Lindane physical

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. 

Results of volatilization and leaching estimations are reported for six pesticides that span a wide range of the physical/chemical properties that affect fate at the soil/air interface. The pesticides are Mirex, toxaphene, methoxychlor, lindane, malathion, and dibromochloropropane (DBCP). These particular pesticides were chosen for discussion here because they illustrate the methods for assessing the fate of organics at the... 

Saleh, F.Y., Dickson, K.L., and Rodgers, J.H., Jr. Fate of lindane in the aquatic environment rate constants of physical and chemical processes. Environ. Toxicol. Chem., l(4) 289-297, 1982. 

The first production of this group of compounds started in 1943. The production of lindane (y-HCH) in developed countries has been estimated to be 720,000 tonnes. The global production of technical-grade HCHs over the period between 1948 and 1997 has been estimated to be 10 million tonnes. Today, the production and use of HCHs have been strongly reduced due to the international restriction. The principal emission sources of this group of compounds are shown in Fig. 3. Their physical-chemical properties are summarised in Table 1. 

The most fundamental properties of a chemical substance are those of the substance in pure form, in most cases as a solid or liquid. Molecular mass can be deduced readily from the chemical formula or structure, although a range of values may exist for commercial mixtures. In some cases, the substance may adopt different structural (e.g., cis-trans) or enantiomeric forms, usually with relatively small physical property differences but with potentially substantial differences in ability to induce toxicity or other biological responses. The hexachlorocyclohexane isomers and enantiomers are examples, the insecticide lindane or y HCH being the most active form. 

Demozay, D., Marechal, G. (1972) Physical and chemical properties in lindane Monograph of an insecticide, E. Ulman, pp. 15-21, K. Schiller, Freiburg im Breisgau. 

Six isomers are separated from industrial products cl i S C They have slightly different physical characteristics. Only the 3T BHC is effective as insecticide. Industrial products generally contains d BHC and only 815% Y BHC. TheY BHC which is separated from the industrial products to more than 99% purity is called "Lindane". It is best to use the Li-product from the manufacture of Lindane. for firework material. 

Sorption phenomena are well described and documented in the basic scientific hterature [1] and standard physical chemistry texts [2-4]. Indoor air researchers first reported extensively on adsorption to and desorption from indoor surfaces in 1987 at the 4th International Conference on Indoor Air Quahty and Climate in Berlin where Seifert and Schmal [5] reported the sink effects of plywood and carpet exposed to lindane and a mixture of 20 volatile organic compounds (VOCs). The Berlin conference also provided data from two studies that examined the sink effect of textiles [6,7]. Finally, Skov and Valbjorn [8] reported on the seminal Danish town hall study. They concluded that sorption to and from large surface areas and fleecy materials was associated with lAQ problems. This work was followed up by Nielsen [9] at Healthy Buildings 88 in Stockholm, where he reviewed several studies on the importance of sorption processes on lAQ. Also in Stockholm, Berglund and her colleagues [10] provided an extensive hterature review and discussion of lAQ data leading to the conclusion that sink effects are important. They also provided the results of a study on adsorption and desorption in a ventilation system. Since then, numerous overviews have been presented on the importance of sink effects on lAQ [11,12]. 

Demozay, D. Marechal, G. Physical and Chemical Properties in Lindane Monograph of an Insecticide," E. Ulmann 1972,... 

Acute CH poisonings manifest with numerous symptoms (see Table 4-2). Few psychiatric effects appear in the acute stages. Most symptoms, such as irritability and confusion, result from acute physical illness and shock. The cyclodienes, not DDT or its related derivatives, produce the most severe symptoms in Table 4-2. One case report described seizures resulting from the concomitant use of lindane for treatment of head lice with dextroamphetamine for treatment of at-tention-deficit/hyperactivity disorder (ADHD) (Cox et al. 2000). 

For arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, endrin, lindane, methoxychlor, toxaphene, 2,4-D (2,4-dichloro-phenoxyacetic acid) or 2,4,5-TP (2,4,5-trichlorophenox3q>ropionic acid) Test Methods for the Evaluation of Solid Waste, Physical/Chemical Methods . 

Toxaphene, lindane, chlordan, and heptachlor were adsorbed by soil particulate matter (158, 216, 255, 261, 268, 279, 291, 295, 299, 301, 302, 303, 304, 305) and volatilized from aqueous (292, 297) and soil (255, 264, 275, 280, 283, 293, 306) systems in a way analogous to that of aldrin, dieldrin, and endrin. Adsorption of the pesticides was most highly related to the organic matter content of soils and aquatic systems and probably occurred through weak physical intermolecular forces at lipophilic sites. Adsorbing and volatizing processes were involved in the fate of these compounds in aquatic and soil systems. Lindane was much more mobile in soil systems than the others (246, 255), probably because of its greater solubility (Table VI), and lindane and heptachlor volatilized much more readily from soils and aquatic systems (290, 292, 293, 296, 306). 

A. Adsorption. The physical adsorption of the nonionic, nonpolar chlorinated pesticides, lindane and toxaphene, were measured in two types of polymers ionic exchange resins and nonionic styreneidivinylbenzene polymers.The following results were obtained ... 

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