Journal of Chemical Thermodynamics最新文献

The density (ρ), and refractive index (n_D) of three binary mixtures containing 1-butanol, 2-butanol, and 2-methyl-2-propanol with diethyl phthalate (DEP) were studied over the whole range of composition at different temperatures from 293.15 to 313.15 K, and atmospheric pressure (0.082 MPa). Experimental data were used to calculate the excess molar volumes ($V_m^E$) and deviation in refractive indices ($\Delta n_D$). The experimental density values were used to calculate the partial molar volumes (${\overline{V}}_{m,i}$), apparent molar volumes ($V_{\varnothing ,i}$), partial molar volumes at infinite dilution (${\overline{V}}_{m,i}^{\infty }$), and excess partial molar volumes (${\overline{V}}_{m,i}^E$). A Redlich-Kister type polynomial equation is used with the method of least-squares to set up a correlation between excess molar volumes and deviation in refractive indices, leading to the estimation of binary coefficients and standard errors. Theoretical refractive index values were calculated using seven relations, namely Arago–Biot (A–B), Dale–Gladstone (D–G), Lorentz–Lorenz (L–L), Heller (H), Weiner (W), Newton (Nw) and Eyring and John (E-J). This study examines how composition and temperature affect the variation of parameters in these mixtures, considering molecular interactions. Experimental data and results provide useful information for further thermodynamic studies of alcohol-ester mixtures.

The shake-flask method was used to determine the solubility of sotalol hydrochloride (STL), a cardiovascular drug, in solvents modeling a variety of body media within the temperature range (293.15–313.15) K. In the descending order of the drug solubility the solvents can be arranged as follows: buffer pH 2.0, buffer pH 7.4, 1-octanol, n-hexane. The experimental values of solubility of the drug in aqueous solvents agree well with the calculated values of the pH-solubility profile. The study shows that the maximum solubility of the salt is observed within the pH range from 2.9 to pH_max equal to 6.1. Temperature dependencies of the STL distribution coefficients were obtained in 1-octanol/buffer pH 7.4 and n-hexane/buffer pH 7.4 systems. Since the values of the partition coefficients of hydrophilic STL are low, it was concluded that the diffusion through the lipid biolayer of cell membranes was unfavorable and that the paracellular transport of the drug molecules might prevail. The thermodynamic functions of dissolution and transfer were calculated and discussed taking into account the physicochemical properties of STL and the solvents used.

Density and viscosity of two trifluoromethanesulfonate-based ionic liquids: 1-ethylimidazolium trifluoromethanesulfonate, [Eim][Triflate], and 1-ethylpyridinium trifluoromethanesulfonate, [Epy][Triflate], as well as binary mixtures of these ILs with water or ethanol were measured within the temperature range of 293.15–333.15 K. Measured density data were used to calculate the excess molar volume and the component partial molar volume and the obtained values were fitted using the Redlich-Kister expansion. Variation of viscosity with the binary mixture composition and temperature was modeled using the Jouyban-Acree model. Data on the vapor−liquid equilibrium (VLE) of the respective ionic liquids with water and ethanol were estimated at atmospheric pressure over a wide range of IL concentrations (up to 70 mol% of IL). For the boiling point temperature measurement of four respective binaries, an adapted Siwoloboff procedure was used. To describe VLE of these binary mixtures, ideal vapor phase and real liquid phase behavior were assumed; experimental isobaric t–x data were correlated with the NRTL model.

The difenoconazole solubilities in acetonitrile/acetone/N,N-dimethylformamide (DMF) + water systems were acquired experimentally with the help of the isothermal shake-flask technique. Analysis of X-ray power diffraction revealed that difenoconazole did not exhibit any crystal transition as well as solvate formation. The solubility acquired here was accurately correlated, which yielded relative average deviations (RAD) of ≤4.99 % and a root-mean-square deviation of ≤20.59 × 10⁻⁵ through the Jouyban-Acree and modified van’t Hoff-Jouyban-Acree models Additionally, to explain the solubility behavior at a temperature of 298.15 K, this work examines the acetonitrile/acetone/DMF + water and the previously published methanol/ethanol/isopropanol/PG + water blends utilizing the extended Hildebrand solubility technique. The RAD levels remained below 6.88 %. The dipolarity-polarizability and the solubility parameter of blended solvents exert a substantial impact on the variability of difenoconazole solubility. The preferred solvation of difenoconazole at a temperature of 298.15 K was examined through the inverse Kirkwood-Buff integrals. The solvation parameters’ values of difenoconazole were positive in blends containing methanol, acetone, DMF, ethanol, isopropanol, and acetonitrile with moderate and rich compositions. This indicates that difenoconazole is preferentially solvated by them in above composition ranges. A shift from an enthalpy-driven mechanism to an entropy-driven one was revealed through an analysis of the thermodynamics of the entropy-enthalpy relationship in the dissolution of difenoconazole in blends. Furthermore, the mean local ionization energy, Hirshfeld surface as well as molecular surface electrostatic potential were employed to illustrate the microscopic electrostatic characteristics. The N and N groups in the five-membered ring of difenoconazole molecule are the primary sites for electrophilic attack. The weak contacts of difenoconazole-solvent were demonstrated with the help of a Hirshfeld partition analysis-based independent gradient model.

As the only known equation of state (EOS) with the rigid theoretical foundation, the virial equation of state (VEOS) can be reliable enough to describe real-gas imperfection for low-to-moderate densities when truncated after the second or third virial coefficient. In our previous work, on the basis of the corresponding state principle, the generalized second and third virial coefficient models were proposed for nonpolar, polar and quantum fluids in a wide temperature range. In this work, combined with the ideal heat capacities, the high-temperature performance of the truncated VEOSs was evaluated on derived thermodynamic properties including speed of sound, isobaric heat capacity, entropy and internal energy. The criterion for being “valid” is defined as 1% relative deviation from the multiparameter EOSs, and this work presents the valid density and pressure regions of the truncated VEOSs for the derived thermodynamic properties. The truncated VEOSs have valid densities of the saturated densities below the critical temperatures, and have valid densities that tend to be constant beyond the critical temperatures. The SRK EOS is chosen as the representative of generalized EOSs. By the comparisons with the SRK EOS, the truncated VEOSs show the advantage in stability and universality. The truncated VEOSs can give a reliable extrapolation with wide applicable pressure ranges at high temperatures for nonpolar, polar and quantum fluids. The applicable density regions of the truncated VEOSs for derived thermodynamic properties are recommended to be the valid density regions of the pvT property. The applicable temperature ranges of the truncated VEOSs for derived thermodynamic properties are determined by the temperature ranges of the available ideal heat capacity data.

The solubility of 2-ethoxy-1-naphthoic acid was determined experimentally in 12 pure solvents (methanol, ethanol, n-propanol, i-propanol, i-butanol, n-pentanol, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, acetone and acetonitrile) using the gravimetric method in the temperature range of 278.15 K to 323.15 K at atmospheric pressure. The study found that solubility increased with temperature, with acetone exhibiting the highest solubility and acetonitrile the lowest at 298.15 K. Furthermore, the influence of solvent properties on solubility, such as polarity and dielectric constant, was analyzed, showing a positive correlation. Mathematical models (including modified Apelblat, NRTL, Margules, UNIQUAC and λh models) were employed to analyze the dissolution process, with the modified Apelblat model providing the best fit to the experimental data. Additionally, thermodynamic properties of the dissolution process were obtained using the Van’t Hoff equation, indicating an entropy-increasing process with heat absorption. Overall, this study elucidates the solubility behavior and related mechanisms of 2-ethoxy-1-naphthoic acid in various solvents, providing theoretical support for its application in solution systems.