COMEDK · Chemistry · 25. Haloalkanes and Haloarenes
Identify the incorrect statement.
- A The reaction of \(\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}_2-\mathrm{CHCl}-\mathrm{C}_6 \mathrm{H}_5\) with alc. KOH on heating yields two products.
- B When (-)-2-bromooctane is reacted with aqueous KOH , the substitution follows \(\mathrm{S}_{\mathrm{N}} 2\) mechanism and product formed is \((-)\)-Octan-2-ol.
- C Benzylic halides show higher reactivity towards \(S_N 1\) reaction.
- D Optically active (-)-2-Methylbutan-1-ol on reaction with HCl yields a product \((+)\)-1-Chloro-2-methylbutane.
Answer & Solution
Correct Answer
(B) When (-)-2-bromooctane is reacted with aqueous KOH , the substitution follows \(\mathrm{S}_{\mathrm{N}} 2\) mechanism and product formed is \((-)\)-Octan-2-ol.
Step-by-step Solution
Detailed explanation
(1) Correct: Dehydrohalogenation of \(C_6H_5CH_2-CHCl-C_6H_5\) with alc. KOH gives stilbene (\(C_6H_5-CH=CH-C_6H_5\)), which exists as two geometric isomers (cis and trans) — hence two products. (2) Incorrect: \(S_N2\) involves Walden inversion. Reaction of \((-)\)-2-bromooctane…
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