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A series of solutions composed of air- and water-stable hydrophobic ionic liquids (ILs) [Etpy][Tf2N], [Bupy][Tf2N], [Pepy][Tf2N], [EtM4py][Tf2N], and [BuM4py][Tf2N] were prepared. The electrical conductivity of the solutions was investigated at T= 298.15 K, respectively. Then the electrical conductivity of solutions of [Bupy][Tf2N] and [Hepy][Tf2N] in acetonitrile/propylene carbonate were investigated at temperature range from (283.15 to 313.15) K. The correlation of concentration and electrical conductivity was fitted according to the empirical Casteel–Amis (CA) equation. The maximum electrical conductivity was extrapolated by the fitted result. The influence of the successive methylene (−CH2−) group and the organic solvent to the electrical conductivity was discussed. The temperature dependence of the electrical conductivity of the solutions, ILs [Bupy][Tf2N] and [Hepy][Tf2N] in acetonitrile/propylene carbonate, was fitted by the empirical Vogel–Fulcher–Tamman (VFT) equation at a volume ratio of 50 %. [ABSTRACT FROM AUTHOR]

Adding some salt to a homogeneous aqueous liquid solution of an organic solvent often results in a liquid–liquid phase split. However, such a phase split can also be achieved by charging such a liquid with a gas, in particular when the temperature is close to the critical temperature of that specific gas. This phenomenon is called “salting out by a near-critical gas”. It might be applied in a high-pressure extraction process, for example, to separate and recover valuable biomolecules from aqueous phases. Using a neutral gas like, for example, ethene for pressurizing additionally allows to adjust the pH of the coexisting liquid phases and to influence the partitioning of biomolecules when they change their electric net charge with the pH of the solution. The design of such separation processes requires not only reliable information on the phase forming system, that is, the ternary system (near-critical gas water organic solvent), but also on the partitioning of typical solutes to the coexisting phases. The present publication reports data (from an experimental study with a static-analytical device) for the partitioning of four biomolecules, that is, l-histidine, Aspirin, cimetidine, and 4-dimethylaminoantipyrine (at nearly infinite dilution) to coexisting liquid phases of the high-pressure three-phase liquid–liquid–vapor (L1L2V) equilibrium of the ternary system (ethene water 2-propanol) at (293 and 333) K and pressures from about (5.5 to 17) MPa. The coexisting liquid phases are characterized by distinctly different compositions, the aqueous phase being more hydrophilic than the alkanol-rich phase. Moreover, electrolytes were additionally added to adjust the pH conditions in the liquid phases. The pH-dependent dissociation equilibrium and the related net charge of the biomolecules primarily determine the partitioning behavior: The pH effect is stronger than the impact of varying pressure or temperature. For example, a switch from basic to acidic conditions can invert the partitioning, if that switch at the same time effects a change in the net charge of the solute, for example, from an ionic to a neutral molecule (or vice versa). The ionic solute is more hydrophilic (and thus prefers the aqueous phase), whereas the neutral or zwitterionic solute is less hydrophilic (i.e., more lipophilic) and consequently prefers the propanol-rich liquid phase. [ABSTRACT FROM AUTHOR]

Densities of N,N′-1,2-ethyl-bis(salicyladimine) Schiff base (salen) in dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dichloromethane (CH2Cl2), and chloroform (CHCl3) binary mixtures have been measured in dilute concentration regions of salen at T= (283.15 to 318.15) K under ambient pressure. Apparent molar volumes, Vϕ, and standard partial molar volumes, Vϕ0, have been calculated from the measured densities. The Vϕ0values in DMSO have larger values corresponding to the high polarity of this solvent. The results show that their values would be increased slightly with an increase in temperature. The partial molar expansivities, Eϕ0, and the isobaric thermal expansion coefficients, α*, have been calculated from the temperature dependence of Vϕ0values. The Hepler’s constant values, (∂2Vϕ0/∂T2)p, were found to be positive or very small and negative which indicate that salen Schiff base is predominately a structure maker in all organic solvents studied. [ABSTRACT FROM AUTHOR]

[60]Fullerene has zero solubility in water and very low solubility in many organic solvents. It was found that it forms reverse micelles in organic solvents in the presence of nonionic surfactants. Reverse micellization studies of fullerene solutions in the presence of a nonionic surfactant (Span60) were carried out, and the thermodynamic quantities of the reverse micellization process derived from experimental results indicate that the process is spontaneous. The solution behavior of the [60]fullerene was understood from its ability to form microemulsions from its toluene solution and water using different nonionic surfactants. Light scattering studies showed that the dimensions of these microemulsions reach a maximum of 170 nm. Phase behavior at different temperatures indicates the very high surface active nature of [60]fullerene. [ABSTRACT FROM AUTHOR]

Amberlite LA-2 (a secondary amine mixture) has been studied for its ability to extract acrylic acid at different amine concentrations. The extraction of acrylic acid by Amberlite LA-2 dissolved in seven single solvents (cyclohexane, 2-octanone, toluene, methyl isobutyl ketone (MIBK), iso-octane, hexane, and 1-octanol) has been investigated with respect to different amine concentrations at 298.15 K. In the extraction, two acid−amine complexes, (HO):(R2N) and (HO):(R2N)2, have been assumed to exist in the organic phase in the case of proton-donating diluents, while the complexes (HO):(R2N) and (HO)2:(R2N)3have been suggested in the case of nonproton-donating diluents. Important data for the design and analysis of different separation processes have been obtained as a result of batch experiments. These important data are distribution coefficients (D), loading factors (Z), extraction efficiency (E), and overall extraction constants (K11, K12, K23). The maximum removal of acrylic acid is 98.22 % with MIBK at 0.93 mol·L−1initial concentration of Amberlite LA-2. [ABSTRACT FROM AUTHOR]

Using a laser monitoring technique, the solubility data of taurine in water and aqueous solutions of methanol, ethanol, and 2-propanol were measured over the temperature range from (274.05 to 353.05) K. From the experimental data, the solubility data of taurine in the mixtures of water methanol, water ethanol, and water 2-propanol were found to increase with increasing temperature and decrease with increasing concentration of methanol, ethanol, and 2-propanol in aqueous solution. Also, the water ethanol solution was a better solvent for the purification of taurine. The Apelblat equation, the simplified model of ideal solution, and the λhequation were used to correlate the solubility data; the results showed that the three models mentioned above agreed well with the experimental data, and the Apelblat equation was the most accurate of all of these for these systems. [ABSTRACT FROM AUTHOR]

Solution densities and conductivities for solutions of [Cnmim]Br (n= 8, 10, 12) ionic liquids (ILs) in ethylene glycol, N,N-dimethylformamide, and dimethylsulfoxide have been determined at 298.15 K as a function of ionic liquid concentration. The apparent molar volumes, standard partial molar volumes, molar conductivities, and the limiting molar conductivities of the ILs have been derived from the experimental data. On the basis of the values of the standard partial molar volume and the limiting molar conductivity of the Br−anion available in the literature, the standard partial molar volumes and the limiting molar conductivities for the cations have also been reported in the three organic solvents. These data help to examine the effect of alkyl chain length of the cations and properties of the solvents. It was shown that the standard partial molar volumes of the ILs and their cations increased, but the limiting molar conductivities decreased linearly with the increase of the alkyl chain length. The fluidity of the solvents played an important role in the conductivity properties. [ABSTRACT FROM AUTHOR]

The protonation constant pKa2of l-norvaline has been determined in aqueous solution at different ionic strengths and different temperatures, using the pH-metric technique. The thermodynamic quantities (ΔG°, ΔH°, and ΔS°) have been studied and discussed. Evaluation of the effect of organic solvent of the medium on the protonation processes was also reported and discussed. The organic solvents used were methanol, dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone, and dioxane. The pKa2values for the ionization in a water (1) + dioxane (2) mixture [100 w2= 10 %, 20 %, 30 %, 40 %, and 50 %] have been determined at five different temperatures from T= (288.15 to 308.15) K. The thermodynamic quantities were calculated. [ABSTRACT FROM AUTHOR]

The solubilities of sebacic acid in mixed solvents n-propanol + water have been measured by a dynamic method using a laser monitoring observation technique over a temperature range (288 to 351) K. A synergistic effect on solubility was found to occur in sebacic acid + n-propanol + water mixed systems. To detect the synergistic effect, solubilities of sebacic acid in 14.35 %, 36.97 %, 79.81 %, and 90.00 % mole fraction ethanol aqueous solution were determined to supplement our previous report. A weak synergistic effect was found for sebacic acid + ethanol + water mixed systems. The solid−liquid equilibrium (SLE) data have been fitted using the λhequation, the Wilson equation, and the NRTL equation. The comparison between the experimental and the calculated solubilities for the three models is reasonable, and the root-mean-square deviations for each system range from (0.30 to 1.95) K. [ABSTRACT FROM AUTHOR]

The solubility of stearic acid was measured in ethanol, 2-propanol, heptane, hexane, acetone, and trichloroethylene and in the azeotropic mixtures of the solvents (ethanol−heptane; hexane−ethanol; ethanol−trichloroethylene; acetone−heptane; heptane−2-propanol; acetone−hexane; hexane−2-propanol; 2-propanol−trichloroethylene), by the phase disappearance method, from (290 to 325) K. The stearic acid−pure solvent experimental data were correlated with the Van Laar, Wilson, NRTL, and UNIQUAC equations and the solubility of stearic acid in azeotropic mixtures with the NIBS/Redlich−Kister equation. The UNIFAC solubility prediction improved when the correction for the existence of stearic acid dimers was applied except for systems with trichloroethylene and 2-propanol. The solubility of stearic acid increased in azeotropic mixtures regarding pure solvents except for the heptane−acetone and hexane−acetone mixtures. [ABSTRACT FROM AUTHOR]

Equivalent conductivities of dilute solutions of calcium nitrate, cadmium nitrate, zinc nitrate, and calcium chloride ( c< 0.0021 eq·dm −3) were measured in binary aqueous mixtures containing up to 70 wt % cosolvent (methanol, ethanol, and acetone) at 298.15 K ± 0.1. Data were treated by the Fuoss−Edelson equation, and its parameters, the limiting equivalent conductivity, Λ 0, and the primary association constants, K1A, were evaluated. Variations in Walden products and K1Awere interpreted in terms of ionic properties as well as solvent structure and dielectric constant. [ABSTRACT FROM AUTHOR]

Naproxen (NAP) partitioning thermodynamics was studied in different solvent/buffer systems such as cyclohexane (CH/W), octanol (ROH/W), isopropyl myristate (IPM/W), and chloroform (CLF/W), as well as in dimyristoyl phosphatidylcholine (DMPC) and dipalmitoyl phosphatidylcholine (DPPC) liposome systems. In all cases, the mole fraction partition coefficients (%@mt;sys@%%@ital@%K%@rsf@%%@sx@%ow%@be@%%@ital@%X%@rsf@%%@sxx@%%@mx@%) were greater than unity; therefore, the standard Gibbs energies of transfer were negative indicating a high affinity of NAP for all the organic media. %@mt;sys@%%@ital@%K%@rsf@%%@sx@%ow%@be@%%@ital@%X%@rsf@%%@sxx@%%@mx@%values were approximately 1000-fold higher in the ROH/W system with respect to the CH/W system, thus indicating a high degree of hydrogen-bonding contribution to partitioning, whereas in the case of the IPM/W and CLF/W systems, the %@mt;sys@%%@ital@%K%@rsf@%%@sx@%ow%@be@%%@ital@%X%@rsf@%%@sxx@%%@mx@%values were approximately only 2-fold or 5-fold lower than those observed in ROH/W. On the other hand, %@mt;sys@%%@ital@%K%@rsf@%%@sx@%ow%@be@%%@ital@%X%@rsf@%%@sxx@%%@mx@%values were approximately 55-fold or 39-fold higher in the liposomes compared to the ROH/W system, for DMPC and DPPC, respectively, thus indicating a high degree of bilayer immobilization and/or an electrostatic contribution to partitioning. In almost all cases, standard enthalpies of transfer of NAP from water to organic solvents were negative (except for CH), whereas the standard entropies of transfer were positive (except for IPM). For liposomes, the standard enthalpies and entropies of transfer were positive. These results indicate some degree of participation of the hydrophobic hydration on the NAP partitioning processes. By using the reported data for solvation of NAP in water, the associated thermodynamic functions for NAP solvation in all tested organic phases were also calculated. Finally, all the results obtained for NAP were compared with those presented previously for ketoprofen. [ABSTRACT FROM AUTHOR]

The solubility of 3-chlorophthalic anhydride and 4-chlorophthalic anhydride in ethyl acetate, acetone, and 1,4-dioxane and the solubility of 3-chlorophthalic acid and 4-chlorophthalic acid in water were measured using Schreinemaker’s wet residue method at temperatures ranging from (283.15 to 333.15) K at atmospheric pressure. Results of these measurements were correlated with the modified Apelblat equation. [ABSTRACT FROM AUTHOR]

The solubilities of cloxacillin sodium in binary butyl acetate + methanol and ethyl acetate + methanol solvent mixtures were measured at temperatures ranging from (283.15 to 298.15) K. The experimental data can be well correlated by the CNIBS/Redlich−Kister model. The results show that the solubility of cloxacillin sodium increases with increasing temperature and mole fraction of methanol in these two binary mixed solvents. [ABSTRACT FROM AUTHOR]

The solubilities of 2-(4-ethylbenzoyl)benzoic acid in N,N-dimethylformamide, N-methyl-2-pyrrolidone, methanol, ethanol, 1-propanol, 2-propanol, tetrahydrofuran, benzene, 1,4-dioxane, acetone, and ethyl formate were measured using a synthetic method at temperatures in the range from (279.55 to 343.15) K under atmospheric pressure. The laser-monitoring observation technique was used to determine the dissolution of the solid phase in a solid liquid mixture. The solubility of 2-(4-ethylbenzoyl)benzoic acid in different solvents increased as the temperature increased. Measured solubility values were well correlated as a function of temperature by the modified Apelblat equation. [ABSTRACT FROM AUTHOR]

The solubility of 4-(3,4-dichlorophenyl)-1-tetralone in methanol, ethanol, 2-propanol, acetone, toluene, N,N-dimethylformamide, and tetrahydrofuran were measured using a laser technique in the temperature range from (278.15 to 323.15) K. The results were correlated with a semiempirical equation, which can be used as a useful model in the production process of 4-(3,4-dichlorophenyl)- 1-tetralone and sertraline hydrochloride. [ABSTRACT FROM AUTHOR]

The solubility of 2-aminopyridine in (ethanol + n-butyl acetate) mixed solvents has been measured in the temperature range from (288.15 to 318.15) K by a static analytical method. The concentrations of the 2-aminopyridine in the saturated solution were analyzed by UV spectrometry. A semiempirical equation was proposed to correlate the experimental data. [ABSTRACT FROM AUTHOR]

The solubility of rifapentine in methanol, ethanol, acetone, chloroform, and dichloromethane was measured at temperatures ranging from (278 to 323) K under the atmospheric pressure. The solubility of rifapentine in the above solvents increased in the order chloroform > methanol > dichloromethane > ethanol > acetone. The experimental solubility data were well-correlated with the data, calculated by means of a semiempirical equation. [ABSTRACT FROM AUTHOR]