Hydrobromic acid

Aqueous solution of hydrogen bromide

Hydrobromic acid

Ball-and-stick model of hydrogen bromide

Ball-and-stick model of the hydronium cation

Names

IUPAC name

Bromane^[1]

Other names

Hydronium bromide
Bromhydric acid

Identifiers

CAS Number

10035-10-6^Y

3D model (JSmol)

Interactive image

ChEBI

CHEBI:47266^Y

ChEMBL

ChEMBL1231461

ChemSpider

255^Y

ECHA InfoCard

100.240.772

EC Number

233-113-0

Gmelin Reference

620

KEGG

C13645

PubChem CID

RTECS number

MW3850000

UNII

3IY7CNP8XJ^Y

UN number

1048 1788

InChI

InChI=1S/BrH/h1H^Y
Key: CPELXLSAUQHCOX-UHFFFAOYSA-N^Y
InChI=1/BrH/h1H
Key: CPELXLSAUQHCOX-UHFFFAOYAZ

SMILES

[OH3+].[Br-]

Properties

Chemical formula

HBr_(aq)

Molar mass

80.91 g·mol⁻¹

Appearance

colorless liquid
(impure samples can appear yellowish)

Odor

acrid

Density

1.49 g/cm³ (48% w/w aq.)

Melting point

−11 °C (12 °F; 262 K) (47–49% w/w aq.)

Boiling point

122 °C (252 °F; 395 K) at 700 mmHg (47–49% w/w aq.)

Solubility in water

221 g/100 mL (0 °C)
204 g/100 mL (15 °C)
130 g/100 mL (100 °C)

Acidity (pK_a)

−9^[2]

Viscosity

0.84 cP (−75 °C)

Thermochemistry

Heat capacity (C)

29.1 J/(K·mol)

Std molar
entropy (S^⦵₂₉₈)

198.7 J/(K·mol)

Std enthalpy of
formation (Δ_fH^⦵₂₉₈)

−36.3 kJ/mol

Hazards

GHS labelling:

Pictograms

Signal word

Danger

Hazard statements

H314, H335

Precautionary statements

P260, P261, P264, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P363, P403+P233, P405, P501

NFPA 704 (fire diamond)

ACID

Flash point

Non-flammable

Safety data sheet (SDS)

ICSC 0282

Related compounds

Other anions

Hydrofluoric acid
Hydrochloric acid
Hydroiodic acid

Related compounds

Hydrogen bromide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is ^YN ?)

Infobox references

Chemical compound

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.

Uses

Hydrobromic acid is mainly used for the production of inorganic bromides, especially the bromides of zinc, calcium, and sodium. It is a useful reagent for generating organobromine compounds. Certain ethers are cleaved with HBr. It also catalyzes alkylation reactions and the extraction of certain ores. Industrially significant organic compounds prepared from hydrobromic acid include allyl bromide, tetrabromobis(phenol), and bromoacetic acid. HBr almost uniquely participates in anti-Markovnikov hydrohalogenation of alkenes. The resulting 1-bromoalkanes are versatile alkylating agents, giving rise to fatty amines and quaternary ammonium salts.^[3]

Synthesis

Hydrobromic acid can be prepared in the laboratory via the reaction of Br₂, SO₂, and water.^[4]

{\ce {Br2 + SO2 + 2 H2O -> H2SO4 + 2 HBr}}

More typically laboratory preparations involve the production of anhydrous HBr, which is then dissolved in water.

Hydrobromic acid has commonly been prepared industrially by reacting bromine with either sulfur or phosphorus and water. However, it can also be produced electrolytically.^[4] It can also be prepared by treating bromides with non-oxidising acids like phosphoric or acetic acids.

Alternatively the acid can be prepared with dilute (5.8M) sulfuric acid and potassium bromide:^[5]

{\ce {H2SO4 + KBr -> KHSO4 + HBr}}

Using more concentrated sulfuric acid or allowing the reaction solution to exceed 75 °C further oxidizes HBr to elemental bromine. The acid is further purified by filtering out the KHSO₄ and by distilling off the water until the solution reaches an azeotrope (124.3 °C). The yield is approximately 85%.^[5]

Hydrobromic acid is available commercially in various concentrations and purities.

References

^ Favre, Henri A.; Powell, Warren H., eds. (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. Cambridge: The Royal Society of Chemistry. p. 131. ISBN 9781849733069.
^ Bell, R. P. The Proton in Chemistry, 2nd ed., Cornell University Press, Ithaca, NY, 1973.
^ Dagani, M. J.; Barda, H. J.; Benya, T. J.; Sanders, D. C. (2012). "Bromine Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a04_405. ISBN 978-3527306732.
^ ^a ^b Scott, A. (1900). "Preparation of Pure Hydrobromic Acid". Journal of the Chemical Society, Transactions. 77: 648–651. doi:10.1039/ct9007700648.
^ ^a ^b Brauer, Georg (1963). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). New York: Academic Press. p. 285. ISBN 978-0121266011.