Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The (liquid + liquid) equilibrium (LLE) of 20 binary systems containing 1-hexyloxymethyl-3-methyl-imidazolium tetra- fluoroborate ([C6H13OCH2mim][BF4]) with aliphatic hydrocarbons (n-pentane, or n-hexane, or n-heptane, or n-octane), aromatic hydrocarbons (benzene, or toluene, or ethylbenzene, or o-xylene, or m-xylene, or p-xylene), cyclohexane and 1-hexyloxymethyl-3- methyl-imidazolium bis(trifluoromethylsulfonyl)-imide ([C6H13OCH2mim][Tf2N]) in aliphatic hydrocarbons (n-hexane, or n-heptane), aromatic hydrocarbons (benzene, or toluene, or ethylbenzene, or o-xylene, or m-xylene, or p-xylene) and cyclohexane was carried out by using a dynamic method from T = 290 K to the boiling temperature of the solvent. In this work, a systematic study of the impact of different factors on the phase behaviour of alkoxy-imidazolium-based ionic liquids with hydrocarbons has been presented. All systems examined showed upper critical solution temperature (UCST) behaviour, with low solubility of the ionic liquid in n-alkanes and cycloalkanes and high solubility in aromatic hydrocarbons. An increase in the alkyl chain length of n-alkane, or at benzene ring resulted in an increase in the UCST. The choice of anion was shown to have large impact on the UCST of the system: by changing the anion [BF4]? to [Tf2N], the solubility dramatically increased and the UCST decreased. The relative hydrocarbon affinity for different anions observed was [BF4]? less than [Tf2N]. The thermophysical characteristic of ionic liquids was detected by differential scanning calorimetry (DSC). The experimental results of LLE have been correlated using the binary parameters of NRTL equation. The average rootmean- square deviation of the equilibrium mole fraction for all the calculated values was 0.0044.