50 Synthetic Routes to AliphaticC-Nitro
NO 2NO 2II N
HH
N NO 2NO 2 NNNO 2
188C(NO 2 ) 3NNNO 2
189C(NO 2 ) 2 K
NH
N NO 2NO 2
NO 2
190CH 2 Cl 2 , 0 °C
74 %H 2 NCH 2 CH 2 NH 2(^183187)
TFAA, HNO 3 ,
CH 2 Cl 2
89 %
18-crown-6,
KI, THF, 89 %
94 %
HCl (aq)
Figure 1.91
of nitronitronate salts (189), which on acidification, yield theN-nitro derivatives of the initial
1,1-diamino-2,2-dinitroethylenes (190).
NHHN
O 2 N NO 2
O O
O 2 N NO 2
H 2 N NH 2
NHN
CH 3
NH 4 OH
193
192 (FOX-7)
191
H 2 SO 4 , HNO 3
Figure 1.92
1,1-Diamino-2,2-dinitroethylenes have recently attracted interest as energetic explosives.
1,1-Diamino-2,2-dinitroethylene (193) (DADE or FOX-7) is a high energy material with a
lower impact sensitivity than HMX and well suited for use in high explosive formulations.^333
FOX-7 (193) was first synthesized by Latypov and co-workers^334 who nitrated 2-methyl-4-
nitroimidazole with mixed acid to give a mixture of parabanic acid and 2-(dinitromethylene)-
4,5-imidazolidinedione (192), followed by reaction of the latter with aqueous ammonia to yield
FOX-7 (193). 2-(Dinitromethylene)-4,5-imidazolidinedione (192) has also been prepared from
the low temperature nitration of 2-methylimidazole (191).^335 The condensation of acetami-
dine hydrochloride with diethyl oxalate in methanol yields a mixture of 2-methylene-4,5-
imidazolidinedione and 2-methoxy-2-methyl-4,5-imidazolidinedione; nitration of the latter
and subsequent treatment with aqueous ammonia at pH 8–9 also provides FOX-7 in 50 %
overall yield.^334 FOX-7 has been synthesized on a pilot plant scale in Sweden^336 by the
nitration of 2-methyl-4,6-dihydroxypyrimidine.^337 The conversion of 2-(dinitromethylene)-
4,5-imidazolidinedione to FOX-7 has been studied by Cai and co-workers^338 who achieved
hydrolysis with water instead of ammonia and also found that hydrolysis with a carboxylic acid
produces a larger crystal size which is more suitable for direct use in explosive formulations.
1.12.2 Other routes to aliphatic nitro compounds
A number of routes to aliphatic nitro compounds are not used for energetic materials synthesis
but are included here for completeness.