Organic Chemistry of Explosives

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JWBK121-09 October 11, 2006 21:24 Char Count= 0

N-nitration 355

The nitration of ethylbenzene (5) to 4-nitroethylbenzene (6) is complete in 5 minutes at 5◦C

and further nitration to 2,4-dinitroethylbenzene (7) requires only 10 minutes at 25◦C.^39 ,^40 2,4-

Dinitroethylbenzene is a component of the energetic plasticizer known as K-10 (2:1 mixture

of 2,4-dinitroethylbenzene and 2,4,6-trinitroethylbenzene).

NO 2

Cl Cl

Cl

8

NO 2

Cl Cl

Cl

9

NO 2

NO 2

Cl Cl

Cl

10

O 2 N NO 2

NO 2

H 2 NNH 2

NH 2

11

(TATB)

O 2 N NO 2

N 2 O 5 , HNO 3

32–35 °C, 2–4 mins

N 2 O 5 , HNO 3

PhCH 3 , NH 3

Figure 9.8

The nitration of 1,3,5-trichloro-2-nitrobenzene (8) to 1,3,5-trichloro-2,4-dinitrobenzene (9)

with dinitrogen pentoxide in absolute nitric acid goes to completion in only 2–4 minutes at 32–

35 ◦C.^38 Further nitration of (9) would yield 1,3,5-trichloro-2,4,6-trinitrobenzene (10) which

undergoes ammonolysis on treatment with ammonia in toluene to give the thermally stable ex-

plosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) (11). The same sequence of reactions with

1,3-dichloro-2-nitrobenzene provides a route to 1,3-diamino-2,4,6-trinitrobenzene (DATB).

Such reactions are clean and occur in essentially quantitative yield.

Dinitrogen pentoxide has been used for aromatic nitration in other media and some are

notable. While a solution of dinitrogen pentoxide in carbon tetrachloride will not convert 1,3-

dinitrobenzene to 1,3,5-trinitrobenzene, a solution in concentrated sulfuric acid at 160◦C will

effect this conversion.^33 In this medium dinitrogen pentoxide is fully ionized to nitronium and

nitrate ions.^41 Solutions of dinitrogen pentoxide in liquid sulfur trioxide have been used for

the nitration of some deactivated pyridines.^42

The complex formed between dinitrogen pentoxide and boron trifluoride is a powerful

nitrating agent and has been used in organic solvents like carbon tetrachloride, nitromethane

and sulfolane for the nitration of deactivated aromatic substrates, including the conversion

of benzoic acid to 1,3-dinitrobenzoic acid in 70 % yield.^43 Olah and co-workers^44 studied

aromatic nitrations with dinitrogen pentoxide in the presence of other Lewis acids.

Nitrations with dinitrogen pentoxide in the presence of phosphorous pentoxide enable the

complete utilization of available nitrogen.^45

9.6 N-nitration

The directN-nitration of secondary amines with acidic reagents is only possible in the case

of substrates of low basicity. However, the presence of catalytic amounts of chloride ion in