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End date: 2019 × Start date: 2010 × Type: Text × Publisher: Cambridge : RSC × Subject: Selective hydrogenation × WGL Institute: LIKAT ×

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Now showing 1 - 4 of 4
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    Efficient and selective hydrogenation of amides to alcohols and amines using a well-defined manganese-PNN pincer complex
    (Cambridge : RSC, 2017) Papa, Veronica; Cabrero-Antonino, Jose R.; Alberico, Elisabetta; Spanneberg, Anke; Junge, Kathrin; Junge, Henrik; Beller, Matthias
    Novel well-defined NNP and PNP manganese pincer complexes have been synthetized and fully characterized. The catalyst Mn-2 containing an imidazolyaminolphosphino ligand shows high activity and selectivity in the hydrogenation of a wide range of secondary and tertiary amides to the corresponding alcohols and amines, under relatively mild conditions. For the first time, more challenging substrates like primary aromatic amides including an actual herbicide can also be hydrogenated using this earth-abundant metal-based pincer catalyst.
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    A robust iron catalyst for the selective hydrogenation of substituted (iso)quinolones
    (Cambridge : RSC, 2018) Sahoo, Basudev; Kreyenschulte, Carsten; Agostini, Giovanni; Lund, Henrik; Bachmann, Stephan; Scalone, Michelangelo; Junge, Kathrin; Beller, Matthias
    By applying N-doped carbon modified iron-based catalysts, the controlled hydrogenation of N-heteroarenes, especially (iso)quinolones, is achieved. Crucial for activity is the catalyst preparation by pyrolysis of a carbon-impregnated composite, obtained from iron(ii) acetate and N-aryliminopyridines. As demonstrated by TEM, XRD, XPS and Raman spectroscopy, the synthesized material is composed of Fe(0), Fe3C and FeNx in a N-doped carbon matrix. The decent catalytic activity of this robust and easily recyclable Fe-material allowed for the selective hydrogenation of various (iso)quinoline derivatives, even in the presence of reducible functional groups, such as nitriles, halogens, esters and amides. For a proof-of-concept, this nanostructured catalyst was implemented in the multistep synthesis of natural products and pharmaceutical lead compounds as well as modification of photoluminescent materials. As such this methodology constitutes the first heterogeneous iron-catalyzed hydrogenation of substituted (iso)quinolones with synthetic importance.
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    Highly selective hydrogenation of amides catalysed by a molybdenum pincer complex : Scope and mechanism
    (Cambridge : RSC, 2019) Leischner, Thomas; Suarez, Lluis Artús; Spannenberg, Anke; Nova, Ainara; Junge, Kathrin; Nova, Ainara; Beller, Matthias
    A series of molybdenum pincer complexes has been shown for the first time to be active in the catalytic hydrogenation of amides. Among the tested catalysts, Mo-1a proved to be particularly well suited for the selective C-N hydrogenolysis of N-methylated formanilides. Notably, high chemoselectivity was observed in the presence of certain reducible groups including even other amides. The general catalytic performance as well as selectivity issues could be rationalized taking an anionic Mo(0) as the active species. The interplay between the amide CO reduction and the catalyst poisoning by primary amides accounts for the selective hydrogenation of N-methylated formanilides. The catalyst resting state was found to be a Mo-alkoxo complex formed by reaction with the alcohol product. This species plays two opposed roles-it facilitates the protolytic cleavage of the C-N bond but it encumbers the activation of hydrogen. This journal is © The Royal Society of Chemistry.
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    Cobalt-based nanoparticles prepared from MOF-carbon templates as efficient hydrogenation catalysts
    (Cambridge : RSC, 2018) Murugesan, Kathiravan; Senthamarai, Thirusangumurugan; Sohail, Manzar; Alshammari, Ahmad S.; Pohl, Marga-Martina; Beller, Matthias; Jagadeesh, Rajenahally V.
    The development of efficient and selective nanostructured catalysts for industrially relevant hydrogenation reactions continues to be an actual goal of chemical research. In particular, the hydrogenation of nitriles and nitroarenes is of importance for the production of primary amines, which constitute essential feedstocks and key intermediates for advanced chemicals, life science molecules and materials. Herein, we report the preparation of graphene shell encapsulated Co3O4- and Co-nanoparticles supported on carbon by the template synthesis of cobalt-terephthalic acid MOF on carbon and subsequent pyrolysis. The resulting nanoparticles create stable and reusable catalysts for selective hydrogenation of functionalized and structurally diverse aromatic, heterocyclic and aliphatic nitriles, and as well as nitro compounds to primary amines (>65 examples). The synthetic and practical utility of this novel non-noble metal-based hydrogenation protocol is demonstrated by upscaling several reactions to multigram-scale and recycling of the catalyst.