Oxidation of alkanes with dioxygen induced by visible light and Cu(II) and Fe(III) chlorides

Cyclohexane and adamantane were oxidized in acetonitrile with dioxygen to the corresponding alcohols and ketones under irradiation of visible light in the presence of CuCl2 or FeCl3 catalyst. Fairly good selectivity of the products was attained with CuCl2: ca. 50% for cyclohexane and 75% for adamantane at over 50% conversion. Alkyl hydroperoxides were detected during the reactions in 10% and 25% amounts of the products at maximum for the cyclohexane oxidation with CuCl2 and FeCl3, respectively. Moreover, the products were overoxidized by the present system at comparable or slower rates than the alkanes. Other features of the reaction, such as the rate of oxygen uptake and carbon dioxide liberation, isotope effect, and radical inhibitor effect, were also investigated.