Thermodynamic Study of the Solubility of Naproxen in Some 2-Propanol + Water Mixtures

The equilibrium solubilities of the anti-inflammatory drug naproxen (NPX) in 2-propanol + water mixtures were determined at several temperatures from 298.15 to 313.15 K. The Gibbs energy, enthalpy, and entropy of solution and of mixing were obtained from these solubility data. The solubility was maximal in φ1 = 0.90 and very low in pure water at all the temperatures studied. A non-linear plot of ∆solnH° vs. ∆solnG° with negative slope from pure water up to 0.20 in volume fraction of 2-propanol and positive beyond this composition up pure 2-propanol was obtained at the mean temperature, 305.55 K. Accordingly, the driving mechanism for NPX solubility in the water-rich mixtures was the entropy, probably due to water-structure loss around non-polar moieties of the drug and for the 2-propanol-rich mixtures it was the enthalpy, probably due to its better solvation of the drug

Ketoprofen Solubility in Organic Solvents and Aqueous Co-solvent Systems: Interactions and Thermodynamic Parameters of Solvation

Ketoprofen (KET) solubility was determined in fifteen pure solvents and aqueous-cosolvent mixtures systems. The results obtained and the parameterized values solvents allowed us to observe the influence of the latter on the solubility of KET. The experimental data obtained indicates that the * parameter, which accounts for the polarity/polarizability of the solvent, and the Hildebrand's solubility parameter, which depicts the cohesive forces of the solvent ,has the greatest influence on the solubility of KET. In all the analyzed cosolvent mixtures, the solute was preferentially solvated by the organic cosolvent. This indicates that with a decreasing polarity of the solvent, solvent-solvent interactions decrease, favoring the solute-solvent interactions. For aqueous binary mixtures of ethanol, ethylene glycol and propylene glycol, the apparent enthalpy, entropy and Gibbs free energy changes involved in the solvation process were determined.Fil: Filippa, Mauricio Andres. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; ArgentinaFil: Melo, Gisela Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto Multidisciplinario de Investigaciones Biológicas de San Luis; ArgentinaFil: Gasull, Estela Isabel. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Departamento de Química; Argentin

Equations for the Correlation and Prediction of Partition Coefcients of Neutral Molecules and Ionic Species in the Water-Isopropanol Solvent System

We use literature data on solubilities of 46 compounds in the water-isopropanol (IPA) system to obtain the corresponding partition coefficients, P, for transfer from water to water- IPA mixtures. We have then used our previously constructed linear free energy equation to obtain equations that correlate log10 P at water-IPA intervals across the entire water-IPA system. These equations can then be used to predict partition coefficients and solubilities of further compounds in the water-IPA systems at 298 K. The coefficients in our linear free energy equation encode information on the physicochemical properties of the water- IPA mixtures. We show that the hydrogen bond basicity of the water-IPA mixtures only increases slightly from water to IPA, but that the hydrogen bond acidity of the mixtures decreases markedly from water to IPA in a smooth continuous manner. We have also used data on ions and on ionic species to set out equations for the estimation of their partition coefficients from water to water-IPA mixtures. We find that for partition from water to IPA itself, log10 P = − 1.81 for H+

Solubility and decomposition of organic compounds in subcritical water

In this article, studies on organic solubility and stability in subcritical water reported during the past 25 years have been reviewed. Data on the solubility and decomposition of organic compounds in subcritical water, a green solvent, are needed in environmental remediation, chemistry, chemical engineering, medicine, polymer, food, agriculture, and many other fields. For solubility studies, the experimental systems used to measure solubility, mathematical equations derived and applied for the modeling of the experimentally determined solubility data, and the correlation between the predicated and experimental data have been summarized and discussed. This paper also reviewed organic decomposition under subcritical water conditions. In general, the solubility of organics is significantly enhanced with increasing water temperature. Likewise, the percentage of organic decomposition also increases with higher temperature

Solubility of pharmaceuticals: A comparison between SciPharma, a PC-SAFT-based approach, and NRTL-SAC

The solubility of seven pharmaceutical compounds (paracetamol, benzoic acid, 4-aminobenzoic acid, salicylic acid, ibuprofen, naproxen and temazepam) in pure and mixed solvents as a function of temperature is calculated with SciPharma, a semi-empirical approach based on PC-SAFT, and the NRTL-SAC model. To conduct a fair comparison between the approaches, the parameters of the compounds were regressed against the same solubility data, chosen to account for hydrophilic, polar and hydrophobic interactions. Only these solubility data were used by both models for predicting solubility in other pure and mixed solvents for which experimental data were available for comparison. A total of 386 pure solvent data points were used for the comparison comprising one or more temperatures per solvent. SciPharma is found to be more accurate than NRTL-SAC on the pure solvent data used especially in the description of the temperature dependence. This is due to the appropriate parameterization of the pharmaceuticals and the temperature-dependent description of the activity coefficient in PC-SAFT. The solubility in mixed solvents is predicted satisfactorily with SciPharma. NRTL-SAC tends to overestimate the solubility in aqueous solutions of alcohols or shows invariable solubility with composition in other cases

Measurement and correlation of the solubility of telmisartan (form A) in nine different solvents from 277.85 to 338.35 K

The solubility of telmisartan (form A) in nine organic solvents (chloroform, dichloromethane, ethanol, toluene, benzene, 2-propanol, ethyl acetate, methanol and acetone) was determined by a laser monitoring technique at temperatures from 277.85 to 338.35 K. The solubility of telmisartan (form A) in all of the nine solvents increased with temperature as did the rates at which the solubility increased except in chloroform and dichloromethane. The mole fraction solubility in chloroform is higher than that in dichloromethane, which are both one order of magnitude higher than those in the other seven solvents at the experimental temperatures. The solubility data were correlated with the modified Apelblat equation and λh equations. The results show that the λh equation is in better agreement with the experimental data than the Apelblat equation. The relative root mean square deviations (σ) of the λh equation are in the range from 0.004 to 0.45 %. The dissolution enthalpies, entropies and Gibbs energies of telmisartan in these solvents were estimated by the Van’t Hoff equation and the Gibbs equation. The melting point and the fusion enthalpy of telmisartan were determined by differential scanning calorimetry

Solubility, Correlation, Dissolution Thermodynamics and Preferential Solvation of Meloxicam in Aqueous Mixtures of 2-Propanol

Article studying solid-liquid equilibrium of meloxicam in {2-propanol + water} mixtures at several temperatures as a contribution to preformulation studies of homogeneous liquid pharmaceutical dosage forms based on this drug

Solution thermodynamics and preferential solvation of 3-chloro-N-phenyl-phthalimide in acetone + methanol mixtures

The thermodynamic properties of the 3-chloro-N-phenyl-phthalimide in acetone + methanol cosolvent mixtures were obtained from solubility data report in literature. The solubility was higher in near acetone and lower in pure methanol at all temperatures studied. A non-linear plot of ∆solnH° vs. ∆solnG° shows a negative slope from pure acetone up to x1 = 0.691. Beyond this composition, a variable positive slope is obtained with the exception of mixtures with x1 = 0.121, x1 = 0.272 and x1 = 0.356 which is a not common trend in these systems. The preferential solvation of 3-chloro-N-phenyl-phthalimide by the components of the solvents was estimated by means of the inverse Kirkwood–Buff integral method, showing the 3-chloro-Nphenyl-phthalimide is preferential solvated by methanol in more polar mixtures and by acetone in less polar ones.Las propiedades termodinámicas de 3-cloro-N-fenil-ftalimida en mezclas cosolventes acetona + metanol fueron obtenidas a partir de los datos de solubilidad reportados en la literatura. La mayor solubilidad se presentó en acetona y la menor en metanol puro en todas las temperaturas estudiadas. La grafica ΔsolnH° vs. ΔsolnG° presenta una tendencia no lineal, con una pendiente negativa desde la acetona pura hasta x1 = 0,691 a partir de esta composición hasta el metanol puro se obtiene una pendiente positiva variable con la excepción de las mezclas con x1 = 0,121, x1 = 0,272 y x1 = 0,356, la cual es una tendencia poco común en estos sistemas. La solvatación preferencial de 3-cloro-N-fenil-ftalimida por cada uno de los solventes de la mezcla se estimó por medio del método de las integrales inversas de Kirkwood-Buff mostrando que la 3-cloro-N-fenil-ftalimida se solvata preferencialmente por metanol en las mezclas más polares y por acetona en las menos polares

Thermodynamics of mixing of the -adrenergic blocker propranolol-hcl in ethanol + water mixtures

Thermodynamic functions Gibbs energy, enthalpy, and entropy of mixing of propranolol hydrochloride in ethanol + water mixtures were evaluated. Mixing quantities were calculated based on fusion calorimetric values obtained from differential scanning calorimetry measurements and equilibrium solubility values reported in the literature for this drug in these cosolvent mixtures. By means of enthalpy-entropy compensation analysis, a non-linear ∆ mix H° vs. ∆ G° plot was obtained indicating different mechanisms involved in the dissolution and mixing of this drug according to mixtures composition. Nevertheless, the molecular and ionic events involved in the dissolution of this drug in this cosolvent system are unclear

Preferential Solvation of the Antioxidant Agent Daidzein in some Aqueous Co-Solvent Mixtures according to IKBI and QLQC Methods

The preferential solvation parameters by ethanol (EtOH) or propylene glycol (PG) of daidzein were derived from their solution thermodynamic properties by means of the inverse Kirkwood-Buff integrals and the quasi-lattice-quasi-chemical (QLQC) methods. According to IKBI method, the preferential solvation parameter by the co-solvent, δx1,3, is negative in water-rich mixtures but positive in co-solvent-rich mixtures in both kinds of systems. This could demonstrate the relevant role of hydrophobic hydration around the aromatic rings in the drug solvation in water-rich mixtures. Furthermore, the more solvation by co-solvent in co-solvent-rich mixtures could be due mainly to polarity effects and acidic behavior of the hydroxyl groups of the compound in front to the more basic solvents present in the mixtures, i.e. EtOH or PG. Otherwise, according to QLQC method, this drug is preferentially solvated by the co-solvents in all the mixtures in both kind of systems