HCHs

BHC, benzene bexacbloride, HCH, hexacbloro-cyclobexane, Chlorinated hydro-... 

Structural studies show allene to be nonplanar As Figure 10 7 illustrates the plane of one HCH unit is perpendicular to the plane of the other Figure 10 7 also portrays the reason for the molecular geometry of allene The 2p orbital of each of the terminal car bons overlaps with a different 2p orbital of the central carbon Because the 2p orbitals of the central carbon are perpendicular to each other the perpendicular nature of the two HCH units follows naturally... 

About 20,000 tons of ultramarines are produced worldwide. The largest manufacturers are Dainichi Seika (Japan), Nubiola (Spain), and Reckitts Colours International (RCI) based in Hull (U.K.), where Isaac Reckitt first began making laundry blue in the 1850s. HoUiday Chemical Hoi dings (HCH of Huddersfield, U.K.) purchased RCI in 1994 (43). 

Lindane is one of eight different hexachlorocyclohexane (HCH), C H Cl, isomers and its Chemical Abstract n.2cniQ is la, 2a 3P, 4a, 5a 6P-hexachlorocyclohexane [58-89-9] (y-HCH or y-BHC, ben2ene hexachloride) (80). Commercial products containing lindane are marketed as either a mixture of isomers or as the pure y-BHC isomer. Not unexpectedly, lindane is a highly stable lipophilic compound and it has been used extensively worldwide as an insecticide. In contrast, hexachloropentadiene, C Cl, is an extremely reactive industrial intermediate used as a chemical intermediate in the synthesis of a broad range of cyclodiene-derived pesticides, which include endosulfan, endrin, heptachlor, and several different organohalogen flame retardants (81). 

Chemistry and Environmental Impact. Lindane is produced by the photocataly2ed addition of chlorine to ben2ene to give a mixture of isomers. The active y-HCH isomer can be preferentially extracted and purified. Composition of the technical-grade product is a (65—70%), B (7—10%), y (14—15%), 5 (7%), and S (1—2%). Lindane has been produced worldwide for its use as an insecticide and for other minor uses in veterinary, agricultural, and medical products. 

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