The Further Chemistry of Ellagic Acid II. Ellagic Acid and Water-Soluble Ellagates as Metal Precipitants

Summary Preparations of the previously unreported, water-soluble, tetraguanidinium, tetracholine and tetrakisbenzyltrimethylammonium ellagates are outlined. Ellagic acid and these water-soluble salts remove Mg 2+ , Ca 2+ and Mn 2+ ions from dilute aqueous solutions at pH greater than 7. The salts also remove Fe 2+ , Fe 3+ , Co 2+ and Cu 2+ between pH 3 and pH 6. At pH 1 the water-soluble ellagates underwent hydrolysis, resulting in the precipitation of free ellagic acid in preference to the formation of metal-ellagate complexes. These trends were also observed when mixtures of metal ions were applied.