline in acetone and water are 6 .3 x 10(-3) and 5.86 s(-1), respectively, All of the data are consiste nt with a concerted electrophilic mechanism and there is no evidence o f free radical or electron transfer reactions.