In recent years, significant ozone concentrations have been noted in the interior of a number of states in the Arabian peninsula, including Saudi Arabia and the United Arab Emirates: S. Osipov et al., Severe atmospheric pollution in the Middle East is attributable to anthropogenic sources. COMMUNICATIONS EARTH & ENVIRONMENT (2022) 3:203 |https://doi.org/10.1038/s43247-022-00514-6. This phenomenon is not new: Lelieveld, J. et al. Severe ozone air pollution in the Persian Gulf region. Atmos. Chem. Phys. 9, 1393–1406 (2009) and continues to persist.
At the same time, our laboratory at UAEU was surprised to note that organic substances exposed (open at rt) to the lab environment tended to oxidize more quickly than in previous lab environments that I had come to know from before. One such oxidative transformation was the reaction of a series of substituted dibenzyl ethers to the corresponding phenyl benzoates. We had first imagined this to progress through an auto-oxidation of the dibenzyl ethers: Rieche, A.; Meister, R. Modellversuche zur Autoyxdation der Äther, Angew. Chem., 1936, 49, 101 – 103. However, a further pathway may be possible that involves ozone as oxidant: P. Angibeaud, J. Defaye, A. Gadelle, J.-P. Utille, Synthesis, 1985, 1123-1125.
At the same time, we have been aware of the rapid oxidative degradation of polythene and polypropylene objects out in the open environment (ambient temperature under sun irradiation; eg., Al Kaabi, M., Poulose, V. and Thiemann, T. (2025) Oxidative Degradation of Plastic Bottle Tops in an Arid, Terrestrial Environment—Identifying Oxidative Degradation by Infrared Spectroscopy. Journal of Environmental Protection, 16, 66-86). While we realize that high temperatures and significant UV irradiation play a role in the rapid degradation, we were never convinced that only diatomic oxygen is reponsible for the first step of polythene / polypropylene chain oxidation.
Therefore, the question: does anybody know of studies on the action of ozone on polythene and/or polypropylene, either photochemically or thermally run.
Dear Professor: Thies Thiemann
Thank you for sharing your recent observations—your exploration into the oxidative effects of ozone is both timely and thought-provoking. The distinction between ozone and molecular oxygen as oxidizing agents, especially in the context of polymer degradation and the oxidation of organic compounds like dibenzyl ethers, certainly opens up intriguing avenues for discussion.
When considering ozone’s interaction with alkanes or saturated polymers such as polyethylene and polypropylene, it’s worth noting that ozone’s higher reactivity could enable unique reaction pathways compared to oxygen. For instance, ozone may facilitate direct cleavage of C–H or C–C bonds, potentially leading to more rapid or extensive degradation. Factors such as temperature, UV irradiation, and the presence of catalysts can further modulate these mechanisms, possibly accelerating oxidation rates in environments with elevated ozone levels—like those observed in the Arabian Peninsula.
Regarding your question about comparative studies, there is a body of research examining the environmental degradation of polymers under various oxidative conditions. It might be beneficial to review literature focusing on controlled experiments that isolate ozone’s effects versus oxygen alone, particularly under high-temperature or UV-irradiated scenarios. Such studies could provide valuable insights into the specific pathways and rates of degradation.
On a practical note, if ozone is indeed a significant driver of rapid oxidation, this could have important implications for both material preservation and experimental design. Adjusting storage conditions, employing protective coatings, or modifying experimental protocols might become necessary to mitigate unwanted degradation.
I’d be interested to hear your thoughts on potential next steps for investigation, or if you’ve come across any particularly relevant studies. Please let me know if you’d like to discuss this further or collaborate on a literature review.
Some important articles to read:
Article Formation of atmospheric nitrate under high Particulate Matt...
Article Clean Air and Environmental Quality, 38, No. 4, 37-41, Novem...
Article Atmospheric Environment, 37, 2003, 2005-2013, Investigations...
Best regards,
Kaushik
Dear Dr. Kaushik Shandilya ,
thank you for your response and your nice papers that you have added.
You had mentioned that ozone cleaves C-C and C-H bonds readily. Do you have any papers regarding those studies?
With my best wishes,
Thies
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