Evidence for the intermediacy of the aryl radical in the Sandmeyer reaction

Abstract

The competition between bromodediazoniation and chiorodediazoniation is exploited as a test of the occurrence of an aryl radical in the Sandmeyer reaction pathway. The use of five reducing agents, covering a wide range of redox ability, is shown not to influence the experimental k_Br/k_Cl values. The intermediacy of a common species is consequently inferred and supported by independent generation of the phenyl radical by decomposition of benzoyl peroxide. Considerations on the rates of the ligand transfer processes are put forward.