Orcinol

{{chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 320722351 | Reference = <ref name="Merck">''Merck Index'', 11th Edition, '''6819'''.</ref> | ImageFile = Orcinol.svg | ImageSize = 150px | PIN = 5-Methylbenzene-1,3-diol | OtherNames = {{ubl| 5-Methylresorcinol| 3,5-Toluenediol| Orcin| 5-Methyl-1,3-benzenediol| 3,5-Dihydroxytoluene}} |Section1={{Chembox Identifiers | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 504-15-4 | ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} | ChemSpiderID = 13839080 | PubChem = 10436 | UNII_Ref = {{fdacite|changed|FDA}} | UNII = 534PMB3438 | SMILES = CC1=CC(=CC(=C1)O)O | InChIKey = OIPPWFOQEKKFEE-UHFFFAOYSA-N | InChI = 1S/C7H8O2/c1-5-2-6(8)4-7(9)3-5/h2-4,8-9H,1H3 }} |Section2={{Chembox Properties | C = 7 | H = 8 | O = 2 | Appearance = Crystalline solid | Density = | MeltingPtC = 109.0 | MeltingPt_ref = <ref name="Mozaffari2020" /> | BoilingPtC = 291 | BoilingPt_ref = <ref name="Mozaffari2020" /> | Solubility = Miscible }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} }}

'''Orcinol''' is an organic compound with the formula CH3C6H3(OH)2. It occurs in many species of lichens<ref>Robiquet: „Essai analytique des lichens de l'orseille", ''Annales de chimie et de physique'', '''1829''', ''42'', p. 236–257.</ref> including ''Roccella tinctoria'' and ''Lecanora''. Orcinol has been detected in the "toxic glue" of the ant species ''Camponotus saundersi''. It is a colorless solid. It is related to resorcinol, 1,3-C6H4(OH)2.

== Synthesis and reactions== Orcinol was first prepared by dehydroacetic acid, a conversion that involved ring-opening of the pyrone to a triketone. This early experiment helped establish the rich condensation chemistry of polyketides.<ref>{{cite journal|title=Polyketide Biosynthesis: A Millennium Review |author1=Staunton, James |author2=Weissman, Kira J. |journal=Natural Product Reports|year=2001|volume=18|issue=4 |pages=380–416|doi=10.1039/a909079g|pmid=11548049 }}</ref> It can be obtained by fusing extract of aloes with potash,<ref name="EB1911"/> followed by acidification.

It undergoes ''O''-methylation with dimethylsulfate.<ref>{{cite journal|title=Orcinol Monomethyl Ether|author=R. N. Mirrington |author2=G. I. Feutrill |journal=Org. Synth.|year=1973|volume=53|page=90|doi=10.15227/orgsyn.053.0090}}</ref>

It is used in the production of the dye orcein and as a reagent in some chemical tests for pentoses, such as Bial's Test. It may be synthesized from toluene; more interesting is its production when acetone dicarboxylic ester is condensed with the aid of sodium. It crystallizes in colorless prisms with one molecule of water, which redden on exposure to air. Ferric chloride gives a bluish-violet coloration with the aqueous solution. Unlike resorcinol it does not give a fluorescein with phthalic anhydride. Oxidation of the ammoniacal solution gives orcein, C28H24N2O7, the chief constituent of the natural dye archil. 4-Methylcatechol is an isomer, found as its methyl ether (creosol) in beech-wood tar.<ref name="EB1911">{{EB1911|inline=y|wstitle=Orcin|volume=20|page=173}}</ref>

:thumb|none|{{center|Orcinol}}

== Production from shale oil == Orcinol is also found in shale oil produced from Kukersite oil shale.<ref name="Mozaffari2020">{{Cite journal|last1=Mozaffari|first1=Parsa|last2=Järvik|first2=Oliver|last3=Baird|first3=Zachariah Steven|date=2020-10-28|title=Vapor Pressures of Phenolic Compounds Found in Pyrolysis Oil|journal=Journal of Chemical & Engineering Data|volume=65 |issue=11 |pages=5559–5566 |doi=10.1021/acs.jced.0c00675|issn=0021-9568|url=https://osf.io/fzex5/ |url-access=subscription}}</ref> It is the main water-soluble phenol in the oil, and has been extracted and refined industrially by Viru Keemia Grupp.<ref>{{Cite web|title=Fine chemicals|url=https://www.vkg.ee/en/fine-chemicals/|access-date=2020-10-23|website=Viru Keemia Grupp|language=en}}</ref>

== References == {{Reflist}}

Category:Alkylresorcinols Category:Lichen products