摘  要: 本文是以离子液体做催化剂，以柠檬酸和甲醇为原料通过酯化反应来制备柠檬酸三甲酯，用此方法可以简单方便的制得产物。但是，由于浓硫酸具有脱水、氧化、和腐蚀性，存在环境污染和对设备的腐蚀，因此，具有一定的局限性。吡啶离子液体作为酯化反应催化剂，可以得到好的转化率和产率，与传统方法相比易于分离且可重复利用，因此可代替浓硫酸来制得理想的产物。在探究反应的最佳条件方面，本论文设计了正交实验，为了得到最高的产品收率，我们探究了反应时间，最适合离子催化剂的用量和酸醇的摩尔比等因素对酯化反应的影响。实验结果表明，本论文得到的最佳实验条件是:酸醇的最佳摩尔配比1: 4，反应最适时间4 h，反应温度范围90-110 ºC，离子液体的最佳用量为3。7。此时，柠檬酸三甲酯的收率可达到84。6 %。最后本论文也提出了此反应所存在的问题，以便后续研究的进行。82138

毕业论文关键词：柠檬酸三甲酯；离子液体；催化剂；

Study on Synthesis of Citric Acid by Ionic Liquid Catalysis

Abstract: In this paper, trimethyl citrate is prepared using the ionic liquid as catalyst, the citric acid and methanol as precursors through a simple esterification reaction。 However, due to the character of dehydration, oxidation and corrosion, the existence of environmental pollution and equipment corrosion of concentrated sulfuric acid, the method is limited in some extends。 Imidazolium ionic liquids, as esterification catalyst, can obtain good percent conversion and productivity。 Compared with the traditional method, the products and the precursors can be easily separated and reused in our technique, respectively, as a result, imidazolium ionic liquids is an excellent candidate to replace concentrated sulfuric acid to obtain the ideal product。 To explore the optimum conditions of the reaction, the orthogonal experiment is designed in this paper。 In order to get the highest yield the product rate, we study on the reaction time, the most suitable ionic catalyst dosage and acid to alcohol and other factors effect on the esterification reaction。 The experimental results show that, the optimal experimental conditions is as follows: the optimum molar ratio of acid to alcohol is 1: 4, the optimal reaction time is 4 h,  the reaction temperature range of 90-110 ºC, and the best dosage of ionic liquids is 3。7。 At this time, the productivity of citric acid can reach 84。6 %。 Finally, this paper also put forward the problem of this reaction, so as to carry on the research。

Key Words: citrate; ionic liquid; catalyst

目    录

摘  要 1

引  言 2

1 实验部分 3

1。1 仪器与试剂 3

1。2  离子液体的制备 3

1。3  柠檬酸三甲酯的制备 3

2 结果与讨论 3

2。1 离子液体的表征 3

2。2 柠檬酸三甲酯的分析与检测 4

2。3 关于离子液体催化合成柠檬酸三甲酯的探讨 5

3 结  论 6

参考文献 7

致  谢 9

离子液体催化合成柠檬酸三甲酯

引　言

离子液体与传统的有机溶剂相比有一些特殊的性质[1, 2]。其优点包括：有良好的稳定性；较低的蒸气压；挥发小；对环境的污染较小；温度的变化范围较大；较高的溶解度等[3, 4]。离子液体能够引起人们的关注，与其这些特殊的性质和表现是分不开的，其可以作为现代有机合成的重要的绿色溶剂和催化剂，在绿色化学中会有广阔的发展前景[5-7]。论文网