Organic Chemistry of Explosives

276 Nitramines and Their Derivatives

6.8 Heterocyclic nitramines derived from Mannich reactions

Hybrid compounds containing heterocyclic nitramine andgem-dinitro functionality represent

a class of high performance energetic materials. Such compounds frequently exhibit higher

heats of formation, crystal density, detonation velocity and pressure, and better oxygen balance

compared to analogous aromatic compounds.

The Mannich reaction has been used to synthesize numerous heterocyclic nitramine ex-

plosives. Adolph and Cichra^32 prepared a number ofN-heterocycles containingtert-butyl

N-blocking groups. The nitrolysis of theset-butyl groups provides the correspondingN-nitro

derivatives in excellent yields (Section 5.6.2.2). Some of the nitramine products from these

reactions are powerful, energetic explosives with attractive properties.

N

t-Bu

90

NO 2

NO 2

O 2 N

O 2 N

N

NO 2

91

NO 2

NO 2

O 2 N

HOCH O^2 N

2 C

NO 2

NO 2

89

CH 2 O, t-BuNH 2

Acidify to pH 6

with AcOH, 15 %

100 % HNO 3

96 %

CH 2 OH

Figure 6.23

1,3,3,5,5-Pentanitropiperidine (91) is prepared from the condensation of 2,2-dinitro-1,3-

propanediol (89) with formaldehyde andt-butylamine under slightly acidic conditions, fol-

lowed by nitrolysis of thet-butyl group of the resulting piperidine (90) with mixed acid or

absolute nitric acid.^32

N

O 2 N NO 2

RR

92, R = i-Pr

93, R = t-Bu

R = t-Bu - HNO 3 ,

H 2 SO 4 , 87 %

R = i-Pr - 90 % HNO 3

94

(DNNC)

N N

NO 2

NO 2

O 2 N

O 2 N

N

Figure 6.24

1,3,5,5-Tetranitrohexahydropyrimidine (DNNC) (94) has been synthesized from the

nitrolysis of theN,N′-di-tert-butylpyrimidine (93).^32 ,^33 Levins and co-workers^34 reported the

synthesis of DNNC (94) from the nitrolysis of the analogousN,N′-di-iso-propylpyrimidine

(92). DNNC is a high performance explosive with a detonation velocity of 8730 m/s, impact

sensitivity lower than RDX and a very favourable oxygen balance. DNNC has been suggested^34

for use as an oxidizer in propellant compositions. This is also considered as an excellent oxidant

for pyrotechnic compositions.^33

N

N

O 2 N

NO 2

96

O

O 2 N

NO 2

NO 2

NO 2

NO 2

NO 2 HN

N

H H

NH

N

95 Cl

97

N

Figure 6.25