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A modified procedure has been developed for the synthesis of Kuhn verdazyl radicals via conversion of 1-(4-R1-phenyl)-3-(4-R2-phenyl)-5-phenylformazan into 1-(4-R1-phenyl)-3-(4-R2-phenyl)-5-phenylver-dazylium tetrafluoroborates, followed by their reduction with D-glucose in alkaline medium to 1-(4-R1-phenyl)-3-(4-R2-phenyl)-5-phenylleucoverdazyls and oxidation of the latter with atmospheric oxygen. The formation of 1-(4-R1-phenyl)-3-(4-R2-phenyl)-5-phenylverdazyl radicals was confirmed by ESR spectroscopy. [ABSTRACT FROM AUTHOR]

The corresponding formazans were synthesized by the reaction of phenylhydrazones of nitro-substituted benzaldehydes and 4-pyridinecarbaldehyde with arenediazonium salts obtained from p-substituted anilines. Formazans were converted into the corresponding 5,6-dihydro-1,2,4,5-tetrazinium triflates by the action of formalin in the presence of CF3SO3H. When tetrazinium salts were treated with D-glucose in a weakly alkaline medium (NH4OH) in the presence of atmospheric oxygen, stable tetrazinyl radicals were formed. Formazans, tetrazinium triflates, and tetrazinyl radicals were isolated in the individual state and characterized by elemental analysis, IR, UV, NMR, or ESR (radicals) spectroscopy. [ABSTRACT FROM AUTHOR]