A norm index-based QSPR model to predict the standard absolute entropy of organic compounds in three phase states

The entropy of organics is a fundamental and crucial thermodynamic quantity. In this work, a unified quantitative structure-property relationship (QSPR) model was proposed to predict the standard absolute entropy for 15 kinds of organic compounds in three phase states based on the norm index concept. Three phase states of the standard absolute entropy of organics, namely, the solid state (S-o(s)), liquid state (S-o(l)) and gas state (S-o(g)), were considered in the model. This unified model presented good accuracy and fitting as demonstrated by the R-2, F and AARD statistical parameters obtained for 45 S-o(s) data points, 190 S-o(l) data points and 174 S-o(g) data points, respectively. Furthermore, the results of internal and external validation and applicability domain analysis proved that this norm index-based QSPR model was stable and robust and had both statistical quality and predictive ability. The satisfactory obtained results suggested that this unified model can be successfully used to predict the So values of organic compounds in different phase states and that the norm descriptors may be general and universal. (C) 2020 Elsevier B.V. All rights reserved.