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Hydrolysis
Published in Richard A. Larson, Eric J. Weber, Reaction Mechanisms in Environmental Organic Chemistry, 2018
Richard A. Larson, Eric J. Weber
Bis(2-ethylhexyl)phthalate, a large volume plasticizer, is fairly resistant to hydrolysis (t1/2 = 100 y at pH 8), suggesting that it will be fairly persistent in aquatic environments if hydrolysis is the primary reaction pathway (Wolfe et al., 1980). Fenpropathrin, which is a synthetic pyrethroid with high insecticidal activity and low mammalian toxicity, undergoes hydrolysis to give fenvaleric acid and the cyanohydrin, which rapidly loses the cyano group to give 3-phenoxybenzaldehyde (Takahashi et al., 1985a). Fenpropathrin is susceptible to neutral and base-catalyzed hydrolysis. Over the pH range of 5 to 9, the hydrolysis half-life for fenpropathrin will range from 8520 d to 11.3 d. The hydrolysis kinetics for fenpropathrin are typical of the synthetic pyrethroids (Camilleri, 1984 and Takahashi et al., 1985b). Because of their degradability and extreme potency, the synthetic pyrethroids have become a popular alternative for the more environmentally persistent chlorohydrocarbons. The hydrolysis kinetics of chlorobenzilate, which is an acaracide (chemical agents used for the control of mites), have not been reported in the literature. Based on the hydrolytic behavior of other similar carboxylic acid esters, the hydrolysis half-life for chlorobenzilate at pH 7 at 25°C is expected to be 1 to 2 years.
Long term bioassessment multiple stressors study in a residential California stream
Published in Journal of Environmental Science and Health, Part A, 2021
Lenwood W. Hall, William D. Killen, Ronald D. Anderson, Raymond W. Alden
The pyrethroids bifenthrin, cypermethrin, cyfluthrin, deltamethrin, esfenvalerate, fenpropathrin, lambda-cyhalothrin and permethrin residues were extracted from sediment by shaking with methanol/water mixture and hexane for one hour. The sample was centrifuged and an aliquot of the upper hexane layer evaporated to dryness and re-dissolved in a small volume of hexane. The hexane sample was then subjected to a silica solid phase extraction (SPE) procedure prior to residue determination by gas chromatography with mass selective detection using negative ion chemical ionization (GC-MS/NICI). The limit of quantitation (LOQ) of the method was 0.16–0.51 ng/g dry weight for all pyrethroids.[44]