Organic Chemistry of Explosives

110 Synthetic Routes to Nitrate Esters

C C

CH 2 OH

O 2 NOCH 2 CH 2

ONO 2

CH 2 OH

CH 2 OH

C

CH 2 ONO 2

CH 2 ONO 2

CH 2 ONO 2

CH 2 =CHCH 2 OCH 2

CH 2 ONO 2

CH 2 ONO 2

CH 2 ONO 2

CH 2 =CHCH 2 OCH 2

CH 2 OCH 2

74 75

76

Figure 3.39

Dihydroxylation of the allyl groups of (70) with hydrogen peroxide and catalytic osmium

tetroxide, followed byO-nitration of the product (72), yields the hexanitrate ester (73). Sim-

ilar treatment of the mono-allyl ether (74) affords the pentanitrate ester (76). Evans and

Gallaghan^141 alsoO-nitrated the hydroxy groups of (70) and (74) to yield the dinitrate and

trinitrate esters, (71) and (75), respectively. The dinitrate ester (71) may find use as a monomer

for the synthesis of energetic binders.

Many polynitrate esters are powerful explosives but have unfavourable physical properties.

Consequently, a considerable amount of work has been directed towards changing the prop-

erties of pre-existing explosives. Such work serves to improve the properties of pre-existing

explosives by increasing thermal stability, reducing sensitivity to shock, or lowering the melting

point so that melt casting of charges becomes possible.

pyridine, 73 %

or

Me 2 CO, H 2 O,

(NH 4 ) 2 CO 3 , 70 %

78, R = acetate, 85 %

79, R = propionate, 70 %

80, R = phenylacetate, 68 %

14 77

O 2 NO O 2 NO

ONO 2 ONO 2 ONO 2

ONO 2

ONO 2 ONO 2

ONO 2

ONO 2 ONO 2

O 2 NO

OR ONO 2

ONO 2

ONO 2 ONO 2

OH

Figure 3.40

Interest has focused on derivatives of mannitol hexanitrate (14) as potential explosives

because although this nitrate ester is a powerful explosive it has some property characteristics of

a primary explosive. Treatment of mannitol hexanitrate (14) with pyridine^142 ,^143 or ammonium

carbonate^143 in aqueous acetone leads to a very selective denitration with the formation of

mannitol-1,2,3,5,6-pentanitrate (77). Marans and co-workers^143 synthesized the acetate (78),

the propionate (79), and the phenylacetate (80) derivatives of mannitol-1,2,3,5,6-pentanitrate

and all have significantly lower melting points than mannitol hexanitrate. The incorporation

of such groups can also help to increase the solubility of an explosive in the melt of another

explosive.

Pentaerythritol tetranitrate (PETN) is a powerful high explosive with importance for both

commercial and military applications. It is therefore unsurprising that work has been focused