Home > Nitroglycerin (Molecule of the Month for March 2007 )

Picture of Nitroglycerin

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Picture of Nitroglycerin

C3 H5 N3 O9

Nitroglycerin is a viscous, colorless, oily, explosive liquid obtained by nitrating glycerol. It is used in the manufacture of explosives, specifically dynamite, and as such is employed in the construction and demolition industries, and as a plasticizer in some solid propellants. In medicine, nitroglycerin is used as a heart medication (under the trade names Nitrospan and Nitrostat). It is used as a medicine for angina pectoris.

Nitroglycerin was discovered by chemist Ascanio Sobrero in 1847, working under TJ Pelouze at the University of Torino. The best manufacturing process was developed by Alfred Nobel in the 1860s. His company exported a liquid combination of nitroglycerin and gunpowder as 'Swedish Blasting Oil', but it was extremely dangerous as a result of its extreme instability. The liquid was widely banned, and this led to the development of dynamite), by mixing the nitroglycerine with inert or combustible absorbents. In its pure form, it is a contact explosive and degrades over time to even more unstable forms. This makes it highly dangerous to transport or use. In this undiluted form it is one of the most powerful high explosives, comparable to the military explosives RDX, PETN and C-4.

Nitroglycerin is prepared by nitration of glycerol (also known as glycerin). In the process, glycerol is slowly tipped into a mix of full concentration nitric acid and sulfuric acid. The mixed acid must be cooled to approximately room temperature before the glycerol is added because they will exotherm (heat up) greatly when combined. A few seconds after mixing, the vessel must be immersed in a jacket of ice water to prevent the exothermic reaction from overheating it, causing nitric acid decomposition or even explosion. If the reaction is successful, the nitroglycerin will form a slightly yellow or straw colored liquid which will float to the top of the acid mix. The mix is then carefully poured into a large container of water. The nitroglycerin will settle to the bottom. Due to the great dangers associated with its production, most commercial nitroglycerin production facilities are in offshore rigs or very remote locations.

Formal Chemical Name (IUPAC)
propane-1,2,3-triyl trinitrate



Update by Karl Harrison
(Molecule of the Month for March 2007 )