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1H and 13C NMR study of the structure of pyrazoles, imidazoles and their benzo derivatives in sulphuric acid (azolium cations)

✍ Scribed by José Elguero; María Luisa Jimeno; Gloria I. Yranzo

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
408 KB
Volume
28
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

The NMR spectra of two imidazoles, benzimidazole, four pyrazoles and three indazoles were recorded in 98% sulphuric acid, and the ^1^H, ^13^C, ^1^H–^1^H and ^1^H–^13^C spectral parameters of the corresponding azolium ions were obtained. The ^1^H N‐H chemical shifts and the ^1^H and ^13^C couplings with the NH proton are discussed. All ^3^J(^1^H^1^H) and ^4^J(^1^H^1^H) coupling constants have values between 1.5 and 3.0 Hz. All ^2^J(^1^H^13^C) and ^3^J(^1^H^13^C) values are about 6 Hz, with the exception of couplings involving C‐4 in imidazolium ions [^2^J(C‐4,H‐5) ≈ 12 Hz, ^3^J(C‐4,H‐1) ≈ 3 Hz].

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