Formation of dibenzofuran, dibenzo-p-dioxin and their hydroxylated derivatives from catechol

Mohammednoor Altarawneh, Bogdan Z. Dlugogorski

Research output: Contribution to journalArticle

Abstract

We present, in this study, mechanistic and kinetic accounts of the formation of dibenzofuran (DF), dibenzo-p-dioxin (DD) and their hydroxylated derivatives (OHs-DF/OHs-DD) from the catechol (CT) molecule, as a model compound for phenolic constituents in biomass. Self-condensation of two CT molecules produces predominantly a DD molecule via open- and closed-shell corridors. Coupling modes involving the o-semiquinone radical and the CT molecule (o-SQ/CT) generate two direct structural blocks for the formation of OHs-DF/OHs-DD structures, ether-type intermediates and di-keto moieties. The calculated reaction rate constants indicate that the fate of ether-type intermediates is to make hydroxylated diphenyl ethers rather than to undergo cyclisation reactions leading to the formation of preDF structures. Unimolecular loss of a H or OH moiety from a pivotal carbon in these hydroxylated diphenyl ethers then produces hydroxylated and non-hydroxylated DD molecules. Formation of OHs-DF initiated by o(C)-o(C) cross-linkages involving o-SQ/o-SQ and o-SQ/CT reactions incurs very similar reaction and activation enthalpies encountered in the formation of chlorinated DFs from chlorophenols.

Original languageEnglish
Pages (from-to)1822-1830
Number of pages9
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number3
Early online date21 Nov 2014
DOIs
Publication statusPublished - 21 Jan 2015
Externally publishedYes

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