Electron transfer mechanism of aromatic 'nucleophilic' substitution

Abstract

Mechanistic implications of the ready formation of aryl iodides from aryldiazonium salt solutions and the iodide ion (in contrast with the general need for cuprous or other catalysts with other halides) have been studied. The reaction between benzenediazonium fluoroborate and potassium iodide in methanol at 0°C has been investigated. A new mechanism involving initial one-electron transfer from the iodide anion to the benzenediazonium cation, resulting in the formation of radical intermediates by heterolytic cleavage of a bond, has been proposed in order to account for the products, viz. iodobenzene, benzene, biphenyl, iodine, anisole, and formaldehyde, and the effect of photochemical catalysis.