Resmethrin
- 5-benzyl- 3- furylmethyl -cis- chrysanthemate
- 5 -benzyl -3- furylmethyl - ( 1RS13RS; 1RS13SR ) -212 -dimethyl- 3-( 2-methylpropyl -enyl) - ciclopropancarboxylat (IUPAC)
White to brownish solid
Fixed
0.958 to 0.968 g · cm -3
56.5 ° C ( pure ( 1 -RS )-trans isomer )
172 ° C.
<0.01 MPa ( 25 ° C)
- Practically insoluble in water
- Soluble in xylene, methylene chloride and acetone
Attention
Template: Infobox chemical / molecular formula search available
Resmethrin is a chemical compound from the group of pyrethroids.
It was developed in the 1960s by the group of Michael Elliott ( Rothamsted Research).
Production and representation
Resmethrin can be prepared by a multistep reaction. Starting from furan 3-carboxylic acid obtained by esterification with methanol of the methyl ester. The methyl ester is chloromethylated with paraformaldehyde and hydrogen chloride in a blanching reaction. By reaction with benzene and aluminum chloride are obtained in a Friedel -Crafts alkylation of the a Benzylfuran. This is reduced with lithium aluminum hydride to the alcohol which is then esterified in a last step with Chrysanthemsäurechlorid.
An alternative production route starts from benzyl cyanide by reaction with diethyl succinate.
Properties
Resmethrin is a flammable solid that is practically insoluble in water. From 180 ° C, the compound decomposes. On exposure to air and light it decomposes easily. The commercial product consists of 20-30 % cis -isomer and 80-70 % trans - isomers and is a white to brownish waxy solid with a smell of chrysanthemums. Melting point of the technical material is 43-48 ° C. The pure ( 1R, trans) isomer is known as bioresmethrin, the pure ( 1R, cis ) isomer as Cismethrin.
Use
Resmethrin is a pyrethroid with broad insecticidal activity. It acts in insects as fast-acting neurotoxin with good contact action, but it has for other animals and plants a low toxicity. Resmethrin 1967 bioresmethrin 1973 was approved in the U.S. for the first time and introduced commercially in 1969. Approximately 50,000 pounds of resmethrin are used annually in the U.S., mostly to combat adult mosquitoes. In the U.S., it is currently classified as a General Use Pesticide for pest control in the home and the food industry as well as due to its acute toxicity to fish as a Restricted Use Pesticide ( with reduced pesticide use) for large-scale mosquito control. Its effect is based on the interaction with the sodium channels in the peripheral and central nervous system of the target organisms. It is used against the house, hygiene and stored-product pests and against whitefly, aphids and other in greenhouses and agricultural crops. Since it itself is not very stable, it is often used in combination with other insecticides that break down more slowly after application or turned down.
Resmethrin is not approved in the European Union as an active ingredient in pesticides. In Germany, Austria and Switzerland, no plant protection products containing this active ingredient are allowed.
Safety
In animal studies, an increase of liver and uterine tumors when exposed to resmethrin was found.