Measurements of Infinite Dilution Activity Coefficients of Alkanols in the Ionic Liquid Tributylmethylammonium Methyl Sulfate Using HS-SPME/GC/FID

The activity coefficients at infinite dilution (γ i ∞) and gas–liquid partition coefficients (K LG) for six solutes (methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, and 2-methyl-2-propanol) in the liquid ionic (IL) tributylmethylammonium methyl sulfate ([TBMA]­[CH3SO4]) were determined by HS-SPME (headspace-solid phase micro extraction) at four temperatures from 338.15 to 368.15 K. The values of partial molar excess enthalpies at infinite dilution (ΔH i E,∞), Gibbs free energies (ΔG i E,∞), and entropies (ΔS i E,∞) were also calculated from the γ i ∞ values. The results are unprecedented in the literature and suggest that SPME can be used to determine activity coefficients at infinite dilution of solutes in liquid ionic solvents.