ABSTRACT The dielectric behaviour of n-hexanol + N,N-dimethylformamide binary mixtures was investigated at 313.15 K over the frequency range 20 Hz–2 MHz using dielectric spectroscopy. The complex permittivity, electric modulus, AC conductivity, and impedance formalisms were analysed to understand relaxation dynamics and charge transport mechanisms. The results reveal pronounced dipolar relaxation and significant electrode polarisation effects, indicating strong intermolecular interactions. Linear and mutual correlation factors, excess Helmholtz free energy, and excess molar polarisation were evaluated to probe molecular association. The analysis confirms dominant hydrogen bonding and dipole–dipole interactions between unlike molecules, along with contributions from long-range dipolar correlations and short-range self-association. The static dielectric constant was theoretically estimated using Luzar’s hydrogen bonding model to determine binding energy and enthalpy of association. Additionally, various dielectric mixing rules were assessed through average percentage deviation analysis. The study provides detailed insight into molecular organisation and interaction mechanisms in alcohol–amide solvent systems.

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy of activation of viscous flow for binary mixtures of 2-nitroanisole with selected alkanolamines, namely, 2-(dimethylamino)ethanol (DMEA), N-methyl ethanolamine (N-MEA), and monoethanolamine (MEA) components selected compositions were determined from the measured values of densities (ρ), viscosities (η), and speeds of sound (u) of pure components and their mixtures from 303.15 K to 313.15 K. The results are analysed in terms of intermolecular interactions or hydrogen bonding interactions or hetero-association interactions in the binary mixtures. Jouyban-Acree model, results are discussed in terms of mean relative deviation (MRD) and individual relative deviation (IRD) between calculated and experimental densities, speeds of sound and viscosities as an accuracy criterion

ABSTRACT Densities (ρ) and speed of sound (c) for the four binary liquid mixtures of ethyl lactate (EL) with 1-propanol, 1-butanol, 1-pentanol and 1-hexanol were measured at different temperatures at (303.15 to 323.15) K, with an Anton Paar density and sound velocity analyser. Measured thermophysical properties increased with an increase in the mole fraction of EL and decreased with and increase in temperature. Furthermore, thermodynamics properties such as excess volume (V E ), isentropic compressibility (k s ) and excess isentropic compressibility k s E have been calculated using the measured data and fitted into the Redlich-Kister polynomial equation to confirm the accuracy of measured data. In addition, the variation in excess thermodynamic properties with composition and temperature have been discussed in terms of molecular interactions between component molecules in liquid mixtures.

ABSTRACT This study explores the physicochemical properties of binary mixtures of 1,3-propanediol with deep eutectic solvents (DESs) formed from quaternary ammonium salts – tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride (TBAC), and tetraethylammonium chloride (TEAC) – as hydrogen bond acceptors (HBAs) and 3-amino-1-propanol as the hydrogen bond donor (HBD) in a 1:8 molar ratio. Measurements of density, speed of sound, and viscosity were conducted at 303.15, 308.15, and 313.15 K over the full composition range. From these data, volumetric properties, deviation in isentropic compressibility, viscometric parameters, and excess Gibbs free energy of activation were derived. Negative V E and Δκs values indicate strong molecular packing and attractive interactions, while positive ∆G *E values reflect greater resistance to flow. Overall, the results highlight notable intermolecular interactions and provide useful insights into the thermodynamic behaviour of 1,3-propanediol–DES systems for potential applications as green solvents and in chemical processing.

ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy of activation of viscous flow for binary mixtures of 2-nitroanisole with selected alkanolamines, namely, 2-(dimethylamino)ethanol (DMEA), N-methyl ethanolamine (N-MEA) and monoethanolamine (MEA) components selected compositions were determined from the measured values of densities (ρ), viscosities (η) and speeds of sound (u) of pure components and their mixtures from 303.15 K to 313.15 K. The results are analysed in terms of intermolecular interactions or hydrogen bonding interactions or hetero-association interactions in the binary mixtures. Jouyban–Acree model results are discussed in terms of mean relative deviation (MRD) and individual relative deviation (IRD) between calculated and experimental densities, speeds of sound and viscosities as an accuracy criterion.

ABSTRACT The experimental solubility data of theophylline in three hydro-alcoholic solvent mixtures at various temperatures were re-analysed concerning practical needs in the pharmaceutical industry. The minimum number of known solubility data in the binary solvents was used as a training data set and the rest of data were predicted using the trained models. In addition, the data was predicted using a previously trained model employing Abraham parameters and the experimental solubility of the drug in the mono-solvents as input values. The accuracy of the provided prediction tools was satisfactory. The results were also compared with those of the models reported in an earlier paper. Moreover, by means of the Gibbs and van’t Hoff equations apparent thermodynamic functions of dissolution were calculated observing positive quantities in all cases indicating endothermic and entropy-driven processes.

ABSTRACT To better understand edaravone (EDA), its solubility behaviour in water-alcohol mixtures (methanol (MeOH), and ethanol (EtOH)) at various temperatures (293.15–323.15 K) was studied. Moreover, it was revealed that the dissolution of EDA is an endothermic process mainly induced by enthalpy changes, where these contributions (over 76%) are common in all solvent systems. The negative Gibbs free energy of transfer values indicates that EDA has a higher thermodynamic affinity for alcohol – water mixtures than for pure water, which is consistent with the increase of its solubility in co-solvent media. According to the inverse Kirkwood – Buff integrals (IKBI) method of preferential solvation, EDA is selectively solvated by alcohol molecules, with the degree of solvation decreasing in the order EtOH > MeOH. The maximal preferential solvation was found in the medium region of alcohol mole fraction (x 1 = 0.30–0.40), where solvation occurs due to alcohol molecules replacing water molecules at the non-polar part of EDA.

ABSTRACT The present study investigated the solubility of paracetamol (PARA) in mixtures of N-methyl-2-pyrrolidone (NMP) and water over the temperature range of 293.2–313.2 K using the shaking flask method. The experimental data were employed to determine thermodynamic parameters governing PARA dissolution. To assess the predictive capability, several mathematical models, including van’t Hoff, Yalkowsky, CNIBS/R–K, Jouyban–Acree and Jouyban–Acree–van’t Hoff models, were applied. Results showed that PARA exhibited the highest solubility in pure NMP at all studied temperatures. Thermodynamic analysis indicated that the dissolution process was endothermic and driven by entropy across in all solvent compositions. Evaluation of predictive accuracy using mean relative deviations (MRDs%) demonstrated that the van’t Hoff model provided the highest accuracy (1.5%), while the Yalkowsky model showed the least accuracy (45.0%). The CNIBS/R–K, λh, Jouyban–Acree, and Jouyban–Acree–van’t Hoff models yielded MRDs of 2.5%, 3.0, 3.5%, and 2.9%, respectively, confirming the suitability of multi-parameter approaches.

ABSTRACT A systematic investigation was undertaken to determine the thermodynamic properties of two binary mixtures comprising a deep eutectic solvent, (DES) specifically choline chloride/p-cresol at 1:2 molar ratio, with two distinct co-solvents: 2-ethyl-1-hexanol and 2-methyl-2,4-pentanediol. Density and viscosity were measured between 303.15 K to 313.15 K. Volumetric characteristics, including excess molar volume (V E ) excess partial molar volumes, excess viscosity parameters like Δη and lnη E were computed. The study shows effect of temperature, co-solvent identity, DES composition and the implications of considering the DES as a mixture of its constituents. Analysis indicates molecular packing effects and hydrogen bonding interactions between the DES and the alcohol solvents contribution to volume contraction. The excess viscosity data underscored the significant role of hydrogen bonding in observed variations. The Jouyban-Acree model was applied for correlation which was assessed using the mean and individual relative deviation. The experimental data reliability was further substantiated through FTIR spectroscopic analysis.

ABSTRACT In the present study, we investigate the phase diagram of silicon within the framework of SNAP machine learning potential model. We show that the melting line of diamond phase of silicon is a linear function of pressure, which is in good agreement with experimental data. At the same time, the melting temperature is strongly underestimated. Also, this model fails to predict the high-pressure phases of silicon.