Shalaby A. Yasin*

Chemistry Department, Faculty of Science, Benha-University, Benha, Egypt

Received 19 July 2004; accepted in revised form 24 January 2006

The electrochemical behavior of citrazinic acid azo dye derivatives (I-V) was recorded in aqueous buffer solutions containing 10% (v/v) DMF using DC-polarography and cyclic voltammetry. The DC-polarograms displayed one or two reduction waves depending on the nature of substituent and the pH of the electrolyte solution. The reduction process takes place irreversibly and diffusion controlled at the electrode surface through the uptake of four electron/molecules for compound I and eight electron/molecules for each of compounds II-V. The recorded cyclic voltammograms displayed two irreversible cathodic peaks at different pH values. The kinetic parameters of the electrode process such as, an, heterogeneous rate constant (k_s) and activation energy (ΔG^#) were evaluated and discussed from cyclic voltammetry. Also, the electrode reaction mechanism is proposed and discussed. The effect of introducing substituents on the half-wave potential of the reduction process is illustrated. The different thermodynamic parameters such as activation energy (ΔG^#), enthalpy change (ΔH^#) and entropy change (ΔS^#) revealed the endergonic nature of the electrode reaction.

Keywords: citrazinic azo dyes, polarography, cyclic voltammetry, thermodynamic parameters.

Texto complete disponível em PDF

Full text only in PDF format

1.      S. Yamashita, Y. Seyama, N. Ishikawa, Experientia 34 (1979) 472.        [ Links ]

2.      T. Mohamed and S.A. Yasin, Bull. Electrochem. 17(7) (2001) 293.         [ Links ]

3.      M.A. El-Ries, S.M. Abu-El-Wafa, S.M. El-Kousy, J. Pharm. Belg. 43 (1988) 99.        [ Links ]

4.      F.I. Savostina, Labanov and R.G. Ofasova, Koord. Khim. 2 (1976) 1614.        [ Links ]

5.      L.Q. Zhan, Y. Luo, D.D. Song and G.H. Lu, J. AOAC Int. 85(2) (2002) 456.        [ Links ]

6.      P.N. Gupta, Anju Raina, J. Indian Chem. Soc. LXII (1985) 363.        [ Links ]

7.      G. Holleck and L. Holleck, Naturwissen-Chaften 51 (1964) 433; Monatsh. 990 (1964).        [ Links ]

8.      I.M. Issa, R.M. Issa, T.M. Temerk and M.R. Mahmoud, Electrochim. Acta 18 (1973) 139.        [ Links ]

9.      W.U. Malik, R.N. Goyal and R. Jain, Talanta 25 (1978) 111.        [ Links ]

10.    J.M. Starely and R.R. Giles (Eastman Kodak Company) U.S. Pat. 2, 857, 372 (1958).        [ Links ]

11.    Cliag, Chemishes, Industrilelles Laboratorium, Swiss Pat. 222, 727 (1942).        [ Links ]

12.    E.M. Mabrouk, K.M. Killa, A.A. Abd Elfattah and S.A. Yasin, Anal. Lett. 24(2) (1991) 275.        [ Links ]

13.    P. Zuman, The Elucidation of Organic Electrode Processes, p. 28, Academic Press, New York 1969.        [ Links ]

14.    J. Heyrovsky, J. Kuta, Principles of Polarography, p. 61. Academia, Prague 1965.        [ Links ]

15.    L. Meites, Polarographic Techniques, 2^nd ed., Chap. 4, Interscience Publishers, New York (1965).        [ Links ]

16.    Z. Galus, Fundamental of Electrochemical Analysis, Ellis Harwood, Chichester (1976).        [ Links ]

17.    A.J. Bard, L.R. Faulkner, Electrochemical Methods, p. 218, Wiley, New York (1980).        [ Links ]

18.    J. Heyrovsky, “Polarographie”, Springer, Wein, 1941, p. 185.        [ Links ]

19.    I.M. Kolthoff, J. Lingane, Polarography, Vol 1. Theoretical Principles; Instrumentation and Technique, Interscience Publishers, New York (1965).        [ Links ]

20.    Ritchie and W.F. Sager, “Progress in Physical Organic Chemistry”, Vol. 2, Interscience Publishers Inc., p. 334 (1964).        [ Links ]

* Corresponding author. E-mail address: drshalby55@yahoo.com