Effect of pore size on the performance of mesoporous material supported chiral Mn(III) salen complex for the epoxidation of unfunctionalized olefins |
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Authors: | Kai Yu Zhicheng Gu Runan Ji Lan-Lan Lou Fei Ding Cui Zhang Shuangxi Liu |
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Affiliation: | aInstitute of New Catalytic Materials Science, College of Chemistry, Nankai University, Tianjin 300071, PR China;bState Key Laboratory of Elemento-organic Chemistry, Nankai University, Tianjin 300071, PR China |
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Abstract: | A series of mesoporous MCM-41 and MCM-48 materials with different pore sizes were synthesized and used as supports to immobilize chiral Mn(III) salen complex. The heterogeneous catalysts were characterized by XRD, FT-IR, DR UV–vis, and N2 sorption, and the results indicated the successful immobilization of chiral Mn(III) salen complex. The confinement effect of pore size on the catalytic performance of the heterogeneous catalysts was studied for the asymmetric epoxidation of unfunctionalized olefins with m-chloroperoxybenzoic acid as an oxidant. It was found that the conversions and enantiomeric excess (ee) values were closely correlated with the pore sizes of parent supports. The catalysts immobilized on the large-pore mesoporous supports exhibited higher conversions, and for the catalysts immobilized on MCM-41 materials, the ee values improved with increasing pore size. However, for the MCM-48 material-supported catalysts, the compatible pore size of the support with the substrate was beneficial for obtaining higher enantioselectivity in olefin epoxidation. |
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Keywords: | Confinement effect Pore size Mesoporous materials Chiral Mn(III) salen complex Immobilization Asymmetric epoxidation Unfunctionalized olefins |
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