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

• Published in: Journal of solution chemistry Vol. 41; no. 2; pp. 241 - 248
• Main Authors: Bayes, Gunaji S., Raut, Sambhaji S., Patil, Vishwanath R., Lokhande, Rama S.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.03.2012; Springer
• Subjects: Chemistry; Chemistry and Materials Science; Complex formation; Condensed Matter Physics; Constants; Derivatives; Exact sciences and technology; General and physical chemistry; Geochemistry; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Metal ions; Oceanography; Physical Chemistry; Protonation; Solutions; Solvents; Strength; Titration; Temperature; Mixed solvent; Complex formation constant; Lanthanides; Diazepam; Water; Lanthanide; Ethanol; Metal ion; Alcohol; Perchlorates; Complexes; Protonation constant; Lanthanide ion; Sodium; Ionic strength; Alkanol; Chemical properties; pK
• ISSN: 0095-9782; 1572-8927
• DOI: 10.1007/s10953-012-9798-3

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 (p K ) of diazepam.