The Wacker Oxidation is an industrial process, which allows the synthesis of ethanal from ethene by palladium-catalyzed oxidation with oxygen. Copper serves as redox cocatalyst.
The lab scale modification - the Wacker-Tsuji Oxidation - is useful for the synthesis of various ketones.
Mechanism of the Wacker-Tsuji Oxidation
The mechanism is typical of palladium olefin chemistry, and water serves as the oxygen source; the reduced palladium is reoxidized by Cu(II) and ultimately by atmospheric oxygen.
J. Tsuji, "Palladium Reagents and Catalysts", First Edition 2004, Wiley, 29-35.
Convenient and Efficient Pd-Catalyzed Regioselective Oxyfunctionalization of Terminal Olefins by Using Molecular Oxygen as Sole Reoxidant
T. Mitsudome, T. Umetani, N. Nosaka, K. Mori, T. Mizugaki, K. Ebitani, K. Kaneda, Angew. Chem. Int. Ed., 2006, 45, 481-485.
A General and Efficient Catalyst System for a Wacker-Type Oxidation Using TBHP as the Terminal Oxidant: Application to Classically Challenging Substrates
B. W. Michel, A. M. Camelio, C. N. Cornell, M. S. Sigman, J. Am. Chem. Soc., 2009, 131, 6076-6077.