3-Phenoxybenzyl alcohol

It was then stirred and refluxed for 8 hours. About 400 ml of methanol was distilled out and the remaining solution was evaporated to about one-third its original volume in vacuo and poured into ice water. This mixture was extracted twice with ether, acidified with 6N HCI, and again extracted with ether. The ether extracts were combined, washed with saturated NaCI solution, dried over anhydrous sodium sulfate, and evaporated in vacuo. The residual oil was distilled through a 15 cm Vigreux column, yielding 666 grams of a-methyl-3-phenoxybenzyl alcohol, BP 132° to 134°C (0.35 mm), no = 1.5809. 

Synthetic pyrethroids are esters of specific acids (chrysantemic acid, halo-substituted chrysantemic acid, 2-[4-chlorophenyl]-3-methylbutyric acid) and alcohols (allethrone, 3-phenoxybenzyl alcohol) (Ray, 1991). They represent a group of insecticides largely used in agriculture and public health because of their relatively low toxicity to humans and mammalian species and their short environmental persistence. 

Synthetic pyrethroids now account for at least 30% of the world insecticide market and are rapidly replacing other agricultural chemicals for control of insect pests. Fenvalerate is one of the more widely used synthetic pyrethroid insecticides. It is derived from a combination of a-cyano-3-phenoxybenzyl alcohol and a-isopropyl phenylacetate ester. Technical fenvalerate is a mixture of four optical isomers, each occurring in equal amounts but with different efficacies against insect pests. Fenvalerate does not usually persist in the environment for >10 weeks, and it does not accumulate readily in the biosphere. Time for 50% loss (Tb 1/2) in fenvalerate-exposed amphibians, birds, and mammals was 6 to 14 h for reptiles, terrestrial insects, aquatic snails, and fish it was >14 h to <2 days and for various species of crop plants, it was 2 to 28 days. Fenvalerate degradation in water is due primarily to photoactivity, and in soils to microbial activity. Half-time persistence in nonbiological materials is variable, but may range up to 6 days in freshwater, 34 days in seawater, 6 weeks in estuarine sediments, and 9 weeks in soils. 

The first significant success in creating a photostabilized pyrethroid with high insecticidal activity was achieved through use of the 3-phenoxybenzyl alcohol moiety. A further step was the finding that 2-aryl-3-methylbutyric acid esters of pyrethroid alcohols were both photostable and... 

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-... 

Dogs produce 3-phenoxybenzyl alcohol and 3-(4 -hydroxyphenoxy) benzyl alcohol, whereas rodents do not. 

Phenoxybenzoic acid, see Cvpermethrin. Permethrin Phenoxybenzyl alcohol, see Permethrin 3-Phenoxybenzyl alcohol, see Permethrin... 

CASRN 52645-53-1 molecular formula C21H20CI2O3 FW 391.29 Soil. Permethrin biodegraded rapidly via hydrolysis yielding 3-(2,2-dichloroethenyl)-2,2-di-methylcyclopropanecarboxylic acid and 3-phenoxybenzyl alcohol (Kaufman et al., 1981). The reported half-life in soil containing 1.3-51.3% organic matter and pH 4.2-7.7 is <38 d (Worthing and Hance, 1991). 

Efficient biochemical processes were developed for the preparation of the two optically active pyrethroid insecticides by a combination of enzyme-catalyzed reactions and chemical transformations. These are based on the findings that a lipase from Arthrobacter species hydrolyzes the acetates of the two important secondary alcohols of synthetic pyrethroids with high enantioselectivity and reaction rate. The two alcohols are 4-hydroxy-3-methy1-2-(2 -propynyl)-2-cyclopentenone (HMPC) and a-cyano-3-phenoxybenzyl alcohol (CPBA). The enzyme gave optically pure (R)-HMPC or (S)-CPBA and the unhydrolyzed esters of their respective antipodes. 

Replacement of the normal pyrethroid ester by alternative linkages usually leads to diminution of biological activity. One important exception to this general phenomena is several oxime ether derivatives, in particular, 3-phenoxybenzyl derivatives of various alkyl aryl ketones. Pyrethroid esters derived from certain 2-substituted-[1,1 -biphenyl]-3-methanols have been shown to possess initial and residual activity surpassing that of esters derived from 3-phenoxybenzyl alcohol. Now it has been demonstrated that the same enhancement of activity was observed for alkyl aryl oxime ethers of certain [1,1 -biphenyl]-3-methanols compared to the corresponding 3-phenoxybenzyl alcohol derived oximes. The synthesis, biological activity, including soil activity, structure-activity relationships and toxicity of several of these biphenylmethyl oxime ethers are described. 

The first question of interest was to compare 2-methyl[1,1 -biphenyl]-3-methanol with 3-phenoxybenzyl alcohol when combined with the oximes of certain alkyl aryl ketones. The enhancement in... 

The replacement of the 3-phenoxybenzyl alcohol fragment by 2-methyl[1,1 -biphenyl]-3-yl leads to an increase in initial and residual foliar activity in the alkyl aryl oxime ethers. An unanticipated result was the activity of these oxime ethers as soil insecticides. The corresponding 3-phenoxybenzyl alcohol oxime ethers were inactive as soil insecticides. The results of a structure activity relationship study revealed biological activity is enhanced by electron withdrawing substituents. 

The pyrethroids and DDT are by far the most important insecticides in this category. According to their modes of action, they are sometimes classified into two types. Type 1 includes DDT, its analogues, and pyrethroids without a cyano group, whereas type 2 compounds include the pyrethroids with an a-cyano-3-phenoxybenzyl alcohol. In mammals, they give slightly different symptoms by poisoning. Type 1 causes whole-body tremors, whereas type 2 causes salivation and choreoathetosis. Insects also show different symptoms, but not so distinct. 

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