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| Titel |
Study of the kinetics and equilibria of the oligomerization reactions of 2-methylglyceric acid |
| VerfasserIn |
A. W. Birdsall, C. A. Zentner, M. J. Elrod |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 6 ; Nr. 13, no. 6 (2013-03-15), S.3097-3109 |
| Datensatznummer |
250018520
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| Publikation (Nr.) |
 copernicus.org/acp-13-3097-2013.pdf |
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| Zusammenfassung |
| The presence of a variety of chemical species related to the gaseous
precursor isoprene in ambient secondary organic aerosol (SOA) has stimulated
investigations of the nature of SOA-phase chemical processing. Recent work
has demonstrated that 2-methylglyceric acid (2-MG) is an important
isoprene-derived ambient SOA component and atmospheric chamber experiments
have suggested that 2-MG may exist in oligomeric form (as oligoesters) under
conditions of low SOA water content. In order to better understand the
thermodynamic and kinetic parameters of such oligomerization reactions,
nuclear magnetic resonance techniques were used to study the bulk phase
acid-catalyzed aqueous reactions (Fischer esterification) of 2-MG. While the
present results indicate that 2-MG oligoesters are formed in the bulk phase
with similar water content equilibrium dependences as observed in
atmospheric chamber SOA experiments, the acid-catalyzed rate of the Fischer
esterification mechanism may be too slow to rationalize the 2-MG oligoester
production timescales observed in the atmospheric chamber experiments.
Furthermore, it appears that unrealistically high ambient SOA acidities
would also be required for significant 2-MG oligoester content to arise via
Fischer esterification. Therefore, the present results suggest that other,
more kinetically facile, esterification mechanisms may be necessary to
rationalize the existence of 2-MG oligomers in atmospheric chamber-generated
and ambient SOA. |
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