Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Liquid liquid phase diagrams of binary mixtures of the ionic liquid 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)amide (C4mimNTf2) with n-alkyl alcohols (butan-1-ol, pentan-1-ol, hexan-1-ol, heptan-1-ol, octan-1-ol, nonan-1-ol, decan-1-ol, and undecan-1-ol) are reported. Phase diagrams were determined at atmospheric pressure over the temperature range (280 to 420) K using the cloud-point method. The phase behavior indicates partial miscibility, with upper critical solution temperatures (UCSTs) between (297 and 408) K. With increasing chain length of the alcohol, the UCST shifts toward higher temperatures and slightly higher concentrations. Ising criticality is presumed for the numerical analysis of the phase diagrams. The temperature dependence of the diameter of the phase diagram, which determines the asymmetry of the phase diagram, was analyzed presuming the validity of the rectilinear diameter rule of Cailletet-Mathias or, alternatively, a nonlinear shape as requested by the theory of complete scaling. The analysis yielded the UCST, the corresponding critical composition, and the width and diameter parameters that characterize the shape of the phase diagram. When the phase diagrams are represented in terms of corresponding states variables, the results for solutions of C4mimNTf2 and C12mimNTf2 become very similar.