Substituent Contributions To Partition Coefficients

The concept of substituent contribution to the partition coefficient of a substituted molecule with respect to a parent molecule was introduced by Fujita et al. (1964) in medicinal chemistry and pharmaceutical science for estimating the Kow values of some drugs and other chemicals in the absence of their experimental values. It has gained relatively good success when applied to small and structurally simple molecules but has had less success when extended to more complicated molecules. To...

Theoretical Considerations

Consider first the simpler case of a partition-limited model for the plant uptake of nonionic contaminants from a soil-free nutrient solution by passive transport through the plant vascular system. Here water is both the solvent for the contaminant and the medium that carries it to plant roots (and to other water-contacted surfaces) and eventually to other parts of the plant via the plant vascular system. The overall plant uptake process is driven by the external-water concentration and is...