Hydrogen-Bonding-Mediated Selective Hydrogenation of Aromatic Ketones over Pd/C in Ionic Liquids at Room Temperature
journal contributionposted on 11.10.2021, 21:30 authored by Ruipeng Li, Yuepeng Wang, Yanfei Zhao, Fengtao Zhang, Wei Zeng, Minhao Tang, Junfeng Xiang, Xiaoyu Zhang, Buxing Han, Zhimin Liu
Selective hydrogenation of aromatic ketones without hydrogenation of aromatic rings over Pd/C is very interesting but still challenging. Herein, we report a hydrogen-bonding-mediated strategy for selective hydrogenation of aryl ketones to either aryl alcohols or aryl alkanes at room temperature, which is achieved over Pd/C in imidazolium-based ionic liquids (ILs) via altering the IL anions from [Cl]− to [BF4]−. 1-Butyl-3-methyl-imidazolium ([BMIm]+) ILs with [Cl]− and [BF4]− anions show high performances, affording a series of aromatic alcohols or alkanes with 100% selectivity and high yields, respectively. Mechanism investigation indicates that the π–π interaction between the ILs and the aromatic ring of the ketones may inhibit the hydrogenation of the aromatic ring, and the dual H-bonding interaction of the IL cation and anion with the resultant alcohol from the ketone hydrogenation mediates the hydrogenation selectivity. This catalytic protocol is simple, highly efficient, and selective toward target products, which may have promising applications.
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mechanism investigation indicatesketone hydrogenation mediatesbased ionic liquidseither aryl alcoholsketones may inhibitmediated selective hydrogenationionic liquidsselective hydrogenationaryl ketonesmediated strategyaromatic alcoholsaromatic ketonesvia alteringstill challengingroom temperatureresultant alcoholpromising applicationsil cationil anionshighly efficienthigh yieldsdual hcatalytic protocolaromatic ringsaromatic ring