Radical reactions in the co‐ordination sphere of transition metals IX—phenoxy and cyclohexadienonyloxy radicals derived from 2,2′‐biphenyldiols and 2,2′‐thiobisphenols

Abstract

AbstractFrom a series of antioxidants comprising 2,2′‐biphenyldiols, 2,2′‐thiobisphenols and 2,2′‐dithiobisphenol, free phenoxyls were prepared by oxidation with tert‐butylperoxyls co‐ordinated to Co(III) in non‐polar media at ambient temperature. Both the effect of extended conjugation as a consequence of the direct bond between the two aromatic nuclei and, also, the steric effect of alkyl substituents could be observed. In the presence of free tert‐butylperoxyls in excess, primary phenoxyls are transformed into cyclohexadienonyloxyls, which form stable radical complexes with Co(III). A mechanism for the formation of the cyclohexadienonyloxyls is suggested.