Chapter 7. Organic Liquid–Water Partitioning

Summary

This chapter focuses on the equilibrium partitioning of nonionic organic compounds between aqueous solutions and water-immiscible, organic liquids. Such partitioning is shown to be directly related to solute aqueous activity coefficients and inversely related to their organic solution activity coefficients. Within a series of structurally related compounds, organic solvent-water partition constants typically increase with decreasing (liquid) aqueous solubilities. Further, the partitioning of apolar and weakly polar compounds within one organic solvent-water system commonly correlates with the partitioning found in other organic solvent-water systems. Multiparameter LFERs are available to quantify the contributions of van der Waals and hydrogen-bonding forces to specific organic solvent-water partition constants for solutes and solvent systems of interest. Particular attention is given to the octanol-water partition coefficients and their relations to aqueous activity coefficients as well as to other organic solvent-water partition coefficients. Finally, an atom/fragment contribution scheme is demonstrated for estimating octanol-water partition constants from solute structures.