Solubility, Hansen solubility parameter and thermodynamic properties of etodolac in twelve organic pure solvents at different temperatures

Abstract

In this article, the solubility of etodolac in n-propanol, n-butanol, isopropanol, isobutanol, methyl acetate, n-butyl acetate, n-amyl acetate, isobutyl acetate, isoamyl acetate, toluene, acetone at 278.15 K–323.15 K and dichloromethane at 278.15 K–303.15 K under the pressure of 0.1 MPa was studied using a laser monitoring technology. The experimental results show that the solubility of etodolac in all the 12 pure solvents is positively correlated with the temperature. The van't Hoff model, Apelblat model, λh model, NRTL model and UNIQUAC model were used to fit the etodolac solubility data. Through comparison, it was found that the Apelblat model has the smallest average values of ARD (average relative deviation) and RMSD (root-mean square deviation), and the average values of ARD% and 104 RMSD were 0.92% and 5.99, respectively. The result shows that the Apelblat model was more suitable for correlating the solubility data. The order of solubility of etodolac was analyzed by using Hansen solubility parameter, and the solvent effect was studied by calculating the KAT-LSER parameter. Besides, the thermodynamic properties of the solution process of etodolac were calculated and analyzed by the van't Hoff analysis. The results show that the dissolution process of etodolac is endothermic and entropy-driven.