Reduction Reactions

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Alkynes are located in the redox scale at a higher oxidation state than alkenes. Therefore, alkenes can be obtained by reduction of alkynes. The reduction can be performed by different methods with different stereochemical outcome:

Hydrogenation of an alkyne with the Lindlar catalyst: cis alkene — Hydrogenation with H₂ and Lindlar catalyst: *syn* addition of both hydrogens, giving the *cis* alkene.

Reduction of an alkyne with Na/NH₃: trans olefin — Reduction with sodium in liquid ammonia: electrons are transferred one at a time and the more stable *trans* alkene is obtained.

The mechanism of these reactions will be described in detail in the alkynes chapter. If you are curious, click here to see it.