D. Jiang, Qihua Yang, Hong Wang
Apr 1, 2006
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Influential Citations
62
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Journal
Journal of Catalysis
Abstract
With benzyl group as a linker, trans-(1R,2R)-diaminocyclohexane was incorporated into the framework of mesoporous silica through one-step co-condensation of tetramethoxysilane with N,N � -bis[4-(trimethoxysilyl)benzyl]-( −)-(1R,2R)-diaminocyclohexane using cetyltrimethylammonium bromide as a structure-directing agent under basic conditions. All materials were fully characterized by X-ray diffraction, N 2 sorption isotherms, transmission electron microscopy, and 13 Ca nd 29 Si cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy. Coordinated with [Rh(cod)Cl]2, the material exhibited a TOF up to ∼414 h −1 with 30% ee for the asymmetric transfer hydrogenation of acetophenone. Various ketones were hydrogenated with different activities and enantioselectivities. An enantioselectivity of about 61% ee was observed in the case of 2-acetylnaphthalene. Moreover, a comparison of the catalytic properties of the materials with benzyl and propyl groups as linkers indicates the importance of the rigidity and electron-withdrawing ability of the linker in the high reaction rate of the catalysts.