酯基功能化离子液体的合成、表征及性质

采用两步法合成了含酯基官能团的功能化离子液体1-乙酸乙酯基-3-甲基咪唑四氟硼酸盐,用核磁共振、红外光谱、元素分析对其进行了结构表征,研究了离子液体的密度、酸值、黏温性、吸湿性、溶解性、玻璃化转变温度及热稳定性能。结果表明:制备的离子液体与预期结构一致,且纯度较高,证明了该功能化离子液体的制备和提纯方法的可靠性;与含有相同烷基的1-丁基-3-甲基咪唑四氟硼酸盐离子液体相比,功能化离子液体具有较高的密度、黏度、玻璃化转变温度和较低的酸值、吸水性及热稳定性,表明酯基官能团的引入,使烷基离子液体展现出不同的特性;另外,制备的2种离子液体均可以与极性大的溶剂混溶,而不溶于非极性或极性小的溶剂。

SYNTHESIS AND CHARACTERIZATION OF AN ESTER-GROUP FUNCTIONALIZED IONIC LIQUID AND ITS PROPERTIES

A new kind of ester-group functionalized ionic liquid,3-methyl-1-(ethoxycarbonylmethyl) imidazolium tetrafluoroborate,was synthesized through a typical two-step method and the product was characterized by ~1H NMR,FT-IR and elemental analysis.The density,acid value,viscosity-temperature characteristics,ability in absorbing water,solubility in some solvents,glass transition temperature and thermal stability of the synthesized ionic liquid was studied in detail.The results showed that the purity of the synthesized ionic liquid was high and its chemical structure was as expected, which proved the reliability of the preparation and purification methods utilized in this study.The property studies showed that,compared with a traditional ionic liquid,3-methy-l-butylimidazolium terafluoroborate,which has the same alkyl as the functionalized one,the functionalized ionic liquid possessed higher density,viscosity and glass transition temperature,but lower acid value,water absorbency and thermal stability.These results indicated the introduction of ester-group made the traditional alkyl imidazolium exhibit some special properties.In addition,it was found that the two ionic liquids were miscible with strong polar solvents,but insoluble in non-or weak polar solvents.