New method for determination of vaporization and sublimation enthalpy of aromatic compounds at 298.15 K using solution calorimetry technique and group-additivity scheme

Abstract

In this work a new method for determination of vaporization/sublimation enthalpies of aromatic compounds directly at T=298.15K was developed. This method is based on the general relationship between vaporization/sublimation enthalpy and enthalpies of solution and solvation of the studied compound in any solvent. According to this method the procedure for determination of vaporization (liquids) or sublimation (solids) enthalpy includes measurement of the solution enthalpy of the compound in a selected solvent and calculation of the solvation enthalpy for this system. A group-additivity scheme for calculation of solvation enthalpies is proposed. The solvation enthalpy of compound is estimated from the solvation enthalpy of parent aromatic or heteroaromatic compound and contributions of the substituent groups. Limiting solution enthalpies of 34 aromatic compounds (substituted benzenes, naphthalenes, biphenyls, pyrene, anthracene and pyridines) in carbon tetrachloride, benzene, acetonitrile and N,N-dimethylformamide were measured in the present work at 298.15K. Vaporization/sublimation enthalpies of 78 aromatic and heteroaromatic compounds were determined directly at 298.15K using experimentally measured solution enthalpies and predicted values of solvation enthalpies. The results are in good agreement with available literature data.