A quantitative structure-property relationship analysis of logP for disubstituted benzenes

Ab initio HF/6-31G* optimization and electrostatic potentials have been computed for a number of disubstituted benzenes. A good six parameter correlation between logP and the computed descriptors for a training set of 103 representative disubstituted benzenes is presented. The predictive power of this model has been demonstrated on a test set of 111 disubstituted benzenes and several polysubstituted benzenes. Of these descriptors introduced, SigmaV(S)(-), a new descriptor proposed in the present work and defined as the sum of the surface minima values of the electrostatic potential, gives the most significant contribution to the logP. This descriptor, together with the molecular volume V, is thought to be mainly responsible for variations in logP with the substituent groups. The influence of group-group interactions on the logP values of isomers has been investigated by treating the ortho-disubstituted benzenes separated from the others. It shows that the influences of interactions between two neighboring substituent groups are basically thought to be relevant to hydrogen bonding and are represented mainly by variations of the V-min, V-s,(max), and polar surface area values of isomers. The applicability of the theoretical linear solvation energy relationship approach and the one proposed by Bodor have been tested and discussed.