【作者】 刘春杰；

【导师】 常瑜； 陈小平；

【作者基本信息】 太原理工大学 ， 应用化学， 2011， 硕士

【摘要】 本文对环氧乙烷氢甲酯化法合成3-羟基丙酸甲酯进行了系统研究,包括羰基钻催化剂制备、配体筛选、工艺优化和反应机理的探讨。通过研究,确定了最优催化剂体系和工艺条件,并对环氧乙烷氢甲酯化的反应机理进行了初步探讨。具体内容与结论如下：以醋酸钴为前驱体分别制备了八羰基二钴和四羰基钻钠两种催化剂,并对其活性进行了评价,结果表明,四羰基钴钠比八羰基二钻制备条件温和,成本低,更易实现。考察了膦配体和N-杂环配体等不同配体及助剂对反应的影响,发现N-杂环配体效果明显优于膦配体,而N-杂环配体中有羟基的3-羟基吡啶优于无羟基的咪唑,3-羟基吡啶受PH影响比较大,弱碱性对反应更有利。对3-羟基丙酸甲酯合成工艺条件进行了优化,得出环氧乙烷氢甲酯化合成3-羟基丙酸甲酯的最佳反应条件为：环氧乙烷浓度5 ml/30 ml甲醇,n(配体)：n(催化剂)=6：1,压力7.5 MPa,温度75℃,时间4h；在此条件下选择性和收率分别为95.7%和64.0%。最后,通过GC-MS分析,对副产物的组成和形成原因进行了探讨。以缔合机理(SN2)为基础,探讨了环氧乙烷合成3-羟基丙酸甲酯的反应机理。此反应中催化剂活性中间体为[Co(CO)4]-,催化剂的配体对催化剂活性中间体的形成和环氧乙烷的激活起重要作用。反应经过HCo(CO)4络合、CO插入、CO缔合、中间体反应(两条途径：直接生成和异构后生成)四个阶段完成。更多还原

【Abstract】 The carbomethoxylation of ethylene oxide to produce methyl 3-hydroxypropanoate was systematically studied in this paper, including the preparation of cobalt carbonyl catalyst, ligands selecting, process optimization and discussion of reaction mechanism. The optimum catalytic system and process was obtained and the reaction mechanism on carbomethoxylation of ethylene oxide was proposed in the research. The detailed contents and conclusions were as follows:The dicobalt octacarbonyl and tetracarbonyl cobaltate sodium were prepared with acetate cobalt as precursor. Their activities were evaluated. The results indicated that the tetracarbonyl cobaltate was more easily prepared with milder condition and lower cost.The effect of different ligands incluing phosphine and N-heterocycle ligands and additives on the reaction was investigated. It was found that the effect of N-heterocycle ligands was better than that of phosphine ligands and 3-hydroxypyridine with hydroxyl was superior to imidazole in N-heterocycle ligands. Moreover, the effect of 3-hydroxypyridine was influenced seriously by PH, within the additives the weak base was favor for the reaction.The synthesis process of methyl 3-hydroxypropanoate has been optimized. The yield and selectivity of methyl 3-hydroxypropanoate is 64.0% and 95.7% respectively at the optimum reaction condition:0.11 mol EO/30 ml methanol, 6:13-OH-Py/Co2(CO)8 ratio,7.5 MPa CO,75℃,4h.At last, the composition and formation reason of byproducts were studied by GC-MS analysis. On the basis of association mechanism(SN2), the reaction mechanism on synthesis of methyl 3-hydroxypropanoate has been proposed. The active intermediate of catalyst was [Co(CO)4]-, and the ligand played an important role on the formation of active intermediate for catalyst and activation of ethylene oxide. The reaction steps included HCo(CO)4 complex, CO insertion, CO association and intermediate reaction(two steps:formed directly and after isomerization).更多还原