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Differentiation between isomeric structures of benzazoles by 14 N, 13 C and 1 H NMR
Author(s) -
Stefaniak Lech
Publication year - 1978
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270110804
Subject(s) - ring (chemistry) , chemical shift , nitrogen , chemistry , crystallography , organic chemistry
Nitrogen chemical shifts constitute an effective means of distinguishing between isomeric benzazole ring systems. There is a large difference in nitrogen shielding, usually more than 20 ppm, between isomeric benzenoid‐ and quinonoid‐like structures. 13 C and 1 H NMR is shown to provide unambiguous structure assignment only in cases of symmetric quinonoid ring systems of azoles.