Manganese porphyrin in solution and heterogenized in different materials mediates oxidation of hydrocarbons by iodosylbenzene

Abstract

We prepared a free base porphyrin (HP) containing hydroxy and methoxy groups in the mesophenyl substituents of the porphyrin ring. We then inserted Mn(III) ion into the resulting HP, to obtain MnP. We used silica synthesized by the sol–gel process to immobilize the MnP in either acidic or basic medium, which afforded the solids MnPA and MnPB, respectively. We also conducted the solvothermal Mn(III) ion insertion into HP, which furnished the self-structured solid MnPS. Because the MnP was catalytically active in homogeneous medium, we investigated the activity of all the prepared solids as heterogeneous catalysts in the oxidation of various hydrocarbons. MnPA, MnPB, and MnPS presented similar or higher activity than the homogeneous MnP in the oxidation of cyclooctene, cyclohexene, cyclohexane and n-heptane. Concerning alkane oxidation, the heterogeneous catalysts were more selective for the alcohol than the MnP in homogeneous solution. Moreover, the solid catalysts favored the oxidation of linear alkane, with selectivity toward the primary alcohol. We were able to recover all the solids at the end of the reaction and reuse them.