Ketones are compounds in which an oxygen atom is bonded to a carbon atom, which is itself bonded to two or more carbon atoms.

Like aldehydes, ketones can be named using either the common system or the IUPAC system. In the common system, ketones names are created by naming the groups attached to the carbonyl carbon and then adding the word ketone. Following are several examples:

The five IUPAC rules for aldehydes also apply to ketones, with one exception: After dropping the ‐e ending of the alkane name, you add ‐one for ketones (rather than ‐al, which designates aldehydes).

In the IUPAC system, aromatic ketones are considered benzenesubstituted aliphatic ketones.

Many aromatic compounds retain their common names in the IUPAC system. Following are two such examples: