Saturday, October 8, 2011

Carbonyl group

The carbonyl group is characterized by the presence of an oxygen atom covalently linked via a double bond to a carbon atom. Depending on the position within the molecule to which it belongs, it can be called aldehyde group or ketone group. The first concerns the carbonyl groups that are located at an end of the molecule, that is, includes groups that are located on the first or the last carbon in the molecule. The ketone group refers to a carbonyl group which is at an internal position within the molecule. If the carbonyl is an aldehyde group, the molecule name ends with the suffix "al". If it is a ketone, it ends with "one".

Oxygen is more electronegative than carbon, which causes the carbonyl group to present a high polarity. As it is more electronegative, oxygen tends to relocate the electronic cloud, pulling it towards it. Consequently, carbon displays a partial positive charge and oxygen a partial negative charge.
Finally, it should also be noted that the term "carbonyl" can also be applied to carbon monoxide, when acting as a ligand in an inorganic or organometallic complex.
In the analysis of the composition of molecules, the carbonyl group can be identified by infrared spectroscopy (it absorbs between approximately 1600-1900 cm-1) or nuclear magnetic resonance (about 160-220 ppm).

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