Organic Chemistry of Explosives

22 Synthetic Routes to AliphaticC-Nitro

C

HNO 2 K

C

2 N NOHO

X

X

C(NO 2 ) 3

X

X = m-NO 2 , 60 %

X = p-NO 2 , 58 %

X = H, 77 %

X = m-NO 2 , 84 %

X = p-NO 2 , 58 %

N 2 O 4 , Et 2 O

Figure 1.28

by treating primary nitronic acids or their salts (nitronates) with nitrous acid, also undergo

nitration to 1,1,1-trinitromethyl compounds.^173 ,^174 ,^177

CNO 2 K

O 2 N

H 3 C

N 2 O 4

24

73

NO 2

C

NO 2

3 NOCH

NO 2

C

NO 2

CH 3 NO 2

N 2 O 4 , Et 2 O

72

Figure 1.29

Mixed acid or anhydrous nitric acid has been used for the nitration ofgem-nitronitronate

salts to the corresponding 1,1,1-trinitromethyl compounds.^178 A convenient route to hexan-

itroethane (75) involves treating the dipotassium salt of 1,1,2,2-tetranitroethane (74) with

mixed acid; the nitration proceeding via electrophilic addition of the nitronium cation to the

bis-nitronitronate ion.^178

CC

O 2 N NO 2

KO 2 NNO 2 K

74

CC

NO 2 NO 2

NO 2 NO 2

O 2 N NO 2

75

H 2 SO 4 , HNO 3 ,

CH 2 Cl 2 , 92 %

Figure 1.30

Tetranitromethane is an electrophilic source of nitronium cation and has been used in

alkaline solution for the nitration of 1,1-dinitropropane to 1,1,1-trinitropropane (32 %), and

for nitration of 1-phenyl-3-nitropropane to 1-phenyl-3,3-dinitropropane (32 %) and its further

nitration to 1-phenyl-3,3,3-trinitropropane (33 %).^179

Olsen and co-workers^180 reported the nitration of secondary nitroalkanes togem-dinitro

compounds with nitronium tetrafluoroborate in acetonitrile at –40◦C. Yields are lower com-

pared to the Kaplan–Shechter reaction and significant amounts of pseudonitroles are formed,

but this is possibly due to impure reagent.

Nitryl fluoride has been used for the nitration of terminalgem-dinitro compounds to the

corresponding 1,1,1-trinitromethyl compounds.^181