ISSN:
0749-1581
Keywords:
13C NMR
;
1H NMR
;
Ranitidine
;
E/Z isomerization
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The E/Z configurational equilibrium of the nitroethylenic moiety of the antiulcer agent ranitidine was studied in aqueous solution and in DMSO-d6 and CDCl3 using 1H and 13C NMR spectroscopy. In aqueous solution the room temperature E/Z isomerization of the unprotonated nitroketenediamine moiety is fast on the NMR time scale, but becomes slow for the species protonated at this moiety owing to intramolecular hydrogen bonding between the nitro group and a neighbouring NH2R+ group. In DMSO-d6 a free energy of activation of the order of 70 kJ mol-1 was estimated for the E/Z isomerization of the unprotonated moiety of ranitidine, in good agreement with values previously found for 2,2-disubstituted nitroethylene model compounds.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260250305
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