Chinese Journal of Catalysis ›› 2014, Vol. 35 ›› Issue (9): 1446-1455.DOI: 10.1016/S1872-2067(14)60064-4

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Chiral Mn(Salen) supported on tunable phenoxyl group modified zirconium poly (styrene-phenylvinylphosphonate)-phosphate as an efficient catalyst for epoxidation of unfunctionalized olefins

Xiaochuan Zoua,b, Kaiyun Shia, Cun Wanga   

  1. a Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China;
    b College of Chemistry and Chemical Engineering, Research Institute of Applied Chemistry, The Key Laboratory of Applied Chemistry of Chongqing Municipality, The Key Laboratory of Eco-environments in Three Gorges Reservoir Region Ministry of Education, Southwest University, Chongqing 400715, China
  • Received:2014-01-30 Revised:2014-02-21 Online:2014-08-19 Published:2014-08-22
  • Supported by:

    This work was supported by the Basic and Frontier Research Project of Chongqing (cstc2013jcyjA50013), Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJ131504), and the Innovation Team Building at Institutions of Higher Education in Chongqing (KJTD201325).

Abstract:

We have developed a series of chiral Mn(Salen) (chiral Jacobsen's catalyst) catalysts that were axially supported onto zirconium poly(styrene-phenylvinylphosphonate)-phosphate through tunable phenoxyl linkers of varying steric hindrance, and evaluated their performance as catalysts (Cat1-Cat3) for the epoxidation of unfunctionalized olefins using m-chloroperbenzoic acid as an oxidant. The corresponding non-supported analogues (Cat4-Cat6) were also prepared and tested under similar conditions. The results demonstrated that the incorporation of substituents at the ortho-positions of the tunable phenoxyl linkers had a critical effect on the catalytic activity. Furthermore, the enantioselectivity increased as the steric hindrance imposed by the linker increased, although this also led to a decrease in the conversions under the same reaction conditions, especially for heterogeneous epoxidation. The heterogeneous system also displayed high ee values and conversions in the absence of the axial additive N-methylmorpholine N-oxide, which is commonly required to improve the catalytic activity of epoxidation reactions, especially for the epoxidation of α-methylstyrene. The reusability of the catalyst was also evaluated over 11 catalytic cycles, with no significant reduction observed in the catalytic activity or enantioselectivity after five runs.

Key words: Zirconium, Poly(styrene-phenylvinylphosphonate)-phosphate, Chiral Jacobsen’s Catalyst, Tunable phenoxyl linker groups, Asymmetric Epoxidation of Alkenes