172 Synthetic Routes to AromaticC-Nitro Compounds
Warman and Siele^237 reported a high yielding route to 1,3-dichloro-2,4,6-trinitrobenzene
(106) (styphnyl chloride) which involves treating styphnic acid (5) with two equivalents of pyri-
dine followed by reacting the resulting pyridinium salt (133) with phosphorous oxychloride.
1,3-Dichloro-2,4,6-trinitrobenzene is an important precursor to the thermally stable explosive
DATB (Section 4.8.1.4).
4.8.4 Synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)
2,4,6-Trinitro-1,3,5-triaminobenzene (14), chemically abbreviated to TATB, has emerged as
an important modern explosive. TATB is very insensitive to impact and friction, exhibits high
thermal stability, and is usable in the 260–290◦C range, but has no observable melting point
(> 350 ◦C with decomposition). Such properties are attributed to strong intermolecular and
intramolecular hydrogen bonding between adjacent nitro and amino groups.^274 TATB finds
extensive military use in low vulnerability munitions and in applications requiring high ther-
mal stability i.e. warheads of high-speed missiles. Agencies like the American Department of
Energy and Department of Defence have switched over from using conventional secondary high
explosives in nuclear weapons to using TATB as a matter of safety.^275 The performance of TATB
(d= 1 .94 g/cm^3 ,VOD∼8000 m/s) lags behind nitramine explosives like RDX (d= 1. 70
g/cm^3 ,VOD∼8440 m/s) and HMX (d= 1 .89 g/cm^3 ,VOD∼9110 m/s) but is considerably
higher than other polynitroarylenes like TNT (d= 1 .55 g/cm^3 ,VOD∼6850 m/s), a conse-
quence of increased crystal density due to the introduction of amino functionality. A large num-
ber of explosive compositions and plastic bonded explosives based on TATB have been reported
for specialized applications and these have been recently reviewed by Agrawal.^276 At present
the cost of TATB production is relatively high and prevents its use for commercial applications.
ClClClClClClO 2 N NO 2NO 2
34NH 2H 2 N NH 2O 2 N NO 2NO 2
14
(TATB)NH 3 , PhCH 333oleum,
fuming HNO 3150 °C, 80 % 150 °C, 100 %Figure 4.56All reported syntheses of TATB to date involve the nitration of substrates containing leaving
groups which are subsequently replaced by amino groups. The current industrial synthesis
of TATB (14) involves the nitration of 1,3,5-trichlorobenzene (33) to 1,3,5-trichloro-2,4,6-
trinitrobenzene (34) followed by reaction with ammonia in toluene under pressure.^53 Both
nitration and amination steps require forced conditions with elevated temperatures.
OCH 3ClClOCH 3Cl ClNO 2NO 2
135O 2 NNH 2H 2 N NH 2O 2 N NO 2NO 2
14H 2 SO 4 , HNO 3 NH 3 , PhCH 3100 °C, 98 % 30 °C, 96 %134Figure 4.57