Question

Write note of rosenmund reduction

Answer 1

The Rosenmund reduction is a hydrogenation process in which an acyl chloride is selectively reduced to an aldehyde. The reaction was named after Karl Wilhelm Rosenmund, who first reported it in 1918.[1]

Rosenmund reduction
Named after
Karl Wilhelm Rosenmund
Reaction type
Organic redox reaction
Identifiers
Organic Chemistry Portal
rosenmund-reduction
RSC ontology ID
RXNO:0000136
The Rosenmund reduction
The reaction, a hydrogenolysis, is catalysed by palladium on barium sulfate, which is sometimes called the Rosenmund catalyst. Barium sulfate has a low surface area which reduces the activity of the palladium, preventing over-reduction. However, for certain reactive acyl chlorides the activity must be reduced further, by the addition of a poison. Originally this was thioquinanthrene although thiourea[2] has also been used.[3][4] Deactivation is required because the system must reduce the acyl chloride but not the subsequent aldehyde. If further reduction does take place it will create a primary alcohol which would then react with the remaining acyl chloride to form an ester.