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

Abstract

Organic polymers/inorganic zirconium hydrogen phosphate (ZSPP, ZPS-IPPA, and ZPS-PVPA) functionalized with 3-aminopropyltrimethoxysilane were prepared and used to support chiral MnIII (salen) complexes (Jacobsen’s catalyst). Different characterization methods demonstrated that the chiral MnIII (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.

Synthesis of GO-SalenMn and Asymmetric Catalytic Olefin Epoxidation

“…Thus, the electron cloud density of manganese atoms decreased after support, which was similar with the reported value [8,27], possibly because the micro environment changed after metallic Mn was immobilized with 3-aminopropyl trimethoxy silane and modified GO. A similar observation has also been made for a chiral salenMn III catalyst, which was axially grafted on an amine (-NH 2 ) group modified organic polymer/inorganic zirconium hydrogen phosphate through N-Mn bonding [28].…”

Synthesis of Sulfonic Acid-Functionalized Zirconium Poly(Styrene-Phenylvinyl-Phosphonate)-Phosphate for Heterogeneous Epoxidation of Soybean Oil

“…As shown in Table 3, it is obvious that the catalyst worked well for up to five cycles with no considerable decrease in reactivity (yield% from 60.06 to 55.25%). An unexpected discovery was that the catalytic activity of the catalyst was gradually restored at the 8th to 10th cycles of the catalyst when the ZPS-PVPA-SO 3 H was allowed to stand in 2 mol/L of dilute hydrochloric acid overnight after the 7th reuse; similar results have been reported in the asymmetric epoxidation of olefin catalyzed by ZPS-PVPA-SalenMn [12]. This novel phenomenon is probably due to the nano-layered self-supporting function [21] of the inorganic zirconium phosphate portion of the catalyst structure.…”

“…Organic polymer-inorganic hydrogen zirconium phosphate hybrid materials have been central to many areas of chemistry because they have the properties of organic and inorganic ingredients [12,13]. It is mainly because these materials have different hydrophilic or hydrophobic properties (regulating the ratio of organic polystyrene segments to inorganic zirconium hydrogen phosphate components), specific surface areas and holes of different sizes (regulating the ratio of organic polymers), and nanolayer structure.…”

Ultra‐low Mn(salen) supported on lignin and selective epoxidation of olefins

“…Even in the case of low grafting, Mn(salen)@LS shows a higher TOF (1833 h À 1 /Mn), which is superior to other supported Mn(salen) catalysts. [13,25,[27][28][29][30] The lower Mn contents of the catalyst may facilitate the distribution which involves much more isolated salen-Mn as the active site on the LS that could restrict the mobility and achieve the cooperation among the functional groups of LS. [31] To understand the supported effect associated with Mn-(salen), a lot of Mn(salen) immobilization catalysts have been prepared.…”