The Cu(II)-Nitroxyl Radicals System: the High Activity and Reactivation of the Catalyst in the Decomposition of Hydroperoxides

摘要

Chelate copper(II) compounds were shown to exhibit high catalytic activity in the decomposition of hydroperoxides in the presence of nitroxyl radicals. The participation of nitroxyl radicals as cocatalysts increased the rate of the reaction and the number of catalytic cycles. Nitroxyl radicals provided catalyst reactivation after complete activity loss characteristic of the process in the absence of promoting admixtures. The promoting action of nitroxyl radicals was observed for hydroperoxides and was not for diacylperoxides. The special behavior of the catalytic system with respect to hydroperoxides presupposed the participation of nitroxyl radicals in one of the key stages of proton transfer from the copper(II)center dot center dot center dot hydroperoxide complex in the overall reaction mechanism. We, however, did not observe direct interaction between nitroxyl radicals and copper(II) ions by the electron transfer mechanism.