R-C ≡C-R (H2)/( Lindlar catalyst )⟶ ?

Name: Problem 26, Chapter 3: The Pearson Guide to Organic Chemistry for the JEE Advanced
Uploaded: 2021-07-12T06:01:45-08:00
Duration: 1 min 25 s
Channel: Qudsiya Anis
Description: R-C ≡C-R (H2)/( Lindlar catalyst )⟶ ?

Key Concepts

Stereoselective Reduction

Stereoselective reduction refers to a reduction process that results in the preferential formation of one stereoisomer over another. In the context of alkyne hydrogenation using a Lindlar catalyst, the addition of hydrogen occurs from the same side of the molecule, leading to the formation of a cis-alkene selectively. This control over stereochemistry is crucial in many synthesis applications.

Lindlar Catalyst

The Lindlar catalyst is a specially modified metal catalyst, typically palladium on calcium carbonate that has been poisoned with lead acetate or quinoline. It is used to achieve partial hydrogenation of alkynes, converting them into alkenes specifically with a cis configuration, while preventing further reduction to alkanes. Its design ensures that the reaction stops at the desired stage of hydrogenation.

Alkyne

An alkyne is an organic compound that contains at least one carbon–carbon triple bond. This functional group is characterized by its linear geometry and high electron density, making it reactive in addition reactions. Alkynes can undergo various transformations, including catalytic hydrogenation that reduces the triple bond without fully saturating the molecule when controlled properly.

Catalytic Hydrogenation

Catalytic hydrogenation is a chemical reaction where hydrogen gas is added across multiple bonds (such as triple or double bonds) in the presence of a metal catalyst. This process is used to reduce unsaturated compounds to less unsaturated or saturated forms. The reaction conditions can be controlled to yield either partial or full hydrogenation, depending on the catalyst and conditions used.

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