Measurement of Solubility of Thiamine Hydrochloride Hemihydrate in Three Binary Solvents and Mixing Properties of Solutions

Data on (solid + liquid) equilibrium of thiamine hydrochloride hemihydrate (HH) in {water + (ethanol, acetone, or 2-propanol)} solvents will provide essential support for industrial design and further theoretical studies. In this study the solid–liquid equilibrium (SLE) was experimentally measured over temperatures ranging from 278.15 to 313.15 K under atmospheric pressure by a dynamic method. For the temperature range investigated, the equilibrium solubility of thiamine hydrochloride hemihydrate (HH) varies with temperature and the composition of the solvents. The experimental solubility was regressed with different models including the modified Apelblat equation, λh equation, as well as NRTL equation. All the models gave good agreements with the experimental results. On the basis of the solubility data of HH, the thermodynamic properties of mixing process of HH with mixed solvents were also discussed. The results indicate that the mixing process of HH is exothermic. Besides, the model outwardly like the Arrhenius equation was employed to quantitatively exhibit the relationship between solubility and solvents mixtures polarity of solvents mixtures.