Issue 33, 2010

Solubility of alkanes, alkanols and their fluorinated counterparts in tetraalkylphosphonium ionic liquids

Abstract

We investigated the mutual solubility of mixtures of phosphonium-based ionic liquids with alkanes, alkanols, fluorinated alkanes and fluorinated alkanols. The solubilities of other solute molecules like water, formamide, 1,4-dioxane, benzene, and dimethylsulfoxide were also tested. Whenever possible, the corresponding temperature-composition (T-x) phase diagrams at atmospheric pressure were built from cloud-point temperature determinations. The influence of the size of the solute was tested with binary mixtures of trihexyl(tetradecyl)phosphonium acetate, [P6 6 6 14][Ac], with hexane, decane or tetradecane. The influence of the anion of the ionic liquid, namely acetate, [Ac], bis-[(trifluoromethyl)sulfonyl]imide, [Ntf2], trifluoromethanesulfonate, [Otf], and dicyanamide, [dca], on the solubility of the ionic liquids in hexane was also studied. For the ionic liquid [P6 6 6 14][Ntf2] the liquid–liquid phase diagrams were determined with different solutes—alkanes, perfluoroalkanes, partially fluorinated alkanes, and partially fluorinated alkanols—with the aim of analysing the solute–solvent interactions. A comparison of the phase behaviour of solutions containing phosphonium-based ionic liquids and 1-alkyl-3-methylimidazolium based ionic liquids, including a discussion of their different morphologies at a structural level, is also provided. It was found that fluorination of the aliphatic chains of organic compounds can be used as an effective way to control the solubility limits of these compounds in phosphonium- or imidazolium-based ionic liquids, both in terms of concentration and temperature.

Graphical abstract: Solubility of alkanes, alkanols and their fluorinated counterparts in tetraalkylphosphonium ionic liquids

Supplementary files

Article information

Article type
Paper
Submitted
18 Feb 2010
Accepted
14 Apr 2010
First published
10 Jun 2010

Phys. Chem. Chem. Phys., 2010,12, 9685-9692

Solubility of alkanes, alkanols and their fluorinated counterparts in tetraalkylphosphonium ionic liquids

M. Blesic, J. N. C. Lopes, M. F. C. Gomes and L. P. N. Rebelo, Phys. Chem. Chem. Phys., 2010, 12, 9685 DOI: 10.1039/C003408H

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