MODELING NORMAL-OCTANOL WATER PARTITION-COEFFICIENTS BY MOLECULAR TOPOLOGY - POLYCYCLIC AROMATIC-HYDROCARBONS AND THEIR ALKYL DERIVATIVES

Models based entirely on the chemical structure have been developed for accurate prediction and evaluation of n-octanol/water partition coefficients (log K(ow)) of the polycyclic aromatic hydrocarbons (PAHs) and their alkyl derivatives. The molecular connectivity indices and other topological features, which are calculated exclusively on the basis of information readily available about all chemicals, synthesized or hypothetical, were used as molecular descriptors. Derived models account for 98% of the variation in the log K(ow) data which cover the range of 4 orders of magnitude. In all models PAHs partitioning properties are described best by the 0-chi-v indices whose numerical values are directly proportional to PAHs log K(ow). Developed models enable the log K(ow) data to be predicted within a factor of two, the probability being about 98%. This result is in agreement with the deviation range of 0.30 log units proposed to be acceptable according to the OECD guidelines for log K(ow) data. Thus, our models can be used as reliable estimation method for predicting PAH K(ow) data in line with the requirements of the OECD guidelines.