Summary
Carbonyl bromide, also known as bromophosgene, is an organic chemical compound with the chemical formula COBr2. It is a colorless liquid. It is a bromine analogue of phosgene. It is a carbon oxohalide. Carbonyl bromide is a decomposition product of halon compounds used in fire extinguishers.[2]
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| Names | |||
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| Preferred IUPAC name
Carbonyl dibromide | |||
| Other names
Bromophosgene, carbonic dibromide
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3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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| 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 | |||
Heat capacity (C)
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61.8 J/(mol·K) (gas) | ||
Std molar
entropy (S⦵298) |
309.1 J/(mol·K) (gas) | ||
Std enthalpy of
formation (ΔfH⦵298) |
−127.2 or −145.2 kJ/mol (liquid) −96.2 or −114 kJ/mol (gas) | ||
| Hazards | |||
| NFPA 704 (fire diamond) | |||
| Related compounds | |||
Related compounds
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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
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Synthesis and reactions edit
Carbonyl bromide is formed by the oxidation 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 further shift of the chemical equilibrium towards the educts (since ΔRH < 0 and ΔRS < 0).[3][4][clarification needed]
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, water and carbon dioxide.
References edit
- ^ 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
- ^ US Occupational Safety and Health Administration (May 1996). "Common Fire Extinguishing Agents". Archived from the original on 2009-09-12. Retrieved 2009-11-21.
- ^ T.A. Ryan; E.A. Seddon; K.R. Seddon; C. Ryan (24 May 1996). Phosgene: And Related Carbonyl Halides. pp. 669–671. ISBN 9780080538808. Retrieved April 11, 2015.
- ^ Parkington, Michael J.; Ryan, T. Anthony; Seddon, Kenneth R. (1997). "Carbonyl dibromide: A novel reagent for the synthesis of metal bromides and bromide oxides". Journal of the Chemical Society, Dalton Transactions (2): 257–262. doi:10.1039/A603977D.
- ^ Katrizsky, Alan R.; Meth-Cohn, Otto; Wees, Charles W. (1995), Organic Functional Group Transformations, vol. 6, Elsevier, pp. 417–8, ISBN 978-0-08-042704-1, retrieved 2009-11-23