Recyclable cobalt(0) nanoparticle catalysts for hydrogenations
作者:Philipp Büschelberger、Efrain Reyes-Rodriguez、Christian Schöttle、Jens Treptow、Claus Feldmann、Axel Jacobi von Wangelin、Robert Wolf
DOI:10.1039/c8cy00595h
日期:——
The search for new hydrogenationcatalysts that replace noble metals is largely driven by sustainability concerns and the distinct mechanistic features of 3d transition metals. Several combinations of cobalt precursors and specific ligands in the presence of reductants or under high-thermal conditions were reported to provide activehydrogenationcatalysts. This study reports a new method of preparation
寻找替代贵金属的新型加氢催化剂的主要原因是对可持续性的关注以及3d过渡金属的独特机械特性。据报道,在还原剂存在下或在高温条件下,钴前体和特定配体的几种组合可提供活性加氢催化剂。这项研究报告了一种在不存在配体或表面活性剂的情况下通过还原商业CoCl 2制备小的单分散Co(0)纳米颗粒(3-4 nm)的新方法。在烯烃,炔烃,亚胺和杂芳烃(2–20 bar H 2)的氢化中观察到高催化活性。磁性使催化剂分离和多次回收成为可能。
Alkene Hydrogenations by Soluble Iron Nanocluster Catalysts
作者:Tim N. Gieshoff、Uttam Chakraborty、Matteo Villa、Axel Jacobi von Wangelin
DOI:10.1002/anie.201612548
日期:2017.3.20
sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron‐catalyzed hydrogenation protocol for tri‐ and tetra‐substituted alkenes of unprecedented activity and scope under mild conditions (1–4 bar H2, 20 °C). Instructive snapshots at the interface of homogeneous and heterogeneous ironcatalysis were recorded by the isolation
贵金属技术的替代以及利用地球上丰富的金属实现新的反应性是可持续合成的核心。迄今为止,烯烃加氢最有效地是通过贵金属催化剂进行的。本研究报道了一种铁催化的三取代和四取代烯烃氢化方案,该方案在温和条件(1-4 bar H 2,20 °C)下具有前所未有的活性和范围。通过分离充当催化剂库和颗粒生长的可溶种子的新型铁纳米簇结构,记录了均相和非均相铁催化界面的指导性快照。
Cobalt-Catalyzed Hydrogenations via Olefin Cobaltate and Hydride Intermediates
作者:Sebastian Sandl、Thomas M. Maier、Nicolaas P. van Leest、Susanne Kröncke、Uttam Chakraborty、Serhiy Demeshko、Konrad Koszinowski、Bas de Bruin、Franc Meyer、Michael Bodensteiner、Carmen Herrmann、Robert Wolf、Axel Jacobi von Wangelin
DOI:10.1021/acscatal.9b01584
日期:2019.8.2
moderate electron transfer processes within base-metal catalysts. This report introduces bis(imino)acenaphthene (BIAN) cobaltate complexes as hydrogenation catalysts. Sterically hindered trisubstituted alkenes, imines, and quinolines underwent clean hydrogenation under mild conditions (2–10 bar, 20–80 °C) by use of the stable catalyst precursor [(DippBIAN)CoBr2] and the cocatalyst LiEt3BH. Mechanistic
A Manganese Nanosheet: New Cluster Topology and Catalysis
作者:Uttam Chakraborty、Efrain Reyes-Rodriguez、Serhiy Demeshko、Franc Meyer、Axel Jacobi von Wangelin
DOI:10.1002/anie.201800079
日期:2018.4.23
and the surface characteristics of larger metal particles are well understood, preparations of molecular metallic nanoclusters remain a great challenge. Discrete planar metal clusters constitute nanoscale snapshots of cluster growth but are especially rare owing to the strong preference for three‐dimensional structures and rapid aggregation or decomposition. A simple ligand‐exchange procedure has led
Olefin-Stabilized Cobalt Nanoparticles for C=C, C=O, and C=N Hydrogenations
作者:Sebastian Sandl、Felix Schwarzhuber、Simon Pöllath、Josef Zweck、Axel Jacobi von Wangelin
DOI:10.1002/chem.201705366
日期:2018.3.7
hazardous reductants, special reaction conditions, and the formation of highly unstable pre‐catalysts. Reduction of CoBr2 with LiEt3BH in the presence of alkenes led to the formation of hydrogenation catalysts that effected clean conversions of alkenes, carbonyls, imines, and heteroarenes at mild conditions (3 mol % cat., 2–10 bar H2, 20–80 °C). Poisoning studies and nanoparticle characterization by
结合了易接近性和高选择性的钴催化剂的开发构成了在氢化反应中替代贵金属催化剂的有前途的方法。本报告介绍了一种用户友好的规程,避免了复杂的配体,危险的还原剂,特殊的反应条件以及高度不稳定的预催化剂的形成。在烯烃存在下用LiEt 3 BH还原CoBr 2导致形成加氢催化剂,该催化剂在温和条件下(3 mol%的催化剂,2-10 bar H 2,可实现烯烃,羰基,亚胺和杂芳烃的干净转化)20–80°C)。通过TEM,EDX和DLS进行的中毒研究和纳米颗粒表征支持了异位催化机制的概念。