An Experimental and Computational Study of the Kinetics and Mechanism of the Reaction of Methyl Formate with Cl Atoms

Article abstract of DOI:10.1021/jp992478z

Ab initio molecular orbital theory has been used to examine the kinetics and mechanism for the reaction of chlorine atoms with methyl formate. From the ab initio parameters, the room-temperature rate constant is calculated and found to be in reasonable agreement with the experimental determination. It is found that 90% of the reaction proceeds via abstraction of the carbonyl hydrogen from methyl formate by chlorine atoms, resulting in the formation of CH₃OCO radical.

Full text of DOI:10.1021/jp992478z

J. Phys. Chem. A 2000, 104, 1505-1511
1505
An Experimental and Computational Study of the Kinetics and Mechanism of the Reaction
of Methyl Formate with Cl Atoms
David A. Good, Jaron Hansen, Mike Kamoboures, Randy Santiono, and Joseph S. Francisco*
Department of Chemistry and Department of Earth and Atmospheric Science, Purdue UniVersity,
West Lafayette, Indiana 47907-1393
ReceiVed: July 20, 1999; In Final Form: October 29, 1999
Ab initio molecular orbital theory has been used to examine the kinetics and mechanism for the reaction of
chlorine atoms with methyl formate. From the ab initio parameters, the room-temperature rate constant is
calculated and found to be in reasonable agreement with the experimental determination. It is found that 90%
of the reaction proceeds via abstraction of the carbonyl hydrogen from methyl formate by chlorine atoms,
resulting in the formation of CH3OCO radical.
I. Introduction
allowed to equilibrate for over 1 h. Chlorine was photolyzed
from the output of a Xenon arc lamp. A 330 nm cutoff filter
was used to limit the amount of UV light that entered the cell
and thus decrease the potential for photolysis side reactions.
The reaction progress was monitored via FTIR spectroscopy
using a Matteson Instruments Galaxy 7020 series spectrometer.
The spectrometer was operated in the mid-IR at 1 cm-1
resolution with an 18 cm path length. The resulting spectra are
the average of 64 replicate scans. As a test of the effectiveness
of the cutoff filter at limiting photolysis side reactions, methyl
formate was radiated in the presence of all reactants except
chlorine. No appreciable loss of methyl formate was found over
the time period of typical experiments. Methyl formate (99.9%)
was purchased from Aldrich and was subjected to several
freeze-pump-thaw cycles prior to use. No impurities were
detected using FTIR and GC/MS. Ultrahigh purity oxygen
(99.99%) was purchased from AGA Speciality Gases, while
ultrahigh purity chlorine (99.97%) was purchased from Scott
Specialty Gases. Both reagents were used without further
purification. Typical experimental conditions consist of 500
mTorr of CH3OCOH, 500 mTorr of Cl2 and 20 Torr of O2.
B. Computational Methods. All calculations were per-
formed with the GAUSSIAN 94 package of programs.8 Geom-
etry optimizations for all species were carried out for all
structures to better than 0.001 Å for bond lengths and 0.1° for
angles. The geometries were fully optimized, and with these
geometries a frequency calculation was performed. Optimiza-
tions and frequency calculations were performed using the
second-order Moller-Plessant perturbation method (MP2) with
the 6-311++G(2d,2p) basis set. In addition, single-point ener-
gies were calculated using the QCISD(T) method with the same
basis set. Restricted wave functions were used for closed-shell
and unrestricted wave functions for open-shell systems with all
orbitals active. For each species, the degree of spin contamina-
tion was monitored. For doublet systems, the s2 value did not
exceed 0.78, thus indicating that the wave functions were not
significantly contaminated by higher order spin states. To obtain
the energy at 298 K, the thermal energy of each species was
added to its total energy instead of the zero-point energy (ZPE).
Usually vibrational frequencies calculated at the MP2 level are
found to overestimate experimental anharmonic frequencies and
thus zero-point energies. To correct for this overestimation, a
popular approach has been to scale the ZPE. The vibrational
Concerns about mobile source emissions and their impact on
urban tropospheric ozone formation have spurred research into
alternative fuels with the goal of reducing emissions of CO and
NOx. Fuel composition affects the tendency of a fuel to form
soot particulates and NOx. Increasing the carbon-to-hydrogen
ratio or the number of carbon-carbon bonds increases the
tendency of a fuel to form soot. Oxygenated hydrocarbons such
as ethers can be added to fuels to maintain performance while
lowering tailpipe emissions of CO.1 Dimethyl ether (DME) is
a fuel anti-knock agent and proposed diesel fuel substitute. DME
has been used as a methanol ignition improver in diesel engines,
where it has been reported to reduce hydrocarbon emissions.1
Some of its attractive features include low self-ignition tem-
perature, low octane number (high cetane number, 55-60), and
reduced combustion noise, particle emission, and NOx emissions.
DME fueled engines are nonsooting, and DME can be economi-
cally produced from a one-step synthesis.1 The atmospheric
oxidation of DME has been studied by Japar et al.,2 Jenkin et
al.,3 Wallington et al.,4 Langer et al.,5 and Sehested et al.6,7
Japar et al.2 used Cl• atom initiated hydrogen abstraction to
simulate the reaction of DME with tropospheric OH radical in
the presence of NO. Reaction products were determined using
FTIR spectroscopy. The production of methyl formate ac-
companied the loss of dimethyl ether quantitatively. The yield
of methyl formate relative to DME loss was found to be 0.90.2
To the best of our knowledge, the resulting fate of methyl
formate has not been studied. This work addresses the atmo-
spheric oxidation of methyl formate. Figure 1 shows a proposed
mechanism for the atmospheric oxidation of methyl formate.
The first step is a hydrogen abstraction reaction initiated by
chlorine atom. As shown there are two possible reaction
pathways, hydrogen abstraction of one of the methyl hydrogens
or hydrogen abstraction of the carbonyl hydrogen. It is a goal
of this work to determine the branching ratio for this step.
II. Methods
A. Experimental Methods. Gas mixtures of chlorine,
oxygen, and methyl formate were introduced into a 64 cm3
square Teflon reaction vessel at various concentrations. Gas
pressures were monitored using a MKS baritron capacitance
manometer which is accurate to (0.01 Torr. The mixture was
10.1021/jp992478z CCC: $19.00 © 2000 American Chemical Society
Published on Web 02/02/2000

1506 J. Phys. Chem. A, Vol. 104, No. 7, 2000
Good et al.
Figure 1. Proposed methyl formate oxidation mechanism.
TABLE 1: Relative Rates for Methyl Formate Reaction
with Chlorine Atomsa
frequencies and ZPE values used in this work have been scaled
by the recommended value of 0.97.28
reference
species
kr reference
reaction with Cl
km methyl formate
reaction with Cl
kr/km
Results and Discussion
CH3F
(3.5 ( 1.3) × 10-13 0.22 ( 0.01 (1.60 ( 0.58) × 10-12
A. Relative Rate Method For Rate Constant Measure-
ment. To calibrate our experimental method, we measured the
rate of Cl reaction with methyl formate using a relative rate
technique. In this experiment, mixtures of methyl formate (∼0.5
Torr), reference gas (CH2Cl2, CH3F, CH2F2; ∼2 Torr), and Cl2
(excess) were allowed to equilibrate for 1 h. The mixture was
illuminated at wavelengths > 330 nm to produce chlorine
radicals and initiate the reaction. The reactant concentrations
were monitored using FTIR spectroscopy by observing the
decrease in intensity of one of their spectral features. The rate
for chlorine atom reaction with methyl formate was measured
relative to CH3F, CH2Cl2, and CH2F2. For CH3F, the recom-
mended9 reaction rate is 3.5 ( 1.3 × 10-13 cm3 molecule-1
s-1 which comes from the work of Tschuikow-Roux et al.,10
Tuazon et al.,11 Wallington et al.,12 and Manning et al.13 For
CH2Cl2, the recommended value of 3.3 ( 1.3 × 10-13 cm3
molecule-1 s-1 is derived from the relative rate work of
Tschuikow-Roux et al.,11 as recommended by the JPL publica-
tion.9 This work shows good agreement with the direct
measurements of Niki et al.14 and Beichert et al.15 CH2F2 is the
slowest species of the three to react with chlorine, having a
CH2Cl2 (3.3 ( 1.3) × 10-13 0.23 ( 0.01 (1.43 ( 0.67) × 10-12
CH2F2
average
(7.0 ( 2.1) × 10-14 0.06 ( 0.001 (1.17 ( 0.33) × 10-12
(1.4 ( 0.5) × 10-12
a All rate data at 298 K. All rate constants in units of cm3 molecule-1
s-1
.
recommended reaction rate of 7.0 ( 2.1 × 10-14 cm3 molecule-1
s-1 based on the work of Tschuikow-Roux et al.9,26 The 298 K
rate constant for reaction of Cl atoms with each of the above
reference species is listed in Table 1, column 2. All reference
reagents were found to react slower than methyl formate with
chlorine. Example experiments from a set of three replicate
determinations are shown in Figure 2. The relative rate of the
reference species reacting with chlorine to that of methyl formate
reacting with chlorine, kr/km, is listed in Table 1, column 3. The
reported ratio is the average of the three replicates, while
reported errors represent 2σ from the least-squares fit. The rate
constant for reaction of methyl formate with chlorine atoms is
presented in the final column of Table 1. With respect to
dichloromethane, a ratio kCH Cl /kCH OCOH of 0.23 ( 0.01 was
2
2
3
determined. Using a rate constant for CH2Cl2 reaction with

Reaction of Methyl Formate with Cl Atoms
J. Phys. Chem. A, Vol. 104, No. 7, 2000 1507
Figure 2. Relative rates of reference vs methyl formate expressed as kr/km.
chlorine of (3.3 ( 1.3) × 10-13 cm3 molecule-1 s-1, a value
for the rate constant for methyl formate reacting with Cl is found
to be (1.43 ( 0.67) × 10-12 cm3 molecule-1 s-1. For
fluoromethane, a ratio of kCH F/kCH OCOH of 0.22 ( 0.01 was
for FAA is production of formic acid and CO. Kuhne et al.20
determined a time constant for the rearrangement of formic acid
anhydride to formic acid and CO of roughly 1 h. Cl radical
initiated decomposition of formic acid has been studied by
Tyndall et al.21 who determined the primary (∼96%) dissociation
pathway is removal of the carbonyl hydrogen in formic acid to
form the HOCO radical. The HOCO radical reacts with O2 to
yield HO2 and CO2.
3
3
determined thus yielding a methyl formate reaction rate of (1.60
( 0.58) × 10-12 cm3 molecule-1 s-1. For CH2F2, a rate constant
of (1.17 ( 0.33) × 10-12 cm3 molecule-1 s-1 is determined.
These separate determinations yield an average rate constant
of (1.4 ( 0.5) × 10-12 cm3 molecule-1 s-1 for methyl formate
reacting with Cl. Two previous investigators have measured the
rate of methyl formate reaction with chlorine. Wallington et
al.,16 using a relative rate technique, found a rate constant of
(1.4 ( 0.1) × 10-12 cm3 molecule-1 s-1. Recently, Notario et
al.17 used a pulsed laser photolysis-resonance fluorescence
technique to directly measure the 298 K rate constant by
following the loss of chlorine atoms in the presence of methyl
formate. The rate constant was determined to be (1.8 ( 0.2) ×
10-12 cm3 molecule-1 s-1. Our value of (1.4 ( 0.5) × 10-12
cm3 molecule-1 s-1 is in agreement with the measurements of
Wallington et al.16 and Notario et al.17
B. Reaction Products. Figure 3a shows an FTIR spectrum
of methyl formate in the presence of oxygen and chlorine prior
to photolysis and thus only features due to methyl formate are
present. Shortly after photolysis is initiated, absorption features
due to HCl, CO2, and CO are clearly visible. At later times,
features due to formic acid anhydride and formic acid become
evident. For formic acid anhydride, the two CO stretches at 998
and 1105 cm-1 as well as the CdO stretches at 1822 and 1767
cm-1 are present.18-20 For formic acid, the CO stretch also at
1105 cm-1 as well as the CdO stretch at 1776 cm-1 are visible.
Formic acid anhydride and formic acid are products from the
reaction channel in which a hydrogen atom is abstracted from
the CH3 group of methyl formate (Figure 1, pathway 2). The
decomposition of formic acid anhydride (FAA) has been studied
by Lundell et al.19 and Kuhne et al.20 Lundell et al.19 using ab
initio methodology confirmed the primary dissociation pathway
No evidence for the second degradation channel (Figure 1,
pathway 1) of methyl formate is found. This channel should
produce products such as CH2O, CH3, and CH3O. Under
oxygen-rich conditions, CH3 and CH3O should also yield
formaldehyde. No evidence for CH2O exists. The reaction of
CH3O radicals with O2 to form CH2O is very slow, having a
recommended rate constant9 of 1.9 × 10-15 cm3 molecule-1
s-1. The subsequent reaction of formaldehyde with excess
chlorine radicals by contrast is relatively fast, having a rate
constant of 7.3 × 10-11 cm3 molecule-1 s-1. In contrast to
formaldehyde, formic acid is removed more slowly by chlorine
radicals. A rate constant of 2.3 × 10-13 cm3 molecule-1 s-1 is
recommended.9,21 The fact that formic acid is detected as a
degradation product while formaldehyde is not may be explained
by arguing that formaldehyde is rapidly reacted away by excess
chlorine radicals. Thus, the concentration of formaldehyde never
increases above the detection limits of the method.
Both pathways in Figure 1 contribute to the loss of methyl
formate and to the rate constant determined in the previous
section. To estimate the relative importance (i.e., branching ratio)
of each pathway, the individual rate constants for each pathway
were calculated using ab initio molecular orbital methods.
C. Computational Study of the Mechanism of Cl Atom
Reaction with Methyl Formate. 1. Structure and Energetics.
The structures of methyl formate, the two possible transition
states, and the two alkyl radical products are illustrated in Figure
4. The two C-O single bonds are predicted to be 1.441 and

1508 J. Phys. Chem. A, Vol. 104, No. 7, 2000
Good et al.
Figure 3. Reaction progress for the reaction, CH3OCOH + Cl f products.
1.341 Å, while the carbonyl bond is predicted to be 1.207 Å in
length. The experimentally determined values reported by Curl22
are 1.437, 1.334, and 1.200 Å, respectively. Thus, the error
associated with the present methodology is less than 1%.
Figure 4b shows the transition state in which the carbonyl
hydrogen is removed by atomic chlorine. In the transition state,
the carbonyl C-H bond lengthens to 1.208 Å while the forming
H-Cl bond shortens to 1.621 Å. In addition, calculations at
the MP2/6-311++G(2d,2p) level of theory suggest that the
carbonyl CdO bond shortens from 1.207 Å in methyl formate
to 1.193 Å in the transition state. The C-O single bond adjacent
to the methyl group increases from 1.441 Å in methyl formate
to 1.454 Å in the transition state. In contrast, the C-O single
bond adjacent to the carbonyl center decreases to 1.318 Å.
Figure 4c illustrates the removal of one of the longer, out-
of-plane hydrogen atoms of the methyl group. In this transition
state, the cleaving C-H bond lengthens to 1.302 Å while the
H-Cl bond shortens to 1.501 Å. Extraction of the in-plane
hydrogen atom was found to lie approximately 5 kcal mol-1
higher in energy than the transition state involving the out-of-

Reaction of Methyl Formate with Cl Atoms
J. Phys. Chem. A, Vol. 104, No. 7, 2000 1509
Figure 4. MP2/6-311++G(2d,2p) optimized structure of methyl formate, transition states, and alkyl radical products.
TABLE 2: Energetic Parameters for Methyl Formate, Transition States, and Products at 298 Ka
energy
thermal
correction
partition
function
imaginary
frequency
species
QCISD(T)/6-311++G(2d,2p)
CH3OCOH
Cl-CH3OCOH
CH3OCOH-Cl
Cl
CH3OCO
CH2OCOH
HCl
-228.6425578
-688.2589126
-688.2628421
-459.625946
-227.9780063
-227.9746316
-460.2886755
0.0656
0.0605
0.0617
.0014
0.0531
0.0511
.00899
4.653 × 1031
1.028 × 1034
1.066 × 1034
4.00 × 1026
-1070
-860
a Energies and thermal corrections in hartrees. Partition functions in units of cm3 molecule-1 s-1. Imaginary frequencies in units of cm-1
.
plane hydrogen atoms. Extraction of the in-plane hydrogen atom
will not contribute significantly to the overall rate constant. Parts
d and e of Figure 4 present the optimized structure of the alkyl
radicals, CH3OCO and CH2OCOH.
hydrogen is slightly more favorable having a reaction enthalpy
of -2.0 kcal mol-1, while the removal of a methyl hydrogen
(reaction 1b) is calculated to be exothermic by -1.1 kcal mol-1
.
Using G2 and G2(MP2) methodology along with isodesmic
reactions, Good et al.25 determined the 298 K heat of formation
The relevant energetic parameters for each reactant and
transition state are reported in Table 2 and Figure 5. For the
following reactions, removal of the carbonyl hydrogen is
predicted to be favored both thermodynamically and kinetically:
of CH3OCO and CH2OCOH to be -37.5 and -36.5 kcal mol-1
,
respectively. These values along with literature values for the
298 K heats of formation of methyl formate (-85.0 kcal
mol-1),24 HCl (-22.06),9 and Cl (28.9)9 yield reaction enthalpies
for reactions 1a and 1b of -3.5 and -2.5 kcal mol-1
,
CH3OCOH + Cl f CH3OCO + HCl
CH3OCOH+ Cl f CH2OCOH + HCl
(1a)
(1b)
respectively. These values are in good agreement with the values
determined in this work.
The C-H bond dissociation energy (BDE) can be estimated
by using 298 K enthalpy values for each species in reactions
2a and 2b.
At the QCISD(T)/6-311++G(2d,2p)//UMP2/6-311++G(2d,2p)
level of theory, the reaction enthalpy for removal of the carbonyl

1510 J. Phys. Chem. A, Vol. 104, No. 7, 2000
Good et al.
Figure 5. Relative energetics for methyl formate reactions.
CH3OCOH f CH3OCO + H
reaction 1a resulting in the formation of CH3OCO radical. A
reasonable estimate for the uncertainty associated with the
computation of each activation energy is (0.5 kcal mol-1. With
this uncertainty, the ratio k1a/k1 could range from 65% to 97%.
Bartels et al.23 examined the analogous hydrocarbon system,
i.e.,
(2a)
(2b)
CH3OCOH f CH2OCOH +H
The 298 K heat of formation9 of the hydrogen atom is 52.1
kcal mol-1. Thus, the BDE for reactions 2a and 2b is estimated
to be 99.6 and 100.6 kcal mol-1, respectively. Previous
investigators have noted a correlation between a molecule’s
C-H bond dissociation energy and the reaction rate of CH bond
dissociation reactions.27 In addition to being thermodynamically
favored, our analysis suggests that removal of the carbonyl
hydrogen is also kinetically favored over removal of one of the
methyl hydrogen atoms. This suggestion is supported by our
molecular orbital calculations of the activation energies for
pathways 1 and 2. At the QCISD(T)/6-311++G(2d,2p)//UMP2/
6-311++G(2d,2p) level of theory, removal of the carbonyl
hydrogen is calculated to proceed over a reaction barrier of 0.2
kcal mol-1 while the activation energy for removal of a methyl
CH3CHO + Cl f CH3CO + HCl
CH3CHO + Cl f CH2CHO + HCl
(4a)
(4b)
Their investigation determined k4b/k4a to be 0.0753 and thus k4a/
k4 to be over 92%. Thus, for the acetylaldehyde system, removal
of the carbonyl hydrogen is shown to be favored over abstraction
of a methyl hydrogen. The analogous conclusions are suggested
for the methyl formate system.
IV. Conclusions
hydrogen is a substantially higher 1.9 kcal mol-1
.
FTIR analysis of the products from the reaction of chlorine
atoms with methyl formate show that both formic acid anhydride
and formic acid are products of the reaction. Chlorine radical
initiated hydrogen abstraction of methyl formate is found to
2. Comparison of Branching Ratio and Rate Constant from
Theory and Experiment. For reactions 1a and 1b, the branching
ratio is expressed as the ratio of the rate constants, i.e., k1a/k1.
From transition state theory, each rate constant is given by the
following expression:
occur with a rate of 1.4 ( 0.5 × 10-12 cm3 molecule-1 s-1
.
This value is in agreement with previous determinations by
Wallington et al.16 (1.4 ( 0.1 × 10-12 cm3 molecule-1 s-1
)
Qq
LkbT
e-E /k T
(3)
and Notorio et al.17 (1.8 ( 0.2 × 10-12 cm3 molecule-1 s-1).
Ab initio calculations at the QCISD(T)/6-311++G(2d,2p)//
MP2/6-311++G(2d,2p) level of theory predict the rate to be
2.8 × 10-12 cm3 molecule-1 s-1, which is in reasonable
agreement with experimental determinations. Additionally, our
calculations suggest that the reaction between methyl formate
and chlorine occurs predominately (90%) at the carbonyl
hydrogen resulting in the formation of CH3OCO radical.
a
b
k )
h
QClQmethylformate
where Ea is the activation energy, T is the temperature, Q
represents the total partition function incorporating translational,
rotational, vibrational, and electronic terms (QT ) QeQvQrQt),
L is a statistical factor representing the number of equivalent
extractable hydrogen atoms, and kb is Boltzmann’s constant.
Tunneling corrections, which may slightly lower the activation
energy, have not been included in this work. Removal of a
methyl hydrogen is estimated to have a rate constant of 2.8 ×
10-13 cm3 molecule-1 s-1, while removal of the carbonyl
hydrogen is predicted to have a rate constant of 2.5 × 10-12
cm3 molecule-1 s-1 at 298 K. The combined rate constant is
thus 2.8 × 10-12 cm3 molecule-1 s-1. The experimentally
determined rate16,17 has previously been found to range between
1.4 × 10-12 and 1.8 × 10-12 cm3 molecule-1 s-1. Thus, the
298 K rate constant for the reaction of methyl formate with
chlorine atom as determined by our ab initio methodology is a
reasonable estimate. It is also reasonable to expect the branching
ratio of reactions 1a and 1b to be more reliable, as errors
common to both calculations may cancel.
References and Notes
(1) Rouhi, A. M. Chem Eng. News 1985, 44, 37.
(2) Japar, S. M.; Wallington, T. J.; Richert, J. F. O.; Ball, J. C. Int. J.
Chem. Kinet. 1990, 22, 1257.
(3) Jenkin, M. E.; Hayman, G. D.; Wallington, T. J.; Hurley, M. D.;
Ball, J. C.; Nielsen, O. J.; Ellerman, T. J. Phys. Chem. 1993, 97, 11712.
(4) Wallington, T. J.; Hurley, M. D.; Ball, J. C.; Jenkin, M. E. Chem.
Phys. Lett. 1993, 211, 41.
(5) Langer, S.; Ljungstrom, E.; Ellerman, T.; Nielsen, O. J.; Sehested,
J. Chem. Phys. Lett. 1995, 240, 53.
(6) Sehested, J.; Mogelberg, T.; Wallington, T. J.; Kaiser, E. W.;
Nielsen, O. J. J. Phys. Chem. 1996, 100, 17218.
(7) Sehested, J.; Sehested, K.; Platz, J.; Egsgaard, H.; Nielsen, O. J.
Int. J. Chem. Kinet. 1997, 29, 627.
(8) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.;
Johnson, B. G.; Robb, M. A.; Cheeseman, J. R.; Keith, T.; Peterson, G. A.;
Montgomery, J. A.; Raghavachari, K.; Al-Laham, M. A.; Zakrzewski, V.
G.; Ortiz, J. V.; Foresman, J. B.; Cioslowski, J.; Stefanov, B. B.;
Using the above rate data for reactions 1a and 1b, it is
predicted that 90% of the total reaction proceeds through

Reaction of Methyl Formate with Cl Atoms
J. Phys. Chem. A, Vol. 104, No. 7, 2000 1511
Nanayakkara, A.; Challacombe, M.; Peng, C. Y.; Ayala, P. Y.; Chen, W.;
Wong, M. W.; Andres, J. L.; Replogle, E. S.; Gomperts, R.; Martin, R. L.;
Fox, D. J.; Binkley, J. S.; DeFrees, D. J.; Baker, J.; Stewart, J. P.; Head-
Gordon, M.; Gonzalez, C.; Pople, J. A. Gaussian 94, revision D.2; Gaussian,
Inc.: Pittsburgh, PA, 1995.
(9) DeMore, W. B.; Sander, S. P.; Golden, D. M.; Hampson, R. F.;
Kurylo, M. J.; Howard, C. J.; Ravishankara, A. R.; Kolb. C. E.; Molina,
M. J. Chemical Kinetics and Photochemical Data for Use in Stratospheric
Modeling EValuation #12; Jet Propulsion Laboratory: Pasadena, CA,
January 1997.
(10) Tschuikow-Roux, E.; Faraji, F.; Paddison, S.; Niedzielski, J.;
Miyokawa, K. J. Phys. Chem. 1988, 92, 1488.
(11) Tuazon, E. C.; Atkinson, R.; Corchnoy, S. B. Int. J. Chem. Kinet.
1992, 24, 639.
(12) Wallington, T. J.; Ball, J. C.; Nielsen, O. J.; Bartkiewicz, E. J.
Phys. Chem. 1992, 96, 1241.
(13) Manning, R.; Kurylo, M. J. J. Phys. Chem. 1977, 81, 291.
(14) Niki, H.; Maker, P. D.; Savage, C. M.; Breitenbach, L. P. Int. J.
Chem. Kinet. 1980, 12, 1001.
(15) Beichert, P.; Wingen, J. L.; Vogt, R.; Ezell, M. J.; Ragains, M.;
Neavyn, R.; Finlayson-Pitts, B. J. J. Phys. Chem. 1995, 99, 13156.
(16) Wallington, T. J.; Hurley, M. D.; Ball, J. C.; Jenkin, M. E. Chem.
Phys. Lett. 1993, 211, 41.
(17) Notario, A.; Le Bras, G.; Mellouki, A. J. Phys. Chem. 1998, 102,
3112.
(18) Wu, G.; Van Alsenoy, C.; Geise, H. J.; Sluyts, E.; Vander Veken,
B. J. J. Phys. Chem. 1995, 99, 8589.
(19) Lundell, J.; Rasanen, M.; Raaska, T.; Nieminen, J.; Murto, J. J.
Phys. Chem. 1993, 97, 4577.
(20) Ku¨hne, H.; Ha, T.-K.; Meyer, R.; Gu¨nthard, Hs. H. J. Mol.
Spectrosc. 1979, 77, 251.
(21) Tyndall, G. S.; Wallington, T. J.; Potts, A. R. Chem. Phys. Lett.
1991, 186, 149.
(22) Curl, R. F. J. Chem. Phys. 1959, 30, 1529.
(23) Bartels, M.; Hoyerman, K.; Langer, U. Ber. Bunsen-Ges. Phys.
Chem. 1989, 93, 423.
(24) Curtiss, L. A.; Ragavachari, K.; Redfern, P. C.; Pople, J. A. J. Chem.
Phys. 1997, 106, 1063.
(25) Good, D. A.; Francisco, J. S. J. Phys. Chem., in press.
(26) Tschuikow-Roux, E.; Yano, T,; Niedzielski, J. J. Chem. Phys. 1985,
82, 65.
(27) Hsu, K. J.; Demore, W. B. J. Phys. Chem. 1995, 99, 11141.
(28) Scott, A. P.; Radom, L. J. Phys. Chem. 1996, 100, 16052.