Thermal decomposition of 2,5-dimethylfuran. Experimental results and computer modeling

Article abstract of DOI:10.1021/jp982772b

The thermal reactions of 2,5-dimethylfuran were studied behind reflected shock waves in a pressurized driver single pulse shock tube over the temperature range 1070-1370 K and overall densities of ～3 × 10^-5 mol/ cm³. A large number of products resulting from unimolecular cleavage of the ring and consecutive free radical reactions were obtained under shock heating. A methyl group migration from C(2) to C(3) in the ring with the elimination of CO produces four isomers of C₅H₈ in unimolecular processes. An additional unimolecular process is the decomposition of 2,5-dimethylfuran to CH₃CO and C₄H₅ which is an important initiator of free radical reactions. Ejection of a hydrogen atom from the methyl group in the molecule is another channel for initiation of free radical reactions in the system. The 2,5-dimethylfuryl radical, which is obtained in the process of H-atom ejection, decomposes in channels similar to those of 2,5-dimethylfuran to produce, among other products, C₅H₇, which is the precursor of cyclopentadiene. The major decomposition product found in the post shock mixtures is carbon monoxide. The rate constant of its overall formation is estimated as k_CO = 10^15.81exp(-75.1 × 10³/RT) s^-1 where R is expressed in units of cal/(K mol). Other products that were found in the postshock samples in decreasing order of abundance were C₄H₄, C₂H₂, and CH₄ in roughly the same abundance, C₂H₄, C₂H₆, CH₂=CH-CH=CH₂, cyclopentadiene p-C₃H₄, and a-C₃H₄ and 2-methylfuran. Other isomers of C₄H₆, C₅H₆ and C₅H₈, and some additional products were found in very small quantities. The total decomposition of 2,5-dimethylfuran in terms of a first-order rate constant is given by: k_total = 10^16.22exp(-77.5 × 10³/RT)s^-1. An oxygen-carbon mass balance among the decomposition products is obtained. A reaction scheme composed of 50 species and some 180 elementary reactions accounts for the product distribution over the temperature range covered in this study. First-order Arrhenius rate parameters for the formation of the various reaction products are given, a reaction scheme is suggested, and results of computer simulation and sensitivity analysis are shown. Differences and similarities among the reactions of furan, 2-methylfuran, and 2,5-dimethylfuran are discussed.

Full text of DOI:10.1021/jp982772b

J. Phys. Chem. A 1998, 102, 10655-10670
10655
Thermal Decomposition of 2,5-Dimethylfuran. Experimental Results and Computer
Modeling
Assa Lifshitz,* Carmen Tamburu, and Ronen Shashua
Department of Physical Chemistry, The Hebrew UniVersity, Jerusalem 91904, Israel
ReceiVed: June 25, 1998; In Final Form: September 10, 1998
The thermal reactions of 2,5-dimethylfuran were studied behind reflected shock waves in a pressurized driver
-
5
single pulse shock tube over the temperature range 1070-1370 K and overall densities of ∼3 × 10 mol/
3
cm . A large number of products resulting from unimolecular cleavage of the ring and consecutive free
radical reactions were obtained under shock heating. A methyl group migration from C(2) to C(3) in the
ring with the elimination of CO produces four isomers of C
unimolecular process is the decomposition of 2,5-dimethylfuran to CH
5
H
8
in unimolecular processes. An additional
CO and C which is an important
3
4 5
H
initiator of free radical reactions. Ejection of a hydrogen atom from the methyl group in the molecule is
another channel for initiation of free radical reactions in the system. The 2,5-dimethylfuryl radical, which is
obtained in the process of H-atom ejection, decomposes in channels similar to those of 2,5-dimethylfuran to
produce, among other products, C H , which is the precursor of cyclopentadiene. The major decomposition
5 7
product found in the post shock mixtures is carbon monoxide. The rate constant of its overall formation is
estimated as kCO ) 101 exp(-75.1 × 10 /RT) s where R is expressed in units of cal/(K mol). Other
5.81
3
-1
products that were found in the postshock samples in decreasing order of abundance were C
H
4 4
, C
, and a-C
, and some additional products were found in
very small quantities. The total decomposition of 2,5-dimethylfuran in terms of a first-order rate constant is
2 2
H , and
CH
4
in roughly the same abundance, C
2
H
4
4
, C
2
H
6
, CH
2
dCH-CHdCH
2
, cyclopentadiene p-C
3
H
4
3 4
H
and 2-methylfuran. Other isomers of C
H
6
, C
5
H
6
and C H
5 8
given by: ktotal ) 101 exp(-77.5 × 10 /RT) s . An oxygen-carbon mass balance among the decomposition
products is obtained. A reaction scheme composed of 50 species and some 180 elementary reactions accounts
for the product distribution over the temperature range covered in this study. First-order Arrhenius rate
parameters for the formation of the various reaction products are given, a reaction scheme is suggested, and
results of computer simulation and sensitivity analysis are shown. Differences and similarities among the
reactions of furan, 2-methylfuran, and 2,5-dimethylfuran are discussed.
6.22
3
-1
I. Introduction
In the second channel, breaking the O-C(5) and the C(2)-
C(3) bonds in the ring yields CO and 1-butyne
We have recently published a detailed investigation on the
thermal decomposition of 2-methylfuran in a single pulse shock
1
tube, covering the temperature range 1070-1370 K at total
-
5
3
densities of ∼3 × 10 mol/cm . A large number of products
were obtained under shock heating. It was shown that the
unimolecular decomposition follows two parallel channels. They
are 1,2 hydrogen atom migration from C(5) to C(4) and a methyl
group migration from C(2) to C(3) in the ring.
whereas in the second mode O-C(5), C(2)-C(3), and C(3)-
C(4) are broken to yield CO, C2H2, and C2H4
Each channel was then followed by two parallel modes of
ring cleavage. In the first channel, breaking the O-C(2) and
the C(4)-C(5) bonds in ring yields CO and different isomers
of C4H6
The four isomers of C4H6 were 1,3-butadiene, 1-butyne, 1,2-
butadiene, and 2-butyne. The total decomposition of
2
-methylfuran in terms of a first-order rate constant was found
1
6.22
3
-1
to be ktotal ) 10
exp(-77.5 × 10 /RT) s . A reaction
scheme composed of 36 species and some 100 elementary
reactions could account for the observed product distribution.1
We are not aware of another detailed study involving doubly
substituted furans such as dimethylfuran. We are aware,
whereas breaking of the O-C(2) and the C(3)-C(4) bonds
yields CH2CO and two isomers C3H4
2
however, of one VLPP study of 2,5-dimethylfuran where only
the overall decomposition rate was determined from which the
high-pressure limit rate constant was evaluated.
1
0.1021/jp982772b CCC: $15.00 © 1998 American Chemical Society
Published on Web 12/10/1998

10656 J. Phys. Chem. A, Vol. 102, No. 52, 1998
Lifshitz et al.
In this investigation we present data on the product distribu-
about 50 min. A typical chromatogram of 0.5% 2,5-dimethyl-
furan in argon shock heated to 1238 K is shown in Figure 1.
Carbon monoxide was analyzed on a 2 m molecular sieve 5
Å column at 35 °C. It was reduced at 400 °C to methane prior
to its detection using a Chrompak methanyzer with a carrier
gas composed of 50% hydrogen and 50% argon. These analyses
gave the ratio [CO]/[CH4]. From these ratios and the known
methane concentration obtained in the Porapak N analyses, the
concentration of CO could be calculated for each run. The ratio
tion in shock heated mixtures of 2,5-dimethylfuran. A detailed
mechanism is suggested, a reaction scheme which includes
unimolecular decompositions, dissociative attachments, and free
radical reactions is composed, and computer simulation is
performed.
II. Experimental Section
1
. Apparatus. The thermal reactions of 2,5-dimethylfuran
were studied behind reflected shocks in a pressurized driver,
2 mm i.d. single-pulse shock tube. The tube and its mode of
[CO]/[CH4] in a standard mixture of methane and carbon
monoxide was determined periodically in order to verify a
complete conversion of the latter to methane in the methanyzer.
In the course of analyzing the raw data we encountered some
separation problems which were solved by using the SIM mode
of a Hewlett-Packard model 5970 mass selective detector
connected to a Hewlett-Packard model 5890 gas chromatograph.
The peaks of 1-butyne and 1,2-butadiene were hidden under a
large peak of C4H4. Two peaks of C5H8 were hidden under a
larger peak of cyclopentadiene. The procedure of determining
the magnitude of the hidden peaks is described in detail in the
5
3
operation have been described in an earlier publication and
will be given here only very briefly.
The driven section was 4 m long and the driver had a variable
length up to a maximum of 2.7 m. It could be varied in small
steps in order to tune for the best cooling conditions. A 36 L
dump tank was connected to the driven section at 45° angle
near the diaphragm holder in order to prevent reheating by
reflection of transmitted waves. The driven section was
separated from the driver by a Mylar polyester film of various
thickness depending upon the desired shock strength.
Before each test the tube was pumped down to approximately
1
article on the decomposition of 2-methylfuran.
We have carried out also a separate series of experiments in
order to verify the presence or absence of ketene and/or methyl
ketene in the postshock mixtures. Methylketene can be formed
by a unimolecular decomposition of 2,5-dimethylfuran. Ketene
and methyl ketene tend to react with small quantities of water
absorbed in various location on the way to the GC and produce
acetic and propionic acids which are also absorbed and hard to
analyze. The postshock mixtures in this series of experiments
were collected in bulbs containing small quantities of methyl
alcohol. In this way, methyl acetate is formed from ketene and
methyl propionate from methyl ketene. The latter can be, at
least qualitatively, analyzed. We did not identify any methyl
propionate in the post shock mixtures and only traces of methyl
acetate
-
5
3
× 10 Torr. After performing an experiment, gas samples
were collected from the tube through an outlet in the driven
3
section (near the end plate) in 150 cm glass bulbs and were
then analyzed on a Carlo-Erba Model VEGA-2000 gas chro-
matograph using a flame ionization detector. Reflected shock
temperatures were calculated from the extent of decomposition
of 1,1,1-trifluoroethane which was added in small quantities to
the reaction mixture and served as an internal standard. Its
decomposition to CH2dCF2+HF is a first-order unimolecular
reaction which under the temperature and pressure conditions
4
14.8
of this investigation has a rate constant of kfirst ) 10 exp(-
3
-1
7
4.0 × 10 /RT) s . Reflected shock temperatures were
calculated from the relation:
The concentrations of the reaction products C5(pr)i were
calculated from their GC peak areas from the following
1
AT
5
T ) -(E/R)/ ln - ln(1 - ø)
(I)
relations:
[
{
}]
C (pr) ) A(pr ) /S(pr )(C (2,5-dimethylfuran) /
5
i
i t
i
5
0
where t is the reaction dwell time and ø is the extent of
decomposition defined as
A(2,5-dimethylfuran) ) (II)
0
ø ) [CH dCF ] /([CH dCF ] + [CH CF ] )
C (2,5-dimethylfuran) )
5 0
2
2 t
2
2 t
3
3 t
p %(2,5-dimethylfuran)(F /F )/100RT (III)
1
5
1
1
The additional reflected shock parameters were calculated from
the measured incident shock velocities using the three conserva-
tion equations and the ideal gas equation of state. Dwell times
of approximately 2 ms were measured with an accuracy of (5%.
A(2,5-dimethylfuran) )
0
A(2,5-dimethylfuran) + 1/6ΣN(pr )×A(pr ) /S(pr ) (IV)
t
i
i t
i
5
Cooling rates were approximately 5 × 10 K/s.
2
. Materials and Analysis. Reaction mixtures containing
In these relations C5(2,5-dimethylfuran)0 is the concentration
of 2,5-dimethylfuran behind the reflected shock prior to
decomposition, and A(2,5-dimethylfuran)0 is the calculated GC
peak area of 2,5-dimethylfuran prior to decomposition (eq IV)
where A(pri)t is the peak area of a product i in the shocked
sample. S(pri) is its sensitivity relative to 2,5-dimethylfuran,
and N(pri) is the number of its carbon atoms. F5/F1 is the
compression behind the reflected shock, and T1 is the temper-
ature of the shock tube.
The identification of the reaction products was based on their
GC retention times but was also assisted by a Hewlett-Packard
model 5970 mass selective detector. The sensitivities of the
various products to the FID were determined relative to 2,5-
dimethylfuran from standard mixtures. The areas under the GC
peaks were integrated with a Spectra Physics Model SP4200
0.5% 2,5-dimethylfuran and 0.1% 1,1,1-trifluoroethane in argon
were prepared manometrically and stored in 12 L glass bulbs
at 700 Torr. Both the bulbs and the line were pumped down to
-
5
∼
10 Torr before the preparation of the mixtures. 2,5-
dimethylfuran was obtained from Aldrich Chemical Co. and
showed only one GC peak. The argon used was Matheson
ultrahigh purity grade, listed as 99.9995%, and the helium was
Matheson pure grade listed as 99.999%. All the materials were
used without further purification.
The gas chromatographic analyses of the postshock mixtures
were performed on two columns with flame ionization detectors.
The analyses of all the products except for CO were performed
on a 2 m Porapak N column. Its initial temperature of 35 °C
was gradually elevated to 190 °C in an analysis which lasted

Thermal Decomposition of 2,5-Dimethylfuran
J. Phys. Chem. A, Vol. 102, No. 52, 1998 10657
in argon, covering the temperature range 1070-1370 K. Extents
of pyrolysis as low as a few hundredths of one percent were
determined. Details of the experimental conditions and the
distribution of reaction products are given in Table 1. The
percent of a given product in the total sample, as shown in the
table, corresponds to its mole fraction in the postshock mixture
irrespective of the number of its carbon atoms.
The balance of oxygen vs carbon among the decomposition
products is shown in Figure 2. The concentrations of carbon
monoxide and methylfuran are plotted against one-sixth the sum
of the concentrations of all the decomposition products (includ-
ing carbon monoxide and methylfuran) each multiplied by the
number of its carbon atoms. One-sixth is the ratio of oxygen
to carbon in the reactant molecule. The 45° line in the figure
represents a complete mass balance. As can be seen, there is
no major deviation from an oxygen-carbon balance over the
temperature range of the investigation.
Figure 1. Gas chromatogram of a post-shock mixture of 0.5% 2,5-
dimethylfuran in argon heated to 1238 K. The numbers on the peaks
are multiplication factors. The measured peak heights are lower than
those on the figure by these factors. (a) CH
, (e) C , (f) allene, (g) propyne, (h) 1,3-butadiene, (i) C
,2-butadiene, 1-butyne, (j) 2-butyne, (k) C , (l) furan, 1,4-pentadiene,
m) 1,2-pentadiene, (n) cyclopentadiene, (o) 1,3-pentadiene, (p) 1,2,4-
4 2 4 2 6
, (b) C H , (c) C H , (d)
C
2
H
2
3
H
6
4 4
H ,
1
4 2
H
Figure 3 shows the rate constant for the total decompositions
of 2,5-dimethylfuran, calculated as a first-order rate constant
from the relation:
(
pentatriene, 2-pentyne, (r) 2-methylfuran, (s) C
furan.
6 6
H , (t) 2,5-dimethyl-
ktotal ) -ln{[2,5-dimethylfuran] /[2,5-dimethylfuran] }/t
t
0
(V)
The value obtained is ktotal ) 1015.43 exp (-73.1 × 10 /RT)
s- where R is expressed in units of cal/(K mol). The rate
constants for the total decompositions of furan and 2-methyl-
furan are also shown for comparison. As can be seen, the total
decomposition of 2,5-dimethylfuran is higher than that of
3
1
2
-methylfuran which is already higher than that of furan.
Figures 4-6 show three examples of Arrhenius plots of the first-
order production rates of CO, C2H2, and 1,3-butadiene calculated
from the relation
Figure 2. Oxygen-carbon mass balance among the decomposition
products. The 45° line represent a perfect carbon-oxygen mass balance.
[product]t
kproduct
)
ktotal
(VI)
[
reactant] - [reactant]t
0
Values of E obtained from the slopes of such lines for the
reaction products and their corresponding preexponential factors
are summarized in Table 2. It should be mentioned that the
parameters for the product formation do not represent elementary
unimolecular reactions owing to further decompositions and
involvement of free radical reactions. This presentation simply
provides a convenient way to summarize general rates.
IV. Discussion
1
. Unimolecular Processes; Production of Stable Prod-
ucts. We have recently demonstrated, in the study on the
1
decomposition of 2-methylfuran, that the latter undergoes a
number of unimolecular decomposition channels to produce both
stable molecules (C4H6 isomers and CO) and unstable inter-
mediates which are responsible for the propagation of free
radical reactions. The major unimolecular channel in the
decomposition of 2-methylfuran is a 1,2-H-atom migration from
C(5) to C(4) in the ring, followed by elimination of carbon
monoxide and formation of several C4H6 isomers
Figure 3. Arrhenius plot of the first-order rate constant for the overall
decomposition of 2,5-dimethylfuran. The rate constant is calculated
t 0
from the relation: ktotal ) ln{[2,5-dimethylfuran] /[2,5-dimethylfuran] }/
1
6.22
3
-1
t. The value obtained is: ktotal ) 10 exp(-77.5 × 10 /RT) s . The
total decomposition of 2-methylfuran and furan is also shown for
comparison.
computing integrator and were transferred after each analysis
to a PC for data reduction and graphical presentation.
III. Results
To determine the distribution of reaction products, some 70
tests were run with mixtures containing 0.5% 2,5-dimethylfuran
and to a much lesser extent a migration of the CH3 group from

TABLE 1: Experimental Conditions and Product Distribution in Percent
5
C
5
× 10
dimethyl-
furan
1,3-
butadiene
1,2-
butadiene
cyclo-
pentadiene
1,2,4-
pentatriene
1,3-penta-
diene
1,2-
pentadiene
3
T
5
(K)
(mol/cm )
t (ms)
1-butyne
2-butyne
C
4
H
4
C
4
H
2
-
2
-3
-2
-2
-2
1
081
086
093
094
095
096
098
099
106
106
107
113
118
124
125
126
126
128
128
128
129
138
144
146
149
149
149
153
154
157
167
171
173
185
187
187
187
198
200
200
202
203
204
206
208
213
216
232
234
237
2.97
3.19
3.02
2.76
3.17
2.15
3.15
2.94
3.07
2.86
3.02
3.01
2.98
3.01
2.79
2.15
2.96
2.79
2.77
3.01
2.87
2.90
2.15
2.53
2.84
2.92
2.45
2.80
2.15
2.73
2.71
2.72
2.65
2.64
2.86
2.52
2.72
2.57
2.15
2.15
2.68
3.16
2.49
2.46
2.68
2.59
2.55
2.44
2.19
2.92
2.00
2.15
2.10
2.00
2.20
2.20
2.20
2.15
2.25
1.94
2.30
2.15
2.20
2.25
2.00
2.25
1.92
1.88
2.20
2.30
2.20
2.30
2.20
2.25
2.30
2.25
2.25
2.30
2.30
1.96
2.20
2.25
2.20
2.02
2.25
2.20
2.30
2.08
2.20
2.20
2.15
1.94
2.00
2.25
1.96
2.16
2.15
2.15
1.94
2.04
98.61
98.70
97.63
97.63
97.92
96.73
97.26
97.12
96.80
95.87
95.90
95.56
91.78
91.58
91.99
91.57
93.39
91.99
89.68
92.65
91.24
87.58
85.65
85.13
83.36
80.81
79.07
76.91
79.66
82.92
70.22
67.96
65.26
67.56
54.01
55.73
54.35
54.71
48.65
45.02
42.32
55.64
50.07
42.44
44.76
43.46
39.96
27.51
37.17
30.48
8.93 × 10
0.115
0.187
0.130
0.179
0.245
0.200
0.215
0.272
0.265
0.293
0.314
0.610
0.592
0.486
0.647
0.402
0.618
0.807
0.585
0.664
0.863
1.500
1.104
1.148
1.348
1.514
1.532
1.536
0.961
2.064
2.209
2.374
1.656
3.001
2.887
2.955
2.283
3.414
3.982
3.728
2.300
2.447
3.754
3.177
2.657
3.906
4.514
3.378
3.581
1.38 × 10
2.00 × 10
3.67 × 10
2.60 × 10
3.66 × 10
5.05 × 10
4.31 × 10
4.73 × 10
6.82 × 10
6.52 × 10
7.44 × 10
8.91 × 10
1.88 × 10
2.01 × 10
1.68 × 10
2.27 × 10
1.41 × 10
2.24 × 10
2.92 × 10
2.12 × 10
2.44 × 10
3.62 × 10
6.82 × 10
5.17 × 10
5.59 × 10
6.57 × 10
7.37 × 10
7.85 × 10
7.96 × 10
5.17 × 10
0.124
1.63 × 10
2.15 × 10
3.60 × 10
2.52 × 10
3.48 × 10
4.77 × 10
3.92 × 10
4.24 × 10
5.52 × 10
5.34 × 10
5.94 × 10
6.55 × 10
0.129
3.37 × 10
6.00 × 10
0.115
3.83 × 10
9.93 × 10
0.176
0.149
0.224
0.232
0.219
0.262
0.268
0.593
0.586
0.434
0.630
0.356
0.422
1.050
0.630
0.708
1.003
1.734
1.490
1.453
1.614
2.000
1.901
1.866
1.227
3.014
3.162
3.407
2.170
4.366
4.347
4.515
3.706
5.277
6.223
5.994
3.590
4.095
6.083
4.744
4.458
6.468
7.608
6.200
6.145
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
3
3
3
3
3
3
3
3
3
3
3
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
7.93 × 10
0.0021
2.16 × 10
9.78 × 10
4.50 × 10
2.95 × 10
3.15 × 10
2.59 × 10
3.23 × 10
4.00 × 10
5.63 × 10
4.06 × 10
4.43 × 10
7.01 × 10
8.12 × 10
7.14 × 10
3.91 × 10
1.35 × 10
6.12 × 10
2.81 × 10
1.85 × 10
2.00 × 10
1.63 × 10
2.03 × 10
2.52 × 10
3.55 × 10
2.56 × 10
2.81 × 10
4.45 × 10
5.18 × 10
4.56 × 10
-3
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-3
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
0.156
0.113
0.122
0.101
0.126
0.162
0.207
0.165
0.185
0.300
0.356
0.291
0.173
0.0046
0.003
-3
1.75 × 10
0.0032
0.0027
0.0033
0.0042
0.0059
0.0043
0.0048
0.0077
0.0091
0.0081
0.0044
-4
8.1 × 10
0.128
0.105
0.141
-3
-3
-3
2.34 × 10
2.00 × 10
8.72 × 10
-2
8.80 × 10
0.136
-2
-2
-2
-2
0.177
0.128
0.146
0.195
0.344
0.255
0.267
0.314
0.353
0.360
0.362
0.228
0.501
0.536
0.583
0.415
0.754
0.725
0.742
0.581
0.871
1.016
0.953
0.588
0.626
0.963
0.818
2.500
1.010
1.171
0.876
0.927
0.624
0.415
0.436
0.693
0.951
0.915
0.953
0.911
1.106
1.015
1.091
0.0159
0.0106
0.0111
0.0177
0.0243
0.0234
0.0244
0.0233
0.0283
0.0261
0.0281
0.140
8.95 × 10
5.96 × 10
6.23 × 10
9.60 × 10
0.129
0.123
0.127
0.121
0.148
0.134
0.143
-2
-2
9.32 × 10
9.74 × 10
0.149
0.200
0.190
0.196
0.187
0.227
0.205
-2
-3
-3
-3
1.45 × 10
4.77 × 10
6.81 × 10
4.67 × 10
-2
1.20 × 10
-3
-2
8.52 × 10
1.37 × 10
0.0087
0.220
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
-2
-2
-2
1.47 × 10
1.84 × 10
2.08 × 10
2.38 × 10
3.35 × 10
3.45 × 10
3.77 × 10
4.17 × 10
5.70 × 10
5.92 × 10
4.79 × 10
4.56 × 10
3.55 × 10
6.11 × 10
7.87 × 10
5.41 × 10
7.35 × 10
9.40 × 10
9.04 × 10
8.87 × 10
2.79 × 10
3.64 × 10
1.41 × 10
0.680
1.873
2.120
1.355
2.586
2.610
2.654
2.453
3.125
3.460
3.168
0.0439
0.0493
0.0560
0.0389
0.0704
0.0711
0.0723
0.0724
0.0883
0.0977
0.0901
0.322
0.353
0.397
0.256
0.460
0.464
0.472
0.441
0.531
0.588
0.535
0.212
0.234
0.263
0.172
0.309
0.312
0.318
0.300
0.362
0.401
0.366
0.139
0.152
0.119
0.219
0.210
0.215
0.181
0.275
0.320
0.304
0.188
0.202
0.314
0.269
0.632
0.345
-2
-2
-2
-2
-2
3.46 × 10
3.14 × 10
4.40 × 10
7.72 × 10
7.60 × 10
-2
-2
-2
-2
4.95 × 10
5.07 × 10
9.17 × 10
5.30 × 10
0.330
0.121
0.195
2.446
3.424
4.022
2.952
3.808
4.203
3.547
3.752
0.0735
0.0986
0.122
0.0912
0.114
0.135
0.119
0.127
0.429
0.571
0.726
0.501
0.614
0.645
0.559
0.586
0.294
0.392
0.480
0.348
0.427
0.458
0.400
0.420
0.424
0.319
0.341
0.105
0.156

TABLE 1: (Continued)
5
C
5
× 10
dimethyl-
furan
1,3-
butadiene
1,2-
butadiene
cyclo-
pentadiene
1,2,4-
pentatriene
1,3-penta-
diene
1,2-
pentadiene
3
T
5
(K)
(mol/cm )
t (ms)
1-butyne
2-butyne
C
4
H
4
C
H
4 2
-
2
1
238
240
260
262
264
265
267
272
283
299
303
305
311
314
324
342
344
350
352
2.34
2.26
2.29
2.40
2.16
2.24
2.29
2.32
2.18
2.65
3.25
2.88
2.07
3.23
3.34
2.63
1.90
2.58
1.82
2.04
2.10
2.10
2.10
2.10
2.05
2.10
2.00
2.00
2.14
2.13
2.14
1.85
1.98
2.04
2.08
1.90
2.16
1.80
30.10
21.04
13.97
14.29
10.07
9.50
10.35
13.23
8.72
7.44
6.27
5.25
3.99
4.21
4.15
2.79
2.66
1.72
3.01
3.228
4.773
4.967
4.592
4.767
5.073
4.840
3.655
4.474
3.549
3.067
4.013
3.902
3.356
2.463
2.080
2.010
1.686
2.296
0.309
0.458
0.484
0.447
0.463
0.492
0.469
0.351
0.418
0.311
0.263
0.340
0.319
0.269
0.176
0.131
0.124
0.838
1.238
1.276
1.177
1.220
1.300
1.235
0.926
1.120
0.864
0.741
0.961
0.925
0.791
0.542
0.452
0.434
0.356
0.482
7.75 × 10
5.731
8.280
8.870
7.870
8.620
9.033
8.643
7.200
8.994
7.740
7.050
9.509
8.650
8.018
6.388
6.809
6.162
5.230
7.040
0.152
0.255
0.363
0.313
0.373
0.400
0.395
0.319
0.530
0.553
0.652
0.719
0.746
0.725
0.800
1.314
1.011
1.495
1.224
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0.105
4.240
4.136
3.592
3.481
3.861
3.840
3.512
3.323
3.025
2.660
3.227
2.547
2.492
1.878
1.461
0.900
0.960
1.020
0.141
0.154
0.135
0.133
0.148
0.151
0.144
0.144
0.636
0.587
0.507
0.489
0.541
0.535
0.492
0.445
0.393
0.343
0.413
0.321
0.312
0.230
0.172
0.107
0.111
0.120
0.456
0.433
0.375
0.363
0.402
0.400
0.370
0.341
0.118
0.112
0.105
0.112
0.119
0.101
0.108
-
-
2
2
9.83 × 10
8.51 × 10
0.125
0.135
0.166
0.137
0.138
0.113
0.104
0.0658
0.073
0.0811
0.270
0.328
0.258
0.252
0.190
0.146
9.14 × 10
9.64 × 10
0.104
-
-
-
-
-
2
2
2
2
2
9.42 × 10
9.02 × 10
6.88 × 10
7.24 × 10
3.91 × 10
6.47 × 10
5.39 × 10
-2
-
2
-2
-2
9.80 × 10
-
2
0.130
5
T
5
(K)
C
5
× 10
t (ms)
CO
CH
4
C
2
H
4
C
2
H
6
C
2
H
2
C
3
H
6
allene
propyne
methylfuran
6 6
C H
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2
2
2
2
2
2
2
2
2
2
2
2
2
2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
-2
1
081
086
093
094
095
096
098
099
106
106
107
113
118
124
125
126
126
128
128
128
129
138
144
146
149
149
149
153
154
2.97
3.19
3.02
2.76
3.17
2.15
3.15
2.94
2.86
3.07
3.02
3.01
2.98
3.01
2.79
2.15
2.96
2.77
3.01
2.79
2.87
2.90
2.15
2.53
2.45
2.92
2.84
2.80
2.15
2.00
2.15
2.10
2.00
2.20
2.20
2.20
2.15
1.94
2.25
2.30
2.15
2.20
2.25
2.00
2.25
1.92
2.20
2.30
1.88
2.20
2.30
2.20
2.25
2.25
2.25
2.30
2.30
2.30
0.745
0.578
1.002
1.178
0.969
1.262
1.054
1.151
1.785
1.426
1.633
1.807
3.462
3.489
3.316
3.417
3.481
3.834
3.253
3.687
3.542
4.890
5.853
5.694
8.562
8.124
6.609
9.866
7.556
0.296
0.298
0.610
0.365
0.434
0.681
0.533
0.552
0.738
0.678
0.783
0.879
1.616
1.650
1.900
1.656
1.207
1.820
1.410
1.713
1.614
2.120
2.16 × 10
1.64 × 10
3.01 × 10
3.40 × 10
2.74 × 10
4.28 × 10
2.75 × 10
2.90 × 10
5.00 × 10
4.19 × 10
4.09 × 10
4.44 × 10
8.57 × 10
9.07 × 10
0.112
2.06 × 10
2.09 × 10
5.27 × 10
8.56 × 10
5.38 × 10
6.11 × 10
4.18 × 10
6.01 × 10
0.104
7.72 × 10
7.34 × 10
7.24 × 10
0.227
0.170
0.285
0.308
0.187
0.277
0.200
0.311
0.229
3.90 × 10
5.80 × 10
6.39 × 10
7.41 × 10
8.34 × 10
0.108
1.34 × 10
1.46 × 10
1.94 × 10
3.08 × 10
2.66 × 10
3.25 × 10
2.50 × 10
2.98 × 10
6.37 × 10
3.97 × 10
3.87 × 10
4.32 × 10
8.08 × 10
8.60 × 10
7.94 × 10
8.78 × 10
6.08 × 10
0.123
0.118
-3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2.08 × 10
0.231
0.163
-2
-2
1.27 × 10
4.00 × 10
-3
5.74 × 10
-2
1.16 × 10
0.415
0.431
0.279
0.360
-2
-3
8.15 × 10
7.64 × 10
-3
0.103
9.77 × 10
0.141
0.131
0.132
0.138
0.276
0.279
0.336
0.294
0.226
0.368
0.290
0.336
0.301
0.448
0.821
0.553
-2
-2
-2
-2
1.21 × 10
-2
1.38 × 10
0.532
0.521
0.671
0.799
0.439
0.824
0.451
0.795
-2
1.56 × 10
-2
3.07 × 10
-2
3.26 × 10
-
2
-2
4.23 × 10
2.94 × 10
4.03 × 10
-
2
0.133
5.00 × 10
2.57 × 10
5.17 × 10
5.85 × 10
4.00 × 10
3.68 × 10
5.22 × 10
0.111
-
-
-
2
2
2
-2
-2
8.29 × 10
-
2
0.113
-2
-2
-2
9.52 × 10
0.145
0.100
-
2
-2
-2
4.09 × 10
8.06 × 10
9.22 × 10
0.129
0.462
0.701
1.307
1.314
1.049
1.188
1.295
1.477
1.478
1.375
9.25 × 10
-
2
0.134
0.293
0.759
0.488
0.743
0.507
0.450
0.621
0.806
0.300
0.171
0.260
0.253
0.200
0.303
0.336
0.231
0.167
0.234
0.209
0.182
0.260
0.241
-
-
-
-
2
2
2
2
2.503
3.592
3.412
2.760
4.025
3.702
7.34 × 10
9.98 × 10
9.13 × 10
7.80 × 10
0.115
0.802
0.713
0.650
0.867
0.296
0.864
0.121

TABLE 1: Continued
5
T
5
(K)
C
5
× 10
t (ms)
CO
CH
4
C
2
H
4
C
2
H
6
C
2
H
2
C
3
H
6
allene
propyne
methylfuran
6 6
C H
-
2
-2
1
157
167
171
173
185
187
187
187
198
200
200
202
203
204
206
208
213
216
232
234
237
238
240
260
262
264
265
267
272
283
299
303
305
311
314
324
342
344
350
352
2.73
2.71
2.72
2.65
2.64
2.72
2.52
2.86
2.57
2.15
2.15
2.68
3.16
2.49
2.46
2.68
2.59
2.55
2.44
2.19
2.92
2.34
2.26
2.29
2.40
2.16
2.24
2.29
2.32
2.18
2.65
3.25
2.88
2.07
3.23
3.34
2.63
1.90
2.58
1.82
1.96
2.20
2.25
2.20
2.02
2.30
2.20
2.25
2.08
2.20
2.20
2.15
1.94
2.00
2.25
1.96
2.16
2.15
2.15
1.94
2.04
2.04
2.10
2.10
2.10
2.10
2.05
2.10
2.00
2.00
2.14
2.13
2.14
1.85
1.98
2.04
2.08
1.90
2.16
1.80
8.657
12.22
12.84
13.93
16.94
18.66
18.04
19.29
20.48
17.88
19.33
23.72
23.25
22.41
22.66
22.37
25.27
23.08
28.09
34.92
29.66
35.49
30.88
32.76
34.54
35.72
35.56
35.38
38.47
35.60
35.24
39.06
34.30
37.16
33.97
42.00
41.68
38.43
30.47
36.76
2.894
4.644
4.940
5.400
3.004
6.765
6.392
6.991
6.161
8.804
7.481
7.924
6.388
7.442
7.954
5.820
6.606
7.653
9.165
0.312
0.420
0.458
0.510
0.627
0.825
0.797
0.850
0.991
1.437
1.260
1.138
1.000
1.203
1.265
1.464
1.330
1.426
2.158
1.341
2.536
2.257
2.552
3.480
3.648
3.980
3.710
3.900
3.716
4.545
5.453
5.187
6.002
5.850
6.162
5.776
6.913
7.370
11.16
7.478
0.758
1.158
1.087
1.162
1.966
1.537
1.548
1.523
2.184
2.641
2.087
2.555
1.868
2.360
2.372
4.076
2.434
2.541
3.161
3.875
3.397
3.407
3.893
4.044
3.412
4.292
4.334
4.001
4.211
4.435
4.488
3.966
6.128
4.049
4.587
3.448
3.821
2.709
3.103
3.065
0.792
1.255
1.374
1.462
1.330
2.262
2.202
2.134
2.552
3.485
3.040
3.008
2.450
2.924
3.281
2.921
3.104
3.670
5.117
3.392
5.562
5.324
5.911
7.755
7.685
8.867
8.544
8.441
8.248
10.25
12.58
13.17
13.40
13.14
15.18
14.70
18.74
20.10
27.25
20.22
9.31 × 10
8.62 × 10
0.175
0.218
0.233
0.266
0.340
0.332
0.345
0.343
0.555
0.472
0.496
0.343
0.390
0.536
0.591
0.448
0.588
0.790
0.581
0.726
0.686
0.915
1.073
1.007
1.090
1.124
1.092
0.909
1.113
1.058
0.973
1.267
1.146
1.112
0.905
1.018
0.884
1.044
0.992
0.215
0.347
0.384
0.410
0.370
0.597
0.586
0.590
0.576
0.873
0.775
0.792
0.563
0.637
0.842
0.872
0.731
0.941
1.292
0.851
1.200
1.124
1.523
1.797
1.732
1.901
1.925
1.912
1.564
2.011
1.980
1.864
2.317
2.237
2.143
1.813
1.926
1.855
1.940
2.121
0.796
1.457
1.650
1.706
1.343
2.164
2.217
1.984
1.406
2.100
1.928
1.958
1.454
1.373
1.975
1.952
1.486
2.107
1.902
1.652
1.411
1.278
1.743
1.429
1.298
1.035
1.161
1.191
1.056
0.932
0.716
0.616
0.660
0.485
0.503
0.357
0.257
0.173
0.177
0.136
-
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
9.86 × 10
0.105
0.130
0.370
0.413
0.236
0.494
0.464
0.486
0.280
0.674
0.573
0.647
0.296
0.307
0.623
0.457
0.353
0.633
0.783
0.327
0.580
0.533
0.880
0.917
0.894
0.950
0.977
0.936
0.674
0.913
0.758
0.694
0.728
0.876
0.795
0.615
0.408
0.543
0.466
0.594
0.153
0.220
0.309
0.328
0.256
0.188
0.300
0.235
0.255
0.516
0.585
0.300
8.324
8.973
9.188
10.36
11.18
11.25
10.92
11.04
9.924
10.52
12.32
11.45
8.814
11.56
13.20
11.53
8.000
12.90
10.38
11.56
0.487
0.890
1.026
1.192
0.835
0.897
1.131
0.926
1.083
1.431
1.492
1.336
1.600
1.701
1.863
1.711
1.445
2.123
1.507

Thermal Decomposition of 2,5-Dimethylfuran
J. Phys. Chem. A, Vol. 102, No. 52, 1998 10661
TABLE 2: Arrhenius Parameters for the Production Rates
of the Various Products
products
log {A, s-1}
E, kcal/mol
total decomposition
16.22
15.25
20.37
15.61
18.31
18.66
19.15
16.55
15.98
14.26
14.46
15.81
13.94
18.11
18.87
18.06
16.02
19.55
17.47
17.61
10.80
77.5
76.3
110.3
81.6
103.3
94.1
106.7
83.8
89.0
75.4
77.4
75.1
67.4
94.7
97.1
92.1
85.2
104.7
91.9
82.5
53.0
1
1
1
2
C
C
,3-butadiene
,2-butadiene
-butyne
-butyne
4
H
H
4
4
2
cyclopentadiene
1
1
1
,2,4-pentatriene
,3-pentadiene
,2-pentadiene
CO
CH
Figure 4. Arrhenius plot of the first-order rate constant of the
production of carbon monoxide. The rate constant is calculated from
4
C
2
C
2
C
2
C
3
H
4
H
6
H
2
H
6
the relation: k(product) ) ktotal× [product]
t 0
/([2,5-dimethylfuran] -[2,5-
dimethylfuran] ).
t
allene
propyne
C H
6 6
methylfuran
C(2) to C(3) (or from C(5) to C(4)) in the ring.
1
As has been shown with 2-methylfuran, this process is
considerably slower than the one in which H-atom migrates.
Indeed, the concentrations of all the C5H8 isomers together are
much smaller than those of C4H6 in 2-methylfuran. They reach
a maximum around 1% of the total distribution whereas the
maximum sum of the concentrations of C4H6 in the decomposi-
tion of 2-methylfuran is around 10%.
Figure 5. Arrhenius plot of the first-order rate constant of the
production of acetylene.
To obtain stable C5H8 molecules after breaking the 2,5-
dimethylfuran ring, additional rearrangements, such as 1,2-, or
1
,4-H-atom migrations, must take place in the open C5H8
biradical together with CO elimination. These are, for example,
1
,2-migration
(
1)
(2)
(3)
(4) (5)
•
•
CH -CH -CHdC -CH f
3
3
CH -CHdCH-CHdCH (5f 4) (1,3-pentadiene)
3
2
•
•
CH -CH -CHdC -CH f
3
3
CH -CH -CtC-CH (3f 2) (2-pentyne)
Figure 6. Arrhenius plot of the first-order production of 1,3-butadiene.
3
2
3
•
•
CH -CH -CHdC -CH f
3
3
C(2) to C(3), with CO elimination and formation of 1-butyne.
CH -CHdCdCH-CH (3f 4) (2,3-pentadiene)
3
3
1
,4-migration
(
1)
(2)
(3)
(4) (5)
•
•
CH -CH -CHdC -CH f
3
3
CH -CH -CHdCdCH (5f 2) (1,2-pentadiene)
Although interisomerization among the various C4H6 isomers
does take place,6 it could be shown, based on computer
modeling, that their observed distribution could not be accounted
for unless a migration of a methyl group in addition to H-atom
migration had to be assumed. Thus the choice of the migration
process determined what isomers were formed.
A similar process involving 2,5-dimethylfuran produces C5H8
and CO. Since however, there are no H atoms in positions 2
or 5, this process requires a migration of a methyl group from
3
2
2
GC-MS analysis revealed the presence of four C5H8 isomers.
Two of them were hidden behind a large peak of cyclopenta-
diene and could be identified only by the SIM mode of the GC-
MS. This can be seen in Figure 7 where the GC peaks
corresponding to m/z 68 (C5H8) and 66 (C5H6) are shown as a
function of retention time. These two isomers were identified
as1,3- and 1,2-pentadiene by both retention time and mass

10662 J. Phys. Chem. A, Vol. 102, No. 52, 1998
Lifshitz et al.
reactions. The free radical initiation steps are therefore
important steps in the overall decomposition mechanism.
The initiation of free radicals can be divided into two classes
of reactions. Those in which the ring is intact and the others
where the ring is cleaved to produce unstable intermediates.
To the first class belongs the ejection of a H atom from the
methyl group in the molecule
and ejection of a methyl group from the ring
Figure 7. GC-MS chromatogram m/z 67 (the highest m/z in C
5 8
H
spectrum) and m/z 66 (C ) are shown as a function of retention time.
5 6
H
The C-H bond in the methyl group is the weakest bond in
spectrum. Additional two peaks of C5H8 that were outside the
range of cyclopentadiene appeared in very small quantities. They
were identified as 1,4-pentadiene and 2-pentyne. In view of
their extremely low concentrations they do not appear neither
in the experimental product distribution nor in the computer
simulation. Only the two larger C5H8 isomers were considered.
An additional unimolecular ring opening channel which yields
stable molecules is a simultaneous production of CO, C2H4, and
C3H4.
3
the molecule. It is a sp bond which is weakened by the â-γ
CdC double bond in the ring. It is estimated as D(CH2-H)
7
∼
88 kcal/mol, similar to the equivalent process in toluene. The
ejection of a hydrogen atom from the methyl group has a
reaction coordinate degeneracy of 6 so it is an important
initiation reaction that affects almost all the reaction products
in the system. The ejection of a methyl group from the ring,
on the other hand, is slower. The C-CH3 bond is strengthen
by the R-â double bond in the ring in comparison to a normal
C-CH3 bond and it is estimated as D(C-CH3) ∼98 kcal/mol.
Its contribution to the overall production of free radicals is much
smaller than that of the H-atom ejection reaction. Ejection of
a hydrogen atom from the ring is very slow in view of the high
C-H bond energy, D(C-H) ∼112 kcal/mol.
In the second class of reactions the ring opens in different
locations. These reactions are shown in the kinetic scheme
Table 3), as reactions 7-9.
Reactions similar to reactions 7 and 8 involving 2,5-
A similar process which produces CO, C2H4, and C2H2 was
(
1
assumed to take place in the decomposition of 2-methylfuran.
The relatively large concentration of C2H2 and C2H4 in the
decomposition of the latter could not be accounted for unless
this process was introduced into the reaction scheme. Indeed,
this process involving 2,5-dimethylfuran which yields in addition
to CO and C2H4 also allene and propyne is practically the only
source of the two C3H4 isomers. When this channel is removed
from the reaction scheme, the concentration of methylacetylene
at the low temperature range drops down by about a factor of
more than 20. At higher temperatures its concentration drops
by only 25% since free radical channels begin to contribute to
its production.
dimethylfuran appear in the decomposition scheme of
1
2-methylfuran. We have added here an additional decomposi-
tion reaction:
This reaction involves a 1,2-methyl group migration together
with a 1,4-H-atom migration from the migrating methyl to a
It is hard to asses the exact nature of this process. Cleavage
of the ring to produce C3H4 would leave, following methyl group
migration, methylketene. However, we could not identify even
traces of the latter among the decomposition product. We
believe that methylketene is not really formed in the process.
A decomposition to CO and C2H4 occurs prior to rearrangement
to a stable methylketene molecule. Although the formation of
CO and C2H4 requires about 10 kcal/mol more than the
formation of CH3(CH)CO, entropy considerations enhances the
formation of carbon monoxide and ethylene in the process of
ring cleavage. It should be mentioned that once methylketene
is formed, its further decomposition by H-atom or methyl group
elimination is very slow at the temperature range of the present
experiment.
carbon atom in the ring. Since CH CHCO further decomposes
2
to C H and CO quite rapidly, the production of acetylene, which
2
3
is formed by the dissociation of C H , highly depends on this
2
3
reaction. In fact, without its presence in the scheme, the
concentration of acetylene, which is among the species with
the highest concentrations, cannot be accounted for.
3. Consecutive Free Radical Reactions. Almost all the
reactions that take part in the kinetic scheme of 2,5-dimethyl-
furan decomposition are reactions that involve free radicals. In
addition to the unimolecular decompositions of the reactant that
produce free radicals, there are consecutive steps such as
abstractions, recombinations, dissociative attachments and uni-
molecular decompositions of unstable, free radical, intermedi-
ates.
2
. Unimolecular Processes: Production of Free Radicals.
a. Abstractions. We have introduced into the reaction
scheme abstraction reactions involving H atoms and free radicals
Except for the two unimolecular processes just discussed, all
other unimolecular reactions of 2,5-dimethylfuran are associated
with production of free radicals. Many of the decomposition
products of 2,5-dimethylfuran are formed by free radical
•
•
containing up to three carbon atoms namely, CH3 , C3H3 , and
•
C3H5 . Abstractions from 2,5-dimethylfuran by relatively high
•
•
concentration free radicals such as C4H5 and C5H5 were also

Thermal Decomposition of 2,5-Dimethylfuran
J. Phys. Chem. A, Vol. 102, No. 52, 1998 10663
TABLE 3: Reactions Scheme for Decomposition of 2,5-Dimethylfurana
reaction
number
reaction
A
E
k
f
k
r
∆S0
∆H0
ref
1
1
1
1
5
5
5
4
1
2
3
4
5
6
7
8
9
DMF f CO + 1,3-pentadiene
DMF f CO + 1,2-pentadiene
1.0 × 10
1.6 × 10
1.5 × 10
8.0 × 10
1.6 × 10
3.0 × 10
2.0 × 10
2.0 × 10
8.0 × 10
3.0 × 10
3.0 × 10
7.5 × 10
1.0 × 10
3.0 × 10
2.0 × 10
1.0 × 10
3.0 × 10
8.0 × 10
8.0 × 10
8.0 × 10
80.0 10
80.0 17
79.5 19
0.16
22
43.9
47.9
76.8
75.8
31.8
36.9
52.9
50.7
59.4
18.8
16.8
20.3
20.0
5.8
15.9 this work
31.9 this work
52.0 est
3
b
DMF f p-C
DMF f a-C
3
H
H
4
+ C
2
H
H
4
+ CO
+ CO
4.1 × 10
2.0 × 10
4.8 × 10
6.8 × 10
5.5 × 10
1.6 × 10
4.8 × 10
2.4 × 10
4.0 × 10
6.1 × 10
2.0 × 10
5.9 × 10
3.1 × 10
2.9 × 10
9.9 × 10
3.9 × 10
1.2 × 10
3.8 × 10
1.8 × 10
5.6 × 10
4.4 × 10
4.2
3
3
4
+ C
2
4
82.5
3.0
53.5 est
88.4 est
98.4 est
84.9 est
84.8 est
80.5 est
-11.2 est
-3.3 est
1.6 est
•
•
16
16
16
16
15
14
13
13
14
14
14
14
13
11
11
11
11
14
13
9
DMF f DMF(R) + H
86.0 14.8
•
•
DMF f MF(R2) + CH
3
96.0
0.49
•
•
DMF f CH
DMF f CH
3
CO + CH
2
-CtC-CH
3
85.0 28
85.0 28
82.0 37
•
•
10
7
3
CO + (CHCCHCH )
3
•
•
DMF f C
3
H
3
O + C H
3 5
•
CO•
CO•
13
10
11
12
13
12
12
10
10
10
9
7
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
6
6
6
6
6
6
6
6
6
7
7
7
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
DMF + H f 1,3-butadiene + CH
3
6.0
15.0
11.0
10.0
6.0
8.0
8.0
15.0
10.0
10.0
14.0
15.0
10.0
15.0
85.1
2.7 × 10
7.2 × 10
9.0 × 10
1.8 × 10
2.7 × 10
8.0 × 10
4.0 × 10
7.2 × 10
1.4 × 10
1.4 × 10
2.9 × 10
1.9 × 10
8.9 × 10
1.2 × 10
3.0
•
•
6
DMF + H f 2-butyne + CH
3
CO
•
7
DMF + H f 1,2-butadiene + CH
3
•
•
8
DMF + H f 1-butyne + CH
3
CO
2.3 est
•
•
9
DMF + H f CH
3
+ MF
-13.7 est
-5.9 est
-18.5 est
-19.3 est
-4.7 est
-3.2 est
-2.0 est
0.2 est
•
•
5
DMF + H f C
3
H
5
+ C
2
H
4
+ CO
52.1
4.2
•
•
8
DMF + H f DMF(R) + H
2
•
•
7
DMF + CH
3
f DMF(R) + CH
4
-2.4
-1.1
-2.2
-2.1
-4.3
1.1
-0.5
42.0
43.9
45.5
45.2
46.3
76.7
52.7
51.4
34.8
7.2
•
•
•
•
9
DMF + C
DMF + C
DMF + C
3
3
3
H
H
H
3
3 4
f DMF(R) + p-C H
•
10
9
3
3 4
f DMF(R) + a-C H
•
5
•
3 6
f DMF(R) + C H
•
9
10
11
9
DMF + CH
2
-CtC-CH
3
fDMF(R) + 2-butyne 8.0 × 10
•
•
1
2
10
9
DMF + (CHCCHCH
3
) fDMF(R) + 1-butyne
5.0 ×10
6.0 est
2.6 est
•
•
11
DMF + (c-C
5
H
5
) f DMF(R) + cyclopentadiene 5.0 × 10
1
1
1
1
1
1
5
5
5
5
5
5
MF f 2-butyne + CO
2.3 × 10
3.5 × 10
4.5 × 10
2.8 × 10
5.8 × 10
1.8 × 10
4.0 × 10
4.0 × 10
8.0 × 10
3.0 × 10
1.0 × 10
5.0 × 10
5.0 × 10
8.0 × 10
3.0 × 10
1.5 × 10
1.0 × 10
5.0 × 10
3.3 × 10
4.0 × 10
2.3 × 10
2.3 × 10
2.3 × 10
3.3 × 10
2.0 × 10
2.0 × 10
2.0 × 10
1.7 × 10
3.0 × 10
3.0 × 10
3.0 × 10
2.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
1.0 × 10
2.0 × 10
1.0 × 10
1.0 × 10
1.0 × 10
6.0 × 10
4.0 × 10
2.0 × 10
1.0 × 10
24.7
16.8
29.6
30.3
49.5
57.2
94.5
108.4
90.5
-16.4
-17.3
-2.6
-1.1
0.1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
MF f 1,3-butadiene + CO
MF f 1,2-butadiene + CO
MF f 1-butyne + CO
79.5 44
0.97
85.1
6.0
10
99
6.6 × 10
79.5 35
82.9 19
79.5 22
4
MF f p-C
MF f C
MF f CH
3
H
2
4
+ CH
+ C
2
CO
+ CO
4
2
H
3
2
H
4
4.0 × 10
6.1 × 10
6.1 × 10
1.2 × 10
3.0 × 10
3.8 × 10
1.2 × 10
3.8 × 10
2.0 × 10
1.1 × 10
1.8 × 10
4.2 × 10
1.8 × 10
1.3 × 10
1.3 × 10
1.0 × 10
3.8 × 10
4.2 × 10
2.6 × 10
3.2 × 10
9.1 × 10
1.3 × 10
•
•
16
16
15
14
13
12
12
11
14
16
15
15
15
15
15
15
15
15
14
15
14
15
10
10
14
8
CO + C
3
H
3
90.5
106.0
86.0
9.0
13.0
10.0
10.0
14.0
6.0
90.0
48.0
56.0
77.0
64.0
71.0
64.0
64.0
76.7
0.0
6.0
•
•
-2
MF f HCO + CH dCH-CHdCH
2
1.2 × 10
•
•
•
MF f MF(R1) + H
7.4
•
12
10
10
10
9
MF + H f MF(R1) + H
2
8.0 × 10
5.3 × 10
8.9 × 10
8.9 × 10
2.9 × 10
2.7 × 10
2.8
4.1 × 10
8.1 × 10
1.1 × 10
2.6 × 10
8.7 × 10
1.5 × 10
1.5 × 10
1.3 × 10
2.0 × 10
1.2 × 10
2.0 × 10
7.4 × 10
1.3 × 10
1.3 × 10
1.3 × 10
•
•
7
MF + CH
3
f MF(R1) + CH
4
0.6
1.9
0.8
0.9
•
•
10
10
9
MF + C
MF + C
MF + C
3
H
H
H
3
3
5
f MF(R1) + p-C
3
3
H
H
4
•
•
•
3
f MF(R1) + a-C
f MF(R1) + C
4
•
3
•
3
H
6
•
13
10
13
5
MF + H f furan + CH
3
7.5
-10.0
•
•
MF f furan(R) + CH
DMF(R) f CH
DMF(R) f CH
3
34.5
41.7
48.4
80.3
40.6
41.8
44.4
45.4
77.1
87.8 est
17.9 est
56.8 est
77.7 est
•
•
6
2
dCH-CHdCH-CH
2
+ CO
•
•
5
10
8
3
CO + C
+ C
dCCHCH
4 4
H
•
•
2
DMF(R) f p-C
3
H
4
2
H
3
+ CO
)•
•
4
5
MF(R1) f CO + (CH
2
2
26.0
35.5
52.1
65.1
80.9
1
1
1
1
1
•
•
2
5
MF(R1) f CO + CH dCH-CHdCH
2
•
•
4
8
MF(R1) f CH
2
CO + C H
3 3
•
•
4
10
9
MF(R1) f HCO + C
4
H
4
•
•
2
MF(R1) f C
2
•
H
2
+ C
MF(R2) + H f MF
2
H
3
+ CO
•
14
3
-4
-3
-2
-31.2 -112.1 est
•
•-CtC-CH
MF(R2) f CO + CH
2
3
70.0
0.0
65.0
65.0
65.0
65.0
46.9
-27.0
49.2
0.8 est
-97.8 est
21.0 est
•
•
14
3
furan(R) + H f furan
•
•
furan(R) f CO + C
3
H
3
64
2.0
1.7
5 31 .1 × 10
14.1
17.1
6.0
9.7
1
1
1
1
3
3
3
3
2
2-butyne f 1,3-butadiene
1,2-butadiene f 1,3-butadiene
1,2-butadiene f 2-butyne
1-butyne f 1,2-butadiene
1.9
-7.9
-12.8
-4.9
6
6
6
6
2
-1.6
-3.5
0.4
-36.1
-32.6
-30.4
-30.7
-33.1
2
2
65.0 87
-0.8
•
•
•
13
13
13
13
13
13
13
13
14
14
14
14
14
14
14
14
14
13
13
13
13
13
13
13
13
3
c
CH
CH
2
-CtC-CH
3
+ H f 2-butyne
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
58.0
54.0
50.0
45.0
53.0
6.8
6.8
6.8
6.8
5.0 × 10
-88.2 1*
-83.3 1*
-83.2 1*
-82.5 1*
-89.8 1*
•
2
-CtC-CH
3
+ H f 1,2-butadiene
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
7.2 × 10
7.3 × 10
1.8 × 10
1.4 × 10
5.4 × 10
3.9 × 10
2.6 × 10
1.3 × 10
6.5 × 10
•
•
(CHCCHCH
(CHCCHCH
3
) + H f 1,2-butadiene
•
•
3
) + H f 1-butyne
•
•
CHtC-CH
2
-CH
2
+ H f 1-butyne
1.7
•
•
-4
CH dCH-CHdCH
2
+ H f 1,3-butadiene
5.5 × 10
-32.7 -109.2 1*
•
•
(CH
(CH
2
dCCHCH
2
) + H f 1,2-butadiene
1.1
-29.9
-31.4
29.6
27.4
27.2
28.8
30.1
8.4
-86.9 1*
-99.7 1*
60.4 1*
60.3 1*
53.1 1*
•
•
-2
12
14
13
13
13
8
2
dCCHCH
2
) + H f 1,3-butadiene
1.3 × 10
9.3 × 10
2.7 × 10
4.0 × 10
1.3 × 10
1.2 × 10
3.0 × 10
5.2 × 10
1.1 × 10
4.1 × 10
•
•
(CHCCHCH
3
) f H + C
4
H
4
•
•
4
CH
2
-CtC-CH
3
f H + C
4
H
4
•
•
5
CHtC-CH
2
-CH
CH dCH-CHdCH
2
f H + C
4
H
4
•
•
6
2
f H + C
4
H
4
47.2
56.7
1
1
1
1
1
1
•
•
4
(CH
2
dCCHCH
2
4 4
) f H + C H
•
•
13
13
13
12
2-butyne + H f CH
2
-CtC-CH
3
+ H
2
-18.7
•
•
12
11
7
1,3-butadiene + H f CH dCH-CHdCH
2
+ H
) + H
+ H
2
5.1
3.8
4.9
2.4
•
•
1,3-butadiene + H f (CH
2
dCCHCH
-CtC-CH
2
2
-7.2
-23.5
•
•
1,2-butadiene + H f CH
2
3
2

10664 J. Phys. Chem. A, Vol. 102, No. 52, 1998
Lifshitz et al.
TABLE 3: Continued
reaction
number
reaction
A
E
k
f
k
r
∆S0
∆H0
ref
•
)• + H
14
14
14
13
13
13
13
13
13
13
12
12
12
12
12
12
12
12
12
12
12
12
12
12
11
11
11
11
11
11
11
13
9
7
7
7
7
7
7
7
8
8
8
8
8
8
8
8
8
8
9
9
9
9
9
9
9
9
9
9
00
01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
1,2-butadiene + H f (CH
2
dCCHCH
2
2
3.0 × 10
2.0 × 10
3.0 × 10
6.0 × 10
4.0 × 10
2.0 × 10
1.0 × 10
3.0 × 10
2.0 × 10
3.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
5.0 × 10
2.0 × 10
2.0 × 10
2.0 × 10
2.0 × 10
2.0 × 10
2.0 × 10
2.0 × 10
8.0 × 10
8.0 × 10
8.0 × 10
8.0 × 10
8.0 × 10
8.0 × 10
8.0 × 10
2.0 × 10
1.2 × 10
2.0 × 10
1.0 × 10
1.0 × 10
1.0 × 10
1.0 × 10
3.2 × 10
1.0 × 10
2.0 × 10
2.0 × 10
5.0 × 10
5.0 × 10
8.0 × 10
1.0 × 10
1.0 × 10
2.0 × 10
2.0 × 10
5.0 × 10
5.0 × 10
8.0 × 10
1.0 × 10
1.0 × 10
1.1 × 10
9.3 × 10
3.0 × 10
3.0 × 10
2.0 × 10
2.0 × 10
2.0 × 10
8.0 × 10
1.0 × 10
1.0 × 10
2.0 × 10
5.0 × 10
6.8 1.9 × 10 2.1 × 10
2.2 -19.9 1
3.1 -24.4 1
5.5 -17.1 1
1.9 -19.5 1
-2.8 -8.0 1
•
•
13
8
1-butyne + H f (CHCCHCH
3
) + H
2
6.8 1.3 × 10 1.5 × 10
•
•
13
9
1-butyne + H f CHtC-CH
2
-CH
2
+ H
-CtC-CH
+ (CH dCCHCH
2
6.8 1.9 × 10 1.3 × 10
•
•
11
7
2-butyne + CH
3
f CH
4
+ CH
2
3
11.5 5.9 × 10 8.8 × 10
•
)•
+ CH dCH-CHdCH
11
10
11
7
1,3-butadiene + CH
1,3-butadiene + CH
1,2-butadiene + CH
3
3
3
3
f CH
f CH
f CH
f CH
4
4
4
4
2
2
11.5 3.9 × 10 6.2 × 10
•
•
•
•
11
2
11.5 2.0 × 10 7.5 × 10
-1.5
1.5 1
•
10
+ CH
+ (CH
2
-CtC-CH
3
11.5 9.8 × 10 1.2 × 10
-1.6 -24.4 1
-4.3 -20.8 1
-3.5 -25.3 1
-1.1 -18.0 1
•
11
8
1,2-butadiene + CH
2
dCCHCH
2
)
11.5 2.9 × 10 5.9 × 10
•
•
11
7
1-butyne + CH
1-butyne + CH
3
f CH
f CH
f p-C
3
3
3
3
4
+ (CHCCHCH
3
)
11.5 2.0 × 10 4.3 × 10
•
•
11
8
3
4
+ CHtC-CH
2
-CH
-CtC-CH
+ (CH
2
11.5 2.9 × 10 3.7 × 10
•
•
10
9
2-butyne + C
3
H
3
3
H
4
+ CH
2
3
11.5 4.9 × 10 1.4 × 10
3.1 -4.9 1*
•
)•
10
12
12
8
1,3-butadiene + C
1,3-butadiene + C
1,2-butadiene + C
H
3
H
3
H
3
H
3
f p-C
f p-C
f p-C
f p-C
3
3
3
3
H
4
H
4
H
4
H
4
2
dCCHCH
2
12.0 4.0 × 10 1.2 × 10
-1.5
6.6 1*
-0.3 16.1 1*
-0.4 -9.8 1
-3.1 -6.2 1*
-2.2 -10.6 1*
0.1 -3.3 1*
2.1 -3.4 1,est
•
•
•
•
9
+ CH dCH-CHdCH
2
17.0 5.3 × 10 4.1 × 10
•
10
+ CH
+ (CH
2
-CtC-CH
3
12.0 4.0 × 10 9.6 × 10
•
10
10
9
1,2-butadiene + C
2
dCCHCH
2
)
12.0 4.0 × 10 1.6 × 10
•
•
10
1-butyne + C
1-butyne + C
2-butyne + C
3
3
3
H
3
H
3
H
3
f p-C
f p-C
f a-C
3
3
3
3
3
3
3
H
H
H
4
4
4
+ (CHCCHCH
3
)
12.0 4.0 × 10 1.7 × 10
•
•
•
10
10
9
+ CHtC-CH
2
-CH
-CtC-CH
+ (CH dCCHCH
2
12.0 4.0 × 10 1.0 × 10
•
10
+ CH
2
3
11.5 2.0 × 10 1.7 × 10
•
)•
10
12
12
9
1,3-butadiene + C
1,3-butadiene + C
1,2-butadiene + C
H
3
H
3
H
3
H
3
f a-C
f a-C
f a-C
f a-C
3
3
3
3
H
4
H
4
H
4
H
4
2
2
12.0 1.6 × 10 1.5 × 10
-2.6
8.1 1,est
•
•
•
•
9
+ CH dCH-CHdCH
2
18.0 1.4 × 10 3.3 × 10
-1.3 17.6 1,est
-1.4 -8.3 1,est
-4.1 -4.7 1,est
-3.3 -9.2 1,est
-0.9 -1.8 1,est
2.1 -2.2 est
•
10
+ CH
+ (CH
2
-CtC-CH
3
12.0 1.6 × 10 1.2 × 10
•
10
10
9
1,2-butadiene + C
2
dCCHCH
2
)
12.0 1.6 × 10 1.9 × 10
•
•
10
1-butyne + C
1-butyne + C
2-butyne + C
3
3
3
H
3
H
3
H
5
f a-C
f a-C
f C
3
3
3
3
3
H
H
4
+ (CHCCHCH
3
)
12.0 1.6 × 10 2.1 × 10
•
•
•
10
10
8
3
4
+ CHtC-CH
2
-CH
2
12.0 1.6 × 10 1.2 × 10
•
9
3
H
6
+ CH
2
-CtC-CH
3
12.0 6.4 × 10 9.3 × 10
•
)•
9
11
11
8
1,3-butadiene + C
1,3-butadiene + C
1,2-butadiene + C
H
5
H
5
H
5
H
5
f C
f C
f C
f C
3
3
3
3
H
6
H
6
H
6
H
6
+ (CH
2
dCCHCH
2
15.0 1.9 × 10 2.9 × 10
-2.5
9.3 est
•
•
•
•
7
+ CH dCH-CHdCH
2
25.0 3.4 × 10 1.3 × 10
-1.3 18.8 est
-1.4 -7.1 est
-4.1 -3.5 est
-3.2 -7.9 est
-0.9 -0.6 est
33.9 49.6 6
•
9
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
+ CH
+ (CH
2
-CtC-CH
3
•
12.0 6.4 × 10 7.5 × 10
9
10
9
1,2-butadiene + C
2
dCCHCH
2
)
12.0 6.4 × 10 1.3 × 10
•
•
9
1-butyne + C
1-butyne + C
3
H
H
5
f C
f C
3
H
H
6
+ (CHCCHCH
3
)
12.0 6.4 × 10 1.3 × 10
•
•
9
9
3
5
3
6
+ CHtC-CH
2
-CH
2
12.0 6.4 × 10 7.8 × 10
1
1
3
3
6
1,3-butadiene f C
1,3-butadiene f C
4
H
H
4
+ H
2
75.0 1.6
66.0 35
2.9 × 10
3.0 × 10
6
2
•
2
+ C
2
H
+ C
4
32.7 40.4 6
•
14
16
16
16
13
12
12
12
12
7
1,3-butadiene + H f C
2
H
3
2
H
4
5.0 2.7 × 10 1.0 × 10
8.9
3.0 est
•
•
2-butyne f C
3
H
3
+ CH
1,2-butadiene f C
3
82.0 46
1.9 × 10
41.7 84.1 est
38.2 79.2 1
38.5 78.4 1
32.1 43.3 17
29.7 90.4 est
38.5 96.4 est
2.0 -16.5 est
-4.5 -17.4 est
-4.3 -1.2 est
-3.3 -2.7 est
•
•
2
3
H
3
+ CH
3
79.0 1.5 × 10 5.0 × 10
•
•
2
1-butyne f C
1,3-pentadiene f c-C
1,3-pentadiene f CH
3
H
3
+ CH
3
78.0 2.3 × 10 4.6 × 10
13
5
H
6
+ H
2
64.5 53
90.0 0.59
97.0 0.11
1.9 × 10
1.3 × 10
3.1 × 10
•
+• H•
15
14
12
9
2
dCH-CHdCH-CH
2
•
16
1,3-pentadiene f CH dCH-CHdCH
2
+ CH
3
•
•
14
13
1,3-pentadiene + H f CH
2
dCH-CHdCH-CH
2
2
+ H
2
7.0 1.2 × 10 5.6 × 10
•
•
13
11
9
1,3-pentadiene + CH
3
f CH
dCH-CHdCH-CH
2
+ CH
4
11.5 2.0 × 10 1.8 × 10
•
•
12
10
11
10
10
13
12
9
1,3-pentadiene + C
1,3-pentadiene + C
1,3-pentadiene + C
3
3
3
H
3
H
3
H
5
f CH
f CH
f CH
2
2
2
dCH-CHdCH-CH
dCH-CHdCH-CH
dCH-CHdCH-CH
2
2
2
+ a-C
+ p-C
3
3
H
H
4
12.0 4.0 × 10 2.1 × 10
•
•
•
•
12
10
4
12.0 4.0 × 10 7.1 × 10
11
9
+ C
3
H
6
12.0 6.4 × 10 5.6 × 10
-4.3
0.0 est
•
•
16
3
1,2-pentadiene f (CH
1,2-pentadiene f C
2
dCCHCH
+ C
2
) + CH
3
71.0 3.9 × 10 5.3 × 10
33.2 70.9 est
37.0 74.9 est
-0.3 -22.5 est
-6.9 -23.4 est
-6.7 -7.2 est
-5.6 -8.7 est
-6.6 -6.0 est
28.4 49.8 est
18.6 30.4 est
32.3 85.8 18
4.7 -21.1 19,20
18.9 30.9 est
19.9 29.5 est
-1.9 -22.0 est
-1.7 -5.8 est
-0.6 -7.3 est
-1.6 -4.6 est
41.4 93.1 est
6.1 -21.0 est
1.0 -9.2 est
9.0 33.0 9
•
•
16
2
3
•
H
3
2
H
5
75.0 7.7 × 10 8.2 × 10
•
14
13
1,2-pentadiene + H f CH
2
dCdCH-CH -CH
2
3
+ H
2
7.0 1.2 × 10 1.6 × 10
•
•
13
11
8
1,2-pentadiene + CH
3
f CH
dCdCH-CH -CH
3
+ CH
4
11.5 2.0 × 10 5.1 × 10
•
•
12
10
10
10
10
12
12
13
8
1,2-pentadiene + C
1,2-pentadiene + C
3
3
3
H
3
H
3
H
5
f CH
f CH
f CH
2
2
2
dCdCH-CH -CH
3
3
3
+ a-C
+ p-C
3
3
H
H
4
12.0 4.0 × 10 6.3 × 10
•
•
•
12
10
dCdCH-CH -CH
4
12.0 4.0 × 10 2.1 × 10
•
11
9
1,2-pentadiene + C
dCdCH-CH -CH
+ C
+ H
3
•H
6
12.0 6.4 × 10 1.6 × 10
•
14
5
CH
CH
2
dCdCH-CH -CH
3
f CH
2
2
dCdCH-CHdCH
2
50.0 1.8 × 10 5.8 × 10
•
•
13
6
2
dCH-CHdCH-CH
f cyclopentadiene + H
40.0 1.0 × 10 1.8 × 10
•
•
15
cyclopentadiene f (c-C
5
H
5
) + H
85.0 1.5
1.3 × 10
•
)• + H
13
13
cyclopentadiene + H f (c-C
5
H
5
2
H
H
5.4 1.1 × 10 2.1 × 10
•
•
14
9
10
10
7
cyclopentadiene + H f C
2
H
H
3
+ a-C
3
4
31.0 1.1 × 10 2.2 × 10
•
•
14
9
cyclopentadiene + H f C
2
3
+ p-C
3
4
30.0 1.7 × 10 1.1 × 10
•
)•
13
11
cyclopentadiene + CH
3
f CH
f a-C
f p-C
4
+ (c-C
5
H
5
12.0 1.6 × 10 5.9 × 10
•
•
•
12
9
9
cyclopentadiene + C
cyclopentadiene + C
cyclopentadiene + C
3
3
3
H
3
H
3
H
5
3
H
H
4
+ (c-C
5
H
H
5
)
)
14.0 7.1 × 10 1.6 × 10
•
•
12
10
9
3
4
+ (c-C
5
5
12.0 1.6 × 10 1.2 × 10
•
11
9
9
f (c-C
5
H
5
) + C
3
•
H
6
12.0 6.4 × 10 2.3 × 10
•
16
12
8
CH
CH
CH
2
2
2
dCdCH-CHdCH
dCdCH-CHdCH
dCdCH-CHdCH
-CHdCH-CHtCH
-CHdCH-CHtCH f C
2
2
2
f C
+ H f C
+ CH
3
•
H
3
+ C
2
H
3
92.0 0.82
1.4 × 10
•
14
13
3
H
3
+ C
3
2
H
+ C
4
5.4 1.1 × 10 1.1 × 10
•
•
13
11
9
3
f C
3
H
3
H
6
12.0 1.6 × 10 2.3 × 10
•
•
13
7
11
10
2
(c-C
5
•
H
5
) f CH
2
33.3 7.5 × 10 4.8 × 10
•
23 -3.11
5
CH
2
H
3 3
+ C
H
2 2
1.3 × 10 T
44.4 5.3 × 10 1.6 × 10
35.4 41.2 9
1.0 -1.5 21
34.0 91.6 12
33.0 93.1 22
13
2
a-C
a-C
p-C
p-C
a-C
3
H
4
H
4
H
4
H
4
H
4
f p-C
3
H
4
1.5 × 10
4.1 × 10
4.7 × 10
2.0 × 10
2.0 × 10
60.4 4.1 × 10 1.3 × 10
•
•
•
17
17
13
13
4
18
17
3
3
3
3
3
+ Ar f C
3
3
H
H
3
+ H + Ar
+ H + Ar
75.0 3.1 × 10 1.2 × 10
•
3
+ Ar f C
3
80.0 4.9 × 10 5.8 × 10
•
•
12
+ H f C
3
H
H
5
2.4 7.6 × 10 1.4 × 10 -24.7 -57.9 11
•
•
12
2
+ H f C
3
5
2.4 7.6 × 10 4.6 × 10 -23.7 -59.4 11

Thermal Decomposition of 2,5-Dimethylfuran
J. Phys. Chem. A, Vol. 102, No. 52, 1998 10665
TABLE 3: Continued
reaction
number
reaction
+ H•
A
E
k
f
k
r
∆S0
∆H0
ref
13
12
6
8
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
p-C
3
H
4
+ C
2
3
H
3
f C
6
H
6
1.5 × 10
6.2 × 10
1.0 × 10
6.0 × 10
6.0 1.3 × 10
41.1 4.1 × 10
66.0 2.9
4.7 × 10
1.0 × 10
2.8 × 10
2.5 × 10
3.0 × 10
1.2 × 10
1.7 × 10
3.9 × 10
9.4 × 10
6.1 × 10
1.1 × 10
4.4 × 10
2.1 × 10
3.0 × 10
7.6 × 10
-27.2
-30.3
2.7
-30.3
-5.6
-6.6
23.8
-3.8
-10.4
-40.4 -102.4 25
25.2
30.9
24.9
24.2
33.0
-10.0
-1.2
-3.5
5.3
-53.7 est
-35.5 12
71.9 23
-49.4 24
8.5 28
13
2
C
2
C
2
C
2
C
2
C
2
C
2
C
2
C
2
C
2
H
2
2
2
2
2
3
3
3
3
+ C
+ C
+ CH
+ CH
+ CH
H
2
f C
f C
f C
f p-C
f a-C
4
H
4
•
+ H•
H
3
•
12
12
3
H
H
H
H
H
H
H
H
2
H
2
•
4
11
10
8
3
3
3
3
H
5
7.7 2.7 × 10
20.6 5.8 × 10
31.6 7.3 × 10
32.0 7.6 × 10
0.0 8.0 × 10
0.0 1.0 × 10
0.0 7.2 × 10
16.9 2.8 × 10
12.5 8.0 × 10
37.2 1.1 × 10
40.0 1.0 × 10
103.0 2.0 × 10
0.0 3.9 × 10
14.0 1.1 × 10
0.0 8.1 × 10
12.0 2.4 × 10
15.0 2.4 × 10
15.0 1.2 × 10
0.0 5.0 × 10
0.0 5.0 × 10
38.0 1.1 × 10
0.0 1.5 × 10
9.0 9.4 × 10
14.9 1.4 × 10
9.5 4.2 × 10
7.7 1.5 × 10
38.2 3.8 × 10
9.6 2.6 × 10
0.0 1.1 × 10
25.0 8.5 × 10
23.5 1.6 × 10
0.0 1.8 × 10
25.0 2.1 × 10
19.8 3.5
•
•
•
•
18 -1.96
11
11
16
2
3
3
H
H
4
+ H
2.7 × 10 T
19 -2.08
7
4
+ H
6.7 × 10 T
10.0 28
37.4 12
-69.5 24
•
•
•
•
•
15
9
+ Ar f C
+ H f C
2
H
2
+ H + Ar
3.0 × 10
•
13
13
13
13
11
12
6
2
H
2
2
+ H
2
8.0 × 10
•
13
2
+ CH
+ CH
3
f C
f C
H
H
2
+ CH
4
1.0 × 10
-70.4
1
•
13
-1
14
13
12
13
12
3
3
6
7.2 × 10
•
•
14
HCO + Ar f H + CO + Ar
2.5 × 10
17.7 11
14.3 11
38.3 12
38.6 26
107.4
-69.2
-0.3
-68.3
0.5
•
•
15
CH
3
CO + Ar f CH
3
+ CO + Ar
1.2 × 10
•
•
•
•
•
12
C
2
C
4
C
4
C
4
C
4
C
4
C
4
C
4
C
4
C
4
C
4
H
H
H
H
H
H
H
H
H
H
H
5
3
4
3
4
3
4
4
3
3
3
f C
f C
f C
2
H
H
4
+ H
+ H
+ H
3.6 × 10
14
7
4
2
1.0 × 10
•
14
-4
11
11
13
12
10
11
11
11
8
4
H
3
2.0 × 10
1
1
1
1
1
1
1
1
1
•
•
•
11
+ CH
3
•
f C
4
H
2
+ CH
4
3.9 × 10
49
•
13
11
2
+ CH
3
f CH
4
+ C
4
H
3
3.0 × 10
1.7 × 10
5.3 × 10
2.0 × 10
7.6 × 10
6.3 × 10
•
13
+ H f C
4
H
2
+ H
2
8.1 × 10
•
•
14
11
12
12
+ H f C
4
H
3
+ H
2
3.0 × 10
•
•
13
+ C
3
H
3
f p-C
3
H
4
+ C
4
H
3
1.0 × 10
0.0
14.3
•
•
•
•
•
•
•
•
13
+ C
+ C
+ C
2
H
3
3
3
f CHtC-CHdCH-CHdCH + H 5.0 × 10
-11.0
-9.2
-11.1
34.8
-3.9
-70.0
-75.5
11
11
14
13
14
14
2
H
H
f C
f C
4
H
H
4
+ C
+ C
2
2
H
2
5.0 × 10
5.0 × 10
5.0 × 10
1.5 × 10
3.5 × 10
5.4 × 10
29
8.4
2
4
2
H
4
•
•
12
-5
9
CHtC-CHdCH-CHdCH f C
4
H
3
+ C
2
H
2
4.8 × 10
4.3 × 10
6.3 × 10
5.3 × 10
3.1 × 10
5.8 × 10
1.5 × 10
7.1 × 10
9.8
3.8 × 10
2.3 × 10
6.7 × 10
1.1 × 10
1.3 × 10
41.4 12
•
•
13
12
12
10
10
7
C
C
C
C
C
3
3
2
2
2
H
H
H
H
H
3
6
4
4
4
+ C
3
H
3
f C
6
H
6
-60.1 -146.8
1
1
•
•
+ H f CH
3
+ C
2
H
4
5.1
7.7
1.1
-11.7
•
•
11
11
7
+ H f C
2
H
3
+ H
2
7.3 24
6.4 24
•
•
+3.70
+ CH
3
f C
f nC
2
H
3
+• CH
4
6.6T
•
11
+ CH
3
3
H
+ H
7
3.3 × 10
1.8 × 10
1.2 × 10
-29.9
24.8
8.0
-22.5 24
34.2 12
-4.6 12
-90.5 24
22.5 est
21.0 est
-47.5 27
27.7 est
57.4 27
•
•
14
13
9
nC
3
H
7
f C
3
H
6
•
•
14
12
13
7
C
2
H
6
+ H f C
H
2 5
+ H
2
•
•
15 -0.64
CH
3
+ CH
3
f C
2
H
2
6
H
H
1.0 × 10 T
-40.3
•
•
•
12
11
11
5
C
2
C
2
C
3
C
3
C
2
H
H
H
H
H
4
4
5
3
6
+ C
+ C
3
H
H
3
f C
f C
3
3
+ a-C
+ p-C
3
3
H
H
4
2.0 × 10
1.3
•
12
8
3
•
3
2
4
2.0 × 10
2.3
•
13
13
9
+ H f a-C
3
H
4
+• H
2
1.8 × 10
-4.0
28.1
-7.1
•
13
13
12
O f CO + C
2
H
3
•
5.0 × 10
•
2
+3.3
+ C
3
H
5
f C
2
H
3
+ C
3
H
6
2.35 × 10 T
a
Units are cm , mol-1, s-1, kcal/mol and cal/(k mol). Values Are Given at 1250 K). b est ) estimated. c 1*: ref 1, modified.
3
(
Figure 8. Radical profiles, calculated at 1250 K. The profile of C
H
2 4
2 4
Figure 9. Radical profiles, calculated at 1250 K. The profile of C H
is also shown for comparison.
is also shown for comparison.
energies ranged between 6 and 17 kcal/mol depending upon
the size of the radical and the thermochemistry of the abstraction
reactions.
taken into account in view of the high concentration of the latter
as a reactant, at least at the low temperature end of the study.
•
•
•
The concentrations of HCO , C2H3 , and C2H5 as can be seen
in Figure 8 are very small, and their abstraction reactions can
be neglected. The concentration of all the free radicals are
shown as a function of time in Figures 8-11. Since most of
the abstraction reactions that appear in the reaction scheme had
to be estimated, we had to assign values for the preexponential
factors and activation energies for these constants. Preexpo-
It should be mentioned that many of the abstraction reactions
have no influence on the overall decomposition rate of 2,5-
dimethylfuran. Specific abstractions, however, affect the con-
centrations of several low-yield species. The concentrations of
the latter, in most cases, are not very sensitive to the exact values
of the abstraction rate constants. However, if they are removed
from the reaction scheme, the concentrations of these species
are affected. Thus the Arrhenius parameters of these estimates
11
14
nential factors ranged from approximately 5 × 10 to 5 × 10
cm mol s , going form large free radicals to H . Activation
3
-1 -1
•

10666 J. Phys. Chem. A, Vol. 102, No. 52, 1998
Lifshitz et al.
2 4
Figure 10. Radical profiles, calculated at 1250 K. The profile of C H
is also shown for comparison.
Figure 12. Experimental and calculated mole percent of 2,5-dimethyl-
furan, showing its total decomposition.
fragments. Several reactions which describe such processes are
present in the reaction scheme. The decomposition of CH3-
•
•
(
C4H2O)CH2 or CH3(C4H2O) to smaller fragments follow
closely the decomposition pattern of 2,5-dimethylfuran and
1
2
-methylfuran. They are very important reactions in the
scheme. Some of the rate parameters for this decomposition,
•
•
for example, that of the reaction CH3CO f CH3 +CO are
11
known. Others were estimated based on comparison with rates
of similar stable fragment taking into account the endothermicity
of the reaction.
4
. Comments on Specific Products. a. C5H6. As was
demonstrated in Figure 7, two isomers of C5H6 are present
among the reaction products. The larger peak was identified
as cyclopentadiene and the much smaller one as 1,2,4-pen-
tatriene. These two isomers are formed via two, completely
different, routes.
2 4
Figure 11. Radical profiles, calculated at 1250 K. The profile of C H
is also shown for comparison.
rate constants are approximate values and should not be
considered as absolute values.
Cyclopentadiene is formed via a 1,4-cyclization of CH2d
b. Recombinations. As in every scheme containing free
radical reactions, there are recombinations in this scheme as
well. Since the number of free radicals is rather large, and since
we did not recover products having more than six carbon atoms,
we have included recombinations of radicals having together
no more than six carbon atoms. Also, free radicals with very
low concentrations were not included. Preexponential factors
for some of the recombinations were estimated. Recombination
rates depend on the free radical sizes and vary from ap-
•
CH-CHdCH-CH2 together with a H-atom ejection: CH2d
•
CH-CHdCH-CH2 f cyclopentadiene + H, where CH2d
•
CH-CHdCH-CH2 is formed by rearrangement of the
•
decomposition products of the radical CH3(C4H2O)CH2 :
•
No matter whether the -CH3 or the -CH2 group in CH3-
11
13
proximately 4 × 10 for large species to 3 × 10 for methyl
•
(
C4H2O)CH2 migrates in the process of CO elimination, the
groups.
only free radical that can be formed is CH2dCH-CHdCH-
c. DissociatiVe Attachments. This is one of the most
important class of reactions involving free radicals. They
replace highly endothermic unimolecular dissociations that
require high activation energies by bimolecular reactions with
relatively low activation energies. These class of reactions is
•
CH2 .
•
•
2
CH dCH-CHdC -CH f CH dCH-CHdCH-CH
2
3
2
(1,2-H-atom migration)
8,9
very common, for example, in organic nitriles (R-CtN). The
•
•
2
•
•
CH -CHdCH-C dCH f CH dCH-CHdCH-CH
3 2 2
dissociations of such molecules to R + CN are highly
endothermic and thus have very high activation energies,
(1,4-H-atom migration)
•
•
whereas the dissociative attachment R-CtN+H f R + HCN
has a very low activation energy. These type of reactions are
known in many systems and their importance is determined by
the steady-state concentrations of hydrogen atoms. Dissociative
attachments of the type 2,5-dimethylfuran + H f CH3-
CO +C4H6 and others are very important in the present system.
Both 1,2- and 1,4-H-atom migration will lead to the produc-
tion of the same species. No other radical that may finally lead
to the formation of 1,2,4-pentatriene by H-atom ejection can
thus be formed.
•
•
1,2,4-Pentatriene must be formed by another channel and the
only possible channel is the one in which C5H8 and later the
d. Unimolecular Decompositions of Unstable, Free Radical
Intermediates. In the process H-atom or methyl group ejection
from the molecule or in the process of ring cleavage, unstable
intermediates are formed. They further decompose to smaller
•
CH2dCdCH-CH -CH3 radical are the precursors. Since the
concentrations of the two C5H8 isomers are rather small, the
concentration of 1,2,4-pentatriene is very small compared to

Thermal Decomposition of 2,5-Dimethylfuran
J. Phys. Chem. A, Vol. 102, No. 52, 1998 10667
Figure 16. Experimental and calculated mole percent of allene,
propyne, and acetylene.
Figure 13. Experimental and calculated mole percent of the four
isomers of C H .
4 6
Figure 17. Experimental and calculated mole percent of carbon
monoxide and the two isomers of C H .
5 6
Figure 14. Experimental and calculated mole percent of methane and
ethane and propylene.
Figure 18. Experimental and calculated mole percent of 2-methylfuran
and 1,2-pentadiene.
4 4
Figure 15. Experimental and calculated mole percent of C H and
C H .
4 2
that of cyclopentadiene, as can be seen in Figure 7. The reaction
sequence for the production of cyclopentadiene is thus 17, 40,
and 126 (Table 3), and the major one of 1,2,4-pentatriene is 2,
in the decomposition of 2-methylfuran, although the isomers’
formation mechanism are very different. In 2-methylfuran they
are formed by unimolecular cleavage of the ring, whereas in
2,5-dimethylfuran they are produced by processes which include
free radicals. Among these processes are the unimolecular
121, and 125.
b. C4H6. Four isomers of C4H6, 1,2- and 1,3-butadiene, and
- and 2-butyne, were found among the products formed as a
•
•
1
decomposition of 2,5-dimethylfuran to CH3CO and C4H5
•
result 2,5-dimethylfuran decomposition. Their distribution,
shown in Figure 13, is very similar to what has been observed
followed by H-atom recombination with C4H5 , and the dis-
sociative attachments of H-atom to 2,5-dimethylfuran with the

10668 J. Phys. Chem. A, Vol. 102, No. 52, 1998
Lifshitz et al.
TABLE 4: Sensitivity Spectrum at 1100/1300 K for Elimination of Reactions from the Kinetic Scheme. Percent Change in
Yield for Reaction Elimination
reaction
number
1,3-
butadiene
1,2-
butadiene
cyclo-
pentadiene
1,2,4-
pentatriene
1,3-
pentadiene
1,2-
pentadiene
1-butyne
2-butyne
C4H4
C4H2
1
2
3
7
8
9
-/-32
-99/-99
-87/-36
-60/-39
-86/-
-19/-
-20/-
-24/-
-99/-77
-23/-15
-23/-28
-24/-
63/-
-90/-20
-/-22
-47/-19
-/-23
-59/-28
-34/-
-81/-37
-23/-
-26/-
-21/-
-/-23
-24/-
-/22
10
12
13
14
17
18
19
21
22
40
41
56
64
65
66
67
68
76
77
82
20/-
-90/-
65/33
-66/-
63/38
-65/-
20/42
-21/-
-49/-
-43/-
-84/-47
-99/-95
-/23
37/-
37/-
-68/-
-22/-
-/-33
217/208
-78/-37
-78/-
-77/-
-/111
434/51
-56/-
460/71
-56/-
-22/29
-/47
-/23
-40/-21
-/-21
-46/-32
-/-22
26/-
-/182
-/28
-/24
-/88
-/33
-/-28
-/23
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
10
14
18
19
21
25
26
44
45
51
56
57
58
61
76
-/-33
-/35
-/25
-/79
-59/34
-81/-44
-90/-65
-53/139
-77/-17
-21/-
-76/-
-24/-
-30/-
-37/-42
49/-
-70/-
-99/-99
-/741
65/-
-94/-
-30/-
-47/-
-30/-
-47/-
-39/-
-83/-50
-25/-
-62/-
-25/-
-64/-26
-/45
-/44
-98/-97
-97/-84
200/100
58/-25
60/31
21/30
78/26
110/160
propyne
-87/-33
-/-41
reaction
number
CO
CH
4
C
2
H
4
C
2
H
6
C
H
2 2
C
3
H
6
allene
methylfuran
6 6
C H
2
3
4
7
8
9
0
4
5
7
8
9
0
8
0
7
8
-60/-
-86/-26
-37/-22
-71/-
-20/-
-21/-
-35/-
-37/-
-30/-
-20/-
-21/-
-25/-
65/31
-22/-
-21/-
-21/-
-93/-38
-77/-67
-27/-
-15/-23
-/22
1
1
1
1
1
1
2
3
4
6
6
36/-
37/31
-55/-29
-37/-
-/21
-/-21
-99/-99
22/-
-58/-
-98/-35
20/24
-66/-
37/-
37/-
-70/-
-22/-
-/22
-78/-
-23/-
-46/-
-44/-
-43/-
-22/-21
26/24
-/-21
-/-64
-/-29
-/83
1
1
1
1
1
1
1
1
1
1
1
1
1
19
26
43
44
45
46
48
51
54
56
58
76
81
-59/-22
-57/-
-81/-
-39/-40
-/-44
-/-32
-78/-23
65/67
-/-26
-21/-24
-/27
-/46
-94/-64
-/35
-/-29
-/-27
-75/-25
-/23
-/52
-20/-
-65/-38
55/-
-28/-
-49/-
159/146
-28/-64
-35/-23
-31/-
-48/-
62/-
-74/-37
98/110
-27/-
35/-
-93/-64
-/-30
-/31
-99/-99
-20/-
34/46
-34/-37
-80/-19

Thermal Decomposition of 2,5-Dimethylfuran
J. Phys. Chem. A, Vol. 102, No. 52, 1998 10669
Figure 20. Experimental and calculated mole percent of benzene.
Figure 19. Experimental and calculated mole percent of ethylene and
1
,3-pentadiene.
measured yields and the calculated yields using the reaction
scheme shown in Table 3. The agreement for most of the
reaction products is satisfactory considering the large number
of products obtained in this decomposition.
•
production of C4H6 and CH3CO . There are also isomerization
reactions among the various C4H66 species and a number of
competition reactions that can vary the distribution among them
depending upon their rate constants.
Table 4 gives the sensitivity of the products to elimination
of specific reactions from the kinetic scheme, at 1100 and 1300
K, respectively. It gives the percent change in the yield of a
particular product as a result of elimination of a given reaction
from the scheme. The calculations were made for dwell times
of 2 ms. Reactions that show an effect of less than 20% both
at 1100 K and at 1300 K are not included in the table. A
common feature to many reactions is the decreased sensitivity
as the temperature increases. The number of channels that
contribute to the formation of the products increase as the
temperature increases and the effect of eliminating a single
reaction diminishes.
c. C4H4 and C4H2. The yield of C4H4 among the decom-
position products is relatively high. There are at least two major
channels that are responsible for its production. The more
•
•
•
important one is CH3(C4H2O)CH2 f CH3CO +C4H4 but C4H5
•
f C4H4+H also contributes to the production of C4H4. If each
one of these is removed from the reaction scheme, the yield of
C4H4 goes down. All the reactions that are responsible for the
•
•
production of CH3(C4H2O)CH2 or C4H5 have also a strong
influence on the yield of C4H4. C4H2, on the other hand, whose
yield is rather small, is formed by one reaction channel at the
•
•
end of which stands the reaction C4H3 f C4H2+H . If the
latter is turned off, C4H2 disappears completely.
Table 4 shows that only a relatively small number of
elementary steps affect the product distribution in the sense that
their elimination from the scheme affects the yield of at least
one of the products. The majority of the elementary reactions
that compose the scheme do not affect the distribution at all.
They are left in the kinetic scheme for completeness and
applicability beyond the temperature range of the present
experiments. It should be mentioned, however, that the
sensitivity analysis is done by removing a single reaction at a
time and examining its effect. When a complete group of
reactions is eliminated from the scheme there can be a strong
effect on particular products although the elimination of only
one step, as is shown in Table 4, does not affect anything.
Most of the sensitivities that appear in Table 4 are self-
explanatory and enable one to follow the sequence of steps that
lead to a particular product. Cyclopentadiene, for example, is
formed by reaction 126 and is turned completely off when this
reaction is removed. However, if either the main channel for
5
. Reaction Scheme and Computer Modeling. To model
the observed product distribution we have constructed a reaction
scheme containing 50 species and 181 elementary reactions.
The scheme is shown in Table 3. The rate constants listed in
3
-1
the Table are given as k ) Aexp(-E/RT) in units of cm , s ,
-
1
kcal, and mol . The Arrhenius parameters for the reactions
in the scheme are either estimated as previously discussed or
taken from various literature sources, mainly from the NIST-
Kinetic Standard Reference Data Base 17.12 The parameters
for the reactions that were taken from the NIST-Kinetic Data
Base are, in many cases, the best fit to a large number of entries.
(
In view of the very large number of citations involved in these
cases, they are not detailed in the article.) The thermodynamic
properties of the species involved were taken from various
literature sources1
3-16
or estimated using NIST-Standard Refer-
ence Data Base 2513 (Structure and Properties program (SP)).
We have performed sensitivity analysis with respect to variations
or rather uncertainties) in the ∆H f of species whose thermo-
•
the formation of CH3(C4H2O)CH2 (reaction 17) or its decom-
0
(
•
position to CH2dCH-CHdCH-CH2 and CO (reaction 40)
dynamic properties were estimated or are not known accurately
enough. Incorrect values of the thermodynamic functions result
in erroneous values for the rate constants of the back reactions
for a given value of the forward rate constant. In several
sensitivity tests that were performed on the thermodynamic
functions, we found that the results of the simulation were only
slightly sensitive to variations in the estimated values.
Figure 12 shows the overall decomposition of 2,5-dimethyl-
furan. The squares are the experimental points and the line is
the best fit to the calculated points taken at 25 K intervals.
Figures 13-20 show comparisons between the experimentally
are removed from the scheme, the yield of cyclopentadiene
drops almost to zero. This indicates that the formation sequence
of cyclopentadiene is 17 f 40 f 126. Many similar examples
can be found by examining of the sensitivity analysis data shown
in Table 4.
References and Notes
(
1) Lifshitz, A.; Tamburu, C.; Shashua, R. J. Phys. Chem. A 1997,
01, 1018.
2) Grela, M. A.; Amorebieta, V. T.; Collusi, A. J. J. Phys. Chem.
1985, 89, 38.
1
(

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(3) Lifshitz, A.; Moran, A.; Bidani, S. Int. J. Chem. Kinet. 1987, 19,
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Organic Compounds; Chapman and Hall: London, 1986.
6
1.
(
(
4) Tsang, W.; Lifshitz, A. Int. J. Chem. Kinet. 1998. In press.
5) Lifshitz, A.; Bidani, M.; Agranat, A.; Suslensky, A. J. Phys. Chem.
(
16) Burcat, A.; McBride, B.; Rabinowitz, M. Ideal Gas Thermodynamic
Data for Compounds Used in Combustion; T. A. E. 657 Report; Technion,
Israel Institute of Technology; Haifa, Israel, 1997.
1
987, 91, 6043.
6) Hidaka, Y.; Higashihara, T.; Ninomiya, N.; Oshita, H.; Kawano,
H. J. Phys. Chem. 1993, 97, 10977.
7) Muller-Markgraf, W.; Troe, J. In Proceedings of the 21st Interna-
(
(17) Nguyen, T. T.; King, K. D. Int. J. Chem. Kinet. 1982, 14, 623.
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