Organic Chemistry of Explosives

228 Synthetic Routes toN-Nitro

derivatives of azetidine are found to yield the expected 1,3-nitramine-nitrates, theN-acyl

derivatives undergo nitrolysis to yieldN-nitroazetidine. Azetidine also undergoesN-nitration

to giveN-nitroazetidine on reaction with dinitrogen pentoxide.

N NO 2

NO 2 155

O 2 N N

N

N N

N

NN NO 2

O 2 NO(CH 2 ) 3

NO 2

(CH 2 ) 3 ONO 2

O 2 N

156 157

Figure 5.64

N-Picrylazetidine (155) is found to be inert to attack by dinitrogen pentoxide, a consequence

of the electron-withdrawing picryl group. The triazine (156) gave a 60 % crude yield of the

energetic 1,3-nitramine-nitrate (157) which is an analogue of Tris-X.

5.9 Nitrosamine oxidation

In view of the highly carcinogenic nature of many nitrosamines any experiments involving

their isolation must be discouraged, and for this reason, this section has only been written for

completeness. This high toxicity is unfortunate because the preparation of nitrosamines from

the parent amines is often facile and they provide a route to highly pure nitramines. Other

equally useful methods for the synthesis of nitramines, such as the chloride-catalyzed nitration

of secondary amines, also suffer from the formation of nitrosamines in appreciable amounts

and must also be viewed with caution.

R^1 R^2 NH R^1 R^2 NNO R^1 R^2 NNO 2 (Eq. 5.16)

HNO 2 CF 3 CO 3 H

CH 2 Cl 2

Figure 5.65

Secondary nitrosamines are readily synthesized in excellent yield by treating secondary

amines with aqueous nitrous acid (Equation 5.16).^106 Emmons found that these secondary ni-

trosamines can be oxidized to the corresponding nitramines in good to excellent yield on treat-

ment with peroxytrifluoroacetic acid (Equation 5.16); the latter is prepared from the addition

of 90 % hydrogen peroxide to an excess of trifluoroacetic acid or trifluoroacetic anhydride.^106

The method is found to yield the corresponding nitramine in a state of high purity with high-

est yield attainable under anhydrous conditions using methylene chloride as solvent.^106 ,^129 ,^130

Other oxidants have been reported although their use is more limited.^4 ,^105