Boron tribromide

Chembox new
Name = Boron tribromide
ImageFile = Boron-tribromide-3D-vdW.png ImageSize = 200px
ImageName = Boron tribromide
IUPACName = Boron tribromide
Section1 = Chembox Identifiers
CASNo = 10294-33-4
Section2 = Chembox Properties
Formula = BBr₃
MolarMass = 250.537 g mol⁻¹
Density = 2.60 g cm⁻³
Solvent = other solvents
Solubility = Reacts violently
MeltingPt = −46.3 °C −51.34 °F 227 K
BoilingPtC = 91

Boron tribromide, BBr₃, is a liquid compound containing boron and bromine. It is usually made by heating boron trioxide with carbon in the presence of bromine: this generates free boron which reacts vigorously with the bromine. It is very volatile and fumes in air because it reacts vigorously with water to form boric acid and hydrogen bromide. [Vacwell Engineering Company v BHD Chemicals Ltd [1969] 1 A.C 191.]

Chemical properties

Boron tribromide is commercially available and is a strong Lewis acid. It is an excellent demethylating or dealkylating agent for ethers, often in the production of pharmaceuticals. Additionally, it also finds applications in olefin polymerization and in Friedel-Craftschemistry 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. [ [http://www.albemarle.com/TDS/Fine_chemistry_services/BC-0196_BORON_Tri-Bromide.pdf Boron Tribromide] , Albemarle Corporation]

ynthesis

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 M. Poggiale in 1846 by reacting boron trioxide with carbon and bromine at high temperatures: [cite journal
title = Bore - Sur un nouveau composé de brome et de bore, l'acide bromoborique et le bromoborate d'ammoniaque
author = M. Poggiale
journal = Comptes rendus hebdomadaires
volume = 22
issue =
pages = 124–130
year = 1846
url = http://gallica.bnf.fr/ark:/12148/bpt6k29798/f128.table
doi = ]

: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: [cite journal
title = Du bore
author = F. Wöhler, H. E. S.-C. Deville
journal = Annales de chimie et de physique
volume = 52
issue =
pages = 63–92
year = 1858
url = http://gallica.bnf.fr/ark:/12148/bpt6k347939/f62.table
doi = ]

:2 B + 3 Br₂ → 2 BBr₃

References

External links

* [http://www.google.de/patents?id=v3VTAAAAEBAJ&printsec=abstract&zoom=4&dq=%22Boron+tribromide%22+%22boron+carbide%22 1962 Patent on the production of boron tribromide]