Study on reactions of 2-(dinitromethylene)-4,5-imidazolidinedione

Article abstract of DOI:10.1021/jo030395f

Some new reactions of 2-(dinitromethylene)-4,5-imidazolidinedione (1) with water, alcohols, carboxylic acids, and alkalis were discovered. By reaction of 1 with carboxylic acids, large particle size 1,1-diamino-2,2-dinitroethylene (2) was prepared. By reaction of 1 with methanol, the methanol adduct (4) was synthesized and characterized. By reaction of 1 with water, the synthetic pathway of 2-methylimidazole to 2 could be achieved in a continuous process. By reaction of 1 with KOH, 2 and potassium dinitromethane (6) could be formed at different temperature, respectively. Compounds 1 and 4 decomposed into parabanic acid (5), losing nitrogen oxides and carbon oxides. Some explosive properties of 1 were studied. The mechanisms of synthesis of 1, 2, and 5 are discussed.

Full text of DOI:10.1021/jo030395f

Stu d y on Rea ction s of 2-(Din itr om eth ylen e)-4,5-im id a zolid in ed ion e
Huaqiang Cai,*,1 Yuanjie Shu, Hui Huang, Bibo Cheng, and J inshan Li
Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900, China
danluxiusan@hotmail.com
Received December 30, 2003
Some new reactions of 2-(dinitromethylene)-4,5-imidazolidinedione (1) with water, alcohols,
carboxylic acids, and alkalis were discovered. By reaction of 1 with carboxylic acids, large particle
size 1,1-diamino-2,2-dinitroethylene (2) was prepared. By reaction of 1 with methanol, the methanol
adduct (4) was synthesized and characterized. By reaction of 1 with water, the synthetic pathway
of 2-methylimidazole to 2 could be achieved in a continuous process. By reaction of 1 with KOH, 2
and potassium dinitromethane (6) could be formed at different temperature, respectively.
Compounds 1 and 4 decomposed into parabanic acid (5), losing nitrogen oxides and carbon oxides.
Some explosive properties of 1 were studied. The mechanisms of synthesis of 1, 2, and 5 are
discussed.
SCHEME 1
1. In tr od u ction
2-(Dinitromethylene)-4,5-imidazolidinedione (1) was
reported in 1998 for the first time.1 It is an important
intermediate which can be aminated to form 1,1-diamino-
2,2-dinitroethylene (2) by aqueous ammonia (see Scheme
1). Compound 2 is also named as FOX-7, with high
performance and low sensitivity, and is known to be a
new energetic material with promising properties as an
attractive ingredient for application in high explosive
formulations.2 In recent years, many properties of FOX-7
have been studied.3-8
But except for this reaction, no more new reactions
involving with 1 have been reported up to now, so the
chemical properties of 1 are not investigated sufficiently.
Our experiments have confirmed that 1 has many new
reaction characters. In the structure of 1, the amide
bonds are reactive and easy to break, while the gem-
dinitro is unstable and also easy to decompose. In
addition, 1 is an explosive and can explode in certain
conditions to produce a great deal of gas products, so we
have expected that 1 can process three different reac-
tions: ring cleavage, losing nitrogen oxides, and explosive
decomposition. These have indeed proved to be the case.
Through experiments we have synthesized the metha-
nol adduct of 1 and have mastered the preparation
method of 2 with large particles, which can be used in
the formulation directly and do not need recrystallization.
2. Resu lts a n d Discu ssion
2.1. Rin g Clea va ge. The carbonylation in molecule 1
links with amino directly and is strongly polarized. The
highly electronegative oxygen leaves the carbon atom a
partial positive charge. Therefore, it is reasonable to
expect nucleophilic reagents or nucleophiles to attack the
carbon atom of the carbonylation.9 The reaction of 1 with
nucleophiles such as KOH, CH3OH, H2O, and HCOOH
can be accounted for on this basis.
Attempts to obtain product 3 (see Scheme 2) failed. The
possible reason was that 3 was unstable and easily
attacked by the second nucleophile. The experimental
results indicated that the two carbonylations could be
replaced, and then 2 and the corresponding oxalic deriva-
tives were produced (see Scheme 3).
(1) Latypov, N. V.; Bergman, J .; Langlet, A.; Wellmar, U.; Bemm,
U. Tetrahedron 1998, 54, 11525.
(2) O¨ stmark, H.; Langlet, A.; Bergman, H.; Wingborg, N.; Wellmar,
U.; Bemm, U. 11th Detonation (International) Symposium, Snowmass,
CO, 1998; pp 807-812.
(3) Bemm, U.; Oatmark, H. Acta Crystallogr. 1998, C54 (12), 1997-
1999.
(4) O¨ stmark, H.; Bergman, H.; Bemm, U.; Goede, P.; Holmgren, E.;
J ohansson, M.; Langlet, A.; Latypov, N. V.; Pettersson, A.; Pettersson,
M.-L.; Wingborg, N.; Vorde, C.; Stenmark, H.; Karlsson, L.; Hihkio,
M. 32nd ICT International Annual Conference on Energetic Materials,
Karlsruhe, Germany, 2001; pp 26/1-21.
(5) Eldsater, C.; Edvinsson, H.; J ohansson, M.; Pettersson, A.;
Sandberg, C. 32nd ICT International Annual Conference on Energetic
Materials, Karlsruhe, Germany, 2001; pp 63/1-14.
(6) Bellamy, A.; Goede, P.; Sandberg, C.; Latypov, N. V. 33rd ICT
International Annual Conference on Energetic Materials, Karlsruhe,
Germany, 2002; pp 3/1-9.
(7) Holmgren, E.; Carlsson, H.; Geode, P.; Latypov, N. V. 34th ICT
International Annual Conference on Energetic Materials, Karlsruhe,
Germany, 2003; pp 107/1-10.
(8) )Matyushin, N.; Afanasev, G. T.; Lebedev, V. P.; Mahov, M. N.;
Pepekin, V. I. 34th ICT International Annual Conference on Energetic
Materials, Karlsruhe, Germany, 2003; pp 119/1-13.
2.1.1. Rea ction of 1 w ith Meth a n ol. Compound 1
was treated with dilute hydrogen chloride to form a
(9) Xing, Q. Y.; Xu, R. Q.; Zhou, Z.; Pei, W. W. Basic Organic
Chemistry; High Education Press: Beijing, China, 1993; p 595.
10.1021/jo030395f CCC: $27.50 © 2004 American Chemical Society
Published on Web 06/02/2004
J . Org. Chem. 2004, 69, 4369-4374
4369

Cai et al.
TABLE 1. Effect of Tem p er a tu r e on Yield of th e
SCHEME 2
P r od u ctsa
T (°C)
0
12.8
0
20
98.0
0
40
95.1
0
60
yield of the adduct (%)
yield of FOX-7 (%)
yield of parabanic acid (%)
21.0
74.3
2.1
14.9
0
3.3
a
Methanol (200 mL), 2-(dinitromethylene)-4,5-imidazolidinedi-
one (0.01 mol), reaction 30 min, Fe and dilute hydrogen chloride
(catalytic amount).
SCHEME 3
SCHEME 6
SCHEME 4
SCHEME 7
SCHEME 5
yield of 4, and parabanic acid (5) was the major product
formed (14.9% optimum at 0 °C, see Scheme 6). While a
higher reaction temperature (above 50 °C) caused ring
cleavage of 1, 2 was the major product (74.3% optimum
at 60 °C).
There were three routes in the reaction of 1 with
methanol, so three different products (2, 4, and 5) were
formed. Generally, more energy was needed in the
reaction of ring cleavage, so Scheme 4 proceeded easily
when the temperature was high (above 50 °C), while little
energy was needed in the self-decomposition of 1, so
Scheme 6 proceeded easily when the temperature was
low (below 0 °C). Forming hydrogen bonds was essential
for producing the methanol adduct, which needed ap-
propriate energy, so Scheme 5 proceeded easily at the
proper temperature (10-40 °C).
mixture at >50 °C. When methanol was added, the white
solid dissolved immediately to form a yellow solution,
and in a few seconds bright yellow crystals precipi-
tated. Spectral analysis proved the product was 2 (see
Scheme 4).
When 1 was treated with methanol at ambient tem-
perature, yellow needle crystals 4 (see Scheme 5) were
formed. Spectral analysis proved 4 was a methanol
adduct of 1. Compound 4, now reported for the first time,
is the first adduct of 1. It cannot be dissolved in common
organic solvents and water, is found to be more thermally
stable than 1, and can exist stably in the air for a long
time. The thermogravimetry (TG) spectrum shows at
least three steps. This gives an indication that a three-
step process characterizes the initial decomposition of 4.
The differential scanning calorimetry (DSC) spectrum of
4 shows a complex structure with one endothermal peak
(131 °C) and three exothermal peaks (135, 175, 231 °C).
More experiments have confirmed that under certain
conditions 1 could also react with other alcohols, for
example, ethanol, but the product was 2, not adducts.
The details of physical properties and the single-crystal
X-ray diffraction studies of 4 are being carried out.
There were many factors affecting the synthesis of 4,
and temperature was one of the most important factors.
The effect of temperature on yield of the products was
given in Table 1. Experiments indicated that high yield
of 4 was achieved in the range of 10-40 °C (98.0%
optimum at 20 °C). Temperatures below 10 °C gave a low
2.1.2. Rea ction of 1 w ith Wa ter . Recently, it has
been reported that FOX-7 was synthesized in a plant on
a multikilogram scale in Sweden4 and the route used was
Scheme 7.10
Dinitromethane was formed as a byproduct, which is
very unstable and explosive, so the safety of this process
is low and there has been a continuous interest in
adapting Scheme 1 as a possible production pathway. At
present, the cost of Scheme 1 is very high due to the low
overall yield of FOX-7 (about 13%). We have investigated
Scheme 1 recently and found two main disadvantages:11
first, 1 needs to be separated and purified, but pure 1 is
sensitive to explosive the process of its separation and
purification is dangerous. Second, trifluoroacetic acid is
used to purify 1, but it is very expensive, impure, and
(10) Astratev, A.; Dashko, D.; Mershin, A,; Stepanov, A.; Urazgild-
eev, N. Russ. J . Org. Chem. 2001, 37, 729.
(11) Cai, H. Q.; Yu, W. F.; Tian, Y.; Shu, Y. J .; Zeng, G. Y.; Cheng,
B.-B. Chin. J . Energetic Mater. 2003, 11 (1), 1.
4370 J . Org. Chem., Vol. 69, No. 13, 2004

Reactions of 2-(Dinitromethylene)-4,5-imidazolidinedione
TABLE 2. Yield of th e P r od u ct Syn th esized by th e
Rea ction of 1 w ith Ca r boxylic Acid a
SCHEME 8
carboxylic acid
yield of 2 (%)
yield of 5 (%)
formic acid
acetic acid
propanoic acid
n-butanoic acid
n-pentanoic acid
94.6
95.8
95.8
96.6
96.5
2.6
2.5
2.7
1.8
1.8
a
Carboxylic acid (200 mL), 2-(dinitromethylene)-4,5-imidazo-
SCHEME 9
lidinedione (0.01mol), reaction 30 min, T ) 25 °C.
hard to reclaim. By reaction of 1 with water these
disadvantages could be removed.
F IGURE 1. SEM photograph of 2 synthesized by ring
cleavage of 1 by formic acid.
Compound 1 was treated with dilute hydrogen chloride
or sulfuric acid to form a mixture at 25 °C. When the
mixture was added to water dropwise, the white solid
dissolved immediately to form a straw yellow solution
and in a few seconds bright yellow crystals precipitated
(81.1% yield under optimal conditions); spectral analysis
proved the product was 2 (see Scheme 8).
SCHEME 10
Water is cheaper than aqueous ammonia, so if this
technique is used for the scale-up of 2, the synthetic
pathway of 2-methylimidazole to FOX-7 (see Scheme 1)
could be achieved in a continuous process. This improve-
ment makes it possible that the large-scale production
of FOX-7 can proceed at low cost.
SCHEME 11
2.1.3. Rea ction of 1 w ith Ca r boxylic Acid . We have
expected that 1 can be attacked by carboxylic acids
and converted to 2 and corresponding oxalic anhydrides.
This expectation has been shown to be correct (see
Scheme 9).
In our experiment, liquid carboxylic acids such as
formic acid, acetic acid, propanoic acid, n-butanoic acid,
and n-pentanoic acid reacted with 1 to form correspond-
ing oxalic anhydrides. The major byproduct formed was
parabanic acid. This kind of reaction has offered a new
method to prepare oxalic anhydrides, but it was difficult
to isolate these compounds. In addition, the crystallizing
rate of 2 was slower while the particle size of the crystal
was larger.
The particle size of FOX-7 produced in Sweden was
much too small to be used directly,4 for example, in the
formulation research. Therefore, the raw product was
recrystallized in a mixture of N-methylpyrrolidone and
water. Through reaction of 1 with carboxylic acids, we
have mastered the preparation of large particle size 2
(approximately 20-1000 µm), which was obtained di-
rectly and did not need recrystallization. In these reac-
tions, the yield of 2 was very high while the yield of
byproduct parabanic acid was very low (Table 2). The
style of crystal was different from that recrystallized by
N-methylpyrrolidone and water. Scanning electron mi-
croscope (SEM) photographs are displayed in Figure 1.
2.1.4. Rea ction of 1 w ith KOH. If 1 was dissolved in
dilute aqueous KOH at ambient temperature, FOX-7 was
formed by ring cleavage. However, it was shown that
under more vigorous reaction conditions (T > 60 °C) 1
dissolved in concentrated aqueous KOH and was easily
hydrolyzed to potassium dinitromethane (6) in a 65.3%
yield (see Scheme 10). Melting point and UV analysis of
the product were consistent with those reported previ-
ously.12,13
Sandberg studied hydrolysis of FOX-7 and found that
6 could be achieved under alkali conditions.14 Thus, the
possible mechanism was that FOX-7 formed first con-
tinued to decompose (see Scheme 11).
2.2 gem -Din itr o Rea ction . gem-Dinitro compounds
differed significantly in their thermal stability, and in
some cases their structures were only postulated. Many
of them are thermally unstable and easy to decompose.
Examples of such decomposition can be found in the
literature,16-19 and carbonylation was usually achieved
finally. According to 13C NMR studies, Latypov confirmed
that 1 underwent slow decomposition in DMSO to yield
(12) Fedorov, Y. A.; Odokienko, S. S.; Selivanov, V. F. J . Appl. Chem.
USSR 1979, 52, 2201.
(13) Grakauskas, V.; Guest, A. M. J . Org. Chem. 1978, 43, 3485.
(14) Sandberg. C.; Latypov, N. V.; Goede. P.; Tryman. R.; Bellamy,
A. J . 32nd ICT International Annual Conference on Energetic Materials,
Karlsruhe, Germany, 2001; pp 33/1-8.
(15) Cai, H. Q.; Shu, Y. J .; Yu, W. F.; Li, J . S.; Cheng, B. B. Acta
Chim. Sinica 2004, 62 (3), 295.
(16) Flournoy, J . M. J . Chem. Phys. 1962, 36, 1107.
(17) Marlin, J . E.; Killpack, M. O. Heterocycles 1992, 34 (7), 1385.
(18) Bergman, J .; Bergman, S. Tetrahedron Lett. 1996, 37, 9263.
(19) Latypov, N. V.; Langlet, A.; Wellmar, U.; Goede, P. 31th ICT
International Annual Conference on Energetic Materials, Karlsruhe,
Germany, 2000; pp 11/1-10.
J . Org. Chem, Vol. 69, No. 13, 2004 4371

Cai et al.
SCHEME 12
SCHEME 13
SCHEME 14
finally 5.1 In our experiments,15 we found that 5 appeared
as a major product or byproduct in almost all reactions
of 1. When 1 was placed in the air, it could absorb water
and also undergo slow decomposition yielding finally a
mixture of 2 and 5. If methanol adduct (4) stands in a
vacuum at ambient temperature for a long time, all of it
could decompose into 5, losing methanol, nitrogen mon-
oxide, and carbon monoxide.
deflagration. Under certain conditions, 4 can deflagrate
as well.
2.4. Rea ction Mech a n ism . 2.4.1. 2-(Din itr om eth -
ylen e)-4,5-im id a zolid in ed ion e (1). We have discussed
the reaction mechanism of 1 synthesized by low-temper-
ature nitrations of 2-methylimidazole.15 The key steps
were rearrangement of nitro group and loss of nitrogen
oxide (see Scheme 12). Compound 1 was formed mainly
via two intermediates, 2-methyl-4,5-dihydro-5-imida-
zolone (7) and 2-(dinitromethylene)-5,5-dinitro-4-imida-
zolidinone (8), which have been discussed, analyzed, and
proven thoroughly.
2.3. Exp losive Decom p osition . 2-(Dinitromethyl-
ene)-4,5-imidazolidinedione (1), with gem-dinitro, was a
powerful and sensitive explosive, so it had some proper-
ties of explosive. In our experiments, we found that under
certain conditions, for example, at high temperature, 1
can decompose rapidly to yield white gas products, and
this exothermic explosive reaction has the capacity to
cause a runaway reaction and in the worst case a
2.4.2. F OX-7 (2). We have also discussed the reaction
mechanism of FOX-7 synthesized by ring cleavage of 1
by ammonium hydroxide.15 The mechanism of ring cleav-
age by other reagents was similar to it. FOX-7 was
4372 J . Org. Chem., Vol. 69, No. 13, 2004

Reactions of 2-(Dinitromethylene)-4,5-imidazolidinedione
Rin g Clea va ge of 1 to 2 by Meth a n ol a t Room Tem -
p er a tu r e. 2-(Dinitromethylene)-4,5-imidazolidinedione (2.1 g,
0.01mol) was dissolved in methanol at 25 °C with vigorous
stirring. Fine iron powder and dilute hydrogen chloride
(catalytic amount) were added to the solution. After 30 min,
concentration of the solution gave the product as bright yellow
crystals. The crystals were washed with water and dried at
50 °C to give 1.3 g (87.8%) of 2. The product was spectroscopi-
cally (IR, NMR, and mass data) identical with previously
prepared FOX-7.
formed mainly by the following steps (see Scheme 13):
nucleophiles attacked the positive carbon of the carbo-
nylation twice, with subsequent elimination of double
carbonylations, and then FOX-7 was formed.
2.4.3. P a r a ba n ic Acid (5). The mechanism of para-
banic acid formed was complex. We think that many
steps are involved (see Scheme 14). The key steps were
rearrangement of nitro group and elimination of carbon
monoxide.
Rin g Clea va ge of 1 to 2 by Meth a n ol a t High Tem p er -
a tu r e. 2-(Dinitromethylene)-4,5-imidazolidinedione (2.1 g,
0.01mol) was dissolved in methanol at 60 °Cwith vigorous
stirring. After 30 min, the solution was concentrated slowly,
and then bright yellow crystals precipitated. The precipitate
was washed with water and dried at 50 °C to give 1.1 g (74.3%)
of 2. The product was spectroscopically (IR, NMR, and mass
data) identical with previous prepared FOX-7.
Rin g Clea va ge of 2-Meth ylim id a zole to 2 by Meth a n ol.
Finely ground 2-methylimidazole (16.5 g, 0.2 mol) was dis-
solved in sulfuric acid (95%, 160 mL) at 19 °C with vigorous
stirring. At the same temperature, nitric acid (32 mL, 1.51
g/L) was added over a 1.5 h period. After 1.5 h, a white
precipitate was formed. Methanol (200 mL) was added, and a
yellow solution was formed. Concentration of the solution gave
the product as bright yellow crystals. The crystals were washed
with water and dried at 50 °C to give 12.2 g (41.2%) of 2. The
product was spectroscopically (IR, NMR, and mass data)
identical with previously prepared FOX-7.
3. Con clu sion s
We have discovered some new reactions of 1 with
water, alcohols, alkalis, and carboxylic acids. By reaction
with carboxylic acids, large particle size FOX-7 (2) was
prepared and might have applications in propellants and
high explosive formulations. By reaction with KOH,
potassium dinitromethane (6) was synthesized, which
was a new route for it. By reaction with methanol, the
methanol adduct of 1, which was more stable than 1, has
been synthesized and characterized. The synthesis of
adducts is important to theoretical research and future
applications.
4. Exp er im en ta l Section
Gen er a l Meth od s. Melting points or decomposition tem-
peratures were determined with DSC. Thermal sensitivity was
measured with TG. IR spectra were measured by a spectrom-
eter. 1H and 13C NMR spectra were recorded at 300 MHz
(DMSO as solvent). Mass spectra were recorded by EI methods
at 70 eV (the temperature of ion source was 200 °C, and the
solid sample inlet was used). Elemental compositions were
measured with an elemental analyzer. The features of FOX-7
were observed by SEM. The organic solvents used were dried
by standard methods when necessary. Commercially obtained
reagents were used without further purification.
R in g Clea va ge of 1 t o 2 by F or m ic Acid . 2-(Dinitro-
methylene)-4,5-imidazolidinedione (2.1 g, 0.01mol) was dis-
solved in formic acid at 25 °C with vigorous stirring. After 30
min, the solution was concentrated slowly, and then bright
yellow crystals precipitated. The crystals were washed with
water and dried at 50 °C to give 1.4 g (94.6%) of 2. IR,
NMR, and mass data were identical with previously prepared
FOX-7.
Under the same conditions, the yields of FOX-7 prepared
by reactions of 1 with acetic acid, propanoic acid, n-butanoic
acid, or n-pentanoic acid were 95.8%, 95.8%, 96.6%, or 96.5%,
respectively.
Rin g Clea va ge of 1 to 2 by KOH. 2-(Dinitromethylene)-
4,5-imidazolidinedione (2.1 g, 0.01 mol) was dissolved in 10
mL of water, and a solution of KOH (5%, 10 mL) was added
dropwise to it at 25 °C. After 3 h, a yellow precipitate of FOX-7
was formed. The solution was concentrated slowly, and then
bright yellow crystals precipitated. The crystals were collected,
washed with water, and dried at 50 °C to give 1.3 g (87.8%) of
2. IR, NMR, and mass data were identical with previous
prepared FOX-7.
Meth a n ol Ad d u ct of 2-(Din itr om eth ylen e)-4,5-im id a -
zolid in ed ion e (4). 2-(Dinitromethylene)-4,5-imidazolidinedi-
one (2.1 g, 0.01mol) was dissolved in 200 mL of methanol at
ambient temperature with vigorous stirring. Fine iron powder
and dilute hydrogen chloride (catalytic amount) were added
to the solution. After 30 min, the solution was concentrated
slowly, and then yellow needle crystals precipitated. The
crystals were washed with water and dried at 50 °C to give
2.3 g (98.3%) of 4: mp 140.0-140.9 °C; IR (KBr) 3362 (NH2),
3249 (NH2), 1753 (CdO), 1734 (CdO), 1618 (NH2), 1575 (NO2),
1475, 1323 (NO2), 1230, 1140, 964 cm-1; 1H NMR (DMSO-d6)
δ 3.69, 8.81, 11.76 ppm; 13C NMR (DMSO-d6) δ 48.7, 53.5,
100.4, 128.7, 154.9, 159.8; MS m/z 234 (M+, 36.14), 188 (100),
175 (40.15), 138 (71.05), 112 (53.12), 69 (75.01), 59 (69.89).;
Anal. Calcd for C5H6N4O7: C, 25.64; H, 2.56; N, 23.93. Found:
C, 25.70; H, 2.64; N, 24.07.
Caution: All polynitro compounds described in this paper
are explosives, and proper shielding is strongly recommended.
For m ation of 2-(Din itr om eth ylen e)-4,5-im idazolidin edi-
on e (1). Finely ground 2-methylimidazole 16.5 g (0.2mol) was
dissolved in sulfuric acid (160 mL, 95%) at 19 °C with vigorous
stirring. At the same temperature, nitric acid (32 mL, 1.51
g/L) was added over a 1.5 h period. After 1.5 h, a white
precipitate was formed, which was collected and washed
several times with cold trifluoroacetic acid. The precipitate was
dried in a vacuum at 0 °C. On standing at room temperature
for 5 h, 2-(dinitromethylene)-5,5-dinitro-4-imidazolidinone lost
26.5% of weight and gave 8.4 g (20.8%) of 2-(dinitromethylene)-
4,5-imidazolidinedione: mp 240 °C dec (10 °C/min DSC); IR
(KBr) 3313 (NH2), 3226 (NH2), 3169 (NH2), 1805 (CdO), 1754
(CdO), 1584 (NO2), 1499, 1318 (NO2), 1232, 1176, 758 cm-1
;
1H NMR (DMSO-d6) δ 11.03 ppm; 13C NMR (DMSO-d6) δ
128.7, 154.7, 159.7; MS m/z 202 (M+, 11.13), 138 (100), 69
(43.01), 30 (19.34). Anal. Calcd for C4H2N4O6: C, 23.77; H, 1.0;
N, 27.72. Found: C, 23. 90; H, 1.23; N, 27.87.
Rin g Clea va ge of 1 to F OX-7 (2) by Wa ter . 2-(Dinitro-
methylene)-4,5-imidazolidinedione (2.1 g, 0.01mol) was treated
with dilute hydrogen chloride to form a mixture at 25 °C, and
then the mixture was added to water dropwise. The white solid
dissolved immediately, and in a few seconds bright yellow
crystals precipitated. The crystals were washed with water and
dried at 50 °C to give 1.2 g (81.1%) of FOX-7: mp 238 °C dec
(7 °C/min DSC); IR (KBr) 3404 (NH2), 3330 (NH2), 3223 (NH2),
1633 (NH2), 1518 (NO2), 1469, 1393, 1351 (NO2), 1221, 1166,
Rin g Clea va ge of 1 to P ota ssiu m Din itr om eth a n e (6)
by KOH. 2-(Dinitromethylene)-4,5-imidazolidinedione (2.1 g,
0.01mol) was dissolved in a solution of KOH (10%,40 mL) at
15 °C. The resulting solution was warmed to 70-95 °C and
was kept at this temperature. After 3 h, when the evolution
of ammonia ceased, the solution was cooled to 15 °C and the
1
1137, 1023, 620, 458 cm-1; H NMR (DMSO-d6) δ 8.76 ppm;
13C NMR (DMSO-d6) δ 129.4, 159.0; MS m/z 148 (M+, 84.01),
86 (21.34), 69 (38.36), 43 (100), 18 (72.01). Anal. Calcd for
C2H4N4O4: C, 16.22; H, 2.72; N, 37.84. Found: C, 16.09; H,
2.68; N, 37.87.
J . Org. Chem, Vol. 69, No. 13, 2004 4373

Cai et al.
pale yellow product formed was collected by filtration, washed
with water, and dried at 50 °C to give 0.94 g (65.3%) of 6: mp
220 °C dec; UV λmax ) 363 nm; ꢀ ) 20 800.
filtrate was condensed, and cooling to 10 °C and keeping
overnight resulted in the precipitation of 0.17 g (14.9%) of 5.
Ack n ow led gm en t. We thank the China Academy
of Engineering Physics for giving financial support to
Project 20020540. We also thank Mrs. Xu Ruijuan and
Yang Xiulan for mass spectra, Mrs. Wang Lin and J iang
Yan for infrared spectra measurements, and Mr. Li Wei
for SEM photographs.
P a r a ba n ic Acid (5). 2-(Dinitromethylene)-4,5-imidazo-
lidinedione (2.1 g, 0.01mol) was dissolved in 200 mL of
methanol at 0 °C with vigorous stirring. Fine iron powder and
dilute hydrogen chloride (catalytic amount) were added to the
solution. After 30 min, the solution was concentrated slowly,
and then the white solids precipitated. The precipitate proved
to be a mixture of parabanic acid and 4, which were dissolved
in water, and the insoluable 4 was filtrated (0.3 g, 12.8%). The
J O030395F
4374 J . Org. Chem., Vol. 69, No. 13, 2004