Carbonyl bromide

Carbonyl bromide[1]
Names
Preferred IUPAC name
Carbonyl dibromide
Other names
Bromophosgene, carbonic dibromide
Identifiers
3D model (JSmol)
ChemSpider
Properties
COBr2
Molar mass 187.818 g/mol
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−1·K−1 (gas)
309.1 J·mol−1·K−1 (gas)
-127.2 or -145.2 kJ·mol−1 (liquid)
-96.2 or -114 kJ·mol−1 (gas)
Hazards
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 4: Very short exposure could cause death or major residual injury. E.g., VX gasReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calciumSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
4
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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Infobox references

Carbonyl bromide, also known as bromophosgene by analogy to phosgene, is an organic chemical compound. It is a decomposition product of halon compounds used in fire extinguishers.[2]

Reactions

Carbonyl bromide is formed when carbon tetrabromide is melted and concentrated sulfuric acid is added.

In contrast to phosgene, carbonyl bromide cannot be produced efficiently from carbon monoxide and bromine. A complete conversion is not possible due to thermodynamic reasons. Additionally, the reaction

CO + Br2 ⇌ COBr2

processes slowly at room temperature. Increasing temperature, in order to increase the reaction rate, results in a further shift of the chemical equilibrium towards the educts (since ΔRH < 0 and ΔRS < 0).[3]

On the other hand, carbonyl bromide slowly decomposes to carbon monoxide and elemental bromine even at low temperatures.[4] It is also sensitive to hydrolysis.

References

  1. ↑ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 3–96, 4–50, 5–26, ISBN 0-8493-0594-2
  2. ↑ US Occupational Safety and Health Administration (May 1996). "Common Fire Extinguishing Agents". Archived from the original on 2009-09-12. Retrieved 2009-11-21.
  3. ↑ T.A. Ryan; E.A. Seddon; K.R. Seddon; C. Ryan. Phosgene: And Related Carbonyl Halides. pp. 669–671. Retrieved April 11, 2015.
  4. ↑ Katrizsky, Alan R.; Meth-Cohn, Otto; Wees, Charles W. (1995), Organic Functional Group Transformations, 6, Elsevier, pp. 417–8, ISBN 978-0-08-042704-1, retrieved 2009-11-23
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