Studying the sublimation thermodynamics of ethionamide and pyridinecarbothioamide isomers by transpiration method

Temperature dependences of saturated vapor pressure for crystalline phases of 2-ethyl-4-pyridinecarbothioamide (ethionamide) and two parent compounds 2- and 4-pyridinecarbothioamide isomers were measured by the transpiration method. The results were used to determine the standard molar enthalpies, entropies and Gibbs energies of sublimation at T = 298.15 K. HYBOT descriptors application has shown an increase in the donor–acceptor ability of the molecules of the studied compounds to form hydrogen bonds to result in their crystal lattice energy growth. The obtained standard molar sublimation enthalpies have been compared with the literature results for 2- and 4-substituted pyridine isomers.