AbstractNewly derived property equations correlate BC(DEF) coordinates with calculated molar volume and refractivity and partitioning between water and six organic solvents. A new method is described for obtaining the BC(DEF) coordinates of a molecule from available physical property data. Its application to 500 compounds indicates that the BC(DEF) intercorrelation describes the properties of large and polar molecules, such as drugs, almost as well as those of simpler molecules. The effects of an erroneous physical property value on calculated BC(DEF) coordinates are described.