Alkaline bromate

Benzilic acid may be obtained in a high state of purity by the action of an alkaline bromate solution upon benzoin at 85-90° ... 

The oxidation of alkaline bromate by fluorine to perbromate is not smooth and small explosions may occur in the vapour above the solution. The reaction should not be run unattended. 

Direct conversion of a benzoin into the corresponding benzilic acid may be accomplished conveniently and in good yield by reaction with alkaline bromate solution at 85-90 °C (see Expt 6.144, Method 2). 

Osmium(VIII)-catalysed oxidation of alanine and proline by alkaline bromate in the presence of Hg(OAc)2, the scavenger for Br ion, was zero order in the substrate, first order in BrOj" and Os(VIII), and retarded by OH ions. ... 

The best method of generating perbromates, which were first made in 1968, involves the passage of fluorine into alkaline bromate ... 

Because they are unstable, hypobromites are usually prepared just before use for such jobs as textile bleaching and desizing. In alkaline solutions at 50—80°C bromine reacts to form bromide and bromate. This reaction is reversed in acidic solutions. 

Hypobromites, the salts of hypobromous acid, do not keep well because they gradually disproportionate to bromide and bromate. Solutions are best prepared as needed from bromine and alkafl with cooling. Because disproportionation is catalyzed by cobalt, nickel, and copper (70), these impurities should be avoided. SoHd alkaline earth hypobromites, or more properly, bromide hypobromites such as calcium bromide hypobromite [67530-61 CaBr(OBr), have been known for many years, but the pure crystalline hydrates sodium hypobromite pentahydrate [13824-96-9] NaOBr 5H20, and potassium hypobromite tribydrate [13824-97-0], KOBr 3H20, were not described until 1952 (71). Hypobromites are strong bleaching agents, similar to hypochlorites. 

Boiling the solution speeds the conversion of intermediate hypobromites and bromites to bromate. The less soluble bromate can be separated from the hahde by fractional crystallization. A method that is often more economical is the oxidation of bromides into bromates by hypochlorites in aqueous solution. This can be done by passing chlorine into an alkaline bromide solution (75) ... 

Disproportionation of X2 in hot alkaline solution has long been used to synthesize chlorates and bromates (see oxidation state diagrams, p. 855) ... 

The oxidizing power of the halate ions in aqueous solution, as measured by their standard reduction potentials (p. 854), decreases in the sequence bromate > chlorate > iodate but the rates of reaction follow the sequence iodate > bromate > chlorate. In addition, both the thermodynamic oxidizing power and the rate of reaction depend markedly on the hydrogen-ion concentration of the solution, being substantially greater in acid than in alkaline conditions (p, 855). 

The liberated bromine is carried by a stream of air into an alkaline solution of sodium carbonate where it dissolves as a mixture of bromide and bromate [the analogy of reaction (79)]. This last step serves to concentrate the product, and free bromine is obtained by subsequent acidification of the solution, through the reaction... 

A similar procedure may also be used for the determination of antimony(V), whilst antimony (III) may be determined like arsenic(III) by direct titration with standard iodine solution (Section 10.113), but in the antimony titration it is necessary to include some tartaric acid in the solution this acts as complexing agent and prevents precipitation of antimony as hydroxide or as basic salt in alkaline solution. On the whole, however, the most satisfactory method for determining antimony is by titration with potassium bromate (Section 10.133). 

A synthetically useful reaction has been reported between alkaline bromine water and dimethyl sulphoxide118, the product being the perbromosulphone (equation 36). A kinetic study of the oxidation of dimethyl sulphoxide by bromate ions, catalysed by ruthenium(III) salts, has also been published but no yield data are available119. 

Impurities in CL have also been destroyed by oxidation with ozone22 followed by distillation. Ozonation treatment of waste CL leaves no ionic impurities. However, the most commonly used oxidizing agents are potassium permanganate, perboric acid, perborate, and potassium bromate. Treatment of CL with these oxidizing agents is carried out in a neutral medium at 40-60°C. Strongly alkaline or acidic conditions accelerate the oxidation of CL to form isocyanates. Hie undesirable oxidation reaction is fast above pH 7 because of the reaction with isocyanate to form carbamic acid salts, which shifts the equilibrium to form additional isocyanate. 

Unstabilized hypobromite solutions are even more unstable than hypochlorite. Hypobromite disproportionates to bromate (Br03), a toxic and potentially carcinogenic compound, in alkaline conditions. The stabilizer in STABREX inhibits that process as shown in Table3. 

Intimate mixtures of chlorates, bromates or iodates of barium, cadmium, calcium, magnesium, potassium, sodium or zinc, with finely divided aluminium, arsenic, copper carbon, phosphorus, sulfur hydrides of alkali- and alkaline earth-metals sulfides of antimony, arsenic, copper or tin metal cyanides, thiocyanates or impure manganese dioxide may react violently or explosively, either spontaneously (especially in presence of moisture) or on initiation by heat, friction, impact, sparks or addition of sulfuric acid [1], Mixtures of sodium or potassium chlorate with sulfur or phosphorus are rated as being exceptionally dangerous on frictional initiation. 

A qualitative similarity to the aqueous chemistry of chlorine will be evident. For each oxoanion of chlorine, there is a corresponding bromine species, although perbromate salts form only under certain strongly oxidizing conditions (e.g., oxidation of bromate ion in alkaline solution with F2 or XeF2) and in fact were unknown until 1968. 

It is unstable to heat, neutral or alkaline pH, and can be easily leached out of foods. Thiamin is destroyed by sulfur dioxide (often used as a food preservative), potassium bromate (oxidizing agent used in bread) and by sodium bicarbonate (in chemically leavened breads). 

Ammonium bromide is formed by the direct union of the two gases and by the neutralization of hydrobromic acid with ammonia. C. E. Schonbein 1 made it along with the hypobromite (q.v.) and bromate, when ammonia is treated with bromine water until it reacts alkaline—some nitrogen is formed at the same time. 

Zinc Bromate. Zn(Br03)2.6H20 mw 429.28 white deliq crysts mp 100° sp grav 2.566. V sol in w. Prepn is by treating Zn oxide with bromine w. Intimate mixts of the bromate with finely divided Al, As, Cu, C, P, S hydrides of alkali and alkaline earth metals, Sb sulfide, metal cyanides, K thiocyanate or impure Mn dioxide can react explosively (spontaneously in the pre-... 

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