Equilibrium Solubility, Modeling, and Extended Hildebrand Solubility Parameter Approach Analysis of 3-Amino-6-bromopyridazine in Four Cosolvent Blends and Ten Pure Solvents at T = 278.15 to 323.15 K

Abstract

The mole fraction of 3-amino-6-bromopyridazine in methanol, ethanol, n-propanol, isopropanol, n-butanol, acetone, toluene, propylene glycol (PG), N,Ndimethylformamide (DMF), and water and methanol/ethanol//PG/DMF + water was experimentally measured by the isothermal saturation method from 278.15 to 323.15 K under 101.2 kPa. The solubility range of 3-amino-6-bromopyridazine is from 2.574 × 10 −5 (water, 278.15 K) to 2.415 × 10 −2 (DMF, 323.15 K). Accordingly, under the given conditions, the mixing of DMF and water is superior to other combinations in terms of dissolution. The solubility of 3-amino-6-bromopyridazine in mono-solvents was correlated with Apelblat, van't Hoff, and λh models. Jouyban−Acree (J-A), modified Apelblat−Jouyban−Acree (A-J-A), and van't Hoff−Jouyban−Acree (V-J-A) models were applied to calculate the solubility of 3-amino-6-bromopyridazine in four solvent mixtures. In terms of thermodynamic properties, the fusion enthalpy (Δ fus H = 37.01 kJ mol −1 ) and melting point (T m = 472.15 K) of 3-amino-6-bromopyridazine are obtained by a differential scanning calorimeter. The interaction between the solute and solvent molecules as well as the interaction generated inside the above molecules could be analyzed through the calculation of the extended Hildebrand solubility parameter approach. The results showed that hydrophobic action of intramolecular groups and self-association of solute and solvent occurred in different concentration ranges.