Thermodynamic properties of Nalidixic and Oxolinic acids: Experimental and computational study

Highlights: • Thermophysical characteristics of nalidixic and oxolinic acids were determined. • The vapor pressure of nalidixic acid was measured. • Different approaches to sublimation enthalpy estimation were compared. • The thermodynamic parameters of oxolinic acid sublimation have been estimated. -- Abstract: The thermophysical characteristics of nalidixic (NLD) and oxolinic (OXL) acids have been determined by DSC. The fusion processes of the studied compounds have been analyzed by mass-spectrometry. The transpiration method has been used to measure the vapor pressures as a function of NLD temperature. Based on these results, the standard molar enthalpy, entropy and Gibbs energy of sublimation at T =298.15 K have been calculated. A comparative study of theoretical methods of sublimation enthalpy estimation has been conducted including correlation analysis, periodic DFT computations and additive schemes based on QTAIMC descriptors and Coulomb-London-Pauli model. The thermodynamic parameters of the OXL sublimation have been estimated.