Organic Chemistry of Explosives

80 Polynitropolycycloalkanes

Br

Br

Br Br

AcHN

AcHN NHAc

NHAc

Cl H 3 N

Cl H 3 N NH

3 Cl

NH 3 Cl

O 2 N

O 2 N NO 2

NO 2

(^100101)
102
104 103
Br 2 , AlCl 3
70 °C, 58 %

1. Br 2 , Al, CH 2 I 2 ,
   80 °C, 75 %
   2. CH 3 CN, hv,
   60 °C, 51 %

HCl (aq)

reflux

NaOH (aq), Me 79 %

2 CO,

MgSO 4 , KMnO 4

45 %

Figure 2.21

Sollett and Gilbert^28 working for ARDEC (US Army Research, Development and Engineer-

ing Center) first reported the synthesis of 1,3,5,7-tetranitroadamantane (104) in 1980. Their

synthesis starts directly from adamantane (100), which on halogenation with bromine and

aluminium chloride yields 1,3,5,7-tetrabromoadamantane (101). Previous attempts for a direct

Br→NH 2 conversion have been reported^29 without success. A more indirect route for this

conversion involves halogen exchange of the tetrabromide (101) to the tetraiodide, followed

by a photo-induced Ritter reaction to give the tetraacetamide (102), which on acid catalyzed

hydrolysis yields the tetrahydrochloride salt of 1,3,5,7-tetraaminoadamantane (103).^28 The

synthesis is complete by treating (103) with an aqueous acetone solution of potassium per-

manganate which generates 1,3,5,7-tetranitroadamantane (104) in 45 % yield; this reflecting a

relative yield of 82 % for the oxidation of each of the four amino groups. Surprisingly, while

the permanganate oxidation of tertiary amines has been known for some time, this method had

never been used to synthesize polynitro compounds until this example was reported. 1,3,5,7-

Tetranitroadamantane shows high thermal stability (m.p. 361◦C) and a similar high chemical

stability would be expected.

The synthesis of 1,3,5,7-tetranitroadamantane (104) from 1,3,5,7-tetraaminoadamantane

(103) has been improved upon by the use of dimethyldioxirane^30 (91 %), and also, by using

a mixture of sodium percarbonate andN,N,N′,N′-tetraacetylethylenediamine in a biphasic

solvent system, followed by treating the crude product with ozone (91 %)^31 ; the latter involving

thein situgeneration of peroxyacetic acid.

Archibald and Baum^32 reported the synthesis of 2,2,6,6-tetranitroadamantane (109). Their

synthesis starts from the dioxime of 2,6-adamantanedione (105), which on reaction with a

buffered solution of NBS yields the bromonitro intermediate (106), surprisingly, without the

need of an oxidant for nitroso to nitro group conversion. Reaction of (106) with sodium

borohydride yields 2,6-dinitroadamantane (107). Attempted oxidative nitration of the an-

ion of (107) with sodium nitrite and silver nitrate was unsuccessful, even though the same

reaction with 2-nitroadamantane gave 2,2-dinitroadamantane in 89 % yield. However, the

alkaline nitration of (107) with tetranitromethane in ethanolic potassium hydroxide gave

2,2,6,6-tetranitroadamantane (109) in 68 % yield along with a 20 % yield of 6,

6-dinitro-2-adamantanone (108); the latter probably arising from a Nef reaction. 2,2,6,6-

Tetranitroadamantane, like its 1,3,5,7-isomer, is reported to exhibit high thermal stability.

Archibald and Baum^32 tried to apply the same strategy used to prepare 2,2,6,6-tetranitro-

adamantane (109) to synthesize 2,2,4,4-tetranitroadamantane (117) from the dioxime of