不同介质下木质素降解转化为香兰素的研究
时间:2017-06-22 17:28 来源:毕业论文 作者:毕业论文 点击:次
| 摘要：本论文首先利用N-甲基咪唑与溴代正丁烷反应合成了离子液体中间体：溴化1-丁基-3-甲基咪唑([Bmim]Br)，进而用[Bmim]Br分别与醋酸钾、KOH进行阴离子交换反应，合成离子液体： 1-丁基-3-甲基咪唑醋酸盐（[Bmim]OAC）和氢氧化1-丁基-3-甲基咪唑([Bmim]OH)。通过核磁共振对所合成的离子液体进行了结构表征和确认。接着，研究木质素在这两种离子液体中降解得到香兰素的情况，并和以NaOH的碱性溶液为反应介质的实验进行对照。实验结果表明，NaOH碱性溶液作为反应介质得到的香兰素产率较高。最后研究了在NaOH的碱性溶液中木质素降解转化为香兰素的较优条件，考察木质素氧化过程中催化剂用量和反应温度的变化对香兰素的产量的影响。实验结果表明，最佳工艺条件为： 在NaOH的碱性溶液（PH=11~12）中，催化剂量为木质素重量的10%，反应温度为100℃，反应时间为3h。在最佳工艺条件下，香兰素的收率为8.1%。10554 关键词：木质素；香兰素；离子液体 Study on degradation of lignin for synthesize vanillin in different medium Abstract: In this paper ,the intermediate of ionic liquid : 1-Butyl-3-methylimidazolium Bromide was prepared which are generated from N－methylimidazole with butyl bromide. Then we used the intermediate synthesizes two ionic liquids through anions exchange with potassium acetate and potassium hydroxide. The two ionic liquids are [Bmim]OAC and [Bmim]OH. And their structures were characterized confirmed by 1HNMR.Then, degradation of lignin for synthesize vanillin were studied in two ionic liquids and the alkaline solution of sodium hydroxide was placed in the control experiment. The experimental results shows that the alkaline solution of sodium hydroxide as reaction medium was better. Finally , the better conditions of lignin for synthesize vanillin were studied in the alkaline solution of sodium hydroxide. The influence of process factors, such as amount of the catalyst and reacting temperature upon the yield of vanillin were investigated. The optimal reaction condition as following, medium is in the alkaline solution of sodium hydroxide （PH=11~12）, the catalyst amount is 10% according to the quantity of lignin,reacting temperature is 100 ℃，reaction time is 3h,the best yield of vanillin was about 8.1%. Key words: lignin; vanilla; ionic liquids 目录 1前言 1 1.1 木质素的简介 1 1.2 香兰素简介 3 1.2.1 香兰素的生产 4 1.3离子液体简介 7 1.3.1 离子液体的定义及发展 8 1.3.2 离子液体的性质 9 1.3.3 离子液体的分类 9 1.3.4 离子液体的合成 10 1.3.5离子液体的应用 10 1.4研究的目的和意义 12 2 实验方法与内容 13 2.1 实验原料及试剂 13 2.2 实验装置 13 2.3 实验方法 14 2.3.1离子液体的制备 14 2.3.2木质素合成香兰素 15 3 实验结果及讨论 16 3.1 离子液体的制备 16 3.1.1 1-丁基-3-甲基咪唑醋酸盐的制备 16 3.1.2 氢氧化1-丁基-3-甲基咪唑的制备 17 3.2 木质素制备香兰素 18 3.2.1不同用量催化剂香兰素产率比较 19 3.2.2 改变反应温度 20 3.3 香兰素的结构分析 20 3.3.1 核磁共振分析 20 4 结论 21 致谢 22 参考文献 23 附录 25 (责任编辑：qin) |