✦ LIBER ✦
NMR of terminal oxygen. 16—17O NMR of amide-analogous N-acyl derivatives of non-basic nitrogen groups: The question of amide resonances
✍ Scribed by Hans Dahn; Vien Van Toan; Peter Péchy
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 387 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
Abstract
Natural abundance ^17^O NMR data for six classes of N‐acyl compounds RCONX are reported: acylazide, acylisocyanate, acylisothiocyanate, diacyldiimide, 1‐acylimidazole and N,N′‐carbonyldiimidazole. Compared with the normal amide group, they all show strong deshielding (Δδ ≈︁ 70–130 ppm), which is attributed to diminished resonance of the CO group with the weaker electron donor NX. The high shielding of isocyanate oxygen is attributed to symmetry‐based anisotropy effects.