A Levels Chemistry (9701)•9701/12/M/J/25
Explanation
Tertiary alcohols resist oxidation but react with sodium Steps:
- Classify alcohols: primary (OH on CH2OH), secondary (OH on CHOH), tertiary (OH on COH with three alkyl groups).
- Acidified K2Cr2O7 oxidizes primary alcohols to carboxylic acids and secondary to ketones; tertiary alcohols do not oxidize due to lack of α-hydrogen.
- All alcohols react with Na to form alkoxide and H2 gas.
- Select the tertiary alcohol as it fits both criteria.
Why A is correct:
- (CH3)3COH is a tertiary alcohol; the C-OH carbon has no H for dehydrogenation, preventing oxidation per oxidation mechanism requiring α-H.
Why the others are wrong:
- B: Primary alcohol (CH3CH2CH2OH), oxidizes to propanoic acid.
- C: Secondary alcohol (CH3CH(OH)CH3), oxidizes to propanone.
- D: Secondary alcohol (CH3CH2CH(OH)CH3), oxidizes to butan-2-one.
Final answer: A
Topic: Hydroxy compounds
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