Estimation of the Enthalpy of Vaporization and the Entropy of Vaporization for Pure Organic Compounds at 298.15 K and at Normal Boiling Temperature by a Group Contribution Method

A new group contribution method for estimating the enthalpy of vaporization at 298.15 K (ΔH V(298.15 K)) and at the normal boiling temperature (ΔH V(T b)), as well as the entropy of vaporization at the normal boiling temperature (ΔS V(T b)), of pure organic compounds has been developed. Large databases of critically assessed data have been used for group contribution calculations: data for 831 compounds have been used for estimations at 298.15 K, and data for 589 compounds have been used for estimations at the normal boiling temperature. Values obtained by the method developed here have been compared with estimations by the Ducros, Chickos, and Ma and Zhao group contribution methods and by empirical equations by Vetere. A statistical analysis of the regressed data has been also performed, indicating the confidence of the regressed parameters and other related information. The average relative errors (ARE) for the new method are as follows: for ΔH V(298.15 K), 2.2%; for ΔH V(T b), 2.6%; and for ΔS V(T b), 1.8%. The error for the enthalpy of vaporization, based on an independent set of various 74 compounds not used for correlation, has been determined to be 2.5%. The new method can also be used for qualitative estimation of the normal boiling temperature.