Enzyme‐Like Selectivity on Metalloporphyrin‐Catalyzed Oxidation by a Linear Homopolymer

Abstract

AbstractThe influence of linear homopolymers on manganese porphyrin‐catalyzed oxidation of cyclohexene and phenol in solution was investigated. Cyclohexene was epoxidized in presence of poly(sodium acrylate)/poly(acrylic acid) (PAA) and H2O2, but the epoxide was the exclusive product only when the reaction was catalyzed by the manganese porphyrin. The regioselectivity of phenol catalytic oxidation in the para position increased up to 81±14 % with PAA, however the same was not observed when PAA‐substrate hydrogen bonding is hampered in oxidation of methoxybenzene. Unlike other bio‐inspired systems the PAA polymer chain was not covalently bound to the metalloporphyrin, but it still promotes chemo‐ and regioselectivity. Catalytic data indicate active participation of the polymeric chain in epoxidation reaction in order to change the active oxidizing agent in the presence of the manganese porphyrin. The PAA chains act as a supramolecular directing agent, which binds phenol via hydrogen bond providing a favorable orientation for regioselective oxidation in the para position. The polymer chain dual role is unprecedented in enzyme‐like catalysis with metalloporphyrin.