Water as an In-situ NMR Indicator for Impurity Acids in Ionic Liquids
Water as an In-situ NMR Indicator for Impurity Acids in Ionic Liquids
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水作为离子液体中杂质酸的原位 NMR 指示剂
DOI：
10.1021/ac801767u
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
and M. Nakahara
中科院分区：
文献类型：
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作者：
Y. Yasaka;C. Wakai;N. Matubayasi;and M. Nakahara
建立了一种灵敏的原位核磁共振检测离子液体(ILS)酸污染的方法。用离子液体中加入水的化学位移和光谱宽度作为衡量杂质酸水平的指标。由于核磁共振的高分辨能力，检测下限低于10−3mol kg−1的水平。该方法适用于一些常用的离子液体，如咪唑类和氨基离子液体，但酸性阳离子或阴离子除外。利用该方法对典型亲水性IL-1-丁基-3-甲基咪唑甲烷磺酸盐从丙酮重结晶过程中的纯化效率进行了监测。结果表明，单重结晶或双重结晶几乎可以完全脱除杂质酸。
A sensitive in situ NMR spectroscopic method for detecting acids contaminating ionic liquids (ILs) has been developed. The chemical shift and the spectral width of water added to ILs were used as indicators to measure the impurity acid level. Owing to the high resolution power of NMR, the detection limit is below the level of 10−3mol kg−1. A new method is applicable to a number of commonly used ILs such as the imidazolium- and ammonium-based ILs except for those composed of acidic cations or anions. The method was utilized to monitor the purification efficiency in the recrystallization of a typical hydrophilic IL, 1-butyl-3-methylimidazolium methanesulfonate from acetone. It was demonstrated that impurity acids can be almost perfectly removed by single or double recrystallization.