Rosenmund reduction
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]
The reaction 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.
See also
- Lindlar catalyst - Palladium on calcium carbonate with added catalytic poison, similar to the Rosenmund catalyst
- Rosenmund–von Braun reaction - Another reaction named after Karl Wilhelm Rosenmund in which an aryl halide is converted into an aryl nitrile
- Grundmann aldehyde synthesis - Also reduces an acyl halide to an aldehyde, via the use of diazomethane
- Diisobutylaluminium hydride (DIBALH) can also reduce acid chlorides to aldehydes.
- Gattermann–Koch reaction - A reaction which produces an aldehyde via an intermediate acyl chloride
References
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Further reading
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