Boron tribromide

Short description: Chemical compound

Boron tribromide

Names
IUPAC name

Boron tribromide

Other names

Tribromoborane, Boron bromide

Identifiers

CAS Number

* 10294-33-4 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 16787736 Y

EC Number |

* 233-657-9

PubChem CID

* 25134

RTECS number |

* ED7400000

UNII |

* A453DV9339 N

UN number | 2692

InChI

* InChI=1S/B.3BrH/h;3*1H/q+3;;;/p-3 Y

Key: LKBREHQHCVRNFR-UHFFFAOYSA-K Y

* InChI=1/BBr3/c2-1(3)4

Key: ILAHWRKJUDSMFH-UHFFFAOYAA

* InChI=1/B.3BrH/h;3*1H/q+3;;;/p-3

Key: LKBREHQHCVRNFR-DFZHHIFOAX

SMILES

* BrB(Br)Br

Properties

Chemical formula

| BBr3
Molar mass | 250.52 g·mol−1
Appearance  | Colorless to amber liquid
Odor | Sharp and irritating[1]
Density | 2.643 g/cm3
Melting point |  −46.3 °C (−51.3 °F; 226.8 K)
Boiling point |  91.3 °C (196.3 °F; 364.4 K)

Solubility in water

| Reacts violently with water and other protic solvents
Solubility | Soluble in CH2Cl2, CCl4
Vapor pressure | 7.2 kPa (20 °C)

Refractive index (nD)

| 1.00207
Viscosity | 7.31 x 10−4 Pa s (20 °C)
Thermochemistry

Heat capacity (C)

| 0.2706 J/K

Std molar
entropy (S ~~o~~ 298)

| 228 J/mol K

Std enthalpy of
formation (ΔfH⦵298)

| -0.8207 kJ/g
Hazards
Main hazards | Reacts violently with water, potassium, sodium, and alcohols; attacks metals, wood, and rubber[1]
Safety data sheet | ICSC 0230
GHS pictograms |
GHS Signal word | DANGER

GHS hazard statements

| H330, H300, H314 Within the European Union, the following additional hazard statement (EUH014) must also be displayed on labeling: Reacts violently with water.
NFPA 704 (fire diamond)  |

~~W~~

Flash point |  Noncombustible[1]
NIOSH (US health exposure limits):

PEL (Permissible)

| None[1]

REL (Recommended)

| C 1 ppm (10 mg/m3)[1]

IDLH (Immediate danger)

| N.D.[1]
Related compounds

Related compounds

| Boron trifluoride
Boron trichloride
Boron triiodide

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

Boron tribromide, BBr3, is a colorless, fuming liquid compound containing boron and bromine. Commercial samples usually are amber to red/brown, due to weak bromine contamination. It is decomposed by water and alcohols.[2]

## Contents

* 1 Chemical properties
* 2 Synthesis
* 3 History
* 4 Applications
* 5 See also
* 6 References
* 7 Further reading
* 8 External links

## Chemical properties

Boron tribromide is commercially available and is a strong Lewis acid.

It is an excellent demethylating or dealkylating agent for the cleavage of ethers, also with subsequent cyclization, often in the production of pharmaceuticals.[3]

The mechanism of dealkylation of tertiary alkyl ethers proceeds via the formation of a complex between the boron center and the ether oxygen followed by the elimination of an alkyl bromide to yield a dibromo(organo)borane.

ROR + BBr3 → RO+(−BBr3)R → ROBBr2 \+ RBr

Aryl methyl ethers (as well as activated primary alkyl ethers), on the other hand are dealkylated through a bimolecular mechanism involving two BBr3-ether adducts.[4]

RO+(−BBr3)CH3 \+ RO+(−BBr3)CH3→ RO(−BBr3) + CH3Br \+ RO+(BBr2)CH3

The dibromo(organo)borane can then undergo hydrolysis to give a hydroxyl group, boric acid, and hydrogen bromide as products.[5]

ROBBr2 \+ 3H2O → ROH + B(OH)3 \+ 2HBr

It also finds applications in olefin polymerization and in Friedel-Crafts chemistry as a Lewis acid catalyst.

The electronics industry uses boron tribromide as a boron source in pre-deposition processes for doping in the manufacture of semiconductors.[6] Boron tribromide also mediates the dealkylation of aryl alkyl ethers, for example demethylation of 3,4-dimethoxystyrene into 3,4-dihydroxystyrene.

## Synthesis

The reaction of boron carbide with bromine at temperatures above 300 °C leads to the formation of boron tribromide. The product can be purified by vacuum distillation.

## History

The first synthesis was done by Poggiale in 1846 by reacting boron trioxide with carbon and bromine at high temperatures:[7]

B2O3 \+ 3 C + 3 Br2 → 2 BBr3 \+ 3 CO

An improvement of this method was developed by F. Wöhler and Deville in 1857. By starting from amorphous boron the reaction temperatures are lower and no carbon monoxide is produced:[8]

2 B + 3 Br2 → 2 BBr3

## Applications

Boron tribromide is used in organic synthesis,[9] pharmaceutical manufacturing, image processing, semiconductor doping, semiconductor plasma etching, and photovoltaic manufacturing.

## See also

* List of highly toxic gases

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 NIOSH Pocket Guide to Chemical Hazards. "#0061". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0061.html.
2. ↑ "Boron Tribromide". Toxicologic Review of Selected Chemicals. National Institute for Occupational Safety and Health. 2018-09-21. https://www.cdc.gov/niosh/pel88/10294-33.html.
3. ↑ Doyagüez, E. G. (2005). "Boron Tribromide". Synlett 2005 (10): 1636–1637. doi:10.1055/s-2005-868513.
4. ↑ Sousa, C.; Silva, P.J. (2013). "BBr3-Assisted Cleavage of Most Ethers Does Not Follow the Commonly Assumed Mechanism". Eur. J. Org. Chem. 2013 (23): 5195–5199. doi:10.1002/ejoc.201300337.
5. ↑ McOmie, J. F. W.; Watts, M. L.; West, D. E. (1968). "Demethylation of Aryl Methyl Ethers by Boron Tribromide". Tetrahedron 24 (5): 2289–2292. doi:10.1016/0040-4020(68)88130-X.
6. ↑ Komatsu, Y.; Mihailetchi, V. D.; Geerligs, L. J.; van Dijk, B.; Rem, J. B.; Harris, M. (2009). "Homogeneous p+ emitter diffused using borontribromide for record 16.4% screen-printed large area n-type mc-Si solar cell". Solar Energy Materials and Solar Cells 93 (6–7): 750–752. doi:10.1016/j.solmat.2008.09.019.
7. ↑ Poggiale, M. (1846). "Nouveau composé de brome et de bore, ou acide bromoborique et bromoborate d'ammoniaque". Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences 22: 124–130. http://gallica.bnf.fr/ark:/12148/bpt6k29798/f128.table.
8. ↑ Wöhler, F.; Deville, H. E. S.-C. (1858). "Du Bore". Annales de Chimie et de Physique 52: 63–92. http://gallica.bnf.fr/ark:/12148/bpt6k347939/f62.table.
9. ↑ Akira Suzuki, Shoji Hara, Xianhai Huang (2006). "Boron Tribromide". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rb244.pub2. ISBN 978-0471936237.

## Further reading

* Doyagüez, E. G. (2005). "Boron Tribromide". Synlett 2005 (10): 1636–1637. doi:10.1055/s-2005-868513.

## External links

* Boron Tribromide at The Periodic Table of Videos (University of Nottingham)
* NIOSH Pocket Guide to Chemical Hazards - Boron Tribromide (Centers for Disease Control and Prevention)
* "Material Safety Data Sheet – Boron tribromide". Fisher Science. http://fscimage.fishersci.com/msds/96654.htm.
* May, F. H.; Bradford, J. L., "Production of Boron Tribromide", US patent 2989375, issued 1961-06-20, assigned to American Potash & Chemical

* v
* t
* e

Boron compounds

* BAs
* BBr3
* BCl3
* BF
* BF3
* BI3
* BN
* B(NO3)3
* B(OH)3
* BP
* BPO4
* B2F4
* B2Cl4
* B2H6
* BH3NH3
* B2O
* B2O3
* B2S3
* B4C
* B6O
* B5H9
* B5H11
* B6H10
* B6H12
* B10H14

* 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

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*[CID]: Compound ID
*[H330]: Fatal if inhaled
*[H300]: Fatal if swallowed
*[H314]: Causes severe skin burns and eye damage
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