Prediction of physicochemical parameters by atomic contributions

We present a new atom type classification system for use in atom-based calculation of partition coefficient (log P) and molar refractivity (MR) designed in part to address published concerns of previous atomic methods. The 68 atomic contributions to log P have been determined by fitting an extensive training set of 9920 molecules, with r(2) = 0.918 and sigma = 0.677. A separate set of 3412 molecules was used for the determination of contributions to MR with r(2) = 0.997 and sigma = 1.43. Both calculations are shown to have high predictive ability.