Diethyl parathion

SYNONYMS Alkron, aileron, diethyl parathion, ethyl parathion, rhodiasol, vitrex. 

Synonyms/Trade Names 0,0-Diethyl-0(p-nitrophenyl) phosphorothioate Diethyl parathion Ethyl parathion Parathion-ethyl ... 

Diethyl parathion. See Parathion Diethylphenylamine. See Diethyl aniline Diethyl [1,2-... 

Synonyms AAT AATP Diethyl-p-nitrophenyl monothiophosphate 0,0-Diethyl-0-4-nitrophenyl phosphorothioate 0,0-Diethyl-0-p-nitrophenyl phosphorothioate Diethyl-p-nitrophenylthionophosphate 0,0-Diethyl-p-nitrophenyl thiophosphate Diethyl parathion DNTP Ethyl parathion p-Nitrophenol, 0-ester with 0,0-diethylphosphorothioate Oleoparathion Parathion-ethyl Parathion liquid Phosphorothioic acid, 0,0-diethyl 0-(4-nitrophenyl) ester... 

The rat LD qS are 13, 3.6 (oral) and 21, 6.8 (dermal) mg/kg. Parathion is resistant to aqueous hydrolysis, but is hydroly2ed by alkah to form the noninsecticidal diethjlphosphorothioic acid and -nitrophenol. The time required for 50% hydrolysis is 120 d ia a saturated aqueous solution, or 8 h ia a solution of lime water. At temperatures above 130°C, parathion slowly isomerizes to 0,%diethyl 0-(4-nitrophenyl) phosphorothioate [597-88-6] which is much less stable and less effective as an insecticide. Parathion is readily reduced, eg, by bacillus subtilis ia polluted water and ia the mammalian mmen to nontoxic 0,0-diethyl 0-(4-aminophenyl) phosphorothioate, and is oxidized with difficulty to the highly toxic paraoxon [511-45-5] diethyl 4-nitrophenyl phosphate d 1.268, soluble ia water to 2.4 mg/L), rat oral LD q 1.2 mg/kg. 

Chemical Designations - Synonyms 0,0-Diethyl 0-(p-nitrophenyl) phoshorothioate 0,0-Diethyl O-(p-nitrophenyl) thiophosphate Ethyl Parathion Phosphoroiioic acid 0,0-diethyl 0-p-nitrophenyl... 

Acetaminophen, which depletes hepatic glutathione, does not potentiate the toxicity of methyl parathion in mice. A possible mechanism of action may be competition between acetaminophen and methyl parathion for mixed function oxidases and subsequent prevention of activation of methyl parathion to methyl paraoxon (Costa and Murphy 1984). Diethyl maleate, an agent that depletes cytosolic glutathione and is not an enzyme inducer, potentiates toxicity of methyl parathion in mice (Mirer et al. 1977). 

Lewis DL, Holm HW. 1981. Rates of transformation of methyl parathion and diethyl phthalate by aufwuchs microorganisms. Appl Environ Microbiol 42 698-703. 

Mirer FE, Levinl BS, Murphy SD. 1977. Parathion and methyl parathion toxicity and metabolism in piperonyl butoxide and diethyl maleate pretreated mice. Chem Biol Interactions 17 99-112. 

Sultatos LG, Huang GJ, Jackson O, et al. 1991. The effect of glutathione monoethyl ester on the potentiation of the acute toxicity of methyl parathion, methyl paraoxon or fenitrothion by diethyl maleate in the mouse. Toxicol Lett 55 77-83. 

Of the three organic phosphorus insecticides—hexaethyl tetraphosphate, tetraethyl pyrophosphate, and parathion—the first two have been shown to be mixtures (36) that contain tetraethyl pyrophosphate as the principal active ingredient. Several methods have been proposed for the determination of this compound in the commercial products (25, 35). All are based on the separation of the tetraethyl pyrophosphate from the related ethyl phosphates, followed by its hydrolysis to diethyl orthophosphoric acid and titration with standard alkali. Both hexaethyl tetraphosphate and tetraethyl pyrophosphate are soluble in water and are rapidly hydrolyzed to monoethyl and diethyl orthophosphoric acid. This rapid hydrolysis to nontoxic products greatly limits the duration of the in- secticidal effectiveness of tetraethyl pyrophosphate, but it also eliminates the danger of toxic residues on the crops treated. 

The purpose of this work was to determine the toxicity to mosquito larvae of insecticide spray residues. That certain insecticides are translocated in plants (4, 5) adds impetus to this study. Fresh orchard fruit sprayed or dusted with preparations containing parathion (0,0-diethyl O-p-nitrophenyl thiophosphate), tetraethyl pyrophosphate (TEPP, HEPP), DDD [2,2-bis(p-chlorophenyl)-l,l-dichloroethane], DDT [2,2-bis(p-chlorophenyl)-l,l,l-trichloroethane], chlorinated camphene, and basic lead arsenate were shipped from California to Yonkers, N. Y., by air express for bioassay. 

The widespread commercial use of DDT [l,l,l-trichloro-2,2-bis-(p-chlorophenyl)-ethane] and the potentialities of the more recently developed parathion (0,0-diethyl O-p-nitrophenyl thiophosphate) have placed emphasis on such investigations concerning these compounds. 

Parathion (0,0-diethyl 0-p-nitrophenyl thiophosphate) is an ester of thiophosphoric acid with the empirical formula C10H14NO5PS. It is a high boiling deep-brown to yellow liquid, some samples of which possess a characteristic odor. Its boiling point has been calculated to be 375 0 C. or higher, at 760 mm. pressure its refractive index is n 5 1.15360 specific gravity is 1.26. The vapor pressure is 0.0006 mm. of mercury at 24° C. The technical grade has a purity of approximately 95%. 

Diethyl chlorophosphate can also be prepared from ethyl alcohol and phosphoryl chloride in the presence of base, but the method shown is reported to give better yields. The intermediate diethyl chlorophosphate has been condensed with nitrophenol in a manner similar to that used for parathion (Equation 39). 

Parathion is the accepted trivial name for 0,0-diethyl O-p-nitrophenyl thiophos-... 

Pure parathion is a pale yellow, practically odorless oil, which crystallizes in long white needles melting at 6.0° C. (17). It is soluble in organic solvents, except kerosenes of low aromatic content, and is only slightly soluble in water (15 to 20 p.p.m. at 20° to 25° C.). Peck (35) measured its rate of hydrolysis to diethyl thiophosphate and nitro-phenate ions in alkaline solutions. He found that the reaction kinetics are first order with respect to the ester and to hydroxyl ion. In normal sulfuric acid the rate of hydrolysis was the same as in distilled water. Peck concluded that hydrolysis takes place by two mechanisms—a reaction catalyzed by hydroxyl ions and an independent uncatalyzed reaction with water. He calculated that at a pH below 10 the time for 50% hydrolysis at 25° C. is 120 days in the presence of saturated lime water the time is 8 hours. The over-all velocity constant at 25° C. is k = 0.047 [OH-] + 4 X 10-6 min.-1... 

The purified tetraethyl pyrophosphate is a colorless, odorless, water-soluble, hygroscopic liquid (24, 4 )- It possesses a very high acute toxicity (28), exceeding that of parathion, and is rapidly absorbed through the skin. There is no spray-residue problem, however, for tetraethyl pyrophosphate hydrolyzes even in the absence of alkali to nontoxic diethyl phosphoric acid. Hall and Jacobson (24) and Toy (47) have measured its rate of hydrolysis, which is a first-order reaction. Its half-life at 25° C. is 6.8 hours and at 38° C. is 3.3 hours. Coates (10) determined the over-all velocity constant at 25° C. k = 160 [OH-] + 1.6 X 10 3 min.-1 Toy (47) has described an elegant method for preparing this ester as well as other tetraalkyl pyrophosphates, based upon the controlled hydrolysis of 2 moles of dialkyl chlorophosphate ... 

Polarographic Determination of 0,0-Diethyl O-p-Nitrophenyl Thiophosphate (Parathion)... 

The 0,0-diethyl O-p-nitrophenyl thiophosphate used in the preparation of the standard curves was obtained by isolation from a high-purity technical parathion according to the method devised by Edwards and Hall (2). It was a crystalline material that melted sharply at 6° C. The physical constants were in agreement with those published by Fletcher et al. (4)-... 

Diethyl p-nitrophenyl phosphate, the oxygen analog of parathion, was investigated to ascertain whether it would interfere, if present, in the determination of parathion. It was found, however, under the conditions used in this method to have a decomposition potential of —0.37 volt and a half-wave potential of —0.47 volt. 

The polarographic method of analysis of parathion as described here has an accuracy of = =1%, and 2 mg. of 0,0-diethyl O-p-nitrophenyl thiophosphate per 100 ml. of solution are apparently a minimum concentration for the sensitivities investigated. However, the polarograph used is equipped with resistors, so that a sensitivity of 0.003 microampere per millimeter may be used. At this sensitivity it would be possible to obtain a sufficient wave height to determine parathion at a concentration of less than 1 p.p.m. 

Snyder et al. [94] compared supercritical extraction with classical sonication and Soxhlet extraction for the extraction of selected organophosphorus insecticides from soil. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of Diazinon (diethyl-2-isopropyl-6-methyl-4-pyrimidinyl phosphorothiodate or 0,0 diethyl-0-(2-isopropyl-6-methyl-4-pyrimidyl) phosphorothioate). Ronnel (or Fenchlorphos) 0,0-dimethyl-0-2,4,5 trichlorophenol phosphorothiodate), Parathion ethyl (diethyl-p-nitrophenyl (phosphorothioate), Tetrachlorovinphos (trans,-2-chloro-l-(2,4,5 trichlorophenyl) vinyl (chlorophenyl-O-methylphenyl phosphorothioate) and Methiadathion. Supercritical fluid extraction with methanol modified carbon dioxide has been applied to the determination of organophosphorus insecticides in soil [260]. 

T.E.P.P. is a colourless, odourless, water-soluble toxic liquid, more toxic than parathion and rapidly absorbed through the skin. It is quickly hydrolysed, even in the absence of alkali, to the non-toxic diethyl hydrogen phosphate. It has found use as an aerosol to control pests on greenhouse vegetables and flowers, and is relatively free from residual toxicity hazards. 

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