Miscibility Phenomena in Systems Containing Polyhydroxy Alcohols and Ionic Liquids

Ionic liquids are innovative media for applications, which offer large advantages over common chemicals, such a negligible vapor pressure, and thus, no air pollution potential, and comparative thermal stability. All these properties make them good solvents compared to the classical volatile chemicals and allow for their employment in reactions, extractions, and material processing. For this reason investigations into phase equilibria in many systems with ionic liquids are essential. This paper focuses on the liquid liquid equilibria of twenty binary mixtures composed of the imidazolium based ionic liquids with dicyanamide ([C(n)mim][DCA]) or bistriflamide([C(n)mim][NTf(2)])anions and glycols, or glycerol, or butan-1-ol. In this study, the following glycols were tested: (ethylene glycol (ethane-1,2-diol); propylene glycol (propane-1,2-diol); propane-1,3-diol; butylene glycols (butane-1,2-diol; butane-1,3-diol, butane-1,4-diol; butane-2,3-diol); diethylene glycol (2,2'-oxydiethanol); dipropylene glycol (4-oxaheptane-1,7-diol). The systems containing hydrophilic dicyanamide ionic liquid exhibit complete miscibility with the studied polyhydroxy alcohols. Solutions containing bis(trifluoromethylsulfonyl)amide ionic liquids demonstrate limited solubility with the investigated butane-1,2-diol and its isomers. It was found that miscibility of [C(n)mim][NTf(2)] with butanediols depends on the choice of the cation and the arrangement of hydroxyl groups in the alcohol structure.