Atmospheric Fate of Methacrolein. 1. Peroxy Radical Isomerization Following Addition of OH and O_2
Abstract
Peroxy radicals formed by addition of OH and O_2 to the olefinic carbon atoms in methacrolein react with NO to form methacrolein hydroxy nitrate and hydroxyacetone. We observe that the ratio of these two compounds, however, unexpectedly decreases as the lifetime of the peroxy radical increases. We propose that this results from an isomerization involving the 1,4-H-shift of the aldehydic hydrogen atom to the peroxy group. The inferred rate (0.5 ± 0.3 s^(–1) at T = 296 K) is consistent with estimates obtained from the potential energy surface determined by high level quantum calculations. The product, a hydroxy hydroperoxy carbonyl radical, decomposes rapidly, producing hydroxyacetone and re-forming OH. Simulations using a global chemical transport model suggest that most of the methacrolein hydroxy peroxy radicals formed in the atmosphere undergo isomerization and decomposition.
Additional Information
© 2012 American Chemical Society. Received: December 1, 2011; Revised: March 12, 2012; Published: March 27, 2012. We thank N. C. Eddingsaas for the design and construction of the chamber used in this work, M. R. Beaver for assistance with experiments, J. M. St. Clair for instrumental assistance, and K. M. Spencer for providing CIMS calibrations of glycolaldehyde and hydroxyacetone. We thank J. Peeters for helpful initial discussions regarding the feasibility of the 1,4-H-shift of MACR-1-OH-2-OO. We thank NASA (NNX08AD29G) and NSF (ATM-0934408), the Danish Council for Independent Research - Natural Sciences, and the Danish Center for Scientific Computing (DCSC) for funding. F.P. acknowledges support from NASA earth and space science fellowship.Attached Files
Supplemental Material - jp211560u_si_001.pdf
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Additional details
- Eprint ID
- 32419
- Resolver ID
- CaltechAUTHORS:20120713-101645825
- NASA
- NNX08AD29G
- NSF
- ATM-0934408
- Danish Council for Independent Research Natural Sciences
- Danish Center for Scientific Computing (DCSC)
- NASA Earth and Space Science Fellowship
- Created
-
2012-07-13Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences