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Transition metal-catalysis metals

The /n j -I,4-polybutadiene made by transition-metal catalysis (112,113) is a resin-like material that has two melting temperatures, 50 and I50°C. [Pg.534]

Transition metal catalysis in Baeyer-Villiger oxidation of cyclic ketones with formation of lactones 98AG(E)1198. [Pg.223]

Transition metal catalysis in liquid/liquid biphasic systems principally requires sufficient solubility and immobilization of the catalysts in the IL phase relative to the extraction phase. Solubilization of metal ions in ILs can be separated into processes, involving the dissolution of simple metal salts (often through coordination with anions from the ionic liquid) and the dissolution of metal coordination complexes, in which the metal coordination sphere remains intact. [Pg.70]

The first example of homogeneous transition metal catalysis in an ionic liquid was the platinum-catalyzed hydroformylation of ethene in tetraethylammonium trichlorostannate (mp. 78 °C), described by Parshall in 1972 (Scheme 5.2-1, a)) [1]. In 1987, Knifton reported the ruthenium- and cobalt-catalyzed hydroformylation of internal and terminal alkenes in molten [Bu4P]Br, a salt that falls under the now accepted definition for an ionic liquid (see Scheme 5.2-1, b)) [2]. The first applications of room-temperature ionic liquids in homogeneous transition metal catalysis were described in 1990 by Chauvin et al. and by Wilkes et ak. Wilkes et al. used weekly acidic chloroaluminate melts and studied ethylene polymerization in them with Ziegler-Natta catalysts (Scheme 5.2-1, c)) [3]. Chauvin s group dissolved nickel catalysts in weakly acidic chloroaluminate melts and investigated the resulting ionic catalyst solutions for the dimerization of propene (Scheme 5.2-1, d)) [4]. [Pg.214]

Scheme 5.2-1 Early examples of transition metal catalysis in ionic liquids. Scheme 5.2-1 Early examples of transition metal catalysis in ionic liquids.
However, a number of limitations are still evident when tetrafluorohorate and hexafluorophosphate ionic liquids are used in homogeneous catalysis. The major aspect is that these anions are still relatively sensitive to hydrolysis. The tendency to anion hydrolysis is of course much less pronounced than that of the chloroalu-minate melts, hut it still occurs and this has major consequences for their use in transition metal catalysis. For example, the [PF ] anion of l-hutyl-3-methylimida-2olium ([BMIM]) hexafluorophosphate was found (in the author s laboratories) to hydrolyze completely after addition of excess water when the sample was kept for 8 h at 100 °C. Gaseous HF and phosphoric acid were formed. Under the same conditions, only small amounts of the tetrafluorohorate ion of [BMlMjjBFJ was converted into HF and boric acid [10]. The hydrolytic formation of HF from the anion of the ionic liquid under the reaction conditions causes the following problems with... [Pg.215]

In this context, the use of ionic liquids with halogen-free anions may become more and more popular. In 1998, Andersen et al. published a paper describing the use of some phosphonium tosylates (all with melting points >70 °C) in the rhodium-catalyzed hydroformylation of 1-hexene [13]. More recently, in our laboratories, we found that ionic liquids with halogen-free anions and with much lower melting points could be synthesized and used as solvents in transition metal catalysis. [BMIM][n-CgHi7S04] (mp = 35 °C), for example, could be used as catalyst solvent in the rhodium-catalyzed hydroformylation of 1-octene [14]. [Pg.216]

The author anticipates that the further development of transition metal catalysis in ionic liquids will, to a significant extent, be driven by the availability of new ionic liquids with different anion systems. In particular, cheap, halogen-free systems combining weak coordination to electrophilic metal centers and low viscosity with high stability to hydrolysis are highly desirable. [Pg.216]

Very recently, Olivier-Bourbigou and Magna [15], Sheldon [16], and Gordon [17] have published three excellent reviews presenting a comprehensive overview of current work in transition metal catalysis involving ionic liquids, with slightly different emphases. All three update previously published reviews on the same topic, by Wasserscheid and Keim [18], Welton [19] and Seddon and Holbrey [20]. [Pg.216]

Why use Ionic Liquids as Solvents for Transition Metal Catalysis ... [Pg.217]

Probably the most prominent property of an ionic liquid is its lack of vapor pressure. Transition metal catalysis in ionic liquids can particularly benefit from this on economic, environmental, and safety grounds. [Pg.217]

Because of the great importance of liquid-liquid biphasic catalysis for ionic liquids, all of Section 5.3 is dedicated to specific aspects relating to this mode of reaction, with special emphasis on practical, technical, and engineering needs. Finally, Section 5.4 summarizes a very interesting recent development for biphasic catalysis with ionic liquids, in the form of the use of ionic liquid/compressed CO2 biphasic mixtures in transition metal catalysis. [Pg.220]

Ionic liquids with wealdy coordinating, inert anions (such as [(CF3S02)2N] , [BFJ , or [PFg] under anhydrous conditions) and inert cations (cations that do not coordinate to the catalyst themselves, nor form species that coordinate to the catalyst under the reaction conditions used) can be looked on as innocent solvents in transition metal catalysis. In these cases, the role of the ionic liquid is solely to provide a more or less polar, more or less weakly coordinating medium for the transition metal catalyst, but which additionally offers special solubility for feedstock and products. [Pg.221]

Ionic liquids formed by treatment of a halide salt with a Lewis acid (such as chloro-aluminate or chlorostannate melts) generally act both as solvent and as co-catalyst in transition metal catalysis. The reason for this is that the Lewis acidity or basicity, which is always present (at least latently), results in strong interactions with the catalyst complex. In many cases, the Lewis acidity of an ionic liquid is used to convert the neutral catalyst precursor into the corresponding cationic active form. The activation of Cp2TiCl2 [26] and (ligand)2NiCl2 [27] in acidic chloroaluminate melts and the activation of (PR3)2PtCl2 in chlorostannate melts [28] are examples of this land of activation (Eqs. 5.2-1, 5.2-2, and 5.2-3). [Pg.221]

Obviously, with the development of the first catalytic reactions in ionic liquids, the general research focus turned away from basic studies of metal complexes dissolved in ionic liquids. Today there is a clear lack of fundamental understanding of many catalytic processes in ionic liquids on a molecular level. Much more fundamental work is undoubtedly needed and should be encouraged in order to speed up the future development of transition metal catalysis in ionic liquids. [Pg.229]

Selected Examples of the Application of Ionic Liquids in Transition Metal Catalysis 5.2.4.1 Hydrogenation... [Pg.229]

However, research into transition metal catalysis in ionic liquids should not focus only on the question of how to make some specific products more economical or ecological by use of a new solvent and, presumably, a new multiphasic process. Since it bridges the gap between homogeneous and heterogeneous catalysis, in a novel and highly attractive manner, the application of ionic liquids in transition metal catalysis gives access to some much more fundamental and conceptual questions for basic research. [Pg.253]


See other pages where Transition metal-catalysis metals is mentioned: [Pg.223]    [Pg.826]    [Pg.826]    [Pg.831]    [Pg.70]    [Pg.213]    [Pg.213]    [Pg.214]    [Pg.215]    [Pg.216]    [Pg.217]    [Pg.217]    [Pg.217]    [Pg.219]    [Pg.220]    [Pg.221]    [Pg.223]    [Pg.225]    [Pg.227]    [Pg.229]    [Pg.231]    [Pg.233]    [Pg.233]    [Pg.235]    [Pg.237]    [Pg.239]    [Pg.241]    [Pg.243]    [Pg.245]    [Pg.247]    [Pg.249]    [Pg.251]    [Pg.253]    [Pg.253]   


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Acids Cleavable by Transition Metal Catalysis

Addition polymers transition metal catalysis

Addition transition metal-catalysis

Alkanes transition metal catalysis

Alkenes transition metal catalysis

Alkylation of Nitro Compounds Using Transition Metal Catalysis

Application of Transition Metal Catalysis in Heterocyclic Synthesis (Typical Examples)

Aqueous transition metal catalysis

Asymmetric catalysis with transition metal

Biphasic systems transition metal catalysis

Carbonylation transition metal catalysis

Catalysis by transition metals

Catalysis continued transition metals

Catalysis transition metal

Catalysis transition metal

Catalysis transition metal catalysts

Catalysis transition metal compounds

Catalysis transition metal oxides

Catalysis transition metal-catalyzed alcohol oxidation

Catalysis via Transition Metal-Mediated Carbene Transfer to Sulfides

Combinatorial asymmetric transition metal catalysis

Conclusion What Photochemical Techniques Can Provide in Mechanistic Studies of Transition Metal Catalysis

Cross transition metal-catalysis

Cumulative Subject transition metal catalysis

Cycloaddition transition metal-catalysis

Cyclohexane transition metal catalysis

Dehydrogenation transition metal catalysis

Dienes transition metal catalysis

General Comments on Catalysis using Transition Metal Nanoparticles

Green solvents transition metal catalysis

Hard Catalysis with Transition Metal Compounds

Heptane, 3-methyloxidation transition metal catalysis

Homogeneous Catalysis by Transition Metal Complexes

Homogeneous Catalysis of Hydrosilation by Transition Metals

Homogeneous Catalysis with Transition Metal Catalysts

Homogeneous Transition-Metal Catalysis in Molten Salts

Homogeneous acid-base catalysis transition metals

Homogeneous catalysis transition-metal halides

Homogeneous catalysis, transition metal

Homogeneous catalysis, transition metal clusters

Hydrogenation transition metal catalysis

Immobilization of Transition Metal Complexes and Their Application to Enantioselective Catalysis

Ionic transition metal catalysis

Jafarpour. Laleh. and Nolan, Steven P Transition-Metal Systems Bearing a Nucleophilic Carbene Ancillary Ligand from Thermochemistry to Catalysis

Ketenes transition metal catalysis

Ketones transition metal catalysis

Late Transition Metal Polymerization Catalysis

Ligands transition metal catalysis

Liquid-solid system, transition metal catalysis

Michael addition transition metal catalysis

Molecular orbital symmetry conservation in transition metal catalysis

Multiphasic systems transition metal catalysis

Nickel Transition Metal Catalysis

Nucleophilic displacement with transition metal catalysis

Oxidative coupling transition metal catalysis

Oxygen transition-metal catalysis

PSiP Transition-Metal Pincer Complexes Synthesis, Bond Activation, and Catalysis

Polyenes transition metal catalysis

Polymers via Late Transition Metal Catalysis

Protecting Groups Cleaved by Transition Metal Catalysis

Reactions with carbon electrophiles transition metal catalysis

Reactions with dienes transition metal catalysis

Self-Assembled Ligands in Transition Metal Catalysis

Soft Catalysis with Transition Metal Compounds

Solvent transition metal catalysis

Substitution transition metal catalysis

The Role of Transition Metal Hydrides in Homogeneous Catalysis

Transition Metal Catalysis in Ionic Liquids

Transition Metals in Catalysis and Electron Transport

Transition catalysis

Transition metal catalysis addition-fragmentations

Transition metal catalysis amine oxidation

Transition metal catalysis and natural gas generation

Transition metal catalysis aqueous biphasic systems

Transition metal catalysis aromatic substitution

Transition metal catalysis asymmetric hydrogenation

Transition metal catalysis asymmetric reduction

Transition metal catalysis carbene reactions

Transition metal catalysis carbenes

Transition metal catalysis cobalt complexes

Transition metal catalysis copper

Transition metal catalysis coupling reactions

Transition metal catalysis cycloisomerizations

Transition metal catalysis fundamental properties

Transition metal catalysis historical background

Transition metal catalysis hydroformylation

Transition metal catalysis intermolecular

Transition metal catalysis intramolecular

Transition metal catalysis nickel complexes

Transition metal catalysis nucleophilic substitution

Transition metal catalysis oxidation

Transition metal catalysis palladium chemistry

Transition metal catalysis production

Transition metal catalysis rearrangements

Transition metal catalysis reductive elimination

Transition metal catalysis, gold

Transition metal catalysis, gold palladium

Transition metal catalysis, gold ruthenium

Transition metal catalysis, initiators

Transition metal catalysis, molecular

Transition metal catalysis, molecular orbital symmetry conservation

Transition metal complexes catalysis

Transition metal complexes epoxidation catalysis

Transition metal ions catalysis

Transition metal sulfides catalysis

Transition metal, catalysis polymerization

Transition metals, binding catalysis

Transition-metal catalysis 16-18-electron rule

Transition-metal catalysis coordination number, geometry

Transition-metal catalysis coordinative unsaturation

Transition-metal catalysis formalisms

Transition-metal catalysis nanoparticles

Transition-metal catalysis overview

Transition-metal catalysis reduction

Transition-metal catalysis supported liquid phase

Transition-metal catalysis targets

Transition-metal heterogeneous catalysi

Transition-metal-based homogeneous catalysis

Why use Ionic Liquids as Solvents for Transition Metal Catalysis

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