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1. Ring-opening yields and auto-oxidation rates of the resulting peroxy radicals from OH-oxidation of α-pinene and β-pinene

   https://doi.org/10.1039/d2ea00133k  

   Lee, Ben H. ; Iyer, Siddharth ; Kurtén, Theo ; Varelas, Jonathan G. ; Luo, Jingyi ; Thomson, Regan J. ; Thornton, Joel A. ( February 2023 , Environmental Science: Atmospheres)

   Atmospheric oxidation of monoterpenes (C₁₀H₁₆) contributes to ambient particle number and mass concentrations due, in part, to the resulting peroxy radicals undergoing auto-oxidation to low-volatility highly oxygenated molecules (HOMs).

    

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2. Heterogeneous Reactions of α-Pinene on Mineral Surfaces: Formation of Organonitrates and α-Pinene Oxidation Products

   https://doi.org/10.1021/acs.jpca.2c02663  

   Hettiarachchi, Eshani ; Grassian, Vicki H. ( June 2022 , The Journal of Physical Chemistry A)
3. Isolating α-Pinene Ozonolysis Pathways Reveals New Insights into Peroxy Radical Chemistry and Secondary Organic Aerosol Formation

   https://doi.org/10.1021/acs.est.1c02107  

   Zhao, Zixu ; Zhang, Wen ; Alexander, Taylor ; Zhang, Xuan ; Martin, David B. ; Zhang, Haofei ( May 2021 , Environmental Science & Technology)

   null (Ed.)
4. α-Pinene-Derived organic coatings on acidic sulfate aerosol impacts secondary organic aerosol formation from isoprene in a box model

   https://doi.org/10.1016/j.atmosenv.2019.06.005  

   Schmedding, Ryan ; Ma, Mutian ; Zhang, Yue ; Farrell, Sara ; Pye, Havala O.T. ; Chen, Yuzhi ; Wang, Chi-tsan ; Rasool, Quazi Z. ; Budisulistiorini, Sri H. ; Ault, Andrew P. ; et al ( September 2019 , Atmospheric Environment)

   null (Ed.)
5. Selective deuteration as a tool for resolving autoxidation mechanisms in α -pinene ozonolysis

   https://doi.org/10.5194/acp-23-4373-2023  

   Meder, Melissa ; Peräkylä, Otso ; Varelas, Jonathan G. ; Luo, Jingyi ; Cai, Runlong ; Zhang, Yanjun ; Kurtén, Theo ; Riva, Matthieu ; Rissanen, Matti ; Geiger, Franz M. ; et al ( January 2023 , Atmospheric Chemistry and Physics)

   Abstract. Highly oxygenated organic molecules (HOMs) from α-pinene ozonolysis have been shown to be significant contributors to secondary organic aerosol (SOA), yet our mechanistic understanding of how the peroxy-radical-driven autoxidation leads to their formation in this system is still limited. The involved isomerisation reactions such as H-atom abstractions followed by O2 additions can take place on sub-second timescales in short-lived intermediates, making the process challenging to study. Similarly, while the end-products and sometimes radical intermediates can be observed using mass spectrometry, their structures remain elusive. Therefore, we propose a method utilising selective deuterations for unveiling the mechanisms of autoxidation, where the HOM products can be used to infer which C atoms have taken part in the isomerisation reactions. This relies on the fact that if a C−D bond is broken due to an abstraction by a peroxy group forming a −OOD hydroperoxide, the D atom will become labile and able to be exchanged with a hydrogen atom in water vapour (H2O), effectively leading to loss of the D atom from the molecule. In this study, we test the applicability of this method using three differently deuterated versions of α-pinene with the newly developed chemical ionisation Orbitrap (CI-Orbitrap) mass spectrometer to inspect the oxidation products. The high mass-resolving power of the Orbitrap is critical, as it allows the unambiguous separation of molecules with a D atom (mD=2.0141) from those with two H atoms (mH2=2.0157). We found that the method worked well, and we could deduce that two of the three tested compounds had lost D atoms during oxidation, suggesting that those deuterated positions were actively involved in the autoxidation process. Surprisingly, the deuterations were not observed to decrease HOM molar yields, as would have been expected due to kinetic isotope effects. This may be an indication that the relevant H (or D) abstractions were fast enough that no competing pathways were of relevance despite slower abstraction rates of the D atom. We show that selective deuteration can be a very useful method for studying autoxidation on a molecular level and likely is not limited to the system of α-pinene ozonolysis tested here.

    

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