scholarly journals Continuous Flow Chiral Amine Racemization Applied to Continuously Recirculating Dynamic Diastereomeric Crystallizations

2021 ◽  
Vol 86 (3) ◽  
pp. 2458-2473
Author(s):  
Maria H. T. Kwan ◽  
Jessica Breen ◽  
Martin Bowden ◽  
Louis Conway ◽  
Ben Crossley ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Chiral Amine

scholarly journals A general and atom-efficient continuous-flow approach to prepare amines, amides and imines via reactive N-chloramines

2018 ◽  
Vol 14 ◽  
pp. 2220-2228 ◽  
Author(s):  
Katherine E Jolley ◽  
Michael R Chapman ◽  
A John Blacker
Keyword(s):  
Continuous Flow ◽  
Important Class ◽  
Chiral Amine ◽  
Reactive N

Chloramines are an important class of reagents, providing a convenient source of chlorine or electrophilic nitrogen. However, the instability of these compounds is a problem which makes their isolation and handling difficult. To overcome these hazards, a continuous-flow approach is reported which generates and immediately reacts N-chloramines directly, avoiding purification and isolation steps. 2-Chloramines were produced from the reaction of styrenes with N-alkyl-N-sulfonyl-N-chloramines, whilst N-alkyl or N,N’-dialkyl-N-chloramines reacted with anisaldehyde in the presence of t-BuO2H oxidant to afford amides. Primary and secondary imines were produced under continuous conditions from the reaction of N-chloramines with base, with one example subsequently reduced under asymmetric conditions to produce a chiral amine in 94% ee.

scholarly journals Enantioselective Transamination in Continuous Flow Mode with Transaminase Immobilized in a Macrocellular Silica Monolith

2017 ◽  
Author(s):  
Ludivine van den Biggelaar ◽  
Patrice Soumillion ◽  
Damien P. Debecker
Keyword(s):  
Continuous Flow ◽  
Preferential Flow ◽  
Kinetic Resolution ◽  
Flow Reactor ◽  
Sol Gel ◽  
Flow Mode ◽  
Chiral Amine ◽  
Silica Monoliths ◽  
Covalent Grafting ◽  
Heterogeneous Biocatalysts

ω-Transaminases have been immobilized on macrocellular silica monoliths and used as heterogeneous biocatalysts in a continuous flow mode enantioselective transamination reaction. The support was prepared by a sol-gel method based on emulsion-templating. The enzyme was immobilized on the structured silica monoliths both by adsorption, and by covalent grafting using amino-functionalized silica monoliths and glutaraldehyde as a coupling agent. A simple reactor set-up based on the use of a heat-shrinkable Teflon tube is presented and successfully used for the continuous flow kinetic resolution of a chiral amine, 4-bromo-α-methylbenzylamine. The porous structure of the supports ensures effective mass transfer and the reactor works in the plug flow regime without preferential flow paths. When immobilized in the monolith and used in the flow reactor, transaminases retain their activity and their enantioselectivity. The solid biocatalyst is also shown to be stable both on stream and during storage. These essential features pave the way to the successful development of an environmentally friendly process for chiral amines production.

scholarly journals Enantioselective Transamination in Continuous Flow Mode with Transaminase Immobilized in a Macrocellular Silica Monolith

2017 ◽  
Author(s):  
Ludivine van den Biggelaar ◽  
Patrice Soumillion ◽  
Damien P. Debecker
Keyword(s):  
Continuous Flow ◽  
Preferential Flow ◽  
Kinetic Resolution ◽  
Flow Reactor ◽  
Sol Gel ◽  
Flow Mode ◽  
Chiral Amine ◽  
Silica Monoliths ◽  
Covalent Grafting ◽  
Heterogeneous Biocatalysts

ω-Transaminases have been immobilized on macrocellular silica monoliths and used as heterogeneous biocatalysts in a continuous flow mode enantioselective transamination reaction. The support was prepared by a sol-gel method based on emulsion templating. The enzyme was immobilized on the structured silica monoliths both by adsorption, and by covalent grafting using amino-functionalized silica monoliths and glutaraldehyde as a coupling agent. A simple reactor set-up based on the use of a heat-shrinkable Teflon tube is presented and successfully used for the continuous flow kinetic resolution of a chiral amine, 4-bromo-α-methylbenzylamine. The porous structure of the supports ensures effective mass transfer and the reactor works in the plug flow regime without preferential flow paths. When immobilized in the monolith and used in the flow reactor, transaminases retain their activity and their enantioselectivity. The solid biocatalyst is also shown to be stable both on stream and during storage. These essential features pave the way to the successful development of an environmentally friendly process for chiral amines production.

Catalyst- and oxidant-free electrochemical para-selective hydroxylation of N-arylamides in batch and continuous-flow

2020 ◽  
Vol 22 (19) ◽  
pp. 6437-6443
Author(s):  
Cheng-Kou Liu ◽  
Meng-Yi Chen ◽  
Xin-Xin Lin ◽  
Zheng Fang ◽  
Kai Guo
Keyword(s):  
Ammonium Salt ◽  
Quaternary Ammonium ◽  
Continuous Flow ◽  
Quaternary Ammonium Salt ◽  
Selective Hydroxylation

A catalyst-, oxidant-, acidic solvent- and quaternary ammonium salt-free electrochemical para-selective hydroxylation of N-arylamides at rt in batch and continuous-flow was developed.

Development of a Progression-Based Signal-Timing Strategy for Continuous-Flow Intersections

2021 ◽  
Vol 147 (3) ◽  
pp. 04021002
Author(s):  
Wenrui Qu ◽  
Shaojie Liu ◽  
Qun Zhao ◽  
Yi Qi
Keyword(s):  
Continuous Flow ◽  
Signal Timing

Avalanche Stratification - Experimental Tests of the “Metastable Wedge” and “Continuous Flow” Models

2000 ◽  
Vol 627 ◽  
Author(s):  
M. E. Swanson ◽  
M. Landreman ◽  
J. Michel ◽  
J. Kakalios
Keyword(s):  
Continuous Flow ◽  
Granular Media ◽  
Experimental Tests ◽  
Coarse Sand ◽  
Angle Of Repose ◽  
Flow Models ◽  
Maximum Angle ◽  
Stratification Effect ◽  
Upward Moving ◽  
Moving Layer

ABSTRACTWhen an initially homogeneous binary mixture of granular media such as fine and coarse sand is poured near the closed edge of a “quasi-two-dimensional” Hele-Shaw cell consisting of two vertical transparent plates held a narrow distance apart, the mixture spontaneously forms alternating segregated layers. Experimental measurements of this stratification effect are reported in order to determine which model, one which suggests that segregation only occurs when the granular material contained within a metastable heap between the critical and maximum angle of repose avalanches down the free surface, or one for which the segregation results from smaller particles becoming trapped in the top surface and being removed from the moving layer during continuous flow. The result reported here indicate that the Metastable Wedge model provides a natural explanation for the initial mixed zone which precedes the formation of the layers, while the Continuous Flow model explains the observed upward moving kink of segregated material for higher granular flux rates, and that both mechansims are necessary in order to understand the observed pairing of segregated layersfor intermediate flow rates and cell separations.

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