Phase Equilibria of (1-Hexyl-3-methylimidazolium Thiocyanate + Water, Alcohol, or Hydrocarbon) Binary Systems

Abstract

Imidazolium ionic liquid has been prepared from 1-methylimidazolium as a substrate. The work includes specific basic characterization of a synthesized compound by NMR spectra, water content, and a glass transition temperature determined by the differential scanning calorimetry (DSC). The mutual solubilities of 1-hexyl-3-methylimidazolium thiocyanate, [HMIM][SCN], with water, alcohols, n-alkanes (n-hexane, n-heptane, n-octane, n-nonane, or n-decane), aromatic hydrocarbons (benzene, toluene, or ethylbenzene), and cyclic hydrocarbons (cyclohexane or cycloheptane) have been measured at ambient pressure by a dynamic method in a range of temperatures from (200 to 420) K. The simple eutectic system was observed for water with complete miscibility in the liquid phase. Complete miscibility has been observed in the systems of [HMIM][SCN] with alcohols ranging from methanol to 1-decanol at a temperature of T = 298.15 K. The upper critical solution temperatures (UCSTs) were observed for the systems with n-alkanes and the lower critical solution temperatures (LCSTs) for the systems with aromatic hydrocarbons. The solubility decreases with an increase of the molecular weight of the solvent. The liquid−liquid phase equilibria (LLE) have been correlated using the nonrandom two-liquid (NRTL) equation. The average root-mean square deviation of the equilibrium mole fraction for all of the LLE data was 0.0021.