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使用不同空间位阻的苯氧链接手臂修饰的聚(苯乙烯基-苯乙烯膦酸)-磷酸氢锆轴向固载手性MnIII(Salen)催化剂(Cat1–Cat3),随后在间氯过氧苯甲酸(m-CPBA)为氧化剂的体系中考察了固载催化剂的催化性能.同时,在相同氧化体系下测试了一系列均相催化剂类似物(Cat4–Cat6).结果表明,在非均相条件下,可调变苯氧链接手臂的邻位取代基对催化剂活性起着重要作用,环氧化产物的对映选择性随着取代基位阻的增加而增大,但产物转化率有一定程度下降.此外,非均相催化剂即使在没有轴向助剂的参与下(通常需要添加,为了增大催化活性)仍然表现出非常高的催化活性,尤其对α-甲基苯乙烯反应,其对映选择性从6.8%增加到76.8%,转化率从19.8%上升到90.7%.制备的非均相催化剂11次的循环使用实验表明,在前5次使用后催化剂活性与对映选择性没有明显变化.
The chiral MnIII (Salen) catalyst (Cat1-Cat3) was axially immobilized with different sterically hindered phenoxy chain-arm modified poly (styryl-styrene phosphonic acid) Benzoic acid (m-CPBA) as the oxidant system.At the same time, a series of homogeneous catalyst analogs (Cat4-Cat6) were tested under the same oxidation system.The results showed that in the heterogeneous Under the conditions, the vicinal substituents of the adjustable phenolic linked arms play an important role in the activity of the catalyst. The enantioselectivity of the epoxidation products increases with the increase of the steric hindrance of the substituents, but the conversion rate of the product is certain In addition, heterogeneous catalysts still exhibit very high catalytic activity even without the aid of an axial promoter, which usually needs to be added, in order to increase the catalytic activity, especially for α-methylstyrene reactions, which The enantioselectivity increased from 6.8% to 76.8%, and the conversion rate increased from 19.8% to 90.7%. The 11 cycles of the prepared heterogeneous catalyst showed that after the first 5 cycles, the catalyst activity and enantioselectivity were not obvious change.