Measurement of the solubility of the salt of 2-mercaptobenzothiazole with cyclohexylamine and tert-butylamine in various solvents at low temperatures: Models and thermodynamic parameters

Abstract The solubility data of the salt of 2-mercaptobenzothiazole with cyclohexylamine (2-MBT-CHA) and tert-butylamine (2-MBT-TBA) in solid-liquid equilibrium, in various alternative solvents, are indispensable for a preliminary industrial application aimed at producing sustainable and renewable materials. In this paper, the solubility behavior of 2-MBT-CHA and 2-MBT-TBA, in various solvents (1,4-dioxane, methyl isobutyl ketone (MIBK), toluene and water) at low temperatures ranging from 303.15 to 348.15 K, has been studied. From the experimental data, it was found that the solubility of 2-MBT-CHA and 2-MBT-TBA increased when temperature increased. In addition, it was found that surface tension and polarity index were strongly dependent on the solubility of 2-MBT-CHA and 2-MBT-TBA. The solubility of 2-MBT-CHA and 2-MBT-TBA is in the following sequence, MIBK,4-Dioxane, toluene and water. To conclude the experimental data, thermodynamic models such as the polynomial empirical, the Van't Hoff, modified Apelblat, the semi-empirical Buchowski–Ksiazczak, the Wilson and the UNIQUAC were investigated. The Wilson model proved to be the most suitable for predicting the solubility behavior of 2-MBT-CHA and 2-MBT-TBA with temperature. Thermodynamic parameters were also investigated. Hence, it was noted that the dissolution process of 2-MBT-CHA and 2-MBT-TBA in investigated solvents is endothermic and spontaneous. The solubility of 2-MBT-CHA and 2-MBT-TBA obtained in solvents in this experiment will provide essential support for 2-MBT-CHA and 2-MBT-TBA industrial design and further theoretical studies.