Chiral MnIII (Salen) Immobilized on Organic Polymer/Inorganic Zirconium Hydrogen Phosphate Functionalized with 3-Aminopropyltrimethoxysilane as an Efficient and Recyclable Catalyst for Enantioselective Epoxidation of Styrene

Xiaochuan Zou; Yue Wang; Cun Wang; Kaiyun Shi; Yanrong Ren; Xin Zhao

doi:10.3390/polym11020212

Chiral Mn^III (Salen) Immobilized on Organic Polymer/Inorganic Zirconium Hydrogen Phosphate Functionalized with 3-Aminopropyltrimethoxysilane as an Efficient and Recyclable Catalyst for Enantioselective Epoxidation of Styrene

Polymers (Basel). 2019 Jan 26;11(2):212. doi: 10.3390/polym11020212.

Authors

Xiaochuan Zou¹, Yue Wang², Cun Wang³, Kaiyun Shi⁴, Yanrong Ren⁵, Xin Zhao^{6

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Affiliations

¹ Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China. zxcvip2003@163.com.
² Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China. b1083@163.com.
³ Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China. wangcun5224@126.com.
⁴ Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China. shiky@cque.edu.cn.
⁵ Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China. renyr@cque.edu.cn.
⁶ Department of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China. zhaoxin@cque.edu.cn.
⁷ Chongqing Collaborative Innovation Center of Functional Food, Chongqing University of Education, Chongqing 400067, China. zhaoxin@cque.edu.cn.
⁸ Chongqing Engineering Technology Research Center for Functional Food, Chongqing University of Education, Chongqing 400067, China. zhaoxin@cque.edu.cn.
⁹ Chongqing Engineering Laboratory of Functional Food, Chongqing University of Education, Chongqing 400067, China. zhaoxin@cque.edu.cn.

Abstract

Organic polymers/inorganic zirconium hydrogen phosphate (ZSPP, ZPS-IPPA, and ZPS-PVPA) functionalized with 3-aminopropyltrimethoxysilane were prepared and used to support chiral Mn^III (salen) complexes (Jacobsen's catalyst). Different characterization methods demonstrated that the chiral Mn^III (salen) complexes was successfully supported on the surface of the carrier (ZSPP, ZPS-IPPA, or ZPS-PVPA) through a 3-aminopropyltrimethoxysilane group spacer. The supported catalysts effectively catalyzed epoxidation of styrene with m-chloroperbenzoic acid (m-CPBA) as an oxidant in the presence of N-methylmorpholine N-oxide (NMO) as an axial base. These results (ee%, 53.3⁻63.9) were significantly better than those achieved under a homogeneous counterpart (ee%, 46.2). Moreover, it is obvious that there was no significant decrease in catalytic activity after the catalyst 3 was recycled four times (cons%: from 95.0 to 92.6; ee%: from 64.7 to 60.1). Further recycles of catalyst 3 resulted in poor conversions, although the enantioselectivity obtained was still higher than that of corresponding homogeneous catalyst even after eight times. After the end of the eighth reaction, the solid catalyst was allowed to stand in 2 mol/L of dilute hydrochloric acid overnight, prompting an unexpected discovery that the catalytic activity of the catalyst was recovered again at the 9th and 10th cycles of the catalyst.

Keywords: 3-aminopropyltrimethoxysilane-functionalized; asymmetric epoxidation; chiral MnIII (salen) complex; organic polymer/inorganic zirconium hydrogen phosphate.