Study of the BHT Oxidation Mechanism Coupling Theory and Experiment

In the present work, the oxidation mechanism of di-t-butyl-hydroxytoluene (BHT) was studied in an aqueous medium
through
different approaches to have a thorough vision of the physical chemistry:
experiments with cyclic voltammetry (CV), quantum chemical calculations,
and simulations of CV. Calculations of thermodynamic parameters, such
as pKa and standard oxidation potential
(Eox°), were used to analyze and
rationalize the CV experiments. Subsequently, different pathways of
the mechanism were constructed, and the most thermodynamically favorable
one was selected. Numerical simulations were then used to model this
mechanism and compare it with the experimental data. The results show
that the oxidation process is due to the coupled loss of an electron
and a proton in the first instance, followed by an irreversible second
electron-transfer process without loss of protons, mainly due to the
adsorption of the products of the first oxidation on the electrode
surface. The effect of different pH values on this oxidative mechanism
was also analyzed, with alkaline pH of 12 as a medium where changes
in reactivity were observed as the appearance of a new peak in the
second voltammetric sweep, the interpretation of this peak is also
provided.