Roland G. Heidenreich

Technical University of Munich

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Klaus Köhler

Technical University of Munich

Jürgen G.E. Krauter

Klinikum Hanau

Jörg Pietsch

TU Dresden

Sandra S. Pröckl

Technical University of Munich

Juergen G. E. Krauter

University of Rostock

P. Albers

Heidelberg University

Sohail Ahmed Soomro

University of Oulu

D.K. Ross

University of Salford

Saeeda S. Soomro

RWTH Aachen University

K. Auwers

Philipps University of Marburg

Cooperative Institutions

Technical University of Munich

Klinikum Hanau

Rutherford Appleton Laboratory

Centre National de la Recherche Scientifique

Heidelberg University

Itasca Consultants (Germany)

University of Salford

Research Complex at Harwell

Philipps University of Marburg

Institut de Recherches sur la Catalyse et l'Environnement de Lyon

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Highly Active Palladium/Activated Carbon Catalysts for Heck Reactions: Correlation of Activity, Catalyst Properties, and Pd Leaching

Chemistry - A European Journal (2002)

Klaus Köhler Roland G. Heidenreich Jürgen G.E. Krauter Jörg Pietsch

A variety of palladium on activated carbon catalysts differing in Pd dispersion, Pd distribution, Pd oxidation state, and water content were tested in Heck reactions of aryl bromides with olefins. The optimization of the catalyst (structure-activity relationship) and reaction conditions (temperature, solvent, base, and Pd loading) allowed Pd/C catalysts with very high activity for Heck reactions of unactivated bromobenzene (turnover number (TON) approximately 18000, turnover frequency (TOF) up to 9000, Pd concentrations down to 0.005 mol %) to be developed. High Pd dispersion, low degree of reduction, sufficient content of water, and uniform Pd impregnation are criteria for the most active system. The catalysts combine high activity and selectivity under ambient conditions (air and moisture), easy separation (filtration), and quantitative recovery of palladium. Determination of Pd in solution after and during the reaction, and catalyst characterization before and after the reaction (transmission electron microscopy (TEM), X-ray diffraction (XRD)), indicate dissolution/reprecipitation of palladium during the reaction. The Pd concentration in solution is highest at the beginning of the reaction and is a minimum (< 1 ppm) at the end of the reaction. Palladium leaching correlates significantly with the reaction parameters.

Heck Reaction

Active carbon

10.1002/1521-3765(20020201)8:3<622::aid-chem622>3.0.co;2-0

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Citations (372)

Über Tetrahydro‐indazole

Justus Liebig s Annalen der Chemie (1924)

K. Auwers Wilhelm Buschmann Roland G. Heidenreich

Indazole

10.1002/jlac.19244350110

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Citations (16)

Pd/C as a Highly Active Catalyst for Heck, Suzuki and Sonogashira Reactions

Synlett (2002)

Roland G. Heidenreich Klaus Köhler Jürgen G.E. Krauter Jörg Pietsch

A specially optimized air-stable Pd on activated carbon catalyst is demonstrated to be a highly active (TON up to 36,000), selective and convenient heterogeneous catalyst for CC couplings of aryl halides in Heck, Suzuki, and Sonogashira reactions. The Pd/C catalyst developed allows extremely low Pd concentrations (down to 0.0025 mol% for Heck coupling, 0.005 mol% for Suzuki coupling) and high conversions of aryl bromides within a few hours. Easy and complete Pd separation and recovery is possible.

Sonogashira coupling

Heck Reaction

Suzuki reaction

Palladium catalyst

10.1055/s-2002-32589

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Citations (194)

Supported Palladium Catalysts for Suzuki Reactions: Structure‐Property Relationships, Optimized Reaction Protocol and Control of Palladium Leaching

Advanced Synthesis & Catalysis (2008)

Klaus Köhler Roland G. Heidenreich Saeeda S. Soomro Sandra S. Pröckl

Abstract Palladium on metal oxides and on activated carbon with particular properties (high palladium dispersion, low degree of reduction, water content) are shown to be highly active (tunrover number, TON=20,000; turnover frequency, TOF=16,600), selective and robust catalysts for Suzuki cross‐couplings of aryl bromides and activated aryl chlorides. Catalysts and reaction protocol offer combined advantages of high catalytic efficiency under ambient conditions (air and moisture), easy separation and reuse and quantitative recovery of palladium. The palladium concentration in solution during the reaction correlates clearly with the progress of the reaction and indicates that dissolved molecular palladium is in fact the catalytically active species. Dissolved palladium is redeposited onto the support at the end of the reaction. Additional minimization of the palladium content in solution (down to 0.1 ppm) could be achieved by simple procedures which meet the requirements of pharmaceutical industry.

Coupling reaction

10.1002/adsc.200800575

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Citations (151)

Control of Pd leaching in Heck reactions of bromoarenes catalyzed by Pd supported on activated carbon

Journal of Molecular Catalysis A Chemical (2002)

Roland G. Heidenreich Jürgen G.E. Krauter Jörg Pietsch Klaus Köhler

Heck Reaction

Inert gas

Inert

10.1016/s1381-1169(01)00499-x

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Citations (168)

Controlled Distribution of Solid Catalysts into Two Immiscible Liquid Phases – Synthesis and Catalytic Applications

Catalysis Letters (2004)

Markus Gruber Michael Wagner Roland G. Heidenreich Jürgen G.E. Krauter Necdet Coşkun

Decantation

Organometallic Chemistry

Liquid phase

10.1023/b:catl.0000020542.87789.f5

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Citations (15)

Supported Palladium Catalysts

Chemical industries (2002)

Jörg Pietsch Juergen G. E. Krauter Roland G. Heidenreich

10.1201/9780203911013.ch28

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Citations (0)

Pd/C as a Highly Active Catalyst for Heck, Suzuki and Sonogashira Reactions.

ChemInform (2002)

Roland G. Heidenreich Klaus Koehler Juergen G. E. Krauter Joerg Pietsch

Abstract For Abstract see ChemInform Abstract in Full Text.

Sonogashira coupling

Heck Reaction

10.1002/chin.200244112

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Citations (12)

Identification of Surface States on Finely Divided Supported Palladium Catalysts by Means of Inelastic Incoherent Neutron Scattering

Langmuir (2004)

P. Albers Jürgen G.E. Krauter D.K. Ross Roland G. Heidenreich Klaus Köhler

The purpose of the present investigation was to utilize the inelastic incoherent neutron scattering (INS) technique to reveal changes at the surface of technical catalysts under the influence of hydrogen in gas/solid interactions and during chemical reactions in a liquid-phase process. The formation and the properties of supported palladium hydride and changes of the hydrogen-related surface chemistry of the corresponding activated carbon supports in 20% Pd/C catalysts after short-term and long-term hydrogen cycling at different hydrogen pressures and temperatures were studied. The spectra indicate that hydrogenation of the activated carbon support by hydrogen spillover occurs to, partly, give a material that strongly resembles a-C:H (amorphous hydrogenated carbon). Indications for different relaxation phenomena and long-range phase coherence inside of supported particles of palladium hydride compared to hydrogenated palladium black were obtained. A 5% Pd/C catalyst after use in C−C coupling reactions, the Heck reaction of bromobenzene and styrene to stilbenes, was also studied after subsequent solvent extraction. Evidence for a preferential adsorption and accumulation of cis-stilbene at the catalyst surface was obtained. INS allows identification of a certain isomer from a complex reaction mixture preferentially adsorbed at the surface of a finely divided industrial heterogeneous catalyst.

Hydrogen spillover

10.1021/la040054c

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Citations (25)

Pd on Metal Oxides and Activated Carbon for Suzuki-Miyaura Coupling

Synfacts (2009)

Klaus Köhler Roland G. Heidenreich Sohail Ahmed Soomro Sandra S. Pröckl

Supported palladium catalysts [Pd/C, Pd/Al2O3, Pd/TiO2, Pd/CeO2, Pd/zeolite (NaY)] led to high activity, short reaction times, and 100% selectivity in the Suzuki-Miyaura couplings. The Suzuki-Miyaura coupling of aryl bromides (R = CN, H, OH, OMe: 5 mmol) with phenylboronic acid (5.5 mmol) in the presence of commercially available 5% Pd/C (Evonik-Degussa AG: 0.005 mol%) and sodium carbonate (6 mmol) gave the corresponding coupling products in 100% GC yield (1.5-2 h, 120 ˚C). Palladium supported on Al2O3 and TiO2 showed similar activity as Pd/C (2 h, Pd/Al2O3 = TON: 19200, selectivity: 100%; Pd/TiO2 = TON: 19400, selectivity: 100%) in the Suzuki-Miyaura coupling of 4-bromoanisole with phenylboronic acid. Pd/CeO2 and Pd/zeolite (NaY) required longer reaction times (4 h, TON: 16400, TOF: 4100).

Phenylboronic acid

Suzuki reaction

Coupling reaction

Sodium carbonate

10.1055/s-0028-1087735

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Citations (1)