Question

What is the IUPAC name of the compound CH₃-CH₂-CO-CH₃?

• A. Butan-2-one
• B. Propan-2-one
• C. Butanal
• D. Propanal

Hint:

For ketones, number the carbon chain to minimize the position number of the carbonyl group in IUPAC naming.

Answer 1

The Correct Option is A

To name the compound CH₃-CH₂-CO-CH₃ using IUPAC nomenclature, we proceed as follows:

1. Identify the functional group: The C=O group indicates a ketone, so the suffix is “-one.”
2. Determine the longest carbon chain including the carbonyl group: \[ \text{CH₃-CH₂-C(=O)-CH₃} \rightarrow 4 \text{ carbons (butane base name)}. \]
3. Number the carbon chain to give the carbonyl carbon the lowest possible number: \[ \text{Left to right: CH₃(1)-CH₂(2)-CO(3)-CH₃(4)} \rightarrow \text{carbonyl at position 3}. \] \[ \text{Right to left: CH₃(4)-CH₂(3)-CO(2)-CH₃(1)} \rightarrow \text{carbonyl at position 2}. \]
4. Choose the lower number: Carbonyl at position 2.
5. Name the compound: Butan-2-one (4 carbons, ketone at position 2).
6. Match with options: Butan-2-one corresponds to option (A).

Thus, the correct answer is: \[ \boxed{\text{Butan-2-one}} \]