The application of liquids that are salts at room temperature to chemical synthesis has become a hugely exciting field of study. The greatest promise that these ionic liquids hold is that they might offer process advantages, even novel behaviors that cannot be achieved in molecular solvents. We report here that the S N 2 reaction of the trifluoromethanesulfonate and bis(trifluoromethanesulfonyl)imide salts of dimethyl-4-nitrophenylsulfonium ([p-NO 2 PhS(CH 3 ) 2 ] + [X] -; [X] -) [CF 3 SO 3 ] -, [N(CF 3 SO 2 ) 2 ] -) with chloride ion follow a fundamentally different pathway to when the same salts react in molecular solvents.

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We report a quantitative comparison of the rates of nucleophilic reactions in ionic liquids and molecular solvents taking place at a cationic center. Cationic sulfonium electrophiles were reacted with three amine nucleophiles (n-butylamine, di-n-butylamine, and tri-n-butylamine) in several molecular solvents (toluene, dichloromethane, tetrahydrofuran, acetonitrile, and methanol) and ionic liquids {1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, and 1-butyl-3-methylimidazolium trifluoromethanesulfonate}. The solvent effects on these reactions are examined using a linear solvation energy relationship based on the Kamlet−Taft solvent scales (α, β, and π*). These correlations reveal that hydrogen-bonding interactions provide the dominant effects in determining the rate of reaction. In particular, hydrogen bonds donated by the sulfonium electrophile to the solvent are the most important controlling factor on the rate of nucleophilic reaction.

The dynamical characteristics and the thermal analysis of water absorbed in filler-free Nafion and in silica or zirconia phosphate Nafion composites, between 20 and -50 degrees C, were investigated by NMR and DSC techniques. Self-diffusion coefficients and longitudinal NMR relaxation times (T(1)) put in evidence a fraction of water freezing at subzero temperatures. The complementary water fraction remains in the liquid state at least down to -50 degrees C. The freezing point (T(f)) depends on the initial water uptake of the electrolyte membrane and, for similar uptake values, water mobility is favorite in composites systems respect to the filler-free Nafion. By DSC thermograms the hydration water molecules number per sulfonic group in the filler-free Nafion was estimated, obtaining 8 molecules/SO(3)(-) group. In the Nafion/Zr(HPO(4))(2) composite, instead, the number of hydration water is about 20 molecules/ionic group, because of the acid nature of the zirconia particles. Below T(f), the presence of this nonfreezable water fraction allows proton transport, and therefore ensures ionic conductivity also at subzero temperatures.