Bromates preparation

Solutions of lead acetate and potassium bromate precipitate the less soluble lead bromate. It is possible for the double salt Pb(Br03)2.Pb(OCOCH3)2 to be formed in this preparation, and this double salt explodes violently at about 165°, or even at room temperature upon percussion. Two fatal accidents have occurred by explosions of Pb(Br03)2 due to the double salt impurity present, and lead(II) bromate prepared in this way should be treated with extreme carei s. An alternative synthesis involves treatment of lead carbonate with bromic acid to form Pb(Br03)2. H20124. 

Chlorine, bromine and iodine form halic(V) acids but only iodic(V) acid, HIO3, can be isolated. Solutions of the chloric) V) and bromic) V) acids can be prepared by the addition of dilute sulphuric acid to barium chlorate(V) and bromate(V) respectively, and then filtering (cf. the preparation of hydrogen peroxide). These two acids can also be prepared by decomposing the corresponding halic(I) acids, but in this case the halide ion is also present in the solution. 

Ha.la.tes, Silver chlorate, AgClO, silver bromate, AgBrO, and silver iodate, AglO, have been prepared. The halates may decompose explosively if heated. 

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. 

Another method for preparing alkah bromates is by electrolysis of bromine in alkah solutions. Anodes coated with Pb02 are used and a small amount of dichromate is added to prevent reduction of BrO at the cathode (76). 

Bromates and iodates are prepared on a much smaller scale, usually by chemical oxidation. For example, Br is oxidized to Br03 by aqueous hypochlorite (conveniently effected by passing... 

Bromination of di-2-thienylmethane is best achieved with a bro-mide-bromate mixture in a heterogenous system. Conventional bromination with bromine in CCU was accompanied by marked tar formation. Bromination occurs in the 5- and 5 -positions of the rings as proved by the preparation of di-(5-bromo-2-thienyl) methane... 

To determine the purity of a sample of arsenic(III) oxide follow the general procedure outlined in Section 10.127 but when the 25 mL sample of solution is being prepared for titration, add 25 mL water, 15 mL of concentrated hydrochloric acid and then two drops of indicator solution (xylidine ponceau or naphthalene black 12B see Section 10.125). Titrate slowly with the standard 0.02M potassium bromate with constant swirling of the solution. As the end point approaches, add the bromate solution dropwise with intervals of 2-3 seconds between the drops until the solution is colourless or very pale yellow. If the colour of the indicator fades, add another drop of indicator solution. (The immediate discharge of the colour indicates that the equivalence point has been passed and the titration is of little value.)... 

Procedure. Prepare an approx. 0.02M standard solution of potassium bromate by weighing accurately about 1.65 g of the analytical grade reagent, dissolving it in water and making it up to 500 mL in a graduated flask (Note 2). 

Fraser CA, Gardner GJ, Maxwell PS, Kubwabo C, Guevremont R, Siu KWM, and Berman SS (1995) Preparation and certification of a biological reference material (CARP-i) for polychlorinated dibenzo-p-dioxin and dibenzofuran congeners. Fresenius J Anal Chem 352 143-147. Gahr A, Huber N, and Niessner R (1998) Fluorimetric determination of bromate by ion-exchange separation and post-column derivatization. Mikrochrm Acta 129 281-290. 

The compound (formulated as the double salt, (fuel + oxidant), rather than the mixed salt) may be formed during the preparation of lead bromate from lead acetate and... 

MRH Barium chlorate 5.06/83, calcium chlorate 5.61/77, potassium chlorate 6.07/76, sodium bromate 4.98/80, sodium chlorate 7.32/75, zinc chlorate 6.11/76 Dry finely divided mixtures of red (or white) phosphorus with chlorates, bromates or iodates of barium, calcium, magnesium, potassium, sodium or zinc will readily explode on initiation by friction, impact or heat. Fires have been caused by accidental contact in the pocket between the red phosphorus in the friction strip on safety-match boxes and potassium chlorate tablets. Addition of a little water to a mixture of white or red phosphorus and potassium iodate causes a violent or explosive reaction. Addition of a little of a solution of phosphorus in carbon disulfide to potassium chlorate causes an explosion when the solvent evaporates. The extreme danger of mixtures of red phosphorus (or sulfur) with chlorates was recognised in the UK some 50 years ago when unlicenced preparation of such mixtures was prohibited by Orders in Council. 

Procedure Transfer an accurately measured volume of about 30.0 ml of 0.1 N potassium bromate solution into a 250 ml iodine flask. Add to it 3.0 g potassium iodide, followed by 3.0 ml of potassium iodide, followed by 3.0 ml of hydrochloric acid. Mix the contents thoroughly and allow it to stand for 5 minutes with its stopper in position. Titrate the liberated iodine with previously standardized 0.1 N sodium thiosulphate, using 3.0 ml of freshly prepared starch solution as an indicator at the end-point. Carry out a blank run using the same quantities of the reagents and incorporate the necessary corrections, if any. Each ml of 0.1 N sodium thiosulphate is equivalent to 0.002784 g of KBr03. 

Procedure Weigh accurately 0.5 g of phenol and dissolve in sufficient water to produce 500 ml in a volumetric flask. Mix 25.0 ml of this solution with 25.0 ml of 0.1 N potassium bromate in a 250 ml iodine flask and add to it 1 g of powdered KI and 10.0 ml of dilute hydrochloric acid. Moisten the glass stopper with a few drops of KI solution and place it in position. Set it aside in a dark place for 20 minutes while shaking the contents frequently in between. Add to it 10 ml of KI solution, shake the contents thoroughly and allow it to stand in the dark for a further duration of 5 minutes. Wash the stopper and neck of the flask carefully with DW, add 10 ml chloroform and titrate with the liberated iodine with 0.1 N sodium thiosulphate using freshly prepared starch as an indicator. Carry out a blank titration simultaneously and incorporate any necessary correction, if required. Each ml of 0.1 N potassium bromate is equivalent to 0.001569 g of C6H60. 

Several explosive salts including the acetylide, azide, borate, bromate, chlorate, chromate, iodate (and ammonium iodate double salt), nitrite, perchlorate (and ammonium perchlorate double salt), periodate, permanganate, picrate and trinitrobenzoate were prepared. The 3 latter salts and the acetylide, azide and bromate are impact-sensitive detonators [1], It appears probable that many of the explosively unstable compounds [2], formed in various ways from interaction of mercury or its compounds with ammonia or its salts, may have the common polymeric structure now recognised for Millon s base [3], This is a silica-like network of N+ and Hg in 4- and 2-coordination, respectively, with OH and water in the interstitial spaces. Individually indexed compounds are Poly(dimercuryimmonium acetylide)... 

If the sample contains a lot of organic matter and no free bromine remains a further 2 ml of the potassium bromate/hromide reagent should be added. A blank containing twice the normal amount of this reagent should also then be prepared. 

Bromic acid is prepared by adding sulfuric acid to barium bromate. 

Potassium bromide also can be prepared by treating iron turnings with a 35 wt% aqueous solution of bromine. The product ferrosoferric bromide is boded in potassium carbonate solution containing a slight excess of 15% potassium carbonate (Dancy, W.B. 1980. Potassium Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3 i ed. p. 963. New York Wiley Interscience). The method does not involve bromate formation. The second step of the process may be represented in the foUowing reaction ... 

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