含环氧基团的聚合物微球固载2,2,6,6-四甲基哌啶氮氧自由基催化剂的制备及其催化分子氧氧化苯甲醇  

Immobilized 2,2,6,6-tetramethyl-piperidinyl-1-oxy catalyst on polymer microspheres and its catalytic oxidation of benzyl alcohol with molecular oxygen

作　　者：余依玲[1] 高保娇[1] 李艳飞[1] 

机构地区：[1]中北大学化学工程系,山西太原030051

出　　处：《催化学报》2013年第9期1776-1786,共11页

基　　金：山西省自然科学基金(201002100843)~~

摘　　要：以甲基丙烯酸缩水甘油酯(GMA)为单体,以乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,采用悬浮聚合法制得交联聚甲基丙烯酸缩水甘油酯(CPGMA)微球,然后以4-羟基-2,2,6,6-四甲基哌啶氮氧自由基(4-OH-TEMPO)为试剂,使CPGMA微球表面的环氧基团发生开环反应,从而制得了TEMPO固载化微球TEMPO/CPGMA,考察了制备条件对固载化反应的影响,并采用多种方法对微球TEMPO/CPGMA进行了表征.将微球TEMPO/CPGMA与CuCl组成共催化体系,用于分子氧氧化苯甲醇,考察了反应条件对催化体系性能的影响.结果表明,以含环氧基团的聚合物微球CPGMA为载体,通过开环反应,可成功地实现TEMPO的固载化,开环反应属SN2亲核取代反应,适宜采用溶剂N,N′-二甲基甲酰胺和反应温度85℃.非均相催化剂TEMPO/CPGMA与助催化剂CuCl构成共催化体系,在室温、常压O2条件下可高效地将苯甲醇氧化为苯甲醛,产物选择性和产率分别为100%和90%.主催化剂TEMPO与助催化剂CuCl适宜的摩尔比为1:1.2;主催化剂适宜用量为0.90g.此外,TEMPO/CPGMA固体催化剂具有良好的循环使用性能.Crosslinked polymer (glycidyl methacrylate) microspheres (CPGMA) were prepared with glycidyl methacrylate as monomer and ethylene dimethacrylate as crosslinker by suspension polymerization. The ring opening reaction between the epoxy groups on the CPGMA microspheres and 4-hydroxy-2,2,6,6-tetramethyl-piperidinyl-1-oxy (4-OH-TEMPO) was carried out to immobilize TEMPO on the polymer microspheres. TEMPO-immobilized microspheres (TEMPO/CPGMA) were obtained and were characterized by several methods. The effects of the main factors in the immobilization were examined so that the reaction conditions were optimized. On this basis, a co-catalyst system was constituted with TEMPO/CPGMA and CuCl and was used in the oxidation reaction of benzyl alcohol by molecular oxygen. The catalytic activity of the co-catalyst system and the effects of the main factors were examined. The experimental results showed that the ring opening reaction of the epoxy group allowed the immobilization of TEMPO to be smoothly realized on the CPGMA polymer microspheres, on which there were many epoxy groups. The ring opening reaction of the epoxy group is a nucleophilic substitution reaction with the S N2 reaction mechanism, and N,N′-dimethyl formamide with a strong polarity is an appropriate solvent and a suitable temperature is 85 ℃. The co-catalyst system consisting of the heterogeneous catalyst TEMPO/CPGMA and CuCl efficiently catalyzed the oxidation reaction of benzyl alcohol by molecular oxygen. Under mild conditions, benzyl alcohol was transformed to benzaldehyde with 100% selectivity and a yield of 90%. The suitable molar ratio of the main catalyst TEMPO/CPGMA to the co-catalyst CuCl is 1:1.2 and the suitable amount of TEMPO/CPGMA is 0.90 g. The TEMPO/CPGMA catalyst has excellent recyclability.

关 键 词：聚甲基丙烯酸缩水甘油酯 氮氧自由基 固载 醇氧化 分子氧 

分 类 号：O643.32[理学—物理化学]