| Rosenmund reduction | |
|---|---|
| Named after | Karl Wilhelm Rosenmund |
| Reaction type | Organic redox reaction |
| Identifiers | |
| Organic Chemistry Portal | rosenmund-reduction |
| RSC ontology ID | RXNO:0000136 |
TheRosenmund reduction is ahydrogenation process in which anacyl chloride is selectivelyreduced to analdehyde. The reaction was named afterKarl Wilhelm Rosenmund, who first reported it in 1918.[1]
The reaction, ahydrogenolysis, is catalysed bypalladium onbarium sulfate, which is sometimes called theRosenmund 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 apoison. Originally this wasthioquinanthrene althoughthiourea[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 anester.
Rosenmund catalyst can be prepared by reduction of palladium(II) chloride solution in the presence of BaSO4. Typical reducing agent is formaldehyde.[5]
While Rosenmund reduction method can be used to prepare several aldehydes, formaldehyde cannot be prepared, as formyl chloride is unstable at room temperatures.[6]
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