Fenvaleric acid

FIGURE 1.32 Stereoisomer separations of chrysanthemic acid (a) and fenvaleric acid (b) employing an 0-9-(tert-bntylcarbamoyl)qninine-based CSP in the polar-organic mode (a) and an 0-9-(2,6-diisopropylphenylcarbamoyl)quinine based CSP (b). Experimental conditions Column dimensions, 150 mm x 4mmID eluents(a)0.06%aceticacidin acetonitrile-methanol (95 5 v/v) (b) acetonitrile-0.3 M ammoninm acetate buffer (90 10 v/v) (pHa 6.0) flow rate, 0.65 mLmin temperature, 25°C detection, UV at 230 nm. (Reproduced from W. Bicker et al., J. Chromatogr. A, 1035 37 (2004). With permission.)... 

Arylalkyl ketones rearrange on treatment with phosphoryl azides to give the phosphorylated amide of fenvaleric acid (Reaction scheme 191) [526]. 

Less effective, in terms of insecticidal activity, is the asymmetric induction in the course of the addition of optically active (S)-cyanhydrine-isomer 299 to the ketene 388 of fenvaleric acid in the presence of a chiral cyclopeptide (D-Phe-D-Ala) 380 [871], optically active amines or even in the absence of any additional reagent [872]. The yield of the actual insecticidal S-aS-ester (esfenvalerate) is low. However, the overall yield in the interesting S-configurated acid component is essentially quantitative (Reaction scheme 261). 

Esfenvaleric acid/Fenvaleric acid Table B34, Appendix B, gives the two isomers arising from the hydrolysis of esfenvalerate/fenvalerate. 

Esfenvaleric/Fenvaleric acid 2-(4-chlorophenyl)-3-methylbutanoic acid CAS no. 2012-74-0 (generic)... 

Esfenvaleric/fenvaleric acids are present in two isomeric forms as shown in Table B34, Appendix B. The structures of these acids are identical and displayed in Table 3. Li et al. (2006) separated the methyl esters of the two isomers (R and S) on a chiral column by GC (Table C19, Appendix C). 

See Table 3 (3.4) for generic structure and technical name of esfenvaleric/fenvaleric acid ... 

Table C19 Separation of fenvaleric acid by HPLC, chiral column...

Pyrethroid Esters of Benzene Acetate. These insecticides have more extensive stmctural optimization in both acid and alcohol moieties. Fenvalerate [51630-58-17, a-cyano-(3-phenoxyphenyl)methyl (+)-(2R,5)"Ct"isoprop5i-4-chlorophenylacetate (24) d 1.17, vp 1.4 p.Pa at 25°C), a mixture of four isomers, is soluble in water to 0.3 mg/L The rat oral LD q is 450 mg/kg. Esfenvalerate [66230-04-4] is the (+)-2-(i, 5)-isomer (mp 59°C). The rat LD qS are 75, 458 (oral), and the rabbit dermal LD q is 2000 mg/kg. These pyrethroids are widely used general-purpose insecticides for field, vegetable, and fmit crops. 

Fenvalerate is not significantly absorbed or translocated in plants. Cotton, apples, and lettuce treated with fenvalerate contained surface residues of parent fenvalerate 8 weeks after treatment (Reed 1981). In addition to the parent compound, which accounted for 80% of all residues, identified metabolites included 3-phenoxybenzaldehyde, 3-phenoxybenzyl methylbutyric acid, and conjugates of these compounds. Half-time persistence of fenvalerate on plant surfaces is between 2 and 4 weeks, and degradation is primarily a result of weathering (Reed 1981). 

In general, these authorities agree that pyrethroids containing both a halogenated acid esterified with the a-cyano-3-phenoxybenzyl alcohol — such as fenvalerate, deltamethrin, and cyper-... 

Metabolism of the 2,S -isomers proceeds sequentially hydroxylation at the phenoxy group, hydrolysis of the cyano group, and cleavage of the ester linkage (Coats et al. 1989). Fenvalerate and the IS-isomers yield two ester metabolites in feces from hydroxylation at the 4 - and 2 -phenoxy positions. Other significant metabolites were 3-phenoxybenzoic acid and its hydroxy derivatives from the alcohol moiety, 3-(4-chlorophenyl) isovaleric acid and its hydroxy derivatives from the acid moiety, and thiocyanate and carbon dioxide from the cyano moiety (Ohkawa et al. 1979). A slow elimination rate characterizes fenvalerate and other a-cyano pyrethroids when compared with... 

Terrestrial plants are relatively unaffected by fenvalerate at recommended application rates, as judged by negligible uptake of fenvalerate from treated soils, formation of numerous fenvalerate conjugates that are pharmacologically inactive, and metabolism of the liberated cyano group into amino acids and eventually carbohydrate and protein (Miyamoto 1988). 

El-Sewedy, S.M., M.H. Mostata, E.A. El-Bassiouni, A. Abdel-Rafee, and A.H. El-Sebae. 1982. Effect of fenvalerate on kynurenine metabolizing enzymes and acid ribonuclease of mouse liver. Jour. Environ. Sci. Health B17 571-579. 

Ohkawa, H., R. Kikuchi, and J.S. Miyamoto. 1980. Bioaccumulation and biodegradation of the (S)-acid isomer of fenvalerate (Sumicidin ) in an aquatic model ecosystem. Jour. Pestic. Sci. 5 11-22. 

Figure 8b shows pyrethroid esters composed of an acid moiety without a cyclopropane ring and a phenoxybenzyl alcohol group. While a cyclopropane ring had long been considered an indispensable acid component constituting a pyrethroid skeleton, Ohno et al. [41] in 1974 developed fenvalerate (32), a-isopropylphenyl acetate derivative, with no cyclopropane ring in its acid moiety. This compound exhibits... 

In addition, three types of lipophilic conjugates have been found in pyrethroid metabolism studies (Fig. 4). They are cholesterol ester (fenvalerate) [15], glyceride (3-PBacid, a common metabolite of several pyrethroids) [16], and bile acid conjugates (fluvalinate) [17]. It is noteworthy that one isomer out of the four chiral isomers of fenvalerate yields a cholesterol ester conjugate from its acid moiety [15]. This chiral-specific formation of the cholesterol ester has been demonstrated to be mediated by transesterification reactions of carboxylesterase(s) in microsomes, not by any of the three known biosynthetic pathways of endogenous cholesterol esters... 

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