Efficient epoxidation of propene using molecular catalysts

2014 ◽  
Vol 4 (11) ◽  
pp. 3845-3849 ◽  
Author(s):  
Iulius I. E. Markovits ◽  
Michael H. Anthofer ◽  
Helene Kolding ◽  
Mirza Cokoja ◽  
Alexander Pöthig ◽  
...  
Keyword(s):  
Mild Conditions ◽  
Propene Oxide ◽  
Molybdenum Catalysts ◽  
Molecular Catalysts

The epoxidation of propene to propene oxide at mild conditions using molecular rhenium and molybdenum catalysts is presented.

CO2-based hydrogen storage – hydrogen liberation from methanol/water mixtures and from anhydrous methanol

2018 ◽  
Vol 3 (9) ◽  
Author(s):  
Monica Trincado ◽  
Matthias Vogt
Keyword(s):  
Hydrogen Storage ◽  
Heterogeneous Catalysts ◽  
Biological Systems ◽  
Anhydrous Methanol ◽  
Mild Conditions ◽  
Production Of Hydrogen ◽  
Hydrogen Liberation ◽  
Dehydrogenation Reactions ◽  
Molecular Catalysts ◽  
New Strategies

Abstract New strategies for the reforming of methanol under mild conditions on the basis of heterogeneous and molecular catalysts have raised the hopes and expectations on this fuel. This contribution will focus on the progress achieved in the production of hydrogen from aqueous and anhydrous methanol with molecular and heterogeneous catalysts. The report entails thermal approaches, as well as light-triggered dehydrogenation reactions. A comparison of the efficiency and mechanistic aspects will be made and principles of catalytic pathways operating in biological systems will be also addressed.

Aerobic oxidation with bifunctional molecular catalysts

2010 ◽  
Vol 82 (7) ◽  
pp. 1471-1483 ◽  
Author(s):  
Takao Ikariya ◽  
Shigeki Kuwata ◽  
Yoshihito Kayaki
Keyword(s):  
Kinetic Resolution ◽  
High Selectivity ◽  
Aerobic Oxidation ◽  
Secondary Alcohol ◽  
Primary Alcohols ◽  
Mild Conditions ◽  
Benzylic Amines ◽  
Oxidative Kinetic Resolution ◽  
Molecular Catalysts ◽  
Half Sandwich

A new series of half-sandwich group 8 and 9 metal complexes bearing a metal/NH bifunctional moiety were synthesized from benzylic amines. The isolable Ir amide complexes serve as effective catalysts for aerobic oxidative transformation of secondary and primary alcohols into the corresponding ketones and esters under mild conditions. The aerobic oxidative kinetic resolution of racemic secondary alcohols with chiral bifunctional Ir catalysts was found to proceed smoothly under mild conditions with high selectivity. A novel imido-bridged dirhodium complex, which may be regarded as a dinuclear variant of the bifunctional mononuclear amide complexes, also proved to promote aerobic oxidation of a secondary alcohol and H2.

Comprehensive insights into synthetic nitrogen fixation assisted by molecular catalysts under ambient or mild conditions

2021 ◽  
Author(s):  
Yoshiaki Tanabe ◽  
Yoshiaki Nishibayashi
Keyword(s):  
Nitrogen Fixation ◽  
Transition Metal ◽  
Biological Nitrogen Fixation ◽  
Molecular Complexes ◽  
Alternative Methods ◽  
Ambient Conditions ◽  
Mild Conditions ◽  
Molecular Catalysts ◽  
Biological Nitrogen ◽  
Harsh Conditions

N2 is fixed as NH3 industrially by the Haber–Bosch process under harsh conditions, whereas biological nitrogen fixation is achieved under ambient conditions, which has prompted development of alternative methods to fix N2 catalyzed by transition metal molecular complexes.

Efficient hydrodeoxygenation of sulfoxides into sulfides under mild conditions using heterogeneous cobalt–molybdenum catalysts

2020 ◽  
Vol 22 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Kaiyue Yao ◽  
Ziliang Yuan ◽  
Shiwei Jin ◽  
Quan Chi ◽  
Bing Liu ◽  
...  
Keyword(s):  
Noble Metal ◽  
Bimetallic Catalysts ◽  
Metal Catalysts ◽  
Nitrogen Doped ◽  
Noble Metal Catalysts ◽  
Mild Conditions ◽  
First Case ◽  
Molybdenum Catalysts ◽  
Nitrogen Doped Carbon

Nitrogen–doped carbon-supported cobalt–molybdenum bimetallic catalysts are active for the hydrodeoxygenation of sulfoxides to sulfides under mild conditions, which is the first case of use of heterogeneous non-noble metal catalysts for the reaction.

The Diorgano Dichalcogenides Addition to Benzyne under Mild Conditions

2007 ◽  
Author(s):  
Fabiano Toledo ◽  
Henrique Marques ◽  
João Comasseto ◽  
Cristiano Raminelli
Keyword(s):  
Mild Conditions

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

An NADH-Inspired Redox Mediator Strategy to Promote Second-Sphere Electron and Proton Transfer for Cooperative Electrochemical CO2 Reduction Catalyzed by Iron Porphyrin

2020 ◽  
Author(s):  
Peter T. Smith ◽  
Sophia Weng ◽  
Christopher Chang
Keyword(s):  
Proton Transfer ◽  
Co2 Reduction ◽  
Iron Porphyrin ◽  
Redox Mediators ◽  
Reservoir Properties ◽  
Proton Reduction ◽  
Electrochemical Co2 Reduction ◽  
Starting Point ◽  
Rate Improvement ◽  
Molecular Catalysts

We present a bioinspired strategy for enhancing electrochemical carbon dioxide reduction catalysis by cooperative use of base-metal molecular catalysts with intermolecular second-sphere redox mediators that facilitate both electron and proton transfer. Functional synthetic mimics of the biological redox cofactor NADH, which are electrochemically stable and are capable of mediating both electron and proton transfer, can enhance the activity of an iron porphyrin catalyst for electrochemical reduction of CO<sub>2</sub> to CO, achieving a 13-fold rate improvement without altering the intrinsic high selectivity of this catalyst platform for CO<sub>2</sub> versus proton reduction. Evaluation of a systematic series of NADH analogs and redox-inactive control additives with varying proton and electron reservoir properties reveals that both electron and proton transfer contribute to the observed catalytic enhancements. This work establishes that second-sphere dual control of electron and proton inventories is a viable design strategy for developing more effective electrocatalysts for CO<sub>2</sub> reduction, providing a starting point for broader applications of this approach to other multi-electron, multi-proton transformations.

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

Double Ring-Closing Approach for the Synthesis of 2,3,6,7-Substituted Anthracene Derivatives

2020 ◽  
Author(s):  
Birgit Meindl ◽  
Katharina Pfennigbauer ◽  
Berthold Stöger ◽  
Martin Heeney ◽  
Florian Glöcklhofer
Keyword(s):  
Wittig Reaction ◽  
Condensation Reaction ◽  
Synthetic Methods ◽  
Anthracene Derivative ◽  
Double Ring ◽  
Mild Conditions ◽  
Wide Range ◽  
Anthracene Derivatives

Anthracene derivatives have been used for a wide range of applications and many different synthetic methods for their preparation have been developed. However, despite continued synthetic efforts, introducing substituents in some positions has remained difficult. Here we present a method for the synthesis of 2,3,6,7-substituted anthracene derivatives, one of the most challenging anthracene substitution patterns to obtain. The method is exemplified by the preparation of 2,3,6,7-anthracenetetracarbonitrile and employs a newly developed, stable protected 1,2,4,5-benzenetetracarbaldehyde as the precursor. The precursor can be obtained in two scalable synthetic steps from 2,5-dibromoterephthalaldehyde and is converted into the anthracene derivative by a double intermolecular Wittig reaction under very mild conditions followed by a deprotection and intramolecular double ring-closing condensation reaction. Further modification of the precursor is expected to enable the introduction of additional substituents in other positions and may even enable the synthesis of fully substituted anthracene derivatives by the presented approach.<br>

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