210 Synthetic Routes toN-Nitro
OO NCH 2 CH 2 ONO 2NCH 2 CH 2 ONO 2NO 2NO 2 11
(NENO)OO NCH 2 CH 2 OHNCH 2 CH 2 OHNO 2NO 2OO NHCH 2 CH 2 ONO 2O NHCH 2 CH 2 ONO 2O NHCH 2 CH 2 OHNHCH 2 CH 2 OHCO 2 EtCO 2 Et2 HOCH 2 CH 2 NH 2+HNO 398 %626163H 2 O, refluxH 2 SO 4 ,
HNO 3 , 85 %H 2 SO 4 , HNO 3H 2 SO 4 ,
HNO 3Figure 5.34A mixture of concentrated sulfuric and nitric acids has been used for theN-nitration of
amides and ureas.N, N′-Dinitro-N, N′-bis(2-hydroxyethyl)oxamide dinitrate (NENO) (11) is
prepared from the action of mixed acid onN, N′-bis(2-hydroxyethyl)oxamide (61), itself pre-
pared from the condensation of diethyloxalate with two equivalents of ethanolamine.^73 Nitro-
sylsulfuric acid is an inhibitor ofN-nitration and so nitrous acid should be rigorously excluded.
The reaction of (61) with absolute nitric acid results inO-nitration of the hydroxy groups but
noN-nitration, and consequently, (62) is isolated as the sole product.
SOONCH 2 CH 2 ONO 2NCH 2 CH 2 ONO 2NO 2NO 2
65SOONHCH 2 CH 2 OHNHCH 2 CH 2 OH
64HNO 3 , H 2 SO 4Figure 5.35A number of other secondary nitramide explosives have been prepared from the action
of mixed acid on the parent amide. Treatment of sulfuryl chloride with two equivalents of
ethanolamine, followed by nitration of the resulting sulfamide (64) with mixed acid, yields the
nitramide explosiveN, N′-dinitro-N, N′-bis(2-hydroxyethyl)sulfamide dinitrate (65).^74
Although a large number of secondary nitramides have been prepared they have not found
wide use as explosives because of their facile hydrolysis to acidic primary nitramines in the
presence of water. Research has focused on the synthesis of cyclic and bicyclicN-nitroureas
andN, N′-dinitroureas because of their high performance.
NHHN NNHNO 3 , H 2 SO 4 O 2 N NO 266 67OOFigure 5.36N, N′-Dinitro-2-imidazolidone (67), a precursor to ethylenedinitramine (EDNA), is synthe-
sized from the nitration of 2-imidazolidinone (66) with mixed acid.^70