Solubility of 1-Dodecyl-3-methylimidazolium Chloride in Alcohols (C2−C12)

Abstract

The solubility of 1-dodecyl-3-methylimidazolium chloride [C12mim][Cl] in alcohols {ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol, 1-dodecanol, 2-butanol, 2-methyl-2-propanol (tert-butyl alcohol)} has been measured by a dynamic method from 270 K to the melting point of the ionic liquid or to the boiling point of the solvent. The melting point, enthalpy of fusion, and enthalpies of four solid−solid phase transitions were determined by differential scanning calorimetry. The solubility of [C12mim][Cl] in primary alcohols decreases with an increase of the molecular weight of the alcohol from C6 to C12. The difference of solubilities in alcohols C2−C4 exists only in α1 and γ1 solid crystalline phases. The difference between the primary, the secondary, and the tertiary alcohols is not significant. The intermolecular solute−solvent interaction of the α stable crystalline solid form is higher for tertiary and secondary alcohol. The data were correlated by means of the Wilson, UNIQUAC ASM, and modified NRTL1 equations utilizing parameters derived from the solid−liquid equilibrium. The root mean square deviations of the solubility temperatures for all calculated data are higher than 7 K and depend on the particular equation used. The high enthalpy of solid−solid (α1→β1) phase transition is the main reason that the correlation of the solubility curves is not satisfied.