Olefin Epoxidation Catalyzed by Sterically Bulky Metalloporphyrins (Metal=Fe,Mn) by Use of Sodium Hypochlorite as an Oxygen Source—A Kinetic Study

Abstract Substituents around an active center give a variety of effects on metalloporphyrin catalyses. In order to examine the effects of a substituent on the kinetic parameters, several olefins (styrene derivatives, cyclooctene and 1-octene) have been epoxidized by iron(III) and manganese(III) complexes of meso-tetrakis(2,6-dimethylphenyl)porphyrin or meso-tetrakis(2,6-dichlorophenyl)porphyrin in the presence of sodium hypochrolite as an oxidant. As previously reported for a manganese porphyrin system, the rate-profile of an iron complex can be described by the Michaelis–Menten equation. Several examples of an anomalous rate dependence on the olefin concentration have been observed. The ortho substituents have little influence on the binding affinity of the oxo–iron complex to olefin, in contrast to the case of manganese complexes. It is additionally proposed that the N-alkylation of an iron porphyrin has some correlation to the kinetic parameters.