 | |
 | |
| Names | |
|---|---|
| IUPAC name Boron tribromide | |
| Other names Tribromoborane, Boron bromide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
|
| ECHA InfoCard | 100.030.585 |
| EC Number |
|
| RTECS number |
|
| UNII | |
| UN number | 2692 |
| |
| |
| Properties | |
| 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) |
| Reacts violently with water and other protic solvents | |
| Solubility | Soluble inCH2Cl2,CCl4 |
| Vapor pressure | 7.2 kPa (20 °C) |
Refractive index (nD) | 1.00207 |
| Viscosity | 7.31 x 10−4 Pa s (20 °C) |
| Thermochemistry | |
| 0.2706 J/K | |
Std molar entropy(S⦵298) | 228 J/mol K |
Std enthalpy of formation(ΔfH⦵298) | −0.8207 kJ/g |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | Reacts violently with water, potassium, sodium, and alcohols; attacks metals, wood, and rubber[1] |
| GHS labelling: | |
  | |
| Danger | |
| H300,H314,H330 Within the European Union, the following additional hazard statement (EUH014) must also be displayed on labeling: Reacts violently with water. | |
| NFPA 704 (fire diamond) | |
| 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] |
| Safety data sheet (SDS) | ICSC 0230 |
| Related compounds | |
Related compounds | Boron trifluoride Boron trichloride Boron triiodide |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Boron tribromide, BBr3, is a colorless, fuming liquid compound containingboron andbromine. Commercial samples usually are amber to red/brown, due to weak bromine contamination. It is decomposed by water and alcohols.[2]
Boron tribromide is commercially available and is a strongLewis acid.
It is an excellent demethylating or dealkylating agent for thecleavage ofethers, also with subsequent cyclization, often in the production ofpharmaceuticals.[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.
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]
The dibromo(organo)borane can then undergohydrolysis to give a hydroxyl group,boric acid, andhydrogen bromide as products.[5]
It also finds applications inolefinpolymerization and inFriedel-Crafts chemistry as aLewis acidcatalyst.
The electronics industry uses boron tribromide as a boron source in pre-deposition processes fordoping in the manufacture ofsemiconductors.[6]Boron tribromide also mediates the dealkylation of aryl alkyl ethers, for exampledemethylation of3,4-dimethoxystyrene into3,4-dihydroxystyrene.
The reaction ofboron carbide withbromine at temperatures above 300 °C leads to the formation of boron tribromide. The product can be purified by vacuumdistillation.
The first synthesis was done byPoggiale in 1846 by reacting boron trioxide with carbon and bromine at high temperatures:[7]
An improvement of this method was developed byF. Wöhler andDeville in 1857. By starting from amorphous boron the reaction temperatures are lower and no carbon monoxide is produced:[8]
Boron tribromide is used in organic synthesis,[9] pharmaceutical manufacturing, image processing, semiconductor doping, semiconductor plasma etching, and photovoltaic manufacturing.
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