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 most byproducts 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.