Equilibrium Solubility of p-Nitroacetanilide in Fifteen Neat Solvents: Determination, Correlation, and Solvent Effect

p-Nitroacetanilide solubility in fifteen neat solvents (N,N-dimethylformamide, ethylene glycol, acetonitrile, methanol, ethyl acetate, n-propanol, ethanol, 1,4-dioxane, isopropanol, water, n-butanol, isobutanol, cyclohexane, n-heptanol, and N-methyl pyrrolidone) was reported. Experiments were done using the shake-flask technique under 101.2 kPa at temperatures ranging from 278.15 to 323.15 K. The solubility magnitudes in the selected 15 neat solvents followed a decreasing trend as N-methyl pyrrolidone (N,N-dimethylformamide) > 1,4-dioxane > ethyl acetate > n-heptanol > acetonitrile > n-butanol > n-propanol > ethanol > isopropanol > methanol > isobutanol > ethylene glycol > water > cyclohexane. Polymorphic transformation and solvation did not happen in the 15 solvents in the equilibration process. Mathematical correlations of equilibrium solubility were studied using activity coefficient models (NRTL and Wilson), semi-empirical equations (lambda h equation and Apelblat equation), and a simple multiple linear regression model. The maximum values of root-mean-square deviation and relative average deviation between the experimental solubility data and back-calculated ones were 59.45 x 10(-4) and 3.47%, respectively. The Apelblat model presented a better correlation result than the other models. An inspection of the interactions between the solvent-solvent and solute-solvent molecules was carried out through the linear solvation energy relationships. Moreover, the dissolution thermodynamic properties, reduced excess enthalpy, and infinite dilution activity coefficient were achieved through the Wilson model.

Automated summary

The solubility of p-nitroacetanilide in fifteen neat solvents was reported, showing decreasing trends in solubility magnitude. Different models were used to study the equilibrium solubility, with the Apelblat model showing the best correlation result. Interactions between solvent-solvent and solute-solvent molecules were examined through linear solvation energy relationships. Additionally, dissolution thermodynamic properties were analyzed using the Wilson model.