title: Study on protolytic equilibria of lorazepam and oxazepam by UV and NMR spectroscopy.
abstract: 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 degrees C 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 13C- and 1H-NMR spectra, deprotonation site in the molecules of the investigated compounds was predicted. Finally, the correlation between chemical shifts in the 1H-NMR spectra and the acidity of the amide proton of 1,4-benzodiazepines was established.
authors.affiliation: Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, P.O. Box 146, 11000, Belgrade, Yugoslavia. gpopovic@chem.bg.ac.yu
authors.forename: G V
authors.initials: GV
authors.lastname: Popović
authors.forename: D M
authors.initials: DM
authors.lastname: Sladić
authors.forename: V M
authors.initials: VM
authors.lastname: Stefanović
authors.forename: L B
authors.initials: LB
authors.lastname: Pfendt
mesh_terms: D008140:Lorazepam / Q000032:analysis* / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010076:Oxazepam / Q000032:analysis* / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D010076:Oxazepam; D008140:Lorazepam