Solid–Liquid Equilibrium for Binary Systems Containing Carboxylic Acids and Acetic Anhydride Obtained by Differential Scanning Calorimetry

In the present study, the solid–liquid phase diagrams of four systems acetic acid + acetic anhydride, propionic acid + acetic anhydride, butyric acid + acetic anhydride, and pentanoic acid + acetic anhydride were determined by differential scanning calorimetry at atmospheric pressure. The experimental results illustrated that these systems showed a eutectic behavior. The experimental data were compared with predicted data acquired by solving the phase equilibrium equations using an algorithm. The liquid-phase activity coefficients were calculated by the Wilson and nonrandom two-liquid activity coefficient models. The results show that the approaches used for the calculated system equilibrium was capable to accurately describe the eutectic solid–liquid phase diagrams of the above-mentioned systems.