Cyhalothrin

Cyhalothrin
Names
IUPAC name
3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl-cyano(3-phenoxyphenyl)methyl cyclopropanecarboxylate
Other names
Cyhalothrine
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.101.414
KEGG
UNII
Properties
C23H19ClF3NO3
Molar mass 449.850 g/mol
Appearance Dark brown/green solid. Colorless when pure.
Density 1.33 ± 0.03 g/cm3 at 25 °C
Melting point 49.2 °C (120.6 °F; 322.3 K)
Boiling point 498.9 °C (930.0 °F; 772.0 K) decomposes (760 mmHg)
Very soluble in xylene. Soluble in ethyl acetate, diethyl ether, cyclohexane, methanol. Insoluble in water (0.005 mg/l [20 °C]).
Acidity (pKa) 5.43 (decomposes in alkaline solutions)
Pharmacology
QP53AC06 (WHO)
Hazards
T+ Xi
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
1
3
1
Flash point 185 °C (365 °F; 458 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Cyhalothrin is an organic compound that is used as a pesticide.[1] It is a pyrethroid, a class of man-made insecticides that mimic the structure and insecticidal properties of the naturally occurring insecticide pyrethrum which comes from the flowers of chrysanthemums. Synthetic pyrethroids, like lambda-cyhalothrin, are often preferred as an active ingredient in insecticides because they remain effective for longer periods of time. It is a colorless solid, although samples can appear beige, with a mild odor. It has a low water solubility and is nonvolatile. It is used to control insects in cotton crops.[2]

Structure

Lambda-cyhalothrin is a mixture of isomers of cyhalothrin.[3] Brand names include "Danger" by "OPAL Agrochemical Pakistan" 'Karate', 'Kung-fu', 'Matador', 'Cyzmic CS', and 'Demand CS' (Syngenta); Proaxis in Indonesia by PT Dow AgroSciences Indonesia; in the USA, 'Triazicide' and 'Hot Shot' are used in the home landscape and garden markets[4][5][6] Home Depot carries a brand of the lambda-cyhalothrin insecticide under the brand name Real Kill and Spectracide Bug Off. Terro also makes an outdoor ant and other insect prevention treatment similar to Home Defense using this ingredient. Syngenta held the patent for lambda-cyhalothrin which expired in most major markets in 2003.[7] Lambda-cyhalothrin may be marketed as Charge, Demand CS, Excaliber, Grenade, Hallmark, Icon, Karate, Matador, OMS 0321, PP321, Saber, Samurai, and Sentinel.

Gamma-cyhalothrin is a single stereoisomer of the pyrethroid insecticide cyhalothrin, and as such shares physical, chemical, and biological properties with both cyhalothrin and lambda-cyhalothrin, which are mixtures of 4 and 2 isomers respectively. Gamma-cyhalothrin is the most insecticidally active isomer of cyhalothrin/lambda-cyhalothrin, and thus the technical gamma-cyhalothrin product may be considered a refined form of cyhalothrin/lambda-cyhalothrin in that it has been purified by removal of less active and inactive isomers. Thus, similar levels of insecticidal efficacy for gamma-cyhalothrin can be obtained with significantly reduced application rates as compared with either cyhalothrin or lambda-cyhalothrin. The tolerance under 40 CFR 180.438 currently identifies lambda-cyhalothrin as a 1:1 mixture of two isomers and their epimers, one of which is the gamma isomer. The gamma isomer is present at 42% in this mixture. By contrast in the proposed tolerance expression the gamma isomer is present at 98% in the mixture.[8] Home Depot carries a brand of the gamma-cyhalothrin insecticide under the brand name Spectracide Triazacide.

Mechanism of action

Pyrethroids, including lambda-cyhalothrin, disrupt the functioning of the nervous system in an organism. By disrupting the nervous system of insects, lambda-cyhalothrin may cause paralysis or death. Temperature influences its effectiveness. It is highly toxic to many fish and aquatic invertebrate species. Bioconcentration is possible in aquatic species, but bioaccumulation is not likely. Binding of lambda-cyhalothrin to soil and sediment reduces exposure and may lessen the risk to fish. Field studies found no significant adverse effects to fish. Lambda-cyhalothrin is also highly toxic to bees, although again field studies found few effects. In laboratory studies, alkaline water degraded lambda-cyhalothrin with an approximate half-life of 7 days, although at neutral and acidic pHs, degradation did not occur. Sunlight accelerates degradation in water and soil. The half-life of lambda-cyhalothrin on plant surfaces is 5 days. Lambda-cyhalothrin has a low potential to contaminate ground water due to its low water solubility and high potential to bind to soil.[9]

Regulation

The LD50 is 79–56 mg/kg (rats, oral).[2] It decomposes in extreme heat (257 °C),[10] liberating toxic gases like CO and HCN.[11][12] It is a potent irritant to mucous membranes and is highly toxic in concentrations higher than 97%.[13]

References

  1. ↑ "Cyhalothrin". Cameo Chemicals. United States National Oceanic and Atmospheric Administration. Retrieved 2008-05-08.
  2. 1 2 Robert L. Metcalf "Insect Control" in Ullmann’s Encyclopedia of Industrial Chemistry" Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a14_263
  3. ↑ "Lambda-cyhalothrin factsheet" (PDF). National Pesticide Telecommunications Network (Oregon State University and the U.S. Environmental Protection Agency). Retrieved 2008-04-15.
  4. ↑ "Insecticides in the Home Landsape and Garden". Iowa State University Department of Entomology. Retrieved 2009-04-29.
  5. ↑ "Regulatory Decision Document: Lambda-Cyhalothrin Demand CS Insecticide". Health Canada. Archived from the original on 2012-07-30. Retrieved 2011-06-10.
  6. ↑ "Demand CS". Syngenta. Retrieved 2011-06-10.
  7. ↑ "WHO Specifications and Evaluations for Public Health Pesticides" (PDF). WHO. Retrieved 2011-06-10.
  8. ↑ "Lambda-Cyhalothrin and an Isomer Gamma-Cyhalothrin; Tolerances for Residues" (PDF). US EPA FEDERAL REGISTER, April 8, 2004 (Volume 69, Number 68). Retrieved 2012-09-07.
  9. ↑ "Lambda-cyhalothrin(General Fact Sheet)" (PDF). NPIC. Retrieved 2012-09-07.
  10. ↑ MSDS of Lambda Cyhalothrin
  11. ↑ "Safety Data Sheet" (PDF). Nufarm. 2012-06-19.
  12. ↑ "MATERIAL SAFETY DATA SHEET" (PDF).
  13. ↑ "Lambda-cyhalothrin" (PDF). NPIC.
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