Cumene hydroperoxide-supported N-demethylation of N,N-dimethylanilines catalyzed by catalase.

Abstract

The stoichiometry and kinetic mechanism of the cumene hydroperoxide (CHP)-supported N-demethylation of N, N-dimethylaniline (DMA) catalyzed by catalase were studied. The formations of formaldehyde, 2-phenyl-2-propanol and N-methylamiline, and the consumption of DMA exhibited a 1 : 1 : 1 : 1 stoichiometry up to 5 min after initiation of the reaction. Plots of reciprocal initial velocity versus the reciprocal concentration of either substrate at several different fixed concentrations of the other substrate resulted in a family of straight lines which converged to a common intersection point on the left side of the ordinate and above the abscissa, suggesting a sequential mechanism involving the formation of a ternary complex of catalase, DMA and CHP followed by one or more reactions and the subsequent release of the products. N, N, N', N'-Tetramethylbenzidine radical cation was detected by electron spin resonance spectroscopy during the CHP-supported oxidation of DMA, whereas the corresponding amine radical cations were detected during the oxidations of N, N-dimethyl-p-toluidine and N, N-dimethyl-p-anisidine. These results suggest that the mechanism of the CHP-supported oxidation of DMA catalyzed by catalase is the same as that of aminopyrine.