What does "hydrogenation" refer to in organic reactions?

Hydrogenation specifically refers to the chemical process in which hydrogen molecules are added to unsaturated organic compounds, such as alkenes and alkynes, resulting in the formation of saturated compounds. This is a crucial reaction in organic chemistry because it allows for the transformation of double (or triple) bonds, which are characteristic of unsaturated compounds, into single bonds, leading to a more stable, saturated product.

For example, when ethylene (an alkene) undergoes hydrogenation, it reacts with hydrogen to become ethane (an alkane), a completely saturated molecule. This reaction typically requires the presence of a catalyst, such as nickel, palladium, or platinum, to facilitate the process and lower the activation energy required for the reaction to proceed.

Understanding hydrogenation is vital in various applications, including the production of margarine from vegetable oils and the synthesis of numerous organic compounds within the pharmaceutical and petrochemical industries.