Editing Nitroglycerin

{{For|the use of this chemical as a drug|Nitroglycerin (medication)}}
{{short description|Chemical compound}}
{{Chembox
| Watchedfields  = changed
| verifiedrevid  = 408765228
| Name           = Nitroglycerin
| ImageFile      = 
| ImageFile1     = Nitroglycerin.svg
| ImageFile1_Ref = {{Chemboximage|correct|??}}
| ImageName1     = Skeletal formula of zwitterionic nitroglycerin
| ImageFile2     = Nirtoglycerin_3D_BallStick.png
| ImageFile2_Ref = {{Chemboximage|correct|??}}
| ImageName2     = Ball and stick model of nitroglycerin
| ImageFile3     = Nitroglycerin-3D-vdW.png
| ImageFile3_Ref = {{Chemboximage|correct|??}}
| ImageName3     = Spacefill model of nitroglycerin
| PIN            = Propane-1,2,3-triyl trinitrate
| SystematicName = 
| OtherNames     = {{ubl|1,2,3-Tris(nitrooxy)propane|1,2,3-Trinitroxypropane|Glyceryl trinitrate|GTN|Nitro|TNG|Trinitroglycerin|''alpha'',''alpha'',''alpha''-Trinitroglycerin}}
| IUPACName      = 
| Section1       = {{Chembox Identifiers
 | IUPHAR_ligand = 7053
 | CASNo = 55-63-0
 | CASNo_Ref = {{cascite|correct|CAS}}
 | PubChem = 4510
 | ChemSpiderID = 4354
 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
 | UNII = G59M7S0WS3
 | UNII_Ref = {{fdacite|correct|FDA}}
 | EINECS = 200-240-8
 | UNNumber = 0143, 0144, 1204, 3064, 3319
 | DrugBank_Ref = {{drugbankcite|correct|drugbank}}
 | DrugBank = DB00727
 | KEGG = D00515
 | KEGG_Ref = {{keggcite|correct|kegg}}
 | MeSHName = Nitroglycerin
 | ChEBI_Ref = {{ebicite|correct|EBI}}
 | ChEBI = 28787
 | ChEMBL = 730
 | ChEMBL_Ref = {{ebicite|correct|EBI}}
 | Beilstein = 1802063
 | Gmelin = 165859
 | SMILES = C(C(CO[N+](=O)[O-])O[N+](=O)[O-])O[N+](=O)[O-]
 | StdInChI = 1S/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2
 | StdInChI_Ref = {{stdinchicite|correct|chemspider}}
 | InChI = 1/C3H5N3O9/c7-4(8)13-1-3(15-6(11)12)2-14-5(9)10/h3H,1-2H2
 | StdInChIKey = SNIOPGDIGTZGOP-UHFFFAOYSA-N
 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
 | InChIKey = SNIOPGDIGTZGOP-UHFFFAOYAR
 }}
| Section2       = {{Chembox Properties
 | C=3 | H=5 | N=3 | O=9
 | Appearance = Colorless or pale yellow, oily liquid or tetraclinic/orthorhombic crystal
 | Density = 1.5931 g/cm<sup>−3</sup>
 | MeltingPtC = 12.8
 | BoilingPtC = 218
 | BoilingPt_notes = Explodes
 | LogP = 2.154
 | Solubility = Slightly<ref name="osha.gov">{{Cite web |url=https://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |title=Occupational Safety and Health Guideline for Nitroglycerin  |access-date=19 October 2016 |archive-url=https://web.archive.org/web/20130516192244/http://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |archive-date=16 May 2013 |url-status=dead |df=dmy-all }}</ref>
 | Solvent =
 | SolubleOther = [[acetone]], [[diethyl ether]], [[benzene]], [[toluene]], [[ethanol]]<ref name="osha.gov"/>
 }}
| Section3       = {{Chembox Structure
 | Coordination = {{ubl
  | Tetragonal at C1, C2, and C3
  | Trigonal planar at N7, N8, and N9
  }}
 | MolShape = {{ubl
  | Tetrahedral at C1, C2, and C3
  | Dihedral at N7, N8, and N9
  }}
 }}
| Section4       = {{Chembox Explosive
 | ShockSens = High
 | FrictionSens = High
 | DetonationV = 7,820{{nbsp}}m/s
 | REFactor = 1.50
 }}
| Section5       = {{Chembox Thermochemistry
 | DeltaHf = −370{{nbsp}}kJ⋅mol<sup>−1</sup>
 | DeltaHc = −1.529{{nbsp}}MJ⋅mol<sup>−1</sup>
 }}
| Section6       = {{Chembox Pharmacology
 | ATCCode_prefix = C01
 | ATCCode_suffix = DA02
 | ATC_Supplemental = {{ATC|C05|AE01}}
 | Bioavail = <1%
 | AdminRoutes = Intravenous, by mouth, under the tongue, topical
 | Metabolism = Liver
 | HalfLife = 3{{nbsp}}min
 | Legal_AU = S3
 | Legal_AU_comment =
 }}
| Section7       = {{Chembox Hazards
 | GHSPictograms = {{GHS02}} {{GHS06}} {{GHS08}} {{GHS01}}
 | GHSSignalWord = '''Danger'''
 | HPhrases = {{H-phrases|202|205|241|301|311|331|370}}
 | PPhrases = {{P-phrases|210|243|250|260|264|270|271|280|302+352|410}}
 | NFPA-H = 3
 | NFPA-F = 2
 | NFPA-R = 4
 | PEL = C 0.2{{nbsp}}ppm (2{{nbsp}}mg/m<sup>3</sup>) [skin]<ref>{{PGCH|0456}}</ref>
 | MainHazards = Explosive, toxic
 }}<ref>{{cite web|url=http://www.ehs.neu.edu/laboratory_safety/general_information/nfpa_hazard_rating/documents/NFPAratingJR.htm|title=Hazard Rating Information for NFPA Fire Diamonds|url-status=dead|archive-url=https://web.archive.org/web/20150217114741/http://www.ehs.neu.edu/laboratory_safety/general_information/nfpa_hazard_rating/documents/NFPAratingJR.htm|archive-date=17 February 2015|df=dmy-all}}</ref>
}}

'''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 [[nitration|nitrating]] [[glycerol]] with [[white fuming nitric acid]] under conditions appropriate to the formation of the nitric acid [[ester]]. Chemically, the substance is a [[nitrate ester]] rather than a [[nitro compound]], but the traditional name is retained. Discovered in 1846 by [[Ascanio Sobrero]],<ref>{{Cite web |title=Ascanio Sobrero |url=https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100514852 |access-date=2024-07-16 |website=Oxford Reference |language=en }}</ref> nitroglycerin has been used as an active ingredient in the manufacture of explosives, namely [[dynamite]], and as such it is employed in the [[construction]], [[demolition]], and [[mining]] industries. It is combined with [[nitrocellulose]] to form double-based [[smokeless powder]], used as a [[propellant]] 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. [[Decomposition|spontaneous decomposition]]) as the temperature is increased.  Upon exposure to heat above 218 °C at sea-level [[Standard atmosphere (unit)|atmospheric pressure]], nitroglycerin becomes extremely unstable and tends to explode. When placed in vacuum, it has an [[Autoignition temperature|autoignition]] temperature of 270 °C instead.<ref name=":0">{{Cite web |date=2013-05-16 |title=Occupational Safety and Health Guideline for Nitroglycerin |url=http://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |access-date=2024-07-09 |archive-url=https://web.archive.org/web/20130516192244/http://www.osha.gov/SLTC/healthguidelines/nitroglycerin/recognition.html |archive-date=16 May 2013 }}</ref> 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.<ref name=":0" /><ref>{{Cite book |last=Haynes |first=W. M. |title=CRC Handbook of Chemistry and Physics |publisher=CRC Press |edition=97th |pages=3–540}}</ref> Although the pure compound itself is colorless, in practice the presence of [[NOx|nitric oxide]] 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),<ref name=":0" /> 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.<ref>{{Cite web |title=Nitroglycerin, desensitized, liquid |url=https://cameochemicals.noaa.gov/chemical/12100 |url-status=live |archive-url=https://web.archive.org/web/20230826040417/https://cameochemicals.noaa.gov/chemical/12100 |archive-date=August 26, 2023 |access-date=July 9, 2024 |website=CAMEO Chemicals {{!}} NOAA}}</ref> Its [[Sensitivity (explosives)|sensitivity]] 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 ([[diatomaceous earth]]) 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 [[glyceryl trinitrate (pharmacology)|in medicine]] as a potent [[vasodilator]] (causing 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.<ref name="Chen et al. 2005 12159–12164">{{cite journal | journal = Proceedings of the National Academy of Sciences | year = 2005 | volume = 102 | pages = 12159–12164 | doi = 10.1073/pnas.0503723102 | pmid = 16103363 | last2 = Foster | first2 = M. W. | last3 = Zhang | first3 = J. | last4 = Mao | first4 = L. | last5 = Rockman | first5 = H. A. | last6 = Kawamoto | first6 = T. | last7 = Kitagawa | first7 = K. | last8 = Nakayama | first8 = K. I. | last9 = Hess | first9 = D. T. | last10 = Stamler | first10 = J. S. | title = An essential role for mitochondrial aldehyde dehydrogenase in nitroglycerin bioactivation | issue = 34 | pmc = 1189320 | last1 = Chen |first1=Z.| bibcode = 2005PNAS..10212159C | doi-access = free }}</ref> Nitroglycerin is available in [[sublingual tablet]]s, sprays, ointments, and patches.<ref>{{Cite web |url=http://web.ebscohost.com/src/detail?vid=17&hid=7&sid=7e55c0c3-4b92-4b24-ac2d-b2091791a502@sessionmgr14&bdata=JnNpdGU9c3JjLWxpdmU= |title=Unknown, behind paywall, archived |access-date=14 April 2018 |archive-url=https://web.archive.org/web/20170510141029/http://web.ebscohost.com/src/detail?vid=17&hid=7&sid=7e55c0c3-4b92-4b24-ac2d-b2091791a502%40sessionmgr14&bdata=JnNpdGU9c3JjLWxpdmU%3d#db=hxh&AN=9703191987 |archive-date=10 May 2017 |url-status=dead |df=dmy-all }}</ref>

== History ==
Nitroglycerin was the first practical explosive produced that was stronger than [[black powder]]. It was synthesized by the Italian [[chemist]] [[Ascanio Sobrero]] in 1846, working under [[Théophile-Jules Pelouze]] at the [[University of Turin]].<ref>{{cite journal|last=Sobrero |first=Ascagne |date=1847 |url=http://gallica.bnf.fr/ark:/12148/bpt6k29812/f247.item.zoom |title=Sur plusieur composés détonants produits avec l'acide nitrique et le sucre, la dextrine, la lactine, la mannite et la glycérine |trans-title=On several detonating compounds produced with nitric acid and sugar, dextrin, lactose, mannitol, and glycerin |journal=Comptes Rendus |volume=24 |pages=247–248}}</ref> Sobrero initially called his discovery ''"pyroglycerin"'' and warned vigorously against its use as an explosive.<ref>{{cite journal|last=Sobrero |first=Ascanio |date=1849 |url=https://babel.hathitrust.org/cgi/pt?id=iau.31858045931643;view=1up;seq=283 |title=Sopra alcuni nuovi composti fulminanti ottenuti col mezzo dell'azione dell'acido nitrico sulle sostante organiche vegetali |trans-title=On some new explosive products obtained by the action of nitric acid on some vegetable organic substances |journal=Memorie della Reale Accademia delle Scienze di Torino |series=2nd Series |volume=10 |pages=195–201}} On p. 197, Sobrero names nitroglycerin "pyroglycerine":
:"Quelle gocciole costituiscono il corpo nuovo di cui descriverò ora le proprietà, e che chiamerò ''Piroglicerina''."  (Those drops constitute the new substance whose properties I will now describe, and which I will call "pyroglycerine".)</ref>

Nitroglycerin was 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.<ref>{{cite web |url=http://nobelprize.org/alfred_nobel/industrial/articles/vinterviken/emil.html |website=NobelPrize.org |title=Emil Nobel |access-date=6 October 2008 |archive-url=https://web.archive.org/web/20090115085417/http://nobelprize.org/alfred_nobel/industrial/articles/vinterviken/emil.html |archive-date=15 January 2009 |url-status=dead |df=dmy-all }}</ref>

{{stack|[[File:Nobel patent.jpg|thumb|upright|[[Alfred Nobel]]'s [[patent application]] from 1864]]}}

One year later, Nobel founded [[Dynamit Nobel AG|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.<ref name="The Manufacture of High Explosives">{{cite web |last1=Ramsay |first1=Sir William |title=The Manufacture of High Explosives |url=https://www.scientificamerican.com/article/the-manufacture-of-high-explosives/ |website=Scientific American |date=28 December 1907 |publisher=Springer Nature |access-date=4 March 2024 |ref=Explains the context and process of the manufacturing of NG at Nobel's factories}}</ref> The buildings of the Krümmel factory were destroyed twice.<ref>{{cite web|url=http://nobelprize.org/alfred_nobel/industrial/articles/krummel/index.html |website=NobelPrize.org |title=Krümmel |url-status=dead |archive-url=https://web.archive.org/web/20060710005656/http://nobelprize.org/alfred_nobel/industrial/articles/krummel/index.html |archive-date=10 July 2006 }}.</ref>

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 {{convert|1659|ft|m|adj=mid|-long}} [[Donner Pass#Railroad & Donner Pass|Summit Tunnel]] through the [[Sierra Nevada (U.S.)|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.<ref>{{cite web|url=https://www.pbs.org/wgbh/amex/tcrr/peopleevents/e_nitro.html |title=Transcontinental Railroad – People & Events: Nitroglycerin |website=[[American Experience]] |publisher=[[Public Broadcasting Service|PBS]]}}</ref>

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.<ref>North Wales Daily Post newspaper of October 14th 2018.</ref> 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 (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 Lancet]]'' in 1879.<ref>{{cite journal|last=Murrell |first=William |date=1879 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.d0000772988;view=1up;seq=78 |title=Nitroglycerin as a remedy for angina pectoris |journal=The Lancet |volume=1 |issue=2890 |pages=80–81, 113–115, 151–152, 225–227|doi=10.1016/s0140-6736(02)46032-1 |pmc=5901592 }}</ref><ref name="ReferenceA">{{cite book|last=Sneader |first=Walter |title=Drug Discovery: A History |publisher=John Wiley and Sons |date=2005 |isbn=978-0-471-89980-8}}</ref> 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."<ref>{{cite web|url=http://www.beyonddiscovery.org/content/view.txt.asp?a=318|title=History of TNG|website=beyonddiscovery.org|access-date=14 April 2018|archive-url=https://web.archive.org/web/20101101191907/http://www.beyonddiscovery.org/content/view.txt.asp?a=318|archive-date=1 November 2010|url-status=dead}}</ref> 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 [[tonne]]s of [[Cordite#Cordite RDB|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 Industries Limited|Canadian Explosives Limited]] cordite factory at [[Nobel, Ontario]], was designed to produce {{convert|1500000|lb|t|abbr=on}} of cordite per month, requiring about 286 tonnes of nitroglycerin per month.

== Instability and desensitization ==
In its undiluted form, nitroglycerin is a [[contact explosive]], meaning physical shock causes 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  "[[Phlegmatized|desensitized]]" by freezing it at a temperature below {{Convert|45|to|55|F|C}} depending on its purity.<ref name="Tallini5">{{Cite web |title=Is Nitroglycerine In This? Page 5 |url=https://www.logwell.com/tales/frozen_nitroglycerin.html |access-date=2024-02-20 |website=www.logwell.com}}</ref> Its sensitivity to shock while frozen is somewhat unpredictable: "It is more insensitive to the shock from a [[Detonator|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."<ref name="LSMI1">{{cite journal |url=https://www.michigan.gov/documents/deq/GIMDL-LSMI1911B_301826_7.pdf |title=Accidents in the Transportation, Storage, and Use of Explosives |first=Charles S. |last=Hurter |date=August 22, 1911 |volume=16 |journal=Proceedings of the Lake Superior Mining Institute |page=70}}</ref> Frozen nitroglycerin is much less energetic than liquid, and so must be thawed before use.<ref name="LSMI2">{{cite journal |url=https://www.michigan.gov/documents/deq/GIMDL-LSMI1911C_301829_7.pdf |title=Accidents in the Transportation, Storage, and Use of Explosives |first=Charles S. |last=Hurter |date=August 22, 1911 |volume=16 |journal=Proceedings of the Lake Superior Mining Institute |page=71}}</ref> Thawing it out can be extremely sensitizing, especially if impurities are present or the warming is too rapid.<ref name="Tallini4">{{cite web |last=Tallini |first=Rick F. |title=Tales of Destruction...Thawing Can Be Hell |url=http://www.logwell.com/tales/second_nitro_death.html |website=Analog |series= |publisher=Analog Services, Inc.}}</ref> [[Ethylene glycol dinitrate]] or another polynitrate may be added to lower the melting point and thereby avoid the necessity of thawing frozen explosive.<ref name="fn_1">{{cite encyclopedia|url=https://www.britannica.com/nobel/micro/426_77.html | encyclopedia=Encyclopaedia Britannica | title=Nitroglycerin | access-date=2005-03-23 |archive-url=https://web.archive.org/web/20020912025024/https://www.britannica.com/nobel/micro/426_77.html |archive-date=2002-09-12 }}</ref>

Chemically "desensitizing" nitroglycerin is possible to a point where it can be considered about as "safe" as modern [[high explosive]]s, such as by the addition of [[ethanol]], [[acetone]], or [[dinitrotoluene]].<ref name="Tallini12">{{cite web |last=Tallini |first=Rick F. |title=Tales of Destruction...Is Nitroglycerin In This? |url=http://www.logwell.com/tales/red_glycerin.html |series= |publisher=Analog Services, Inc.}}</ref> 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.<ref name="Tallini12"/>

== Detonation ==
When nitroglycerin explodes, the products after cooling are given by:
:4{{chem2|C3H5N3O9}} → 12{{CHEM2|CO2}} + 10{{CHEM2|H2O}} + 6{{CHEM2|N2}} + {{CHEM2|O2}}

The heat released can be calculated from the heats of formation. Using &minus;371&nbsp;kJ/[[Mole (unit)|mol]] for the heat of formation of condensed phase nitroglycerin<ref>{{Cite web |last=Informatics |first=NIST Office of Data and |title=Nitroglycerin |url=https://webbook.nist.gov/cgi/cbook.cgi?ID=C55630&Units=SI&Mask=FFF |access-date=2024-02-20 |website=webbook.nist.gov |language=en}}</ref> gives 1414&nbsp;kJ/mol released if forming water vapor, and 1524 if forming liquid water.

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 {{convert|5000|C|F|-3}}.<ref name="fn_1"/> With a standard enthalpy of explosive decomposition of &minus;1414&nbsp;kJ/[[Mole (unit)|mol]] and a molecular weight of 227.0865&nbsp;g/mol, nitroglycerin has a specific explosive energy density of 1.488&nbsp;[[Calorie|kilocalories]] per gram, or 6.23&nbsp;kJ/g, making nitroglycerin 49% more energetic on a mass basis than the standard definitional value assigned to TNT (precisely 1&nbsp;kcal/g).

== Manufacturing ==
{{More citations needed|date=August 2024}}
[[File:Nitroglycerin Synthesis V.1.svg|thumb|upright=1.5|Nitroglycerin synthesis<ref>{{Cite journal|doi = 10.1002/jlac.18480640364|title = Zusammensetzung der Zuckerasche|trans-title=Composition of sugar ash|journal = Annalen der Chemie und Pharmacie|volume = 64|issue = 3|pages = 398–399|year = 1848}}</ref><ref>{{Cite journal|doi = 10.1002/jlac.18540920309|title = Ueber Nitroglycerin|journal = Annalen der Chemie und Pharmacie|volume = 92|issue = 3|pages = 305–306|year = 1854}}</ref><ref>{{Cite journal|doi = 10.3109/03602537508993747|pmid = 812687|title = Nitroglycerin Revisited: Chemistry, Biochemistry, Interactions|journal = Drug Metabolism Reviews|volume = 4|issue = 1|pages = 1–38|year = 1975|last1 = Di Carlo|first1 = F. J. }}</ref>]]

Nitroglycerin can be produced by acid-catalyzed nitration of [[glycerol]] (glycerin).<ref>{{cite book |last1=Lewis |first1=Richard J., Sr |title=Hawley's Condensed Chemical Dictionary |date=15 March 2007 |publisher=John Wiley & Sons, Inc |location=United States |isbn=978-0-471-76865-4 |page=897 |edition=15th}}</ref>

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).<ref>{{Cite book |last=Wexler |first=Philip |title=Encyclopedia of Toxicology |date=April 7, 2014 |publisher=Academic Press |isbn=978-0123864543 |edition=3rd |location=USA |pages=569 |language=en |trans-title=}}</ref>

The [[sulfuric acid]] produces [[protonated]] [[nitric acid]] species, which are attacked by [[glycerol]]'s [[nucleophile|nucleophilic]] [[oxygen]] atoms. The [[nitro compound|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 electrophilic aromatic substitution reaction in which [[nitronium ion]]s are the [[electrophile]].

The addition of [[glycerol]] results in an [[chemical reaction|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 {{convert|22|C|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 {{convert|30|C|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 ==
{{Main|Dynamite|Ballistite|Cordite|smokeless powder|Gelignite}}
Nitroglycerin is an oily liquid that explodes when subjected to heat, shock, or flame. The main use of nitroglycerin, by [[tonnage]], is in explosives such as dynamite and in propellants as an ingredient. However, its sensitivity has limited the usefulness of nitroglycerin as a military explosive; less sensitive explosives such as [[TNT]], [[RDX]], and [[HMX]] have largely replaced it in munitions.

[[Alfred Nobel]] developed the use of nitroglycerin as a blasting explosive by mixing nitroglycerin with inert [[Absorption (chemistry)|absorbent]]s, particularly "''Kieselgur''", or [[diatomaceous earth]]. He named this explosive dynamite and [[patented]] it in 1867.<ref>{{cite news|url=http://inventors.about.com/od/dstartinventions/a/Alfred_Nobel.htm|title=Alfred Nobel and the History of Dynamite|first=Mary|last=Bellis|work=About.com Money|access-date=10 November 2009|archive-date=28 August 2021|archive-url=https://web.archive.org/web/20210828185843/https://www.thoughtco.com/history-of-dynamite-1991564|url-status=dead}}</ref> It was supplied ready for use in the form of sticks, individually wrapped in greased waterproof paper. Dynamite and similar explosives were widely adopted for [[civil engineering]] tasks, such as in drilling [[highway]] and [[railroad]] [[tunnel]]s, for [[mining]], for clearing farmland of stumps, in [[quarrying]], and in [[demolition|demolition work]]. Likewise, [[military engineer]]s have used dynamite for construction and demolition work.

Nitroglycerin has been used in conjunction with [[hydraulic fracturing]], a process used to recover [[crude oil|oil]] and [[natural gas|gas]] from [[shale]] formations. The technique involves displacing and detonating nitroglycerin in natural or hydraulically induced fracture systems, or displacing and detonating nitroglycerin in hydraulically induced fractures followed by wellbore shots using pelletized [[trinitrotoluene|TNT]].<ref name="recovery">{{cite journal|last1=Miller|first1=J. S.|last2=Johansen|first2=R. T.|date=1976|title=Fracturing Oil Shale with Explosives for In Situ Recovery.|journal=Shale Oil, Tar Sand and Related Fuel Sources|pages=151|bibcode=1976sots.rept...98M|url=https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/19_2_LOS%20ANGELES_04-74__0060.pdf|access-date=27 March 2015|archive-date=2 October 2018|archive-url=https://web.archive.org/web/20181002204137/https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/19_2_LOS%20ANGELES_04-74__0060.pdf|url-status=dead}}</ref>

Nitroglycerin has an advantage over some other high explosives that on detonation it produces practically no visible smoke. Therefore, it is useful as an ingredient in the formulation of various kinds of [[smokeless powder]].<ref>{{cite web|url=http://www.ch.ic.ac.uk/rzepa/mim/environmental/html/nitroglyc_text.htm|title=Nitroglycerin}}</ref>

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. The British government and the Commonwealth governments adopted [[cordite]] instead, which had been developed by Sir [[Frederick Abel]] and Sir [[James Dewar]] of the United Kingdom in 1889. The original Cordite Mk&nbsp;I consisted of 58% nitroglycerin, 37% guncotton, and 5.0% [[petroleum jelly]]. Ballistite and cordite were both manufactured in the form of "cords".

Smokeless powders were originally developed using nitrocellulose as the sole explosive ingredient. Therefore, they were known as single-base propellants. A range of smokeless powders that contains both nitrocellulose and nitroglycerin, known as double-base propellants, were also developed. Smokeless powders were originally supplied only for military use, but they were also soon developed for civilian use and were quickly adopted for sports. Some are known as sporting powders. Triple-base propellants contain nitrocellulose, nitroglycerin, and [[nitroguanidine]], but are reserved mainly for extremely high-caliber ammunition rounds such as those used in tank cannons and [[naval artillery]]. Blasting gelatin, also known as [[gelignite]], was invented by Nobel in 1875, using nitroglycerin, [[wood pulp]], and [[sodium nitrate|sodium]] or [[potassium nitrate]]. This was an early, low-cost, flexible explosive.

== Medical use ==
{{Main|Medical use of nitroglycerin}}
Nitroglycerin belongs to a group of drugs called nitrates, which includes many other nitrates like [[isosorbide dinitrate]] (Isordil) and [[isosorbide mononitrate]] (Imdur, Ismo, Monoket).<ref name="Nitroglycerin Article">{{cite web|url=http://www.medicinenet.com/nitroglycerin/article.htm|title=nitroglycerin, Nitro-Bid: Drug Facts, Side Effects and Dosing|first=Omudhome|last=Ogbru|work=MedicineNet}}</ref> These agents all exert their effect by being converted to [[nitric oxide]] in the body by mitochondrial [[aldehyde dehydrogenase]] ([[ALDH2]]),<ref name="Chen et al. 2005 12159–12164"/> and nitric oxide is a potent natural vasodilator.

[[File:Nitro.JPG|alt=Nitro - bangy stuff|thumb|upright|left|Nitroglycerin in three different forms: intravenous, sublingual spray, and the nitroglycerin patch.]]

In [[medicine]], nitroglycerin is probably most commonly prescribed for [[angina pectoris]], a painful symptom of [[coronary heart disease|ischemic heart disease]] caused by inadequate flow of blood and oxygen to the heart and as a potent antihypertensive agent. Nitroglycerin corrects the imbalance between the flow of oxygen and blood to the heart and the heart's energy demand.<ref name="Nitroglycerin Article"/> There are many formulations on the market at different doses. At low doses, nitroglycerin dilates veins more than arteries, thereby reducing [[preload (cardiology)|preload]] (volume of blood in the heart after filling); this is thought to be its primary mechanism of action. By decreasing preload, the heart has less blood to pump, which decreases oxygen requirement since the heart does not have to work as hard. Additionally, having a smaller preload reduces the ventricular transmural pressure (pressure exerted on the walls of the heart), which decreases the compression of heart arteries to allow more blood to flow through the heart. At higher doses, it also dilates arteries, thereby reducing [[afterload]] (decreasing the pressure against which the heart must pump).<ref name="Nitroglycerin Article"/> An improved ratio of myocardial oxygen demand to supply leads to the following therapeutic effects during episodes of angina pectoris: subsiding of chest pain, decrease of [[blood pressure]], increase of heart rate, and [[orthostatic hypotension]]. Patients experiencing angina when doing certain physical activities can often prevent symptoms by taking nitroglycerin 5 to 10 minutes before the activity. Overdoses may generate [[methemoglobinemia]].<ref>{{cite journal| pmid=3917597 | volume=55 | issue=1 | title=Association of methemoglobinemia and intravenous nitroglycerin administration | year=1985 | journal=[[American Journal of Cardiology]] | pages=181–183 | last1=Kaplan | first1=K. J. | last2=Taber | first2=M. | last3=Teagarden | first3=J. R. | last4=Parker | first4=M. | last5=Davison | first5=R. | doi=10.1016/0002-9149(85)90324-8}}</ref><ref>{{cite web|url=http://www.intramed.net/contenidover.asp?contenidoID=86507|title=IntraMed – Bienvenido|website=www.intramed.net|access-date=14 April 2018}}</ref>

Nitroglycerin is available in tablets, ointment, solution for [[intravenous]] use, [[transdermal patch]]es, or sprays administered [[sublingual]]ly. Some forms of nitroglycerin last much longer in the body than others.  Nitroglycerin as well as the onset and duration of action of each form is different. The sublingual or tablet spray of nitroglycerin has a two minute onset and twenty five minute duration of action. The oral formulation of nitroglycerin has a thirty five minute onset and a duration of action of 4–8 hours. The transdermal patch has an onset of thirty minutes and a duration of action of ten to twelve hours. Continuous exposure to nitrates has been shown to cause the body to stop responding normally to this medicine. Experts recommend that the patches be removed at night, allowing the body a few hours to restore its responsiveness to nitrates. Shorter-acting preparations of nitroglycerin can be used several times a day with less risk of developing tolerance.<ref>{{cite web|url=http://connection.ebscohost.com/c/articles/9703191987|title=Nitroglycerin for angina, February 1997, Vol. 7|access-date=9 November 2009|archive-url=https://web.archive.org/web/20170510141029/http://web.ebscohost.com/src/detail?vid=17&hid=7&sid=7e55c0c3-4b92-4b24-ac2d-b2091791a502%40sessionmgr14&bdata=JnNpdGU9c3JjLWxpdmU%3d#db=hxh&AN=9703191987|archive-date=10 May 2017|url-status=dead}}</ref> Nitroglycerin was first used by [[William Murrell (physician)|William Murrell]] to treat angina attacks in 1878, with the discovery published that same year.<ref name="ReferenceA"/><ref>{{cite journal | pmc = 1798737| year = 1971| last1 = Smith| first1 = E.| title = William Murrell, physician and practical therapist| journal = British Medical Journal| volume = 3| issue = 5775| pages = 632–633| last2 = Hart| first2 = F. D.| pmid = 4998847| doi=10.1136/bmj.3.5775.632}}</ref>

{{clear left}}

== Industrial exposure ==
Infrequent exposure to high doses of nitroglycerin can cause severe [[headache]]s known as "NG head" or "bang head". These headaches can be severe enough to incapacitate some people; however, humans develop a [[tachyphylaxis|tolerance]] to and dependence on nitroglycerin after long-term exposure. Although rare, withdrawal can be fatal;<ref name="CDT">{{cite book|last1=Amdur |first1=Mary O. |last2=Doull |first2=John |title=Casarett and Doull's Toxicology |edition=4th |publisher=Elsevier |date=1991 |isbn=978-0071052399}}</ref> symptoms include chest pain and other heart problems.  These symptoms may be relieved with re-exposure to nitroglycerin or other suitable organic nitrates.<ref name="Jr.Krieger2001">{{cite book| first1=John B. Jr. |last1=Sullivan |first2=Gary R. |last2=Krieger|title=Clinical Environmental Health and Toxic Exposures: Latex|url=https://books.google.com/books?id=PyUSgdZUGr4C&pg=PA264|access-date=23 April 2013|year=2001|publisher=Lippincott Williams & Wilkins|isbn=978-0-683-08027-8|pages=264}}</ref>

For workers in nitroglycerin (NTG) manufacturing facilities, the effects of withdrawal sometimes include "Sunday heart attacks" in those experiencing regular nitroglycerin exposure in the workplace, leading to the development of tolerance for the venodilating effects. Over the weekend, the workers lose the tolerance, and when they are re-exposed on Monday, the drastic [[vasodilation]] produces a [[tachycardia|fast heart rate]], dizziness, and a headache. This is referred to as "Monday disease."<ref name="Short history">{{cite journal |last1=Marsh |first1=N. |last2=Marsh |first2=A. |title=A short history of nitroglycerine and nitric oxide in pharmacology and physiology |journal=Clinical and Experimental Pharmacology and Physiology |volume=27 |issue=4 |pages=313–319 |year=2000 |pmid=10779131 |doi= 10.1046/j.1440-1681.2000.03240.x|s2cid=12897126 }}</ref><ref name="Toxicology">{{cite book|author=Assembly of Life Sciences (U.S.) Advisory Center on Toxicology|title=Toxicological Reports|url=https://books.google.com/books?id=fEQrAAAAYAAJ&pg=PA115|access-date=23 April 2013|publisher=National Academies|pages=115|id=NAP:11288}}</ref>

People can be exposed to nitroglycerin in the workplace by breathing it in, skin absorption, swallowing it, or eye contact. The [[Occupational Safety and Health Administration]]  has set the legal limit ([[permissible exposure limit]]) for nitroglycerin exposure in the workplace as 0.2&nbsp;ppm (2&nbsp;mg/m<sup>3</sup>) skin exposure over an 8-hour workday. The [[National Institute for Occupational Safety and Health]]  has set a [[recommended exposure limit]]  of 0.1&nbsp;mg/m<sup>3</sup> skin exposure over an 8-hour workday. At levels of 75&nbsp;mg/m<sup>3</sup>, nitroglycerin is [[IDLH|immediately dangerous to life and health]].<ref>{{Cite web|publisher= CDC |work=NIOSH Pocket Guide to Chemical Hazards |title=Nitroglycerine|url = https://www.cdc.gov/niosh/npg/npgd0456.html|access-date = 2015-11-21}}</ref>

== See also ==
{{div col|colwidth=22em}}
* [[Erythritol tetranitrate]]
* [[Ethylene glycol dinitrate]]
* [[Mannitol hexanitrate]]
* [[Methyl nitrate]]
* [[Tetranitratoxycarbon]]
* [[Xylitol pentanitrate]]
* [[RE factor]]
{{div col end}}

== References ==
{{Reflist|30em}}

==External links==
{{Commonscat|Nitroglycerin}}
*{{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 | access-date=2005-03-23 }} – 1866 Newspaper article
*[http://webbook.nist.gov/cgi/cbook.cgi?ID=C55630 WebBook page for C<sub>3</sub>H<sub>5</sub>N<sub>3</sub>O<sub>9</sub>]
*[https://www.cdc.gov/niosh/npg/npgd0456.html CDC - NIOSH Pocket Guide to Chemical Hazards]
*[http://www.logwell.com/tales/menu/index.html The Tallini Tales of Destruction] Detailed and horrific stories of the historical use of nitroglycerin-filled [[torpedo (petroleum)|torpedoes]] to restart petroleum wells.
*[http://www.periodicvideos.com/videos/mv_dynamite.htm Dynamite and TNT] at ''[[The Periodic Table of Videos]]'' (University of Nottingham)

{{Nitric oxide signaling}}
{{Authority control}}
{{Use dmy dates|date=April 2017}}

[[Category:Aldehyde dehydrogenase inhibitors]]
[[Category:Disulfiram-like drugs]]
[[Category:Nitrate esters]]
[[Category:Explosive chemicals]]
[[Category:Liquid explosives]]
[[Category:Sugar alcohol explosives]]
[[Category:Italian inventions]]
[[Category:Glycerol esters]]