Gas-liquid Partition Coefficients Research Articles

Measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid 1-butyl-1-methylpyrrolidinium tricyanomethanide

The activity coefficients at infinite dilution, γ13∞, for 62 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, ethers, ketones, acetonitrile, pyridine and 1-nitropropane in the ionic liquid 1-butyl-1-methylpyrrolidinium tricyanomethanide, [BMPYR][TCM] were determined by gas–liquid chromatography at six temperatures over the range of (318.15 to 368.15)K. The partial molar excess Gibbs free energy, ΔG1E∞, enthalpy ΔH1E∞, and entropy term TrefΔS1E,∞ at infinite dilution were calculated from the experimental γ13∞ values obtained over the temperature range. The densities of [BMPYR][TCM] were measured within temperature range from 318.15K to 368.15K. The gas–liquid partition coefficients, KL were calculated for all solutes. The values of selectivity for few separation problems as hexane/benzene, cyclohexane/benzene, heptane/thiophene were calculated from γ13∞ and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other ionic liquids based on [BMPYR]+ cation. In comparison with the former measured ILs, [BMPYR][TCM] present quite high selectivity for the separation of aromatic hydrocarbons and aliphatics hydrocarbons, an average capacity for benzene. The data presented here shows that [BMPYR][TCM] ionic liquid can be used as an alternative solvent for the separation of thiophene from the aliphatic hydrocarbons.

Estimation of extraction properties of new imidazolide anion based ionic liquids on the basis of activity coefficient at infinite dilution measurements

New ionic liquids, based on the 4,5-dicyano-2-(trifluoromethyl)imidazolide [TDI] anion proposed as a new electrolyte in Li-ion batteries, 1-butyl-3-methylimidazolium 4,5-dicyano-2-(trifluoromethyl)imidazolide, [BMIM][TDI] and the 1-butyl-3-methylpyridinium 4,5-dicyano-2-(trifluoromethyl)imidazolide, [BM3PY][TDI], were synthesized and purified. The basic thermal properties of the pure [BMIM][TDI] and [BM3PY][TDI] ionic liquids i.e. glass-transition temperatures, and the heat capacity change at glass transition have been measured using a differential scanning microcalorimetry (DSC). The densities, viscosities and surface tensions of [BMIM][TDI] and [BM3PY][TDI] in temperature range from 283.15K to 363.15K were measured. The density and viscosity correlation for these systems was tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. The surface tensions of pure ionic liquid were measured at atmospheric pressure at five temperatures (298.15, 308.15, 318.15, 328.15 and 338.15)K. The surface thermodynamic functions such as surface entropy and enthalpy were derived from the temperature dependence of the surface tension values. The critical temperature, parachor and speed of sound for pure ionic liquids were described and compared with other ILs with the same cation. The activity coefficients at infinite dilution, γ13∞ were determined at the temperature range from 318.15K to 368.15K by gas–liquid chromatography in the ionic liquid [BMIM][TDI] and [BM3PY][TDI] for 67 solutes: alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, ethers, ketones and pyridine. The interaction of these 66 organic compounds and water with the ILs were described with the partial excess molar Gibbs energies, ΔG1E,∞, enthalpies ΔH1E,∞, and entropies TrefΔS1E,∞ at infinite dilution, calculated from the experimental γ13∞ values, obtained over the temperature range. The gas–liquid partition coefficients, KL were calculated for all solutes. The selectivities for different separation problems were calculated from γ13∞ and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other 1-butyl-3-methylimidazolium, or 1-butyl-3-methylpyridinium-based ionic liquids. Obtained values were compared to the literature values for the other ionic liquids, NMP and sulfolane. The selectivities in proposed extraction processes were not attractive in comparison with previously measured ILs, with exception of water/1-butanol system. However, in contrast with the former measured ILs, [BMIM][TDI] and [BM3PY][TDI] posses higher capacity for benzene and thiophene. The gas–liquid partition coefficients, KL were calculated for all solutes and the Abraham solvation parameter model was discussed.

Infinite dilution activity coefficients of volatile organic compounds in two ionic liquids composed of the tris(pentafluoroethyl)trifluorophosphate ([FAP]) anion and a functionalized cation

Interactions of volatile organic compounds with two ionic liquids (ILs) containing tris(pentafluoroethyl)trifluorophosphate ([FAP]) anion and a functionalized cation, 1-(2-hydroxyethyl)-3-methylimidazolium ([HO-EMIM]) and 1-(2-methoxyethyl)-1-methylpyrrolidinium ([MO-EMPYR]), were explored through systematic GLC retention measurements. Infinite dilution activity coefficients γ1∞ and gas–liquid partition coefficients KL of 30 selected solutes in [HO-EMIM][FAP] and [MO-EMPYR][FAP] were determined at five temperatures in the range from (318.15 to 353.15)K. Partial molar excess enthalpies and entropies at infinite dilution were derived from the temperature dependence of the γ1∞ values. The Linear Free Energy Relationship (LFER) solvation model was used to correlate the KL values. The LFER correlation parameters and excess thermodynamic functions were analyzed to identify molecular interactions operating between the ILs and the individual solutes. By comparing the behaviors of the studied ILs and of their closely similar unfunctionalized analogs, net effects imparted by cation functionalization were also disclosed. The cohesivity of the two ILs was shown to differ dramatically: while [MO-EMPYR][FAP] ranks among ILs to the least cohesive, [HO-EMIM][FAP] belongs to the most cohesive ones. Both [HO-EMIM][FAP] and [MO-EMPYR][FAP] are capable of interacting with solutes specifically through dipolarity/polarizibility and hydrogen bonding, but apparently lack the ability to interact with solute lone electron pairs. The proton donating capability of [HO-EMIM][FAP], undoubtedly brought by the hydroxyl functionality, is enormous and imparts to this IL extraordinary potential for use in solvent-aided separations. As we have demonstrated on some model aliphatic/aromatic separation pairs, [HO-EMIM][FAP] as a solvent for the separation of aliphatic hydrocarbons from aromatics gives superior performance, its performance index (product of selectivity and capacity) surpassing distinctly that of conventional solvents and of most ILs studied so far. [HO-EMIM][FAP] and [MO-EMPYR][FAP] could also serve as efficient entrainers in separations of other non-petrochemical azeotropic systems of industrial importance by extractive distillation as exemplified for some mixtures of alcohols with aprotic oxygenates.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 1-(2-hydroxyethyl)-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate

This work presents new data of activity coefficients at infinite dilution, γ∞ of different organic solutes and water in the 1-(2-hydroxyethyl)-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate, [C2OHmim][FAP] ionic liquid. Values of γ∞ were determined for 65 organic solutes, including alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, 1-nitropropane, aldehydes, acetonitrile and water by inverse gas chromatography within the temperature range from (318.15 to 368.15)K. The basic thermodynamic functions, such as partial molar excess Gibbs energies, ΔG1E,∞, enthalpies, ΔH1E,∞ and entropies, ΔS1E,∞ at infinite dilution were calculated from the experimental γ∞ values obtained over the temperature range. Additionally the gas–liquid partition coefficients, KL were determined. Experimental values of gas–liquid partition coefficients were used to determine the coefficients in the Abraham solvation parameter model (LFER). Results are compared to previously investigated ionic liquids with the same [C2OHmim]+ cation and [FAP]− anion. The selectivity and capacity at infinite dilution for alkanes/thiophene extraction problems were calculated from experimental γ∞ values to verify the possibility of investigated ionic liquid as an entrainer in liquid–liquid extraction.

Determinations of gas–liquid partition coefficients using capillary chromatographic columns. Alkanols in squalane

This study focused on an investigation into the experimental quantities inherent in the determination of partition coefficients from gas–liquid chromatographic measurements through the use of capillary columns. We prepared several squalane – (2,6,10,15,19,23-hexamethyltetracosane) – containing columns with very precisely known phase ratios and determined solute retention and hold-up times at 30, 40, 50 and 60°C. We calculated infinite dilution partition coefficients from the slopes of the linear regression of retention factors as a function of the reciprocal of the phase ratio by means of fundamental chromatographic equations. In order to minimize gas–solid and liquid–solid interface contributions to retention, the surface of the capillary inner wall was pretreated to guarantee a uniform coat of stationary phase. The validity of the proposed approach was first tested by estimating the partition coefficients of n-alkanes between n-pentane and n-nonane, for which compounds data from the literature were available. Then partition coefficients of sixteen aliphatic alcohols in squalane were determined at those four temperatures. We deliberately chose these highly challenging systems: alcohols in the reference paraffinic stationary phase. These solutes exhibited adsorption in the gas–liquid interface that contributed to retention. The corresponding adsorption constant values were estimated. We fully discuss here the uncertainties associated with each experimental measurement and how these fundamental determinations can be performed precisely by circumventing the main drawbacks.The proposed strategy is reliable and much simpler than the classical chromatographic method employing packed columns.

Odour‐causing compounds in air samples: Gas–liquid partition coefficients and determination using solid‐phase microextraction and GC with mass spectrometric detection

A quantification method based on solid-phase microextraction followed by GC coupled to MS was developed for the determination of gas-liquid partition coefficients and for the air monitoring of a group of odour-causing compounds that had previously been found in wastewater samples including dimethyl disulphide, phenol, indole, skatole, octanal, nonanal, benzothiazole and some terpenes. Using a divinylbenzene/carboxen/polydimethylsiloxane fibre, adsorption kinetics have been studied to define an extraction time that would avoid coating saturation. It was found that for an extraction time of 10 min, external calibration could be performed in the range of 0.4-100 μg/m(3), with detection limits between 0.1 and 20 μg/m(3). Inter-day precision of the developed method was evaluated (n = 5) and RSD values between 12 and 24% were obtained for all compounds. The proposed method has been applied to the analysis of air samples surrounding a wastewater treatment plant in Catalonia (Spain). In all air samples evaluated, dimethyl disulphide, limonene and phenol were detected, and the first two were the compounds that showed the highest partition coefficients.

Measurements of activity coefficients at infinite dilution for organic solutes and water in N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] using GLC

This work is a continuation of our research of ionic liquids (ILs) to investigate the possibility of using them as a solvent for the separation processes, especially for extraction of aromatic from aliphatic hydrocarbons. New data of the activity coefficients at infinite dilution, γ13∞ were determined for 53 solutes including: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, acetonitrile, pyridine, 1-nitropropane and water in the ionic liquid: N-hexylisoquinolinium thiocyanate, [HiQuin][SCN] using inverse gas chromatography at wide range of temperature from (308.15 to 368.15)K. From the temperature dependence of γ13∞ the basic thermodynamic function, that is partial molar excess Gibbs free energies, ΔG1E,∞, enthalpies ΔH1E,∞ and entropies TrefΔS1E,∞ at infinite dilution were calculated at a wide temperature range. Additionally the gas–liquid partition coefficients, KL were determined. The selectivities for n-heptane/toluene, cyclohexane/benzene, n-heptane/xylenes separation problems were calculated directly from the experimental values of γ13∞ and compared to the studies from the recent literature for other ionic liquids.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpyrrolidinium trifluorotris(perfluoroethyl)phosphate

This work presents new data of activity coefficients at infinite dilution, γ∞ of different organic solutes and water in the 1-(2-methoxyethyl)-1-methylpyrrolidinium trifluorotris(perfluoroethyl)phosphate ionic liquid. Values of γ∞ were determined for 62 solutes, including alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, 1-nitropropane, butanal, acetonitrile and water by inverse gas chromatography over the temperature range from (318.15 to 368.15)K. The basic thermodynamic functions, namely partial molar excess Gibbs energies, ΔG1E,∞, enthalpies, ΔH1E,∞ and entropies, ΔS1E,∞ at infinite dilution were calculated from the experimental γ∞ values obtained over the temperature range. Additionally the gas–liquid partition coefficients, KL were determined. Experimental values of gas–liquid partition coefficients were used to determine the coefficients in the Abraham solvation parameter model (LFER). Results are compared to previously investigated ionic liquids with the same cations or anions. The selectivities and capacities at infinite dilution for alkanes/thiophene extraction problems were calculated from experimental γ∞ values to verify the possibility of investigated ionic liquid as an entrainer in liquid–liquid extraction.

Physicochemical properties and activity coefficients at infinite dilution for organic solutes and water in a novel bicyclic guanidinium superbase-derived protic ionic liquid

The activity coefficient at infinite dilution, γ13∞, was determined by gas–liquid chromatography at temperatures from T=308.15 to T=348.15K for 54 assorted solutes—among them, alkanes (linear, branched, or cyclic), alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, tetrahydrofuran, 1,4-dioxane, ethers, acetone, ketones, acetonitrile, pyridine, and 1-nitropropane—in the novel bicyclic guanidine superbase-derived protic ionic liquid 1,3,4,6,7,8-hexahydro-1-methyl-2H-pyrimido[1,2-a]pyrimidine bis(pentafluoroethyl)sulfonylimide, [MTBDH][BETI]. The partial molar excess Gibbs free energy ΔG1E,∞, the partial molar excess enthalpy ΔH1E,∞, and entropy at reference temperature TrefΔS1E,∞ at infinite dilution were calculated from the experimental γ13∞ values obtained over this temperature range. The gas–liquid partition coefficient, KL, was calculated for each solute and discussed in light of the Abraham solvation parameter model. The density of the IL as a function of temperature was also measured. The selectivities for heptane/benzene, heptane/thiophene, heptane/pyridine, and heptane/nitropropane separation problems were calculated from γ13∞ and compared to literature values for select ILs, as these separation problems are central to the petroleum industry.

Interactions of volatile organic compounds with the ionic liquids 1-butyl-1-methylpyrrolidinium tetracyanoborate and 1-butyl-1-methylpyrrolidinium bis(oxalato)borate

Interactions of volatile organic compounds with two ionic liquids (ILs) 1-butyl-1-methylpyrrolidinium tetracyanoborate [BMPYR][B(CN)4] and 1-butyl-1-methylpyrrolidinium bis(oxalato)borate [BMPYR][BOB] were explored through systematic GLC retention measurements. Infinite dilution activity coefficients γ1∞ and gas–liquid partition coefficients KL of 30 selected solutes in [BMPYR][B(CN)4] and [BMPYR][BOB] were determined at five temperatures in the range from (318.15 to 353.15)K and from (333.15 to 373.15)K, respectively. Partial molar excess enthalpies and entropies at infinite dilution were derived from the temperature dependence of the γ1∞ values. The Linear Free Energy Relationship (LFER) solvation model was used to correlate successfully the KL values. The LFER correlation parameters and excess thermodynamic functions were analyzed to disclose molecular interactions operating between the ILs and the individual solutes. Among other ILs, [BMPYR][B(CN)4] was identified as a very weakly cohesive solvent medium, in contrast to [BMPYR][BOB] which appears to be fairly cohesive IL close in this respect to [BMPYR][DCA] examined recently. Both [BMPYR][B(CN)4] and [BMPYR][BOB] are capable of interacting specifically through all modes (lone electron pairs, dipolarity/polarizibility, and hydrogen bonding) with solutes of complementary capabilities. Their hydrogen bond basicity and ability to interact with lone electron pairs are appreciable but distinctly lower than those of [BMPYR][DCA]. The proton donating capability of these ILs is weak, but still traceable, and stems undoubtedly from unsubstituted hydrogen atoms on the pyrrolidinium ring of their cation. The selectivities of [BMPYR][B(CN)4] and [BMPYR][BOB] for separation of aromatic hydrocarbons and thiophene from saturated hydrocarbons rank among [BMPYR] ILs the lowest and medium, respectively. The selectivity of [BMPYR][B(CN)4] is comparable to that of sulfolane, but this IL surpasses it roughly three times in the capacity. [BMPYR][B(CN)4] and [BMPYR][BOB] could also serve as efficient entrainers in separations of other non-petrochemical azeotropic systems of industrial importance by extractive distillation. In particular, we have identified [BMPYR][B(CN)4] as a very convenient separation agent for (methanol+dimethyl carbonate) mixture.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate

This work is continuation of our systematic study of activity coefficients at infinite dilution, γ∞ of different organic solutes and water in the ionic liquids. New data of γ∞ were determined for 62 solutes, including alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, 1-nitropropane, butanal, acetonitrile, and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpiperidinium trifluorotris(perfluoroethyl)phosphate by inverse gas chromatography at the temperature range from (318.15 to 368.15)K. The basic thermodynamic functions, namely partial molar excess Gibbs free energies, ΔG1E,∞, enthalpies, ΔH1E,∞ and entropies, ΔS1E,∞ at infinite dilution were calculated from the experimental γ∞ values obtained over the temperature range. Additionally the gas–liquid partition coefficients, KL were determined. Results are compared to previously investigated ionic liquids with the same cations or anions. Values of the selectivity and capacity at infinite dilution for heptane/benzene, heptane/thiophene, and heptane/methanol extraction problems were calculated from experimental γ∞ values to verify the possibility of investigated ionic liquid as an entrainer in liquid–liquid extraction.

Activity coefficients at infinite dilution of organic solutes in 1-octyl-3-methylimidazolium nitrate using gas–liquid chromatography

Activity coefficients at infinite dilution and gas–liquid partition coefficients (KL) of 25 organic solutes, including alkanes, alkenes, alkylbenzenes, alcohols, acetonitrile, ethyacetate, acetone, tetrahydrofuran, dichloromethane, trichromethane, and tetrchloromrthane in the ionic liquid 1-octyl-3-methylimidazolium nitrate ([OMIM][NO3]), have been determined by means of gas–liquid chromatography over a temperature range of 303.15–363.15K with the ionic liquid as the stationary phase. From the dependence of experimental activity coefficients, the partial molar excess enthalpies at infinite dilution and the solubility parameters of the organic solutes in the ionic liquid [OMIM][NO3] have been determined.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-amide

The activity coefficients at infinite dilution, γ∞, gas–liquid partition coefficients, KL, the partial molar excess Gibbs free energy ΔG1E,∞, enthalpy ΔH1E,∞ and entropy ΔS1E,∞ at infinite dilution for 61 organic solutes and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-amide were determined by inverse gas chromatography at the temperatures from (318.15 to 368.15)K. The values of the selectivity for selected compounds which form azeotropic mixtures were calculated from the γ∞ and compared to the literature values for other ionic liquids based on bis(trifluoromethylsulfonyl)-amide anion.

Measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate

The activity coefficients at infinite dilution, γ13∞, for 43 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, ethers, ketones, acetonitrile, pyridine, and 1-nitropropane in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate [EMIM][MeSO3] were determined by gas–liquid chromatography at six temperatures within the range (308.15 to 358.15)K. The interaction of these 42 organic compounds and water with the ionic liquid were described with the partial molar excess Gibbs free energy, ΔG1E,∞, enthalpy ΔH1E,∞, and entropy TrefΔS1E,∞ at infinite dilution, calculated from the experimental γ13∞ values obtained over the temperature range. The gas–liquid partition coefficients, KL were calculated for all solutes. The values of the selectivity for few separation problems as heptane/toluene, cyclohexane/benzene, heptane/xylenes and heptane/thiophene were calculated from γ13∞ and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other ionic liquids based on [EMIM]+ cation. Comparison with the results published earlier for [EMIM][MeSO3] show much lower selectivities in the discussed separation problems. By contrast with the former measured ILs [EMIM][MeSO3] reveals the average selectivity for the separation of aromatics/aliphatics and low capacity for benzene. An interesting high value of selectivity was observed in the separation of thiophene/aliphatics. Very high values of selectivity may be expected in the separation of the azeotropic systems including water. The density of [EMIM][MeSO3] within temperature range from (298.15 to 358.15)K was measured and compared to the literature values.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide

The activity coefficients at infinite dilution, γ∞ and gas–liquid partition coefficients, KL for 61 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, 1-nitropropane, butanal, acetonitrile, and water in the ionic liquid 1-(2-methoxyethyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)-amide were determined by inverse gas chromatography at the temperatures from (318.15 to 368.15)K. The partial molar excess Gibbs free energies ΔG1E,∞, enthalpies ΔH1E,∞ and entropies ΔS1E,∞ at infinite dilution were calculated from the experimental γ∞ values obtained over the temperature range. The selectivities for selected compounds, which form azeotropic mixtures, were calculated from the γ∞ and compared to the literature values for other ionic liquids based on bis(trifluoromethylsulfonyl)-amide anion.

Measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate ([BMPYR][FAP

The activity coefficients at infinite dilution, γ13∞, for 60 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, acetic acid, thiophene, ethers, ketones, esters, butyraldehyde and acetonitrile in the ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate [BMPYR][FAP], were determined by gas–liquid chromatography at six temperatures in range of 318.15–368.15K. The interaction of these 59 organic compounds and water with the IL was described with the partial excess molar Gibbs energies, ΔG1E,∞, enthalpies ΔH1E,∞, and entropies TrefΔS1E,∞ at infinite dilution, calculated from the experimental γ13∞ values obtained over the temperature range. The gas–liquid partition coefficients, KL were calculated for all solutes. The selectivities for different separation problems were calculated from γ13∞ and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other tris(pentafluoroethyl)trifluorophosphate-based ionic liquids. Comparison with other 1-butyl-1-methylpyrrolidynium-based ILs shows much lower capability of [BMPYR][FAP] to reveal hydrogen bonds and interact with lone electron pairs and/or polar groups of solutes. In contrast with the former measured ILs, [BMPYR][FAP] was found to posses however very high capacity for benzene. The density of [BMPYR][FAP] in temperature range from 318.15K to 368.15K was measured.

Activity coefficients at infinite dilution and physicochemical properties for organic solutes and water in the ionic liquid 4-(2-methoxyethyl)-4-methylmorpholinium bis(trifluoromethylsulfonyl)-amide

The activity coefficients at infinite dilution, γ 13 ∞ and gas–liquid partition coefficients, K L for 62 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, esters, 1-nitropropane, butanal, acetonitrile, acetic acid and water in the ionic liquid 4-(2-methoxyethyl)-4-methylmorpholinium bis(trifluoromethylsulfonyl)-amide were determined by gas–liquid chromatography at the temperatures from (318.15 to 368.15) K. The partial molar excess Gibbs free energies Δ G 1 E, ∞ , enthalpies Δ H 1 E, ∞ and entropies Δ S 1 E, ∞ at infinite dilution were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The selectivities for selected compounds which form azeotropic mixtures were calculated from the γ 13 ∞ and compared to the literature values for other ionic liquids based on bis(trifluoromethylsulfonyl)-amide anion.

Measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid 1-hexyl-3-methylimidazolium tetracyanoborate

The activity coefficients at infinite dilution, γ 13 ∞ , for 59 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, acetic acid, thiophene, ethers, ketones, esters, butanal 4, and acetonitrile in the ionic liquid 1-hexyl-3-methylimidazolium tetracyanoborate, [HMIM][TCB], were determined by gas–liquid chromatography at six temperatures over the range (318.15 to 368.15) K. The partial molar excess Gibbs free energies Δ G 1 E, ∞ , enthalpies Δ H 1 E, ∞ , and entropies Δ S 1 E, ∞ at infinite dilution were calculated from the experimental γ 13 ∞ values obtained over the temperature range. The gas–liquid partition coefficients, K L were calculated for all solutes. The selectivities for different separation problems were calculated from γ 13 ∞ and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, and other tetracyanoborate-based ionic liquids. The densities of [HMIM][TCB] within the temperature range from 318.15 K to 368.15 K were measured.

Interactions of Volatile Organic Compounds with the Ionic Liquid 1-Butyl-1-methylpyrrolidinium Dicyanamide

Interactions of volatile organic compounds with the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium dicyanamide [BMPYR][DCA] were explored through systematic gas–liquid chromatography retention measurements. Infinite dilution activity coefficients γ1∞ and gas–liquid partition coefficients KL of 30 selected hydrocarbons, alcohols, ketones, ethers, esters, haloalkanes, and nitrogen- or sulfur-containing compounds in [BMPYR][DCA] were determined at five temperatures in the range from (318.15 to 353.15) K. Partial molar excess enthalpies and entropies at infinite dilution were derived from the temperature dependence of the γ1∞ values. The linear free energy relationship (LFER) solvation model was used to correlate successfully the KL values. The LFER correlation parameters and excess thermodynamic functions were analyzed to disclose molecular interactions operating between the IL and the individual solutes. Among other ILs, [BMPYR][DCA] was identified to be a fairly cohesive solvent medium, which is capable o...

Interactions of volatile organic compounds with the ionic liquid 1-ethyl-3-methylimidazolium tetracyanoborate

Interactions of volatile organic compounds with the ionic liquid (IL) 1-ethyl-3-methylimidazolium tetracyanoborate [EMIM][B(CN) 4] were explored through systematic GLC retention measurements. Infinite dilution activity coefficients γ 1 ∞ and gas–liquid partition coefficients K L of 30 selected solutes in [EMIM][B(CN) 4] were determined at five temperatures in the range from (318.15 to 353.15) K and respective dissolution enthalpies H ¯ 1 E, ∞ and entropies S ¯ 1 E, ∞ were derived. Reliability of our results was substantiated by additional measurements we carried out using the inert gas stripping technique, IL samples from two different batches, and careful purity checks. Since two similar experimental studies on [EMIM][B(CN) 4] have emerged during the progression of this work, a unique possibility has arisen for direct inter-laboratory comparison of results. While the present values and those of Yan et al. [P.F. Yan, M. Yang, X.M. Liu, C. Wang, Z.C. Tan, U. Welz-Biermann, J. Chem. Thermodyn. 42 (2010) 817–822] show disparities as large as 30% in γ 1 ∞ and 6 kJ · mol −1 in H ¯ 1 E, ∞ , the present values and those of Domanska et al. [U. Domanska, M. Krolikowska, W.E. Acree, G.A. Baker, J. Chem. Thermodyn. 43 (2011) 1050–1057] exhibit almost perfect agreement. The Linear Free Energy Relationship (LFER) analysis of the results was performed to disclose molecular interactions operating between the IL and the individual solutes. [EMIM][B(CN) 4] was identified as a rather weakly cohesive IL. Comparison with [EMIM][NO 3] and [EMIM][MeSO 3], two [EMIM] based ILs with hard anions we studied recently, reveals much lower capability of [EMIM][B(CN) 4] to accept hydrogen bonds and interact with lone electron pairs of solutes. In contrast with the former ILs, [EMIM][B(CN) 4] was found to possess however appreciable proton donating capability. This striking observation demonstrates that the behavior of [EMIM] cation is affected by its counterion: while in case of the former ILs the acidic hydrogen in position 2 on the [EMIM] ring is blocked interacting with the hard anions, in case of [EMIM][B(CN) 4] this hydrogen atom is made more available for hydrogen bonding with basic solutes thanks to the soft character of [B(CN) 4] anion.