LIQUID-LIQUID-EXTRACTION OF IRON(III) AND GALLIUM(III) WITH MACROCYCLIC SCHIFF-BASES CONTAINING BISPHENOL-A SUBUNITS

The quantitative extraction of iron(III) and gallium(III) was investig ated with the recently synthesized macrocyclic Schiff base containing bisphenol A subunits. The phenol groups in the Schiff base moiety led to a large increase in the percent extraction of trivalent metal ions. The substitution of methoxy groups for phenolic OH ligands resulted i n a marked decrease in the extractability of metal ions, and no iron(I II) was extracted. The corresponding acyclic Schiff base was found to have a reasonable reactivity toward metal ions and a better solubility in organic solvents. The iron(III) and gallium(III) complexes with ma crocyclic and acyclic Schiff bases were quantitatively extracted into nitrobenzene without the presence of bulky counter anions. A single ex traction gave a good separation of iron(III) from iron(II) in the mole ratios 4:1 to 1:3. The red iron(III) complexes can be used for the ex traction-spectrophotometric determination of iron(III). The apparent m olar absorptivity at 518 nm is 5.43 X 10(3) 1 mol(-1) cm(-1).