C7h5n3o6
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.
Preparation
Industrially, TNT is synthesized in a three-step process. First, toluene is nitrated with a mixture of sulfuric and nitric acid to produce mono-nitrotoluene or MNT. In the final step, the DNT is nitrated to trinitrotoluene or TNT using an anhydrous mixture of nitric acid and oleum.
Nitric acid is consumed by the manufacturing process, but the diluted sulfuric acid can be reconcentrated and reused. Subsequent to nitration, TNT is stabilized by a process called sulphitation, where the crude TNT is treated with aqueous sodium sulfite solution in order to remove less stable isomers of TNT and other undesired reaction products.
The rinse water from sulphitation is known as red water and is a significant pollutant and waste product of TNT manufacture.
Control of nitrogen oxides in feed nitric acid is very important because free nitrogen dioxide can result in oxidation of the methyl group of toluene. This reaction is highly exothermic and carries with it the risk of runaway reaction and explosion.
In the laboratory, 2,4,6-trinitrotoluene is produced by a two step process.
A nitritating mixture of concentrated nitric and sulfuric acids is used to nitrate toluene to a mixture of mono- and di-nitrotoluene isomers, with cooling to maintain careful temperature control. The nitrated toluenes are separated, washed with dilute sodium bicarbonate to remove oxides of nitrogen, and then carefully nitrated with a mixture of fuming nitric acid and sulfuric acid.
Towards the end of the nitration, the mixture is heated on a steam bath. The trinitrotoluene is separated, washed with a dilute solution of sodium sulfite and then recrystallized from alcohol.
Applications
TNT is one of the most commonly used explosives for military and industrial applications.
During the 20th century, amatol, a mixture of TNT with ammonium nitrate was a widely used military explosive.
Detonation of TNT can be done using a high velocity initiator or by efficient concussion.
For many years, TNT used to be the reference point for the Figure of Insensitivity. TNT has a rating of exactly 100 on the F of I scale.
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 is still widely used by the United States military and construction companies around the world.
The majority of TNT currently used by the US military is manufactured by Radford Army Ammunition Plant near Radford, Virginia.
HE 120mm mortar shell fitted with proximity fuze. Manufactured in January 2006 and marked to indicate a 100% TNT filling
Safety and toxicity
TNT is poisonous, and skin contact can cause skin irritation, causing the skin to turn a bright yellow-orange color.
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. Consumption of TNT produces red urine through the presence of breakdown products and not blood as sometimes believed.
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.