Gas‐phase acidity of bis[(perfluoroalkyl)sulfonyl]imides. Effects of the perfluoroalkyl group on the acidity

Abstract

The gas-phase acidity (GA) values were determined for a number of perfluoroalkyl-substituted sulfonylimides by measuring proton-transfer equilibria using a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The GA scale below 286.5 kcal mol À1 for (CF 3 SO 2 ) 2 NH was extended and partially revised. The GA value of (C 4 F 9 SO 2 ) 2 NH which is currently the strongest acid was revised from 284.1 to 278.6 kcal mol À1 . The effect of fluorine atoms on the acidity of perfluoroalkylsubstituted sulfonylimides was described with the following model N (γ) , and N (δ) are the numbers of fluorine atoms at α, β, γ, and δ position in R f SO 2 (R f = perfluoroalkyl group), respectively. This correlation indicates that the electron-withdrawing ability of the R f SO 2 group can be described in terms of the number of fluorine atoms in the perfluoroalkyl group corrected by taking into account their positions.

Clustering of H2SO4 with BX3 (X = H, F, Cl, Br, CN, OH) compounds creates strong acids and superacids

“…Comparison of the acidity of the complexes (HNO3)1,2H2SO4 and (BH3)1,2H2SO4 reveals that the effect of HNO3 and BH3 on the acidity enhancement of H2SO4 is similar. When H atoms are substituted by EWGs F, Cl, Br, and CN, the acidity enhancement is greater, and all the corresponding (BX3)1,2H2SO4 clusters are more acidic than bis-trifluoromethylsulfonylimide (TF2NH), one of the strongest known acids with ∆Gacid of 286.5 kcal.mol -1 [59]. Also, the simple cluster (B (CN)3)H2SO4-a with ∆Hacid and ∆Gacid values of 266.1 and 258.2 kcal.mol -1 , respectively, is as acidic as C5(CN)5H with ∆Hacid of 263.5 kcal.mol -1 [60], and HB(BF4)4 with ∆Gacid of 257.7 [61], and stronger than HAlF4 and HAl2F7 with ∆Gacid of 269.2 and 261.1 [62], respectively.…”

Multiple Ether‐Functionalized Phosphonium Ionic Liquids as Highly Fluid Electrolytes

“…This rank order is entirely consistent with the strength of the anion's corresponding acid, which decreases in the same order. [67][68][69] The presence of more weakly coordinating anions hence accelerates the diffusive movements of both cation and anion. This effect is also visible in the other physicochemical properties.…”

Control of proton concentration in water and organic solvents using electrochemically generated acid in very small footprint electrochemical cells.

“…These tables were created mainly by the spectrophotometric titration of the acids to determine its acidity relative to some indicator acid, whose conjugate anion was colored. [7][8][9][10][11][12][13][14][15] After Bordwell's work, other contributions completed the information with data relative to pKa values in other solvents obtained from different experiments including UV-vis measurements 16,17 , potentiometry [18][19][20] , quantum chemistry [21][22][23] , magnetic nuclear resonance 24 and other indirect measurements of the relative acidity and basicity of the compounds. For practical reasons, potentiometric acidity sensors like glass electrodes or ISFETs are the most used pH meters in water [25][26][27][28] .…”