Organic Chemistry of Explosives

38 Synthetic Routes to AliphaticC-Nitro

alcohols with two or more strong electron-withdrawing groups on theβ-carbon atom to the

alcohol functionality make the corresponding alkoxide a very weak nucleophile. However, there

are cases of the 2-fluoro-2,2-dinitroethoxide anion (134) undergoing Michael 1,4-addition with

some very reactive Michael acceptors.^261

FCCH 2 OH

NO 2

NO 2

FCCH 2 O

NO 2

NO 2

OH

FC(NO 2 ) 2 + CH 2 O

134

• CH 2 O

119

Figure 1.62

1.10.2.2 Additions to nitroalkenes

(NO 2 ) 3 CH + (NO 2 ) 3 CCH 2 CH 2 NO 2

135 136112

50 %

CH 2 =CHNO 2

Figure 1.63

The conjugate 1,4-addition of nitronate anions and other nucleophiles to α-

nitroalkenes constitutes an important method for the synthesis of polynitroaliphatic

compounds.^250 ,^253 ,^258 ,^260 ,^267 −^269 Nitroform (112) reacts with nitroethene (135) and 2-

nitropropene to yield 1,1,1,3-tetranitropropane^258 (136) and 1,1,1,3-tetranitrobutane^267

respectively. A number of examples of additions of 1,1-dinitroethane, 1,1-dinitropropane

and 1,1-dinitrobutane to nitroalkenes have been reported.^260 ,^267 ,269cFeuer and co-workers^250

reported the synthesis of 1,3,3,6,6,8-hexanitrooctane (137) from the reaction of 1,1,4,4-

tetranitrobutane (30) with nitroethene under basic conditions.

CCCH 2 CH 2

NO 2

NO 2

NO 2

NO 2

CCHCH 2 CH 2 O 2 N(CH 2 ) 2 (CH 2 ) 2 NO 2

NO 2

NO 2

NO 2

NO 2

H

THF, Triton B, 58 %

30 137

2 CH 2 =CHNO 2

Figure 1.64

Synthetic routes to α-nitroalkenes have been discussed in previous sections. Gen-

eral routes include: (1) treatingβ-nitroacetates with alkali metal acetates, carbonates or

bicarbonates,^5 ,^268 ,^270 (2) elimination of water fromβ-nitroalcohols via heating with phthalic

anhydride^271 or in the presence of a base,^40 ,^272 ,^273 and (3) degradation of the Mannich products

derived from a primary nitroalkane, formaldehyde, and a secondary amine.^274

Direct Michael addition of secondary nitroalkanes toα-nitroalkenes gives acceptable yields

of addition product, however, in general, primary nitroalkanes give much poorer yields of prod-

uct. Low to moderate yields in both cases are mainly due to the tendency ofα-nitroalkenes

to polymerize before and during a reaction. More common is thein situgeneration of the

α-nitroalkenes in these addition reactions. Feuer and Miller^268 discovered that 2-nitroalkyl

acetates (β-nitroacetates) react with base, in the form of sodium acetate or the sodium salt

of a nitroalkane, to generate the correspondingα-nitroalkene. Michael adducts are formed if