疏水性咪唑类离子液体的水浴微波合成

Water-bath microwave synthesis of hydrophobic imidazolium-based ionic liquids

以溴代烷烃、N-甲基咪唑和六氟磷酸铵为原料,采用水浴微波法合成了3种疏水性咪唑类离子液体:[bmim]PF6、[hmim]PF6和[omim]PF6.结果表明,与传统方法相比,水浴微波法产率较高,且反应时间由传统的36 h缩短至50 min.通过正交试验对离子液体[bmim]PF6的水浴微波合成反应条件进行了优化,得到了适宜的合成条件:反应时间50 min,n(1-溴正丁烷)∶n(N-甲基咪唑)∶n(六氟磷酸铵)为1.1∶1.0∶1.0,微波功率385 W,产率可达到94.54%.结合反应机理对优化结果进行了分析,并通过红外光谱验证了3种疏水性离子液体的结构.

Three hydrophobic imidazolium-based ionic liquids （ [ bmim ] PF6, [ hmim ] PF6 and [ omim ] PF6 ） were synthesized by reacting alkyl bromide, N-methylimidazolium with NH4PF6 using water-bath microwave method. The results showed that： compared to the conventional method, the yield of production was higher, and the reaction time was dramatically reduced to 50 minutes from 36 hours. Meanwhile, reaction conditions of water-bath microwave synthesis of [ bmim ] PF6 were optimized by orthogonal experiments. The obtained optimization results were： reaction time 50 minutes, molar ratio of butyl bromide, N-methylimidazolium and NH4PF61.1： 1.0： 1.0, microwave power 385 W. Under the above conditions, the yield of [ bmim ] PF6 could reach 94. 54%. The optimization results were also discussed with synthesis mechanism, and three ionic liquids＇ structures were verified by IR spectrum.