benzofurans and phenyl-ether

Two cross-bridged cyclen-based macrocycles with two trans-N-acetic acid arms, one having a dibenzofuran (DBF) moiety as the bridge, H2L1, and the other a diphenyl ether (DPE) one, H2L2, were synthesized. Both compounds behave as "proton sponges." The thermodynamic stability constants for the Cu(2+), Zn(2+), Al(3+), and Ga(3+) complexes of both compounds were determined. They exhibit an excellent thermodynamic selectivity for copper(II), ensuring that metal ions largely present in the human body do not interfere with the copper(II) chelates. All complexes are very slow to form, and [CuL2] and [CuL1] are extremely inert to demetallate, especially [CuL2]. The acid-assisted dissociation of [CuL1] led to a half-life of 4.28 h in 5 M HCl at 363.2 K, while [CuL2] needed harsher conditions of 12 M HCl at 363.2 K with a half-life of 30.8 days. To the best of our knowledge, [CuL2] exhibits the highest half-life value for a copper(II) complex of a polyazamacrocycle derivative reported in the literature until now. Single crystal X-ray diffraction determined for [Cu(H2L1)](ClO4)2 showed the copper center in a distorted octahedral environment bound to the N4O donors of the macrobicycle and one oxygen atom from a carboxylic arm, while for [CuL2] it showed the copper center in a trigonal bipyramid geometry only bound to the donors of the macrobicycle and leaving the carboxylate arms away from the coordination sphere. UV-vis-NIR and X-band EPR spectra showed that in [CuL1] the copper center adopts a distorted compressed octahedral environment, which is the only structure found in solution for this complex, while in [CuL2] a similar environment was found in the first stages of its slow formation but reached a square-pyramidal geometry upon stabilization. The acetate arms play therefore an important role during the formation of the complex, as revealed by the comparison of its complexation behavior with the corresponding parent compounds.

Topics: Acetates; Benzofurans; Chelating Agents; Coordination Complexes; Copper; Crystallography, X-Ray; Cyclams; Heterocyclic Compounds; Macrocyclic Compounds; Models, Molecular; Phenyl Ethers; Spectrum Analysis; Thermodynamics

This article examines the thermal decomposition of alpha-cypermethrin, one of the most common pyrethroid pesticides. The objective was to identify its decomposition pathways and to gain an understanding into the formation of toxic species in the environment, including those that may behave in combustion systems, especially in fires in the environment, as precursors for PCDD/F (polychlorinated dibenzo-p-dioxins and dibenzofurans). The experiments were conducted under non-oxidative conditions using a tubular reactor housed in a three-zone heating furnace and operated with a dilute stream of alpha-cypermethrin in 99.999% nitrogen. The condensable products were identified and quantitated, after being collected in a cold solvent trap and in an activated charcoal cartridge. The study revealed the formation of pollutants including precursors of toxic PCDD/F such as diphenyl ether and phenol. It was also found that the decomposition of alpha-cypermethrin involved parallel pathways of an unusual vinylcyclopropane rearrangement-cum-aromatisation reaction transforming alpha-cypermethrin and a rupture of the C(=O)O-C(-C≡N) linkage. The former is similar to that occurring in the decomposition of permethrin pesticide, whereas the latter constitutes a newly discovered channel for the formation of pollutants. Density functional theory (DFT) calculations allowed us to attribute the occurrence of the second pathway to the effect of the cyanide group in significantly weakening the O-C bond.

Topics: Benzofurans; Dibenzofurans, Polychlorinated; Environmental Pollutants; Fires; Gas Chromatography-Mass Spectrometry; Insecticides; Oxygen; Phenol; Phenyl Ethers; Polychlorinated Dibenzodioxins; Pyrethrins; Spectroscopy, Fourier Transform Infrared

Polybrominated diphenyl ethers (PBDEs) have been determined in 30 samples, including soil, biota and plant collected from an electronic waste recycling site and its vicinage towns. Polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) were also simultaneously analyzed in 20 samples. PBDEs were detected in all soil samples and the highest was up to 789 ng/g dry weight (dw). The toxic equivalency (TEQ) of PCBs and PCDD/Fs detected in E-waste recycling site is significant higher than those in the vicinage samples. Biota and plant were also contaminated with high level of PBDEs, PCBs and PCDD/Fs in this area. High levels of the three kinds of organic compounds in the environmental samples showed that the E-waste recycling have induced serious environmental problems.

Topics: Animals; Benzofurans; Conservation of Natural Resources; Dibenzofurans, Polychlorinated; Environmental Pollutants; Environmental Pollution; Industrial Waste; Phenyl Ethers; Plants; Polybrominated Biphenyls; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins; Snails; Soil

The concentrations and composition profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, polybrominated diphenyl ethers and polychlorinated naphthalenes were determined in herring individuals collected from the commercial catches of the Bothnian Sea, northern Baltic. The median age of herring was 5.0 years and in the muscle the median toxic equivalent concentration of PCDD/Fs was 5.6 WHO(PCDD/F)-TEQ pg/g fresh weight (fw) and that of PCBs 2.7 WHO(PCB)-TEQ pg/g fw. The median sum concentration of PBDEs was 1.4 ng/g fw and that of PCNs 0.1 ng/g fw. Differences in age-dependent accumulation between the organohalogen groups and individual congeners were major. In the Bothnian Sea the content of organohalogen compounds in herring is obviously elevated due to the availability and large proportion of Mysis crustaceans in their diet. More intensive fishing could reduce the concentrations of organohalogens, including the abundant, accumulative and toxic 2,3,4,7,8-PeCDF congener in the Baltic herring catch.

Topics: Age Factors; Animals; Benzofurans; Body Size; Environmental Monitoring; Female; Fishes; Hydrocarbons, Halogenated; Male; Naphthalenes; Oceans and Seas; Phenyl Ethers; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins; Water Pollutants, Chemical

A total of 156 fish composite samples were collected from five areas of the Baltic Sea and from three lakes and analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polybrominated diphenyl ethers (PBDEs). The European Union's maximum permissible level for PCDD/Fs, 4 pg WHO-TEQ/g fresh weight (fw), was exceeded in salmon, river lamprey and Baltic herring. In other species from the Baltic Sea, the 90th percentile was 3.42 pg WHO(PCDD/F)-TEQ/g fw. In the lake fish, the concentrations of PCDD/Fs, PCBs and PCNs were only 29-46% of those in the same species caught from the Baltic Sea, whereas the concentrations of PBDEs in the lake fish were as high as in the Baltic Sea fish. Dioxin-like PCBs contributed to the total dioxin-like toxicity of PCBs and PCDD/Fs by 49+/-12% in all the analysed samples.

Topics: Animals; Benzofurans; Dibenzofurans, Polychlorinated; Dioxins; Environmental Exposure; Finland; Fishes; Food Analysis; Fresh Water; Lampreys; Naphthalenes; Oceans and Seas; Phenyl Ethers; Polychlorinated Biphenyls; Polychlorinated Dibenzodioxins; Salmon; Water Pollutants, Chemical

Hydroxylation of dibenzo- p-dioxin (DD), dibenzofuran (DF), biphenyl (BP) and diphenyl ether (DPE) by the white-rot fungus Phlebia lindtneri GB-1027 was studied. DD and DF were rapidly degraded in a culture of P. lindtneri. The initial oxidation products were identified by gas chromatography-mass spectrometry. P. lindtneri oxidized DD to 2-hydroxy-DD, and DF to 2- and 3-hydroxy-DF. BP and DPE were also oxidized to p-hydroxy-BP and p-hydroxy-DPE, respectively. The oxidation catalyzed by P. lindtneri with each substrate was position-specific, because the hydroxyl group was introduced to the molecular edge of every substrate. Significant inhibition of the degradation of DD and DF was observed in incubation with the cytochrome P-450 monooxygenase inhibitors 1-aminobenzotriazole and piperonyl butoxide. These experiments with cytochrome P-450 inhibitors, and formation of the mono-hydroxyl metabolites suggest that P. lindtneri initially oxidizes DD, DF, BP, and DPE by a cytochrome P-450 monooxygenase and that it directly introduces a hydroxyl group to each of these substrates.

Topics: Basidiomycota; Benzofurans; Biodegradation, Environmental; Biphenyl Compounds; Cytochrome P-450 Enzyme System; Dioxins; Hydroxylation; Kinetics; Mass Spectrometry; Oxidation-Reduction; Oxygenases; Phenyl Ethers

The biotransformation of biphenyl, dibenzofuran, and diphenyl ether by 24 strains belonging to 18 species of the genus Trichosporon was investigated to assess the taxonomic relevance of this property at species and genus level. With the exceptions of T. brassicae and T. porosum CBS 2040, all other strains were able to transform the parent compounds to monohydroxylated intermediates. A second hydroxylation on the same aromatic ring was carried out by fewer strains and depended on the substrate. It appears that this step is the rate-limiting one in the biotransformation of the biarylic compounds tested. Ring fission of dihydroxylated derivatives of biphenyl was observed within 12 species. The aromatic ring system of dihydroxylated dibenzofuran was cleaved by strains of 5 species, while strains of 13 species were able to cleave the aromatic ring system of dihydroxylated diphenyl ether. Only 4 strains out of 18 species were able to cleave the aromatic ring system of all three parent compounds. These most active yeasts belong to the species T. coremiiforme, T. montevideense, T. mucoides, and T. sporotrichoides. In addition, strains of the species Cryptococcus curvatus and Cryptococcus humicola, closely related to the genus Trichosporon, were tested in parallel.

Topics: Benzofurans; Biodegradation, Environmental; Biphenyl Compounds; DNA, Fungal; DNA, Ribosomal; Mycological Typing Techniques; Phenyl Ethers; Phylogeny; RNA, Ribosomal; Trichosporon