Analytical Chemistry and Spectroscopy
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The 13C NMR spectra of some 1,3-diaryltriazenes, 3(1)-aryl-1(3)-hetaryltriazenes and their methylated derovatives have been recorded. From the comparison of the 13C chemical shifts between 3-aryl-1-(3,4-dimethyl-5-isoxazolyl)triazenes 1 and compounds with fixed structure, such as 1-aryl-3,3-dimentyltriazenes and methylated derivatives of 5-amino-3,4-dimethylisxazole, we found that the triazenes 1 have the sturcture (A) in which the azo group is conjugated with the heterocycllic moiety. para-Substituent on the aromatic ring have a week influence on the displacement of this tautomeric equilibrium. 13C NMR gives only qualitatives results. Theoretical calculation (HMO, CNDO-2) are also consistent with the greater stability of tautomeric form A.
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