Concept:To determine the IUPAC name, we must first translate the common name into a structural formula, then apply systematic numbering.
Solution:- "Diisopropyl ketone" means the central carbonyl group (\( -CO- \)) is flanked by two isopropyl groups: \( (CH_3)_2CH- \).
- The full structural formula is: \( CH_3-CH(CH_3)-CO-CH(CH_3)-CH_3 \).
- Identify the longest continuous carbon chain containing the carbonyl group. Counting straight across gives a 5-carbon chain (pentane).
- Number from either end to give the carbonyl the lowest number. It lands on C3 (pentan-3-one).
- There are methyl groups branching off at C2 and C4.
- Combining these, we get 2,4-dimethylpentan-3-one.
Why other options are incorrect:Option A incorrectly uses the substituents as part of the parent name without finding the longest chain. Option C places the ketone at C2, which would destroy the symmetry of the diisopropyl structure.
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