Urszula Domańska

Vapour-liquid-solid equilibrium of eicosanoic acid in one- and two-component solvents

Domanska, U., 1986. Vapour-liquid-solid equilibrium of eicosanoic acid in one- and two-component solvents. Fluid Phase Equilibria, 26: 201–220. Solubilities of eicosanoic acid in 14 pure solvents and in 18 pairs of binary solvent systems, at room temperature to temperatures near the melting point of the solid, and VLE along the saturation line in cyclohexane, heptane and ethanol have been determined. Five methods of calculation were applied: the Hilderbrand-Scatchard regular solution theory, the Wilson equation, the Redlich-Kister equation, the van Laar equation and the generalized solubility equation (λh). Mixed solvent systems were found to exhibit a synergistic effect on solubility. The best correlation was obtained with the λh equation.

Activity Coefficients at Infinite Dilution Measurements for Organic Solutes and Water in the Ionic Liquid 1-Butyl-3-methylimidazolium Trifluoromethanesulfonate

The activity coefficients at infinite dilution, gamma 13 (infinity) for 32 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofurane, tert-butyl methyl ether, and water in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][CF3SO3] were determined by gas-liquid chromatography at the temperatures from 298.15 to 368.15 K. The partial molar excess enthalpies at infinite dilution values Delta H 1 (E,infinity) were calculated from the experimental gamma 13 (infinity) values obtained over the temperature range. The selectivities for the hexane/benzene, cyclohexane/benzene, n-hexane/thiophene, n-decane/thiophene, cyclohexane/thiophene, toluene/thiophene, and oct-1-ene/thiophene separation problems were calculated from the gamma 13 (infinity). Obtained values were compared to the literature values for the other ionic liquids, NMP, and sulfolane.

Liquid–liquid equilibria in the binary systems (1,3-dimethylimidazolium, or 1-butyl-3-methylimidazolium methylsulfate + hydrocarbons)

Liquid–liquid equilibria in binary mixtures that contain a room-temperature ionic liquid and an organic solvent—namely, 1,3-dimethylimidazolium methylsulfate, [mmim][CH3SO4], or 1-butyl-3-methylimidazolium methylsulfate, [bmim][CH3SO4] with an aliphatic hydrocarbon (n-pentane, or n-hexane, or n-heptane, or n-octane, or n-decane), or a cyclohydrocarbon (cyclohexane, or cycloheptane), or an aromatic hydrocarbon (benzene, or toluene, or ethylbenzene, or propylbenzene, or o-xylene, or m-xylene, or p-xylene) have been measured at normal pressure by a dynamic method from 270 K to the boiling point of the solvent. Thermophysical basic characterization of pure ionic liquids are presented obtained via differential scanning calorimetry (TG/DSC), temperatures of decomposition and melting, enthalpies of fusion, and enthalpies of glass phase transition. The liquidus curves were predicted by the COSMO-RS method. For [bmim][CH3SO4] the COSMO-RS results correspond much better with experiment than those for [mmim][CH3SO4]. This can be explained partly by the stronger polarity of [mmim][CH3SO4]. The solubilities of [mmim][CH3SO4] and [bmim][CH3SO4] in alkanes, cycloalkanes and aromatic hydrocarbons decrease with an increase of the molecular weight of the solvent. The differences of the solubilities in o-, m-, and p-xylene are not significant. By increasing the alkyl chain length on the cation, the upper critical solution temperature, UCST decreased in all solvents except in n-alkanes.

Solubilities and thermophysical properties of ionic liquids

This report presents the systematic study on the solubilities of 1-alkyl-3-methylimidazolium hexafluorophosphate [e, or bmim][PF6], 1-alkyl-3-methylimidazolium methylsulfate [almim][CH3SO4], 1-hexyloxymethyl-3-methylimidazolium ionic liquids (ILs) [C6H13OCH2mim][BF4], or [C6H13OCH2mim][(CF3SO2)2N] in aliphatic hydrocarbons (heptane, octane), cyclohydrocarbons (cyclopentane, cyclohexane) and aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene), and in alcohols (methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol, tert-butyl alcohol, and 3-methylbutan-1-ol) as well as of 1-alkyl-3-methyl-imidazolium chloride [C4, C10, or C12mim][Cl] in alcohols. The solubilities have been measured by a dynamic method from 290 K to the melting point of IL or to the boiling point of the solvent. The solubility of [emim][PF6] and [bmim][PF6] in aromatic hydrocarbons decreases with an increase of the molecular weight of the solvent. The difference on the solubility in o-, m-, and p-xylene is not significant. The solubility of [emim][PF6] in alcohols decreases with an increase of the molecular weight of the solvent and is higher in secondary alcohols than in primary alcohols. In every case, with the exception of methanol, the mutual liquid–liquid equilibrium was observed. The shape of the equilibrium curve is similar for [emim][PF6] in every alcohol. The observations of upper critical solution temperatures were limited by the boiling temperature of the solvent. For example, for [emim][PF6], solubilities in methanol and ethanol are higher than that in aromatic hydrocarbons. The miscibility gap for C3 alcohols is higher than that in benzene, but comparable with the solubility in toluene; solubility in 3-methyl-butan-1-ol is very similar to ethylbenzene and o-, m-, and p-xylene. The data were correlated by means of the UNIQUAC and modified nonrandom two-liquid (NRTL) equations utilizing parameters derived from the solid–liquid equilibrium (SLE). The root-mean-square deviations of the solubility temperatures for all calculated data depend on the particular system and the equation used. The solubilities of [C4, C10, or C12mim][Cl] and alkyl-(2-hydroxyethyl)-dimethyl-ammonium ILs in octan-1-ol and water have been measured and used to calculate the octan-1-ol/water partition coefficients as a function of temperature and alkyl substituent. Experimental partition coefficients (log P) are negative for imidazoles, 1,3-dialkylimidazolium chlorides, and investigated ammonium salts. Good knowledge of ILs permits the elimination of volatile organic compounds and makes chemistry cleaner and greener.

Thermodynamic Modeling of Ionic Liquid Systems: Development and Detailed Overview of Novel Methodology Based on the PC-SAFT

We present the results of an extensive study on a novel approach of modeling ionic liquids (ILs) and their mixtures with molecular compounds, incorporating perturbed-chain statistical associating fluid theory (PC-SAFT). PC-SAFT was used to calculate the thermodynamic properties of different homologous series of ILs based on the bis(trifluormethylsulfonyl)imide anion ([NTf2]). First, pure fluid parameters were obtained for each IL by means of fitting the model predictions to experimental liquid densities over a broad range of temperature and pressure. The reliability and physical significance of the parameters as well as the employed molecular scheme were tested by calculation of density, vapor pressure, and other properties of pure ILs (e.g., critical properties, normal boiling point). Additionally, the surface tension of pure ILs was calculated by coupling the PC-SAFT equation of state with density gradient theory (DGT). All correlated/predicted results were compared with literature experimental or simulation data. Afterward, we attempted to model various thermodynamic properties of some binary systems composed of IL and organic solvent or water. The properties under study were the binary vapor-liquid, liquid-liquid, and solid-liquid equilibria and the excess enthalpies of mixing. To calculate cross-interaction energies we used the standard combining rules of Lorentz-Berthelot, Kleiner-Sadowski, and Wolbach-Sandler. It was shown that incorporation of temperature-dependent binary corrections was required to obtain much more accurate results than in the case of conventional predictions. Binary corrections were adjusted to infinite dilution activity coefficients of a particular solute in a given IL determined experimentally or predicted by means of the modified UNIFAC (Dortmund) group contribution method. We concluded that the latter method allows accurate and reliable calculations of bulk-phase properties in a totally predictive manner.

Viscosity of ionic liquids: an extensive database and a new group contribution model based on a feed-forward artificial neural network.

A knowledge of various thermophysical (in particular transport) properties of ionic liquids (ILs) is crucial from the point of view of potential applications of these fluids in chemical and related industries. In this work, over 13 000 data points of temperature- and pressure-dependent viscosity of 1484 ILs were retrieved from more than 450 research papers published in the open literature in the last three decades. The data were critically revised and then used to develop and test a new model allowing in silico predictions of the viscosities of ILs on the basis of the chemical structures of their cations and anions. The model employs a two-layer feed-forward artificial neural network (FFANN) strategy to represent the relationship between the viscosity and the input variables: temperature, pressure, and group contributions (GCs). In total, the resulting GC-FFANN model employs 242 GC-type molecular descriptors that are capable of accurately representing the viscosity behavior of ILs composed of 901 distinct ions. The neural network training, validation, and testing processes, involving 90, 5, and 5% of the whole data pool, respectively, gave mean square errors of 0.0334, 0.0595, and 0.0603 log units, corresponding to squared correlation coefficients of 0.986, 0.973, and 0.972 and overall relative deviations at the level of 11.1, 13.8, and 14.7%, respectively. The results calculated in this work were shown be more accurate than those obtained with the best current GC model for viscosity of ILs described in the literature.

Measurements of Activity Coefficients at Infinite Dilution in Solvent Mixtures with Thiocyanate-Based Ionic Liquids Using GLC Technique

The activity coefficients at infinite dilution, gamma13(infinity) for 34 solutes--alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, water, thiophene, ethers, and ketones--in the ionic liquid 1-butyl-4-methylpyridinium thiocyanate, [BMPy][SCN], and in 1-butyl-1-methylpyrrolidinium thiocyanate, [BMPYR][SCN], were determined by gas-liquid chromatography at the temperature range from 298.15 to 368.15 K. The partial molar excess enthalpies at infinite dilution values, DeltaH1E,infinity, were calculated from the experimental gamma13(infinity) values obtained over the temperature range. The selectivities for the n-heptane/benzene, cyclohexane/benzene, and n-heptane/thiophene separation problems were calculated from the gamma13(infinity). Obtained values were compared to the literature values for the other ionic liquids, NMP, and sulfolane.

pKa and Solubility of Drugs in Water, Ethanol, and 1-Octanol

Dissociation constants and corresponding pK(a) values of five drugs were obtained with the Bates-Schwarzenbach method using a Perkin-Elmer Lambda 35 UV/vis spectrophotometer at temperature 298.15 K in the buffer solutions. Atropine, promethazine hydrochloride, ibuprofen, flurbiprofen, and meclofenamic acid sodium salt exhibited pK(a) values of 10.3, 6.47, 5.38, 4.50, and 4.39, respectively. The equilibrium mole fraction solubilities of six drugs were measured in a range of temperatures from 240 to 340 K in three important solvents for drugs: water, ethanol, and 1-octanol using the dynamic method. The basic thermal properties of pure drugs, i.e., melting and glass-transition temperatures, as well as the enthalpy of melting and the molar heat capacity at glass transition (at constant pressure) have been measured with the differential scanning microcalorimetry technique (DSC). Molar volumes have been calculated with the Barton group contribution method. The experimental solubility data have been correlated by means of three commonly known G(E) equations: the Wilson, NRTL, and UNIQUAC, with the assumption that the systems studied here have revealed simple eutectic mixtures. As a measure of goodness of correlation, the root-mean-square deviations of temperature have been used. The activity coefficients of the drugs in saturated solutions for each correlated binary mixture were calculated from the experimental data.

Density and Viscosity of Binary Mixtures of Thiocyanate Ionic Liquids + Water as a Function of Temperature

Densities and viscosities have been determined for binary mixtures of the ionic liquids (ILs) 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN], or 1-butyl-4-methylpyridinium thiocyanate [BMPy][SCN], or 1-butyl-1-methylpyrrolidinium thiocyanate [BMPYR][SCN], or 1-butyl-1-methylpiperidinium thiocyanate [BMPIP][SCN] with water over wide range of temperatures (298.15–348.15) K and ambient pressure. The thermal properties of [BMPy][SCN], i.e. glass transition temperature and the heat capacity at glass transition, have been measured using a differential scanning microcalorimetry, DSC. The decomposition of [BMPy][SCN] was detected. The density and viscosity correlations for these systems have been made using an empirical second-order polynomial and by the Vogel–Fulcher–Tammann equation, respectively. The concentration dependences have been described by polynomials. The excess molar volumes and deviations in viscosity have been calculated from the experimental values and were correlated by Redlich–Kister polynomial expansions. The variations of these parameters, with compositions of the mixtures and temperature, have been discussed in terms of molecular interactions. A qualitative analysis of the trend of properties with composition and temperature was performed. Further, the excess partial molar volumes,

Surface tension of binary mixtures of imidazolium and ammonium based ionic liquids with alcohols, or water : Cation, anion effect

V_{1}^{\mathrm{E}}