O Levels Chemistry (5070)•5070/12/M/J/24
Explanation
Ester naming: alkyl alkanoate rule Steps:
- Examine the formula CH3CH2CH2COOCH2CH3 (butanoate chain with ethyl group).
- Identify the acid portion: CH3CH2CH2COO- (4-carbon chain from butanoic acid).
- Identify the alcohol portion: -OCH2CH3 (ethyl group from ethanol).
- Combine as alkyl (ethyl) + alkanoate (butanoate).
Why B is correct:
- Butanoate derives from butanoic acid (CH3CH2CH2COOH, 4 carbons); ethyl from CH3CH2OH, matching the formula exactly.
Why the others are wrong:
- A: Butyl (4C alcohol) with ethanoate (2C acid) mismatches chain lengths.
- C: Propanoate (3C acid) has one fewer carbon in acid chain.
- D: Propyl (3C alcohol) with ethanoate (2C acid) swaps alcohol and acid parts incorrectly.
Final answer: B
Topic: Naming organic compounds
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