Mn(II) Schiff base complex anchored in MCM-41 matrix as a heterogeneous catalyst for epoxidation of alkenes

Manganese Schiff base complexes have high catalytic activity for epoxidation of alkenes in homogeneous phase but this homogeneous catalyst is not facile separated and recycled. Therefore, more attempts have been made for immobilization of homogeneous catalysts on solid support such as MCM-41[1-2]. In this work anchoring Mn(II)Schiff base complex on MCM-41 matrix by forming urethane linkage between the surface hydroxyl groups of MCM-41 and one of the terminal isocyanate groups of DIC-4(1-4 Diisocyanatobutane) were described, while the other isocyanate ending was attached the hydroxyl groups in the salen ligand [3]. Heterogeneous MCM-41@DIC-Mn (Scheme 1) was synthesized according to literature [3] and their structure are well confirmed by FT-IR, XRD and ICP. A typical epoxidation process with H2O2 (30%) as a green oxidant is processed in a solution of ethanol containing olefin, imidazole as axial base and heterogeneous catalyst. The yields of epoxides were determined by GC.Furthermore, the effect of various parameters such as reaction time, amount of catalyst, oxidant and imidazole have been investigated. The optimum condition of the reaction shows the maximum conversion (93%) was obtained for cycloocten in optimum condition when Catalyst: Imidazole:olefin molar ratio is 1:100:30. The catalyst reusability confirm that catalyst is stable during oxidation reaction. The stability and reusability of catalyst was studied by separation of catalyst and reuse five times again without a detectable catalyst leaching or a significant loss of it activity(Table1). catalyst reusability confirm that catalyst is stable during oxidation reaction.