Cyclic Volta Metric Study of Alizarin Yellow R and Some Analogous Arylazo Compounds in DMF and in Aqueous Media

The Cyclic Voltammetry (CV) was used to investigate the electrochemical behavior of alizarin yellow R and some analogous arylazo compounds having almost the same central azo group. For this purpose, the substances chosen for the measurements are Alizarin Yellow R (AYR), Eriochrome Black T (EBT) and Sudan II (SUD II). The investigations were carried out at room temperature (298 K) in both aqueous solutions (HClO₄, NaClO₄, KNO₃) and non-aqueous medium (DMF), on the Hanging Mercury Drop Electrode (HMDE) and on the conventional Pt-disc electrode respectively. The CV results of AYR in aqueous solutions are characterized by a trace crossing that appears upon scan reversal, which is relatively rare. The CV experimental data together with their theoretical calculations for all compounds in DMF reveal unexpectedly irreversible radical anion step as a result of cis trans-isomerisation followed by reversible dianion process.