Catalytic Hydrogenation of Alkenes

Hydrogenation of alkenes occurs in the presence of a metal catalyst, a syn addition process. The two hydrogen atoms add to the same face of the double bond. Furthermore, if one side is more hindered than the other, addition is stereoselective for the less hindered side. Hydrogenation is exothermic, and relative heats of hydrogenation can be used to infer the relative stability of double bonds in different contexts. The more stable the double bond, the lower the heat of hydrogenation will be.