新型离子液体1-烷基-3-甲基咪唑苯甲酰基三氟硼酸盐的合成与性质

合成了新型离子液体1-烷基-3-甲基咪唑苯甲酰基三氟硼酸盐C_nmim]BTB](n=4,6,8),并通过NMR、差热、热重等方法研究了其基础物化性质。 结果发现,3种离子液体的分解温度在200 ℃左右;随着阳离子碳链的增长,离子液体的粘度、熔点逐渐升高,并从亲水性变为疏水性。 尤其是疏水性的C₆mim]BTB]和C₈mim]BTB]在与水长时间的混合中表现出较好的稳定性,基本解决了四氟硼酸盐离子液体亲水性强、$BF^{-}_{4}$易水解的缺点,有望用于乏燃料后处理并提高临界安全。

Syntheses and Properties of Novel Boron-Containing Ionic Liquids 1-Alkyl-3-methylimidazolium Benzyoltrifluoroborates

Three novel boron-containing ionic liquids(ILs), 1-alkyl-3-methylimidazolium benzyoltrifluoroborates(C_nmim]BTB], n=4, 6, 8), were successfully synthesized and some of their physico-chemical properties were characterized by nuclear magnetic resonance(NMR), differential scanning calorimeter(DSC), and thermogravimetric analysis(TGA). It was found that their decomposition temperatures were around 200 ℃. With the increase of the length of carbon chain on the imidazolium ring, the melting temperature, viscosity and hydrophobicity gradually increased. C₄mim]BTB] was hydrophilic, while C₆mim]BTB] and C₈mim]BTB] were hydrophobic. In particular, the later two were more stable when they mixed with water for a long time. In other words, the shortcoming of tetrafluoroborate ILs(i.e., strong hydrophilicity, especially the easy hydrolysis of $BF^{-}_{4}$) was overcome to great extent. Thus, it is hopeful for the two ILs to be used in the field of spent fuel reprocessing, which will effectively impove the critical safety.