Oxidation of alcohols using solid-phase hypervalent iodine reagents in continuous flow Kathrin Bensberg, Stefan F. Kirsch, Athanasios Savvidis, Frederic Ballaschk University of Wuppertal, Germany The oxidation of alcohols towards carbonyls is one of the most fundamental reactions in organic chemistry. Decades of research have already been invested to study these apparent, easy transformations. 1 A plethora of methods have been invented, primary using metals or toxic reagents (e.g. chromium-based). Current demands of modern, organic chemistry to fulfil the 12 principles of green chemistry (atom economy, less hazardous chemical syntheses, or safer solvent use etc.) do not really match here. 2,3 Nevertheless, the challenge of creating a more sustainable future requires addressing these problems and making the usage of greener methods more attractive to both academia and industry. 4 The development of hypervalent iodine reagents, such as IBX or DMP, were already an improvement in terms of safety and sustainability, despite the requirement of stoichiometric or even overstoichiometric use. Therefore, they do not meet the requirements of an atom economic reaction. 5 To adapt to the challenge of creating more environmental-friendly methods, we developed a metal-free, sustainable method for the oxidation of various alcohols 6 in continuous flow. The utilization of a reusable cartridge with a solid-supported hypervalent iodine catalyst system made the transformation of a variety of alcohols towards their corresponding aldehydes or ketones possible. The efficiency of this method regarding the reaction time is complemented by its sustainability aspects. Reusability and use of in “green” solvents makes this method a powerful, yet environmentally friendly tool for the transformation of alcohols. References
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