Oxidation of catechol to muconic acid: A theoretical study

The oxidation reaction of catechol to cis-cis muconic acid was studied with the B3LYP density functional and the 6-311G** basis set to explore the singlet and triplet potential surfaces. The singlet potential surface was treated with the broken symmetry formalism, and the stability of the wave function was confirmed. The calculations indicate that, in absence of catalyst, the reaction must undergo photo-excitation in order to promote the system to the singlet potential surface, which leads to a lower-lying transition state and the final products. Oxidation is a two step process; the singlet transition state is peroxide-like, while that of the triplet state involves a cyclic structure. Intermediates along the triplet surface lie at substantially higher energy.