Naming esters: alkyl from alcohol, alkanoate from acid chain

Steps:

• Examine the ester structure: locate the -COO- linkage.
• Count carbons in the acyl group (R-COO-): 4 carbons indicate butanoate.
• Count carbons in the alkyl group (-OR'): 3 carbons indicate propyl.
• Name as alkyl alkanoate: propyl butanoate.

Why C is correct:

• The structure has a 4-carbon acyl chain (butanoate from butanoic acid) and a 3-carbon propyl group from propanol, per IUPAC ester naming.

Why the others are wrong:

• A. butyl butanoate: alkyl is butyl (4 carbons), not propyl (3).
• B. butyl propanoate: alkyl is butyl (4 carbons) and acyl is propanoate (3 carbons).
• D. propyl propanoate: alkyl is correct (propyl), but acyl is propanoate (3 carbons), not butanoate (4).

Final answer: C