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Showing posts with label ALKENE AND ALKYNE:. Show all posts
Showing posts with label ALKENE AND ALKYNE:. Show all posts

Tuesday, February 4, 2020

What is Lindlar’s catalyst and does Lindlar’s catalyst use ?

Metallic palladium deposited on calcium carbonate with lead acetate and quinoline is known as Lindlar's catalyst and use for reduction of alkynes into cis alkenes.

The reactant alkyne molecules and hydrogen molecules get adsorbed at the surface of metal catalyst. It is chemical adsorption (chemisorption). In this state, the reactants lie very close to each other and so the hydrogen atoms start forming bond with carbon. Two hydrogen atoms are added to two triply bonded carbon atom from the same side of π-bond and a cis or syn addition product is formed. The product alkene now escapes away from the surface of the catalyst. Quinoline occupies the metal surface inhibiting further reduction to be alkanes Quinoline therefore is called catalyst poison and palladium is called deactivated catalyst or poisoned catalyst.

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