Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-butyl-3-methylimidazolium methyl sulfate

•Measurements of activity coefficients at infinite dilution using GLC.•22 Organic solutes in the ionic liquid [BMIM][CH3SO4].•The excess thermodynamic functions, the (gas + liquid) partition coefficients were calculated.•The solubility parameter of the IL [BMIM][CH3SO4] was determined by the regular solution theory.•The linear free energy relationship (LFER) analysis of the results was performed.

Activity coefficients at infinite dilution (γi∞) and (gas + liquid) partition coefficients (KL) for organic solutes: alkanes, alkenes, alkyl benzenes, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, and chloromethanes in the ionic liquid (IL) 1-butyl-3-methylimidazolium methyl sulfate ([BMIM][CH3SO4]) have been measured by the (gas + liquid) chromatographic method in the temperature range of (313.15 to 363.15) K. The values of the partial molar excess enthalpies at infinite dilution (H‾iE,∞) were derived from the temperature dependence of the γi∞ values. The entropies (TrefS‾iE,∞) and Gibbs free energies (G‾iE,∞) of organic solutes in [BMIM][CH3SO4] at a reference temperature Tref = 298.15 K were also calculated from the γi∞ values. The solubility parameters of the IL [BMIM][CH3SO4] were also determined by the regular solution theory (RST). The linear free energy relationship (LFER) analysis of the results was performed to disclose molecular interactions operating between the IL and the individual solutes.