Measurement and correlation of the solubility of 3-methoxybenzoic acid in fourteen mono-solvents at temperatures from 278.15 K to 323.15 K

Abstract

A gravimetric method was used to determine the equilibrium solubility of 3-methoxybenzoic acid (3MBA) in 14 kinds of organic mono-solvents (methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, formic acid, acetic acid, ethyl formate, methyl acetate, ethyl acetate, iso-propyl acetate, butyl acetate) from 278.15 K to 323.15 K at 0.1 MPa. In all the solvent systems studied, the solubility increases monotonously with the increasing of temperature. In addition, the effect of solvent properties on solid–liquid equilibrium of 3MBA was investigated. The results show that dissolving process of 3MBA in solvent is a complex process, which is affected by the action of solvent properties; Correlation analysis found that the solvent properties containing hydrogen bond donation (α), hydrogen bond acceptance (β), polarity index (ET30), Hildebrand solubility parameter (δH), cohesive energy density and surface tension process great influence on the dissolving behavior of 3MBA. And then, topological index (H) which can reflect the molecular structure information of the solvents was calculated. It was found that the solubility of 3MBA decreased with the increasing of H values in alcohol and ester solvents, and increased with the increasing of H values in carboxylic acid solvents. Besides, the solubility of 3MBA were related to the modified Apelblat model, λh model, van’t Hoff model and NRTL model, and the modified Apelblat model gave the best correlation results, with the ARD% of 0.68%. In addition, COSMO-RS model was used to calculate the σ-profiles and solvation free energy of selected solute–solvent systems, σ-profiles analysis was qualitatively described the intermolecular interaction, it was found that the solubility of 3MBA in the selected solvents was correlated with the solute–solvent intermolecular interactions; Solvation free energy was calculated in the “Molar” framework and found that the solubility of 3MBA in alcohols, esters and carboxylic acids decreased with the decreasing of the absolute value of the solvation free energy.