Question:
The composition of "Lindlar catalyst" is:
The composition of "Lindlar catalyst" is:
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The Lindlar catalyst is specifically used for the partial hydrogenation of alkynes, and its composition includes palladium supported on calcium carbonate.
Updated On: Jul 14, 2026
- Amalgamated Zinc and HCl
- NH2NH2 and KOH
- Palladium with calcium carbonate
- Palladium with Sodium carbonate
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The Correct Option is C
Approach Solution - 1
The Lindlar catalyst is composed of palladium (Pd) supported on calcium carbonate (CaCO₃). It is commonly used for the hydrogenation of alkynes to cis-alkenes, and it is a key catalyst in selective hydrogenation reactions.
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Approach Solution -2
The question asks what the Lindlar catalyst is made of. Let's check each option against known catalyst and reducing-agent compositions.
- Amalgamated Zinc and HCl: This combination is the reagent used in the Clemmensen reduction, which converts a ketone's carbonyl group into a methylene (-CH2-) group. It has no connection to alkyne hydrogenation and is not the Lindlar catalyst.
- NH2NH2 and KOH: Hydrazine with potassium hydroxide (with heat, in a high-boiling solvent) is the reagent combination for the Wolff-Kishner reduction, another method for reducing a carbonyl to a methylene group. It, too, is unrelated to alkyne hydrogenation.
- Palladium with calcium carbonate: Lindlar catalyst is palladium metal deposited on calcium carbonate support, typically further treated (poisoned) with lead acetate and a trace of quinoline to reduce its activity. This partial poisoning is deliberate: it lets the catalyst add hydrogen across a carbon-carbon triple bond just once, stopping cleanly at the cis (Z) alkene stage instead of continuing on to the fully saturated alkane.
- Palladium with Sodium carbonate: Sodium carbonate is not the support material used in the Lindlar catalyst; the standard, well-established support is calcium carbonate, not sodium carbonate.
The defining composition of the Lindlar catalyst, palladium supported on calcium carbonate and mildly poisoned, is what allows it to stop selectively at the cis-alkene rather than reducing all the way to the alkane.
Therefore, the correct answer is Palladium with calcium carbonate.
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