The IUPAC name for the compound CH3CH2COCH3 is butan-2-one.
To arrive at this name, let’s break down the molecular structure. The compound has four carbon atoms, making it a butane derivative. The longest continuous chain of carbon atoms is four: CH3–CH2–C(=O)–CH3.
Next, we identify the functional group present. The presence of a carbonyl group (C=O) indicates that this compound is a ketone. Specifically, the carbonyl is located on the second carbon of the butane chain. Thus, we use ‘butan’ as the base name, and since the carbonyl is on the second carbon, we add ‘2-one’ to denote the ketone functional group.
Therefore, combining both parts, we arrive at the IUPAC name: butan-2-one.