What is difference between hydrogenation and hydrogenolysis?

Question

Ryan Andrews · Accepted Answer

The key difference is that the former does not involve bond cleavage, but the latter does. Both are essentially catalytically driven reactions of organic molecules with hydrogen gas.

Hydrogenation refers to the reaction between a susbtance and molecular hydrogen #H_2#. The substance could be, for example, an organic compound such as an olefin, which is being saturated (ethylene --> ethane), or could be substance undergoing reduction. The process usually takes place in the presence of a calalyst (e.g. palladium on graphite). Hydrogenolysis refers to the breaking of a bond between two carbon atoms or between an atom of carbon and that of another element via reaction with hydrogen. Again, a catalyst is usually required. This process is the basis of hydrotreatment of base oil which is carried out in refineries.

Nicholas Antonuccio · Answer

undefined Hydrogenation is the chemical reaction in which hydrogen gas (H2) is added to a compound, typically an unsaturated organic compound, to form a saturated compound. Hydrogenolysis, on the other hand, is the chemical reaction in which a bond in a molecule is cleaved by the addition of hydrogen gas (H2), resulting in the formation of smaller molecules. Essentially, hydrogenation adds hydrogen to a molecule, while hydrogenolysis breaks a bond in a molecule using hydrogen.