Organophosphorus model

Mingelgrin, U., Saltzman, S., and Yaron, B. A possible model for the surface-induced hydrolysis of organophosphorus pesticides on kaolinite clays. Soil Sol. Soc. Am. J., 41 519-523, 1977. 

The objective of this work Is to establish a reaction mechanism between sodium perborate and several organophosphorus esters. By analogy we can then describe Its probable effects upon other phosphorus-based Insecticides. We conclude that the reactivity of sodium perborate toward five model compounds Is attributable to the nucleophilic reactions of hydroperoxyl anion, HO2 , produced by perborate dissociation In water. On this basis we predict that sodium perborate solutions will be effective chemical detoxicants for phosphorus ester Insecticides. 

In this paper, the volatilization of five organophosphorus pesticides from model soil pits and evaporation ponds is measured and predicted. A simple environmental chamber is used to obtain volatilization measurements. The use of the two-film model for predicting volatilization rates of organics from water is illustrated, and agreement between experimental and predicted rate constants is evaluated. Comparative volatilization studies are described using model water, soil-water, and soil disposal systems, and the results are compared to predictions of EXAMS, a popular computer code for predicting the fate of organics in aquatic systems. Finally, the experimental effect of Triton X-100, an emulsifier, on pesticide volatilization from water is presented. 

The oxime-induced reactivation of organophosphorus-inhibited AChE has been modeled recently through the Density Functional Theory (DFT) approach. Two possible computed reactivation pathways of Sarin-inhibited AChE adduct by formoximate anion are shown in Scheme The two-step mechanism (Scheme 7B) is favored by the authors. 

Model compounds (simulants) are often used to estimate the reactivity of organophosphorus pesticides and warfare agents toward potential remediation technologies because of their availability and ease of handling [5-18]. The structures of select organophosphorus pesticides, chemical warfare agents, and model compounds (simulants) are presented in Fig. 1. 

R Tauler, S Lacorte, D Barcelo. Application of multivariate self-modeling curve resolution to the quatitation of trace levels of organophosphorus pesticides in natural waters from interlaboratory studies. J Chromatogr A 730 177-183, 1996. 

Goto, M., Matsumoto, S., Uezu, K. et al. 1999. Development and computational modeling of novel bifunctional organophosphorus extractants for lanthanoid separation. Sep. Sci. Technol. 34 (11) 2125-2139. 

Yoshizuka, K., Shinohara, T., Shigematsu, H., Kuroki, S., Inoue, K. 2006. Solvent extraction and molecular modeling of uranyl and thorium ions with organophosphorus extractants. Solvent Extr. Res. Dev. Jpn. 13 115-122. 

Alkyl-substituted monoamides are known as extractants for the uranyl cation and they could potentially be considered as alternatives to organophosphorus compounds in nuclear fuel reprocessing. In toluene, the uranyl cation forms complexes with two monoamide molecules. These relatively simple molecules were selected for computer-aided design,14 taking into account a lot of synthetic and experimental work that must be done to prove the modeling predictions. 

This review summarizes experimental and theoretical studies which are used to develop theoretical models that explain and predict how clay minerals and metal oxides can affect the adsorption and decomposition of selected organophosphorus compounds. The results can contribute to a better knowledge of the impact of such processes on existing remedial technologies and in the development of new removal and decomposition techniques. 

The basic experimental studies of the interactions between organophosphorus compounds and metal oxide surfaces have been carried out intensively during the last several years. Metal oxides, such as MgO, AI2O3, FeO, CaO, Ti02 a-Fe203, ZnO, and WO3, are currently under consideration as destructive adsorbents for the decontamination of chemical warfare agents [46, 47], For example, several studies have addressed adsorption of dimethyl methylphosphonate (DMMP) (a widely used model compound for the simulation of interactions of phosphate esters with a surface) on the surface of these metal oxides [48-60], In most of these works, the authors have observed that, at first, DMMP is adsorbed molecularly via hydrogen... 

A QUEST FOR EFFICIENT METHODS OF DISINTEGRATION OF ORGANOPHOSPHORUS COMPOUNDS MODELING ADSORPTION AND DECOMPOSITION PROCESSES... 

A recent publication on PBTK/TD modeling to determine dosimetry and cholinesterase inhibition for a chemical mixture of 2 organophosphorus insecticides, chlo-rpyrifos and diazinon (Timchalk and Poet 2008), deserves some special discussion here. Based on the individual PBTK/TD models developed earlier by the same laboratory, Timchalk and Poet (2008) reported their development of a binary interaction PBTK/TD model for chlorpyrifos and diazinon. In their development of the model, Timchalk and Poet (2008) took into consideration a number of important metabolic steps (CYP450 mediated activation and detoxification of a number of esterases—B-... 

Jager T, Kooijman SALM. 2005. Modeling receptor kinetics in the analysis of survival data for organophosphorus pesticides. Environ Sci Technol 39 8307-8314. 

Legierse KCHM, Verhaar HJM, Vaes WHJ, De Bruijn JHM, Hermens JLM. 1999. Analysis of the time-dependent acute aquatic toxicity of organophosphorus pesticides the critical target occupation model. Environ Sci Technol 33 917-925. 

PoetTS, KousbaAA, Dennison SL, TimchalkC. 2004. Physiologically based pharmacokinetic/ pharmacodynamic model for the organophosphorus pesticide diazinon. Neurotoxicology 25 1013-1030. 

Furlong, C.D., W.F. Li, L.G. Costa, R.J. Richter, D.M. Shih, and A.J. Lusis. 1998. Genetically determined susceptibility to organophosphorus insecticides and nerve agents Developing a mouse model for die human PONl polymorphism. Neurotoxicology 19 645-650. 

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