Hydrogen bromide

Hydrogen bromide

Names
Preferred IUPAC name Hydrogen bromide[citation needed]
Systematic IUPAC name Bromane[1]
Identifiers
CAS Number	10035-10-6 Y
3D model (JSmol)	Interactive image
Beilstein Reference	3587158
ChEBI	CHEBI:47266 Y
ChEMBL	ChEMBL1231461 N
ChemSpider	255 Y
ECHA InfoCard	100.030.090
EC Number	233-113-0
KEGG	C13645 N
MeSH	Hydrobromic+Acid
PubChem CID	260
RTECS number	MW3850000
UNII	3IY7CNP8XJ N
UN number	1048
InChI InChI=1S/BrH/h1H Y Key: CPELXLSAUQHCOX-UHFFFAOYSA-N Y
SMILES Br
Properties
Chemical formula	HBr
Molar mass	80.91 g/mol
Appearance	Colorless gas
Odor	Acrid
Density	3.6452 kg/m3 (0 °C, 1013 mbar)[2]
Melting point	−86.9 °C (−124.4 °F; 186.2 K)
Boiling point	−66.8 °C (−88.2 °F; 206.3 K)
Solubility in water	221 g/100 mL (0 °C) 204 g/100 mL (15 °C) 193 g/100 mL (20 °C) 130 g/100 mL (100 °C)
Solubility	Soluble in alcohol, organic solvents
Vapor pressure	2.308 MPa (at 21 °C)
Acidity (pKa)	−8.8 (±0.8);[3] ~−9[4]
Basicity (pKb)	~23
Conjugate acid	Bromonium
Conjugate base	Bromide
Refractive index (nD)	1.325[citation needed]
Structure
Molecular shape	Linear
Dipole moment	820 mD
Thermochemistry
Heat capacity (C)	350.7 mJ/(K·g)
Std molar entropy (So298)	198.696–198.704 J/(K·mol)[5]
Std enthalpy of formation (ΔfHo298)	−36.45...−36.13 kJ/mol[5]
Hazards
Safety data sheet	hazard.com physchem.ox.ac.uk
GHS pictograms
GHS signal word	Danger
GHS hazard statements	H314, H335
GHS precautionary statements	P261, P280, P305+351+338, P310
NFPA 704	0 3 0 COR
Lethal dose or concentration (LD, LC):
LC50 (median concentration)	2858 ppm (rat, 1 h) 814 ppm (mouse, 1 h)[7]
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 3 ppm (10 mg/m3)[6]
REL (Recommended)	TWA 3 ppm (10 mg/m3)[6]
IDLH (Immediate danger)	30 ppm[6]
Related compounds
Related compounds	Hydrogen fluoride Hydrogen chloride Hydrogen iodide Hydrogen astatide
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

Hydrogen bromide is the diatomic molecule with the formula HBr. It is a colorless compound and a hydrogen halide. Hydrobromic acid is a solution of HBr in water. Both the anhydrous and aqueous solutions of HBr are common reagents in the preparation of bromide compounds.

HBr is very soluble in water, forming hydrobromic acid solution, 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. Boiling less concentrated solutions releases H₂O until the constant-boiling mixture composition is reached.

Contents

• 
  1 Uses of HBr
  
  
  
  • 
    1.1 Other reactions
    
  
  
  • 
    1.2 Potential applications
    
  
  
  
  


• 
  2 Industrial preparation
  


• 
  3 Laboratory synthesis
  


• 
  4 Safety
  


• 
  5 References
  

Uses of HBr

Hydrogen bromide and hydrobromic acid are important reagents in the production of inorganic and organic bromine compounds.^[8] The free-radical addition of HBr to alkenes gives alkyl bromides:

RCH=CH₂ + HBr → R−CHBr−CH₃

These alkylating agents are precursors to fatty amine derivatives. Similar free radical addition to allyl chloride and styrene gives 1-bromo-3-chloropropane and phenylethylbromide, respectively.

Hydrogen bromide reacts with dichloromethane to give bromochloromethane and dibromomethane, sequentially:

HBr + CH₂Cl₂ → HCl + CH₂BrCl

HBr + CH₂BrCl → HCl + CH₂Br₂

Allyl bromide is prepared by treating allyl alcohol with HBr:

CH₂=CHCH₂OH + HBr → CH₂=CHCH₂Br + H₂O

Other reactions

Although not widely used industrially, HBr adds to alkenes to give bromoalkanes, an important family of organobromine compounds. Similarly, HBr adds to haloalkene to form a geminal dihaloalkane. (This type of addition follows Markovnikov's rule):

RC(Br)=CH₂ + HBr → RC(Br₂)−CH₃

HBr also adds to alkynes to yield bromoalkenes. The stereochemistry of this type of addition is usually anti:

RC≡CH + HBr → RC(Br)=CH₂

Also, HBr is used to open epoxides and lactones and in the synthesis of bromoacetals. Additionally, HBr catalyzes many organic reactions.^{[9][10][11][12]}

Potential applications

HBr has been proposed for use in a utility-scale flow-type battery.^[13]

Industrial preparation

Hydrogen bromide (along with hydrobromic acid) is produced by combining hydrogen and bromine at temperatures between 200 and 400 °C. The reaction is typically catalyzed by platinum or asbestos.^[10][14]

Laboratory synthesis

HBr can be synthesized by a variety of methods. It may be prepared in the laboratory by distillation of a solution of sodium bromide or potassium bromide with phosphoric acid or sulfuric acid:^[15]

KBr + H₂SO₄ → KHSO₄ + HBr

Concentrated sulfuric acid is less effective because it oxidizes HBr to bromine:

2 HBr + H₂SO₄ → Br₂ + SO₂ + 2 H₂O

The acid may be prepared by:

• reaction of bromine with water and sulfur:^[15]

  2 Br₂ + S + 2 H₂O → 4 HBr + SO₂
  

  
  


• bromination of tetralin:^[15]

  C₁₀H₁₂ + 4 Br₂ → C₁₀H₈Br₄ + 4 HBr

  
  


• reduction of bromine with phosphorous acid:^[10]

  Br₂ + H₃PO₃ + H₂O → H₃PO₄ + 2 HBr

  
  

Anhydrous hydrogen bromide can also be produced on a small scale by thermolysis of triphenylphosphonium bromide in refluxing xylene.^[9]

Hydrogen bromide prepared by the above methods can be contaminated with Br₂, which can be removed by passing the gas through a solution of phenol at room temperature in tetrachloromethane or other suitable solvent (producing 2,4,6-tribromophenol and generating more HBr in the process) or through copper turnings or copper gauze at high temperature.^[14]

Safety

HBr is highly corrosive and irritating to inhalation.

References

1. 
   ^ "Hydrobromic Acid - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 10 November 2011..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"""""""'""'"}.mw-parser-output .citation .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
   


2. 
   ^ Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
   


3. 
   ^ Trummal, Aleksander; Lipping, Lauri; Kaljurand, Ivari; Koppel, Ilmar A; Leito, Ivo (2016). "Acidity of Strong Acids in Water and Dimethyl Sulfoxide". The Journal of Physical Chemistry A. 120 (20): 3663. doi:10.1021/acs.jpca.6b02253. PMID 27115918.
   


4. 
   ^ Perrin, D. D. Dissociation constants of inorganic acids and bases in aqueous solution. Butterworths, London, 1969.
   


5. 
   ^ ^ab Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. ISBN 0-618-94690-X.
   


6. 
   ^ ^abc NIOSH Pocket Guide to Chemical Hazards. "#0331". National Institute for Occupational Safety and Health (NIOSH).
   


7. 
   ^ "Hydrogen bromide". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
   


8. 
   ^ Dagani, M. J.; Barda, H. J.; Benya, T. J.; Sanders, D. C., "Bromine Compounds", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a04_405CS1 maint: Multiple names: authors list (link)
   


9. 
   ^ ^ab Hercouet, A.; LeCorre, M. (1988) Triphenylphosphonium bromide: A convenient and quantitative source of gaseous hydrogen bromide. Synthesis, 157–158.
   


10. 
    ^ ^abc Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements; Butterworth-Heineman: Oxford, Great Britain; 1997; pp. 809–812.
    


11. 
    ^ Carlin, William W. U.S. Patent 4,147,601, April 3, 1979.
    


12. 
    ^ Vollhardt, K. P. C.; Schore, N. E. Organic Chemistry: Structure and Function; 4th Ed.; W. H. Freeman and Company: New York, NY; 2003.
    


13. 
    ^ http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/30535ag.pdf
    


14. 
    ^ ^ab Ruhoff, J. R.; Burnett, R. E.; Reid, E. E. "Hydrogen Bromide (Anhydrous)" Organic Syntheses, Vol. 15, p. 35 (Coll. Vol. 2, p. 338).
    


15. 
    ^ ^abc M. Schmeisser "Chlorine, Bromine, Iodine" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 282.
    

v t e Hydrogen compounds

H3AsO3 H3AsO4 HArF HAt HSO3F HBF4 HBr HBrO HBrO2 HBrO3 HBrO4 HCl HClO HClO2 HClO3 HClO4 HCN HCNO H2CrO4/H2Cr2O7 H2CO3 H2CS3 HF HFΟ HI HIO HIO2 HIO3 HIO4 HMnO4 H2MoO4 HNC NaHCO3 HNCO HNO HNO2 HNO3 H2N2O2 HNO5S H3NSO3 H2O H2O2 H2O3 H3PO2 H3PO3 H3PO4 H4P2O7 H5P3O10 H2PtCl6 H2S H2S2 H2Se H2SeO3 H2SeO4 H4SiO4 H2SiF6 HSCN HNSC H2SO3 H2SO4 H2SO5 H2S2O3 H2S2O6 H2S2O7 H2S2O8 CF3SO3H H2Te H2TeO3 H6TeO6 H4TiO4 H2Po HCo(CO)4

v t e Bromine compounds
AgBr AlBr3 AmBr3 AsBr3 AuBr3 BBr3 B2Br4 BaBr2 BeBr2 BiBr3 BrCl CsBr BrF3 BrF5 HBr IBr KBr LiBr BrN3 NaBr BrO2 RbBr TlBr CaBr2 CdBr2 CoBr2 CuBr2 EuBr2 FeBr2 GeBr2 HgBr2 Hg2Br2 MgBr2 MnBr2 NiBr2 Br2O Br2O3 Br2O5 PbBr2 PdBr2 PtBr2 RaBr2 S2Br2 Se2Br2 SnBr2 SrBr2 TeBr2 YbBr2 ZnBr2 CeBr3 CrBr3 CsBr3 DyBr3 ErBr3 EuBr3 FeBr3 GaBr3 GdBr3 HoBr3 InBr InBr3 IrBr3 LaBr3 LuBr3 MoBr3 NBr3 NdBr3 PBr3 PrBr3 ReBr3 SbBr3 SmBr3 TbBr3 TmBr3 UBr3 VBr3 YBr3 YbBr3 GeBr4 HfBr4 PbBr4 SeBr4 SiBr4 SnBr4 TeBr4 ThBr4 TiBr4 UBr4 WBr4 ZrBr4 NbBr5 PBr5 TaBr5 UBr5 WBr5 CBr4 CrBr2 DyBr2 HfBr2 HfBr3
Chemical formulas

v t e Binary compounds of hydrogen
Alkali metal hydrides	LiH NaH KH RbH CsH	Lithium hydride, LiH ionic metal hydride Beryllium hydride Left (gas phase): BeH2 covalent metal hydride Right: (BeH2)n (solid phase) polymeric metal hydride Borane and diborane Left: BH3 (special conditions), covalent metalloid hydride Right: B2H6 (standard conditions), dimeric metalloid hydride Methane, CH4 covalent nonmetal hydride Ammonia, NH3 covalent nonmetal hydride Water, H2O covalent nonmetal hydride Hydrogen fluoride, HF covalent nonmetal hydride
Alkaline earth hydrides	Monohydrides BeH MgH CaH SrH BaH Dihydrides BeH2 MgH2 CaH2 SrH2 BaH2
Group 13 hydrides	Boranes BH3 B2H6 B2H2 B2H4 B4H10 B5H9 B5H11 B6H10 B6H12 B10H14 B18H22 Alanes AlH3 Al2H6 Gallanes GaH3 Ga2H6 Indiganes InH3 In2H6 Thallanes TlH3 Tl2H6
Group 14 hydrides	Linear alkanes CH4 C2H6 C3H8 C4H10 C5H12 C6H14 C7H16 C8H18 C9H20 C10H22 more... Linear alkenes C2H4 C3H6 C4H8 C5H10 C6H12 C7H14 C8H16 C9H18 C10H20 more... Linear alkynes C2H2 C3H4 C4H6 C5H8 C6H10 C7H12 C8H14 C9H16 C10H18 more... Silanes SiH4 Si2H6 Si3H8 Si4H10 Si5H12 Si6H14 Si7H16 Si8H18 Si9H20 Si10H22 more... Silenes Si2H4 Silynes Si2H2 SiH Germanes GeH4 Ge2H6 Ge3H8 Ge4H10 Ge5H12 Stannanes SnH4 Sn2H6 Plumbanes PbH4 CH CH2 CH3 C2H Cycloalkanes Cycloalkenes Annulenes Many more
Pnictogen hydrides	Azanes NH3 N2H4 N3H5 N4H6 N5H7 N6H8 N7H9 N8H10 N9H11 N10H12 more... Azenes N2H2 N3H3 N4H4 Phosphanes PH3 P2H4 P3H5 P4H6 P5H7 P6H8 P7H9 P8H10 P9H11 P10H12 more... Phosphenes P2H2 P3H3 P4H4 Arsanes AsH3 As2H4 Stibanes SbH3 Bismuthanes BiH3 HN3 NH radical
Hydrogen chalcogenides	Polyoxidanes H2O H2O2 H2O3 H2O4 H2O5 H2O6 H2O7 H2O8 H2O9 H2O10 more... Polysulfanes H2S H2S2 H2S3 H2S4 H2S5 H2S6 H2S7 H2S8 H2S9 H2S10 more... Selanes H2Se H2Se2 Tellanes H2Te H2Te2 Polanes PoH2 HO HO2 HO3 H2O+–O– H2S=S (HS)2S+–S– HS HDO D2O T2O
Hydrogen halides	HF HCl HBr HI HAt
Transition metal hydrides	ScH2 YH2 YH3 TiH2 ZrH2 HfH2 VH VH2 NbH NbH2 TaH CrH CrH2 CrHx NiH PdHx (x < 1) FeH FeH2 FeH5 CuH ZnH2 CdH2 HgH2
Lanthanide hydrides	LaH2 LaH3 LaH10 CeH2 CeH3 PrH2 PrH3 NdH2 NdH3 SmH2 SmH3 EuH2 GdH2 GdH3 TbH2 TbH3 DyH2 DyH3 HoH2 HoH3 ErH2 ErH3 TmH2 TmH3 YbH2 YbH2.5 LuH2 LuH3
Actinide hydrides	AcH2 ThH2 Th4H15 PaH3 UH3 NpH2 NpH3 PuH2 PuH3 AmH2 AmH3 CmH2

Authority control	GND: 4289691-5

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