Chlorodibenzo-p-dioxin

The 1-chloro- and 2-chlorodibenzo-p-dioxins, which readily dissolved in TFMS acid, formed cation radicals without UV irradiation or the addition of oxidizing agents. With the exception of broader resonance lines. Figure 3 shows that the five-line pattern observed with 1-chloro-dibenzo-p-dioxin is similar to that of the unsubstituted dibenzo-p-dioxin. Apparently, protons at the 2, 3, 7, and 8 positions became less equivalent... 

Figure 4. ESR spectrum of 2-chlorodibenzo-p-dioxin in TFMS acid...

Female Wistar rats treated orally with 0.125-16 jug/kg/day of 2,3,7,8-tetrachlorodibenzo-p-dioxin (8-D), 50-800 jug/kg/day of 1,2,3,4-tetra-chlorodibenzo-p-dioxin (4-D , and 250-2000 /xg/kg/day of 2,7-dichloro-dibenzo-p-dioxin (2-D) and 1,000-2,000 /xg/kg/day of 2,3-dichlorodi-benzo-p-dioxin or 2-chlorodibenzo-p-dioxin during 6—15 days of gestation (first morning of a positive vaginal smear was designated as day 1) were assessed for prenatal effects of the compounds on their progeny. 

Tetrachlorodibenzo-p-dioxin elicited no apparent prenatal or postnatal effects when doses of up to 800 /xg/kg/day were given orally for 10 days of gestation. Treatment with 250-2000 /xg/kg/day of 2,7-di-chlorodibenzo-p-dioxin (99% purity) had no significant effect on prenatal and postnatal measures of toxicity but caused a low incidence of cardiac lesions. 2,3-Dichlorodibenzo-p-dioxin and 2-chlorodibenzo-p-dioxin up to 2000 /xg/kg/day had no adverse effect on survival, average weight, and skeleton of term fetuses. 

Common Name 2-Chlorodibenzo-p-dioxin Synonym 2-CDD, 2-MCDD Chemical Name 2-chlorodibenzo-p-dioxin CAS Registry No 39227-54-8 Molecular Formula C6H402C6H3C1 Molecular Weight 218.636 Melting Point (°C) ... 

Reported aqueous solubilities and vapor pressures of 2-chlorodibenzo-p-dioxin at various temperatures... 

FIGURE 8.1.1.3.1 Logarithm of mole fraction solubility and vapor pressure versus reciprocal temperature for 2-chlorodibenzo-p-dioxin. 

Variations in the manufacturing process of 2,4,5-trichloro- and pentachlorophenol (but not 2,4-dichlorophenol) have sometimes resulted in contamination of the product by small amounts of heterocyclic impurities (4,5). Of these, the chlorinated dibenzo-p-dioxins such as TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) have received much scientific and public attention because of their real or potential toxicity 6, 7), [Chick edema factor, a curious toxicological problem to poultry producers for several years, has been shown to be composed of chlorodibenzo-p-dioxins (8).]... 

Figure 3. Photolysis rate of 2,3,7,8-tetra-chlorodibenzo-p-dioxin (5 mg/liter in methanol) in sunlight (20), 1971 by AAAS...

Figure 2. Excretion of activity by rats following a single oral dose of 50 fJig/kg (0.14 iCi/kg) 2,3J,8-tetra-chlorodibenzo-p-dioxin. Each point represents the mean SE for three rats.

An environmental protocol has been developed to assess the significance of newly discovered hazardous substances that might enter soil, water, and the food chain. Using established laboratory procedures and C-labeled 2,3,7,8-tetra-chlorodibenzo-p-dioxin (TCDD), gas chromatography, and mass spectrometry, we determined mobility of TCDD by soil TLC in five soils, rate and amount of plant uptake in oats and soybeans, photodecomposition rate and nature of the products, persistence in two soils at 1,10, and 100 ppm, and metabolism rate in soils. We found that TCDD is immobile in soils, not readily taken up by plants, subject to photodecomposition, persistent in soils, and slowly degraded in soils to polar metabolites. Subsequent studies revealed that the environmental contamination by TCDD is extremely small and not detectable in biological samples. 

To investigate the possibility of preparing uniquely substituted hexa-chlorodibenzo-p-dioxins, several experiments were performed under Ullmann conditions. Although condensation of potassium 2-bromo-4-chlorphenate occurred readily, several 2,6-substituted phenates failed to... 

The most convenient and successful synthetic preparation of octa-chlorodibenzo-p-dioxin has been described by Kulka (13). The procedure involves chlorination of pentachlorophenol in refluxing trichlorobenzene to give octachlorodibenzo-p-dioxin in 80% yield. Kulka has explained the reaction as coupling between two pentachlorophenoxy radicals. Large amounts (5—15%) of heptachlorodibenzo-p-dioxin were observed in the unpurified product. Since the pentachlorophenol used in this study contained 0.07% tetrachlorophenol, we feel that tetrachloro-phenol may be produced in situ (Reaction 4). Such a scheme would be analogous to the formation of 2,4-dichlorophenol and 3-chlorophenol produced from 2,4,4 -trichloro-2 -hydroxydiphenyl ether (Reaction 2). The solubility of octachlorodibenzo-p-dioxin was determined in various solvents data are presented in Table II. 

Kwok ESC, R Atkinson, J Arey (1995) Rate constants for the gas-phase reactions of the OH radical with dichlorobiphenyls, 1-chlorodibenzo-p-dioxin, 1,2-dimethoxybenzene, and diphenyl ether estimation of OH radical reaction rate constants for PCBs, PCDDs, and PCDFs. Environ Sci Technol 29 1591-1598. 

Ankley, G.T., D.E. Tillitt, J.P. Giesy, P.D. Jones, and D.A. Verbrugge. 1991. Bioassay-derived 2,3,7,8-tetra-chlorodibenzo-p-dioxin equivalents in PCB-containing extracts from the flesh and eggs of Lake Michigan chinook salmon (Oncorhynchus tshawytscha) and possible implications for reproduction. Canad. Jour. Fish. Aquat. Sci. 48 1685-1690. 

Hanberg, A., Nilsson, C. B., Trossvik, C., and Hakansson, H. (1998). Effect of 2,3,7,8-tetra-chlorodibenzo-p-dioxin on the lymphatic absorption of a single oral dose of [3H]retinol and on the intestinal retinol esterification in the rat. /. Toxicol. Environ. Health A 55, 331-344. 

Another development is due to the interest in polychlorodibenzofurans, spurred by their occurrence as environmental contaminants. Polychloro-phenols are manufactured in large amounts (150,000 tons per annum) and find a wide range of uses. The usual method of manufacture involves the hydrolysis of chlorobenzenes, and side reactions, favored by high temperature, can lead to the production of polychlorodibenzofurans and poly-chlorodibenzo-p-dioxins. The Seveso incident is well known." Polychloro-biphenyls are also widely used industrial chemicals, particularly in heat exchange systems, and their pyrolysis leads to the formation of polychloro-dibenzofurans. Polychlorodibenzofurans have also been detected in the fly ash and flue gases of incinerators and industrial heating plants. The most toxic of the polychlorodibenzofurans are 2,3,7,8-tetra-, 1,2,3,7,8-penta-, and 2,3,4,7,8-pentachlorodibenzofuran, and an extensive literature exists on the environmental pollution and the results of human exposure to these substances. A particularly tragic example of the latter occurred in 1968 in the Fukuoka prefecture of Japan after consumption of rice oil contaminated with a commercial polychlorobiphenyl. 

Poland A, Glover E, Kende AS. 1976. Stereospecific, high affinity binding of 2,3,7,8-tetra-chlorodibenzo-p-dioxin by hepatic cytosol. Evidence that the binding species is receptor for induction of aryl hydrocarbon hydrolase. J Biol Chem 251 4936-4946. 

Calculate the aqueous activity coefficients,, and the excess free energies in aqueous solution, G (in kJ mol1), of (a) w-decane (n-C ioH22), (b) 2,3,7,8-tetra-chlorodibenzo-p-dioxin, and (c) bromomethane (CH3Br) at 25°C using the data provided in Appendix C. 

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