Palladium-charcoal Catalyzed Direct Esterification of Aldehydes to Esters by NaIO4

An efficient direct oxidation method was developed to oxidize some aromatic and aliphatic aldehydes to esters by the dual utilization of NaIO4 and Pd-C. At ambient conditions, various aldehydes were employed in a clean esterification reaction to afford numerous esters in good to excellent yields. By this adopted method, some multifunctional aldehydes, high-energy-containing aromatic and unsaturated aldehydes, were advantageously oxidized to esters without noticeable difficulties. Moreover, no over-oxidation occurred to alcohols, and mostly by products were not formed during this oxidation process. Conventional and some modern methods lag behind owing to their easier operability and easy work-up process. This investigation has proven that the required oxidant (NaIO4) or catalyst (Pd-C) is useless to employ in excess, although some current methods utilize hugely expensive reagents for such conversions. Mundane reaction set-up, easy product recovery technique, non-toxic catalyst, and cheap and available starting materials are the noteworthy advantages of this method.