Editing Azulene (section)

{{Use dmy dates|date=December 2023}}

{{chembox
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageFileL1 = Azulen_num.svg
| ImageSizeL1 = 120
| ImageFileR1 = Azulene_3d_structure.png
| ImageSizeR1 = 120
| PIN = Azulene<ref>{{cite book |author=[[International Union of Pure and Applied Chemistry]] |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=[[Royal Society of Chemistry|The Royal Society of Chemistry]] |pages=207 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}</ref>
| SystematicName = Bicyclo[5.3.0]decapentaene
| OtherNames = 
|Section1={{Chembox Identifiers
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 82R6M9MGLP
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C13392
| InChI = 1/C10H8/c1-2-5-9-7-4-8-10(9)6-3-1/h1-8H
| InChIKey = CUFNKYGDVFVPHO-UHFFFAOYAT
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C10H8/c1-2-5-9-7-4-8-10(9)6-3-1/h1-8H
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = CUFNKYGDVFVPHO-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 275-51-4
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID =8876
| PubChem = 9231
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 31249
| SMILES = c1cccc2cccc2c1
}}
|Section2={{Chembox Properties
| C=10 | H=8
| Appearance = 
| Density = 
| MeltingPtC = 99 to 100
| MeltingPt_notes = 
| BoilingPtC = 242
| BoilingPt_notes = 
| Solubility =  
| MagSus = −98.5·10<sup>−6</sup> cm<sup>3</sup>/mol<ref>{{cite journal |doi=10.1007/s001289900330 |pmid=8975804|url=http://deepblue.lib.umich.edu/bitstream/2027.42/42354/1/128-58-2-268_58n2p268.pdf|title=Lethal and Sublethal Effects of Azulene and Longifolene to Microtox®, Ceriodaphnia dubia, Daphnia magna, and Pimephales promelas|journal=[[Bulletin of Environmental Contamination and Toxicology]] |volume=58|issue=2|pages=268–274|year=1997|last1=Sweet|first1=L. I.|last2=Meier|first2=P. G.|bibcode=1997BuECT..58..268S |hdl=2027.42/42354|hdl-access=free}}</ref>}}
|Section3={{Chembox Thermochemistry
| DeltaHc = −1266.5 kcal/mol<ref>{{cite journal |last1=Salter |first1=Carl |last2=Foresman |first2=James B. |year=1998 |title=Naphthalene and Azulene I: Semimicro Bomb Calorimetry and Quantum Mechanical Calculations  |journal=[[Journal of Chemical Education]] |volume=75 |issue=10 |pages=1341 |bibcode=1998JChEd..75.1341S |doi=10.1021/ed075p1341}}</ref>
| DeltaHf =
| Entropy = 
| HeatCapacity = }}
|Section4={{Chembox Hazards
| MainHazards = 
| FlashPt = 
| AutoignitionPt = 
 }}
}}

'''Azulene''' is an aromatic [[organic compound]] and an [[Valence isomer|isomer]] of [[naphthalene]]. Naphthalene is colourless, whereas azulene is dark blue. The compound is named after its colour, as "azul" is [[Spanish language|Spanish]] for blue. Two terpenoids, [[vetivazulene]] (4,8-dimethyl-2-isopropylazulene) and [[guaiazulene]] (1,4-dimethyl-7-isopropylazulene), that feature the azulene skeleton are found in nature as constituents of pigments in mushrooms, [[Oil of guaiac|guaiac wood oil]], and some marine invertebrates.

Azulene has a long history, dating back to the 15th century as the azure-blue [[chromophore]] obtained by [[steam distillation]] of [[Matricaria recutita|German chamomile]]. The chromophore was discovered in [[yarrow]] and [[Artemisia (genus)|wormwood]] and named in 1863 by Septimus Piesse. Its structure was first reported by [[Lavoslav Ružička]], followed by its [[organic synthesis]] in 1937 by Placidus Plattner.