Bromine alkali bromide

Sodium bromide [7647-15-6] NaBr, the most common and available alkali bromide, is a salt of hydrobromic acid (see Bromine compounds). Sodium bromide crystallines from aqueous solution as a 3466-08-5] NaBr-2H20, below 51°C. Above 51°C, it crystallines as the anhydrous compound. 

The increase in the solubility of bromine in soln. of ammonium salts is very marked, as is also the case with the alkali chlorides. The case with the alkali bromides is specially interesting. The solubilities by F. P. Worley are indicated in Table IX. The marked increase in the solubility of bromine in soln. of potassium bromide was attributed by M. Roloff to the formation of molecules of KBr3. He shook up a soln. of bromine in carbon disulphide with water and with an aq. soln. of potassium biomide, and measured the concentration of the bromine in the two layers. M. Wildermann has shown that the density of bromine vapour over a soln. of potassium bromide sat. with bromine is the same as over water sat. with bromine, indicating that the cone, of the free bromine in all the aq. soln. is the same, and any excess in the presence of potassium bromide must be united with the potassium bromide. All the bromine dissolved by a soln. of potassium bromide can be removed... 

The history of the bromides dates from the discovery of bromine by A. J. Balard1 in 1824. He prepared potassium bromide by the action of bromine on potash lye, and calcined the residue remaining on evaporating the product to dryness. The bromine in sea-water may be present as alkali bromide, but more probably as magnesium bromide. It is, however, uncertain how the bromides are distributed and similar remarks apply to the bromides present in spring and mine waters. Potassium bromide is used in chemical laboratories medicinally in some nervous diseases and in photography. 

The preparation oi the alkali bromides.—While V. Merz and W. Weith 2 found that metallic sodium reacts very slowly with bromine such that even after the two elements have been kept for 8 hrs. at 200°, the conversion of sodium into the bromide is but superficial potassium, caesium, and rubidium unite with bromine more quickly, forming the alkali bromide. The bromides are also formed when hydro-bromic acid is neutralized with the alkali hydroxide or carbonate, and the soln. evaporated. This method, for example, has been used for preparing rubidium bromide, RbBr. C. Chaubrie and N. N. Beketofi made a soln. of caesium bromide, CsBr, by the double decomposition of caesium sulphate, and barium bromide. P. Klein 3 made lithium bromide by digesting calcium bromide with lithium carbonate... 

Bromine can function as a solvent. One of the very few metal bromides that has significant solubility in bromine is cesium bromide, 19.3 g/100 g of solution, thus providing a method of separating cesium bromide from the other alkali bromides (12). Aluminum bromide also is reported to have significant solubility in bromine but the published solubility values are not in good agreement (13). Bromine serves as the solvent in some brominations of organic compounds, such as 1,2-diphenylethane (14). 

With the alkali bromides and alkyl ammonium bromides selenium tetrabromide can form crystalline additive compounds of the type MaSeBr6, termed selenibromides. Indeed, by the action of bromine on finely divided selenium in the presence of concentrated hydrobromic acid, a solution is obtained 4 which gradually deposits deep red crystals of hydrogen selenibromide, HaSeBr6. The solution of this body in hydrobromic acid on dilution with water undergoes decomposition with liberation of colloidal selenium. Two reactions probably occur concurrently ... 

Bromine is used for the production of alkali bromides that cannot be manufactured by the action of caustic soda on bromine because hypo-bromites and bromates are also produced. Thus, the van der Meulen process from the production of potassium bromide involves treating bromine with potassium carbonate in the presence of ammonia. 

Arsenical, and 8. Bromiuretted (Woodhall, Lincolnshire) waters contain small quantities of arsenic and bromine (as an alkali bromide) respectively. 

Sodium bromide [7647-15-6] NaBr, the most common and available alkali bromide, is a salt of hydrobromic acid (see Bromine COMPOUNDS). Sodium bromide crystallizes from aqueous solution as a di ydj 2LX.e[13466-08-5] NaBr-2H20, below 51 C. Above 51°C, it crystallizes as the anhydrous compound. Crystals of the dihydrate belong to the monoclinic system and have lattice parameters a = 659 pm, b = 1020 pm, and c = 651 pm. The anhydrous crystal belongs to the cubic system, a = 596 pm. Other physical properties of the anhydrous salt are Hsted in Table 1. The anhydrous salt is hygroscopic but not dehquescent. 

The more volatile silicon tetrachloride and silicon tetrabromide may be effectively separated on silicone oils coated on a polytetrafluoroethylene supports. Less volatile metal bromides generally require high-temperature stationary phases. Thus, the use of alkali bromide salts coated on silica as stationary phases with the use of bromine/nitrogen and boron tribromide/bromine/nitrogen mobile... 

In direct oxidation of L-xyZo-hexulose (L-sorbose) to L-xt/Zo-hexulosonic acid, with graphite electrodes in the presence of alkali (or alkaline-earth) halides, nitrates, nitrites, or borates, the yields of the acid did not exceed 35%. It was recommended that the electro-oxidation of 2,3 4,6-di-O-isopropylidene-a-L-sorbofuranose be performed in the presence of bromine, or bromide, and oxidation catalysts (for example, water-soluble nitrites or nitrates) within the pH range 6.5-8.0. Fioshin and co-workers have studied the electrosynthesis of 2,3 4,6-di-O-isopropyl-... 

If only zinc chloride and starch (or thiodene indicator) are added to the test solution, a blue color indicates the presence of hjrpoiodite. Hypobromite is identified by the formation of red tetrabromofluorescein (eosin), specific for bromine, on the addition of zinc chloride and fluorescein (compare p. 145). Upon addition of alkali bromide (formation of bromine) hypochlorite shows the same behavior of hypobromite. 

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