Atomic Connectivity Group Contribution Method for Predicting the Phase Transition Properties of Enthalpy and Entropy

In this paper, four atomic connectivity group contribution (ACGC) models are developed for predicting the phase transition properties of organic compounds. These established ACGC models include atomic adjacent groups (AAG), shape factors (SFs), and atomic connectivity factors (ACFs), which are used to predict the entropy of fusion (ΔfusS), standard enthalpy of vaporization (ΔvapH°), standard enthalpy of sublimation (ΔsubH°), and enthalpy of fusion (ΔfusH). Groups are defined as atomic adjacent groups through the relation between the core atom and its neighbor atoms. Shape factors and atomic connectivity factors are proposed to deal with isomers in the group contribution (GC) method. After the introduction of SFs and ACFs into our models, the mean absolute error of the ΔfusS, ΔvapH°, ΔsubH°, and ΔfusH values for isomers decreases by 7.97%, 16.57%, 14.33%, and 6.28%, respectively. The ΔfusS, ΔvapH°, ΔsubH°, and ΔfusH models of ACGC can provide accurate calculation results with high R2 values of 0.945, 0.991, 0.921, and 0.901. Further, it is proved that ACGC models have good predictive ability and robustness through external validation and cross validation.