scholarly journals Translation of microwave methodology to continuous flow for the efficient synthesis of diaryl ethers via a base-mediated SNAr reaction

2011 ◽  
Vol 7 ◽  
pp. 1360-1371 ◽  
Author(s):  
Charlotte Wiles ◽  
Paul Watts
Keyword(s):  
Reaction Time ◽  
Continuous Flow ◽  
Stopped Flow ◽  
Efficient Synthesis ◽  
Diaryl Ethers ◽  
Microwave Reactor ◽  
Starting Point ◽  
Microreaction Technology ◽  
Snar Reaction ◽  
Rapid Reaction

Whilst microwave heating has been widely demonstrated as a synthetically useful tool for rapid reaction screening, a microwave-absorbing solvent is often required in order to achieve efficient reactant heating. In comparison, microreactors can be readily heated and pressurised in order to “super-heat” the reaction mixture, meaning that microwave-transparent solvents can also be employed. To demonstrate the advantages associated with microreaction technology a series of SNAr reactions were performed under continuous flow by following previously developed microwave protocols as a starting point for the investigation. By this approach, an automated microreaction platform (Labtrix® S1) was employed for the continuous flow synthesis of diaryl ethers at 195 °C and 25 bar, affording a reduction in reaction time from tens of minutes to 60 s when compared with a stopped-flow microwave reactor.

Visible Light-Mediated Oxidative Debenzylation

2020 ◽  
Author(s):  
Cristian Cavedon ◽  
Eric T. Sletten ◽  
Amiera Madani ◽  
Olaf Niemeyer ◽  
Peter H. Seeberger ◽  
...  
Keyword(s):  
Reaction Time ◽  
Visible Light ◽  
Functional Groups ◽  
Continuous Flow ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Complex Molecules ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow. <br>

scholarly journals Achieving selectivity in porphyrin bromination through a DoE-driven optimization under continuous flow conditions

2020 ◽  
Author(s):  
Paolo Zardi ◽  
Michele Maggini ◽  
Tommaso Carofiglio
Keyword(s):  
Reaction Time ◽  
Design Of Experiment ◽  
Continuous Flow ◽  
Optimization Process ◽  
Porphyrin Ring ◽  
Flow Conditions ◽  
Reaction Parameters ◽  
Synthetic Procedure ◽  
Relevant Factors ◽  
Post Functionalization

AbstractThe post-functionalization of porphyrins through the bromination in β position of the pyrrolic rings is a relevant transformation because the resulting bromoderivatives are useful synthons to covalently link a variety of chemical architectures to a porphyrin ring. However, single bromination of porphyrins is a challenging reaction for the abundancy of reactive β-pyrrolic positions in the aromatic macrocycle. We herein report a synthetic procedure for the efficient preparation of 2-bromo-5,10,15,20-tetraphenylporphyrin (1) under continuous flow conditions. The use of flow technology allows to reach an accurate control over critical reaction parameters such as temperature and reaction time. Furthermore, by performing the optimization process through a statistical DoE (Design of Experiment) approach, these parameters could be properly adjusted with a limited number of experiments. This process led us to a better understanding of the relevant factors that govern porphyrins monobromination and to obtain compound 1 with an unprecedent 80% yield.

scholarly journals Continuous-Flow Processes for the Production of Floxacin Intermediates: Efficient C–C Bond Formation through a Rapid and Strong Activation of Carboxylic Acids

2020 ◽  
Vol 02 (03) ◽  
pp. e128-e132
Author(s):  
Shao-Zheng Guo ◽  
Zhi-Qun Yu ◽  
Wei-Ke Su
Keyword(s):  
Reaction Time ◽  
Continuous Flow ◽  
Flow System ◽  
Bond Formation ◽  
Product Yield ◽  
Raw Material ◽  
Material Consumption ◽  
Tank Reactor ◽  
Mild Conditions ◽  
Flow Processes

AbstractThe development of highly efficient C–C bond formation methods for the synthesis of ethyl 2-(2,4-dichloro-5-fluorobenzoyl)-3-(dimethylamino)acrylate 1 in continuous flow processes has been described, which is based on the concept of rapid and efficient activation of carboxylic acid. 2,4-Dichloro-5-fluorobenzoic acid is rapidly converted into highly reactive 2,4-dichloro-5-fluorobenzoyl chloride by treating with inexpensive and less-toxic solid bis(trichloromethyl)carbonate. And then it rapidly reacts with ethyl 3-(dimethylamino)acrylate to afford the desired 1. This process can be performed under mild conditions. Compared with the traditional tank reactor process, less raw material consumption, higher product yield, less reaction time, higher operation safety ensured by more the environmentally friendly procedure, and process continuity are achieved in the continuous-flow system.

A Simple Continuous Flow Microwave Reactor

2005 ◽  
Vol 70 (17) ◽  
pp. 7003-7006 ◽  
Author(s):  
Mark C. Bagley ◽  
Robert L. Jenkins ◽  
M. Caterina Lubinu ◽  
Christopher Mason ◽  
Robin Wood
Keyword(s):  
Continuous Flow ◽  
Microwave Reactor

A stopped-flow/continuous-flow method for kinetic determinations

1995 ◽  
Vol 309 (1-3) ◽  
pp. 277-282 ◽  
Author(s):  
Yun-Sheng Hsieh ◽  
S.R. Crouch
Keyword(s):  
Continuous Flow ◽  
Stopped Flow ◽  
Flow Method ◽  
Continuous Flow Method

scholarly journals Continuous Flow Chlorination of Alkenyl Iodides Promoted by Copper Tubing

Synthesis ◽  
2018 ◽  
Vol 51 (01) ◽  
pp. 251-257 ◽  
Author(s):  
Antoine Nitelet ◽  
Vanessa Kairouz ◽  
Hélène Lebel ◽  
André Charette ◽  
Gwilherm Evano
Keyword(s):  
Reaction Time ◽  
Double Bond ◽  
Continuous Flow ◽  
Batch Process ◽  
Flow Synthesis ◽  
Copper Tubing

A simple continuous flow synthesis of alkenyl chlorides from the corresponding readily available alkenyl iodides in copper reactor tubing is described. A variety of alkenyl chlorides were obtained in good to excellent yields with full retention of the double bond geometry. The reaction time was reduced by a factor of 24–48 compared to the batch process.

Rate of bicarbonate-chloride exchange in human red cells at 37 degrees C

1976 ◽  
Vol 40 (5) ◽  
pp. 707-714 ◽  
Author(s):  
R. A. Klocke
Keyword(s):  
Continuous Flow ◽  
Co2 Concentration ◽  
Carbonic Anhydrase Activity ◽  
Chloride Ions ◽  
Red Cell ◽  
Chloride Permeability ◽  
Red Cell Membrane ◽  
Chloride Exchange ◽  
Rapid Reaction ◽  
Human Red Cells

The rate of exchange of bicarbonate and chloride ions across the red cell membrane was studied in a continuous flow rapid reaction apparatus at 37 degrees C. A transmembrane gradient both ions was produced by mixture of cells suspended in a solution of one ion with an isosmotic solution of the other ion. Carbonic anhydrase activity was inhibited by acetazolamide to prevent changes in CO2 concentration during the experiments. Chloride and bicarbonate efflux from cells were studied in separate experiments at each experimental pH. Using a least squares technique, values of chloride and bicarbonate permeabilities were fitted to each pair of independent experiments. Chloride permeability averaged 1.1 (+/- 0.2 SD) X 10–4 cm/s and was not affected by change in pH. Recovered bicarbonate permeabilities varied widely, always remaining at least fivefold greater than chloride permeability. While bicarbonate permeability could not be accurately characterized, it appears to be greater than chloride permeability. Analysis of CO2 transfer with the estimated permeabilities indicates that the bicarbonate-chloride exchange by itself probably does not limit CO2 transfer.

A Continuous-Flow Model for Phonatory Reaction Time

1991 ◽  
Vol 34 (3) ◽  
pp. 517-525 ◽  
Author(s):  
Carole Ferrand ◽  
Gordon W. Blood ◽  
Harvey R. Gilbert
Keyword(s):  
Reaction Time ◽  
Continuous Flow ◽  
Vocal Fold ◽  
Flow Model ◽  
Reaction Time Task ◽  
Central Process ◽  
Brain Potentials ◽  
Time Task ◽  
Vocal Fold Vibration ◽  
Yield Information

The purpose of this study was to validate a proposed continuous-flow model of phonatory reaction time by investigating the temporal order of selected laryngeal and neurophysiological events involved in a phonatory reaction time task. Ten normal speakers participated in a phonatory reaction time task. Laryngeal positioning movements prior to vocal fold closure (laryngeal shift) and onset of vocal fold vibration (acoustic onset) were recorded with an electroglottograph. P300 brain potentials were collected simultaneously, and they served as an index of a central process underlying reaction time. The obtained temporal ordering of laryngeal shift, P300, and acoustic onset supported a continuous-flow model of phonatory reaction time. Use of this model might yield information that is more accurate in explaining physiological function and more precise in describing temporal patterning than the serial model.

Efficient Synthesis of Ir-Polyoxometalate Cluster Using a Continuous Flow Apparatus and STM Investigation of Its Coassembly Behavior on HOPG Surface

2016 ◽  
Vol 55 (11) ◽  
pp. 5585-5591 ◽  
Author(s):  
Junyong Zhang ◽  
Shaoqing Chang ◽  
Bryan H. R. Suryanto ◽  
Chunhua Gong ◽  
Xianghua Zeng ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Efficient Synthesis ◽  
Flow Apparatus
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