2,6,8,12-Tetraacetyl-4,10-dibenzyl-2,4,6,8,10,12-hexaaza-
isowurtzitane (3, 57 g, 0.11mol) was added over a 10 min
period to dinitrogen tetroxide (240 mL, 3.78 mol) and water
(9.6 mL) at 0 °C. After maintaining the magnetically stirred
solution at 0 °C for 1 h, the flask was securely stoppered
and allowed to warm to 20-25 °C without stirring. The
solution was re-cooled to <5 °C after 20 h, and 90% nitric
acid (960 mL, 20.6 mol) was slowly added (1.5-2 h) with
stirring, keeping the temperature below 5 °C. Sulphuric acid
(98%, 240 mL) was then added over 10 min without external
cooling; the temperature rose to about 35 °C. The resultant
solution was slowly heated in an oil bath until the liquid
temperature reached 80 °C. During this period, the excess
of dinitrogen tetroxide and some nitric acid distilled off and
was collected for reuse. The total volume of distillate was
241 mL (at 0 °C) forming two layers6san upper layer (130
mL) consisting of 94.5 wt % dinitrogen tetroxide and 5.5
wt % nitric acid (this liquid can be reused for the nitrosation
without further purification), and a lower layer (111 mL)
consisting of 56.5 wt % dinitrogen tetroxide and 43.5 wt %
nitric acid. Once the internal temperature reached 80 °C, the
solution was held at this temperature for 2-2.5 h before
pouring the hot solution, with stirring, into ice/water (4 kg).
The white solid that separated was filtered off from the green
solution, washed thoroughly with water, and then dried in
vacuo over silica gel to give a pale yellow powder (1, 47.0
g, 97%). HPLC analysis showed that the purity of the
2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane
(1) obtained was 95.1%.
2,6,8,12-Tetraacetyl-4,10-dinitroso-2,4,6,8,10,12-hexaaza-
isowurtzitane (5). To a mixture of acetic acid (400-450
mL), dinitrogen tetroxide (240 mL, 3.78mol), and water (20
mL) in a round-bottomed flask equipped with a reflux
condenser was added 2,6,8,12-tetraacetyl-4,10-dibenzyl-
2,4,6,8,10,12-hexaazaisowurtzitane (3, 400 g, 0.78mol) with
vigorous stirring over a 20 min period at 20-25 °C. The
reaction was monitored by thin-layer chromatography (ethyl
acetate/triethylamine 1/1). After 24 and 48 h additional
dinitrogen tetroxide (20 mL, 31.5 mmol) was added. After
72 h, thin-layer chromatography showed no remaining (6)
(Rf ) 0.38). Instead, two spots were observed, the major
one corresponding to 2,6,8,12-tetraacetyl-4,10-dinitroso-
2,4,6,8,10,12-hexaazaisowurtzitane (5) (=90%, Rf ) 0.5),
and the minor one most probably corresponding to 6,8,12-
triacetyl-2,4,10-trinitroso-2,4,6,8,10,12-hexaazaisowurtzi-
tane (7) (=10%, Rf ) 0.61). The reaction mixture was
transferred to a crystallising dish where it was stirred for 3
h to remove the remaining oxides of nitrogen. Ethanol (3 L)
was added with vigorous stirring and the product was allowed
to precipitate for 3 h. The precipitate was filtered off and
then washed with ethanol (3 × 300 mL) to remove all traces
of benzaldehyde. After drying (50 °C for 12 h) the product
was obtained as a yellowish powder (250 g, 0.635 mol, 82%
based on 3), mp 280 °C (lit.1 mp 290-295 °C). This product
was used without further purification in the subsequent
nitration step. In a smaller scale reaction dinitrogen tetroxide
(3.8 mL, 0.06 mol) was added to 3 (5.16 g, 0.01mol) in 50
mL of acetic acid; the reaction mixture was stirred for 24 h
when additional dinitrogen tetroxide (4.0 mL, 0.063mol) was
added. After the reaction mixture was stirred for a total of
72 h, the excess of acetic acid was removed under reduced
pressure, and the reaction mixture was worked up as above.
After recrystallization from ethyl acetate/acetic acid 5 with
a decomposition temperature (290-295 °C), FTIR and NMR
spectra identical to those reported1 was obtained.
2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzi-
tane (1). To a solution of 2,6,8,12-tetraacetyl-4,10-dinitroso-
2,4,6,8,10,12-hexaazaisowurtzitane (5, 500 g, 1.27 mol) in
99% nitric acid (6 L) was added 96% sulphuric acid (750
mL) over a 5 min period. The reaction mixture was heated
to 75-80 °C, maintained at this temperature for 2 h, and
then poured into ice/water (30 kg) with vigorous stirring,
the temperature being kept below 35 °C during the addition.
The precipitated product was filtered off and washed with
water (4-5 times) until neutral washings were obtained. The
product was isolated in the hydrated alpha form after drying
to constant weight at 40 °C. HPLC analysis showed that the
purity of the 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-
isowurtzitane (1) obtained was 99.0%, (520 g, 93%). The
decomposition temperature (240 °C) and FTIR and NMR
spectra were identical to those reported,3,7,8 respectively.
A reaction mixture quenched after 20 min gave a mixture
of 1, 8, and 9. This mixture was resolved into the three
components by chromatography using the Chromatotron
system with heptane/ethyl acetate 3/1 f 3/2 as eluent.
2,8-Diacetyl-4,6,10,12-tetranitro-2,4,6,8,10,12-hexaaza-
isowurtzitane (8). The decomposition temperature (233-
234 °C) and FTIR and NMR spectra were identical to those
reported.9
2-Acetyl-4,6,8,10,12-pentanitro-2,4,6,8,10,12-hexaaza-
isowurtzitane (9). The decomposition temperature (203.5
°C) and FTIR and NMR spectra were identical to those
reported.10
Acknowledgment
We thank FMV for financing this project and NEXPLO
Bofors AB for supplying 2,6,8,12-tetraacetyl-4,10-dibenzyl-
2,4,6,8,10,12-hexaazaisowurtzitane (3).
(6) Addison, C. C. Chem. ReV. 1980, 80, 21.
(7) Foltz, M. F. Propellants, Explos. Pyrotech. 1994, 19, 63.
(8) Kaiser, M.; Ditz, B. In Annual ICT Conference on Energetic Materials;
Karlsruhe: Germany, 1998; pp 130-1.
Received for review November 12, 1999.
OP990097D
(9) Zhao, X.; Li, L.; Bai, J.; Feng, Z. J. Beijing Inst. Technol. 1998, 18, 660.
(10) Zhao, X.; Liu, J. Chin. Sci. Bull. 1998, 42, 1055.
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Vol. 4, No. 3, 2000 / Organic Process Research & Development