COMEDK202510 May 2025Evening ShiftChemistryHaloalkanes and HaloarenesActual
Identify the incorrect statement.
Options
- AThe reaction of C ₆ H ₅ CH ₂- CHCl - C ₆ H ₅ with alc. KOH on heating yields two products.
- BWhen (-)-2-bromooctane is reacted with aqueous KOH , the substitution follows S _ N 2 mechanism and product fo
- CBenzylic halides show higher reactivity towards S_N 1 reaction.
- DOptically active (-)-2-Methylbutan-1-ol on reaction with HCl yields a product (+) -1-Chloro-2-methylbutane.
Correct answer
B. When (-)-2-bromooctane is reacted with aqueous KOH , the substitution follows S _ N 2 mechanism and product fo
Step-by-step solution
(1) Correct: Dehydrohalogenation of C₆H₅CH₂-CHCl-C₆H₅ with alc. KOH gives stilbene ( C₆H₅-CH=CH-C₆H₅ ), which exists as two geometric isomers (cis and trans) — hence two products. (2) Incorrect: S_N2 involves Walden inversion. Reaction of (-) -2-bromooctane with aqueous KOH via S_N2 gives (+) -octan-2-ol (inverted configuration), not (-) -octan-2-ol. (3) Correct: Benzylic halides readily undergo S_N1 because the benzylic carbocation intermediate is stabilised by resonance with the benzene ring. (4) Correct: Reactio