I.P. Alimarin

The influence of the nature of the organic solvent on the extraction of chelate compounds

Abstract The influence of the nature of the organic solvent on the extraction of the thenoyltrifluoroacetonates of NpV, CoII and CeIII, the hydroxyquinolates of NpV and WVI, the acetylacetonates of CoII and FeIII, the 1-nitroso-2-naphtholate of CoII, and some other chelate compounds has been studied. As a rule, “co-ordination-unsaturated” chelates (co-ordination number of the central atom greater than twice its charge, bidentate reagent) are extracted better by ketones, esters, and, particularly, by alcohols; and, normally, are less well extracted by ethers and by hydrocarbons and their halogen-substituted derivatives. The extraction of “co-ordination-unsaturated” chelates can in some cases be favoured by the use of an excess of the reagent. “Coordination-saturated” chelate compounds (co-ordination number not greater than twice the charge, bidentate reagent) can be extracted by solvents of extremely diverse nature, including non-oxygen-containing solvents of relatively low polarity. Attention is drawn to the possibility of separating “co-ordination-saturated” and “co-ordination-unsaturated” chelate compounds.

Investigation of the chemistry of pentavalent neptunium

Abstract The formation of complex compounds of Np(V) in solutions of oxalic, tartaric, citric and ethylenediaminetetraacetic acids has been investigated by an ion exchange procedure. Several complexes have been shown to exist and their composition and stability constants determined. A qualitative spectrophotometric study has shown Np(V) forms complexes with some other substances. The ability of the NpO2+ ion to form complexes appears to exceed that expected for a large singly charged cation. The extraction of Np(V) chelates with thenoyltrifluoroacetone, acetylacetone, 1-nitroso-2-naphthol, cupferron and 8-hydroxyquinoline has been studied. Chelates of Np(V) with TTA and 1-nitroso-2-naphthol have been shown to be readily extracted at pH 7–10 by solutions of the reagents in active oxygen-containing solvents, especially in n-butyl and other alcohols. The nature of the solvent markedly affects the extraction. The properties of NpO2+ have been compared with those of the ions of other pentavalent actinides and an analogy between Np(V) and Am(V) and between U(V) and Pu(V) noted.

Extraction kinetics of metal chelates

The factors which in the authors opinion are most important in determining the rates of extraction processes are considered. These include: site of metal chelate formation extraction of metal chelates as a homogeneous heterophase process (quantitative characteristics); role of replacement of water in the aquo-complex; catalysis by the ligand; influence of the method of reagent introduction and kinetics of exchange extraction reactions. The urgent need for further development of the kinetic investigation of extraction seems incontrovertible. Suitable apparatus is needed for rapid mixing and separation of phases.

Exchange extraction reactions of internal complex compounds

1. n nThe exchange reactions of 8-hydroxyquinolinates and cupferronates were studied, and the corresponding exchange series were compiled. The sequence of arrangement of the elements in the series coincides with the sequence of variation of the values of Kex1/p. n n n n n2. n nA method was described for determining extraction constants using exchange reactions. n n n n n3. n nValues of the extraction constants were determined for diethyldithiocarbamates of zinc, cadmium, and lead.