Question

Identify the reagent used for Rosenmund reduction.

• A. $H_2/Ni$
• B. $H_2/Pd, BaSO_4$
• C. $Na - Hg/H_2O$
• D. $SnCl_2 - H_2O$

Hint:

$R-COCl \xrightarrow{H_2/Pd-BaSO_4} R-CHO$.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
Rosenmund reduction is a specific naming reaction used to convert acid chlorides into aldehydes.
Step 2: Detailed Explanation:
1. Rosenmund reduction involves the hydrogenation of an acyl chloride ($RCOCl$) to an aldehyde ($RCHO$).
2. The catalyst used is Palladium ($Pd$) deposited on Barium Sulphate ($BaSO_4$).
3. The $BaSO_4$ acts as a catalyst poison, reducing the activity of the Palladium catalyst to prevent the further reduction of the aldehyde into a primary alcohol.
4. Sometimes sulfur or quinoline is also added to further poison the catalyst.
Step 4: Final Answer:
The reagent for Rosenmund reduction is $H_2/Pd, BaSO_4$.