Formation of Diazepam–Lanthanides(III) Complexes in the 50–50 Volume % Ethanol–Water Solvent System and Study of the Effect of Temperature on the Complex Formation Constants
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Diazepam (7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one) is an important derivative of the 1,4-benzodiazepine compound commercially distributed as Valium. The complex formation constants of diazepam with some light lanthanide(III) metal ions have been studied by potentiometric measurements. All titrations were performed in 50–50% (volume/volume) ethanol–water solvent mixtures at constant ionic strength (0.10 mol⋅dm−3). The ionic strength was maintained by using sodium perchlorate. The complex formation constants were determined at 25.00, 35.00 and 45.00 °C. With increasing temperature, a decrease was observed in the protonation constant (pK) of diazepam.
KeywordsDiazepam Complex formation constant Temperature Lanthanides Mixed solvent
The authors thank the late Prof. V.G. Dongre, Department of Chemistry, University of Mumbai for his precious guidance.
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