Liquid phase selective oxidation of diphenylmethane to benzophenone over ternary hydrotalcites with tert-butylhydroperoxide

Selective oxidation of diphenylmethane to benzophenone was carried out over M–MgAl ternary hydrotalcites, where M is Cu, Co or Fe, using tert-butylhydroperoxide (TBHP) as an oxidant. Influence of various reaction parameters, such as reaction temperature, reaction time, substrate: catalyst mass ratio, substrate: oxidant mole ratio and nature of solvent on the activity and selectivity for the desired reaction were evaluated. Among the catalysts studied CuMgAl-13 showed a maximum diphenylmethane conversion of 95% with 100% selectivity towards benzophenone, at 65 oC/24 h with TBHP as an oxidant and acetonitrile as a solvent. Redox metal species present in the hydrotalcite structure were thought to be the active centers involved and a reaction mechanism involving free radicals was proposed.