Ohtani Hajime, Ishimura Shinji, Kumai Miyuki
Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Japan.
Anal Sci. 2008 Oct;24(10):1335-40. doi: 10.2116/analsci.24.1335.
Thermal decomposition behaviors of a series of imidazolium-type ionic liquid samples were studied by pyrolysis-gas chromatography at 550 degrees C using various detectors. As for the imidazolium halides, haloalkanes and 1-alkylimidazoles corresponding to the alkyl substituents were mainly formed through the nucleophilic attacks of halide ions to the alkyl groups followed by C-N bond cleavage, along with a minor amount of alkenes. Meanwhile, in the case of the ionic liquids with BF(4), PF(6) and CF(3)SO(3) anions, corresponding alkenes were predominantly produced along with 1-alkylimidazoles rather than haloalkanes. No boron-containing products were found even from the samples with BF(4) anion, whereas minor but clear peaks of phosphorous-containing products were observed in the pyrograms of the samples with PF(6) anions. As for the samples with longer alkyl group, the pyrolyzates reflecting the C-C bond scissions in the alkyl groups were also formed to some extent. Meanwhile, imidazole rings did not decompose under the experimental conditions at around 550 degrees C.
采用热解气相色谱法，在550℃下使用各种检测器研究了一系列咪唑型离子液体样品的热分解行为。对于卤化咪唑鎓盐，卤离子对烷基进行亲核攻击，随后C-N键断裂，主要生成与烷基取代基对应的卤代烷和1-烷基咪唑，同时伴有少量烯烃。同时，对于含有BF(4)、PF(6)和CF(3)SO(3)阴离子的离子液体，主要生成相应的烯烃以及1-烷基咪唑，而非卤代烷。即使是含有BF(4)阴离子的样品，也未发现含硼产物，而在含有PF(6)阴离子的样品的热解图谱中观察到了少量但明显的含磷产物峰。对于具有较长烷基的样品，在一定程度上也形成了反映烷基中C-C键断裂的热解产物。同时，在约550℃的实验条件下，咪唑环未发生分解。
