Ionic liquids based aqueous biphasic systems: Effect of the alkyl chains in the cation versus in the anion
authors Patinha, DJS; Alves, F; Rebelo, LPN; Marrucho, IM
nationality International
journal JOURNAL OF CHEMICAL THERMODYNAMICS
author keywords Ionic liquids; Aqueous biphasic systems; Alkylsulfonate anions; L-tryptophan extraction
keywords 2-PHASE SYSTEMS; EXTRACTION; SALTS; SEPARATION; WATER; TEMPERATURE; PHOSPHATE; SULFATE
abstract The use of alkyl-3-methylimidazolium alkylsulfonate ionic liquids for implementing aqueous biphasic systems is studied in this work for the first time. The ability of high charge density inorganic salts, such as K3PO4, to promote phase segregation in aqueous solutions containing the ionic liquids 1,3-dimethylimidazolium methylsulfonate ([C(1)mim][C1SO3]), 1-ethyl-3-methylimidazolium hexylsulfonate ([C(2)mim][C6SO3]), 1-ethyl-3-methylimidazolium butylsulfonate ([C(2)mim][C4SO3]), 1-butyl-3-methylimidazolium methylsulfonate ([C(4)mim][C1SO3]), 1-butyl-3-methylimidazolium ethylsulfonate ([C(4)mim][C2SO3]), 1-pentyl-3-methylimidazolium methylsulfonate ([C(5)mim][C1SO3]), 1-hexyl-3-methylimidazolium methylsulfonate ([C(6)mim][C1SO3]) and 1-hexyl-3-methylimidazolium ethylsulfonate ([C(6)mim][C2SO3]) was experimentally determined at 298.15 K and atmospheric pressure. In general, the hydrophobicity of the ionic liquids studied is affected by the increase of the alkyl chain length. However, the position of the alkyl chain, whether in the cation or in the anion affects in a different way the lipophilic effect of the ionic liquid. Two ionic liquids with the same number of carbon atoms, the one with a longer chain in the anion is the more hydrophobic. Furthermore, four ionic liquids were chosen to extract the aminoacid L-tryptophan from aqueous solutions. The chain lengths of the anion or cation were fixed and the partition coefficients compared. The extractions, carried out at 298.15 K, showed the good extractive power of these ionic liquids and also that the less hydrophobic ionic liquids have the better extraction coefficients. Overall, the results from this work identify relations between the length and position of the alkyl chain with the hydrophobicity and also with the extractive power of the imidazolium-alkylsulfonate based ionic liquids. (c) 2013 Elsevier Ltd. All rights reserved.
publisher ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
issn 0021-9614
year published 2013
volume 65
beginning page 106
ending page 112
digital object identifier (doi) 10.1016/j.jct.2013.05.043
web of science category Thermodynamics; Chemistry, Physical
subject category Thermodynamics; Chemistry
unique article identifier WOS:000323600300016
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journal impact factor 2.631
5 year journal impact factor 2.531
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