Models for liquid–liquid partition in the system formamide–organic solvent and their use for estimating descriptors for organic compounds

Partition coefficients for varied compounds were determined for the organic solvent–formamide biphasic partition system where the organic solvent is 1,2-dichloroethane, 1-octanol or isopentyl ether. These partition coefficient databases are analyzed using the solvation parameter model facilitating a quantitative comparison of the formamide-based partition systems with other totally organic and water-based partition systems. Formamide is shown to be a less cohesive and hydrogen-bond acidic solvent than water with similar hydrogen-bond basicity and dipolarity/polarizability. Compared with other organic solvents its higher cohesion, dipolarity/polarizability and hydrogen-bonding capability make it a useful base solvent for forming biphasic partition systems with a range of system properties obtained through variation of the counter solvent. Formamide–organic solvent systems offer a complementary approach to water-based partition systems for sample preparation and the determination of descriptors for compounds virtually insoluble in water or unstable in water.