scholarly journals One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

2013 ◽  
Vol 9 ◽  
pp. 1957-1968 ◽  
Author(s):  
Mark C Bagley ◽  
Vincenzo Fusillo ◽  
Robert L Jenkins ◽  
M Caterina Lubinu ◽  
Christopher Mason
Keyword(s):  
Michael Addition ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Acid Catalyst ◽  
Single Step ◽  
Continuous Processing ◽  
Microwave Reactor ◽  
One Step ◽  
Very High ◽  
Yielding Process

The Bohlmann–Rahtz pyridine synthesis and the Hantzsch dihydropyridine synthesis can be carried out in a microwave flow reactor or using a conductive heating flow platform for the continuous processing of material. In the Bohlmann–Rahtz reaction, the use of a Brønsted acid catalyst allows Michael addition and cyclodehydration to be carried out in a single step without isolation of intermediates to give the corresponding trisubstituted pyridine as a single regioisomer in good yield. Furthermore, 3-substituted propargyl aldehydes undergo Hantzsch dihydropyridine synthesis in preference to Bohlmann–Rahtz reaction in a very high yielding process that is readily transferred to continuous flow processing.

scholarly journals Sonochemical preparation of alumina-spheres loaded with Pd nanoparticles for 2-butyne-1,4-diol semi-hydrogenation in a continuous flow microwave reactor

RSC Advances ◽  
2018 ◽  
Vol 8 (13) ◽  
pp. 7029-7039 ◽  
Author(s):  
Emanuela Calcio Gaudino ◽  
Maela Manzoli ◽  
Diego Carnaroglio ◽  
Zhilin Wu ◽  
Giorgio Grillo ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Pd Nanoparticles ◽  
Microwave Assisted ◽  
Continuous Flow Reactor ◽  
Microwave Reactor

A novel protocol for microwave-assisted alkyne semi-hydrogenation under heterogeneous catalysis in a continuous flow reactor is reported herein.

scholarly journals Continuous-Flow Synthesis of Thermochromic M-Phase VO2 Particles via Rapid One-Step Hydrothermal Reaction: Effect of Mixers

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Xiaojie Yan ◽  
William Trevillyan ◽  
Ioannina Castano ◽  
Yugang Sun ◽  
Ralph Muehleisen ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Hydrothermal Reaction ◽  
Xrd Analysis ◽  
Single Step ◽  
Hot Water ◽  
Scanning Calorimetry ◽  
Smart Windows ◽  
M Phase ◽  
One Step ◽  
Resident Time

VO2 particles are promising materials for thermochromic smart windows that reduce building energy loss. Continuous-flow hydrothermal processes showcase advantages for synthesizing VO2 particles compared with traditional batch reaction systems. Mixers play a crucial role in particle fabrication in continuous-flow systems. In this study, a Center T-Mixer and a Collision Cross-Mixer are developed and implemented in a hot water fluidized suspension reaction (HWFSR) system. The influence of the resident time on the particle phase and size was evaluated, and properties of particles derived from systems equipped with differing mixers were compared. The resulting particles were characterized using techniques of X-ray powder diffraction (XRD) analysis, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). When compared with the Center T-Mixer, results indicate that the Collision Cross-Mixer has better control regarding the morphology and size distribution of resulting particles while improving the transition temperatures of the as-synthesized materials. HWFSR systems containing novel mixer designs are capable of producing pure M-phase VO2 particles in a single step contrary to the current reactor design that use a second postheat treatment step, and they are capable of synthesizing many other nanoparticle species, especially those requiring high temperature and pressure reaction conditions.

Synthesis of Nano-sized Yttrium-Aluminum Garnet in a Continuous-Flow Reactor in Supercritical Fluids

2008 ◽  
Vol 63 (6) ◽  
pp. 756-764 ◽  
Author(s):  
Tadeusz Chudoba ◽  
Edward Lester ◽  
Witold Łojkowski ◽  
Martin Poliakoff ◽  
Jun Li ◽  
...  
Keyword(s):  
Supercritical Fluids ◽  
Continuous Flow ◽  
Yttrium Aluminum Garnet ◽  
Flow Reactor ◽  
Step Process ◽  
Continuous Flow Reactor ◽  
Yttrium Aluminum ◽  
One Step ◽  
Favorable Conditions ◽  
Helium Pycnometry

The conditions for obtaining pure yttrium-aluminum garnet (YAG) in a one-step process starting from components soluble in supercritical (SCR) liquids in a flow reactor have been studied. The powders were characterized using XRD, BET, SEM and helium pycnometry. Favorable conditions for YAG production were achieved using acetates (and acetylacetonates) in aqueous-alcoholic solutions as starting materials. Aqueous and alcoholic solutions of nitrates and aqueous solutions of acetates were found not appropriate as precursors for YAG production. The powders obtained had the shape of nano-sized cubes with diameters in the range 80 - 120 nm. After annealing at 600 °C the powders have comparable density as those made via a conventional precipitation-calcination route but differ from the calcinated products form soft agglomerates.

An entirely solvent-free photooxygenation of olefins under continuous flow conditions

2020 ◽  
Vol 22 (8) ◽  
pp. 2359-2364 ◽  
Author(s):  
Patrick Bayer ◽  
Axel Jacobi von Wangelin
Keyword(s):  
Singlet Oxygen ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Space Time ◽  
Solvent Free ◽  
Flow Conditions ◽  
High Substrate ◽  
Solvent Free Conditions ◽  
High Space ◽  
Very High

Photooxygenations of alkenes with singlet oxygen have been performed under solvent-free conditions in a flow reactor under VIS irradiation. The reaction operates at very high substrate/sensitizer ratios and enables high space–time yields.

Droplet Factories: Synthesis and Assembly of Silver and Palladium Nanoparticles at the Liquid-Liquid Interface

2019 ◽  
Author(s):  
Suchanuch Sachdev ◽  
Rhushabh Maugi ◽  
Sam Davis ◽  
Scott Doak ◽  
Zhaoxia Zhou ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Reaction Rate ◽  
Tertiary Structure ◽  
Flow Reactor ◽  
Pd Nanoparticles ◽  
Subsequent Removal ◽  
Immiscible Liquids ◽  
Flow Reactors ◽  
Droplet Flow ◽  
One Step

<div>The interface between two immiscible liquids represent an ideal substrate for the assembly of nanomaterials. The defect free surface provides a reproducible support for creating densely packed ordered materials. Here a droplet flow reactor is presented for the synthesis and/ or assembly of nanomaterials at the interface of the emulsion. Each droplet acts as microreactor for a reaction between decamethylferrocene (DmFc) within the hexane and metal salts (Ag+/ Pd2+) in the aqueous phase. The hypothesis was that a spontaneous, interfacial reaction would lead to the assembly of nanomaterials creating a Pickering emulsion. The subsequent removal of the solvents showed how the Ag nanoparticles were trapped at the interface and retain the shape of the droplet, however the Pd nanoparticles were dispersed with no tertiary structure. To further exploit this, a one-step process where the particles are synthesised and then assembled into core-shell materials was proposed. The same reactions were performed in the presence of oleic acid stabilise Iron oxide nanoparticles dispersed within the hexane. It was shown that by changing the reaction rate and ratio between palladium and iron oxide a continuous coating of palladium onto iron oxide microspheres can be created. The same reaction with silver, was unsuccessful and resulted in the silver particles being shed into solution, or incorporated within the iron oxide micro particle. These insights offer a new method and chemistry within flow reactors for the creation of palladium and silver nanoparticles. We use the technique to create metal coated iron oxide nanomaterials but the methodology could be easily transferred to the assembly of other materials.</div><div><br></div>

Renewable Energy from Agricultural Waste

2018 ◽  
Vol 69 (6) ◽  
pp. 1363-1366 ◽  
Author(s):  
Stefania Daniela Bran ◽  
Petre Chipurici ◽  
Mariana Bran ◽  
Alexandru Vlaicu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gas Chromatography ◽  
Continuous Flow ◽  
Laboratory Experiments ◽  
Fermentation Process ◽  
Flow Reactor ◽  
Agricultural Waste ◽  
Continuous Flow Reactor ◽  
Natural Support ◽  
Co2 Flow

This paper has aimed at evaluating the concentration of bioethanol obtained using sunflower stem as natural support, molasses as carbon source and Saccharomyces cerevisiae yeast in a continuous flow reactor. The natural support was tested to investigate the immobilization/growth of S. cerevisiae yeast. The concentration of bioethanol produced by fermentation was analyzed by gas chromatography using two methods: aqueous solutions and extraction in organic phase. The CO2 flow obtained during the fermentation process was considered to estimate when the yeast was deactivated. The laboratory experiments have highlighted that the use of plant-based wastes to bioconversion in ethanol could be a non-pollutant and sustainable alternative.

Thermocatalytic Hydrodeoxygenation and Depolymerization of Waste Lignin to Oxygenates and Biofuels in a Continuous Flow Reactor at Atmospheric Pressure

2020 ◽  
Vol 8 (35) ◽  
pp. 13195-13205 ◽  
Author(s):  
Swathi Mukundan ◽  
Daria Boffito ◽  
Abhijit Shrotri ◽  
Luqman Atanda ◽  
Jorge Beltramini ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Continuous Flow ◽  
Flow Reactor ◽  
Continuous Flow Reactor

Synthesis of Polycycles and Oxacycles by Tandem Metathesis of endo–norbornene Derivatives

Synthesis ◽  
2021 ◽  
Author(s):  
Sambasivarao Kotha ◽  
Sunil Pulletikurti ◽  
Ambareen Fatma ◽  
gopal dhangar ◽  
gonna somu Naidu
Keyword(s):  
Natural Products ◽  
Metal Complex ◽  
Carbonyl Group ◽  
Single Step ◽  
Time Dependent ◽  
Computational Studies ◽  
Nmr Studies ◽  
Tricyclic Compounds ◽  
One Step ◽  
Norbornene Derivatives

Here, we have demonstrated that the presence of a carbonyl group at C7 position is preventing the olefin metathesis of endo-norbornene derivatives due to the complexation of the metal alkylidene. Time-dependent NMR studies showed the presence of new proton signals in the metal alkylidene region, which indicate the formation of metal complex with the carbonyl group of the substrate. These observations were further proved by ESI-MS analysis. Whereas, computational studies provided that the catalyst was interacting with the C7 carbonyl group and aligned perpendicular to that of norbornene olefin. Later, these endo-keto norbornene derivatives were reduced to hydroxyl derivatives diastereoselectively. Ring-rearrangement metathesis (RRM) of these hydroxyl derivatives, produced the [6/5/6], and [5/6/5] carbo-tricyclic cores of the natural products in one step. Whereas the RRM of O-allyl derivatives, delivered the oxa-tricyclic compounds in a single step with excellent yields.

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