Novel chiral core–shell silica microspheres with trans -(1 R ,2 R )-diaminocyclohexane (DACH) moiety bridged in the mesoporous shell were synthesized using layer-by-layer method. The chiral mesoporous shell around the nonporous silica core was formed by the co-condensation of N , N ′- bis -[(triethoxysilyl)propyl]- trans -(1 R ,2 R )- bis -(ureido)-cyclohexane (DACH-BS) and tetraethoxysilane (TEOS) using octadecyltrimethylammonium chloride (C 18 TMACl) and triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (P123) as the templates. The functionalized core–shell silica microspheres were characterized and tested as chiral stationary phases for high performance liquid chromatography (HPLC). R / S -1,1′-bi-2,2′-naphthol, R / S -6,6′-dibromo-1,1′-bi-2-naphthol and R / S -1,1′-bi-2,2′-phenanthrol were enantioseparated rapidly on the column packed with the DACH core–shell silica particles. Moreover, the column packed with core–shell particles exhibited better performance than the column packed with the DACH functionalized periodic mesoporous organosilicas.
Huanxin Li,Junwei Zhang,Yonghui Dou,Li Xu,Guoji Liu
(Liquid + liquid) equilibrium data for the ternary systems of {(2-Methyl-1-propanol or 3-Methyl-1-butanol) + (1 R ,2 R )-(−)-1,2-Diaminocyclohexane + water} were measured at (288.2–318.2) K under atmospheric pressure. The Othmer-Tobias and Hand equations were employed to verify the reliability of the experimental data. Besides, the distribution coefficients and selectivity factors calculated from the experimental tie-line data were applied to evaluate the extraction performance of separating (1 R ,2 R )-(−)-1,2-Diaminocyclohexane from aqueous solution and 3-Methyl-1-butanol was proved to be very promising. Furthermore, the binary interaction parameter values were obtained by correlating the experimental data with NRTL and UNIQUAC models. All the RMSD values were less than 0.0184, indicating that both models can be used to describe the liquid-liquid equilibrium behaviour of the studied systems.
Li C. L.,Wang S. Y.,Zhan M. R.,Chen C. C.,Wang Z. X.
Chiral monosubstituted cyclohexanediamine catalyst, namely (1 R ,2 R )-2-(piperidin-1-yl)cyclohexan-1-amine ( Cat1 ) has been efficiently synthesized and used to catalyze the aldol reaction of cyclohexanone and 2-(trifluoromethyl)benzaldehyde to obtain ( R )-2-{( S )-hydroxy[2-(trifluoromethyl)phenyl]methyl}cyclohexan-1-one. The catalyst (20 mol %) provided high yield (up to 85%) and excellent enantioselectivity (95.6% ee ) in water solution in three parallel tests.
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