K. J. Palmer

Toxaphene Insecticide: A Complex Biodegradable Mixture

Adsorption and gas-liquid chromatography separate toxaphene into at least 175 polychlorinated 10-carbon compounds including Cl6, Cl7, Cl8, Cl9, and Cl10 derivatives. One toxic component is 2,2,5-endo,6-exo,8,9,10-heptachlorobornane. Rats metabolically dechlorinate toxaphene, removing about half of the chlorine from the technical insecticide and from each of seven subfractions of varying composition and toxicity.

Constituents of Tabebuia guayacan: The structure of guayacanin

Abstract The heartwood of T. guayacan has yielded tectol and a new, novel dibenz-xanthene derivative (guayacanin). The structure of guayacanin suggests its biogenetic derivation through the condensation of prenylnaphthalene quinols. The tetrahydro derivative of the xanthene was synthesized by an analogous acid catalyzed reaction of prenylnaphthalene quinol derivatives of lapachol and 1,4 naphthalene diol.

Constituents of tabebuia guayacan—II : The structure of guayin

Abstract A unique oxalactone dibenzxanthone, guayin, has been isolated from the heartwood of T. guayacan and structurally identified. A biomimetic synthesis of the dihydro derivative of guayin, based upon the probable biosynthetic origin of guayin from the dibenzxanthene guayacanin, has been successfully achieved.

The structure of guayacanin (with acetone of crystallization) C30H24O4.1/3(C3H6O), a naturally occurring dibenzoxanthene from Tabebuia guayacan

The crystal structure of guayacanin (with acetone of crystallization), C30H2404.½(CaH60), has been determined by X-ray diffraction. The crystals are rhombohedral, space group R3 with hexagonal cell dimensions a=24.677 (7), c=20.588 (6) ,~, Z= 18. The structure was solved by use of the programs NORMAL and MULTAN. The parameters were refined by full-matrix least squares to an RI index of 0.051 for 2681 reflections. The molecule has two chromene gem dimethyl groups, one of which is benzylically substituted. The molecule is approximately planar; repulsion between two hydrogen atoms produces an appreciable twist to the molecule. The crystal consists of clusters of six molecules; each cluster is centered on an inversion triad axis. The molecules in each cluster are held together by a network of hydrogen bonds. The only attractive force between clusters results from van der Waals interactions. The crystal contains two acetone molecules per cluster. The acetone molecules are disordered; the four heavy atoms partially occupy six positions and are centered on inversion triad axes. There are no bonds between the acetone molecules and the clusters.

Guayin: an unusual oxalactone dibenzxanthone from Tabebuia guayacan

A unique oxalactone dibenzxanthone has been identified in Tabebuia guayacan wood and its dihydro derivative has been successfully synthesised.