Carbonyl bromide

Chemical compound From Wikipedia, the free encyclopedia

Carbonyl bromide, also known as bromophosgene, is a carbon oxohalide and a bromine analogue of phosgene, with the chemical formula COBr2. It is a colorless liquid. Carbonyl bromide is a decomposition product of halon compounds used in fire extinguishers.[2]

Quick facts Names, Identifiers ...
Carbonyl bromide[1]
Structural formula of carbonyl bromide
Structural formula of carbonyl bromide
Ball-and-stick model of carbonyl bromide
Ball-and-stick model of carbonyl bromide
Names
Preferred IUPAC name
Carbonyl dibromide
Other names
Bromophosgene, carbonic dibromide
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/CBr2O/c2-1(3)4 checkY
    Key: MOIPGXQKZSZOQX-UHFFFAOYSA-N checkY
  • InChI=1/CBr2O/c2-1(3)4
    Key: MOIPGXQKZSZOQX-UHFFFAOYAM
  • BrC(Br)=O
Properties
COBr2
Molar mass 187.818 g·mol−1
Appearance colorless liquid
Density 2.52 g/mL at 15 °C
Boiling point 64.5 °C (148.1 °F; 337.6 K) decomposes
reacts
Thermochemistry
61.8 J/(mol·K) (gas)
309.1 J/(mol·K) (gas)
−127.2 or −145.2 kJ/mol (liquid)
−96.2 or −114 kJ/mol (gas)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
4
0
1
Related compounds
Related compounds
 Carbonyl fluoride
Phosgene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis and reactions

Carbonyl bromide is formed by the oxidation of carbon tetrabromide with sulfuric acid:

CBr4 + H2SO4 → COBr2 + SO2 + Br2 + H2O

In contrast to phosgene, carbonyl bromide cannot be produced efficiently by halogenation of carbon monoxide. The bromination of carbon monoxide follows this equation:

CO + Br2 ⇌ COBr2

But the process is slow at room temperature. Increasing temperature, in order to increase the reaction rate, results in a shift of the chemical equilibrium towards the reactants (since ΔH < 0 and ΔS < 0).[3][4]

Carbonyl bromide slowly decomposes to carbon monoxide and elemental bromine even at low temperatures.[5] It is also sensitive to hydrolysis, breaking down into hydrogen bromide and carbon dioxide.

References

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