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     ...Introduction

Definition of Log P Property Data

The logP property value is taken from the ratio of the respective concentrations of a compound in the octanol and water partitions of a two-phase system at equilibrium.  The concentration measurements are made at a constant temperature, normally 25° C.

where the subscripts oct and aq are for octanol and water phases respectively.

In traditional QSAR paradigms, log of the octanol-water partition coefficient (logP) has been used extensively to describe the lipophilic or hydrophobic properties of a compound.  The partitioning of a compound between two immiscible phases, aqueous [A] and octanol [O], is considered to closely approximate the interactions involved in hydrophobic bonding.

The logarithm of water/octanol partition coefficent is the value given in standard practice.  This is becuase the measured value of the w/o ratios range over more than 12 orders of magnitude (i.e. 10E8 to 10E-4).