Communication Dans Un Congrès Année : 2022

Efficient photooxygenation process of bio-sourced alpha-terpinene by combining controlled led-driven flow photochemistry and rose bengal-anchored polymer colloids

Résumé

Organic photochemistry is a key synthetic pathway for sustainable chemistry (Hoffmann 2008). In particular, photooxygenation reactions are very attractive as they involve only singlet oxygen, a powerful selective oxidant, which is produced by safe photosensitization of oxygen in the visible range and at ambient temperature (Ghogare and Greer, 2016). They have proved to be very efficient for the preparation of endoperoxides from biosourced molecules such as terpene and furanone derivatives (Iesce et al 2012). Only a limited number of these transformations can be carried out thermally, as they require the use of complex oxidants containing either hazardous peroxides or hypervalent iodine compounds or metal catalysts. Until now, their industrial implementation is limited to a few examples in the flavour, fragrance or pharmaceutical industries (Braun et al, 2014). Batch reactors equipped with energy-demanding mercury light sources are the main systems currently used. Non-eco-friendly solvents are generally used to maximize the singlet oxygen lifetime, and the photosensitizer (as solid powder) should be regularly fed to counterbalance its degradation. Continuous-flow microstructured technologies, combined with LEDs as light sources, are promising alternatives to batch photochemical processing. Their benefits for organic photochemistry have been highlighted at lab scale (Cambié et al, 2016). Most of the literature considers a sensitizer solubilized in the reaction medium, even if the concept of solid-supported sensitizers offers many advantages. The separation of the organic sensitizer from the other reactants and products is then made easier, avoiding expensive downstream separation. It is also a strategy for transposing poorly soluble photosensitizers into green solvents, while simultaneously enhancing their photostability and reusability.

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hal-04796348 , version 1 (21-11-2024)

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  • HAL Id : hal-04796348 , version 1

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Karine Loubière, Robbie Radjagobalou, Jean-François Blanco, Luca Petrizza, Mickael Le Béchec, et al.. Efficient photooxygenation process of bio-sourced alpha-terpinene by combining controlled led-driven flow photochemistry and rose bengal-anchored polymer colloids. International Symposium on Green chemistry (ISGC), May 2022, La Rochelle, France. ⟨hal-04796348⟩
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