Organic Chemistry of Explosives

302 N-Heterocycles

dioxide in acetonitrile. The bis-nitramine (53) is too reactive for practical use, although the

bis-picryl derivative (54), formed from the dianion of (52) and picryl chloride, is more stable.

7.3.5 Benzofurazans

NH 2

NO 2

55

NO 2

NH 2

O 2 N

N

O

N

NH 2

O 2 N

NO 2

56

N

O

N

NO 2

H 2 N

NO 2

57

tetradecane

reflux

Figure 7.22

Some nitro derivatives of benzofurazan have been investigated for their explosive proper-

ties. 4-Amino-5,7-dinitrobenzofurazan (56) has been prepared^33 by a number of routes in-

cluding: (1) the thermally induced cyclodehydration of 1,3-diamino-2,4,6-trinitrobenzene

(55), (2) the nitration of 4-amino-7-nitrobenzofurazan and (3) the reduction of 4-amino-5,7-

dinitrobenzofuroxan with triphenylphoshine. The isomeric 5-amino-4,7-dinitrobenzofurazan

(57) has been prepared along similar routes.^33

7.3.6 Furoxans

The furoxan ring is a highly energetic heterocycle whose introduction into organic compounds

is a known strategy for increasing crystal density and improving explosive performance.

NN

O

O 2 N

O

58

(DNFX)

NO 2

Figure 7.23

NN

O

RCH 2 CH 2 R

RCH 2 CHN 2

O

ClCH 2 CH 2 Cl

R = (NO 2 ) 3 CCH 2 N

NO 2

N 2 O 4

(^5960)
O
Figure 7.24
Simple nitro derivatives of furoxan have not attracted much interest for use as practical en-
ergetic materials, a consequence of their poor thermal stability and the reactivity of the nitro
groups to nucleophilic displacement. 3,4-Dinitrofuroxan (DNFX) (58) has been prepared from
the nitration of glyoxime followed by cyclization of the resulting dinitroglyoxime.^34 DNFX
is unstable at room temperature and highly sensitive to impact. 3-Nitro-4-methylfuroxan is
formed in low yield from the reaction of dinitrogen tetroxide with propylene at subambi-
ent temperature.^35 The reaction of diazoketones with dinitrogen tetroxide has been used to
synthesize energetic 3,4-disubstituted furoxans like (60).^36