Question

Trans-2 - phenyl -1 - bromocyclopentane on reaction with alcoholic KOH produces:

• A. 4 - Phenyl cyclo pentene
• B. 2 - Phenyl cycio pentene
• C. 1 - Phenyl cyclo pentene
• D. 3 - Phenyl cyclo pentene

Answer 1

The correct option is D 3 - Phenyl cyclo pentene

Trnas-2-phenyl-1-Bromo cyclo pentane

Structure is as follows :

halo alloane treatment with dlcoholic $KOH$ results in

$E_2$ anti-elimination mechanism

Anti elimination means $H$ and $Br$ both departing groups must be present at dihedral angle ${180}^0$ (anti).