Lindlar’s catalyst consists of -

Options

A. Metallic nickel + nickel boride
B. Metallic platinum
C. Metallic palladium deposited on calcium carbonate containing lead acetate and quinoline
D. Sodium borohydride in ethanol.

Answer

**Step-by-Step Solution:**

1. **Understanding Lindlar’s Catalyst**: Lindlar’s catalyst is a specific type of catalyst used in organic chemistry, particularly for the hydrogenation of alkynes to cis-alkenes.

2. **Components of Lindlar’s Catalyst**: The catalyst primarily consists of:
- **Palladium (Pd)**: This is the main metal component that facilitates the hydrogenation reaction.
- **Calcium Carbonate (CaCO3)**: This acts as a support for the palladium and helps in controlling the reaction conditions.
- **Lead Acetate (Pb(OAc)2)**: This is added to modify the activity of palladium and prevent over-hydrogenation.
- **Quinoline**: This is also included to further inhibit the complete hydrogenation of alkynes to alkanes.

3. **Final Composition**: Therefore, Lindlar’s catalyst can be summarized as:
- Metallic palladium deposited on calcium carbonate, along with lead acetate and quinoline.

4. **Conclusion**: The correct answer to the question "Lindlar’s catalyst consists of" is:
- Metallic palladium deposited on calcium carbonate containing lead acetate and quinoline.

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