ChemInform Abstract: Efficient and Selective Chemical Transformations under Flow Conditions: The Combination of Supported Catalysts and Supercritical Fluids

ChemInform ◽  
2012 ◽  
Vol 43 (17) ◽  
pp. no-no
Author(s):  
M. Isabel Burguete ◽  
Eduardo Garcia-Verdugo ◽  
Santiago V. Luis
Keyword(s):  
Supercritical Fluids ◽  
Supported Catalysts ◽  
Chemical Transformations ◽  
Flow Conditions ◽  
Selective Chemical

scholarly journals Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

2011 ◽  
Vol 7 ◽  
pp. 1347-1359 ◽  
Author(s):  
M Isabel Burguete ◽  
Eduardo García-Verdugo ◽  
Santiago V Luis
Keyword(s):  
Supercritical Fluids ◽  
Supported Catalysts ◽  
Chemical Transformations ◽  
Flow Conditions ◽  
Catalytic Systems ◽  
Enhanced Diffusion ◽  
Long Term Stability ◽  
Current Trends ◽  
Liquid Phases ◽  
Combined Use

This paper reviews the current trends in the combined use of supported catalytic systems, either on solid supports or in liquid phases and supercritical fluids (scFs), to develop selective and enantioselective chemical transformations under continuous and semi-continuous flow conditions. The results presented have been selected to highlight how the combined use of those two elements can contribute to: (i) Significant improvements in productivity as a result of the enhanced diffusion of substrates and reagents through the interfaces favored by the scF phase; (ii) the long term stability of the catalytic systems, which also contributes to the improvement of the final productivity, as the use of an appropriate immobilization strategy facilitates catalyst isolation and reuse; (iii) the development of highly efficient selective or, when applicable, enantioselective chemical transformations. Although the examples reported in the literature and considered in this review are currently confined to a limited number of fields, a significant development in this area can be envisaged for the near future due to the clear advantages of these systems over the conventional ones.

scholarly journals Hydrogen-Free Deoxygenation of Bio-Oil Model Compounds over Sulfur-Free Polymer Supported Catalysts

2020 ◽  
Vol 7 (1) ◽  
pp. 29-36
Author(s):  
Antonina A. Stepacheva ◽  
Mariia E. Markova ◽  
Yury V. Lugovoy ◽  
Kirill V. Chalov ◽  
Mikhail G. Sulman ◽  
...  
Keyword(s):  
Supercritical Fluids ◽  
Aromatic Compounds ◽  
Supported Catalysts ◽  
Major Product ◽  
Hypercrosslinked Polystyrene ◽  
Model Compounds ◽  
Transportation Fuel ◽  
Novel Approach ◽  
Bio Oil ◽  
Hydrogen Donors

AbstractHydrotreatment of bio-oil oxygen compounds allows the final product to be effectively used as a liquid transportation fuel from biomass. Deoxygenation is considered to be one of the most promising ways for bio-oil upgrading. In the current work, we describe a novel approach for the deoxygenation of bio-oil model compounds (anisole, guaiacol) using supercritical fluids as both the solvent and hydrogen-donors. We estimated the possibility of the use of complex solvent consisting of non-polar n-hexane with low critical points (Tc = 234.5 ºC, Pc = 3.02 MPa) and propanol-2 used as H-donor. The experiments were performed without catalysts and in the presence of noble and transition metals hydrothermally deposited on the polymeric matrix of hypercrosslinked polystyrene (HPS). The experiments showed that the presence of 20 vol. % of propanol-2 in n-hexane results in the highest (up to 99%) conversion of model compounds. When the process was carried out without a catalyst, phenols were found to be a major product yielding up to 95 %. The use of Pd- and Co-containing catalyst yielded 90 % of aromatic compounds (benzene and toluene) while in the presence of Ru and Ni cyclohexane and methylcyclohexane (up to 98 %) were the main products.

scholarly journals Enamine/Transition Metal Combined Catalysis: Catalytic Transformations Involving Organometallic Electrophilic Intermediates

2019 ◽  
Vol 377 (6) ◽  
Author(s):  
Samson Afewerki ◽  
Armando Córdova
Keyword(s):  
Transition Metal ◽  
Metal Complex ◽  
Carbonyl Compounds ◽  
Transition Metal Catalysis ◽  
Chemical Transformations ◽  
Considerable Effort ◽  
Metal Catalysis ◽  
First Report ◽  
Wide Range ◽  
Selective Chemical

AbstractThe concept of merging enamine activation catalysis with transition metal catalysis is an important strategy, which allows for selective chemical transformations not accessible without this combination. The amine catalyst activates the carbonyl compounds through the formation of a reactive nucleophilic enamine intermediate and, in parallel, the transition metal activates a wide range of functionalities such as allylic substrates through the formation of reactive electrophilic π-allyl-metal complex. Since the first report of this strategy in 2006, considerable effort has been devoted to the successful advancement of this technology. In this chapter, these findings are highlighted and discussed.

Stereochemistry of Dehydrogenation by D-Galactose Oxidase

1971 ◽  
Vol 49 (21) ◽  
pp. 3429-3437 ◽  
Author(s):  
A. Maradufu ◽  
G. M. Cree ◽  
A. S. Perlin
Keyword(s):  
Hydrogen Atom ◽  
Isotope Effect ◽  
Galactose Oxidase ◽  
Relative Impact ◽  
Chemical Transformations ◽  
Product Analysis ◽  
Deuterium Isotope Effect ◽  
Oxidation Rates ◽  
Selective Chemical ◽  
Sugar Derivatives

The stereochemistry of dehydrogenation of the primary carbinol group of D-galactose by D-galactose oxidase has been determined. Using D-galactose-6-d and methyl β-D-galactopyranoside-6-d, it has been established that the reaction involves removal of the pro-S 6-hydrogen atom. This conclusion is based on product analysis, and on the relative impact of the deuterium isotope effect on oxidation rates of substrates having different R:S deuteration patterns. The absolute configurations at C-6 of these substrates have been determined by selective chemical transformations to products of known configuration. The rotational conformation of the 6-carbinol group of D-galactose and its possible relationship to the specificity of the enzyme are discussed, as well as the stereochemistry of reductive deuteration of aldehydo sugar derivatives.

Biosynthetically-inspired oxidations of capillobenzopyranol

2017 ◽  
Vol 15 (22) ◽  
pp. 4811-4815 ◽  
Author(s):  
Henry P. Pepper ◽  
Hiu C. Lam ◽  
Jonathan H. George
Keyword(s):  
Marine Sponge ◽  
Chemical Transformations ◽  
Selective Chemical

The marine sponge meroterpenoid capillobenzopyranol has been converted into the co-isolated verrubenzospirolactone using simple and selective chemical transformations.

Recoverable Microparticle-Supported Metal Nanocatalysts

2019 ◽  
Author(s):  
Arthur Bonfá Fernandes ◽  
Mariia V. Pavliuk ◽  
Cristina Paun ◽  
Alexandrina C. Carvalho ◽  
Cassiana S. Nomura ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Metal Oxide Nanoparticles ◽  
Catalytic Performance ◽  
Chemical Transformations ◽  
Flow Conditions ◽  
Facile Synthesis ◽  
Mild Conditions ◽  
One Step ◽  
The One ◽  
Supported Metal

Metal nanoparticles have been widely exploited in catalysis, but their full impact on the environment and human health is still under debate. Here we describe the one-step fabrication of polymer microbead-supported metal and metal oxide nanoparticles and their application as recoverable nanocatalysts for reactions under batch and flow conditions. Au, Ag and Fe<sub>3</sub>O<sub>4</sub> nanoparticles were prepared directly at the surface of benzylamine-coated spherical polymer beads in water by using low energy microwave radiation. The morphology and size of the nanoparticles, and therefore their catalytic properties, were tuned by modifying the bead surface using betalamic acid, an antioxidant from plant origin. The catalytic performance and recovery of these environmentally friendly nanocatalysts was demonstrated towards model redox chemical transformations. We anticipate the results reported herein can provide important insights into the controlled and facile synthesis of microparticle supported nanocatalysts under mild conditions.

scholarly journals Development of efficient processes under flow conditions based on catalysts immobilized onto monolithic supported ionic liquid-like phases

2009 ◽  
Vol 81 (11) ◽  
pp. 1991-2000 ◽  
Author(s):  
M. Isabel Burguete ◽  
Eduardo García-Verdugo ◽  
Naima Karbass ◽  
Santiago V. Luis ◽  
Victor Sans ◽  
...  
Keyword(s):  
Supercritical Fluids ◽  
Immobilized Enzymes ◽  
Pd Nanoparticles ◽  
The Other ◽  
Morphological Properties ◽  
Flow Conditions ◽  
Catalytic Systems ◽  
Supported Ionic Liquid ◽  
Basic Catalysts ◽  
Catalytically Active

The introduction of imidazolium subunits into polystyrene-divinylbenzene (PS-DVB) polymers enables the preparation of a variety of catalytic systems. Those include the stabilization of catalytically active Pd nanoparticles (PdNPs), immobilized enzymes, and basic catalysts. The use of monolithic supports having the appropriate morphological properties is greatly advantageous for the development of efficient catalytic processes under flow conditions based on those systems. On the other hand, the combination of those supported catalytic systems and flow conditions can be further implemented, in terms of green chemistry, by the substitution of the use of traditional solvents by environmentally friendly conditions such as the use of supercritical fluids (SCFs).

scholarly journals Exploration of new reaction tools for late-stage functionalization of complex chemicals

2019 ◽  
Vol 97 (2) ◽  
pp. 67-85 ◽  
Author(s):  
Alejandra Dominguez-Huerta ◽  
Xi-Jie Dai ◽  
Feng Zhou ◽  
Pierre Querard ◽  
Zihang Qiu ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Late Stage ◽  
Chemical Transformations ◽  
Synthetic Route ◽  
Atom Economy ◽  
Complex Molecules ◽  
Mild Conditions ◽  
The Past ◽  
Renewable Feedstocks ◽  
Selective Chemical

Chemistry has always had as a target the conversion of molecules into valuable materials. Nevertheless, the aim of past synthesis has primarily focused on achieving a given transformation, regardless of the environmental impact of the synthetic route. Given the current global situation, the demand for sustainable alternatives has substantially increased. Our group focuses on developing selective chemical transformations that benefit from mild conditions, improved atom economy, and that can make use of renewable feedstocks as starting materials. This account summarizes our work over the past two decades specifically regarding the selective removal, conversion, and addition of functional groups that can, later on, be applied at a late stage for the modification of complex molecules.

Synthesis and Antimicrobial Activity of (Z)-2-(4-((5-((1-Benzylpiperidin-4-yl)methylene)- 2,4-dioxothiazolidin-3-yl)methyl)-1H-1,2,3-triazol-1-yl)-N-phenylacetamides

2021 ◽  
Vol 6 (4) ◽  
pp. 315-321
Author(s):  
Ashokbhai R. Rathod ◽  
Kapil Kumar Galachar ◽  
Chandan Kumar Pashavan ◽  
Sushil S. Korgaokar ◽  
Yogesh T. Naliapara
Keyword(s):  
Antimicrobial Activity ◽  
Click Chemistry ◽  
Analytical Techniques ◽  
Chemical Transformations ◽  
Biological Application ◽  
Selective Chemical

In current times, researchers adopted the click chemistry approach for the synthesis of various druglike molecules by using a few reliable, feasible, practical and selective chemical transformations via click formation. In present work, we focussed on the most triazole clubbed thiazolidine-2,4-dione derivatives as the most promising motifs for broad biological application. A total of fifteen (CF-4a-o) derivatives were synthesized and well characterized with various analytical techniques.

scholarly journals Origin and Control of Chemoselectivity in Cytochrome c-Catalyzed Carbene Transfer into Si–H and N–H bonds

2021 ◽  
Author(s):  
Marc Garcia-Borràs ◽  
S. B. Jennifer Kan ◽  
Russell D. Lewis ◽  
Allison Tang ◽  
Gonzalo Jiménez-Osés ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Bond Formation ◽  
Conformational Dynamics ◽  
Active Species ◽  
Chemical Transformations ◽  
Carbene Insertion ◽  
Biological World ◽  
Selective Chemical ◽  
And Control ◽  
Loop Conformation

<div><div><div><p>A cytochrome c heme protein was recently engineered to catalyze the formation of carbon–silicon bonds via carbene insertion into Si–H bonds, a reaction that was not previously known to be catalyzed by a protein. High chemoselectivity towards C–Si bond formation over competing C–N bond formation was achieved, although this trait was not screened for during directed evolution. Using computational and experimental tools, we now establish that activity and chemoselectivity are modulated by conformational dynamics of a protein loop that covers the substrate access to the iron-carbene active species. Mutagenesis of residues computationally predicted to control the loop conformation altered the protein’s chemoselectivity from preferred silylation to preferred amination of a substrate containing both N–H and Si–H functionalities. We demonstrate that information on protein structure and conformational dynamics, combined with knowledge of mechanism, leads to understanding of how non-natural and selective chemical transformations can be introduced into the biological world.</p></div></div></div>

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