Reactions of chloroethenes with atomic chlorine in air at atmospheric pressure

Article abstract of DOI:10.1007/s11172-010-0158-4

Relative rate method at the temperature of 298 K and pressure of 1013 hPa and GC-MS detection were used for the study of kinetics of the reactions of Cl atoms with H₂C=CCl₂, cis-ClHC=CHCl, trans-ClHC=CHCl, ClHC=CCl₂, and Cl₂C=CCl₂. The reaction products were identified by FTIR spectroscopy. A mechanism for the atmospheric degradation of chloro-ethenes has been suggested.

Full text of DOI:10.1007/s11172-010-0158-4

Russian Chemical Bulletin, International Edition, Vol. 59, No. 4, pp. 754—760, April, 2010
754
Reactions of chloroethenes with atomic chlorine in air
at atmospheric pressure
I. I. Morozov,a C. Nielsen,b O. S. Morozova,a E. S. Vasiliev,a and E. E. Loukhovitskayaa
aN. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences,
4 ul. Kosygina, 119991 Moscow, Russian Federation.
Fax: +7 (495) 137 8318. Eꢀmail: morozov@chph.ras.ru
bUniversity of Oslo, Department of Chemistry,
Nꢀ0315 Oslo, Norway
Relative rate method at the temperature of 298 K and pressure of 1013 hPa and GCꢀMS
detection were used for the study of kinetics of the reactions of Cl atoms with H2C=CCl2,
cisꢀClHC=CHCl, transꢀClHC=CHCl, ClHC=CCl2, and Cl2C=CCl2. The reaction products
were identified by FTIR spectroscopy. A mechanism for the atmospheric degradation of chloroꢀ
ethenes has been suggested.
Key words: atmospheric chemistry, chloroethenes, reaction rate constant, FTIR spectroꢀ
scopy, reaction mechanism, chlorination, atomic chlorine.
Chloroethenes (CE) are widely used in industry in the
study their reaction channels and products during atmoꢀ
synthesis of polyvinyl chloride and other polymers, as well
as solvents for chemical purification and degreasing. They
are formed as side products in the process of plastic waste
burning in industry if the burning regime is not optimum.
The worldwide production of dichloroethenes (DCE)
reached 3.5 million metric tons in 1998 and during period
1996—2004 increased on average by 2.5% every year.1 The
combustion process of CE and chlorineꢀcontaining polyꢀ
mers leads to the emission of chlorineꢀcontaining gases to
the environment, which can have negative consequences.
Recirculation and burning of polymers is an important
problem, too: in the processes indicated, significant emisꢀ
sion of gases during pyrolysis and combustion is also posꢀ
sible, for which allowance should be made during optiꢀ
mization of production parameters. At present, techꢀ
nological studies in the field under consideration are
mainly devoted to the aspects of the "endꢀofꢀlife" of
polyvinyl chloride. The main accent is made on the
danger of smoke gases evolved on combustion of polyviꢀ
nyl chloride and their purification during the combusꢀ
tion process. Almost nothing is known about possible
natural sources of halogenated ethylenes. Biogenic emisꢀ
sion of CE is rare. Halogenation of simple biogenic
alkenes and terpenes with atomic chlorine and bromine
was studied only in laboratory experiments.2,3 Halogeꢀ
nated alkenes in the amount of halogen atoms formed in
atmosphere have the same effect on the environment
in industrial regions, as the reservoir forms of halogens
in the Arctic at the time of polar sunrise.4 To evaluate
the influence of CE on the atmosphere, it is necessary to
spheric degradation.
Though there is a number of publications on this quesꢀ
tion, elementary chemical processes of CE degradation in
atmosphere are not entirely determined. Earlier,5 we have
studied kinetics of recombination of peroxy radicals
(CHCl2CHClO2, CHCl2CCl2O2, and CCl3CCl2O2 ) formed
in the chlorineꢀinitiated oxidation processes of 1,2ꢀdiꢀ
chloroethene, trichloroethene, and tetrachloroethene,
respectively. However, the question about the reacꢀ
tion products remained open. The results published6 on
the study of the reaction products and channels during
atmospheric degradation of CE are rather difficult to comꢀ
pare, since reactions of CE with atomic chlorine have
been studied by different methods under different condiꢀ
tions. In the present work, we performed systematic study
of the kinetics and mechanism of the reaction of CE with
chlorine atoms at atmospheric conditions in a smog chamꢀ
ber using GCꢀMS and FTIR spectroscopy. The reaction
rate constants of Cl atoms with CE (C2Cl4, C2HC13,
cisꢀ and transꢀisomers of ClHC=CHCl, and H2C=CCl2)
are found and major gasꢀphase products of these reactions
are determined.
Experimental
Relative rate method. The rate constants of the reaction of
CE with Cl atoms were found by the relative rate (RR) method,
in which the ratio of the reaction rate constants of molecules S
and R (kS and kR) with Cl atoms is determined (by the slope
coefficient of the line in the coordinates of Eq. (3), see further).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 739—744, April, 2010.
1066ꢀ5285/10/5904ꢀ0754 © 2010 Springer Science+Business Media, Inc.

Chlorination of chloroethenes in air
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
755
The extent of the reagent transformations in the course of the
reaction was measured.
graphic column with internal diameter of 0.25 mm and a 0.25ꢀμm
film of polyethylene glycol was used in all the experiments. The
temperature of 100 °C was maintained in the region of the samꢀ
ple inlet and the loop. For the control of the inflow conditions of
reagents, chemically inert gas (reference gas), perfluoroꢀ1,2ꢀ
dimethylcyclohexane, was feeded into the reactor. The change
of concentrations in Eq. (3) can be neglected, since the dilution
was insignificant.
S + Сl
R + Сl
P,
P,
(1)
(2)
where P are the products.
The use for the "soft" CI of [CH5]+ ions allowed us to avoid
fragmentation and overlap of mass spectra. A full mass spectrum
of reagents and reaction products at the outlet of the gas chroꢀ
matograph was analyzed at the beginning of an experiment to
reveal characteristic mass peaks, which gave us a possibility to
operate with selected individual ions. This allowed us to deterꢀ
mine individual compounds quantitatively and decrease the backꢀ
ground noise, as well as to remove the overlapping effect in the
case of incomplete chromatographic separation. Relative conꢀ
centrations of the reagents were found by the measurement of
the ions [MH]+ signal values.
The smog chamber was equipped with a system of mirrors
providing multiple passage of the IR irradiation through it (White
Cell), the optical distance was 120 m. The absorption IR spectꢀ
rum in the smog chamber was recorded on a Bruker FTIR
spectrometer (IFSꢀ88).
In this method the rate constant of the reaction of moleꢀ
cules R with the Cl atom must be known. Molecules S and R are
consumed exclusively in the reactions with Cl atoms and are not
involved into the secondary reactions with any other species.
Therefore, the following expressions operate for the relative rate
constant krel
:
ln{[S]0/[S]t} = krelln{[R]0/[R]t}, krel = kS/kR,
(3)
where [S]0, [R]0, [S]t, and [R]t are the concentrations of moleꢀ
cules S and R at the initial and t moments of time, respectively.
The krel value can be determined from the graph of the depenꢀ
dence of ln{[S]0/[S]t} versus ln{[R]0/[R]t}. The data of indepenꢀ
dent experiments were analyzed using the least squares method,
in which allowance was made for the uncertainties in the conꢀ
centration of reagents.7
Experimental apparatus (Fig. 1). Kinetic measurements were
performed at the pressure of 1013 15 hPa and temperature of
298 2 K in the synthetic air of a 250ꢀL smog chamber (the
chamber length was 220 cm, its diameter, 40 cm) made of stainꢀ
less steel treated by electropolishing. For the photolysis of moꢀ
lecular chlorine, lowꢀpressure mercury luminescent lamps with
luminescent coating of the inside wall, emitting the longꢀwave
The losses of CE due to the nonphotochemical reactions in
the smog chamber was monitored before each experiment, they
never exceeded 1—2% of total consumption of the compound
during the experiment. To determine photostability, the UV irꢀ
radiation of CE for 5 min was performed before beginning each
experiment. The change in intensity of the mass spectra did not
exceed 1—2%. Thus, the losses of compound due to the nonphoꢀ
tochemical reactions and direct photolysis were insignificant.
For recording IR spectra of the reaction products of Cl atoms
with CE, special experiments were carried out without addition
of molecule R.
Reactants. Synthetic air ([CO] + [NOx] < 0.1 ppm,
[CnHm] < 1 ppm) was purchased from AGA. Commercial (Fluꢀ
ka) CE (C2C14, C2HC13, cisꢀ, transꢀClHC=CHCl, H2C=CCl2)
of analytically pure grade were used in this work. Purity of CE
was additionally controlled by GCꢀMS, in all the cases the conꢀ
tent of CE in the sample was >98%. Partially fluorinated ether
(C2F5CH2OMe) from Fluorochem Ltd. (>98%) was used in exꢀ
periments.
UV radiation (Philips TLDꢀ08, λ
≈ 370 nm), were used. Chloꢀ
max
rine atoms during photodissociation were formed in the ground
electron state. The chamber temperature during experiments
was kept constant. The reaction mixture was analyzed in situ
using an Agilent 6890/5973 GCꢀMS instrument with chemiꢀ
cal ionization (CI). The gas chromatograph worked in isotherꢀ
mic conditions at 46 °C. Excessive constant pressure of ~5 hPa
was maintained in the reactor to guarantee a stationary current
of ~20 cm3 min–1. A sample of 0.5 cm3 was taken during the
inflow cycle into the gas chromatograph, which was diluted by
50 times before injection into the chromatographic column. Heꢀ
lium was used as a carrier gas. A 30ꢀm DBꢀWAXetr chromatoꢀ
5
Results and Discussion
1
2
Determination of the reaction rate constants by the
relative rate method. Partially fluorinated ether
C2F5CH2OMe (1) in concentration comparable with the
concentration of CE was used in all the experiments as the
compound competing with CE in the reactions with chloꢀ
rine atoms. The concentration of CE in the mixture at the
beginning of experiment usually was 2—6 ppm, whereas
the content of Cl2 in the chamber was 10—20 ppm.
The choice of compound 1 is due to the fact that the
rate constant of the reaction of this ether with atomic Cl
2
3
4
Fig. 1. The scheme of experimental apparatus: 1 is the smog
chamber, 2 are the low pressure luminescent lamps, 3 is the
GCꢀMS spectrometer, 4 is the FTIR spectrometer, 5 is the source
of the IR irradiation.
→
has been recently studied. For the reaction Cl + 1
P
(P are the products), the rate constant is found8 to be
4.0(0.8)•l0–11 cm3 molecule–1 s–1 (here and further, the

756
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
Morozov et al.
ln{[C2Cl4]0/[C2Cl4]t}
0.6
error of statistical analysis is given in parentheses 3σ). In
addition, relative concentrations of compound 1 are found
using the signal in the mass spectrum on the line at
m/z = 165, which is conveniently placed with regard to the
lines of CE under study.
0.4
0.2
0
Figure 2 shows the data on three independent experiꢀ
ments, in which the signal of C2Cl4 was measured on the
line at m/z = 167 [M + H] (C2Cl37Cl353H+). Analysis
of the data gives the following value for the ratio of the
reaction rate constants: kCl + C C /kCl + 1 = 1.12(0.12).
2
14
From this it follows that the absolute rate constant of
the reaction of Cl atoms with C2Cl4 is equal to
4.5(1.0)•l0–11 cm3 molecule–1 s–1 at 298 K. The known9
value for this rate constant, 4.0•l0–11 cm3 molecule–1 s–1
(Table 1), is very close to that obtained in our experiments.
The data from other experiments with CE are given in
Fig. 3 and the results in Table 1 are compared with the
values obtained by the direct measurements at room temꢀ
perature.
Study of the products. For determination of the reaction
products of Cl atoms with CE, the mixture contained reꢀ
agents in the same concentrations that in kinetic experiꢀ
ments. The difference was that reagent R has not been
placed into the smog chamber.
Figure 4 shows the IR spectra of a mixture of reagents
Cl2C=CCl2, Cl2, and air before and after photolysis, when
all the tetrachloroethene was consumed in the reaction
with chlorine atoms. The spectrum of the products is rathꢀ
er simple and mainly is formed by trichloroacetyl chloride
(CCl3COCl), as well as by small amount of phosgene
(CCl2O), which was inferred from the absorption bands
for the C=O and C—Cl functional group with the maxima
0
0.2 ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t}
Fig. 2. The dependence of ln{[C2Cl4]0/[C2Cl4]t} on
ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t} for 39 measurements in
three independent experiments; the result of linear regression
(errors 3σ): y = (–0.008 0.013) + (1.12 0.12)x.
at 1827 and 850 cm–1, respectively. Figure 5 shows the
IR spectra recorded for the reaction of ClHC=CCl2 with
Cl atoms. In the spectrum of the products, acetyl chloꢀ
rides CCl3COCl (with wave numbers 740, 802, 850, 988,
1790 cm–1) and CHCl2COCl (with wave numbers 587,
740, 802, 988, 1076, 1790, 1824 cm–1), as well as phosꢀ
gene and formyl chloride are identified. The IR spectra
recorded for the reaction of transꢀClHC=CHCl with Cl
atoms are shown in Fig. 6. The spectrum of the products is
almost identical to the spectrum recorded for the reaction
of cisꢀClHC=CHCl with Cl atoms and is a superposiꢀ
tion of the absorption spectra of dichloroacetyl chloride
(CHCl2COCl), phosgene, and formyl chloride (CHClO).
The latter compound can be identified by the C—H group
Table 1. The rate constants for the reaction of Cl atoms with chlorinated ethenes at 298 K
Compound
Cl2C=CCl2
krel(298 K)a
k(298 K)•1011
Methodb
Reference
/cm3 molecule–1 s–1
1.12(0.12)
04.5 (1.0)
03.9(0.3)
04.13(0.25)
04.0
08.7(1.8)
08.1(0.08)
09.8(2.1)
09.6(0.2)
12.2(2.5)
09.6(0.1)
13.2(2.8)
14.0(0.14)
12.7(0.25)
RRꢀGC/MS
FPꢀRF
RRꢀGC
Estimation
RRꢀGC/MS
RRꢀGC
RRꢀGC/MS
RRꢀGC
RRꢀGC/MS
RRꢀGC
RRꢀGC/MS
RRꢀFTIR
RRꢀGC
The present work
10
11
09
HClC=CCl2
2.17(0.14)
2.45(0.21)
3.06(0.17)
3.30(0.2)
The present work
11
transꢀHClC=CHCl
cisꢀHClC=CHCl
H2C=CCl2
The present work
11
The present work
11
The present work
11
11
H2C=CHCl
a
Measurements were performed using the reaction of Cl atoms with CF3CF2CH2OMe (1), for which
Cl + 1 = 4.0(0.8)•l0–11 cm3 molecule–1 s–1 at 298 K, as a comparison reaction.
k
b RRꢀGC/MS stands for the relative rate method in combination with GCꢀMS, FPꢀRF stands for the method of
resonance fluorescence in combination with a flowꢀtube reactor, RRꢀGC stands for the relative rate method in
combination with GC, RRꢀFTIR stands for FTIR spectroscopy in combination with a flowꢀtube reactor.

Chlorination of chloroethenes in air
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
757
ln{[HClC=CCl2]0/[HClC=CCl2]t}
0.6
ln{[cisꢀHCl2C=CCl2]0/[cisꢀHClC=CHCl]t}
a
b
0.8
0.6
0.4
0.2
0
0.4
0.2
0
0
0.1
ln{[transꢀHClC=CCl2]0/[transꢀHClC=CHCl]t}
0.2
ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t}
0
0.1
ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t}
c
d
ln{[CH2CCl2]0/[CH2CCl2]t}
0.8
0.6
0.4
0.2
0
0.1
0
0
0.02
ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t}
0
0.05 0.10 ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t}
Fig. 3. The dependence of ln{[S]0/[S]t} on ln{[C2F5CH2OMe]0/[C2F5CH2OMe]t} during the reaction with Cl atoms; S = ClHC=CCl2 (a),
cisꢀClHC=CHCl (b), transꢀClHC=CHCl (c), H2C=CCl2 (d); the result of linear regression (errors 3σ): y = (0.009 0.015) +
+ (2.17 0.14)x (a), y = (0.002 0.011) + (3.06 0.17)x (b), y = (0.004 0.006) + (2.45 0.21)x (c), y = (–0.011 0.014) + (3.30 0.20)x (d).
stretching band at 2933 cm–1 12
,
which overlaps with the
or Cl2HC—COCl. The ions with m/z 113 and 115
(Cl2HC—COH), 99 (CCl2O) were recorded in the system
Cl + transꢀClHC=CHCl. The peaks of low intensities
for the ions with m/z 113 and 115 (Cl2HC—COH),
77 (ClHC=C=O), and 65 (CHClO) were found in the
system Cl + cisꢀClHC=CHCl and the ions with m/z 113
(ClH2C—COCl), 99 (CCl2O), in the system Cl +
+ H2C=CCl2.
rotationꢀvibrational structure of HCl. Finally, Fig. 7 shows
the IR spectra recorded for the reaction of 1,1ꢀdichloroetꢀ
hene with Cl atoms. On the analysis of the spectra, chloꢀ
roacetyl chloride (ClCH2COCl) and phosgene were idenꢀ
tified as the products. Figure 8 illustrates a partial change
of the IR spectrum for this reaction. During the reaction,
a part of the spectrum characteristic of the C=C bond
disappears and absorption bands for the C=O bonds apꢀ
pear, which are characteristic of the CE transformation
products.
The data on the products identified by the analysis are
given in Table 2.
The FTIR spectroscopy data were complemented by the
GCꢀMS analysis. In this procedure, the photolysis prodꢀ
ucts were pumped off through a trap cooled by liquid niꢀ
trogen, then the trap was defrosted and the mixture was
analyzed. The products were analyzed by mass spectromꢀ
etry using CI to record [MH]+ ions. When products of the
reaction Cl + Cl2C=CCl2 were analyzed, only ions with
m/z 99 were reliably identified, that corresponds to phosꢀ
gene. The ions with m/z 163, 147, 99, and 65 were found in
the system Cl + ClHC=CCl2. Comparison with the IR
spectroscopic data allows us to state that the ions with
m/z 99, 65, and 147 can be assign to, respectively,
phosgene, CHClO, and one of the isomers Cl3C—COH
A (rel. units)
1.0
2
0.5
1
1000
1500
2000 ν/cm–1
Fig. 4. The IR spectra of Cl2C=CCl2 (1) and products of its
reaction with Cl atoms in air (2). Here and in Figs 5—7, the
spectra of the products are displaced along the ordinate axis.

758
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
Morozov et al.
A (rel. units)
Table 2. The products identified in the reactions of Cl atoms with
chlorinated ethenes in air (1 atm, 298 K)
2.0
Chlorinated
ethylene
Major
products
Minor
products
2
1.0
Cl2C=CCl2
ClHC=CCl2
Cl3C—COCl
Cl3C—COCl,
Cl2HC—COCl
CCl2O
CCl2O, CHClO;
HCl; CO
1
600 800 1000 1200 1400 1600 1800 ν/sm–1
trans, cisꢀClHC=CHCl Cl2HC—COCl
H2C=CCl2 ClH2C—COCl
CCl2O, CHClO;
HCl; CO
CCl2O, CHClO;
HCl; CO
Fig. 5. The IR spectra of ClHC=CCl2 (1) and products of its
reaction with Cl atoms in air (2).
A (rel. units)
Reaction rate. It is known that the reactions of CE
with Cl atoms have third order, but at the pressure of 1 atm
predominantly proceed in the high pressure regime.
Since many studies6 were performed at low pressures, their
results cannot be directly compared with the present work
data. The results obtained for the reaction of Cl with CE
are summarized in Table 1. Tetrachloroethene is the only
CE, for which the reaction rate constant value is recomꢀ
mended.9 The data obtained in the present work agree
with the results of systematic studies10,11 of the CE reacꢀ
tions kinetics. Note that in contrast to the values pubꢀ
lished earlier,11 the rate constant for the reaction of
cisꢀClHC=CHCl with atomic chlorine determined by us
is by ~30% higher than the rate constant for the reaction
of transꢀClHC=CHCl. However, the rate constants agree
within the indicated measurement errors. To sum up,
our data indicate a somewhat higher reaction rate of
cisꢀisomer CE with Cl atoms as compared to transꢀisoꢀ
mer. Similar behavior was also found for the reactions
with radicals •OH (see Refs 13 and 14) and •NO3.15,16
This was also confirmed by recent calculations using moꢀ
lecular orbital theory.17
1.5
1.0
2
0.5
1
0
1000
1500
2800 3200 ν/sm–1
Fig. 6. The IR spectra of transꢀClHC=CHCl (1) and products of
its reaction with Cl atoms in air (2).
A (rel. units)
1.5
1.0
2
0.5
1
0.0
1000
1500
2000 ν/sm–1
Fig. 7. The IR spectra of H2C=CCl2 (1) and products of its
reaction with Cl atoms in air (2).
Reaction mechanism. Trichloroacetyl chloride is the
major product found in the oxidation process of tetrachloꢀ
roethene with Cl atoms (see Table 2). This agrees with the
recent study,18 in which formation of 68% and 87% of
trichloroacetyl chloride in the atmosphere containing or
containing no NOx, respectively, was reported. The mechꢀ
anism of the reaction in the NOxꢀfree atmosphere is
as follows:
A (rel. units)
C=O
0.8
0.6
0.4
0.2
0
3
•
Cl + Cl2C=CCl2
Cl3C—CCl2
,
(4)
(5)
C=C
2
Cl3C—CCl2• + O2
Cl3C—CCl2O2 ,
•
1
•
Cl3C—CCl2O2• + RO2
Cl3C—CCl2O• + RO• + O2,
Cl3C—COCl + Cl,
(6)
(7a)
(7b)
1600
1700
1800
1900
ν/sm–1
Cl3C—CCl2O•
Cl3C—CCl2O•
Fig. 8. The change in the IR spectrum in the region
1500—2000 cm–1 of the reaction mixture Cl + O2 + H2C=CCl2
depending on the photolysis time: 0 (1), 120 (2), and 300 s (3).
CCl2O + •CCl3.

Chlorination of chloroethenes in air
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
759
Channel (7a) predominates over channel (7b). Here
and further in Schemes on mechanism of reactions, RO2
means peroxy radicals formed by oxidation of the main
compound. The sequence of the reactions similar to
(5)—(7a) will result in the transformation of radicals •CCl3
to the final product CCl2O.
In the reaction of trichloroethene, the major products
are acetyl chlorides Cl3C—COCl and Cl2HC—COCl, and
minor products are CCl2O and CHClO. In the work,19
oxidation of trichloroethene at 357 °C activated by the
photodissociation of chlorine has been studied and a conꢀ
clusion has been drawn that addition of Cl to the least
chlorinated carbon atom in trichloroethene is at least by
8 times more probable than addition to the most chloriꢀ
nated carbon atom. Our results indicate somewhat less
difference in the reactivity. A mechanism for the oxidaꢀ
tion of ClHC=CCl2 has been suggested, the first steps of
which are as follows:
The results obtained in the present work allows one to
suggest for isomers ClHC=CHCl the following mechaꢀ
nism of degradation initiated by the reaction with Cl atoms:
•
Cl + ClHC=CHCl
Cl2HC—CHCl•,
(16)
(17)
•
Cl2HC—CHCl• + O2
Cl2HC—CHClO2• + RO2
Cl2HC—CHClO2
,
•
Cl2HC—CHClO• + RO• + O2,
(18)
(19)
(20)
Cl2HC—CHClO• + O2
Cl2HC—CHClO•
Cl2HC—COCl + HO2
•CHCl2 + CHClO.
,
•
Analysis of the products shows that the reaction chanꢀ
nel (19) predominates over channel (20). Radicals •CHCl2
through the sequence of reactions similar to (17)—(19)
will further lead to the formation of additional amount of
CCl2O. Dichloroacetyl chloride formed in the reaction
(19) can further react with excess of Cl atoms forming
oxalyl chloride C2O2Cl2, which readily photodissociates
to Cl atoms and CO. Formyl chloride is thermally unstaꢀ
ble and easily decomposes to CO and HCl. Formation of
these products was inferred from analysis of the spectrum
(see Fig. 6).
Chloroacetyl chloride is the major product of
1,1ꢀdichloroethene oxidation with atomic chlorine, CCl2O
and CHClO are formed as well (no formation of CHClO
was found in Ref. 21). The fact that the IR spectrum of the
products does not exhibit trichloroacetaldehyde indicates
that addition of the Cl atom takes place predominantly to
the CH2 group. The following mechanism can be suggestꢀ
ed for the oxidation:
•
Cl + ClHC=CCl2
Cl2HC—CCl2
,
(8a)
(8b)
(9)
Cl + ClHC=CCl2
•ClHC—CCl3,
Cl2HC—CCl2• + O2
Cl2HC—CCl2O2 ,
•
•
HCl2C—CCl2O2• + RO2
HCl2C—CCl2O• + RO• + O2,
Cl2HC—COCl + Cl,
(10)
(11a)
(11b)
(12)
Cl2HC—CCl2O•
Cl2HC—CCl2O•
•ClHC—CCl3 + O2
•CHCl2 + CCl2O,
•O2CHCl—CCl3,
•
•O2CHCl—CCl3 + RO2
•
•OCHCl—CCl3 + RO• + O2,
(13)
(14)
(15)
Cl + H2C=CCl2
ClH2C—CCl2
,
(21)
(22)
•
•OCHCl—CCl3 + O2
OClC—CCl3 + HO2
CHClO + •CCl3.
,
ClH2C—CCl2• + O2
ClH2C—CCl2O2• + RO2
ClH2C—CCl2O2
,
•
•OCHCl—CCl3
•
•
•
ClH2C—CCl2O•+ RO• + O2,
ClH2C—CClO + Cl,
(23)
(24а)
(24b)
The radicals CHCl2 and CCl3 formed will produce
the final products, phosgene and CCl2O, in further reacꢀ
tions. Since the major registered oxidation products are
CCCl3COCl and CHCl2COCl (see Table 2), it is obvious
that the reactions (11a) and (14) are the main channels for
the formation of the products from the intermediate alkoxy
radicals (RO).
ClH2C—CCl2O•
ClH2C—CCl2O•
•CH2Cl + CCl2O.
The only direct channel for the formation of CHClO
can involve radicals •CH2Cl, formed in the channel (24b).
Therefore, the reaction channel (24a) predominates over
channel (24b).
Atmospheric implications. Degradation of CE in the
oxidation with Cl atoms leads to the formation of chloroꢀ
acetyl chlorides, phosgene, and formyl chloride. Hydrolyꢀ
sis of phosgene gives CO2 and HCl, whereas formyl chloꢀ
For cisꢀ and transꢀClHC=CHCl in the reactions with
Cl, formation of dichloroacetyl chloride was mainly obꢀ
served together with insignificant yields of products CCl2O
and CHClO. This contradicts the data in Ref. 20, accordꢀ
ing to which the main reaction gives product CHClO,
with the formation of CCl2O and isomerization of
ClHC=CHCl through the secondary channels.

760
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 4, April, 2010
Morozov et al.
B. J. FinlaysonꢀPitts, R. E. Huie, V. L. Orkin, Chemical
Kinetics and Photochemical Data for Use in Atmospheric Studꢀ
ies. Evaluation Number 15, National Aeronautics and Space
Administration, Jet Propulsion Laboratory, California Instiꢀ
tute of Technology, California, 2006.
ride is thermally unstable and decomposes to CO and HCl
or, alternatively, can hydrolyze in atmospheric drops to
yield formic and hydrochloric acids. Chloroacetyl chloꢀ
rides will hydrolyze in drops forming partially chlorinated
acetic acids, the influence of which on the environment is
not yet completely established at present.
10. J. M. Nicovich, S. Wang, M. L. McKee, P. H. Wine, J. Phys.
Chem., 1996, 100, 680.
11. R. Atkinson, S. M. Aschmann, Int. J. Chem. Kinet., 1987,
19, 1097.
12. H. G. Libuda, F. Zabel, E. H. Fink, K. H. Becker, J. Phys.
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13. J. P. D. Abbatt, J. G. Anderson, J. Phys. Chem., 1991,
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14. E. C. Tuazon, R. Atkinson, S. M. Aschmann, M. A. Goodꢀ
man, A. M. Winer, Int. J. Chem. Kinet., 1988, 20, 241.
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This work was partially financially supported by the
Federal Agency for Science and Innovations (State Conꢀ
tract 02.740.11.5176), the Division of Chemistry and Maꢀ
terials Science of the Russian Academy of Sciences,
Scandinavian Fund for the Baltic Countries and the
NorthꢀWest of Russia, and the NATO (Grant CLGꢀ
ESP.EAP.CLG 983035).
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Received January 30, 2009;
in revised form February 15, 2010