双(咪唑)硼烷类自燃离子液体的合成、表征及性质

Synthesis,Characterization and Properties of Bis( imidazole) dihydroboronium Hypergolic Ionic Liquids

以三甲胺硼烷为反应底物,通过两步法,合成了以不同烃基侧链咪唑硼烷为阳离子,二氰胺根和硝基氰胺根为阴离子的系列离子液体。采用1H和13C核磁、红外及高分辨质谱等表征方法,确认了所得离子液体的结构和组成,并测定计算了其性质。结果表明：所得离子液体的分解温度均高于150℃,密度为1.04~1.27 g·cm-3,比冲为173.8~202.1 s。随着咪唑阳离子烃基侧链的增长,相应离子液体的密度减小,生成焓增大。二氰胺类离子液体同相应的硝基氰胺类离子液体相比,具有更短的点火延迟时间。其中,双烯丙基咪唑硼烷二氰胺离子液体具有良好的综合性能（粘度69 m Pa·s,分解温度180℃,生成焓753.6 k J·mol-1,点火延迟时间18 ms,比冲176.7 s）,有望作为一种绿色燃料应用于双组元液体自燃推进剂。

A series of bis（ imidazole） dihydroboronium ionic liquids with dicyanamide and nitrocyanamide anions were prepared by two-step synthetic method using trimethylamine borane as reaction substrate. Their structures and compositions were confirmed by1 H NMR and13 C NMR,infrared and high resolution mass spectrometry,and properties were measured and calculated. The results show that resulting ionic liquids have good performances： decomposition temperature up to 150 ℃,densities from 1. 04 to 1. 27 g·cm-3and specific impulses from173. 8 to 202. 1 s. With the increase of hydrocarbon side chains in imidazolium cations,densities of ionic liquids decrease while heats of formation increase. The dicyanamide ionic liquids show shorter ignition delay times than the corresponding nitrocyanamide ionic liquids. Among the ionic liquids,bis（ 1-allyl-1H-imidazole-3-yl） dihydroboronium dicyanamide possesses good comprehensive properties such as viscosity 69 mP a·s,decomposition temperature 180 ℃,heat of formation 753. 6 kJ ·mol-1,ignition delay time 18 ms and specific impulse 176. 7 s,therefore exhibiting application potential as the green fuel of hypergolic bipropellants.