Strategies toward the design of energetic ionic liquids: nitro- and nitrile-substituted N,N′-dialkylimidazolium salts
作者:Alan R. Katritzky、Hongfang Yang、Dazhi Zhang、Kostyantyn Kirichenko、Marcin Smiglak、John D. Holbrey、W. Matthew Reichert、Robin D. Rogers
DOI:10.1039/b509260d
日期:——
Twelve novel 1,3-dialkylimidazolium salts containing strongly electron-withdrawing nitro- and cyano-functionalities directly appended to the cationic heterocyclic rings have been synthesized; the influences of the substituents on both formation and thermal properties of the resultant ionic liquids have been determined by DSC, TGA, and single crystal X-ray diffraction, showing that an electron-withdrawing nitro-substituent can be successfully appended and has a similar influence on the melting behaviour as that of corresponding methyl group substitution. Synthesis of di-, or trinitro-substituted 1,3-dialkylimidazolium cations was unsuccessful due to the resistance of dinitro-substituted imidazoles to undergo either N-alkylation or protonation, while 1-alkyl-4,5-dicyanoimidazoles were successfully alkylated to obtain 1,3-dialkyl-4,5-dicyanoimidazolium salts. Five crystal structures (one of each cation type) show that, in the solid state, the NO2-group has little significant effect, beyond the steric contribution, on the crystal packing.
合成了12种新型1,3-二烷基咪唑鎓盐,其阳离子杂环上直接附加了强吸电子硝基和氰基功能团;通过DSC、TGA和单晶X射线衍射确定了取代基对所得离子液体形成和热性质的影响,结果表明吸电子硝基取代基可以成功附加,并且对熔融行为的影响与相应的甲基取代相似。由于二硝基取代的咪唑对N-烷基化或质子化的抵抗力,未能成功合成二硝基或三硝基取代的1,3-二烷基咪唑鎓阳离子,而1-烷基-4,5-二氰基咪唑成功进行了烷基化,得到了1,3-二烷基-4,5-二氰基咪唑鎓盐。五种晶体结构(每种阳离子类型各一种)显示,在固态下,NO2基团对晶体堆积的影响不大,仅限于空间贡献。