Naming Esters Correctly

Steps:

• Identify the alcohol part: "ethyl" indicates ethanol (C2H5OH), so the alkyl group is ethyl.
• Identify the acid part: "propanoate" comes from propanoic acid (CH3CH2COOH), so the chain is three carbons with the carbonyl.
• Combine: The ester is CH3CH2COOCH2CH3, where the acid chain is numbered starting from the carbonyl carbon as 1.
• Verify IUPAC name: It's ethyl propanoate, not "1 ethyl propanoate," which is non-standard.

Why D is correct:

• D matches the standard IUPAC structure for ethyl propanoate (CH3CH2C(O)OCH2CH3).

Why the others are wrong:

• A shows propyl ethanoate, swapping alkyl and acyl groups.
• B depicts methyl butanoate, with wrong chain lengths.
• C is ethyl acetate, using acetic acid instead of propanoic.

Not enough information on exact choice labels, but D is the valid ester.

Final answer: D