Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy
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Protolytic equilibria in homogeneous and heterogeneous systems of lorazepam and oxazepam, which are sparingly soluble ampholytes from the class of 1,4-benzodiazepines, were studied at 25 degreesC and ionic strength of 0.1 M. Acidity constants and equilibrium constants in a heterogeneous system were determined. On the basis of the analysis of the corresponding C-13- and H-1-NMR spectra, deprotonation site in the molecules of the investigated compounds was predicted. Finally, the correlation between chemical shifts in the H-1-NMR spectra and the acidity of the amide proton of 1,4-benzodiazepines was established.
Source:Journal of Pharmaceutical and Biomedical Analysis, 2003, 31, 4, 693-699
- Pergamon-Elsevier Science Ltd, Oxford