Solubility and thermodynamic/solvation behavior of 6-phenyl-4,5-dihydropyridazin-3(2H)-one in different (Transcutol + water) mixtures

Pyridazinone derivatives are useful cardiovascular drugs which suffer from weak aqueous solubility and toxicity problems. Hence, in this work, the solubility of pyridazinone derivative i.e. 6-phenyl-4,5-dihydropyridazin-3(2H)-one (PDP-6) was measured in various “2-(2-ethoxyethoxy)ethanol (Transcutol®) + water” mixtures at temperatures “T = 293.2 K to 313.2 K and pressure “p = 0.1 MPa”. The experimental solubilities of PDP-6 were correlated with “Apelblat, Van't Hoff and Yalkowsky models” in terms of mean percent deviations and coefficient of determination. The highest solubilities of PDP-6 as mole fraction were obtained in pure Transcutol (5.27 × 10− 1 at T = 313.2 K). However, the lowest one was obtained in pure water (7.45 × 10− 7 at T = 293.2 K). “Apparent thermodynamic analysis” of solubilities of PDP-6 as mole fraction indicated an “endothermic dissolution” of PDP-6 in all “Transcutol + water” mixtures due to its positive values. “Enthalpy-entropy compensation” analysis indicated that the solvation of PDP-6 was “enthalpy-driven” in all “Transcutol + water” mixtures evaluated. Based on the results of the current study, PDP-6 has been proposed as practically insoluble in water and very soluble in Transcutol at T = 298.2 K.