Theoretical Insights into the Reaction Mechanism between 2,3,7,8-Tetrachlorodibenzofuran and Hydrogen Peroxide: A DFT Study.

A detailed knowledge of the reactivity of 2,3,7,8-tetrachlorodibenzofuran (TCDF) at the molecular level is important to better understand the transformation of dioxins analogous to TCDF in the environment. To clarify the reactivity of the organic hydroperoxides toward TCDF, the reaction of the TCDF with hydrogen peroxide (HO) and its anion has been investigated theoretically. For the reaction of the neutral HO, a molecular complex can be formed between TCDF and HO first. Then, the nucleophilic aromatic substitution of TCDF by HO occurs in the presence of the water molecules to form an intermediate containing an O-O bond. Finally, the O-O bond cleavages homolytically for the above intermediate. On the other hand, as for the reaction of the anion of HO (HO ), the nucleophilic addition of HO to TCDF can also occur besides the nucleophilic aromatic substitution reaction mentioned above, resulting in the dissociation of the C-O bond of TCDF. Unlike the reaction involving neutral HO, no water molecules are required. In addition, the selected substitution effects, such as F-, Br-, and CH-substituents, on the reactivity of the above reaction have also been explored. Hopefully, the present results can enable us to gain insights into the reactivity of the organic hydroperoxides with TCDF-like environmental pollutants.