Thermochemistry of phase transitions of aromatic amines: Estimation of the sublimation enthalpy at 298.15 K through the fusion enthalpy

Abstract

In the present work two methods of determination of sublimation enthalpies at 298.15K based on solution enthalpies at 298.15K and fusion enthalpies at the melting temperatures were applied for aromatic amines. The sublimation enthalpies of 17 substituted anilines and 1- and 2-naphthylamines at 298.15K were calculated using their fusion enthalpies at the melting temperatures found in the literature, the solvation enthalpies in benzene and vaporization enthalpy of aniline. Additionally, the sublimation enthalpies of 9 substituted anilines and 1- and 2-naphthylamines were determined from their solution and solvation enthalpies. In this work we measured the solution enthalpies of aniline, its five derivatives and 2-naphthylamine in benzene while the solution enthalpies of other five aromatic amines were taken from the literature. The solvation enthalpies were calculated by means of the group-additivity scheme. The sublimation enthalpies values obtained as such were compared to the reference data. This method showed the good congruence with both direct experiment and solution calorimetry approach. In most cases the divergence does not exceed 2–3%. The consistency between independently determined sublimation enthalpies values validates the reliability of the relationship between the sublimation enthalpy at 298.15K and fusion enthalpy at the melting temperature.