以4-甲基吡啶和苄基溴为原料,采用直接合成法和阴离子交换法分别合成了溴化1 -苄基-4-甲基吡啶([BMPy]·Br)、1-苄基-4-甲基吡啶四氟硼酸盐([BMPy] BF4)和1-苄基-4-甲基吡啶六氟磷酸盐([BMPy]PF6)3种吡啶盐离子液体；分别对3种离子液体进行了元素分析、DSC分析、溶解性能和电导性能的测定.实验结果表明,3种离子液体的熔点较高且具有较高的热稳定性,热稳定性由高到低的顺序为:[ BMPy] PF6≈[BMPy] BF4＞[BMPy] Br.3种离子液体在极性不同的溶剂中具有不同的溶解性能；在10-5～10-4mol/L的浓度范围内其电导率均随温度的升高和浓度的增加而增大；溶剂不同,离子液体的解离-缔合状态不同,电导性能有很大差别；[ BMPy]Br在二甲基甲酰胺(DMF)溶液中的极限电导率最大,表明其在DMF溶液中离解成阴、阳离子的能力最强；3种离子液体的电导率随温度的变化均符合Arrhenius公式.%Three ionic liquids, namely 1 -benzy1-4-methylpyridinium bromide ([ BMPy ] Br), 1 -benzyl-4-methyl-pyridinium tetrafluoroborate ([BMPy] BF4 ) and 1-benzyl-4-methylpyridinium hexafluorophosphate ([ BMPy ] PF6), were prepared from 4-methylpyridine and benzyl bromide by direct synthesis method and anion-exchange method separately. Elementary analysis, DSC analysis, melting point determination, solubility determination and electric conductivity determination of the ionic liquids were carried. The results showed that both the melting points and the thermal stabilities of the ionic liquids were high with the thermal stability sequence of [ BMPy ] PF6 ≈ [ BMPy ] BF4 > [ BMPy ] Br. Their solubility in solvents varied with different solvent polarities. The electric conductivities of the ionic liquids increased with increases of the temperature and the solution concentration in the concentration range of 10 -5 - 10 -4 mol/L. The electric conductivities varied in different solvents which could be attributed to their different association-dissociation states. The highest limiting electric conductivity of [ BMPy ] Br indicated its strongest dissociating capability in dimethylformamide among the three ionic liquids. The change of the electric conductivities of the three ionic liquids with temperature accorded with Arrhenius equation.
展开▼
