Alkaline bromate oxidation with

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. 

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-... 

The use of bromine in alkaline media resulted in the formation of uronic acids.416,417 Oxidation to some non-uronic acid products, (carbonyl compounds) accompanied the major oxidation pathway.418-420 The 2,2,6,6-tetramethyl-l-piperidinyloxy-mediated oxidation by hypobromite was highly selective for the 6-OH groups of the glucose residues.421 Potassium bromate (HB1-O3) was also used.338 The kinetics of oxidation with bromine at pH 6-8 has been studied 422 It was observed that oxidation decreases the heat and temperature of gelation as the oxidation proceeds. Simultaneously, the molecular weight of starch and the viscosity of its aqueous solutions decreased. Subsequent reduction of the oxidation products increased the viscosity. Microscopic observations revealed that the starch granularity vanished at a low level of oxidation.423... 

A variable order with respect to pinacol concentration in its oxidation by acidic bromate catalyzed by Mn(II) has been interpreted " in terms of equilibria involving 1 1 and 1 2 complexes between Mn(II) and pinacol in which only the 1 1 complex is involved in oxidation with BrO J. Bromate oxidation of Ce(III) and Co(II) in the presence of cyclo-hexanediaminetetraacetate have been studied. Electron transfer between Br04 and tris complexes of Fe(II) and bipyridyl and o-phenanthroline requires initial dissociation of the chelate followed by rapid electron trans-fer. Oxidation of V(IV) by JV-bromosuccinimide in aqueous acetic/per-chloric acids is first order in oxidant and independent of acid. " " The mechanisms of oxidation of alcohols in alkaline AT-bromoacetamide have been studied. Controversy abounds concerning the nature of radical intermediates in JV-bromosuccinimide brominations. " " ... 

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. 

The finely divided metal is soluble in hypohalites if an excess of alkali is present. At red heat, the metal combines with C z to form the dichlondc. Ruthenium(VIIl) oxide is formed when an alkaline ruthenium solution is treated with a strong oxidant, such as chlorine, or bromate ion when the Ru is in acid solution,... 

Chloric acid, in conjunction with catalysts (particularly vanadium pentaoxide), is used for the oxidation of aldonic acids or lactones to the 2-glyculosonic acids. Thus, D-glucono-1,4-lactone (9) and potassium D-galactonate in methanol, in the presence of phosphoric acid and vanadium pentaoxide, are oxidized by chloric acid to methyl D-arabino-2-hexulosonate (10) and methyl D-/yxo-2-hexulosonate, respectively.38 At moderate temperatures in the absence of a catalyst, aldoses, ketoses, and sucrose are inert to the action of chlorates over a several weeks time period 39 bromates in alkaline solution also exert no oxidative action (Scheme 5). 

Cystine, which contains a disulfide bond, is reported to be the most numerous and reactive amino acid present in hair keratin. Disulfide bonds in cystine are reduced by mercaptans and phosphines, and oxidized by perborates, bromates, and bleach. These reactions result in structural rearrangements within keratin which may affect the physiochemical properties of hair, since disulfide bonds in cystine contribute to the stability of hair. For example, hydrogen peroxide bleaching of hair is an oxidative process which occurs readily in an alkaline medium. This results in the formation of perhydroxy anions which have been proposed to react with cystine to form cysteic acid residues. The process of bleaching results in the loss of approximately 15% of the cystine bonds originally present in keratin and may explain the increased permeability of bleached hair to chemicals. - ... 

Under given conditions, passivity is attained with increasing readiness in the order iron, cobalt, nickel iron is much more difficult to render passive than is nickel in a particular electrolyte. Metals of the iron group become passive more readily in alkaline than in acid solutions, and oxidizing agents, e.g., iodate, bromate, chlorate, chromate and nitrate, favor passivity chloride ions markedly inhibit the onset of passivity. Increase of temperature increases the c.d. required for the anode to become passive under a given set of conditions. 

Bromine (Br, at. mass 79.91) is a dark red-brown liquid. Saturated bromine water contains 3.6% (w/v) of bromine (at 20°C). Bromine forms bromide (Br) and hypobromite (BrO ) in alkaline solution. The most stable forms of bromine are bromide and bromate (BrOa ). Bromide has reducing properties, whereas bromine (Br2), hypobromite, and bromate are oxidants. Many bromides are sparingly soluble compounds, and soluble bromide complexes are formed with the same metals as form soluble chloride complexes. 

The oxidation of bromide to bromine, and the bromination of Phenol Red are carried out in a weakly alkaline medium [1], Calcium hypochlorite can be used as oxidizing agent. The periods of time specified for oxidation (2 min) and for bromination (4 min) must be adhered to strictly (see procedure below). With longer oxidation, bromine is oxidized to bromate. 

Oxidation of aliphatic aldehydes by benzyltrimethylammonium chlorobromate to the corresponding carboxylic acid proceeds via the transfer of a hydride ion from the aldehyde hydrate to the oxidant. The oxidation of aUyl alcohol with potassium bromate in the presence of osmium(Vin) catalyst in aqueous acidic medium is first order in bromate, Os(Vni) and substrate, but inverse fractional order in H+ the stoichiometry of the reaction is 2 3 (oxidantsubstrate). The active species of oxidant and catalyst in the reaction were understood to be BrOs and H2OSO5, respectively, which form a complex. Autocatalysis by Br, one of the products, was observed, and attributed to complex formation between Br and osmium(VIII). First-order kinetics each in BrOs, Ru(VI), and substrate were observed for the ruthenium(VI)-catalyzed oxidation of cyclopentanol by alkaline KBrOs containing Hg(OAc)2. A zero-order dependence on HO concentration was observed and a suitable mechanism was postulated. The oxidation reaction of aniUne blue (AB+) with bromate at low pH exhibits interesting non-linear phenomena. The depletion of AB+ in the presence of excess of bromate and acid occurs at a distinctly slow rate, followed by a very rapid reaction. A 12-step reaction mechanism, consistent with the reaction dynamics, has been proposed. The novel cyclohexane-l,4-dione-bromate-acid system has been shown to exhibit a rapid oscillatory redox reaction superimposed on a slower... 

Quantitative Determination of Free Chlorine. The gas mixture can be shaken with a potassium iodide solution, and the liberated iodine can be then determined by titration. Chlorine in alkaline solution can be reduced to chloride by potassium or sodium arsenite, and the arsenite can be then oxidized to arsenate. The end point is detected by spot tests with starch-iodide paper. Excess arsenite is back-titrated with acidified potassium bromate solution. Small amounts of chlorine, e.g. in drinking water, can be determined by photometric measurement of the yellow color produced by the reaction with o-tolidine in hydrochloric acid solution [281]. 

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