question_answer

Which of the following alkenes will react fastest withunder catalytic hydrogenation conditions?

A)

B)                       

C)                       

D)                       

Correct Answer: A

Solution :

During catalytic hydrogenation, the hydrogens are transferred from the catalyst to the same side of the double bond. Evidently, smaller the number ofsubstituents, lesser is the steric hinderance and hence faster is the rate of hydrogenation. Thus, option (a) with two R groups on the same side of the molecule is correct.