Cyclobutadiene

Cyclobutadiene
Cyclobutadiene	Space-filling model.
Names
	Preferred IUPAC name Cyclobuta-1,3-diene
	Other names 1,3-Cyclobutadiene; Cyclobutadiene; [4]Annulene
Identifiers
CAS Number	1120-53-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:33657 ;
ChemSpider	120626 ;
PubChem CID	136879;
UNII	I5G5583N4F ;
CompTox Dashboard (EPA)	DTXSID00149807 ;
	InChI InChI=1S/C4H4/c1-2-4-3-1/h1-4H Key: HWEQKSVYKBUIIK-UHFFFAOYSA-N ; InChI=1/C4H4/c1-2-4-3-1/h1-4H Key: HWEQKSVYKBUIIK-UHFFFAOYAI;
	SMILES C1=CC=C1;
Properties
Chemical formula	C4H4
Molar mass	52.076 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Cyclobutadiene is an organic compound with the formula C₄H₄. It is very reactive owing to its tendency to dimerize. Although the parent compound has not been isolated, some substituted derivatives are robust and a single molecule of cyclobutadiene is quite stable. Since the compound degrades by a bimolecular process, the species can be observed by matrix isolation techniques at temperatures below 35 K. It is thought to adopt a rectangular structure.^[1]^[2]

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