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

It follows E2 mechanism. Hughes and Ingold proposed that bimolecular elimination reactions take place when the two groups to be eliminated are trans and lie in one plane with the two carbon atoms to which they are attached i.e. E2 reactions are stereoselectively trans.