Topic summary
Organic reduction

Extracted from the Wikipedia article Organic redox reaction.
Organic reductions
In organic chemistry, reduction is equivalent to the addition of hydrogen atoms, usually in pairs. The reaction of unsaturated organic compounds with hydrogen gas is called hydrogenation. The reaction of saturated organic compounds with hydrogen gas is called hydrogenolysis. Hydrogenolyses necessarily cleaves C-X bonds (X = C, O, N, etc.). Reductions can also be effected by adding hydride and proton sources, the so-called heterolytic pathway. Such reactions are often effected using stoichiometric hydride reagents such as sodium borohydride or lithium aluminium hydride.