Benzoquinone imines. Part IV. Mechanism and kinetics of the formation of Bandrowski's base

摘要: The kinetics of the formation Bandrowski's base, by oxidation p-phenylenediamine with ferricyanide in aqueous solution at pH > 8, indicate that rate-controlling step involves electrophilic attack protonated p-benzoquinone di-imine on neutral p-phenylenediamine. resulting intermediate, 2,4′,5-triaminodiphenylamine, suffers rapid C(4) a second molecule to give reduced form base. latter is oxidised third di-imine, thereby regenerating p-phenylenediamine, which can thus be considered catalyst conversion into base.At < 8 reaction are complicated significant amounts p-benzosemiquinone radicals expense primary reactants. At low concentrations, relatively stable and disproportionate as base proceeds.