Distribution model for Folch partition



Partition coefficients for 86 varied compounds were determined for the chloroform–methanol–water (8:4:3 v/v) biphasic partition system and used to derive a model for the distribution of neutral compounds between the water-rich and chloroform-rich layers. The partition coefficients, log Kp, were correlated through the solvation parameter model giving log Kp = 1.336 – 0.014E + 0.413S + 1.583A + 1.344B – 1.378V with a multiple correlation coefficient of 0.973, standard error of the estimate 0.151, and Fischer statistic 286. In the model the solute descriptors are excess molar refraction, E, dipolarity/polarizability, S, overall hydrogen-bond acidity, A, overall hydrogen-bond basicity, B, and McGowan's characteristic volume, V. The model is expected to be able to estimate further values of the partition coefficient to about 0.13 log units. The chloroform–methanol–water partition system is shown to have different selectivities to 44 common water–organic solvent and totally organic biphasic partition systems.