Advances in Computational Simulation of Autoxidation Reactions of Atmospheric Peroxyalkyl Radicals
Volatile organic compounds (VOCs) are key precursors of secondary organic aerosols (SOA), and their oxidation reactions are regulated by reactive intermediates. A deep understanding of the reaction mechanisms of VOCs-derived reactive intermediates is crucial for evaluating SOA formation. Atmospheric peroxyalkyl radicals (RO2·) are important intermediates produced during VOCs oxidation and can generate highly oxygenated organic molecules (HOMs) through a unique atmospheric autoxidation mechanism, contributing significantly to SOA formation. This article reviews recent advances in computational studies on the autoxidation mechanisms of RO2· with different functional groups, focusing on the autoxidation reactions of RO2· derived from alkanes, alkenes, carbonyl compounds, aromatic hydrocarbons, heteroatom-containing compounds, and other substances. The review highlights the commonalities and differences in autoxidation mechanisms across these functional groups, emphasizing the role of intramolecular hydrogen shifts and subsequent O2 addition steps. Furthermore, we emphasize that future research should focus on the autoxidation of second-generation RO2· and autoxidation mechanisms driven by different intramolecular reactions. Quantum chemical calculations, often combined with kinetic modeling, provide molecular-level insights into reaction pathways and rate constants, which are essential for predicting HOM formation and SOA yields. This review aims to guide further theoretical investigations and support the development of more accurate atmospheric chemistry models.