December 1951 E-832 
 
 United States Department of Agriculture 
 
 Agricultural Research Administration 
 
 Bureau of Entomology and Plant Quarantine 
 
 CHEMICAL AND PHYSICAL PROPERTIES OF 
 ORGANIC PHOSPHORUS INSECTICIDES 
 
 By Fred I. Edwards, Division of Insecticide Investigations 
 
 Several organic phosphorus compounds have recently come into use 
 as insecticides, and a number of others have been proposed for this 
 purpose. The physical and chemical properties of these compounds are 
 presented herein for the guidance of investigators working with them. 
 The information has been compiled from the literature, from data 
 supplied by manufacturers, and from measurements made in this 
 laboratory. Only the compounds that are now in commercial use or 
 are being tested extensively are included. 
 
 All these compounds are highly toxic to man, and caution should be 
 used in handling them. 
 
 Literature Cited 
 
 (1) Hall, S. A. 
 
 1950. Methyl homolog of parathion. Amer. Chem. Soc. Jour. 
 
 72: 2768-2769. 
 
 (2) and Jacobson, M. 
 
 1948. Hexaethyl tetraphosphate and tetraethyl pyrophosphate. 
 Ind. Eng. Chem. 40: 694-699. 
 
 (3) Schrader, G. S. 
 
 1951. Die Entwicklung neuer Insectizide auf Grundlage 
 
 organischer Fluor- und Phosphor-verbindungen. 
 Monograph No. 62, p. 52. Verlag Chemie, GMBH, 
 Weinheim, Germany. 
 
 (4) Toy, A. D. F. 
 
 1948. Preparation of tetraethyl pyrophosphate and other tetraethyl 
 pyrophospates. Amer. Chem. Soc. Jour. 70: 3882-3886. 
 
Structural formula. 
 
 Other names 
 
 0,0-Diethyl O-p-nitropbenyl 
 thiophosphate 
 
 Empirical formula 
 Molecular weight. 
 Phosphorus content 
 Physical state . 
 Melting point . . 
 Boiling point . . 
 Specific gravity 
 
 Refractive index 
 
 Solubility in water 
 Hydrolysis rate . 
 
 C 2 H 5 Q S 
 
 ^P-O- 
 
 C2H5C/ 
 
 Parathion, E-605 
 
 C 10 H 14 NO 5 PS 
 
 291 
 
 10.63% 
 
 Pale-yellow liquid 
 
 6.0°C. 
 
 157-162°C. at 0.6 mm 
 
 1.2655 at 25°/4°C. 
 
 N0 2 
 
 n 
 
 25 
 D 
 
 1.5370 
 
 15-20 p. p.m. at 20-25°C. 
 
 Very slow at pH 7 and below. Half- 
 life 120 days at 25°C. 
 
 Very rapid above pH 7. Half- life 
 8.6 m in. in N/'l alkali at 30°C. 
 
 0,0-Dimethyl O-p-nitro 
 thiophosphate 
 
 CH30 2 
 
 x p-o 
 
 CH30 
 
 / 
 
 -NO, 
 
 Methyl parathion, methyl h| 
 
 parathion 
 C 8 H 10 NO 5 PS 
 
 263 
 
 11.78% 
 
 White crystalline solid 
 
 35°(l)f ^OC^)- 7 
 
 1.358 at 20°/4°C 
 
 35 
 n D 1.5515 
 
 50 p. p. m. at 25°C. 
 
 Stable for several days in rlt: 
 water. Very rapid in alksne 
 solution. Half-life approi; 
 2.5 m in. in N/l alkali at 3% 
 
 Structural formula- • 
 
 Other names 
 
 Tetraethyl pyrophosphate 
 C2H5P •?, ?/ OC 2H5 
 
 V-o-p( 
 
 C 2 H 5 CK X OC 2 H 5 
 
 Tetraethyl dithiopyropft<p 
 
 C 2 H 5 0j I y OC ? V 
 
 \P-G-P' 
 C2H 5 / OC 2 H 
 
 Empirical formula. 
 
 Molecular weight. . 
 Phosphorus content 
 Physical state . . . 
 
 Melting point. . . . 
 
 Eoiling point. . . . 
 
 Specific gravity . . 
 
 Refractive index 
 
 Solubility in water . 
 Hydrolysis rate . . 
 
 TEPP (commercial preparation con- SSulfotepp, dithio, tetraethy 
 
 taining about 40% of tetraethyl 
 pyrophosphate) 
 
 C 8 H 2 0O 7 P2 
 290 
 
 21.36% 
 Colorless liquid 
 
 pyrophosphate 
 
 C 8 H20°5 P 2 S 2 
 
 322 
 
 19.25% 
 
 Yellow to colorless oil 
 
 104-110 C. at 0.08 mm. 
 1,1810 at 25°/4°C. 
 
 n ^ 1.4170 (2_)r 1.4180 (4)- 
 
 Completely miscible 
 
 'Rapid- in neutral water; half-life at 
 
 25°C. 6.8 hours; at 38°C. 3.3 hours 
 
 Very rapid in alkaline solution 
 
 110-113 W C. at 0.2 mm 
 
 1,196 at 25°/4°C. 
 
 25 
 n^ 1.4753 
 
 670 p. p. m. 
 Very stable 
 
 1/ See Literature Cited 
 
):2nyl 
 
 Diethyl p-nitrophenyl phosphate 
 
 teolog of 
 
 C 2 H 5 0. ° 
 
 \p-o- 
 
 C 2 H 5 ° 
 
 / V 
 
 NO. 
 
 O-Ethyl O-p-nitrophenylbenzene 
 thiophos phonate 
 S 
 
 c 2 H 5°\p_o 
 
 "\ 
 
 X 
 
 NO2 
 
 :itral 
 
 me 
 
 ?nately 
 
 C. 
 
 Para-oxon, E-60C, oxygen analog of 
 
 parathion 
 C 10 H 14 NO 6 P 
 
 275 
 
 11.26% 
 
 Reddish-yellow liquid 
 
 148-151°C. at 1 mm. 
 1.269 at 25°/25°C. 
 
 n 2 ^ 1.5060 
 
 2500 p. p.m. at 25°C. 
 Very slow at pH 7 
 
 EPN, ethyl p-nitrophenyl thiono- 
 
 benzenephosphate 
 C 14 H 14 4 NPS 
 
 323 
 
 9.59% 
 
 Off-white crystals 
 
 36°C. 
 
 Essentially insoluble 
 Stable at pH 7 and below; slow 
 above pH 7 
 
 phate 
 
 Octamethyl pyrophosphoramide 
 
 (CH 3 ) 2 N ^ V N(CH 3 } 2 
 
 >p-o-p x 
 
 \N(CH 3 ) 2 
 
 0,0 -Diethyl 4-methylumbelliferone 
 thiophosphate 
 
 \ 
 
 ithiono- 
 
 (CH 3 ) 2 N 
 
 OMPA, schradan 
 
 C 8 H 24 N 4 3 P 2 
 
 286 
 
 21.65% 
 Colorless liquid 
 
 C2H50 7 
 
 / 
 
 P-O 
 
 118-122 U C. at 0.3 mm. 
 1.1343 at 25°/4°C. 
 
 n 2 D 1. 4612 
 
 Completely miscible 
 
 Rapid in strong acid solution and very 
 slow in neutral and alkaline solutions 
 
 vS 
 
 c=o 
 
 i H 
 
 H3 
 
 Diethyl thiophosphoric acid ester 
 of 7-hydroxy-4-methyl coumarin, 
 E-838 
 
 Ci 4 H 17 5 PS 
 
 328 
 
 9.44% 
 
 Fine white crystals 
 
 36°C. 
 
 1.260 at 38°/4°C. 
 n^ 1.5685 
 
 Very slightly soluble 
 Very slow 
 
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