Journal of Chemical and Engineering Data, Vol.56, No.9, 3589-3597, 2011
Thermophysical Properties of 1-Ethyl-3-methylimidazolium 1,1,2,2-Tetrafluoroethanesulfonate and 1-Ethyl-3-methylimidazolium Ethylsulfate Ionic Liquids as a Function of Temperature
Refractive indices, densities, and viscosities of 1-ethyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate ([emim][CHF(2)CF(2)SO(3)]), and 1-ethyl-3-methylimidazolium ethylsulfate ([emim][CH(3)CH(2)SO(4)]) ionic liquids (ILs) were measured over the temperature range from (293.15 to 353.15) K at atmospheric pressure. The surface tension of the two ILs was also determined at temperatures between (303.15 and 333.15) K. The reliability of the results gathered in this work was assessed by comparing experimental values of [emim][CH(3)CH(2)SO(4)] with data available in the literature. Molar volumes, molar refractions, molar free volumes, volume expansivities, surface entropies, surface enthalpies, and critical temperatures of the ILs were calculated from the experimental data. The influence of temperature on the viscosity was described by the Arrhenius and Vogel-Fulcher-Tammann (VET) models. The variation of surface tension with temperature was modeled using the Eotvos equation. An evaluation of the influence of several sulfur and fluorinated anions on the physical properties of 1-ethyl-3-methylimidazolium based-ILs was performed by comparison between experimental measurements of [emim][CHF(2)CF(2)SO(3)] and [emim][CH(3)CH(2)SO(4)] and published data of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][CF(3)SO(3)]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][(CF(2)SO(3))(2)N]).