Using surface-specific HD-SFG vibrational spectroscopy, we examine water molecular structure at a freely suspended graphene/water interface, finding that the SFG response mainly arises from the topmost 1–2 water layers, with minimal contribution ...
Artikel
Electrochemical Nickel‐Catalyzed Hydrogenation
Von Wiley-VCH zur Verfügung gestellt
An economical and efficient electrochemical Ni-catalyzed alkene hydrogenation is described. The reaction features outstanding substrate generality and functional group compatibility, and distinct chemoselectivity. Notably, hydrodebromination of alkyl and aryl bromides can be realized using the same reaction system with a different ligand, and high chemoselectivity between hydrogenation of alkene and hydrodebromination could be achieved through ligand selection.
Abstract
Olefin hydrogenation is one of the most important transformations in organic synthesis. Electrochemical transition metal-catalyzed hydrogenation is an attractive approach to replace the dangerous hydrogen gas with electrons and protons. However, this reaction poses major challenges due to rapid hydrogen evolution reaction (HER) of metal-hydride species that outcompetes alkene hydrogenation step, and facile deposition of the metal catalyst at the electrode that stalls reaction. Here we report an economical and efficient strategy to achieve high selectivity for hydrogenation reactivity over the well-established HER. Using an inexpensive and bench-stable nickel salt as the catalyst, this mild reaction features outstanding substrate generality and functional group compatibility, and distinct chemoselectivity. In addition, hydrodebromination of alkyl and aryl bromides could be realized using the same reaction system with a different ligand, and high chemoselectivity between hydrogenation and hydrodebromination could be achieved through ligand selection. The practicability of our method has been demonstrated by the success of large-scale synthesis using catalytic amount of electrolyte and a minimal amount of solvent. Cyclic voltammetry and kinetic studies were performed, which support a NiII/0 catalytic cycle and the pre-coordination of the substrate to the nickel center.
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