Martin H. G. Prechtl

University of Lisbon

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Leo E. Heim

University of Cologne

Jaı̈rton Dupont

Universidade Federal do Rio Grande do Sul

Jackson D. Scholten

Universidade Federal do Rio Grande do Sul

Jong‐Hoo Choi

University of Cologne

Jan Deska

University of Helsinki

Christian Gedig

University of Cologne

Hannelore Konnerth

National Taiwan University

M. Kessler

Universitätsklinikum Würzburg

Sebastian Sahler

University of Cologne

Christian Wolf

Australian National University

Cooperative Institutions

University of Cologne

Max Planck Society

Max Planck Institute for Plasma Physics

Universidade Federal do Rio Grande do Sul

Centre National de la Recherche Scientifique

Max Planck Innovation

Culham Science Centre

University of Lisbon

RWTH Aachen University

Royal Military Academy

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Schwingungsfähige Systeme

Springer eBooks (2014)

Martin H. G. Prechtl

10.1007/978-3-662-44796-3_5

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Back Cover: The Prospecting Shortcut to an Old Molecule: Formaldehyde Synthesis at Low Temperature in Solution (ChemSusChem 20/2016)

ChemSusChem (2016)

Leo E. Heim Hannelore Konnerth Martin H. G. Prechtl

The Back Cover picture shows a direct route to formaldehyde synthesis from syngas. Current megaton-scale formaldehyde production requires high-temperature gas-phase processes. In contrast, the depicted route, developed by Tanksale and co-workers, takes place in solution at low temperature and eliminates the need for energy- and cost-intensive steps used in the currently applied methods. More details can be found in the Highlight by Heim et al. on page 2905 in Issue 20, 2016 (DOI: 10.1002/cssc.201601043).

10.1002/cssc.201601416

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Challenging Thermodynamics: Hydrogenation of Benzene to 1,3‐Cyclohexadiene by Ru@Pt Nanoparticles

ChemCatChem (2016)

Andreas Weilhard Gabriel Abarca Janine R. Viscardi Martin H. G. Prechtl Jackson D. Scholten

Abstract Since the earliest reports on catalytic benzene hydrogenation, 1,3‐cyclohexadiene and cyclohexene have been proposed as key intermediates. However, the former has never been obtained with remarkable selectivity. Herein, we report the first partial hydrogenation of benzene towards 1,3‐cyclohexadiene under mild conditions in a catalytic biphasic system consisting of Ru@Pt nanoparticles (NPs) in ionic liquid (IL). The tandem reduction of [Ru(COD)(2‐methylallyl) 2 ] (COD=1,5‐cyclooctadiene) followed by decomposition of [Pt 2 (dba) 3 ] (dba=dibenzylideneacetone) in 1‐ n ‐butyl‐3‐methylimidazolium hexafluorophosphate (BMI ⋅ PF 6 ) IL under hydrogen affords core–shell Ru@Pt NPs of 2.9±0.2 nm. The hydrogenation of benzene (60 °C, 6 bar of H 2 ) dissolved in n ‐heptane by these bimetallic NPs in BMI ⋅ PF 6 affords 1,3‐cyclohexadiene with an unprecedented 21 % selectivity at 5 % benzene conversion. Conversely, almost no 1,3‐cyclohexadiene was observed when using monometallic Pt 0 or Ru 0 NPs under the same reaction conditions and benzene conversions. This study reveals that the selectivity is related to synergetic effects of the bimetallic composition of the catalyst material as well as to the performance under biphasic reaction conditions. It is proposed that colloidal metal catalysts in ILs and under multiphase conditions (“dynamic asymmetric mixtures”) can operate far from the thermodynamic equilibrium akin to chemically active membranes.

Bimetallic strip

Hexafluorophosphate

10.1002/cctc.201601196

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Citations (32)

The Prospecting Shortcut to an Old Molecule: Formaldehyde Synthesis at Low Temperature in Solution

ChemSusChem (2016)

Leo E. Heim Hannelore Konnerth Martin H. G. Prechtl

Over 30 megatons of formaldehyde are required per year and industrially produced through three high-temperature gas-phase processes: i) natural gas reforming to syngas, ii) methanol synthesis, and iii) partial oxidation to formaldehyde with limited selectivity. In vast contrast to these energy-intensive oxidative and dehydrogenative methods, a reductive "top-down" methodology using CO2 and CO as carbon source would be desirable and is not very well present in the literature for more than 100 years. The key to success is the reaction performance in liquid solution in water or methanol at low temperature.

Prospecting

10.1002/cssc.201601043

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Das Lehr-Zyklotron COLUMBUS

Essentials (2020)

Martin H. G. Prechtl Christian Wolf

10.1007/978-3-658-29710-7

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Can [M(H)₂(H₂)(PXP)] Pincer Complexes (M=Fe, Ru, Os; X=N, O, S) Serve as Catalyst Lead Structures for NH₃ Synthesis from N₂ and H₂?

Chemistry - A European Journal (2007)

Markus Hölscher Martin H. G. Prechtl Walter Leitner

The potential of pincer complexes [M(H)(2)(H(2))(PXP)] (M=Fe, Ru, Os; X=N, O, S) to coordinate, activate, and thus catalyze the reaction of N(2) with classical or nonclassical hydrogen centers present at the metal center, with the aim of forming NH(3) with H(2) as the only other reagent, was explored by means of DF (density functional) calculations. Screening of various complexes for their ability to perform initial hydrogen transfer to coordinated N(2) showed ruthenium pincer complexes to be more promising than the corresponding iron and osmium analogues. The ligand backbone influences the reaction dramatically: the presence of pyridine and thioether groups as backbones in the ligand result in inactive catalysts, whereas ether groups such as gamma-pyran and furan enable the reaction and result in unprecedented low activation barriers (23.7 and 22.1 kcal mol(-1), respectively), low enough to be interesting for practical application. Catalytic cycles were calculated for [Ru(H)(2)(H(2))(POP)] catalysts (POP=2,5-bis(dimethylphosphanylmethyl)furan and 2,6-bis(dimethylphosphanylmethyl)-gamma-pyran). The height of activation barriers for the furan system is somewhat more advantageous. Formation of inactive metal nitrides has not been observed. SCRF calculations were used to introduce solvent (toluene) effects. The Gibbs free energies of activation of the numerous single reaction steps do not change significantly when solvent is included. The reaction steps associated with the formation of the active catalyst from precursors [M(H)(2)(H(2))(PXP)] were also calculated. The otherwise inactive pyridine ligand system allows for the generation of the active catalyst species, whereas the ether ligand systems show activation barriers that could prohibit practical application. Consequently the generation of the active catalyst species needs to be addressed in further studies.

Thioether

Furan

10.1002/chem.200700289

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Schwingungsfähige Systeme

Springer eBooks (2021)

Martin H. G. Prechtl

10.1007/978-3-662-62107-3_5

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UN Sustainable Development Goal 7: clean energy – a holistic approach towards a sustainable future through hydrogen storage

RSC Sustainability (2023)

Martin H. G. Prechtl

UN Sustainability Development Goal 7, “Ensure access to affordable and clean energy”, is a key and a foundation for the majority of the other UNSDGs.

Clean energy

Foundation (evidence)

10.1039/d3su90036c

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Amide versus amine ligand paradigm in the direct amination of alcohols with Ru-PNP complexes

Dennis Pingen Jong‐Hoo Choi Henry Allen George Murray Prasad Ganji

Amide

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Palladium nanoparticle catalysts in ionic liquids: synthesis, characterisation and selective partial hydrogenation of alkynes to Z-alkenes

Journal of Materials Chemistry (2011)

Ramprakash Venkatesan Martin H. G. Prechtl Jackson D. Scholten R. P. Pezzi Giovanna Machado

The simple heating (120 °C) of Pd(OAc)2 in 1-butyronitrile-3-methylimidazolium-N-bis(trifluoromethane sulfonyl)imide ((BCN)MI·NTf2) under reduced pressure leads to the formation of stable and small-sized Pd(0)-NPs (diameter: 7.3 ± 2.2 nm). These metal nanoparticles were characterised by means of TEM, HRTEM and XPS analysis techniques. Moreover, the potential for partial hydrogenation of alkynes in multiphase systems was evaluated. The hydrogenation of internal alkynes at 25 °C and under 1 bar of hydrogen yields Z-alkenes (up to 98% selectivity). Application of higher hydrogen pressure (4 bar) in these reactions always led to the formation of alkanes without the detection of any alkenes. TOF values were attained up to 1282 h−1 with a good recyclability of the system which does not lose its activity for at least 4 runs.

Sulfonyl

Imide

Alkyne

Partial pressure

10.1039/c0jm03557b

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Citations (111)