1112-38-5Relevant articles and documents
Photolysis of chlorpyrifos-methyl, chlorpyrifos-methyl oxon, and 3,5,6-trichloro-2-pyridinol
Lobatto, Virginia L.,Argüello, Gustavo A.,Buján, Elba I.
, (2019)
The photodegradation of chlorpyrifos-methyl (1), and two of its photodegradation products, chlorpyrifos-methyl oxon (2), and 3,5,6-trichloro-2-pyridinol (3) was studied using low pressure Hg lamps irradiating at 254?nm either in pure acetonitrile (ACN) or in 10% ACN/H2O. Experiments conducted in pure ACN allowed us to identify the photoproducts in the photolysis of 1, 2, and 3 both, in air saturated samples and in the absence of oxygen as analyzed by gas chromatography–mass spectrometry (GC-MS), high resolution mass spectrometry (HRMS), and phosphorus-31 nuclear magnetic resonance (31P NMR). Since 2 and 3 are products in the photodegradation of 1, their degradations in 10% ACN/H2O were independently measured, and it was determined that 1 and 2 degrade at comparable rates. Instead, 3 does not interfere in the measurement since it degrades much faster, and their products do not absorb in the region of 1. Our results indicate that short wave photolysis could become a plausible detoxification mechanism.
Reactivity of the insecticide chlorpyrifos-methyl toward hydroxy! and perhydroxyl ion. Effect of cyclodextrins
Vico, Raquel V.,De Rossi, Rita H.,Bujaan, Elba I.
, p. 691 - 702 (2009)
The reactivity of Chlorpyrifos-Methyl (1) toward hydroxyl ion and the α-nucleophile, perhydroxyl ion was investigated in aqueous basic media. The hydrolysis of 1 was studied at 25° C in water containing 10% ACN or 7% 1,4-dioxane at NaOH concentrations between 0.01 and 0.6m; the second-order rate constant is 1.88 × 10-2m-1 s-1 in 10% ACN and 1.70 × 10-2m-1 s-1 in 7% 1,4-dioxane. The reaction with H2O2 was studied in a pH range from 9.14 to 12.40 in 7% 1,4-dioxane/H2O; the second-order rate constant for the reaction of HOO ion is 7.9 m-1 s-1 whereas neutral H2O2 does not compete as nucleophile. In all cases quantitative formation of 3,5,6-trichloro-2-pyridinol (3) was observed indicating an SN2(P) pathway. The hydrolysis reaction is inhibited by α-, β-, and γ-cyclodextrin showing saturation kinetics; the greater inhibition is produced by γ-cyclodextrin. The reaction with hydrogen peroxide is weakly inhibited by α- and β-cyclodextrin (β-CD), whereas g-cyclodextrin produces a greater inhibition and saturation kinetics. The kinetic data obtained in the presence of β-or γ-cyclodextrin for the reaction with hydroxyl or perhydroxyl ion indicate that the main reaction pathway for the cyclodextrin-mediated reaction is the reaction of HO- or HOO- ion with the substrate complexed with the anion of the cyclodextrin. The inhibition is attributed to the inclusion of the substrate with the reaction center far from the ionized secondary OH groups of the cyclodextrin and protected from external attack of the nucleophile. Sucrose also inhibits the hydrolysis reaction but the effect is independent of its concentration. Copyright
Adsorption and degradation of methyl parathion (MP), a toxic organophosphorus pesticide, using NaY/Mn0.5Zn0.5Fe2O4 nanocomposite
Yekta, Sina,Sadeghi, Meysam
, p. 1865 - 1887 (2017/11/27)
In this research, the applicability of NaY/Mn0.5Zn0.5Fe2O4 as a new synthesized nanocomposite adsorbent for the adsorption and degradation of methyl parathion (MP, O,O-dimethyl O-p-nitrophenyl phosphorothioate), an organophosphorus pesticide, is investigated. IThe prepared samples were characterized via SEM-EDAX, TEM, XRD, FTIR, VSM and N2-BET techniques. The role of several experimental factors such as contact time, adsorbent dose and initial concentration of methyl parathion on the removal efficiency of this pesticide were considered and evaluated via 31P nuclear magnetic resonance (31PNMR) spectroscopy. 31PNMR spectroscopy showed that methyl parathion was desirably removed by the NaY/Mn0.5Zn0.5Fe2O4 nanocomposite with a yield of more than 90% under certain optimized conditions. Factors including contact time (80?min), adsorbent dose (0.5?g), and initial pesticide concentration (15?mg/L) were studied and optimized for the reaction. Reaction kinetic status was surveyed using a first order model. The values of the half-life (T1/2) and rate constant (k) were 54.6?min and 0.0127?min?1, respectively. The products of the degradation reaction between methyl parathion and NaY/Mn0.5Zn0.5Fe2O4 were dimethyl phosphorothioic acid (DMPA) and p-nitrophenol (PNP), which are significantly less toxic than the primary pesticide.
