Carbonyl



 

In oxygen atom : C=O.

The term carbonyl can also refer to triple-bonded to oxygen : C≡O.

The remainder of this article concerns itself with the organic chemistry definition of carbonyl.

Carbonyl compounds

A carbonyl group characterizes the following types of compounds (where -CO denotes a C=O carbonyl group):

CompoundAcid anhydride
Structure
General formulaRCHORCOR'RCOOHRCOOR'RCONR'R''RC(O)C(R')CR''R'''RCOCl(RCO)2O

Other organic carbonyls are phosgene

Reactivity

Oxygen is more nucleophiles. Also, the electronegative oxygen can react with an electrophile; for example a proton in an acidic solution or other Lewis Acid.

The alpha hydrogen in a carbonyl compound is much more acidic (~1030 times more acidic) than a typical CH bond. For example the pKa values of acetone are 16.7 and 19, respectively.[1]

Amides are the most stable of the carbonyl couplings due to their high resonance stabilization between the Nitrogen-Carbon and Carbon-Oxygen bonds.

Carbonyl groups can be Grignard reagents.

Other important reactions include:

α,β-Unsaturated carbonyl compounds

α,β-Unsaturated carbonyl compounds are an important class of carbonyl compounds with the general structure Cβ=Cα−C=O. In these compounds the carbonyl group is aldol reaction and in the Perkin reaction. The carbonyl group, be it an electrophilic addition. On the other hand, these compounds are activated towards nucleophilic addition.

Spectroscopy

  • Infrared spectroscopy: the C=O double bond absorbs infrared light at wavenumbers between approximately 1600–1900 cm−1. The exact location of the absorption is well understood with respect to the geometry of the molecule. This absorption is known as the "carbonyl stretch" when displayed on an infrared absorption spectrum.[2]
  • Nuclear magnetic resonance: the C=O double-bond exhibits different resonances depending on surrounding atoms, generally a downfield shift. The 13C NMR of a carbonyl carbon is in the range of 160-220 ppm.


See also

References

  1. ^ Ouellette, R.J. and Rawn, J.D. “Organic Chemistry” 1st Ed. Prentice-Hall, Inc., 1996: New Jersey. ISBN 0-02-390171-3.
  2. ^ Mayo D.W., Miller F.A and Hannah R.W “Course Notes On The Interpretation of Infrared and Raman Spectra” 1st Ed. John Wiley & Sons Inc, 2004: New Jersey. ISBN 0-471-24823-1.

Further reading

  • L.G. Wade, Jr. Organic Chemistry, 5th ed. Prentice Hall, 2002. ISBN 0-13-033832-X
  • The Frostburg State University Chemistry Department. Organic Chemistry Help (2000).
  • Advanced Chemistry Development, Inc. IUPAC Nomenclature of Organic Chemistry (1997).
  • William Reusch. VirtualText of Organic Chemistry (2004).
  • Purdue Chemistry Department [1] (retrieved Sep 2006). Includes water solubility data.
  • William Reusch. (2004) Aldehydes and Ketones Retrieved 23 May 2005.
  • ILPI. (2005) The MSDS Hyperglossary- Anhydride.
 
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