Electrochemical study of the anodic oxidation of terpinenes at the electrode and by homogeneous redox catalysis

The electrochemical behaviour of α-terpinene, α-phellandrene and γ-terpinene is studied in acetonitrile. Cyclic voltammetry and potentiostatic electrolysis show that the oxidation product is p-cymene and the mechanism is an ECE type, the chemical step being the deprotonation of the cation radical following the first electron transfer. The kinetics of the electrode process are analyzed by means of homogeneous redox catalysis with organic mediators. This leads to the determination of both the standard potential of the terpinene cation radical/parent compound and the deprotonation rate of the corresponding cation radical.