Organic Chemistry of Explosives

34 Synthetic Routes to AliphaticC-Nitro

the reaction of nitroform (112) with the corresponding vinyl ethers.^243 The synthesis ofα-

trinitromethyl ethers from the reaction of an acetal with nitroform involves 1,2-addition via an

intermediate oxonium cation; (117) is synthesized in 85 % yield from the reaction of nitroform

with the acetal (116).^244 α-Trinitromethyl ethers have been synthesized in a one-pot process

from nitroform in the presence of an aldehyde and alcohol, in which case, the acetal is formed

in situ.^245

O OCH 3 O C(NO 2 ) 3

HC(NO 2 ) 3

85 %

116 117

Figure 1.50

Shackelford and co-workers^246 studied the 1,2-addition of 2,2-dinitropropanol, 2,2,2-

trinitroethanol, and 2-fluoro-2,2-dinitroethanol across the double bonds of vinyl ethers. These

reactions are Lewis acid catalyzed because of the weak nucleophilic character of alcohols

which contain two or three electron-withdrawing groups on the carbonβto the hydroxy func-

tionality. Base catalysis is precluded since alkaline conditions lead to deformylation with the

formation of formaldehyde and the nitronate salt.

CH 2 OH

NO 2

NO 2

H 2 C CHOCH CH 2 +

119

118

121

120

122

H 2 C CHOCH 2 CF(NO 2 ) 2

C

OCH 2 CF(NO 2 ) 2

H

C

(O 2 N) 2 CFCH 2 O OCH 2 CF(NO 2 ) 2

CH 3 CH 3

CH 3

Hg 2 SO 4

or HgSO 4

OCH CH 2

CH 2 Cl 2

F C

HH

CO

Figure 1.51

The reaction of 2-fluoro-2,2-dinitroethanol (119) with divinylether (118) under different

conditions gives three products, namely, the expected vinyl acetal (120) and the bis-acetal (121)

from addition of one and two equivalents of 2-fluoro-2,2-dinitroethanol, respectively, and the

vinyl ether (122), which results fromtrans-etherification of (118) with loss of acetaldehyde.

Shackelford and co-workers^246 found that by altering the nature of the Lewis acid catalyst and

the reaction stoichiometry they were able to alter the distribution ratio of these products.

H 2 C CHOAc +

123

HgSO 4

CH 2 Cl 2

CH 2 OH

NO 2

NO 2

119

OCH 2 CF(NO 2 ) 2

OCH 2 CF(NO 2 ) 2

124

C H 3 C2 F CH

Figure 1.52

Thetrans-etherification of vinyl ethers is not uncommon under Lewis acid catalysis. 1,1-

Bis(2-fluoro-2,2-dinitroethyl)ethyl acetal (124) is obtained on reaction of two equivalents of

2-fluoro-2,2-dinitroethanol (119) with vinyl acetate (123) in the presence of mercuric sulfate.^247