Editing Purine (section)

== History ==
The word ''purine'' (''pure urine'')<ref name="McGuigan">{{cite book | vauthors = McGuigan H |title=An Introduction To Chemical Pharmacology |url=http://www.ebooksread.com/authors-eng/hugh-mcguigan/an-introduction-to-chemical-pharmacology-pharmacodynamics-in-relation-to--goo/page-20-an-introduction-to-chemical-pharmacology-pharmacodynamics-in-relation-to--goo.shtml |publisher=P. Blakiston's Sons & Co. |year=1921 |page=283 |access-date=July 18, 2012 |archive-date=April 16, 2020 |archive-url=https://web.archive.org/web/20200416132051/http://www.ebooksread.com/authors-eng/hugh-mcguigan/an-introduction-to-chemical-pharmacology-pharmacodynamics-in-relation-to--goo/page-20-an-introduction-to-chemical-pharmacology-pharmacodynamics-in-relation-to--goo.shtml |url-status=live }}</ref> was coined by the [[Germany|German]] [[chemist]] [[Emil Fischer]] in 1884.<ref>{{cite journal | vauthors = Fischer E |date=1884 |url=https://zenodo.org/record/1425341/files/article.pdf |title=Ueber die Harnsäure. I. |trans-title=On uric acid. I. |journal=Berichte der Deutschen Chemischen Gesellschaft |volume=17 |pages=328–338 |doi=10.1002/cber.18840170196 |access-date=2016-04-20 |archive-date= |archive-url= |url-status= }} {{open access}}<br>[https://babel.hathitrust.org/cgi/pt?id=uiug.30112025692879;view=1up;seq=343 From p. 329] {{Webarchive|url=https://web.archive.org/web/20220217094238/https://babel.hathitrust.org/cgi/pt?id=uiug.30112025692879;view=1up;seq=343;a=zoom:1 |date=2022-02-17 }}: ''"Um eine rationelle Nomenklatur der so entstehenden zahlreichen Substanzen zu ermöglichen, betrachte ich dieselben als Abkömmlinge der noch unbekannten Wasserstoffverbindung CH<sub>3</sub>.C<sub>5</sub>N<sub>4</sub>H<sub>3</sub> and nenne die letztere Methylpurin."'' (In order to make possible a rational nomenclature for the numerous existing substances, I regarded them as derivatives of a still unknown hydrogen compound, CH<sub>3</sub>.C<sub>5</sub>N<sub>4</sub>H<sub>3</sub>, and call the latter "methylpurine".)</ref><ref name=Fischer1898>{{cite journal | vauthors = Fischer E |date=1898 |url=https://zenodo.org/record/1425916/files/article.pdf |title=Ueber das Purin und seine Methylderivate |trans-title=On purine and its methyl derivatives |journal=Berichte der Deutschen Chemischen Gesellschaft |volume=31 |issue=3 |pages=2550–74 |doi=10.1002/cber.18980310304 |access-date=2016-04-20 |archive-date= |archive-url= |url-status= }} {{open access}}<br>[https://babel.hathitrust.org/cgi/pt?id=hvd.cl1i1u;view=1up;seq=14 From p. 2550] {{Webarchive|url=https://web.archive.org/web/20201018131621/https://babel.hathitrust.org/cgi/pt?id=hvd.cl1i1u;view=1up;seq=14 |date=2020-10-18 }}: ''"…hielt ich es für zweckmäßig, alle diese Produkte ebenso wie die Harnsäure als Derivate der sauerstofffreien Verbindung C<sub>5</sub>H<sub>4</sub>N<sub>4</sub> zu betrachten, und wählte für diese den Namen Purin, welcher aus den Wörtern purum und uricum kombiniert war."'' (…I regarded it as expedient to consider all of these products, just like uric acid, as derivatives of the oxygen-free compound C<sub>5</sub>H<sub>4</sub>N<sub>4</sub>, and chose for them the name "purine", which was formed from the [Latin] words ''purum'' and ''uricum''.)</ref> He synthesized it for the first time in 1898.<ref name=Fischer1898/> The starting material for the reaction sequence was [[uric acid]] ('''8'''), which had been isolated from [[kidney stone]]s by [[Carl Wilhelm Scheele]] in 1776.<ref>{{cite journal | vauthors = Scheele CW | year = 1776 | title = Examen chemicum calculi urinari | trans-title = A chemical examination of kidney stones | journal = Opuscula | volume = 2 | page = 73 }}</ref> Uric acid was reacted with [[phosphorus pentachloride|PCl<sub>5</sub>]] to give 2,6,8-trichloropurine, which was converted with [[hydrogen iodide|HI]] and [[Phosphonium iodide|PH<sub>4</sub>I]] to give 2,6-diiodopurine. The product was reduced to purine using [[zinc]] dust.
:[[File:FischerPurineSynthesis-crop.svg|thumb|left|500px|Conversion of uric acid (left) to purine (right) via 2,6,8-trichloropurine and 2,6-diiodopurine intermediates]]{{clear-left}}