1,2,3,4,5,6-Hexachlorocyclohexane gamma isomer

Synonyms/Trade Names BHC HCH y-Hexachlorocyclohexane gamma Isomer of 1,2,3,4,5,6-Hexachlorocyclohexane ... 

That benzene hexachloride isomer mixture is then the raw material for lindane production. The production of lindane per se is not a chemical synthesis operation but a physical separation process. It is possible to influence the gamma isomer content of benzene hexachloride to an extent during the synthesis process. Basically, however, one is faced with the problem of separating a 99%-plus purity gamma isomer from a crude product containing perhaps 12 to 15% of the gamma isomer. The separation and concentration process is done by a carefully controlled solvent extraction and crystallization process. One such process is described by R.D. Donaldson et al. Another description of hexachlorocyclohexane isomer separation is given by R.H. Kimball. 

Laboratory studies showed the pure gamma isomer of hexachlorocyclohexane to have residual life equivalent to that of the normal mixed isomers. The material does not break down in normal storage, as do mixed isomers. 

Field test work with technically pure gamma isomer of hexachlorocyclohexane has been extensive and involved and is being continued. It was necessary to know such factors as insecticidal value in field applications as compared to other insecticides, as well as residual life, residue from the poison standpoint, and residual taste or odor factors. These factors have been worked out on numerous crops and some of the results are dealt wTith in this paper. Because the pure gamma isomer was found to be effective on insects in the soil as well as on insect infestations on plants, its residual life in soil of all types and effects on tuber and root crops were also of major importance. 

The use of pure gamma isomer of hexachlorocyclohexane on livestock has also been worked out. It has been found possible to use the wettable powder formulation dispersed in water as a spray on livestock for control of flies, lice, and ticks. Proper dosage and application must be used, of course, but this is again indicative of the safety factor of this insecticide. 

Chlorination of benzene gives an addition product that is a mixture of stereoisomers known collectively as hexachlorocyclohexane (HCH). At one time, this was incorrectly termed benzene hexachloride. The mixtnre has insecticidal activity, though activity was found to reside in only one isomer, the so-called gamma isomer, y-HCH. y-HCH, sometimes under its generic name lindane, has been a mainstay insecticide for many years, and is about the only example of the chlorinated hydrocarbons that has not been banned and is still available for general use. Although chlorinated hydrocarbons have proved very effective insecticides, they are not readily degraded in the environment, they accumulate and persist in animal tissues, and have proved toxic to many bird and animal species. 

The gamma isomer of hexachlorocyclohexane was commonly called gamma benzene hexachloride, a misnomer, since no... 

Hexachlorocyclohexane, once confusingly called benzene hexachloride (BHC), consists of several stereoisomers with different orientations of H and Cl atoms. The gamma isomer is shown in Figure 16.5. It is an effective insecticide, constituting at least 99% of the commercial insecticide lindane. 

Lindane is a pesticide that is widely used in the treatment of scabies and pediculosis, usually in a 1 % lotion (SEDA-5, 154) (1-4). It is the gamma-isomer of 1,2,3,4,5,6-hexachlorocyclohexane. The hazards of excessive industrial exposure and accidental ingestion have been well documented (3). 

The use of the gamma isomer of hexachlorocyclohexane with added tetra-methylthiuram disulfide (TMTD), the wetting agent OP-7 (nonionic), a concentrate of sulfite alcohol residue (SAR), and other fillers have been proposed in [346]. 

Benzene hexachloride is a misnomer for a chemical. Benzene hexachloride, originally prepared by Michael Faraday in 1825, is hexachlorocyclohexane.) Lindane has the spatial configuration that possesses the (99% + gamma isomer) highest activity six hexa-chlorocyclohexanes are found in commercial preparations although the stereochemistry of the cyclohexane ring does provide many more theoretical isomers. Lindane has three axial and three equatorial chlorines. 

When the individual insecticides are present in the solution in such a concentration range, the electron capture responds nearly uniformly to all insecticides. A column filled with 1.5% silicone OV-17 plus silicone oil (fluoralchylsiloxane) on Chromasorb W (80-100 mesh) is used for separation of the BHC alpha, beta, gamma and delta isomers (hexachlorocyclohexane), o,p -DDT, p,p -DDE, p,p -DDD, and p,p -DDT. a-BHC and hexachlorobenzene (HCB) have a common peak. They can be separated on a column filled with 2.5% Silicone Oil XE-60 (Is-cyanoethyl-methylsilicone) on Chromosorb W (80-100 mesh). 

Lindane is absorbed from the gastrointestinal tract, the respiratory tract, and skin. The metabolism of lindane is complex and involves a number of pathways depending on which isomer of hexachlorocyclohexane (HCH) is involved (lindane is the gamma (y) isomer). It is nonetheless rapid. Lindane is metabolized in the liver by microsomal enzymes. The main pathways include stepwise elimination of chlorines to form tri- and tetrachloro-phenols and conjugation with sulfates or glucuron-ides and subsequent elimination. Other metabolic pathways involve the production of mercaptura-tes. These water-soluble products are eliminated in the urine. Lindane is bound by serum proteins in the blood. Storage is in adipose tissue and other... 

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