Aerobic Epoxidation of Alkenes with Manganese (III) Salen Complexes Immobilised Onto Aminopropyl-Hms
Jamil Khan1, Peter Styring1, and Adam F. Lee2. (1) Department of Chemical and Process Engineering, University of Sheffield, Hadfield Building, Mappin Street, Sheffield, United Kingdom, (2) Department of Chemistry, University of York, Heslington, York, United Kingdom
A multi-grafting technique has been used for the anchoring of new salen manganese complexes, Mn-Sal-Lys onto modified hexagonal mesoporous silica (HMS) with aminopropyl groups and 4-(aminomethyl)benzoic acid. The HMS material was analysed with FT-IR, N2 adsorption and XPS. Along with two homogeneous complexes, the catalytic activity was tested for the aerobic epoxidation of cyclohexene and styrene to their oxides using isobutyraldehyde as a co reductant under mild conditions. The homogeneous catalysts were more active however it is possible to get good yields and selectivity from the immobilised catalysts. Repeated experiments were conducted and even after the fifth run, the results show some consistency with some drop in performance.