Organic Chemistry of Explosives

48 Synthetic Routes to AliphaticC-Nitro

Formals and acetals prepared from the reaction of polynitroaliphatic alcohols with

formaldehyde and acetaldehyde have found use as explosive plastisizers for nitrocellulose

and in plastic bonded explosives (PBXs). Formals of polynitroaliphatic alcohols are com-

monly prepared via reaction with trioxane or paraformaldehyde in the presence of sulfuric

acid as a condensing agent. Bis(2,2-dinitropropyl)formal (175) is prepared from the reac-

tion of trioxane with 2,2-dinitropropanol (25).^322 ,^323 The reaction of 2,2,2-trinitroethanol

(159) and 2,2-dinitro-1,3-propanediol (19) with formaldehyde in the presence of sulfu-

ric acid yields bis(2,2,2-trinitroethyl)formal (177)^322 and the 1,3-dioxane (178)^322 ,^324 re-

spectively. Bis(2-fluoro-2,2-dinitroethyl)formal (176) (FEFO), an energetic plastisizer used

in some high energy PBXs, is prepared in 75–80 % yield from the condensation of

2-fluoro-2,2-dinitroethanol (119) with formaldehyde in the presence of concentrated sulfu-

ric acid.^237 ,^312 ,^325 −^327

NO 2

C

NO 2

25

CH 3 CH 2 OH

NO 2

NO 2

CH 3 CCH 2 O C OCH 2

CH 3

179

H

C CH 3

NO 2

NO 2

paraldehyde

BF 3

Figure 1.87

Sulfuric acid cannot be used for the synthesis of acetals and so bis(2,2-dinitropropyl)acetal

(179) is prepared from the reaction of paraldehyde with 2,2-dinitropropanol (25) in the pres-

ence of boron trifluoride.^322 ,^323 A 50:50 eutectic mixture of bis(2,2-dinitropropyl)formal (175)

and bis(2,2-dinitropropyl)acetal (179) has found use as an energetic liquid plastisizer for ni-

trocellulose.

CCl 4 , FeCl 3 CHCl 3 , FeCl 3

89 % 74 %

HC[OCH 2 C(NO 2 ) 3 ] 3

181

C[OCH 2 C(NO 2 ) 3 ] 4

180

NO 2

NO 2

159

O 2 N CCH 2 OH

Figure 1.88

Orthoesters of polynitroaliphatic alcohols have been synthesized in the presence of metal

chloride Lewis acid catalysts. Tetrakis(2,2,2-trinitroethyl)orthocarbonate (180) and tris(2,2,2-

trinitroethyl)orthoformate (181) are obtained from the reaction of 2,2,2-trinitroethanol

(159) with carbon tetrachloride and chloroform, respectively, in the presence of anhy-

drous ferric chloride.^328 ,^329 Analogous reactions with 2-fluoro-2,2-dinitroethanol have been

reported.^329

The weak nucleophilic nature of polynitroaliphatic alcohols is also reflected in their slow

reactions with isocyanates to yield carbamates. These reactions often need the presence of

Lewis acids like ferric acetylacetonate or boron trifluoride etherate.^330 The reaction of bi-

functional isocyanates with polynitroaliphatic diols has been used to synthesize energetic

polymers.^330

Alkylations and other reactions using polynitroaliphatic alcohols as nucleophiles usually re-

quire Lewis acid catalysts. A comprehensive review of the chemistry of fluoronitro compounds,