Solubility and Thermodynamic Functions of Isatin in Pure Solvents

The solubility of isatin in eight pure solvents including dichloromethane, toluene, acetone, ethyl acetate, 1,4-dioxane, N,N-dimethylformamide, tetrahydrofuran, and acetonitrile were determined from (278.15 to 333.15) K at atmospheric pressure using the synthetic method. The solubility was determined by a laser monitoring observation technique and found to increase with the rise of temperature. The experimental solubilities were correlated by four models including the ideal solution model, the modified Apelblat equation, λh (Buchowski) equation, and Wilson models with the overall average percentage deviations less than 0.52% in all cases. Thermodynamic functions of the solution of isatin in these solvents including apparent standard enthalpy and entropy of solution were obtained by van’t Hoff plot, and the apparent standard Gibbs energy change of solution was also calculated.