Strontium reduction

Reduction of BaSO appears to begin about 900°C (15). The presence of iron or iron oxide can cataly2e the barium (9) and also strontium reduction reaction rates. However, iron impurity can also increase the acid-soluble content of the black ash (9). 

For the Verneuil growth of mtile and strontium titanate it is necessary to maintain strongly oxidizing conditions to prevent excessive reduction of TF+ to Tk+. This is achieved by adding a third outer tube carrying extra oxygen to the Verneuil torch (Fig. 1) in the tricone modification. Annealing in O2 at about 1100°C is subsequently used to achieve full oxidation. 

Selective Reduction. In aqueous solution, europium(III) [22541 -18-0] reduction to europium(II) [16910-54-6] is carried out by treatment with amalgams or zinc, or by continuous electrolytic reduction. Photochemical reduction has also been proposed. When reduced to the divalent state, europium exhibits chemical properties similar to the alkaline-earth elements and can be selectively precipitated as a sulfate, for example. This process is highly selective and allows production of high purity europium fromlow europium content solutions (see Calcium compounds Strontiumand strontium compounds). 

This reaction occurs in a vacuum and the gaseous metal is condensed in a cooler part of the apparatus. AH strontium metal is produced commercially by the thermal reduction process in aUoy steel retorts. 

Heating with the following solids, their fusions, or vapours (a) oxides, peroxides, hydroxides, nitrates, nitrites, sulphides, cyanides, hexacyano-ferrate(III), and hexacyanoferrate(II) of the alkali and alkaline-earth metals (except oxides and hydroxides of calcium and strontium) (b) molten lead, silver, copper, zinc, bismuth, tin, or gold, or mixtures which form these metals upon reduction (c) phosphorus, arsenic, antimony, or silicon, or mixtures which form these elements upon reduction, particularly phosphates, arsenates,... 

The true alkaline earth metals—calcium, strontium, and barium—are obtained either by electrolysis or by reduction with aluminum in a version of the thermite process (see Fig. 6.8) ... 

Strontium ranelate is an oral agent possessing bone-forming and antiresorptive properties. Some data suggest significant reductions in vertebral fractures.46 However, the benefit in nonvertebral fractures is unclear. This agent has not yet been approved for use by the FDA. 

The reduction of octaethyl-l,r-biphosphole, -biarsole, and -bistibole with strontium and barium in THF yields the l,l -dipentelaoctaethylstrontocenes and -barocenes (ECsEt4H)2M (E = P 157, As, Sb). The strontocene crystallizes as a THF adduct whereas the barocene 157 precipitates co-ligand-free but as a coordination polymer (Figure 83).260... 

The removal of inorganic salts from reaction mixtures afforded by polymeric materials may be simply and effectively accomplished by dialysis,166 178 after decomposition of remaining periodate with ethylene glycol130 131 or butylene glycol. 161 170 Alternatively, the iodate and periodate ions may be removed as such, or after reduction to free iodine. The iodate and periodate ions have been effectively precipitated by means of sodium carbonate plus manganous sulfate,6 or by lead dithionate,191 barium chloride,24 192 193 strontium hydroxide194 202 or barium hydroxide,203 204 lead... 

Since aldehydes are notoriously polymerizable and difficult to manipulate, the products of periodate oxidation are oftentimes further oxidized, with hypohalite, to carboxylic acids, or are reduced to the corresponding alcohols. Oxidation has been more usually employed than reduction, since acids frequently form crystalline salts and other conveniently prepared derivatives. A process of oxidation of these aldehydic products by hypo-bromite, in the presence of barium carbonate or strontium carbonate, was developed and used extensively by Hudson and his coworkers.107 110 194-199,90s Their method can best be illustrated by an example the further oxidation of the dialdehyde, VI, shown previously (see p. 16) to be obtained by the oxidation of the methyl a-D-aldohexopyranosides. The isolation of... 

Preparation. Strontium metal can be obtained by electrolysis of the fused chlorides or by reduction of the oxide by aluminium. 

Roden EE, Leonardo MR, Ferris FG (2002) Immobilization of strontium during iron biomineralization coupled to dissimilatory hydrous ferric oxide reduction. Geochim Cosmochim Acta 66 2823-2839 Roe JE, Anbar AD, Barling J (2003) Nonbiological fractionation of Ee isotopes evidence of an equilibrium isotope effect. Chem Geol 195 69-85... 

Two other methods of producing strontium are by thermal reduction of strontium oxide and by the distillation of strontium in a vacuum. 

Palladium catalysts resemble closely the platinum catalysts. Palladium oxide (PdO) is prepared from palladium chloride and sodium nitrate by fusion at 575-600° [29,30]. Elemental palladium is obtained by reduction of palladium chloride with sodium borohydride [27, 31], Supported palladium catalysts are prepared with the contents of 5% or 10% of palladium on charcoal, calcium carbonate and barium sulfate [32], Sometimes a special support can increase the selectivity of palladium. Palladium on strontium carbonate (2%) was successfully used for reduction of just y, (5-double bond in a system of oc, / , y, (5-unsaturated ketone [ii]. 

If the free energy changes for the reduction of the sulfate to make H2S rather than SO2 had been considered in this analysis, the oxides of several more elements would have been included in the boxed-off area of appropriate materials. From past practice, however, it is known that oxides of calcium, strontium and lithium, for instance, are not as effective. An appropriate future area of research would be to investigate those materials more thoroughly. 

Strontium metal also can be prepared by thermal reduction of its oxide with aluminum. Strontium oxide-aluminum mixture is heated at high temperature in vacuum. Strontium is collected by distillation in vacuum. Strontium also is obtained by reduction of its amalgam, hydride, and other salts. The amalgam is heated and the mercury is separated by distillation. If hydride is used, it is heated at 1,000°C in vacuum for decomposition and removal of hydrogen. Such thermal reductions yield high—purity metal. 

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