SELECTIVE HYDROGENATION BY WILKINSON'S CATALYST
Wilkinson's catalyst can be used to achieve selective hydrogenations.
* Less substituted and sterically less hindered double bonds are selectively hydrogenated.
selective hydrogenation of less substituted double bond using wilkinson's catalyst
* Exocyclic double bonds are selectively hydrogenated over endocyclic double bonds.
selective hydrogenation of exo cyclic double bond using wilkinsons catalyst
* Cis alkenes are reduced rapidly than trans alkenes.
cis trans selectivity : wilkinson's catalyst
* Isolated double bonds are rapidly hydrogenated over conjugated dienes.
selective hydrogenation of isolated double bond using wilkinson's catalst
* Terminal alkynes are hydrogenated more rapidly than terminal alkenes. The selectivity can be enhanced by using acidic alcoholic co-solvents.
selective hydrogenation of triple bond
* Functional groups like C=O, C=N, NO2, Aryl, CO2R etc., are unaffected. The compatibility of Wilkinson's catalyst with polar multiple bonds indicates the metal hydride bond is primarily covalent in character.
compatibility of functional groups containing polar multiple bonds
Note: But sterically unhindered aldehyde groups are susceptible to decarbonylation, also rendering the catalyst ineffective.
* Unsaturated substrates containing polar functionality are hydrogenated more rapidly. It may be due to easy coordination of olefin to the catalyst that is assisted by polar functional group.
polar assisted hydrogenation using wilkinson's catalyst