Pyrethrins
Title: Pyrethrins
Literature References: Active insecticidal constituents of pyrethrum flowers. Isoln: Staudinger, Ruzicka, Helv. Chim. Acta 7, 177 (1924). Prepn by reconstitution from pyrethrolone and chrysanthemic acid: Elliott, Janes, Chem. Ind. (London) 1969, 270. Structure: Crombie et al., J. Chem. Soc. 1956, 3963; Godin et al., ibid. (C) 1966, 332. Stereochemistry: Begley et al., Chem. Commun. 1972, 1276. Biosynthesis: Crowley et al., Biochim. Biophys. Acta 60, 312 (1962). Review: Crombie, Elliott, Fortschr. Chem. Org. Naturst. 19, 120 (1961). Review of toxicology and human exposure: Toxicological Profile for Pyrethrins and Pyrethroids (PB2004-100004, 2003) 332 pp.
 
Derivative Type: Pyrethrin I
CAS Registry Number: 121-21-1
CAS Name: (1R,3R)-2,2-Dimethyl-3-(2-methyl-1-propenyl)cyclopropanecarboxylic acid (1S)-2-methyl-4-oxo-3-(2Z)-2,4-pentadienyl-2-cyclopenten-1-yl ester
Additional Names: chrysanthemummonocarboxylic acid pyrethrolone ester
Molecular Formula: C21H28O3
Molecular Weight: 328.45
Percent Composition: C 76.79%, H 8.59%, O 14.61%
Properties: Viscous liquid. bp0.0005 146-150°. nD20 1.5242. [a]D20 -14° (isooctane). uv max (95% ethanol): 225 nm (e 36400). Oxidizes readily and becomes inactive in air. Should be refrigerated and stored in darkness. Stability data of pyrethrins I and II: Godin, Pyrethrum Post 9, 17 (1968), C.A. 71, 12031q (1969). Practically insol in water. Sol in alcohol, petr ether, kerosene, carbon tetrachloride, ethylene dichloride, nitromethane.
Boiling point: bp0.0005 146-150°
Optical Rotation: [a]D20 -14° (isooctane)
Index of refraction: nD20 1.5242
Absorption maximum: uv max (95% ethanol): 225 nm (e 36400)
 
Derivative Type: Pyrethrin II
CAS Registry Number: 121-29-9
CAS Name: (1R,3R)-3-[(1E)-3-methoxy-2-methyl-3-oxo-1-propenyl]-2,2-dimethylcyclopropanecarboxylic acid (1S)-2-methyl-4-oxo-3-(2Z)-2,4-pentadienyl-2-cyclopenten-1-yl ester
Additional Names: chrysanthemumdicarboxylic acid monomethyl ester pyrethrolone ester
Molecular Formula: C22H28O5
Molecular Weight: 372.45
Percent Composition: C 70.95%, H 7.58%, O 21.48%
Properties: Viscous liquid. Oxidizes rapidly and becomes inactive in air. bp0.007 192-193°. nD20 1.5355. [a]D19 +14.7° (isooctane-ether). uv max (95% ethanol): 229 nm (e 45850). Practically insol in water. Sol in alc, petr ether (less sol than pyrethrin I), kerosene, carbon tetrachloride, ethylene dichloride, nitromethane.
Boiling point: bp0.007 192-193°
Optical Rotation: [a]D19 +14.7° (isooctane-ether)
Index of refraction: nD20 1.5355
Absorption maximum: uv max (95% ethanol): 229 nm (e 45850)
 
CAUTION: Direct skin contact or inhalation may cause severe allergic attacks in sensitive people. Potential symptoms of overexposure are erythema, dermatitis, papules, pruritus; asthma, sneezing, vasomotor rhinitis, anaphylactic reactions; numbness of lips and tongue, sneezing, vomiting, diarrhea; tinnitus, headache, restlessness, incoordination, clonic convulsions, stupor, prostration; death due to respiratory paralysis. See: Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, Baltimore, 5th ed., 1984) Section III, pp 352-355; NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 270.
Use: Insecticide.

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