Nitroglycerin
21530
225564450
2008-07-14T09:45:18Z
Pyrotec
319310
/* Detonation */ clean up
{{dablink|This article is about the chemical properties of nitroglycerin and its use as an explosive. For medical and pharmacological applications, see [[Glyceryl trinitrate (pharmacology)]]''.}}
{{explosivebox |
|IUPAC_name = 1,2,3-trinitroxypropane<br/>1,3-dinitrooxypropan-2-yl nitrate<br/>propane-1,2,3-triyl trinitrate
|image=Nitroglycerin-2D-skeletal.png
|chemical_formula = C<sub>3</sub>H<sub>5</sub>(NO<sub>3</sub>)<sub>3</sub>
|molecular_weight = 227.0872 [[gram|g]]/[[mole (unit)|mol]]
|shock_sensitivity = high
|friction_sensitivity = high
|density = 1.6 [[gram|g]]/[[cubic centimeter|cm³]] at 15 [[Celsius|°C]]
|explosive_velocity = 7700 [[metre per second|m/s]]
|RE_factor = 1.50
|melting point = 13.2 °C (55.76 °F)
|boiling_point = Decomposes at 50 to 60 °C (122 to 140 °F)
|appearance = Clear yellow/colorless oily liquid
|CAS_number = 55-63-0
|UNNumber = [[List of UN Numbers 0101 to 0200|0143, 0144]], [[List of UN Numbers 1201 to 1300|1204]], [[List of UN Numbers 3001 to 3100|3064]]
|PubChem = 4510
|SMILES = C(C(CO[N+](=O)[O-])O<br>[N+](=O)[O-])O[N+](=O)[O-]
}}
'''Nitroglycerin''' ('''NG'''), ([[US]] spelling) also known as '''nitroglycerine''', ([[UK]] Spelling), '''trinitroglycerin''', '''trinitroglycerine''', '''1,2,3-trinitroxypropane''' and '''glyceryl trinitrate''', is a heavy, colorless, oily, explosive liquid obtained by [[nitration|nitrating]] [[glycerol]]. Since the 1860s, it has been used as an active ingredient in the manufacture of [[explosive]]s, specifically [[dynamite]], and as such is employed in the [[construction]] and [[demolition]] industries. Similarly, since the 1880s, it has been used by the military as an active ingredient, and a gellatinizer for [[nitrocellulose]], in some solid [[propellant]]s, such as [[Cordite]] and [[Ballistite]]. Nitroglycerin is also used [[Glyceryl trinitrate (pharmacology)|medically]] as a [[vasodilator]] to treat [[heart]] conditions, such as [[angina pectoris|angina]] and [[chronic heart failure]].
== History ==
Nitroglycerin was discovered by chemist [[Ascanio Sobrero]] in 1846, working under [[TJ Pelouze]] at the [[University of Turin]]. 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, as shown in numerous "appalling catastrophes," such as the explosion that destroyed a [[Wells Fargo]] office in [[San Francisco]] in 1866.
Liquid nitroglycerin was widely banned, and this led to the development of [[dynamite]] (and similar mixtures, such as [[blasting gelatine]], ''dualine'' and ''lithofracteur''), made by mixing the nitroglycerin with inert absorbents; for example, Nobel used ''[[kieselguhr]]''. Other nitrated materials, such as [[nitrocellulose|nitrocellulose gel]], were also used. Dynamites containing nitrocellulose, which increase the viscosity of the mix, are commonly known as "gelatins."
== Instability and desensitization ==
In its pure form, it is a [[contact explosive]] (physical shock can cause it to explode) 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 more powerful explosives, comparable to the more recently developed [[RDX]] and [[PETN]], as well as the [[plastic explosive]] [[C-4 (explosive)|C-4]]—which contains over 90% RDX as its active ingredient.
Early in the history of this explosive it was discovered that liquid nitroglycerin can be "desensitized" by cooling to 5 to 10 [[Celsius|°C]] (40 to 50 [[Fahrenheit|°F]]), at which temperature it freezes, contracting upon solidification. However, later thawing can be extremely sensitizing, especially if impurities are present or if warming is too rapid. It is possible to chemically "desensitize" nitroglycerin to a point where it can be considered approximately as "safe" as modern [[Explosive material|high explosive]] formulations, by the addition of approximately 10-30% [[ethanol]], [[acetone]], or [[dinitrotoluene]] (percentage varies with the desensitizing agent used). Desensitization requires extra effort to reconstitute the "pure" product. Failing this, it must be assumed that desensitized nitroglycerin is substantially more difficult to detonate, possibly rendering it useless as an explosive for practical application.
A serious problem in the use of nitroglycerin results from its high freezing point 13 [[Celsius|°C]] (55 [[Fahrenheit|°F]]). Solid nitroglycerin is much less sensitive to shock than the liquid, a feature common in explosives; in the past it was often shipped in the frozen state, but this resulted in a high number of accidents during the thawing process by the end user just prior to use. This disadvantage is overcome by using mixtures of nitroglycerin with other polynitrates; for example, a mixture of nitroglycerin and [[ethylene glycol dinitrate]] freezes at -29 [[Celsius|°C]] (-20 [[Fahrenheit|°F]]).<ref name="fn_1">{{cite web|url=http://www.britannica.com/nobel/micro/426_77.html | work=Britannica | title=nitroglycerin | accessmonthday=23 March | accessyear=2005 }}</ref>
== Detonation ==
Nitroglycerin and all of the dilutents used can certainly [[deflagration|deflagrate]] or burn. However, the explosive power of nitroglycerin is derived from [[detonation]]: energy from the initial decomposition causes a pressure gradient that detonates the surrounding fuel. This can generate a self-sustained shock-wave that propagates through the fuel-rich medium at or above the [[speed of sound]] as a cascade of near-instantaneous pressure-induced decomposition of the fuel into gas. This is quite unlike deflagration, which depends solely upon available fuel, regardless of pressure or shock.
== Manufacturing ==
The industrial manufacturing process often uses a nearly 50:50 mixture of [[sulfuric acid]] and [[nitric acid]]. This can be produced by mixing white fuming nitric acid (quite costly pure nitric acid in which oxides of nitrogen have been removed, as opposed to red fuming nitric acid) 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 around 70% nitric acid, the rest being water).
The sulfuric acid produces protonated nitric acid species, which are attacked by glycerin's [[Nucleophile|nucleophilic]] [[oxygen]] atoms. The [[nitro]] [[functional group|group]] is thus added as an ester C-O-NO<sub>2</sub> and water is produced. This is different from an aromatic nitration reaction in which [[nitronium ion]]s are the active species in an electrophilic attack of the molecules' ring system.
The addition of glycerin results in an [[chemical reaction|exothermic reaction]] (i.e., heat is produced), as usual for mixed acid nitrations. However, if the mixture becomes too hot, it results in runaway, a state of accelerated nitration accompanied by the destructive oxidizing of organic materials of nitric acid and the release of very poisonous brown [[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, much below which the esterification occurs too slowly to be useful. 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 10 °C (actual value varying by country) or brown fumes are seen in the nitrators vent, then it is immediately drowned.
== Use as an explosive and a propellant ==
{{Main|Dynamite|Ballistite|Cordite|smokeless powder|Gelignite}}
[[Image:Nobel patent.jpg|thumb|150px|[[Alfred Nobel]]'s [[patent application]] from [[1864]].]]
The main use of nitroglycerin, by tonnage, is in explosives such as dynamite and in propellants.
[[Alfred Nobel]] developed the use of nitroglycerin as a blasting explosive by mixing the nitroglycerine with inert [[chemistry|absorbents]] particularly [[kieselgur]]. He named this explosive [[dynamite]] and [[patented]] it in 1867. It was supplied ready for use in the form of ''sticks'', individually wrapped in grease proof paper. Dynamite and similar explosives were widely adopted for civil engineering tasks, such as building railway tunnels and cuttings; and for quarrying.
Nitroglycerin was also adapted as a military propellant, for use in guns and rifles. [[Poudre B]], invented in [[France]] in 1886, was one of the first military propellants to replace [[gunpowder]]; but it was based on nitrocellulose, not nitroglycerin. It was later found to be unstable.
Alfred Nobel then developed [[ballistite]], by combining nitroglycerin and [[guncotton]]. He patented it in 1887. Ballistite was adopted by a number of European governments, as a military propellant. [[Italy]] was the first to adopt it. However, it was not adopted by the British Government. They, together with the British Commonwealth countries, adopted [[cordite]], which had been developed by Sir [[Frederick Abel]] and [[Sir James Dewar]], in 1889. The original Cordite Mk I consisted of 58% nitroglycerine, 37% guncotton and 5% [[petroleum jelly]]. Ballistite and cordite were both manufactured in the forms of ''cords''.
[[Smokeless powder]]s were originally developed using nitrocellulose as the sole explosive ingredient; and were therefore known as ''single base'' propellants. A range of smokeless powders that contain both nitrocellulose and nitroglycerin, known as ''double base'' propellants, were also developed. Smokeless powders were originally supplied only for military use; however they were also soon developed for civilian use and were quickly adopted for sport. Some are known as sporting powders.
'''Blasting gelatin''', also known as [[gelignite]], was invented by Nobel in 1875, using nitroglycerine, wood pulp, and sodium or potassium nitrates. This was an early low-cost, flexible explosive.
== War time production rates ==
Large quantities of nitroglycerin were manufactured in both World Wars for use in military propellants.
=== World War I ===
In [[World War I]] [[HM Factory, Gretna]], the largest propellant factory in the United Kingdom was producing 800 [[ton]]s (812 [[tonne]]) of Cordite RDB per week. This required 336 tons of nitroglycerin per week (assuming no losses in production). The [[Royal Navy]] had its own factory at [[Royal Navy Cordite Factory, Holton Heath]].
A large cordite factory was also built in [[Canada]] in World War I. The [[Canadian Industries Limited|Canadian Explosives Limited]] Cordite factory at [[Nobel, Ontario]] was designed to produce 1,500,000 lb (681 tonne) of Cordite per month. It required 286 tonnes of nitroglycerin per month.
== Medical implications ==<!-- This section is linked from [[Emergency medical technician]] -->
{{main|Glyceryl trinitrate (pharmacology)}}
=== Medical use ===
Nitroglycerin in [[medicine]], where it is generally called glyceryl trinitrate, is used as a [[heart]] medication (under the trade names '''Nitrospan''', '''Nitrostat''', and '''Tridil''', amongst others). It is used as a medicine for [[angina pectoris]] ([[coronary heart disease|ischaemic heart disease]]) in tablets, ointment, solution for intravenous use, transdermal patches ('''Transderm Nitro''', '''Nitro-Dur'''), or sprays administered [[sublingual]]ly ('''Nitrolingual Pump Spray''', '''Natispray''').
The principal action of nitroglycerin is [[vasodilation]]—widening of the [[blood vessel]]s. Nitroglycerin will dilate veins more than arteries, decreasing cardiac preload and leading to the following therapeutic effects during episodes of [[angina pectoris]]:
* subsiding of chest pain
* decrease of [[blood pressure]]
* increase of heart rate.
* [[orthostatic hypotension]]
These effects arise because nitroglycerin is converted to [[nitric oxide]] in the body (by a mechanism that is not completely understood), and nitric oxide is a natural vasodilator. Recently, it has also become popular in an [[off-label]] use at reduced (0.2%) concentration in ointment form as an effective treatment for [[anal fissure]].
=== Industrial exposure ===
Infrequent exposure to high doses of nitroglycerin can cause severe headaches known as "NG head". These headaches can be severe enough to incapacitate some people; however, humans develop a tolerance and dependence to nitroglycerin after long-term exposure. Withdrawal can (rarely) be fatal; withdrawal symptoms include headaches and heart problems; with re-exposure to nitroglycerin, these symptoms may disappear.
For workers in nitroglycerin (NTG) manufacturing facilities, this can result in a "Monday morning headache" phenomenon for those who experience regular nitroglycerin exposure in the workplace leading to the development of NTG tolerance for the vasodilating effects. Over the weekend the workers lose the tolerance to NTG and when they are reexposed on Monday the prominent [[vasodilation]] produces [[tachycardia]], dizziness, and a headache.
== References ==
* {{cite web|url=http://CPRR.org/Museum/Newspapers/Nitroglycerine.html | work=Central Pacific Railroad Photographic History Museum | title=Nitroglycerine! Terrible Explosion and Loss of Lives in San Francisco | accessmonthday=23 March | accessyear=2005 }} - 1866 Newspaper article
<references />
== See also ==
* [[Mannitol hexanitrate]]
* [[Xylitol pentanitrate]]
* [[Erythritol tetranitrate]]
* [[Nitroglycerine|Nitroglycerine, most properly Gycerol trinitrate]]
* [[Ethylene glycol dinitrate]]
* [[Nitromethane]]
==External links==
* [http://webbook.nist.gov/cgi/cbook.cgi?ID=C55630 WebBook page for C3H5N3O9]
* [http://www.compchemwiki.org/index.php?title=Nitroglycerin Computational Chemistry Wiki]
* [http://www.logwell.com/tales/menu/index.html The Tallini Tales of Destruction] Detailed and horrific stories of the historical use of nitroglycerin-filled torpedoes to restart petroleum wells.
[[Category:Alkyl nitrates]]
[[Category:Antianginals]]
[[Category:Explosive chemicals]]
[[Category:Liquid explosives]]
[[Category:Sugar alcohol explosives]]
[[ar:نيتروغليسرين]]
[[bs:Nitroglicerin]]
[[bg:Нитроглицерин]]
[[ca:Nitroglicerina]]
[[cs:Nitroglycerin]]
[[da:Nitroglycerin]]
[[de:Glycerintrinitrat]]
[[es:Nitroglicerina]]
[[eo:Nitroglicerino]]
[[fr:Nitroglycérine]]
[[gl:Nitroglicerina]]
[[ko:나이트로글리세린]]
[[hr:Nitroglicerin]]
[[id:Nitrogliserin]]
[[it:Nitroglicerina]]
[[he:ניטרוגליצרין]]
[[lv:Nitroglicerīns]]
[[lt:Nitroglicerinas]]
[[hu:Glicerin-trinitrát]]
[[nl:Nitroglycerine]]
[[ja:ニトログリセリン]]
[[no:Nitroglyserin]]
[[km:នីត្រូគ្លីសេរីន]]
[[pl:Nitrogliceryna]]
[[pt:Nitroglicerina]]
[[ro:Nitroglicerină]]
[[ru:Нитроглицерин]]
[[sk:Nitroglycerín]]
[[sl:Nitroglicerin]]
[[fi:Nitroglyseroli]]
[[sv:Nitroglycerin]]
[[th:ไนโตรกลีเซอรีน]]
[[vi:Nitroglycerin]]
[[tr:Nitrogliserin]]
[[uk:Нітрогліцерин]]
[[zh:硝酸甘油]]