Carbonyl bromide

Carbonyl bromide^[1]
Structural formula of carbonyl bromide	Ball-and-stick model of carbonyl bromide
Names
	Preferred IUPAC name Carbonyl dibromide
	Other names Bromophosgene, carbonic dibromide
Identifiers
CAS Number	593-95-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	71389 ;
PubChem CID	79057;
UNII	MNU12QTS1I ;
CompTox Dashboard (EPA)	DTXSID20208041 ;
	InChI InChI=1S/CBr2O/c2-1(3)4 Key: MOIPGXQKZSZOQX-UHFFFAOYSA-N ; InChI=1/CBr2O/c2-1(3)4 Key: MOIPGXQKZSZOQX-UHFFFAOYAM;
	SMILES BrC(Br)=O;
Properties
Chemical formula	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
Solubility in water	reacts
Thermochemistry
Heat capacity (C)	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)	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). verify (what is ?) Infobox references

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]

Synthesis and reactions

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 Δ_RH < 0 and Δ_RS < 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

^ 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

[hand-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 (24 May 1996). Phosgene: And Related Carbonyl Halides. pp. 669–671. ISBN 9780080538808. Retrieved April 11, 2015.

[4] 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.

[org-5] 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

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