Insecticides epoxides

Pyrethroids from Chiysanthemic Acid. The unsaturated side chains of the aHethrolone alcohol moieties of the natural pyrethrins are readily epoxidized by microsomal oxidases and converted to diols, thus detoxifying the insecticides. Esterification of chrysanthemic acid (9), R = CH3, with substituted ben2yl alcohols produces usehil insecticides barthrin [70-43-9J, 2-chloro-3,4-methylenedioxyben2yl (+)-i7j ,/n7 j -chrysanthemate, and dimethrin [70-38-2] 2,4-dimethylben2yl (+)-i7j ,/n7 j -chrysanthemate. These have alimited spectmm of insecticidal activity but are of very low mammalian toxicity, ie, rat oralLD s >20,000 mg/kg. 

Dieldrin [60-57-1] or l,2,3,4,10,10-hexachloro-l,4,4t ,5,8,8t -hexahydro-6,7-epoxy-l,4- <7o, Aro-5,8-dimethanonaphthalene (34) (mp 176°C, vp 0.4 mPa at 20°C) is formed from aldrin by epoxidation with peracetic or perben2oic acids. It is soluble in water to 27 / g/L. Aldrin and dieldrin have had extensive use as soil insecticides and for seed treatments. Dieldrin, which is very persistent, has had wide use to control migratory locusts, as a residual spray to control the Anopheles vectors of malaria, and to control tsetse flies. Because of environmental persistence and propensity for bio accumulation, registrations in the United States were canceled in 1974. 

Endrin [72-20-8] is l,2,3,4,10,10-hexachloro-l,4,4t ,5,8,8t -hexahydro-6,7-epoxy-l,4- <7o, <7o-5,8-dimethanonaphthalene (35) (mp 245 dec, vp 0.022 mPa at 25°C) and is soluble in water to 23 / g/L. It is produced by a Diels-Alder reaction of hexachloronorbomadiene with cyclopentadiene, followed by epoxidation. This reaction produces the endo,endo isomer of dieldrin, which is less stable and more toxic with rat LD q values of 17.8 and 7.5 (oral) and 15 (dermal) mg/kg. It is used as a cotton insecticide but because of its high toxicity to fish it has been restricted. 

Thiiranes (77) show some juvenile hormone activity, but the epoxide is often more active. Thiophosphates of 2-mercaptomethylthiirane are strong contact insecticides 2-chloromethylthiirane and4-vinyl- 1,2-epithiocyclohexane are nematocides. Severalthiirane 1 -oxides are reported to be insecticides, molluscicides and herbicides (68USP3413306). 1,2-Epithio-1,2,3,4-tetrahydronaphthalene is a mild herbicide. 

Alkylamines have a variety of applications in the chemical industry as starting materials for the preparation of insecticides and pharmaceuticals. Labetalol, for instance, a so-called /3-blocker used for the treatment of hi h blood pressure, is prepared by SN2 reaction of an epoxide with a primary amine. The substance marketed for drug use is a mixture of all four possible stereoisomers, but the biological activity derives primarily from the (R,R) isomer. 

As mentioned earlier (Figure 5.5), aldrin and heptachlor are rapidly metabolized to their respective epoxides (i.e., dieldrin and heptachlor epoxide) by most vertebrate species. These two stable toxic compounds are the most important residues of the three insecticides found in terrestrial or aquatic food chains. In soils and sediments, aldrin and heptachlor are epoxidized relatively slowly and, in contrast to the situation in biota, may reach significant levels (note, however, the difference between aldrin and dieldrin half-lives in soil shown in Table 5.8). The important point is that, after entering the food chain, they are quickly converted to their epoxides, which become the dominant residues. 

In one example (Lawrence and Casida 1984, Abalis et al. 1985) rat brain microsacs were used to test the action of cyclodiene insecticides such as dieldrin and endrin on the GABA receptors contained therein. The influx of radiolabeled CL into the microsacs via the pore channel of the receptor was inhibited by these chemicals. A similar assay was developed using microsacs from cockroach nerve. Assays with this preparation showed again the inhibitory effect of a cyclodiene (this time heptachlor epoxide) on CL influx. Also, that microsacs from cyclodiene resistant cockroaches were insensitive to the inhibitory effect of picrotoxinin, which binds to the same site on the GABA receptor (Kadous et al. 1983). 

To test further the accuracy of the method, synthetic mixtures of Compound 118 with its insecticidally active epoxide derivative, Compound 497, were prepared (2). The results, shown in Table III, indicate that Compound 118 can accurately be determined in the presence of gross amounts of structurally related material. 

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]. 

Dining the blending of the two insecticides (endrin is a halogenated polycyclic epoxide) into a petroleum solvent, an unexpected exothermic reaction occurred which vaporised some solvent and led to a vapour-air explosion. Faulty agitation was suspected. 

The procedure described by Suzuki et al. [11, 12], discussed in section 9.1.1.1 for the determination of chlorinated insecticides in soils has also been applied to hexane extracts of river sediments using high-resolution gas chromatography with glass capillary columns. Minimum detectable levels of a-BHC, fs-BHC, -BHC, P-BHC, Heptachlor, Heptachlor epoxide, Aldrin, Dieldrin, Endrin, p,p -DDE, p,p -TDE and p,p -DDT in lOOg samples of bottom sediment were 0.0005, 0.0032, 0.0014, 0.0040, 0.0012, 0.0020, 0.0014, 0.0020, 0.0056, 0.0032, 0.0080 and 0.0120mg kgr1 respectively. 

Savage EP, Keefe TJ, Tessari JD, et al. 1981. National study of chlorinated hydrocarbon insecticide residues in human milk, USA I. Geographic distribution of dieldrin, heptachlor, heptachlor epoxide, chlordane, oxychlordane, and mirex. Am J Epidemiol 113(4) 413-422. 

In the case of insecticides, this oxidation converts the precursor to a product which is more toxic (e. g., the conversion of Heptachlor and Aldrin to epoxides). 

Our final (and contrasting) examples are dieldrin (10.135) and endrin (10.136), two isomeric polychlorinated insecticides that contain exo-epoxide... 

Heptachlor epoxide is a breakdown product of heptachlor. It was not manufactured and was not used as an insecticide like heptachlor. Like pure heptachlor, heptachlor epoxide is a white powder that does not explode easily. Heptachlor epoxide is made by bacteria in the environment. Animals and people also make heptachlor epoxide when heptachlor enters their bodies. This profile describes these two chemicals together because about 20% of heptachlor is changed within hours into heptachlor epoxide in the environment and in your body. 

No studies were located regarding death in humans after oral exposure to heptachlor or heptachlor epoxide. However, since heptachlor is a major component of the insecticide chlordane, chlordane poisoning can be considered when evaluating heptachlor toxicity data. In the case study of a woman who ingested 6 g of chlordane with suicidal intent and died 9.5 days following ingestion, no information was presented on the composition of the chlordane. Therefore, the amount of heptachlor exposure is unknown, and the effect of other components of chlordane cannot be ruled out (Derbes et al. 1955). 

Organochlorine insecticide residues were determined in samples of human milk, evaporated milk, and prepared baby formulas from various regions of Canada (Ritcey 1972). A mean concentration of 0.003 mg/kg of heptachlor epoxide was detected in human milk, with significantly lower levels in evaporated milk and prepared baby formulas. 

In the past (prior to 1974), exposure of humans to heptachlor and heptachlor epoxide was directly related to the application of heptachlor as an insecticide. However, because of the persistence and bioaccumulation of heptachlor and heptachlor epoxide, exposure of the general population can occur through ingestion of contaminated food (especially cow s or maternal human milk), inhalation of vapors from contaminated soil and water, or direct contact with residual heptachlor from pesticide application. People whose homes have been treated may continue to be exposed to these chemicals in the air over long periods. Occupational exposure can occur in the manufacture of the chemical or from use of heptachlor to control fire ants. The most likely routes of exposure at hazardous waste sites are unknown. Heptachlor has been found infrequently in soil and groundwater at hazardous waste sites. Children who eat contaminated soil or people who obtain tap water from wells located near hazardous waste sites might be exposed to heptachlor. Also, since both compounds can volatilize from soil, people living near hazardous waste sites may be exposed to the compounds in the air. 

Heptachlor and heptachlor epoxide have been found in human milk samples (Al-Omar et al. 1986 Fytianos et al. 1985 Larsen et al. 1971 Mes et al. 1986 Ritcey 1972 Savage et al. 1981). Breast milk samples (n=210) taken from Canadian women from five different regions who had resided in Canada for at least 5 years were analyzed for chlorinated hydrocarbon contaminants as part of a monitoring program. Trends from 1967 to 1982 showed heptachlor epoxide levels decreased from a mean of 3 ppb in 1967 to a mean of <1 ppb in 1982 (maximum, 7 ppb) (Mes et al. 1986). Heptachlor epoxide was found in 62% of all samples taken in 1982 (Mes et al. 1986). Human milk samples obtained from 1,436 women residing in the United States were analyzed for chlorinated hydrocarbon insecticides. While heptachlor was recovered in less than 2% of the samples, heptachlor epoxide... 

Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), all uses of heptachlor and heptachlor epoxide were canceled in 1978, except for use in subsurface control of subterranean termites and for dipping of roots and tops of nonfood plants (ERA 1985c FDA 1989c). 

Gillett JW, Chan TM. 1968. Cyclodiene insecticides as inducers, substrates, and inhibitors of microsomal epoxidation. J Agric Food Chem 16 590-593. 

Synonyms AI3-17251 BRN 0091397 CCRIS 276 Caswell No. 423 Compound 269 ED EINECS 200-775-7 EN 57 Endrex Endricol Endrine ENT 17251 EPA pesticide chemical code 041601 Experimental insecticide 269 Hexachloroepoxyoctahydro-e/ r/o,e/ r/o-dimethanonaphtha-lene l,2,3,4,10,10-Hexachloro-6,7-epoxy-l,4,4a,5,6,7,8,8a-octahydro-enr/o,e/ c/o-l,4 5,8-dimeth-anonaphthalene 3,4,5,6,9,9-Hexachloro-la,2,2a,3,6,6a,7,7a-octahydro-2,7 3,6-dimethano-naphth[2,3-A]oxirene Hexadrin Isodrin epoxide Mendrin NA 2761 NCI-C00157 Nendrin NSC 8935 Octanex QMS 197 RCRA waste number D013 RCRA waste number P051 Stardrin Stardrin 20 UN 2761. 

Richardson s interest in these trehalose epoxides stemmed from his desire to prepare a wide range of modified trehalose analogues for evaluation as inhibitors of the trehalase of insects, as trehalose is known to be the storage carbohydrate of many insects and good inhibitors of this processing enzyme could potentially function as green insecticides. 

Heptachlor epoxide Pesticide - organochlorine - bioaccumulates - heptachlor epoxide is a breakdown product of heptachlor, an insecticide from 1953 to 1974 in US on a wide range of insects. Most use canceled in 1974 and importation and manufacture prohibited in the US, use banned in 1988... 

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