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.
Synthesis of methylene bisphosphonates from carbon disulfide and phosphites via desulfurization: A mechanistic study
Heuze,Lemarie,Vazeux,Gulea,Masson,Sene,Jaffres,Alberti,MacCiantelli
, p. 820 - 829 (2009)
The reaction of carbon disulfide with an excess of sodium dialkylphosphite in an aprotic solvent led to the formation of the carbanion of methylene bisphosphonate and sodium thiophosphate. The mechanistic study of this unexpected reaction, using both 31P
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
Effect of cyclodextrins on the reactivity of fenitrothion
Rougier, Natalia M.,Cruickshank, Dyanne L.,Vico, Raquel V.,Bourne, Susan A.,Caira, Mino R.,Buján, Elba I.,De Rossi, Rita H.
, p. 322 - 327 (2011)
The hydrolysis reaction of fenitrothion was studied in water containing 2% dioxane and in the presence of native cyclodextrins (α-, β- and γ-CD) and two commercially available modified derivatives, namely, permethylated β- and α-cyclodextrin (TRIMEB and TRIMEA, respectively). The kinetics of the reaction in the presence of TRIMEA could not be measured because the complex formed is insoluble and precipitated even at low concentration. On the other hand, the reaction is only weakly affected by the presence of α-CD. The hydrolysis reaction is inhibited by all the other cyclodextrins. From the kinetic data the association equilibrium constants for the formation of the 1:1 inclusion complexes were determined as 417, 511 and 99 M-1 for β-CD, TRIMEB and γ-CD, respectively. Despite the differences in the association constants for β- and γ-CD, the observed inhibition effect is about the same and this is due to the fact that the rate of hydrolysis in the cavity of γ-CD is smaller than that in the cavity of β-CD. The strongest inhibitor is TRIMEB and this result is consistent with the known structure of the complex in the solid state.
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.
Studies on hydrolysis of methyl parathion with Zr(IV), Hf(IV) and Cu(II) catalysts in acidic aqueous-solutions
Algiwale, Tushar Amar,Shinde,Purnanand
, p. 269 - 272 (2008/02/12)
Hydrolysis of O,O-dimethyl O-p-nitrophenyl phosphorothionate (Methyl Parathion) has been studied in acidic medium with catalysts such as Zr 4+, Hf4+ and Cu2+ cations. In the case of Zr4+ and Hf4+ cati
Reaction of thiometon and disulfoton with reduced sulfur species in simulated natural environment
Gan, Qui,Jans, Urs
, p. 7753 - 7760 (2007/10/03)
The reactions of thiometon and its ethyl analogue, disulfoton, with reduced sulfur species [e.g., bisulfide (HS-), polysulfide (S n2-), thiophenolate (PhS-), and thiosulfate (S2O32-)] were examined in well-defined aqueous solutions under anoxic conditions. The role of reduced sulfur species was investigated in the abiotic degradation of thiometon and disulfoton. Experiments at 25°C demonstrated that HS-, Sn2-, PhS-, and S2O32- promoted the degradation of thiometon to a great extent while only Sn2- and PhS- showed a small accelerating effect in the degradation of disulfoton. Reactions were monitored at varying concentrations of reduced sulfur species to obtain the second-order rate constants. The reactivity of the reduced sulfur species decreased in the following order: Sn 2- > PhS- > HS- ≈ S2O 32-. Transformation products were confirmed by standards or characterized by gas chromatography mass spectrometry. The results illustrate that multiple pathways occur in the reactions with reduced sulfur species, among which the nucleophilic attack at the α-carbon of the alkoxy group was the predominant pathway. Activation parameters of the reaction of thiometon and disulfoton with HS- were also determined from the measured second-order rate constants over a temperature range. ΔH≠ values indicated that the reactivity of thiometon toward HS- was much greater than for disulfoton. Nucleophilic attack at the alkoxy group was more important for thiometon than disulfoton. When the measured second-order rate constants at 25°C are multiplied by [HS-] and ∑[S n2-] reported in saltmarsh porewaters, predicted half-lives show that reduced sulfur species present at environmentally relevant concentrations may present an important sink for thiometon in coastal marine environments.
The effects of substrate orientation on the mechanism of a phosphotriesterase
Jackson, Colin J.,Liu, Jian-Wei,Coote, Michelle L.,Ollis, David L.
, p. 4343 - 4350 (2007/10/03)
While the underlying chemistry of enzyme-catalyzed reactions may be almost identical, the actual turnover rates of different substrates can vary significantly. This is seen in the turnover rates for the catalyzed hydrolysis of organophosphates by the bacterial phosphotriesterase OpdA. We investigate the variation in turnover rates by examining the hydrolysis of three classes of substrates: phosphotriesters, phosphothionates, and phosphorothiolates. Theoretical calculations were used to analyze the reactivity of these substrates and the energy barriers to their hydrolysis. This information was then compared to information derived from enzyme kinetics and crystallographic studies, providing new insights into the mechanism of this enzyme. We demonstrate that the enzyme catalyzes the hydrolysis of organophosphates through steric constraint of the reactants, and that the equilibrium between productively and unproductively bound substrates makes a significant contribution to the turnover rate of highly reactive substrates. These results highlight the importance of correct orientation of reactants within the active sites of enzymes to enable efficient catalysis. The Royal Society of Chemistry 2005.
Cycloplatinated aryl ketoximes as efficient biomimicking catalysts for hydrolysis of esters of phosphorothioic acid
Kazankov,Sergeeva,Borisenko,Zatsman,Ryabov
, p. 1844 - 1848 (2007/10/03)
Cyclometallated aryl ketoximes are introduced as catalysts for hydrolysis of organophosphorus neurotoxins. Platinum-containing catalysts exhibit the highest activity and selectivity with respect to O-alkyl phosphorothioates (parathion, methyl parathion, coumaphos) and efficiently promote the hydrolysis of S-alkyl phosphorothioates and -dithioates (demeton-S, malathion) at the P - S bonds.
BROMINATION OF 6-ACETYL-2-ETHOXY-4H-1,3,2-BENZODIOXAPHOSPHORIN 2-SULFIDE IN METHANOL AND CARBON TETRACHLORIDE
Borthakur, Rohit Chandra,Borthakur, Naleen,Rastogi, Ramesh Chandra
, p. 745 - 748 (2007/10/02)
The reaction of 6-acetyl-2-ethoxy-4H-1,3,2-benzodioxaphosphorin 2-sulfide 1 with methanol-bromine gave 4-hydroxy-3-(methoxymethyl)acetophenone 4, ω-bromo-4-hydroxy-3-(methoxymethyl)acetophenone 5 and 5,ω-dibromo-4-hydroxy-3-(methoxymethyl)acetophenone 6;
