Abstract
The aim of the present investigation was to measure and correlate the solubility of N-(4-chlorophenyl)-2-(pyridin-4-ylcarbonyl)hydrazinecarbothioamide [isoniazid (INH) analogue] in five different pure solvents, namely, ethanol, ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), and isopropyl alcohol (IPA) at (298.15 to 338.15) K using the shake flask method. The experimental solubilities of INH analogue were regressed with Apelblat equation with root-mean-square deviations in the range of (0.22 to 4.42) %. The correlation coefficients were observed in the range of 0.996 to 0.999, indicating good fitting of experimental data. The solubility of INH analogue was found to increase with an increase in temperature in each solvent investigated. The mole fraction solubility of INH analogue was found to be highest in PEG-400 (1.08 × 10–1 at 298.15 K) followed by EG (7.70 × 10–3 at 298.15 K), PG (7.38 × 10–3 at 298.15 K), IPA (1.13 × 10–3 at 298.15 K), and ethanol (6.47 × 10–4 at 298.15 K). Dissolution thermodynamic studies indicated nonspontaneous and endothermic dissolution of INH analogue in each solvent investigated. Based on these results, INH analogue has been considered as freely soluble in PEG-400, soluble in IPA, EG, and PG, and slightly soluble in ethanol. The solubility data of this study could be useful in crystallization/purification and formulation development of INH analogue.