Roy L. Holmstead

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.

Triphenyl derivatives of group IV elements as inhibitors of growth and digestive enzymes of Tribolium castaneum larvae

Abstract The potency of triphenyl derivatives of group IV elements in inhibiting the growth of first and fourth instar Tribolium castaneum larvae is much greater for Ph 3 SnCl and Ph 3 PbCl than for Ph 3 GeCl, Ph 3 SiOH, and Ph 3 CCl. Pupated larvae emerge normally, showing that the pupal stage is not affected. The larval growth retardation may result from an antifeeding effect involving digestive enzyme inhibition. Ph 3 SnCl and Ph 3 PbCl at 500 μmol/kg of diet completely inhibit larval growth (fourth instar larvae) and provide a reduction of 56–59, 29–33, and 2–15% in the in vivo activity of invertase, amylase, and protease, respectively. Under these conditions Ph 3 GeCl, Ph 3 SiOH, and Ph 3 CCl are essentially inactive. High concentrations (5 × 10 −4 and 2 × 10 −3 M ) of Ph 3 SnCl and Ph 3 GeCl acting in vitro strongly inhibit invertase, amylase, and protease activities, whereas Ph 3 PbCl is moderately inhibitory and Ph 3 SiOH and Ph 3 CCl are inactive. When both in vivo and in vitro findings are considered, Ph 3 SnCl is the most potent inhibitor of larval digestive enzymes.

Gas phase protonolysis reactions : Chemical ionization mass spectrometry of N-nitrosamines

Abstract Gas phase protonolysis reactions of a wide variety of N-nitrosamines have been studied utilizing methane chemical ionization mass spectrometry (CIMS). N-Nitrosamines are protonated at either the N or O atoms of the N-nitroso triad (NNO) leading to aminium radicals, nitrenium ions, ammonium ions, carbenium ions and various elimination reaction. A structure-CIMS reactivity relationship of N-nitrosamines is presented.

Gas phase 1,3-deoxystannylation reactions of γ-substituted organotin alcohols utilizing chemical ionization mass spectrometry

The gas phase 1,3-deoxystannylation reactions of γ-substituted organotin alcohols have been studied by methane and isobutane chemical ionization mass spectrometry. It was found that γ-hydroxybutyltributyltin and γ-hydroxybutyldibutyltin chloride undergo the 1,3-deoxystannylation reaction to a greater extent than the corresponding 1,4-deoxystannylation using the δ-substituted analogues of the above named compounds. This result substantiates the unusual reactivity of γ-substituted organotin alcohols under gas phase protonolysis conditions. The electronic factors affecting the stabilization of the transition state were ascertained with γ-phenyl-γ-hydroxypropyltrimethyltin derivatives, in which the γ-phenyl group was substituted with groups such as H, p-OMe, p-Me, p-Cl, p-F, m-OMe, m-Me, m-Cl and m-CF3. We observed a reasonably linear Hammett relationship when plotting the log [P − 17]x+/[P − 17]H+ vs. σ+ with rho (ρ) equal to −1.0. Thus electron-donating groups stabilize the [P − 17]+ ion and carbon—tin sigma (σ) electrons can either, by a neighbouring group effect, attack the nucleofugic center, or the carbonium ion can attack the carbon—tin σ electrons to form the trimethyltin cation and a cyclopropane derivative. Consequently, we propose that a two-step mechanism for the 1,3-deoxystannylation reaction is operating in the gas-phase with this type of compound. The factors contributing to this gas phase reaction will be discussed.