【作者】 朱玉梅；

【导师】 杨元法；

【作者基本信息】 浙江师范大学 ， 物理化学， 2013， 硕士

【摘要】 氟代醇是一类重要的脂肪族含氟中间体,主要用于农药、医药合成、染料合成、材料、含氟表面活性剂等领域。二氟乙醇是氟代醇的典型代表,主要用于杀虫剂、除草剂和医药中间体。目前国内氟化工还处于起步阶段,而对于二氟乙醇的研究更少。文献表明,硼氢化钠直接还原二氟乙酸乙酯可制备二氟乙醇。但由于硼氢化钠价格较高、不够经济,因此采用催化加氢还原酯来制备二氟乙醇就成为了理想的方法。本文采用Ru/ZrO2·xH2O为催化剂,水作溶剂,催化加氢制备二氟乙醇,符合绿色化学的理念。实验围绕硼氢化钠还原二氟乙酸乙酯和Ru/ZrO2·xH2O催化二氟乙酸甲酯加氢制备二氟乙醇展开,主要研究内容有以下几个方面：1.以硼氢化钠为还原剂还原二氟乙酸乙酯制备二氟乙醇。考察了溶剂、反应温度、反应时间、硼氢化钠用量对该反应的影响。结果表明：反应最佳条件为0℃、n(NaBH4)/n(CF2HCOOCH2CH3)=0.6、乙醇为溶剂,此时二氟乙醇的收率可达到98.1%。并且对还原机理进行了推断。2.考察了Ru/ZrO2·xH2O对二氟乙酸甲酯催化加氢的反应性能。结果表明：以水溶剂,压力2.8MPa,140℃,反应5h,CF2HCH2OOCH3的转化率为100%,CF2HCH2OH的收率达到51%。3.考察了催化剂制备条件对该反应的影响。氨水为沉淀剂,Ru担载量为10%,不焙烧,pH=10为催化剂最佳制备条件。FT-IR、TG-DTA表征表明反应后催化剂中有单斜二氧化锆(m-ZrO2)生成,H2-TPR表征表明催化剂在还原时被还原的钌来自与载体结合不紧密的RuO2。4.对二氟乙酸加氢反应的研究表明：二氟乙酸甲酯加氢反应实质是二氟乙酸的加氢反应。二氟乙酸加氢反应的最佳溶剂为水,反应液pH的改变和C1-的添加均对该反应不利。并对Ru/ZrO2·xH2O上二氟乙酸加氢的反应机理进行了探究。更多还原

【Abstract】 Fluoroalcohols was an important aliphatic fluorine-containing intermediates, which was widely used in pesticide, medicine, coloring matter, material and fluoro-surfactant and so on.2,2-difluoroethanol was typical representative of fluoroalcohols, which was mainly used for pesticide, herbicide, and pharmaceutical intermediates. At present domestic fluorine chemical industry was still in its infancy, and researches of2,2-difluoroethanol was less. Literatures showed that2,2-difluoroethanol can be obtained by the reduction of ethyl difluoroacetate using sodium borohydride. Due to the high price of sodium borohydride, the preparation of2,2-difluoroethanol by the catalytic hydrogenation reduction of ester had become an ideal method. In this paper,2,2-difluoroethanol was obtained by catalytic hydrogenation in water used Ru/ZrO2xH2O as catalyst, which was a green method in chemistry. Experiments for the preparation of2,2-difluoroethanol were carried out around the reduction of ethyl difluoroacetate by using sodium borohydridethe and catalytic hydrogenation of methyl difluoroacetate by using Ru/ZrO2·xH2O catalyst. This paper studies mainly in the following respects:1.2,2-difluoroethanol was obtained by reduction of ethyl difluoroacetate using sodium borohydridethe. Effects of solvents,reaction temperature,reaction time, sodium borohydride dosage, and so on were investigated. The results showed that n (NaBH4)/n (CF2HCOOCH2CH3)=0.6, ethanol as solvent at0℃, the yield of2,2-difluoroethanol is98.1%in the reaction. And the mechanism for the reduction was deduced.2. Reaction performance of catalytic hydrogenation of methyl difluoroacetate by Ru/ZrO2·xH2O catalyst was investigated. The results showed that the water as solvent, pressure was2.8MPa,140℃, reaction time was5h, conversion rate of methyl difluoroacetate was100%, yield of2,2-difluoroethanol reached51%. 3. The effect of catalyst preparation conditions on the reaction was investigated. the best preparation conditions were that Ammonia as precipitant, Ru loading was10%, roasting, pH=10, FT-IR, TG-DTA characterization showed that monoclinic zirconium dioxide (m-ZrO2) was generated in the catalyst after reaction, H2-TPR characterization showed that the reduction of ruthenium was from the RuO2that not closely combined with carrier.4. Studies on hydrogenation reaction of difluoroacetic acid showed that the substance of hydrogenation of methyl difluoroacetate was hydrogenation of difluoroacetic acid. The best solvent of difluoroacetic acid hydrogenation reaction was water, the change of solution pH and Cl-adding were bad to the reaction. The mechanism of hydrogenation of difluoroacetic acid byRu/ZrO2·xH2O catalyst was explored.更多还原