Aluminium and iron: a strong team

Lithium aluminium hydride (LiAlH₄) is a versatile bulk reagent for reduction of ketones to alcohols, or imines to amines. This is a stoichiometric process, needing a lot of LiAlH₄ and creating quite some lithium and aluminium waste. Recently the Harder group showed that the imine-to-amine conversion under hydrogen only needs small catalytic quantities of LiAlH₄ [1, 2]. It is now found that addition of just a pinch of iron powder transforms LiAlH₄ into a catalyst for the challenging reduction of highly stable aromatic molecules like benzene. While iron or LiAlH₄ alone do not react with benzene, tiny amounts of the mixture catalyze the conversion of benzene to cyclohexane. Even better, the lithium component is not needed: aluminium/iron combinations are considerably more active for benzene reduction. Such reductions become increasingly important in storing hydrogen for a future energy technology. They are normally most efficiently catalyzed by precious metals like palladium or platinum but combining the two most abundant metals in the world, aluminium & iron, is a sustainable alternative. As previously reported, the secret is to activate the iron by metal evaporation [3].

[1] Nature Catalysis 2018 https://doi.org/10.1038/s41929-017-0006-0
[2] Angewandte Chemie 2018 https://doi.org/10.1002/anie.201803804
[3] Nature Communications 2022 https://doi.org/10.1038/s41467-022-30840-4

Publication

Knüpfer, C., Färber, C., Langer, J., Harder, S., Angew. Chem. Int. Ed. 2023, e202219016; Angew. Chem. 2023, e202219016. :  https://onlinelibrary.wiley.com/doi/epdf/10.1002/anie.202219016

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