Organic Chemistry of Explosives

240 Synthetic Routes toN-Nitro

An interesting reaction has been reported for the synthesis of polymethylenenitramines and

also illustrates the instability of these compounds. Such compounds can undergo nitromethy-

lene transfer reactions when heated in polar solvents like DMSO.^167 Methylenedinitramine

(168) reacts under these conditions to generate both nitramine (161) and 1,3,5-trinitro-1,3,5-

triazapentane (218); reaction of the latter under similar conditions allows the synthesis of

1,3,5,7-tetranitro-1,3,5,7-tetraazaheptane (220) and so on. The primary nitramino groups of

these polymethylenenitramines can undergo condensation reactions and may be useful for the

synthesis of energetic polymers.

5.13.4 Nucleophilic displacement reactions

DMSO

Cl NNN

NO 2 NO 2 NO 2

O 2 NN N NNO 2

NO 2

222

AcO NN OAc

NO 2 NO 2

N NNN

NO 2

NO 2 NO 2 NO 2

N

NO 2

223

NNO 2

225

NNO (^2) DMSO
2 Na
2 Na
n

• n
  224
  221
  226
  2-


• 
  

  2-
  Cl
  Figure 5.92
  The readiness with which primary nitramines form terminal methylol derivatives on reaction
  with formaldehyde has been utilized for the synthesis of some energetic polymers by converting
  the terminal hydroxy functionality into a better leaving group such as an acetate ester or a
  halogen. The alkali metal salts of some linear polynitramines have been used as nucleophiles
  to displace such leaving groups and form energetic polymers like (223)^168 and (226).^169
  The alkylation of primary nitramines with alkyl halides is of little preparative value for
  the synthesis of secondary nitramines. Such reactions often result in a mixture ofN- and
  O-alkylated products. The product distribution appears to be very dependent on the nature of
  the cation of the nitramine used, with silver salts^170 favouringO-alkylation and alkali metal
  salts^171 usually givingN-alkylation as the predominant product. However, this is not always
  the case.

  
  

5.14 Aromatic nitramines

Numerous aromatic nitramines have been synthesized but only N,2,4,6-tetranitro-N-

methylaniline (tetryl) and 1-(2-nitroxyethylnitramino)-2,4,6-trinitrobenzene (pentryl) have

found practical use as explosives. Both tetryl and pentryl are more powerful than TNT. Tetryl is

widely used in boosters and as a component of explosive formulations like tetrytol (tetryl/TNT),

PTX-1 (tetryl/RDX/TNT) and Composition C-3 (tetryl/RDX/TNT/DNT/MNT/NC).

Tetryl (8) can be prepared from the nitration–oxidation ofN, N-dimethylaniline (90) with

a variety of nitrating agents and conditions, including the use of a large excess of 70 % nitric