Recycling of Rare Earth Elements: From E‐Waste to Stereoselective Catalytic Reactions

Abstract Raw mixtures of Rare Earths Elements, REE, recovered by E‐waste, were used as catalysts to promote the (stereoselective) synthesis of highly valuable compounds. Y 2 O 3 , the major species that is recovered by the E‐waste, can be easily converted into the catalytically active Y(OTf) 3 that is able to efficiently promote the Michael addition of indoles to benzylidene malonates and the stereoselective Diels‐Alder cycloaddition between cyclopentadiene and 4‐( S )‐3 acryloyl 4‐tert‐butyl 2‐oxazolidinone. Additionally, the raw mixtures were immobilissed onto silica and used to construct packed reactors, resulting in values for Productivity and Space‐Time Yields that were significantly higher than those of the corresponding batch conversions. Notably, the prepared cartridge employed in the model Michael reaction maintained its catalytic efficiency for more than 4 days of continuous running.