Palladium-catalyzed aryl-aryl coupling in water using molecular hydrogen: kinetics and process optimization of a solid-liquid-gas system

Mukhopadhyay, Sourav; Rothenberg, Gadi; Wiener, Harold; Sasson, Yoel

doi:10.1016/s0040-4020(99)00920-5

Cited by 90 publications

(59 citation statements)

References 21 publications

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“…Two reaction pathways are possible: Reductive coupling, where Pd 2+ is generated and reduced back to Pd(0) using an external reducing agent, and oxidative coupling, which starts with Pd 2+ and needs an oxidising agent. Various reagents can be used for closing the reductive coupling cycle, including HCO 2 À , [4] H 2 gas, [5] Zn/H 2 O, [6] and alcohols. [7] The two pathways can even be joined, giving a tandem system that converges on one product.…”

Section: Introductionmentioning

confidence: 99%

Electroreductive Palladium‐Catalysed Ullmann Reactions in Ionic Liquids: Scope and Mechanism

2006

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A room-temperature catalytic alternative to the Ullmann reaction is presented, based on electroreductive homocoupling of haloarenes catalysed by palladium nanoparticles. The particles are generated in situ in an electrochemical cell, and electrons are used to close the catalytic cycle and provide the motivating force for the reaction. This system gives good yields using iodo-and bromoarenes, and requires only electric current and water as reagents. Using an ionic liquid solvent combines the advantages of excellent conductivity and cluster stabilising. The solvent is reusable at least five times. Kinetic experiments at different electrode potentials show that the two-electron oxidation of water closes the catalytic cycle by regenerating the Pd(0). A mechanism involving radical anion formation is proposed. The advantages and limitations of this new system for carbon-carbon homocoupling and cross-coupling are discussed.

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Section: Introductionmentioning

confidence: 99%

Electroreductive Palladium‐Catalysed Ullmann Reactions in Ionic Liquids: Scope and Mechanism

2006

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“…Palladium-catalyzed homocoupling reactions offer a mild alternative to the classical Ullman coupling, usually conducted with copper catalysts under rather harsh conditions. [33] Although homocoupling reactions of deactivated aryl chlorides catalyzed by heterogeneous palladium have been reported to take place even in water with moderate yields, [34] the novelty of our system is that the polyaniline nanofibers also act as the reductant, a role usually played by an external reducing agent such as formate salts, [35] hydrogen gas, [36] or zinc. [37] We tested the Pd/PANI system as catalyst for other reactions.…”

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confidence: 99%

Palladium Nanoparticles Supported on Polyaniline Nanofibers as a Semi‐Heterogeneous Catalyst in Water

et al. 2007

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“…In comparison to the 1 H and 13 C NMR spectra of acid 2, the aromatic region of the dimer shows signals corresponding to only two aromatic protons. In the 1 H NMR spectra at room temperature all signals of the side product are broadened, but their chemical shifts are very similar to the monomer, acid 2.…”

Section: Introductionmentioning

confidence: 93%

“…[7][8][9] Palladium has also been shown to catalyze aryl halide homocoupling under elevated reaction temperatures in the presence of a reducing agent under both transfer [10][11][12] and catalytic hydrogenation conditions. 13 The transfer type process is discussed in more detail in the literature and the following parameters promote the formation of Ullmann dimers: phase transfer conditions, presence of strong bases, elevation of temperature and increasing amounts of catalyst.…”

Section: Introductionmentioning

confidence: 99%

Optimization of a catalytic hydrogenation procedure of a prostaglandin intermediate by DOE methods

Rozsumberszki¹,

Horváth²,

Bokotey³

et al. 2004

Arkivoc

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An optimization procedure for the preparation of Beraprost key intermediate 2 is described. The catalytic hydrogenation of lactone 3 was optimized by Design of Experiment (DoE) methods for minimal Ullmann type side product formation. Experiments used a fractional factorial design method followed by a central composite design allowing optimization of a number of factors as well as statistical analysis of results. The response surface analysis showed that the rate of the side reaction, in a defined experimental area, can be described by a second-order polynomial equation in which the water content and the status of the catalyst are the major influences. The results confirm the mechanistic hypothesis of dimer production as a side reaction on the surface of the catalyst.

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Palladium-catalyzed aryl-aryl coupling in water using molecular hydrogen: kinetics and process optimization of a solid-liquid-gas system

Cited by 90 publications

References 21 publications

Electroreductive Palladium‐Catalysed Ullmann Reactions in Ionic Liquids: Scope and Mechanism

Electroreductive Palladium‐Catalysed Ullmann Reactions in Ionic Liquids: Scope and Mechanism

Palladium Nanoparticles Supported on Polyaniline Nanofibers as a Semi‐Heterogeneous Catalyst in Water

Optimization of a catalytic hydrogenation procedure of a prostaglandin intermediate by DOE methods

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