Heterogeneous liquid-base oxidation of cyclohexene with manganese dioxide as catalyst

The oxidation of cyclohexene and the decomposition of cyclohexenyl hydroperoxide have been studied in liquid phase using manganese dioxide as catalyst. The dependence of the initial rate on the catalyst amount has been studied both for the oxidation and the decomposition reactions. It is postulated that a degenerate chain branching mechanism occurs. Hydroperoxide which is produced in the propagation step is decomposed on the solid, providing the free radicals necessary for the initiation of the chains. Cyclohexenol and cyclohexenone are produced in the initiation and termination steps. Above a critical catalyst to hydrocarbon ratio, no oxidation reaction was observed. At that critical composition, the rate of hydroperoxide decomposition was equal to its rate of formation. The length of the chain decreased to a low value with increasing catalyst to hydrocarbon ratios.