Question #a203b

1 Answer
Apr 10, 2017

TNT is a yellow solid that is used as a reagent in some chemical syntheses, but is most famous for its use as an explosive material.


TNT stands for trinitrotoluene. As you might know, a toluene is a benzene derivative with a #CH_3# group attached to it.
enter image source here
Structural formula of toluene.

TNT is prepared by a three-stage nitration reaction. At first, toluene is nitrated with nitric acid and sulfuric acid. The reactions are as follows:
Formation of electrophile:#H_2SO_4 + HNO3 -> HSO_4^(-) + H_2NO_3^+#
#H_2NO_3^(+) -> NO_2^(+) + H_2O#
The #NO_2^(+)# acts as the electrophile, which is attacked by the electron-rich toluene ring.
#C_6H_5CH_3 + NO_2^(+) -> C_6H4CH_3NO_2#
The product of this reaction is mononitrotoluene(MNT), or simply nitrotoluene.

For the second stage, the MNT is renitrated in the same manner.
#C_6H_4CH_3NO_2 + NO_2^(+) -> C_6H_3CH_3(NO_2)_2#
The product of this reaction is 2,4-dinitrotoluene, or DNT. This DNT is then nitrated to 2,4,6-trinitrotoluene, TNT, using and anhydrous mixture of nitric acid and oleum.
#C_6H_3CH_3(NO_2)_2 + NO_2^(+) -> C_6H_2CH_3(NO_2)_3#
enter image source hereStructural formula of TNT.

TNT's most common use is as an explosive. TNT is insensitive to shock and friction, so the risk of accidentally setting it off is greatly reduced, a problem greatly associated with nitroglycerine. TNT doesn't dissolve in water, neither does it absorb water, making it perfect for use in wet conditions.

Another property for which TNT is valued as such is that it has a melting point of 80 degrees Celsius, which is far below the temperature at which TNT would explode spontaneously. This allows TNT to be poured into any mold or mixed with other compounds safely. TNT is set-off using a booster, a small explosive attached to the main explosive.