Cyclononatetraene

Cyclononatetraene
Names
	IUPAC name Cyclonona-1,3,5,7-tetraene
Identifiers
CAS Number	7129-70-6;
3D model (JSmol)	Interactive image;
ChemSpider	11341386;
PubChem CID	12543719;
CompTox Dashboard (EPA)	DTXSID40499530 ;
	InChI InChI=1S/C9H10/c1-2-4-6-8-9-7-5-3-1/h1-8H,9H2/b3-1-,4-2-,7-5-,8-6- Key: GORPVKZVZYAFSO-KZPCVFJPSA-N;
	SMILES C\1/C=C\C=C/C=C\C=C1;
Properties
Chemical formula	C9H10
Molar mass	118.179 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Cyclononatetraene is an organic compound with the formula C₉H₁₀. It was first prepared in 1969 by protonation of the corresponding aromatic anion (described below). It is unstable and isomerizes with a half-life of 50 minutes at room temperature to 3a,7a-dihydro-1H-indene via a thermal 6π disrotatory electrocyclic ring closing. Upon exposure to ultraviolet light, it undergoes a photochemical 8π electrocyclic ring closing to give bicyclo[6.1.0]nona-2,4,6-triene.