Kinetics and mechanism of the thermal gas-phase oxidation of tetrachloroethene by molecular oxygen in presence of trifluoromethylhypofluorite, CF3OF

Article abstract of DOI:10.1524/zpch.1998.203.Part_1_2.183

The oxidation of tetrachloroethene by molecular oxygen in presence of CF₃OF has been studied at 314.0, 324.2, 334.1 and 344.3 K. The initial pressure of CF₃OF was varied between 2.0 and 8.2 Torr, that of CCl₂CCl₂ between 8.7 and 21.7 Torr, that of O₂ between 33.2 and 730.7 Torr. Several runs were made adding N₂ at pressure varying between 250.4 and 525.9 Torr. The major products were CCl₃C(O)Cl and COCl₂. CF₃OCCl₂C(O)Cl, CCl₂FC(O)Cl, CF₃OCCl₂CCl₂F and CCl₂FCCl₂F were formed in traces. The oxidation is a chain reaction. Its rate increases with total pressure. The following mechanism, where E = CCl₂CCl₂, R = CCl₂FCCl₂, CF₃OCCl₂CCl₂ or CCl₃CCl₂, R′ = CCl₂F, CF₃OCCl₂ or CCl₃ and M = effective pressure, explains the experimental results: 1) CF₃OF+E → R+CF₃O 3, 7) R+O₂+M → RO₂+M 5) RO → R′C(O)Cl+Cl 9) CCl₃CCl₂O → CCl₃C(O)Cl+Cl 11) CCl₃+O₂+M → CCl₃O₂+M 13) CCl₃O → COCl₂+Cl 15) R+CF₃OF → RF+CF₃O 2) CF₃O+E → R 4, 8) 2RO₂ → 2RO+O₂ 6) Cl+E → CCl₃CCl₂ 10) CCl₃CCl₂O → CCl₃+COCl₂ 12) CCl₃O₂+RO₂ → CCl₃O+RO+O₂ 14) 2R → recombination products, k₉ = (3.0±1.4) × 10¹³ exp(-9.66±1 kcal mol^-1/RT) s^-1. by R. Oldenbourg Verlag, Muenchen 1998.

Full text of DOI:10.1524/zpch.1998.203.Part_1_2.183

Zeitschrift für
Chemie, Bd.
203, (1998)
S. 183-197
Physikalische
©
by R. Oldenbourg Verlag, München 1998
Kinetics and Mechanism
of the Thermal Gas-Phase Oxidation
of Tetrachloroethene
Molecular
by
Oxygen
in Presence of
Trifluoromethylhypofluorite,
CF3OF
By Joanna
Czarnowski
Instituto de
Teóricas Aplicadas, Sucursal 4,
y
Investigaciones Fisicoquímicas
Casilla de Correo 16, (1900) La Plata, Argentina
(
Received March 3, 1997)
I
Oxidation
I
Tetrachloroethene
I
Gas-phase
I
Chlorine atoms
Trifluoromethylhypofluorite
The oxidation of tetrachloroethene by molecular
in
of CF,OF has been
presence
oxygen
studied at 314.0, 324.2, 334.1 and 344.3 K. The initial
of CF3OF was varied
pressure
between 2.0 and 8.2 Torr, that of CC12CC12 between 8.7 and 21.7 Torr, that of O, between
3
3.2 and 730.7 Torr. Several runs were made adding N2 at
between 250.4
pressure varying
and 525.9 Torr. The major products were CC13C(0)C1 and COCl2. CF30CC12C(0)C1,
CC12FC(0)C1, CF,OCCl2CCl2F
and CC12FCC12F were formed in traces. The oxidation is
a
chain reaction. Its rate increases with total
The following mechanism, where
or
pressure.
E
CC12CC12,
R
CC12FCC12,
or CC13CC12, R'
CCLF,
CF,0CC12CC12
CF,OCCl2
CO, and
M
effective
explains the experimental results:
E
pressure,
R+CF,0
R02+M
—
1)
CF3OF+E
2) CF,0
+
R
R
+
02
+
M
-»
4, 8) 2RO,
—
2RO
+
3,
7)
02
-
>
—
5
)
)
RO
R'C(0)C1
—
+
CI
6)
Cl+E
CC13CC12
—
9
CC1.,CC120
CC1,C(0)C1+C1
10) CC1,CC120
CCl,+COCl2
—
—
1
1) CCl.,+02+M
CC1302+M
COCl2+Cl
5) R+CF,OF — RF+CF30
(3.0±1.4)X1013exp(-9.66±l kcal moi-'IRT) s"
12) CC1302+R02
CCl,0+RO+02
1
3) CC1,0
-»
14)
2R —» recombination
products,
1
kg
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1
84
Joanna Czarnowski
CF2CC1, [1]
Introduction
In the
CHC1CCL [2] in
studied reactions of
with
and
previously
CF3OF
of 02,
a
low
oxidation of each alkene
presence
temperature
occurred, giving CF2C1C(0)C1 and CHC12C(0)C1 as the major products.
These works
absence of
alkene.
To rationalize the
evidence that chlorine atoms can be
in
provided
generated
the addition of CF,OF to the double bond of chloro-
light by
results of the oxidation of
and
experimental
CF2CC12
CHC1CC12 in presence of CF,OF, the formation of free radicals CF30' was
The recent studies of the reactions of CF,OF with haloalkenes
postulated.
E) [3, 4] confirmed,
which radicals
that these reactions occur via
and
are formed
the
a
radical
in
of
(
mechanism,
CF,0'
F(E)'
by
homolytic cleavage
the O—F bond in the bimolecular reaction between CF,OF and haloalkene.
The radical CF30' adds
rapidly
The formation of these radicals was detected
to the double bond, radical CF,0(E)'.
giving
EPR and ENDOR. It was
by
other authors that the addition of CF,0' to the unsaturated
reported by
system is the major reaction channel
in these
system
[5-8].
Radicals
are formed in
oxidation of HCFCs and
CF30'
atmospheric
HFCs
CF,
[9—19]. Tetrachloroethene is
indus-
and is used in metal
containing
group
produced
1
in
amounts about 400 ktons
trially
large
yr [20],
and as industrial solvent. It
into the
degreasing, dry cleaning
atmosphere
escapes
at 90—100% of the amount
produced.
In this work
a
kinetic
of the oxidation of
CCLCCL,
initiated
the addition of CF,OF to its double bond has been undertaken.
study
by
Experimental
The reaction
with
decrease. The
were
proceeded
pressure
static
experiments
per-
formed in
a
measurements at
bulb of 270 cm' was
grease-free
system allowing pressure
constant volume and
A
temperature.
spherical quartz
used as
gauge and the temperature
stat. Infrared
were recorded on
a
reaction vessel. The
was measured with
a
quartz
spiral
pressure
maintained within ±0.1
Perkin-Elmer 325
10 cm cell with sodium chloride windows.
were recorded on
Gow-Mac 625
a
Lauda thermo-
spectrometer
using
a
spectra
a
using
The
a
chromato-
gas
column of 5%
chromatograms
with
a
balance detector,
a
graph, provided
gas-density
using
SE-30 on chromosorb W-AW at 273 K. The carrier
was N2. The gas
gas
balance
in wt% if each
area is
density
responds directly
peak
respective
and then each corrected area is
gas,
multiplied by
Mj/CM, Mc),
where and Mc are the
M¡
molecular
weights
F,
of each
divided
and the carrier
component
the sum of all corrected areas [21].
by
All reactants were commercial
CF3OF was washed with
[22]. Tetrachloroethene
products.
0
.1 mol dm"3 NaOH solution and filtered at 80
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Thermal Gas-Phase Oxidation of CC1,CC1,
O, in Presence of CF.OF
185
by
was
several
distillations on
a
vacuum line,
retaining
purified by
trap-to-trap
each fraction
between 263 and 273 K. 02 and N2 were bubbled
distilling
98%
H2S04 and
passed slowly through a Pyrex
through
analytical-grade
coil at 123
and at
liquid-air temperature, respectively.
The reaction was followed
the
decrease as
a
by measuring
pressure
324.2,
of CF,OF was varied between 2.0 and
function of time.
44.3 K. The initial
were made at 314.0,
334.1 and
Experiments
3
8
3
pressure
.2 Torr, that of CC12CC12 between 8.7 and 21.7 Torr and that of 02 between
3.2 and 730.7 Torr. Several runs were made in
of
N2, varying its
presence
from 250.4 to 525.9 Torr.
pressure
Results
The reaction was
a
chain reaction,
the order 1.5 with
respect
approaching
to both reactants. It indicated that both
formation of the chain carriers. The reaction rate
and
CF,OF
CC12CC12 accounted for
on the total
depended
pressure. The effects of 02 and N2 were similar. At the pressure of 02 used
in this work, the reaction attained the
condition with
pseudo-zeroth-order
to 02 as reactant, 02
as a
third
respect
acting
body.
Within the temperature
used, and in absence of
CF,OF, no
reac-
range
tion between alkene and 02 was observed after several hours.
In of CF,OF the
were identified:
presence
following products
CC1,C(0)C1, COCl2, CF,0CC12C(0)C1, CC12FC(0)C1, CF,0CC12CC12F and
CC12FCC12F. CC1,C(0)C1 and COCl2 were the major products. The other
were formed in traces. The
very strong
infrared
absorption band
consumption of
products
of CF,OOCF, at 1166 cm-' [23, 24] was never observed.
All the
were carried out until the total
experiments
CC12CC12. For analyzing the reaction mixture of each experiment, the reac-
tion vessel was
cooled to
air
and the mixture
and non-consumed O,
The fraction volatile at
rapidly
liquid
temperature
fractional condensation. N2, if
separated by
were
present,
as volatile at
air
separated
liquid
temperature.
153
consisted of CF,OF. COCI, was
remaining as
as volatile at 183 K. The
in two
separated
fraction
residue at 183
was
always separated
samples
I
and II.
of each
sample
I
were
to determine the
Chromatograms
performed
relative concentration of CC1,C(0)C1. In these
six
>
chromatograms
peaks
Their areas were A2(II) S§> A5(V)
>
>
appeared.
A,(I)
A4(IV)
Aft(VI)
>
where the
and the Roman numeral in the
the ordinal number of each
the
A,(III),
subscript signifies
peak
parenthesis designates
corresponding
characterized
its retention time. In the IR
was identified.
of the
compound,
samples I, only CC1,C(0)C1
The
by
spectra
II of all
were condensed
the condensate was
in three fractions Fr,, Fr2 and Fr3.
To concen-
samples
experiments
together.
trate the more volatile
products,
condensation at 195 and 223
fractional
separated by
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186
Joanna Czarnowski
Table 1. Analytical data of 25 experiments. The pressure differences Ap and the partial pressures
are given in Torr. (%) are the respective yields of CC1,C(0)C1 and COCf based on the initial
of CCl2CCl2i.
pressure
Run 77K
CF,OF, CF,OF, CCfCCl,, O,,
O,,
50.8
93.2
191.7
CCl,C(0)CIa (%)
COCl2
(%)
17
12
16
15
14
314.0 4.0
314.0 5.0
314.0 5.5
314.0 4,7
314.0 5.2
7.0
6.5
6.3
7.0
8.2
4.0
3.7
4.7
6.4
4.8
5.4
7.0
6.4
3.2
2.6
3.4
6.9
6.4
6.3
6.9
8.1
4.0
3.7
4.7
6.3
4.8
5.4
6.9
6.3
3.2
2.6
3.4
9.5
12.0
12.8
56.3
100.1
199.0
287.7 281.6
400.6 393.8 10.2
46.9
67.5
98.2
111.2 103.5
208.9 203.0
339.6 330.5
47.7
131.3
196.1
364.7 357.0 12.2
497.5 490.2 11.2
8.1
10.1
11.0
9.2
(85.3
3.0
3.6
3.8
3.0
(84.2
(85.9
(84.4
10.9
12.0
12.0
11.4
10.5
13.6
10.5
16.0
(85.0 3.8
(85.0 3.4
(86.0 3.2
2
4h 324.2 5.0
40.3
61.0
92.2
10.2
9.8
9.0
2
1
3
9
324.2 4.9
324.2 4.4
324.2 5.8
324.2 4.4
324.2 7.0
334.1 4.7
334.1
334.1
334.1
(85.7
(86.8
(85.7
(86.9
(86.2
(88.2
3.0
3.8
2.8
4.4
21
11.8
2
IX
2
2
9.0
13.9
9.4
11.2
11.9
8
10.9
12.7
41.6
124.1
188.2
2.6
3.1
25
5.8
6.0
6.0
2
3
7
2
13.9
13.7
13.0
(85.6 3.8
3.4
3.2
2.8
(
89.1
31
334.1 5.7
(86.2
(87.4
(88.2
3
2
3
0
9
9
334.1
334.1
4.5
5.0
3.8
3.3
2.9
2.8
2.0
3.3
2.5
2.5
2.2
3.8
3.3
2.9
2.8
2.0
10.3
11.0
19.5
14.6
17.0
16.4
21.7
588.0 582.2
730.7 724.4
9.0
9.7
2.8
4.6
344.3 8.6
344.3 6.4
344.3 7.5
344.3 7.3
344.3 9.6
344.3 6.4
344.3 6.4
64.9
54.0
17.4
13.0
(
89.2
33
38
37
111.0 102.7
194.9 185.4 14.8
320.1 311.1 14.6
392.1 380.0 19.0
494.6 486.4 12.9
585.2 577.1
(89.0 3.6
(87.1
4.0
3.3
2.5
2.5
2.2
(89.0; 3.8
36
(87.6
(89.0
(86.9
5.0
3.4
3.4
3
5
14.5
14.5
3
4
12.6
CC1,C(0)C1 contains traces of CF^OCCUCíOjCl, CC1,FC(0)CI, CF,OCCl,CCl,F and CCLFCfF.
This
of 525.9 Torr of N2.
experiment was made in presence
In the
of the fraction
four
Their
chromatograms
areas were A2(II)
The retention times of the
Fr,
peaks2 appeared.
>
>
>
A,(III). The
to
A,(I)
A4(VI)
peak corresponded
3
and
4
were
to those of
CC13C(0)C1.
the arisen
peaks
equal
CC12FCC12F and CF,0CC12CC12F in the
peaks
by
chromatograms
under similar conditions in the
of the
of
performed
previous study
products
the addition of CF3OF to tetrachloroethene in absence of 02 [25]. In the IR
of the fraction Fr,, the
bands of CC12FC(0)C1 [26] were
spectra
identified after
absorption
the
of CC1,C(0)C1.
subtracting
spectra
In the
areas were A,(II)
of the fraction Fr2 three
Their
chromatograms
peaks appeared.
>
A3(V)
spectra
>
A2(IV). The
1
to
peak
corresponded
In the IR
of the fraction Fr2, the
bands at
CC13C(0)C1.
absorption
1
806, 1287-1180 and 913-744 cm"1 were observed after subtracting the
of
These
are characteristic to groups
spectra
CC13C(0)C1.
frequencies
C(0)C1, CF3O [24, 27] and CC12, respectively, and are consistent with the
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Thermal Gas-Phase Oxidation of CC1,CC12
02 in Presence of CF,OF
187
by
presence of a compound having
served vibrational
the structure
The ob-
CC13C(0)0 is
CF30CC12C(0)C1.
of
of
pure
frequency
carbonyl group
1812 cm'.
The fraction
consisted of
practically pure CC13C(0)C1, as
confirmed
Fr3
IR
and
by
spectra
chromatograms performed.
The
these data the
data of 25
are summarized in Table 1. From
analytical
experiments
can be deduced
:
following
The formation of CC13C(0)C1 increased with
At 314.0,
temperature.
24.2, 334.1 and 344.3 K, the mean yields of CC13C(0)C1 and COCl2, based
3
on the initial
of CC12CC12, were 85 and 30, 86 and 27.9, 87.3
pressure
and 25.4, and 88.3 and 23.5,
respectively. The consumption
of CF3OF was
<
2%.
[
CCl2CCl2]CUIlsumed
[CC13C(0)C1]
+
0.5 [cocy
Ap, (final pressure decrease)
0.5 [CC13C(0)C1]
Discussion
In order to
propose a
reaction mechanism the
reactions were
con-
following
in
sidered: oxidations of CF2CC12 [1] and CHC1CC12
of
[
2]
presence
CF3OF
and addition of CF3OF to CC12CC12 [28] and to some other haloalkenes
[
3, 4, 29] in absence of 02. The following reactions were also taken into
account: oxidation of radicals CCI, [30—34], reactions between
peroxy
[36], oxidation of
radicals [35], chlorine atom elimination from
CC130'
radicals
19, 37-39], oxidation of CC13CC12H initiated
CF3CCI2 [11,
by
fluorine and chlorine atoms [40] and oxidations of
initiated
CC12CC12
by
OH' and chlorine atoms [41-45].
The
mechanism, where
R
or
following
CC12FCC12, CF3OCCl2CCl2
results:
was
postulated to explain the experimental
—
CC13CC12,
1.
+
CCLFCCi;
+
CF,OF
CC12CC12
CF30'
2.
+
-»
CF30"
CC12CC12
CF30CC12CC12
M
—»
+
M
3a. CC12FCC12
+
02
+
CC12FCC1202
—
3b. CF,OCCl2CCi;
+
02
+
M
CF30CC12CC120;
+
M
4
4
5
5
a.
+
R02
+
—
+
RO'
+
02
RO'
CC12FCC120;
CC12FCCT20'
b. CF30CC12CC1202
—
RO;
—
+
+
02
CF3OCCl2CCl20'
Cl
CF3OCCl2C(0)Cl
CCI3CCI2
CC13CC1202
a.
b.
CC12FC(0)C1
+
CC12FCC120'
-»
+
Cl
CF30CC12CC120'
6.
.
Cl
+
CC12CC12
—
7
CC13CC12
+
02
+
M
—
+
M
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188
Joanna Czarnowski
8
.
.
casern;
CC13CC120'
cci3cci2o'
+
ro; — CCI3CCL0* + Rcr
+
0,
->
+
Cl
9
CC13C(0)C1
—
cci.; + cocu
—
1
0.
1
1. cci;
+
,
+
m
cci,o;
+
m
—
ro; cci3o'
1
1
1
1
2. cci,o;
+
+
ro'
+
o2
3.
4.
5.
—
COCl2
+
Cl
CC130'
2R' — Recombination
products
R"
The
+
CF,OF
->
RF
+
CF,0'.
is
low
the thermal reaction of CF,OF with the
by
primary path
CCFCCF. The
alkenes were
additions of CF,OF to some
rapid
temperature
simple
other authors in studies made for
reported by
preparative
pur-
poses [46, 47].
The recent studies of reactions of CF3OF with haloalkenes
E) [3, 4], have shown that these reactions occur via
The formation of the intermediate radicals was detected
(
a
radical mechanism.
EPR and
cleav-
and halo-
by
ENDOR. The radicals CF,0' and
are
F(E)'
generated by homolytic
age of the o—F bond
alkene. The radical
in the bimolecular reaction between
double bond
CF,OF
giving
CF3O' adds rapidly to the
the radical
CF,0(E)\
A
elimination of chlorine atoms
alkenes was
very rapid
by
reported
system
for CCFCCF
containing
atoms
and
The addition of
eliminated so
to reaction
[
43]
C2H4 [48].
C2H4
rapidly
radicals CCI, and
in the
the free chlorine
02,
that the CIO
observed in absence
produced
process,
spectrum,
of C2H4, was not observed [49]. The addition of chlorine atoms to the
double bond is the
CC12CC12 [50].
removal mechanism of Cl in presence of
predominant
The lack of formation of CF.,OOCF3 corroborates the results of
previous
works [51, 52], which indicate that the addition of the CF,0' radicals to the
double bond of alkenes is faster that
other
halogenated
reaction of CF,0'. It was
considerably
any
that the values of rate constants for the
reported
addition of CF,0° to several alkenes are of order of 1010 dm3 moF1 s"1
[
5-8].
CF3OF is
a
successful gas-phase scavenger for free radicals in absence
of 02,
5
the stable fluoro and CF,0' [3, 4,
giving
corresponding
analogues
3, 54]. But at the oxygen pressure used in this work, the radicals are
It was
other
authors,
that the frac-
Torr of 02 [55]
radicals with
principally scavenged by 02.
reported by
tion of
radicals that escapes oxidation was <0.1% at
2
ethyl
and that the reaction rate constants for
02
exceed those for fluorine atom abstraction from CF,OF by three to four
and
methyl
halomethyl
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Thermal Gas-Phase Oxidation of CCLCCL by O, in Presence of CF,OF
189
orders of
[53]. Then, the rate of reaction
(15) must be very
magnitude
the reaction
low,
the
for the
of CF,OF.
being
(1)
principal pathway
scavenged by
CF30', which initiate chains with chlorine atoms as chain carriers [29].
It was
other authors
that 85% of radicals
consumption
A
small fraction of radicals R'
CF,OF,
generates
radicals
very
reported by
[40],
CC13CC120',
atoms, eliminate
via C—C
formed in the oxidation of CC13CC12h initiated
Cl and
15%
F
by
Cl atom to
CC1,C(0)C1. The
give
remaining
decompose
of CC12CC12, were
pressure
bond scission to
radicals CC13 and COCF. In this work the mean
give
yields
of CC1,C(0)C1 and
based on initial
COCl2,
found to be 85 and 30%, 86 and 27.9%, 87.3 and 25.4% and 88.3 and
2
3.5%, at 314.0, 324.2, 334.1 and 344.3 K,
out that
products originated
small amounts.
It was assumed that
It
respectively.
points
the other
from the
CC12CC12, are formed in
parent
very
/
c3a
/c3b
k7
ku, /c4a
/c4h
kg
kt2 and
k5a
k5b
/cq
kn
and that the recombination constant k,4 is
equal
for all
radicals. The rate constant k,5 was considered to be
of the
independent
radical structure. This
is
the
a
supposition
supported by
room-temperature
values of the rate constants for the abstraction of
fluorine atom from
to
CF,OF by OF;, C2h;, CF,0(CHC1CC12)' and CF30(CC12CCT2)'
reported
be 2X10S [53], >6X10J
2.3XÍ05 [56] and
dm^mol"1 s"1
[
54],
1,4X105
[
28], respectively.
the
to the
sub-
Applying
steady-state approximation
and
mechanism,
stituting UC1][CC12CC12] by /c9[R0']
/c2[CF30'][CCl2CCl2] by
/
v,[CF,OF][Ca2CCl2], for /c,[CF3OF][CCl2CCl2]
>
/t,,[R'][CF3OF], the fol-
of alkene:
was obtained for the
lowing expression
consumption
2
+
.
-d[CCl2CCl2]/d/
/c,[CF3OF][CCl2CCl2]
k9[RO']
(I)
The reaction is of
with
on the total
to O, at the
pseudo-zeroth-order
respect
pres-
sures of 02 used in this work and
The
of the chain
depends
pressure.
velocity
velocity
of elimination of radicals R'
to the
by
02,
proportional
equal
of radicals R', is
to the rate of formation of radicals
generation
the concentration of alkene and fas defined
Troe
CF,0\
[57]:
by
f(l+
'
|log(MM]/*,))2)
(UUCVfcc + 1/[M])-'
=
/
where /c<> is the third-order
first-order
constant, k^ is the
is the
of the stabilization of the ener-
low-pressure-limit
constant and
pseudo-
factor
high-pressure-limit
Fc
broadening
which describes the
pressure dependence
adduct R02 on the effective
M. The concentrations of
pressure
the collisional deactivation efficiencies of
gized
radicals R02 and RO'
depend on
and other
02
gases present.
Then:
URO"] Â:v[R"][02][M]
kp Â:I5[R'][CF30F][CC12CC12]/
(III)
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190
Joanna C/arnowski
C
0.0005
.0000
0
0.5
1
.0
1.5
f
(
[cf3of] [ccijCcgr0
Fig. 1. The plot of {{AplAt)ri[CV,0¥}[CC\2CC\2}) vs. {([CF,0F][CC12CC12])"5/1 at 314.0 K,
where Ap is the
decrease, At is the reaction time and
to
r
([CCUCCl,],,,,,,,,,/
in the Table 2.
pressure
/
J/'i„,r,i) /is defined by Eq. (II). The value of the slope, equal
k,
is
given
where
:
kJK
(IV)
is the ratio of the rate constant for chlorine atoms
chlorine atoms elimination and
generation to
that for
[
R']
(*,/)ki4)05[CF3OF]05[CCl2CCl2]05.
and (V) into (Ill), one obtains:
(V)
Substituting Eqs. (IV)
9[RO']
Eq.
£
(VI)
feifc15/*6)(ifc1/ife14)05[CF3OF]15[CCl2CCl2]15/.
Substituting Eq. (VI)
of alkene is obtained:
into
Eq.
(I), the
following rate
of the
consumption
2
A:,[CF,OF|[CCl2CCl2]
(^*15/*6)(fc1/fc14)0S[CF3OF]15[CCl2CCl2]15/.
(VII)
-d[CCl2CCl2]/dr
+
Data treatment
The
composite constant
from
Eq.
(VII):
k
(VIII)
(
LikMikJk^r
a
was obtained as
tion of
defined
slope, plotting j(zl/5/z/?)r/[CF,OF][CCFCCF]} as
a
func-
where
r
{
[CF30F][CC12CC12]}0-5/,
([CCl2CCl2]initial/zlpflnal) and/is
(II). The
at 314.0, 324.2, 334.1 and 344.3 are illus-
by Eq.
Figs.
plots
-4,
respectively.
trated at
1
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Thermal Gas-Phase Oxidation of CC1,CC12
Í-A 0.006
02 in Presence of CF,OF
191
by
_
O
O
-
~
0.005
o
o
324.2
0
.004
.003
o
0
o
0
.002
0.001
.000
X
C
0
0.2
0.4
0.6
0.8
1.0
1.2
f
([CFjOF]
[CCI2CCI2])
Fig. 2. The plot of {(zJp/zfr)r/[CF,OF][CCl2CCl2]} vs.
at 324.2
,
(
([CF,OF][CCl2CCl2])05/)
where zip is the
decrease, zfr is the reaction time and
r
pressure
defined by Eq. (II). The value of the slope,
([CCl2CCl2]i„uui/
dpnnud-fis
equal
to
k,
is
given
in the Table 2.
S
o.oooo
0.2
0.4
0.6
0.8
1.0
1.2
f
([CFjOF]
[CCI2CCI2])°-5
3
.
The plot of {(Ap/At)ri[CF,OF][CC\2CC\2]} vs.
at 334.1 K,
Fig.
{([CF,0F][CC12CC12])"5/)
where Ap is the
decrease, zJr'is the reaction time and
r
pressure
([CCl2CCl2]¡„;,ia|/
defined by Eq. (II). The value of the slope, equal to k, is
given in
the Table 2.
4
pr,„ai)./is
the data for the radical CC1,CC12, the values of k0, k^ and
Lacking
Fc,
derived from the
for the termolecular
temperature dependent expression
02
were used to
calculate/.
+
+
M
+
M
process CC\¡
The
CC1302
[33],
following expression was
used to calculate the effective
M
:
pressure
0.4[COC12]
M
[CCLCCy
+
+
+
[
+
CC1,C(0)C1]
0.42[CF,OF]
+
0.21
0.25[O2]
[N2]
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192
Joanna Czarnowski
;
0.035
o
<
o.ooo
0
.0 0.2 0.4 0.6 0.8 1.0 1.2
5
f
(
[CF30F]
[CCI2CCI2])°
4.
The plot of
vs.
at 344.3 K,
([CCl2CCl2]in¡,¡„|/
Fig.
where
lpfi„,i)./is defined by Eq.
{(zi/;/zff)r/[CF3OF][CCI2CCl2]}
{([CF,0F][CC12CC12])"'5/]
A
is the
decrease, At is the reaction time and
r
pressure
(II). The value of the slope, equal to k, is given in the Table 2.
¿
Table 2. Constants used to calculate the consumption rates od CC1,CC12 at different
temperatures.
1
¿
,/KT5
kJW2
(Torr min ')
A./10"
(Torr 'min ')
km
(min ')
(K)
(Torr1 min"')
3
14.0
24.2
0.259
0.54
2.8
2.16
4.56
4.27
0.997
3.14
3
3
3
34.1
44.3
1.05
2.014
1.69
1.32
4.0
3.76
9.39
26.3
The relative collisional deactivation
factors with
to
efficiency
respect
that of CC12CC12, taken as
were obtained for each gas from the corre-
unity,
collisional efficiencies, derived from the correlation between the
sponding
of
a
third
and the association rate of two
[58]. It
boiling point
body
species
was
that C2H4 is 3.16 and
4
times more effective than 02 [59] and
reported
N2 [60], respectively.
For Fc the value of 0.6 was taken. The values of
fe»,
k
and
ku
the
ko,
rate constant for the addition of CF3OF to CC12CC12 obtained
previously
[
28], are given in the Table 2.
The results of the
are
in the Table 3. In this table
experiments
presented
t
is the reaction time,
is the
decrease, and
i
and
f„ —f„_,
zip
pressure
subscripts
/
initial and final. The amounts of CF3OF consumed di At
signify
were
1
computed, 3point by point, by CF,OF„{
exp(-£,zlf[CCFCCF],,,)},
where
1, 2,
and [CCFCCF],,, is the mean
of alkene in the
pressure
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Thermal Gas-Phase Oxidation of CC12CC12
O, in Presence of CF,OF
193
by
Table 3. The observed rate of reaction and the calculated rate of consumption of CC12CC12
divided by
r
[CCLCCUyAp,.
Run
77K
CF3OFJ CC12CC12,/ 02i/
AtI
min
ApJ
Torr
Ap/
1
Torr
Torr
Torr
Torr
Torr min
Torr min
1
7
2
314.0 7.0
9.5
56.3 4.0
31.50 0.7
9.95
81.70 2.3
0.022
0.014
0.009
0.020
0.014
0.009
8
1
1.5
1
314.0 6.5
314.0 6.3
314.0 8.2
324.2 4.0
324.2 4.7
324.2 4.8
324.2 5.4
334.1 7.0
12.0
12.8
100.1 5.0
199.0 5.5
31.40
8.30 2.1
19.40 2.7
1.1
0.035
0.027
0.012
0.033
0.022
0.014
6
1
1
6
30.10
9.20 2.2
21.70 3.5
1.4
0.047
0.027
0.021
0.047
0.031
0.019
5
1
1
4
12.0
12.0
400.6 5.2
46.9 5.0
98.2 4.4
29.90 2.3
9.00 3.4
18.70 4.2
0.077
0.038
0.012
0.073
0.032
0.015
5
1
24"
26.30 1.9
9.35 3.2
17.90 4.2
0.072
0.039
0.017
0.079
0.037
0.014
5
1
1
9
10.5
10.5
29.80
9.80 2.1
21.05 2.9
1.3
0.044
0.027
0.013
0.040
0.024
0.014
5
1
22
208.9 4.4
339.6 7.0
28.90 1.6
0.055
0.029
0.017
0.057
0.030
0.014
5
9.60 2.5
18.80 3.5
1
18
16.0
10.9
8.7
16.30 2.6
0.160
0.086
0.050
0.173
0.094
0.047
3
0.20 3.8
2.20 5.4
6
28
26
30
29
40
47.7 4.7
98.6 3.8
13.80 2.0
0.145
0.065
0.026
0.141
0.063
0.028
2
9.30 3.0
9.70 3.8
5
334.1 3.6
334.1 3.8
30.80
8.40 2.3
24.10 3.0
1.4
0.045
0.024
0.013
0.050
0.025
0.011
6
1
10.3
11.0
588.0 4.5
730.7 5.0
21.8
3.0
9.10 3.9
9.10 4.2
0.138
0.033
0.007
0.134
0.028
0.008
4
8
334.1 3.3
344.3 3.4
23.00 3.0
0.40 4.5
19.25 4.8
0.130
0.040
0.005
0.149
0.032
0.005
6
1
15.7
33.2 6.9
6.60
1.7
0.258
0.138
0.086
0.047
0.236
0.156
0.096
0.042
1
3
6
4.55 2.8
0.90 4.2
0.80 5.6
"
This experiment was performed in presence of 525.9 Torr of N2.
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194
Joanna Czarnowski
Table 3. Continuation.
Run
77K
O,,/
All
min
V„hJ
Vcal/
CF,OF¡/ CC12CCI2,/
Ap,/
Ap/
1
'
Torr
Torr
Ton-
Ton-
Torr
Torr min
Torr min
3
8
6
344.3 2.0
344.3 2.5
344.3 2.5
17.0
194.9 7.5
392.1 9.6
494.6 6.4
5.70 1.5
3.80 3.0
3.80 4.3
0.263
0.185
0.130
0.258
0.175
0.109
1
2
3
21.7
14.5
4.2 3.0
2.90 5.6
0.50 6.9
0.714
0.299
0.171
0.683
0.359
0.179
1
2
35
5.95 2.2
0.370
0.203
0.110
0.051
0.030
0.393
0.192
0.090
0.050
0.027
14.80 4.0
22.10 4.8
31.90 5.3
45.40 5.7
interval At. It was assumed that other
of
CF,OF in
pathways
removing
of 02 do not
its concentration. As all the
presence
change significantly
were carried out to the total consumption of alkene, the
experiments
amounts of CC12CC12 consumed were
computed,
point
by
point, multiplying
r
Vobs is
to
At, and Vcal is the
Ap by
([CCi2CC\2]imUJAptinJ.
equal
Api
rate of
of CCFCCF calculated
from
divided
r.
consumption
using Eq. (VII),
by
In order to derive
was assumed to be
to the
k9
Eq. (VIII), kl4
equal
collisional
factor
dm3 moF1 s~') [61]. The
frequency
(10'°
room-tempera-
ture value of the rate constant for the addition of
a
chlorine atom to
CC12CC12, reported by other authors [43], was used for k6. The rate constants
kt and fe15 were calculated from
the
obtained
previously [28] :
expressions
3.16±0.6X107exp(-15.2±1.7kcalmoF'//?F) dm3 mol1 s1
.7±0.5X
k¡
3
1(Fexp(-6.0±l.l kcal mo\
5.74±1.4)
X106, (9.1 ±2.6)
'/RT) dm3 mol"1 s"1.
k15
The values of
X
106, (1.46±0.4)
X
107 and
(
s"1 were obtained for k9 at 314.0, 324.2, 334.1 and
(
2.22±0.4)X107
3
44.3 K,
The
of the
rate
respectively.
temperature dependence
experimental
constant k9 can be
in the Arrhenius form (Fig. 5), as follows:
expressed
(3.0±1.4)X 10l3exp(-9.66±l kcal mol VRT) s
of
".
kg
In
a
theoretical
of the
rad-
study
decomposition
halogenated alkoxy
icals, the following kinetic parameters were calculated for the temperature
2
40-260 [62]
:
range
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Thermal Gas-Phase Oxidation of CC12CC12 by O, in Presence of CF,OF
195
15.0
2.8
2.9
3.0
3.1
3.2
3.3
(103/T)/K
Fig. 5. Arrhenius plot of ¿,
CC1.,0': A=(4.09-4.49)X1013
s
';
E= 9.7 kcal mol"1
'
CFC120": A=(2.85-3.1)Xl013s-1;
E= 10.6 kcal mol"
CF2C10': A=(2.85-3.13)Xl013s-*;
The lower limits determined for
E= 12.4 kcal mol"'.
rates of
CC1,0' and
decomposition
CFCTO' are
1
X
10s s1 at 233
and
3
104 s~' at 253
activation limits of 9.6 and 11 kcal mol"1
K, respectively, and
to the
The
correspond
upper
values of the activation
[36].
for the extrusion of chlorine atoms
are 9.2 and 11.6 kcal mol
reported
energies
from CFC120'
at 238 and 298
[
63]
', respec-
and those for
CF2C1CC120' [1] and CHC12CC120' [2] are
respectively.
This work provides evidence that free chlorine atoms can be released
and COCI, formed as
thermal
9.4 and
tively,
9
.45 kcal mol-',
a
of
the
addition of radical
consequence
CF,0' to the double bond of tetrachloroethene in
constant for chlorine atom detachment from the
has been determined for the first time.
The rate
presence
of
02.
radical
perchloroethyl oxy
Acknowledgement
The author thanks Mr. Z. Czarnowski for
comments. This work
very helpful
was
financially supported by the Consejo
Nacional de
Investigaciones
Científicas Técnicas.
y
References
1
.
J. Czarnowski, J. Chem. Soc,
Trans. 2, 85
(1989)
1425.
Faraday
2.
J. Czarnowski, .
Chem. 191 (1995) 103.
Phys.
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196
Joanna Czarnowski
3
.
F. Conti, C. Corvaja, F. Cremonese, W. Navarrini and V. Torterlli, J. Chem. Soc.,
Faraday Trans. 91 (1995) 3813.
4
5
6
.
.
.
W. Navarini, A. Ruso and V. Tortelli, J.
Chem. 60
6441.
Org.
(1995)
J. Chen, T. Zhu. V. Young and H. Niki, J. Phys. Chem. 97 (1993) 7174.
Ch. Kelly, J. Treaey, H. W. Sidebottom and O. J. Nielsen, Chem. Phys. Lett. 207
(
1993) 498.
7.
C. Kelly. H. W. Sidebottom, J. Treacy and O. J. Nielsen. Chem. Phys. Lett. 218
9.
H. Niki, J. Chen and V.
2
(1994)
8
9
.
.
Res. Chem. Intermed. 20
J. J. Szente and E. W. Kaiser, Chem.
0. E. C. Tuazon and R. Atkinson, J. Atmos. Chem. 16 (1993) 301.
277.
Young,
(1994)
Lett. 197 (1992) 149.
Phys.
M. M.
Maricq,
1
1
1. E. C. Tuazon and R. Atkinson, J. Atmos. Chem. 17
179.
(1993)
1
1
2. J. Sehested and T.
Environ. Sci. Technol. 27 (1993) 146.
Wallington,
3. T. J. Wallington. W. F. Schneider. D. R. Worsnop, O. J. Nielsen, J. Sehested, W. J.
Debruyn and J. A. Shorter, Environ. Sci. Technol. 28 (1994) 320 A.
1
4. T. E.
O. J. Nielsen, J. Sehested, T. J.
M. D.
Hurley and W.
Mogelberg,
Wallington,
F. Schneider, Chem.
Lett. 225
(1994)
375.
Phys.
1
5. O. V. Rattingan, D. M. Rowley, O. Wild, R. L. Jones and R. A. Cox, J. Chem. Soc.
Faraday Trans. 90 (1994) 1819.
1
6. M. M.
J. J.
M. D.
Hurley and T.
J.
Wallington, J. Phys.
Chem. 98
Maricq,
Szente,
(
1994) 8962.
1
1
7. A.
and R. W. Carr, Chem. Phys. Lett. 238 (1995) 9.
Bhatnagar
8. T. J. Wallington, W. F. Schneider, J. Sehested and O. J. Nielsen, Faraday Discuss.
00 (1995) 55.
9. M. Kanakidou, F. J. Dentener and P. J. Crutzen, J. Geophvs. Res. 100 (1995) 18781.
1
1
2
2
0. A. McCulloch and P. M. Midgley, Atmos. Environ. 30 (1996) 601.
1. H. M. McNair and E. J. Bonelli. Basic Gas
Berkeley 1969.
Consolidated Printers,
Chromatography,
2
2
2
2
2
2
2. F. A. Hohorts and J. M. Shreeve, Inorg. Synth. 11 (1967) 143.
3. A. J. Arvia and P. J. Aymonino, Spectrochim. Acta 18 (1962) 1299.
4. J. R. Durig and D. W. Wertz, J. Mol. Spectros. 25 (1968) 467.
5. H. Di Loreto and J. Czarnowski. J. Fluorine Chem. 74 (1995) 199.
6. J. R. Durig, J. F. Davis and G. A.
J. Mol. Struct. 346 (1995) 197.
Guirgis,
7. P. J. Aymonino, J. Inorg. Nucl. Chem. 27 (1965) 2675.
2
2
8. J. Czarnowski, Int. J. Chem. Kinet. 28 (1996) 489.
9. C. Corvaja, F. Cremonese, W. Navarini, C. Tonelli and V. Tortelli, Tetrahedron Lett.
36
(1995) 3543.
3
3
0. K. R. Ryan and I. C. Plumb, Inter. J. Chem. Kinet. 16 (1984) 591.
1. J. J. Russell, J. A. Seetula, D. Gutman. F. Danis, F.
P. D. Lightfoot, R.
Caralp,
Lesclaux, C. F. Melius and S. M. Senkan, J. Phys. Chem. 94 (1990) 3277.
2. F. Danis, F.
M. T. Rayez and R. Lesclaux, J. Phys. Chem. 95 (1991) 7300.
3
3
Caralp.
3. F. F. Fenter. P. D.
313.
4. W. C.
Lightfoot. J.
T. Niiranen and D. Gutman, J. Phys. Chem. 97 (1993)
P. Andrews, J. H. Moore and J. A. Tossell,
5
3
3
R. N.
.
Nottingham,
Int. J. Chem. Kinet. 26 (1994) 749.
R. A. Cox, J. N. Crowley. M. Destriau, G. D. Hayman, M. E. Jenkin,
Rudolph,
5. P. D.
Lightfoot,
G. K. Moortgat and F. Zabel, Air Pollution Research
40, Organic
Peroxy
Report
Radicals, Kinetics, Spectroscopy and Tropospheric Chemistry, published by Com-
mission of the European Communities 1993.
3
6. R. Lesclaux, A. M. Dognon and F.
Caralp, J.
Photochem. Photobiol. A: Chem. 41
(
1987) 1.
3
7. G. D. Hayman. M. E. Jenkin, T. P. Murrells and C. E. Johnson, Atmos. Environ. 28
1994) 421.
(
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Thermal Gas-Phase Oxidation of CCLCC1,
O, in Presence of CF,OF
197
by
3
3
4
4
8. A. A. Jemi-Alade, P. D. Lightfoot and R. Lesclaux, Chem. Phys. Lett. 179 (1991)
19.
9. T. J. Wellington, T. Ellermann and O. J. Nielsen, Res. Chem. Intermed. 20 (1994)
65.
0. T. E. Mogelberg, J. Sehested, O. J. Nielsen and T. J. Wallington, J. Phys. Chem. 99
1995) 16932.
1. H. F. Andersson, J. A. Dahlberg and R. Wettstrom, Acta Chem. Scand. 29 (1975)
1
2
(
473.
4
4
4
2. E. Sanhueza, I. C. Hisatsune and J. Heicklen, Chem. Rev. 76 (1976) 801.
3. R. Atkinson and S. M. Aschmann, Int. J. Chem. Kinet. 19 (1987) 1097.
4. E. C. Tuazon, R. Atkinson, S. M. Aschmann, M. A. Goodman and A. M. Winer, Int.
J. Chem. Kinet. 20 (1988) 241.
4
4
4
4
4
5
5. K. Kirchner, D. Helf, P. Ott and S. Vogt, Ber. Bunsenges.
Chem. 94 (1990) 77.
Phys.
6. K. K. Johri and D. D. DesMarteau, J. Org. Chem. 48 (1983) 242.
7. A. Sekiya and K. Ueda, Chem. Letters 1990, 609.
8. T. J.
L. M. Skewes and W. O.
Siegl, J.
Photochem. and Photobiol. A:
Wallington,
Chem. 45 (1988) 167.
9. R.
J. B. Cumming, S. Gordon and W. A. Mulac, Radiât.
Chem. 16
Cooper,
1980) 169.
0. J. M. Nicovich, S. Wang, M. L. McKee and P. H. Wine, J. Phys. Chem. 100 (1996)
80.
Phys.
(
6
5
5
5
5
5
5
5
5
1. J. Czarnowski, Inter. J. Chem. Kinet. 18 (1986) 1323.
2. J. Czarnowski, J. Chem. Soc, Faraday Trans. 2, 83 (1987) 579.
3. A. A. Shoikhet, M. A. Teitelboim and V. I. Vedeneev, Kinet
i
Katal. 24 (1983) 225.
4. N. Y. Wang and F. S. Rowland, J. Phys. Chem. 89 (1985) 5154.
5. H. Adachi, N. Basco and D. G. L. James, Int. J. Chem. Kinet. 11 (1979) 1211.
6. Z. Czarnowski and J. Czarnowski, J. Chem. Soc, Faraday Trans. 89 (1993) 451.
7. J. Troe, J. Phys. Chem. 83 (1979) 114.
8. S. C. Chan, B. S. Rabinowitch, J. T. Bryant, D. L.
and S. Pavlou, J. Phys. Chem. 74 (1970) 3160.
Spicer, T.
Fujimoto. Y. N. Lin
5
6
6
9. G. L. Pratt and S. W. Wood, J. Chem. Soc.
Trans. 1, 80 (1984) 3419.
Faraday
0. W. Braun and M. Lenzi, Disc. Faraday Soc. 44 (1967) 252.
1. Handbook of Bimolecular and Termolecular Gas Reaction, Eds. J. A. Kerr and S. J.
Moss (CRC Press Inc., Boca Raton, Florida 1981), Vol. II.
6
2. J. C.
M. T.
116
Rayez, P.
(1987)
203.
Halwick, B.
R. Lesclaux and J. J.
Rayez,
Duguay,
Danneberg,
Chem.
Phys.
6
3. F. Wu and R. W. Carr, J. Phys. Chem. 96 (1992) 1743.
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