Fractional Extraction of Weak Acid Mixture from Its Very Dilute Solution

It was found that a weak-acid mixture could be separated successfully by fractional extraction ; two immiscible solvent layers were diluted to a certain extent, and the substances separated were purified. This fractionation method consists in the combination of the stepwise extraction of each acid from their mixture in an organic solution (dilution 7-350) with successive, small portions of aqueous sodium hydroxide solution (dilution 5-30) and subsequent thin layer chromatographic tests on each of the acidified extracts. When an organic solvent suitable for separation can be found the fractional extraction is possible regardless of the difference in ionization constants.