【作者】 鹿骋；

【导师】 吕秀阳；

【作者基本信息】 浙江大学 ， 化学工艺， 2004， 硕士

【摘要】 近临界水与常温常压水相比具有一些优良性质，其电离常数大和介电常数小的特点使近临界水自身具备了酸碱催化功能和能同时溶解有机物和无机物的特性。这些特性使它既可作为有机化学反应的催化剂，又可用作反应物和溶剂。其催化性能可使某些酸碱催化反应不必加入酸碱催化剂，避免酸碱的中和、盐的处理等工序，避免环境污染；其溶解性能使之能用于替代有毒有害溶剂。 本研究以特定反应体系为对象，采用自行研制的高压反应装置，对近临界水中的水解反应和缩合反应进行了考察，以探索绿色化工过程的新技术和新方法。 1、测定了压力150bar下，温度152℃～216℃范围内乙酸苯酯在高温高压水中的水解反应动力学数据。结果表明在无任何外加催化剂的情况下，乙酸苯酯能够顺利进行水解反应。随温度升高，反应速率迅速增大，选择性从不足50％提高到80％以上。拟合得到反应活化能为67.77kJ／mol。 2、苯甲醛和乙醛以近临界水为反应介质，可在无外加催化剂和有机溶剂条件下发生羟醛缩合反应，生成肉桂醛。测定了反应时间3～8hr，温度220℃～300℃，反应压力160bar～250bar，反应物和水配比1:20～1:10范围内的各因素对反应的影响。该反应的最佳条件：温度260℃，压力160bar，苯甲醛和乙醛摩尔比1:3，反应物和水体积比1:15，反应时间5小时。更多还原

【Abstract】 Near-critical water can serve as a reactive medium for organic synthesis as a result of the changes that occur to its chemical and physical properties at elevated temperature. It has already shown its abilities to replace for many toxic organic solvents, and ability to catalyze reactions that traditionally require the addition of acid or base. The task of this work was to gain a better understanding of the hydrolysis and condensation reactions in near-critical water.The kinetics of non-catalyzed hydrolysis of phenylacetate in water at 150bar and temperature from 152℃ to 216℃ was investigated. From the results, we could see that no acid catalyst was needed for the hydrolysis reaction. With the increasing of temperature, the reaction rates increased sharply arid the selectivity of phenol went up from less than 50% to over 80%. The activation energy evaluated was 67.77 kJ/mol.Cinnamaldehyde was synthesized successfully through the reaction of phenylaldehyde with acetaldehyde in near-critical water, without any added catalyst or organic solvent. The phenylaldehyde conversion and the yield of cinnamaldehyde are influenced by the residence time, temperature, pressure and initial reactant volume. The optimal conditions are 260℃ , 160bar , 5hours, phenylaldehyde: acetaldehyde=l :3(mol), reactant:water=l: 15(volume).更多还原