Solid-Liquid Phase Equilibrium of Nicotinamide in Different Pure Solvents: Measurements and Thermodynamic Modeling

The solubility of nicotinamide in water, methanol, ethanol, 2-propanol, n-butanol, and ethyl acetate at temperatures ranging from 288.15 K to 318.15 K was measured via a static gravimetric analytic method, and the melting temperature and fusion enthalpy of nicotinamide were obtained using differential scanning calorimetry. The experimental solubility data were correlated by the modified Apelblat equation, the van't Hoff equation, the lambda h (Buchowski) equation, and the Wilson model; the van't Hoff equation shows the best agreement. Furthermore, the dissolution enthalpy and dissolution entropy of nicotinamide in the corresponding solvents were predicted.