71669-28-8

Basic information

• Product Name: 1,2,4,7-Tetrachlorodibenzo[1,4]dioxin
• Synonyms: 1,2,4,7-TCDD;1,2,4,7-Tetrachlorodibenzo[1,4]dioxin;1,2,4,7-Tetrachlorodibenzo[b,e][1,4]dioxin;1,2,4,7-Tetrachlorodibenzodioxin;1,2,4,7-Tetrachlorodibenzo-p-dioxin
• CAS NO: 71669-28-8
• Molecular Formula: C₁₂H₄Cl₄O₂
• Molecular Weight: 321.97
• Mol File: 71669-28-8.mol
• Article Data: 6

Chemical Properties

• Boiling Point: 412 °C at 760 mmHg
• Flash Point: 161.2 °C
• Appearance: /
• Density: 1.643 g/cm³
• Vapor Pressure: 1.28E-06mmHg at 25°C
• Refractive Index: 1.655
• CAS DataBase Reference: 1,2,4,7-Tetrachlorodibenzo[1,4]dioxin(CAS DataBase Reference)
• NIST Chemistry Reference: 1,2,4,7-Tetrachlorodibenzo[1,4]dioxin(71669-28-8)
• EPA Substance Registry System: 1,2,4,7-Tetrachlorodibenzo[1,4]dioxin(71669-28-8)

Safety Data

• Hazardous Substances Data: 71669-28-8(Hazardous Substances Data)

Usage

General Description

1,2,4,7-Tetrachlorodibenzo[1,4]dioxin, also known as TCDD, is a highly toxic and persistent environmental pollutant. It is a member of the dioxin family of chemicals, which are produced as byproducts of industrial processes such as waste incineration, chemical manufacturing, and pesticide production. TCDD is considered one of the most toxic dioxins and is classified as a human carcinogen. It has been linked to a range of health effects, including cancer, reproductive and developmental disorders, and immune system impairment. TCDD can bioaccumulate in the food chain, leading to potential human exposure through the consumption of contaminated animal products. Due to its persistence and potential for widespread environmental contamination, efforts to control and reduce TCDD exposure are ongoing.

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

Upstream product

• 74-86-2 acetylene 
• 50884-30-5 potassium salt of 2,4-dichlorophenol 
• 58200-75-2 potassium salt of 2,3,5,6-tetrachlorophenol 

Relevant articles and documents

Role of copper chloride in the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans during incineration

Combustion experiments in a laboratory-scale fluidized-bed reactor were performed to elucidate the role of copper chloride in formation of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) during model waste incineration. The amounts of PCDDs and PCDFs formed, the homologue profiles, and the isomer distributions were measured in the flue gas from incineration of model wastes containing various levels of copper. A correlation was found between the Cu content of the waste and the proportion of each congener. An increase in copper enhanced the formation of certain congeners, showing that copper acts as a catalyst for formation of PCDDs and PCDFs. An increase in the copper content of the waste decreased the CO concentration in the flue gas and reduced the formation of PCDDs and PCDFs during incineration. This indicates that copper also works as an oxidation catalyst to promote combustion, leading to lower concentrations of products of incomplete combustion. It is indispensable to consider both roles of the catalyst, i.e., enhancement and suppression, in the formation of PCDDs and PCDFs during waste incineration, which are estimated separately from the isomer distributions and the amounts of PCDDs and PCDFs formed.

Natural formation of chlorinated phenols, dibenzo-p-dioxins, and dibenzofurans in soil of a Douglas fir forest

The natural formation of 4-MCP, 24/25- and 26-DCP, and 245-TrCP was detected in four selected areas of a rural Douglas fir forest where the humic layer was spiked in situ with a solution of Na37Cl and covered by an enclosure, after 1 year of incubation. Chlorinated phenols (CP) can be formed naturally from organic matter and inorganic chloride by either de novo synthesis or chloroperoxidase (CPO)-catalyzed chlorination. The natural CP congeners were found to be present in high concentrations in soil compared to the other congeners, except for 245-TrCP which was present in a relatively low concentration. This study did not reveal which source, natural or anthropogenic, caused the observed concentrations. Some 20 chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/F) were found to be formed naturally in soil of the Douglas fir forest; the formation of three 2,3,7,8-substituted congeners, 2378-TeCDD, 12378-PeCDD, and 123789-HxCDD, deserves special attention. A formation mechanism has been proposed which starts from naturally formed CP congeners and which probably involves peroxidase mediation. Chlorination of CDD/F congeners by the CPO-mediated reaction cannot be ruled out, but seems to be less likely due to the absence of several predicted congeners. The natural formation of 4-MCP, 24/25- and 26-DCP, and 245-TrCP was detected in four selected areas of a rural Douglas fir forest where the humic layer was spiked in situ with a solution of Na37Cl and covered by an enclosure, after 1 year of incubation. Chlorinated phenols (CP) can be formed naturally from organic matter and inorganic chloride by either de novo synthesis or chloroperoxidase (CPO)-catalyzed chlorination. The natural CP congeners were found to be present in high concentrations in soil compared to the other congeners, except for 245-TrCP which was present in a relatively low concentration. This study did not reveal which source, natural or anthropogenic, caused the observed concentrations. Some 20 chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/F) were found to be formed naturally in soil of the Douglas fir forest; the formation of three 2,3,7,8-substituted congeners, 2378-TeCDD, 12378-PeCDD, and 123789-HxCDD, deserves special attention. A formation mechanism has been proposed which starts from naturally formed CP congeners and which probably involves peroxidase mediation. Chlorination of CDD/F congeners by the CPO-mediated reaction cannot be ruled out, but seems to be less likely due to the absence of several predicted congeners.

Isomer-Specific Separation of 2378-Substituted Polychlorinated Dibenzo-p-dioxins by High-Resolution Gas Chromatography/Mass Spectrometry

All polychlorinated dibenzo-p-dioxin (PCDD) isomers containing four and more chlorine substituents were prepared by micropyrolysis of chlorophenolates.The synthesis included the preparation of all 22 tetra-, 14 penta-, 10 hexa-, 2 hepta-, and octachlorinated species (tetra- to octa-CDD).The gas chromatographic and mass spectrometric properties of these isomers were studied.High resolution gas chromatography (HRGC) on a 55-m Silar 10c glass capillary column allowed the separation of many of these isomers and allowed the unambiguous assignment of the toxic and environmentally hazardous 2378-substituted isomers (2378-tetra-, 12378-penta-, 123478-, 123678-, and 123789-hexa-CDD).Analyses were carried out to determine the occurence of these isomers in environmental samples and in fly ash from municipal incinerators.