Organic Chemistry of Explosives

324 N-Heterocycles

NH 2

ClCl

NN

O

tN NtBuBu

ClCl

N

O

N

N

N

N

O

O

ButN

H 2 N

+

Cl

N

N

N

N

O

O

N

N

N

N

O

O

215

219

(TBTDO)

218, 37 %

216

Cl

N

O

N

N

N

N

O

O

ButN

NH 2

217, 43 %

Cl

N

O

N

N

N

N

O

O

ButN

N 2 O 5 , MeCN

41 %

NH 3 , DMSO

N 2 O 5 , MeCN

55 %

O

Figure 7.78

of the 1,2,3,4-tetrazine-1,3-dioxide ring system starts from (215) and utilizes the reaction of

thetert-butyl-NNO-azoxy group with an adjacent amino group in the presence of dinitrogen

pentoxide. Thetert-butyl-NNO-azoxy groups of (215) are introduced by treating the corre-

sponding nitroso derivative withN,N-dibromo-tert-butylamine. Tartakovsky and Churakov^134

recently reviewed the chemistry of 1,2,3,4-tetrazines.

7.10 Dibenzotetraazapentalenes

N

N

N

N

N

N

NN

220 91

Figure 7.79

The dibenzotetraazapentalene ring system was first discovered by chemists at DuPont^135 –^138

and is a planar system with six electrons delocalized over four nitrogen atoms. There are two

isomeric arrangements of these four nitrogens which lead to the 1,3a,4,6a- (220) and 1,3a,6,6a-

(91) ring systems. Nitro derivatives of both isomeric dibenzotetraazapentalenes have been

explored as thermally stable explosives.

Isomeric 1,3a,4,6a- (220) and 1,3a,6,6a- (91) dibenzotetraazapentalenes can be prepared

from the thermal decomposition of 2-(o-azidophenyl)-2H-benzotriazole (224) and 1-(o-

azidophenyl)-2H-benzotriazole (230), respectively, in high boiling solvents such as o-

dichlorobenzene and decalin.^135 –^138 This synthesis was improved upon when it was found

that (220) and (91) can be prepared from the reactions of 2-(o-nitrophenyl)-2H-benzotriazole

(226) and 1-(o-nitrophenyl)-2H-benzotriazole (229), respectively, with triethyl phosphite in

refluxing xylene.^138