Arylesters of alkylsulfonic acids in sediments Part III of organic compounds as contaminants of the Elbe River and its tributaries

Sediments from the Elbe River and from its major tributaries are shown to be contaminated with arylesters of alkylsulfonic acids. Here we report on the structure elucidation and quantification of aryl esters of alkylsulfonic acids. Chromatographic separation and mass spectrometric properties are discussed. Congener-specific analyses revealed a highly similar pattern throughout the area investigated. Alkylsulfonic acid phenylesters were present at almost all sampling locations. Amounts ranged from 33 000 μg/kg near the industrial region of Bitterfeld to 15 μg/kg in wadden sea sediments. Concentrations of alkylsulfonic acid cresylesters were between 10–40% of the phenylesters, and fell below the detection limit only in the Elbe estuary. The presence of aryl esters of alkylsulfonic acids in all sediment samples analyzed indicates a widespread distribution of these compounds in the environment. Previous literature described these compounds erroneously as phenoxyalkanes. Received: 5 August 1997 / Accepted: 21 August 1997     

Electrogenerated hypervalent iodine compounds as mediators in organic synthesis

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PHOTOREACTIVITY OF 5-GERANOXYPSORALEN AND LACK OF PHOTOREACTION WITH DNA

5-Geranoxypsoralen, commonly called bergamottin, a major furocoumarin contained in bergamot oil, is reported in vitro as a highly photoreactive psoralen. In ethanol, it exhibits quite a high triplet state quantum yield (approximately 0.37). The triplet state is involved in subsequent photochemistry which depends on the initial concentration and on the presence of oxygen. In contrast to most psoralens, absorption and fluorescence data suggest that 5-geranoxypsoralen does not interact with DNA in the dark. No UVA-induced interstrand cross-links in DNA were shown.     

Structure-type separation of diesel fuels by solid phase extraction and identification of the two- and three-ring aromatics by capillary GC-mass spectrometry

A simple and effective solid phase extraction (SPE) method using silica gel micro glass columns has been developed for the separation of diesel fuel into groups of aliphatic, and mono-, di- and polyaromatic hydrocarbons. It is based on a stepwise gradient of dichloromethane in n-pentane. The resulting fractions were analyzed by capillary gas chromatography with a flame ionization detector and coupled gas chromatography-mass spectrometry. Commercially available standards, and retention indices and mass spectra were used for identification of individual aromatic compounds. The principal polycyclic aromatic hydrocarbons (PAHs) in diesel fuel are naphthalene, biphenyl, fluorene, phen-anthrene and their alkylated derivatives. Sulfur-containing PAHs are mainly represented by methyl-substituted dibenzo-thiophenes.     

Solid state 13C MAS NMR as a tool for the study of reactions between compounds adsorbed on porous materials

It is shown that magic angle spinning (MAS) solid state ¹³C NMR spectroscopy is a valuable tool for the study of reactions between compounds adsorbed on porous materials because it allows the direct characterization of surface species. The mobility of the adsorbed species yields high-resolution ¹³C spectra at moderate spinning speeds (4 kHz) from which the reactions can be traced. Catalysis of KMnO₄ oxidation of alcohols and proton transfer by the solid support is demonstrated. Received: 22 July 1996 / Revised: 20 August 1996 / Accepted: 23 August 1996     

Carbamate Series of Juvenoids: Variation of the O-alkyl substituent

By changing the O-alkyl substituents of the carbamate moiety of alkyl N-{2-{4-[(2-oxocyclohexyl)methyl]phenoxy}ethyl}carbamates and subsequent transformation of the oxo group in the cyclohexyl substituent, the juvenoids 1–20 were synthesized (Scheme). The methyl ( 1–4 ), propyl ( 9–12 ), isopropyl ( 13–16 ), and prop-2-ynylcarbamates ( 17–20 ) were subjected to biological screening on several non-related insect species (Tenebrio molitor, Galleria mellonella, Dysdercus cingulatus, and Pyrrhocoris apterus). Some of the juvenoids showed high biological activity and excellent selectivity with respect to target insect species (Table 2).     

Differential non-destructive image current detection in a fourier transform quadrupole ion trap

Dual-detector differential non-destructive Fourier transform detection in a quadrupole ion trap is shown to improve signal intensity and reduce noise compared with spectra recorded using a single detector. A larger area detector in each end-cap electrode is machined to fit its hyperbolic shape and so minimize field imperfections on the z-axis. Argon, acetophenone and bromobenzene spectra were recorded to allow a comparison between single- and dual-detector (differential) modes of detection and to demonstrate the improvement achieved with differential detection. Copyright 1999 John Wiley & Sons, Ltd.     

Chlorinated di- and triphenylmethanes in sediments of the Mulde and Elbe rivers

Congeneric groups of chlorinated diphenylmethanes (ClDPM) and triphenylmethanes (ClTPM) identified by coupled GC/MS investigations of Elbe and Mulde river sediments were not as yet noticed as environmental contaminants of aquatic sediments. ClDPM and ClTPM are structurally related to other polychlorinated aromatic compounds and form complex mixtures of congeners. Individual ClDPM/ClTPM as well as mixtures of congerers were synthesized, and served as reference compounds for isomer identification and quantitative analysis. In addition to mass spectra, GC/FTIR-investigations and retention indices proved to be valuable for structural assignments. Sediments from the Mulde river contained up to 220 μg/kg ClTPM and 170 μg/kg ClDPM. The spatial distribution of ClDPM/TPM concentrations indicated a strong localized source of emisson at the lower Mulde river, from where the compounds enter sediments and suspended matter of the Elbe river. The occurrence of ClTPM in the Hamburg harbour at comparable levels in samples of recent and older sediments indicates emissions over a prolonged period.