Organic reagents cupferron

Classical analysis by gravimetry (see Section 5) took a new turn when L. H. Tschugaeff reported the novel use of a new organic reagent, dimethylglyoxime, in 1905, but several decades passed before other reagents such as cupferron see Cupferron), 8-hydroxyquinoline, l-nitroso-2-naphthol, the alkyl- and arylarsonic acids, and so on, became firmly established. ... 

Only those organic reagents, such as cupferron and acetylacetone, which form chelates highly soluble in non-polar organic solvents, can be used in the extraction of matrix elements. 

The elements which are co-precipitated as hydroxides can also be separated by organic reagents of the R-OH type, such as 8-hydroxyquinoline, cupferron, or 6-diketones. Metal ions giving sparingly soluble sulphides may be co-precipitated by organic reagents of the R-SH type, e.g., dithiocarbamates. 

A number of organic compounds, eg, acetylacetone [123-54-6] and cupferron [135-20-6] form compounds with aqueous actinide ions (IV state for reagents mentioned) that can be extracted from aqueous solution by organic solvents (12). The chelate complexes are especially noteworthy and, among these, the ones formed with diketones, such as 3-(2-thiophenoyl)-l,l,l-trifluoroacetone [326-91-0] (C4H2SCOCH2COCF2), are of importance in separation procedures for plutonium. 

The combined GHCls extracts are washed with 20 ml of HsO to which has been added 1 ml of cupferron reagent and sufficient (NEiJeCOe soln. to make the pH 8.0-8.5. Then the Th234 Is back-extracted Into 10 ml of 3 M nitric acid containing a few ml of saturated Br2 water which serves to decompose the UXi cupferrate. This allows extraction of all the organic material and excess bromine Into the CHCle phase. 

Kemp found that Pu(III) required four cupferron molecules per Pu atom in extractions into chloroform from HCl-ammonium chloride solutions (p = 1.0 pH = 4.5 - 5). He ruled out oxidation of the Pu(III) by the reagent and postulated an "extra" cupferron molecule in the organic phase to complete the eightfold coordination sphere. The pH dependence for Pu(III)from these solutions was found to be third power, in accordance with Eq. 1. 

Distribution ratios (chloroform-water) have also been reported for curium complexes with 8-hydroxyquinoline (oxineX cupferron, and JV-benzoyl-phenylhydroxylamine (NBPHA) [136]. Only 1 3 complexes with Cm(iii) and Am(iii) were reported, and extraction into the organic phase appears to be very high at pH values above 5. Solution interaction of Cm(iii) with bis(salicylidene)ethylenediimine (SALEN) and derivatives has also been studied [137], With the reagent arsenazo(iii), both Cm(iii) and Am(iii) form 1 1 and 1 2 complexes [138]. 

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