【作者】 侯志强；

【导师】 戴立益；

【作者基本信息】 华东师范大学 ， 物理化学， 2014， 博士

【摘要】 随着人口的急剧增长、资源的耗竭和工业的快速发展,环境问题日益严重。化学工业生产所带来的污染是当今环境污染的主要来源之一,因此,开发绿色化工技术已成为化学工业发展的必然趋势。近几十年来,超临界流体技术作为绿色化工技术的代表之一得到迅速发展,常见的超临界流体包括超临界水、超临界二氧化碳和超临界醇。与超临界水和二氧化碳相比,超临界醇除了具有超临界流体共有的优异传质性能外,还拥有以下3个特性：1、对于需较高操作温度和压力的工艺,超临界醇的操作条件更温和,对设备的腐蚀能力更低,产物的分离与提纯更为简单、节能；2、具有良好的溶解性,可以溶解木质素、纤维素等生物质资源和高分子材料；3、超临界醇既可以作为反应介质,又可以作为反应物参与烷基化反应,避免使用有毒害的烷基化试剂。因此,超临界醇在有机合成、废弃高分子材料回收、生物质资源化和纳米材料的制备等领域得到了广泛应用。酯类化合物在化工生产和日常生活中起着重要的作用,可作为医药合成的中间体,也可用于香料、香精、化妆品等的制造。采用传统的醇解反应制取酯类化合物时,存在许多问题,如需要加入强酸作为催化剂,腐蚀反应设备,产物不易分离等,且产物产率较低,反应时间过长。鉴于超临界醇的优势,采用超临界醇的方法有望克服传统方法的弊端,实现提高产物产率和缩短反应时间的目标。本论文中我们选取了脲、苯乙腈和己内酰胺作为研究对象,考察了其在超临界醇及醇水混合体系中的醇解制备酯类化合物的反应,并结合实验结果探讨了反应机理。研究内容有望丰富有机反应在超临界醇体系中的基础理论研究,并为工业化生产提供可靠的实验数据。具体研究内容如下：1.脲在超临界甲醇和乙醇体系中的醇解反应研究研究了尿素在超临界甲醇中生成碳酸二甲酯的醇解反应,考察了反应温度、反应时间、甲醇和脲的摩尔比、反应溶液的体积、少量水的添加和反应釜的处理方法对该醇解反应的影响。实验结果表明,在538K、2.0h、甲醇／尿素的摩尔比为14、反应溶液体积为285μL和清洗反应釜的溶剂为丙酮的条件下,得到碳酸二甲酯的最佳产率为98%。在最佳条件的基础上讨论了加入少量的水对该反应的影响。并提出尿素在超临界甲醇中的反应机理。同时也对脲在超临界乙醇中的醇解反应作了比较研究,探讨了反应温度、反应时间、填充气体和不同金属氧化物等对该反应的影响。研究结果表明超临界甲醇的反应活性要优于超临界乙醇。依据实验结果探讨了脲在超临界乙醇中的醇解反应机理。2.苯乙腈在超临界甲醇-水、乙醇-水和2-丙醇-水混合体系中的醇解反应研究研究了苯乙腈在超临界甲醇-水、乙醇-水和2-丙醇-水的混合体系中的醇解反应。并对反应温度、反应时间和摩尔比等反应条件进行了优化。实验结果表明,苯乙腈在超临界甲醇、乙醇和2-丙醇及水混合体系的醇解反应产物——苯乙酸甲酯、苯乙酸乙酯和苯乙酸异丙酯的最佳产率分别为70%、80%和31%。苯乙腈在甲醇和乙醇中溶解度的差异是导致苯乙酸乙酯的产率比苯乙酸甲酯产率高的根本原因。而2-丙醇在超临界态下的醇盐离子浓度较低,是导致苯乙酸异丙酯产率低的直接原因。依据实验结果探讨了苯乙腈在超临界醇水混合体系中的醇解反应机理。3.己内酰胺在超临界乙醇-水混合体系中的醇解反应研究研究了己内酰胺在超临界乙醇和水混合体系下的醇解反应,产物为6-氨基-己酸乙酯。考察了反应温度、反应时间、起始反应物的摩尔比和助剂等对产物产率的影响。在573K、2.5h、己内酰胺/水/乙醇的摩尔比为1：56：28和加入少量氯化锡作为催化剂的条件下,6-氨基-己酸乙酯的产率为98%。同时,研究了该反应的动力学特征,得出该反应为二级反应,并根据阿累尼乌斯方程式得出该反应在酸性和碱性条件下的活化能Ea分别为85kJ.mol-1和116kJ.mol-1。根据实验结果提出了己内酰胺在超临界乙醇与水混合体系的反应机理。更多还原

【Abstract】 With the rapid growth of population, depletion of resources, and the rapid development of industry, the environmental pollution has become more and more serious. The pollution caused by the chemical industry is the main source of today’s environmental pollution. The development of green chemical technology has become an inevitable trend of evelopment of chemical industry.In recent decades, the supercritical fluid technology as the representative of the green chemical technology obtained the rapid development. The supercritical fluids include the supercritical water, the supercritical carbon dioxide, and the supercritical alcohol. Compared with the supercritical water and carbon dioxide, the supercritical alcohol has the excellent mass transfer performance as well as other supercritical fluids. Besides, it also has the three characters, namely,1. For the technology operated at the high temperature and pressure, the supercritical alcohol has the advantages of the mild operating conditions, reducing the corrosion of the equipment, the simple and energy conservation for the product’s purification and separation.2. It has good solubility. In instance, it can be dissolved lignin, cellulose and other biomass resources and polymer materials.3. Supercritical alcohol can be used as reacton medium, and also be used as a reactant in alkylation reaction, which avoid using the toxic alkylation agents. So the supercritical alcohol is widely used in many fields, such as organic synthesis, the waste polymer recycled, the biomass resource, and the preparation of nanoparticles and so on.The esters or ester amine compounds plays an important role in the chemical production and daily life, being used as the medicine intermediate and making the spices,flavors, cometics etc. However, there are much drawback to produce these compounds by the conventional methods, such as adding strong acid as catalyst, easy corrosion reaction equipment, difficult separation of products, and low yield. Based on the advantage of supercritical alcohol, it could-resolve the problems to promote the yield and reduce the reaction time.In the paper, urea, nitrile and amide are used as subjects. And the alcoholysis of urea, phenylacetonitrile, and caprolactam in supercritical alcohol or alcohol/water system is proposed in order to enrich the application of organic synthesis using supercritical alcohol method and to provide the experimental data and the theoretical basis for the chemical industry.The details are given as follows:1. Research on the alcoholysis of urea in supercritical methanol and ethanolThe synthesis of dimethyl carbonate (DMC) from the direct alcoholysis of urea in supercritical methanol system was investigated. The effects of different reaction parameters, such as reaction temperature, reaction time, the molar ratio of methanol/urea, reaction pressure, the volume of reaction solution, the treating reactor and the amount of water on DMC yield were systematically investigated. The-experimental results indicated that the optimal reaction conditions were reaction temperature of538K, time of2h, the molar ratio of methanol/urea of14, and the reactor loading of285μL, respectively. And the DMC yield was98%under the optimal reaction condition. The reaction mechanism of urea in supercritical methanol was proposed. At the same time, the alcoholysis of urea in supercritical ethanol was compared with the alcoholysis of urea in supercritical methanol. The reaction condition, such as CO2(N2or air) loaded into the reactor and metallic oxides on the reaction was further investigated. It suggested that the reactivity of supercritical methanol is better than that of supercritical ethanol. A probable mechanism for alcoholysis of urea in supercritical ethanol was also proposed.2. Research on the phenylacetonitrile in supercritical alcohol with little water systemThe alcoholysis of phenylacetonitrile in supercritical methanol, ethanol and2-propanol with little water system was investigated. The effects of various operating conditions, such as the reaction temperature, the reaction time, the molar ratio of phenylacetonitrile/water/methanol or ethanol on product yield were systematically investigated. The experimental results indicated that the yields of methyl phenylacetate, ethyl phenylacetate, and isopropyl phenylacetate are70%,80%and31%, respectively. The solubility parameter of ethanol was close to phenylacetonitrile, but was greatly less than methanol which leaded to the yield of ethyl phenylacetate being higher than that of methyl phenylacetate. The low alkoxide ion concentration in supercritical2-propanol resulted in the low yield of isopropyl phenylacetate. At the same time, a plausible mechanism was proposed for phenylacetonitrile in supercritical methanol, ethanol and2-propanol with little water system.3. Research on the caprolactam in supercritical ethanol with waterThe reaction of caprolactam in supercritical alcohol with water system was investigated. The main product was ethyl-6-aminohexanoate. The effects of the reaction temperature, reaction time, molar ratio of reactant/water and additives on the yields of ethyl-6-aminohexanoate were systematically investigated. The optimal yield (98%) was obtained at573K,2.5h, molar ration of caprolactam/water/alcohol of1:56:28and SnCl2as additive. At the same time, the reaction between caprolactam and alcohol was proposed by a lumped kinetic equation as a second-order reaction in supercritical ethanol with water system, and the active energy was obtained according to the Arrhenius equation under the acid and base condition. Based on the experimental results, the reaction mechanism of caprolactam in supercritical ethanol with water was proposed.更多还原