Ultra-fast Cu-based A3-coupling catalysts: faceted Cu2O microcrystals as efficient catalyst-delivery systems in batch and flow conditions

Canadian Journal of Chemistry ◽

10.1139/cjc-2021-0197 ◽

2021 ◽

Author(s):

Huizhi Bao ◽

Alain Y. Li ◽

Vanessa Kairouz ◽

Audrey Moores

Keyword(s):

Flow Reactor ◽

Reaction Medium ◽

Loading Conditions ◽

Thermal Heating ◽

Flow Conditions ◽

Efficient Catalyst ◽

Cu Contamination ◽

Drug Synthesis ◽

A3 Coupling

Cu(I) catalysts were studied for the synthesis of a propargylamine via A3-coupling of aldehyde, amine, and alkyne, under solvent-free and low loading conditions, using batch microwave or flow thermal heating. We explore ultra-low loading conditions with Cu(I) salts as ultra fast and active catalysts featuring TOFs above 105 h-1. Well-defined octahedral and cubic Cu2O microcrystals were also successfully applied and compared to this reaction. Both types of microcrystals exhibited excellent catalytic activities within minutes, via in-situ generation of low dose of Cu(I) ions within the reaction medium, to achieve TON beyond 2000 and recycling up to 10 times in a flow reactor. The study of the catalytic system demonstrated that the activity was surface-structure dependent and allowed for the design of low Cu contamination A3-coupling systems, affording a product at the decigram scale, with Cu contamination below FDA recommendations for drug synthesis, without the need for a purification procedure.

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Bismuth Subnitrate-Catalyzed Markovnikov-Type Alkyne Hydrations under Batch and Continuous Flow Conditions

Molecules ◽

10.3390/molecules26102864 ◽

2021 ◽

Vol 26 (10) ◽

pp. 2864

Author(s):

Zsanett Szécsényi ◽

Ferenc Fülöp ◽

Sándor B. Ötvös

Keyword(s):

Continuous Flow ◽

Reaction Medium ◽

Batch Process ◽

Packed Bed ◽

Methyl Ketones ◽

Flow Conditions ◽

Efficient Catalyst ◽

Ready Availability ◽

Bismuth Subnitrate ◽

Terminal Acetylenes

Bismuth subnitrate is reported herein as a simple and efficient catalyst for the atom-economical synthesis of methyl ketones via Markovnikov-type alkyne hydration. Besides an effective batch process under reasonably mild conditions, a chemically intensified continuous flow protocol was also developed in a packed-bed system. The applicability of the methodologies was demonstrated through hydration of a diverse set of terminal acetylenes. By simply switching the reaction medium from methanol to methanol-d4, valuable trideuteromethyl ketones were also prepared. Due to the ready availability and nontoxicity of the heterogeneous catalyst, which eliminated the need for any special additives and/or harmful reagents, the presented processes display significant advances in terms of practicality and sustainability.

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Liquid Phase Furfural Oxidation under Uncontrolled pH in Batch and Flow Conditions: The Role of In Situ Formed Base

Catalysts ◽

10.3390/catal10010073 ◽

2020 ◽

Vol 10 (1) ◽

pp. 73 ◽

Cited By ~ 2

Author(s):

Alessandra Roselli ◽

Yuri Carvalho ◽

Franck Dumeignil ◽

Fabrizio Cavani ◽

Sébastien Paul ◽

...

Keyword(s):

Reaction Medium ◽

Pure Oxygen ◽

Continuous Stirred Tank Reactor ◽

Flow Conditions ◽

Furoic Acid ◽

Continuous Stirred Tank ◽

Supported Gold Nanoparticles ◽

Supported Gold

Selective oxidation of furfural to furoic acid was performed with pure oxygen in aqueous phase under mild conditions and uncontrolled pH using hydrotalcite-supported gold nanoparticles as catalyst. Hydrotalcites with different Mg: Al ratios were tested as support. The effects of reaction time, temperature and furfural/catalyst ratio were evaluated. The catalyst Au/HT 4:1 showed the highest activity and selectivity to the desired product, achieving a complete conversion of furfural to furoic acid after 2 h at 110 °C. Further, stability tests were carried out in a continuous stirred-tank reactor and a progressive deactivation of the catalyst due to the leaching of Mg2+ cations from the support inducing changes in the pH of the reaction medium was observed.

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In situ deformation characterization of density-graded foams in quasi-static and impact loading conditions

International Journal of Impact Engineering ◽

10.1016/j.ijimpeng.2021.103820 ◽

2021 ◽

Vol 150 ◽

pp. 103820

Author(s):

Behrad Koohbor ◽

Suraj Ravindran ◽

Addis Kidane

Keyword(s):

Impact Loading ◽

Loading Conditions ◽

In Situ Deformation

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Immobilization of an Iridium(I)-NHC-Phosphine Catalyst for Hydrogenation Reactions under Batch and Flow Conditions

Catalysts ◽

10.3390/catal11060656 ◽

2021 ◽

Vol 11 (6) ◽

pp. 656

Author(s):

Henrietta Kovács ◽

Krisztina Orosz ◽

Gábor Papp ◽

Ferenc Joó ◽

Henrietta Horváth

Keyword(s):

Catalytic Activity ◽

Ion Exchange ◽

Heterogeneous Catalyst ◽

Aqueous Phase ◽

Levulinic Acid ◽

Flow Reactor ◽

High Catalytic Activity ◽

Flow Conditions ◽

Hydrogenation Reactions ◽

Excellent Selectivity

Na2[Ir(cod)(emim)(mtppts)] (1) with high catalytic activity in various organic- and aqueous-phase hydrogenation reactions was immobilized on several types of commercially available ion-exchange supports. The resulting heterogeneous catalyst was investigated in batch reactions and in an H-Cube flow reactor in the hydrogenation of phenylacetylene, diphenylacetylene, 1-hexyne, and benzylideneacetone. Under proper conditions, the catalyst was highly selective in the hydrogenation of alkynes to alkenes, and demonstrated excellent selectivity in C=C over C=O hydrogenation; furthermore, it displayed remarkable stability. Activity of 1 in hydrogenation of levulinic acid to γ-valerolactone was also assessed.

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Adherence of platelets to in situ albumin-binding surfaces under flow conditions: role of surface-adsorbed albumin

Biomedical Materials ◽

10.1088/1748-6041/7/4/045007 ◽

2012 ◽

Vol 7 (4) ◽

pp. 045007 ◽

Cited By ~ 2

Author(s):

Sanjukta Guha Thakurta ◽

Robert Miller ◽

Anuradha Subramanian

Keyword(s):

Albumin Binding ◽

Flow Conditions

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Discrete element analysis of the punching behaviour of a secured drapery system: from laboratory characterization to idealized in situ conditions

Acta Geotechnica ◽

10.1007/s11440-020-01119-z ◽

2021 ◽

Author(s):

Antonio Pol ◽

Fabio Gabrieli ◽

Lorenzo Brezzi

Keyword(s):

Mechanical Response ◽

Steel Wire ◽

Discrete Element ◽

Wire Mesh ◽

Steel Plates ◽

Loading Conditions ◽

Element Analysis ◽

In Situ Conditions ◽

Wire Meshes

AbstractIn this work, the mechanical response of a steel wire mesh panel against a punching load is studied starting from laboratory test conditions and extending the results to field applications. Wire meshes anchored with bolts and steel plates are extensively used in rockfall protection and slope stabilization. Their performances are evaluated through laboratory tests, but the mechanical constraints, the geometry and the loading conditions may strongly differ from the in situ conditions leading to incorrect estimations of the strength of the mesh. In this work, the discrete element method is used to simulate a wire mesh. After validation of the numerical mesh model against experimental data, the punching behaviour of an anchored mesh panel is investigated in order to obtain a more realistic characterization of the mesh mechanical response in field conditions. The dimension of the punching element, its position, the anchor plate size and the anchor spacing are varied, providing analytical relationships able to predict the panel response in different loading conditions. Furthermore, the mesh panel aspect ratio is analysed showing the existence of an optimal value. The results of this study can provide useful information to practitioners for designing secured drapery systems, as well as for the assessment of their safety conditions.

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Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

Molecules ◽

10.3390/molecules26133844 ◽

2021 ◽

Vol 26 (13) ◽

pp. 3844

Author(s):

Lijuan Li ◽

Bingdong Li ◽

Liwei Feng ◽

Xiaoqiu Zhang ◽

Yuqian Zhang ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Reaction System ◽

Reaction Medium ◽

Pure Tio2 ◽

H2o2 Production ◽

Tio2 Photocatalyst ◽

H2o2 Decomposition ◽

Spin Resonance ◽

Photocatalytic Synthesis

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

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