Kinetics of N-oxyl Radicals’ Decay

Abstract

N-oxyl radicals of various structure were generated by oxidation of corresponding N hydroxyimides with iodobenzene diacetate, [bis(trifluoroacetoxy)]iodobenzene and ammonium cerium (IV) nitrate in acetonitrile. The decay rate of imide N oxyl radicals follows first order kinetics and depends on the structure of N oxyl radicals, reaction conditions, the nature of the solvent and oxidant. The values of the self decay constants change within 1.4·10-4 s 1 for 3,4,5,6 tetraphenylphthalimide N oxyl radical to 1.4·10-2 s 1 for 1 benzotriazole N oxyl radical. It was shown that the rate constants of the phthalimide N oxyl radicalsʼ self decay with different electron withdrawing or donor substituents in the benzene ring are higher than that of unsubstituted phthalimide N oxyl radical in most cases. The solvent effect on the process of phthalimide-N-oxyl radical self-decomposition was investigated. It was shown the dependence of the rate constants on the Gutmann donor numbers.