Elassovalene
{{Chembox
| ImageFile = Elassovalene.svg
| ImageSize = 120px
| PIN = 2a,2a1-Dihydrocyclopenta[cd]azulene
| OtherNames =
| Section1 = {{Chembox Identifiers
| CASNo = 38310-40-6
| ChemSpiderID = 125478
| PubChem = 142246
| UNII = 5HK24EQ36P
| SMILES = C1=CC=C2C=CC3C2C(=C1)C=C3
| StdInChI= 1S/C12H10/c1-2-4-10-6-8-11-7-5-9(3-1)12(10)11/h1-8,11-12H
| StdInChIKey = HXHFTTRCEKEWIZ-UHFFFAOYSA-N
}}
| Section2 = {{Chembox Properties
| C=12|H=10
| Appearance =
| Density =
| MeltingPt =
| BoilingPt =
| Solubility =
}}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
Elassovalene (2a,8b-dihydro-cyclopent[cd]azulene) is a polycyclic hydrocarbon with chemical formula C12H10, composed of one cycloheptatriene ring and two fused cyclopentene rings.{{Cite book|title=Organic Chemistry: The Name Game: Modern Coined Terms and Their Origins|last1=Nickon|first1=Alex|last2=Silversmith|first2=Ernest F.|publisher=Elsevier|year=2013|isbn=978-1483145235|location=|pages=297|quote=}}