Publication Details (including relevant citation information):
“Liquid-liquid phase transition in the ionic solutions of tetra-n-butylammonium chloride in o-xylene and ethylbenzene : Phase diagrams and corresponding state analysis”, H. Dittmar, A. Butka, V. R. Vale, W. Schröer, J. Mol. Liq. 145, 116 (2009)
The phase diagrams of the liquid-liquid phase transition of solutions of tetrabutyl ammonium chloride (N4444Cl) in o-xylene and ethyl benzene are reported and compared with the phase diagrams of solutions of other ionic liquids (IL) with halide anions (trihexyl tetradecyl phosphonium (P666 14+)chloride and bromide and 1-alkyl 3-methyl imidazolium (Rnmim+) chlorides) in non-polar solvents as alkanes, arenes and CCl4 and also with solutions of various 1-alkyl 3-methyl imidazolium tetrafluoroborates (Rnmim+ BF4) in alcohols and water. All phase diagrams have an upper critical solution point (UCSP) and are consistent with the presumption of Ising criticality. For the corresponding state analysis different choices for the concentration variable are applied. Using the variables of the model fluid of charged hard spheres in a dielectric continuum, termed restricted primitive model (RPM) a systematic overview of the critical properties of the mixtures is obtained. The critical temperatures of the solutions in the non-polar solvents are in the region of the RPM but somewhat smaller. They are very similar, do not correlate with the dielectric constant of the solvents but show a weak correlation with the boiling temperatures of the solvents, indicating the influence of the cohesion of the solvents on the phase separation driven by Coulomb interactions. The critical concentrations, width of the phase diagrams and the slope of the diameter are noticeable different for the solutions in protic and aprotic solvents but show no further systematic.