The Mechanism and Kinetic Models of the Catalytic Oxidation of Ethylene by p-Benzoquinone in Aqueous–Acetonitrile Solutions of Pd(II) Cationic Complexes

Resumo

A kinetic study of ethylene oxidation to acetaldehyde by p-benzoquinone in the Pd(OAc)₂–HClO₄−LiClO₄–CH₃CN–H₂O system has been carried out under conditions when palladium(II) cationic complexes exist at a molar fraction of water of 0.67 and 30°С. For a reaction that mostly lead to the formation ofPd(CH₃CN)(H₂O)₃²⁺ two-route mechanism and a kinetic model have been proposed that describe adequately the experimental dependence of the reaction initial rate on the concentration of p-benzoquinone, HClO₄, and palladium. The model takes into account previous findings on the H₂O/D₂O and C₂H₄/C₂D₄ kinetic isotope effects and the important role of Pd(0) quinone complexes.