Decay kinetics of cumylperoxyl radical produced by the decomposition of cumene hydroperoxide

Cumylperoxyl radicals, produced by the decomposition of cumene hydroperoxide on heterogeneous catalysts (manganese dioxide and cobalt oxide supported on silica) at 300 and 295 K, have been detected in the liquid phase by use of e.s.r. spectroscopy. The decay kinetics of cumylperoxyl radicals have been investigated at various initial concentrations of the peroxyl radical (2.3 × 10^-6-1.12 × 10^-5M) over a range of the initial hydroperoxide concentration (0.74-4.70M). The decay of cumylperoxyl radicals strictly obeyed first-order kinetics with rate constant k_t =0.15 ±0.01 s^-1 at 300 K, irrespective of the initial hydroperoxide concentration, the solvent used as diluent (carbon tetrachloride, benzene, and cumene), and the catalyst (manganese dioxide and cobalt oxide supported on silica).