Paul Frøyen

Distribution of 14C from ingested, radiolabelled dichlorostearic, stearic and oleic acids in body and in lipids of perch, Perca fluviatilis

Distribution of C-14 from ingested, radiolabelled dichlorostearic, stearic and oleic acids in body and in lipids of perch, Perca fluviatilis

PHOSPHORUS IN ORGANIC SYNTHESIS. THE TANIGAWA REACTION REVISITED AS A METHOD FOR CONVERTING ALCOHOLS TO TERTIARY AMINES

Abstract Contrary to earlier observations, N-methyl-N-phenylaminotriphenylphosphonium iodide 1 (the Murahashi reagent) does not react with alcohols and primary or secondary amines under mild conditions (80°) to give secondary or tertiary amines. However the reaction can be successfully performed at higher temperatures. A mechanistic scheme implying initial amine exchange between 1 and the added amine leading to the N,N-dimethyl analog 5 is suggested. An improved synthesis where the reactive intermediate 5 is formed in situ from triphenylphosphine, carbon tetrachloride and HNR3R4 is described.

Metabolic fate of 14 C-labelled chlorinated and non-chlorinated fatty acids in goldfish ( Carassius auratus )

In order to study the metabolic fate of chlorinated fatty acids in fish, goldfish were fed either 9,10-dichlorostearic acid or oleic acid, chosen as the unchlorinated analogue, both radiolabelled at either the carboxyl (1st) or the terminal (18th) carbon of the fatty acid chain. By keeping the fish in hermetically closed aquaria, all the respired, assimilated and excreted radioactivity could be accounted for. Fish fed 9,10-dichlorostearic acid labelled in the terminal end respired radioactive CO2 to a much lower degree than fish fed the other test compounds. As a consequence, the radioactivity bound in lipids was higher in the group of fish fed dichlorostearic acid labelled in the terminal end. It is suggested that the chlorine atoms in the middle of the carbon chain obstruct the metabolic turn-over of 9,10-dichlorostearic acid, which may have an impact on the residence time of these compounds in the ecosystem.

Chlorinated thiophenes. Part 2. Trihalogenated hydroxythiophenes; preparation, reactions and tautomeric properties

2-Hydroxy-3,4,5-trichlorothiophene (4), 3-hydroxy-4-bromo-2,5-dichlorothiophene (5) and 3-hydroxy-2,4,5-trichlorothiophene (6) have been synthesised. It was found that 4 exists in a carbonyl form, whereas in 5 and 6 the hydroxy forms were the major tautomers. Several derivatives of the trihalogenated hydroxythiophenes were prepared. O-Methylation was carried out with diazomethane and O-acetylation with acetyl chloride. Silylation of 4 was performed using N,O-bis(trimethylsilyl)acetamide. Compound 4 reacted with methylmagnesium iodide in an unexpected way by exchanging chlorine with magnesium iodide, giving 3,4-dichloro-2,5-dihydrothiophen-2-one (16) after hydrolysis. In an unsuccessful attempt to try to prepare thiophene isosteres of the infamous 2,3,7,8-tetrachlorodibenzo-p-dioxine, the new dimer 2,2′,3,3′,4,4′-hexachloro-2,2′,5,5′-tetrahydro-2,2′-bithiophen-5-one (15) was discovered, the crystal structure of which is reported.