A pH-switched Pickering emulsion catalytic system: high reaction efficiency and facile catalyst recycling

2015 ◽  
Vol 51 (34) ◽  
pp. 7333-7336 ◽  
Author(s):  
Jianping Huang ◽  
Hengquan Yang
Keyword(s):  
Catalytic System ◽  
Reaction Rate ◽  
Pickering Emulsion ◽  
Catalyst Recycling ◽  
Rate Enhancement ◽  
Reaction Efficiency ◽  
Nanoparticle Catalysts ◽  
High Reaction

A smart Pickering emulsion catalytic system is first constructed, which not only exhibits fivefold reaction rate enhancement effects in comparison to the conventional biphasic reactions but also can be demulsified by tuning pH at the end of reaction, allowing for in situ recycling nanoparticle catalysts.

Growing a hydrophilic nanoporous shell on a hydrophobic catalyst interface for aqueous reactions with high reaction efficiency and in situ catalyst recycling

2017 ◽  
Vol 5 (31) ◽  
pp. 16162-16170 ◽  
Author(s):  
Yajuan Hao ◽  
Xuan Jiao ◽  
Houbing Zou ◽  
Hengquan Yang ◽  
Jian Liu
Keyword(s):  
Catalytic Efficiency ◽  
Catalyst Recycling ◽  
Reaction Efficiency ◽  
High Reaction ◽  
Hydrophobic Catalyst ◽  
Aqueous Reactions

We developed a strategy to construct a catalyst with a hydrophobic catalytic interface covered by a hydrophilic, nanoporous shell, which displays high catalytic efficiency and recyclability in aqueous reactions.

A pH-responsive TiO2-based Pickering emulsion system for in situ catalyst recycling

2018 ◽  
Vol 29 (6) ◽  
pp. 778-782 ◽  
Author(s):  
Yajuan Hao ◽  
Yanfang Liu ◽  
Rui Yang ◽  
Xiaoming Zhang ◽  
Jian Liu ◽  
...  
Keyword(s):  
Pickering Emulsion ◽  
Emulsion System ◽  
Ph Responsive ◽  
Catalyst Recycling

Monitoring Polymer-Assisted Mechanochemical Cocrystallisation Through in Situ X-Ray Powder Diffraction

2020 ◽  
Author(s):  
Luzia S. Germann ◽  
Sebastian T. Emmerling ◽  
Manuel Wilke ◽  
Robert E. Dinnebier ◽  
Mariarosa Moneghini ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Powder Diffraction ◽  
Reaction Rate ◽  
Polymer Additives ◽  
Time Resolved ◽  
X Ray

Time-resolved mechanochemical cocrystallisation studies have so-far focused solely on neat and liquid-assisted grinding. Here, we report the monitoring of polymer-assisted grinding reactions using <i>in situ</i> X-ray powder diffraction, revealing that reaction rate is almost double compared to neat grinding and independent of the molecular weight and amount of used polymer additives.<br>

In-situ study and modeling of the decreasing reaction rate at the end of CoSi2 formation

2011 ◽  
Author(s):  
R. Delattre ◽  
R. Simola ◽  
C. Rivero ◽  
V. Serradeil ◽  
C. Perrin-Pellegrino ◽  
...  
Keyword(s):  
Reaction Rate ◽  
In Situ Study

Acceleration of Baylis-Hillman reaction using ionic liquid supported organocatalyst

2021 ◽  
Vol 08 ◽  
Author(s):  
Vivek Srivastava
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Reaction Rate ◽  
Reaction Medium ◽  
Catalyst Loading ◽  
Catalyst Recycling ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Highly Active ◽  
Low Catalyst Loading

Background: Baylis-Hillman reaction suffers from the requirement of cheap starting materials, easy reaction protocol, possibility to create the chiral center in the reaction product has increased the synthetic efficacy of this reaction, and high catalyst loading, low reaction rate, and poor yield. Objective: The extensive use of various functional or non-functional ionic liquids (ILs) with organocatalyst increases the reaction rate of various organic transformations as a reaction medium and as a support to anchor the catalysts. Methods: In this manuscript, we have demonstrated the synthesis of quinuclidine-supported trimethylamine-based functionalized ionic liquid as a catalyst for the Baylis-Hillman reaction. Results: We obtained the Baylis-Hillman adducts in good, isolated yield, low catalyst loading, short reaction time, broad substrate scope, accessible product, and catalyst recycling. N-((E,3S,4R)-5-benzylidene-tetrahydro-4-hydroxy-6-oxo-2H-pyran-3-yl) palmitamide was also successfully synthesized using CATALYST-3 promoted Baylis-Hillman reaction. Conclusion: We successfully isolated the 25 types of Baylis-Hillman adducts using three different quinuclidine-supported ammonium-based ionic liquids such as Et3AmQ][BF4] (CATALYST-1), [Et3AmQ][PF6] (CATALYST-2), and [TMAAmEQ][NTf2](CATALYST-3) as new and efficient catalysts. Tedious and highly active N-((E,3S,4R)-5-benzylidene-tetrahydro-4-hydroxy-6-oxo-2H-pyran-3-yl) palmitamide derivative was also synthesized using CATALYST-3 followed by Baylis-Hillman reaction. Generally, all the responses demonstrated higher activity and yielded high competition with various previously reported homogenous and heterogeneous Catalytic systems. Easy catalyst and product recovery followed by six catalysts recycling were the added advantages of the prosed catalytic system.

Benign by design. New catalysts for an environmentally conscious age

2001 ◽  
Vol 73 (7) ◽  
pp. 1087-1101 ◽  
Author(s):  
John Meurig Thomas ◽  
Robert Raja ◽  
Gopinathan Sankar ◽  
Robert G. Bell ◽  
Dewi W. Lewis
Keyword(s):  
Sustainable Development ◽  
Screening Methods ◽  
Reaction Conditions ◽  
Environmentally Conscious ◽  
Nanoparticle Catalysts ◽  
Fast Screening ◽  
Linear Alkanes ◽  
One Step ◽  
Acid Precursor

There is a pressing need for: (i) cleaner fuels (free of aromatics and of minimal sulfur content) or ones that convert chemical energy directly to electricity, silently and without production of noxious oxides and particulates; (ii) chemical, petrochemical, and pharmaceutical processes that may be conducted in a one-step, solvent-free manner, and that use air as the preferred oxidant; and (iii) industrial processes that minimize consumption of energy, production of waste or the use of corrosive, explosive, volatile and nonbiodegradable materials. All these needs and other desiderata, such as the in situ production and containment of aggressive and hazardous reagents, and the avoidance of use of ecologically harmful elements, may be achieved by designing the appropriate heterogeneous inorganic catalyst, which, ideally should be cheap, readily preparable, and fully characterizable, preferably under in situ reaction conditions. A range of nanoporous and nanoparticle catalysts, designed, synthesized, characterized, and tested by the authors and their colleagues, that meet most of the stringent demands of sustainable development and responsible (clean) technology is described. Specific examples that are highlighted include: (a) the production of adipic acid (precursor of polyamides and urethanes) without the use of concentrated nitric acid or the production of greenhouse gases such as nitrous oxide; (b) the production of caprolactam (precursor of nylon) without the use of oleum and hydroxylamine sulfate; and (c) the terminal oxyfunctionalization of linear alkanes in air. The topic of biocatalysis and sustainable development is also briefly discussed, and a cautionary note is sounded concerning fast screening methods for the discovery of new inorganic catalysts.

scholarly journals Ruthenium-Based Catalytic Systems Incorporating a Labile Cyclooctadiene Ligand with N-Heterocyclic Carbene Precursors for the Atom-Economic Alcohol Amidation Using Amines

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2413 ◽  
Author(s):  
Cheng Chen ◽  
Yang Miao ◽  
Kimmy De Winter ◽  
Hua-Jing Wang ◽  
Patrick Demeyere ◽  
...  
Keyword(s):  
Catalytic System ◽  
High Resolution Mass Spectrometry ◽  
Amide Bond ◽  
Catalyst Loading ◽  
Catalytic Systems ◽  
Amide Bond Formation ◽  
Highly Active ◽  
Metal Catalyzed ◽  
Ru Species

Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.

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