Hypobromous acid, HOBr

The Addition of Hypobromous Acid HOBr) to Steroid Olefins... 

O O Write the chemical formula for the conjugate base of hypobromous acid, HOBr. Calculate Kb for this ion. 

Hypobromous acid HOBr results from the hydrolysis of bromine with H2O and exists only in aqueous solution. The compound finds limited use as a germicide and in water treatment also it can be used as an oxidizing or brominating agent in the production of certain organic compounds. Although hypobromous acid is low in bromine content, concentrated hypobromite solutions can be formed by adding bromine to cooled solutions of alkalis. 

The pH of 0.040 M hypobromous acid (HOBr) is 5.05. Set up the equilibrium equation for dissociation of HOBr, and calculate the value of the acid-dissociation constant. 

In contrast to MPO, eosinophil peroxidase (EPO) prefers to oxidize plasma level bromide (20-100 pM) to hypobromous acid (HOBr) and several biological targets are implicated, including nucleic acids and nucleosides (1480, 1482, 2376), proteins (1812, 1813, 2377, 2378), unsaturated fatty acids (2379), and low-density lipoprotein (2380, 2381). This EPO-dependent bromination is suggested to be involved in the pathogenesis of asthma (2382). Accordingly, both 3-bromotyrosine and 3,5-dibromotyrosine (1812,1813) are produced by EPO-induced bromination of tyrosine residues in lung tissue (1813, 2382). 

Hypobromous acid, HOBr, is found to be a poorer brominating agent than Bra at pll 3 (aqueous solutions). However, at higher concentrations of strong acids a third-order rate law is observed/... 

The incoming nucleophile may not necessarily be a second halogen atom. Hypobromous acid (HOBr), generated from iV-bromosuccinimide... 

Hypobromous acid, HOBr (1, 80). Erickson and Kim1 generated hypobromous acid from NBS and water and showed that it reacts with methylenecyclobutane (1, Aldrich) to give l-(bromomethyl)cyclobutanol (2) in 78% yield of about 90% purity. The reaction thus is regioselective. 

Hypochlorous acid Chlorous acid HOCl HOCIO (HCIO2) Hypobromous acid HOBr Hypoiodous acid HOI ... 

Treatment of nitroxides with strong acids such as toluenesulfonic acid or perchloric acid facilitates disproportionation to form one oxoammonium salt in situ for every two equivalents of starting nitroxide. Under strongly acidic conditions, secondary alcohols are efficiently oxidized to ketones, whereas primary alcohols are much slower to react [33]. The reaction mechanism [31] is most likely that shown in Scheme 15. A kinetic isotope effect [kn/ku = 3.1) supports deprotonation of the alpha hydrogen as the rate limiting step [34]. The use of an additional oxidant such as bleach (NaOCl) or hypobromous acid (HOBr) or hypochlorous acid (HOCl) generated in situ from bromide or chloride ion [35] can facilitate the reaction by rapidly reforming the oxoammonium species under the reaction conditions. This allows the nitroxide to be utilized in catalytic amounts. Recently, Bobbitt [36] has... 

Hypobromous acid (HOBr) then presumably acts as the brominating agent ... 

It is known that dissolving chlorine in water leads to a solution that contains hypochlorous acid (HOCl) and bromine dissolved in water contains hypobromous acid (HOBr). In one experiment, 1-pentene is mixed with chlorine and water (HOCl in aqueous media) and the major product is l-chloro-2-pentanol (48), in 43% isolated yield. ° In the previous section, chlorine reacted with 1-pentene in a nonaqueous solvent such as carbon tetrachloride to give a dichloride. To ascertain why this reaction is different, the first useful observation is that HOCl is in solution rather than Cl-Cl. The polarization of HOCl is HO -Cl, where chlorine is the electrophilic atom. The 7t-bond of an alkene should react with the positive chlorine atom, and cleavage of the Cl-H bond will give hydroxide ion, which is a... 

The pH of a 0.063-M solution of hypobromous acid (HOBr but usually written HBrO) is 4.95. Calculate K. ... 

Isoflavones have been shown to be beneficial in several chronic diseases in which oxidants are involved. Isoflavones are weak antioxidants when tested in vitro in die context of scavenging lipid peroxyl radicals. However, at sites of mflammation proinflammatory oxidants such as peroxynitrite (ONOO"), hypochlorous acid (HOCl), and hypobromous acid (HOBr) are formed that may also react widi isoflavones. We present evidence herein, using reverse-phase HPLC-mass spectrometry and proton NMR, that at concmitrations of diese oxidants formed at these local sites, nitration, chlorination, and bromination of isoflavones occurs. 

DBDMH and BCDMH. These slow-dissolving tablets are used in either a floater or in-line erosion feeder. When bromine tablets are added to water, hypobromous acid (HOBr) is produced along with bromide ion (Br ). The bromide ion is ineffective in pool sanitation. The bromide ion in a pool can be activated, or reactivated, to hypobromous acid using chlorine, ozone or more commonly by the use of potassium monopersulfate. 

Hypobromous acid. HOBr (hypobromous acid) is produced by reacting NaBr (available as a Nalco product) with HOCl (either from bleach or chlorine gas). Therefore, a dual feeding system is required. Chlorine dioxide will not activate NaBr. 

Hypobromous acid (HOBr) and all three bromoamines species (NH2Br, NHBr2, NBra) are analyzed as a sum parameter and hypochlorous add (HCXZl), monochloramine (NH2CI), and chlorine dioxide (CIQ2) can be determined selectively. However, no distinction is possible between HOCl and the active bromine spedes. Free chlorine and NH2CI can be measured in the presence of ozone. The method is therefore suitable if combinations of disinfectants are used, such as chlorine/chlorine dioxide or chlorine/ ozone. In natural waters, the method provides a detection limit for all chlorine/bromine species of less than 0.1 mM. The oxidation reaction with ABTS is fast and has a known stoichiometry therefore, a direct calculation of the analyte concentration using the molar absorptivity of the colored oxidation produd is possible. 

The brominated polymer is then hydrolysed rapidly with water to produce hypobromous acid (HOBr) as follows ... 

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