Question

What is the function of $BaS{O}_4$ in Rosenmund reaction:

• A. To stop further oxidation of aldehyde
• B. To stop further reduction of aldehyde
• C. To further reduce aldehyde
• D. None

Answer 1

The correct option is B To stop further reduction of aldehyde

The Rosenmund reaction is catalyzed by palladium on barium sulphate. As the barium sulphate posses low surface area, it reduces the activity of palladium. Thus preventing over reduction.

Over reduction of the palladium catalyst in Rosenmund's reduction has to be prevented otherwise, the aldehyde obtained by the reduction of acyl chloride or acid chloride will be reduced further to primary alcohols, which can undergo further reaction with remaining acid chloride forming the corresponding ester as the final product i.e. instead of obtaining product (aldehyde).

Therefore, the correct option is (B).