caa a22 4500 467919852 CHVBK 20180406152913.0 cr unu---uuuuu 170328e20060301xx s 000 0 eng 10.1007/s00706-005-0447-z doi (NATIONALLICENCE)springer-10.1007/s00706-005-0447-z Voltammetric, Potentiometric and Spectrophotometric Studies of Some Hydrazones and Their Metal Complexes in Ethanolic-Aqueous Buffered Solutions [Elektronische Daten] [Mohammed M. Ghoneim, Ibrahim S. El-Hallag, Kamal Y. El-Baradie, Hanaa S. El-Desoky, Mona A. El-Attar] Summary.: The electrochemical behavior of some hydrazones derived from 6-chloro-2-hydrazinopyridine in the Britton-Robinson universal buffer of pH 2-11 containing 35% ethanol was investigated at the mercury electrode using dc-polarography, controlled-potential coulometry, and cyclic voltammetry techniques. The examined hydrazones were reduced in solutions of pH < 9 in a single 4-electron diffusion-controlled irreversible step corresponding to both the saturation of -N=C< double bond and cleavage of the -HN-NH- single bond of the hydrazone molecule via the consumption of two electrons for each center. Whereas the starting compound, 6-chloro-2-hydrazinopyridine, was reduced in a single 2-electron diffusion-controlled irreversible step corresponding to cleavage of its -NH-NH2 single bond. The mechanistic pathway of the electrode reaction of the studied compounds was elucidated and discussed. The pKa values of the examined hydrazones and the stoichiometry of their complexes in solution with some transition metal ions were determined spectrophotometrically. The dissociation constants and the thermodynamic parameters of the investigated hydrazones, and the stability constants of their metal complexes in solution were determined potentiometrically. Springer-Verlag/Wien, 2006 Keywords. Hydrazones nationallicence 6-Chloro-2-hydrazinopyridine nationallicence Polarography nationallicence Coulometry nationallicence Cyclic voltammetry nationallicence Ghoneim Mohammed M. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut El-Hallag Ibrahim S. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut El-Baradie Kamal Y. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut El-Desoky Hanaa S. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut El-Attar Mona A. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut Monatshefte für Chemie / Chemical Monthly Springer-Verlag 137/3(2006-03-01), 285-299 0026-9247 137:3<285 2006 137 706 https://doi.org/10.1007/s00706-005-0447-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00706-005-0447-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ghoneim Mohammed M. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut NATIONALLICENCE 700 1- El-Hallag Ibrahim S. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut NATIONALLICENCE 700 1- El-Baradie Kamal Y. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut NATIONALLICENCE 700 1- El-Desoky Hanaa S. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut NATIONALLICENCE 700 1- El-Attar Mona A. Chemistry Department, Faculty of Science, Tanta University, 31527, Tanta, Egypt aut NATIONALLICENCE 773 0- Monatshefte für Chemie / Chemical Monthly Springer-Verlag 137/3(2006-03-01), 285-299 0026-9247 137:3<285 2006 137 706 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer