Final answer:
Hydrogenation is the reaction of alkenes with hydrogen in the presence of a catalyst like nickel, platinum, or palladium, which results in the conversion of alkenes to alkanes.
Step-by-step explanation:
Hydrogenation of Alkenes
When an alkene is treated with hydrogen (H₂) in the presence of a catalyst, a hydrogenation reaction occurs. The catalyst, often a substance like finely divided nickel (Ni), platinum (Pt), or palladium (Pd) supported on carbon, facilitates the addition of hydrogen atoms to the alkene, converting it to an alkane. The presence of the catalyst surface is crucial for the reaction to proceed efficiently as it allows for the absorption of both the hydrogen and the alkene, leading to the breaking of the H-H bond and the addition of hydrogen atoms across the double bond of the alkene.
The mechanism of catalytic hydrogenation involves several steps on the catalyst surface. The alkene and hydrogen first adsorb to the catalyst, with the hydrogen molecules dissociating into individual reactive hydrogen atoms. The alkene then interacts with these hydrogen atoms and step by step adds them to form the alkane, with the release of the alkane product signifying the completion of the reaction.
Hydrogenation is a valuable reaction for converting alkenes to alkanes, a process that is widely used in the chemical industry. It is a classic example of an addition reaction involving the addition of hydrogen to the carbon-carbon double bond in alkenes to form saturated hydrocarbons (alkanes).