A new highly selective and environment-friendly Wacker oxidation process employing superparamagnetic Pd–Fe3O4 heterodimer nanocrystals in EtOH–H2O under 1 atm O2 has been developed. Consistently high yields of the desired Wacker product and excellent reaction selectivity were observed in almost all of the reactions examined. This operationally simple oxidation protocol allows recycling of the Pd–Fe3O4 catalyst after the reaction through the use of an external magnet.
