Epoxidation of Styrene with Aqueous Hypochlorite Catalyzed by a Manganese (III) Porphyrin Bound to Colloidal Anion-Exchange Particles

Abstract

Epoxidation of styrene in aqueous sodium hypochlorite solution was catalyzed by the tetrasodium salt of 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphinatomanganese(III) chloride (1). Manganese porphyrin 1 was more active bound to 60 nm diameter colloidal anion exchange particles than in aqueous solution: 0.12 mol % of 1 bound to four different types of particles gave 71-81% conversion of 1.2 mmol of styrene to styrene oxide with 1.5 mmol of hypochlorite in 1 h at room temperature. Although the activity of the catalyst decreased with time due to oxidative degradation of the porphyrin, 620 mol of styrene oxide per mol of catalyst were produced in the presence of excess oxidant. The conditions were highly selective for epoxidation of styrene: substituted styrenes epoxidized more slowly, and aliphatic alkenes did not react. Visible spectra indicated that oxidized forms of 1 were present in the hypochlorite solutions, and that the form of 1 in solution was different from that in the particles