- Screening of by-products of esfenvalerate in aqueous medium using SBSE probe desorption GC-IT-MS technique
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The pyrethroids, their metabolites and by-products have been recognized as toxic to environment and human health. Despite several studies about esfenvalerate toxicity and its detection in water and sediments, information about its degradation products is still scanty. In this work, esfenvalerate degradation products were obtained by chemical oxidation with hydrogen peroxide and their structure was elucidated using a procedure known as stir bar sorptive extraction (SBSE) probe desorption gas chromatography-ion trap mass spectrometry (GC-IT-MS) analysis. This procedure consists of the thermal desorption of analytes extracted from a SBSE stir bar introduced by a probe into a gas chromatograph (GC) coupled to an ion trap mass spectrometry (IT-MS) system. Based on IT-MS data, a degradation pathway of esfenvalerate is proposed with ten products of chemical oxidation of esfenvalerate that are fully identified. Among these compounds, 3-phenoxybenzoic acid and 3-phenoxybenzaldehyde were detected, reported as being environmental metabolites of some pyrethroids, with endocrine-disrupting activity.
- Colombo, Renata,Ferreira, Tanare C. R.,Yariwake, Janete H.,Lanza, Marcos R. V.
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p. 1831 - 1837
(2015/09/22)
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- The first synthetic agonists of FFA2: Discovery and SAR of phenylacetamides as allosteric modulators
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Free fatty acid receptor 2 (FFA2) is a G-protein coupled receptor for which only short-chain fatty acids (SCFAs) have been reported as endogenous ligands. We describe the discovery and optimization of phenylacetamides as allosteric agonists of FFA2. These novel ligands can suppress adipocyte lipolysis in vitro and reduce plasma FFA levels in vivo, suggesting that these allosteric modulators can serve as pharmacological tools for exploring the potential function of FFA2 in various disease conditions.
- Wang, Yingcai,Jiao, Xianyun,Kayser, Frank,Liu, Jiwen,Wang, Zhongyu,Wanska, Malgorzata,Greenberg, Joanne,Weiszmann, Jennifer,Ge, Hongfei,Tian, Hui,Wong, Simon,Schwandner, Ralf,Lee, Taeweon,Li, Yang
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scheme or table
p. 493 - 498
(2010/04/26)
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- Purification and characterization of a novel pyrethroid hydrolase from Aspergillus niger ZD11
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The pyrethroid pesticides residues on foods and environmental contamination are a public safety concern. Pretreatment with pyrethroid hydrolase has the potential to alleviate the conditions. For this purpose, a fungus capable of using pyrethroid pesticides as a sole carbon source was isolated from the soil and characterized as Aspergillus niger ZD11. A novel pyrethroid hydrolase from cell extract was purified 41.5-fold to apparent homogeneity with 12.6% overall recovery. It is a monomeric structure with a molecular mass of 56 kDa, a pl of 5.4, and the enzyme activity was optimal at 45°C and pH 6.5. The activities were strongly inhibited by Hg2+, Ag+, and p-chloromercuribenzoate, whereas less pronounced effects (5-10% inhibition) were observed in the presence of the remaining divalent cations, the chelating agent EDTA and phenanthroline. The purified enzyme hydrolyzed various insecticides with similar carboxylester. trans-Permethrin is the preferred substrate.
- Liang, Wei Q.,Wang, Zhuo Y.,Li, He,Wu, Pei C.,Hu, Ji M.,Luo, Na,Cao, Li X.,Liu, Yu H.
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p. 7415 - 7420
(2007/10/03)
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- A Rearrangement Route to Fenvaleric Acid
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(±)-Fenvaleric acid 2, the key intermediate for the preparation of the pesticide esfenvalerate 1, was prepared by a novel sequence which first involves the Henry reaction of 2-methyl-1-nitropropane and 4-chlorobenzaldehyde. The nitroaldol reaction provided nitroalcohol 5 which was then reduced to the corresponding aminoalcohol 6. Submission of 6 to an aminopinacol rearrangement promoted by nitrous acid deamination then afforded aldehyde 8 through a 1,2-aryl shift. The product fenvaleric aldehyde 8 was then converted to the title compound 2 by a modified Jones oxidation.
- Luzzio, Frederick A.,Fitch, Richard W.
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p. 498 - 501
(2007/10/03)
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- Studies on the synthesis of chiral 2-(p.chlorophenyl)-3-methylbutanoic acid, a key-precursor of Fenvalerate, by hydrocarbonylation reactions
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The preparation of racemic 2-(p.chlorophenyl)-3-methylbutanoic acid (2), a building block for (S,S)-Fenvalerate (an important broad spectrum insecticide), was effected by rhodium catalyzed hydroformylation of 2-methyl-1 -(p.chlorophenyl) propene (4) in the presence of excess of triphenylphosphine to inhibit substrate isomerization followed by mild oxidation of the resulting aldehyde 6; an overall yield of 88% was reached. Olefin 4 exhibits a very low tendency to undergo both hydrocarboethoxylation and hydrocarboxylation in the presence of palladium complexes as catalysts. Enantioselective hydrocarbonylation reactions carried out on olefin 4 afford unsatisfactory chemical and optical yields of the optically active ester 5 or acid 2. Springer-Verlag 1996.
- Botteghi, Carlo,Bona, Denis Dalla,Paganelli, Stefano,Marchetti, Mauro,Sechi, Barbara
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p. 101 - 107
(2007/10/03)
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- Asymmetric Catalytic Alkylation of 4-Chlorophenylacetic Acid
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Using N-(monoalkyl)-α,β-diphenyl-β-hydroxy ethylamine as chiral ligands, 46.2percent enantiomeric excess was obtained in the asymmetric catalytic alkylation of 4-chlorophenylacetic acid.
- Mi, A. Q.,Wang, Z. Y.,Jiang, Y. Z.
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p. 1957 - 1960
(2007/10/02)
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- Process for the preparation of 2-(4-chlorophenyl)-3-methylbutyric acid
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A process for the preparation of 2-(4-chlorophenyl)-3-methylbutyric acid from 4-chlorobenzaldehyde by conversion of the benzaldehyde to 3-(4-chlorophenyl)-2-methylpropenal, 3-(4-chlorophenyl)-2-methylpropanol, 1-(4-chlorophenyl)-2-methylpropene-1, and 2-(4-chlorophenyl)-2-methylbutyraldehyde, and finally to the desired corresponding butyric acid.
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- Racemization of optically active 2-(4-chlorophenyl)-3-methylbutyric acid
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A method for racemization of optically active 2-(4-chlorophenyl)-3-methylbutyric acid which comprises the steps of (a) reacting optically active 2-(4-chlorophenyl)-3-methylbutyric acid with a hydroxide or carbonate of an alkali metal or alkaline earth metal at a temperature of more than 110° C. to produce a racemate of the alkali metal or alkaline earth metal salt of the above acid, and (b) converting the resulting racemate of the salt to the acid.
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- (S) α-Cyano-3-phenoxy-benzyl alcohol
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(S) α-cyano-3-phenoxy-benzyl alcohol having the formula STR1 and a novel process for its preparation and novel intermediates.
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- Inert organic solvent dispersion of alkali hydroxide and reaction using the same
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An inert organic solvent dispersion of alkali hydroxide is prepared by mixing an alkali hydroxide, an inert organic solvent and a stabilizer and heating and stirring at the temperature for forming the pasty alkali hydroxide and cooling the dispersion. The dispersion of alkali hydroxide is used in a reaction of an active methylene compound with an organoalkyl halide such as a reaction of a halophenylacetonitrile with an isopropyl halide to obtain α-isopropyl halophenylacetonitrile.
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- Substituted pyridine methyl esters of 2-isopropyl-2-(4-chlorophenyl)acetic acid and their use as insecticides
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Substituted pyridine methyl esters of 2-isopropyl-2-(4-chlorophenyl)acetic acid are prepared which correspond to the formula: STR1 wherein n represents an integer of 0 to 2; X independently represents alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, alkylthio of 1 to 4 carbon atoms, alkylsulfinyl of 1 to 4 carbon atoms, alkylsulfonyl of 1 to 4 carbon atoms, trifluoromethyl, nitro, cyano, chloro, fluoro, bromo, or 3,4-methylenedioxy (when n is 2 and both X's are taken together); and R represents hydrogen, cyano or ethynyl. These compounds have been found to exhibit a high degree of insecticidal activity and compositions containing said compounds are so employed.
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- Process for preparing phenyl-acetic acid esters
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A process for preparing a substituted phenyl-acetic acid ester of the formula (I), SPC1 wherein R1 is an ethyl group or an isopropyl group, R2 is a hydrogen atom, a C1 -C4 alkyl group, a methoxy group, a halogen atom or a methylenedioxy group, which comprises reacting a quaternary ammonium salt of the formula (III), SPC2 wherein X is a halogen atom, and A is an alkylamine, pyridine or an N-alkylaniline, with a carboxylic acid of the formula (II), SPC3 wherein R1 and R2 are each as defined above, its reactive derivative, or a mixture of the acid and its reactive derivative.
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