Boron tribromide
From Wikipedia, the free encyclopedia
| Boron tribromide | |
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| IUPAC name | Boron tribromide |
| Identifiers | |
| CAS number | [10294-33-4] |
| Properties | |
| Molecular formula | BBr3 |
| Molar mass | 250.537 g mol−1 |
| Density | 2.60 g cm−3 |
| Melting point |
−46.3 °C −51.34 °F 227 K |
| Boiling point |
91 °C, 364 K, 196 °F |
| Solubility in water | Reacts violently |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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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.[1]
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[edit] 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-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.[2]
[edit] 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.
[edit] History
The first synthesis was done by M. Poggiale in 1846 by reacting boron trioxide with carbon and bromine at high temperatures:[3]
- 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:[4]
- 2 B + 3 Br2 → 2 BBr3
[edit] References
- ^ Vacwell Engineering Company v BHD Chemicals Ltd [1969] 1 A.C 191.
- ^ Boron Tribromide, Albemarle Corporation
- ^ M. Poggiale (1846). "Bore - Sur un nouveau composé de brome et de bore, l'acide bromoborique et le bromoborate d'ammoniaque". Comptes rendus hebdomadaires 22: 124–130.
- ^ F. Wöhler, H. E. S.-C. Deville (1858). "Du bore". Annales de chimie et de physique 52: 63–92.
