This title appears in the Scientific Report :
2015
Please use the identifier:
http://dx.doi.org/10.5194/acpd-15-2791-2015 in citations.
Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships
Formation of highly oxidized multifunctional compounds: autoxidation of peroxy radicals formed in the ozonolysis of alkenes – deduced from structure–product relationships
It has been postulated that secondary organic particulate matter plays a pivotal role in the early growth of newly formed particles in forest areas. The recently detected class of extremely low volatile organic compounds (ELVOC) provides the missing organic vapours and possibly contributes a~signifi...
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Personal Name(s): | Mentel, T. F. (Corresponding Author) |
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Springer, M. / Ehn, M. / Kleist, E. / Pullinen, I. / Kurtén, T. / Rissanen, M. / Wahner, A. / Wildt, J. | |
Contributing Institute: |
Troposphäre; IEK-8 Pflanzenwissenschaften; IBG-2 |
Published in: | Atmospheric chemistry and physics / Discussions, 15 (2015) 2, S. 2791 - 2851 |
Imprint: |
Katlenburg-Lindau
EGU
2015
|
DOI: |
10.5194/acpd-15-2791-2015 |
Document Type: |
Journal Article |
Research Program: |
Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) Tropospheric trace substances and their transformation processes Plant Science |
Publikationsportal JuSER |
It has been postulated that secondary organic particulate matter plays a pivotal role in the early growth of newly formed particles in forest areas. The recently detected class of extremely low volatile organic compounds (ELVOC) provides the missing organic vapours and possibly contributes a~significant fraction to atmospheric SOA. ELVOC are highly oxidized multifunctional molecules (HOM), formed by sequential rearrangement of peroxy radicals and subsequent O2 addition. Key for efficiency in early particle growth is that formation of HOM is induced by one attack of the oxidant (here O3) and followed by an autoxidation process involving molecular oxygen. Similar mechanisms were recently observed and predicted by quantum mechanical calculations e.g. for isoprene. To assess the atmospheric importance and therewith the potential generality, it is crucial to understand the formation pathway of HOM.To elucidate the formation path of HOM as well as necessary and sufficient structural prerequisites of their formation we studied homologues series of cycloalkenes in comparison to two monoterpenes. We were able to directly observe highly oxidized multifunctional peroxy radicals with 8 or 10 O-atoms by an Atmospheric Pressure interface High Resolution Time of Flight Mass Spectrometer equipped with a NO3−-Chemical Ionization (CI) source. In case of O3 acting as oxidant the starting peroxy radical is formed on the so called vinylhydroperoxide path. HOM peroxy radicals and their termination reactions with other peroxy radicals, including dimerization, allowed for analysing the observed mass spectra and narrow down the likely formation path. As consequence we propose that HOM are multifunctional percarboxylic acids; with carbonyl-, hydroperoxy-, or hydroxy-groups arising from the termination steps. We figured that aldehyde groups facilitate the initial rearrangement steps. In simple molecules like cyloalkenes autoxidation was limited to both terminal C-atoms and two further C-atoms in the respective α-positions. In more complex molecules containing tertiary H-atoms or small constraint rings even higher oxidation degree were possible, either by simple H-shift of the tertiary H-atom or by initialisation of complex ring-opening reactions. |