Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The activity coefficient at infinite dilution, c1 13, was determined by gas liquid chromatography at temperatures from T = 308.15 to T = 348.15 K for 54 assorted solutes among them, alkanes (linear, branched, or cyclic), alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, tetrahydrofuran, 1,4-dioxane, ethers, acetone, ketones, acetonitrile, pyridine, and 1-nitropropane in the novel bicyclic guanidine superbase-derived protic ionic liquid 1,3,4,6,7,8-hexahydro-1-methyl-2H-pyrimido[1,2-a]pyrimidine bis(pentafluoroethyl)sulfonylimide, [MTBDH][BETI]. The partial molar excess Gibbs free energy DGE;1 1 , the partial molar excess enthalpy DHE;1 1 , and entropy at reference temperature TrefDSE;1 1 at infinite dilution were calculated from the experimental c1 13 values obtained over this temperature range. The gas liquid partition coefficient, KL, was calculated for each solute and discussed in light of the Abraham solvation parameter model. The density of the IL as a function of temperature was also measured. The selectivities for heptane/benzene, heptane/thiophene, heptane/pyridine, and heptane/nitropropane separation problems were calculated from c1 13 and compared to literature values for select ILs, as these separation problems are central to the petroleum industry.