2,3,7,8-Tetrachlorodibenzodioxin

2,3,7,8-Tetrachlorodibenzodioxin
Names
	Preferred IUPAC name 2,3,7,8-Tetrachlorooxanthrene
	Other names 2,3,7,8-Tetrachlorodibenzo[b,e][1,4]dioxine; Tetradioxin; Tetrachlorodibenzodioxin; Tetrachlorodibenzo-p-dioxin
Identifiers
CAS Number	1746-01-6 ;
3D model (JSmol)	Interactive image;
Abbreviations	TCDD; TCDBD
ChEBI	CHEBI:28119 ;
ChEMBL	ChEMBL30327 ;
ChemSpider	14865 ;
ECHA InfoCard	100.015.566
KEGG	C07557 ;
PubChem CID	15625;
UNII	DO80M48B6O ;
CompTox Dashboard (EPA)	DTXSID2021315 ;
	InChI InChI=1S/C12H4Cl4O2/c13-5-1-9-10(2-6(5)14)18-12-4-8(16)7(15)3-11(12)17-9/h1-4H Key: HGUFODBRKLSHSI-UHFFFAOYSA-N ; InChI=1/C12H4Cl4O2/c13-5-1-9-10(2-6(5)14)18-12-4-8(16)7(15)3-11(12)17-9/h1-4H Key: HGUFODBRKLSHSI-UHFFFAOYAA;
	SMILES ClC1=C(Cl)C=C2OC(C=C(C(Cl)=C3)Cl)=C3OC2=C1;
Properties
Chemical formula	C12H4Cl4O2
Molar mass	321.96 g·mol−1
Appearance	Colorless to white crystalline solid
Density	1.8 g/cm3
Melting point	305 °C (581 °F; 578 K)
Solubility in water	0.2 μg/L
log P	6.8
Vapor pressure	1.5 × 10−9 mmHg
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Potent carcinogen and persistent organic pollutant.
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H304, H315, H336, H361, H373, H401, H410
Precautionary statements	P201, P202, P210, P233, P240, P241, P242, P243, P260, P264, P271, P273, P280, P301+P310, P303+P361+P353, P304+P340+P312, P308+P313, P331, P332+P313, P362+P364, P370+P378, P391, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)	4 1 0
Flash point	164.2 °C (327.6 °F; 437.3 K)
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	Ca
IDLH (Immediate danger)	N.D.
Safety data sheet (SDS)	MSDS
	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

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a polychlorinated dibenzo-p-dioxin (sometimes shortened, though inaccurately, to simply dioxin) with the chemical formula C₁₂H₄Cl₄O₂. Pure TCDD is a colorless solid with no distinguishable odor at room temperature. It is usually formed as an unwanted product in burning processes of organic materials or as a side product in organic synthesis.

TCDD is the most potent compound (congener) of its series (polychlorinated dibenzodioxins, known as PCDDs or simply dioxins) and became known as a contaminant in Agent Orange, an herbicide used in the Vietnam War. TCDD was released into the environment in the Seveso disaster. It is a persistent organic pollutant.