Solubility Data, Modeling, and Solvent Effect of 8-Isoquinolinamine in Four Mixed Solvents and Ten Monosolvents from 278.15 to 323.15 K

Abstract

The equilibrium solubility of 8-isoquinolinamine in methanol, ethanol, n-propanol, isopropanol, N,N-dimethylformamide (DMF), acetonitrile, acetone, propylene glycol (PG), ethylene glycol (EG), and water, and aqueous mixtures of methanol/ethanol/n-propanol/isopropanol plus water was experimentally measured by the isothermal saturation method at 278.15–323.15 K under 101.2 kPa. The mole fractions of 8-isoquinolinamine in monosolvents were obtained to be maximum in neat DMF. For the four binary mixed solvent systems, the amount of 8-isoquinolinamine dissolved in n-propanol + water is more than that in the other three systems. The mole fractions of 8-isoquinolinamine in pure solvents were correlated using the Apelblat model, van’t Hoff model, and Wilson model, and the calculated value of the Apelblat model was the closest to the experimental value. The Jouyban–Acree model, modified Apelblat–Jouyban–Acree model, and van’t Hoff–Jouyban–Acree model were applied to calculate the solubility of 8-isoquinolinamine in the four solvent mixtures. The feedback obtained by comparing the experimental data with the calculated data is that the calculated data from the Jouyban–Acree model was relatively close to the experimental results. Solvent effects as a powerful tool can be used to estimate interactions at the molecular level, and the results showed that solvent–solvent intermolecular interactions contribute to dissolution. van’t Hoff plots are adopted as a method to show the relationship between ln(x) and 1/T.