Solubility determination and thermodynamic modelling for 2-amino-4-chlorobenzoic acid in eleven organic solvents from T = (278.15 to 313.15) K and mixing properties of solutions

The solubility of 2-amino-4-chlorobenzoic acid in eleven organic solvents including N-methyl-2-pyrrolidone, ethanol, n-propanol, isopropanol, ethyl benzene, toluene, n-butanol, acetonitrile, ethyl acetate, 1,4-dioxane and acetone were determined experimentally using the isothermal saturation method over a temperature range from (278.15 to 313.15) K under 101.2 kPa. Within the temperature range studied, the mole fraction solubility of 2-amino-4-chlorobenzoic acid in the solvents increased with a rise of temperature. On the whole, they obeyed the following order from high to low in the selected solvents: N-methyl-2-pyrrolidone > acetone > 1, 4-dioxane > ethyl acetate > ethanol > isopropanol > n-propanol > n-butanol > acetonitrile > toluene > ethyl benzene. The solubility values obtained for 2-amino-4-chlorobenzoic acid were correlated with the modified Apelblat equation,,lambda h equation, Wilson model and NRTL model. The largest values of root-mean-square deviation (RMSD) and relative average deviation (RAD) were 8.25 x 10(-4) and 3.35%, respectively. The modified Apelblat equation correlated the experimental solubility best on the basis of the result of AIC analysis. Furthermore, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient (gamma(infinity)(1)) and reduced excess enthalpy (H-1(E,infinity)) at infinitesimal concentration were determined. Solubility and thermodynamic studies are very important for optimizing the purification process of 2-amino-4-chlorobenzoic acid. (C) 2016 Elsevier Ltd.