Aerobic oxidation of cyclohexene catalyzed by Fe(III)(5,10,15,20-tetrakis(pentafluorophenyl)porphyrin)Cl in supercritical CO2

The kinetics of aerobic oxidation of cyclohexene catalyzed by Fe(III)(5,10,15,20-tetrakis(pentafluorophenyl)porphyrin)Cl in supercritical CO2 was studied at 50 °C and 165 atm of the total pressure with ca. 20 atm O2 partial pressure. The reaction proceeded to yield allylic oxidation products, i.e. 2-cyclohexen-1-ol and 2-cyclohexen-1-one, and epoxidation products, i.e. cyclohexene oxide and 7-oxabicyclo[4,1,0]heptan-2-one. The reaction was retarded in the presence of radical inhibitor, 2,6-di-tert-butyl-4-methylphenol. The overall reaction rate under the steady state was dependent with ca. second order on the cyclohexene concentration, and zero order on the O2 concentration except for the very small O2 pressure range. These kinetic behaviors could be analyzed on the basis of the free radical allylic oxidation mechanism.