Synthesis and thermal stability of O-vinylketoximes

Article abstract of DOI:10.1055/s-2000-6330

The O-vinylketoximes 2 were synthesized from ketoximes 1 and acetylene in superbase systems in good to excellent yields. Their thermal stability was investigated.

Full text of DOI:10.1055/s-2000-6330

PAPER
1125
Synthesis and Thermal Stability of O-Vinylketoximes
Boris A. Trofimov,*a Al’bina I. Mikhaleva,a Alexander M. Vasil’tsov,a Elena Yu. Schmidt,a Ol’ga A. Tarasova,a
Ludmila V. Morozova,a Lubov’ N. Sobenina,a Thomas Preiss,b Jochem Henkelmannb
aIrkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk, Russian Federation
Fax +73952396046; E-mail: bat@irioch.irk.ru
bBASF Aktiengesellschaft, Ammoniaklaboratorium ZAR/C-M 311, 67056 Ludwigshafen, Germany
Received 16 February 2000; revised 21 March 2000
flow system; the O-vinylacetoxime 2a formed was
brought out with the acetylene flow into a trap cooled to
-78 °C. The formation of undesirable (in this case) pyr-
roles 3 and 4 during O-vinylacetoxime synthesis1 was
suppressed by water additives.2,3 At the same time, it is
known that the presence of water in the alkali-DMSO
system decreases its basicity15 and, consequently, the ke-
toxime-acetylene reaction rate. Indeed, variation of the re-
action conditions has shown the yields of O-vinyl-
acetoxime 2a to increase with decreasing the concentra-
tion of water and increasing the amount of alkali loading
(Table 2).
Abstract: The O-vinylketoximes 2 were synthesized from ke-
toximes 1 and acetylene in superbase systems in good to excellent
yields. Their thermal stability was investigated.
Key words: vinylation, O-vinylketoximes, ketoximes, acetylene,
superbase systems
O-Vinylketoximes, precursors in the synthesis of pyrroles
from ketoximes and acetylenes,1 contain a highly reactive
NO-vinyl group and attract much attention as promising
monomers and synthons. However, they are potentially
explosive and hence for their safe and proper application
in organic synthesis and polymer chemistry, the knowl-
edge of their thermal stability is crucial. Meanwhile, no
data of such a kind were so far published.
A significant growth (from 30% to 42%) of the yield of 2a
with increasing the amount of alkali (Table 2, runs 3-5)
or with reducing the acetoxime concentration (Table 2,
run 6) is observed under anhydrous conditions. The syn-
thesis of oxime 2a under the conditions of runs 3-5 may
be considered as a preparative one, but, though experi-
mentally simple, it suffers from shortcomings. First, a
considerable portion of the initial acetoxime transforms to
the pyrroles 3a and 4a. Second, a loss of O-vinylace-
toxime 2a is observed owing to its high volatility in the
presence of acetylene; in the trap a solution with a many-
fold excess of liquid acetylene over that of the product 2a
is condensed. Therefore, an uptake of the product 2a with
acetylene occurs upon slow heating of the condensate to
ambient temperature. Third, by the same reason and due
to the formation of large volumes of explosive liquid acet-
ylene the scaling up of the synthesis becomes difficult.
Direct acetylene vinylation of a ketoxime, namely ace-
toxime 1a, was first reported 20 years ago.2 The reaction
was carried out under atmospheric pressure at 110 °C, the
yield of O-vinylacetoxime being 10%. Later, the yield
was improved up to 78% by carrying out the reaction in an
autoclave (80-90 °C, initial acetylene pressure 15 atmo-
spheres) and by use of fractional vinylation.3 However,
this procedure turned out to be poorly reproducible.
A series of vinylketoximes 2 was unselectively prepared
by using superbase systems MOH-DMSO (M = Li, Na,
K) under acetylene pressure,3-12 with the help of indirect
methods using halogen derivatives.13,14 The synthetic con-
ditions and yields of 2 are presented in Table 1.
The goal of the present work was to develop high-perfor-
mance and reliable synthetic routes to O-vinylketoximes
of accessible alkyl- and arylmethylketones and to under-
take their stability investigation.
Using vinylation of acetoxime 1a (R1 = Me, R2 = R3 = H)
as a model, the effect of the reaction parameters on the
yield and purity of O-vinylketoximes under both atmo-
spheric and elevated pressure has been examined. The re-
sults of acetoxime vinylation under atmospheric pressure
are presented in Table 2. The runs were carried out in a
In order to intensify the reaction a series of runs were per-
formed under acetylene pressure (16-17 atmospheres)
(Table 3). When the reaction was carried out under milder
conditions than those reported,3 the oxime 2a was pre-
pared in a yield as low as 29% (Table 3, run 1). Further
temperature decrease to 77 °C and shortening the reaction
time to 6-10 minutes under anhydrous conditions allow
neither selective reaction nor noticeable increase in yield
(Table 3, run 2). A more efficient vinylation occurs only
with reducing the reagent and catalyst concentrations (Ta-
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

1126
B. A. Trofimov et al.
PAPER
Table 1 Preparative Yields of and Synthetic Routes to all the Known
O-Vinylketoximes 2
Pentane proved to be the most appropriate inert liquid
phase (Table 3, run 4, yield of oxime 2a: 75.6%, purity
~100%). The pentane:DMSO optimal ratio is 0.8 (Figure).
O-Vinylketoxime
Yield, %
Direct Vinylation
Other
Methods
R1
R2
R3
Atmospher- Autoclave
ic pressure
Me
t-Bu
Ph
H
H
H
H
H
H
H
H
H
103
163
126
723
603
463
203
383
563
378
4114
4-ClC6H4
2-Furyl
H
H
H
613
2-Thienyl
Ph
4313
Me Me
2,5-Me2C6H3
4-H2NC6H4
H
H
H
H
H
H
1010
311
Figure O-Vinylacetoxime yield versus pentane:DMSO volume ra-
tio
1-Methyl-2-
pyrrolyl
4112
As O-vinylacetoxime boiling point is close to 100 °C
(720 mm Hg, depending on the atmospheric pressure),
high-boiling hydrocarbons (dodecane and vaseline oil)
were also tried as inert phases; but in this case, the ace-
toxime vinylation was completely suppressed. At the
same time, the use of lower-boiling hydrocarbons (such as
hexane, petroleum ether, bp: 40-70 °C) makes the purifi-
cation of O-vinylacetoxime difficult because of the low
difference between their boiling points. Diethyl ether in-
hibited the formation of not only pyrroles, but of the target
oxime 2a (Table 3, run 5). The preparation of O-vinylac-
etoxime in the system KOH-DMSO-diethyl ether in a
yield of 52.5% requires longer time (1 hour) and higher
reaction temperature (77 °C) compared to acetoxime vi-
nylation in the system KOH-DMSO [~0.1 hour and
70 °C (Table 3, run 4)]. As catalysts, RbOH and CsOH
1-Methyl-3-
indolyl
H
H
H
H
H
549
1,2-Dimethyl-
3-indolyl
109
219
1,2-Dimethyl- Me
3-indolyl
1,2-Dimethyl- Et
3-indolyl
Me 259
ble 3, run 3). It should be noted that under anhydrous con-
ditions the reaction is difficult to control due to a large
exothermal effect.
In order to make the synthesis of O-vinyloxime 2a more were tried in the pentane-DMSO system.
controllable we used a second inert liquid phase unmix-
It is known that the nature of cation in MOH exerts signif-
able with DMSO to dissolve and bring the forming O-vi-
nylacetoxime 2a out of the reaction zone, thus preventing
it from further transformation to pyrroles 3a and 4a.
icant effect on the catalytic activity of the MOH-DMSO
system that, as a rule, increases with increasing the M
atomic mass. CsOH formed in situ in the reaction mixture
from MOH and CsX was supposed to catalyze the ace-
Table 2 Acetoxime Vinylation under Atmospheric Pressure
Run
Oxime (g)
KOH (g)
DMSO (mL)
H2O (g)
T (oC)
Time (h)
Yield (%)
3a
2a
4a
1a
2
3
4
5
6
7
7.0
14.0
7.0
7.0
7.0
2.8
2.8
2.8
5.6
8.4
50
50
50
50
50
50
250
2.8
2.8
no
no
no
no
no
110
6
9
6
6
6
3
6
8–15
4
52–60
trace
15
50
53
32–33
trace
trace
6
2
12
92–95
95–97
95–97
92–95
95–97
95–97
30
37
42
39
29
3.5
16.8
2.8
16.8
33
trace
trace
a Based on the results of a series of runs.
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Synthesis and Thermal Stability of O-Vinylketoximes
1127
Table 3 Acetoxime Vinylation under Acetylene Pressure
Run
Oxime (g)
KOH (g)
DMSO (pentane),
(mL)
T (oC)
Time (h)
Yield (%)
3a
2a
4a
2.3
12.7
trace
no
no
2.0
no
1
2
3
4
5
12.5
12.5
6.25
6.25
6.25
12.5
12.5
6.25
6.25
6.25
15
10
250a
125
125
125 (100)
125 (60)b
125 (100)
125 (100)
125 (100)
125 (100)
125 (100)b
83
77
74
70
77
78
73
69
70
80
2.0
~0.1
0.5
~0.1
1.0
2.0
2.0
~0.1
~0.1
1.0
29.0
38.2
65.9
75.6
52.5
46.7
56.4
86.9
75.6
12.2
5.0
0.2
8.0
no
no
3.0
no
no
no
trace
5.0
5.0
5.0
4.1d
7.0 e
5.0
5.0
5.0
6c
7c
8c
9f
10g
no
no
trace
a 15 g of H2O is added.
bDiethyl ether instead of pentane.
c 25.0 g of CsF is added.
d LiOH instead of KOH.
f NaOH instead of KOH, 12.7 g of CsCl is added.
g 11.4 g of CsF is added.
toxime vinylation more actively than KOH. Therefore a R2 = R3 = H) and previously unknown O-vinylmethyliso-
series of tests has been carried out to examine the effect of propylketoxime 2c (R1 = Me, R2 = R3 = Me) as well as O-
the CsX-MOH systems (M = Li, Na, K; X = F, Cl) on the vinyldiisopropylketoxime 2d (R1 = i-Pr, R2 = R3 = Me)
synthesis of O-vinylacetoxime in a two-phase system; are shown in Table 4.
DMSO-pentane (Table 3, runs 6-10). The highest activ-
In runs 2-4, the pyrroles 3 were identified as impurities.
ity was observed with the CsF-KOH pair. In this case, the
Besides, in all the runs the corresponding ketones 5 result-
impurity-free oxime 2a was prepared at a lower tempera-
ture in 86.9% yield (Table 3, run 8). This supports CsOH
ing from deoximation of the initial ketoximes 1 or O-vi-
nylketoximes 2 were revealed.
reputation as the strongest base and most active catalyst of
the nucleophilic additions to acetylene.16
R2R3CH
The replacement of DMSO by NMP with water content of
C=O
1 (2)
approximately 1% did not allow preparation of O-vinylac-
etoxime even in trace amounts, in spite of the fact that the
potassium oximate prepared beforehand was used. As
shown by potentiometric titration of the reaction mixture,
the lactone NMP ring-opening takes place to form the po-
tassium salt of g-aminobutyric acid. With N-methylpyr-
rolidones (NMP) (water content < 0.2%) under the
conditions of run 3 (Table 3) O-vinyloxime 2a was ob-
tained without impurities, though in low yield (~16%).
R1
5
Thus, close to optimal conditions of the dialkylketoxime
vinylation have been found. This enables O-vinyldialkyl-
ketoximes to be prepared in a yield of up to 88% (the prep-
aration of O-vinylpinacolonoxime 2b in 60% yield in an
autoclave was reported).3
Thus, the above investigations have enabled the develop-
ment of a preparative method for the synthesis of O-vinyl-
acetoxime under atmospheric pressure in 42% yield (32%
higher than in the known procedure).2 A two-phase sys-
tem pentane-DMSO has been first applied for the ace-
toxime vinylation under pressure. This made it possible to
shorten the reaction time (~6 minutes), obtain O-vinyl-
acetoxime in 86.9% yield, inhibit pyrrolization of the O-
vinylacetoxime formed and the side reactions of acetylene
with water, which lead to hardly separable
vinyloxybutadienes3 and make the reaction a controllable
process. A feasibility of acetoxime vinylation in NMP has
been demonstrated.
Table 4 Synthesis of O-Vinyldialkylketoximes under Acetylene
Pressure (16 atm) [Ketoxime 1b–d (85.6 mmol), KOH (5.64 g,
85.6 mmol), Pentane (100 mL), DMSO (125 mL), 0.1 h]
Run
Ketoxime
T
(∞C)
Yield (%)
Pyrrole
O-Vinyl-
ketoxime
Ketone
1
2
3
4
5
1b
1b
1b
1c
1d
67
70
73
70
70
2b, 59.4
2b, 74.8
2b, 73.8
2c, 51.2
2d, 87.8
3b, none
3b, 1.9
3b, 0.6
3c, trace
none
5b, 6.2
5b, 1.9
5b, 2.7
5c, trace
5d, trace
The optimal conditions found for the acetoxime 1a vinyl-
ation at elevated acetylene pressure in the two-phase sys-
tem pentane-DMSO were applied to the synthesis of oth-
er aliphatic O-vinylketoximes. The conditions and results
of the syntheses of O-vinylpinacolonoxime 2b (R1 = t-Bu,
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

1128
B. A. Trofimov et al.
PAPER
The effect of factors influencing the yields and the selec- ta, one should be very careful when working with pure
tivity of acetoxime vinylation was investigated in the syn- new O-vinylketoximes.
thesis of O-vinylketoximes having aromatic substituents.
As reported earlier,3 O-vinylketoximes can be kept for a
The experimental results are presented in Table 5.
long time in a refrigerator without noticeable changes.
The addition of petroleum ether (PE) (Table 5, runs 2-5) Comparison of runs 1 and 2 (Table 6) does not show the
with a simultaneous temperature decrease from 75 °C to generation of any explosion-initiating impurities in O-vi-
58 °C allows selective vinylation to be carried out.
nylacetoxime during its storage for 10 months at room
temperature in a sealed vessel.
O-Vinylalkylarylketoximes, especially those having elec-
tron-withdrawing substituents, are more prone to pyr- Dilution of O-vinylacetoxime with toluene (1:1) makes it
rolization compared to their aliphatic analogs.3 Therefore safe and allows the mixture to be distilled under atmo-
it could be expected that O-vinylacetophenonoximes with spheric pressure. It should be noted that slightly higher
electron-donating substituents in the benzene ring would boiling toluene always dominates in the distillation vessel
be more resistant to pyrrolization than the unsubstituted thus bringing up safe concentration in the still. The 1:4
O-vinylacetophenonoxime and this would allow a more toluene-O-vinylacetoxime mixture explodes but at a
selective preparation of the corresponding O-vinyl- higher temperature (Table 6, run 4), than it does without
oximes. This suggestion has been proven experimentally. toluene. In the presence of CuBr, the explosion of O-viny-
Thus, if some amount of 2-phenylpyrrole 3e is always loxime 2a occurs even below room temperature (Table 6,
present in the acetophenonoxime-acetylene reaction mix- run 5).
tures obtained under the conditions of runs 1-5, then the
Solid products from the explosive decomposition of the
reactions of the methylarylketoximes 1f and 1g with acet-
O-vinyloxime 2a (10-25% yield) were examined. These
ylene proceed selectively to afford the corresponding
are dark-brown lustrous polymers, soluble in organic sol-
O-vinylketoximes as the only reaction products (Table 5,
vents (methanol, acetone, chloroform, DMSO). Their IR
spectra (chloroform films) display broad bands and high
runs 6 and 7).
It has been reported3 that O-vinylacetoxime can explode background, that are characteristic of polymers. The
during distillation under normal pressure. In order to as- bands of CH3 and CH2 groups (n = 2870-2962, 1435,
sess the thermal stability of selected O-vinylketoximes, 1378 cm-1) and bond stretching vibrations (n = 1177
we have conducted measurements of the heats and tem- cm-1) remain in the spectrum. Also, there is a broad in-
peratures of decomposition using differential scanning tense signal at n = 1650-1697 cm-1 in which a C=N
calorimetry (DSC) as well as the explosion temperature stretching vibration frequency at n = 1662 cm-1 and a
upon heating the samples in sealed ampoules. Explosion C=O signal at n = 1697 cm-1 are distinguished. The C=C
temperature tests for O-vinylacetoxime were carried out double bonds may be present in this region too, whereas
with the additives supposedly inhibiting the decomposi- the CH2=CH-O group absorption bands (n = 3120, 3040,
tion.
1620, 1320, 1220, 980, 840 cm-1)18 practically disappear.
In addition, a series of new absorption bands appear.
These are intense bands at n = 3290 (NH) and 754 cm-1
(O-N=O) and weak bands at n = 2218 (C∫N) and 1074 (C-
O) cm-1.
From the data obtained (Table 6) it follows that O-vi-
nylketoximes are unstable energetic compounds (for com-
parison: Enthalpy of explosion of mercury fulminate, a
known explosive compound is 1790 J/g17) with any corre-
lation of energies of decomposition with molecular mass In the 1H NMR spectra of the polymers, there are signals
and radical branching being fuzzy. Considering these da- of CH= groups (d = 6.61, 6.08, 5.86 ppm), CH2-polymer
chain (d = 3.43 ppm) and a broad multiplet of alkyl group
Table 5 The Effect of Reaction Conditions on the Synthesis of O-vinylacetophenonoximes 2e–g (e: R1 = Ph, R2 = R3 = H; f: R1 = 4-EtC6H4,
R2 = R3 = H; g: R1 = 4-MeOC6H4, R2 = R3 = H)
Run
Ketoxime
DMSO/PE (mL)
T (∞C)
Time (h)
Yield (%)
O-Vinylketoxime Pyrrole
Vinylpyrrole
4e, 0.8
4e, 8.5
4e, 0.2
4e, no
1
2
3
4
5
6
7
1e
1e
1e
1e
1e
1f
100/0
75
75
70
66
58
60
60
2.0
2.0
2e, 4.5
2e, 14.3
2e, 24.8
2e, 33.9
2e, 51.0
2f, 41.3
2g, 52.4
3e, 53.4
3e, 46.4
3e, 32.7
3e, 3.4
3e, 0.7
3f, no
100/50
150/100
150/100
75/50
1.0
~0.1
2.0
4e, no
75/50
1.0
4f, no
1g
75/50
1.0
3g, no
4g, no
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Synthesis and Thermal Stability of O-Vinylketoximes
1129
Table 6 Temperatures and Energies (dQ) of Decomposition of O-vi-
nylketoximes 2a–e (0.4 g, Temperature Rise Rate 4 oC/min, Maxi-
mum Heating Temperature: 220 C)
pounds in the condensate. In the spectrum there are also
bands of CH3 and CH2 group stretching vibrations (n =
2964, 2873, 2740, 1467, 1370 cm-1), an intense band
nC∫N (2243 cm-1) as well as a fundamental intense re-
solved band nC=O at 1705-1719 cm-1. Apart from these, a
broadened band appears in the n = 3612-3432 cm-1 re-
gion (possibly it is nOH of water either originated by de-
composition or absorbed from air). The structures of the
O-vinylketoxime decomposition products are supported
by the 1H NMR data. The 1H NMR spectra display signals
of the methylene (d = 0.81-1.22 ppm) and CH3C=O
groups (d = 1.95-1.98 ppm) and a small signal corre-
sponding to the aldehyde function HC=O (d = 9.80 ppm).
Owing to a low concentration of propane in the mixture of
volatile decomposition products, there are no signals of
the CH3 and CH2 groups in the d = 15-16 ppm region in
the 13C NMR spectrum.
o
Run O-Vinylketoxime Decomposition dQ
Explosion
(additive, %)
Temperaturea
(J/g) Temperatureb
(∞C)
(∞C)
1
2
3
4
5
6
7
8
9
2a
102–110
1800 144
2ac
145
2a (PhMe, 30)
no explosion
160
2a (PhMe, 20)
2a (CuBr, 4)
<20
2b
2c
2d
2e
115–134
114–135
110–130
130–150
1536 no explosion
834 143
1327 no explosion
1267 155
All the O-vinylketoximes synthesized are relatively stable
at room temperature. For example, when O-vinylace-
toxime 2a was kept for 10 months (initial purity was
98.7%, impurities were 0.2% of acetone and 1.1% of
vinyloxybutadienes19), the acetone concentration was
only increased to 2.5%. In addition, a brown polymeric
product (~2.0% yield) was isolated.
a DSC.
b In a sealed ampoule.
c Sample kept at room temperature over 10 months prior to the test.
The polymer gives an asymmetrical EPR singlet of free
electron (g = 2.0048, DH = 8.8 Oe, N = 2.807. 1018 sp/g)
corresponding to a polyconjugated system, apparently,
polyacetylene formed according to the following scheme:
signals (d = 0.83-2.20 ppm). Signals of the CH2= groups
present in the initial monomer (d = 4.05 and 4.53 ppm) are
not observed in the polymers.
Thus, the products obtained are likely to be copolymers
containing both O-vinylacetoxime units and fragments re-
sulting from O-vinylacetoxime thermal decomposition.
The analysis of liquid and gaseous products of thermal de-
composition was carried out with an O-vinylpinacolon-
oxime 2b sample, that did not explode even at 220 °C. In
this case the ratio of the isolated gaseous, liquid and solid
products was approximately 4:45:51. The liquid products
were examined by GLC, IR, 13C and 1H NMR spectrosco-
py, and GLC-MS spectrometry. Of eight compounds
fixed by the GLC-MS method, four species constituting
93.8 ms% were identified. These are 3,3-dimethyl-2-bu-
tanone, 2,2,3,3-tetramethylbutane, acetonitrile and pro-
pane dissolved in the liquid (the major propane portion is
emitted into air upon opening the ampoules).
The rearrangement of O-vinylketoximes 2 to the parent
ketones 5 and acetonitrile upon storage or heating may in-
volve the formation of nitrone 6 followed by the release of
vinylnitrene 7 further rearranging to acetonitrile (see de-
composition of O-vinylpinacoloneoxime), polymerizing
or copolimerizing with the O-vinylketoxime.1,20
Since under normal conditions the decomposition of O-vi-
nylketoximes proceeds very slowly, the rate of O-vinylac-
etoxime decomposition at 97 °C was evaluated using a
12.5% O-vinylacetoxime solution in octane. The samples
of reaction mixtures were taken every 10 minutes and an-
alyzed by GLC (octane as an internal standard). The kinet-
ic curve of O-vinylketoxime concentration change
corresponds to that described by the first order equation
(k = 1.15.10-4 sec-1):
-lnx = kt,
where x is the O-vinylacetoxime conversion and t is the
reaction time. Taking into account that in the reaction
mixture only a brown insoluble polymer is formed and
that neither liquid nor gaseous products are discernible, it
is suggested that a thermopolymerization is the main di-
The IR spectrum of the liquid fraction shows no bands
corresponding to the initial O-vinylketoximes and pro-
vides strong evidence for the presence of the above com-
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

1130
B. A. Trofimov et al.
PAPER
R2R3CH
R1
R2R3CH
R1
R2R3CH
R1
O
+
N
N
C
N
O
-
O
2
6
R2R3CH
C
O
+
polymer
N
N
N
R1
7
5
H
N
C CH3
C=CH2
:N
rection of the O-vinylacetoxime transformation upon
heating under the explosion temperature (140-145 °C).
(125 mL) at 110-115 °C for 5 min. The mixture is saturated with
acetylene under pressure (16 atm) and subjected to heating for 30
min to the reaction temperature of 74 °C. Once the reaction temper-
ature is reached, the heating is immediately stopped, and the auto-
clave furnace opened. After cooling to r.t., the reaction mixture is
discharged, neutralized with dry ice, and analyzed by GLC. The re-
action mixture contains O-vinylacetoxime 2a (5.57 g, 65.9% yield)
and 2-methylpyrrole (0.55 g, 8.0% yield) (Table 3, run 3).
1H and 13C NMR spectra were run on Bruker Avance DPX 250 (250
MHz) and Joel FX-90Q (90 MHz) instruments in CDCl3, HMDS as
internal standard. IR spectra were recorded on Bruker IFS 25 and
Specord 75 IR spectrometers in microlayer. GLC was performed on
an LCM-80 chromatograph: column 3.5 m ¥ 3 mm, liquid phase
XE-60 on Chromaton N-AW-HMDS, detector katharometer, gas-
carrier He, temperature programming rate 8-12 °C/min.
Vinylation of Acetoxime under Pressure in the KOH-Pentane-
DMSO System
A steel 1 L rotating autoclave is charged with pentane (100 mL) and
a potassium oximate solution in DMSO prepared by heating of a
mixture of acetoxime (6.25 g, 85.5 mmol) KOH (5.0 g, 75.5 mmol)
and CsF (25.0 g, 164.5 mmol) in DMSO (125 mL) at 110-115 °C
for 10 min. The mixture is saturated with acetylene and subjected to
heating for 30 min at 69 °C and kept at this temperature for 2 h. Af-
ter this, the autoclave furnace is opened and the reaction mixture
cooled to r.t. Excess acetylene is let out to normal pressure through
a trap cooled with a mixture of acetone and dry ice (-78 °C). The
reaction mixture is discharged, and the pentane layer separated. Af-
ter vacuum distillation (1-3 mm Hg) of volatile products from DM-
SO, they are combined with the pentane solution and the trap
condensate, washed with H2O, dried (calcined MgSO4), and ana-
lyzed by GLC (O-vinylacetoxime content: 7.36 g, yield 86.9%) (Ta-
ble 3, run 8). No acetoxime is present in the reaction mixture (GLC).
The heats and temperatures of O-vinylketoximes decomposition
were measured by differential scanning calorimetry on a Universal
V2.3C TA instrument. Mass spectra were run on an LKB 2091
CLC-MS spectrometer, ionization energy 60 eV, capillary column
38 m long, SB-5 phase, isothermal conditions, column temperature
40 °C, ion source temperature 200 °C.
Commercial grade DMSO with H2O content of ~0.4% and NMP
(Merck, <0.2% H2O), LiOH and NaOH (<2% H2O), KOH (~15%
H2O, in fact 2KOH•H2O), CsF and CsCl (ABCR, 99+%) were used
in experiments.
Synthesis of O-Vinylacetoxime 2a under Atmospheric Pressure
Into a three-necked 100 mL flask equipped with a magnetic stirrer,
bubbler, thermometer, dropping funnel and a gas outlet connected
with a trap cooled to -78 °C, KOH (8.4 g, 128 mmol) and DMSO
(50 mL) are placed and heated on a boiling water bath (92-95 °C).
Then the reaction mixture is saturated with acetylene for 15 min and
acetoxime 1a (7 g, 96 mmol) in DMSO (20 mL) is added dropwise
while bubbling acetylene for 4 h. Then acetylene is bubbled for 2 h
more. The O-vinylacetoxime formed is condensed in the trap to-
gether with dissolved acetylene. The contents of the trap are heated
to r.t. (which is accompanied by liberation of the dissolved acety-
lene) and H2O (1 mL) is added to the remaining mixture of volatile
reaction products. The upper layer is separated, dried (MgSO4),
weighed and analyzed (GLC). As a result, O-vinylacetoxime
(4.45 g, 89% purity) corresponding to 3.96 g (49 mmol) of pure
product is obtained. The yield of O-vinylacetoxime is 42% (Table
2, run 5).
Vinylation of Acetoxime in the KOH-Et2O-DMSO System
A steel 1 L rotating autoclave is charged with Et2O (60 mL) and a
potassium oximate solution in DMSO prepared by heating of a mix-
ture of acetoxime (6.25 g, 85.5 mmol) and KOH (5 g, 75.5 mmol)
in DMSO (125 mL) at 110-115 °C for 10 min. The mixture is sat-
urated with acetylene under pressure (11 atm), heated for 30 min to
77 °C and kept at this temperature for 1 h. Then the autoclave fur-
nace is opened and the reaction mixture cooled to r.t. Excess acety-
lene is let out to normal pressure through a trap cooled to -78 °C.
The reaction mixture is discharged, the Et2O layer separated. From
the DMSO layer, the reaction products are distilled off in vacuum
(1-3 mm Hg) and combined with the Et2O solution and the trap
condensate, washed with H2O, dried (calcined MgSO4), and ana-
lyzed by GLC. The yield of O-vinylacetoxime is 52.5% (Table 3,
run 5).
Vinylation of Acetoxime under Pressure in the KOH-DMSO
System
A steel 1 L rotating autoclave is charged with a potassium oximate
solution in DMSO prepared by heating of a mixture of acetoxime
(6.25 g, 85.5 mmol) and KOH (5.0 g, 75.5 mmol) in DMSO
Vinylation of Acetoxime in the KOH-NMP System
A steel 1 L rotating autoclave is charged with acetoxime (6.25 g,
85.5 mmol), KOH (5.0 g, 75.5 mmol) in NMP (125 mL). The mix-
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Synthesis and Thermal Stability of O-Vinylketoximes
1131
ture is saturated with acetylene under 14 atm pressure, and heated
for 30 min to 75 °C. Then the autoclave furnace is opened and the
reaction mixture is cooled to r.t. Excess acetylene is let out to nor-
mal pressure through a trap cooled with a mixture of acetone and
dry ice (-78 °C). The reaction mixture is discharged, neutralized
with dry ice, and analyzed by GLC. The reaction mixture contains
O-vinylacetoxime (1.35 g, yield: 15.9%).
1H NMR (250 MHz): d = 6.827 (q, CH = ), 4.496 and 4.013 (dd, J
trans = 14.3, Jcis = 6.9, Jgem = 1.4 Hz, CH2 = ), 3.023 and 2.544 [m,
2CH(CH3)2], 1.146 and 1.119 [d, 2CH(CH3)2].
13C NMR (62.89 MHz): d = 171.343 (>C = N), 152.872 ( = CH),
86.716 ( = CH2), 31.463, 28.858 [2CH(CH3)2], 21.064, 19.119
[2CH(CH3)2].
Anal. Calcd for C9H17NO: C, 69.63; H, 11.04; N, 9.02. Found: C,
69.47; H, 10.98; N, 9.09.
Vinylation of Pinacolonoxime in the KOH-Pentane-DMSO
System
Vinylation of Acetophenonoxime 1e in the KOH-Petroleum
ether-DMSO System
A steel 1 L rotating autoclave is charged with pentane (100 mL) and
a potassium oximate solution in DMSO prepared by heating of a
mixture of pinacolonoxime (9.85 g, 85.6 mmol) and KOH (5.64 g,
85.6 mmol) in DMSO (125 mL) at 110-115 °C for 5 min. The mix-
ture is saturated with acetylene under 16 atm pressure and heated for
30 min to the reaction temperature 70 °C. After this time, heating is
ceased immediately and the autoclave furnace is opened, this means
about 6 min exposure to 70 °C. After cooling to r.t., the excess acet-
ylene is let through a trap cooled to -78 °C. The reaction mixture is
discharged and the pentane layer separated. The DMSO solution is
extracted with pentane 5 times. The pentane extracts are combined
with the trap condensate, washed with H2O (3 ¥ 20 mL), and dried
(calcined MgSO4). The major pentane portion is removed by distil-
lation. The remaining portion is distilled off in vacuum (50 mm Hg)
at 40 °C and analyzed by GLC. As a result, O-vinylpinacolonoxime
is obtained (6.98 g, 98.9% purity of the extract). The reaction mix-
ture is diluted with H2O, extracted with Et2O (4 ¥ 30 mL), the ex-
tract is washed with H2O to remove DMSO and dried (MgSO4).
Et2O is removed in the same manner as pentane. The residue is an-
alyzed by GLC to determine O-vinylpinacolonoxime (1.40 g, total
yield: 68.8%), pinacolonoxime (1.37 g, conversion 92%) and pina-
colone (1.9%). The yield of O-vinylpinacolonoxime corrected for
the incomplete conversion of initial ketoxime is 74.8% (Table 4, run
2).
A steel 1 L rotating autoclave is charged with petroleum ether (50
mL, bp 40-70 °C) and a potassium oximate solution in DMSO pre-
pared by heating of a mixture of acetophenonoxime 1e (6.75 g, 50
mmol) and KOH (3.0 g, 53.5 mmol) in DMSO (75 mL) at 115-
120 °C for 5 min. The mixture is saturated with acetylene under
pressure of 14 atm and heated for 30 min to the temperature of
58 °C, after that heating being continued for 2 h. After cooling to
r.t., the reaction mixture is discharged and the petroleum ether layer
separated. The DMSO solution is extracted with petroleum ether
(5 ¥ 20 mL). The extract is washed with H2O (3 ¥ 20 mL), dried
(MgSO4), and petroleum ether is removed by distillation to obtain
O-vinylacetophenonoxime 2e (4.11 g, 51.0%, 98.9% purity). The
reaction mixture is diluted with H2O and extracted with Et2O, the
Et2O extract is washed with H2O to remove DMSO and dried
(MgSO4). After Et2O removal, the residue containing 2-phenylpyr-
role 3e (0.05 g, yield: 0.7%) and acetophenonoxime 1e (2.19 g, con-
version 67.6%) is obtained (Table 5, run 5). Colorless oil, bp 80 °C
(4 mm Hg), [a]D20 1.5542.
O-Vinylacetophenonoximes 2f and 2g were prepared analogously.
O-Vinyl-4-ethylacetophenonoxime 2f
Colorless oil.
O-Vinylpinacolonoxime 2b: bp 71 °C (60 mm Hg), [a]D23 1.4400
IR: n = 3075 (n = CH), 2963 (nasCH3), 2934 (nCH2), 2838 (nsCH3),
1639 (ntransC = C), 1607, 1513 (ncisC = C benzene ring), 1459
(dasCH3), 1385 (dsCH3+dCH2), 1372 (dsCH3), 1249 (nC-C-C), 1172
(nC-O), 1119 (dCH3), 972 (nN-O), 958 (dtrans = CH), 885 (gC-C-C),
834 (gCH2, gCH3) cm-1.
1H NMR (90 MHz): d = 7.52-7.10 (m, Ph), 7.00 (q, CH = ), 4.64
and 4.10 (dd, CH2 = ), 2.56 (q, CH2), 2.21 (s, Me), 1.15 (t, MeCH2).
[Lit.3 bp 54-55 °C (26 mm Hg), [a]D20 1.4400].
O-Vinyloximes 2c and 2d were prepared analogously.
O-Vinylmethylisopropylketoxime 2c
Bp 75 °C (95 mm Hg), [a]D20 1.4390.
IR (E-isomer): n = 3050 (n = CH), 2969 (nas CH3), 2933 (nCH2),
2875 (nsCH3), 1669 (nC = N), 1652 (ntrans C = C), 1623 (ncis C = C),
1466 (dasCH3), 1386 (dsCH3+dCH2), 1367 (dsCH3), 1246 (n C-C-C),
1177 (nC-O), 1151 (dCH3, nC-O), 979 (nN-O), 957 (dtrans = CH),
875 (gC-C-C), 803 (gCH3) cm-1.
1H NMR (250 MHz) (E-isomer): d = 6.863 (q, CH = ), 4.531 and
4.046 (dd, Jtrans = 14.3, Jcis = 6.7, Jgem = 1.5 Hz, CH2 = ), 2.523 m
[CH(CH3)2], 1.846 (s, CH3), 1.091 [d, CH(CH3)2].
Anal. Calcd for C12H15NO: C, 76.19; H, 7.93; N, 7.41. Found: C,
76.37; H, 7.65; N, 7.23.
O-Vinyl-4-methoxyacetophenonoxime 2g
White crystals, mp 53-54 °C.
IR: n = 3075 (n = CH), 2963 (nasCH3), 2934 (nCH2), 2838 (nsCH3),
1639 (ntransC = C), 1607, 1513 (ncisC = C benzene ring), 1459
(dasCH3), 1385 (dsCH3+dCH2), 1372 (dsCH3), 1249 (nC-C-C), 1172
(nC-O), 1119 (dCH3), 972 (nN-O), 958 (dtrans = CH), 885 (gC-C-C),
834 (gCH2, gCH3) cm-1.
1H NMR (250 MHz) (Z-isomer): d = 6.846 (q, CH = ), 4.508 and 4.
044 (dd, Jtrans = 14.3, Jcis = 6.7, Jgem = 1.5 Hz, CH2 = ), 2. 405 [m,
CH(CH3)2], 1.807 (s, CH3), 1.034 [d, CH(CH3)2].
1H NMR (90 MHz): d = 7.60-6.87 (m, Ph), 7.00 (q, CH = ), 4.65
13C NMR (62.89 MHz) (E:Z = 6:1): d = 164.657 (>C = N), 152.615
( = CH), 86.999 ( = CH2), 34.295 [CH(CH3)2], 19.625 [CH(CH3)2],
11.830 (CH3).
and 4.13 (dd, CH2 = ), 3.77 (s, MeO), 2.24 (s, Me).
Anal. Calcd for C11H13NO2: C, 69.11; H, 6.81; N, 7.33. Found: C;
69.47; H, 7.05; N, 7.09.
Anal. Calcd for C7H13NO: C, 66.11; H, 10.30; N, 11.01. Found: C,
65.94; H, 10.17; N, 11.09.
A Technique to Determine O-Vinylketoxime Explosion Tem-
perature
O-Vinyldiisopropylketoxime 2d
Bp 59 °C (25 mm Hg), [a]D24 1.4386.
A sample of O-vinylketoxime 2a-e (400 mg) sealed upon cooling
(-78 °C) in a conventional glass ampoule (2.0 mL) was placed into
a brass casing with a capillary opening to remove excess pressure
and subjected to heating (bath, silicone oil). Explosion was accom-
panied by emission of volatile products. Immediately after the ex-
plosion, the bath temperature was fixed and the casing was cooled
IR: n = 3070, 3050 (n = CH), 2967 (nas CH3), 2934 (nCH2), 2875
(nsCH3), 1667 (nC = N), 1641 (ntrans C = C), 1619 (ncis C = C), 1486
(dasCH3), 1385 (dsCH3+dCH2), 1366 (dsCH3), 1246 (n C-C-C), 1181
(nC-O), 1154 (dCH3, nC-O), 1119 (dCH3), 979 (nN-O), 951
(dtrans = CH), 890 (gC-C-C), 829 (gCH2, gCH3) cm-1.
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York

1132
B. A. Trofimov et al.
PAPER
(7) Korostova, S. E.; Mikhaleva, A. I.; Nesterenko, R. N.;
Mazhnaya, N. V., Voronov, V. K.; Borodina, N. M. Zh. Org.
Khim. 1985, 21, 406; Chem. Abstr. 1985, 103, 53894.
(8) Korostova, S. E.; Shevchenko, S. G.; Sigalov, M. V. Khim.
Geterotsikl. Soed. 1991, 1371; Chem. Abstr. 1992, 117,
48251u.
(9) Yurovskaya, M. A.; Druzhinina, V. V.; Tyurekshodzhaeva,
M. A.; Bundel, Yu. G. Khim. Geterotsikl. Soed. 1984, 69;
Chem. Abstr. 1984, 100, 191693.
(10) Aliev, I. A.; Korostova, S. E.; Mikhaleva, A. I.; Shevchenko,
S. G.; Zeinalova, S. N.; Sobenina, L. N.; Sigalov, M. V.;
Gasanov, B. R. Khim. Geterotsikl. Soed. 1991, 1320; Chem.
Abstr. 1992, 117, 69688g.
(11) Korostova, S. E.; Shevchenko, S. G.; Sigalov, M. V. Khim.
Geterotsikl. Soed. 1991, 2, 187; Chem. Abstr. 1991, 115,
49308p.
(12) Korostova, S. E.; Shevchenko, S. G.; Sigalov, M. V.;
Golovanova, N. I. Khim. Geterotsikl. Soed. 1991, 460 Chem.
Abstr. 1991, 115, 183005u.
(13) Korostova, S. E.; Nesterenko, R. N.; Mikhaleva, A. I.;
Polovnikova, R. I.; Golovanova, N. I. Khim. Geterotsikl. Soed.
1989, 901; Chem. Abstr. 1990, 112, 178530s.
to r.t. A mixture of fine-dispersed fragments of glass and polymers
was treated with MeOH. The solution was separated by decantation.
After MeOH evaporation, 30-50 mg of a dark-brown powdery
product was collected.
Analysis of the O-Vinylpinacolonoxime 2b Decomposition
Products
A sample of O-vinylpinacolonoxime 2b (400 mg) was charged into
a glass ampoule (1.5 mL), the ampoule was cooled to -78 °C,
sealed, placed into a brass casing and heated (bath, silicone oil) to
220 °C, heating time 50 min. After cooling to r.t., the casing with
the ampoule was cooled in liquid N2, the ampoule was taken out and
unsealed. Upon elevating the ampoule temperature, a vigorous evo-
lution of gas from the reaction mixture took place. Two syntheses
conducted according to this procedure were combined and a color-
less liquid was collected on heating to 190 °C into a cooled trap.
Four major condensate components: 3,3-dimethyl-2-butanone
(39.3%), MeCN (32.2%), 2,2,3,3-tetramethylbutane (19.8%) and
propane (2.5%), altogether 93.8% of the mass, were identified
(GLC-MS, IR, 1H and 13C NMR).
References
(14) Dhanak, D.; Reese, C. B.; Romana, S. R.; Zappia, G. J. Chem.
Soc., Chem. Commun. 1986, 903.
(1) Trofimov, B. A.; Mikhaleva, A. I. N-Vinylpyrroles; Nauka:
Novosibirsk, 1984; p 264 (in Russian).
(2) Trofimov, B. A.; Mikhaleva, A. I.; Vasilyev, A. N.; Sigalov,
M. V. Izv. Akad. Nauk, Ser.Khim. 1979, 695; Chem. Abstr.
1979, 91, 385874.
(3) Tarasova, O. A.; Korostova, S. E.; Mikhaleva, A. I.; Sobenina,
L. N.; Nesterenko, R. N.; Shevchenko, S. G.; Trofimov, B. A.
Zh. Org. Khim. 1994, 30, 810; Chem. Abstr. 1995, 122,
186603q.
(4) Trofimov, B. A.; Korostova, S. E.; Mikhaleva, A. I.,
Sobenina, L. N.; Vasil’ev, A. N.; Nesterenko, R. N. Khim.
Geterotsikl. Soed. 1983, 273; Chem. Abstr. 1983, 98, 215435.
(5) Trofimov, B. A.; Korostova, S. E.; Mikhaleva, A. I.,
Sobenina, L. N.; Nesterenko, R. N. USSR Patent SU 1095593,
1982; Chem. Abstr. 1995, 123, 285266j.
(15) Trofimov, B. A.; Vasil’tsov, A. M.; Amosova, S. V. Izv. Akad.
Nauk, Ser. Khim. 1986, 751; Chem. Abstr. 1986, 104, 214113.
(16) Tzalis, D.; Knochel, P. Angew. Chem. 1999, 111, 1547.
(17) Khimicheskaya Entsiklopedia, Vol. 1; Sovetskaya
Entsiklopedia Publishers: Moskow, 1988; p 613.
(18) Trofimov, B. A. Heteroatomic Derivatives of Acetylene: New
Polyfunctional Monomers, Reagents, and Intermediates;
Nauka: Moscow, 1981; p 320 (in Russian).
(19) Tarasova, O. A.; Amosova, S. V. Trofimov, B. A. Zh. Org.
Khim. 1982, 18, 2042; Chem. Abstr. 1983, 98, 53127b.
(20) Trofimov, B. A.; Mikhaleva, A. I. Khim. Geterotsikl. Soed.
1987, 1299; Chem. Abstr. 1988, 109, 6333b.
Article Identifier:
1437-210X,E;2000,0,08,1125,1132,ftx,en;Z00900SS.pdf
(6) Korostova, S. E.; Mikhaleva, A. I.; Sobenina, L. N.;
Shevchenko, S. G.; Shcherbakov, V. V. Khim. Geterotsikl.
Soed. 1985, 1501; Chem. Abstr. 1985, 103, 53901.
Synthesis 2000, No. 8, 1125–1132 ISSN 0039-7881 © Thieme Stuttgart · New York