title: Revision of the gas-phase acidity scale below 300 kcal mol(-1).
abstract: 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.
authors: Institute of Chemistry, University of Tartu, 2 Jakobi Street, 51014 Tartu, Estonia. ivo.leito@ut.ee
authors: Ivo
authors: I
authors: Leito
authors: Elin
authors: E
authors: Raamat
authors: Agnes
authors: A
authors: Kütt
authors: Jaan
authors: J
authors: Saame
authors: Karin
authors: K
authors: Kipper
authors: Ilmar A
authors: IA
authors: Koppel
authors: Ivar
authors: I
authors: Koppel
authors: Min
authors: M
authors: Zhang
authors: Masaaki
authors: M
authors: Mishima
authors: Lev M
authors: LM
authors: Yagupolskii
authors: Romute Yu
authors: RY
authors: Garlyauskayte
authors: Andrey A
authors: AA
authors: Filatov