Photolysis of Matrix-Isolated Acryloyl Chloride: 1,3 Chlorine Migration and Further Evolutions

Article abstract of DOI:10.1021/jo971217n

Photolysis, at λ ≥ 310 nm (ΔE < 387 kJ mol^-1), of acryloyl chloride 1 isolated in argon matrixes at 10 K yields 3-chloro-1,2-propenone 4 through 1,3-chlorine migration. There is no evidence of cyclopropenone or propadienone formation. 4 is also synthesized by irradiation of 3-chloropropanoyl chloride (λ ≥ 230 nm) isolated in argon matrix at 10 K. Identification is performed by comparison of experimental FT-IR spectrum with calculated ones (ab initio calculations at the 6-31G** level). Irradiation of 1 at λ ≥ 230 nm induces the photolysis of 4 which breaks into CO and the postulated transient 2-chloroethylidene 5 and/or into propadienone 2 complexed by HCL The transient 5 collapses to form ground-state vinyl chloride 6 by 1,2 hydrogen migration. In the next step, 2 loses CO to form a new transient assumed to be vinylidene 7 which yields ethyne by intramolecular isomerization process and vinyl chloride by intermolecular reaction with HCl trapped in the same cage. CO, HCl, ethyne, and vinyl chloride are the final reaction products. Modeling of the 1,3 chlorine migration process from 1 using ab initio calculations at the MP2/6-31G* level is performed in the ground state (S₀) and the first singlet excited state (S₁). The reaction energy value for an S₁ (509 kJ/mol) state process is higher than for an S₀ process (207.2 kJ/mol), these theoretical results suggesting the reaction take place in the ground state.

Full text of DOI:10.1021/jo971217n

2462
J . Org. Chem. 1998, 63, 2462-2468
P h otolysis of Ma tr ix-Isola ted Acr yloyl Ch lor id e: 1,3 Ch lor in e
Migr a tion a n d F u r th er Evolu tion s
Nathalie Pie´tri, Maurice Monnier, and J ean-Pierre Aycard*
UMR CNRS 6633, Physique des Interactions Ioniques et Mole´culaires, Equipe Spectrome´tries et
Dynamique Mole´culaire, Universite´ de Provence, Case 542, 13397 Marseille Cedex 20, France
Received J uly 3, 1997
Photolysis, at λ g 310 nm (∆E < 387 kJ mol-1), of acryloyl chloride 1 isolated in argon matrixes at
10 K yields 3-chloro-1,2-propenone 4 through 1,3-chlorine migration. There is no evidence of
cyclopropenone or propadienone formation. 4 is also synthesized by irradiation of 3-chloropropanoyl
chloride (λ g 230 nm) isolated in argon matrix at 10 K. Identification is performed by comparison
of experimental FT-IR spectrum with calculated ones (ab initio calculations at the 6-31G** level).
Irradiation of 1 at λ g 230 nm induces the photolysis of 4 which breaks into CO and the postulated
transient 2-chloroethylidene 5 and/or into propadienone 2 complexed by HCl. The transient 5
collapses to form ground-state vinyl chloride 6 by 1,2 hydrogen migration. In the next step, 2
loses CO to form a new transient assumed to be vinylidene 7 which yields ethyne by intramolecular
isomerization process and vinyl chloride by intermolecular reaction with HCl trapped in the same
cage. CO, HCl, ethyne, and vinyl chloride are the final reaction products. Modeling of the 1,3
chlorine migration process from 1 using ab initio calculations at the MP2/6-31G* level is performed
in the ground state (S0) and the first singlet excited state (S1). The reaction energy value for an S1
(509 kJ /mol) state process is higher than for an S0 process (207.2 kJ /mol), these theoretical results
suggesting the reaction take place in the ground state.
In tr od u ction
shift in ketene derivatives have been carried out by
Wentrup and co-workers.6 They have shown that the
rate of the 1,3 migration is strongly dependent on the
nature of the substituent. In particular, the electron-
rich n-donating groups, such as Cl, are found to accelerate
this rearrangement. In a recent paper, Koch et al.7 have
used high level ab initio calculations to examinate the
1,3 and 1,5 chlorine migration occurring in ketene
derivatives. In the case of chloro oxoketene, they forecast
a very low activation barrier for the 1,3 chlorine sigma-
tropic migration. Such a rearrangement may occur
during acryloyl chloride irradiation and lead to 3-chloro-
1,2-propenone 4 (cf. eq 2).
Our group is actively involved in the synthesis, iden-
tifications, and reactivity of neutral intermediates trapped
in rare gas matrixes.1-3 The matrix isolation technique
is certainly the most appropriate method for investigation
of reactive species. In previous works, we showed that
aliphatic acyl chlorides isolated in rare gas matrixes lead
to ketenes by a syn photodehydrochlorination process
when submitted to UV irradiation.4 Taking into account
such a mechanism, s-cis and s-trans conformers of
acryloyl chloride 1 seem convenient precursors for pro-
padienone 2 and cyclopropenone 3, respectively (cf. eq
1).
(1)
(2)
On the other hand, photochemical (1,n) sigmatropic
rearrangements are well-known processes and have
formed the subject of several reviews.5 Further experi-
mental and theoretical investigations on the thermal 1,3
In the present study, we report the first photolysis
experiments on 1 isolated in argon matrixes. Experi-
mental data on the photoreactivity of each conformer of
acryloyl chloride are expected. Theoretical calculations
were undertaken in order to compare the experimental
IR spectra with the calculated ones, to assign the
observed absorption of photoproducts, and furthermore
to identify the different photolysis pathways.
(1) Bachmann, C.; N’Guessan, T. Y.; Debu, F.; Monnier, M.; Pourcin,
J .; Aycard, J .-P.; Bodot, H. J . Am. Chem. Soc. 1990, 112, 7488.
(2) Risi, F.; Pizzala, L.; Carles, M.; Verlaque, P.; Aycard, J .-P. J .
Org. Chem. 1996, 61, 666.
(3) Pie´tri, N.; Chiavassa, T.; Allouche, A.; Aycard, J .-P. J . Phys.
Chem. A, 1997, 101, 1093.
(4) (a) Monnier, M.; Allouche, A.; Verlaque, P.; Aycard, J .-P. J . Phys.
Chem. 1995, 99, 5977. (b) Pie´tri, N.; Chiavassa, T.; Allouche, A.;
Rajzmann, M.; Aycard, J .-P. J . Phys. Chem. 1996, 100, 7034. (c) Pie´tri,
N. Thesis, Universite´ de Provence, Marseille, 1996.
(5) (a) Hoffmann, R.; Woodward, R. B. Acc. Chem. Res. 1968, 1, 17.
(b) Gilchrist, T. L.; Storr, R. C. Organic Reactions and Orbital
Symmetry; Cambridge University Press: New York, 1972. (c) Salem,
L. Acc. Chem. Res. 1979, 12, 82. (d) Peijnenburg, W. J . G. M.; Buck,
H. M. Tetrahedron 1988, 44, 4821. Peijnenburg, W. J . G. M.; Buck, H.
M. Tetrahedron 1988, 44, 4940.
(6) (a) Ben Cheik, A.; Chuche, J .; Manisse, N.; Pommelet, J . C.;
Netsch, K. P.; Lorenzack, P.; Wentrup, C. J . Org. Chem. 1991, 56, 970.
(b) Kappe, C. O.; Kollenz, G.; Leung-Toung, R.; Wentrup, C. J . Chem.
Soc., Chem. Commun. 1992, 487. (c) Wong, M. W.; Wentrup, C. J . Org.
Chem. 1994, 59, 5279. (d) Fulloon, B. E.; Wentrup, C. J . Org. Chem.
1996, 61, 1363. (e) Bibas, H.; Wong, M. W.; Wentrup, C. J . Am. Chem.
Soc. 1995, 117, 9582.
(7) Koch, R.; Wong, M. W.; Wentrup, C. J . Org. Chem. 1996, 61,
6809.
S0022-3263(97)01217-6 CCC: $15.00 © 1998 American Chemical Society
Published on Web 03/19/1998

Photolysis of Matrix-Isolated Acryloyl Chloride
J . Org. Chem., Vol. 63, No. 8, 1998 2463
Sch em e 1
Exp er im en ta l Section
Acryloyl chloride and 3-chloropropanoyl chloride, supplied
from Aldrich, were used after purification by vacuum distil-
lation.
Ma tr ix Isola tion Exp er im en ts. The apparatus and ex-
perimental techniques have been described elsewhere in the
literature.8 The relative concentration of rare gas to acryloyl
chloride, and to 3-chloropropanoyl chloride, at room temper-
ature (M/S ratio) was adjusted by pressure measurements;
reproducible solute partial pressures required the use of a
Datametrics (Barocel, series 600) capacitance manometer. The
mixture was heated at 323 K before deposit at 20 K on a CsBr
window. The deposition rate of gas mixtures was controlled
with an Air Liquide microleak (V.P/RX); it never exceeded 2
mmol/h, a value chosen to avoid, as far as possible, the site
splitting of vibrational absorption bands. The thickness of
matrixes was determined by counting transmission franges.
F TIR a n d UV Sp ectr oscop ies. The IR spectra were
recorded in the 4000-400 cm-1 range on a 7199 Nicolet
spectrometer equipped with a liquid N2 cooled MCT detector;
the resolution was 0.12 cm-1 without apodization. The inte-
grated absorbances A (cm-1) were measured as the area under
a simulated peak (giving the best fit with the experimental
data) using the FOCAS program of the Nicolet library.
The UV spectra were recorded in the 200-800 nm range
on a Unicam UV4 spectrometer.
F igu r e 1. Infrared spectra of νCO range of the acryloyl chloride
1 (a) and 3-chloro-1,2 propenone 4 (b) isolated in argon
matrix: (c) spectrum after deposition; (d) spectrum after 1260
min of irradiation time at λ > 310 nm.
Ir r a d ia tion Tech n iqu es. Irradiation was carried out
using an Osram 200 W high-pressure mercury lamp equipped
with a quartz envelope. The broad band was filtered at λ >
310 nm and λ > 230 nm. The light intensity is the same in
all experiments, and the irradiation area is wider than the
surface used to obtain the spectrum. It is assumed that the
matrix has no significant absorbance.
Deta il of Ca lcu la tion s. The energies of the reaction
products as well as the vibrational spectra were determined
by ab initio calculations. The Gaussian 949 program package
using the Møller-Plesset second-order (MP2) procedure with
6-31G* basis set10 was used for these calculations. The frozen-
core approximation was employed for all correlated calcula-
F igu r e 2. Evolution of integrated absorbances during irradia-
tion of acryloyl chloride 1 at λ > 310 nm.
tions. The calculated vibrational frequencies were scaled via
the standard Pulay procedure.11,12 The 1,3 chlorine migration
was studied by semiempirical calculations using AMPAC13
with intrinsic reaction coordinate (IRC), at the PM3 level.14
The 1 and 4 ground states and the transition state of the
migration reaction are optimized by ab initio calculations. The
berny procedure15 was used for transition state optimizations.
(8) (a) Monnier, M. D. Sc. Thesis, Universite´ de Provence, Marseille,
1991. (b) Pourcin, J .; Monnier, M.; Verlaque, P.; Davidovics, G.;
Lauricella, R.; Colonna, C.; Bodot, H. J . Mol. Spectrosc. 1985, 109, 186.
(9) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.;
J ohnson, B. G.; Robb, M. A.; Cheeseman, J . R.; Keith, T.; Petersson,
G. A.; Montgomery, J . A.; Raghavachari, K.; Al-Laham, M. A.;
Zakrzewski, V. G.; Ortiz, J .V.; Foresman, J . B.; Cioslowski, J .; Stefanov,
B. B.; Nanayakkara, A.; Challacombe, M.; Peng, C. Y.; Ayala, P. Y.;
Chen, W.; Wong, M. W.; Andres, J . L.; Replogle, E. S.; Gomperts, R.;
Martin, R. L.; Fox, D. J .; Binkley, J . S.; Defrees, D. J .; Baker, J .;
Stewart, J . P.; Head-Gordon, M.; Gonzalez, C.; Pople, J . A. Gaussian
94, Revision C.2, Gaussian, Inc., Pittsburgh, PA, 1995.
(10) Moller, C.; Plesset, M. S. Phys. Rev. 1984, 46, 618.
(11) (a) Fogarasi, G.; Pulay, P. Vib. Spectra Struct. 1984, 14, 191.
(b) Durig, J . R.; Fogarasi, G.; Pulay, P. Annu. Rev. Phys. Chem. 1984,
35, 191.

2464 J . Org. Chem., Vol. 63, No. 8, 1998
Pie´tri et al.
The electronic excited-state energies and wave functions
were evaluated using the CI-single (CIS) configuration ap-
proach which models an excited state as a combination of
single excitations from the Hartree-Fock ground state16
adapted to large systems. A certain portion of CI is actually
included, but the computational effort is less formidable.
Although CIS was originally developed for organic molecules,17a
Sch em e 2
it has been successfully tested for the computation of electronic
17b
absorption spectra of fairly large clusters such as Na18Cl17
.
Resu lts a n d Discu ssion
The involved compounds and the reaction paths are
depicted in Scheme 1. Photolysis experiments were
monitored by FT-IR spectroscopy. Reaction compounds
were identified by comparison of their experimental IR
spectra with literature data. For the 3-chloro-1,2-pro-
penone, the experimental spectra was compared with
simulated spectra obtained by ab initio force field calcu-
lations using the MP2/6-31G* basis set.
can be speculated that the RHF/6-31G* calculations
overestimate the steric repulsion between the chloride
and the vinyl hydrogen in the s-trans conformation.
Nevertheless, there are small differences between the
geometries calculated at the different computational
levels.
The FT-IR spectra were systematically recorded at
different times during the photolysis process. As the
integrated intensities of numerous absorption bands were
plotted versus time, we were able to detect those having
identical behavior, indicating that they belong to the
same product. The distinction between 1 s-cis and 1
s-trans infrared spectra was confirmed by observing the
opposite behavior of the two sets of absorption bands
during the irradiation experiments which reveals the
occurrence of a photoisomerization process.
P h otolysis Exp er im en ts. When matrix-isolated 1 is
submitted to a broad band irradiation, with high-pressure
Hg lamp, filtered at λ > 310 nm in its nfπ* electronic
absorption band, we observe the decrease of 1 s-trans IR
absorption bands and the increase of 1 s-cis absorption
bands. The photochemical behavior of the two conform-
ers of acryloyl chloride in argon matrix is reported in
Figure 1 and the evolution of the integrated absorbances
versus time in Figure 2.
Vibr a tion a l An a lysis of 1 Isola ted in Ar gon Ma -
tr ixes. Prior to photolysis experiments, the experimen-
tal spectrum of 1 was carefully studied in order to
distinguish between the conformer spectra. This com-
pound adopts two conformations by rotation around the
carbon-carbon single bond: the 1 s-trans and 1 s-cis
conformers for which the dihedral angle CdC-CdO is
equal to 180° and 0°, respectively.18 The evolution of the
infrared spectrum of 1, from the liquid to the low-
temperature solid at 178 K, shows that the 1-s-trans
conformer is more stable.
In our experiments, the infrared spectrum, obtained
after deposition at 20 K, features the characteristic
absorption bands of the two conformers, with multiplet
structure arising from alternative trapping sites. The
conformational preference, determined using the two
carbon chloride stretching vibration is clearly for the s-cis
conformer, and the ratio of the two conformers (K (s-cis/
s-trans) ≈ 1.4) is similar to those obtained between 276
and 361 K by Katon et al. in the gaseous phase.18b
Our ab initio calculations, at the MP2/6-31G* level,
which show that the s-cis conformer is the most stable
(∆E s-cis - s-trans ) -0.37 kcal/mol), are in good
agreement with the ones obtained by Garcia et al.19
These authors have performed ab initio calculations at
different computational levels in order to study the s-cis/
s-trans conformational preference. These results show
that the calculated ∆E values are dependent on the
computational level (-0.57 and 0.1 kcal/mol using RHF/
6-31G* and MP3/6-311++G** levels, respectively). It
Under irradiation, new absorption bands appear in
different areas of the spectra. In particular, we observe
new strong absorption bands growing at 2149 and 2139
cm-1, indicative of the presence of νCdCdO stretching
mode. The lack of νHCl absorption bands around 2870
cm-1 and characteristic νCCCO20 and νCO21 vibration bands
of compounds 2 and 3, at 2125 and 1835-1870 cm-1
,
respectively, rule out the occurrence of the deshydrochlo-
rination process. It further suggests that irradiation
induces 1,3 migration of the chlorine atom to form 4 as
primary photoproduct. This intermediate reaches a
photochemical steady state with 1 conformers.
To unambiguously identify 4 as the primary photo-
product, we carried out an other experiment: the irradia-
tion of 3-chloropropanoyl chloride (ClCH2CH2COCl)
trapped in argon matrix at 10 K (Scheme 2). Broad band
filtered irradiation at λ > 230 nm of 3-chloropropanoyl
chloride embedded in argon matrix induces the formation
(12) Allouche, A.; Pourcin, J . Spectrochim. Acta 1993, 49A, 571.
(13) Liotard, D. A.; Heally, E. H.; Ruiz, J . M.; Dewar, M. J . S.
AMPAC Manual, version 2, 1. A General Molecular Orbital Package,
1989, University of Texas: Austin, TX.
(14) Stewart, J . J . P. J . Comput. Chem. 1989, 10, 209.
(15) (a) Schlegel, A. B. J . Comput. Chem. 1982, 3, 214. (b) Frish, M.
J .; Foresman, J . B.; Frish, Æ., Appendix IV, Gaussian 92 User’s guide,
Gaussian Inc. Pittsburgh, PA, 1992.
(16) Foresman, J . B.; Head-Gordon, M.; Pople, J . A.; Frish, M. J . J .
Phys. Chem. 1992, 96, 135.
(17) (a) Allouche, A. J . Phys. Chem. 1996, 100, 17915. (b) Ochsen-
fields, C.; Gauss, J .; Ahlrichs, R. J . Chem. Phys. 1995, 103, 7401.
(18) (a) Kataoka, T.; Shimada, H.; Shimada, R. Mem. Fac. Sci.,
Kyushu Univ., Ser. C 1982, 13, 261. (b) Katon, J . E.; Feairheller, W.
R., J r. J . Chem. Phys. 1967, 47, 1248. (c) Hagen, K.; Hedberg, K. J .
Am. Chem. Soc. 1984, 106, 6150. (d) Durig, J . R.; Church, J . S.;
Compton, D. A. C. J . Chem. Phys. 1979, 71, 1175. (e) Durig, J . R.;
Berny, R. J .; Groner, P. J . Chem. Phys. 1987, 87, 6303.
(19) Garcia, J . I.; Mayoral, J . A.; Salvatella, L.; Assfeld, X.; Ruiz-
Lopez, M. F. J . Mol. Struct. 1996, 187, 362.
(20) Chapman, O. L.;. Miller, M. D.; Pitzenberger, S. M. J . Am.
Chem. Soc. 1987, 109, 6867.
(21) (a) Breslow, R; Ryan, G. J . Am. Chem. Soc. 1967, 89, 3072. (b)
Potts, K. T.; Baum, J . S. Chem. Rev. 1974, 74, 189.

Photolysis of Matrix-Isolated Acryloyl Chloride
J . Org. Chem., Vol. 63, No. 8, 1998 2465
Ta ble 1. Obser ved a n d Sim u la ted In fr a r ed Sp ectr a of Acr yloyl Ch lor id e 1 Con for m er s
experiment
obsdb
calculation
no.
obsda
Ic
νcalcd
νd
Ic
sym
assignment
1 s-trans
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
3334
3354
3232
1821
1701
1478
1336
1203
1021
988
976
766
617
510
455
447
263
105
3328
3280
3227
1834
1701
1473
1347
1121
1023
1021
989
747
729
783
459
402
262
85
3109
3036
3015
1765
1633
1418
1282
1159
995
974
939
753
597
1
A′
A′
A′
A′
A′
A′
A′
A′
A′′
A′′
A′
A′′
A′
A′
A′′
A′
A′
A′′
A′
A′
A′
A′
A′
A′
A′
A′
A′′
A′
A′′
A′′
A′
A′′
A′
A′
A′
A′′
νCH2as
<1
<1
100
5
9
1
νCH
νCH2s
1761
1617
1393
1277
1143
1001
973
932
753
606
495
1766
1626
1394
1284
1150
984
979
936
756
605
100
2
15
2
56
18
14
5
νCdO
νCdC
âCH2
âCH
66
19
9
50
8
36
11
<1
7
<1
<1
<1
<1
<1
57
8
18
<1
6
15
7
100
7
30
<<1
6
νC-C
tors CdC
oop CH2
νC-C + âCH2
oop C-Cl
νC-Cl
âC-C-Cl + âO-C-Cl
oop C-Cl
νC-Cl
5
6
3
494
489
447
432
253
âC-C-Cl + âCCO
tors C-C
νCH2as
101
1 s-cis
3105
3060
3010
1778
1632
1413
1293
1078
1000
984
969
736
702
474
443
386
252
82
νCH
νCH2s
1772
1608
1393
1295
1072
994
973
970
737
703
1779
1619
1398
1288
1075
999
986
973
744
705
60
6
νCdO
νCdC
43
<1
<1
<1
32
100
7
âCH2
âCH
νC-C + âCCH
tors CdC
νC-C
oop CH2
oop C-Cl
νC-Cl + âC-C-O
oop C-Cl
νC-Cl
νC-Cl + âCl-C-O
âC-C-Cl + âCCO
tors C-C
58
446
380
446
6
6
<1
<1
a
b
d
This work. Liquid state.16b c Relative intensities. Scaled frequencies (the scaling factors are as follows: stretching C-C ) 0.92;
other stretchings ) 0.94; bending and torsion ) 0.92; deformation ) 0.98).
Ta ble 2. Exp er im en ta l a n d Ca lcu la ted Vibr a tion a l F r equ en cies of 3-Ch lor o-1,2-p r op en on e 4 (cm -1
)
experiment
obsda
calculation
no.
obsdb
νcalcd
νc
Id
assigment
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
3279
3232
3164
2225
1540
1452
1362
1253
1179
1072
902
746
635
559
531
313
204
69
3162
3116
3051
2146
1445
1380
1277
1182
1116
1020
854
714
597
523
499
294
192
66
2
<1
2
100
6
<1
12
3
<1
4
2
21
2
νCH
νCH2as
νCH2s
2143.6-2138
2139.2-2145
νCdCdO
1448
1447.5
âCH2
νC-C
1268.6-1262
1183.9
1267.8-1263
1183.5
âH-C-Cl
âH-C-Cl
âC-C-H
1021
701
1017.4
701
νC-C + νCdCdO
νC-C + âCH2
νC-Cl
oop O5 + νCdC-C
âCdCdO + oopO5
âCdCdO + oopO5
âCdCdO + âC-C-Cl
âC-CdC + âCdCdO
tors C-C
7
<1
3
<1
<1
a
b
Frequencies oObtained from photolysis of acryloyl chloride 1 in argon matrix at λ > 310 nm. Frequencies obtained from photolysis
of 3-chloropropionyl chloride (CH2ClCH2COCl) in argon matrix at λ > 230 nm. c Scaled frequencies. The scaling factors are as follows:
0.93 for stretchings and 0.88 for bendings and deformations. Relative intensities.
d
of HCl (νHCl ) 2742.5 cm-1) and of 4. The frequency shift
observed for the νHCl stretching mode (-127.5 cm-1 lower
existence of this complex explains the frequency differ-
ence of 4 absorption bands in the two experiments (cf.
Table 2).
When the matrix-isolated 1 is submitted to broad band
irradiation at λ > 230 nm in the πfπ* electronic
absorption band (277 nm), the IR absorption bands of the
than the value for free HCl trapped in argon matrix3,22
indicates that HCl and 4 produced by photolysis yield
an 1:1 complex. This result is similar to those previously
observed in our laboratory3,4 and by Kogure et al.23 The
)

2466 J . Org. Chem., Vol. 63, No. 8, 1998
Pie´tri et al.
F igu r e 4. Evolution of integrated absorbance during pho-
tolysis of acryloyl chloride 1 at λ > 230 nm.
Ta ble 3. Exp er im en ta l Vibr a tion a l F r equ en cies of
P r od u cts Obta in ed fr om P h otolysis of th e Acr yloyl
Ch lor id e 1. Th e Ma in P ea k F r equ en cies Ar e Un d er lin ed
observed frequencies (cm-1
literature
)
our work
identification
3282.7-3281-3280.8
2789-2787
2761-2759
2754-2752
2145.9-2144.5
2145-2143.6-2142.7
2141.4-2140.9
2138.7
3282.6a
8‚HCl
2‚HCl
8‚HCl
8‚HCl
2764.4a
4
CO
CO
2138.5-2135.9-2134
4
2102
2‚HCl
8‚HCl
4
6
6
8‚HCl
6
4
4
6
4
6
6
1972.2-1971.9
1448
1608.9
1366.8-1350.5
1344.9
1283.7-1282.9
1269-1262.3
1183.9
1026.4
1021
951
896-895
754.3-751.8
741.5-738.5
712.3
701
621.6
1973.1a
1601-1621b
1360-1381b
1343.9a
1271-1292b
1021-1038b
941-960b
896b
751.2a
8‚HCl
8‚HCl
6
737.2a
710-731b
4
629.8a
8‚HCl
a
b
See ref 24. See ref 25.
vibrational frequencies are reported in Table 2 where
they can be compared to theoretical scaled and unscaled
frequencies.
In the very early stage of the irradiation at λ > 230
nm, new absorption bands appear in different areas (cf.
Figure 3). A broad absorption band assigned to the νHCl
stretching mode (cf. Figure 3a) appears at 2761 cm-1 and
a smaller one at 2789 cm-1. These frequencies are lower
than the value observed for free HCl22 by ∆νHCl ) -106
F igu r e 3. Evolution of the FTIR spectra of acryloyl chloride
1 isolated in an argon matrix at 10 K during irradiation. (a)
νHCl range, (b) νCCO range; (c) νCH range, (d) extended part of
the νCCO range: (e) spectrum after 1260 min of irradiation time
at λ > 310 nm; (f) spectrum after 322 min of irradiation at λ
> 230 nm; (g) spectrum after 2460 min of irradiation at λ >
230 nm. * bands of 3-chloro-1,2-propenone.
(22) (a) Girardet, C.; Lakhlifi, A.; Laroui, B.J . Chem. Phys. 1992,
97, 7955. (b) Laroui, B.; Damak, O. Maillard, O.; Girardet, C. J . Chem.
Phys. 1992, 97, 2359. (c) Laroui, B.; Perchard, J .-P.; Girardet, C. J .
Chem. Phys. 1992, 97, 2347. (d) Hunt, R. D.; Andrews, L.; MacToth,
L. Inorg. Chem. 1991, 30, 3829. (e) Andrews, L.; Hunt, R. D. J . Chem.
Phys. 1988, 89, 3502. (f) Verstegen, J . M. P. J .; Goldring, H.; Kemel,
S.; Katz, B. J . Chem. Phys. 1966, 44, 3216.
two conformers of acryloyl chloride decrease while the
absorption bands of 3-chloro-1,2-propenone first increase
and then decrease (cf. Figure 4). This last result enables
us to assign the absorption bands of this intermediate
product in all the spectral range. These experimental
(23) Kogure, N. N.; Ono, T.; Suzuki, E.; Watari, F. J . Mol. Struct.
1993, 296, 1.

Photolysis of Matrix-Isolated Acryloyl Chloride
J . Org. Chem., Vol. 63, No. 8, 1998 2467
Ta ble 4. Rela tive En er gies, Activa tion Ba r r ier Va lu es, a n d Geom etr ies (bon d len gth s in a n gstr om s, va len ce a n d
d ih ed r a l a n gles in d egr ees) for Rea cta n t, Tr a n sition Sta tes, a n d P r od u cts in th e Tw o F ir st Sin glet Electr on ic Levels
ab initio (MP2/6-31G*)
semiempirical (PM3)
S0
S1
S0
S1
1
TS
4
1
TS
4
1
TS
4
1
TS
4
parameters
C2-C3
1.340
1.474
1.206
1.796
3.085
1.086
1.084
1.378
1.387
1.165
2.549
2.449
1.085
1.076
1.487
1.326
1.179
3.605
1.808
1.083
1.090
1.328
1.444
1.263
1.737
3.204
1.075
1.073
1.447
1.417
1.169
3.410
2.221
1.080
1.073
1.491
1.394
1.178
4.040
1.780
1.079
1.017
1.341
1.477
1.202
1.781
3.019
1.096
1.086
1.400
1.392
1.168
2.204
2.214
1.092
1.092
1.485
1.321
1.176
3.500
1.784
1.096
1.097
1.375
1.389
1.325
1.657
3.084
1.095
1.083
1.354
1.439
1.170
3.278
2.221
1.097
1.119
1.463
1.426
1.174
4.005
1.772
1.095
1.104
C3-C4
C4-O5
C4-Cl6
C2-Cl6
C3-H7
C2-H1
C3-C4-O5
C2-C3-C4
H1-C2-H8
Cl6-C4-C3
C2-C3-C4-Cl6
C2-C3-C4-O5
relative energies(*)
kJ mol-1-1
124.2
160.5
178.3
123.6
130.6
132.8
126.3
159.5
178.8
119.4
140.8
142.3
125.7
117.5
115.8
0.0
180.0
0
116.7
115.9
86.7
30.6
168.2
207.2
121.3
108.7
41.6
99.0
0.00 180.0
42.6 457.6
126.0
117.4
123.4
0.0
122.4
114.8
63.8
38.8
183.0
509.0
120.0
107.9
15.0
179.8
180.0
315.5
123.1
114.9
113.9
22.1
160.0
0
113.8
113.7
87.1
27.5
198.1
158.8
123.2
109.4
41.1
46.8
157.4
29.7
121.5
116.3
125.8
0.0
180.0
362.1
119.3
114.7
65.6
32.6
173.6
371.4
117.3
107.9
15.6
179.9
180.0
268.0
(*) The S0 state of 1 s-trans is taken as the reference energy.
and -81 cm-1, respectively, and are characteristic of
complexed HCl.3
In the range of the νcco and νco stretching frequencies
between 2200 and 2100 cm-1, two kinds of absorption
bands appear. The strongest ones (2145.9-2140.9-
2148.7-2134.5 cm-1) are assigned to CO (trapped in
different sites with different surrounding molecules
(Figure 3b)). The smaller one (2102 cm-1) can be as-
signed to 2 complexed with HCl for two reasons: This
band has the same kinetic behavior than the νHCl band
at 2789 cm-1, and its shift to low frequency (25 cm-1 in
comparison with the value observed by Chapman20) is
indicative of a complex (cf. Figure 3d).
Another set of absorption bands at 3280.2, 1971.9, and
1345 cm-1 and the sharp doublet at 781.6 and 738.6 cm-1
with similar behavior must be assigned to ethyne com-
plexed with HCl by comparison with the Andrews
results24 (cf. Figure 3c). The infrared frequencies of the
fundamental vibrational modes of vinyl chloride at 1608,
1350.5, 1283.7, 1026.4, 954, 754, and 712 cm-1 were also
observed. They are close to those reported in the
literature25 for free molecules embedded in an argon
matrix without a CO molecule as a cage companion. The
experimental frequency values are reported in Table 3.
The evolution of the integrated aborbances of the differ-
ent products at different irradiation times are reported
in Figure 4.
F igu r e 5. Transition state of the 1,3 chlorine migration
calculated in the ground state with MP2/6-31G* basis set.
state (Ea ) 207.2 kJ mol-1) via an out of plane transition
state (Figure 5), probably after relaxation in a high
vibrational energy level. These results are similar to
those obtained by Kock et al.7 for the activation barrier
(216 kJ mol-1) and the out of plane transition state of
the 1,3 chlorine migration in the 3-chloro-1-propene.
Con clu sion
During the photolysis of acryloyl chloride 1 at λ > 310
nm the initial loss of HCl has been expected to produce
2 and 3 as the first intermediates. Experimentally,
3-chloro-1,2-propenone 4 is the only observed product.
There is no evidence for the formation of cyclopropenone
3 and propadienone 2. A photochemical steady state is
reached involving 1 s-trans, 1 s-cis, and 4. Irradiation
at shorter wavelengths speeds up this isomerization
process and induces the photolysis of 4 which presents
two reaction paths:
(1) splitting into CO and the postulated 2-chloroeth-
ylidene transient 5, the latter isomerizing to vinyl
chloride 6;
(2) elimination of HCl with formation of propadienone
2 complexed by the HCl molecule. Subsequently, the
photolysis of 2 gives CO and a new transient assumed
to be the vinylidene 7 which isomerizes to ethyne 8.26
CO, HCl, ethyne, and vinyl chloride are the final
reaction output. The 1,3 photoisomerization process
Th eor etica l Stu d ies
Absolute energies and calculated geometries by ab
initio and semiempirical method are summarized in
Table 4. The first calculated singlet excited (S1) in MP2/
6-31G* basis set is 457 kJ mol-1 above the ground state
(S0). The energy available upon photolysis in the range
310-600 nm is not sufficient (E < 387 kJ mol-1) to
populate the first excited state (S1). Moreover, in the CIS
approximation16 used in this work, the transition here
considered S0fS1 (σfπ*) is forbidden. Consequently, the
1,3 chlorine migration has to take place in the ground
(24) Andrews, L.; J ohnson, G. L.; Kelsall, B. J . J . Phys. Chem. 1982,
86, 3374.
(25) (a) Zaki El-Sabban, M.; Zwolinski, B. J . J . Mol. Spectrosc. 1968,
27, 1. (b) Enomoto, S.; Asahima, M. J . Mol. Spectrosc. 1966, 19, 117.
(c) Gullikson, C. W.; Rud Nielsen, J . J . Mol. Spectrosc. 1957, 1, 158.
(26) (a) Fahie, B. J .; Leigh, W. J . Can. J . Chem. 1989, 67, 1859. (b)
Mincu, I.; Hillebrand, M.; Allouche, A.; Cossu, M.; Verlaque, P.; Aycard,
J .-P.; Pourcin, J . J . Phys. Chem. 1996, 100, 16045. (c) Mincu, I. Thesis,
Universite´ de Provence, Marseille 1995. (d) Likhotvorik, I. R.; Brown,
D. W.; J ones J r., M. J . Am. Chem. Soc. 1994, 116, 6175.

2468 J . Org. Chem., Vol. 63, No. 8, 1998
Pie´tri et al.
occurs in the first excited state or in the S0 ground state
after relaxation to a high vibrational energy level which
allows isomerization.
fique) and the Re´gion Provence-Alpes-Coˆte d’Azur (Cen-
tre Re´gional de Calcul Scientifique) are gratefully
acknowledged. We thank Professor H. Bodot and Dr. A.
Allouche for their invaluable remarks.
Ack n ow led gm en t. The CNRS (Institut du de´vel-
oppement et des Ressources en Informatique Scienti-
J O971217N