Title: Allethrins
Additional Names: Allyl cinerins
Literature References: Synthetic analogs of the naturally occurring insecticides cinerins, jasmolins, and pyrethrins, q.q.v. Review: Barthel, World Rev. Pest Control 6, 59 (1967); World Health Org., Environ. Health Criter. 87, 1-75 (1989). Review of toxicology and human exposure: Toxicological Profile for Pyrethrins and Pyrethroids (PB2004-100004, 2003) 332 pp.
Derivative Type: Allethrin I
CAS Registry Number: 584-79-2
Additional Names: 2,2-Dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylic acid 2-methyl-4-oxo-3-(2-propenyl)-2-cyclopenten-1-yl ester; allethrolone ester of chrysanthemummonocarboxylic acid
Trademarks: Pynamin (Sumitomo)
Molecular Formula: C19H26O3
Molecular Weight: 302.41
Percent Composition: C 75.46%, H 8.67%, O 15.87%
Literature References: Synthesis: M. S. Schechter et al., J. Am. Chem. Soc. 71, 1517, 3165 (1949); H. A. Stansbury, H. R. Guest, US 2768965 (1956 to UCC). Commercial process: H. J. Sanders, A. W. Taff, Ind. Eng. Chem. 46, 414 (1954).
Properties: The commercial product is a mixture of 8 optically active isomers. Clear, pale yellow oil. bp 0.1 140°. Decomp by rapid pyrolysis at >400°. Vaporizes without dec when heated at 150°. Unstable in light, air, alkaline conditions. d2020 1.010; nD20 1.5040; nD30 1.5023. Practically insol in water. Sol in alcohol, petr ether, kerosene, carbon tetrachloride, ethylene dichloride, nitromethane. Incompatible with alkalies.
Boiling point: bp 0.1 140°
Index of refraction: nD20 1.5040; nD30 1.5023
Density: d2020 1.010
Derivative Type: Allethrin II
CAS Registry Number: 497-92-7
Additional Names: 3-(3-Methoxy-2-methyl-3-oxo-1-propenyl)-2,2-dimethylcyclopropanecarboxylic acid 2-methyl-4-oxo-3-(2-propenyl)-2-cyclopenten-1-yl ester; allethrolone ester of chrysanthemumdicarboxylic acid monomethyl ester
Manufacturers' Codes: ENT-17510
Molecular Formula: C20H26O5
Molecular Weight: 346.42
Percent Composition: C 69.34%, H 7.56%, O 23.09%
Literature References: Synthesis: M. Matsui, Y. Yamada, Agric. Biol. Chem. 27, 373 (1963); M. Matsui, H. Meguro, ibid. 28, 27 (1964); M. Elliott, N. F. Janes, Chem. Ind. (London) 1969, 270; A. Kobayashi et al., Agric. Biol. Chem. 35, 1961 (1971); T. Sugiyama et al., ibid. 36, 565 (1972).
Properties: Oily pale yellow liq. nD20.6 1.5156. uv max (ethanol): 232 nm (e 23000). Unstable in light, air, alkaline conditions. Sol in organic solvents. Practically insol in water.
Index of refraction: nD20.6 1.5156
Absorption maximum: uv max (ethanol): 232 nm (e 23000)
CAUTION: Potential symptoms of toxicity are similar to those of the pyrethrins.
Use: Insecticide.
Allidochlor Allobarbital Allocholesterol Alloclamide Allocryptopine

Allethrin I (R = −CH3)
Allethrin II (R = −COOCH3)

The allethrins are a pair of related synthetic compounds used in insecticides. They are synthetic pyrethroids, a synthetic form of a chemical found naturally in the chrysanthemum flower. They were first synthesized in the United States by Milton S. Schechter in 1949. Allethrin was the first pyrethroid.

The compounds have low toxicity for humans and birds, and are used in many household insecticides such as RAID as well as mosquito coils. They are, however, highly toxic to fish and bees. Insects subject to its exposure become paralyzed (nervous system effect) before dying. They are also highly toxic to cats because[1] they either do not produce, or produce less of certain isoforms of glucuronosyltransferase, which serve in hepatic detoxifying metabolism pathways.[2]

They are also used as an ultra-low volume spray for outdoor mosquito control.