The lipophilic behaviour of organic compounds: 1. An updating of the hydrophobic fragmental constant approach

In the first part of this paper we briefly describe experimental (octanol/water partitioning) as well as computational approaches to quantifying molecular lipophilicity. The central section focuses on the hydrophobic fragmental constant approach (Σf-system) as developed by Rekker and his group, starting in the early seventies. The original approach has been extended and revised a number of times; the most recent updating is presented here. It is followed by a detailed description of how to apply the correction factor C<INF>M</INF>. The practical procedure of Σf-calculations is described for some examples and the validity of these calculations is verified by comparison with other calculation methods and experimental data.