Selective hydrogenations of (hetero)arenes represent essential processes in the chemical industry, especially for the production of polymer intermediates and a multitude of fine chemicals. Herein, we describe a new type of well-dispersed Ru nanoparticles supported on a nitrogen-doped carbon material obtained from ruthenium chloride and dicyanamide in a facile and scalable method. These novel catalysts are stable and display both excellent activity and selectivity in the hydrogenation of aromatic ethers, phenols as well as other functionalized substrates to the corresponding alicyclic reaction products. Furthermore, reduction of the aromatic core is preferred over hydrogenolysis of the C–O bond in the case of ether substrates. The selective hydrogenation of biomass-derived arenes, such as lignin building blocks, plays a pivotal role in the exploitation of novel sustainable feedstocks for chemical production and represents a notoriously difficult transformation up to now.
Catalytic hydrosilylation
represents a straightforward and atom-efficient
methodology for the creation of C–Si bonds. In general, the
application of homogeneous platinum complexes prevails in industry
and academia. Herein, we describe the first heterogeneous single atom
catalysts (SACs), which are conveniently prepared by decorating alumina
nanorods with platinum atoms. The resulting stable material efficiently
catalyzes hydrosilylation of industrially relevant olefins with high
TON (≈105). A variety of substrates is selectively
hydrosilylated including compounds with sensitive reducible and other
functional groups (N, B, F, Cl). The single atom based catalyst shows
significantly higher activity compared to related Pt nanoparticles.
For the first time N-graphitic-modified cobalt nanoparticles (Co/phen@SiO 2 -800) are shown to be active in the semihydrogenation of alkynes to alkenes. Key to success for efficient catalysis is both the modification of the metal nanoparticles by nitrogen-doped graphitic layers and the use of silica as support. Several internal alkynes are converted to the Z isomer in high yields with up to 93% selectivity. In addition, a variety of terminal alkynes, including sensitive functionalized compounds, are readily converted into terminal alkenes. Notably, this non-noble-metal catalyst allows for the purification of alkenes by selective hydrogenation of the corresponding alkyne in the presence of an excess of olefin.
Nitrogen modified cobalt nanoparticles are easily prepared from melamine or melamine resins. The resulting catalysts show excellent selectivity for transfer hydrogenation of N-heteroarenes.
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