Leito Ivo, Raamat Elin, Kütt Agnes, Saame Jaan, Kipper Karin, Koppel Ilmar A, Koppel Ivar, Zhang Min, Mishima Masaaki, Yagupolskii Lev M, Garlyauskayte Romute Yu, Filatov Andrey A
Institute of Chemistry, University of Tartu, 2 Jakobi Street, 51014 Tartu, Estonia.
J Phys Chem A. 2009 Jul 23;113(29):8421-4. doi: 10.1021/jp903780k.
The gas-phase acidity (GA) scale from (CF(3)CO)(2)NH to (C(2)F(5)SO(2))(2)NH--about a 24 kcal mol(-1) range of gas-phase acidities--was reexamined using the Fourier transform ion cyclotron resonance equilibrium measurement approach. Some additions and modifications to the standard methodology of GA measurements were introduced (estimation of partial pressures from mass spectra of the compounds, instead of the pressure gauge readings and use of long reaction times) to achieve higher reliability. Gas-phase acidities of 18 compounds were determined for the first time. The results reveal a contraction of the previously published values in this part of the scale. In particular, the GA values of (CF(3)SO(2))(2)NH and (C(2)F(5)SO(2))(2)NH (important components of lithium ion battery electrolytes and ionic liquids) were revised toward stronger acidities from 291.8 kcal mol(-1) to 286.5 kcal mol(-1) and from 289.4 kcal mol(-1) to 283.7 kcal mol(-1) (i.e., by 5.3 and 5.7 kcal mol(-1)), respectively. Experimental and computational evidence is presented in support of the current results.
使用傅里叶变换离子回旋共振平衡测量方法，重新审视了从（CF(3)CO）(2)NH到（C(2)F(5)SO(2)）(2)NH的气相酸度（GA）标度——气相酸度范围约为24千卡摩尔(-1)。引入了一些对GA测量标准方法的补充和修改（从化合物的质谱估计分压，而不是压力计读数，并使用较长的反应时间）以实现更高的可靠性。首次测定了18种化合物的气相酸度。结果显示，该标度这一部分中先前公布的值有所收缩。特别是，（CF(3)SO(2)）(2)NH和（C(2)F(5)SO(2)）(2)NH（锂离子电池电解质和离子液体的重要成分）的GA值从291.8千卡摩尔(-1)和289.4千卡摩尔(-1)分别修正为更强的酸度，即286.5千卡摩尔(-1)和283.7千卡摩尔(-1)（即分别降低了5.3和5.7千卡摩尔(-1)）。给出了实验和计算证据以支持当前结果。
