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@ARTICLE{Bohn:22983,
author = {Bohn, B. and Zetzsch, C.},
title = {{K}inetics and mechanism of the reaction of {OH} with the
trimethlbenzenes - experimental evidence for the formation
of adduct isomers},
journal = {Physical Chemistry Chemical Physics},
volume = {14},
issn = {1463-9076},
address = {Cambridge},
publisher = {RSC Publ.},
reportid = {PreJuSER-22983},
pages = {13933 - 13948},
year = {2012},
note = {This work was supported within the joint French-German
research project ATMOCHEM funded by the Deutsche
Forschungsgemeinschaft under grant BO-1580/3-1 and ZE
792/6-1. We thank R. Koch for detecting the triexponential
feature of the decays of OH in the presence of
1,3,5-trimethylbenzene, M. Elend for the GC-analysis of the
liquid reactants, and R. Koch and M. Siese for their efforts
to improve the instrument.},
abstract = {The reversible gas-phase addition of OH radicals to the
trimethylbenzenes was investigated in pulsed experiments
utilizing VUV flash-photolysis resonance-fluorescence of
H(2)O in the temperature range of 275-340 K. Triexponential
OH decays were observed in the presence of the
trimethylbenzenes, indicating the participation of more than
one adduct species. Analytical solutions for the system of
differential equations with two adduct isomers were derived,
and the OH decay curves were evaluated based on this
reaction model. This led to significant improvements of fit
qualities and notable changes in OH rate constants compared
to a previous model with a single adduct species. The
detailed analysis was confined to 1,3,5-trimethylbenzene
where reversible formation of two OH-aromatic ortho- and
ipso-adduct isomers is feasible in accordance with the
extended reaction model. Only after inclusion of additional
isomerization reactions, consistent thermochemical data were
obtained from the fitted rate constants. Reaction enthalpies
of -83 ± 7 kJ mol(-1) and -35 ± 22 kJ mol(-1) were derived
for the formation of one adduct isomer and the isomerization
into the other, respectively. Based on literature data, the
more and less stable adducts were assigned to ipso- and
ortho-adduct isomers, respectively. The potential
isomerization precluded the determination of primary yields
of adduct isomers but formation of the ipso-adduct in any
case is a minor process. For the rate constants of the OH +
1,3,5-trimethylbenzene reaction an Arrhenius expression
k(OH) = 1.32 × 10(-11) cm(3) s(-1) exp(450 ± 50 K/T) was
obtained. Based on the same approach, the rate constants of
the OH reactions with 1,2,3-trimethylbenzene and
1,2,4-trimethylbenzene were derived as k(OH) = 3.61 ×
10(-12) cm(3) s(-1) exp(620 ± 80 K/T) and k(OH) = 2.73 ×
10(-12) cm(3) s(-1) exp(730 ± 70 K/T), respectively.},
keywords = {J (WoSType)},
cin = {IEK-8},
ddc = {540},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {Atmosphäre und Klima},
pid = {G:(DE-Juel1)FUEK491},
shelfmark = {Chemistry, Physical / Physics, Atomic, Molecular $\&$
Chemical},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:22968679},
UT = {WOS:000309140400027},
doi = {10.1039/c2cp42434g},
url = {https://juser.fz-juelich.de/record/22983},
}