The Rosenmund route also uses hydrogen gas and a palladium catalyst poisoned with barium sulfate ( Rosenmund reduction ), but uses perchloric acid instead of thionyl chloride.
2.
Lithium tri-tert-butoxyaluminium hydride, a bulky hydride donor, reduces acyl chlorides to aldehydes, as does the Rosenmund reduction using hydrogen gas over a poisoned palladium catalyst.
3.
For example, in the classical " Rosenmund reduction " of an acyl chloride to the corresponding aldehyde, the palladium catalyst ( over barium sulfate or calcium carbonate ) is intentionally poisoned by the addition of sulfur or quinoline in order to lower the catalyst activity and thereby prevent further reduction of the aldehyde product to yield a primary alcohol.