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950-35-6Relevant academic research and scientific papers
Kinetic-spectrophotometric determination of methyl parathion in water and vegetable samples
Tiwari, Neetu,Asthana, Anupama,Upadhyay, Kanchan
, p. 54 - 58 (2013)
A new selective and sensitive kinetic method has been developed for spectrophotometric determination of methyl parathion based on its inhibitory effect on the redox reaction between bromate and hydrochloric acid. The decolorization of neutral red by the r
Investigating the breakdown of the nerve agent simulant methyl paraoxon and chemical warfare agents GB and VX using nitrogen containing bases
Wilson, Craig,Cooper, Nicholas J.,Briggs, Michael E.,Cooper, Andrew I.,Adams, Dave J.
supporting information, p. 9285 - 9291 (2019/01/03)
A range of nitrogen containing bases was tested for the hydrolysis of a nerve agent simulant, methyl paraoxon (MP), and the chemical warfare agents, GB and VX. The product distribution was found to be highly dependant on the basicity of the base and the quantity of water used for the hydrolysis. This study is important in the design of decontamination technology, which often involve mimics of CWAs.
Synthesis, characterization and photocatalytic activity of Ag-TiO2 nanoparticulate film
Ramacharyulu,Praveen Kumar,Prasad,Srivastava
, p. 1309 - 1314 (2015/02/02)
Ag-TiO2 nanoparticulate film was synthesized by dip coating followed by adsorption and photoreduction in UVA light, characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive analysis of X-rays, glancing angle X-ray diffractometry and UV-Vis absorption spectrophotometry techniques. The data indicated the presence of TiO2 particles of anatase phase of size varying from 5-15 nm, Ag nanoparticles of size varying from 10-20 nm, and also indicated the added visible light activity in Ag-TiO2 nanoparticle films. Photocatalytic degradation of methyl parathion (O,O-dimethyl O-(4-nitrophenyl) phosphorothioate), a well known pesticide in aqueous solution was studied using Ag-TiO2 nanoparticulate film and the data was compared with TiO2 nanoparticulate film. Photocatalytic degradation reactions demonstrated pseudo first order behaviour. Methyl parathion was found to be degraded initially to paraoxon which further was degraded to p-nitrophenol, trimethyl ester of phosphoric acid, trimethyl ester of phosphothioic acid, and finally to phosphate ion. Minute amounts of carbon dioxide and acetaldehyde were also detected. This journal is
Photolysis of methyl-parathion thin films: Products, kinetics and quantum yields under different atmospheric conditions
Segal-Rosenheimer, Michal,Dubowski, Yael
scheme or table, p. 193 - 202 (2010/10/01)
The present study focuses on the photodegradation of methyl-parathion thin films, an organophosphate insecticide, under different atmospheric conditions. The latter include nitrogenated, oxygenated and ozonated atmospheres, under low and high relative humidity conditions. Addition of oxygen to the atmospheric mixture did not seem to affect the reaction rates and quantum yields. Relative humidity affect was minor, with a small enhancement in reaction rate under 254. nm radiation. The addition of ozone (to either dry or humid atmosphere), at all concentrations tested, largely enhanced degradation rates. In the absence of ozone, the obtained quantum yields for photolysis of methyl-parathion thin films under 254 and 313. nm were 0.024 ± 0.007 and 0.012 ± 0.005, respectively. These values are higher than the values previously reported for solutions of methanol and water. Although the presence of molecular oxygen and water vapors did not seem to affect much the reaction rates, it did have a certain effect on the resulted products. More polar products were obtained under oxygenated and ozonated atmospheres, as well as dimers under ozone conditions. The reaction on thin films has yielded more toxic products than usually found in solutions, adding alkylphosphate esters in addition to the oxons formed normally.
Kinetic study on the interactions of cyclodextrins with organic phosphates and thiophosphates
Nagata, Takuya,Yamamoto, Kenta,Yoshikiyo, Keisuke,Matsui, Yoshihisa,Yamamoto, Tatsuyuki
experimental part, p. 76 - 80 (2009/04/10)
α-Cyclodextrin (α-CD) and 6-O-α-D-glucopyranosyl-β- cyclodextrin (G1-β-CD) affected the rates of phenol release from a few dimethyl(nitrophenyl) phosphates and the corresponding thiophosphates in aqueous alkaline solutions. Curvefitting analysis of change
Oxidation of organophosphorus pesticides for the sensitive detection by a cholinesterase-based biosensor
Lee, Hye-Sung,Ah Kim, Young,Ae Cho, Young,Tae Lee, Yong
, p. 571 - 576 (2007/10/03)
A potentiometric flow injection-type biosensor developed in our laboratory was used for the determination of organophosphorus pesticides (OPs). The principle of the biosensor is that the degree of inhibition of a sensor enzyme by an OP is dependent on the concentration of the pesticide. The sensor system consisted of a reactor with acetylcholinesterase (AChE) immobilized on a controlled pore glass and a detector with a tubular H+-selective membrane electrode. In order to examine the possibility of enhancing the sensitivity of the sensor by converting OPs to oxidized forms (stronger inhibitors), a comparison of the degree of enzyme inhibition by OPs at 10-6 M before and after their oxidation was made. All of the ten pesticides tested exhibited greater inhibitory power toward the sensor enzyme following oxidation. All of the oxidized pesticides at 10-6 M inhibited the sensor enzyme to a considerable degree, demonstrating the utility of the developed method for the class-specific determination of OPs. A calibration curve for diazinon, over the concentration range of 10-11-10-4 M, was obtained. The lower detection limit was 2 × 10-10 M. Treatment of the inhibited enzyme with pyridine-2-aldoxime restored the enzyme to near full activity, allowing repeated use of the sensor,
Kinetic isotope effects and stereochemical studies on a ribonuclease model: Hydrolysis reactions of uridine 3'-nitrophenyl phosphate
Hengge,Bruzik,Tobin,Cleland,Tsai
, p. 119 - 133 (2007/10/03)
The reactions of a ribonuclease model substrate, the compound uridine-3'-p-nitrophenyl phosphate, have been examined using heavy-atom isotope effects and stereochemical analysis. The cyclization of this compound is subject to catalysis by general base (by imidazole buffer), specific base (by carbonate buffer), and by acid. All three reactions proceed by the same mechanistic sequence, via cyclization to cUMP, which is stable under basic conditions but which is rapidly hydrolyzed to a mixture of 2'- and 3'-UMP under acid conditions. The isotope effects indicate that the specific base-catalyzed reaction exhibits an earlier transition state with respect to bond cleavage to the leaving group compared to the general base-catalyzed reaction. Stereochemical analysis indicates that both of the base-catalyzed reactions proceed with the same stereochemical outcome. It is concluded that the difference in the nucleophile in the two base-catalyzed reactions results in a difference in the transition state structure but both reactions are most likely concerted, with no phosphorane intermediate. The 15N isotope effects were also measured for the reaction of the substrate with ribonuclease A. The results indicate that considerably less negative charge develops on the leaving group in the transition state than for the general base-catalyzed reaction in solution. (C) 2000 Academic Press.
Solvent isotope effects as a probe of general catalysis and solvation in phosphoryl transfer
Bryan,Schowen,Schowen
, p. 931 - 938 (2007/10/03)
Phosphoryl transfer to methanol from PNNN, PMNN, and PMMN exhibits general base catalysis by acetate ion but no detectable catalysis by acetic acid. For PNNN, acetate catalysis produces normal solvent isotope effects that arise from a one-proton catalytic bridge in the transition state. The proton inventory for the least reactive substrate PMMN is suggestive of transition-state stabilization, while the proton inventory for the most reactive substrate PNNN suggests only generalized transition-state solvation. Furthermore, the proton inventory for PMNN suggests an intermediate situation. The data are consistent with a model in which transition states with exterior concentrations of charge favor stabilization of the charge by isotope-fractionating one-proton bridges, while transition states with distributed charge favor stabilization of the charge by many distributed sites.