N-甲基咪唑合成工艺研究

Research on the Synthetic Technology of N-methylimidazole

目的:优化N-甲基咪唑合成工艺。方法:以乙二醛、甲胺、氨水、多聚甲醛为原料,"一锅法"合成N-甲基咪唑,对N-甲基咪唑转化率的影响因素-投料顺序、反应温度、反应时间等进行条件优化,通过N-甲基咪唑的标准折光率曲线法准确、快速检测反应过程中N-甲基咪唑含量。所得产品N-甲基咪唑分别用氢谱、碳谱以及气质联用GC-MS进行表征。结果:以当量的多聚甲醛、氨水、甲胺、乙二醛的投料顺序,反应温度为60℃,反应时间为4小时,N-甲基咪唑的转化率高达98%。通过减压蒸馏除水,共沸剂环己烷精制,最后减压蒸馏得到的产品N-甲基咪唑纯度可达到99.5%。结论:该合成工艺具有产品转化率高,污水处理量少,检测方法快速高效的优点,适合于大规模工业生产。

Objective： Different influential factors were optimized during the synthetic technology of N - methy- limidazole in synthesizing process. Method： N - methy - limidazole was synthesized by a one - pot reaction with using glyoxal, methylamine, ammonia and paraformaldehyde as raw materials. The influential factor including materials adding order, reaction temperature and reaction time on the conversion rate of N - methy - limidazole were optimized. The content of N - methy - limidazole in synthesizing process was also accurately and rapidly de- tected through the standard curve of refractive index for N - methy - limidazole. The chemical structure of the fi- nal product was characterized by 1H and 13C NMR spectroscopy and （GC -MS） mass spectrometry. Result： The results show that the conversion of the reaction is over 98% using the materials adding order of paraformalde- hyde, ammonia methylamine and glyoxal, reaction temperature of 60℃ and reaction time of 4 h. The water was removed under vacuum and then using cyclohexane as azeotrope, the product was finally obtained with a purity of 99.5%. Conduslon： The synthetic technology has the advantages of high conversion, low sewage treatment, rapid and efficient detection method, which will be suitable for the industrial production.