Question

In ROSEMUND REDUCTION why BaSO4 is also used with Palladium?

Answer 1

The Palladium Catalyst used in Rosenmund's reduction must be poisoned with BaSO4because the untreated catalyst Palladium (Pd) is too reactive and will undergo overreduction forming other products

Answer 2

Hii

Here is your answer  -

The rosemund reaction is catalyzed by palladium on barium sulfate. Barium sulfate reduces the activity of palladium due to its low surface area meaning it decreases the reducing power of palladium in order to prevent over-reduction of the acid.  

Acyl chloride -----> primary aldehyde  

This reduction in activity is required otherwise palladium being a strong reducing agent will further reduce the aldehyde formed to alcohol, which will react with the remaining acyl chloride to produce an ester.  

Primary aldehyde -----> primary alcohol