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At least 343 records · Page 19Linked to original sources
PubMed2006

Natural and man-made organobromine compounds in marine biota from Central Norway.

Brominated organic pollutants were found in selected samples of mollusk tissue, fish liver, as well as in the eggs and livers of shag from three sites in Central Norway. More than 80 organobromines were identified owing to the defined isotope ratio acquired by GC/ECNI-MS. However, only a few peaks could be assigned to anthropogenic brominated flame retardants (polybrominated diphenyl ethers). Most of the organobromine compounds detected were unknown or halogenated natural products. The known halogenated natural products MHC-1 and TBA were abundant in all samples and usually between equally abundant, and up to 50 fold more concentrated than the major polybrominated diphenyl ether congener BDE 47. The halogenated natural products BC-2 (2-MeO-BDE 68) and BC-3 (6'-MeO-BDE 47), were on level with BDE 100 which was the second most abundant BDE congener in many samples. The previously identified natural polybrominated hexahydroxanthene derivatives (PBHDs) were detected for the first time in bird eggs. Being major contaminants in bird eggs, PBHDs were only present at low levels in bird liver from nestlings originating from the same clutch. Such differences were detected for several other major contaminants. One unknown tetrabromo compound particularly abundant in mussels from Munkholmen was studied by GC/MS and the molecular ion was detected at m/z 446. The abundance of the most important unknown compounds did not correlate with BDEs and they most likely represent halogenated natural products. This study supports that halogenated natural products have to be treated as serious contaminants of marine coastal waters. Our data suggest that their abundance is highest in habitats along the shoreline. Thorough examination of these compounds in environmental samples is an important task.

Animals↗
PubMed2004

The molecular structures of pentaborane(9) with halogen substituents in apical and basal positions, determined by electron diffraction and theoretical calculations.

The molecular structures of 1-bromo-pentaborane(9) and 2-bromo-pentaborane(9) in the gas phase have been determined by electron diffraction and ab initio and DFT computational methods. Computational methods have also been applied to the fluoro and chloro analogues, to 1,2-dibromo-pentaborane(9), and to the parent unsubstituted borane. The electronic effects of halogen substitution on the borane cage are remarkably small, particularly for chlorine and bromine substituents, and steric effects are also minimal, even in the compound with two bromine atoms. The largest effects are (a) lengthening of B((base))-B((apex)) bonds adjacent to the halogen in the 2-isomers, with an associated shortening of the opposite base-apex bond, (b) shortening of the B((base))-B((apex)) bond in the 1-fluoro compound, and (c) increase of the B((base))-B((apex))-F angle in 1-F-B(5)H(8), but a decrease in this angle in the 2-bromo compounds.

Journal Article↗
PubMed2003

Potential chlorinated and brominated interferences on the polybrominated diphenyl ether determinations by gas chromatography-mass spectrometry.

The analysis of polybrominated diphenyl ether (PBDE) congeners by GC-MS was studied in terms of potential interferences. Different MS approaches were normally used for the PBDE analyses: negative ion chemical ionization (NICI-MS) and electron ionization (EI-MS). This paper studied the presence of potential interferences in each instrumental technique approach, principally those corresponding to different chlorinated compounds (PCBs, PCNs, etc.) as well as brominated compounds (PBBs, MeO-PBDEs, TBBPA, etc.). The two ionization modes are subjected to different types of interferences. In general, EI-MS is affected by chlorinated interferences, especially PCBs. NICI-MS eliminated chlorinated interferences but presented different brominated interferences, well resolved with the EI-MS approach.

Bromine↗
PubMed2002

[Synthesis and anti alpha-adrenoceptor activity in vitro of 4-((4-((2-substitutedphenoxy)ethyl)-1-piperazinyl) methyl)- 1,2-dihydro-quinoline-2-one compounds].

AIM: To study the synthesis and anti alpha-adrenoceptor activity of 1,2-dihydro-quinoline-2-one compounds. METHODS: Acylation, bromination and cyclization, and substitute reactions were used in the synthesis of the title compounds IV. A proposed mechanism was showed to explain the unusual compounds 5 and 6 in the route C. The inhibition activity of the six target compounds were tested. RESULTS: Twelve new compounds were synthesized (II1-6 and IV1-6). Among them, six new compounds (IV1-6) are the title compounds. Structure of the title compounds were determined by IR, 1HNMR, MS and HRMS. CONCLUSION: Compounds IV3, IV4 and IV6 showed inhibitiion activity, and were worth further studying.

Adrenergic alpha-Antagonists↗
PubMed2004

The individual and cumulative effect of brominated flame retardant and polyvinylchloride (PVC) on thermal degradation of acrylonitrile-butadiene-styrene (ABS) copolymer.

Acrylonitrile-butadiene-styrene (ABS) copolymers without and with a polybrominated epoxy type flame retardant were thermally degraded at 450 degrees C alone (10 g) and mixed with polyvinylchloride (PVC) (8 g/2 g). Gaseous and liquid products of degradation were analysed by various gas chromatographic methods (GC with TCD, FID, AED, MSD) in order to determine the individual and cumulative effect of bromine and chlorine on the quality and quantity of degradation compounds. It was found that nitrogen, chlorine, bromine and oxygen are present as organic compounds in liquid products, their quantity depends on the pyrolysed polymer or polymer mixture. Bromophenol and dibromophenols were the main brominated compounds that come from the flame retardant. 1-Chloroethylbenzene was the main chlorine compound observed in liquid products. It was also determined that interactions appear at high temperatures during decomposition between the flame retardant, PVC and the ABS copolymer.

Acrylic Resins↗
PubMed2006

An intercalibration study on organobromine compounds: Results on polybrominated diphenylethers and related dioxin-like compounds.

An intercalibration study on organobromine compounds has been conducted to evaluate the accuracy and reliability in the analysis of brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and their related compounds like polybrominated and monobromo-polychlorinated dibenzodioxins and -furans (PBDDs/DFs, MoBPCDDs/DFs). This paper reports the results for these compounds in 'Mixed Standard Solutions' and 'Air-Dried Sediment'. The relative standard deviations (RSDs) for PBDEs, PBDDs/DFs and MoBPCDDs/DFs in mixed standard solutions ranged from 9% to 24%, 4% to 20% and 8% to 27%, respectively. The results of this study are better than those reported in earlier international interlaboratory studies due to general improvement in analytical methods and an increasing number of available authentic standards, particularly for PBDEs. In the analysis for higher brominated compounds such as octabromodibenzodioxin, the participants were advised to optimize the calibration curves befitting the range of concentrations found in samples because variation of relative response factors was noted. The results for 'Air-Dried Sediment' were also reasonable with RSDs from 10% to 38% for PBDEs, 8% to 38% for PBDDs/DFs and 17% to 36% for MoBPCDDs/DFs. In the sediment sample, possible errors in the sample pretreatment and/or interference by other compounds/impurities were indicated. The concentrations of pentabromodiphenylether, BDE100, varied more than the other PBDE isomers due to its poor separation in some chromatographic conditions. In addition, interference by PBDEs was observed in the analysis for PBDFs. Potential degradation/secondary formulation of PBDEs and PBDFs during the Soxhlet extraction were suggested when copper powder was added into the sediment samples. Inspite of these observations, the results in this study are better than those reported in other interlaboratory studies due to the advice given to participants for improving the results. Compared with the results for PCDDs/DFs (5-23% RSDs) and Co-PCBs (6-24% RSDs), the RSDs for most of the organobromine compounds were high, indicating an immature QA/QC approach for the analysis of PBDEs and related compounds in comparison to common chlorinated dioxins.

Calibration↗
PubMed1998

Synthesis, cancericidal and antimicrotubule activities of 3-(haloacetamido)-benzoylureas.

The four title compounds (not hitherto reported) were synthesized from 3-aminobenzoic acid through its trifluoroacetic acid-acid chloride derivative, reaction with urea and aminolytic deprotection to yield 3-aminobenzoylurea, followed by unconventional haloacetylation. Three key factors were found essential for antitumor activity: (i) the cytotoxic nature of the halogen: I > Br > Cl > F (ID90 0.014->10 microM); (ii) the position of the halogen: only the 3-position (meta) expressed relevant activity; and (iii) the presence of the urea group (1-position). The selectivity of the bromo and iodo compounds were higher than those of vinblastine and paclitaxel in terms of cytotoxicity (ID50 ratios in nonmalignant myocardial fibroblasts and CEM leukemia cells) and therapeutic indices (P338 leukemia bearing mice). Relevant mechanisms of bioactivity were mitotic arrest and apoptosis. Complete inhibition of microtubule assembly occurred in cell-free systems (at 2.8 versus 2.1 microM for vinblastine); in contrast to paclitaxel, the target compounds did not interfere with microtubule disassembly. The strong cancericidal and antimicrotubular activities of the bromine and iodine compounds justify further exploration of their potential in antineoplastic chemotherapy.

Animals↗
PubMed2006

Iron-mediated reduction rates and pathways of halogenated methanes with nanoscale Pd/Fe: analysis of linear free energy relationship.

The influence of halogen substitution in chlorinated methanes and brominated methanes on their abiotic reductive dehalogenation with nanoscale Pd/Fe bimetallic particles was investigated in this study. The 0.2% and 1.0% Pd/Fe particles, with particle sizes of less than 100nm, were synthesized in the laboratory. Reduction of the halogenated methanes with the Pd/Fe particles followed pseudo-first-order kinetics. The Pd/Fe bimetallic particles demonstrated at least an order of magnitude higher in reactivity compared to the unpalladized Fe particles of similar particle size. Comparing the 0.2% Pd/Fe and the 1.0% Pd/Fe particles, the latter exhibited higher reduction rates of various halogenated methanes. On the other hand, the reduction rates of chlorinated methanes were consistently lower than those of their brominated counterparts. The compounds with higher number of halogen substitutions were more readily reduced than the lightly halogenated ones. Coupled hydrogenolysis-elimination processes were the important mechanism for complete dehalogenation of the chlorinated and brominated methanes. From the kinetic examination of their transformation rates and mechanistic insight into the associated pathways, an attempt to analyze linear free energy relationship between the observed kinetics and the associated thermodynamic constants was performed. The observed reaction rate constants were analyzed for their correlations with one-electron potential (E(1)), two-electron potential (E(2)), bond dissociation energy (BDE) and the lowest unoccupied molecular orbital (LUMO) energy (E(LUMO)). LUMO energy appeared to be the best descriptor for the kinetic prediction, while E(1) and E(2) might be more suitable for mechanistic analysis.

Environmental Pollutants↗
PubMed1992

Chemical burns: our 10-year experience.

A review of 173 patients with chemical burns admitted to our burn unit was carried out during the years 1976-85. Most burns were work related (83 per cent). The majority of patients were men aged 21-50 years (mean age = 29.6 years). The mean total body surface area involved was 3.6 per cent (range = 1-30 per cent). The mean length of stay in hospital was 6.3 days (range = 1-52 days). The extremities were involved in 68 per cent of the patients. The more common aetiological agents were bromine and its compounds (36 per cent), then acids (21 per cent), alkalis and organic substances (14.5 per cent each). The severest burns were caused by the inorganic substances. Delayed admission was most characteristic of the bromine and alkali burns. Complications included local infection (19 cases), systemic infection (two cases), inhalation injury (two cases), tissue necrosis (one case) and corneal erosion (one case). There were no deaths. Increased awareness of the hazardous potential of chemicals should help reduce the incidence of chemical burns.

Accidents, Occupational↗
PubMed2005

Attaching the fluorine atom to organic molecules using BrF3 and other reagents directly derived from F2.

Elemental fluorine is a starting point for nucleophilic fluorinations (e.g., BrF3), radical fluorinations (e.g., F2 under irradiation), and electrophilic fluorinations (e.g., AcOF). All three categories are represented in this Account. Bromine trifluoride, although commercially available, can be readily made from the elements and is a very good source for naked nucleophilic fluoride ions. To minimize radical reactions, an anchor has to be installed in the molecules with which it reacts. Such an anchor is constituted of a soft base such as nitrogen and especially sulfur atoms. This reagent was used for constructing compounds with a CF2, CF3, CHF2, or CF2COOH group in specific sites. F2 itself was used for completing perfluorination of various polyfluoroethers, while the electrophilic acetyl hypofluorite is an excellent tool for introducing a single fluorine atom into organic molecules such as carboxylic acids and nitro compounds.

Bromine↗
PubMed1986

Synthesis and biological activities of 5-deaza analogues of aminopterin and folic acid.

N-[p-[[(2,4-Diaminopyrido[2,3-d]pyrimidin-6-yl)methyl] amino]benzoyl]-L-glutamic acid (1a, 5-deazaaminopterin) and the 5-methyl analogue (1b) were synthesized in 14 steps from 5-cyanouracil (4a) and 5-cyano-6-methyluracil (4b), respectively, by exploitation of the novel pyrimidine to pyrido[2,3-d]pyrimidine ring transformation reaction. The 5-cyanouracils 4 were treated with chloromethyl methyl ether to the 1,3-bis(methoxymethyl)uracils (5, which were treated with malononitrile in NaOEt/EtOH to give the pyrido[2,3-d]pyrimidines 6. Diazotization of 6 in concentrated HCl afforded the 7-chloro derivatives 8 in high yield. After reduction of 8, the 7-unsubstituted products 9 were reduced in the presence of Ac2O and the products, 6-(acetamidomethyl)pyridopyrimidines 10, were converted into the 6-acetoxymethyl derivatives 12 via nitrosation. After removal of the N-methoxymethyl groups from 12, the 6-(acetoxymethyl)pyrido[2,3-d]pyrimidine-2,4(1H,3H)-diones 14 were converted into 2,4-diamino-6-(hydroxymethyl)pyrido[2,3-d]pyrimidine (15a) and its 5-methyl analogue 15b by the silylation-amination procedure. Compounds 15 were brominated to the 6-bromomethyl derivatives 16, which were treated with diethyl (p-aminobenzoyl)-L-glutamate, and the products 17 were saponified to afford 5-deazaaminopterin (1a) and its 5-methyl analogue 1b. Compound 1b was also prepared by an alternative procedure in 10 steps from cyanothioacetamide and ethyl beta-(ethoxymethylene)acetoacetate via 2,4-diamino-6-(hydroxymethyl)-5-methylpyrido[2,3-d]pyrimidine (15b). 5-Deaza-5-methylfolic acid (2) was also prepared in four steps from 15b. The aminopterine analogues 1 showed significant anticancer activity in vitro and in vivo, whereas the folic acid analogue 2 did not exhibit any significant toxicity.

Aminopterin↗
PubMed2001

Simultaneous determination of halogenated derivatives of alkylphenol ethoxylates and their metabolites in sludges, river sediments, and surface, drinking, and wastewaters by liquid chromatography-mass spectrometry.

A quantitative solid-phase extraction-liquid chromatography/mass spectrometry (SPE-LC/MS) method is described for the simultaneous analysis of halogenated byproducts of alkylphenolic compounds and their degradation products formed during chlorine disinfection in the presence of bromide ions. Compounds analyzed include brominated and chlorinated nonylphenol ethoxylates (XN-PEOs); octylphenol ethoxylates (XOPEOs); nonylphenols (XNP); nonylphenoxycarboxylates (XNPECs) and their precursors nonionic surfactants, alkylphenol ethoxylates (APEOs); and their metabolites formed during sewage treatment, alkylphenoxycarboxylates (APECs) and alkylphenols (APs). Target compounds were concentrated from water samples using a C18 SPE procedure. Extracts were analyzed using reversed phase LC/MS. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ESI) interfaces were compared. ESI offered better sensitivity and specificity for a higher range of oligomers. Detection limits (LODs) for water samples were from 20 to 100 ng/L; and for sediment samples, from 2 to 10 microg/kg. Slightly higher LODs were obtained for sludge samples (5-25 microg/kg). Halogenated byproducts were found in sludge from Barcelona drinking water treatment plant in concentrations of 220 microg/kg for BrNP, 430 microg/kg for BrNPEOs (nEO = 1 - 2), and 1600 microg/kg for BrNPEOs (nEO = 3 - 15). The concentration of ClNPEOs was estimated to be in the order of 660 microg/kg (assuming the same response as BrNPEOs). Halogenated OPEOs were also identified, and their concentration was approximately 50 times lower than the concentration of NPEOs analogues. To our knowledge, this is the first method described that allows simultaneous determination of alkyphenol ethoxylates and halogenated derivatives, including degradation products.

Chromatography, High Pressure Liquid↗
PubMed1983

The biosynthesis of brominated pyrrolnitrin derivatives by Pseudomonas aureofaciens.

The mutant strain ACN of Pseudomonas aureofaciens ATCC 15926 produces several bromo derivatives of pyrrolnitrin. Five brominated amino- and three brominated nitrophenyl pyrrole compounds could be isolated, and their structures were established by 1H NMR, UV and mass spectroscopy. The isolated amino compounds showed no biological activity; the nitro derivatives inhibited the growth of Neurospora crassa ATCC 9276, though not as effective as pyrrolnitrin itself. 2-Carboxy-4-(2-amino-3-bromophenyl)pyrrole (X) is demonstrated to be an intermediate in the biosynthesis of brominated pyrrolnitrin; the biosynthetic pathway to bromo derivatives of pyrrolnitrin is discussed.

Antifungal Agents↗
PubMed2000

Phthalocyaninodehydroannulenes.

4-Bromo- and 4,5-dibromo-3,6-dibutoxyphthalonitrile have been prepared and treated with 3,6-didecylphthalonitrile in cross tetramerisation reactions in the presence of nickel acetate to afford monobromo- and dibromo-dibutoxyhexadecylphthalocyaninato nickel(II) complexes. Sonogashira and Stille coupling reactions on these compounds displaced the bromine substituents by ethynyl groups. Oxidative coupling of the monoethynyl derivatised nickel phthalocyanine afforded a butadiynyl-linked dinuclear phthalocyanine. The corresponding coupling reaction of the diethynylated phthalocyanine gave a mixture of phthalocyaninodehydroannulenes. Separation of the mixture yielded the diphthalocyaninodehydro[12]annulene as the major product. Electrospray mass spectrometry provides evidence for its aggregation in solution. The corresponding cyclic trimer, the triphthalocyaninodehydro[18]annulene, has been identified as a minor product. Both compounds show a large splitting of the Q-band absorption in the visible region spectrum. Most of the mononuclear phthalocyanine precursors exhibit discotic liquid crystal behaviour. The diphthalocyaninodehydro[12]annulene also enters a mobile phase on heating, but undergoes an irreversible change at 220 degrees C. MALDI-TOF mass spectrometry of the product reveals that the compound undergoes oligomerisation at this temperature.

Journal Article↗