Base-Free Transfer Hydrogenation with an Ionic-Liquid-Supported Ruthenium ηp>6p>-Arene Bis(pyrazolyl)methane Catalyst

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• 作者：Francisco Sepú ; lveda ; M. Carmen Carrió ; n ; Andrew D. Phillips ; F&eacute ; lix A. Jaló ; n ; Paul J. Dyson and Blanca R. Manzano
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：2017
• 期：3
• 页码：630-638
• 全文大小：1874K
• ISSN：1099-0682c

文摘

Ruthenium complexes of the type [RuCl(ηp>6p>-arene)(NN)]X (X = BF₄ or BPh₄) featuring an ηp>6p>-arene ligand modified with an imidazolium ring and incorporating the bis(azo) chelating (NN) ligands 2-hydroxyphenylbis(3,5-dimethylpyrazol-1-yl)methane or 2-nitrophenylbis(3,5-dimethylpyrazol-1-yl)methane are reported. The catalytic activities of the complexes were evaluated in the transfer hydrogenation of benzaldehyde to benzyl alcohol with iPrOH as the hydrogen donor in the absence of a base and under biphasic conditions; one of the two phases was iPrOH, and the other was an ionic liquid. The catalysts featuring the imidazolium-modified ηp>6p>-arene could be recycled and reused with only a minor decrease in substrate conversion after multiple reaction cycles. The reaction rate was strongly influenced by the type of ionic liquid employed in the biphasic system.