Chlorobenzenes Hexachlorobenzene

Chloroaniline 4-Chlorophenol Chlorobenzene Hexachlorobenzene Pentachloroaniline Pentachlorobenzene Pentachlorophenol... 

Chlorine and bromine add to benzene in the absence of oxygen and presence of light to yield hexachloro- [27154-44-5] and hexabromocyclohexane [30105-41-0] CgHgBr. Technical benzene hexachloride is produced by either batch or continuous methods at 15—25°C in glass reactors. Five stereoisomers are produced in the reaction and these are separated by fractional crystallization. The gamma isomer (BHC), which composes 12—14% of the reaction product, was formerly used as an insecticide. Benzene hexachloride [608-73-17, C HgCl, is converted into hexachlorobenzene [118-74-17, C Clg, upon reaction with ferric chloride in chlorobenzene solution. 

The chlorination of benzene can theoretically produce 12 different chlorobenzenes. With the exception of 1,3-dichlorobenzene, 1,3,5-trichlorobenzene, and 1,2,3,5-tetrachlorobenzene, all of the compounds are produced readily by chlorinating benzene in the presence of a Friedel-Crafts catalyst (see Friedel-CRAFTS reactions). The usual catalyst is ferric chloride either as such or generated in situ by exposing a large surface of iron to the Hquid being chlorinated. With the exception of hexachlorobenzene, each compound can be further chlorinated therefore, the finished product is always a mixture of chlorobenzenes. Refined products are obtained by distillation and crystallization. 

The major aromatics (organics having at least one ring structure with six carbon atoms) manufactured include benzene, toluene, xylene, and naphthalene. Other aromatics manufactured include phenol, chlorobenzene, styrene, phthalic and maleic anhydride, nitrobenzene, and aniline. Benzene is generally recovered from cracker streams at petrochemical plants and is used for the manufacture of phenol, styrene, aniline, nitrobenzene, sulfonated detergents, pesticides such as hexachlorobenzene, cyclohexane (an important intermediate in synthetic fiber manufacture), and caprolactam, used in the manufacture of nylon. Benzene is also used as a general purpose solvent. 

Chlorobenzenes other than hexachlorobenzene environmental aspects (No. 60, 2004) Chloroform (No. 58, 2004)... 

When an aqueous solution containing hexachlorobenzene (150 nM) and a nonionic surfactant micelle (0.50 M Brij 58, a polyoxyethylene cetyl ether) was illuminated by a photo-reactor equipped with 253.7-nm monochromatic UV lamps, significant concentrations of pentachlorobenzene, all tetra-, tri-, and dichlorobenzenes, chlorobenzene, benzene, phenol, hydrogen, and chloride ions were formed. Two compounds, namely 1,2-dichlorobenzene and 1,2,3,4-tetrachlorobenzene, formed in minor amounts (<40 ppb). The half-life for this reaction, based on... 

Source Hexachlorobenzene may enter the environment from incomplete combustion of chlorinated compounds including mirex, kepone, chlorobenzenes, pentachlorophenol, PVC, polychlorinated biphenyls, and chlorinated solvents (Ahling et al., 1978 Dellinger et al., 1991). In addition, hexachlorobenzene may enter the environment as a reaction by-product in the production of carbon tetrachloride, dichloroethylene, hexachlorobutadiene, trichloroethylene, tetrachloro-ethylene, pentachloronitrobenzene, and vinyl chloride monomer (quoted, Verschueren, 1983). 

Amarthol fast orange R base, see 3-Nitroaniline Amatin, see Hexachlorobenzene Ameisenatod, see Lindane Ameisenmittel merck, see Lindane American Cyanamid 3422, see Parathion American Cyanamid 4049, see Malathion Amerstat 274, see Ethylenediamine Amfol, see Ammonia Amidox, see 2,4-D Amine 2,4,5-T for rice, see 2,4,5-T Aminic acid, see Formic acid 2-Aminoacetylfluorene, see 2-Acetylaminofluorene 4-Aminoaniline, see / Phenylenediamine p-Aminoaniline, see / Phenylenediamine 2-Aminoanisole, see oAnisidine 4-Aminoanisole, see p-Anisidine oAminoanisole, see oAnisidine joAminoanisole, see p-Anisidine Aminobenzene, see Aniline p-Aminobiphenyl, see 4-Aminobiphenyl 1-Aminobutane, see Butylamine l-Amino-4-chloroaniline, see 4-Chloroaniline l-Amino-4-chlorobenzene, see 4-Chloroaniline 1-Amino-p-chlorobenzene, see 4-Chloroaniline 4-Aminochlorobenzene, see 4-Chloroaniline p-Aminochlorobenzene, see 4-Chloroaniline 4-Aminodiphenyl, see 4-Aminobiphenyl... 

Benzazimide, see Azinphos-methvl Benzene, see Chlorobenzene, Cyclohexane, Diallate, Diethyl phthalate, Hexachlorobenzene, 1-Hexene, Lindane, Pentachlorobenzene, Styrene, Triallate. 1,2,3-Trichlorobenzene... 

Chlorobenzene, see a-BHC, 1.2-Dichlorobenzene, 1,3-Dichlorobenzene. 1.4-Dichlorobenzene. Diuron. Hexachlorobenzene, Pentachlorobenzene, 1.2.3-Trichlorobenzene... 

Phenol, see Aminocarb. Benzene, Bromobenzene, Carbaryl, Chlorobenzene, 2-Chlorobiphenvl. 4 Chlorobiphenvl. 1,4-Dichlorobenzene, Hexachlorobenzene, Hydroquinone, 4-Methylphenol, Naphthalene, Pentachlorobenzene, Toluene, 1,2,3-Trichlorobenzene Phenoxazinone, see Phosalone Phenoxyacetic acid, see 2,4-D... 

Chlorobenzenes other than hexachlorobenzene (No. 128,1991) Chlorofluorocarbons, fully halogenated (No. 113,1990)... 

Within a given class of apolar or weakly polar compounds (e.g., alkanes, chlorobenzenes, alkylbenzenes, PCBs), the variation in the air-octanol partition constants (Kiao) is much larger than the variation in the air-water partition constants (Kiaw). For example, the Kim values of the chlorinated benzenes vary between 10 3 5 (chlorobenzene) and 10-7 (hexachlorobenzene, see Hamer and Mackay, 1995), whereas their A, aw values are all within the same order of magnitude (Appendix C). Try to explain these findings. 

No studies were located regarding human populations that are unusually susceptible to chlorobenzene. By analogy to other lipophilic chlorinated benzenes such as hexachlorobenzene, which is found in human milk (Weisenberg et al. 1985), nursing infants may be susceptible to chlorobenzene toxicity. 

Hexachlorobenzene Between 1955 and 1959, more than 3,000 people in Turkey contracted porphyria cutanea tarda after hexa-chlorobenzene had been used as a preservative for cereals. (52)... 

The results of this study show that chlorobenzenes can be expected to occur at trace levels in UK sewage sludge. Concentrations will vary widely, with dichlorobenzenes likely to occur in the range up to 50 ppm, trichlorobenzenes up to 3 ppm, tetrachlorobenzenes up to 0.3 ppm and hexachlorobenzene up to 0.5 ppm. Pentachlorobenzene never occurred at concentrations above the detection limit (0.01 ppm) in the samples examined and therefore is unlikely to be a significant contaminant in sewage sludge. 

Typical enrichment of organic chemicals in the aquatic food chain of Lake Ontario has been observed for DDT and PCBs, which exhibit concentrations up to 8 ug/g and 17 tg/g, respectively, in fish on a lower concentration level - mainly due to the higher solubility of these compounds - similar effects can be seen for mirex and lindane (Table 2-8). Chlorobenzenes, in relation to sediment data, do not exhibit food chain enrichment, except for hexachlorobenzene, which is significantly concentrated in planktonic and benthic organisms. However, there is a distinct accumulation of all chlorobenzene isomers by organisms from the water phase, and it has been Stressed by Oliver Nicol (1982) as a typical feature that Lake Ontario fish contains much higher concentrations of CB s than fish from the other Great Lakes. 

Dechlorination of chlorobenzenes has been shown to occur under anaerobic conditions. Sewage sludge completely transformed 190 pM hexachlorobenzene to DCB [102]. The metabolic pathway for biodegradation of o-DCB [42], m-DCB [93], and p-DCB [99] proposes that they all form a common intermediate dichlorocatediol, and then the benzene ring is broken as indicated in Figure 3. 

The most common method for manufacturing pentachlorophenol is the progressive chlorination of phenols in the presence of Lewis acid catalysts. Another method specific for 2,4,5-trichlorophenol and pentachlorophenol is by hydrolysis of chlorobenzenes such as penta-and hexachlorobenzene. In general, the hydrolysis method always produces more impurities. The final product is a mixture often containing a couple or more of the following compounds ... 

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