Hypobromous acid

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Hypobromous acid
Hypobromous acid.png
Hypobromous-acid-3D-vdW.png
   Hydrogen, H
   Oxygen, O
   Bromine, Br
Names
IUPAC name
Hypobromous acid
Other names
  • Bromanol
  • Bromic(I) acid
  • Bromooxidane
  • Hydroxidobromine
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.119.006 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/BrHO/c1-2/h2H Yes check.svgY
    Key: CUILPNURFADTPE-UHFFFAOYSA-N Yes check.svgY
  • InChI=1S/BrHO/c1-2/h2H
    Key: CUILPNURFADTPE-UHFFFAOYSA-N
  • InChI=1/BrHO/c1-2/h2H
    Key: CUILPNURFADTPE-UHFFFAOYAL
  • OBr
Properties
HOBr
Molar mass 96.911 g·mol−1
Density 2.470 g/cm3
Boiling point 20–25 °C (68–77 °F; 293–298 K)
Acidity (pKa)8.65 [1]
Conjugate base Hypobromite
Related compounds
Other cations
Sodium hypobromite
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hypobromous acid is an inorganic compound with chemical formula of H O Br . It is a weak, unstable acid. It is mainly produced and handled in an aqueous solution. It is generated both biologically and commercially as a disinfectant. Salts of hypobromite are rarely isolated as solids.

Contents

Synthesis and properties

Addition of bromine to water gives hypobromous acid and hydrobromic acid (HBr(aq)) via a disproportionation reaction.

Br2 + H2O HOBr + HBr

In nature, hypobromous acid is produced by bromoperoxidases, which are enzymes that catalyze the oxidation of bromide with hydrogen peroxide: [2] [3]

Br + H2O2HOBr + OH

Hypobromous acid has a pKa of 8.65 and is therefore only partially dissociated in water at pH 7. Like the acid, hypobromite salts are unstable and undergo a slow disproportionation reaction to yield the respective bromate and bromide salts.

3 BrO(aq) → 2 Br(aq) + BrO3(aq)

Its chemical and physical properties are similar to those of other hypohalites.

Uses

HOBr is used as a bleach, an oxidizer, a deodorant, and a disinfectant, due to its ability to kill the cells of many pathogens. The compound is generated in warm-blooded vertebrate organisms especially by eosinophils, which produce it by the action of eosinophil peroxidase, an enzyme which preferentially uses bromide. [4] Bromide is also used in hot tubs and spas as a germicidal agent, using the action of an oxidizing agent to generate hypobromite in a similar fashion to the peroxidase in eosinophils. It is especially effective when used in combination with its congener, hypochlorous acid.

Related Research Articles

<span class="mw-page-title-main">Bromine</span> Chemical element with atomic number 35 (Br)

Bromine is a chemical element; it has symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig and Antoine Jérôme Balard, its name was derived from Ancient Greek βρῶμος (bromos) 'stench', referring to its sharp and pungent smell.

Hydrobromic acid is an aqueous solution of hydrogen bromide. It is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C (255.7 °F) and contains 47.6% HBr by mass, which is 8.77 mol/L. Hydrobromic acid is one of the strongest mineral acids known.

<span class="mw-page-title-main">Silver chloride</span> Chemical compound with the formula AgCl

Silver chloride is an inorganic chemical compound with the chemical formula AgCl. This white crystalline solid is well known for its low solubility in water and its sensitivity to light. Upon illumination or heating, silver chloride converts to silver, which is signaled by grey to black or purplish coloration in some samples. AgCl occurs naturally as the mineral chlorargyrite.

<span class="mw-page-title-main">Hydrogen bromide</span> Chemical compound

Hydrogen bromide is the inorganic compound with the formula HBr. It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temperature. Aqueous solutions that are 47.6% HBr by mass form a constant-boiling azeotrope mixture that boils at 124.3 °C (255.7 °F). Boiling less concentrated solutions releases H2O until the constant-boiling mixture composition is reached.

A bromide ion is the negatively charged form (Br) of the element bromine, a member of the halogens group on the periodic table. Most bromides are colorless. Bromides have many practical roles, being found in anticonvulsants, flame-retardant materials, and cell stains. Although uncommon, chronic toxicity from bromide can result in bromism, a syndrome with multiple neurological symptoms. Bromide toxicity can also cause a type of skin eruption, see potassium bromide. The bromide ion has an ionic radius of 196 pm.

<span class="mw-page-title-main">Ammonium bromide</span> Chemical compound

Ammonium bromide, NH4Br, is the ammonium salt of hydrobromic acid. The chemical crystallizes in colorless prisms, possessing a saline taste; it sublimes on heating and is easily soluble in water. On exposure to air it gradually assumes a yellow color because of the oxidation of traces of bromide (Br) to bromine (Br2).

Cyanogen bromide is the inorganic compound with the formula (CN)Br or BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides, and synthesize other compounds. The compound is classified as a pseudohalogen.

<span class="mw-page-title-main">BCDMH</span> Chemical compound

1-Bromo-3-chloro-5,5-dimethylhydantoin is a chemical structurally related to hydantoin. It is a white crystalline compound with a slight bromine and acetone odor and is insoluble in water, but soluble in acetone.

<span class="mw-page-title-main">DBDMH</span> Chemical compound

DBDMH is an organic compound derived from the heterocycle called dimethylhydantoin. This white crystalline compound with a slight bromine odor is widely used as a disinfectant used for drinking water purification, recreational water treatment, as a bleaching agent in pulp and paper mills, and for treating industrial/commercial water cooling systems. Its action does not involve the use of hypochlorous acid.

<span class="mw-page-title-main">Hypobromite</span> Ion, and compounds containing the ion

The hypobromite ion, also called alkaline bromine water, is BrO. Bromine is in the +1 oxidation state. The Br–O bond length is 1.82 Å. Hypobromite is the bromine compound analogous to hypochlorites found in common bleaches, and in immune cells. In many ways, hypobromite functions in the same manner as hypochlorite, and is also used as a germicide and antiparasitic in both industrial applications, and in the immune system.

Bromine compounds are compounds containing the element bromine (Br). These compounds usually form the -1, +1, +3 and +5 oxidation states. Bromine is intermediate in reactivity between chlorine and iodine, and is one of the most reactive elements. Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X2/X couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V). Bromination often leads to higher oxidation states than iodination but lower or equal oxidation states to chlorination. Bromine tends to react with compounds including M–M, M–H, or M–C bonds to form M–Br bonds.

<span class="mw-page-title-main">Barium bromide</span> Chemical compound

Barium bromide is the chemical compound with the formula BaBr2. It is ionic and hygroscopic in nature.

<span class="mw-page-title-main">Bromous acid</span> Chemical compound

Bromous acid is the inorganic compound with the formula of HBrO2. It is an unstable compound, although salts of its conjugate base – bromites – have been isolated. In acidic solution, bromites decompose to bromine.

Haloperoxidases are peroxidases that are able to mediate the oxidation of halides by hydrogen peroxide. Both halides and hydrogen peroxide are widely available in the environment.

Organobromine chemistry is the study of the synthesis and properties of organobromine compounds, also called organobromides, which are organic compounds that contain carbon bonded to bromine. The most pervasive is the naturally produced bromomethane.

<span class="mw-page-title-main">Bromide peroxidase</span> Family of enzymes

Bromide peroxidase (EC 1.11.1.18, bromoperoxidase, haloperoxidase (ambiguous), eosinophil peroxidase) is a family of enzymes with systematic name bromide:hydrogen-peroxide oxidoreductase. These enzymes catalyse the following chemical reaction:

<span class="mw-page-title-main">Eosinophil peroxidase</span> Protein-coding gene in the species Homo sapiens

Eosinophil peroxidase is an enzyme found within the eosinophil granulocytes, innate immune cells of humans and mammals. This oxidoreductase protein is encoded by the gene EPX, expressed within these myeloid cells. EPO shares many similarities with its orthologous peroxidases, myeloperoxidase (MPO), lactoperoxidase (LPO), and thyroid peroxidase (TPO). The protein is concentrated in secretory granules within eosinophils. Eosinophil peroxidase is a heme peroxidase, its activities including the oxidation of halide ions to bacteriocidal reactive oxygen species, the cationic disruption of bacterial cell walls, and the post-translational modification of protein amino acid residues.

Sodium hypobromite is an inorganic compound with the chemical formula NaOBr. It is a sodium salt of hypobromous acid. It consists of sodium cations Na+ and hypobromite anions OBr. It is usually obtained as the pentahydrate, so the compound that is usually called sodium hypobromite actually has the formula NaBrO·5H2O. It is a yellow-orange solid that is soluble in water. It adopts a monoclinic crystal structure with a Br–O bond length of 1.820 Å. It is the bromine analogue of sodium hypochlorite, the active ingredient in common bleach. In practice the salt is usually encountered as an aqueous solution.

A hypohalous acid is an oxyacid consisting of a hydroxyl group single-bonded to any halogen. Examples include hypofluorous acid, hypochlorous acid, hypobromous acid, and hypoiodous acid. The conjugate base is a hypohalite. They can be formed by reacting the corresponding diatomic halogen molecule with water in the reaction:

A halous acid, also known as a halogenous acid, is an oxyacid consisting of a halogen atom in the +3 oxidation state single-bonded to a hydroxyl group and double-bonded to an oxygen atom. Examples include chlorous acid, bromous acid, and iodous acid. The conjugate base is a halite.

References

  1. Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 117. ISBN   0-08-029214-3. LCCN   82-16524.
  2. Ximenes, V. F., Morgon, N. H., & de Souza, A. R. (2015). Hypobromous acid, a powerful endogenous electrophile: Experimental and theoretical studies. Journal of inorganic biochemistry, 146, 61-68.
  3. Butler, Alison.; Walker, J. V. (1993). "Marine haloperoxidases". Chemical Reviews. 93 (5): 1937–1944. doi:10.1021/cr00021a014.
  4. Mayeno, AN; Curran, AJ; Roberts, RL; Foote, CS (1989). "Eosinophils preferentially use bromide to generate halogenating agents". The Journal of Biological Chemistry. 264 (10): 5660–8. doi: 10.1016/S0021-9258(18)83599-2 . PMID   2538427. Archived from the original on 2009-05-26. Retrieved 2008-01-12.