The trans enantiomeric pair is known as transpermethrin. (1R,3S)-trans and (1R,3R)-cis enantiomers are responsible for the insecticidal properties of permethrin. History
Permethrin was first made in 1973.Numerous synthetic routes exist for the production of the DV-acid ester precursor. The pathway known as the Kuraray Process uses four steps. In general, the final step in the total synthesis of any of the synthetic pyrethroids is a coupling of a DV-acid ester and an alcohol. In the case of permethrin synthesis, the DV-acid cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, ethyl ester, is coupled with the alcohol, m-phenoxybenzyl alcohol, through a transesterification reaction with base. Tetraisopropyl titanate or sodium ethylate may be used as the base.The alcohol precursor may be prepared in three steps. First, m-cresol, chlorobenzene, sodium hydroxide, potassium hydroxide, and copper chloride react to yield m-phenoxytoluene. Second, oxidation of m-phenoxytoluene over selenium dioxide provides m-phenoxybenzaldehyde. Third, a Cannizzaro reaction of the benzaldehyde in formaldehyde and potassium hydroxide affords the m-phenoxybenzyl alcohol. Brand names
In Nordic countries and North America, a permethrin formulation for lice treatment is marketed under trade name Nix, available over the counter. Johnson & Johnsons UK brand Lyclear covers an assortment of different products, mostly non-insecticidal, but a few of which are based on permethrin.Stronger concentrations of permethrin are used to treat scabies (which embed inside the skin), compared to lice (which remain outside the skin). In the U.S. the more concentrated products such as Elimite are available by prescription only. Other animals
It is known to be highly toxic to cats, fish and aquatic species with long-lasting effects.
Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto clothing or mosquito nets to kill the insects that touch them.Side effects include rash and irritation at the area of use. Use during pregnancy appears to be safe. It is approved for use on and around people over the age of two months. Permethrin is in the pyrethroid family of medications. It works by disrupting the function of the neurons of lice and scabies mites.Permethrin was discovered in 1973. It is on the World Health Organizations List of Essential Medicines. In 2017, it was the 410th most commonly prescribed medication in the United States, with more than 150 thousand prescriptions. Uses
Insecticide
In agriculture, to protect crops (a drawback is that it is lethal to bees)
In agriculture, to kill livestock parasites
For industrial and domestic insect control
In the textile industry, to prevent insect attack of woollen products
In aviation, the WHO, IHR and ICAO require arriving aircraft be disinsected prior to embarkation, departure, descent, or deplaning in certain countries. Aircraft disinsection with permethrin-based products is recommended only prior to embarkation. Prior to departure (after boarding), at the top of descent or on arrival, d-phenothrin-based (1R-trans phenothrin) aircraft insecticides are recommended. Insect repellent
As a personal protective measure, permethrin is applied to clothing. It is a cloth impregnant, notably in mosquito nets and field wear.