Update and expansion of a system constant database for biphasic liquid-liquid partition systems.

The solvation parameter model is used to characterize the distribution of neutral organic compounds in 8 gas-liquid, 8 water-organic solvent and 22 organic solvent-organic solvent biphasic systems. The Wayne State University (WSU-2025) compound descriptor database is used exclusively as the sole source for compound descriptors to unify the model system constants with a verified descriptor database. The gas-liquid partition models provide insight into solvent properties used to explain the driving force for the distribution of varied compounds in liquid-liquid partition systems. For aqueous biphasic systems formed with cyclohexane, n-hexadecane, toluene, chlorobenzene, 1,2-dichloroethane, chloroform, or n-octanol as a counter solvent water plays a dominant role in the distribution mechanism and the selectivity space is comparatively narrow. For totally organic biphasic systems employing acetonitrile, dimethyl formamide, dimethyl sulfoxide, ethanolamine, ethylene glycol, formamide, 1,1,1,3,3,3-hexafluoroisopropanol, methanol, propylene carbonate, or 2,2,2-trifluoroethanol as the polar solvent with n-heptane (or n-hexane), isopentyl ether, 1,2-dichloroethane, n-octanol, or triethylamine as counter solvents forming biphasic systems the selectivity space is densely occupied without redundancy among the systems reflecting the wide range of properties possible for polar organic solvents and the absence of a dominant solvent in the database. The selectivity space for the aqueous and totally organic biphasic systems do not overlap on account of the significant difference for the range of the v and b system constants. Hierarchical cluster analysis with the system constants as variables is used to visualize the selectivity space to facilitate system selection.