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
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−1·K−1 (gas)
Std molar; entropy (So298)	309.1 J·mol−1·K−1 (gas)
Std enthalpy of; formation (ΔfH⦵298)	-127.2 or -145.2 kJ·mol−1 (liquid) ; -96.2 or -114 kJ·mol−1 (gas)
Hazards
NFPA 704 (fire 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 Δ_RH < 0 and Δ_RS < 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

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.
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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[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.

[org-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