Catalytic asymmetric epoxidation of unfunctionalized olefins using a series novel type of layered crystalline organic polymer–inorganic hybrid zinc phosphonate–phosphate immobilized aryldiamine modified chiral salen Mn(III) complex
In this report we demonstrate the suitability of layered crystalline organic polymer–inorganic hybrid material ZnPS–PVPA with different content of the organic group and different inorganic phosphate as catalyst supports for asymmetric catalysis. A series of the chiral salen Mn(III) complex immobilized onto ZnPS–PVPA modified by aryldiamine were synthesized and characterized by FT-IR, diffusion reflection UV–vis, AAS, N2 volumetric adsorption, SEM, TEM, XRD and TG. The supported catalysts displayed superior catalytic activities in the asymmetric epoxidation of α-methylstyrene and indene with m-CPBA and NaIO4 as oxidants, compared with the corresponding homogeneous catalyst (ee, >99% vs 54% and >99% vs 65%). And the heterogeneous catalysts are relatively stable and can be recycled nine times in the asymmetric epoxidation of α-methylstyrene. These results revealed that the special structure of ZnPS–PVPA played vital impacts on the conversion and enantioselectivity. Furthermore, this novel type of catalyst can also be validly used in large-scale reactions with superior catalytic disposition being maintained at the same level, which possessed the potentiality for application in industry.
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (157 K)Download as PowerPoint slideHighlights► Organic polymer–inorganic hybrid material layered crystalline ZnPS–PVPA was synthesized and characterized. ► The chiral salen Mn(III) was immobilized on aryldiamine modified ZnPS–PVPA. ► The heterogeneous catalysts displayed superior activity according to the homogeneous catalysts. ► The heterogeneous catalysts could be reused at least nine times without significant loss of activity. ► The catalysts could be used in large-scale reactions with superior catalytic disposition.
Journal: Applied Catalysis A: General - Volume 407, Issues 1–2, 4 November 2011, Pages 163–172