Thermochemistry of fusion of benzocaine and S-naproxen between 298.15 K and Tm studied by solution and fast scanning calorimetry

• Published in: Journal of thermal analysis and calorimetry 2023-03, Vol.148 (6), p.2457-2466
• Main Authors: Yagofarov, Mikhail I., Sokolov, Andrey A., Ziganshin, Marat A., Mukhametzyanov, Timur A., Solomonov, Boris N.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Differential scanning calorimetry; Enthalpy; Heat measurement; High temperature; Inorganic Chemistry; Measurement Science and Instrumentation; Melting points; Naproxen; Organic chemistry; Parameters; Physical Chemistry; Polymer Sciences; Specific heat; Thermochemistry; Thermodynamics
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-022-11676-y

Thermodynamic parameters of fusion define the solubility and stability of the crystalline materials and thus are important in the field of pharmaceutics. However, determining these parameters in practice by the common approaches, such as differential scanning calorimetry, is often hindered by the evaporation and degradation at high temperatures. Thus, the development of the independent approaches for determination of thermodynamic parameters of melting is important from both fundamental and practical standpoints. In this work two active pharmaceutical ingredients, S -naproxen and benzocaine, were studied by differential scanning calorimetry, fast scanning calorimetry, and solution calorimetry. Solution calorimetry was used to independently find the fusion enthalpies at 298.15 K. Fast scanning calorimetry was used to access the heat capacities of the supercooled liquid states. The literature data on the fusion enthalpies and heat capacities of the solid and liquid were collected and critically analyzed, considering the performed measurements. As a result, a consistent set of the fusion enthalpies and solid and liquid heat capacities between 298.15 K and melting point of S -naproxen and benzocaine was derived. The viability of the solution calorimetry approach was verified for polyfunctional organic molecules, providing a basis for the further use of this approach in the field of the thermochemistry of the pharmaceutically active compounds.