Trinitrotoluene

Trinitrotoluene (TNT) is a chemical compound with the formula C₆H₂(NO₂)₃CH₃. This yellow-coloured solid is a reagent (reactant) in chemistry but is best known as a useful explosive material with convenient handling properties. The explosive yield of TNT is considered the standard measure of strength of bombs and other explosives. In chemistry, TNT is used to generate charge transfer salts.

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Explosive character

Upon detonation, TNT decomposes as follows:

2 C₇H₅N₃O₆ → 3 N₂ + 5 H₂O + 7 CO + 7 C

The reaction is exothermic but has a high activation energy. Because of the production of carbon, TNT explosions have a sooty appearance.

TNT used to be the reference point for the Figure of Insensitivity (exactly 100 by definition), but the reference point is now the more sensitive (or less insensitive) RDX which is deemed to have a FofI of exactly 80.

Toxicity, environmental concerns, and degradation

TNT is poisonous, and skin contact can cause skin irritation, causing the skin to turn a bright yellow-orange color. During the First World War, munition workers who handled the chemical found that their skin turned bright yellow, which resulted in their acquiring the nickname "canary girls" or simply "canaries." People exposed to TNT over a prolonged period tend to experience anemia and abnormal liver functions. Blood and liver effects, spleen enlargement and other harmful effects on the immune system have also been found in animals that ingested or breathed trinitrotoluene. There is evidence that TNT adversely affects male fertility,^{[citation needed]} and TNT is listed as a possible human carcinogen. Consumption of TNT produces red urine through the presence of breakdown products and not blood as sometimes believed.2,4,6-Trinitrotoluene (September 1996).

Some military testing grounds are contaminated with TNT. Wastewater from munitions programs including contamination of surface and subsurface waters may be colored pink because of the presence of TNT. Such contamination, called "pinkwater", may be difficult and expensive to remedy.

Applications

TNT is one of the most commonly used explosives for military and industrial applications. It is valued because of its insensitivity to shock and friction, which reduces the risk of unexpected detonations. TNT melts at 80 °C (180 °F), far below the temperature at which it will spontaneously detonate, allowing it to be poured as well as safely combined with other explosives. TNT neither absorbs nor dissolves in water, which allows it to be used effectively in wet environments. Additionally, it is comparatively stable when compared to other high explosives.

Although blocks of pure TNT are available in various sizes (250, 500, and 1,000 g), it is more commonly encountered in synergistic explosive blends that comprise a variable percentage of TNT plus other ingredients. Examples of explosive blends containing TNT include

• Amatol
• Ammonal
• Baratol
• Composition B
• Composition H6
• Ednatol
• Octol
• Pentolite
• Picratol
• Tetrytol
• Torpex
• Tritonal

History

TNT was first prepared in 1863 by German chemist Joseph Wilbrand and originally used as a yellow dye. Its potential as an explosive was not appreciated for several years mainly because it was so difficult to detonate and because it was less powerful than alternatives. TNT can be safely poured when liquid into shell cases, and is so insensitive that in 1910, it was exempted from the UK's Explosives Act 1875 and was not considered an explosive for the purposes of manufacture and storage.

The German armed forces adopted it as a filling for artillery shells in 1902. TNT-filled armour-piercing shells would explode after they had penetrated the armour of British capital ships, whereas the British lyddite-filled shells tended to explode upon striking armour, thus expending much of their energy outside the ship. The British started replacing lyddite with TNT in 1907.

Preparation

TNT is synthesized in a two-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mono- and dinitrotoluene. Next, the mixture of mono- and dinitrotoluene is further nitrated with a mixture of nitric acid and oleum, a more potent nitration recipe. The waste acid from this second step can be recycled for use in the first.

Difference from dynamite

It is a common misconception that TNT and dynamite are the same, or that dynamite contains TNT. In fact, whereas TNT is a specific chemical compound, dynamite is an absorbent mixture soaked in nitroglycerin that is compressed into a cylindrical shape and wrapped in paper.

See also

• Megaton
• Explosives used during WW II

References

1. ^ Erich Ammedick: Militärchemie. eine Einführung. 4. Auflage. In: Bausteine der Chemie. VEB Deutscher Verlag für Grundstoffindustrie, Leipzig 1980, ISBN 978-3342000372 (German)