Ruthenium catalysts, heterogeneous

K. Yamaguchi, N. Mizuno, Supported Ruthenium Catalyst for the Heterogeneous Oxidation of Alcohols. Chem. 41 (2002) 4538-4531. 

Accordingly, the synthesis of highly active and selective heterogeneous catalysts has been explored in recent years. Among these, ruthenium-based catalysts have been found to show interesting catalytic activity, and various types of ruthenium-based heterogeneous catalyst have been developed [7]. 

Chandler BD, Gilbertson JD (2006) Dendrimer-Encapsulated Bimetallic Nanoparticles Synthesis, Characterization, and Applications to Homogeneous and Heterogeneous Catalysis. 20 97-120 ChataniN (2004) Selective Carbonylations with Ruthenium Catalysts. 11 173-195 Chatani N, see Kakiuchi F (2004) 11 45-79... 

Table 7 Oxidation of primary and secondary amines using heterogeneous ruthenium catalysts with molecular oxygen...

Other examples of heterogeneous ruthenium catalysts are a ruthenium-based hydroxyapatite catalyst [158], a ferrite spinel-based catalyst MnFe1.5Ruo.35 CU0.15O4 [159], and Ru supported on Ce02 [160], which all gave lower activities. 

Another class of ruthenium catalysts, which has attracted considerable interest due to their inherent stability under oxidative conditions, are the polyoxome-talates [161]. Recently, Mizuno et al. [162] reported that a mono-ruthenium-sub-stituted silicotungstate, synthesized by the reaction of the lacunary polyoxometa-late [SiWu039]8- with Ru3+ in an organic solvent, acts as an efficient heterogeneous catalyst with high turnover frequencies for the aerobic oxidation of alcohols (see Fig. 4.63). Among the solvents used 2-butyl acetate was the most... 

Compared to the multistep electron-transfer process shown in Scheme 3.4, more simple aerobic oxidations of alcohols were reported with various homogeneous and heterogeneous ruthenium catalysts. The aerobic oxidation of alcohols with metal catalysts is an attractive method for economical and environmental reasons. Aerobic oxidation of alcohols can be carried out using RUCI3 catalyst with moderate conversion and selectivities (Eq. 3.13) [31]. Since this reaction was first reported, an arduous search for suitable catalysts has been continuing using various ruthenium complexes (Table 3.1). 

Platinum oxide-Fe or Cu-containing catalysts allow hydrogenation of furfural to furfurylalcohol". Ruthenium catalysts (Ru—C, RuOj) are successful in this specific case they have an activity well preserved through reuses. Otherwise Ru exhibits little activity in the heterogeneous hydrogenation of aromatic aldehydes. Other heterogeneous catalysis include platinized (PtC ) Raney Ni and copper chromite. 

Initial attempts were made by ter Halle et al.[7] to convert the homogeneous ruthenium catalyst into a heterogeneous catalyst by incorporating the metal center in a solid support using polymerizable diamine ligands. Unfortunately, both the conversions and % ee s for the transfer hydrogenations were low compared to the... 

Chauvin et al. reported the asymmetric hydrogenation of acetamidocinnamic acid to (S)-phenylalanine with a cationic chiral rhodium catalyst in [C4-mim][SbF6] ionic liquid, more recently the 2-arylacryhc acid has been produced with a reasonable 64% yield using a chiral ruthenium catalysts in [C4-mim][BF4] ionic hquids. Palladium catalysts immobilized in an ionic liquid-polymer gel membrane containing either [C2-mim][CF3S03] or [C2-mim][BF4] have also been reported as catalysts for heterogeneous hydrogenation reactions. 

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