Homogeneous Hydrogenation

Chaloner, Penny A.; Esteruelas, Miguel A.; Joó, Ferenc; Oro, Luis A.

doi:10.1007/978-94-017-1791-5

Cited by 234 publications

(210 citation statements)

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“…Indeed, metal hydrides exhibit a wide range of kinetic and thermodynamic acidity. [7] From Norton×s measurements in CH 3 CN, the pK a of 8.3 determined for [CoH(CO) 4 ] indicates that it is of comparable acidity to HCl in that solvent. [9] The molybdenum hydride [Mo(Cp)(CO) 3 H] is less acidic, with a pK a of 13.9.…”

Section: Introductionmentioning

confidence: 99%

“…Landmark discoveries followed, such as the report in 1970 by Schrock and Osborn of cationic Rh catalysts for hydrogenation of the C=O bond of ketones. [2] Progress in catalytic hydrogenations was so remarkable that by 1973 Brian James had written an entire book [3] devoted to ™Homogeneous Hydrogenation.∫ While many subtle mechanistic details were elucidated, [4] a pervasive mechanistic feature exhibited by nearly all of these catalysts is that two key steps are 1) binding of the unsaturated substrate to the metal, and 2) subsequent insertion of that substrate into a metal hydride bond (MÀH), as shown in generalized form in Equation (1) for the case of ketone hydrogenation.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic Ionic Hydrogenations

Bullock

2004

Chemistry A European J

290

206

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Catalytic ionic hydrogenation of ketones occurs by proton transfer to a ketone from a cationic metal dihydride, followed by hydride transfer from a neutral metal hydride. This contrasts with traditional catalysts for ketone hydrogenation that require binding of the ketone to the metal and subsequent insertion of the ketone into a M-H bond. Ionic hydrogenation catalysts based on the inexpensive metals molybdenum and tungsten have been developed based on mechanistic understanding of the individual steps required in the catalytic reaction.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Catalytic Ionic Hydrogenations

Bullock

2004

Chemistry A European J

290

206

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“…[1][2][3] One of the most important examples, RuHCl(CO)-A C H T U N G T R E N N U N G (PCy 3 ) 2 (2), has been extensively used for the challenging problem of polymer hydrogenation, a key technology in the synthesis of specialty materials, including engineering elastomers and thermoplastics. [4,5] Complex 2, used either directly or generated in situ, is among the most efficient catalysts in current use for the reduction of C=C bonds in nitrile-butadiene polymers [5][6][7][8] and unsaturated polymers derived from ringopening metathesis polymerization (ROMP).…”

Section: Introductionmentioning

confidence: 99%

“…The corresponding mono-NHC derivatives 3a/b form, among other products, during decomposition of the second-generation Grubbs catalysts RuCl 2 A…”

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confidence: 99%

Improved Syntheses of Versatile Ruthenium Hydridocarbonyl Catalysts Containing Electron‐Rich Ancillary Ligands

et al. 2008

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“…For instance, in smectites, interlayer spacing can be adjusted by introducing substituents, by pillaring or solvent swelling, or even by transformation to new structures, and the acidic nature of the structure can also usefully be altered to improve their selectivity. 3 In any aluminosilicate, the porous structure provides a high surface area that enables it to receive high charges of a welldispersed active component. Therefore, the industrial efficacy of aluminosilicates results from a combination of porosity and mechanical resistance.…”

mentioning

confidence: 99%

Preparation of rhodium catalysts on laminar and zeolitic structures by anchoring of organometallic rhodium

Blanco

Ruiz

Pesquera

et al. 2001

Applied Organom Chemis

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Rhodium catalysts supported on six different aluminosilicate structures were prepared by hydrogen reduction of a cationic organometallic rhodium complex anchored to the support. The precursor active phase was incorporated in acetone medium through ion exchange using [Rh(Me 2 CO) x (NBD)]-ClO 4 as the metal precursor species, in which NBD is 2,5-norbornadiene and (Me 2 CO) x is acetone. The effect of the structure and characteristics of the support on metal load and dispersion was studied in the heterogeneous catalysts thus prepared. The supports were characterized by X-ray diffraction, energy-dispersive X-ray analysis, volumetric adsorption and surface acidity. For the precursors and catalysts, the metal load was determined by UV±VIS spectra, the reduction temperature was determined by differential scanning calorimetry, and rhodium dispersion was measured by chemisorption. The structure of the materials used as supports had a great influence on the catalyst prepared. A higher metal content was achieved in the supports with laminar structures, whereas better dispersion was shown by the catalysts supported on zeolitic structures. Copyright # 2001 John Wiley & Sons, Ltd.KEYWORDS: organometallic rhodium; montmorillonite; zeolitic products; catalyst preparation Zeolites and zeolitic materials have an increasing role in heterogeneous catalysis, and are widely applied in largescale industrial processes. Developments in the synthesis and characterization of zeolites have favored the design of materials that efficiently accelerate the reaction and which, therefore, help to achieve favorable thermodynamics and rates, as well as controlling the selectivity of a chemical reaction.1 Activity, selectivity and durability are characteristics that favor the use of heterogeneous catalysts in a wide range of chemical reactions under different pressure and temperature conditions. In view of their characteristics, natural and synthetic aluminosilicates have been used as catalysts and heterogeneous catalysts for a great number of active phases. In addition, clays and zeolites have advantages as supports because they are chemically and physically robust, and inexpensive. Clays can easily be modified to improve their catalytic properties. For instance, in smectites, interlayer spacing can be adjusted by introducing substituents, by pillaring or solvent swelling, or even by transformation to new structures, and the acidic nature of the structure can also usefully be altered to improve their selectivity. 3 In any aluminosilicate, the porous structure provides a high surface area that enables it to receive high charges of a welldispersed active component. Therefore, the industrial efficacy of aluminosilicates results from a combination of porosity and mechanical resistance. Zeolites and zeolite-like products have regular pore and cage dimensions, which makes them different from other aluminosilicates. Most of the active sites are located in the molecular size pores and cages so that, during the reaction, the transforming molecules are subj...

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Homogeneous Hydrogenation

Cited by 234 publications

References 0 publications

Catalytic Ionic Hydrogenations

Catalytic Ionic Hydrogenations

Improved Syntheses of Versatile Ruthenium Hydridocarbonyl Catalysts Containing Electron‐Rich Ancillary Ligands

Preparation of rhodium catalysts on laminar and zeolitic structures by anchoring of organometallic rhodium

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