ABSTRACT Ozonation represents a promising mild-condition biorefinery strategy for oxidative valorization of biomass-derived alkenes. However, it suffers from oxidative decomposition, resulting in product loss. A deep understanding of such decomposition is crucial for designing efficient conversion pathways that suppress overoxidation, especially when phenolic compounds are involved. In this study, we systematically screened nearly one hundred monomeric and dimeric phenols and methylated analogs to explore the structure-reactivity relationship during ozonation. We found the substrate structure significantly influenced decomposition reactivity, leading to rate differences exceeding two orders of magnitude. Some phenols are completely inert toward O 3 , while certain non-phenolic derivatives undergo rapid oxidation. Ozonation of para-substituted phenols follows Hammett equation. The decomposition of guaiacol-type phenols selectively yields value-added monomethyl muconates. Among solvents, tetrahydrofurfuryl alcohol exhibits significant stabilizing and protective functions, enhancing product yield and mitigating overoxidation. Integrating methylation pretreatment and tetrahydrofurfuryl alcohol, we achieved the high-yield of methylated vanillin (88%) and methylated syringaldehyde (96%) via ozonation of methylated lignin depolymerization products, showcasing an efficient ozone-based valorization pathway. Collectively, this work provides fundamental insights of ozonation of phenolic derivatives, validates the efficient production of lignin-derived aromatic aldehydes at mild conditions, and highlights the great potential of ozone-based technologies for advanced biorefinery.
Pan et al. (2026) studied this question.