A Spatial Group Contribution Method for Predicting the Phase Transition Properties of Organic Compounds

A spatial group contribution (SGC) method is proposed for predicting the ΔvapH° (298.15 K), ΔsubH° (298.15 K), ΔfusH, and ΔfusS values of organic compounds. Relying solely on the count of groups to predict molecular properties in traditional group contribution (GC) largely overlooks the specificity conferred by the molecular stereochemistry. Our study introduces spatial group factor (SGF) and spatial position factor (SPF), designed to quantitatively characterize the three-dimensional morphological features of groups and their spatial position, respectively. The average absolute deviations of the isomers for four SGC models are reduced by 21.5, 23.3, 10.5, and 10.7%, respectively, compared with the traditional GC method, indicating that the proposed SGF and SPF facilitate the differentiation of isomers. The squared correlation coefficients (Rtest2) of the test sets in all models are higher than 0.91, and their QLOO2 obtained by internal validation exceeds 0.89, indicating that all models have good predictive ability and stability.