作者:Masahiro Yoshizawa-Fujita、Yuri Kousa、Koh Kidena、Akihiro Ohira、Yuko Takeoka、Masahiro Rikukawa
DOI:10.1039/c1cp21387c
日期:——
An ionic liquid having a hydroxyl group, choline bis(trifluoromethylsulfonyl)amide ([N111(2OH)][N(Tf)2]), was synthesized to investigate the effect of hydroxyl groups on the proton transport. 1,1,1-Trifluoro-N-(trifluoromethylsulfonyl)methanesulfoneamide (HN(Tf)2) as a proton source was mixed with the choline derivative at various molar ratios. Their thermal properties, viscosities, and ionic conductivities were investigated. [N111(2OH)][N(Tf)2] showed a melting point at 27 °C, and its thermal stability was higher than 400 °C. The viscosity of [N111(2OH)][N(Tf)2]/HN(Tf)2 mixtures increased as the acid molar fraction increased. The ionic conductivity of [N111(2OH)][N(Tf)2] was 2.1 × 10−3 S cm−1 at 25 °C; the ionic conductivity monotonously decreased as the acid molar fraction increased. There was a clear correlation between the ionic conductivity and the viscosity for the mixtures of the choline derivative and the acid. PFG-NMR measurements were carried out to investigate the diffusion behavior of protons. Although the acid and the hydroxyl group were indistinguishable by 1H NMR, the self-diffusion coefficient of the 1H of the hydroxyl group and the acid was larger than those of other 1H nuclei. This difference suggests that a fast intermolecular proton transfer exists between the hydroxyl group and the acid.
合成了一种含有羟基的离子液体胆碱双(三氟甲磺酰)酰胺([N111(2OH)][N(Tf)2]),以研究羟基对质子传递的影响。将质子源1,1,1-三氟-N-(三氟甲磺酰)甲磺酰胺(HN(Tf)2)与胆碱衍生物以不同摩尔比混合。研究了它们的热性能、黏度和离子电导率。[N111(2OH)][N(Tf)2]的熔点为27 °C,热稳定性高于400 °C。随着酸摩尔分数的增加,[N111(2OH)][N(Tf)2]/HN(Tf)2混合物的粘度增加。[N111(2OH)][N(Tf)2]的离子电导率为2.1 × 10−3 S cm−1,在25 °C时,随着酸摩尔分数的增加,离子电导率单调下降。胆碱衍生物与酸的混合物的离子电导率与粘度之间有着明显的关系。进行了PFG-NMR测量,以研究质子的扩散行为。尽管酸和羟基在1H NMR中无法区分,但羟基和酸的1H的自扩散系数大于其他1H核。这种差异表明,羟基和酸之间存在着快速分子间质子转移。