Turning Teflon-coated magnetic stirring bars to catalyst systems with metal nanoparticle trace deposits – A caveat and a chance

Vollmer, Christian; Schröder, Marcel; Thomann, Yi; Thomann, Ralf; Janiak, Christoph

doi:10.1016/j.apcata.2012.03.017

Cited by 33 publications

(28 citation statements)

References 50 publications

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“…In order to demonstrate the potential of the SLS 3d printing technology to create functional objects of various shapes, 3d printed sleeves for magnetic stirring bars were fabricated (Figure ). Impregnation of Teflon coated magnetic stirrers with transition metals has been suggested as an attractive approach to fabrication of reusable catalysts, and our group has advanced this idea by implementing removable 3d printed sleeves for stirring bars . Such design provides the advantages of constant renewal of the liquid layer around the catalyst during the reaction due to stirring, and easy removal of the catalyst from the reaction mixture by using a magnetic rod.…”

Section: Resultsmentioning

confidence: 99%

3D Printed Palladium Catalyst for Suzuki‐Miyaura Cross‐coupling Reactions

et al. 2020

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Selective laser sintering (SLS) 3d printing was utilized to manufacture a solid catalyst for Suzuki-Miyaura cross-coupling reactions from polypropylene as a base material and palladium nanoparticles on silica (SilicaCat Pd 0 R815-100 by SiliCycle) as the catalytically active additive. The 3d printed catalyst showed similar activity to that of the pristine powdery commercial catalyst, but with improved practical recoverability and reduced leaching of palladium into solution. Recycling of the printed catalyst led to increase of the induction period of the reactions, attributed to the pseudo-homogeneous catalysis. The reaction is initiated by oxidative addition of aryl iodide to palladium nanoparticles, resulting in formation of soluble molecular species, which then act as the homogeneous catalyst. SLS 3d printing improves handling, overall practicality and recyclability of the catalyst without altering the chemical behaviour of the active component.

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Section: Resultsmentioning

confidence: 99%

3D Printed Palladium Catalyst for Suzuki‐Miyaura Cross‐coupling Reactions

et al. 2020

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“…This proves the great sensitivity of the system towards metal contaminations. Janiak and co‐workers recently showed that nanoparticles are easily deposited onto Teflon‐coated magnetic stirring bars 87. This could be a potential source for trace metal contaminations in many catalytic systems.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Aspects of Submol % Copper‐Catalyzed CN Cross‐Coupling

2014

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Carbonnitrogen bond formation can be catalyzed by copper in very low concentrations (≈100 ppm), with mechanistic features that are distinct from those in the high‐concentration regime. The reaction was studied by initial rate kinetics, competitive Hammett studies, and DFT calculations. The deprotonation of the model nucleophile, pyrrole, is limited by mass transfer with the heterogeneous base. The positive reaction order in dimethylethylenediamine was explained by this reagent working not only as a ligand to Cu, but also as a facilitator for mass transfer. The selectivity‐determining step in the competitive Hammett study is oxidative addition. Alternative mechanisms for this step, such as single‐electron transfer, atom transfer, or σ‐bond metathesis, can be excluded based on the observed Hammett behavior and DFT calculations.

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“…Rhodium nanoparticle-coated stirring bars are easily handled, separable and re-usable catalysts for the heterogeneous hydrogenation with quantitative conversion and very high turnover frequencies of up to 32 800 mol cyclohexene per mol Rh per h under organic-solvent-free conditions (Fig. 23) [212].…”

Section: Catalytic Applications Of Metal Nanoparticles Derived From Mmentioning

confidence: 99%

“…23 (color online). Rh-NP deposition on a Teflon-coated magnetic stirring bar from an IL dispersion and the use of a Rh-NP@stirring bar in hydrogenation catalysis [212].…”

Section: Catalytic Applications Of Metal Nanoparticles Derived From Mmentioning

confidence: 99%

Ionic Liquids for the Synthesis and Stabilization of Metal Nanoparticles

Janiak

2013

Zeitschrift Für Naturforschung B

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131

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The synthesis and stabilization of metal nanoparticles (M-NPs) from metals, metal salts, metal complexes and metal carbonyls in ionic liquids (ILs) is reviewed. The electrostatic and steric properties of ionic liquids allow for the stabilization of M-NPs without the need of additional stabilizers, surfactants or capping ligands. The synthesis of M-NPs in ILs can be carried out by chemical or electroreduction, thermolysis and photochemical methods including decomposition by microwave or sono-/ultrasound irradiation. Gas-phase syntheses can use sputtering, plasma/glow-discharge electrolysis and physical vapor deposition or electron beam and γ-irradiation. Metal carbonyl precursors M x (CO) y contain the metal atoms already in the zero-valent oxidation state needed for M-NPs so that no extra reducing agent is necessary. Microwave-induced thermal decomposition of precursors in ILs is a rapid and energy-saving access to M-NPs because of the significant absorption efficiency of ILs for microwave energy due to their ionic charge, high polarity and high dielectric constant. M-NP/IL dispersions can be applied in catalytic reactions, e. g., in C-C coupling or hydrogenation catalysis.

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Turning Teflon-coated magnetic stirring bars to catalyst systems with metal nanoparticle trace deposits – A caveat and a chance

Cited by 33 publications

References 50 publications

3D Printed Palladium Catalyst for Suzuki‐Miyaura Cross‐coupling Reactions

3D Printed Palladium Catalyst for Suzuki‐Miyaura Cross‐coupling Reactions

Mechanistic Aspects of Submol % Copper‐Catalyzed CN Cross‐Coupling

Ionic Liquids for the Synthesis and Stabilization of Metal Nanoparticles

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