Organic Chemistry of Explosives

16 Synthetic Routes to AliphaticC-Nitro

Yields are frequently moderate for Scholl reactions. Aldoximes are not usually compatible

with these harsh reaction conditions and are very sensitive to factors such as temperature and

reaction time. Consequently, oxidation to the corresponding carboxylic acid is a major side-

reaction. However, both the ketoxime (51) and the aldoxime (53) are reported to give good

yields of the correspondinggem-dinitro compounds, (52) and (54) respectively, on treatment

with absolute nitric acid in methylene chloride followed by hydrogen peroxide.^127

[FC(NO 2 ) 2 CH 2 OCH 2 ] 2 C(NO 2 ) 2

2. H 2 O 2 52


3. H 2 O 2
   65 % (2 steps)

[FC(NO 2 ) 2 CH 2 OCH 2 ] 2 C NOH

51

FC(NO 2 ) 2 CH 2 OCH 2 CH NOH

53

FC(NO 2 ) 2 CH 2 OCH 2 CH(NO 2 ) 2

54

1. HNO 3 , CH 2 Cl 2


2. HNO 3 , CH 2 Cl 2

Figure 1.20

The nitration of oximinocyanoacetic acid esters with mixed acid at room temperature

yields dinitrocyanoacetic acid esters which are precursors to dinitroacetonitrile and its salts.^128

α-Oximinonitriles can be nitrated toα,α-dinitronitriles with anhydrous nitric acid containing

ammonium nitrate, and then subjected to ammonolysis with aqueous ammonia to give the

ammonium salt of the correspondinggem-dinitroalkane.^129

CCNOH

R

NC

RC NH 4

NO 2

NO 2

HNO 3

NH 4 NO 3

NH 3

R CN

NO 2

NO 2

R = Me, 8%

R = Et, 12 %

R = Pr, 22 %

Figure 1.21

A series ofα,α-dinitroesters have been synthesized from the reaction ofα-oximinoesters

with cold nitric acid containing ammonium nitrate, followed by oxidation of the resulting

pseudonitroles with oxygen.^130

1.6.1.2 Ponzio reaction

CH NOH

NO 2

CH(NO 2 ) 2

1. N 2 O 4 , Et 2 O, 38 %

55 56

2. HNO 3 , H 2 SO 4 , 93 %

Figure 1.22

The Ponzio reaction^131 provides a useful route togem-dinitro compounds and involves treating

oximes with a solution of nitrogen dioxide or its dimer in diethyl ether or a chlorinated solvent.

The Ponzio reaction works best for aromatic oximes where the synthesis of many substituted

aryldinitromethanes have been reported.^132 Compound (56), an isomer of TNT, is formed from

the reaction of dinitrogen tetroxide with the oxime of benzaldehyde (55) followed by mono-

nitration of the aromatic ring with mixed acid.^133 Yields are usually much lower for aliphatic

aldoximes and ketoximes.134b,^135 The parent carbonyl compound of the oxime is usually the

major by-product in these reactions.