Influence of the structure of the cation of ionic liquids on the vapor pressure and osmotic coefficients in their binary mixtures with 1-propanol

The osmotic and activity coefficients and vapor pressures of binary mixtures containing the alcohol 1-propanol and the ionic liquids 1-ethyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide, C(2)MpyNTf(2), 1-propyl-3methylpyridinium bis(trifluoromethylsulfonyl)imide, C(3)MpyNTf(2), 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl) imide, C(4)MpyNTf(2) and 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide, C(4)MpyrNTf(2) were determined at T = 323.15 K using the vapor pressure osmometry technique. The experimental osmotic coefficients were correlated using the Extended Pitzer model of Archer obtaining standard deviations lower than 0.060. The mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated from the parameters of the Extended Pitzer model of Archer. From the experimental determination, the influence of the alky1-side chain of the cation and of the cation itself on the osmotic and activity coefficients and on the vapor pressures can be analyzed. (C) 2012 Published by Elsevier Ltd.