双阳离子型离子液体的合成与性能

Study on synthesis and properties of dicationic ionic liquids

以N-甲基咪唑、吡啶和二溴代烷为原料合成了一系列α,ω-亚烷基-双(N-甲基咪唑鎓)型和α,ω-亚烷基-双(吡啶鎓)型离子液体,并对其结构、熔点、溶解性、吸湿性和热性能分别进行了表征。结果表明,随着连接两个阳离子联接基的碳氢链长度的增加,离子液体的熔点先降低后升高,联接基的碳氢链长度为5个碳原子时最低;α,ω-亚烷基-双(N-甲基咪唑鎓)型离子液体的熔点低于α,ω-亚烷基-双(吡啶鎓)型离子液体;双阳离子溴盐型离子液体溶于水,双阳离子六氟磷酸盐型离子液体溶于丙酮和乙腈等;双阳离子溴盐型离子液体有一定的吸湿性,所合成的双阳离子型离子液体具有较高的热稳定性。

A series of N-methylimidazolium-based dicationic ionic liquids and pyridinium-based dicationic ionic liquids were Synthesized using N-methylimidazole, pyridine and dibromoalkane as starting materials. FT-IR spectrometry and ^1HNMR spectrometry were applied to identify the molecular structure of the ionic liquids., Key physical properties such as melting point, miscibility in common solvents, hydroseopieity and thermal properties were used to characterize the ionic liquids. The results showed that, by increasing the length of the connecting group between the dicationic ionic liquids, the melting point decreased first then increased, and the melting point of the ionic liquids with a spacing of 5-carbon chain of the hydrocarbon species was the lowest, the mehing point of the N-methylimidazolium-based dicationic ionic liquids was lower than that of the pyridinium-based dieationic ionic liquids. Dicationic ionic liquids based on bromide anion is soluble in water, and dieationic ionic liquids based on hexafluorophosphate anion is soluble in acetone and acetonitrile. Dicationic ionic liquids based on bromide anion has a definite hydroscopicity. The dieationic ionic liquids possess higher thermal stability.