Solid-Liquid Equilibria of Benzoic Acid Derivatives in 1-Octanol*

The solid-liquid equilibrium of benzoic acid derivatives in 1-octanol was first determined in this article. Using a laser monitoring observation technique, the solubility data of 0-amino-benzoic acid, p-amino-benzoic acid, 0-chloro-benzoic acid, and m-nitro-benzoic acid in 1-octanol were measured by the polythermal method in the temperature range of 20–50°C. The experimental data were regressed with the Wilson equation and the λH equation. The experimental results showed that the solubility of the four chemicals in 1-octanol increased significantly with temperature. The results indicate that the molecular structure and interactions affect the solubility significantly. The solubility order of the benzoic acid derivatives is as follows: m-nitro-benzoic acid > 0-chloro-benzoic acid > 0-amino-benzoic acid > p-amino-benzoic acid. Both the Wilson equation and λH equation are in good agreement with the experimental data.