Investigating the photochemical reaction of an oxazolone derivative under continuous-flow conditions: from analytical monitoring to implementation in an advanced UVC-LED-driven microreactor

This study examined the photochemical transformation of an oxazolone derivative in a continuous microreactor irradiated by a UVC LED array (273 nm). The aim of this study was to transfer the reaction protocol originally developed under batch conditions to continuous flow and to further evaluate the...

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Bibliographic Details
Published in:Journal of flow chemistry 2023-12, Vol.13 (4), p.413-425
Main Authors: Lebrun, Gaëlle, Schmitt, Marie, Oelgemöller, Michael, Vedrenne, Marc, Blanco, Jean-François, Loubière, Karine
Format: Article
Language:English
Subjects:
Chemical and Process Engineering
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Engineering Sciences
Green Chemistry
Industrial Chemistry/Chemical Engineering
Inorganic Chemistry
Nanochemistry
Organic Chemistry
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Summary:This study examined the photochemical transformation of an oxazolone derivative in a continuous microreactor irradiated by a UVC LED array (273 nm). The aim of this study was to transfer the reaction protocol originally developed under batch conditions to continuous flow and to further evaluate the scope of this application. A custom-built UVC-LED panel was combined with a microchip, and this microflow system allowed to work under perfectly controlled operating conditions. NMR and LC-MS were used to identify and quantify the main products obtained during the reaction. From this, an HPLC method was developed for imine separation, allowing for an easy and fast monitoring of the reaction progress. Subsequently, the influence of the operating conditions (residence time, photon flux density, temperature) on the selectivity and conversion was investigated to identify the most favorable conditions for a specific product. Temperature did not affect conversion but had an impact on the reaction’s selectivity. The developed UVC-LED-driven continuous-flow microreactor was found to be very efficient since a quantum photon balance ratio of 0.7 was enough to convert all the reactant, while at the same time achieving the maximal yield of the target product. Exhaustive irradiation did not change the molar ratio of each compound present in the reaction medium, thus excluding follow-up photoreactions of the products. This work opens promising perspectives for boosting flow photochemistry in the UV-C domain. Graphical abstract
ISSN:2062-249X
2063-0212
DOI:10.1007/s41981-023-00284-y