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

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References

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  1. ^ a b c 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.