Description
Alpha-cypermethrin is a widely used pyrethroid insecticide. It has a low aqueous solubility, in relatively volatile and, based on its chemical properties, is not expected to leach to groundwater. However, it is considered to be a serious water pollutant. It is moderately persistent in soil and has been known to persist in water. It is highly toxic to mammals and a recognised irritant. It is relatively non-toxic to birds but is highly toxic to most aquatic organisms and honeybees. Alpha-cypermethrin is moderately toxic to earthworms.
Chemical Properties
alpha-cypermethrin is a colorless crystalline solid or viscous yellowish-brown semisolid mass. mild aromatic odor. easily soluble in alcohols, ketones and aromatic hydrocarbon organic solvents, such as cyclohexanone 515g/l, xylene 315g/l, solubility in water 5 ~ 10mg/l (0.01 ~ 0.2mg/l). it is relatively stable under acidic and neutral conditions, easy to hydrolyze under strong alkaline conditions, and has good thermal stability.
Uses
alpha-Cypermethrin is a synthetic pyrethroid pesticide used in large-scale commercial agricultural applications as well as in consumer products for domestic purposes.
Uses
Alpha-cypermethrin is used to control a wide range of insects,
especially Lepidoptera, in fruit, vines, vegetables, cereals, beans, beets,
cotton, ornamentals and forestry and other crops. It is also used for insect
control in public health and for ectoparasite control on animals.
Definition
ChEBI: Cypermethrin is a carboxylic ester resulting from the formal condensation between 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid and the alcoholic hydroxy group of hydroxy(3-phenoxyphenyl)acetonitrile. It has a role as a pyrethroid ester insecticide, a pyrethroid ester acaricide, an agrochemical and a molluscicide. It is an organochlorine compound, a nitrile, an aromatic ether and a cyclopropanecarboxylate ester. It is functionally related to a 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid.
Production Methods
Alpha-cypermethrin is produced commercially through a multi-step chemical synthesis that isolates the most biologically active isomers of cypermethrin. The process begins with the synthesis of the isomeric-mixture of cypermethrin and involves reacting 3-phenoxybenzyl alcohol with cyanoacetic acid derivatives and dichlorovinyl cyclopropane carboxylic acid. The alpha isomer is isolated using chiral resolution or selective crystallization.
Agricultural Uses
Insecticide: A U.S. EPA restricted Use Pesticide (RUP) (zeta-Cypermethrin only). Used for the control of a wide range of chewing and sucking insects (particularly Lepidotera, Coleoptera, and Hemiptera) in fruit (including citrus), vegetables, vines, cereals, maize, beet, oilseed rape, potatoes, cotton, rice, soya beans, forestry, and other crops. Control of cockroaches, mosquitoes, flies, and other insect pests in public health; and flies in animal houses. Also used as an animal ectoparasiticide.
Trade name
BESTOX®; CONCORD®; DOMINEX®; FASTAC®; FENDONA®; FMC 45497®[C]; NRDC 160®; RENEGADE®; WL-85871® Cypermethrin-s: FURY® (s-isomer); FMC 56701® (s-isomer)
Mechanism of action
Non-systemic with contact and stomach action. Sodium channel modulator.
Potential Exposure
alpha-Cypermethrin useds for the control of a wide range of chewing and sucking insects (particularly lepidotera, coleoptera, and hemiptera) in fruit (including citrus), vegetables, vines, cereals, maize, beet, oilseed rape, potatoes, cotton, rice, soya beans, forestry, and other crops. Control of cockroaches, mosquitoes, flies, and other insect pests in public health; and flies in animal houses. Also used as an animal ectoparasiticide. alpha-Cypermethrin only is a United States Environmental Protection Agency Restricted Use Pesticide (RUP).
Metabolic pathway
Alpha-cypermethrin is composed of two of the four cis-cypermethrin
isomers (i.e. two of the eight cypermethrin isomers). These are the lRcisaS
and 1ScisaR isomers. The fate of alpha-cypermethrin specifically has been
reported for soils, rat and human. Metabolite analysis was conducted in
enough detail to indicate that the fate of this mixture is very similar to its
fate when presented to biological systems as part of cis-cypermethrin.
Thus reference can be made to the cypermethrin entry for details. The
structure and Scheme numbering used below refers to the cypermethrin
entry.
Shipping
UN3349 Pyrethroid pesticide, solid toxic,
Hazard Class: 6.1; Labels: 6.1-Poisonous material. UN3352
Pyrethroid pesticide, liquid toxic, Hazard Class: 6.1;
Labels: 6.1-Poisonous materials.
Degradation
Alpha-cypermethrin is stable as a solid but it is readily hydrolysed in
solution under alkaline conditions. By analogy with cypermethrin, the
rate-determining step in dilute solution is nucleophilic attack by OH
-.
Half-lives of cis-cypermethrin in river water and sea water at 25 °C
were 21 and 24 days, respectively. Major products were 3-(2,2-dichlorovinyl)-
2,2-dimethylcyclopropanecarboxylic acid (2, DCVA), 3-phenoxybenzaldehyde
(9, 3PBAl) and a-carbamoyl-3-phenoxybenzyl 3-(2,2-
dichlorovinyl)-2,2-dimethylcyclopropanecarboxyltae (the amide 3);
minor products were the a-carboxy analogue of 3 (4) and 3-phenoxybenzoic
acid (10,3PBA) (see cypermethrin, Schemes la and lb).
Photodecomposition would be expected to be similar to that of
cis-cy permethrin.
Incompatibilities
May react violently with strong oxidi-
zers, bromine, 90% hydrogen peroxide, phosphorus
trichloride, silver powders, or dust. Incompatible with silver
compounds. Mixture with some silver compounds forms
explosive salts of silver oxalate.
Waste Disposal
Do not discharge into drains
or sewers. Burn in incinerator specifically designed for pes-
ticide disposal or dispose as a Hazardous waste in a landfill
approved and licensed for the disposal of pesticides.
Consult with environmental regulatory agencies for guid-
ance on acceptable disposal practices. Ultimate disposal of
the chemical must consider: the material’s impact on air
quality; potential migration in soil or water; effects on ani-
mal, aquatic, and plant life; and conformance with environ-
mental and public health regulations.
Pesticide Type
Insecticide; Veterinary substance
