The electrochemical behaviour of 2′-halogenated derivatives of 4-methoxyazobenzene at a mercury electrode

The electrochemical behaviour of 2′-halogenated-4-methoxyazobenzene derivatives were investigated using both polarographic and voltammetric methods. The number of electrons transferred, standard rate constant and diffusion coefficient were evaluated. The standard rate constant was determined using either a Laviron technique or Nicholson and Klingler–Kochi technique. Diffusion coefficients were calculated from cyclic voltammetric data using the method developed by Garrido. The adsorption and transfer coefficients of electron transfer were determined using chronocoulometry and constant-potential coulometry, respectively. The number of electrons transferred was found to be 4 (pH < 4) and 2 (pH > 4) for all derivatives studied. The compounds could be determined quantitatively at between 5 × 10−5 M and 5 × 10−7 M using sampled current polarography, differential pulse polarography and cyclic voltammetry.