IUPAC Naming of Hydroxy Ketones

Steps:

• Parse the name: "3-Hydroxypentan-one" indicates a 5-carbon chain with a ketone (suffix -one) and a hydroxy group at position 3 (prefix 3-hydroxy).
• Determine ketone position: In pentanone, the carbonyl gets the lowest number, so it's pentan-2-one with OH at carbon 3.
• Construct structure: CH3-C(O)-CH(OH)-CH2-CH3, where carbon 1 is CH3, 2 is C=O, 3 is CH(OH), 4 is CH2, 5 is CH3.
• Verify functional group priority: Ketone has higher priority than alcohol, so name is correct as 3-hydroxypentan-2-one.

Why D is correct:

• Option D matches the structure CH3COCH(OH)CH2CH3, following IUPAC rules for numbering the chain from the end giving the carbonyl the lowest position (carbon 2).

Why the others are wrong:

• A: Places OH at carbon 2, forming an alpha-hydroxy ketone incorrectly numbered as pentan-3-one.
• B: Shows carbonyl at carbon 3, violating lowest-number rule for the principal functional group (ketone).
• C: Uses a 4-carbon chain, mismatching the "pentan" prefix for 5 carbons.

Final answer: D