Reactivity of the Halogen in the Isomeric 4- and 4\u27-Chloroazoxybenzenes

The relative ease of displacement of a halogen in the benzene ring by anionic reagents is markedly influenced by the character of other substituents in the ring. A thorough survey of the literature on these aromatic nucleophilic substitution reactions has been given by Bunnett and Zahler (1). These authors discuss the influences exerted by various groups in the ortho, meta and para positions, the effects of different electron donor reagents and variations in experimental conditions. Since no data are available concerning the effect of the azoxy group, it was desirable to synthesize some chloro-substituted aromatic azoxy compounds and compare them with chloro-nitro-compounds and chloro-azo-compounds. The azo-grouping has only a slight activating effect (2) being reported by Badger, Cook and Vidal (3) to be about one-sixth as effective as a nitro group