Parathion structure

Mathematical models have also predicted a low volatility for methyl parathion (Jury et al. 1983 McLean et al. 1988). One study using a laboratory model designed to mimic conditions at soil pit and evaporation pond disposal sites (Sanders and Seiber 1983) did find a high volatility from the soil pit model (75% of the deposited material), but a low volatility for the evaporation pond model (3. 7% of the deposited material). A study of methyl parathion and the structurally similar compound ethyl parathion, which have similar vapor pressures, foimd that methyl parathion underwent less volatilization than ethyl parathion in a review of the data, the reduced level of volatilization for methyl parathion was determined to be due to its adsorption to the soil phase (Alvarez-Benedi et al. 1999). 

Because of continued interest in the in situ degradation products of both DDT and parathion, preliminary spectrophotometric evidences, which are also indicative of structural alterations and/or changes in composition, have been secured with extracts of navel oranges previously treated with standard formulations of these compounds. 

Formulas 42 to 44 give examples of phosphate esters related to parathion and prepared by the above methods. In some of these compounds the ethyl group has been changed, whereas in others various substituents have been introduced into the benzene ring. A number of the structures shown have been reported by the Germans (11-18). 

Estimate the Ki0Vi values at 25°C of the following compounds based on the experimental Ki0Vi values of the indicated structurally related compounds (a) benzoic acid dimethylaminoethyl ester from benzoic acid ethyl ester (log Kiaw = 2.64), (b) the insecticide methoxychlor from DDT (log Ki0Vi = 6.20), (c) the insecticide fenthion from parathion [log Kiow = 3.83, see 111. Ex. 7.2, Answer (d)], and (d) the hormone estradiol from testosterone [log Ki0Vi = 3.32, see 111. Ex. 7.2, Answer (e)]. 

The mechanism resembles that proposed for a phosphotriesterase (Fig. 12-24). The triesterase catalyzes detoxification of organophosphorus toxins such as parathion (Box 12-E) and seems to have evolved rapidly from a homologous protein of unknown function.721 The phosphotriesterase contains two Zn2+ ions in a dimetal center. An unusual structural feature is a carbamate group, formed from Lys 169 and C02, which provides a bridging ligand for the metal pair.721-725 A carbamylated lysine also functions in ribulose bisphos-phate carboxylase (Fig. 13-11). 

Recently, a parathion-selective voltammetric MIP chemosensor was designed [205]. The parathion-imprinted polymer particles were prepared by polymerization of an MAA functional monomer, EGDMA cross-linker and AIBN initiator. Subsequently, the powdered MIP particles were blended with a graphite powder, in the presence of n-icosane. to form an (MlP)-(carbon paste) (MIP-CP) electrode. After removal of the template, MIP-CP much more selectively rebound parathion than the (non-imprinted imprinted polymer)-(carbon paste) carbon paste (NIP-CP) electrode. Recognition ability of the MIP-CP electrode was very high compared to that of the NIP-CP electrode. The chemosensor response was calibrated in the linear range of 1.7-900 nM parathion and LOD was 0.5 nM [205]. This chemosensor selectively determined parathion in the presence of its structural and functional counterparts, such as paraxon, in real samples. 

This paper establishes toxicologically-safe levels for total residues of parathion, azinphosmethyl, methidathion and their oxons on tree foliage and reports these levels in terms of absorbance units as determined by the rapid field method. Safe levels for a new insecticide, chlorthiophos, are also proposed based on preliminary residue data. Chemical structures of the four insecticides mentioned above are shown in figures 1, 2, 3 and 6. 

Structures of toxicants that can affect pulse rate. Methyl parathion, a commonly used plant insecticide, can cause bradycardia. Imiprimine hydrochloride, a tricyclic antidepressant, can cause either tachycardia or arrhythmia. 

In the body, parathion is converted to paraoxon (structure in Figure 18.8), which is a potent inhibitor of acetylcholinesterase. Because this conversion is required for parathion to have a toxic effect, symptoms develop several hours after exposure, whereas the toxic effects of TEPP or... 

Fig. 8.7 Chemical structure of pesticides (a) parathion (b)phosmet (c) terbufos (d) chlopyrifos (e) azinphos-methyl (f) tribufos (g) bomoxynil (h) dichlorophene (i) pentrachlorophenol...

The use of parathion has resulted in many accidental deaths because of its extreme toxicity. In fact, its use in the United States has been prohibited since 1991, but it is still used in other parts of the world. Sarin is a nerve gas that has been produced for military use, and it has the structure... 

Structure 4.12 C2H5° i /= c2h5ox w Parathion O.O-Diethyl 0-/ -nitrophenyl Phosphorothioate... 

Organophosphates (OPs) are a group of chemicals with similar structures and similar modes of action, which includes the nerve gases. Only the pesticides wiU be considered in this chapter. Organophosphates were developed during the Second World War as insecticides and chemical warfare agents. The first was parathion, which is very toxic compared to DDT and to other OPs and is no longer used in most countries (see box and Table i). 

The metabolic and/or hydrolytic products of parathion encountered as residues in the urine include both diethyl phosphoric acid and diethyl phosphorothioic acid, most probably as their salts (potassium or sodium). Derivatization of these residues with diazomethane would result in the formation of three trialkyl phosphate compounds, namely, 0,0-diethyl O-methyl phosphate (DEMMP), 0,0-diethyl 0-methyl phosphoro-thionate (DEMMTP), and 0,0-diethyl S-methyl phosphorothiolate (DEMMPTh). Earlier (15), it had been shown by combined gas chromatography-mass spectrometry and other analytical data that a later-eluting major product ca. 85%) of the methylation of diethyl phosphorothioic acid formed under the conditions of the analytical method was DEMMPTh, and the minor product formed (ca. 15%) was DEMMTP. Accordingly, all three trialkyl phosphates were observed and confirmed by mass spectrometry in the analysis of the human urine extract. Sufficient internal bond energy differences are associated with the isomeric structures DEMMPTh and DEMMTP that qualitatively and quantitatively dissimilar fragmentation patterns are observed for both isomers as can be seen from the mass spectra of these compounds shown in Figure 4. 

Figure 1 Structures of the phosphorothioate insecticides chlorpyrifos and methyl parathion and their corresponding oxygen analogs.

Synonyms Bayer E-605 Corthion 0,0-Diethyl-O-(p-nitrophenyl) phosphorothioate Diethyl 4-nitrophenyl phosphorothionate DNTP DDPP Ethyl parathion AC 3422 Alkron Aileron Aphamite Corothion E-605 ENT 15108 Etilon Fosferno 50 Niran Nitrostigine Orthophos Panthion Paramar Paraphos Parathene Para-wet Pethion Phoskil Rhodiatox Soprathion Stathion Sulphos Thiophos Chemical/Pharmaceutical/Other Class Organo-phosphorus insecticide Chemical Structure ... 

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