スチレン由来エアロゾル生成を促進する多世代酸化経路を解明（Study Unravels Multi-Generation Oxidation Pathways Driving Styrene-Derived Aerosol Formation）

2026-05-29 中国科学院（CAS）

＜関連情報＞

• https://english.cas.cn/newsroom/research-news/202605/t20260529_1160177.shtml
• https://acp.copernicus.org/articles/26/4823/2026/

スチレンの多世代● OH酸化による多官能性生成物の生成機構に関する研究 Mechanistic investigations of the formation of multifunctional products from the multi-generation ●OH oxidation of styrene

Long Chen, Yu Huang, Yonggang Xue, Long Cui, and Zhihui Jia
Atmospheric Chemistry and Physics  Published:13 Apr 2026
DOI:https://doi.org/10.5194/acp-26-4823-2026

Abstract

Styrene is a highly reactive aromatic hydrocarbon that has been identified as a key secondary organic aerosol (SOA) precursor. Recent laboratory chamber experiments have identified C₇ and C₈ series compounds as the main components of SOA in the photooxidation of styrene. However, their molecular structures and formation pathways remain largely uncharacterized. Herein, the formation mechanisms of multifunctional products from the multi-generation •OH oxidation of styrene are studied using the quantum chemistry methods. The calculations show that the first generation RO₂ radicals can either proceed unimolecular decomposition to yield benzaldehyde (C₇H₆O), or undergo bimolecular reactions with HO₂•/NO to form the first generation closed-shell C₇– and C₈-products, hydroperoxide 1st-ROOH (C₈H₁₀O₃), benzaldehyde, and organic nitrate 1st-RONO₂ (C₈H₉NO₃). For the second generation •OH oxidation, OH-addition reaction occurring at the ortho-site of 1st-ROOH and 1st-RONO₂ has a significant dominance. The ortho-OH-addition products can proceed through two O₂-addition steps and a cyclization process to produce the peroxide bicyclic peroxy radicals (BPR). BPR can further react with HO₂•/NO to form the second generation closed-shell C₈-products, hydroperoxide 2nd-ROOH (C₈H₁₂O₈), organic nitrate 2nd-RONO₂ (C₈H₁₀N₂O₁₀), and other multifunctional products, in which the first two products have fractional yields of 41.4 % and 4.8 %, respectively. For the third generation •OH oxidation, OH-addition occurring at the C=C double bond of 2nd-ROOH and 2nd-RONO₂ has the lowest barrier. The major third generation closed-shell C₈-products are the multifunctional hydroperoxides and organic nitrates. These findings carry important implications for advancing our understanding of the chemical composition and formation mechanisms of aromatic SOA.