Organic Chemistry of Explosives

Nitration of compounds containing acidic hydrogen 29

NCCH 2 (CH 2 ) 2 CH 2 CN

O 2 NCH 2 (CH 2 ) 2 CH 2 NO 2

CCH 2 CH 2 C

NO 2

CN

O 2 N

NC

2 K+

(^9596)
27
KOtBu

1. KOH (aq), heat


2. AcOH
   32 % (2 steps)

2-

CH 3 (CH 2 ) 4 ONO 2

-50 °C, 93 %

Figure 1.39

Feuer and co-workers^216 extended their studies to the alkaline nitration ofα,ω-dinitriles.

Nitration with potassiumtert-butoxide and amyl nitrate in THF at− 30 ◦C yields the cor-

responding dipotassium salt of theα,ω-dinitro-α,ω-dinitrile. The nitronate salts from these

reactions are isolated via methanol-induced precipitation from the aqueous reaction liquors,

a process which also separates the product from impurities. These salts undergo hydrolysis

on treatment with aqueous potassium hydroxide, and subsequent acidification yields the cor-

respondingα,ω-dinitroalkane. This route has been used to synthesize 1,4-dinitrobutane (27)

from apidonitrile (95) in 30 % overall yield.

Feuer and co-workers^217 also nitrated ring-substituted toluenes to the corresponding

arylnitromethanes with potassium amide in liquid ammonia. Sulfonate esters^218 andN,N-

dialkylamides^219 undergo similar nitration; the latter isolated as theirα-bromo derivatives.

Alkaline nitration of ethyl andtert-butyl carboxylic esters with potassium amide in liquid

ammonia yields both theα-nitroester and the corresponding nitroalkane from decarboxy-

lation.^220

Treating the dianion of a carboxylic acid with an alkyl nitrate leads to anα-nitrocarboxylic

acid which readily undergoes decarboxylation to the corresponding nitroalkane.^221 This method

is particularly useful for the synthesis of arylnitromethanes containing electron-donating

groups.^221

1.8.1.2 Alkaline nitration with cyanohydrin nitrates

Acetone cyanohydrin nitrate, a reagent prepared from the nitration of acetone cyanohydrin

with acetic anhydride-nitric acid,^222 has been used for the alkaline nitration of alkyl-substituted

malonate esters.^222 In these reactions sodium hydride is used to form the carbanions of the

malonate esters, which on reaction with acetone cyanohydrin nitrate form the corresponding

nitromalonates. The use of a 100 % excess of sodium hydride in these reactions causes the

nitromalonates to decompose by decarboxylation to the correspondingα-nitroesters. Alkyl-

substituted acetoacetic acid esters behave in a similar way and have been used to synthesize

α-nitroesters.^223 Yields ofα-nitroesters from both methods average 50–55 %.

In a related reaction arylacetonitriles are nitrated to the correspondingα-nitronitriles, which

on alkaline hydrolysis and subsequent acidification, yield arylnitromethanes.^223 This method

has been used to convert phenylacetonitrile to phenylnitromethane in 70 % overall yield without

the need for intermediate purification.

Acetone cyanohydrin nitrate is, however, of limited use for the nitration of many carbanions

and is rapidly destroyed in the presence of alkoxides.^224 Its use for the nitration of weakly basic