Complex Formation of Metal Ions with Sulfonated Crown Ethers in Water as Ion Size Selective Masking Reagents.

Abstract

A new type of water-soluble sulfonated crown ether has been prepared and utilized as an ion size selective masking reagent with a view to establishing a highly selective extraction-separation system. In the synergistic extraction of alkaline earths with 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone and trioctylphosphine oxide in cyclohexane, the extraction of these with larger ionic radii shifted to a higher pH region on adding the sulfonated crown ether to the aqueous phase, giving improved separations. A similar result was achieved in the extraction of lanthanides into cyclohexane with bis(2-ethylhexyl)phosphoric acid. The complex formation of alkaline earth and lanthanide ions with the sulfonated crown ethers in the aqueous solution were evaluated via the solvent extraction method.