Dissociation extraction


A PROCESS has been devised for separating organic acids (or bases) of different dissociation constants from each other by solvent extraction. It is based on the fact that, in general, weak organic acids are soluble in solvents only in the form of the free undissociated acid. In essence, the system consists of a continuous counter-current extraction column in which the solvent flows in one direction (say, upwards) and water flows in the opposite direction. The mixture to be separated is fed to an intermediate point in the column. The acids partition themselves between the solvent and the water in a way which depends on the dissociation constant (K) and the pH. The concentration of an acid in the solvent (CS) is related to its concentration in the water (CW) by the equation


  1. 1

    Craig, L. C., J. Biol. Chem., 155, 519 (1944).

    CAS  Google Scholar 

  2. 2

    B.P. 599, 854.

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Twigg, G. Dissociation extraction. Nature 163, 1006–1007 (1949). https://doi.org/10.1038/1631006a0

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