A Levels Chemistry (9701)•9701/11/O/N/22

Explanation
Elimination Reaction in Hot Ethanolic NaOH
Steps:
- Hot ethanolic NaOH with secondary alkyl halide favors E2 elimination over substitution.
- 2-Bromopropane (CH₃CHBrCH₃) undergoes dehydrohalogenation.
- OH⁻ abstracts β-hydrogen from adjacent carbon, Br⁻ leaves.
- Forms propene (CH₃CH=CH₂) as the major product.
Why D is correct:
- E2 mechanism in alcoholic KOH/NaOH yields alkenes from alkyl halides, per standard organic reaction conditions.
Why the others are wrong:
- A: Propan-1-ol requires primary halide and aqueous NaOH for SN2 substitution.
- B: Propan-2-ol is minor SN1 substitution product, but elimination dominates in ethanol.
- C: 2-Hydroxypropane names propan-2-ol, which is substitution product, not major here.
Final answer: D
Topic: Halogen compounds
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