Newland, Michael, Rea, Gerard, Thuner, Lars et al. (5 more authors) (2019) Photochemistry of 2-butenedial and 4-oxo-2-pentenal under atmospheric boundary layer conditions. Physical Chemistry Chemical Physics. pp. 1160-1171. ISSN 1463-9084
Abstract
Unsaturated 1,4-dicarbonyl compounds, such as 2-butenedial and 4-oxo-2-pentenal are produced in the atmospheric boundary layer from the oxidation of aromatic compounds and furans. These species are expected to undergo rapid photochemical processing, affecting atmospheric composition. In this study, the photochemistry of (E)-2-butenedial and both E and Z isomers of 4-oxo-2- pentenal was investigated under natural sunlight conditions at the large outdoor atmospheric simulation chamber EUPHORE. Photochemical loss rates, relative to j(NO2), are determined to be j((E)-2-butenedial)/j(NO2) = 0.14 (0.02), j((E)-4-oxo-2-pentenal)/j(NO2) = 0.18 (0.01), and j((Z)-4-oxo-2-pentenal)/j(NO2) = 0.20 (0.03). The major products detected for both species are a furanone (30 – 42%) and, for (E)-2-butenedial, maleic anhydride (2,5-furandione) (12 – 14%). The mechanism appears to proceed predominantly via photoisomerization to a ketene- enol species following -H abstraction. The lifetimes of the ketene-enol species in the dark from 2-butenedial and 4-oxo-2-pentenal are determined to be 465 s and 235 s, respectively. The ketene-enol can undergo ring closure to yield the corresponding furanone, or further unimolecular rearrangement which can subsequently form maleic anhydride. A minor channel (10 – 15%) also appears to form CO directly. This is presumed to be via a molecular elimination route of an initial biradical intermediate formed in photolysis, with an unsaturated carbonyl (detected here but not quantified) as co-product. -dicarbonyl and radical yields are very low, which has implications for ozone production from the photo-oxidation of unsaturated 1,4-dicarbonyls in the boundary layer. Photochemical removal is determined to be the major loss process for these species in the boundary layer with lifetimes of the order of 10 – 15 minutes, compared to > 3 hours for reaction with OH.
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Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © the Owner Societies 2019. This is an author-produced version of the published paper. Uploaded with permission of the publisher/copyright holder. Further copying may not be permitted; contact the publisher for details |
Keywords: | ATMOSPHERIC CHEMISTRY,PHOTOCHEMISTRY,Aromatic photochemistry,Air quality |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Funding Information: | Funder Grant number EUROPEAN COMMISSION 730997 NATURAL ENVIRONMENT RESEARCH COUNCIL NE/M013448/1 |
Depositing User: | Pure (York) |
Date Deposited: | 08 Jan 2019 11:50 |
Last Modified: | 26 Nov 2024 00:41 |
Published Version: | https://doi.org/10.1039/c8cp06437g |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1039/c8cp06437g |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:140766 |
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Description: Unsat. 1,4 dicarbs photolysis_19.12.18