Aldehydes and Ketones
Aldehydes and ketones contain a carbonyl group (>C=O), and are collectively called carbonyl compounds.
Some other examples of carbonyl compounds are : R-COOH (Carboxylic acid), R-COX (Acid halide), R-COOR' (Ester) etc.
In aldehydes, one end of the carbonyl group is attached to an alkyl (or aryl) group and the other is to a hydrogen atom.
Here R and Ar represent alkyl and aryl groups respectively. In condensed structural formulae, the carbonyl group of an aldehyde is represented as −CHO.
In ketones, both the ends of carbonyl group are attached to alkyl or aryl groups.
Important Points Regarding Carbonyl Groups
- The carbon atom of carbonyl group is sp2 hybridised and has trigonal planar structure.
- Since the electronegativity of oxygen is higher than that of carbon, the C=O bond is polar.
- The carbonyl group exhibits resonance :