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Tautomerism in OH-, SH-, and NH2-substituted pyrazines - a carbon-13 and nitrogen-15 NMR study -

✍ Scribed by Stefan Tobias; Harald Günther

Book ID
104219723
Publisher
Elsevier Science
Year
1982
Tongue
French
Weight
229 KB
Volume
23
Category
Article
ISSN
0040-4039

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✦ Synopsis

It is shown that 13 1 C, H spin-spin coupling constants can be used to study heteroaromatic tautomerism. Results for the title compounds are supported by 15 N-NMR data. NMR spin-spin coupling constants between carbon-13 and protons have recently been recognized as sensitive probes for the elucidation of protonation schemes in heterocyclic systems. 1) The application of these parameters to problems of heteroaromatic tautomerism of the pyridone-hydroxypyridine type 2) was thus indicated. Considering the tautomers A and B, on the basis of earlier results 1,3) we expected especially the constants involving 6-H -i.e. 3 5(2,6) and 2 J(5,6) -to differ characteristically in both structures.

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Carbon–13 NMR studies of tautomerism in
Carbon–13 NMR studies of tautomerism in some 2-substituted imidazoles and benzimidazoles
✍ E. Paul Papadopoulos; Ulrich Hollstein 📂 Article 📅 1982 🏛 John Wiley and Sons 🌐 English ⚖ 353 KB

## Abstract The ^13^C NMR spectra of several 2‐substituted imidazoles and benzimidazoles have been measured. The substituent was CH~3~, COOH and CONHR, where R = H, __n__‐Bu, __p__‐tolyl or __m__‐chlorophenyl. Carbons 4 and 5 in the imidazoles and the carbon pairs 8/9, 4/7 and 5/6 become equivalent