Editing Nitroglycerin (section)

== Manufacturing ==
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[[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.