Radicals from Oxadiazoles, Thiadiazoles, and Selenadiazoles

Hiinig, D. Scheutzow, H. Schlaf, and A. Schott, Justus Liebigs Ann. Chem., 1423 (1974). 

Several electrochemiluminescent systems have been described which involve 220.i -i - - - 2 

Pirkle and Gravel have described the synthesis of 3-substituted l,3,4-oxazolidine-2,5-diones and the preparation from these of heterocyclic i-radicals (e.g., 221) by oxidation of a solution in toluene with lead dioxide. The radicals are best considered as cyclic acylhydrazide radicals they are relatively persistent, decomposing over 48 h in solution, but are not isolable. 

Attempts to reduce furoxans (e.g., 3,4-dimethyl-1,2-5-oxadiazole 2-oxide) to anion-radicals led to paramagnetic products of indeterminate structure or multielectron reduction products.  

4-oxadiazoles in protic media results in the transfer of a total of six electrons in two waves corresponding to the attachment of first two and then four electrons, one-electron reduction of 2,5-diaryl-l,3,4-oxadiazoles occurs in DMF. The ESR spectrum of the anion-radical 220 of 2,5- 

Several electrochemiluminescent systems have been described which involve 

Pirkle and Gravel have described the synthesis of 3-substituted 

---