N-甲基咪唑合成工艺研究

摘要

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%. Conclusion: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.%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。