Estimating Solid–Liquid Phase Change Enthalpies and Entropies

Abstract

A group additivity method based on molecular structure is described that can be used to estimate solid–liquid total phase change entropy (Δ0TfusStpce) and enthalpy (Δ0TfusHtpce) of organic molecules. The estimation of these phase changes is described and numerous examples are provided to guide the user in evaluating these properties for a broad range of organic structures. A total of 1858 compounds were used in deriving the group values and these values are tested on a database of 260 additional compounds. The absolute average and relative errors between experimental and calculated values for these 1858 compounds are 9.9 J⋅mol−1⋅K−1 and 3.52 kJ⋅mol−1, and 0.154 and 0.17 for Δ0TfusStpce and Δ0TfusHtpce, respectively. For the 260 test compounds, standard deviations of ±13.0 J⋅mol−1⋅K−1(Δ0TfusStpce) and ±4.88 kJ mol−1(Δ0TfusHtpce) between experimental and calculated values were obtained. Estimations are provided for both databases. Fusion enthalpies for some additional compounds not included in the statistics are also included in the tabulation.