Organic Chemistry of Explosives

Cubanes 71

in alkaline solution.^5 No reference is made to the attempted oxidative nitration of (24) to

2,2,5,5,8,8,10,10-octanitrodispiro[3.1.3.1]decane.

HON NOH

NOH

NOH

Cl

Cl

Cl

O 2 N

O 2 N

NO 2

Cl

NO 2

NO 2

NO 2

NO 2

H H

H

H NO 2

1. Cl 2 , CH 2 Cl 2


2. NaOCl,
   Bu 4 NHSO 4
   89–90 %

Zn, NH 2 OH.HCl

THF (aq), 20 %

23

22 24

Figure 2.8

2.4 Cubanes

Of the various caged structures investigated for the synthesis of energetic compounds some have

more internal strain than others. The cubane skeleton is highly energetic (Hf∼620 KJ/mol)

and shows a high degree of molecular strain. Consequently, the nitro derivatives of cubane ex-

hibit much higher performance than those of say, adamantane, which show little to no molecular

strain. While this lack of molecular strain is reflected in higher thermal stability, the nitro deriva-

tives of cubane are generally thermally stable. Additionally, the higher decomposition temper-

atures of some nitro derivatives of cubane, as compared to cubane itself, could infer that the

electron-withdrawing nitro groups stabilize the cubane system and enhance thermal stability.^6

Interest in polynitrocubanes surfaced when studies^7 predicted these compounds to have

high crystal densities coupled with explosive performances significantly greater than standard

C-nitro explosives like TNT. These studies were correct – highly nitrated cubanes are now

known to constitute a class of high-energy shock insensitive explosives.

HO 2 C

CO 2 H NHCO 2 tBu

tBuO

2 CHN H 2 N

NH 2

O

O

N 3

N 3

OCN

NCO

O 2 N

NO 2

25 27

29 30

OO

28

26

78 % acetone–water

85 %

(PhO) 2 PON 3 ,

Et 3 N, tBuOH

94 %

1. HCl (aq), 67 %


2. NaOH, 71 %

ClCH 2 CH 2 Cl,

m-CPBA, reflux

40 %

1. SOCl 2


2. TMSN 3

Figure 2.9