Which of the following alkenes will react fastest with `H_(2)` under catalytic hydrogenation conditions

Options

A.
B.
C.
D.

Answer

A

Explanation

During catalytic hydrogenation of an alkene, the hydrogens are transferred from the catalyst to the same side of the double bond. As such, smaller the number of R-groups as substituents, lesser is the steric hinderance and thus faster is the rate of hydrogenation. Therefore rate of catalytic hydrogenation will be maximum in case of (A).