Nitroglycerin

Nitroglycerin (NG) (alternative spelling nitroglycerine), also known as trinitroglycerol (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless or pale yellow, oily, explosive liquid most commonly produced by <a href="/facts/Nitration/VnszL09H">nitrating</a> <a href="/facts/Glycerol/sRQ6NBQQ">glycerol</a> with <a href="/facts/White_fuming_nitric_acid/UDbwGp6s">white fuming nitric acid</a> under conditions appropriate to the formation of the nitric acid <a href="/facts/Ester/FoUAIIw4">ester</a>. Chemically, the substance is a <a href="/facts/Nitrate_ester/4mSHBqaw">nitrate ester</a> rather than a <a href="/facts/Nitro_compound/pem2BhMY">nitro compound</a>, but the traditional name is retained. Discovered in 1846 by <a href="/facts/Ascanio_Sobrero/knAf2sSA">Ascanio Sobrero</a>, nitroglycerin has been used as an active ingredient in the manufacture of explosives, namely <a href="/facts/Dynamite/WQ06BcGK">dynamite</a>, and as such it is employed in the <a href="/facts/Construction/58eqDhy9">construction</a>, <a href="/facts/Demolition/205k0BUM">demolition</a>, and <a href="/facts/Mining/g6uDIFab">mining</a> industries. It is combined with <a href="/facts/Nitrocellulose/5NoD5eTm">nitrocellulose</a> to form double-based <a href="/facts/Smokeless_powder/BQfV4rcN">smokeless powder</a>, used as a <a href="/facts/Propellant/K88ymXRy">propellant</a> in artillery and firearms since the 1880s. 
As is the case for many other explosives, nitroglycerin becomes more and more prone to exploding (i.e. <a href="/facts/Decomposition/6Bve4pgl">spontaneous decomposition</a>) as the temperature is increased. Upon exposure to heat above 218 °C at sea-level <a href="/facts/Standard_atmosphere_(unit)/aTbYALII">atmospheric pressure</a>, nitroglycerin becomes extremely unstable and tends to explode. When placed in vacuum, it has an <a href="/facts/Autoignition_temperature/bRATNu6d">autoignition</a> temperature of 270 °C instead. With a melting point of 12.8 °C, the chemical is almost always encountered as a thick and viscous fluid, changing to a crystalline solid when frozen. Although the pure compound itself is colorless, in practice the presence of <a href="/facts/NOx/aC4Squ7z">nitric oxide</a> impurities left over during production tends to give it a slight yellowish tint. 
Due to its high boiling point and consequently low vapor pressure (0.00026 mmHg at 20 °C), pure nitroglycerin has practically no odor at room temperature, with a sweet and burning taste when ingested. Unintentional detonation may ensue when dropped, shaken, lit on fire, rapidly heated, exposed to sunlight and ozone, subjected to sparks and electrical discharges, or roughly handled. Its <a href="/facts/Sensitivity_(explosives)/NQb9DTPh">sensitivity</a> to exploding is responsible for numerous devastating industrial accidents throughout its history. The chemical's characteristic reactivity may be reduced through the addition of desensitizing agents, which makes it less likely to explode. Clay (<a href="/facts/Diatomaceous_earth/kQVwJICV">diatomaceous earth</a>) is an example of such an agent, forming dynamite, a much more easily handled composition. Addition of other desensitizing agents give birth to the various formulations of dynamite. 
Nitroglycerin has been used for over 130 years <a href="/facts/Glyceryl_trinitrate_(pharmacology)/nvR7lm8K">in medicine</a> as a potent <a href="/facts/Vasodilator/cjzrU8Ro">vasodilator</a> (causing dilation of the vascular system) to treat <a href="/facts/Heart/fF4KSGdk">heart</a> conditions, such as <a href="/facts/Angina_pectoris/rT1brdwS">angina pectoris</a> and <a href="/facts/Chronic_heart_failure/7fckX3Jm">chronic heart failure</a>. Though it was previously known that these beneficial effects are due to nitroglycerin being converted to <a href="/facts/Nitric_oxide/UvhdvDzp">nitric oxide</a>, a potent venodilator, the <a href="/facts/Enzyme/DSI1Fh7y">enzyme</a> for this conversion was only discovered to be mitochondrial <a href="/facts/Aldehyde_dehydrogenase/qNWTxjtR">aldehyde dehydrogenase</a> (<a href="/facts/ALDH2/nC0H4RfY">ALDH2</a>) in 2002. Nitroglycerin is available in <a href="/facts/Sublingual_tablet/dSzR1gYG">sublingual tablets</a>, sprays, ointments, and patches.

Nitroglycerin open-in-new

Nitroglycerin