Solubility Measurement of Tiopronin in Four Mixed Solvents at 273.15-318.15 K and Correlation Using Thermodynamic Models

The solubility data of tiopronin in four binary mixtures in the temperature range from 273.15 to 318.15 K were obtained using the isothermal saturation method under 101.3 kPa. In mixtures of 1-butanol + toluene and 1-butanol + acetonitrile, the mole solubility data increased monotonically with the increasing mass fraction of 1-butanol at a certain temperature. In addition, it increased to the maximum and then decreased with the increasing mass fraction of i-butanol in systems of i-butanol + toluene and i-butanol + acetonitrile. The maximum values in mixtures of 1-butanol + toluene and 1-butanol + acetonitrile were all obtained in pure 1-butanol (0.103 at 318.15 K), while these data in systems of i-butanol + toluene and i-butanol + acetonitrile were 4.644 x 10(-2) and 5.243 x 10(-2) at 318.15 K, respectively. The solubility data were correlated using the Jouyban-Acree model and CNIBS/R-K model. The maximum relative average deviation value was no more than 5%. In addition, the square of the linear correlation coefficient between experimental and calculated values is closer to 1. Therefore, the Jouyban-Acree model is suitable to correlate the solubility values of tiopronin in selected binary mixtures at studied temperatures. The solubility data and model parameters were important for the preparation and purification of tiopronin.