Preparation of chiral Salen-Mn(III) complex supported on MCM-41 and its catalytic properties for enantioselective epoxidation

MCM-41 was functionalized with 3-aminopropyl groups by the reaction of hydroxyl groups on the MCM-41 surface with 3-aminopropyltriethoxysilane being refluxed in toluene. By employing the reaction of amino groups with active ester groups on the chiral Salen-Mn(III) complex, the homogeneous chiral Salen-Mn (III) complex was heterogenized. The supported catalyst was characterized by FT-IR, DR UV-Vis, XRD, ICP, and N(2) adsorption. The results indicated that the complex was supported on MCM-41 and the native structure of MCM-41 was maintained. The supported catalyst was applied to the enantioselective epoxidation of 1,2-dihydronaphthalene using NaClO and m-chloroperbenzoic acid as oxidants. The results confirmed that the activity of the supported catalyst was lower than that of the homogeneous chiral Salen-Mn(III). However, its enantioselectivity was higher than that of the homogeneous one. A yield of 45.9% and ee of 84.3% of epoxide were obtained when 1,2-dihydronaphthalene was oxidized by NaClO for 12 h at 20 degrees C in the presence of the pyridine nitrogen oxide. About 34% of manganese leaching was observed after the supported catalyst was run 5 times.