Copper cupferronate

SHAB theory, 1040 Copper cupferronate vibration frequencies, 511 Copper proteins models, 85 Coprogen... 

Another extremely sensitive method for the reliable detection of traces of copper in water is based on the production of copper cupferronate when cupferron (ammonium salt of nitrosophenylhydroxylamine) is added to the water. The product can be taken up in chloroform, the latter evaporated, and the residue tested with alizarin blue (page 216). 

The name cupferron was assigned to the compound by O. Baudisch, and is derived from the fact that the reagent precipitates both copper and iron. Cupferron precipitates iron completely in strong mineral-acid solution, and copper is only quantitatively precipitated in faintly acid solution. The selectivity of the reagent is greatest in strongly acid solution. 

The substance is dissolved in ether and by passing in dry ammonia gas the ammonium salt is precipitated. From this salt the iron and copper salts, insoluble in water, are prepared by precipitation with Fe+ + + and Cu++ ( Cupferron ). 

Cupferron (29), as the name suggests, has been applied to the analytical determination of copper and iron. In neutral solution, a white 1 1 complex with Ag1 has been obtained which reacted with Mel to give the methyl ether.292 Reaction of the related ligand (30) with silver nitrate in aqueous methanol gave a red predpitate which on further reaction with Mel gave the methyl ether in a reaction analogous to that for cupferron.293... 

Complexes of neocupferron, the ammonium salt of Ar-nitroso-Ar-2-naphthylhydroxylamine (16 Ar = naphthyl) are less soluble and bulkier than those of cupferron and can be used to determine copper and iron from the sea and natural waters without a preliminary concentration stage. 

Soon after the introduction of dimethylglyoxime as a specific reagent for nickel by Tschugaeff-Kraut-Brunck (1905-1907), Baudisch discovered a compound which precipitates copper and iron quantitatively from acid solutions.82 He appropriately named this reagent as cupferron . It is the water soluble ammonium salt of nitrosophenylhydroxylamine (5). When dissolved in chloroform, the whitish-grey copper compound gives a bright yellow solution and the brown yellow iron(III) compound a deep red solution. This behaviour reveals the inner complex character of these derivatives (6). 

The earliest expectations of cupferron being a selective and specific reagent for copper and iron only were not justified as the reagent has been found to precipitate, with the exception of aluminum and chromium,83 almost all the tri- to penta-valent metals which form insoluble hydrous oxides. However, the reagent has acquired permanent value as an aid in separating certain metals, e.g. titanium from aluminum and chromium.84... 

The selectivity potentially offered by these reagents has attracted the attention of many workers who have proceeded on the assumption that these reagents will adsorb onto the surface of minerals with a selectivity for the metal ions of the lattice similar to that found in aqueous solution. Examples of this are dimethyglyoxime for nickel,6 cupferron for tin,5 salicylaldoxime for copper and 9-hy-droxyquinoline for lead and zinc minerals.7... 

Cupferron or amino nitroso phenyl hydroxylamine 1 may be used for the direct precipitation of iron in acid solution, in the presence of aluminium, chromium, cobalt, nickel, and zinc. Copper is precipitated along with the iron, but is easily removed afterwards by treatment with ammonia, m which it is soluble. 

As early as in the beginning of this century, chelating agents have been used as collectors in the flotation. For example, cupferron was used for flotation of oxidized copper minerals and 8-hydroxy quinoline for wolframite and lead-zinc minerals. Recently, chelating agents have been used as depressants by Schubert, Avotins and Nagaraj for the separation of fluorite from gangue minerals and molibdenite from copper sulfide minerals, respectively [3,13]. 

White to light buff crystals sensitive to light, mp 125- 26 with decompn. Soluble in water, methanol insol in ether. The aq soln is unstable. use Reagent for iron and copper. See also Cupferron. 

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