Novel catalysts for methane activation

Several naturally occurring enzymes, such as cytochrome P-450 and methane monooxygenase, catalyze the oxidation of alkanes to alcohols at low temperatures and pressures. We are attempting to develop catalysts that mimic the activity of these enzymes. Computer-aided design studies on unique carboranyl porphyrins have shown that they can have a pocket analogous to those of the enzymes. This work uses molecular-energy dynamics calculations to evaluate the methane interactions with the synthetic compounds. Activity tests have been devised for oxidation of cyclohexane, hexane and butane with iodosylbenzene as the oxidant, methylene chloride as the solvent, and Fe, Mn, Ni, and Rh tetraphenyl porphyrins and Fe and Mn tetra(pentafluorophenyl) porphyrins as catalysts. Results showed that Fe and Mn were the most active metals. With the Fe tetra(pentafluorophenyl) porphyrin, cyclohexanol, hexanol and butanol yields (based on oxidant) were 80%, 64% and 40%, respectively. Additional tests are being developed for oxidation of ethane and methane. 17 refs., 8 figs.