Trivalent ions bismuth

A2Pt207, similar to those reported for tin, ruthenium, titanium, and several other tetravalent ions. Trivalent ions which form cubic platinum pyrochlores range from Sc(III) at 0.87 A to Pr(III) at X.14 A. Distorted pyrochlore structures are formed by lanthanum (1.18 A) and by bismuth (1.11 A). Platinum dioxide oxidizes Sb203 to Sb2(>4 at high pressure. The infrared spectra and thermal stability of the rare earth platinates have been reported previously and will not be repeated here, except to point out the rather remarkable thermal stability of these compounds decomposition to the rare earth sesquioxide and platinum requires temperatures in excess of 1200 °C. 

Cerium (IV) in solution is obtained by treatment of Ce111 solutions with very powerful oxidizing agents, for example, peroxodisulfate or bismuthate in nitric acid. The aqueous chemistry of CeIV is similar to that of Zr, Hf, and, particularly, tetravalent actinides. Thus Ce gives a phosphate insoluble in 4 M HN03 and an iodate insoluble in 6 M HN03, as well as an insoluble oxalate. The phosphate and iodate precipitations can be used to separate Ce from the trivalent lanthanides. Ce is also much more readily extracted into organic solvents by tributyl phosphate and similar extractants than are the Lnm lanthanide ions. 

Reduction of triarylbismuth dihalides to the parent triarylbismuthines can be performed by using a variety of reducing agents, which include hydrazine hydrate, sodium hydrosulfite, liquid ammonia, LiAlH4, NaBH4, sodium sulfide and sodium dialkyldithiocarbamate. This type of reduction has been used for the purification of tris(3-methylphenyl)bismuthine which is purified with difficulty in the trivalent state [26JA507]. The electrolytic reduction of triphenyl-bismuth dibromide has been found to be a one-step, two-electron process where the bromine atoms are released as bromide ions [66JA467]. 

The test identifies the substance to be examined as a salt of bismuth, Several insoluble bismutii salts have foxmd use orally as antacids and topically in the treatment of skin disorders. Others have been used in the treatment of syphilis and as an amoebicide. Most of these therapeutic substances have been replaced by more modem alternatives, and reference to bismuth is currently made in only four monographs, and just one dictate method (a). Bismuth forms trivalent and pentavalent ions, but the trivalent is by far the most conunon. Most bismutii(III) and bismuth(V) forms insoluble salts, especially xmder alkaline conditions. This behavior and the insolubility of bismuth sulphide form the basis of test (a). In test (b) a colored complex between bismuth and thiourea is formed. 

In the processing of nuclear materials, precipitation/coprecipitation techniques are used for the separation of the actinides from most fission products. Both fluoride and oxalate complexes of these metal ions are sufficiently insoluble to accomplish this separation (Stary 1966). Coprecipitation with bismuth phosphate has also been used for this purpose (Stary 1966). Because of their insensitivity to subtle changes induced by minor cation-radius changes, such techniques are not useful for the separation of the lanthanides from the trivalent actinide metal ions. 

Some oxidants are rather specific in their action and tend to bring about a preferred type of oxidation. A few such oxidants are periodate ion, lead tetraacetate, bismuthate ion, or trivalent silver, which oxidize adjacent secondary alcohol groups with chain cleavage to dialdehydes, and nitrogen dioxide, which preferentially oxidizes primary alcohol groups to carboxyl groups. 

The nonstoichiometric sugar oxidation process in the presence of alkali is used for both qualitative and quantitative determination of reducing sugars (Fehling s reaction with alkaline cupric tartrate Nylander s reaction with alkaline trivalent bismuth tartrate or using Benedict s solution, in which cupric ion complexes with citrate ion). Hydroxyaldehydes and hydroxyketones are formed by chain cleavage due to retroaldol reaction under nonoxidative conditions using dilute alkali at elevated temperatures or concentrated alkali even in the cold. 

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