In this work, we present a comprehensive study of the thermodynamic properties of 3-and 4-ethoxyacetanilides. The heat capacities in crystalline, liquid, and supercooled liquid states from 80 to 475 K were obtained using adiabatic, differential scanning (DSC), and fast scanning (FSC) calorimetries. The fusion enthalpies at T_m were combined from DSC measurement results and the literature data. The fusion enthalpies at 298.15 K were evaluated in two independent ways: adjusted according to Kirchhoff’s law of thermochemistry, and using Hess’ law. For the latter approach, the enthalpies of the solution in DMF in crystalline and supercooled liquid states were derived. The values obtained by the two methods are consistent with each other. The standard thermodynamic functions (entropy, enthalpy, and Gibbs energy) between 80 and 470 K were calculated.

In this work, detailed information on the phase-transition thermodynamics of the analgesic and antipyretic drug phenazone, also known as antipyrine, is reported. It was found that the compound forms two polymorphs. Fusion thermodynamics of both forms was studied between 298.15 K and T_m using the combination of differential scanning calorimetry and solution calorimetry. The vapor pressures above crystalline and liquid phenazone were measured for the first time using thermogravimetry—fast scanning calorimetry technique. These studies were complemented by computation of the ideal gas entropy and heat capacity and by measurements of the condensed phase heat capacities. On the basis of experiments performed, we derived sublimation and vaporization enthalpies and vapor pressure above liquid and both crystalline modifications of phenazone in a wide range of temperatures.

Supercooled tolbutamide melt was studied revealing nucleation and growth kinetics, nuclei stability and growth rate, and factors guiding polymorph selection.