Rosenmund Reduction

The Rosenmund reduction is a hydrogenation method used to selectively reduce an acyl chloride to an aldehyde. Named after Karl Wilhelm Rosenmund, who first described the reaction in 1918, it involves a hydrogenolysis process catalyzed by palladium on barium sulfate—known as the Rosenmund catalyst. The barium sulfate has a low surface area, which decreases the palladium's activity and prevents over-reduction to an alcohol. For particularly reactive acyl chlorides, the catalyst's activity may need to be further suppressed by adding a catalyst poison.

References

Rosenmund, K. W. (1918). "Über eine neue Methode zur Darstellung von Aldehyden. 1. Mitteilung". Chemische Berichte (in German). 51: 585–593. doi:10.1002/cber.19180510170.