1.2.3.4.5.6- Hexachloro-cyclohexane

IUPAC name 1,2,3,4,5,6-hexachloro-cyclohexane-mixed isomer Molecular formula CeHgCb,... 

SYNS BHC (USDA) compound-666 DBH ENT 8,601 GAMMEXANE HCCH HEXA HEXACHLOR HEXACHLORAN HEXACHLORO-CYCLOHEXANE 1,2,3,4,5,6-HEXACHLORO-CYCLOHEXANE HEXYLAN JACUTIN LATKA 666... 

Y-HEXACHLOROBENZENE i-o,2-a,3-p,4-a,5-a,6-P-HEXACHLOROCYCLOHEXANE Y-HEXACHLORO-CYCLOHEXANE (MAK) 1,2,3,4,5,6-HEXACHLORO-CYCLOHEXANE, Y-ISOMER HEXATOX HEXICIDE... 

Addition of 3 moles of chlorine to benzene leads to 1,2,3,4,5,6-hexachloro-cyclohexanes. If the cyclohexane ring is in its more stable chair conformation eight isomers are possible, of which five have so far been isolated.120,121 One of these, y-hexachlorocyclohexane, has become a large-scale commercial insecticide.122... 

The past decade has shown that hydrocarbon desaturation is not uncommon but, except in cases such as the biosynthesis of ergosterol, it generally accounts for a minor proportion of the metabolic products. The earliest reported example of P450-mediated hydrocarbon desaturation appears to be the conversion of lindane (1,2,3,4,5,6-hexachloro-cyclohexane) to 1,2,3,4,5,6-hexachlorocyclohex-ene, but the known hydrocarbon desaturation reactions now include the A -desaturation of androstenedione and deoxycorticosterone by adrenal mitochondria, the oxidation of dihydronaphthalene to naphthalene and 7,8-dihydrobenzo[a] pyrene to benzo[a]pyrene the conversion of warfarin to dehydrowarfarin ", the desaturation of lovostatin and simvastatin to the 6-exo-methylene... 

PROBLEM 7.27 Draw all nine possible stereoisomers of 1,2,3,4,5,6-hexachloro-cyclohexane. Rrst, draw the molecules flat using some schematic device to indicate the stereochemistry of the chlorine atoms. Next, make three-dimensional... 

Figure 2.17 Schematic representation of the set-up used for on-line liquid-liquid exti action coupled with capillary GC when using a membrane phase separator. Reprinted from Journal of High Resdution Chromatography, 13, E. C. Goosens et al., Determination of hexachloro-cyclohexanes in gi ound water by coupled liquid-liquid extraction and capillaiy gas cliro-matography , pp. 438-441, 1990, with permission from Wiley-VCH.

Note Chloramines do not require exposure to chlorine gas before application of o-toluidine. A range of halogen-containing substances (e.g. bromazine, hexachloro-cyclohexane isomers) can be detected with o-toluidine (1 % in ethanol) after subsequent irradiation with UV light (k = 254 or 366 nm 10-15 min) [1, 8]. 

Wiberg K, E Brorstom-Lunden, TF Bidleman, P Haglund (2001) Concentrations and fluxes of hexachloro-cyclohexanes and chiral composition of a-HCH in environmental samples from the southern Baltic Sea. Environ Sci Technol 35 4739-4746. 

Middeldorp PJM, M Jaspers, AJB Zehnder, G Schraa (1996) Biotransformation of a,[5,y, and 5-hexachloro-cyclohexane under methanogenic conditions. Environ Sci Technol 30 2345-2349. 

Figure 1. Vapor Pressure of Gamma Isomer of Hexachloro-cyclohexane and DDT...

Kearns, Weinman, and Decker rate the more common halogenated insect toxicants in the following order of decreasing toxicity (7) dieldrin, aldrin, heptachlor, 7-hexachloro-cyclohexane, chlordan, toxaphene, and DDT. This rating follows as the result of rather extensive tests on ten species of insects and is believed to represent, in general, the order of their relative activity. 

Colorimetric methods (3, 6-10), some of which are specific, have been developed for the determination of DDT in small amounts. For benzene hexachloride (hexachloro-cyclohexane), chlordan, and toxaphene, however, specific analytical methods have not been developed, and their residues have been evaluated by the determination of organically bound chlorine. The procedure comprises extraction of the insecticide residue from the sample with benzene or other suitable organic solvent, evaporation of the solvent, treatment of the residue with isopropyl alcohol and metallic sodium, and finally determination by standard methods of the amount of chloride ion formed. 

This voluntary risk assessment programme started in 1995 and concerned a list of 25 chemicals dichloromethane, chloroform, tetrachloromethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, vinyl chloride, trichloroethene, tetra-chloroethene, hexachlorobutadiene, monochlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, tetrachlorobenzene, hexachlorobenzene, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, pentachlorophenol, hexachloro-cyclohexane, dioxins, PCB, DDT, and elemental mercury. 

Recently Boucard and Deffet [67] examined the action of organic compounds containing halogens, such as carbon tetrachloride, hexachloroethane, y-hexachloro-cyclohexane, chlordane (C10H6C18), iodoform and also iodine. 

The Binational Toxics Strategy between the USA and Canada has identified 12 bioaccumulative substances (referred to as Level-1 substances) having significant persistency and toxicity to the Great Lakes system, with the goal of reducing the sources of these substances to achieve naturally occurring levels [23]. Six of the 12 Level-1 substances are OC pesticides aldrin/dieldrin, chlordane, DDT, HCB, mirex, and toxaphene. Several other OC pesticides, such as endrin, heptachlor/heptachlor epoxide, hexachloro-cyclohexanes, tetra- and penta-chlorobenzenes, and pentachlorophenol, have been identified as Level-2 substances. 

Buser, H-R., Muller, M.D. (1995) Isomer and enantioselective degradation of hexachloro-cyclohexane isomers in sewage sludge under anaerobic conditions. Environ. Sci. Technol. 29, 664-672. 

Kucklick, J.R., Hinckley, D.A., Bidleman, T.F. (1991) Determination of Henry s law constants for hexachloro-cyclohexane in distilled water and artificial seawater as a function of temperature. Marine Chem. 34, 197-209. 

Cyclohexane, hexachloro-(HCH, BHC, mixed isomers) Cyclohexane, a-Hexachloro-Cyclohexane, /3-Hexachloro-Cyclohexane, y-Hexachloro-(lindane)... 

ATSDR (1999) Toxicological profile for alpha-, beta-, gamma-, and delta-hexachloro-cyclohexane. Atlanta, GA, United States Department of Health and Human Services, Agency for Toxic Substances and Disease Registry. 

SYNS a-BENZENEHEXACHLORIDE O-BHC ENT 9,232 O-HCH a-HEXACHLORANE HEXA-CHLORCYCLOHEXAN (GERMAN) O-HEXACHLORO-CYCLOHEXANE (X-l,2.3,4,5,6-HEXACHLOROCYCLO-HEXANE (MAK) l-0,2-(x3-P,4-0,5-P,6-P-HEXA-CHLOROCYCLOHEXANE a-UNDANE... 

The structures of cyclohexane derivatives were also determined by X-ray diffraction techniques. Measurements on the / -isomers of hexachloro-cyclohexane and hexabromocyclohexane verified the ideas of Sachse regarding cyclohexane. The determination of the locations of the halogen atoms in the unit cell showed that these molecules exist in the chair conformation with substituents in so-called equatorial positions as shown in Figure 1.10. 

US EPA (Environmental Protection Agency) (1986) Health and Environmental Effects Profile for Hexachloro-cyclohexanes. Prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH, for the Office of Solid Waste and Emergency Response, Washington, DC. 

The most important product from a commercial as well as a envirotoxicological point of view has been l,l,l-trichloro-2,2 -bis(4-chlorophenyl) ethane or dichlor-odiphenyltrichloroethane (DDT), but also aldrin, dieldrin, lindane (y-hexachloro-cyclohexane, y-HCH), chlordane and toxaphene are of environmental concern (Figure 3.8). 

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