Non-additivity in the solvation enthalpies of NH-containing compounds and estimation of their sublimation enthalpies at 298Â K

- Non-additivity contributions into solvation enthalpies of NH-containing compounds were estimated.
- Solution enthalpies of 19 compounds were measured.
- Vaporization/sublimation enthalpies of 6 NH-containing compounds were determined.
- Method for determination of vaporization/sublimation enthalpies directly at 298.15 K was applied.
- Obtained values are in good agreement with the results of conventional methods.

In the present work, we have developed an additivity scheme for the calculation of solvation enthalpies of NH-containing compounds capable of hydrogen bond formation with solvent. The solvation enthalpies of these compounds were calculated using an additivity scheme and taking into account the contribution due to hydrogen bond formation between solute and solvent. This contribution was calculated using several different equations which connected the enthalpies of hydrogen bonds with frequency shifts of NH stretching vibrations. The efficiency of the scheme for calculating the enthalpies of solvation was tested on the heterocyclic NH-containing compounds in tetrahydrofuran and 1,4-dioxane. The vaporization and sublimation enthalpies of heterocyclic NH-containing compounds at 298.15 K were estimated using experimentally measured solution enthalpies and estimated values of solvation enthalpies. The vaporization and sublimation enthalpies obtained in the present work are in good agreement with available literature data.The solution enthalpies of nineteen heterocyclic compounds were measured experimentally in the present work.