Hydrogenation on NHC-Modified Ru/K-Al2O3 Catalysts

Yasuhiro Uozumi; Takuma Sato

doi:10.1055/s-0036-1589442

Synfacts, Table of Contents

Synfacts 2016; 12(12): 1313
DOI: 10.1055/s-0036-1589442

Polymer-Supported Synthesis

Hydrogenation on NHC-Modified Ru/K-Al₂O₃ Catalysts

Authors

Yasuhiro Uozumi
Takuma Sato

Abstract

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Ernst JB, Muratsugu S, * Wang F, Tada M, Glorius F. * Westfälische Wilhelms-Universität Münster, Germany and Nagoya University, Japan
Tunable Heterogeneous Catalysis: N-Heterocyclic Carbenes as Ligands for Supported Heterogeneous Ru/K-Al₂O₃ Catalysts to Tune Reactivity and Selectivity.

J. Am. Chem. Soc. 2016;
138: 10718-10721

Key words

N-heterocyclic carbenes - ruthenium catalysis - hydrogenation - heterogeneous catalysis - ligands

Significance

A surface-modification method was developed for tuning the catalytic performance of ruthenium nanoparticles supported on K-doped alumina (Ru/K-Al₂O₃) by using N-heterocyclic carbene (NHC) ligands. For example, the hydrogenation of ethynylbenzene (1) under hydrogen in the presence of unmodified Ru/K-Al₂O₃ gave ethylcyclohexane (3) as the sole product in 95% yield, whereas the use of IMes/Ru/K-Al₂O₃ or ICy/Ru/ K-Al₂O₃ (2 mol% ruthenium, NHC-modified Ru/K-Al₂O₃, 3.0 equiv of the NHC based on surface ruthenium) as a catalyst under similar conditions gave ethylbenzene (2) as the sole product in 89% and 92% yield, respectively.

Comment

The catalysts were characterized by means of ¹³C solid-state NMR, Ru 3p XPS, Ru K-edge EXAFS, and TEM. The particle size of ruthenium (TEM), the oxidation state of ruthenium (XPS), and the Ru–Ru coordination number (EXAFS) remained unchanged after the surface modification. In addition, ¹³C NMR spectroscopy confirmed that the carbene carbon was directly attached to the ruthenium nanoparticles.

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