Alkyne reduction to (Z)-Alkene
Abstract
The conversion of an alkyne to a cis (Z)-alkene is achieved via heterogeneous catalytic hydrogenation using a poisoned (i.e. partially deactivated) catalyst, typically Lindlar’s catalyst (Pd deposited on CaCO3 then poisoned with Pb(OAc)2 and quinoline).
Keywords
Alkyne, Reduction, (Z)-Alkene
Category
Alkyne
Mechanism
The reaction proceeds via syn addition of H2 on the catalyst surface. First, both the alkyne and H2 are absorbed onto the same face of the Pd catalyst surface. Then, the two hydrogen atoms are delivered to the same face of the triple bond (syn addition). Thanks to the catalyst poisoning, the resulting (Z)-alkene detaches from the surface before any further reduction can occur.
