Prediction of Octanol-Water Partition Coefficients Using Group Contribution Solvation Model

Shiang-Tai Lin and Stanley I. Sandler
Center for Molecular and Engineering Thermodynamics
Department of Chemical Engineering
University of Delaware
Newark, DE 19716

Using our recently derived Group Contribution Solvation (GCS) model, we have developed a predictive model for the octanol-water partition coefficient (KOW), the GCSKOW model. In this model KOW is calculated from two molecular structure parameters which take into account the size and shape effects, and one energy parameter that determines the attractive interactions between the solute and the solvent. Based on quantum mechanical studies we found that for organic solutes with a single strong functional group, all these parameters can be obtained in a group contribution manner. Consequently, we present a database here for various functional group contributions in this new, easy-to-use model. The root mean square deviation of predicted log10KOW from GCSKOW for 226 solutes is found to be 0.14 (which corresponds to 38% in KOW), which considerably less than from the methods of Hansch and Leo (0.18 in log10KOW or 51%), KOW-UNIFAC (0.21 or 62%), and LSER (0.23 or 71%).

Last updated on June 16, 1999
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