Barbiturates, especially phenobarbitone is frequently encountered drug by forensic toxicologist in cases of drugging & poisoning. In the present work, pH titration technique have been employed to study the complexation reaction of barbituric acid and some of its derivatives with copper (II) phenanthroline chelate in 50% (v/v) aqueous – ethanol media at 30° ± 1°C and m = 0.1 M (NaNO3). The stability constants of the resulting complexes when the following ligands have been used as secondary ligand, are: barbituric acid: 9.38; 5,5 - diethylbarbituric acid: 9.89; 5-ethyl-5-phenylbarbituric acid: 9.78; 5,5-diallylbarbituric acid: 9.85. The tentative structures of the complexes have also been suggested.
Barbiturates, Phenanthroline, Stability constants, Chelate, Ligand
