Preparation of ruthenium catalyst

H2 reduction method. The elimination of chlorines in catalyst is an important role and step during the preparation of ruthenium catalyst. In order to eliminate the Cl in activated carbon supported ruthenium catalyst prepared using RuClg as the precursors, it is necessary that RuCla is reduced to elementary ruthenium and... 

Ruthenium hydride complexes, e.g., the dimer 34, have been used by Hofmann et al. for the preparation of ruthenium carbene complexes [19]. Reaction of 34 with two equivalents of propargyl chloride 35 gives carbene complex 36 with a chelating diphosphane ligand (Eq. 3). Complex 36 is a remarkable example because its phosphine ligands are, in contrast to the other ruthenium carbene complexes described so far, arranged in a fixed cis stereochemistry. Although 36 was found to be less active than conventional metathesis catalysts, it catalyzes the ROMP of norbornene or cyclopentene. 

Ru3(CO)i2 is the binary carbonyl of ruthenium that has been most used in the preparation of supported catalysts [90-99]. 

The preparation of the catalyst starts with the synthesis of 1-mes-ityl-3-(7-octene)-imidazole bromide. This compound is prepared by condensing mesityl imidazole with 8-bromooctene. The resulting salt is deprotonated with (TMS)2NK, where TMS is the tetrameth-ylsilyl radical. This step is performed in tetrahydrofuran at -30°C for 30 min. To this product a solution of the ruthenium complex (PCy3)2Cl2Ru=CHPh is added at 0°C. Bringing the solution slowly to room temperature, after 1 h the ligand displacement was determined to be complete. Afterwards, the reaction mixture is then diluted with n-pentane and heated to reflux for 2 h to induce intramolecular cyclization. 

Scheme 11. Preparation of aldehydes from terminal alkynes and water in the presence of ruthenium catalyst.

An example of the use of direct redox reactions in the preparation of bimetallic catalysts is the modification of copper catalysts by the addition of ruthenium, platinum, gold, or palladium [11-14], Assuming the metallic state for copper atoms on the surface, the redox reaction with the noble metal salts is... 

The development of a large-scale process for the DKR of alcohols using various lipases in combination with a range of ruthenium catalysts has been demonstrated. The reactions can be carried at concentrations up to 1M with lower catalyst loadings (Pamies, and Backvall, 2003b). The process for the preparation of (R)-3,5-bis-trifluoromethyl-phenylethan-l-ol using [RuCl2(p-... 

As more active members of the ruthenium catalyst family were developed, more complex systems could be prepared. For example, the first generation of ruthenium catalysts were very selective for less-substituted double bonds, and would not dose tri-substituted double bonds in medium-ring systems. As demonstrated below, Ru-1 would only react with the unsubstituted terminal double bond. However, the newer catalyst will convert the intermediate into the desired ring system containing a tri-substituted double bond (Eq. 6.5) [23]. 

The tolerance of ruthenium catalysts to a variety of functionality, and the efficiency of the reaction, have led to cross metathesis being used to prepare a variety of highly functionalized molecules. The examples in Eq. 6.17 demonstrate the array of functionality that can be tolerated [37]. 

Interestingly, alkyl groups on amines can be employed for the synthesis of unsymmetrical selenides in the presence of ruthenium catalysts prepared by the reduction of RuCls with potassium (Scheme 15.78) [159]. 

Preparation of ruthenium supported catalysts for wet air oxidation of p-hydroxybenzoic acid... 

In the present work, we investigated the influence of the metal precursor and of the nature of the support on the performences of ruthenium catalysts for the wet air oxidation of p-hydroxybenzoic (p-HBZ) acid chosen as a model of phenolic pollutants. Titanium and zirconium oxides were selected as supporting materials. The preparation method adopted for supports was sol-gel combined with the use of supercritical drying. The motivation of such combination is to prepare aerogel supports with high BET surface area and unique morphological and chemical properties [9,10]. 

Ruthenium-aluminium oxide/hydroxide catalyst ( 2.5wt% Ru loading). The preparation of this catalyst is described in Chapter 8 because it consists of Ru(0) nanoparticles encapsulated in an aluminium oxy-hydroxide... 

T. L6pez, A. Lopez-Gaona, and R. Gomez, Deactivation of Ruthenium Catalysts Prepared by the Sol-Gel Method in Reactions of Benzene Hydrogenation and n-Pentane Hydrogenolysis, Langmuir, 6, pp. 1343-46, 1990. 

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