碱性离子液体甲氧化1-乙基-3-甲基咪唑盐的合成与表征

Synthesis and characterization of basic ionic liquid methyl oxide 1-ethyl-3-methyl imidazole salt

以N-甲基咪唑、溴乙烷和甲醇钠为原料,通过采用两步法,先合成中间体溴化1-乙基-3-甲基咪唑[Emim]Br,最终合成碱性离子液体甲氧化1-乙基-3-甲基咪唑盐[Emim]OCH_(3)。通过红外光谱进行结构表征,TG进行热性能测定、pH值法进行碱性表征,同时研究了各因素对其电导率的影响,测定了临界胶束浓度及其溶解性。结果表明,[Emim]OCH_(3)的热稳定性良好,碱性较强且碱性在25~55℃范围内受温度影响较小;[Emim]Br和[Emim]OCH_(3)与不同溶剂的二元混合体系在20℃、6~20 g/L的浓度范围内,电导率随浓度的增大而增大,相同浓度下在25~60℃范围内,电导率随温度的升高而增大,同时符合阿伦尼乌斯公式;[Emim]Br和[Emim]OCH_(3)的临界胶束浓度分别为12.09,9.73 g/L;常温下,[Emim]OCH_(3)易溶解在极性较大的溶剂中。

N-methylimidazole,bromoethane and sodium methoxide were used as raw materials.The intermediate 1-ethyl-3-methylimidazole bromide[Emim]Br was synthesized firstly through a two-step method,and then the basic ionic liquid methyl oxide 1-ethyl-3-methylimidazole salt[Emim]OCH_(3) was synthesized finally.Infrared spectroscopy was used to characterize the structure,TG was used to determine the thermal properties,and pH was used to characterize the alkalinity.At the same time,the influence of various factors on the electrical conductivity was studied,and the critical micelle concentration and solubility were determined.The results show that[Emim]OCH_(3) has good thermal stability properties and strong alkalinity,which is less affected by temperature in the range of 25~55℃.The conductivity of[Emim]Br,[Emim]OCH_(3)and binary mixed system with different solvents increase with that of the concentration in 20℃and the range of 6~20 g/L.The conductivity of[Emim]Br,[Emim]OCH_(3)and binary mixed system increase with the temperature goes up in the range of 25~60℃at the same concentration,which also conform to Arrhenius formula.The critical micelle concentrations of[Emim]Br and[Emim]OCH_(3)are 12.09 g/L and 9.73 g/L,respectively.At room temperature,[Emim]OCH_(3)is readily soluble in solvents with greater polarity.