Nitro Compounds

Besides cellulose derivatives, there are many other explosive molecules that have been discovered, most of which contain a nitro group (NO2).  Known as nitro compounds, these substances have been in use for millenia and can range considerably in their explosive power, depending on how many nitro groups are in the compound.  The first explosive mixture ever invented was gunpowder, also known as black powder, and was used in Ancient China, Arabia, and India.  Gunpowder works by igniting a certain proportion of potassium nitrate (also known as saltpeter), sulfur, and carbon (in the form of wood charcoal), which react to produce hot, rapidly expanding gases.  These gases expand so violently that a deadly shock wave is often produced, that can also propel a projectile such as a bullet or a cannonball, which is where its application in warfare becomes apparent.  The first firearm, the firelock, was developed in the early 1300s and was essentially an iron tube loaded with gunpowder that was ignited by the insertion of a heated wire.

The nitrogen gas that is formed in these reactions provides the main driving force behind the explosion, as the triple bond between the two nitrogen molecules makes it very stable.  One example of a nitrocompound, nitrotoluene, has only one nitro group, so it does not produce as much nitrogen gas as dinitrotoluene or trinitrotoluene (TNT), which have two and three nitro groups respectively.  Another nitro molecule called nitroglycerin is also extremely volatile, but is also very dangerous as it was often unpredictable and was too easily detonated.  Though the manufacture of this compound leveled many factories and killed thousands of workers, the demand for it was high and production continued.  Swedish scientist Alfred Nobel developed a method however in the mid 1800s that would allow the compound nitroglycerin to be used safely and reliably.  He stabilized the substance by mixing it with about one-third weight of kieselguhr, which is the remains of tiny marine animals. These two substances combine to form a plastic mass with a putty-like consistency that was easy to control but could still be detonated.

Although Nobel had intended for his invention to be used as a deterrant from war, by the late 1800s it was being used widely as a weapon of warfare, and it was first used on a grand scale in World War I.  However, the use of explosives in combat also led to further developments.  Germany relied heavily on TNT during the war, which requires saltpeter, which it bought from Chile.  When the British blockaded the trade route between the two nations, Germany worked to find a way to synthetically produce the saltpeter compound.  By 1913, German chemists had managed to do so in a process that began with the synthetic production of ammonia.  This production of ammonia also greatly helped to produce efficient fertilizers that are now crucial to sustaining world agriculture.  As one can see, the effects of nitro compounds on world society are widespread, having increased our ability to wage war, to construct tunnels and canals, and has even indirectly promoted improvments in world agriculture.