Article
Engineering, Environmental
Hongru Shen, Defeng Zhao, Iida Pullinen, Sungah Kang, Luc Vereecken, Hendrik Fuchs, Ismail-Hakki Acir, Ralf Tillmann, Franz Rohrer, Juergen Wildt, Astrid Kiendler-Scharr, Andreas Wahner, Thomas F. Mentel
Summary: The study investigated the formation of gas-phase highly oxygenated organic molecules-organic nitrates (HOM-ON) from NO3-initiated oxidation of beta-pinene in the SAPHIR chamber. Results showed a mean molar yield of HOM-ON at 4.8%, with significant contributions to SOA formation, highlighting the importance of carbonylnitrates in the process.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2021)
Article
Multidisciplinary Sciences
Qindan Zhu, Joshua L. Laughner, Ronald C. Cohen
Summary: The hydroxyl radical (OH) is the most important oxidant on a global and local scale, controlling the removal rate of primary pollutants and triggering the production of ozone. The interannual trends of OH in North American cities show significant variation, with some cities experiencing an increase while others experience a decrease. The variation of OH is linked to the decline of NO2, emphasizing the importance of controlling NOx emissions in regulating ozone pollution in these cities.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Chemistry, Physical
Long Chen, Yu Huang, Yonggang Xue, Zhihui Jia, Wenliang Wang
Summary: The oxidation mechanism of methyl butyl ketone (MBK) initiated by OH radicals and the subsequent transformation of the resulting intermediates were studied using quantum chemical and kinetic modeling methods. The results showed temperature-dependent pathways for H-abstraction and unimolecular degradation of MBK, as well as the enhanced H-shift rates due to the presence of the carbonyl group in the RO2 radicals. Additionally, the reaction with NO was identified as the dominant removal pathway for the RO2 radicals formed from the oxidation of MBK under realistic atmospheric conditions.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Physical
Galib Hasan, Rashid R. Valiev, Vili-Taneli Salo, Theo Kurten
Summary: This study investigates the formation of accretion products in atmospheric aerosol formation through systematic conformational sampling and ISC rate calculations on complex RO·····OR' systems. The research reveals significant differences in ISC rates among different diastereomer pairs, with all systems showing high ISC rates, indicating a competitive process for accretion product formation.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Article
Engineering, Environmental
Varun Kumar, Jay G. Slowik, Urs Baltensperger, Andre S. H. Prevot, David M. Bell
Summary: This study examines the composition and evolution of secondary organic aerosol (SOA) formed by the reactions of aromatic VOCs with OH and NO3 radicals. The results show that the SOA formed by the oxidation of VOCs by OH radicals is dominated by monomers, while the SOA formed by NO3 radicals consists mainly of dimers. The study also highlights the importance of particle-phase reactions in the formation and degradation of SOA. Rating: 8/10
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Engineering, Environmental
Jiumeng Liu, Emma L. D'Ambro, Ben Hwan Lee, Siegfried Schobesberger, David M. Bell, Rahul A. Zaveri, Alla Zelenyuk, Joel A. Thornton, John E. Shilling
Summary: Monoterpene photooxidation plays an important role in the formation of secondary organic aerosols (SOA), and this study investigates the factors influencing SOA yield from alpha-pinene and Delta-3-carene photooxidation. The results show that oxidation conditions, addition of NO, and the molecular structure of volatile organic compounds (VOCs) can all affect SOA formation. The study also reveals that the composition of the photooxidation products and the SOA yield differ between alpha-pinene and Delta-3-carene.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Julia G. Bakker-Arkema, Paul J. Ziemann
Summary: Environmental chamber studies are essential for measuring reaction product yields and secondary organic aerosols formed from the oxidation of volatile organic compounds to develop atmospheric chemistry models. These measurements are challenging due to various potential sources of errors that need careful consideration and mitigation.
ACS EARTH AND SPACE CHEMISTRY
(2021)
Article
Environmental Sciences
Zhezheng Ding, Yayi Yi, Wenxing Wang, Qingzhu Zhang
Summary: Chrysene, a recalcitrant polycyclic aromatic hydrocarbon, undergoes atmospheric degradation initiated by OH radical, generating toxic oxygenated and nitro products. The study reveals the rate constant and atmospheric lifetime of chrysene in reaction with OH radical.
Article
Environmental Sciences
Tam V-T Mai, Hieu T. Nguyen, Lam K. Huynh
Summary: The comprehensive kinetic mechanism of OH-initiated gas-phase oxidation of pyrrole was theoretically reported, revealing competition between OH-addition and direct H-abstraction pathways under different temperature and pressure conditions. The calculated results show that OH-addition is favored at low temperature and high pressure, while direct H-abstraction dominates at high temperature and atmospheric pressure. The study also predicts global rate constants in excellent agreement with laboratory values, recommending the derived kinetic parameters for modeling N-heterocycle-related applications.
Article
Environmental Sciences
Maria de los A. Garavagno, Federico J. Hernandez, Rafael A. Jara-Toro, Genesys Mahecha, Javier A. Barrera, Raul A. Taccone, Gustavo A. Pino
Summary: The degradation process of cyclobutanol by hydroxyl radical under atmospheric conditions was studied, and the reaction mechanism and rate coefficient were determined using experimental and theoretical methods. The identification of reaction products in clean and NOx-contaminated atmospheres was performed, and the atmospheric implications were discussed.
ATMOSPHERIC ENVIRONMENT
(2022)
Article
Environmental Sciences
Xiaoxiao Lin, Xiaofeng Tang, Zuoying Wen, Bo Long, Christa Fittschen, Xuejun Gu, Yanbo Gai, Weijun Zhang
Summary: The oxidation of 1,3,5-trimethylbenzene (1,3,5-TMB) initiated by OH under NOx-free conditions was studied using experimental and theoretical methods. The presence of high mass O-2-bridged bicyclic compounds in the particle phase was observed and confirmed. Theoretical calculations shed light on the mechanism of formation of these bicyclic compounds.
ATMOSPHERIC ENVIRONMENT
(2022)
Article
Chemistry, Physical
Saber Safari Balsini, Abolfazl Shiroudi, Farhad Hatamjafari, Ehsan Zahedi, Khalil Pourshamsian, Ahmad Reza Oliaey
Summary: The degradation of chlorotrifluoroethylene (CTFE) by OH· was studied using density functional theory (DFT). The reaction pathways and rate constants were calculated, and it was found that the reaction with C-beta atom had a higher energy release. The main pathway was the addition of OH· to the beta-carbon, forming a stable species. The subsequent reactions involved the addition of O2 to the OH group, resulting in the formation of stable products in an oxidative atmosphere.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Environmental Sciences
Kumar Sarang, Tobias Otto, Sahir Gagan, Krzysztof Rudzinski, Thomas Schaefer, Martin Brueggemann, Irena Grgic, Adam Kubas, Hartmut Herrmann, Rafal Szmigielski
Summary: Plants under stress emit Green Leaf Volatiles (GLVs), which may clarify uncertainties in secondary organic aerosol (SOA) budget. In this study, we investigated the aqueous photo-oxidation products of three abundant GLVs induced by center dot OH radicals. Advanced mass spectrometry techniques were used to analyze the reaction samples. The results suggest the potential formation of aqueous SOA and provide insight into the formation mechanism and structures of the identified oxidation products.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Chemistry, Multidisciplinary
Thomas Golin Almeida, Theo Kurten
Summary: The reaction mechanism and fate of cyclic imine 1,2,3,6-tetrahydropyrazine (THPyz) upon oxidation by OH radicals were studied using quantum chemistry and theoretical kinetics methods. The major reaction steps involve H-abstraction from a carbon adjacent to the amine nitrogen, leading to the formation of a second imine function. The calculated yields of potentially hazardous products are low but non-negligible. Additionally, it was found that the aminyl radical formed from OH radical addition to the imine carbon undergoes C-C bond scission, leading to the formation of an imidic acid. These findings are important for understanding the oxidative processes of THPyz and similar compounds in the atmosphere.
ACS EARTH AND SPACE CHEMISTRY
(2022)
Article
Chemistry, Organic
Xian Wu, Chengli Xiang, Jin-Tao Yu
Summary: A visible-light induced radical 1,2-aryl migration of α,α-diarylallyl alcohols was developed using commercially available CHCl3 and CH2Cl2 as tri- and dichloromethyl radical precursors under mild and metal-free conditions. This reaction provided structurally diverse β-polochloromethylated ketones in good to moderate yields through neophyl-type rearrangement, and the polychloromethyl group could be easily transformed into other useful functional groups.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)