Authors:Zine Eddine Hamami, Laurent Vanoye, Pascal Fongarland, Claude de Bellefon and Alain Favre-Reguillon
An efficient and metal-free method for the oxidation of aldehydes to the corresponding carboxylic acids has been developed. In a simple continuous-flow photochemical reactor, the use of camphorquinone (CQ) irradiated with a white light-emitting diode (LED) source enhanced the autoxidation of aldehydes. Under 5 bar of oxygen, visible light, and 0.3 mol% of CQ, the rate of oxidation was increased from 6 times with 2-ethylhexanal to 30 times for n-nonanal. The large interfacial area generated by a segmented flow apparatus associated with radicals formed by photooxidation of CQ ensures metal-free high throughput of carboxylic acids under safe conditions.