Deltamethrin structure

The structures of some pyrethroid insecticides are shown in Figure 12.1. They are all lipophilic esters showing some structural resemblance to the natural pyrethrins. They can all exist in a number of different enantiomeric forms. Permethrin, cypermethrin, and deltamethrin, for example, all have three asymmetric carbon atoms... 

Figure 15.5 Structures of the natural pyrethrins and the synthetic analogs permethrin and deltamethrin. Data from [136, 141].

Figure 3.46 a Catalytic oxidation of 3-carene to 3-caren-5-one b molecular structure of Deltamethrin, showingthe incorporation of the carenone precursor in the final product. 

Tessier, J. Structure, Synthesis and Physical-Chemical Properties of Deltamethrin. In Deltamethrin Monograph Tessier, J., Ed. Roussel-Uclaf Paris, 1982 pp 37-66 translated by B. V. d. G. Walden. 

An important characteristic of the pyrethroid-generated tail current is that its amplitude and duration are independent. The current amplitude is dependent only on the proportion of sodium channels modified, and hence shows a saturable relationship with pyrethroid concentration or dose. The current duration however is dependent only on the pyrethroid structure some pyrethroids, such as permethrin holding the channel open for a few milliseconds and others, such as deltamethrin, holding it open for tens of milliseconds. Individual pyrethroids thus generate a characteristic time constant for prolongation of the sodium channel tail current that is virtually independent of dose. 

Pyrethroids may conveniently be classified into two groups based on the chemical structure and toxic action (1 -Z8). Type I pyrethroids do not possess an alpha-cyano group and include many conventional ones such as allethrin, tetramethrin, phenothrin and permethrin. Type II pyrethroids possess a cyano group at the a position and include cyphenothrin, cypermethrin, deltamethrin and fenvalerate. 

In the last century, the development of organophosphorus, carbamate, and organochloride insecticides was followed by synthetic pyrethroids. As a result, pyrethroids are now used frequently in the domestic milieu. Pyrethroid insecticides are synthetically derived from the molecular structure or sharing the same mechanism of action of natural pyrethrins that have broader spectmm of activity, more stability, and residual activity (persists longer than that of natural pyrethrins) and include the following allethrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, fenvalerate, flumethrin, fluvalinate, tau-fluvalinate, and permethrin (see structure in Fig. 137.2). They are lipophilic compounds and generally of low acute oral toxicity to mammals but are very toxic to aquatic organisms. When synthetic pyrethroids are administered to mammals parenterally, the synthetic pyrethroids are neurotoxic. 

Pyrethroid insecticides are generally classified into one of two large groups on the basis of the central neurotoxic syndrome that they produce [5, 6]. Type I pyrethroids are esters of chrysanthemic acid and an alcohol, having a furan ring and terminal side chain moieties, and absence of a cyano moiety. Allethrin was the first pyrethroid identified in 1949. Allethrin and other pyrethroids such as phenothrin and permethrin with the basic cyclopropane carboxylic ester structure are type I pyrethroids. The insecticidal activity of these synthetic pyrethroids was enhanced further by the addition of a cyano group to give ot-cyano type II pyrethroids such as deltamethrin, fenvalerate, cyfluthrin, cyhalothrin, and lambda-cyhalothrin (Fig. 137.2). 

Synthetic analogs of the pyrethrins, pyrethroids, have been widely produced as insecticides during recent years. The first of these was allethrin, and another common example is fenvalerate (see structural formulas in Figure 4.6). Other examples of insecticidal pyrethroids that have water pollution potential include cypermethrin and deltamethrin. Because of the ways that they are applied and their biodegradabilities, these substances generally are not found to be significant water pollutants. 

In Table 3, we present the structures and names of the chrysanthemic acids that are used in the synthesis of allethrin, cyfluthrin, deltamethrin, permethrin, fenvalerate, phenothrin, resmethrin, and tetramethrin. These acids (isomers), depicted in Tables B31-B35, Appendix B, are released during metabolism and are excreted in the urine of exposed animals. A short discussion of each acid and their isomers is presented in the following paragraphs. 

A preliminary physiological model for allethrin is presented in Fig. IF, Appendix F. Preliminary ACSL-based physiological models were also written for deltamethrin, cisitrans permethrin, and cisitrans resmethrin (Knaak, unpublished). A PBPK model was developed for deltamethrin (Mirfazaelian et al. 2006 Godin et al. 2010 Tornero-Velez et al. 2010) to assess internal dose levels in various organs and tissues of rats and humans. Deltamethrin was selected to represent the disposition of the pyrethroids, because it is structurally similar to other commercial... 

See Table 2 (2.6) for generic structure and technical name of deltamethrin. OR = Optical rotation... 

Table D6 Chemical structure, physical and chemical properties, and tissue partition coefficients for deltamethrin and resulting metabolites...

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