2-chloro-1-(2,4-dichlorophenyl)vinyl diethyl phosphate 

2-chloro-1-(2,4-dichlorophenyl)ethenyl diethyl phosphate 

C₁₂H₁₄C_l3O₄P

 Colourless liquid; (tech., amber liquid). 

-23 to -19 ºC 

167-170 ºC/0.5 mmHg 

1 mPa (25 ºC); 0.53 mPa (extrapolated to 20 ºC) 

No flash point up to 285 °C (EC method AP - ISO 3679) 

1.36 at 20 ºC 

In water 121 mg/l ((Z)- isomer); 7.3 mg/l ((E)- isomer) (23 ºC). Miscible with most common organic solvents, e.g. ethanol, acetone, dichloromethane, hexane, xylene, propylene glycol, kerosene. 

Hydrolysed slowly in neutral, acidic, and slightly alkaline aqueous solutions. Hydrolysed rapidly in strongly alkaline solutions. DT50 (38 ºC) >700 h (pH 1.1), >400 h (pH 9.1); (20 ºC) 1.28 h (pH 13). 

3.85 ((Z)- isomer

Cholinesterase inhibitor. 

Insecticide and acaricide with contact and stomach action. Long residual activity. 

Soil application for control of root flies, rootworms, and other soil insects in vegetables; frit flies in maize; wheat bulb flies in wheat; bean seed flies; and phorid and sciarid flies in mushrooms; using granular formulations, applied at 0.8-7 kg/ha. Foliar application for control of Colorado beetles on potatoes; scale insects and mite eggs on citrus fruit; stem borers and leafhoppers on rice; stem borers on maize and sugar cane; and whitefly on cotton; using liquid formulations, applied at 240-2400 g/ha for vegetables and cotton, and up to 12 000 g/ha for ornamentals. Used in public health for control of mosquito larvae. Also used as an animal ectoparasiticide.

Non-phytotoxic when used as directed. Some injury may occur if applied directly to the seeds of certain crops.

Incompatible with alkaline materials.  

FAO/WHO 71, 73 (see part 2 of the Bibliography).

Acute oral LD50 for rats 10, mice 117-200, rabbits 300-1000, dogs >12 000 mg/kg.  

Acute percutaneous LD50 for rats 31-108, rabbits 400-4700 mg/kg. Non-irritating to skin and eyes (rabbits). 

LC50 (4 h) for rats c. 0.05 mg/l air. 

(2 y) for rats and dogs 1 mg/kg diet (0.05 mg/kg daily). 

(JMPR) 0.0005 mg/kg b.w. [1994]. 

WHO (a.i.) Ib; EPA (formulation) I 

T+; R28| T; R24| N; R50, R53 

LC50 (96 h) for harlequin fish <0.32, guppies 0.3-1.6, tilapia 0.04 mg/l.  

EC50 (48 h) 0.3 mg/l. 

EC50 (96 h) for Selenastrum capricornutum 1.6 mg/l. 

LC50 (14 d) 217 mg/kg of soil. 

Metabolism is similar to that in mammals; see K. I. Beynon et al., Residue Rev., 1973, 47, 55. 

Primary metabolic detoxification is by de-esterification to give 2-chloro-1-(2,4-dichlorophenyl)vinyl ethyl hydrogen phosphate. Ultimate metabolites include the glucuronides of 2,4-dichlorophenylethanediol and 1-(2,4-dichlorophenyl)ethanol, and N-(2,4-dichlorobenzoyl)glycine; see D. H. Hutson in "Prog. in Pesticide Biochem.", Vol. 1, D. H. Hutson & T. R. Roberts, eds., Wiley (1981). 

chlorfenvinphos is slowly degraded by hydrolysis; DT50 88 d (pH 9), 270 d (pH 7) ((Z)- isomer); 71 d (pH 9), 275 d (pH 4) ((E)- isomer). In the presence of light, isomerises from the (Z)- to (E)- isomer, DT50 482 h. In soil, chlorfenvinphos is rapidly degraded and apparently mineralised under aerobic conditions; the rate depends on soil characteristics and temperature; DT50 8 d in a sandy loam soil, 161 d in a sand soil (20 °C).