Synchronously Synthesizing and Immobilizing N-Hydroxyphthalimide on Polymer Microspheres and Catalytic Performance of Solid Catalyst in Oxidation of Ethylbenzene by Molecular Oxygen
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- 作者：Baojiao Gao ; Suqing Meng ; Xiaolin Yang
- 刊名：Organic Process Research & Development
- 出版年：2015
- 出版时间：October 16, 2015
- 年：2015
- 卷：19
- 期：10
- 页码：1374-1382
- 全文大小：470K
- ISSN：1520-586X
文摘
Cross-linked copolymer microspheres of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) were first prepared (GMA/MMA microspheres), and then N-hydroxyphthalimide (NHPI) was synchronously synthesized and immobilized on the GMA/MMA microspheres to form a recyclable heterogeneous catalyst, GMA/MMA-NHPI, via several steps of polymer reactions by molecular design. A compositional catalyst was made with GMA/MMA-NHPI microspheres as the main catalyst and a transition metal salt as co-catalyst, and this compositional catalyst was used in the oxidation of ethylbenzene by molecular oxygen. The mechanism of the catalytic oxidation reaction was investigated, and the effects of some main factors on the catalytic oxidation reaction were examined. The experimental results show that, among several transition metal salts, Co(OAc)2 is the best co-catalyst, and the catalytic activity order is Co(OAc)2 > CoCl2 > Mn(OAc)2 > CuCl2. The compositional catalyst composed of GMA/MMA-NHPI microspheres and Co(OAc)2 can effectively catalyze the oxidation of ethylbenzene by molecular oxygen under mild conditions (at 100 掳C and ordinary molecular oxygen pressure), and transform ethylbenzene into acetophenone with a yield of 20.1% and a selectivity of 75.8% in 25 h. The catalytic oxidation follows a free radical chain reaction mechanism. The type of solvent used significantly affects the catalytic oxidation reaction, and acetic acid is a more suitable solvent compared with acetonitrile. For the compositional catalyst, there is an optimum amount of added co-catalyst Co(OAc)2; correspondingly, the optimum ratio of immobilized NHPI on GMA/MMA-NHPI microspheres to Co(OAc)2 is 14:1. The appropriate reaction temperature is 100 掳C. The solid catalyst, GMA/MMA-NHPI microspheres, exhibits good recycling and reusing properties.