Tore Skjetne

Gyroxanthin—the First Allenic Acetylenic Carotenoid

Abstract Selected recent studies on marine allenic and acetylenic carotenoids are focused on. The structure elucidation of gyroxanthin, (3 S ,5 R ,6 S ,3′ S ,5′ R ,6′ R )-5,6-epoxy-6,7,7′,8′-tetradehydro-5,6,5′,6′-tetrahydro-β,β-carotene-3,19,3′,5′-tetrol, is reported in detail and in historical perspective. Gyroxanthin occurs as a diester (19-dodecanoate 3′-acetate) in the dinoflagellate Gymnodinium galatheanum .

The structure of abelsonite

Abelsonite, a C31 nickel-porphyrin of the deoxophylloerythroetioporphyrin type, is shown to have methyl groups in the 2, 3, 7, 12, and 18 positions and ethyl groups in the 8 and 17 positions by high-resolution, high-field 1H nuclear magnetic resonance and nuclear Overhauser effect studies. Removal of the nickel by treatment with methanesulfonic acid permitted confirmation of the structure on the free base porphyrin and demonstrated structural integrity under the conditions required for demetallation. The structure is best accounted for geochemically by the hypothesis that abelsonite is derived from a chlorophyll.

Nuclear magnetic resonance spectroscopy of petroporphyrins

Abstract The substitution pattern of the two major petroporphyrins of Marl Slate, the ETIO III and the C 32 DPEP, is determined by NMR spectroscopy alone, using self-aggregation effects, nuclear Overhauser enhancements and spin-lattice relaxation times. Protoporphyrin IX dimethyl ester was used as a model compound.

Isolation and identification of two hydroxy C32 and C30 deoxophylloerythroetioporphyrins

Two unusual 10-hydroxy C32 and C30 deoxophylloerythroetioporphyrins (DPEPs) have been characterized by high resolution high field 1H nuclear magnetic resonance and nuclear Overhauser effect studies and by fast atom bombardment and electron impact mass spectrometry. The compounds have been isolated from Marl Slate, and it is discussed whether the porphyrins are genuine geochemical entities or not.

Studies of crown ether complexes aryldiazonium ion complexes

Abstract DNMR studies show that for complexation of aryldiazonium salts 21-crown-7 is the preferred host.

Characterization of sedimentary organic matter using nuclear magnetic resonance and pyrolysis techniques

The aromatic hydrocarbon fractions from a series of sediment extracts have been isolated and subjected to proton nuclear magnetic resonance spectroscopy (1H NMR). The NMR results were correlated with maturity data such as Rock—Eval T max values, vitrinite reflectance and specific biomarker ratios. Evidence is presented to indicate that the percentage of aromatic protons in the aromatic fraction (PAP) is proportional to the level of maturity of the sediment. Some kerogens have been subjected to 13C NMR (CP/MAS) and flash pyrolysis—gas chromatography (Py−GC) analysis to provide complementary structural information about the kerogens. The 13C NMR and pyrolysis results are compared with maturity and other organic geochemical data.