Autoxidation of Organic Compounds in the Atmosphere
Abstract
We present a hypothesis that autoxidation (inter- and intramolecular hydrogen abstraction by peroxy radicals) plays an important role in the oxidation of organic compounds in the atmosphere, particularly organic matter associated with aerosol. In the laboratory, we determine the rate of this process at room temperature for a model system, 3-pentanone. We employ ab initio calculations to investigate H-shifts within a broader group of substituted organic compounds. We show that the rate of abstraction of hydrogen by peroxy radicals is largely determined by the thermochemistry of the nascent alkyl radicals and thus is highly influenced by neighboring substituents. As a result, autoxidation rates increase rapidly as oxygen-containing functional groups (carbonyl, hydroxy, and hydroperoxy) are added to organic compounds. This mechanism is consistent with formation of the multifunctional hydroperoxides and carbonyls often found in atmospheric aerosol particles.
Additional Information
© 2013 American Chemical Society. Received: September 6, 2013; Accepted: September 30, 2013; Published: September 30, 2013. The authors thank NASA (NNX12AC06G) and NSF (AGS-1240604), the Danish Council for Independent Research - Natural Sciences, and the Danish Center for Scientific Computing (DCSC) for their support of this research. Additional information on the instrumental calibration, timeline of 3-PN oxidation products, RO₂ H-shift barriers as a function of the number of atoms in the cyclic transition state, stereoselectivity of the RO₂ H-shift reactions, hydrogen abstraction in 3-pentanone oxidation by OH, and theoretical calculations for additional RO₂ H-shift reactions.Attached Files
Supplemental Material - jz4019207_si_001.pdf
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Additional details
- Eprint ID
- 42636
- DOI
- 10.1021/jz4019207
- Resolver ID
- CaltechAUTHORS:20131121-161549474
- NNX12AC06G
- NASA
- AGS-1240604
- NSF
- Danish Council for Independent Research - Natural Sciences
- Danish Center for Scientific Computing (DCSC)
- Created
-
2013-11-22Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences