Synthesis, limitations, and thermal properties of energetically-substituted, protonated imidazolium picrate and nitrate salts and further comparison with their methylated analogs
作者:Marcin Smiglak、C. Corey Hines、W. Matthew Reichert、Adam S. Vincek、Alan R. Katritzky、Joseph S. Thrasher、Luyi Sun、Parker D. McCrary、Preston A. Beasley、Steven P. Kelley、Robin D. Rogers
DOI:10.1039/c1nj20677j
日期:——
and nitro, dinitro, and dicyano-substituted derivatives. The melting points of most of the prepared salts were lower than expected and of the 30 compounds prepared, more than half were found to melt below 100 °C. Limitations in the approach were found as a result of the use of energetic electron withdrawing substituents, such as nitro or cyano, which results in a reduction in nucleophilicity of the
通过杂环胺直接用硝酸或硝酸质子化形成简单的高能离子液体的可能性苦味酸用1-烷基咪唑,1-烷基-2-甲基咪唑以及硝基,二硝基和二氰基取代的衍生物进行了探索。大多数制得的盐的熔点均低于预期,制得的30种化合物中,有一半以上在低于100°C的温度下熔化。由于使用了高能的吸电子取代基(例如硝基或氰基),发现了该方法的局限性,这导致杂环的亲核性降低,并且无法与所研究的酸形成盐。在几种新盐中观察到了有趣的热行为,包括过冷和加热时的结晶。简单的质子化硝酸咪唑鎓盐和苦味酸盐与它们的甲基化类似物的比较表明,质子化的离子液体的熔点与甲基化的类似物没有实质性的区别。然而,质子化的咪唑鎓盐的热稳定性远低于其烷基化的衍生物。具有烷基化阳离子的硝酸盐趋于比相应的苦味酸盐更热稳定,但是具有质子化阳离子的苦味酸盐趋于比硝酸盐稳定约70–80°C。此外,加速量热法(ARC)显示,烷基化的盐在放热时(在某些情况下是吸热的)分