Hydrobromic acid

Hydrobromic acid
Names
	Other names Hydronium bromide
Identifiers
CAS Number	10035-10-6 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:47266 ;
ChEMBL	ChEMBL1231461;
ChemSpider	255 ;
ECHA InfoCard	100.240.772
EC Number	233-113-0;
Gmelin Reference	620
KEGG	C13645;
PubChem CID	260;
RTECS number	MW3850000;
UNII	3IY7CNP8XJ ;
UN number	1048 1788
	show InChI
	show SMILES
Properties
Chemical formula	HBr(aq)
Molar mass	80.91 g·mol−1
Appearance	colorless/faint yellow liquid
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 (pKa)	−9
Viscosity	0.84 cP (−75 °C)
Thermochemistry
Heat capacity (C)	29.1 J/(K·mol)
Std molar; entropy (So298)	198.7 J/(K·mol)
Std enthalpy of; formation (ΔfH⦵298)	−36.3 kJ/mol
Hazards
Safety data sheet	ICSC 0282
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H314, H335
GHS precautionary statements	P260, P261, P264, P271, P280, P301+330+331, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P363, P403+233, P405, P501
NFPA 704 (fire diamond)	3 0 0 ACID
Flash point	Non-flammable
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).
	(what is ?)
	Infobox references

Hydrobromic acid 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 and contains 47.6% HBr by mass, which is 8.77 mol/L. Hydrobromic acid has a pK_a of −9, making it a stronger acid than hydrochloric acid, but not as strong as hydroiodic acid. 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.^[2]

Synthesis[]

Hydrobromic acid can be prepared in the laboratory via the reaction of Br₂, SO₂, and water.^[3]

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.^[3] 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:^[4]

H₂SO₄ + KBr → KHSO₄ + HBr

Using more concentrated sulfuric acid or allowing the reaction solution to exceed 75 °C further oxidizes HBr to bromine gas. The acid is further purified by filtering out the KHSO₄ and by distilling off the water until the solution reaches an azeotrope (≈ 126 °C at 760 torr). The yield is approximately 85%.^[4]

Hydrobromic acid is available commercially in various concentrations and purities.

References[]

^ 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.
^ Jump up to: ^a ^b Scott, A. (1900). "Preparation of Pure Hydrobromic Acid". Journal of the Chemical Society, Transactions. 77: 648–651. doi:10.1039/ct9007700648.
^ Jump up to: ^a ^b Brauer, Georg (1963). Handbook of Preparative Inorganic Chemistry. 1 (2nd ed.). New York: Academic Press. p. 285. ISBN 978-0121266011.

External links[]

Media related to Hydrogen bromide at Wikimedia Commons

[1] Bell, R. P. The Proton in Chemistry, 2nd ed., Cornell University Press, Ithaca, NY, 1973.

[2] 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.

[scott-3] Jump up to: ^a ^b Scott, A. (1900). "Preparation of Pure Hydrobromic Acid". Journal of the Chemical Society, Transactions. 77: 648–651. doi:10.1039/ct9007700648.

[Georg-4] Jump up to: ^a ^b Brauer, Georg (1963). Handbook of Preparative Inorganic Chemistry. 1 (2nd ed.). New York: Academic Press. p. 285. ISBN 978-0121266011.

[1]

[2]

[3]

[4]

show Authority control
General	Integrated Authority File (Germany)
Other	Microsoft Academic