Phase behavior of tricyanomethanide-based ionic liquids with alcohols and hydrocarbons

Abstract

Ionic liquids (ILs) are known as attractive solvents showing high extraction capacity for aromatic hydrocarbons from aliphatic hydrocarbons and for sulfur compounds from alkanes. New experimental results on liquid–liquid phase equilibrium (LLE) in the binary systems of {1-butyl-1-methylpyrrolidinium tricyanomethanide, [BMPYR][TCM]+an alcohol (1-octanol, 1-decanol), or + hydrocarbons (benzene, toluene, ethylbenzene, and heptane)} and of {1-butyl-1-methylmorpholinium tricyanomethanide, [BMMOR][TCM]+an alcohol (1-hexanol, 1-octanol, 1-decanol), or + hydrocarbons (benzene, toluene, ethylbenzene, thiophene, and heptane)} have been determined at atmospheric pressure using a dynamic method. Upper critical solution temperature type of phase behavior for alcohols and a visible tendency for heptane was observed. For aromatic hydrocarbons there is a visible tendency of the lower critical solution temperature phase behavior. Decrease of solubility of alcohol with an increase of its alkyl chain length and of aromatic hydrocarbons with an increase of the alkyl chain length of substituent for all studied systems was detected. The correlation of the experimental data has been carried out using the non-random two liquid (NRTL) equation. The influence of the cation structure on the phase behavior has been discussed. The phase diagrams reported here have been compared to the systems published earlier with the 1-butyl-1-methylpyrrolidinium, or TCM – based ionic liquids.