2-Methoxy-4-nitroaniline Solubility in Several Monosolvents: Measurement, Correlation, and Solvent Effect Analysis

Abstract

The 2-methoxy-4-nitroaniline solubilities in some monosolvents of n-propanol, methanol, ethyl acetate, ethanol, isopropanol, acetonitrile, ethylene glycol (EG), n-butanol, water, dimethyl sulfoxide (DMSO), 1,4-dioxane, and N-methylpyrrolidone (NMP) were reported. Experiments were made via a shake-flask technique within the temperature range of 278.15 to 323.15 K under local atmospheric pressure (101.2 kPa). The change trend of the solubility magnitude in different monosolvents from high to low was as follows: NMP > DMSO > 1,4-dioxane > ethyl acetate > acetonitrile > ethanol > methanol > n-propanol > isopropanol > EG > n-butanol > water. Analysis of X-ray powder diffraction scans indicated that polymorphic transformation or solvate formation did not happen in the selected monosolvents. Mathematical description of the determined solubility was carried out through the common Wilson model, Apelblat equation, NRTL model, and λh equation. The acquired values of maximum relative average deviation and root-mean-square deviation were 5.99% and 23.66 × 10–4, respectively. The correlating results were better with the Apelblat equation than with the other models. The interactions between the solute–solvent molecules and solvent–solvent molecules were examined by the use of the method of linear solvation energy relationships. Moreover, the mixing thermodynamic properties, activity coefficient under infinitesimal concentration, and reduced excess enthalpy were attained by using the Wilson model.