Reduction Sodium bismuthate

Nakashima et al. [719] detail a procedure for preliminary concentration of 16 elements from coastal waters and deep seawater, based on their reductive precipitation by sodium tetrahydroborate, prior to determination by graphite-furnace AAS. Results obtained on two reference materials are tabulated. This was a simple, rapid, and accurate technique for determination of a wide range of trace elements, including hydride-forming elements such as arsenic, selenium, tin, bismuth, antimony, and tellurium. The advantages of this procedure over other methods are indicated. 

The optimal reaction conditions for the generation of the hydrides can be quite different for the various elements. The type of acid and its concentration in the sample solution often have a marked effect on sensitivity. Additional complications arise because many of the hydrideforming elements exist in two oxidation states which are not equally amenable to borohydride reduction. For example, potassium iodide is often used to pre-reduce AsV and SbV to the 3+ oxidation state for maximum sensitivity, but this can also cause reduction of Se IV to elemental selenium from which no hydride is formed. For this and other reasons Thompson et al. [132] found it necessary to develop a separate procedure for the determination of selenium in soils and sediments although arsenic, antimony and bismuth could be determined simultaneously [133]. A method for simultaneous determination of As III, Sb III and Se IV has been reported in which the problem of reduction of Se IV to Se O by potassium iodide was circumvented by adding the potassium iodide after the addition of sodium borohydride [134], Goulden et al. [123] have reported the simultaneous determination of arsenic, antimony, selenium, tin and bismuth, but it appears that in this case the generation of arsine and stibene occurs from the 5+ oxidation state. 

Time factors and reagent parameters are the same for As, Sb, Bi, Te, Ge, and Sn when using the modified Perkin-Elmer high sensitivity arsenic-selenium sampling system. The sodium borohydride reduction can be used for arsenic, antimony, bismuth, and tellurium as well. 

The only known examples are the 1-methyl- and 1-phenyl-arsetanes no four-membered heterocycles of either antimony or bismuth have yet been reported. They were prepared (77MI11800) by the reductive cyclization of a 3-chloropropyliodoarsine with sodium. Long reaction periods (48-60 h) are required for reasonable yields to be obtained. 1-Methyl-arsetane (1) was also prepared from disodium methylarsine and 1,3-dichloropropane but in lower yield (Scheme 1). 

Reduction of add solutions of vanadium pentoxide to the tetravalent state also takes place with bismuth amalgam 5 magnesium gives the trivalent salts of vanadium, while by using zinc, zinc coated with cadmium, electrolytically deposited cadmium, or sodium amalgam in the absence of air, divalent vanadium salts are obtained in solution.7 Vanadous salts and hypovanadous salts are, however, much more conveniently prepared by electrolytic reduction of acid solutions of vanadium pentoxide in an atmosphere of carbon dioxide.8... 

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]. 

A combination of metallic bismuth or bismuth chloride and a reducing agent has been employed for the reduction of the nitro group and C-C/C-N double bonds, as shown in Schemes 5.21 and 5.22. The reducing ability and/or selectivity of sodium borohydride is improved considerably in the presenee of bismuth powder or bismuth chloride. 

Reduction of nitrobenzenes to aniiines with bismuth chloride-sodium borohydride typical procedure... 

Platinum catalysts were prepared by an ion-exchange method [16,17]. Oxidised sites on the surface of an activated carbon support (CECA SOS) were created by pre-treatment with sodium hypochlorite (3%) the associated protons were subsequently exchanged with Pt(NH3)4 " ions, in an aqueous ammonia solution, and reduction was carried out on the dry catalyst under a flow of hydrogen at 300°C. A surface redox reaction was subsequently employed to deposit the bismuth whereby the catalyst was suspended in a glucose solution, under an inert nitrogen atmosphere, and the required volume of a solution of BiONOs, dissolved in hydrochloric acid (IM), was added [18]. 

A few C.C. of the urine are mixed in a test-tube with sn equal volume of solution of sodium carbonate (1 pt. ciystal. carbonate and 3 pta water), a few granules of bismuth aubnitiY.to are added, nnd the mixture boiled for some time (until it begins to bump," if necessaiy). If sugar be present, the bismuth jx>wder turns brown or black by reduction to... 

Sodium borohydride-bismuth(III) chi Reduction of nitrogenous compomm... 

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