Berthon L, Nikitenko S I, Bisel I, Berthon C, Faucon M, Saucerotte B, Zorz N, Moisy Ph
CEA Marcoule, DRCP/SCPS, BP 17171, 30207 Bagnols sur Cèze Cedex, France.
Dalton Trans. 2006 Jun 7(21):2526-34. doi: 10.1039/b601111j. Epub 2006 Apr 25.
Stability of neat hydrophobic Room-Temperature Ionic Liquids (RTIL) [BuMeIm]X, where [BuMeIm]+ is 1-butyl-3-methylimidazolium and X- is PF6-, and (CF3SO2)2N-, was studied under gamma radiolysis (137Cs) in an argon atmosphere and in air. It was found that the density, surface tension, and refraction index of RTILs are unchanged even by an absorbed dose of approximately 600 kGy. Studied RTILs exhibit considerable darkening when subjected to gamma irradiation. The light absorbance of ionic liquids increases linearly with the irradiation dose. Water has no influence on radiolytic darkening. A comparative study of [BuMeIm]X and [Bu4N][Tf2N] leads to the conclusion that the formation of colored products is related to gamma radiolysis of the [BuMeIm]+ cation. The radiolytic darkening kinetics of RTILs is influenced by the anions as follows: Cl- < (CF3SO2)2N- < PF6-. Electrospray ionization mass spectrometry and NMR analysis reveal the presence of nonvolatile radiolysis products at concentrations below 1 mol% for an absorbed dose exceeding 1200 kGy. Initial step of BuMeIm+ cation radiolysis is the loss of the Bu* group, the H* atom from the 2 position on the imidazolium ring, and the H* atom from the butyl chain. Radiolysis of ionic liquid anions yields F* and CF3* from PF6- and [Tf2N]-, respectively. Recombinations of these primary products of radiolysis lead to various polymeric and acidic species.
研究了纯疏水室温离子液体（RTIL）[BuMeIm]X在γ辐射（137Cs）下于氩气气氛和空气中的稳定性，其中[BuMeIm]+为1-丁基-3-甲基咪唑鎓，X-为PF6-和（CF3SO2）2N-。结果发现，即使吸收剂量约为600 kGy，RTILs的密度、表面张力和折射率也未发生变化。研究发现，RTILs在受到γ辐射时会出现明显的变黑现象。离子液体的吸光度随辐照剂量呈线性增加。水对辐射变黑没有影响。对[BuMeIm]X和[Bu4N][Tf2N]的比较研究得出结论，有色产物的形成与[BuMeIm]+阳离子的γ辐射分解有关。RTILs的辐射变黑动力学受阴离子的影响如下：Cl- < （CF3SO2）2N- < PF6-。电喷雾电离质谱和核磁共振分析表明，对于超过1200 kGy的吸收剂量，浓度低于1 mol%时存在非挥发性辐射分解产物。BuMeIm+阳离子辐射分解的初始步骤是失去Bu基团、咪唑环2位上的H原子以及丁基链上的H原子。离子液体阴离子的辐射分解分别从PF6-和[Tf2N]-产生F和CF3*。这些辐射分解初级产物的重组导致形成各种聚合物和酸性物质。
