Solubility of N-(4-Chlorophenyl)-2-(pyridin-4-ylcarbonyl)hydrazinecarbothioamide (Isoniazid Analogue) in Transcutol + Water Cosolvent Mixtures at (298.15 to 338.15) K

Solubility Determination and Comprehensive Analysis of the New Heat-Resistant Energetic Material TNBP

To improve the crystal quality of 4,8-bis(2,4,6-trinitrophenyl)difurazolo [3,4-b:3′,4′-e] pyrazine (TNBP), the solubility of TNBP in organic solvents (six pure and four mixed solvents) was determined by the laser monitoring technique from 293.15 to 353.15 K. The results showed that the solubility was positively correlated with the increase in the experimental temperature and the main solvent content, except for the co-solvent phenomenon in the DMSO + ethyl acetate solvent mixture. To explain the dissolution behavior of TNBP, the KAT-SER model was analyzed for pure solvent systems, and it was found that hydrogen bonding alkalinity and self-cohesiveness were the main influencing factors. The free energy of solvation and radial distribution function of TNBP in mixed solvents were also obtained by molecular dynamics simulation, and the effect of solute–solvent and solvent–solvent interactions on the solubility trend was analyzed. The experimental data were correlated using three empirical equations (van’t Hoff equation, modified Apelblat equation, and λh equation), and the deviation analysis showed the good applicability of the modified Apelblat model. Furthermore, the dissolution of TNBP was heat-absorbing and not spontaneous, according to the thermodynamic characteristics estimated by the van’t Hoff equation.

Experimental measurement - correlation of solubility and dissolution thermodynamics study of itraconazole in pure monosolvents at various temperatures

The information about the solubility and thermodynamic properties of solution is important for pharmaceutically important processes, formulation development, and further theoretical studies. In the present study, the solid-liquid equilibrium (solubility) for itraconazole (ITC) was determined experimentally in 14 monosolvents at temperatures between 293.15 K and 318.15 K under pressure of 0.1 MPa. The mole fraction solubilities were found to increase with increasing temperatures and followed inverse trend with the polarity of selected solvents. Besides, KAT-LSER analysis was performed to study the effect of solvent. The results revealed that the solute-solvent interaction (43.94%) was much higher than that of solvent-solvent interaction (16.59%). Thermodynamic based models like van't Hoff equation, modified Apelblat equation, Buchowski-Ksiazaczak equation, and polynomial empirical equation were applied to fit and correlate the experimental solubilities. Overall relative average deviation (RAD) and overall root-mean square deviation (104×RMSD) were observed to be minimum with the empirical polynomial equation and attained the values of 0.0033 and 0.0047, respectively. Furthermore, theoretical ideal solubilities, activity coefficients, and thermodynamic properties of dissolution including molar enthalpy, molar entropy, molar Gibbs free energy, and excess enthalpy were estimated. Ideal solubilities were projected considerably higher than experimental solubilities at each studied temperature. Thermodynamic properties of dissolution indicated that the dissolution was not a spontaneous process; observed to be endothermic (ΔH0soln>0) and enthalpy driven (ΔS0soln>0). Such solid-liquid equilibrium data of ITC will be of immense help in process and formulation development in pharmaceutical sciences.

Synthesis, Characterization and Solubility Determination of 6-Phenyl-pyridazin-3(2H)-one in Different Pharmaceutical Solvents

The current research work proposed the solubility data and solution thermodynamic properties of the cardiovascular agent 6-phenylpyridazin-3(2H)-one [PPD] in twelve pharmaceutical solvents at "T = 298.2 K to 318.2 K" and "p = 0.1 MPa". The measured solubilities of PPD were regressed well with "van't Hoff and Apelblat models". The solid phases of pure and equilibrated PPD were characterized using differential scanning calorimetry and powder X-ray differactometry, and the results suggested no transformation of PPD into solvates/hydrates/polymorphs after equilibrium. The solubilities of PPD in a mole fraction at "T = 318.2 K" were noted at a maximum in dimethyl sulfoxide (DMSO, 4.73 × 10^-1), followed by polyethylene glycol-400 (PEG-400, 4.12 × 10^-1), Transcutol^® (3.46 × 10^-1), ethyl acetate (EA, 81 × 10^-2), 2-butanol (2.18 × 10^-2), 1-butanol (2.11 × 10^-2), propylene glycol (PG, 1.50 × 10^-2), isopropyl alcohol (IPA, 1.44 × 10^-2), ethylene glycol (EG, 1.27 × 10^-2), ethanol (8.22 × 10^-3), methanol (5.18 × 10^-3) and water (1.26 × 10^-5). Similar tendencies were also noted at other studied temperatures. The results of the "apparent thermodynamic analysis" showed an endothermic and entropy-driven dissolution of PPD in all pharmaceutical solvents. The results of the activity coefficients suggested a maximum interaction at the molecular level in PPD-DMSO, PPD-PEG-400 and PPD-Transcutol, compared with other combination of the solute and solvents.

Thermodynamic solubility and solvation behavior of ferulic acid in different (PEG-400 + water) binary solvent mixtures

This work was carried out to determine solubility, solution thermodynamics, solvation behavior, and molecular interactions of a natural compound ferulic acid (FLA) in different '[polyethylene glycol-400 (PEG-400) + water]' binary solvent mixtures at 'T = 298.2 K to 318.2 K' and 'p = 0.1 MPa.' The mole fraction solubilities (x_e) of FLA were determined by liquid chromatographic technique using a static equilibrium technique. The obtained solubility data of FLA were regressed using 'Van't Hoff, Apelblat, Yalkowsky-Roseman and Jouyban-Acree models.' The solubility of FLA (expressed in mole fraction) was enhanced with elevation in absolute temperature in each 'PEG-400 + water' binary solvent mixture evaluated. The maximum x_e values of FLA were recorded in neat PEG-400 (1.94 × 10^-1) at 'T = 318.2 K.' While, the minimum one was obtained in neat water (4.90 × 10^-5) at 'T = 298.2 K.' The molecular interactions between FLA-PEG-400 and FLA-water were obtained by determination of activity coefficients of FLA in different 'PEG-400 + water' binary solvent mixtures. The physical data of activity coefficients recorded in this work suggested strong molecular interactions in FLA-PEG-400 in comparison with FLA-water. 'Apparent thermodynamic analysis' suggested an 'endothermic and entropy-driven dissolution' of FLA in each 'PEG-400 + water' binary solvent mixture investigated.

Solubility and molecular interactions of ferulic acid in various (isopropanol + water) mixtures

OBJECTIVE

The solubility of an herbal compound ferulic acid (FA) in various (isopropanol (IPA) + water) mixtures was measured and correlated at temperatures 'T = 298.2 K to 318.2 K' and pressure 'p = 0.1 MPa'.

METHODS

The experimental solubilities of FA in mole fraction were determined using a static equilibrium method and correlated with 'Apelblat, Van't Hoff, Yalkowsky and Jouyban-Acree models'.

KEY FINDINGS

The maximum mole fraction solubilities of FA were obtained in neat IPA (2.58 × 10^-2 at T = 318.2 K) followed by minimum in neat water (4.87 × 10^-5 at T = 298.2 K). The activity coefficients of FA in various (IPA + water) mixtures were determined to evaluate the molecular interactions between FA and co solvent mixtures. Strong molecular interactions were seen between FA and neat IPA in comparison with FA and neat water. 'Apparent thermodynamic analysis' indicated an 'endothermic and entropy-driven dissolution' of FA in all (IPA + water) mixtures evaluated.

CONCLUSIONS

Isopropanol was investigated as a good cosolvent in the solubility enhancement of FA in water; therefore, it could be used as solubilizer in solubility enhancement and formulation development of FA.