Isomer effect of propanol on liquid-liquid equilibrium in hydrophobic room-temperature ionic liquids

The cloud-point temperature determined the liquid-liquid phase equilibrium (LLE) of binary systems comprising hydrophobic room-temperature ionic liquids (RTILs) and propanol. The RTILs were 1-alkyl3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [C(x)mim][TFSI] (2 <= x <= 10). Upper critical solution temperatures in LLE are inversely proportional to the C(x)mim(+) cation alkyl chain length, x. The propanol isomer effect indicates the critical alkyl chain length (X-critical = 6-7). UNIQUAC model determined the interaction parameters (with crossing points at x= 6). In pure RTILs, conformation stability of TFSI- by Raman spectroscopy changed between x= 6 and 7, corresponding to the simulation-determined 90 degrees-torsion angle at x= 6. (C) 2014 Elsevier B.V. All rights reserved.