Editing Acridine (section)

== Isolation and syntheses ==
[[Carl Gräbe]] and [[Heinrich Caro]] first isolated acridine in 1870 from [[coal tar]].<ref>{{cite journal |last1=Gräbe |first1=C. |last2=Caro |first2=H. |title=Ueber Acridin |journal=Berichte der Deutschen Chemischen Gesellschaft |date=July 1870 |volume=3 |issue=2 |pages=746–747 |doi=10.1002/cber.18700030223 |url=https://zenodo.org/record/1424998 |language=de}}</ref> Acridine is separated from coal tar by extracting with dilute [[sulfuric acid]]. Addition of [[potassium dichromate]] to this solution [[precipitate]]s acridine bichromate.  The bichromate is [[chemical decomposition|decomposed]] using [[ammonia]].

Acridine and its derivatives can be prepared by many synthetic processes.  In the [[Bernthsen acridine synthesis]], [[diphenylamine]] is condensed with [[carboxylic acid]]s in the presence of [[zinc chloride]]. When [[formic acid]] is the carboxylic acid, the reaction yields the parent acridine.  With the higher [[homologous series|larger carboxylic acids]], the derivatives substituted at the ''[[meso position|meso]]'' carbon atom are generated.
:[[Image:Bernthsen Acridine Synthesis Scheme.png|center|500px|The Bernthsen acridine synthesis]]

Other older methods for the [[organic synthesis]] of acridines include condensing diphenylamine with [[chloroform]] in the presence of [[aluminium chloride]], by passing the vapours of orthoaminodiphenylmethane over heated [[litharge]], by heating [[salicylaldehyde]] with [[aniline]] and [[zinc chloride]]  or by distilling [[acridone]] (9-position a [[carbonyl]] group) over [[zinc]] dust.<ref name ="Chisholm">{{EB1911|inline=1|wstitle=Acridine|volume=1|page=155}}</ref>  Another classic method for the synthesis of acridones is the [[Lehmstedt-Tanasescu reaction]].

In [[enzymology]], an [[acridone synthase]] ({{EC number|2.3.1.159}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]

:3 malonyl-CoA + ''N''-methylanthraniloyl-CoA {{eqm}} 4 CoA + 1,3-dihydroxy-''N''-methylacridone + 3 CO<sub>2</sub>

Thus, the two [[substrate (biochemistry)|substrates]] of this enzyme are [[malonyl-CoA]] and [[N-methylanthraniloyl-CoA|''N''-methylanthraniloyl-CoA]], whereas its three [[product (chemistry)|products]] are [[coenzyme A|CoA]], [[1,3-dihydroxy-N-methylacridone|1,3-dihydroxy-''N''-methylacridone]], and [[carbon dioxide|CO<sub>2</sub>]].<ref>{{cite journal|vauthors=Maier W, Baumert A, Schumann B, Furukawa H, Gröger D | date = 1993 | title = Synthesis of 1,3-dihydroxy-N-methylacridone and its conversion to rutacridone by cell-free extracts of Ruta-graveolens cell cultures | journal = [[Phytochemistry (journal)|Phytochemistry]]  | volume = 32 | issue = 3 | pages = 691&ndash;698 | doi = 10.1016/S0031-9422(00)95155-0 | bibcode = 1993PChem..32..691M }}</ref>