Electrochemical reduction processes on glassy carbon electrode of 2- Amino-4-phenylthiazoles

Abstract

In this work the electrochemical reduction of the compounds 2-Amino-4-(4-R-phenyl)thiazoles (1a, R = -H and 1b, R = -NHCOCH3) was performed by cyclic voltammetry in dimethylsulfoxide (DMSO) + 0,1 M tetraethylammonium tetrafluoroborate (TEABF4) and tetrabutylammonium hexafluorophosphate (TBAPF6). Two reduction signal were observed, the Ic wave (EpIc = -2.52 V) and wave IIc (EpIIc = -2.77 V) due to an electron transfer of the electrogenerated product in the Ic wave. The change of substituent influences the electrochemical behaviour, showing that an electrodonating substituent causes a higher energy requirement for the reduction of 1b, which became evident in the more negative potential, with respect to 1a. Additionally, it was observed that the peak potential in the first reduction signal Ic wave shifted to more negative values as the potential sweep rate was higher and this was indicative of an irreversible behaviour. A larger salt such as TBAPF6 causes a decrease in the intensity of peak reduction currents, contrary to what was shown by a smaller salt such as TEABF4. Also for both compounds, the cathodic peak potential of wave Ic and IIc is influenced by the effect of the size of salt used. A smaller salt favoured the electrochemical reduction of both heterocyclic compounds.