Radical cations, generation from pyrazines

Azacyclohexatriene-2-ylidene (3), the 2-isomer of pyridine, has been generated by one-electron oxidation of the corresponding radical cation in neutralization-reionization mass spectrometry.17 It was determined by ab initio H-F calculations that the charge polarization of the radical fonned by H-abstraction from pyrazine can be... 

Reduction of pyrazine with potassium in 1,2-diethoxyethane at — 70° gives the paramagnetic radical anion. Anions have also been generated from the low-temperature reaction of pyrazine, methyl-pyrazine, 2,5- and 2,6-dimethylpyrazines with sodium or potassium in tetrahydrofuran or 1,2-dimethoxyethane. From measurements of their ESR spectra, ion-pair formation is proposed between the alkali metal cation and the pyrazine anion.96-101... 

Fenner and co-workers have described radicals in which an NH from the pyrazine ring of lumazine or isoalloxazine derived radicals is replaced by S (e.g., 273-275) (cf. Part I Section III,C,5). Cation-radicals were generated by solution of the parent heterocycles in concentrated sulfuric acid or by oxidation by dibenzoyl peroxide in trifluoracetic acid-containing... 

Heterocyclic Compounds. All the heterocyclic compounds, unsubstituted by electroactive groups, from which radical ions have been obtained by electrochemical generation are nitrogen heterocycles. Among the numerous systems involved radical anions have been obtained from pyrazine [118], pyridazine [126], and tetrazine [126], and radical cations have been obtained from dihydropyrazine [126-128] and dihydrotetramethylpyrazine [128]. 

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