% IMPORTANT: The following is UTF-8 encoded. This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.
@ARTICLE{Alarcn:154645,
author = {Alarcón, Paulo and Bohn, Birger and Zetzsch, Cornelius and
Rayez, Marie-Thérèse and Rayez, Jean-Claude},
title = {{R}eversible addition of the {OH} radical to p-cymene in
the gas phase: multiple adduct formation. {P}art 2},
journal = {Physical chemistry, chemical physics},
volume = {16},
issn = {1463-9084},
address = {Cambridge},
publisher = {RSC Publ.},
reportid = {FZJ-2014-03929},
pages = {17315-17326},
year = {2014},
abstract = {A flash photolysis-resonance fluorescence (FP-RF) system
was used to study the p-cymene (PC) + OHreaction at
temperatures between 299 and 349 K in helium. Triexponential
functions were fitted to groups ofobserved OH decay curves
according to a model considering a reversible addition to
form two adducts asthermolabile reservoirs of OH. Compared
to Part 1 of this paper, consideration of a second adduct
stronglyimproved the fits to our measurements, and the rate
constants for the major pathways were optimizedbetween 299
and 349 K. The Arrhenius expression for the rate constant of
the sum of OH addition andH-atom abstraction pathways was
found to be kOH = 1.9 1012 exp[(610 210) K/T] cm3 s1.
Rateconstants of unimolecular decomposition reactions of the
adducts were similar to other aromaticcompounds with the
following Arrhenius expressions: 1 1012 exp[(7600 800) K/T]
s1 for adduct1 and 4 1011 exp[(8000 300) K/T] s1 for adduct
2. Adduct yields increased and decreased withtemperature for
adduct 1 and 2, respectively, but were similar (B0.4) around
room temperature.Equilibrium constants yielded values for
reaction enthalpies and entropies of adduct formations.
Whilefor one adduct reasonable agreement was obtained with
theoretical predictions, there were significantdeviations
for the other adduct. This indicates the presence of more
than two adduct isomers that werenot accounted for in the
reaction model. Quantum chemical calculations (DFT
M06-2X/6-31G(d,p)) andRRKM kinetics were employed with the
aim of clarifying the mechanism of the OH addition to
PC.These calculations show that formation of adducts with OH
in ortho positions to the isopropyl andmethyl substituents
is predominant $(55\%$ and $24\%)$ to those with OH in ipso
positions $(21\%$ and $3\%).A$ large fraction $(490\%)$ of
the ipso-C3H7 adduct is predicted to react by dealkylation
forming p-cresol(in the absence of oxygen) and isopropyl
radicals. These theoretical results agree well with the
interpretationof the experimental results showing that the
two ortho adducts (which appeared as OHreservoirs in the
experiment) have been observed.},
cin = {IEK-8},
ddc = {540},
cid = {I:(DE-Juel1)IEK-8-20101013},
pnm = {233 - Trace gas and aerosol processes in the troposphere
(POF2-233)},
pid = {G:(DE-HGF)POF2-233},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000340353000047},
doi = {10.1039/C4CP02073A},
url = {https://juser.fz-juelich.de/record/154645},
}