Carbonyl bromide

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Carbonyl bromide[1]
Structural formula of carbonyl bromide
Ball-and-stick model of carbonyl bromide
Names
Other names
Bromophosgene, carbonic dibromide, carbonyl dibromide
Identifiers
593-95-3 YesY=
ChemSpider 71389 YesY
Jmol-3D images Image
PubChem 79057
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
EU Index Not Listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 4: Very short exposure could cause death or major residual injury. E.g., VX gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
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[edit]

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[edit]

  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". Retrieved 2009-11-21. 
  3. ^ https://books.google.de/books?id=fM43Ny2eFS8C&pg=PA900&lpg=PA900&dq=carbonyl+bromide+enthalpy+of+formation&source=bl&ots=-ny9U7I-bx&sig=4XDedlqIFEK2OtXizrJaUfkBdzI&hl=de&sa=X&ei=UEgoVYCmI86uabvrgLAK&ved=0CDwQ6AEwAw#v=onepage&q=carbonyl%20bromide%20enthalpy%20of%20formation&f=false, pp. 669-671, retrieved 2015-04-11
  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