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Chem. J. Chinese Universities ›› 2002, Vol. 23 ›› Issue (9): 1758.

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Studies on the Enantioselective Hydrogenation of Ethyl Pyruvate Catalyzed by γ-Al2O3 Support Rhodium Nanocluster/Quinine

XIONG Wei1,2, MA Hong-Xia1, CHEN Hua1, HUANG Yan-Yi1, HUANG Yu-Lin1, LI Xian-Jun1, LI Xing-Shu3, QI Jian-Ying3, CHEN Xin-Zi3   

  1. 1. College of Chemistry, Sichuan University, Chengdu 610064, China;
    2. Department of Chemistry, Xichang Normal College, Xichang 615022, China;
    3. Department of Applied Biologyand Chemical Technology, Hong Kong Polytechnic University, Hong Kong, China
  • Received:2001-08-03 Online:2002-09-24 Published:2002-09-24

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Abstract: In the asymmetric hydrogenation of ethyl pyruvate catalyzed by Rh/PVPand Rh/PVP-γ-Al2O3, quinine as a chiral modifier can not only induce the enantioselectivity but also greatly accelerate the reaction rate.When nanocluster of Rh/PVPis supported on γ-Al2O3, the catalytic activity and enantioselectivity increase obviously. Comparing the turnover frequency(TOF) and enantiomeric excess of R-(+)-ethyl lactate(e.e. value) of Rh/PVPwith Rh/PVP-γ-Al2O3, the TOF and e.e. value rise by a factor of 10.6 and 2.03, respectively. The results indicate that γ-Al2O3 plays a very important role in the asymmetric hydrogenation for the accelaration of the reaction and promoting the increase of enantioselectivity. It is possible that γ-Al2O3 is fovourable for the dispersion of Rh/PVPon the support surface and inhibits the aggregation of Rh/PVP. Under the optimum conditions of 20 ℃, 7.0 MPa H2 and 3.86×10-3 mol/L of quinine concentration in tetrahydrofuran, TOFand e.e. value using Rh/PVP-γ-Al2O3 as catalyst can reach 871h-1 and 54.7%, respectively. When reaction temperature decreases to 3 ℃, the e.e. value increases to 59.2%.

Key words: Rhodium nanocluster, Ethyl pyruvate, Quinine, Enantioselective hydrogenation

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