Question:
The composition of "Lindlar catalyst" is:
The composition of "Lindlar catalyst" is:
Updated On: Jul 14, 2026
- Amalgamated Zinc and HCl
- \(NH_2NH_2\) and \(KOH\)
- Palladium with calcium carbonate
- Palladium with Sodium carbonate
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The Correct Option is C
Approach Solution - 1
The correct option is (C): Palladium with calcium carbonate.
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Approach Solution -2
Lindlar catalyst is used to partially hydrogenate an alkyne down to a cis-alkene without over-reducing it to the fully saturated alkane. The question asks what this catalyst is actually made of. Let's check each option.
- Amalgamated zinc and HCl: This combination is the reagent used in the Clemmensen reduction, which reduces a ketone's carbonyl group to a methylene group. It has no role in alkyne hydrogenation and is not the Lindlar catalyst.
- NH2NH2 and KOH: Hydrazine with potassium hydroxide is used in the Wolff-Kishner reduction, another method for turning a carbonyl group into a methylene group. It is unrelated to catalytic hydrogenation of alkynes.
- Palladium with calcium carbonate: Lindlar catalyst is palladium metal deposited on calcium carbonate, then partly poisoned, usually with lead acetate and a trace of quinoline. The poisoning lowers the catalyst's activity just enough that hydrogen addition stops at the cis-alkene stage instead of continuing to the alkane.
- Palladium with sodium carbonate: While this sounds close to the real answer, the actual support used in Lindlar's catalyst is calcium carbonate, not sodium carbonate, so this option describes a different, non-standard preparation.
The catalyst that reliably stops hydrogenation at the alkene stage, giving the cis-product, is the poisoned palladium on calcium carbonate system.
So the correct answer is Palladium with calcium carbonate.
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