温控双咪唑离子液体的合成与晶体结构表征

Synthesis and crystal structure characterization of temperature controlled bimidazole ionic liquid

以1-乙基咪唑和1,3-二溴丙烷(或1,5-二溴戊烷)为原料制得溴盐中间体,然后与六氟磷酸钾在水溶液中进行阴离子交换,以制备双咪唑型温控型离子液体。通过对上述两种双-(3-乙基咪唑)烷烃六氟磷酸盐进行X-射线单晶结构分析,发现两者结构相近,但晶体形貌差异较大,其中双-(3-乙基咪唑)丙烷六氟磷酸盐属于四方晶系,而另一个属于正交晶系;两者在晶胞堆积结构上呈现高度对称。另外,将双-(3-乙基咪唑)烷烃六氟磷酸盐应用到苯胺的缩合反应中,随着反应温度的升高,晶体物质渐渐溶解,达到85℃时反应体系为淡红色均相,反应结束后冷却到60℃以下,晶体物质逐渐析出,取得了较好的温控分离效果。

Bromide intermediates were prepared from 1-ethylimidazole and 1,3-dibromopropane(or 1,5-dibromopentane),and then anion exchanged with potassium hexafluorophosphate in aqueous solution was proceeded to prepare biimidazole-type temperature-controlled ionic liquids.X-ray single crystal structure analysis of the above two bis-(3-ethylimidazole)alkanes hexafluorophosphate showed that their crystal morphologies were quite different,although their structures were similar.Among them,bis-(3-ethylimidazole)propane hexafluorophosphate belongs to tetragonal system,while the other belongs to orthorhombic system,and both of them are highly symmetrical in cell stacking structure.In addition,in the application of bis-(3-ethylimidazole)alkane hexafluorophosphate to the condensation reaction,With the increase of reaction temperature,the crystalline substances gradually dissolve,and the reaction system is light red homogeneous when the reaction temperature reached 85℃.After the reaction completed,the crystalline substances gradually precipitate if it cooled to below 60℃,so that it achieved a good temperature-controlled separation effect.