Mixed-metal MIL-100(Sc,M) (M=Al, Cr, Fe) for Lewis acid catalysis and tandem C−C bond formation and alcohol oxidation
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Date
05/12/2014Author
Grant ID
F/00 268/BJ
EP/J501542/1
EP/J501542/1
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The trivalent metal cations Al3+, Cr3+, and Fe3+ were each introduced, together with Sc3+, into MIL-100(Sc,M) solid solutions (M=Al, Cr, Fe) by direct synthesis. The substitution has been confirmed by powder X-ray diffraction (PXRD) and solid-state NMR, UV/Vis, and X-ray absorption (XAS) spectroscopy. Mixed Sc/Fe MIL-100 samples were prepared in which part of the Fe is present as α-Fe2O3 nanoparticles within the mesoporous cages of the MOF, as shown by XAS, TGA, and PXRD. The catalytic activity of the mixed-metal catalysts in Lewis acid catalysed Friedel–Crafts additions increases with the amount of Sc present, with the attenuating effect of the second metal decreasing in the order Al>Fe>Cr. Mixed-metal Sc,Fe materials give acceptable activity: 40 % Fe incorporation only results in a 20 % decrease in activity over the same reaction time and pure product can still be obtained and filtered off after extended reaction times. Supported α-Fe2O3 nanoparticles were also active Lewis acid species, although less active than Sc3+ in trimer sites. The incorporation of Fe3+ into MIL-100(Sc) imparts activity for oxidation catalysis and tandem catalytic processes (Lewis acid+oxidation) that make use of both catalytically active framework Sc3+ and Fe3+. A procedure for using these mixed-metal heterogeneous catalysts has been developed for making ketones from (hetero)aromatics and a hemiacetal.
Citation
Mitchell , L , Williamson , P , Ehrlichova , B , Anderson , A E , Seymour , V R , Ashbrook , S E , Acerbi , N , Daniels , L , Walton , R , Clarke , M L & Wright , P A 2014 , ' Mixed-metal MIL-100(Sc,M) (M=Al, Cr, Fe) for Lewis acid catalysis and tandem C−C bond formation and alcohol oxidation ' , Chemistry - A European Journal , vol. 20 , no. 51 , pp. 17185-17197 . https://doi.org/10.1002/chem.201404377
Publication
Chemistry - A European Journal
Status
Peer reviewed
ISSN
0947-6539Type
Journal article
Description
The authors thank Johnson Matthey and the EPSRC for an Industrial CASE award to L.M. We gratefully acknowledge the IAESTE UK for a scholarship to B.E. They also thank the Leverhulme Trust (F/00 268/BJ), EPSRC (EP/J501542/1), and the EaStCHEM Research Computing Facility.Collections
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