Lindlar catalyst (H2\/Pd,CaCO3) is poisoned palladium catalyst. It is known as also partially deactivated palladised charcoal. It is composed of powdered calcium carbonate coated with palladium and poisoned with quinoline. It is used for reduction of alkyne to alkene and acid chloride to aldehyde. Stereochemistry involved is syn-addition. H3C−C≡C−2CH3