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| Titel |
A group contribution method for estimating the vapour pressures of α-pinene oxidation products |
| VerfasserIn |
M. Capouet, J.-F. Müller |
| 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 ; 6, no. 6 ; Nr. 6, no. 6 (2006-05-08), S.1455-1467 |
| Datensatznummer |
250003816
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| Publikation (Nr.) |
 copernicus.org/acp-6-1455-2006.pdf |
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| Zusammenfassung |
| A prediction method based on group contribution principles is
proposed for estimating the vapour pressure of α-pinene
oxidation products. Temperature dependent contributions are
provided for the following chemical groups: carbonyl, nitrate,
hydroxy, hydroperoxy, acyl peroxy nitrate and carboxy. On the basis
of observed vapour pressure differences between isomers of diols and
dinitrates, a simple refinement is introduced in the method to
account for the influence of substitutions on the vapour pressure
for alcohols and nitrates. The vapour pressures predicted with this
new method have been compared with the predictions from UNIFAC
(Asher et al., 2002). Given the large uncertainties of the vapour
pressure data for the least volatile compounds, further experimental
studies of subcooled vapour pressures of multifunctional compounds
at ambient temperatures are required for better parameterizations.
Among the α-pinene products identified to date, pinic acid
and hydroxy pinonic acid are predicted to be the least volatile
compounds, with estimated vapour pressures of 3×10−6 torr and 6×10−7 torr, respectively. The
vapour pressure of the other primary products range from 10−5 to 10−3 torr, with hydroxy hydroperoxides presenting the
lowest values. Noting that multifunctional carboxylic acids, in
particular pinic acid, are believed to be mostly present as dimers
in laboratory conditions, we suggest that the partial vapour
pressure of the pinic acid dimer should be close to the experimental
subcooled vapour pressure for pinic acid (estimated at ~10−6 torr) due to its large contribution to the total
concentration (dimer+monomer) in experimental conditions. |
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