33423-92-6

Basic information

• Product Name: 1,3,6,8-TETRACHLORODIBENZO-P-DIOXIN
• Synonyms: 1,3,6,8-TCDD;1,3,6,8-Tetrachlorobenzo-p-dioxin;1,3,6,8-Tetrachlorodibenzo[1,4]dioxin;1,3,6,8-Tetrachlorodibenzodioxin;1,3,6,8-Tetrachlorodibenzo-para-dioxin;1,3,6,8-tetrachloro-dibenzo-p-dioxi;1,3,6,8-Tetrachlorooxanthrene;Dibenzo-p-dioxin, 1,3,6,8-tetrachloro-
• CAS NO: 33423-92-6
• Molecular Formula: C₁₂H₄Cl₄O₂
• Molecular Weight: 321.97096
• Mol File: 33423-92-6.mol
• Article Data: 8

Chemical Properties

• Melting Point: 219°C
• Boiling Point: 407.62°C (rough estimate)
• Flash Point: 161.7°C
• Appearance: /
• Density: 1.6430 (estimate)
• Vapor Pressure: 1.19E-06mmHg at 25°C
• Refractive Index: 1.6430 (estimate)
• Water Solubility: 0.32ug/L(20 oC)
• CAS DataBase Reference: 1,3,6,8-TETRACHLORODIBENZO-P-DIOXIN(CAS DataBase Reference)
• NIST Chemistry Reference: 1,3,6,8-TETRACHLORODIBENZO-P-DIOXIN(33423-92-6)
• EPA Substance Registry System: 1,3,6,8-TETRACHLORODIBENZO-P-DIOXIN(33423-92-6)

Safety Data

• RIDADR: 2811
• HazardClass: 6.1(a)
• PackingGroup: I
• Hazardous Substances Data: 33423-92-6(Hazardous Substances Data)

Usage

General Description

1,3,6,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a highly toxic and persistent environmental contaminant that belongs to a group of chemical compounds known as dioxins. TCDD is formed as a byproduct of various industrial processes, including waste incineration, chemical manufacturing, and pesticide production. It is also produced naturally as a result of forest fires and volcanic eruptions. TCDD is known to be carcinogenic and can cause a range of adverse health effects in humans and animals, including developmental and reproductive issues, immune system suppression, and chloracne. Due to its high toxicity and persistence in the environment, TCDD is considered to be a major public health and environmental concern.

InChI:InChI=1/C12H4Cl4O2/c13-5-1-7(15)11-9(3-5)18-12-8(16)2-6(14)4-10(12)17-11/h1-4H

Upstream product

• 2591-21-1 potassium salt of 2,4,6-trichlorophenol 
• 58200-72-9 potassium salt of 2,3,5-trichlorophenol 
• 88-06-2 2,4,6-Trichlorophenol 
• 74-86-2 acetylene 
• 3784-03-0 sodium 2,4,6-trichlorophenolate 

Relevant articles and documents

Comparison of 2,4,6-trichlorophenol conversion to PCDD/PCDF on a MSWI- fly ash and a model fly ash

We performed experiments on two different matrices with 2,4,6- trichlorophenol as precursor to Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD)/F. A municipal solid waste incinerators (MSWI) and a model fly ash were spiked in two different ways. The experiments demonstrated a three times higher formation potential of the trichlorophenol to PCDD on MSWI fly ash compared with the model fly ash used. For both fly ashes the PCDD yield was higher when gaseous trichlorophenol was fed continuously compared to mixing the fly ashes prior to the experiments with the total amount of the precursor. Despite dilution of the fly ashes tenfold with an inactive matrix the conversion of the chlorophenol was very high. (C) 2000 Elsevier Science Ltd.

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C2 through C8 organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene. (C) 2000 Elsevier Science Ltd.

Isomer distributions of polychlorinated dibenzo-p-dioxins/dibenzofurans formed during de novo synthesis on incinerator fly ash

Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) emitted from municipal waste incinerators appear to have a chlorination pattern that is quite constant across various samples and conditions. This suggested that these patterns may be controlled by thermodynamic properties of the individual PCDD/F congeners, such as the free Gibbs energy of formation (Δg°(f,T)). This would make prediction of the isomer composition of a particular sample (and hence its TEQ value) possible, based on values of ΔG°(f,T). A laboratory scale study was carried out with activated carbon on fly ash as the source of PCDD/F formation. Although it was found that the isomer distributions within homologues were independent of the reaction time (proof of thermodynamic control), other observations (lack of equilibrium/isomerization between isomers and lack of similarity between isomer distributions measured and predicted by ΔG°(f,T)) contradicted the possibility of thermodynamic control. Hence, this study could not confirm that de novo formation of PCDD/F could explain thermodynamically controlled isomer distributions in incinerators. Some recommendations for further work- time-based studies with precursors, isomerization studies with single congeners, and more data on ΔG°(f,T) values of PCDD/F-were made. Polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) emitted from municipal waste incinerators appear to have a chlorination pattern that is quite constant across various samples and conditions. This suggested that these patterns may be controlled by thermodynamic properties of the individual PCDD/F congeners, such as the free Gibbs energy of formation (ΔG°f,T). This would make prediction of the isomer composition of a particular sample (and hence its TEQ value) possible, based on values of ΔG°f,T. A laboratory scale study was carried out with activated carbon on fly ash as the source of PCDD/F formation. Although it was found that the isomer distributions within homologues were independent of the reaction time (proof of thermodynamic control), other observations (lack of equilibrium/isomerization between isomers and lack of similarity between isomer distributions measured and predicted by ΔG°f,T) contradicted the possibility of thermodynamic control. Hence, this study could not confirm that de novo formation of PCDD/F could explain thermodynamically controlled isomer distributions in incinerators. Some recommendations for further work - time-based studies with precursors, isomerization studies with single congeners, and more data on ΔG°f,T values of PCDD/F - were made.