Solubility of 1-alkyl-3-ethylimidazolium-based ionic liquids in water and 1-octanol

The liquid-liquid phase equilibria (LLE) of the following imidazolium ionic liquids (ILs), {1-ethyl-3-ethylimidazohum,orl-butyl-3-ethyhmidazolitim,or 1-hexyl-3-ethylimidazoliumbis{(tiifluoromethyl)sylfony}limide [EEIM] [Tf2N], or [BEIM] [Tf2N], or [HEIM][Tf2N], + water or + 1-octano.1 1, and {1-butyl-3-ethylimidazolium hexafluorophosphate [BEIM][PF6] + water or + 1-octanol), have been measured. The effect of anion type ([Tf2N]- compared to [PF6]-) and the effect of structural components of an ionic liquid including alkyl chain length on the cation and the ethyl substituent instead of methyl at the cation on the physicalchemical properties of the IL and on the phase behavior were studied. An upper critical solution temperature (UCST) was observed in every system. An. increase in the alkyl chain length increases the mutual solubility with 1-octanol and partly with water. Ionic liquids with the ethyl substituent on the cation [HEIM][Tf2N] show higher solubility in I-octanol in comparison with the methyl substituent. After the synthesis, the characterization and purity of the compounds were obtained by nuclear magnetic resonance (NMR), elemental analysis, water content (Fischer method), and differential scanning microcalorimetry (DSC). From DSC, the melting point, enthalpy of fusion, and the temperatures of glass transition of all the investigated ionic liquids were determined. The experimental LLE data were correlated by means of the NRTL equation.