Solvent extraction of lithium and sodium with 4-benzoyl or 4-perfluoroacyl-5-pyrazolone and TOPO

The synergic solvent extraction of lithium and sodium into benzene or cyclohexane with 4-benzoyl or 4-perfluoroacyl-5-pyrazolone and trioctylphosphine oxide (TOPO) has been investigated. Quantitative extraction (>99%) of lithium, which is one of the most poorly extractable metal ions, can be achieved with 1-tolyl-3-methyl-4-perfluoroacyl-5-pyrazolone and TOPO. The extraction of sodium is somewhat poorer than that of lithium under the same conditions. The perfluoroacyl group at the 4-position of the pyrazolone ring enhances the extraction and increases the maximum percentage extracted. Cyclohexane is found to be suitable for a quantitative extraction as an organic phase when the reagents are soluble in it. Improved separation of lithium and sodium can be attained when they are extracted into benzene.