scholarly journals A multifaceted role of a mobile bismuth promoter in alcohol amination over cobalt catalysts

2020 ◽  
Vol 22 (13) ◽  
pp. 4270-4278
Author(s):  
Feng Niu ◽  
Mounib Bahri ◽  
Ovidiu Ersen ◽  
Zhen Yan ◽  
Bright T. Kusema ◽  
...  
Keyword(s):  
Cobalt Catalysts ◽  
Coupling Reactions ◽  
Adsorbed Species ◽  
Amine Coupling

Bi as a mobile metal promoter on the surface of Co leads to multiple effects with enhancement of activity, selectivity and stability due to easy reduction, removal of strongly adsorbed species and suppression of amine coupling reactions.

scholarly journals Palladium-catalyzed Suzuki-Miyaura coupling of thioureas or thioamides

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shaoyu Mai ◽  
Wendong Li ◽  
Xue Li ◽  
Yingwei Zhao ◽  
Qiuling Song
Keyword(s):  
Silver Salt ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Mechanistic Studies ◽  
Aromatic Rings ◽  
Cross Coupling Reactions ◽  
Broad Array ◽  
Palladium Catalyzed

AbstractCross-coupling reactions involving metal carbene intermediates play an increasingly important role in C–C bond formation. Expanding the carbene precursors to a broader range of starting materials and more diverse products is an ongoing challenge in synthetic organic chemistry. Herein, we report a Suzuki-Miyaura coupling reaction of in situ-generated Pd–carbene complexes via desulfurization of thioureas or thioamides. This strategy enables the preparation of a broad array of substituted amidinium salts and unsymmetrical diaryl ketones. The reaction is readily scalable, compatible with bromo groups on aromatic rings, tolerant to moisture and air and has a broad substrate scope. Furthermore, a single crystal structure of Pd-diaminocarbene complex is obtained and proven to be the key intermediate in both catalytic and stoichiometric reactions. Preliminary mechanistic studies demonstrate the dual role of the silver salt as a desulfurating reagent assisting the elimination of sulfur and as oxidant facilitating the PdII/Pd0/PdII catalytic cycle.

scholarly journals Effects of the Interfacial Structure on the Methanol Oxidation on Platinum Single Crystal Electrodes

Surfaces ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 177-192 ◽  
Author(s):  
Mohammad Kamyabi ◽  
Ricardo Martínez-Hincapié ◽  
Juan Feliu ◽  
Enrique Herrero
Keyword(s):  
Single Crystal ◽  
Methanol Oxidation ◽  
Interfacial Structure ◽  
Direct Oxidation ◽  
Adsorbed Species ◽  
Oxidation Of Methanol ◽  
Methanol Solutions ◽  
Platinum Single Crystal ◽  
The Right

Methanol oxidation has been studied on low index platinum single crystal electrodes using methanol solutions with different pH (1–5) in the absence of specific adsorption. The goal is to determine the role of the interfacial structure in the reaction. The comparison between the voltammetric profiles obtained in the presence and absence of methanol indicates that methanol oxidation is only taking place when the surface is partially covered by adsorbed OH. Thus, on the Pt(111) electrode, the onset for the direct oxidation of methanol and the adsorption of OH coincide. In this case, the adsorbed OH species are not a mere spectator, because the obtained results for the reaction order for methanol and the proton concentrations indicate that OH adsorbed species are involved in the reaction mechanism. On the other hand, the dehydrogenation step to yield adsorbed CO on the Pt(100) surface coincides with the onset of OH adsorption on this electrode. It is proposed that adsorbed OH collaborates in the dehydrogenation step during methanol oxidation, facilitating either the adsorption of the methanol in the right configuration or the cleavage of the C—H bond.

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