ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Radical Reactions of N-Heterocyclic Compounds. IV. ESR Investigation of H-Transfer between Aminic Antioxydants and Peroxy RadicalsThe N-radicals of pyrazole-, imidazole- and indole-derivatives were prepared in comparatively high concentrations at room temperature in benzene or toluene and their e.s.r. signals were interpreted. In H-abstraction by free or to Co(III)-coordinated tert.-butylperoxy radicals from bifunctional heterocyclic substituted amines 2-9, 11 the following efficiency was ascertained: unhindered —OH— 〉 aniline-NH 〉 heterocyclic-NH—, hindered OH-groups. No radical attack on the exocyclic NH2-group took place.The splitting constant concerning the heterocyclic nitrogen of nitroxyl radicals 5a, 10a was in the range aNendo = 0.7 to 0.85 mT in contrast to exocyclic nitroxyls 6a, 8a, 9a, 11a possessing aNexo = 1.0 to 1.1 mT. The interruption of the π-conjugation between the heterocyclic and the aniline groups by insertion of a CH2-group led to the decrease of the stability of the generated N-radicals. In the case of anilinebenzimidazole 9 the Co(III)-complexed endocyclic aminyl radical 9b was observed simultaneously with the exocyclic nitroxyl radical 9a.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19863280109
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