Editing Pyridine (section)

==History==
[[File:ThomasAnderson(1819-1874).jpg|thumb|upright|[[Thomas Anderson (chemist)|Thomas Anderson]]]]
Impure pyridine was undoubtedly prepared by early [[Alchemy|alchemists]] by heating animal bones and other organic matter,<ref name=weiss>{{cite book|last1=Weissberger |first1=A. |last2=Klingberg |first2=A. |last3=Barnes |first3=R. A.|last4= Brody |first4=F. |last5=Ruby |first5=P.R. |title=Pyridine and its Derivatives |volume=1 |date=1960 |publisher=Interscience |location=New York}}</ref> but the earliest documented reference is attributed to the Scottish scientist [[Thomas Anderson (chemist)|Thomas Anderson]].<ref>{{cite journal |last1=Anderson |first1=Thomas |title=On the constitution and properties of picoline, a new organic base from coal-tar |journal=Transactions of the Royal Societies of Edinburgh University |date=1849 |volume=16 |issue=2 |pages=123–136 |url=https://babel.hathitrust.org/cgi/pt?id=njp.32101074834258;view=1up;seq=153 |doi=10.1017/S0080456800024984 |s2cid=100301190 |access-date=24 September 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045408/https://babel.hathitrust.org/cgi/pt?id=njp.32101074834258;view=1up;seq=153 |url-status=live }}</ref><ref name="Von1849">{{cite journal|last1=Anderson|first1=T.|title=Producte der trocknen Destillation thierischer Materien|trans-title=Products of the dry distillation of animal matter|journal=Annalen der Chemie und Pharmacie|volume=70|pages=32–38|year=1849|language=de|url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112025848026;view=1up;seq=434|doi=10.1002/jlac.18490700105|access-date=24 September 2018|archive-date=24 May 2020|archive-url=https://web.archive.org/web/20200524045414/https://babel.hathitrust.org/cgi/pt?id=uiug.30112025848026;view=1up;seq=434|url-status=live}}</ref> In 1849, Anderson examined the contents of the [[Dippel's oil|oil obtained through high-temperature heating of animal bones]].<ref name="Von1849" /> Among other substances, he separated from the oil a colorless liquid with unpleasant odor, from which he isolated pure pyridine two years later. He described it as highly soluble in water, readily soluble in concentrated acids and salts upon heating, and only slightly soluble in oils.

Owing to its flammability, Anderson named the new substance ''pyridine'', after {{langx|el|[[wikt:πῦρ|πῦρ]]}} (pyr) meaning ''fire''. The suffix ''[[wikt:-idine|idine]]'' was added in compliance with the chemical nomenclature, as in ''[[toluidine]]'', to indicate a [[cyclic compound]] containing a nitrogen atom.<ref>{{cite journal |last1=Anderson |first1=Thomas |title=On the products of the destructive distillation of animal substances. Part II. |journal=Transactions of the Royal Society of Edinburgh |date=1851 |volume=20 |issue=2 |pages=247–260 |url=https://babel.hathitrust.org/cgi/pt?id=njp.32101074834290;view=1up;seq=287 |doi=10.1017/S0080456800033160 |s2cid=102143621 |access-date=24 September 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045301/https://babel.hathitrust.org/cgi/pt?id=njp.32101074834290;view=1up;seq=287 |url-status=live }}  From p. 253: "Pyridine. The first of these bases, to which I give the name of pyridine, … "</ref><ref name=anderson2>{{cite journal |last1=Anderson |first1=T. |title=Ueber die Producte der trocknen Destillation thierischer Materien |trans-title=On the products of dry distillation of animal matter |journal=Annalen der Chemie und Pharmacie |volume=80 |pages=44–65 |year=1851 |language=de |url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112025848422;view=1up;seq=444 |doi=10.1002/jlac.18510800104 |access-date=24 September 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045314/https://babel.hathitrust.org/cgi/pt?id=uiug.30112025848422;view=1up;seq=444 |url-status=live }}</ref>

The chemical structure of pyridine was determined decades after its discovery. [[Wilhelm Körner]] (1869)<ref>{{cite journal |last1=Koerner |first1=W. |title=Synthèse d'une base isomère à la toluidine |journal=Giornale di Scienze Naturali ed Economiche (Journal of Natural Science and Economics (Palermo, Italy)) |date=1869 |volume=5 |pages=111–114 |url=https://books.google.com/books?id=J00_AAAAcAAJ&pg=PA111 |trans-title=Synthesis of a base [that is] isomeric to toluidine |language=fr}}</ref> and [[James Dewar]] (1871)<ref>{{cite journal |last1=Dewar |first1=James |title=On the oxidation products of picoline |journal=Chemical News |date=27 January 1871 |volume=23 |pages=38–41 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.$c193335;view=1up;seq=46 |access-date=27 September 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045420/https://babel.hathitrust.org/cgi/pt?id=uc1.$c193335;view=1up;seq=46 |url-status=live }}</ref><ref>{{cite journal |title=Koerner, Dewar and the Structure of Pyridine |first=Alan J. |last=Rocke |journal=Bulletin for the History of Chemistry |volume=2 |date=1988 |page=4 |url=http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/bull88-num2.php |access-date=5 May 2016 |archive-date=24 September 2018 |archive-url=https://web.archive.org/web/20180924105914/http://www.scs.illinois.edu/~mainzv/HIST/bulletin_open_access/bull88-num2.php |url-status=live }} {{open access}}</ref> suggested that, in analogy between [[quinoline]] and [[naphthalene]], the structure of pyridine is derived from [[benzene]] by substituting one C–H unit with a nitrogen atom.<ref>{{cite book |author-link=Albert Ladenburg |last=Ladenburg |first=Albert |url=http://www.sciencemadness.org/library/books/lectures_on_the_history_of_the_development_of_chemistry.pdf |title=Lectures on the history of the development of chemistry since the time of Lavoisier |pages=283–287 |year=1911|access-date=7 January 2011 |archive-date=20 September 2018 |archive-url=https://web.archive.org/web/20180920134805/http://www.sciencemadness.org/library/books/lectures_on_the_history_of_the_development_of_chemistry.pdf |url-status=live }} {{open access}}</ref><ref>{{cite book|last=Bansal |first=Raj K. |url=https://books.google.com/books?id=RH1l_VQcFDQC&pg=PA216 |title=Heterocyclic Chemistry |date=1999 |isbn=81-224-1212-2 |page=216|publisher=New Age International }}</ref> The suggestion by Körner and Dewar was later confirmed in an experiment where pyridine was reduced to [[piperidine]] with [[sodium]] in [[ethanol]].<ref>{{cite journal |last1=Ladenburg |first1=A. |title=Synthese des Piperidins |journal=Berichte der Deutschen Chemischen Gesellschaft |date=1884 |volume=17 |page=156 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.31210011601398;view=1up;seq=164 |trans-title=Synthesis of piperidine |language=de |doi=10.1002/cber.18840170143 |access-date=15 October 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045307/https://babel.hathitrust.org/cgi/pt?id=uc1.31210011601398;view=1up;seq=164 |url-status=live }}</ref><ref>{{cite journal |last1=Ladenburg |first1=A. |title=Synthese des Piperidins und seiner Homologen |journal=Berichte der Deutschen Chemischen Gesellschaft |date=1884 |volume=17 |pages=388–391 |url=https://babel.hathitrust.org/cgi/pt?id=uc1.31210011601398;view=1up;seq=396 |trans-title=Synthesis of piperidine and its homologues |language=de |doi=10.1002/cber.188401701110 |access-date=15 October 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045355/https://babel.hathitrust.org/cgi/pt?id=uc1.31210011601398;view=1up;seq=396 |url-status=live }}</ref> In 1876, [[William Ramsay]] combined [[acetylene]] and [[hydrogen cyanide]] into pyridine in a [[Red heat|red-hot]] iron-tube furnace.<ref>{{cite journal |last1=Ramsay |first1=William |title=On picoline and its derivatives |journal=Philosophical Magazine |date=1876 |volume=2 |pages=269–281 |url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112098008771;view=1up;seq=283 |series=5th series |issue=11 |doi=10.1080/14786447608639105 |access-date=24 September 2018 |archive-date=24 May 2020 |archive-url=https://web.archive.org/web/20200524045452/https://babel.hathitrust.org/cgi/pt?id=uiug.30112098008771;view=1up;seq=283 |url-status=live }}</ref> This was the first synthesis of a heteroaromatic compound.<ref name=osha/><ref>{{cite journal|title=A. Henninger, aus Paris. 12. April 1877|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=10|pages=727–737|year=1877|doi=10.1002/cber.187701001202|type=Correspondence}}</ref>

The first major synthesis of pyridine derivatives was described in 1881 by [[Arthur Rudolf Hantzsch]].<ref>{{cite journal|last1=Hantzsch|first1=A.|title=Condensationsprodukte aus Aldehydammoniak und ketonartigen Verbindungen|trans-title=Condensation products from aldehyde ammonia and ketone-type compounds|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=14|pages=1637–1638|year=1881|doi=10.1002/cber.18810140214|issue=2|url=https://zenodo.org/record/1425236|access-date=6 September 2019|archive-date=22 January 2021|archive-url=https://web.archive.org/web/20210122224737/https://zenodo.org/record/1425236|url-status=live}}</ref> The [[Hantzsch pyridine synthesis]] typically uses a 2:1:1 mixture of a β-[[keto acid]] (often [[Acetoacetic acid|acetoacetate]]), an [[aldehyde]] (often [[formaldehyde]]), and [[ammonia]] or its salt as the nitrogen donor. First, a double [[Hydration reaction|hydrogenated]] pyridine is obtained, which is then oxidized to the corresponding pyridine derivative. [[Emil Knoevenagel]] showed that asymmetrically substituted pyridine derivatives can be produced with this process.<ref>{{cite journal|last1=Knoevenagel|first1=E.|last2=Fries|first2=A.|title=Synthesen in der Pyridinreihe. Ueber eine Erweiterung der Hantzsch'schen Dihydropyridinsynthese|trans-title=Syntheses in the pyridine series. On an extension of the Hantzsch dihydropyridine synthesis|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=31|pages=761–767|year=1898|doi=10.1002/cber.189803101157|url=https://zenodo.org/record/1425894|access-date=29 June 2019|archive-date=15 January 2020|archive-url=https://web.archive.org/web/20200115174109/https://zenodo.org/record/1425894|url-status=live}}</ref>

[[File:Hantzsch pyridine synthesis.svg|class=skin-invert-image|800px|thumb|center|[[Hantzsch pyridine synthesis]] with acetoacetate, formaldehyde and [[ammonium acetate]], and [[iron(III) chloride]] as the oxidizer.]]

The contemporary methods of pyridine production had a low yield, and the increasing demand for the new compound urged to search for more efficient routes. A breakthrough came in 1924 when the Russian chemist [[Aleksei Chichibabin]] invented a [[Chichibabin pyridine synthesis|pyridine synthesis reaction]], which was based on inexpensive reagents.<ref name=tschi>{{cite journal
| last = Chichibabin
| first = A. E.
| trans-title = On condensation of aldehydes with ammonia to make pyridines
| title = Über Kondensation der Aldehyde mit Ammoniak zu Pyridinebasen
| url = http://gallica.bnf.fr/ark:/12148/bpt6k90877m/f132.chemindefer
| journal = Journal für Praktische Chemie
| year = 1924
| volume = 107
| pages = 122
| doi = 10.1002/prac.19241070110
| access-date = 7 January 2011
| archive-date = 20 September 2018
| archive-url = https://web.archive.org/web/20180920134841/https://gallica.bnf.fr/ark:/12148/bpt6k90877m/f132.chemindefer
| url-status = live
}}</ref> This method is still used for the industrial production of pyridine.<ref name=ul/>