Potentiometric Studies on Some 6- Amino 2- Pyridyl Azo Dyes and Their Chelates

Nadia A. Abdalla, Th. I. El-Desoky, A. H. Amrallah and F. W. Hassan

Chemistry Department, Faculty of Science, Aswan (Egypt)

Potentiometric titrations of the system Cu(II),Ni(II),Co(II) and Zn(II) with 6-amino-2-pyridyl azo compounds (L1-L4) againsts carbonate free NaOH reveal that as the pH of the system is raised the two inflection before the acid curve, these are due to the the protonation of nitrogen atom in pyridine ring and the protonation of nitrogen atom in amino group while the second two inflections after the acid curve these are due to the deprotonation of p-OH,-COOH and o-OH in phenyl ring. The formation constants of the binary complexes were determined. The order of stabilities is Cu(II) >Ni(II) > Co(II) >Zn(II). The species distribution diagrams of the metal complex species was discussed.

6-amino 2-pyridyl azo dyes; chelates