Selective and efficient oxidation of ethylene to ethylene glycol acetates with H2O2 catalyzed by Pd(OAc)2-di(2-pyridyl)ketone-di(2-pyridyl)methanesulfonate system

Novel systems for palladium-catalyzed selective oxidation of ethylene to a mixture of ethylene glycol mono- and di-acetates as the major reaction products (90-95% selectivity) with H2O2 in acetic acid solution at ambient pressure and 20 degrees C were developed. The catalytic reaction is very efficient with up to 90% combined yield of glycol acetates with H2O2 as a limiting reagent and 1 mol% catalyst loading. The catalytic systems developed are comprised of a mixture of Pd(OAc)(2), and 6-methyl substituted (2-pyridyl) methanesulfonate and/or di(6-pyridyl)ketone ligands. Compositions of the binary, Pd(OAc)(2)-dpk, Pd(OAc)(2)-Me-dpms, and ternary, Pd(OAc)(2)-dpk-Me-dpms, systems have been studied by means of H-1 NMR spectroscopy and ESI mass spectrometry. Kinetics studies were performed as well and plausible reaction mechanism was suggested, which features facially chelating ligand-enabled facile oxidation of (PdC2H4OAc)-C-II intermediates with H2O2 to form (PdC2H4OAc)-C-IV transients. (C) 2011 Elsevier B.V. All rights reserved.