An examination of polymerized pyrethrins

Abstract

The resinous material formed by polymerization of a highly purified pyrethrum concentrate has been examined. It was insoluble in cold light petroleum or deodorized kerosene, and gave high values for apparent pyrethrins by the Seil or mercuryreduction methods, although it was devoid of insecticidal effect on houseflies. In these respects it resembled the additional ' pyrethrins ' recently shown' to be extracted by chloroform or by warm light petroleum from pyrethrum flowefs, differing only in its higher content of apparent 'pyrethrin 1.On hydrolysis of this material, pure chrysanthemum mono-and di-carboxylic acids were isolated in yields of some 75% of the quantities calculated from the analysis. These acids were identical with those derived from normal pyrethrum extracts. Hence it appears that polymerization is confined to the keto-alcoholic constituents of the esters, the acids not being involved. The chemical assay methods at present available do not distinguish such polymerized material from true pyrethrins : but the modification described by Mitchell and Tresadernl largely prevents the extraction of polymerized material.The need for confirming all chemical assays by biolugical tests is emphasized. A portion of the monocarboxylic acid was esterified with DL-allylcyclopentenolone ; thc ester possessed the expected insecticidal activity. The action of this ester on houseflies is discussed and contrasted with that of the pyrethrins.

Photodecomposition of pyrethrin I, allethrin, phthalthrin, and dimethrin. Modifications in the acid moiety

“…for 3 months, produced resinous material Division of Entomology, University of California, Berkeley, Calif. 94720 1 Present address, Department of Agricultural Chemistry, National Taiwan University, Taipei, Taiwan which, after hydrolysis, yielded crystalline chrysanthemumic and chrysanthemumdicarboxylic acids; this finding supports the view that the photodecomposition involves only the cyclopentenolone portion of the esters, the acids not being attacked (Campbell and Mitchell, 1950). When films of pyrethrum oleoresin extract were irradiated with a tungsten light, Brown and Phipers (1955) found that the green-colored material in the extracts catalyzed degradation of the chrysanthemumic acid moiety but not the slower changes taking place in the cyclopentenolone moiety.…”

Determination of Insecticide Residues

“…Trans., 60, 1235-40 (1941. (2) Daigle, E. C., and Lee, J. H., Petroleum Refiner, 27, No. 9, 492-5 (1948).…”