Collect. Czech. Chem. Commun. 1991, 56, 2791-2799

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

Juan A. Squellaa, Luis J. Nuñez-Vergaraa, Hernan Rodrígueza, Amelia Márqueza, Jose M. Rodríguez-Melladob, Manuel Blázquezb, Emilio Roldán and Manuel Dominguezc,*

a Facultad de Ciencias Químicas y Farmaceuticas, Universidad de Chile, Chile
b Departamento de Química Física y Termodinámica Aplicada, Universidad de Córdoba, Córdoba, Spain
c Departamento de Química Física, Universidad de Sevilla, 41012 Sevilla, Spain


Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.