An aldehyde has a carbonyl group at the end of the chain. A ketone has a carbonyl group
somewhere in the middle of the carbon chain. Another way to think of this is that the carbonyl
carbon of an aldehyde has at least one bond to a hydrogen atom, whereas the carbonyl carbon of
a ketone is always bonded to two other carbons.Aldehydes are referred to with the suffix –al, while ketones are given the suffix –one. Carbonyl
groups of both aldehydes and ketones are labeled as oxo– substituents (ketones may also be
called keto– substituents).IUPAC Name Common Name
Methanal Formaldehyde
Ethanal Acetaldehyde
Propanal Propionaldehyde
Propanone AcetoneKetones and aldehydes both take precedence over both alcohols and hydrocarbon chains, and
the functional group that is the highest priority determines the suffix. Because the aldehyde is
chain-terminating and therefore on carbon number 1, the aldehyde would determine the suffix
when naming this compound.1.4
The ester derivative would be methyl pentanoate. The amide would be pentanamide. The
anhydride would be pentanoic anhydride.
3-methyl-2-oxopentanoic acid