Bromamine Bromine

Antimicrobial efficacy is also affected by demand in the cooling water system, specifically demand exerted by ammonia. Chlorine reacts with ammonia to form chloramines, which are not as efficacious as hypochlorous acid or the hypochlorite ion in microbiological control. Bromine reacts with ammonia to form bromamines. Unlike chloramines, bromamines are unstable and reform hypobromous acid. 

Bromamines. Bromamide [14519-10-9] NH2Br, is formed from bromine andliquid ammonia ... 

Similar reactions occur with ammonia and HOBr (19—25), but since HOBr is a stronger electrophile than HOCl, formation rates are faster. Because of rapid bromine transfer between bromamines, equihbrium concentrations of the respective bromamines are obtained quickly. Mon ohrom amine predominates at basic pH at high N Br ratios. Below pH 8.5, NHBr2 and NBr predominate. Tribromamine formation is favored at lower pH and higher Br N ratios. The bromamines are less stable than chloramines but are better disinfectants. 

Efforts to raise the alpha-selectivity have been made. Thus nitration of anthraquinone using nitrogen dioxide and ozone has been reported (17). l-Amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) [116-81 -4] (8) is the most important intermediate for manufacturing reactive and acid dyes. Bromamine acid is manufactured from l-aminoanthraquinone-2-sulfonic acid [83-62-5] (19) by bromination in aqueous medium (18—20), or in concentrated sulfuric acid (21). l-Aminoanthraquinone-2-sulfonic acid is prepared from l-aminoanthraquinone by sulfonation in an inert, high boiling point organic solvent (22), or in oleum with sodium sulfate (23). 

Many anthraquinone reactive and acid dyes are derived from bromamine acid. The bromine atom is replaced with appropriate amines in the presence of copper catalyst in water or water—alcohol mixtures in the presence of acid binding agents such as alkaU metal carbonate, bicarbonate, hydroxide, or acetate (Ullmaim condensation reaction). 

As with chlorine-containing oxidants, JV-bromo species have been used to oxidize sulphoxides to sulphones (with no bromine incorporation) through the initial formation of a bromosulphonium ion, by nucleophilic attack of the sulphoxide sulphur atom on the electrophilic halogen atom. Such reactions involve JV-bromosuccinimide ° bromamine-T, iV-bromoacetamide ° and iV-bromobenzenesulphonamide. All reported studies were of a kinetic nature and yields were not quoted. In acid solution all oxidations occurred at or around room temperature with the nucleophilic attack on the electrophilic bromine atom being the rate-limiting step. In alkaline solution a catalyst such as osmium tetroxide is required for the reaction to proceed . ... 

Nucleophilic substitution reactions, to which the aromatic rings are activated by the presence of the carbonyl groups, are commonly used in the elaboration of the anthraquinone nucleus, particularly for the introduction of hydroxy and amino groups. Commonly these substitution reactions are catalysed by either boric acid or by transition metal ions. As an example, amino and hydroxy groups may be introduced into the anthraquinone system by nucleophilic displacement of sulfonic acid groups. Another example of an industrially useful nucleophilic substitution is the reaction of l-amino-4-bromoanthraquinone-2-sulfonic acid (bromamine acid) (76) with aromatic amines, as shown in Scheme 4.5, to give a series of useful water-soluble blue dyes. The displacement of bromine in these reactions is catalysed markedly by the presence of copper(n) ions. 

Inorganic bismuth compounds, 4 17—26 Inorganic bromamines, 13 101—104 Inorganic bromine compounds, 4 318-339 Inorganic cellulose esters, 5 394-412 physical properties, 5 402 103 preparation, 5 396-402 uses of, 5 402 08... 

Organic bromamines, 13 104-112 Organic bromine compounds, 4 340-362 aliphatic, 4 345-349 chemical reactions, 4 341—343 dyes and indicators, 4 361-362t, 362 flame retardants, 4 349, 354, 355—358t industrial chemical intermediates, 4 350—353t... 

Kinetic studies of the oxidation of aspirin by bromamine-T, A-bromosuccinimide (NBS), and A-bromophthalimide (NBP) support a mechanism in which the unpro-tonated oxidant is the active species. " The ultimate product of the reaction is 2,4,6-tribromophenol, which arises through decarboxylation, bromination and loss of acetic acid. The NBP and NBS oxidations of -hydroxy acids are found to be similar in mechanism. 

Bromamines, quickly formed in the presence of nitrogen compounds, remain as active biocides. As a result, breakpoint bromination is not relevant. Bromamines are relatively unstable reaction products (unlike chloramines) and quickly hydrolyze to re-form as HOBr. 

Bromine, although more volatile in cooling systems than generally supposed, is less volatile than chlorine (less than half as volatile). This often permits lower free halogen reserve and a less corrosive environment. In addition, bromamines are significantly less volatile... 

First, bromine chemistry works The combination of high pH activity, high bromamine activity, and a fast kill rate has given it a significant edge over chlorine chemistry. 

For bromine to act as a biocide in the most efficient manner, there must always be sufficient free chlorine available in the cooling water to enable HOBr to be formed from all the available bromine compounds (e.g., bromamines). This requires a higher ratio of total chlorine to bromine than normally available with other bromine technologies. 

The reactivity of sulfanilic acid towards haloamines, in alkaline solutions, follows the order BAB > bromamine-T > CAB > CAT. This has been attributed to the difference in the electrophilicities of Cl+ and Br+ ions and the van der Waal s radii of chlorine and bromine. A probable mechanism has been suggested.174... 

It is not possible to establish whether amines are preferentially brominated over organic substrates in the V-BrPO reactions. Bromamine buildup is not observed under V-BrPO-catalyzed conditions when an appropriate halogen acceptor is present, either because the organic substrate is brominated before bromamine formation or because the bromamine concentration never builds up to detectable levels because of very rapid substrate bromination by the bromamine. If bromination of mcd is carried out with peracetic acid as the source of peroxide and in the presence of 3 mM tris buffer, Br-tris is only observed after the mcd has been... 

The major utility of bromamines is in the selective ortho- bromination of phenols755. The high selectivity of N, A-dibromo-/ butylamine has been neatly demonstrated by Desmurs and colleagues756, who have selectively brominated eugenol at the 6 position without affecting the double bond (equation 101). 

Aqueous solutions of bromamine NH2Br are formed during the bromination of NH3 with hypobromite ... 

Fig. 14.18 compares the hypochlorous and hypobromous acid concentration at different pH [Marshall and Bott 1988]. It will be seen that the ionisation of hypobromous acid occurs at a higher pH than hypochlorous acid so that bromine may be used as a biocide at higher pH values than chlorine. If ammonia is present in the water, bromine reacts with the ammonia to form bromamines that are also very effective biocides compared to the corresponding chloramines. 

Low-level chlorination of 0.5-1.5 mg/1, resulting in a chlorine residual of 0.1 -0.2 mg/1, is used to reduce the degree of biofouling. In sea-water, chlorine oxidizes bromide, present at about 65 mg/1, to bromine, which also contributes to the generation of halogenated by-products [176]. The by-products include hypobromous acid, hypobromite, chloramines, bromamines, trihalomethanes, haloacetonitriles,haloacetic acids, and small amounts of halophenols. However, some haloforms and bromophenols as well as other organobromine compounds are also produced naturally in coastal waters [ 181,182]. Empirical equations for the disappearance of chlorine/bromine derived oxidants from brackish water have been published [183]. 

A convenient procedure for the aminobromination of electron-deficient olefins 90 using Bromamine-T (TsNBrNa) as nitrogen and bromine source promoted by (diacetoxyiodo)benzene has been developed [96]. This heavy-metal-free protocol is highly efficient and affords the vicinal bromamines 91 with excellent regio-and stereoselectivities (Scheme 3.35). 

It is manufactured by the reaction of 1-aminoanthraquinone with chloro-sulfonic acid to yield l-aminoanthraquinone-2-sulfonic acid from this, 1-amino-4-bromoanthraquinone-2-sulfonic acid can be obtained by the reaction with bromine, with ice cooling. Examples of dyes from bromamine acid are Alizarine Brilliant Blue R (Add Blue 62), which is obtained from bromamine acid by reac-... 

Chloramine-T and bromamine-T can also be used as the nitrene source in the copper-catalyzed aziridination but the transfer to olefins occurs with less efficiency. In this context, bromine and iodine are better catalysts. However, CuOTf... 

Reactions with ammonia and organic compounds. Hypobromous acid reacts with amines to form bromamines in a manner similar to ehorine. However bromamines are efficacious as sanitizers in recreational water, unlike chloramines which are biocidal, but of limited value due to their slow rate of kill. Additionally, bromamines are not irritating to the skin and eyes and do not possess a strong odor. Breakpoint bromination is not required. Re-oxidation of the inactive bromide ions will re-convert the salt to biocidal form (HOBr/OBr ). These qualities make bromine biocides much more favorable products for use in spas, relative to chlorine. Bromine products are primarily used for treating indoor pools and spas. Chemicals used for the neutralization of hypobromous acid are identieal to those used for hypochlorous acid. 

Test methods. The same direct and indirect test methods used for the measurement of chlorine residual can be used for measuring total bromine. The results of the chlorine assays must be multiplied by a factor of 2.25 to account for the differenee in the chlorine and bromine molecular weights. In bromine systems the only active reported is the total bromine. This is a reflection that combine bromine (bromamine) is efficacious. 

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