Excess volumes and enthalpies of mixing benzene with various bicyclic compounds

The V _m ^E and H _m ^E for solutions of benzene in decahydronaphthalene, in bicyclohexyl, in cyclohexylbezene and in 1,2,3,4-tetrahydronaphthalene have been measured over the complete composition range at 25°C. The results have been fitted to the Flory theory of liquid mixtures.     

Application of the Prigogine-Flory-Patterson theory part II. Mixtures of a bicyclic compound,benzene, cyclohexane,n-hexane with a 1-alkene and a 1-alkyne

The Prigogine-Flory-Patterson theory of liquid mixtures has been applied to the H _m ^E and V _m ^E for binary mixtures of an n-alkane with decalin, bicyclohexyl, tetralin, cyclohexylbenzene, benzene, cyclohexane and n-hexane with 1-hexene, 1-hexyne, 1-heptene and 1-heptyne. Furthermore the Prigogine-Flory theory has been used to predict activity coefficients at infinite dilution from the experimentally determined H _m ^E at 25°C for the mixtures 1-hexene, 1-hexyne, 1-heptene, 1-heptyne with decalin, bicyclohexyl, tetralin and cyclohexylbenzene. The predictions are compared to experimental results.     

Application of the Prigogine-Flory-Patterson theory part III. Mixtures of a bicyclic compound,benzene, cyclohexane,n-hexane with a cycloalkane,cyclohexene, a cycloalkadiene and benzene

The Prigogine-Flory-Patterson theory of liquid mixtures has been qpplied to the H _m ^E and V _m ^E for binary mixtures of a bicyclic compound, benzene, cyclohexane and n-hexane with a cycloalkane, cyclohexene, a cycloalkadiene and benzene. Furthermore the Prigogine-Flory theory has been used to predict activity coefficients at infinite dilution from the experimentally determined H _m ^E at 25°C for the mixtures cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene and benzene with a bicyclic compound. The predictions are compared to experimental results.     

Application of the Prigogine-Flory-Patterson theory part I. Mixtures ofn-alkanes with bicyclic compounds,benzene, cyclohexane andn-hexane

The Prigogine-Flory-Patterson theory of liquid mixtures has been applied to the H _m ^E and V _m ^E for binary mixtures of an n-alkane with decalin, bicyclohexyl, tetralin, cyclohexylbenzene, benzene, cyclohexane and n-hexane. Furthermore the Prigogine-Flory theory has been used to predict activity coefficients at infinite dilution from the experimentally determined H _m ^E at 25°C and at finite concentrations for n-hexane and n-heptane with decalin, bicyclohexyl, tetralin and cyclohexylbenzene.     

Activity coefficient at infinite dilution, azeotropic data, excess enthalpies and solid–liquid-equilibria for binary systems of alkanes and aromatics with esters

Binary azeotropic data have been measured at different pressures for ethyl acetate + heptane, methyl acetate + heptane, isopropyl acetate + hexane and isopropyl acetate + heptane by means of a wire band column. Additionally activity coefficients at infinite dilution have been determined for ethyl acetate and isopropyl acetate in decane and dodecane in the temperature range between 303.15 and 333.15 K with the help of the dilutor technique. Furthermore excess enthalpies for the binary systems methyl acetate + hexane, methyl acetate + decane, ethyl acetate + hexane and ethyl acetate + decane at 363.15 and 413.15 K have been studied with the help of isothermal flow calorimetry. Finally solid–liquid equilibria for the systems ethyl myristate + benzene and ethyl myristate + p-xylene have been investigated by a visual technique. All these data have been used for the revision and extension of the group interaction parameters of the group contribution method modified UNIFAC (Dortmund) and the group contribution equation of state VTPR. The experimental data was compared with the results predicted using the group contribution method modified UNIFAC (Dortmund) and the group contribution equation of state VTPR.     

Activity coefficients at infinite dilution measurements for organic solutes in the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide using g.l.c. at T = (298.15, 313.15, and 333.15) K

The activity coefficients at infinite dilution, (where 1 refers to the solute and 3 to the solvent), for both polar and non-polar solutes (alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, benzene, carbon tetrachloride, and methanol) in the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide [HMIM][Tf₂N] at three temperatures T = (298.15, 313.15, and 333.15) K have been determined by gas-liquid chromatography. The interaction at the gas-liquid interface between the solutes and the solvent was examined by varying solvent liquid loading on the column. Corrected retention values, taking carrier gas and solute imperfections into account, were determined and used to calculate the activity coefficients at infinite dilution. The results have been used to predict the solvent potential for the hexane/benzene separation from calculated selectivity values. The results were compared to for similar systems found in the literature in an attempt to understand the effect of the nature of the cation and anion has on solute-solvent interactions.The partial molar excess enthalpies at infinite dilution values were calculated from the experimental values obtained over the temperature range.     

Thermodynamic properties of some N-alkyl-N-methylpiperidinium chlorides and N-alkylpiperidine hydrochlorides in water

Densities and heat capacities at 25°C were measured for N-octyl-, N-decyl- and N-dodecyl-N-methylpiperidinium chlorides and for N-octyl- and N-dodecylpiperidine hydrochlorides in water as functions of concentration. Enthalpies of dilution at 25°C and osmotic coefficients at 37°C of the N-methyl-N-alkylpiperidinium chlorides were also measured as functions of concentration. The partial molar volumes, heat capacities, relative enthalpies, nonideal Gibbs energies and entropies at 25°C were derived as functions of the surfactant concentration. By increasing the alkyl chain length of the surfactant, both the apparent molar volume vs. concentration curves are shifted toward greater values while the corresponding ones for the heat capacity are moved toward more negative values. These results are consistent with the higher hydrophobicity the longer the alkyl chain of the surfactant is. In the micellar region, the entropy and enthalpy vs. log m/m _cmc curves increase in a parallel manner by decreasing the alkyl chain length of the surfactant. Consequently, the negligible effect of the hydrophobicity of the surfactant on the Gibbs energy vs. log m/m _cmc trends is due to the enthalpy-entropy compensative effect. The thermodynamic functions of micellization were graphically evaluated on the basis of the pseudo-phase transition model. The absolute values of both the volume and heat capacity of micellization increase with an increasing number of carbon atoms in the alkyl chain (n _c ). The enthalpy and entropy of micellization vs. n _c are convex curves. Comparisons are also made between the present data and those of some alkylpyridinium chlorides reported elsewhere.     

Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 4-methyl-N-butyl-pyridinium bis(trifluoromethylsulfonyl)-imide

The activity coefficients at infinite dilution, for 36 solutes: alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, ethers, acetone, and water in the ionic liquid 4-methyl-N-butyl-pyridinium bis(trifluoromethylsulfonyl)-imide [bmPY][NTf₂] were determined by gas–liquid chromatography at temperatures from 298.15 K to 368.15 K. The partial molar excess enthalpies at infinite dilution values were calculated from the experimental values obtained over the temperature range. The selectivity for different separation problems were calculated from the and compared to the literature values for other ionic liquids, N-methyl-2-pyrrolidinone (NMP) and sulfolane.     

Thermodynamic data for nonmesomorphic solutes at infinite dilution in the nematic and isotropic phases of hexylcyanobiphenyl

Infinite dilution solute activity coefficients _o ² , partial molar excess enthalpies and entropies , and partial molar enthalpies ( ) and entropies ( ) of solution, obtained using gas-liquid chromatography (GLC), are reported for thirty nonmesomorphic solutes in the nematic and isotropic phases of p-n-hexyl-p-cyanobiphenyl (6CB). The solutes studied include normal and branched alkanes, alkenes and hexadienes (with some cis and trans isomers), and benzene. The results corroborate earlier studies on other members of the p-n-alkyl-p-cyanobiphenyl homologous series of liquid crystals. The results demonstrate the effect that solute structure (size, shape, flexibility, polarizability and polarity) has on the solution process. Thermodynamic data for the cis and trans isomers of 2-pentene and 2-hexene are examined. A method for the simultaneous examination of the effects of both solute and solvent structures on the solution process is suggested.     

Enthalpies of dilution of aqueous Li2B4O7 solutions at 298.15 K and application of ion-interaction model

The enthalpies of dilution have been measured for aqueous Li₂B₄O₇ solutions from 0.0212 to 2.1530 mol kg⁻¹ at 298.15 K. The relative apparent molar enthalpies, L_?, and relative partial molar enthalpies of the solvent and solute, and were calculated. The thermodynamic properties of the complex aqueous solutions were represented with a modified Pitzer ion-interaction model.     

Activity coefficients at infinite dilution of organic solutes in N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([CnPY][NTf2], n = 2, 4, 5) using gas–liquid chromatography

The activity coefficients at infinite dilution, for both polar and non-polar solutes in the ionic liquids N-alkylpyridinium bis(trifluoromethylsulfonyl)imide ([C_nPY][NTf₂], n = 2, 4, 5) have been determined by gas–liquid chromatography using the ionic liquid as the stationary phase. The measurements were carried out at the temperatures from (303 to 353) K. The partial molar excess enthalpies at infinite dilution of the solutes in the ionic liquids were also derived from the temperature dependence of the values. The values of the selectivity for the hexane/benzene and cyclohexane/benzene separation problems were calculated from experimental infinite dilution activity coefficient values and compared to the other ionic liquids, taken from the recent literatures.     

Thermodynamics of mixed electrolyte solutions. IX. Calculation of the osmotic and activity coefficients in a pseudoternary system (NaCl−nKCl)−MgCl2-H2O at 298.15°K

The equation of Reilly, Wood, and Robinson was used to predict the osmotic coefficient of a pseudoternary system (NaCl–nKCl)–MgCl₂–H₂O over a molal ionic strength range of 1.0 to 5.0 moles-kg^–1. The results are in close agreement with experimental data at most ionic strengths. The standard deviation in the osmotic coefficients over the entire concentration range lies within 0.0035. The predicted values of the mean activity coefficients are in good agreement with those obtained by the treatments of both Scatchard and Friedman. Mean activity coefficients for the other components were also predicted.     

Thermodynamic properties of transition metals in aqueous solution:4. The enthalpies of mixing aqueous solutions of CdCl2, CuCl2 and ZnCl2 with MgCl2 at varying ionic strength at 25°C

Enthalpies of mixing ΔH _m of aqueous solutions of CdCl₂, CuCl₂, and ZnCl₂ with MgCl₂ solutions were measured at ionic strengths of 1.0, 2.0, and 3.0 at 25°C. The excess enthalpy equations of Pitzer were then fitted to the resulting ΔH _m data. The resulting parameters are the temperature derivatives of the activity coefficient mixing parameters in the Pitzer system.     

Dioxouranium(VI)-carboxylate complexes: A calorimetric and potentiometric investigation of interaction with oxalate at infinite dilution and in NaCl aqueous solution at I = 1.0 mol L and T = 25 °C

In this paper we investigated the interactions between dioxouranium(VI) and oxalate using (H⁺-glass electrode) potentiometry and titration calorimetry. Potentiometric measurements were carried out in NaCl aqueous solutions and at T = 25 °C in a wide range of experimental conditions (concentrations, ligand/metal molar ratio, pH, titrants) at low ionic strength values (I ≤ 0.090 mol L⁻¹, without supporting electrolyte) and at I = 1.0 mol L⁻¹; different procedures were employed for the acquisition of experimental data and careful analysis of these data performed. In all cases the speciation model that best fits experimental data takes into account the formation of the binary mononuclear species UO₂(ox)⁰, UO₂(ox)₂²⁻, UO₂(ox)₃⁴⁻ widely reported in literature, the ternary hydroxyl mononuclear species UO₂(ox)OH⁻, UO₂(ox)(OH)₂²⁻, UO₂(ox)₂OH³⁻, UO₂(ox)₃OH⁵⁻, the protonated ternary mononuclear species UO₂(ox)₃H³⁻ and the binuclear species (UO₂)₂(ox)₅⁶⁻.Calorimetric measurements were carried out following similar procedures and in the same experimental conditions as employed for the potentiometric measurements at I = 1.0 mol L⁻¹ in NaCl. The stability of UO₂²⁺-oxalate²⁻ complexes is fairly high and their main contribution to stability is entropic in nature. Some linear empirical relationships were found which make it possible to calculate (i) the contribution of a single bond: and ; (ii) chelate stabilisation per ring: and and (iii) the mean stability of negatively charged Na⁺-ion pair complexes: log^TK = (0.46 ± 0.02)·|z| (z = charge of complex species), ΔG° = −(2.60 ± 0.1)·|z| kJ mol⁻¹ and TΔS° = 2.5 ± 0.5 kJ mol⁻¹. Both potentiometric and calorimetric results provide evidence of the penta-coordination of the species UO₂(ox)₃⁴⁻. SIT parameters were calculated from the data at I = 0 and I = 1.02 mol kg⁻¹. Comparisons are made with literature data. An insoluble dioxouranium(VI) ternary complex was synthesised (at I = 1.0 mol L⁻¹ in NaCl) and characterised by thermoanalysis and elemental analysis.     

Thermodynamic investigations on derivatives of pyrimidine nucleic acid bases: Joint use of calorimetric, volumetric and structural data for the description of properties of pyrimidine nucleic acid bases and their derivatives

The experimental enthalpies of solution Δ_solH_m^∞, van’t Hoff enthalpies of sublimation Δ_s^gH_m⁰ of solid compounds, partial molar volumes V₂⁰, and partial molar heat capacities C_p,2⁰ of aqueous solutions of pyrimidine nucleic acid bases and their derivatives, determined previously and collected here, are discussed in terms of calculated structural parameters. Relations have been established between the calorimetric and volumetric properties. Correlations have been developed to relate both the enthalpies of solvation and the partial molar heat capacities to the polar and apolar parts of the accessible molecular surface areas.