QSPR modeling of n-octanol/water partition coefficients and water solubility of PCDEs by the method of Cl substitution position.

The number of Cl substitution positions (N(PCS)) of all 209 possible molecular structure patterns of polychlorinated diphenyl ethers (PCDEs) were correlated with their partition properties n-octanol/water partition coefficient (lgK(ow)) and sub-cooled liquid water solubilities (-lgS(w,l)). The correlation coefficients (R) and the leave-one-out (LOO) cross-validation correlation coefficients (R(cv)) of all the 6-descriptor models for lgK(ow) and -lgS(w,l) are more than 0.98. By using stepwise multiple regression (SMR), the best two models of lgK(ow) with three descriptors (R=0.9,913) and lgS(w,l) with four descriptors(R=0.9,818) were obtained respectively. Based on these equations, the two properties of all 209 PCDEs were predicted. Model validation showed that the two models exhibit optimum stability and high predictive power. Moreover, results of prediction were further compared with data from similar studies by molecular connectivity indices (MCIs) and PM3 methods.