Organic Chemistry of Explosives

200 Synthetic Routes toN-Nitro

One simple example of chloride-catalyzed nitration is the synthesis of the energetic plasti-

cizer Bu-NENA (34) from the nitration ofn-butyl ethanolamine (33) with a mixture of acetic

anhydride–nitric acid to which catalytic zinc chloride has been added.^25

Many cyclic, bicyclic and caged polyamines are synthesized via condensation reactions and

these are usually isolated as their salts. The free bases are usually difficult to isolate and readily

decompose in aqueous or acid solution. Since hydrochloric acid is frequently employed in these

condensations the hydrochloride salt of the amine is usually used directly for theN-nitration.

N

OHH

HH

Cl N

H ONO 2

NO 2

HN

N

NH

NO 2

HN

HH

N

NH

N

NO 2

N

NO 2

Cl

35

36

(^3738)
Figure 5.15
The strainedN-nitroazetidine (36) has been synthesized from the nitration of the hydrochlo-
ride salt of the corresponding azetidine (35) with acetic anhydride–nitric acid.^26 The hetero-
cyclic guanidine (38) is synthesized from (37) in a similar way.^27
OO
HN NH
OO
OO
OO
NN

. 2HCl O 2 N NO 2
39

1. H 2 SO 4


2. HNO 3

40

(TEX)

Figure 5.16

Acetic anhydride–nitric acid mixtures are extensively used for chloride-catalyzed nitrations.

Other nitrating agents have been used and involve similar sources of electropositive chlorine for

intermediate chloramine formation. 4,10-Dinitro-4,10-diaza-2,6,8,12-tetraoxaisowurtzitane

(TEX) (40), an insensitive high performance explosive (VOD∼8665 m/s,d= 1 .99 g/cm^3 ),

is synthesized by treating the dihydrochloride salt of the corresponding amine (39) with strong

mixed acid.^28

As previously discussed, heterocyclic polyamines containing methylenediamine function-

ality are usually unstable if unprotected. In contrast, the presence of a urea group stabilizes this

functionality and allows the isolation of a number of heterocyclic amines. These are usually

synthesized via a condensation reaction and isolated as the hydrochloride salt. TheN-nitration

of the 2,5,7,9-tetraazabicyclo[4.3.0]nonan-8-one^29 and 2,4,6,8-tetraazabicyclo[3.3.0]octan-3-

one^30 ring systems has been investigated and serve as valuable examples.

N

N

N

H

N

O

NO 2

NO (^2) NO
2
43
(HK-56)
N
N
N
H
H
N
O
NO 2
NO 2
42
N
H
H
N
N
H
H
N
O
N
N
N
N
O
NO 2
NO 2
NO 2
NO 2
44
(K-56)
41

. 2HCl

Figure 5.17