Insecticides aldrin

The cyclodiene insecticides aldrin, dieldrin, endrin, heptachlor, endosulfan, and others were introduced in the early 1950s. They were used to control a variety of pests, parasites, and, in developing countries, certain vectors of disease such as the tsetse fly. However, some of them (e.g., dieldrin) combined high toxicity to vertebrates with marked persistence and were soon found to have serious side effects in the field, notably in Western European countries where they were extensively used. During the 1960s, severe restrictions were placed on cyclodienes so that few uses remained by the 1980s. 

An atom economic route to the insecticide aldrin (Scheme 1.9) was developed some fifty years ago. This very potent insecticide was later banned in most countries owing to its toxicity to wild life. This example illustrates the need to look at the whole product lifecycle, not just the synthetic route. 

The insecticide heptachlor oxidizes in the soil, and becomes a more toxic epoxide, capable of remaining for a long time. The insecticide aldrin transforms in the soil into dieldrin, maintaining its toxicity [15, 30]. Mirex (FDso=300-600 mg/kg), used to fight ants, just like kelevan (FDS0=255-325 mg/kg), used to fight the Colorado beetle, transform in the soil into the more toxic chlordekon (FD50 decreases to 95-140 mg/kg) [30]. 

The insecticide heptachlor (FD50 for mice is 82 mg/kg [4]) oxidizes into an epoxy-product in living organisms this product is twice as toxic for practically all species [21, 35]. The insecticide aldrin (FD50 is 40-50 mg/ kg) oxidizes in plants, insects, and invertebrates, as well as in the soil it thus transforms into the seed protectant dieldrin (FD50 is 25-50 mg/kg), which is equally as dangerous to humans [15] aldrin => dieldrin. 

Versteeg JP, Jager KW. 1973. Long-term occupational exposure to the insecticides aldrin, dieldrin, endrin, and telodrin. Br J Ind Med 30 201-202. 

A drin and Dieldrin Metabolism.— The in vivo metabolism of the chlorinated alicyclic insecticides, aldrin and dieldrin, has been measured. Fish were exposed to l c-labelled aldrin or dieldrin for 6 hours. The metabolism of each compound was monitored by thin layer chromatography of hexane and chloroform-methanol extracts of liver homogenates, followed by liquid scintillation counting of the spots (5,15,16). 

As already mentioned, the pharmacological activity of certain drugs is lengthened in the female rat, and also the toxicity of certain compounds may be increased. Procaine is hydrolyzed more in male rats (chap. 4, Fig. 43), with consequently a lower toxicity in the sex, whereas the insecticides aldrin and heptachlor are metabolized more rapidly to the more toxic epoxides in males and are therefore less toxic to females (Fig. 5.16). 

Photolysis of 2-bromo-4,4-dimethyl-2-cyclohexenone only affords reduction, even in a nucleophilic medium343,344. Apparently, this substrate is structurally not suitable to form a vinyl cation. Formation of vinyl radical-derived products is also the main process for all vinylic halides, if their irradiation is performed in an apolar medium. Such photochemical reductive dehalogenation and especially dechlorination reactions have been extensively studied in the past, not in the least because of their importance as abiotic transformation of persistent polychlorinated environmental pollutants. Examples are the cyclodiene insecticides aldrin and dieldrin, which contain a vicinal dichloroethene chromophore. In recent... 

Even though biochemical lesions have not been identified for this group, one class of insecticides (aldrin, DDT, etc.) can reduce the toxicity of another class (parathion, etc.) in rats, suggesting a possible reason why some exposed workers seem able to withstand high exposures to these toxic substances without apparent ill effects. 

The chlorinated insecticides aldrin and heptachlor are microbiologically converted in soils into the corresponding epoxides. The products remain in the treated fields while the parent compounds are essentially absent. 

Epoxidation Epoxidation is an important microsomal reaction. For example, the cyclodiene insecticide aldrin can be oxidized to its epoxide dieldrin (as shown in Chapter 4, Figure 4.4), and heptachlor is oxidized to heptachlor epoxide. There is no great increase in toxicity in this case, but the epoxides are more environmentally persistent than their precursors. Moreover, some of the epoxides produced in the microsomal oxidation are highly reactive and can form adducts with cellular macromolecules such as proteins, RNA, and DNA, often resulting in chemical carcinogenesis. 

Researchers were also able to establish the link between declines of other predatory species such as the European sparrowhawk and the use of organo-chlorine pesticides other than DDT. For instance, the cyclodiene insecticides aldrin, dieldrin, and he-ptachlor used as seed treatments caused massive mortality of both seed-eating species and their predators. All of the insecticides had the following points in common they were highly soluble in fats and refractory to metabolism. The impacts on the predatory species typically take place in periods of food stress when fat soluble residues are released from fat stores and returned into general circulation. In a food-stressed individual, the brain remains as the most lipid rich tissue and this is where contaminants move to. Toxicity results when threshold values in brain tissue are exceeded. At sublethal levels, documented effects of cyclodiene insecticides in birds have included changes in their reproductive, social, and avoidance behaviors. 

Lithium-t-Butanol-Tetrahydrohirane. The insecticides aldrin and isodrin became attractive starting materials for the synthesis of compounds of interesting ring systems with the discovery by Bruck, Thompson, and Winstein of a simple method for effecting their dechlorination, that is, replacement of all the chlorine atoms by hydrogen. The polyhalogen compound is treated with lithium ribbon (3 g. atoms per... 

Kazantzis G, McLaughlin AIG, Prior PF Poisoning in industrial workers by the insecticide aldrin. British Journal of Industrial Medicine 21 46-51,1964... 

Epoxidation or the insertion of an oxygen atom into a carbon-carbon double bond can frequently result in the formation of products with greater environmental toxicity. Various microorganisms can catalyze the reaction of the chlorinated cyclodiene insecticides aldrin, isodrin, and heptachlor to their more toxic epoxide derivatives. 

Chlorinated organic compounds (COCs) undoubtedly represent one of the main categories of water pollutants. This is due, on one hand, to their wide use in many industrial fields from solvents to chemical industry intermediates, pesticides (chlordane, 57-74-9 [1]), fungicides (hexachlorobenzene, 118-74-1), insecticides (aldrin, 309-00-2 dieldrin, 60-57-1 endrin, 72-20-8 heptachlor, 76-44-8), dielectrics and coolants (polychlorinated biphenyls - PCBs), plasticizers (PCBs), and drugs (chloral, 75-87-6, representing the first synthetic COC, by Liebig in 1832). 

Larger polychlorinated molecules have been employed as insecticides—aldrin, DDT, chlordane, dieldrin, endrin, gammexane, and isodrin, for example. One of the earliest was DDT (r/ichloror/iphenyltrichloroethane), which is prepared by the condensation of chlorobenzene and chloral in the presence of sulfuric acid (H2SO4) ... 

The synthesis of dieldrin starts with hexachlorocyclopentadiene, and the intermediate in the synthesis is another insecticide, aldrin. Devise a synthesis and give a mechanism for each step. 

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