A Levels Chemistry (9701)•9701/11/M/J/23
Explanation
Oxidation of primary alcohols yields carboxylic acids Steps:
- Identify butanoic acid formula: CH₃CH₂CH₂COOH (4-carbon chain).
- Examine A: Acid-base reaction of CH₃CH₂COONa yields CH₃CH₂COOH (propanoic acid, 3 carbons).
- Examine B: Hydrolysis of CH₃CH₂CN (propanenitrile) yields CH₃CH₂COOH (propanoic acid).
- Examine C: Acidic hydrolysis of CH₃CH₂COOCH₃ (methyl propanoate) yields CH₃CH₂COOH (propanoic acid).
- Examine D: Oxidation of CH₃CH₂CH₂OH (butan-1-ol) with strong oxidant like KMnO₄ yields CH₃CH₂CH₂COOH (butanoic acid).
Why D is correct:
- Primary alcohols oxidize to carboxylic acids with the same carbon chain length, per standard organic oxidation rules.
Why the others are wrong:
- A produces propanoic acid due to 3-carbon starting material.
- B produces propanoic acid from nitrile hydrolysis adding O but retaining 3 carbons.
- C produces propanoic acid from ester hydrolysis retaining 3-carbon acyl group.
Final answer: D
Topic: Carboxylic acids and derivatives
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