Carbon oxohalide

Carbon oxohalides are a group of chemical compounds that contain only carbon, oxygen and halogen atoms: fluorine, chlorine, bromine and iodine. They include carbonyl halides, COX₂, and oxalyl halides, C₂X₂O₂, where X = F, Cl, Br or I. The halogen atoms X do not have to be identical; they differ in mixed oxohalides. Most combinations of halogens exist but carbonyl iodide, COI₂, is unknown. The carbon–oxygen bond length in carbonyl halides (1.13–1.17 Å)^[1] is shorter than in other carbonyl compounds^[2] such as aldehydes and ketones, carboxylic acids, esters and amides (1.20–1.21 Å).^[3] They are reactive reagents for halogenation,^[1] acylation and dehydration reactions.^[4]

Carbon oxohalides^[1]

Name	Formula	Melting point / °C	Boiling point / °C	C–O bond length / Å
Carbonyl fluoride	COF2	−114	−83.1	1.174
Carbonyl chloride fluoride	COFCl		−42
Carbonyl bromide fluoride	COFBr		−20.6
Phosgene	COCl2	−127.8	+7.6	1.166
Carbonyl iodide fluoride	COFI	−90	+23.4
Carbonyl bromide chloride	COClBr
Carbonyl bromide	COBr2		+64.5	1.13
Oxalyl fluoride	C2F2O2	−3	+26.6
Oxalyl chloride	C2Cl2O2	−16	+63
Diphosgene	C2Cl4O2	−57	+128
Triphosgene	C3Cl6O3	+80	+206

See also

• Oxohalide
• Carbon compounds#Carbon halides
• Carbon compounds#Carbon-oxygen compounds
• Oxocarbon

References

1. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 304–305. ISBN 978-0-08-037941-8.
2. Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. p. 917. ISBN 978-0-19-965763-6.
3. David R. Lide, ed. (1995). CRC Handbook of Chemistry and Physics (84th ed.). CRC Press. p. 9-34. ISBN 978-0849304842.
4. Smith, Michael B.; March, Jerry (2007). March's Advanced Organic Chemistry (6th ed.). John Wiley & Sons. pp. 724, 728, 1276, 1427, 1550. ISBN 978-0-471-72091-1.