SOLVENT EXTRACTION OF NEODYMIUM(III) AND ERBIUM(III) FROM CHLORIDE MEDIA BY MIXTURES OF 3,5- DIISOPROPYLSALICYLlC ACID AND NEUTRAL ORGANOPHOSPHORUS COMPOUNDS

ABSTRACT

Neutral organophosphorus compounds containing a phosphoryl donor group were found to cause synergistic shifts in the extraction of neodymium(III) and erbium(III) from chloride media by solutions of 3,5-diisopropylsalicyUc acid in xylene. With the series of compounds containing n-butyl substituent groups (R), the extent of the synergistic effect for both metals follows the order of increasing basicity caused by the progressive replacement of alkoxy groups by alkyl groups through the series: (RO)₃PO < (RO) ₂RPO < (RO)R₂PO < R₃PO. For the series of compounds with R = isobutyl, irregularities occur in this order, presumably because of steric effects. Both steric and electro-inductive effects appear to play a role in determining the extent of the synergistic shifts caused by the series of isomeric phosphonates, (n-C₄H₉O) ₂RPO, where R = n-butyl, isobutyl, sec-butyl and tert-butyl.

Treatment of distribution data by slope analysis and by the method of continuous variation suggests that the extracted neodymium and erbium complexes have the composition NdA3L2 and ErA3L2, where HA = 3,5-diisopropylsalicylic acid and L = neutral organophosphorus compound.