KINETICS OF OXIDATIVE ADDITION OF ZEROVALENT PALLADIUM TO AROMATIC IODIDES

Article abstract of DOI:10.1016/S0022-328X(00)86726-1

The kinetic of oxidative addition of zerovalent palladium to aromatic iodides in tetrahydrofuran in the presence of the ligand triphenylphosphine have been studied by amperometry on the oxidation wave of palladium.The reaction is first order in aromatic iodide and first order in palladium and the rate constant is inversely proportional to the free ligand concentration.The reactive palladium intermediate is assumed to be Pd2.This assumption is compatible with the observed activation parameters ΔH(excit.) = +77 kJ mol^-1; ΔS(excit.) = 13 J mol^-1 K^-1.With substituted aromatic iodides, the rate constants give a linear Hammett relationship with ρ = +2.The suggested mechanism can be regarded as related to an aromatic nucleophilic substitution with some assistance from halogen-palladium interaction.