Question

Reaction of trans-2-Phenyl-1-bromocyclopentane on reaction with alcoholic $KOH$ produces

• A. 4-phenylcyclopentene
• B. 2-phenylcyclopentene
• C. 1-phenylcyclopentene
• D. 3-phenylcyclopentene

Answer 1

The correct option is D 3-phenylcyclopentene

Secondary alkyl halide on reacting with alcoholic $KOH$ undergoes E2 elimination reaction. E2 is an anti-elimination reaction i.e., the leaving group and the proton which has to be abstracted should be in anti-periplanar position. Since, the given reactant is trans-2-Phenyl-2-bromocyclopentane, the H attached to carbon bearing phenyl group is at syn position to the $Br$ so the abstraction of hydrogen occurs at the other adjacent carbon atom to form a Hofmann product.
Compelete reaction is

Hence, option ''D'' is the correct answer.