𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Carbon–13 NMR studies of tautomerism in some 2-substituted imidazoles and benzimidazoles

✍ Scribed by E. Paul Papadopoulos; Ulrich Hollstein

Publisher
John Wiley and Sons
Year
1982
Tongue
English
Weight
353 KB
Volume
19
Category
Article
ISSN
0749-1581

No coin nor oath required. For personal study only.

✦ Synopsis

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 by proton transfer from N‐1 to N‐3, possibly through intermolecular association. The rate of this proton exchange increases with concentration and temperature. It decreases with extension of the 2‐substituent (rate CH~3~≫CONH‐phenyl > CONH‐p‐tolyl ≃ CONH‐m‐chlorophenyl ≫ CONH‐n‐butyl) due to steric hindrance at the site of the (benz)imidazole nitrogen.

📜 SIMILAR VOLUMES

Carbon-13 NMR Spectra of some aryl subst
Carbon-13 NMR Spectra of some aryl substituted ferrocenes
✍ S. Gronowitz; I. Johnson; A. Maholanyiova; S. Toma; E. Solcániová 📂 Article 📅 1975 🏛 John Wiley and Sons 🌐 English ⚖ 337 KB 👁 1 views

## Abstract The carbon‐13 spectra of some __para__ and __meta__ substituted phenylferrocenes have been analysed. The substituent‐caused shifts are discussed and compared with similarly substituted biphenyls. Correlations with Hammett parameters and with the reactivity parameters of Swain and Lupton

Carbon-13 NMR spectra of substituted 2-t
Carbon-13 NMR spectra of substituted 2-thiophenecarboxanilides
✍ Maria E. Amato; Salvatore Fisichella; Giuseppe Musumarra; Francesco A. Bottino 📂 Article 📅 1987 🏛 John Wiley and Sons 🌐 English ⚖ 227 KB

The effects of the X and Y substituents on these shifts are discussed, and correlated with substituent constants and with carbon shifts of analogous series of compounds.

NMR investigation of hydrogen bonding an
NMR investigation of hydrogen bonding and 1,3-tautomerism in 2-(2-hydroxy-5-substituted-aryl) benzimidazoles
✍ V. Sridharan; S. Saravanan; S. Muthusubramanian; S. Sivasubramanian 📂 Article 📅 2005 🏛 John Wiley and Sons 🌐 English ⚖ 124 KB

## Abstract The 1,3‐tautomerism associated with 2‐(2‐hydroxy‐5‐substituted‐aryl)benzimidazoles was studied in different solvents. The effect of hydrogen bonding involving the hydroxyl group of the 2‐aryl ring on the tautomerism was investigated using NMR spectroscopy. The influence of the solvent c

Carbon-13 NMR spectra of some 4-substitu
Carbon-13 NMR spectra of some 4-substituted phenacyl bromides
✍ Fred Yukio Fujiwara; Roberto Rittner; Haydeé R. Freire 📂 Article 📅 1984 🏛 John Wiley and Sons 🌐 English ⚖ 115 KB

The 13C NMR signals for some 4substituted phenacyl bromides were assigned. The experimental chemical shifts of the aromatic ring carbons are in close agreement with those calculated using substituent chemical shifts. Both the car-bony1 and the a-methylene carbons exhibit upfield shifts compared with