Modified ruthenium-copper catalyst

The aziridination of olefins, which forms a three-membered nitrogen heterocycle, is one important nitrene transfer reaction. Aziridination shows an advantage over the more classic olefin hydroamination reaction in some syntheses because the three-membered ring that is formed can be further modified. More recently, intramolecular amidation and intermolecular amination of C-H bonds into new C-N bonds has been developed with various metal catalysts. When compared with conventional substitution or nucleophilic addition routes, the direct formation of C-N bonds from C-H bonds reduces the number of synthetic steps and improves overall efficiency.2 After early work on iron, manganese, and copper,6 Muller, Dauban, Dodd, Du Bois, and others developed different dirhodium carboxylate catalyst systems that catalyze C-N bond formation starting from nitrene precursors,7 while Che studied a ruthenium porphyrin catalyst system extensively.8 The rhodium and ruthenium systems are... 

Nickel, cobalt, copper, ruthenium, and copper-ruthenium catalysts modified with optically active amino acid or hydroxy acid have been extensively investigated by Klabunovskii s group since 1964 (82). However, those catalysts have been reported to have lower EDA than that of MRNi. 

Hydrogenation. Gas-phase catalytic hydrogenation of succinic anhydride yields y-butyrolactone [96-48-0] (GBL), tetrahydrofuran [109-99-9] (THF), 1,4-butanediol (BDO), or a mixture of these products, depending on the experimental conditions. Catalysts mentioned in the literature include copper chromites with various additives (72), copper—zinc oxides with promoters (73—75), and ruthenium (76). The same products are obtained by liquid-phase hydrogenation catalysts used include Pd with various modifiers on various carriers (77—80), Ru on C (81) or Ru complexes (82,83), Rh on C (79), Cu—Co—Mn oxides (84), Co—Ni—Re oxides (85), Cu—Ti oxides (86), Ca—Mo—Ni on diatomaceous earth (87), and Mo—Ba—Re oxides (88). Chemical reduction of succinic anhydride to GBL or THF can be performed with 2-propanol in the presence of Zr02 catalyst (89,90). 

In the case of powder bulk catalysts, Cu Raney was modified by direct redox reaction between reduced copper and the salt of a noble metal M (Ru, Pt and Au) [5, 7]. Typically the Cu-M bimetallic catalysts were obtained by mixing a freshly prepared Cu Raney with an aqueous solution of the noble metal salt. When the amount of M is in excess compared to the number of copper surface atoms, it appears that ruthenium deposition is restricted to approximately 1/3 of the copper surface atoms. For platinum and gold, a deposit larger than a monolayer is obtained, indicating that subsurface copper atoms are involved in direct redox reaction. This result is explained by the lower potential difference between copper and rathenium compared to those of copper and platinum or gold [7j. However, the reactions involved in the direct redox reaction may not be as simple as indicated in Section 9.2. A typical time distribution of ion concentrations in solution during the preparation of Cu-Pt is shown in Fig. 9.1. It can be observed that platinum ions disappear very rapidly from the solution while at the same time copper... 

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