ABSTRACT
In this paper, we report the most comprehensive equilibrium superacidity scale that is available to date. Contrary to most of the past works, this scale is set up in a medium of constant composition and the obtained acidity values characterize the acidities of molecules rather than acidities of media. The current scale is thus complementary to the well-known H(0) scale in the information that it provides. The solvent used is 1,2-dichloroethane (DCE). DCE has very weak basic properties (but sufficiently high polarity) and is an appropriate solvent for measuring acidities of very strong acids of diverse chemical nature. DCE acidities of well-known superacids (CF(3)SO(2)OH, (CF(3)SO(2))(2)NH, cyanocarbon acids, etc.) as well as common mineral acids (H(2)SO(4), HI, HBr, etc.) are reported. Acidities of altogether 62 acids have been determined from 176 interlinked relative acidity measurements. The scale spans 15 orders of magnitude (from picric acid to 1,1,2,3,3-pentacyanopropene) and is expected to be a useful tool in design, use, and further acidity measurements of superacidic molecules.
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.
ABSTRACT
N-methyl and N-ethyl derivatives of N-(trifluoromethylsulfonyl)-[N'-(trifluoromethylsufonyl)-trifluoromethylsulfoximidoyl] imides 2a,b were prepared by alkylation of bis(trifluoromethylsulfonylimino)trifluoromethanesulfonic acid 1 or its silver salt 1a. It turns out that these imides are strong alkylating agents in spite of the fact that Me (Et) groups are attached to nitrogen atom. The alkylating activity of n-PrI, i-PrI, n-BuI, and n-AmI in the presence of silver salt of bis(trifluoromethylsulfonylimino)trifluoromethanesulfonic acid 1a was investigated.
ABSTRACT
A synthesis of new unsymmetric trifluoromethylsulfonylimino(nonafluoro-n-butyl-sulfonylimino)trifluoromethanesulfonic acid (1b) is reported. During the silylation reactions studies of bis(perfluoroalkylsulfonylimino)trifluoromethanesulfonic acids (1a,b) it was shown that reaction proceeds exclusively on the central oxygen atom to give trimethylsilyl esters. The obtained esters along with several trimethylsilylesters of sulfonic acids have been studied by 29Si-NMR spectroscopy and an attempt to estimate the strength of bis(perfluoroalkylsulfonylimino)trifluoromethanesulfonic acids by the 29Si-NMR chemical shifts of their trimethylsilylesters was made, resulting in the conclusion that these compounds may be cited as the strongest organic Brønsted acids.
ABSTRACT
Salts of N-trifluoromethylsulfonyl derivatives of trifluoromethyl- and phenylsulfonimidoyl imides have been synthesized by two different routes. Both methods are one-pot reactions, that run in mild conditions with good yields. Two novel organic super acids: bis[N-(trifluoromethylsulfonyl)trifluoromethanesulfonimidoyl]imide and N,N'-bis(trifluoromethyl-sulfonyl)diimino trifluoromethanesulfonic acid were prepared and the structure of their potassium salts was obtained by single-crystal X-ray diffraction.
