Nitroglycerin (NG), more correctly called glycerol trinitrate, is the nitrate ester of glycerol. It is one of the most commonly used explosives, found in dynamites, blasting gelatine and smokeless powders.
Nitroglycerin is a dense (1.59 g/cm3), oily, colourless liquid with freezing point 14 °C. It is a solvent for nitrocellulose, and the resulting gel is known as blasting gelatine (blasting jelly).
Nitroglycerin is a powerful explosive, similar to ethylene glycol dinitrate. It is highly sensitive to impact, but incomplete detonation result from everything but a strong initiation. This causes its lead block test value to be dependent on the strength of initiation:
- detonator No.1 ... 190 cm3
- detonator No.2 ... 225 cm3
- detonator No.6 ... 460 cm3
- detonator No.8 ... 590 cm3
Nitroglycerin pills contain a very small amount of nitroglycerin, impractical for extraction and use (though some types of pills will burn if ignited).
The classic dynamite contains NG mixed with kieselgur (diatomaceous earth), to make it stable. Most smokeless powders contain nitro. Extracting the nitroglycerin from these products however, is impractical and dangerous for large quantities.
Nitroglycerin is prepared by the nitration of glycerol using a concentrated mixture of nitric and sulfuric acids in an ice bath, at very low temperatures. The information in this article is not enough to attempt such a synthesis though, as the risks are very high with this compound.
- Smokeless powder
- Various propellents
Nitroglycerin is a dangerously sensitive and extremely powerful explosive. Improperly neutralized it is even more sensitive. It is also toxic by skin contact and inhalation. As a strong vasodilator, it results in severe headaches, though it is used medicinally in very low concentrations.
Never store liquid nitroglycerin, even for short periods!
Dynamite, which consists of nitroglycerin mixed with diatomite, is much more stable, though over time the dynamite will "sweat" or "weep" its nitroglycerin, which can then pool in the bottom of the box or storage area and can explode.
Nitroglycerin can be neutralized by adding sodium hydroxide or being exposed to sunlight for a while.
Chemistry and Technology of Explosives - Volume II, first edition, 1965.