ABSTRACT

The knowledge of the liquid-liquid equilibria (LLE) between ionic liquids (ILs) and water is of utmost importance for environmental monitoring, process design and optimization. Therefore, in this work, the mutual solubilities with water, for the ILs combining the 1-methylimidazolium,[C1im]+; 1-ethylimidazolium, [C2im]+; 1-ethyl-3-propylimidazolium, [C2C3im]+; and 1-butyl-2,3-dimethylimidazolium, [C4C1C1im]+cations with the bis(trifluoromethylsulfonyl)imide anion,were determined and compared with the isomers of the symmetric 1,3-dialkylimidazoliumbis(trifluoromethylsulfonyl)imide ([CnCnim][NTf2], with n = 1 3) and of the asymmetric 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([CnC1im][NTf2], with n = 2 5) series of ILs. The results obtained provide a broad picture of the impact of the IL cation structural isomerism, including the number of alkyl side chains at the cation, on the water-IL mutual solubilities. Despite the hydrophobic behaviour associated to the [NTf2]-anion, the results show a significant solubility of water in the IL-rich phase, while the solubility of ILs in the water-rich phase is much lower. The thermodynamic propertiesof solution indicate that the solubility of ILs in water is entropically driven and highly influenced bythe cation size. Using the results obtained here in addition to literature data, a correlation between the solubility of [NTf2]-based ILs in water and their molar volume, for a large range of cations, is proposed.The COnductor like Screening MOdel for Real Solvents (COSMO-RS) was also used to estimate the LLE ofthe investigated systems and proved to be a useful predictive tool for the a priori screening of ILs aiming at finding suitable candidates before extensive experimental measurements.

Compounds

#	Formula	Name
1	C6H7F6N3O4S2	1-methylimidazolium bis(trifluoromethylsulfonyl)imide
2	C7H9F6N3O4S2	1-ethylimidazolium bis[(trifluoromethyl)sulfonyl]imide
3	C10H15F6N3O4S2	1-ethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide
4	C11H17F6N3O4S2	1-butyl-2,3-dimethyl-1H-imidazolium bis(trifluoromethylsulfonyl)amide
5	H2O	water

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	5 1	Mole fraction - 5 ; Liquid mixture 1	Temperature, K; Liquid mixture 1	Pressure, kPa; Liquid mixture 1	Liquid mixture 1 Liquid mixture 2	Titration method	7
POMD	5 1	Mole fraction - 1 ; Liquid mixture 2	Temperature, K; Liquid mixture 2	Pressure, kPa; Liquid mixture 2	Liquid mixture 2 Liquid mixture 1	UV-vis spectrophotometry	7
POMD	5 2	Mole fraction - 5 ; Liquid mixture 1	Temperature, K; Liquid mixture 1	Pressure, kPa; Liquid mixture 1	Liquid mixture 1 Liquid mixture 2	Titration method	7
POMD	5 2	Mole fraction - 2 ; Liquid mixture 2	Temperature, K; Liquid mixture 2	Pressure, kPa; Liquid mixture 2	Liquid mixture 2 Liquid mixture 1	UV-vis spectrophotometry	7
POMD	5 3	Mole fraction - 5 ; Liquid mixture 1	Temperature, K; Liquid mixture 1	Pressure, kPa; Liquid mixture 1	Liquid mixture 1 Liquid mixture 2	Titration method	7
POMD	5 3	Mole fraction - 3 ; Liquid mixture 2	Temperature, K; Liquid mixture 2	Pressure, kPa; Liquid mixture 2	Liquid mixture 2 Liquid mixture 1	UV-vis spectrophotometry	7
POMD	5 4	Mole fraction - 5 ; Liquid mixture 1	Temperature, K; Liquid mixture 1	Pressure, kPa; Liquid mixture 1	Liquid mixture 1 Liquid mixture 2	Titration method	7
POMD	5 4	Mole fraction - 4 ; Liquid mixture 2	Temperature, K; Liquid mixture 2	Pressure, kPa; Liquid mixture 2	Liquid mixture 2 Liquid mixture 1	UV-vis spectrophotometry	7

Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

Analysis of the isomerism effect on the mutual solubilities of bis(trifluoromethylsulfonyl)imide-based ionic liquids with water

Martins, M. A. R.[Monia A. R.], Neves, C. M. S. S.[Catarina M. S. S.], Kurnia, K. A.[Kiki A.], Santos, L. M. N. B. F.[Luis M. N. B. F.], Freire, M. G.[Mara G.], Pinho, S. P.[Simao P.], Coutinho, J. A. P.[Joao A. P.]

ABSTRACT