nitroglycerin nitroglycerin nitroglycerin (ng), (alternative spelling of nitroglycerine) also known as trinitroglycerin (tng), nitro, glyceryl trinitrate (gtn), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions appropriate to the formation of the nitric acid ester. chemically, the substance is an organic nitrate compound rather than a nitro compound, but the traditional name is retained. invented in 1847 by ascanio sobrero, nitroglycerin has been used ever since as an active ingredient in the manufacture of explosives, namely dynamite, and as such it is employed in the construction, demolition, and mining industries. since the 1880s, it has been used by militaries as an active ingredient and gelatinizer for nitrocellulose in some solid propellants such as cordite and ballistite. it is a major component in double-based smokeless propellants used by reloaders. combined with nitrocellulose, hundreds of powder combinations are used by rifle, pistol, and shotgun reloaders. for the use of this chemical as a drug, see nitroglycerin (medication). nitroglycerin names preferred iupac name propane-1,2,3-triyl trinitrate other names 1,2,3-tris(nitrooxy)propane1,2,3-trinitroxypropaneglyceryl trinitrategtnnitrotngtrinitroglycerinalpha,alpha,alpha-trinitroglycerin identifiers cas number 55-63-0 y 3d model (jsmol) interactive image beilstein reference 1802063 chebi chebi:28787 y chembl chembl730 y chemspider 4354 y drugbank db00727 y echa infocard 100.000.219 ec number 200-240-8 gmelin reference 165859 iuphar/bps 7053 kegg d00515 y mesh nitroglycerin pubchem cid 4510 unii g59m7s0ws3 y un number 0143, 0144, 1204, 3064, 3319 comptox dashboard (epa) dtxsid1021407 inchi inchi=1s/c3h5n3o9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3h,1-2h2 ykey: sniopgdigtzgop-uhfffaoysa-n yinchi=1/c3h5n3o9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3h,1-2h2key: sniopgdigtzgop-uhfffaoyar smiles c(c(co(=o))o(=o))o(=o) properties chemical formula c3h5n3o9 molar mass 227.085 g·mol−1 appearance colorless liquid density 1.6 g⋅cm−3 (at 15 °c) melting point 14 °c (57 °f; 287 k) boiling point 50 °c (122 °f; 323 k) explodes solubility in water slightly solubility acetone, ether, benzene, alcohol log p 2.154 structure coordination geometry tetragonal at c1, c2, and c3trigonal planar at n7, n8, and n9 molecular shape tetrahedral at c1, c2, and c3dihedral at n7, n8, and n9 explosive data shock sensitivity high friction sensitivity high detonation velocity 7700 m⋅s−1 re factor 1.50 thermochemistry std enthalpy offormation (δfh⦵298) −370 kj⋅mol−1 std enthalpy ofcombustion (δch⦵298) −1.529 mj⋅mol−1 pharmacology atc code c01da02 (who) c05ae01 (who) routes ofadministration intravenous, by mouth, under the tongue, topical pharmacokinetics: bioavailability <1% metabolism liver biological half-life 3 min legal status au: s3 (pharmacist only) hazards occupational safety and health (ohs/osh): main hazards explosive, toxic ghs labelling: pictograms signal word danger hazard statements h202, h205, h241, h301, h311, h331, h370 precautionary statements p210, p243, p250, p260, p264, p270, p271, p280, p302+p352, p410 nfpa 704 (fire diamond) 3 2 4 niosh (us health exposure limits): pel (permissible) c 0.2 ppm (2 mg/m3) except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). y verify (what is yn ?) infobox references nitroglycerin has been used for over 130 years in medicine as a potent vasodilator (dilation of the vascular system) to treat heart conditions, such as angina pectoris and chronic heart failure. though it was previously known that these beneficial effects are due to nitroglycerin being converted to nitric oxide, a potent venodilator, the enzyme for this conversion was only discovered to be mitochondrial aldehyde dehydrogenase (aldh2) in 2002. nitroglycerin is available in sublingual tablets, sprays, ointments, and patches. history nitroglycerin was the first practical explosive produced that was stronger than black powder. it was first synthesized by the italian chemist ascanio sobrero in 1847, working under théophile-jules pelouze at the university of turin. sobrero initially called his discovery pyroglycerine and warned vigorously against its use as an explosive. nitroglycerin was later adopted as a commercially useful explosive by alfred nobel, who experimented with safer ways to handle the dangerous compound after his younger brother, emil oskar nobel, and several factory workers were killed in an explosion at the nobels' armaments factory in 1864 in heleneborg, sweden. alfred nobel's patent application from 1864 one year later, nobel founded alfred nobel and company in germany and built an isolated factory in the krümmel hills of geesthacht near hamburg. this business exported a liquid combination of nitroglycerin and gunpowder called "blasting oil", but this was extremely unstable and difficult to handle, as evidenced in numerous catastrophes. the buildings of the krümmel factory were destroyed twice. in april 1866, several crates of nitroglycerin were shipped to california, three of which were destined for the central pacific railroad, which planned to experiment with it as a blasting explosive to expedite the construction of the 1,659-foot-long (506 m) summit tunnel through the sierra nevada mountains. one of the remaining crates exploded, destroying a wells fargo company office in san francisco and killing 15 people. this led to a complete ban on the transportation of liquid nitroglycerin in california. the on-site manufacture of nitroglycerin was thus required for the remaining hard-rock drilling and blasting required for the completion of the first transcontinental railroad in north america. on christmas day 1867, an attempt to dispose of nine canisters of blasting oil that had been illegally stored at the white swan inn in the centre of newcastle upon tyne resulted in an explosion on the town moor that killed eight people. in june 1869, two one-ton wagons loaded with nitroglycerin, then known locally as powder-oil, exploded in the road at the north wales village of cwm-y-glo. the explosion led to the loss of six lives, many injuries and much damage to the village. little trace was found of the two horses. the uk government was so alarmed at the damage caused and what could have happened in a city location (these two tons were part of a larger load coming from germany via liverpool) that they soon passed the nitro-glycerine act of 1869. liquid nitroglycerin was widely banned elsewhere, as well, and these legal restrictions led to alfred nobel and his company's developing dynamite in 1867. this was made by mixing nitroglycerin with diatomaceous earth ("kieselguhr" in german) found in the krümmel hills. similar mixtures, such as "dualine" (1867), "lithofracteur" (1869), and "gelignite" (1875), were formed by mixing nitroglycerin with other inert absorbents, and many combinations were tried by other companies in attempts to get around nobel's tightly held patents for dynamite. dynamite mixtures containing nitrocellulose, which increases the viscosity of the mix, are commonly known as "gelatins". following the discovery that amyl nitrite helped alleviate chest pain, the physician william murrell experimented with the use of nitroglycerin to alleviate angina pectoris and to reduce the blood pressure. he began treating his patients with small diluted doses of nitroglycerin in 1878, and this treatment was soon adopted into widespread use after murrell published his results in the journal the lancet in 1879. a few months before his death in 1896, alfred nobel was prescribed nitroglycerin for this heart condition, writing to a friend: "isn't it the irony of fate that i have been prescribed nitro-glycerin, to be taken internally! they call it trinitrin, so as not to scare the chemist and the public." the medical establishment also used the name "glyceryl trinitrate" for the same reason. wartime production rates large quantities of nitroglycerin were manufactured during world war i and world war ii for use as military propellants and in military engineering work. during world war i, hm factory, gretna, the largest propellant factory in the united kingdom, produced about 800 tonnes of cordite rdb per week. this amount required at least 336 tonnes of nitroglycerin per week (assuming no losses in production). the royal navy had its own factory at the royal navy cordite factory, holton heath, in dorset, england. a large cordite factory was also built in canada during world war i. the canadian explosives limited cordite factory at nobel, ontario, was designed to produce 1,500,000 lb (680 t) of cordite per month, requiring about 286 tonnes of nitroglycerin per month. instability and desensitization in its undiluted form, nitroglycerin is a contact explosive, with physical shock causing it to explode. if it has not been adequately purified during manufacture it can degrade over time to even more unstable forms. this makes nitroglycerin highly dangerous to transport or use. in its undiluted form, it is one of the world's most powerful explosives, comparable to the more recently developed rdx and petn. early in its history, liquid nitroglycerin was found to be "desensitized" by freezing it at a temperature below 45 to 55 °f (7 to 13 °c) depending on its purity. its sensitivity to shock while frozen is somewhat unpredictable: "it is more insensitive to the shock from a fulminate cap or a rifle ball when in that condition but on the other hand it appears to be more liable to explode on breaking, crushing, tamping, etc." frozen nitroglycerine is much less energetic than liquid, and so must be thawed before use. thawing it out can be extremely sensitizing, especially if impurities are present or the warming is too rapid. ethylene glycol dinitrate or another polynitrate may be added to lower the melting point and thereby avoid the necessity of thawing frozen explosive. chemically "desensitizing" nitroglycerin is possible to a point where it can be considered about as "safe" as modern high explosives, such as by the addition of ethanol, acetone, or dinitrotoluene. the nitroglycerin may have to be extracted from the desensitizer chemical to restore its effectiveness before use, for example by adding water to draw off ethanol used as a desensitizer. detonation the detonation velocity of nitroglycerin is 7820 meters per second, which is about 113% the speed of tnt. accordingly, nitroglycerin is considered to be a high-brisance explosive, which is to say, it has excellent shattering ability. the heat liberated during detonation raises the temperature of the gaseous byproducts to about 5,000 °c (9,000 °f). with a standard enthalpy of explosive decomposition of −1414 kj/mol and a molecular weight of 227.0865 g/mol, nitroglycerin has a specific explosive energy density of 1.488 kilocalories per gram, or 6.23 kj/g, making nitroglycerin 49% more energetic on a mass basis than the standard definitional value assigned to tnt (precisely 1 kcal/g). manufacturing nitroglycerin can be produced by acid-catalyzed nitration of glycerol (glycerin). nitroglycerin synthesis: the industrial manufacturing process often reacts glycerol with a nearly 1:1 mixture of concentrated sulfuric acid and concentrated nitric acid. this can be produced by mixing white fuming nitric acid—a quite expensive pure nitric acid in which the oxides of nitrogen have been removed, as opposed to red fuming nitric acid, which contains nitrogen oxides—and concentrated sulfuric acid. more often, this mixture is attained by the cheaper method of mixing fuming sulfuric acid, also known as oleum—sulfuric acid containing excess sulfur trioxide—and azeotropic nitric acid (consisting of about 70% nitric acid, with the rest being water). the sulfuric acid produces protonated nitric acid species, which are attacked by glycerol's nucleophilic oxygen atoms. the nitro group is thus added as an ester c−o−no2 and water is produced. this is different from an electrophilic aromatic substitution reaction in which nitronium ions are the electrophile. the addition of glycerol results in an exothermic reaction (i.e., heat is produced), as usual for mixed-acid nitrations. if the mixture becomes too hot, it results in a runaway reaction, a state of accelerated nitration accompanied by the destructive oxidation of organic materials by the hot nitric acid and the release of poisonous nitrogen dioxide gas at high risk of an explosion. thus, the glycerin mixture is added slowly to the reaction vessel containing the mixed acid (not acid to glycerin). the nitrator is cooled with cold water or some other coolant mixture and maintained throughout the glycerin addition at about 22 °c (72 °f), hot enough for esterification to occur at a fast rate but cold enough to avoid runaway reaction. the nitrator vessel, often constructed of iron or lead and generally stirred with compressed air, has an emergency trap door at its base, which hangs over a large pool of very cold water and into which the whole reaction mixture (called the charge) can be dumped to prevent an explosion, a process referred to as drowning. if the temperature of the charge exceeds about 30 °c (86 °f) (actual value varying by country) or brown fumes are seen in the nitrator's vent, then it is immediately drowned. use as an explosive and a propellant the main use of nitroglycerin, by tonnage, is in explosives such as dynamite and