1-烷基-2,3-二甲基咪唑溴盐的合成及表征

Synthesis and characterization of 1-alkyl-2,3-dimethylimidazolium Bromides

以1,2-二甲基咪唑和溴代烷烃为原料,合成了5种离子液体中间体1-烷基-2,3-二甲基咪唑溴盐.讨论了反应时间、反应温度和原料摩尔比对产物收率的影响,得到最佳的条件是：溴代烷烃与1,2-二甲基咪唑以1.1∶1（摩尔比）的比例,在90℃下反应24 h.产物结构经IR和1H-NMR确证,得出结论：阳离子烷基链长度的增加会使3 100～3 000 cm^-1波数范围内谱带减弱,降低离子液体的熔点,而对咪唑环上质子化学位移影响不大.

Five ionic liquid intermediates 1 -alkyl -2, 3 -dimethylimidazolium bromides were synthesized from 1,2 - dimethylimidazolium and alkyl bromides. The effects of reaction temperature and time and molar ratio of materials were investigated. The optimum conditions were ： molar ratio of alkyl bromides and 1,2 - dimethylimidazolium was 1. 1 ： 1, temperature was 90 ℃, time was 24 h. Their structures were characterized by IR and 1 s - NMR. It was concluded the increase of alkyl chain length of cation would weaken band during 3 100 -3 000 cm^-1 and decreased melting point of ionic liquids, but had weaker effect on proton chemical shifts of imidazolium ring.