Liquid-Liquid Equilibrium of Cholinium-Derived Bistriflimide Ionic Liquids with Water and Octanol

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Abstract

The liquid-liquid equilibria of mixtures of cholinum-based ionic liquids (N-alkyl-N,N-dimethylhydroxyethylammonium bis(trifluoromethane)sulfonylimide, [N-11n2OH](-) [Ntf(2)], n = 1, 2, 3, 4, and 5) plus water or 1-octanol were investigated at atmospheric pressure over the entire composition range. The experiments were conducted between 265 and 385 K using the cloud-point method. The systems exhibit phase diagrams consistent with the existence of upper critical solution temperatures. The solubility of [N-1 (1) (n) (2OH)](-) [Ntf(2)] in water is lower for cations with longer alkyl side chains (larger n values). The corresponding trend in the octanol mixtures is reversed. The ([N-1 (1) (1) (2OH)][Ntf(2)] + water + octanol) ternary system shows triple liquid-liquid immiscibility at room temperature and atmospheric pressure. A combined analytic/synthetic method was used to estimate the corresponding phase diagram under those conditions. Auxiliary molecular dynamics simulation data were used to interpret the experimental results at a molecular level.
Original languageUnknown
Pages (from-to)9186-9195
JournalJournal Of Physical Chemistry B
Volume116
Issue number30
DOIs
Publication statusPublished - 1 Jan 2012

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