Visible Light-Emitting Diode Light-Driven Aerial Oxidation of Aldehydes under Catalyst and Solvent-Free Conditions.

Green and sustainable method for the oxidation of aldehydes into acids is now on demand as carboxylic acid are important and versatile intermediates. In this context, visible LED light-promoted aerial oxidation can be efficient and greener protocol. Herein, we have demonstrated a visible LED light-promoted efficient and greener protocol for the aerial oxidation of aromatic aldehydes into corresponding acids in absence of any additives, base, catalyst, and oxidant. The oxidation of aromatic aldehydes was irradiated by LED light at room temperature under open atmosphere, monitored by TLC. The rate of oxidation was also monitored using different LED lights by UV-Vis studies. The products were purified by column chromatography using silica gel and mixture of ethyl acetate/petroleum ether as eluting solvent and the pure products were confirmed by their melting point determination and NMR spectroscopic analysis. The aldehydes were successfully converted into corresponding acids with good isolated yields (60-90 %) by this protocol, where blue LED light (~ 490 nm) was found to be best choice. The clean aerial oxidation of aromatic aldehydes under visible LED light. The present protocol of aerial oxidation of aromatic aldehydes into corresponding acids under visible LED light has been carried out in the absence of catalyst, oxidant, base, and any other additives. The higher isolated yields, no byproduct formation, neat reaction conditions are the major advantages of the protocol.