Radicals Containing a Dioxin Ring

It has been shown voltammetrically that oxidation of 1,4-dioxin and of its 2,3,5,6-tetraphenyl, benzo, and dibenzo derivatives takes place at a rotating platinum electrode in acetonitrile in single-electron steps with the intermediate formation of radical cations.The simplest dioxin cation-radical for which an ESR spectrum has been obtained is 79, for which hyperfine splittings are indicated in gauss.The radical was prepared by treatment with sulfuric acid of the dimer which forms spontaneously on the storage of acetoin. 

It is of interest to compare the distribution of spin population in 80 with that in anthracene anion-radical, with which it is isoelectronic, and also with those of similar heteroaromatic radicals. In Table are given the 

Tomita, S. Ueda, Y. Nakai, Y. Deguchi, and H. Takaki, Tetrahedron Lett., 1189 (1963). 

Variation of Proton Hyperfinb Splittings (in Gauss) with Heteroatom in Radicals ISOELECTRONIC WITH ANTHRACENE ANION-RaDICAL 

The same Romanian group has measured ESR spectra for the cation- and anion-radicals 82 and 83, respectively, of 2-nitrodibenzo[l,4]dioxin. As expected, the cation-radical is heterocycle-centered, showing a very small substituent-nitrogen hyperfine splitting, whereas the opposite is true for the 

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