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Sample records for tert-butyl ether benzene

  1. Exposure to methyl tert-butyl ether, benzene, and total hydrocarbons at the Singapore-Malaysia causeway immigration checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.; Ong, H.Y.; Kok, P.W. [and others

    1996-12-31

    The primary aim of this study was to determine the extent and levels of exposure to volatile organic compounds (VOCs) from automobile emissions in a group of immigration officers at a busy cross-border checkpoint. A majority (80%) of the workers monitored were exposed to benzene at levels between 0.01 and 0.5 ppm, with only 1.2% exceeding the current Occupational Safety and Health Administration occupational exposure limit of 1 ppm. The geometric mean (GM) concentrations of 8-hr time-weighted average exposure were 0.03 ppm, 0.9 ppm, and 2.46 ppm for methyl-tert-butyl ether (MTBE), benzene, and total hydrocarbons (THC), respectively. The highest time-weighted average concentrations measured were 1.05 ppm for MTBE, 2.01 ppm for benzene, and 34 ppm for THC. It was found that motorbikes emitted a more significant amount of pollutants compared with motor cars. On average, officers at the motorcycle booths were exposed to four to five times higher levels of VOCs (GMs of 0.07 ppm, 0.23 ppm, and 4.7 ppm for MTBE, benzene, and THC) than their counterparts at the motor car booths (GMs of 0.01 ppm, 0.05 ppm, and 1.5 ppm). The airborne concentrations of all three pollutants correlated with the flow of vehicle traffic. Close correlations were also noted for the concentrations in ambient air for the three pollutants measured. Benzene and MTBE had a correlation coefficient of 0.97. The overall findings showed that the concentrations of various VOCs were closely related to the traffic density, suggesting that they were from a common source, such as exhaust emissions from the vehicles. The results also indicated that although benzene, MTBE, and THC are known to be volatile, a significant amount could still be detected in the ambient environment, thus contributing to our exposure to these compounds. 4 refs., 6 figs.

  2. An efficient and highly selective ortho-tert-butylation of p-cresol with methyl tert-butyl ether catalyzed by sulfonated ionic liquids

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    Alamdari Reza Fareghi

    2014-01-01

    Full Text Available A novel series of sulfonic acid-functionalized ionic liquids (SFILs was found to act as efficient catalysts for ortho-tert-butylation of p-cresol with methyl tert-butyl ether (MTBE as the tert-butylating agent without an added solvent. The mono o-tert-butylated product was obtained in up to 80.4% isolated yield and 95.2% selectivity under such green conditions. No O-tert-butylated byproducts were formed.

  3. Removal of methyl tert-butyl ether (MTBE) with Nafion.

    Science.gov (United States)

    Lien, Hsing-Lung; Zhang, Wei-Xian

    2007-06-01

    A solid organic polymer, Nafion, is tested for the removal of methyl tert-butyl ether (MTBE) in water. Nafion with perfluorosulfonic acid backbone and terminal sulfonic acid groups has a surface acidity similar to 100% sulfuric acid, and has been commonly used as a strong-acid catalyst in many organic reactions. Sorption and subsequent transformation of MTBE were observed in batch experiments. The transformation of MTBE by porous nanocomposite Nafion SAC-13 to tert-butyl alcohol (TBA), acetone, isobutene and probably methanol was found. Subsequent transformation of TBA to acetone was also observed. Results suggest that transformational pathways may include hydrolysis, dehydrogenation and oxidation. Dissolved oxygen is needed for the oxidation of isobutene to acetone. As Nafion is insoluble in water, chemically stable, and regenerable, its use in packed-bed reactors for MTBE removal looks promising.

  4. Anaerobic biodegradation of methyl tert-butyl ether and tert-butyl alcohol in petrochemical wastewater.

    Science.gov (United States)

    Ghasemian, Mohammad; Amin, Mohammad Mehdi; Morgenroth, Eberhard; Jaafarzadeh, Neemat

    2012-09-01

    A laboratory-scale anaerobic sequencing batch reactor was used to evaluate treatment of a synthetic substrate mixture representing petrochemical wastewater containing methyl tert-butyl ether (MTBE), ethanol and acetic acid. Influent MTBE concentrations were 5, 10 and 50 mg/l (corresponding to MTBE loading rates of 0.2, 0.4 and 2 mg/l.d) with overall organic loading rates (OLRs) of 1.51, 3.23 and 3.25 g COD/1.d, respectively. These OLRs resulted in removal efficiencies for MTBE of 78%, 98% and 88%. Removal efficiencies for chemical oxygen demand were 85% and 90% with influent MTBE concentrations of 5 and 10mg/l, but were significantly reduced to 72% with influent MTBE concentrations of 50mg/l. During all reactor runs, effluent concentrations oftert-butyl alcohol (TBA) were below the detection limit. Batch degradation of the organic substrate mixture demonstrated initial inhibitory effects when exposed to MTBE concentrations of 50 mg/l and complete inhibition with MTBE concentrations above 2000 mg/l. It is interesting to note that in batch tests using MTBE as the sole organic substrate (initial MTBE concentrations of 50, 100 and 200 mg/l), the specific methanogenic activity decreased to below detection within the first 96 hours, but following a 72-hour lag phase the methane production increased again. Based on low volatile fatty acid (VFA) concentration, disappearance of TBA peaks and no findings of any other intermediate via gas chromatography/mass spectrometry, while the MTBE concentration is still high, it can be suggested that during the batch tests the breakdown of gas production and the following lag phase were the direct effect of higher MTBE concentrations (more than 50 mg/l) and not because of the TBA or VFA accumulations.

  5. Biodegradation of methyl tert-butyl ether by Kocuria sp.

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    Kiković Dragan D.

    2012-01-01

    Full Text Available Methyl tert-butyl ether (MTBE has been used to replace the toxic compounds from gasoline and to reduce emission of air pollutants. Due to its intensive use, MTBE has become one of the most important environment pollutants. The aim of this paper is isolation and identification of the bacteria from wastewater sample of “HIP Petrohemija” Pančevo (Serbia, capable of MTBE biodegradation. The results of the investigation showed that only the bacterial isolate 27/1 was capable of growth on MTBE. The result of sequence analyzes of 16S rDNA showed that this bacterial isolate belongs to the Kocuria sp. After the incubation period of 86 days, the degradation rates of initial MTBE concentration of 25 and 125 μg/ml were 55 and 36%, respectively. These results indicated that bacteria Kocuria sp. is successfully adapted on MTBE and can be potentially used in bioremediation of soils and waters contaminated with MTBE.

  6. Biodegradation of methyl tert-butyl ether (MTBE) by Enterobacter sp. NKNU02.

    Science.gov (United States)

    Chen, Ssu Ching; Chen, Colin S; Zhan, Kai-Van; Yang, Kai-Hsing; Chien, Chih-Ching; Shieh, Bao-Sen; Chen, Wen-Ming

    2011-02-28

    We previously isolated and identified Enterobacter sp. NKNU02 as a methyl tert-butyl ether (MTBE)-degrading bacterial strain from gasoline-contaminated water. In this study, tert-butyl alcohol, acetic acid, 2-propanol, and propenoic acid were detected using gas chromatography/mass spectrometry when MTBE was degraded by rest cells of Enterobacter sp. NKNU02 cells. We also found that biodegradation of MTBE was decreased, but not totally inhibited in mixtures of benzene, toluene, ethylbenzene and xylene. The effects of MTBE on the biology of Enterobacter sp. NKNU02 were elucidated using 2D proteomic analysis. The cytoplasmic proteins isolated from these MTBE-treated and -untreated cells were carried out for proteomic analysis. Results showed that there were 6 differential protein spots and 8 differential protein spots, respectively, as compared to their corresponding control (without MTBE addition), at the indicated incubation times when 40% and 60% of 100 mg/L of MTBE had been removed, Among these proteins, nine were successfully identified with matrix-assisted laser desorption ionization-time of flight-mass spectrometry. Proteins identified included extracellular solute-binding protein, periplasmic-binding protein ytfQ, cationic amino acid ABC transporter, isocitrate dehydrogenase, cysteine synthase A, alkyl hydroperoxide reductase (AhpC), transaldolase, and alcohol dehydrogenase. Based on these differential proteins, we discuss the bacterial responses to MTBE at the molecular level. Copyright © 2010 Elsevier B.V. All rights reserved.

  7. Hydrolysis of tert-butyl formate: Kinetics, products, and implications for the environmental impact of methyl tert-butyl ether

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    Church, Clinton D.; Pankow, James F.; Tratnyek, Paul G.

    1999-01-01

    Asessing the environmental fate of methyl tert-butyl ether (MTBE) has become a subject of renewed interest because of the large quantities of this compound that are being used as an oxygenated additive in gasoline. Various studies on the fate of MTBE have shown that it can be degraded to tert-butyl formate (TBF), particularly in the atmosphere. Although it is generally recognized that TBF is subject to hydrolysis, the kinetics and products of this reaction under environmentally relevant conditions have not been described previously. In this study, we determined the kinetics of TBF hydrolysis as a function of pH and temperature. Over the pH range of 5 to 7, the neutral hydrolysis pathway predominates, with kN = (1.0 ± 0.2) × 10−6/s. Outside this range, strong pH effects were observed because of acidic and basic hydrolyses, from which we determined that kA = (2.7 ± 0.5) × 10−3/(M·s) and kB = 1.7 ± 0.3/(M·s). Buffered and unbuffered systems gave the same hydrolysis rates for a given pH, indicating that buffer catalysis was not significant under the conditions tested. The activation energies corresponding to kN, kA, and kBwere determined to be 78 ± 5, 59 ± 4, and 88 ±11 kJ/mol, respectively. In all experiments, tert-butyl alcohol was found at concentrations corresponding to stoichiometric formation from TBF. Based on our kinetics data, the expected half-life for hydrolysis of TBF at pH = 2 and 4°C (as per some standard preservation protocols for water sampling) is 6 h. At neutral pH and 22°C, the estimated half-life is 5 d, and at pH = 11 and 22°C, the value is only 8 min.

  8. EFFECTS OF STIMULATOR SUBSTANCES ON AEROBIC METHYL TERT-BUTYL ETHER BIODEGRADATION BY MICROBIAL CONSORTIUM

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    M. Farrokhi ، S. Ahmadizad

    2009-04-01

    Full Text Available In this study dissolved humic substances and yeast extract were tested in different concentrations for enhancing methyl tert-butyl ether mineralization by isolated microorganisms from a variety of sources. All experiments were conducted at a constant temperature of 25ºC. Vials of 50 mL and 125 mL volume sealed with Teflon-lined Mini-Nert caps was used for microcosm experiments. In all experiments 1% sodium azide were used as control. Samples of bacterial cultures that metabolize methyl tert-butyl ether have been analysed by direct GC analysis using flame ionization detector. Cultures able to metabolize have been found in activated sludge and soils. These microorganisms weregram-positive bacterium. An aerobic microbial consortium was enriched in laboratory for four months. Methyl tert-butyl ether has been shown to biodegrade under aerobic and co-metabolic conditions. A microbial consortium isolated from activated sludges was identified as Cocobacillus. The concentration of the initial attached biomass was about 0.11 g/L of dry weight. The maximum mineralization rate and beneficial effects of stimulator substances on aerobic biodegradation of methyl tert-butyl ether occurred with the culture by combined concentrations of 500 mg/L of yeast extract and 20 mg/L of peat humic growth support of microbial consortium within 216 h and in presence of high oxygen levels and well mixing conditions. It was shown that adding, peat humic and yeast extract together, had better stimulatory effect on methyl tert-butyl ether biodegradation. Results clearly showed a stimulatory effect on methyl tert-butyl ether consumption higher than 20%. Consortium was capable of degrading concentrations of ≤1000 mg/L, whereas concentrations of >1000 mg/L, were not degraded.

  9. The screening of microorganisms capable of methyl tert-butyl ether (MTBE) biodegradation.

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    Wieczorek, Andrzej; Przybulewska, Krystyna; Karpowicz, Katarzyna; Nowak, Maciej J

    2013-01-01

    As a result of examinations carried out, 16 strains of microorganisms able to grow on mineral media with methyl tert-butyl ether as the sole source of carbon and energy were isolated. Bacteria prevailed among the isolated microorganisms. The growth of microorganisms under laboratory conditions was long and accompanied by low biomass increase. Under the conditions of the experiment, the isolated microorganisms did not show any quantitatively measurable biodegradability of methyl tert-butyl ether (MTBE) under aerobic conditions. This requires far-reaching caution with respect to trading in MTBE-modified petrols in order to protect the natural environment in Poland against contamination with that hard-to-biodegrade substance.

  10. TREATMENT OF METHYL TERT-BUTYL ETHER CONTAMINATED WATER USING PHOTOCATALYSIS

    Science.gov (United States)

    The feasibility of photo-oxidation treatment of methyl tert-butyl ether (MTBE) in water was investigated in three ways, 1) using a slurry falling film photo-reactor, 2) a batch solar reactor system, and 3) a combination of air-stripping and gas phase photooxidation system. MTBE-c...

  11. Distribution of methyl tert-butyl ether (MTBE) and selected water-quality constituents in the surficial aquifer at the Dover National Test Site, Dover Air Force Base, Delaware, 2001

    Science.gov (United States)

    Stewart, Marie; Guertal, William R.; Barbaro, Jeffrey R.; McHale, Timothy J.

    2004-01-01

    A joint study by the Dover National Test Site, Dover Air Force Base, Delaware, and the U.S. Geological Survey was conducted from June 27 through July 18, 2001, to determine the spatial distribution of the gasoline oxygenate additive methyl tert-butyl ether and selected water-quality constituents in the surficial aquifer underlying the Dover National Test Site. This report provides a summary assessment of the distribution of methyl tert-butyl ether and a preliminary screening of selected constituents that may affect natural attenuation and remediation demonstrations at the Dover National Test Site. The information gathered during this study is designed to assist potential remedial investigators who are considering conducting a methyl tert-butyl ether remedial demonstration at the test site. In addition, the study supported a planned enhanced bioremediation demonstration and assisted the Dover National Test Site in identifying possible locations for future methyl tert-butyl ether remediation demonstrations. A direct-push drill rig was used to collect a total of 147 ground-water samples (115 VOC samples and 32 quality-assurance samples) at varying depths. Volatile organic compounds were above the method reporting limits in 59 of the 115 ground-water samples. The concentrations ranged from below detection limits to maximum values of 12.4 micrograms per liter of cis-1,2-dichloro-ethene, 1.14 micrograms per liter of trichloro-ethene, 2.65 micrograms per liter of tetrachloro-ethene, 1,070 micrograms per liter of methyl tert-butyl ether, 4.36 micrograms per liter of benzene, and 1.8 micrograms per liter of toluene. Vinyl chloride, ethylbenzene, p,m-xylene, and o-xylene were not detected in any of the samples collected during this investigation. Methyl tert-butyl ether was detected in 47 of the 115 ground-water samples. The highest concentrations of methyl tert-butyl ether were detected in the surficial aquifer from ?4.6 to 6.4 feet mean sea level; however, methyl tert-butyl

  12. Estimation of the fraction of biologically active methyl tert-butyl ether degraders in a heterogeneous biomass sample

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    The fraction of biologically active methyl tert-butyl ether degraders in reactors is just as important for prediction of removal rates as knowledge of the kinetic parameters. The fraction of biologically active methyl tert-butyl ether degraders in a heterogeneous biomass sample, taken from a packed...... bed reactor, was determined using a batch kinetic based approach. The procedure involved modeling of methyl tert-butyl ether removal rates from batch experiments followed by parameter estimations. It was estimated to be 5-14% (w/w) of the measured volatile suspended solids concentration in the reactor....

  13. Artificial Neural Network Approach to Predict Biodiesel Production in Supercritical tert-Butyl Methyl Ether

    OpenAIRE

    Obie Farobie; Nur Hasanah

    2016-01-01

    In this study, for the first time artificial neural network was used to predict biodiesel yield in supercritical tert-butyl methyl ether (MTBE). The experimental data of biodiesel yield conducted by varying four input factors (i.e. temperature, pressure, oil-to-MTBE molar ratio, and reaction time) were used to elucidate artificial neural network model in order to predict biodiesel yield. The main goal of this study was to assess how accurately this artificial neural network model to predict b...

  14. Synthesis and Characterization of a Gasoline Oxygenate, Ethyl tert-Butyl Ether

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    Donahue, Craig J.; D'Amico, Teresa; Exline, Jennifer A.

    2002-06-01

    A laboratory procedure involving the synthesis and characterization of ethyl tert-butyl ether (ETBE) is described. This experiment has been used in a general chemistry sequence that includes a section on organic chemistry, but is also well suited for an introductory organic chemistry laboratory course. ETBE is prepared by the acid-catalyzed reaction of tert-butyl alcohol with ethyl alcohol. The product is recovered as a low-boiling azeotrope and purified by liquid liquid extraction with water. By using gas chromatography and IR spectroscopy to examine both the crude and the purified products, students can see how much the purity of their sample improves. They can also appreciate the value of these methods (especially GC) as tools to establish purity. Student results are presented. The use of ETBE and its more prominent cousin methyl tert-butyl ether (MTBE) as gasoline oxygenates has become very controversial because they have polluted underground water supplies. This lab permits students to prepare a compound that has a real use and regularly makes headlines in the news. This lab experiment is part of an effort to develop a general chemistry sequence for engineering students using the theme of "Chemistry and the Automobile".

  15. [Degradation of methyl tert-butyl ether (MTBE) by O3/H2O2].

    Science.gov (United States)

    Hu, Qin-Hai; Mao, Ke-Hui; Zhu, Miao-Jun; Zhang, Xing-Qing; Xiong, Yun-Long; Wang, Juan

    2008-05-01

    The degradation of methyl tert-butyl ether (MTBE) in water solution has been studied using the combination of ozone/hydrogen peroxide in a bubble column. Effects of air (containing O3) currents, quantities of H2O2, initial concentrations of MTBE, pH values and temperatures on the oxidation of MTBE have been tested, and it is implicated that under the conditions of initial MTBE concentration of 10 mg x L(-1), air current of 0.5 L x min(-1), pH 6.5, 293 K and 2.4 mg x L(-1) H2O2 addition, MTBE can be reduced by 75.5% and the removal rate of COD reaches 68.0% within 30 min. The main of degradation products identified are tert-butyl formate (TBF), tert-butyl alcohol (TBA), acetone (AC) and methyl acetate (MA). On the basis of that, the probable mechanism and pathway of the oxidation of MTBE by ozone/hydrogen peroxide have been proposed.

  16. Photo catalytic degradation of methyl tert-Butyl Ether (MTBE) from contaminated water: complete mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Eslami, A.; Nasseri, S.; Maleki, A.; Aghvami, T.

    2009-07-01

    Methyl tert-butyl ether (MTBE) has been commercially used as an octane enhancer to replace tetraethyl lead in gasoline since 1979. The high mobility, water solubility, and resistance to natural attenuation associated with MTBE may result in contamination of ground and surface waters. In this investigation the degradation of aqueous MTBE at relatively high concentrations was studied by UV-vis/TiO{sub 2}/O{sub 2} photo catalytic process. The effect of important operational parameters such as ph, oxygen flow, catalyst loading, and irradiation time were also studied. (Author)

  17. Enzymes and genes involved in the aerobic biodegradation of methyl tert-butyl ether (MTBE).

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    Lopes Ferreira, Nicolas; Malandain, Cédric; Fayolle-Guichard, Françoise

    2006-09-01

    Fuel oxygenates, mainly methyl tert-butyl ether (MTBE) but also ethyl tert-butyl ether (ETBE), are added to gasoline in replacement of lead tetraethyl to enhance its octane index. Their addition also improves the combustion efficiency and therefore decreases the emission of pollutants (CO and hydrocarbons). On the other hand, MTBE, being highly soluble in water and recalcitrant to biodegradation, is a major pollutant of water in aquifers contaminated by MTBE-supplemented gasoline during accidental release. MTBE was shown to be degraded through cometabolic oxidation or to be used as a carbon and energy source by a few microorganisms. We have summarized the present state of knowledge about the microorganisms involved in MTBE degradation and the MTBE catabolic pathways. The role of the different enzymes is discussed as well as the rare and recent data concerning the genes encoding the enzymes involved in the MTBE pathway. The phylogeny of the microorganisms isolated for their capacity to grow on MTBE is also described.

  18. Degradation of a recalcitrant xenobiotic compound: methyl tert-butyl ether (MTBE) metabolism by mycobacterium austroafricanum; Degradation d'un compose xenobiotique recalcitrant: metabolisme du methyl tert-butyl ether (MTBE) par mycobacterium austroafricanum IFP 2012

    Energy Technology Data Exchange (ETDEWEB)

    Francois, A.

    2002-11-01

    Methyl tert-butyl ether (MTBE) is introduced up to 15% (vol/vol) in gasoline in order to obtain a good octane number and to prevent carbon monoxide emissions. However, as a consequence of storage tanks leakage, MTBE became one of the major pollutants of aquifers because of its very low biodegradability. The present study aimed at investigating the biodegradation of MTBE by Mycobacterium austroafricanum IFP 2012. The MTBE metabolic pathway was partially elucidated owing to the identification of some intermediates (tert-butyl formate (TBF), tert-butyl alcohol (TBA), a-hydroxy-isobutyric acid and acetone) and some enzymatic activities (MTBE/TBA monooxygenase (non hemic and inducible), TBF esterase, 2-propanol: NDMA oxidoreductase and another monooxygenase involved in acetone degradation). The involvement of TBF and the requirement of cobalt could be explanations for the low natural attenuation of MTBE; whereas the methoxy group does not seem to be implicated. (author)

  19. Community characterization of anaerobic methyl tert-butyl ether (MTBE)-degrading enrichment cultures.

    Science.gov (United States)

    Youngster, Laura K G; Kerkhof, Lee J; Häggblom, Max M

    2010-05-01

    Use of the fuel oxygenate methyl tert-butyl ether (MTBE) has led to widespread environmental contamination. Anaerobic biodegradation of MTBE observed under different redox conditions is a potential means for remediation of contaminated aquifers; however, no responsible microorganisms have been identified as yet. We analyzed the bacterial communities in anaerobic-enriched cultures originating from three different contaminated sediments that have retained MTBE-degrading activity for over a decade. MTBE was transformed to tert-butyl alcohol and the methyl group used as a carbon and energy source. Terminal restriction fragment length polymorphism (T-RFLP) analysis of bacterial 16S rRNA genes showed that the MTBE-utilizing microcosms established from different sediment sources had substantially different community profiles, suggesting that multiple species are capable of MTBE biodegradation. The 16S rRNA genes from one enrichment culture were cloned and sequenced. Phylogenetic analysis showed a diverse community, with phylotypes belonging to the Proteobacteria, Bacteroidetes, Firmicutes, Chloroflexi and Thermotogae. Continued enrichment on MTBE further reduced the community to three predominant phylotypes, as evidenced by T-RFLP analysis, which were most closely related to the Deltaproteobacteria, Firmicutes and Chloroflexi. These three common operational taxonomic units were detectable in the enrichments from Atlantic and Pacific coastal samples. Identification of the microorganisms important in mediating anaerobic MTBE transformation will provide the foundation for developing tools for site assessment and bioremediation monitoring.

  20. Biodegradation of Methyl tert-Butyl Ether by Co-Metabolism with a Pseudomonas sp. Strain

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    Shanshan Li

    2016-09-01

    Full Text Available Co-metabolic bioremediation is supposed to be an impressive and promising approach in the elimination technology of methyl tert-butyl ether (MTBE, which was found to be a common pollutant worldwide in the ground or underground water in recent years. In this paper, bacterial strain DZ13 (which can co-metabolically degrade MTBE was isolated and named as Pseudomonas sp. DZ13 based on the result of 16S rRNA gene sequencing analysis. Strain DZ13 could grow on n-alkanes (C5-C8, accompanied with the co-metabolic degradation of MTBE. Diverse n-alkanes with different carbon number showed a significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA. When Pseudomonas sp. DZ13 co-metabolically degraded MTBE with n-pentane as the growth substrate, a higher MTBE-degrading rate (Vmax = 38.1 nmol/min/mgprotein, Ks = 6.8 mmol/L and lower TBA-accumulation was observed. In the continuous degradation experiment, the removal efficiency of MTBE by Pseudomonas sp. Strain DZ13 did not show an obvious decrease after five times of continuous addition.

  1. Vapor intrusion risk of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME) and ethyl tert-butyl ether (ETBE): A modeling study.

    Science.gov (United States)

    Ma, Jie; Xiong, Desen; Li, Haiyan; Ding, Yi; Xia, Xiangcheng; Yang, Yongqi

    2017-06-15

    Vapor intrusion of synthetic fuel additives represents a critical yet still neglected problem at sites contaminated by petroleum fuel releases. This study used an advanced numerical model to investigate the vapor intrusion potential of fuel ether oxygenates methyl tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and ethyl tert-butyl ether (ETBE). Simulated indoor air concentration of these compounds can exceed USEPA indoor air screening level for MTBE (110μg/m 3 ). Our results also reveal that MTBE has much higher chance to cause vapor intrusion problems than TAME and ETBE. This study supports the statements made by USEPA in the Petroleum Vapor Intrusion (PVI) Guidance that the vertical screening criteria for petroleum hydrocarbons may not provide sufficient protectiveness for fuel additives, and ether oxygenates in particular. In addition to adverse impacts on human health, ether oxygenate vapor intrusion may also cause aesthetic problems (i.e., odour and flavour). Overall, this study points out that ether oxygenates can cause vapor intrusion problems. We recommend that USEPA consider including the field measurement data of synthetic fuel additives in the existing PVI database and possibly revising the PVI Guidance as necessary. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Methyl tert-butyl ether (MTBE) degradation by ferrous ion-activated persulfate oxidation: feasibility and kinetics studies.

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    Chen, K F; Kao, C M; Wu, L C; Surampalli, R Y; Liang, S H

    2009-07-01

    The objective of this study was to evaluate the feasibility of using ferrous ion-activated persulfate oxidation to remediate groundwater contaminated with methyl tert-butyl ether (MTBE). In this study, batch experiments were conducted to evaluate the effects of various factors on the efficiency of MTBE degradation including persulfate concentrations, ferrous ion concentrations, and persulfate coupled with hydrogen peroxide. Results show that ferrous ion-activated persulfate oxidation was capable of degrading MTBE efficiently. Persulfate and ferrous ion concentrations correlated with MTBE degradation rates. However, excess addition of ferrous ion resulted in decreased MTBE degrading rates most likely because of competition for sulfate free radicals between ferrous ion and MTBE. Two main byproducts of MTBE degradation, tert-butyl formate and tert-butyl alcohol, were detected in the experiments; both were, however, subsequently degraded. Results of sulfate analysis show that proper addition of ferrous ion could prevent unnecessary persulfate decomposition.

  3. Degradation of methyl tert-butyl ether (MTBE) in water by glow discharge plasma.

    Science.gov (United States)

    Tong, Shaoping; Ni, Yanyan; Shen, Chensi; Wen, Yuezhong; Jiang, Xuanzhen

    2011-01-01

    This study evaluated the ability of the glow discharge plasma (GDP) technique to degrade methyl tert-butyl ether (MTBE) in an aqueous solution. The results showed that a large amount of hydrogen peroxide and highly active *OH free radicals were produced during the treatment. Various experimental parameters including discharge current, initial MTBE concentration and initial pH played significant roles on MTBE degradation. In addition, Fe2+ had a catalytic effect on the degradation of MTBE, which is potentially attributable to the reaction between Fe3+ and the hydrated electron. It was also confirmed that GDP was comparable to electrocatalytic oxidation and high-density plasma and more efficient than photocatalytic degradation techniques. These results suggest that GDP may become a competitive MTBE wastewater treatment technology.

  4. Epidemiology, toxicokinetics, and health effects of methyl tert-butyl ether (MTBE).

    Science.gov (United States)

    Phillips, Scott; Palmer, Robert B; Brody, Aaron

    2008-06-01

    This paper reviews the published information assessing the kinetics and potential for adverse health effects related to exposure to the fuel oxygenate, methyl tert-butyl ether (MTBE). Data were obtained from previously published reports, using human data where possible. If human data were not available, animal studies were cited. The kinetic profile of MTBE in humans is similar for ingestion and inhalation. The concentrations of MTBE to which the general public is expected to be exposed are orders of magnitude below concentrations that have caused adverse health effects in animals. Controlled human studies have not replicated early epidemiology studies that suggested, but did not confirm, a possible association between MTBE exposure and nonspecific health complaints.

  5. Volumetric properties of binary mixtures of alkoxyethanols with ethyl tert-butyl ether at various temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kinart, Cezary M. [Department of Chemistry, University of Lodz, 90-236 Lodz, Pomorska 163 (Poland)]. E-mail: ckinart@uni.lodz.pl; Nowak, Katarzyna [Department of Chemistry, University of Lodz, 90-236 Lodz, Pomorska 163 (Poland); Kinart, Wojciech J. [Department of Organic Chemistry, University of Lodz, 90-136 Lodz, Narutowicza 68 (Poland)

    2005-05-15

    Densities at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K in the binary liquid mixtures of ethyl tert-butyl ether with 2-methoxyethanol, 2-(2-methoxyethoxy)ethanol or 2-{l_brace}2-(2-methoxyethoxy)ethoxy{r_brace}ethanol have been measured over the entire mixture compositions. These data have been used to compute the excess molar volumes. The excess molar volumes are negative over the entire range of composition for all mixtures. The changes of V{sup E} with variations of the composition and the chain-length of the alkyl groups in the alkoxyethanol molecules are discussed in terms of intermolecular interactions.

  6. Degradation of aqueous methyl tert-butyl ether by photochemical, biological, and their combined processes

    Directory of Open Access Journals (Sweden)

    Azadeh Asadi

    2006-01-01

    Full Text Available The degradation of aqueous methyl tert-butyl ether (MTBE at relatively high concentrations was investigated by various photo-induced oxidation processes such as UV/H2O2 and UV/TiO2 as well as biological processes and their combination. It was shown that the degradation of MTBE by UV/H2O2 and TiO2 photocatalytic followed a first-order model with apparent rate constant of 1.31×10−1 and 1.21×10−2 min-1, respectively. It was observed that UV/H2O2/TiO2 process did not have any advantages over each of the other processes alone. The biodegradation of methyl tert-butyl ether (MTBE was evaluated using aerobic mixed culture with three different approaches, including ultimate biological oxygen demand (BODU assessment, nonacclimated, and acclimated mixed cultures. The apparent rate constant for the biodegradation of MTBE by nonacclimated mixed culture was 4.36×10−2 day-1. It was shown that the acclimatization of the mixed cultures enhanced the rate of biodegradation of MTBE to 3.24×10−1mg L-1h-1. Finally, the effects of the photocatalytic pretreatment of aqueous MTBE on its subsequent biological treatment were studied. It was observed that the rate of bioreaction was not enhanced and the photocatalytic pretreatment had adverse effects on its biological treatment so that the apparent rate constant decreased to 2.83×10−1 mg L-1h-1.

  7. Effects of co-substrates and inhibitors on the anaerobic O-demethylation of methyl tert-butyl ether (MTBE).

    Science.gov (United States)

    Youngster, Laura K G; Somsamak, Piyapawn; Häggblom, Max M

    2008-10-01

    Methyl tert-butyl ether (MTBE) contamination is widespread in aquifers near urban areas around the world. Since this synthetic fuel oxygenate is resistant to most physical methods of treating fuel-contaminated water, biodegradation may be a useful means of remediation. Currently, information on anaerobic MTBE degradation is scarce. Depletion has been observed in soil and sediment microcosms from a variety of locations and under several redox conditions, but the responsible organisms are unknown. We are studying anaerobic consortia, enriched from contaminated sediments for MTBE-utilizing microorganisms for over a decade. MTBE degradation occurred in the presence of other fuel components and was not affected by toluene, benzene, ethanol, methanol, or gasoline. Many aryl O-methyl ethers, such as syringic acid, that are O-demethylated by acetogenic bacteria, were also O-demethylated by the MTBE-utilizing enrichment cultures. The addition of these compounds as co-substrates increased the rate of MTBE degradation, offering a potentially useful method of stimulating the MTBE degradation rate in situ. Propyl iodide caused light-reversible inhibition of MTBE degradation, suggesting that the MTBE degradation process is corrinoid dependent. The anaerobic MTBE degradation process was not directly coupled to methanogenesis or sulfidogenesis and was inhibited by the bactericidal antibiotic, rifampicin. These results suggest that MTBE degradation is mediated by acetogenic bacteria.

  8. Adsorption of methyl tert-butyl ether using granular activated carbon : equilibrium and kinetic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.Z.; Chen, J.M. [Zhejiang Univ. of Technology, Hangzhou (China). College of Biological and Environmental Engineering; Zhang, J.X. [Yuhuan County Environmental Protection Bureau, Yuhuan (China)

    2010-04-01

    Methyl tert-butyl ether (MTBE) is used in gasoline as a replacement for lead in order to promote combustion efficiency. However, MTBE is one of the most frequently detected underground water pollutants caused by leaks in underground fuel storage tanks, and has been classified as a potential human carcinogen. This study investigated that adsorption of MTBE through a granular activated carbon filter. Pseudo-first order, pseudo-second order equation and intraparticle diffusion equation kinetic models were used to predict the constant rate of adsorption. The study showed that the pseudo-second order model accurately described the adsorption kinetics for the removal of MTBE from an aqueous solution onto granular activated carbon. The Lagergren first-order rate constant k{sub 1} and the pseudo-second order rate constant k{sub 2} decreased with initial increases of MTBE. A Boyd plot was used to demonstrate that external mass transfer is the principal rate-limiting step during the initial stages of adsorption. Results of the study indicated that granular activated carbon is an effective adsorbent for MTBE. 34 refs., 2 tabs., 7 figs.

  9. Exposure to methyl tert-butyl ether (MTBE) is associated with mitochondrial dysfunction in rat.

    Science.gov (United States)

    Saeedi, Arastoo; Omidi, Mahmoud; Khoshnoud, Mohammad Javad; Mohammadi-Bardbori, Afshin

    2017-05-01

    1. Methyl tert-butyl ether (MTBE) is commonly used as an octane booster and oxygenate additive to gasoline. The assumed toxic effects of MTBE on human health are a matter of great debate. Exposure to MTBE has been shown to induce oxidative damage and no mechanistic explanation is available so far. Our goals were to determine whether MTBE is a mitochondrial toxicant, if so, what mechanism(s) is involved. 2. Male Sprague-Dawley rats were received MTBE in drinking water for 3 months. At the end of treatments, animals were killed, liver and blood samples were collected for biochemical and histopathological studies, and oxidative stress biomarkers. The rat liver mitochondria were isolated and several mitochondrial indices were measured. 3. We found that zinc plasma levels were remarkably declined with MTBE and N, N, N', N'-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN; a zinc chelator) exposure. MTBE induced oxidative damage and caused mitochondrial dysfunctions in rats. Supplementation with zinc was able to protect against MTBE-induced cellular and sub-cellular toxicity. 4. Our results demonstrated that long-term exposure to MTBE is associated with zinc deficiency, oxidative stress, and mitochondrial energy failure in rat.

  10. Toxicity and biofilm-based selection for methyl tert-butyl ether bioremediation technology.

    Science.gov (United States)

    Guisado, I M; Purswani, J; Catón-Alcubierre, L; González-López, J; Pozo, C

    2016-12-01

    Extractive membrane biofilm reactor (EMBFR) technology offers productive solutions for volatile and semi-volatile compound removal from water bodies. In this study, the bacterial strains Paenibacillus etheri SH7(T) (CECT 8558), Agrobacterium sp. MS2 (CECT 8557) and Rhodococcus ruber strains A5 (CECT 8556), EE6 (CECT 8612) and EE1 (CECT 8555), previously isolated from fuel-contaminated sites, were tested for adherence on tubular semipermeable membranes in laboratory-scale systems designed for methyl tert-butyl ether (MTBE) bioremediation. Biofilm formation on the membrane surface was evaluated through observation by field-emission scanning electron microscope (FESEM) as well as the acute toxicity (as EC50) of the bacterial growth media. Moreover, extracellular polymeric substance (EPS) production for each strain under different MTBE concentrations was measured. Strains A5 and MS2 were biofilm producers and their adherence increased when the MTBE flowed through the inner tubular semipermeable membrane. No biofilm was formed by Paenibacillus etheri SH7(T), nevertheless, the latter and strain MS2 exhibited the lowest toxicity after growth on the EMBFR. The results obtained from FESEM and toxicity analysis demonstrate that bacterial strains R. ruber EE6, A5, P. etheri SH7(T) and Agrobacterium sp. MS2 could be excellent candidates to be used as selective inocula in EMBFR technology for MTBE bioremediation.

  11. Artificial Neural Network Approach to Predict Biodiesel Production in Supercritical tert-Butyl Methyl Ether

    Directory of Open Access Journals (Sweden)

    Obie Farobie

    2016-05-01

    Full Text Available In this study, for the first time artificial neural network was used to predict biodiesel yield in supercritical tert-butyl methyl ether (MTBE. The experimental data of biodiesel yield conducted by varying four input factors (i.e. temperature, pressure, oil-to-MTBE molar ratio, and reaction time were used to elucidate artificial neural network model in order to predict biodiesel yield. The main goal of this study was to assess how accurately this artificial neural network model to predict biodiesel yield conducted under supercritical MTBE condition. The result shows that artificial neural network is a powerful tool for modeling and predicting biodiesel yield conducted under supercritical MTBE condition that was proven by a high value of coefficient of determination (R of 0.9969, 0.9899, and 0.9658 for training, validation, and testing, respectively. Using this approach, the highest biodiesel yield was determined of 0.93 mol/mol (corresponding to the actual biodiesel yield of 0.94 mol/mol that was achieved at 400 °C, under the reactor pressure of 10 MPa, oil-to-MTBE molar ratio of 1:40 within 15 min of reaction time.

  12. Cometabolism of methyl tert-butyl ether by a new microbial consortium ERS.

    Science.gov (United States)

    Li, Shanshan; Li, Danni; Yan, Wei

    2015-07-01

    The release of methyl tert-butyl-ether (MTBE) into the environment has increased the worldwide concern about the pollution of MTBE. In this paper, a microbial consortium was isolated from the soil sample near an oil station, which can degrade MTBE directly with a low biomass yield and MTBE degrading efficiency. Further research has indicated that this consortium can degrade MTBE efficiently when grown on n-octane as the cometabolic substrate. The results of 16S rDNA based on phylogenetic analysis of the selected operating taxonomic units (OTUs) involved in the consortium revealed that one OTU was related to Pseudomonas putida GPo1, which could cometabolically degrade MTBE on the growth of n-octane. This may help explain why n-octane could be the optimal cometabolic substrate of the consortium for MTBE degradation. Furthermore, the degradation of MTBE was observed along with the consumption of n-octane. Different K s values for MTBE were observed for cells grown with or without n-octane, suggesting that different enzymes are responsible for the oxidation of MTBE in cells grown on n-octane or MTBE. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism.

  13. Adsorption of methyl tert-butyl ether (MTBE) from aqueous solution by porous polymeric adsorbents.

    Science.gov (United States)

    Ji, Biyan; Shao, Fei; Hu, Guanjiu; Zheng, Shourong; Zhang, Qingmei; Xu, Zhaoyi

    2009-01-15

    MTBE has emerged as an important water pollutant because of its high mobility, persistence, and toxicity. In this study, a postcrosslinked polymeric adsorbent was prepared by postcrosslinking of a commercial chloromethylated polymer, and a nonpolar porous polymer with comparable surface area and micropore volume to the postcrosslinked polymer was prepared by suspended polymerization. The postcrosslinked polymer, nonpolar porous polymer and chloromethylated polymer were characterized by N2 adsorption, FTIR and XPS analysis. Results showed that postcrosslinking reaction led to the generation of a microporous postcrosslinked polymer with BET surface area 782m2g(-1), average pore width 3.0nm and micropore volume 0.33cm3g(-1). FTIR and XPS analysis indicated the formation of surface oxygen-containing groups on the postcrosslinked polymer. The three polymers were used as adsorbents to remove aqueous methyl tert-butyl ether (MTBE). Adsorption of MTBE over the postcrosslinked polymeric adsorbent was found to follow the linear adsorption isotherm, whereas MTBE adsorption onto the nonpolar porous polymer and chloromethylated polymer followed Langmuir adsorption model. Comparison of adsorption capacities of the postcrosslinked polymer, chloromethylated polymer and nonpolar porous polymer revealed that the adsorption of MTBE from aqueous solution is dependent on both pore structure and surface chemistry of polymeric adsorbents, and the high adsorption efficiency of the postcrosslinked polymer towards MTBE is attributed to its high surface area, large micropore volume and moderate hydrophility. The process of MTBE adsorption onto the adsorbents can be well described by pseudo-second-order kinetics, and the rate of adsorption decreased at higher MTBE initial concentration.

  14. The effects of methyl tert-butyl ether (MTBE) on the male rat reproductive system.

    Science.gov (United States)

    Li, Dongmei; Yuan, Chuntao; Gong, Yi; Huang, Yufeng; Han, Xiaodong

    2008-07-01

    Methyl tert-butyl ether (MTBE) is an oxygenated compound, which has been widely used in Asia, Europe and North America. Although numerous in vitro and in vivo studies have demonstrated the carcinogenicity and the toxicity of MTBE, there is still a lack of data on reproductive system exposure of MTBE in male rodent animals. We studied subacute exposure of MTBE on the reproductive systems of male Sprague-Dawley rats. MTBE was administered to rats at dose levels of 0, 400, 800 and 1600 mg/kg/day. After 2 or 4 weeks of treatments, the rats were euthanized, and their serum, epididymis and testes were collected. Significant adverse effects in their reproductive system were observed including: a significant increase in the percentage of abnormal sperm; an irregular and disordered arrangement of the seminiferous epithelium indicated by a histopathological examination; changed serum levels of testosterone (T), luteinizing hormone (LH) and follicle stimulating hormone (FSH); and decreased levels of mRNA and of androgen binding protein (ABP). In the oxidative stress study, results indicated an increased maleic dialdehyde (MDA) content, implying a raised peroxide level, and that the total antioxidant ability in serum was significantly increased. This finding was especially strong at 1600 mg/kg/day MTBE. In the 2-week treatment, at 1600 mg/kg/day, the mRNA level of 8-oxoguanine DNA glycosidase (OGG1) was significantly decreased, and the mRNA level of the extra-cellular form of superoxide dismutase (SOD(EX)) was significantly increased. Our experiments suggest that relatively high doses of MTBE can exert reproductive system toxicity of male rats and disturb the secretions of T, LH and FSH, possibly due to oxidative stress induced by MTBE.

  15. Impact of activation methods on persulfate oxidation of methyl tert-butyl ether.

    Science.gov (United States)

    Deng, Dayi; Peng, Libin; Guan, Mengyun; Kang, Yuan

    2014-01-15

    To provide guidance on the selection of proper persulfate processes for the remediation of MTBE contaminated groundwater, MTBE aqueous solutions were treated with three common field persulfate processes including heat activated persulfate, Fe(III)-EDTA activated persulfate and alkaline persulfate, respectively. The results were compared with MTBE oxidation by Fenton's reagent and persulfate alone at 25°C. The impact of the activating conditions on the fate of MTBE and its daughter products was investigated. Heat activation at 40°C offered the most rapid removal of MTBE and its daughter products, while Fe(III)-EDTA activation showed higher efficiency of MTBE removal but low removal efficiency of its daughter products. On the other hand, alkaline persulfate showed slower kinetics for the removal of MTBE and less accumulation of the daughter products. Furthermore, tert-butyl alcohol and acetone were observed as the main purgeable daughter products along with a small amount of tert-butyl formate in persulfate oxidation of MTBE, while tert-butyl formate, tert-butyl alcohol and acetone were the main products in Fenton oxidation. Mechanistic analysis suggests that degradation of MTBE by persulfate most likely happens via non-oxygen demand pathways, different from the dominant oxygen demand degradation pathways observed in Fenton oxidation. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Methyl tert-butyl ether (MTBE) in river and wastewater in Germany.

    Science.gov (United States)

    Achten, Christine; Kolb, Axel; Püttmann, Wilhelm; Seel, Peter; Gihr, Regine

    2002-09-01

    An overview of methyl tert-butyl ether (MTBE) concentrations in German river water (315 samples) and wastewater (82 samples) is given. In the agglomerated area of Frankfurt/M, several samples of surface water, wastewater, and industrial effluents were analyzed for its MTBE content from 1999 to 2001. MTBE was analyzed by a combination of headspace-solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS). Rhine and Main water concentrations of MTBE in the lower parts of the rivers were approximately 250 ng/L and 200 ng/L, respectively. The concentrations increased from the upper parts of the rivers to its mouths. Water from the Elbe, Neckar, and Weser rivers showed lower MTBE concentrations, and the ether was not detected in the Danube river. Generally, higher MTBE concentrations were detected at urban agglomerations compared to rural areas. Small urban creeks without significant industrial input showed MTBE concentrations of approximately 50 ng/L, and it was hardly detectable in small rural creeks. Higher MTBE concentrations in river water were correlated with increased concentrations of the oxygenate measured in precipitation. Most MTBE concentrations in river water fell in the range of 50-200 ng/L (32%), 10-50 ng/L (28%), and 200-1000 ng/L (26%). MTBE concentrations in German surface water and air are 3-17 times lower compared to Californian data. Wastewater samples from influents of two sewage plants showed MTBE concentrations of approximately 100-300 ng/L, and a loading of 2-37 kg/a was calculated. An eliminated MTBE percentage of roughly 30-35% of MTBE in the plants was estimated. Industrially influenced samples of river water or public wastewater and industrial effluents showed MTBE concentrations of up to 2267 ng/L and 28 microg/L, respectively. This input has not been considered before because only 1.5% of the produced amount of MTBE in Germany is used for industrial processes, but it should not be neglected because MTBE is very

  17. Vacuum ultraviolet photoionization and ab initio Investigations of methyl tert-butyl ether (MTBE) clusters and MTBE-water clusters

    Science.gov (United States)

    Di Palma, Tonia M.; Bende, Attila

    2013-03-01

    The structures and energetics of neutral, ionized and protonated methyl tert-butyl ether (MTBE) clusters and (MTBE)m(H2O)n clusters are investigated by tunable vacuum-UV photoionization mass spectrometry and DFT calculations. While the mass spectra of bare MTBE clusters show unprotonated and protonated clusters ions, the mass spectra of mixed clusters show protonated ions that exhibit magic numbers that correspond to n = m - 2 combinations. Ab initio calculations show that in the larger clusters a multiple proton transfer leads to a protonated water core where all available hydrogen bonds interact with MTBE molecules. The resulting bond structure explains the cluster stability.

  18. Methyl tert-Butyl Ether (MTBE) in Ground Water, Air, and Precipitation at North Windham, Maine

    Science.gov (United States)

    Nielsen, Martha G.; Peckenham, John M.

    2000-01-01

    Thirty-one monitoring wells in the Windham aquifer in North Windham, Maine, were sampled for methyl tert-butyl ether (MTBE) from July 1998 to May 1999. MTBE was detected in 35 percent of the wells sampled in the Windham aquifer. MTBE was detected in 64 percent of wells in the high-yielding part of the aquifer; these wells account for 82 percent of all wells with detectable MTBE. Land cover also was found to be associated with MTBE in the wells in the study area, with the urban and low-density residential areas having more MTBE than undeveloped areas. The median concentration in wells with detectable MTBE was 1.13 micrograms per liter. Air and precipitation samples were collected in North Windham along with ground-water samples. Air samples were collected every 10 days from December 1998 to July 1999 (20 samples). MTBE was present in all 20 air samples collected, at concentrations ranging from 0.03 ppbv (parts per billion by volume) to 1.0 ppbv. Before Maine opted out of the reformulated gasoline (RFG) program in the spring of 1999, median concentrations in air at the North Windham site were 0.25 ppbv. After Maine stopped using RFG, the median concentration in air dropped to 0.09 ppbv. No MTBE was detected in four samples of precipitation at North Windham. The lack of rainfall during the study period prevented the collection of an adequate number of samples, and technical difficulties negated the results of some of the analyses of the samples that were collected. Based on the equilibrium partitioning of MTBE from the air into rain, the hypothetical average concentration of MTBE in rainfall during months when recharge typically occurs (March-April and October-December) would be approximately 0.3 to 0.4 micrograms per liter during the time that RFG was being used in Maine. After the phaseout of RFG, the maximum average concentration of MTBE in rainfall during these months would be approximately 0.1 micrograms per liter. The distribution and concentrations of MTBE that

  19. [Methyl tert-butyl ether (MTBE) in atmosphere of the Pearl River Delta, China].

    Science.gov (United States)

    Wang, Bo-guang; Shao, Min; Zhang, Yuan-hang; Lü, Wan-Ming; Zhou, Yan

    2007-07-01

    The concentration of methyl tert-butyl ether (MTBE) and its spatio-temporal distribution were researched in atmosphere of the Pearl River Delta (PRD) by sampling with air sampling canisters and analyzing with pre-concentrator and gas chromatograph-mass spectrum instrument. The results showed that 1) MTBE could be prevalently checked in atmosphere of traffic area, industrial area, residential area and commercial area of the PRD, and its range of hourly average concentration in the long-term observation was from 0 - 1.250 microg m(-3), the summer had more serious pollution than the spring, and urban was the central area of high MTBE concentration, and suburban in the downwind was obviously polluted by the urban air. 2) During the enhanced observation in summertime, the diurnal average concentration of Guangzhou urban site was (1.520 +/- 0.370) microg m(-3), which was about 7 times of Huadou site in the downwind of Guangzhou and over 100 times of Conghua site in the background of Guangzhou. In urban, 2 peak values appeared in the period of 10:00 - 12:00 and 16:00 - 18:00 respectively, and the nighttime had the lowest average concentration, but the suburban in the downwind had the peak value in the nighttime. 3) During the enhanced observation in wintertime, the diurnal average concentration of Guangzhou urban site was (0.950 +/- 0.240) microg m(-3), which was 3.6 times of Xinken site in the downwind of Guangzhou. Several peak values appeared on the diurnal variation, the high concentration period of urban was in 18:00 - 22:00, and that of suburban was in 04:00 - 10:00 of the next day. 4) When it was weak sunshine, the concentration of MTBE beside the urban traffic roadside was decreasing with the height increasing, but when it was strong sunshine, it was increasing with the height increasing. So, except the original emission from the automobiles, MTBE still had the secondary pollution sources formed by air photochemical reaction.

  20. Pyrolysis of methyl tert-butyl ether (MTBE). 2. Theoretical study of decomposition pathways.

    Science.gov (United States)

    Zhang, Taichang; Zhang, Lidong; Wang, Jing; Yuan, Tao; Hong, Xin; Qi, Fei

    2008-10-23

    The thermal decomposition pathways of MTBE have been investigated using the G3B3 method. On the basis of the experimental observation and theoretical calculation, the pyrolysis channels are provided, especially for primary pyrolysis reactions. The primary decomposition pathways include formation of methanol and isobutene, CH4 elimination, H2 elimination and C-H, C-C, C-O bond cleavage reactions. Among them, the formation channel of methanol and isobutene is the lowest energy pathway, which is in accordance with experimental observation. Furthermore, the secondary pyrolysis pathways have been calculated as well, including decomposition of tert-butyl radical, isobutene, methanol and acetone. The radicals play an important role in the formation of pyrolysis products, for example, tert-butyl radical and allyl radical are major precursors for the formation of allene and propyne. Although some isomers (isobutene and 1-butene, allene and propyne, acetone and propanal) are identified in our experiment, these isomerization reaction pathways occur merely at the high temperature due to their high activation energies. The theoretical calculation can explain the experimental results reported in part 1 and shed further light on the thermal decomposition pathways.

  1. A comparative study of biodiesel production using methanol, ethanol, and tert-butyl methyl ether (MTBE) under supercritical conditions.

    Science.gov (United States)

    Farobie, Obie; Matsumura, Yukihiko

    2015-09-01

    In this study, biodiesel production under supercritical conditions among methanol, ethanol, and tert-butyl methyl ether (MTBE) was compared in order to elucidate the differences in their reaction behavior. A continuous reactor was employed, and experiments were conducted at various reaction temperatures (270-400 °C) and reaction times (3-30 min) and at a fixed pressure of 20 MPa and an oil-to-reactant molar ratio of 1:40. The results showed that under the same reaction conditions, the supercritical methanol method provided the highest yield of biodiesel. At 350 °C and 20 MPa, canola oil was completely converted to biodiesel after 10, 30, and 30 min in the case of - supercritical methanol, ethanol, and MTBE, respectively. The reaction kinetics of biodiesel production was also compared for supercritical methanol, ethanol, and MTBE. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Energy analysis for the production of biodiesel in a spiral reactor using supercritical tert-butyl methyl ether (MTBE).

    Science.gov (United States)

    Farobie, Obie; Matsumura, Yukihiko

    2015-11-01

    In this study, energy analysis was conducted for the production of biodiesel in a spiral reactor using supercritical tert-butyl methyl ether (MTBE). This study aims to determine the net energy ratio (NER) and energy efficiency for the production of biodiesel using supercritical MTBE and to verify the effectiveness of the spiral reactor in terms of heat recovery efficiency. The analysis results revealed that the NER for this process was 0.92. Meanwhile, the energy efficiency was 0.98, indicating that the production of biodiesel in a spiral reactor using supercritical MTBE is an energy-efficient process. By comparing the energy supply required for biodiesel production between spiral and conventional reactors, the spiral reactor was more efficient than the conventional reactor. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Cytotoxicity and oxidative stress study in cultured rat Sertoli cells with methyl tert-butyl ether (MTBE) exposure.

    Science.gov (United States)

    Li, Dongmei; Liu, Qin; Gong, Yi; Huang, Yufeng; Han, Xiaodong

    2009-04-01

    Cultured Sertoli cells were tested for their cytotoxicity and oxidative stress induced by methyl tert-butyl ether (MTBE) which has been extensively used as a gasoline additive. In cytotoxic experiments, Sertoli cells were cultured with medium alone (control), 5, 500, or 50,000 microM MTBE. Lactate dehydrogcnase (LDH) leakage assay, staining with fluorescein diacetate (FDA) and propidium iodide (PI), and flow cytometric analyses were used. In oxidative stress experiments, Sertoli cells were cultured with medium alone (control), 0.5, 50, or 5000 microM MTBE. The production of reactive oxygen species (ROS), maleic dialdehyde (MDA) content and the level of superoxide dismutase (SOD) activity in cell supernatants were measured. Meanwhile, the expression level of 8-oxoguanine DNA glycosidase (OGG1) and extracellular form of superoxide dismutase (SOD(EX)) in Sertoli cells were determined by RT-PCR. We also compared the current findings with the previous findings in rat spermatogenic cells exposed to MTBE. The present data indicate that high dose MTBE may exert a direct toxic effect on Sertoli cells. Oxidative stress induced by MTBE is a possible mechanism of cytotoxicity.

  4. Disturbance of zinc and glucose homeostasis by methyl tert-butyl ether (MTBE); evidence for type 2 diabetes.

    Science.gov (United States)

    Saeedi, Arastoo; Fardid, Reza; Khoshnoud, Mohammad Javad; Kazemi, Elaheh; Omidi, Mahmoud; Mohammadi-Bardbori, Afshin

    2017-06-01

    1. The prevalence of diabetes and the other metabolic disorders has noticeably increased worldwide. A causal link between increasing risk of type 2 diabetes and exposure to environmental pollutants has been reported. 2. We hypothesized that exposure to methyl tert-butyl ether (MTBE), an oxygenate additive to gasoline would hinder zinc and glucose homeostasis in rats. 3. Male Sprague-Dawley rats received MTBE in drinking water for 90 days. At the end of the treatment, pancreas and blood samples were collected for biochemical and molecular examinations. Expression of four candidate genes, including Insulin1, Insulin2, MT1A, SLC30A8 by Real-Time Quantitative PCR (Q-PCR) as well as biochemical parameters, including fasting blood glucose (FBS), triglycerides (TG), cholesterol (CHO), low-density lipoprotein (LDL), high-density lipoprotein (HDL), copper (Cu(2+)) and calcium (Ca(2+)) levels as well as High-sensitive C-reactive protein were assessed as endpoints. 4. This study suggested that MTBE exposure can be associated with disruption in zinc homeostasis and glucose tolerance.

  5. Antichaperone activity and heme degradation effect of methyl tert-butyl ether (MTBE) on normal and diabetic hemoglobins.

    Science.gov (United States)

    Najdegerami, Ismaeil Hossein; Maghami, Parvaneh; Sheikh-Hasani, Vahid; Hosseinzadeh, Ghader; Sheibani, Nader; Moosavi-Movahedi, Ali A

    2017-05-01

    Because of the extensive use of methyl tert-butyl ether (MTBE) as an additive to increase the octane quality of gasoline, the environmental pollution by this compound has increased in recent decades. Environmental release of MTBE may lead to its entry to the blood stream through inhalation or drinking of contaminated water, and its interactions with biological molecules such as proteins. The present study was proposed to comparatively investigate the interactions of MTBE with hemoglobin (Hb) from diabetic and nondiabetic individuals using various spectroscopic methods including UV-visible, fluorescence, chemiluminescence, and circular dichroism. These results demonstrated the effects of MTBE on heme degradation of Hb and the reaction of these degradation products with water generating reactive oxygen species. Interaction of Hb with MTBE enhanced its aggregation rate and decreased lag time, indicating the antichaperone activity of MTBE upon interaction with Hb. Furthermore, the diabetic Hb showed more severe effects of MTBE, including heme degradation, reactive oxygen species production, unfolding, and antichaperone behavior than the nondiabetic Hb. The results from molecular docking suggested that the special interaction site of MTBE in the vicinity of Hb heme group is responsible for heme degradation. Copyright © 2016 John Wiley & Sons, Ltd.

  6. Methyl tert-butyl ether (MTBE) induced Ca(2+)-dependent cytotoxicity in isolated rabbit tracheal epithelial cells.

    Science.gov (United States)

    Wang, Yajing; Chen, Chang; Wu, Tao; Xu, Jing; Han, Xiaodong

    2008-10-01

    As a volatile synthetic organic chemical, methyl tert-butyl ether (MTBE) was the most common gasoline additive. The increasing use of MTBE raised concern over its health safety. Inhalation was the principle route of exposure for the general population. This study used a model of rabbit tracheal epithelial cells (RTEs) in primary culture to investigate the cytotoxic effects induced by MTBE and the potential mechanism. RTEs were incubated with medium alone (control), 0.5, 50, 5000ppm MTBE respectively. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazo liumbromide) assay, staining with fluorescein diacetate, propidium iodide and lactate dehydrogenase leakage ratio were used to assess MTBE cytotoxicity on cells. We also observed a significant elevation in cytosolic Ca2+ by fluorescence probe Fluo-3AM at 3, 6 and 12h following exposure to MTBE. Loss of mitochondrial membrane potential (MMP) was detected following 12 and 24h treatment of NP and assessment by rhodamine 123 (Rh123) staining. Activity changes of the Ca(2+)-ATPase, Ca(2+)-Mg(2+)-ATPase following MTBE treatment displayed a similar trend, suggesting an initial elevation before 6h and subsequent dramatic decrease at 12h. Our results demonstrated that induction of cell injury, associated with mitochondrial dysfunction, and alterations in cytosolic Ca2+ in RTEs represent key mechanisms by which MTBE exerts its cytotoxic effects.

  7. UV absorption spectra and kinetics for alkyl and alkyl peroxy radicals originating from di-tert-butyl ether

    DEFF Research Database (Denmark)

    Nielsen, O.J.; Sehested, J.; Langer, S.

    1995-01-01

    Alkyl, (CH3)(3)COC(CH3)(2)CH2, and alkyl peroxy, (CH3)(3)COC(CH3)(2)CH2O2, radicals from di-tert-butyl ether (DTBE), have been studied in the gas phase at 296 K. A pulse radiolysis UV absorption technique was used to measure the spectra and kinetics. Absorption cross sections were quantified over...... the wavelength range 220-330 nm. At 240 nm, sigma((CH3)3COC(CH3)2CH2) = (3.6 +/- 0.4) X 10(-18) cm(2) molecule(-1) and at 260 nm, sigma((CH3)3COC(CH3)2CH2) = (3.8 +/- 0.3) X 10(-18) cm(2) molecule(-1) have been obtained. The observed rate constants for the self-reaction of (CH3)(3)COC(CH3)(2)CH2 and (CH3)(3)COC...

  8. Method detection limit determination and application of a convenient headspace analysis method for methyl tert-butyl ether in water.

    Science.gov (United States)

    O'Neill, Dennis T; Rochette, Elizabeth A; Ramsey, Philip J

    2002-11-15

    Methyl tert-butyl ether (MTBE) is a common groundwater contaminant, introduced to the environment by leaking petroleum storage tanks, urban runoff, and motorized watercraft. In this study. a simplified (static) headspace analysis method was adapted for determination of MTBE in water samples and soil water extracts. The MDL of the headspace method was calculated to be 2.0 microg L(-1) by the EPA single-concentration design method(1) and 1.2 microg L(-1) by a calibration method developed by Hubaux and Vos (Hubaux, A.; Vos, G. Anal. Chem. 1970,42, 849-855). The MDL calculated with the Hubaux and Vos method was favored because it considers both a true positive and a false positive. The static headspace method was applied to analysis of a tap water sample and a monitoring well sample from a gasoline service station, a river sample, and aqueous extracts from soil excavated during removal of a leaking underground storage tank (LUST). The water samples examined in this study had MTTBE concentrations ranging from 6 to 19 microg L(-1). Aqueous extracts of a soil sample taken from the LUST site had 8 microg L(-1) MTBE.

  9. [Biodegradation of methyl tert-butyl ether by stabilized immobilized Methylibium petroleiphilum PM1 cells and its biodegradation kinetics analysis].

    Science.gov (United States)

    Cheng, Zhuo-wei; Fu, Ling-xiao; Jiang, Yi-feng; Chen, Jian-meng; Zhang, Rong

    2011-05-01

    Methylibium petroleiphilum PM1, which is capable of degrading methyl tert-butyl ether (MTBE) , was immobilized in calcium alginate gel beads. Several methods were explored to increase the strength of these gel beads. The central composite design analysis indicated that the introduction of 0.2 mol x L(-1) Ca2+ into the crosslinking solution, 1.38 mmol x L(-1) Ca2+ into the growth medium and 0.1% polyethyleneimine (PEI) as the chemical crosslinking agent could increase the stability of the Ca-alginate gel beads with no loss of biodegradation activity. The stabilized immobilized cells could be used 400 h continuously with no breakage and no bioactivity loss. Examination of scanning electron microscope demonstrated that a membrane surrounding the gel beads was formed and the cells could grow and breed well in the stabilized calcium alginate gel beads. Kinetic analysis of the gel bead-degradation indicated that the rate-limiting step was biochemical process instead of intraparticle diffusion process. The diameter of 3 mm affected the biodegradability less while high concentration of PEI induced much more serious mass transfer restraint.

  10. Effect of Ethanol and Methyl-tert-Butyl Ether on Monoaromatic Hydrocarbon Biodegradation: Response Variability for Different Aquifer Materials Under Various Electron-Accepting Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Aguilar, G L; Fernandez-Sanchez, J M; Kane, S R; Kim, D; Alvarez, P J

    2003-10-06

    Aquifer microcosms were used to determine how ethanol and methyl-tert-butyl ether (MtBE) affect monoaromatic hydrocarbon degradation under different electron-accepting conditions commonly found in contaminated sites experiencing natural attenuation. Response variability was investigated by using aquifer material from four sites with different exposure history. The lag phase prior to BTEX (benzene, toluene, ethylbenzene, and xylenes) and ethanol degradation was typically shorter in microcosms with previously contaminated aquifer material, although previous exposure did not always result in high degradation activity. Toluene was degraded in all aquifer materials and generally under a broader range of electron-accepting conditions compared to benzene, which was degraded only under aerobic conditions. MtBE was not degraded within 100 days under any condition, and it did not affect BTEX or ethanol degradation patterns. Ethanol was often degraded before BTEX compounds, and had a variable effect on BTEX degradation as a function of electron-accepting conditions and aquifer material source. An occasional enhancement of toluene degradation by ethanol occurred in denitrifying microcosms with unlimited nitrate; this may be attributable to the fortuitous growth of toluene-degrading bacteria during ethanol degradation. Nevertheless, experiments with flow-through aquifer columns showed that this beneficial effect could be eclipsed by an ethanol-driven depletion of electron acceptors, which significantly inhibited BTEX degradation and is probably the most important mechanism by which ethanol could hinder BTEX natural attenuation. A decrease in natural attenuation could increase the likelihood that BTEX compounds reach a receptor as well as the potential duration of exposure.

  11. Methyl tert-butyl ether (MTBE)-induced cytotoxicity and oxidative stress in isolated rat spermatogenic cells.

    Science.gov (United States)

    Li, Dongmei; Yin, Daqiang; Han, Xiaodong

    2007-01-01

    Methyl tert-butyl ether (MTBE) is a class of synthetic organic chemical. In the USA, MTBE pollution is regarded as a serious environmental problem. The objective of the present study was to investigate the cytotoxic effects and oxidative stress induced by MTBE in isolated rat spermatogenic cells. In cytotoxic experiments, spermatogenic cells isolated from the testes of adult Sprague-Dawley rats by a mechanical procedure without the use of trypsin were incubated with medium alone (control), 0.5, 5, 50 mm MTBE, respectively, for 6, 12 and 18 h. MTT assay, staining with fluorescein diacetate (FDA) and propidium iodide (PI) and flow cytometric analyses were used. In oxidative stress experiments, the spermatogenic cells were incubated with medium alone (control) and with 0.5, 50 microm, 5 mm MTBE. For 1, 2, 6, 12, 18 h incubation, ROS production was tested using a 2',7'-dichlorofluorescein diacetate (DCHF-DA) probe; for 1, 3, 6, 12, 18 h incubation, cytosolic superoxide dismutase (SOD) and extracellular SOD (SOD(EX)) activity was assessed; and for 18 h incubation, lipid peroxidation was assessed. The results showed that MTBE at high doses significantly decreased the spermatogenic cell viability and increased plasma membrane damage and the ratio of necrotic cells compared with the control. Assessment of the MTBE-induced oxidative stress revealed that MTBE increased the production of reactive oxygen species (ROS) and enhanced lipid peroxidation. In addition, although SOD(EX) activity increased at a high dose level, cytosolic SOD activity decreased. These results suggest that an increase of MTBE-induced ROS production and an enhancement of membrane lipid peroxidation may play an important role in its cytotoxicity in isolated rat spermatogenic cells. Copyright 2006 John Wiley & Sons, Ltd.

  12. Manipulation of the HIF-Vegf pathway rescues methyl tert-butyl ether (MTBE)-induced vascular lesions.

    Science.gov (United States)

    Bonventre, Josephine A; Kung, Tiffany S; White, Lori A; Cooper, Keith R

    2013-12-15

    Methyl tert-butyl ether (MTBE) has been shown to be specifically anti-angiogenic in piscine and mammalian model systems at concentrations that appear non-toxic in other organ systems. The mechanism by which MTBE targets developing vascular structures is unknown. A global transcriptome analysis of zebrafish embryos developmentally exposed to 0.00625-5mM MTBE suggested that hypoxia inducible factor (HIF)-regulated pathways were affected. HIF-driven angiogenesis via vascular endothelial growth factor (vegf) is essential to the developing vasculature of an embryo. Three rescue studies were designed to rescue MTBE-induced vascular lesions: pooled blood in the common cardinal vein (CCV), cranial hemorrhages (CH), and abnormal intersegmental vessels (ISV), and test the hypothesis that MTBE toxicity was HIF-Vegf dependent. First, zebrafish vegf-a over-expression via plasmid injection, resulted in significantly fewer CH and ISV lesions, 46 and 35% respectively, in embryos exposed to 10mM MTBE. Then HIF degradation was inhibited in two ways. Chemical rescue by N-oxaloylglycine significantly reduced CCV and CH lesions by 30 and 32% in 10mM exposed embryos, and ISV lesions were reduced 24% in 5mM exposed zebrafish. Finally, a morpholino designed to knock-down ubiquitin associated von Hippel-Lindau protein, significantly reduced CCV lesions by 35% in 10mM exposed embryos. In addition, expression of some angiogenesis related genes altered by MTBE exposure were rescued. These studies demonstrated that MTBE vascular toxicity is mediated by a down regulation of HIF-Vegf driven angiogenesis. The selective toxicity of MTBE toward developing vasculature makes it a potentially useful chemical in the designing of new drugs or in elucidating roles for specific angiogenic proteins in future studies of vascular development. © 2013.

  13. Trends in Methyl tert-Butyl Ether Concentrations in Private Wells in Southeast New Hampshire: 2005 to 2015.

    Science.gov (United States)

    Flanagan, Sarah M; Levitt, Joseph P; Ayotte, Joseph D

    2017-02-07

    In southeast New Hampshire, where reformulated gasoline was used from the 1990s to 2007, methyl tert-butyl ether (MtBE) concentrations ≥0.2 μg/L were found in water from 26.7% of 195 domestic wells sampled in 2005. Ten years later in 2015, and eight years after MtBE was banned, 10.3% continue to have MtBE. Most wells (140 of 195) had no MtBE detections (concentrations MtBE concentrations increased in 4 wells, decreased in 47 wells, and did not change in 4 wells. On average, MtBE concentrations decreased 65% among 47 wells whereas MtBE concentrations increased 17% among 4 wells between 2005 and 2015. The percent change in detection frequency from 2005 to 2015 (the decontamination rate) was lowest (45.5%) in high-population-density areas and in wells completed in the Berwick Formation geologic units. The decontamination rate was the highest (78.6%) where population densities were low and wells were completed in bedrock composed of granite, metamorphic, and mafic rocks. Wells in the Berwick Formation are characteristically deeper and have lower yields than wells in other rock types and have shallower overburden cover, which may allow for more rapid transport of MtBE from land-surface releases. Low-yielding, deep bedrock wells may require large contributing areas to achieve adequate well yield, and thus have a greater chance of intercepting MtBE, in addition to diluting contaminants at a slower rate and thus requiring more time to decontaminate.

  14. An extractive membrane biofilm reactor as alternative technology for the treatment of methyl tert-butyl ether contaminated water.

    Science.gov (United States)

    Guisado, I M; Purswani, J; González-López, J; Pozo, C

    2016-09-01

    Among the strategies developed for contaminated groundwater bioremediation, those based on the use of bacteria adhering to inert supports and establishing biofilms have gained great importance in this field. Extractive membrane biofilm reactor (EMBFR) technology offers productive solutions for the removal of volatile and semi-volatile compounds. EMBFR technology is based on the use of extractive semipermeable membranes through which contaminants migrate to the biological compartment in which microorganisms with pollutant biotransformation and/or mineralization capacities can grow, forming an active biofilm on the membrane surface. The objective of this study was to assess the use of three bacterial strains (Paenibacillus sp. SH7 CECT 8558, Agrobacterium sp. MS2 CECT 8557, and Rhodococcus ruber EE6 CECT 8612), as inoculum in a lab-scale EMBFR running for 28 days under aerobic conditions to eliminate methyl tert-butyl ether (MTBE) from water samples. Three different hydraulic retention times (1, 6, and 12 h) were employed. MTBE degradation values were determined daily by a gas GC-MS technique, as well as suspended bacterial growth. The biofilm established by the bacterial strains on the semipermeable membrane was detected by Field-Emission Scanning Electron Microscopy (FESEM) at the end of each experiment. The acute toxicity of the treated effluents and biomedium was determined by Microtox(©) assay (EC50 ).The results achieved from the MTBE degradation, biofilm formation, and toxicity analysis indicated that bacterial strains MS2 and EE6 were the best options as selective inoculum, although further research is needed, particularly with regard to their possible use as a mixed culture. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1238-1245, 2016. © 2016 American Institute of Chemical Engineers.

  15. The interactions of methyl tert-butyl ether on high silica zeolites: a combined experimental and computational study.

    Science.gov (United States)

    Sacchetto, V; Gatti, G; Paul, G; Braschi, I; Berlier, G; Cossi, M; Marchese, L; Bagatin, R; Bisio, C

    2013-08-28

    In this work, the interactions of methyl tert-butyl ether (MTBE) on different dealuminated high silica zeolites were studied by means of both experimental and computational approaches. Zeolites with different textural and surface features were selected as adsorbents and the effect of their physico-chemical properties (i.e. pore size architecture and type and amount of surface OH sites) on sorption capacity were studied. High silica mordenite (MOR) and Y zeolites (both with a SiO2/Al2O3 ratio of 200) and ZSM-5 solid (SiO2/Al2O3 ratio of 500) were selected as model sorbents. By combining FTIR and SS-NMR (both (1)H and (13)C CPMAS NMR) spectroscopy it was possible to follow accurately the MTBE adsorption process on highly defective MOR characterized by a high concentration of surface SiOH groups. The adsorption process is found to occur in different steps and to involve isolated silanol sites, weakly interacting silanols, and the siloxane network of the zeolite, respectively. H-bonding and van der Waals interactions occurring between the mordenite surface and MTBE molecules were modeled by DFT calculations using a large cluster of the MOR structure where two adjacent side-pockets were fused in a large micropore to simulate a dealumination process leading to silanol groups. This is the locus where MTBE molecules are more strongly bound and stabilized. FTIR spectroscopy and gravimetric measurements allowed determination of the interaction strength and sorption capacities of all three zeolites. In the case of both Y and MOR zeolites, medium-weak H-bonding with isolated silanols (both on internal and external zeolite surfaces) and van der Waals interactions are responsible for MTBE adsorption, whereas ZSM-5, in which a negligible amount of surface silanol species is present, displays a much lower amount of adsorbed MTBE retained mainly through van der Waals interactions with zeolite siloxane network.

  16. Oxidation of methyl tert-butyl ether by alkane hydroxylase in dicyclopropylketone-induced and n-octane-grown Pseudomonas putida GPo1.

    Science.gov (United States)

    Smith, Christy A; Hyman, Michael R

    2004-08-01

    The alkane hydroxylase enzyme system in Pseudomonas putida GPo1 has previously been reported to be unreactive toward the gasoline oxygenate methyl tert-butyl ether (MTBE). We have reexamined this finding by using cells of strain GPo1 grown in rich medium containing dicyclopropylketone (DCPK), a potent gratuitous inducer of alkane hydroxylase activity. Cells grown with DCPK oxidized MTBE and generated stoichiometric quantities of tert-butyl alcohol (TBA). Cells grown in the presence of DCPK also oxidized tert-amyl methyl ether but did not appear to oxidize either TBA, ethyl tert-butyl ether, or tert-amyl alcohol. Evidence linking MTBE oxidation to alkane hydroxylase activity was obtained through several approaches. First, no TBA production from MTBE was observed with cells of strain GPo1 grown on rich medium without DCPK. Second, no TBA production from MTBE was observed in DCPK-treated cells of P. putida GPo12, a strain that lacks the alkane-hydroxylase-encoding OCT plasmid. Third, all n-alkanes that support the growth of strain GPo1 inhibited MTBE oxidation by DCPK-treated cells. Fourth, two non-growth-supporting n-alkanes (propane and n-butane) inhibited MTBE oxidation in a saturable, concentration-dependent process. Fifth, 1,7-octadiyne, a putative mechanism-based inactivator of alkane hydroxylase, fully inhibited TBA production from MTBE. Sixth, MTBE-oxidizing activity was also observed in n-octane-grown cells. Kinetic studies with strain GPo1 grown on n-octane or rich medium with DCPK suggest that MTBE-oxidizing activity may have previously gone undetected in n-octane-grown cells because of the unusually high K(s) value (20 to 40 mM) for MTBE.

  17. Excess enthalpy, density, and speed of sound determination for the ternary mixture (methyl tert-butyl ether + 1-butanol + n-hexane)

    Energy Technology Data Exchange (ETDEWEB)

    Mascato, Eva [Departamento de Fisica Aplicada, Facultade de Ciencias, Universidade de Vigo, E-36310 Vigo (Spain); Mariano, Alejandra [Laboratorio de Fisicoquimica, Departamento de Quimica, Facultad de Ingenieria, Universidad Nacional del Comahue, 8300 Neuquen (Argentina); Pineiro, Manuel M. [Departamento de Fisica Aplicada, Facultade de Ciencias, Universidade de Vigo, E-36310 Vigo (Spain)], E-mail: mmpineiro@uvigo.es; Legido, Jose Luis [Departamento de Fisica Aplicada, Facultade de Ciencias, Universidade de Vigo, E-36310 Vigo (Spain); Paz Andrade, M.I. [Departamento de Fisica Aplicada, Facultade de Fisica, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela (Spain)

    2007-09-15

    Density, ({rho}), and speed of sound, (u), from T = 288.15 to T = 308.15 K, and excess molar enthalpies, (h{sup E}) at T = 298.15 K, have been measured over the entire composition range for (methyl tert-butyl ether + 1-butanol + n-hexane). In addition, excess molar volumes, V{sup E}, and excess isentropic compressibility, {kappa}{sub s}{sup E}, were calculated from experimental data. Finally, experimental excess enthalpies results are compared with the estimations obtained by applying the group-contribution models of UNIFAC (in the versions of Dang and Tassios, Larsen et al., Gmehling et al.), and DISQUAC.

  18. Manipulation of the HIF–Vegf pathway rescues methyl tert-butyl ether (MTBE)-induced vascular lesions

    Energy Technology Data Exchange (ETDEWEB)

    Bonventre, Josephine A., E-mail: josephine.bonventre@oregonstate.edu [Rutgers, The State University of New Jersey, Joint Graduate Program in Toxicology, 170 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Rutgers, The State University of New Jersey, Department of Biochemistry and Microbiology, 76 Lipman Dr., New Brunswick, NJ 08901 (United States); Oregon State University, Department of Environmental and Molecular Toxicology, 1011 Agricultural and Life Sciences Bldg, Corvallis, OR 97331 (United States); Kung, Tiffany S., E-mail: tiffany.kung@rutgers.edu [Rutgers, The State University of New Jersey, Joint Graduate Program in Toxicology, 170 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Rutgers, The State University of New Jersey, Department of Biochemistry and Microbiology, 76 Lipman Dr., New Brunswick, NJ 08901 (United States); White, Lori A., E-mail: lawhite@aesop.rutgers.edu [Rutgers, The State University of New Jersey, Joint Graduate Program in Toxicology, 170 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Rutgers, The State University of New Jersey, Department of Biochemistry and Microbiology, 76 Lipman Dr., New Brunswick, NJ 08901 (United States); Cooper, Keith R., E-mail: cooper@aesop.rutgers.edu [Rutgers, The State University of New Jersey, Joint Graduate Program in Toxicology, 170 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Rutgers, The State University of New Jersey, Department of Biochemistry and Microbiology, 76 Lipman Dr., New Brunswick, NJ 08901 (United States)

    2013-12-15

    Methyl tert-butyl ether (MTBE) has been shown to be specifically anti-angiogenic in piscine and mammalian model systems at concentrations that appear non-toxic in other organ systems. The mechanism by which MTBE targets developing vascular structures is unknown. A global transcriptome analysis of zebrafish embryos developmentally exposed to 0.00625–5 mM MTBE suggested that hypoxia inducible factor (HIF)-regulated pathways were affected. HIF-driven angiogenesis via vascular endothelial growth factor (vegf) is essential to the developing vasculature of an embryo. Three rescue studies were designed to rescue MTBE-induced vascular lesions: pooled blood in the common cardinal vein (CCV), cranial hemorrhages (CH), and abnormal intersegmental vessels (ISV), and test the hypothesis that MTBE toxicity was HIF–Vegf dependent. First, zebrafish vegf-a over-expression via plasmid injection, resulted in significantly fewer CH and ISV lesions, 46 and 35% respectively, in embryos exposed to 10 mM MTBE. Then HIF degradation was inhibited in two ways. Chemical rescue by N-oxaloylglycine significantly reduced CCV and CH lesions by 30 and 32% in 10 mM exposed embryos, and ISV lesions were reduced 24% in 5 mM exposed zebrafish. Finally, a morpholino designed to knock-down ubiquitin associated von Hippel–Lindau protein, significantly reduced CCV lesions by 35% in 10 mM exposed embryos. In addition, expression of some angiogenesis related genes altered by MTBE exposure were rescued. These studies demonstrated that MTBE vascular toxicity is mediated by a down regulation of HIF–Vegf driven angiogenesis. The selective toxicity of MTBE toward developing vasculature makes it a potentially useful chemical in the designing of new drugs or in elucidating roles for specific angiogenic proteins in future studies of vascular development. - Highlights: • Global gene expression of MTBE exposed zebrafish suggested altered HIF1 signaling. • Over expression of zebrafish vegf-a rescues MTBE

  19. Methyl tert-butyl ether (MTBE) and other volatile organic compounds in lakes in Byram Township, Sussex County, New Jersey, summer 1998

    Science.gov (United States)

    Baehr, Arthur L.; Zapecza, Otto S.

    1998-01-01

     Water samples were collected from four lakes in Byram Township, Sussex County, N.J., in the summer of 1998 as part of an investigation of the occurrence of volatile organic compounds (VOCs) in domestic wells of lakeside communities. Cranberry Lake and Lake Lackawanna are surrounded by densely populated communities where the use of gasoline-powered watercraft is prevalent, and water is supplied by lakeside wells. Forest Lake is surrounded by a densely populated community where the use of gasoline-powered watercraft is prohibited. Stag Pond is privately owned, is situated in a sparsely populated area, and is not navigated by gasoline-powered watercraft. Samples were collected from Cranberry Lake in early summer and again in late summer 1998. Concentrations of the gasoline oxygenate methyl tert-butyl ether (MTBE) ranged from 1.6 to 15.0 µg/L (micrograms per liter) on June 24 and decreased with depth. The depth-related concentration gradient is attributed to density stratification caused by the temperature gradient that is present in the lake during the early summer. MTBE concentrations ranged from 7.4 to 29.0 µg/L on September 8 and were uniform with depth, as was water temperature, indicating that the lake was vertically mixed. On the basis of these concentration profiles, the mass of MTBE in Cranberry Lake was estimated to be 15 kilograms on June 24 and 27 kilograms on September 8. These mass estimates are equal to the amount of MTBE in 52 and 95 gallons, respectively, of gasoline that contains 10 percent MTBE by volume. Concentrations of another gasoline oxygenate, tert-amyl-methyl ether (TAME), ranged from 0.07 to 0.43 µg/L on June 24 and from 0.2 to 0.69 µg/L on September 8. The highest concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) were 0.18, 1.2, 0.18, and 0.97 µg/L, respectively, on June 24. All BTEX concentrations in Cranberry Lake on September 8 were less than 0.2 µg/L.

  20. Occurrence of methyl tert-butyl ether (MTBE) in riverbank fiftered water and drnking water produced by riverbank filtration. 2.

    Science.gov (United States)

    Achten, Christine; Kolb, Axel; Püttmann, Wilhelm

    2002-09-01

    Bank filtration of river or lake water represents an efficient and natural purification process used for the drinking water production in many countries and at an amount of about 15-16% in Germany. From experiences over decades particularly at the river Rhine and Elbe, it is known that the occurrence of persistent pollutants in river water can represent a problem for the quality of drinking water produced by bank filtration. The common detection of the gasoline additive methyl tert-butyl ether (MTBE) in drinking water and the announced phase-out of the oxygenate in the U.S. show that MTBE can contaminate large water amounts due to its physicochemical properties. The MTBE situation in the U.S differs from Europe, and significantly lower concentrations in the German environment can be expected. Average MTBE concentrations of 200-250 ng/L in the Lower Main and Lower Rhine river in 2000/2001 were reported. At two sites at the Lower Rhine and Lower Main rivers MTBE concentrations in bank filtered water (n = 22), recovering well water, raw water, and drinking water produced by the water utility at the Lower Rhine site (n = 30) and tap water at Frankfurt/M City (n = 13) were analyzed from 1999 to 2001. Sample analysis is performed by a combination of headspace-solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC/MS) with a detection limit of 10 ng/L and a relative standard deviation of 11%. At the Lower Rhine site up to 80 m from the river an average MTBE concentration of 88 ng/L in riverbank filtered water, recovering well water, and raw water (n = 7) and of 43-110 ng/L in drinking water (n = 3) result. At the Lower Main site up to 400 m from the river MTBE concentrations from 52 to 250 ng/L (n = 7) were measured. Tap water samples at Frankfurt/M (mean of 35 ng/L, maximum of 71 ng/L) were in the same range as MTBE amounts in drinking water at the Lower Rhine site. Measured MTBE amounts eliminated by bank filtration at the Lower Rhine site

  1. The effect of loading palladium on zinc oxide on the photocatalytic degradation of methyl tert-butyl ether (MTBE) in water.

    Science.gov (United States)

    Seddigi, Zaki S; Ahmed, Saleh A; Ansari, Shahid P; Yarkandi, Naeema H; Danish, Ekram; Alkibash, Abdullah Abu; Oteef, Mohammed D Y; Ahmed, Shakeel

    2014-01-01

    A series of heterogeneous catalysts was prepared by doping zinc oxide with different palladium loadings in the range of 0.5%-1.5%. The prepared catalysts were characterized by SEM, TEM and XRD. These catalysts were applied to study the degradation of Methyl tert-Butyl Ether (MTBE). An amount of 100 mg of each of these catalysts was added to an aqueous solution of 100 ppm of MTBE. The resulting mixtures were irradiated with UV light for a period of 5 h. A 99.7% removal of MTBE was achieved in the case of the zinc oxide photocatalyst particles doped with 1% Pd. The photoreaction was found to be a first-order one. © 2014 The American Society of Photobiology.

  2. The application of silicalite-1/fly ash cenosphere (S/FAC) zeolite composite for the adsorption of methyl tert-butyl ether (MTBE).

    Science.gov (United States)

    Lu, Jia; Xu, Fang; Wang, Deju; Huang, Jue; Cai, Weimin

    2009-06-15

    Silicalite-1/fly ash cenosphere (S/FAC) zeolite composite has been applied for batch adsorption of methyl tert-butyl ether (MTBE) from water systems. Here the key experimental conditions, including the ratio of initial MTBE concentration to the amount weight of S/FAC, adsorption time and temperature, have been discussed in detail. The results show that approximately 93-95% MTBE could be adsorbed with initial concentration of MTBE solution 1000 microg l(-1). The column flow-through experiments also prove the high capacity of S/FAC composite for MTBE removal. The distinct advantages of S/FAC zeolite composite as adsorbent lie in (1) enhanced adsorption rate and capacity based on hierarchical micro and meso/macroporosity of S/FAC; (2) more easily operation and recycling process by assembly of nano-sized silicalite-1 zeolite on FAC support.

  3. Kinetic Analysis of the Gas-Phase Reactions of Methyl Tert-Butyl Ether with the OH Radical in the Presence of NOx

    Directory of Open Access Journals (Sweden)

    Pimentel André Silva

    1998-01-01

    Full Text Available An explicit chemical mechanism for the reaction of methyl tert-butyl ether (MTBE with OH radicals in NOx-air systems, was simulated by solving the corresponding ordinary differential equations using Runge-Kutta-4-semi-implicit method. The simulated results are consistent with the published experimental data and the model accounts for all the major pathways by which MTBE reacts in NOx-air systems. An eigenvalue-eigenvector analysis is used to extract meaningful kinetic information from linear sensitivity coefficients computed for all species of the chemical mechanism at several time points. This method is used to get an objective condition for constructing a minimal reaction set. Also, a classic method called rate of production analysis (ROPA was used for the study of the reactions relevance. Using the principal component information as well as the rate of production analysis the main paths of reaction are identified and discussed.

  4. Pulse radiolysis study of reactions of alkyl and alkylperoxy radicals originating from methyl tert-butyl ether in the gas phase

    DEFF Research Database (Denmark)

    Langer, S.; Ljungström, E.; Ellermann, T.

    1995-01-01

    UV spectra and kinetics for the reactions of alkyl and alkylperoxy radicals from methyl tert-butyl ether (MTBE) were studied in 1 atm of SF6 by the pulse radiolysis-UV absorption technique. UV spectra for the radical mixtures were quantified from 215 to 340 nm. At 240 nm, sigma(R) = (2.6 +/- 0.4) X...... 10(-18) cm(2) molecule(-1) and sigma(RO2) = (4.1 +/- 0.6) X 10(-18) cm(2) molecule(-1) (base e). The rate constant for the self-reaction of the alkyl radicals is (2.5 +/- 1.1) X 10(-11) cm(3) molecule(-1) s(-1). The rate constants for reaction of the alkyl radicals with molecular oxygen...

  5. Viscosities of binary mixtures of some n-ethoxyethanols with ethyl tert-butyl ether at T = (293.15, 298.15, and 303.15) K

    Energy Technology Data Exchange (ETDEWEB)

    Cwiklinska, Aneta [Department of Chemistry, University of Lodz, 90-236 Lodz, Pomorska 163 (Poland); Dzikowski, Tomasz [Department of Physics, University of Lodz, 90-236 Lodz, Pomorska 148/153 (Poland); Szychowski, Dariusz [Warsaw University of Technology, Faculty of Civil Engineering, Mechanics and Petrochemistry, Institute of Chemistry in Plock, 09-400 Plock, Lukasiewicza 17 (Poland); Kinart, Wojciech J. [Department of Organic Chemistry, University of Lodz, 90-136 Lodz, Narutowicza 68 (Poland); Kinart, Cezary M. [Department of Chemistry, University of Lodz, 90-236 Lodz, Pomorska 163 (Poland)], E-mail: ckinart@uni.lodz.pl

    2007-09-15

    Viscosities at T = (293.15, 298.15, and 303.15) K in the binary mixtures of ethyl tert-butyl ether with 2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, and 2-[2-(2-ethoxyethoxy)ethoxy]ethanol have been measured over the entire range of mixture compositions. From the experimental data, deviations in the viscosity ({delta}ln {eta}) and excess energies of activation for viscous flow ({delta}G{sup *E}) have been calculated. The viscosity data were correlated with equations of Hind et al., Grunberg and Nissan, Auslaender, and McAllister. The results for {delta}ln {eta} and {delta}G{sup *E} are discussed in terms of intermolecular interactions and structure of studied binary mixtures.

  6. Temperature-Induced Desorption of Methyl tert-Butyl Ether Confined on ZSM-5: An In Situ Synchrotron XRD Powder Diffraction Study

    Directory of Open Access Journals (Sweden)

    Elisa Rodeghero

    2017-02-01

    Full Text Available The temperature-induced desorption of methyl tert-butyl ether (MTBE from aqueous solutions onto hydrophobic ZSM-5 was studied by in situ synchrotron powder diffraction and chromatographic techniques. This kind of information is crucial for designing and optimizing the regeneration treatment of such zeolite. The evolution of the structural features monitored by full profile Rietveld refinements revealed that a monoclinic (P21/n to orthorhombic (Pnma phase transition occurred at about 100 °C. The MTBE desorption process caused a remarkable change in the unit-cell parameters. Complete MTBE desorption was achieved upon heating at about 250 °C. Rietveld analysis demonstrated that the desorption process occurred without any significant zeolite crystallinity loss, but with slight deformations in the channel apertures.

  7. National survey of Methyl tert-Butyl Ether and other Volatile Organic Compounds in drinking-water sources: Results of the random source-water survey

    Science.gov (United States)

    Grady, Stephen J.

    2002-01-01

    Methyl tert-butyl ether (MTBE) was detected in source water used by 8.7 percent of randomly selected community water systems (CWSs) in the United States at concentrations that ranged from 0.2 to 20 micrograms per liter (?g/L). The Random Survey conducted by the U.S. Geological Survey, in cooperation with the Metropolitan Water District of Southern California and the Oregon Health & Science University, was designed to provide an assessment of the frequency of detection, concentration, and distribution of MTBE, three other ether gasoline oxygenates, and 62 other volatile organic compounds (VOCs) in ground- and surface-water sources used for drinking-water supplies. The Random Survey was the first of two components of a national assessment of the quality of source water supplying CWSs sponsored by the American Water Works Association Research Foundation. A total of 954 CWSs were selected for VOC sampling from the population of nearly 47,000 active, self-supplied CWSs in all 50 States, Native American Lands, and Puerto Rico based on a statistical design that stratified on CWS size (population served), type of source water (ground and surface water), and geographic distribution (State).At a reporting level of 0.2 ?g/L, VOCs were detected in 27 percent of source-water samples collected from May 3, 1999 through October 23, 2000. Chloroform (in 13 percent of samples) was the most frequently detected of 42 VOCs present in the source-water samples, followed by MTBE. VOC concentrations were generally less than 10 ?g/L?95 percent of the 530 detections?and 63 percent were less than 1.0 ?g/L. Concentrations of 1,1-dichloroethene, tetrachloroethene, trichloroethene, vinyl chloride, and total trihalomethanes (TTHMs), however, exceeded drinking-water regulations in eight samples.Detections of most VOCs were more frequent in surface-water sources than in ground-water sources, with gasoline compounds collectively and MTBE individually detected significantly more often in surface

  8. Use of Methyl Tert-Butyl Ether for the Treatment of Refractory Intrahepatic Biliary Strictures and Bile Casts: A Modern Perspective

    Directory of Open Access Journals (Sweden)

    Gregory Kim

    2015-01-01

    Full Text Available Cholelithiasis is a prevalent problem in the United States with 14% or more adults affected. Definitive treatment of cholelithiasis is cholecystectomy. When cholecystectomy yields minimal resolution treatment options include expectant management of asymptomatic gallstones or endoscopic retrograde cholangiopancreatogram. We present a case of intrahepatic biliary casts where surgical option was not possible, interventional radiology was unsuccessful, and methyl tert-butyl ether was used to dissolve the biliary obstruction. Dissolution therapy of gallstones was first reported in 1722 when Vollisnieri used turpentine in vitro. While diethyl ether has excellent solubilizing capacity, its low boiling point limited its use surgically as it vaporizes immediately. Diethyl ether can expand 120-fold during warming to body temperature after injection into the biliary system making it impractical for routine use. The use of dissolution is out of favor due to the success of laparoscopic cholecystectomy. Epidemiological studies have shown the general population should have minimal concerns from passive exposure. Dissolution using MTBE remains a viable option if surgical or endoscopic options are not available. However, because of risks involved to both the patient and the staff, careful multidisciplinary team approach must be undertaken to minimize the risks and provide the best possible care to the patient.

  9. Toxicokinetics of methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME) in humans, and implications to their biological monitoring.

    Science.gov (United States)

    Vainiotalo, Sinikka; Riihimäki, Vesa; Pekari, Kaija; Teräväinen, Eija; Aitio, Antero

    2007-10-01

    Healthy male volunteers were exposed via inhalation to gasoline oxygenates methyl tert-butyl ether (MTBE) or tert-amyl methyl ether (TAME). The 4-hr exposures were carried out in a dynamic chamber at 25 and 75 ppm for MTBE and at 15 and 50 ppm for TAME. The overall mean pulmonary retention of MTBE was 43 +/- 2.6%; the corresponding mean for TAME was 51 +/- 3.9%. Approximately 52% of the absorbed dose of MTBE was exhaled within 44 hr following the exposure; for TAME, the corresponding figure was 30%. MTBE and TAME in blood and exhaled air reached their highest concentrations at the end of exposure, whereas the concentrations of the metabolites tert-butanol (TBA) and tert-amyl alcohol (TAA) concentrations were highest 0.5-1 hr after the exposure and then declined slowly. Two consecutive half-times were observed for the disappearance of MTBE and TAME from blood and exhaled air. The half-times for MTBE in blood were about 1.7 and 3.8 hr and those for TAME 1.2 and 4.9 hr. For TAA, a single half-time of about 6 hr best described the disappearance from blood and exhaled air; for TBA, the disappearance was slow and seemed to follow zero-order kinetics for 24 hr. In urine, maximal concentrations of MTBE and TAME were observed toward the end of exposure or slightly (MTBE and 0.1% of the dose of TAME was excreted unchanged in urine, whereas the urinary excretion of free TBA and TAA was 1.2% and 0.3% within 48 hr. The blood/air and oil/blood partition coefficients, determined in vitro, were 20 and 14 for MTBE and 20 and 37 for TAME. By intrapolation from the two experimental exposure concentrations, biomonitoring action limits corresponding to an 8-hr time-weighted average (TWA) exposure of 50 ppm was estimated to be 20 micro mol/L for post-shift urinary MTBE, 1 mu mol/L for exhaled air MTBE in a post-shift sample, and 30 micro mol/L for urinary TBA in a next-morning specimen. For TAME and TAA, concentrations corresponding to an 8-hr TWA exposure at 20 ppm were estimated to be

  10. Paenibacillus etheri sp. nov., able to growth on media supplemented with methyl tert-butyl ether (MTBE) isolated from hydrocarbon contaminated soil.

    Science.gov (United States)

    Guisado, Isabel M; Purswani, Jessica; González-López, Jesús; Pozo, Clementina

    2015-11-26

    A bacterial strain designated as strain SH7T was isolated from the hydrocarbon contaminated soil of a pilot plant (Granada, Spain). The strain was selected for its capacity to growth in media supplemented with methyl tert-butyl ether (MTBE) as sole energy and carbon source. Strain SH7T was a Gram-stain-positive, facultatively anaerobic, spore-forming, rod-shaped bacterium. Phylogenetic analysis using 16S rRNA gene sequences showed that strain SH7T belongs to a cluster comprising species of the genus Paenibacillus and was closely related to Paenibacillus borealis DSM 13188T (97%) and Paenibacillus odorifer DSM 15391T (98%). DNA-DNA hybridization tests showed low relatedness of the strain SH7T with Paenibacillus borealis (16.9±1.5%) and Paenibacillus odorifer (16.6±2.1%) respectively. The cell wall contained meso-diaminopimelic acid. The predominant respiratory quinone was MK-7, anteiso-C15:0 (32.9%) and C16:0 (29.0%) were the predominant cellular fatty acids. Phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol and three unknown aminophospholipids were the major phospholipids. The DNA G+C content was 44.3 mol%. The data obtained in this study indicate that the SH7Tstrain represents a novel species of the genus Paenibacillus, for which the name Paenibacillus etheri sp. nov. is proposed. The type strain is SH7T (= CECT 8558T =DSM 29760T).

  11. Mechanistic considerations for the degradation of methyl tert-butyl ether (MTBE) by sonolysis: effect of argon vs. oxygen saturated solutions.

    Science.gov (United States)

    Kim, Duk Kyung; O'Shea, Kevin E; Cooper, William J

    2012-07-01

    The ultrasonic degradation mechanism of methyl tert-butyl ether (MTBE) in aqueous solution is complex because of the competition between hydroxyl radical attack, pyrolysis, and hydrolysis reactions. A detailed investigation of degradation pathways using sonolysis has been performed using reaction byproducts identification. The observed bi-product distributions are rationalized in terms of hydroxyl radical (()OH) mediated processes and pyrolysis. The role of oxygen mediated and pyrolytic pathways were assessed using O(2) and Ar saturated solutions. Chemical destruction by sonolysis is often rationalized using hydroxyl radical chemistry. Pyrolysis is unique to this advanced oxidation process, and is important in the case of MTBE because it transfers into the cavitating bubbles. While α-hydrogen abstraction by ()OH and low temperature pyrolysis was important, it was also shown that β-hydrogen abstraction leads, in some cases, to the same reaction byproducts, which emphasized the importance of α-hydrogen abstraction. High temperature pyrolysis resulted in minor degradation reactions based on the formation of reaction by-products. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Pyrolysis of methyl tert-butyl ether (MTBE). 1. Experimental study with molecular-beam mass spectrometry and tunable synchrotron VUV photoionization.

    Science.gov (United States)

    Zhang, Taichang; Wang, Jing; Yuan, Tao; Hong, Xin; Zhang, Lidong; Qi, Fei

    2008-10-23

    An experimental study of methyl tert-butyl ether (MTBE) pyrolysis (3.72% MTBE in argon) has been performed at low pressure (267 Pa) within the temperature range from 700 to 1420 K. The pyrolysis process was detected with the tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry (MBMS). About thirty intermediates are identified from near-threshold measurements of photoionization mass spectrum and photoionization efficiency spectrum. Among them, H2, CO, CH4, CH3OH and C4H8 are the major pyrolysis products. The radicals such as methyl, methoxy, propargyl, allyl, C4H5 and C4H7 are detected. The isomers of pyrolysis products are identified as well, i.e., propyne and allene, 1,2,3-butatriene and vinylacetylene, isobutene and 1-butene, propanal and acetone. Furthermore, the mole fractions of the pyrolysis products have been evaluated under various temperatures. Meanwhile, the initial formation temperatures of different pyrolysis products can be obtained. This work is anticipated to present a new experimental method for pyrolysis study and help understand the pyrolysis and combustion chemistry of MTBE and other oxygenated fuels.

  13. Naturally occurring bacteria similar to the methyl tert-butyl ether (MTBE)-degrading strain PM1 are present in MTBE-contaminated groundwater.

    Science.gov (United States)

    Hristova, Krassimira; Gebreyesus, Binyam; Mackay, Douglas; Scow, Kate M

    2003-05-01

    Methyl tert-butyl ether (MTBE) is a widespread groundwater contaminant that does not respond well to conventional treatment technologies. Growing evidence indicates that microbial communities indigenous to groundwater can degrade MTBE under aerobic and anaerobic conditions. Although pure cultures of microorganisms able to degrade or cometabolize MTBE have been reported, to date the specific organisms responsible for MTBE degradation in various field studies have not be identified. We report that DNA sequences almost identical (99% homology) to those of strain PM1, originally isolated from a biofilter in southern California, are naturally occurring in an MTBE-polluted aquifer in Vandenberg Air Force Base (VAFB), Lompoc, California. Cell densities of native PM1 (measured by TaqMan quantitative PCR) in VAFB groundwater samples ranged from below the detection limit (in anaerobic sites) to 10(3) to 10(4) cells/ml (in oxygen-amended sites). In groundwater from anaerobic or aerobic sites incubated in microcosms spiked with 10 microg of MTBE/liter, densities of native PM1 increased to approximately 10(5) cells/ml. Native PM1 densities also increased during incubation of VAFB sediments during MTBE degradation. In controlled field plots amended with oxygen, artificially increasing the MTBE concentration was followed by an increase in the in situ native PM1 cell density. This is the first reported relationship between in situ MTBE biodegradation and densities of MTBE-degrading bacteria by quantitative molecular methods.

  14. Polypyrrole-Grafted Coconut Shell Biological Carbon as a Potential Adsorbent for Methyl Tert-Butyl Ether Removal: Characterization and Adsorption Capability

    Directory of Open Access Journals (Sweden)

    Shanshan Li

    2017-01-01

    Full Text Available Methyl tert-butyl ether (MTBE has been used as a common gasoline additive worldwide since the late twentieth century, and it has become the most frequently detected groundwater pollutant in many countries. This study aimed to synthesize a novel microbial carrier to improve its adsorptive capacity for MTBE and biofilm formation, compared to the traditional granular activated carbon (GAC. A polypyrrole (PPy-modified GAC composite (PPy/GAC was synthesized, and characterized by Fourier transform infrared spectroscopy (FT-IR and Brunauer-Emmett-Teller (BET surface area analysis. The adsorption behaviors of MTBE were well described by the pseudo-second-order and Langmuir isotherm models. Furthermore, three biofilm reactors were established with PPy/GAC, PPy, and GAC as the carriers, respectively, and the degradation of MTBE under continuous flow was investigated. Compared to the biofilm reactors with PPy or GAC (which both broke after a period of operation, the PPy/GAC biofilm column produced stable effluents under variable treatment conditions with a long-term effluent MTBE concentration <20 μg/L. Pseudomonas aeruginosa and Acinetobacter pittii may be the predominant bacteria responsible for MTBE degradation in these biofilm reactors.

  15. Polypyrrole-Grafted Coconut Shell Biological Carbon as a Potential Adsorbent for Methyl Tert-Butyl Ether Removal: Characterization and Adsorption Capability.

    Science.gov (United States)

    Li, Shanshan; Qian, Keke; Wang, Shan; Liang, Kaiqiang; Yan, Wei

    2017-01-24

    Methyl tert-butyl ether (MTBE) has been used as a common gasoline additive worldwide since the late twentieth century, and it has become the most frequently detected groundwater pollutant in many countries. This study aimed to synthesize a novel microbial carrier to improve its adsorptive capacity for MTBE and biofilm formation, compared to the traditional granular activated carbon (GAC). A polypyrrole (PPy)-modified GAC composite (PPy/GAC) was synthesized, and characterized by Fourier transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) surface area analysis. The adsorption behaviors of MTBE were well described by the pseudo-second-order and Langmuir isotherm models. Furthermore, three biofilm reactors were established with PPy/GAC, PPy, and GAC as the carriers, respectively, and the degradation of MTBE under continuous flow was investigated. Compared to the biofilm reactors with PPy or GAC (which both broke after a period of operation), the PPy/GAC biofilm column produced stable effluents under variable treatment conditions with a long-term effluent MTBE concentration MTBE degradation in these biofilm reactors.

  16. Cytotoxic and DNA-damaging effects of methyl tert-butyl ether and its metabolites on HL-60 cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Tang, G.H. [Xian Medical Univ. (China); Shen, Y.; Shen, H.M. [National Univ. of Singapore (Singapore)] [and others

    1996-12-31

    Methyl tert-butyl ether (MTBE) is a widely used oxygenate in unleaded gasoline; however, few studies have been conducted on the toxicity of this compound. This study evaluates the cytotoxic and DNA-damaging effects of MTBE and its metabolites in a human haemopoietic cell line, HL-60. The metabolites of MTBE studied include tertiary butyl alcohol (TBA), {alpha}-hydroxyisobutyric acid (HIBA), and formaldehyde. Comet assay is used to assess DNA damage, and the cytotoxicity is investigated by lactate dehydrogenease (LDH) release. The results show no significant cytotoxic effects of MTBE, TBA, and HIBA over a concentration ranging from 1 to 30 mM. Formaldehyde, in contrast, causes a substantial LDH release at a concentration of 5 {mu}M. Hydrogen peroxide, a known oxidative agent, at concentrations ranging from 10 to 100 {mu}M, produces a significant dose-related increase in DNA damage, whereas a much higher concentration of MTBE (1 to 30 mM) is required to produce a similar observation. The genotoxic effects of TBA and HIBA appear to be identical to that of MTBE. Conversely, DNA damage is observed for formaldehyde at a relatively low concentration range (5 to 100 {mu}M). These findings suggest that MTBE and its metabolites, except formaldehyde, have relatively low cytotoxic and genotoxic effects. 16 refs., 4 figs.

  17. Response surface analysis of photocatalytic degradation of methyl tert-butyl ether by core/shell Fe3O4/ZnO nanoparticles.

    Science.gov (United States)

    Safari, Mojtaba; Rostami, Mohammad Hossein; Alizadeh, Mehriana; Alizadehbirjandi, Atefeh; Nakhli, Seyyed Ali Akbar; Aminzadeh, Reza

    2014-01-06

    The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface modeling (RSM). Using the four-factor-three-level Box-Behnken design, 29 runs were designed considering the effective ranges of the influential factors. The optimized values for the operational parameters under the respective constraints were obtained at PH of 7.2, Fe3O4/ZnO concentration of 1.78 g/L, initial MTBE concentration of 89.14 mg/L and [H2O2]/ [MTBE] molar ratio of 2.33. Moreover, kinetics of MTBE degradation was determined under optimum condition. The study about core/shell magnetic nanoparticles (MNPs) recycling were also carried out and after about four times, the percentage of the photocatalytic degradation was about 70%.

  18. The study of binding of methyl tert-butyl ether to human telomeric G-quadruplex and calf thymus DNA by gas chromatography, a thermodynamic discussion.

    Science.gov (United States)

    Ghasemi, Sahar; Ahmadi, Farhad

    2014-11-15

    Methyl-tert-butyl ether (MTBE) is widely used as an antiknock additive for increasing octane number of gasoline. Recently, the in vivo studies demonstrated that MTBE has genotoxic potential and able to form adducts with DNA. In the work, the interactions of MTBE with calf thymus DNA (ct-DNA) and the Na(+) form of G-quadruplex DNA (wtTel22) were studied by using of head space-solid phase microextraction technique coupled to gas chromatography. The binding equilibrium constants were measured through the equilibriums of a four phase system. In addition, the MTBE Henry's law constants for two different buffers in the temperature range of 283-303K were measured. Thermodynamic studies revealed that the complexation of MTBE to both DNAs is enthalpy favored and entropy disfavored. The thermodynamic results revealed that MTBE may have interaction with ct-DNA via the minor groove of DNA. Also, MTBE may be complexed into the basket of G-quadruplex structure. In addition, the low difference in the binding constants of MTBE for both different DNA targets may confirm that MTBE is poorly selective for different conformations of DNA. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Photodegradation of methyl tert-butyl ether (MTBE) by UV/H2O2 and UV/TiO2.

    Science.gov (United States)

    Hu, Qinhai; Zhang, Chunlong; Wang, Zhirong; Chen, Yan; Mao, Kehui; Zhang, Xingqing; Xiong, Yunlong; Zhu, Miaojun

    2008-06-15

    Two UV-based advanced oxidation processes (AOPs), UV/H2O2 and UV/TiO2, were tested in batch reactor systems to evaluate the removal efficiencies and optimal conditions for the photodegradation of methyl tert-butyl ether (MTBE). The optimal conditions at an initial MTBE concentration of 1 mM ([MTBE]0=1 mM) were acidic and 15 mM H2O2 in UV/H2O2 system, and pH 3.0 and 2.0 g/l TiO2 in UV/TiO2 suspended slurries system under 254-nm UV irradiation. Under the optimal conditions, MTBE photodegradation during the initial period of 60 min in UV/H2O2 and UV/TiO2 systems reached 98 and 80%, respectively. In both systems, MTBE photodegradation decreased with increasing [MTBE]0. While MTBE photodegradation rates increased with increasing dosage of H2O2 (5-15 mM) and TiO2 (0.5-3 g/l), further increase in the dosage of H2O2 (20 mM) or TiO2 (4 g/l) adversely reduced the MTBE photodegradation. Pseudo first-order kinetics with regard to [MTBE] can be used to describe the MTBE photodegradation in both systems. The pseudo first-order rate constants linearly increased with the increase in the molar ratio of [H2O2]0 to [MTBE]0 in UV/H2O2 system and linearly increased with the decrease in [MTBE]0 in UV/TiO2 system.

  20. Application of artificial neural networks for modeling of the treatment of wastewater contaminated with methyl tert-butyl ether (MTBE) by UV/H2O2 process.

    Science.gov (United States)

    Salari, D; Daneshvar, N; Aghazadeh, F; Khataee, A R

    2005-10-17

    During the last two decades, methyl tert-butyl ether (MTBE) has been widely used as an additive to gasoline (up to 15%) both to increase the octane number and as a fuel oxygenate to improve air quality by reducing the level of carbon monoxide in vehicle exhausts. The present work mainly deals with photooxidative degradation of MTBE in the presence of H2O2 under UV light illumination (30W). We studied the influence of the basic operational parameters such as initial concentration of H2O2 and irradiation time on the photodegradation of MTBE. The oxidation rate of MTBE was low when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The addition of proper amount of hydrogen peroxide improved the degradation, while the excess hydrogen peroxide could quench the formation of hydroxyl radicals (OH). The semi-log plot of MTBE concentration versus time was linear, suggesting a first order reaction. Therefore, the treatment efficiency was evaluated by figure-of-merit electrical energy per order (E(Eo)). Our results showed that MTBE could be treated easily and effectively with the UV/H2O2 process with E(Eo) value 80 kWh/m3/order. The proposed model based on artificial neural network (ANN) could predict the MTBE concentration during irradiation time in optimized conditions. A comparison between the predicted results of the designed ANN model and experimental data was also conducted.

  1. Evaluation of ethyl tert-butyl ether biodegradation in a contaminated aquifer by compound-specific isotope analysis and in situ microcosms

    Energy Technology Data Exchange (ETDEWEB)

    Bombach, Petra, E-mail: petra.bombach@ufz.de [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Isodetect GmbH Leipzig, Deutscher Platz 5b, D-04103 Leipzig (Germany); Nägele, Norbert [Kuvier the Biotech Company S.L., Ctra. N-I, p.k. 234–P.E. INBISA 23" a, E-09001 Burgos (Spain); Rosell, Mònica [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Grup de Mineralogia Aplicada i Medi Ambient, Departament de Cristallografia, Mineralogia i Dipòsits Minerals, Facultat de Geologia, Universitat de Barcelona (UB), C/Martí i Franquès s/n, 08028 Barcelona (Spain); Richnow, Hans H. [UFZ – Helmholtz Centre for Environmental Research, Department of Isotope Biogeochemistry, Permoserstrasse 15, D-04318 Leipzig (Germany); Fischer, Anko [Isodetect GmbH Leipzig, Deutscher Platz 5b, D-04103 Leipzig (Germany)

    2015-04-09

    Highlights: • In situ biodegradation of ETBE was investigated in a fuel contaminated aquifer. • Degradation was studied by CSIA and in situ microcosms in combination with TLFA-SIP. • ETBE was degraded when ETBE was the main groundwater contaminant. • ETBE was also degraded in the presence of BTEX and MTBE. • Hydrochemical analysis indicated aerobic and anaerobic ETBE biodegradation. - Abstract: Ethyl tert-butyl ether (ETBE) is an upcoming groundwater pollutant in Europe whose environmental fate has been less investigated, thus far. In the present study, we investigated the in situ biodegradation of ETBE in a fuel-contaminated aquifer using compound-specific stable isotope analysis (CSIA), and in situ microcosms in combination with total lipid fatty acid (TLFA)-stable isotope probing (SIP). In a first field investigation, CSIA revealed insignificant carbon isotope fractionation, but low hydrogen isotope fractionation of up to +14‰ along the prevailing anoxic ETBE plume suggesting biodegradation of ETBE. Ten months later, oxygen injection was conducted to enhance the biodegradation of petroleum hydrocarbons (PH) at the field site. Within the framework of this remediation measure, in situ microcosms loaded with [{sup 13}C{sub 6}]-ETBE (BACTRAP{sup ®}s) were exposed for 119 days in selected groundwater wells to assess the biodegradation of ETBE by TLFA-SIP under the following conditions: (i) ETBE as main contaminant; (ii) ETBE as main contaminant subjected to oxygen injection; (iii) ETBE plus other PH; (iv) ETBE plus other PH subjected to oxygen injection. Under all conditions investigated, significant {sup 13}C-incorporation into microbial total lipid fatty acids extracted from the in situ microcosms was found, providing clear evidence of ETBE biodegradation.

  2. Using groundwater age distributions to understand changes in methyl tert-butyl ether (MtBE) concentrations in ambient groundwater, northeastern United States

    Science.gov (United States)

    Lindsey, Bruce; Ayotte, Joseph; Jurgens, Bryant; DeSimone, Leslie

    2017-01-01

    Temporal changes in methyl tert-butyl ether (MtBE) concentrations in groundwater were evaluated in the northeastern United States, an area of the nation with widespread low-level detections of MtBE based on a national survey of wells selected to represent ambient conditions. MtBE use in the U.S. peaked in 1999 and was largely discontinued by 2007. Six well networks, each representing specific areas and well types (monitoring or supply wells), were each sampled at 10 year intervals between 1996 and 2012. Concentrations were decreasing or unchanged in most wells as of 2012, with the exception of a small number of wells where concentrations continue to increase. Statistically significant increasing concentrations were found in one network sampled for the second time shortly after the peak of MtBE use, and decreasing concentrations were found in two networks sampled for the second time about 10 years after the peak of MtBE use. Simulated concentrations from convolutions of estimates for concentrations of MtBE in recharge water with age distributions from environmental tracer data correctly predicted the direction of MtBE concentration changes in about 65 percent of individual wells. The best matches between simulated and observed concentrations were found when simulating recharge concentrations that followed the pattern of national MtBE use. Some observations were matched better when recharge was modeled as a plume moving past the well from a spill at one point in time. Modeling and sample results showed that wells with young median ages and narrow age distributions responded more quickly to changes in the contaminant source than wells with older median ages and broad age distributions. Well depth and aquifer type affect these responses. Regardless of the timing of decontamination, all of these aquifers show high susceptibility for contamination by a highly soluble, persistent constituent.

  3. Methyl tert butyl ether (MTBE) is anti- angiogenic in both in vitro and in vivo mammalian model systems

    Science.gov (United States)

    Kozlosky, John; Bonventre, Josephine; Cooper, Keith

    2015-01-01

    Methyl-tertiary butyl ether (MTBE), a well known gasoline oxygenate, and FDA approved gallstone treatment, has been previously shown to specifically target teleost embryonic angiogenesis. The studies reported here were to determine if similar vascular disrupting effects occurred in higher vertebrate models. Rat brain endothelial cells were isolated and allowed to form microcapillary-like tubes on Matrigel. MTBE (0.34–34.0 mM) exposure resulted in a dose-dependent reduction of tube formation, with the LOAEL at 0.34 mM, while MTBE’s primary metabolite, tertiary butyl alcohol had no effect on tube formation. HUVECs, a primary cell line representing macrovascular cells, were able to form tubes on Matrigel in the presence of MTBE (1.25 – 80 mM), but the tubes were narrower than those formed in the absence of MTBE. In a mouse Matrigel plug implantation assay, 34.0 mM MTBE completely inhibited vessel invasion into plugs containing Endothelial Cell Growth Supplement (ECGS) compared to control plugs with ECGS alone. When timed-pregnant Fisher 344 rats were gavaged with MTBE (500–1500 mg/kg) from day 6 of organogenesis through 10 days post parturition, no organ toxicity or histological changes in pup vasculature were observed. Therefore, MTBE is anti-angiogenic at mM concentrations and therefore a potential use as an anti-angiogenic treatment for solid tumors with minimal toxicity. PMID:22407988

  4. Methyl tert-butyl ether in ground and surface water of the United States: National-scale relations between MTBE occurrence in surface and ground water and MTBE use in gasoline

    Science.gov (United States)

    Moran, M.J.; Clawges, R.M.; Zogorski, J.S.

    2002-01-01

    The detection frequency of methyl tert-butyl ether (MTBE) in ground and surface water of the United States is positively related to the content of MTBE in gasoline in various metropolitan areas of the U.S. The frequency of detection of MTBE is generally higher in areas that use larger amounts of MTBE in gasoline. Sampling of surface and ground water by the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program between 1993 and 1998 revealed a frequent detection of low concentrations of MTBE. In this analysis, data from several national-scale gasoline surveys are examined and data from one survey that is most extensive in geographic and temporal coverage is used to relate the detection of MTBE in ground and surface water to the volumetric content of MTBE in gasoline.

  5. Ionic-liquid-mediated poly(dimethylsiloxane)- grafted carbon nanotube fiber prepared by the sol-gel technique for the head space solid-phase microextraction of methyl tert-butyl ether using GC.

    Science.gov (United States)

    Vatani, Hossein; Yazdi, Ali Sarafraz

    2014-01-01

    A headspace solid-phase microextraction method was developed for the preconcentration and extraction of methyl tert-butyl ether. An ionic-liquid-mediated multiwalled carbon nanotube-poly(dimethylsiloxane) hybrid coating, which was prepared by covalent functionalization of multiwalled carbon nanotubes with hydroxyl-terminated poly(dimethylsiloxane) using the sol-gel technique, was used as solid-phase microextraction adsorbent. This innovative fiber exhibited a highly porous surface structure, high thermal stability (at least 320°C) and long lifespan (over 210 uses). Potential factors affecting the extraction efficiency were optimized. Under the optimum conditions, the method LOD (S/N = 3) was 0.007 ng/mL and the LOQ (S/N = 10) was 0.03 ng/mL. The calibration curve was linear in the range of 0.03-200 ng/mL. The RSDs for one fiber (repeatability, n = 5) at three different concentrations (0.05, 1, and 150 ng/mL) were 5.1, 4.2, and 4.6% and for the fibers obtained from different batches (reproducibility, n = 3) were 6.5, 5.9, and 6.3%, respectively. The developed method was successfully applied to the determination of methyl tert-butyl ether in different real water samples on three consecutive days. The relative recoveries for the spiked samples with 0.05, 1, and 150 ng/mL were between 94-104%. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. 2-Benzhydryl-6-tert-butyl-4-methylphenol

    Directory of Open Access Journals (Sweden)

    Sungwoo Yoon

    2013-02-01

    Full Text Available The title compound, C24H26O, was prepared by the reaction between 2-tert-butyl-4-methylphenol and diphenylmethanol in the presence of sulfuric acid. Three benzene rings are attached directly to the central C—H group in a twisted propeller conformation with the local pseudo-C3 rotational axis coinciding with the C—H bond. There are three short C—H...O contacts in the molecule.

  7. gamma-Aminobutyric acid(A) (GABA(A)) receptor regulates ERK1/2 phosphorylation in rat hippocampus in high doses of methyl tert-butyl ether (MTBE)-induced impairment of spatial memory.

    Science.gov (United States)

    Zheng, Gang; Zhang, Wenbin; Zhang, Yun; Chen, Yaoming; Liu, Mingchao; Yao, Ting; Yang, Yanxia; Zhao, Fang; Li, Jingxia; Huang, Chuanshu; Luo, Wenjing; Chen, Jingyuan

    2009-04-15

    Experimental and occupational exposure to methyl tert-butyl ether (MTBE) has been reported to induce neurotoxicological and neurobehavioral effects, such as headache, nausea, dizziness, and disorientation, etc. However, the molecular mechanisms involved in MTBE-induced neurotoxicity are still not well understood. In the present study, we investigated the effects of MTBE on spatial memory and the expression and function of GABA(A) receptor in the hippocampus. Our results demonstrated that intraventricular injection of MTBE impaired the performance of the rats in a Morris water maze task, and significantly increased the expression of GABA(A) receptor alpha1 subunit in the hippocampus. The phosphorylation of ERK1/2 decreased after the MTBE injection. Furthermore, the decreased ability of learning and the reduction of phosphorylated ERK1/2 level of the MTBE-treated rats was partly reversed by bicuculline injected 30 min before the training. These results suggested that MTBE exposure could result in impaired spatial memory. GABA(A) receptor may play an important role in the MTBE-induced impairment of learning and memory by regulating the phosphorylation of ERK in the hippocampus.

  8. Water Quality and Occurrence of Methyl Tert-Butyl Ether (MTBE) and Other Fuel-Related Compounds in Lakes and Ground Water at Lakeside Communities in Sussex and Morris Counties, New Jersey, 1998-1999

    Science.gov (United States)

    Baehr, Arthur L.; Reilly, Timothy J.

    2001-01-01

    Densely populated communities surround many of the larger lakes in northwestern New Jersey. These communities derive most of their water supply from wells. The lakes can be navigated by gasoline-powered watercraft, can be in various stages of eutrophication, may contain pathogens associated with bathing and waterfowl, and are periodically subjected to chemical applications to control aquatic plant growth. Another feature that contributes to water-quality concerns in lakeside communities is the widespread use of septic tanks. Concentrations of methyl tert-butyl ether (MTBE), a gasoline oxygenate, in samples from Cranberry Lake and Lake Lackawanna ranged from 20 to 30 ug/L (micrograms per liter) and 5 to 14 ug/L during the summers of 1998 and 1999, respectively. These levels were persistent throughout the depth of the lakes when mixing conditions were present. MTBE concentrations in samples from the top 20 feet of Lake Hopatcong during summer 1999 were about 10 ug/L and about 2 to 3 ug/L in samples below 20 feet. The source of the MTBE in the lakes was determined to be gasoline-powered watercraft. Other constituents of gasoline--tertiary amyl methyl ether (TAME) and benzene, toluene, ethylbenzene, and xylenes (BTEX)--were detected in the lakes but at much lower concentrations than MTBE. Ambient ground-water quality at Cranberry Lake and Lake Lackawanna appears to be affected by the use of gasoline-powered watercraft. MTBE was detected in water samples from 13 of the 14 wells sampled at Cranberry Lake in fall 1998 and summer 1999. The wells were selected to monitor ambient ground-water quality and had no history of contamination. In ground-water samples collected during fall 1998, MTBE concentrations ranged from 0.12 to 19.8 ug/L, and the median concentration was 0.43 ug/L. In samples from summer 1999, MTBE concentrations ranged from 0.14 to 13.2 ug/L, and the median concentration was 0.38 ug/L. MTBE was detected in samples from four of the five wells at Lake

  9. Four coordination polymers based on 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers: Synthesis, luminescence detection of acetone and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Arıcı, Mürsel, E-mail: marici@ogu.edu.tr [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Zafer Yeşilel, Okan [Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University, 26480 Eskişehir (Turkey); Büyükgüngör, Orhan [Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayıs University, 55139 Samsun (Turkey)

    2017-05-15

    methanol could be used as a fluorescent sensor for the detection of acetone. Moreover, thermal and optical properties of the complexes were also studied. - Highlights: • Four new 2D and 3D coordination polymers with 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers. • The structural diversity depending on ligands and coordination number of metal centers. • Fluorescent sensor for the detection of acetone.

  10. Linking low-level stable isotope fractionation to expression of the cytochrome P450 monooxygenase-encoding ethB gene for elucidation of methyl tert-butyl ether biodegradation in aerated treatment pond systems.

    Science.gov (United States)

    Jechalke, Sven; Rosell, Mònica; Martínez-Lavanchy, Paula M; Pérez-Leiva, Paola; Rohwerder, Thore; Vogt, Carsten; Richnow, Hans H

    2011-02-01

    Multidimensional compound-specific stable isotope analysis (CSIA) was applied in combination with RNA-based molecular tools to characterize methyl tertiary (tert-) butyl ether (MTBE) degradation mechanisms occurring in biofilms in an aerated treatment pond used for remediation of MTBE-contaminated groundwater. The main pathway for MTBE oxidation was elucidated by linking the low-level stable isotope fractionation (mean carbon isotopic enrichment factor [ε(C)] of -0.37‰ ± 0.05‰ and no significant hydrogen isotopic enrichment factor [ε(H)]) observed in microcosm experiments to expression of the ethB gene encoding a cytochrome P450 monooxygenase able to catalyze the oxidation of MTBE in biofilm samples both from the microcosms and directly from the ponds. 16S rRNA-specific primers revealed the presence of a sequence 100% identical to that of Methylibium petroleiphilum PM1, a well-characterized MTBE degrader. However, neither expression of the mdpA genes encoding the alkane hydroxylase-like enzyme responsible for MTBE oxidation in this strain nor the related MTBE isotope fractionation pattern produced by PM1 could be detected, suggesting that this enzyme was not active in this system. Additionally, observed low inverse fractionation of carbon (ε(C) of +0.11‰ ± 0.03‰) and low fractionation of hydrogen (ε(H) of -5‰ ± 1‰) in laboratory experiments simulating MTBE stripping from an open surface water body suggest that the application of CSIA in field investigations to detect biodegradation may lead to false-negative results when volatilization effects coincide with the activity of low-fractionating enzymes. As shown in this study, complementary examination of expression of specific catabolic genes can be used as additional direct evidence for microbial degradation activity and may overcome this problem.

  11. Linking Low-Level Stable Isotope Fractionation to Expression of the Cytochrome P450 Monooxygenase-Encoding ethB Gene for Elucidation of Methyl tert-Butyl Ether Biodegradation in Aerated Treatment Pond Systems▿ †

    Science.gov (United States)

    Jechalke, Sven; Rosell, Mònica; Martínez-Lavanchy, Paula M.; Pérez-Leiva, Paola; Rohwerder, Thore; Vogt, Carsten; Richnow, Hans H.

    2011-01-01

    Multidimensional compound-specific stable isotope analysis (CSIA) was applied in combination with RNA-based molecular tools to characterize methyl tertiary (tert-) butyl ether (MTBE) degradation mechanisms occurring in biofilms in an aerated treatment pond used for remediation of MTBE-contaminated groundwater. The main pathway for MTBE oxidation was elucidated by linking the low-level stable isotope fractionation (mean carbon isotopic enrichment factor [ɛC] of −0.37‰ ± 0.05‰ and no significant hydrogen isotopic enrichment factor [ɛH]) observed in microcosm experiments to expression of the ethB gene encoding a cytochrome P450 monooxygenase able to catalyze the oxidation of MTBE in biofilm samples both from the microcosms and directly from the ponds. 16S rRNA-specific primers revealed the presence of a sequence 100% identical to that of Methylibium petroleiphilum PM1, a well-characterized MTBE degrader. However, neither expression of the mdpA genes encoding the alkane hydroxylase-like enzyme responsible for MTBE oxidation in this strain nor the related MTBE isotope fractionation pattern produced by PM1 could be detected, suggesting that this enzyme was not active in this system. Additionally, observed low inverse fractionation of carbon (ɛC of +0.11‰ ± 0.03‰) and low fractionation of hydrogen (ɛH of −5‰ ± 1‰) in laboratory experiments simulating MTBE stripping from an open surface water body suggest that the application of CSIA in field investigations to detect biodegradation may lead to false-negative results when volatilization effects coincide with the activity of low-fractionating enzymes. As shown in this study, complementary examination of expression of specific catabolic genes can be used as additional direct evidence for microbial degradation activity and may overcome this problem. PMID:21148686

  12. Simulation of methyl tert-butyl ether (MTBE) transport to ground water from immobile sources of gasoline in the vadose zone

    Science.gov (United States)

    Lahvis, M.A.; Rehmann, L.C.

    1999-01-01

    The mathematical model, R-UNSAT, developed to simulate the transport of benzene and MTBE in representative sand and clay hydrogeologic systems was evaluated. The effects on groundwater were simulated for small, chronic-, and single-volume releases of gasoline trapped in unsaturated soil. Hydrocarbon biodegradation was simulated by using a dual Monod-type kinetics model that includes oxygen and the reactive constituents. MTBE was assumed to be non-reactive. For MTBE, infiltration had the greatest effect on transport to groundwater. Infiltration also affected mass losses of MTBE to the atmosphere, particularly, in fine-grained soils. Depth to groundwater and soil type primarily affected travel times of MTBE to groundwater, but could affect mass-loading rates to groundwater if infiltration is insignificant. For benzene, transport to groundwater was significant only if the depth to the water table was MTBE by more than two orders of magnitude. Thus, water that recharges an aquifer beneath a spill can be enriched in MTBE relative to benzene when compared to the composition of water in equilibrium with gasoline.

  13. Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate)-poly(poly(ethylene glycol) methyl ether methacrylate) Copolymers

    OpenAIRE

    Patcharin Kanhakeaw; Boonjira Rutnakornpituk; Uthai Wichai; Metha Rutnakornpituk

    2015-01-01

    This work presented the surface modification of magnetite nanoparticle (MNP) with poly[(t-butyl acrylate)-stat-(poly(ethylene glycol) methyl ether methacrylate)] copolymers (P[(t-BA)-stat-PEGMA]) via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP). Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp.) such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water,...

  14. Surface-Initiated Atom Transfer Radical Polymerization of Magnetite Nanoparticles with Statistical Poly(tert-butyl acrylate-poly(poly(ethylene glycol methyl ether methacrylate Copolymers

    Directory of Open Access Journals (Sweden)

    Patcharin Kanhakeaw

    2015-01-01

    Full Text Available This work presented the surface modification of magnetite nanoparticle (MNP with poly[(t-butyl acrylate-stat-(poly(ethylene glycol methyl ether methacrylate] copolymers (P[(t-BA-stat-PEGMA] via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP. Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp. such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR. The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA and their magnetic properties were investigated via vibrating sample magnetometry (VSM.

  15. Aerobic mineralization of MTBE and tert-butyl alcohol by stream-bed sediment microorganisms

    Science.gov (United States)

    Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H.

    1999-01-01

    Microorganisms indigenous to the stream-bed sediments at two gasoline- contaminated groundwater sites demonstrated significant mineralization of the fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Up to 73% of [U-14C]-MTBE and 84% of [U-14C]-TBA were degraded to 14CO2 under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream-bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface water bodies by contaminated groundwater or by other sources.Microorganisms indigenous to the stream-bed sediments at two gasoline-contaminated groundwater sites demonstrated significant mineralization of the fuel oxygenates, methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Up to 73% of [U-14C]-MTBE and 84% of [U-14C]-TBA were degraded to 14CO2 under mixed aerobic/anaerobic conditions. No significant mineralization was observed under strictly anaerobic conditions. The results indicate that, under the mixed aerobic/anaerobic conditions characteristic of stream-bed sediments, microbial processes may provide a significant environmental sink for MTBE and TBA delivered to surface water bodies by contaminated groundwater or by other sources.

  16. Temperature effect on tert-butyl alcohol (TBA biodegradation kinetics in hyporheic zone soils

    Directory of Open Access Journals (Sweden)

    Sims Ronald C

    2007-09-01

    Full Text Available Abstract Background Remediation of tert-butyl alcohol (TBA in subsurface waters should be taken into consideration at reformulated gasoline contaminated sites since it is a biodegradation intermediate of methyl tert-butyl ether (MTBE, ethyl tert-butyl ether (ETBE, and tert-butyl formate (TBF. The effect of temperature on TBA biodegradation has not been not been published in the literature. Methods Biodegradation of [U 14C] TBA was determined using hyporheic zone soil microcosms. Results First order mineralization rate constants of TBA at 5°C, 15°C and 25°C were 7.84 ± 0.14 × 10-3, 9.07 ± 0.09 × 10-3, and 15.3 ± 0.3 × 10-3 days-1, respectively (or 2.86 ± 0.05, 3.31 ± 0.03, 5.60 ± 0.14 years-1, respectively. Temperature had a statistically significant effect on the mineralization rates and was modelled using the Arrhenius equation with frequency factor (A and activation energy (Ea of 154 day-1 and 23,006 mol/J, respectively. Conclusion Results of this study are the first to determine mineralization rates of TBA for different temperatures. The kinetic rates determined in this study can be used in groundwater fate and transport modelling of TBA at the Ronan, MT site and provide an estimate for TBA removal at other similar shallow aquifer sites and hyporheic zones as a function of seasonal change in temperature.

  17. Exposure to BTEX and Ethers in Petrol Station Attendants and Proposal of Biological Exposure Equivalents for Urinary Benzene and MTBE.

    Science.gov (United States)

    Campo, Laura; Rossella, Federica; Mercadante, Rosa; Fustinoni, Silvia

    2016-04-01

    To assess exposure to benzene (BEN) and other aromatic compounds (toluene, ethylbenzene, m+p-xylene, o-xylene) (BTEX), methyl tert-butyl ether (MTBE), and ethyl tert-butyl ether (ETBE) in petrol station workers using air sampling and biological monitoring and to propose biological equivalents to occupational limit values. Eighty-nine petrol station workers and 90 control subjects were investigated. Personal exposure to airborne BTEX and ethers was assessed during a mid-week shift; urine samples were collected at the beginning of the work week, prior to and at the end of air sampling. Petrol station workers had median airborne exposures to benzene and MTBE of 59 and 408 µg m(-3), respectively, with urinary benzene (BEN-U) and MTBE (MTBE-U) of 339 and 780 ng l(-1), respectively. Concentrations in petrol station workers were higher than in control subjects. There were significant positive correlations between airborne exposure and the corresponding biological marker, with Pearson's correlation coefficient (r) values of 0.437 and 0.865 for benzene and MTBE, respectively. There was also a strong correlation between airborne benzene and urinary MTBE (r = 0.835). Multiple linear regression analysis showed that the urinary levels of benzene were influenced by personal airborne exposure, urinary creatinine, and tobacco smoking [determination coefficient (R(2)) 0.572], while MTBE-U was influenced only by personal exposure (R(2) = 0.741). BEN-U and MTBE-U are sensitive and specific biomarkers of low occupational exposures. We propose using BEN-U as biomarker of exposure to benzene in nonsmokers and suggest 1457 ng l(-1) in end shift urine samples as biological exposure equivalent to the EU occupational limit value of 1 p.p.m.; for both smokers and nonsmokers, MTBE-U may be proposed as a surrogate biomarker of benzene exposure, with a biological exposure equivalent of 22 µg l(-1) in end shift samples. For MTBE exposure, we suggest the use of MTBE-U with a biological exposure

  18. 4-tert-Butyl-pyridinium triiodide-4-tert-butyl-pyridine (1/1).

    Science.gov (United States)

    He, Hongshan; Sykes, Andrew G

    2011-01-22

    The title compound, C(9)H(14)N(+)·I(3) (-)·C(9)H(13)N, consists of monoprotonated 4-tert-butyl-pyridinium cations and triiodide anions. The triiodide ion has near-symmetric linear geometry, with bond lengths of 2.9105 (4) Å (I-I) and a bond angle of 177.55 (3)° (I-I-I). For this room-temperature structure, the butyl group on the pyridine ring is disordered and has been treated as a rigid rotator, modeled in three separate positions with 1/3, 1/3, 1/3 occupancies. The cations assemble into dimeric forms by way of N-H⋯N hydrogen bonds.

  19. 4-tert-Butyl­pyridinium triiodide–4-tert-butyl­pyridine (1/1)

    Science.gov (United States)

    He, Hongshan; Sykes, Andrew G.

    2011-01-01

    The title compound, C9H14N+·I3 −·C9H13N, consists of monoprotonated 4-tert-butyl­pyridinium cations and triiodide anions. The triiodide ion has near-symmetric linear geometry, with bond lengths of 2.9105 (4) Å (I—I) and a bond angle of 177.55 (3)° (I—I—I). For this room-temperature structure, the butyl group on the pyridine ring is disordered and has been treated as a rigid rotator, modeled in three separate positions with 1/3, 1/3, 1/3 occupancies. The cations assemble into dimeric forms by way of N—H⋯N hydrogen bonds. PMID:21523100

  20. Catabolism of methyl ter-butyl ether (MTBE): characterization of the enzymes of Mycobacterium austroafricanum IFP 2012 involved in MTBE degradation; Catabolisme du methyl tert-butyl ether (MTBE): caracterisation des enzymes impliquees dans la degradation du MTBE chez Mycobacterium austroafricanum IFP 2012

    Energy Technology Data Exchange (ETDEWEB)

    Lopes Ferreira, N.

    2005-11-15

    Methyl tert-butyl ether (MTBE) is added to gasoline to meet the octane index requirement. its solubility in water and its poor biodegradability made the use of MTBE a great environmental concern, particularly regarding aquifers. We previously isolated M austroafricanum IFP 2012 able to use MTBE as a sole source of carbon and energy and the MTBE pathway was partially characterized. In the present study, which aimed at isolating the genes involved in MTBE biodegradation in order to use them for estimation of MTBE biodegradation capacities in contaminated environment, we isolated a new M. austroafricanum strain, IFP 2015. A new degradation intermediate, the 2-methyl 1,2-propane-diol (2-M1,2-PD), the product of tert-butanol (TBA) oxidation, was identified. We also determined the enzymes induced during growth of M. austroafricanum IFP 2012 on MTBF. Then, using the tools of protein analysis and of molecular biology, we isolated and cloned the mpd genes cluster in the plasmid pCL4D. Heterologous expression of the recombinant plasmid in M smegmatis tmc2 155, showed the involvement of an 2-M1,2-PD dehydrogenase (MpdB) and a hydroxy-iso-butyr-aldehyde dehydrogenase (MpdC), encoded by mpdB and mpdC, respectively. Both enzymes were responsible for the conversion of 2-M 1,2-PD to hydroxy-isobutyric acid (HIBA). A further survey of different M austroafricanum strains, including IFP 2012, IFP 2015 and JOBS (ex-M vaccae) showed the link between the ability to grow on C{sub 2} to C{sub 16} n-alkanes and the MTBE and TBA degradation capacities. The alkB gene was partially sequenced in all these strains. Expression of alkB was demonstrated in M. austroafricanum IFP 2012 after growth on propane, hexane, hexadecane and TBA. Finally, we identified 2-propanol as the intermediate of HIBA degradation. The gene encoding the 2-propanol:p-N,N'-dimethyl-4-nitroso-aniline (NDMA) oxidoreductase was detected M austroafricanum IFP 2012. (author)

  1. 27 CFR 21.101 - tert-Butyl alcohol.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21...

  2. 5-tert-Butyl-2-[5-(5-tert-butyl-1,3-benzoxazol-2-yl-2-thienyl]-1,3-benzoxazole

    Directory of Open Access Journals (Sweden)

    Fang-Fang Jian

    2008-12-01

    Full Text Available The title compound, C26H26N2O2S, was prepared by the reaction of thiophene-2,5-dicarboxylic acid and 2-amino-4-tert-butylphenol. One of the tert-butyl groups is disordered over two conformations, with occupancies of 0.539 (1 and 0.461 (2. The two 1,3-benzoxazole rings are almost planar, with dihedral angles of 0.83 (18 and 1.64 (17° between the five- and six-membered rings. The thiophene ring makes dihedral angles of 21.54 (19 and 4.49 (18° with the planes of the five-membered oxazole rings. The crystal packing is controlled by π–π stacking interactions involving the thiophene and benzene rings, with a centroid–centroid distance of 3.748 (2 Å.

  3. Four coordination polymers based on 5-tert-butyl isophthalic acid and rigid bis(imidazol-1yl)benzene linkers: Synthesis, luminescence detection of acetone and optical properties

    Science.gov (United States)

    Arıcı, Mürsel; Zafer Yeşilel, Okan; Büyükgüngör, Orhan

    2017-05-01

    Four coordination polymers including, [Co(μ-Htbip)2(μ-dib)]n (1), [Co(μ-tbip)(μ-dmib)0.5]n (2), [Zn2(μ-tbip)(μ3-tbip)(μ-dmib)1.5]n (3) and [Cd(μ3-tbip)(μ-dib)0.5 (H2O)]n (4) (tbip: 5-tert-butylisophthalate, dib: 1,4-bis(imidazol-1yl)benzene, dmib: 1,4-bis(imidazol-1yl)-2,5-dimethylbenzene), were hydrothermally synthesized and characterized by elemental analysis, IR spectra, single crystal and powder X-ray diffraction and thermal analysis (TG/DTA). The structural diversity is observed depending on ligands and coordination number of metal centers in the synthesized complexes. The tbip ligand displayed five different coordination modes in its complexes. In 1 and 2, complex 1 is 3D framework with the dia topology while complex 2 has 2D structure with the sql topology depending on coordination geometries of Co ions. Complex 3 is 3D framework with the fsh 4,6-conn topology and complex 4 has 2D 4-connected sql topology. Photoluminescent properties of complex 3 dispersed in various organic solvents were investigated and the results showed that 3 dispersed in methanol could be used as a fluorescent sensor for the detection of acetone. Moreover, thermal and optical properties of the complexes were also studied.

  4. A novel organogelator incorporating tert-butyl esters of asparagines.

    Science.gov (United States)

    Lozano, Virginia; Hernández, Rebeca; Mijangos, Carmen; Pérez-Pérez, María-Jesús

    2009-01-21

    A novel organogelator based on tert-butyl esters of asparagines has been synthesized and its organogelation abilities have been investigated. The rheological characterization has confirmed the gelation behavior, and its thixotropic properties. Furthermore, the morphological studies performed reveal a spherical structure. Thus, this organogelator can be considered as a new example of the emerging, but still reduced, list of gels with a non-fibrillar assembly.

  5. Molecular structures of tris(1-tert-butyl-2-mercaptoimidazolyl)hydroborate complexes of titanium, zirconium and hafnium.

    Science.gov (United States)

    Rong, Yi; Sambade, David; Parkin, Gerard

    2016-11-01

    Cyclopentadienyl and tris(pyrazolyl)hydroborate have found much use as supporting ligands in the chemistry of titanium, zirconium and hafnium, especially with respect to applications involving olefin polymerization catalysis. In contrast, closely related tris(1-alkyl-2-mercaptoimidazolyl)hydroborate, [Tm(R)], ligands have so far found little application to the chemistry of these elements, despite the fact that such ligands are currently used extensively in coordination chemistry. In view of the fact that a substituent in the 2-position exerts a direct influence on the steric environment of the metal center, we report here the application of the sterically demanding tris(1-tert-butyl-2-mercaptoimidazolyl)hydroborate [Tm(t-Bu)] ligand to these metals. Dichlorido(η(5)-cyclopentadienyl)[tris(1-tert-butyl-2-sulfanylidene-2,3-dihydro-1H-imidazol-3-yl)borato-κ(3)S,S',H]zirconium(IV) benzene hemisolvate, [Zr(C21H34BN6S3)(C5H5)Cl2]·0.5C6H6, (I), dichlorido(η(5)-cyclopentadienyl)[tris(1-tert-butyl-2-sulfanylidene-2,3-dihydro-1H-imidazol-3-yl)borato-κ(3)S,S',H]titanium(IV) benzene hemisolvate, [Ti(C21H34BN6S3)(C5H5)Cl2]·0.5C6H6, (II), [bis(1-tert-butyl-2-sulfanylidene-2,3-dihydro-1H-imidazol-3-yl)borato-κ(3)S,S',H]dichlorido(η(5)-cyclopentadienyl)zirconium(IV), [Zr(C14H24BN4S2)(C5H5)Cl2], (III), (1-tert-butyl-2,3-dihydro-1H-imidazole-2-thione-κS)(1-tert-butyl-2-sulfanylidene-1H-imidazol-3-ido-κ(2)N(3),S)dichlorido(η(5)-cyclopentadienyl)zirconium(IV) benzene monosolvate, [Zr(C7H11N2S)(C7H12N2S)(C5H5)Cl2]·C6H6, (IV), and tribenzyl[tris(1-tert-butyl-2-sulfanylidene-2,3-dihydro-1H-imidazol-3-yl)borato-κ(3)S,S',S'']hafnium(IV) benzene tetrasolvate, [Hf(C7H7)3(C21H34BN6S3)]·4C6H6, (V), have been structurally characterized by X-ray diffraction. The [Tm(t-Bu)] ligand coordinates to Ti and Zr in Cp[κ(3)S2,H-Tm(t-Bu)]MCl2 [M = Zr, (I), and Ti, (II)] in a κ(3)S2,H mode, while the benzyl compounds [Tm(t-Bu)]M(CH2Ph)3 [M = Zr and Hf, (V)] exhibit κ(3)S3 coordination.

  6. Product analyses and kinetic studies on gas phase oxidation of the fuel additive ethyl tert-butyl ether and its products; Produktanalysen und Kinetikuntersuchungen der Gasphasenoxidation des Kraftstoffadditivs Ethyl-tert-butylether und seiner Produkte

    Energy Technology Data Exchange (ETDEWEB)

    Becker, K.H.; Thuener, L.

    1997-04-01

    The widespread use of the additive ETBE in gasoline leads to an increased release of this compound into the atmosphere via evaporation or exhaust fumes. In order to determine the influence of this additive on trace gas cycles it is first necessary to carry out studies on the degradation mechanisms and pertinent kinetic properties of this substance. The aim of the present study was to examine the degradation mechanisms of the fuel additive t-butyl ethyl ether under atmospheric conditions. The reactions of the main degradation products (t-butyl formiate and t-butyl acetate, together ca. 80%) were also studied in order to obtain as complete a picture of the degradation paths as possible. This was to permit an assessment of the influence of ETBE and its products on tropospheric trace gas cycles and ozone formation. [Deutsch] Bei haeufigem Zusatz von ETBE in Benzin wird diese Verbindung durch Verdampfung oder als Abgas verstaerkt in die Atmosphaere abgegeben. Um den Einfluss des Additivs auf die Spurengas-Kreislaeufe zu bestimmen, sind daher Untersuchungen noetig, um die Abbau-Mechanismen und die zugehoerigen kinetischen Daten zu ermitteln. Das Ziel dieser Arbeit ist die Untersuchung der Abbaumechanismen des Kraftstoffadditivs t-Butylethylether unter atmosphaerischen Bedingungen. Fuer eine moeglichst vollstaendige Analyse des Abbauweges werden auch die Reaktionen der Hauptabbauprodukte (t-Butylformiat und t-Butylacetat, zusammen etwa 80%) untersucht. Dadurch soll der Einfluss auf troposphaerische Spurengas-Kreislaeufe und auf die Ozonbildung von ETBE und seinen Produkten abgeschaetzt werden. (orig./SR)

  7. Customer exposure to MTBE, TAME, C6 alkyl methyl ethers, and benzene during gasoline refueling.

    Science.gov (United States)

    Vainiotalo, S; Peltonen, Y; Ruonakangas, A; Pfäffli, P

    1999-01-01

    We studied customer exposure during refueling by collecting air samples from customers' breathing zone. The measurements were carried out during 4 days in summer 1996 at two Finnish self-service gasoline stations with "stage I" vapor recovery systems. The 95-RON (research octane number) gasoline contained approximately 2.7% methyl tert-butyl ether (MTBE), approximately 8.5% tert-amyl methyl ether (TAME), approximately 3.2% C6 alkyl methyl ethers (C6 AMEs), and 0.75% benzene. The individual exposure concentrations showed a wide log-normal distribution, with low exposures being the most frequent. In over 90% of the samples, the concentration of MTBE was higher (range MTBE values were well below the short-term (15 min) threshold limits set for occupational exposure (250-360 mg/m3). At station A, the geometric mean concentrations in individual samples were 3.9 mg/m3 MTBE and 2. 2 mg/m3 TAME. The corresponding values at station B were 2.4 and 1.7 mg/m3, respectively. The average refueling (sampling) time was 63 sec at station A and 74 sec at station B. No statistically significant difference was observed in customer exposures between the two service stations. The overall geometric means (n = 167) for an adjusted 1-min refueling time were 3.3 mg/m3 MTBE and 1.9 mg/m3 TAME. Each day an integrated breathing zone sample was also collected, corresponding to an arithmetic mean of 20-21 refuelings. The overall arithmetic mean concentrations in the integrated samples (n = 8) were 0.90 mg/m3 for benzene and 0.56 mg/m3 for C6 AMEs calculated as a group. Mean MTBE concentrations in ambient air (a stationary point in the middle of the pump island) were 0.16 mg/m3 for station A and 0.07 mg/m3 for station B. The mean ambient concentrations of TAME, C6 AMEs, and benzene were 0.031 mg/m3, approximately 0.005 mg/m3, and approximately 0.01 mg/m3, respectively, at both stations. The mean wind speed was 1.4 m/sec and mean air temperature was 21 degreesC. Of the gasoline refueled during the

  8. Di-tert-butyl (2R,3R-2-{[(2E-3-(4-acetyloxy-3-methoxyphenylprop-2-enoyl]oxy}-3-hydroxybutanedioate

    Directory of Open Access Journals (Sweden)

    Edward R. T. Tiekink

    2012-03-01

    Full Text Available In the title molecule, C24H32O10, one tert-butyl ester group is folded towards the central benzene ring while the other is directed away. The acetyl group is almost perpendicular to the benzene ring to which it is connected [C—C—O—C torsion angle = 90.4 (12°]. The conformation about the ethene bond [1.313 (7 Å] is E. The atoms of the benzene ring and its attached ester group and part of the hydroxy tert-butyl ester side chain are disordered over two sets of sites in a 50:50 ratio. Linear supramolecular chains along the a axis mediated by hydroxy–carbonyl O—H...O hydrogen bonds feature in the crystal packing. The same H atom also partakes in an intramolecular O—H...O interaction.

  9. Design and Control of Glycerol-tert-Butyl Alcohol Etherification Process

    Science.gov (United States)

    Vlad, Elena; Bozga, Grigore

    2012-01-01

    Design, economics, and plantwide control of a glycerol-tert-butyl alcohol (TBA) etherification plant are presented. The reaction takes place in liquid phase, in a plug flow reactor, using Amberlyst 15 as a catalyst. The products' separation is achieved by two distillation columns where high-purity ethers are obtained and a section involving extractive distillation with 1,4-butanediol as solvent, which separates TBA from the TBA/water azeotrope. Details of design performed in AspenPlus and an economic evaluation of the process are given. Three plantwide control structures are examined using a mass balance model of the plant. The preferred control structure fixes the fresh glycerol flow rate and the ratio glycerol + monoether : TBA at reactor-inlet. The stability and robustness in the operation are checked by rigorous dynamic simulation in AspenDynamics. PMID:23365512

  10. Design and Control of Glycerol-tert-Butyl Alcohol Etherification Process

    Directory of Open Access Journals (Sweden)

    Elena Vlad

    2012-01-01

    Full Text Available Design, economics, and plantwide control of a glycerol-tert-butyl alcohol (TBA etherification plant are presented. The reaction takes place in liquid phase, in a plug flow reactor, using Amberlyst 15 as a catalyst. The products' separation is achieved by two distillation columns where high-purity ethers are obtained and a section involving extractive distillation with 1,4-butanediol as solvent, which separates TBA from the TBA/water azeotrope. Details of design performed in AspenPlus and an economic evaluation of the process are given. Three plantwide control structures are examined using a mass balance model of the plant. The preferred control structure fixes the fresh glycerol flow rate and the ratio glycerol + monoether : TBA at reactor-inlet. The stability and robustness in the operation are checked by rigorous dynamic simulation in AspenDynamics.

  11. tert-Butyl N-(thiophen-2-ylcarbamate

    Directory of Open Access Journals (Sweden)

    Gene C. Hsu

    2013-09-01

    Full Text Available In the title compound, C9H13NO2S, the dihedral angle between the thiophene ring and the carbamate group is 15.79 (14°. In the crystal structure, intramolecular C—H...O interactions in tandem with the tert-butyl groups render the packing of adjacent molecules in the [001] direction nearly perpendicular [the angle between adjacent thiophene rings is 74.83 (7°]. An intermolecular N—H...O hydrogen bond gives rise to a chain extending along [001]. The crystal studied was found to be a racemic twin.

  12. Electrochemical degradation of methyl tert-butyl ether

    Directory of Open Access Journals (Sweden)

    Aleksandr B. Velichenko

    2014-12-01

    Full Text Available In this paper, we have examined the performance of PbO2 anodes in the EC degradation of MTBE. It was shown that electrochemical oxidation of MTBE at lead dioxide anodes is effective method of anodic conversion of the organic pollutant to acetic acid as untoxic product. Proposed method is formally reagent treatment of water at the same time it does not need addition of any reagent in reaction media. All needed reagents formed directly from the solvent (water thanks to electrochemical reactions. According to obtained data the main electrochemical stages of the process of anodic conversion of MTBE are formation of hydroxyl-radicals and molecular oxygen. Then formed compounds take part in stages of chemical MTBE oxidation and intermediate species that led to deeper oxidation to form acetic acid as the result. Proposed mechanism of MTBE electrochemical oxidation is in satisfactory agreement with experimental data. Dependence of MTBE conversion rate from the nature of micro-doped and composite lead dioxide anodes is explained by difference in hydroxyl-radical bond strength with an electrode surface that determined it reaction ability in secondary chemical reactions of organic compounds oxidation.

  13. An investigation of 2,5-di-tertbutyl-1,4-bis(methoxyethoxy)benzene in ether-based electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Su, Liang; Ferrandon, Magali; Barton, John L.; de la Rosa, Noel Upia; Vaughey, John T.; Brushett, Fikile R.

    2017-08-01

    The identification and development of conductive electrolytes with high concentrations of redox active species is key to realizing energy-dense nonaqueous flow batteries. Herein, we explore the use of ether solvents (1,3-dioxolane (DOL), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (DEGDME), and tetraethylene glycol dimethyl ether (TEGDME)) as the basis for redox electrolytes containing a lithium ion supporting salt (LiBF4 or LiTFSI) and 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB) as an active material. An automated high-throughput platform is employed to screen various electrolyte compositions by measuring solution conductivity and solute solubility as a function of solvent and salt type, component concentration, and temperature. Subsequently, the electrochemical and transport properties of select redox electrolytes are characterized by cyclic voltammetry using glassy carbon disk electrodes and by linear sweep voltammetry using carbon fiber ultramicroelectrodes. In general, improvements in electrolyte conductivity and solute solubility are observed with ether-based formulations as compared to previously reported propylene carbonate (PC)-based formulations. In particular, the addition of DOL to a DME-based electrolyte increases the conductivity and decreases the temperature for solubilization at high LiTFSI and DBBB concentrations. The redox behavior of DBBB remains consistent across the range of concentrations tested while the diffusion coefficient scales with changes in solution viscosity.

  14. Synthesis of Highly Porous Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) Asymmetric Membranes

    KAUST Repository

    Xie, Yihui

    2016-03-24

    For the first time, self-assembly and non-solvent induced phase separation was applied to polysulfone-based linear block copolymers, reaching mechanical stability much higher than other block copolymers membranes used in this method, which were mainly based on polystyrene blocks. Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) (PtBA30k-b-PSU14k-b-PtBA30k) with a low polydispersity of 1.4 was synthesized by combining step-growth condensation and RAFT polymerization. Various advanced electron microscopies revealed that PtBA30k-b-PSU14k-b-PtBA30k assembles into worm-like cylindrical micelles in DMAc and adopts a “flower-like” arrangement with the PSU central block forming the shell. Computational modeling described the mechanism of micelle formation and morphological transition. Asymmetric nanostructured membranes were obtained with a highly porous interconnected skin layer and a sublayer with finger-like macrovoids. Ultrafiltration tests confirmed a water permeance of 555 L m-2 h-1 bar-1 with molecular weight cut-off of 28 kg/mol. PtBA segments on the membrane surface were then hydrolyzed and complexed with metals, leading to cross-linking and enhancement of antibacterial capability.

  15. (2E-4-tert-Butyl-2-(4-methoxybenzylidene-3,4-dihydronaphthalen-1(2H-one

    Directory of Open Access Journals (Sweden)

    Mohamed Akhazzane

    2011-07-01

    Full Text Available In the title compound C22H24O2, the exocyclic C=C double bond is in an E configuration and the tert-butyl group is in an axial position on the cyclohexanone ring. The cyclohexanone ring in the dihydronaphthalene fused-ring system adopts a half-chair conformation in both independent two molecules in the asymetric unit. The benzene ring system is oriented angles of 43.97 (12 and 39.24 (12° with respect to the naphthyl ring system in the two independent molecules. In the crystal, molecules are linked via C—H...O hydrogen bonds and C—H...π interactions.

  16. Selective enzymatic hydrolysis of C-terminal tert-butyl esters of peptides

    NARCIS (Netherlands)

    Eggen, I.F.; Boeriu, C.G.

    2007-01-01

    The present invention relates to a process for the selective enzymatic hydrolysis of C-terminal esters of peptide substrates in the synthesis of peptides, comprising hydrolysing C-terminal tert-butyl esters using the protease subtilisin. This process is useful in the production of protected or

  17. Selective enzymatic hydrolysis of C-terminal tert-butyl esters of peptides

    OpenAIRE

    Eggen, I.F.; Boeriu, C.G.

    2007-01-01

    The present invention relates to a process for the selective enzymatic hydrolysis of C-terminal esters of peptide substrates in the synthesis of peptides, comprising hydrolysing C-terminal tert-butyl esters using the protease subtilisin. This process is useful in the production of protected or unprotected peptides.

  18. and triorganotin(IV) complexes of 2-tert-butyl-4-methyl phenol

    Indian Academy of Sciences (India)

    TECS

    of organotin(IV) complexes of phenols are found in literature. 13–17 .... method suggested them to exist as monomers. 3.1 IR spectra. In the IR .... Tert-butyl. Phenolic butyl substituent. Phenolic ring carbon. Phenolic ring substituent Methyl. 119. Sn. Compound group protons protons protons R–Sn –CH3. –C o, m and p Cipso.

  19. (R-N-{2-tert-Butyl-2-[(R-tert-butylsulfonamido]ethylidene}-tert-butanesulfonamide

    Directory of Open Access Journals (Sweden)

    Cong-Bin Fan

    2008-10-01

    Full Text Available The title compound, C14H30N2O2S2, is the product of the monoaddition reaction of tert-butyl magnesium chloride with bis-[(R-N-tert-butanesulfinyl]ethanediimine. There are two almost identical molecules in the asymmetric unit, the molecular conformation of which is stabilized by an intramolecular N—H...N hydrogen bond.

  20. A new efficient synthesis of isothiocyanates from amines using di-tert-butyl dicarbonate

    DEFF Research Database (Denmark)

    Munch, Henrik; Hansen, Jon S.; Pittelkow, Michael

    2008-01-01

    Alkyl and aryl amines are converted smoothly to the corresponding isothiocyanates via the dithiocarbamates in good to excellent yields using di-tert-butyl dicarbonate (Boc(2)O) and 1-3 mol% of DMAP or DABCO as catalyst. As most of the byproducts are volatile, the work-up involves simple evaporation...

  1. Preparation and characterization of a p-tert-butyl-calix[6]-1,4-benzocrown-4-bonded silica gel stationary phase for liquid chromatography.

    Science.gov (United States)

    Li, Lai-Sheng; Da, Shi-Lu; Feng, Yu-Qi; Liu, Min

    2004-06-18

    A p-tert-butyl-calix[6]-1,4-benzocrown-4-bonded silica gel stationary phase (CR6BS) was first prepared via 3-glycidoxypropyltrimethoxysilane as coupling reagent for high performance liquid chromatography. The structure of the new stationary phase was characterized by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), elemental analysis and thermal analysis. The chromatographic performance of the bonded-stationary phase was evaluated by using neutral, acidic and basic solutes as probes. Meanwhile, comparative study of the new stationary phase with a p-tert-butyl-calix[6]arene-bonded silica gel stationary phase (C6BS, the parent) and ODS was done under the same chromatographic conditions. The results show that the new stationary phase has an excellent reversed-phase property, which is similar to C6BS and ODS. However, the selectivities for some aromatic compounds are different from the parent phase (C6BS) and ODS, especially the latter. In one hand, as hybrid of calixarene and crown ether, CR6BS with the oxygen atoms of ether-bridge can provide the complexation sites for the solutes, lacking of C6BS. On the other hand, the rigid conformation of CR6BS may be responsible to the different performance partially. CR6BS exhibits high selectivity in the separation of alkylated aromatics from their parents as compared with C6BS.

  2. 1,4-Di-tert-butyl (2R,3R-2-({(2E-3-[4-(acetyloxyphenyl]prop-2-enoyl}oxy-3-hydroxybutanedioate

    Directory of Open Access Journals (Sweden)

    Josh L. Hixson

    2012-02-01

    Full Text Available The title compound, C23H30O9, has an approximate T-shape with the tert-butyl ester groups lying either side of the benzene ring. The acetyl group is almost perpendicular to the benzene ring to which it is connected [C—C—O—C torsion angle = −106.7 (3°]. The conformation about the C=C double bond [1.331 (4 Å] is E. Linear supramolecular chains along the a axis mediated by hydroxy–carbonyl O—H...O hydrogen bonds feature in the crystal packing. The same H atom is also involved in an intramolecular O—H...O interaction.

  3. Cultivation of Aquincola tertiaricarbonis L108 on the fuel oxygenate intermediate tert-butyl alcohol induces aerobic anoxygenic photosynthesis at extremely low feeding rates.

    Science.gov (United States)

    Rohwerder, Thore; Müller, Roland H; Weichler, M Teresa; Schuster, Judith; Hübschmann, Thomas; Müller, Susann; Harms, Hauke

    2013-10-01

    Aerobic anoxygenic photosynthesis (AAP) is found in an increasing number of proteobacterial strains thriving in ecosystems ranging from extremely oligotrophic to eutrophic. Here, we have investigated whether the fuel oxygenate-degrading betaproteobacterium Aquincola tertiaricarbonis L108 can use AAP to compensate kinetic limitations at low heterotrophic substrate fluxes. In a fermenter experiment with complete biomass retention and also during chemostat cultivation, strain L108 was challenged with extremely low substrate feeding rates of tert-butyl alcohol (TBA), an intermediate of methyl tert-butyl ether (MTBE). Interestingly, formation of photosynthetic pigments, identified as bacteriochlorophyll a and spirilloxanthin, was only induced in growing cells at TBA feeding rates less than or equal to maintenance requirements observed under energy excess conditions. Growth continued at rates between 0.001 and 0.002 h(-1) even when the TBA feed was decreased to values close to 30 % of this maintenance rate. Partial sequencing of genomic DNA of strain L108 revealed a bacteriochlorophyll synthesis gene cluster (bchFNBHL) and photosynthesis regulator genes (ppsR and ppaA) typically found in AAP and other photosynthetic proteobacteria. The usage of light as auxiliary energy source enabling evolution of efficient degradation pathways for kinetically limited heterotrophic substrates and for lowering the threshold substrate concentration Smin at which growth becomes zero is discussed.

  4. 5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetrakis[2-(2-chloroethoxyethoxy]-2,8,14,20-tetrasulfonylcalix[4]arene

    Directory of Open Access Journals (Sweden)

    Dian-Shun Guo

    2009-02-01

    Full Text Available Molecules of the title compound, C56H76Cl4O16S4, have crystallographic C2 symmetry and adopt a 1,3-alternate conformation where the four –OCH2CH2OCH2CH2Cl groups are located alternately above and below the virtual plane (R defined by the four bridging S atoms. The dihedral angles between the plane (R and the phenolic rings are 72.85 (7 and 74.57 (7°. An unusual 24-membered macrocyclic ring is formed in the crystal structure with an array of eight intramolecular C—H...O hydrogen bonds between the ether arm H atoms and the sulfonyl O atoms. In the supramolecular structure, the molecular components are linked into infinite zigzag one-dimensional chains by a combination of four intermolecular C—H...O hydrogen bonds, forming R22(13, R22(16, R22(21 and R22(26 ring motifs. These chains are augmented into a wave-like two-dimensional network by weak C...O interactions. One tert-butyl group shows rotational disorder, and one CH2CH2Cl group is disordered over two orientations; the site-occupation factors are 0.756 (6 and 0.244 (6 for the two tert-butyl groups, and 0.808 (3 and 0.192 (3 for the two CH2CH2Cl units.

  5. 1-[(E-2-(5-tert-Butyl-2-hydroxyphenyldiazen-1-yl]naphthalen-2-ol

    Directory of Open Access Journals (Sweden)

    Hassiba Bougueria

    2014-02-01

    Full Text Available The non-H atoms of the title compound, C20H20N2O2, is located on a mirror plane except two methyl groups of the tert-butyl group. Intramolecular N—H...O hydrogen bonds exist between the hydroxy and diazenyl groups. In the crystal, molecules are linked by weak C—H...O hydrogen bonds into supramolecular chains running along the a-axis direction.

  6. Tert-butyl alcohol used to fabricate nano-cellulose aerogels via freeze-drying technology

    Science.gov (United States)

    Wang, Xiaoyu; Zhang, Yang; Jiang, Hua; Song, Yuxuan; Zhou, Zhaobing; Zhao, Hua

    2017-06-01

    Aerogel, a highly porous material, is attracting increasing attention owing to low thermal conductivity and high specific surface area. Freeze-drying technology has been employed to produce nano-cellulose aerogels; however, the resultant product has low specific surface areas. Here, a modified approach to prepare nano-cellulose aerogels was reported, which involves tert-butyl alcohol as a solvent. Nano-cellulose aerogels were prepared via a spontaneous gelation fashion using calcium chloride solution, followed by tert-butyl alcohol solvent displacement and freeze drying. Addition of calcium chloride (0.25%) accelerated the physical gelation process. The application of tert-butyl alcohol as a solvent contributed to preservation of gel network. The obtained spherical nano-cellulose aerogels had a shrinkage rate of 5.89%. The specific surface area and average pore size was 164. 9666 m2 g-1 and 10.01 nm, respectively. Additionally, nano-cellulose aerogels had a comparable thermal degradation property when compared to microcrystalline cellulose. These biophysical properties make nano-cellulose aerogels as a promising absorption material.

  7. Carbonyl{3,3′-di-tert-butyl-5,5′-dimethoxy-2,2′-bis[(4,4,5,5-tetramethyl-1,3,2-dioxaphospholan-2-yloxy]biphenyl-κ2P,P′}hydrido(triphenylphosphane-κPrhodium(I diethyl ether trisolvate

    Directory of Open Access Journals (Sweden)

    Detlef Selent

    2013-01-01

    Full Text Available In the title compound, [RhH(C74H68O8P2(C18H15P(CO]·3C4H10O, the CHP3 coordination set at the RhI ion is arranged in a distorted trigonal–bipyramidal geometry with the P atoms adopting equatorial coordination sites and the C atom of the carbonyl ligand as well as the H atom adopting the axial sites. The asymmetric unit contains two very similar molecules of the rhodium complex, two half-occupied diethyl ether molecules and further diethyl ether solvent molecules which could not be modelled successfully. Therefore contributions of the latter were removed from the diffraction data using the SQUEEZE procedure in PLATON [Spek (2009. Acta Cryst. D65, 148–155].

  8. Oxidation of heteroleptic diarylpalladium compounds with tert-butyl hydroperoxide. Substituent effects in aromatic oxidation reactions

    NARCIS (Netherlands)

    Koten, G. van; Valk, J.-M.; Boersma, J.

    1996-01-01

    A series of heteroleptic diarylpalladium compounds, containing both a naphthyl (1-C10H6CH2NMe2-2 or 1-C10H5CH2NMe2-2-Me-3) and a phenyl (1-C6H4CH2NMe2-2 or 1-C6H3CH2NMe2-2-Me-x, x = 3, 5, 6) monoanionic C,N-bidentate ligand, was reacted with tert-butyl hydroperoxide (TBHP) to give selective oxygen

  9. tert-Butyl 2-(3-acetylamino-2-oxo-1,2-dihydro-1-pyridylacetate

    Directory of Open Access Journals (Sweden)

    Peter C. Healy

    2008-12-01

    Full Text Available The title compound, C13H18N2O4, crystallizes as discrete molecules associated as N—H...O hydrogen-bonded dimers disposed about a crystallographic inversion centre. The structure is the first solid-state structure for a 3-acetylpyridone without C-4 to C-6 substituents. The amide subsituent at C-3 is coplanar with the pyridone ring, while the tert-butyl ester group is orthogonal to the pyridine ring. The amide and ester carbonyl O atoms are not involved in strong hydrogen bonding with only a number of intramolecular and intermolecular C—H...O interactions apparent in the structure.

  10. One-electron redox reaction of di-tert-butyl nitroxide at platinum electrode in acetonitrile

    Energy Technology Data Exchange (ETDEWEB)

    Kishioka, Shin-ya; Yamada, Akifumi [Nagaoka University of Technology, Nagaoka, Niigata (Japan). Department of Chemistry, Faculty of Engineering

    2005-10-20

    The electrochemical oxidation of di-tert-butyl nitroxide (DTBN) at a platinum electrode in acetonitrile was examined. The cyclic voltammogram indicated an irreversible response during a normal time scale measurement, whereas chemically reversible voltammograms were obtained during a shorter time using a micro disk electrode with relatively fast sweep rates. The apparent formal redox potential and heterogeneous electron transfer rate constant were estimated to be 0.218 V (versus Fc{sup +}Fc) and 0.035 {+-} 0.015 cms{sup -1} from the digital simulation analysis. (author)

  11. 2,6-Di-tert-butyl-4-(methoxy-meth-yl)phenol.

    Science.gov (United States)

    Zeng, Tao; Sun, Ju-Feng

    2008-02-13

    The title compound, C(16)H(26)O(2), was easily obtained in high yield when 4-bromo-methyl-2,6-di-tert-butyl-phenol was reacted with methanol. There are two independent mol-ecules in the asymmetric unit. The meth-oxy group in each of the independent mol-ecules was found to be disordered, with site-occupation factors of 0.8728 (18)/0.1272 (18) and 0.8781 (17)/0.1219 (17).

  12. Simultaneous determination of gasoline oxygenates and benzene, toluene, ethylbenzene and xylene in water samples using headspace-programmed temperature vaporization-fast gas chromatography-mass spectrometry.

    Science.gov (United States)

    Pérez Pavón, José Luis; del Nogal Sánchez, Miguel; Fernández Laespada, María Esther; Moreno Cordero, Bernardo

    2007-12-14

    A sensitive method is presented for the fast analysis of seven fuel oxygenates (methanol, ethanol, tert-butyl alcohol (TBA), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE)) and benzene, toluene, ethylbenzene and p-xylene (BTEX) in water samples. The applicability of a headspace (HS) autosampler in combination with a GC device equipped with a programmable temperature vaporizer (PTV) and a MS detector is explored. The proposed method achieves a clear improvement in sensitivity with respect to conventional headspace methods due to the use of the PTV. Two different packed liners with materials of different trapping strengths (glass wool and Tenax-TA) were compared. The benefits of using Tenax-TA instead of glass wool as packed material for the measurement of the 11 compounds emerged as better signal-to-noise ratios and hence better detection limits. The proposed method is extremely sensitive. The limits of detection are of the order of ng/L for six of the compounds studied and of the order of microg/L for the rest, with the exception of the most polar and volatile compound: methanol. Precision (measured as the relative standard deviation for a level with an S/N ratio close to 3) was equal to or lower than 15% in all cases. The method was applied to the determination of the analytes in natural matrixes (tap, river and sea water) and the results obtained can be considered highly satisfactory. The methodology has much lower detection limits than the concentration limits proposed in drinking water by the US Environmental Protection Agency (EPA) and the European Union for compounds under regulation.

  13. Enzymatic Kinetic Resolution of tert-Butyl 2-(1-Hydroxyethylphenylcarbamate, A Key Intermediate to Chiral Organoselenanes and Organotelluranes

    Directory of Open Access Journals (Sweden)

    Leandro Piovan

    2011-09-01

    Full Text Available The enzymatic kinetic resolution of tert-butyl 2-(1-hydroxyethyl phenylcarbamate via lipase-catalyzed transesterification reaction was studied. We investigated several reaction conditions and the carbamate was resolved by Candida antarctica lipase B (CAL-B, leading to the optically pure (R- and (S-enantiomers. The enzymatic process showed excellent enantioselectivity (E > 200. (R- and (S-tert-butyl 2-(1-hydroxyethylphenylcarbamate were easily transformed into the corresponding (R- and (S-1-(2-aminophenylethanols.

  14. Review of quantitative surveys of the length and stability of MTBE, TBA, and benzene plumes in groundwater at UST sites.

    Science.gov (United States)

    Connor, John A; Kamath, Roopa; Walker, Kenneth L; McHugh, Thomas E

    2015-01-01

    Quantitative information regarding the length and stability condition of groundwater plumes of benzene, methyl tert-butyl ether (MTBE), and tert-butyl alcohol (TBA) has been compiled from thousands of underground storage tank (UST) sites in the United States where gasoline fuel releases have occurred. This paper presents a review and summary of 13 published scientific surveys, of which 10 address benzene and/or MTBE plumes only, and 3 address benzene, MTBE, and TBA plumes. These data show the observed lengths of benzene and MTBE plumes to be relatively consistent among various regions and hydrogeologic settings, with median lengths at a delineation limit of 10 µg/L falling into relatively narrow ranges from 101 to 185 feet for benzene and 110 to 178 feet for MTBE. The observed statistical distributions of MTBE and benzene plumes show the two plume types to be of comparable lengths, with 90th percentile MTBE plume lengths moderately exceeding benzene plume lengths by 16% at a 10-µg/L delineation limit (400 feet vs. 345 feet) and 25% at a 5-µg/L delineation limit (530 feet vs. 425 feet). Stability analyses for benzene and MTBE plumes found 94 and 93% of these plumes, respectively, to be in a nonexpanding condition, and over 91% of individual monitoring wells to exhibit nonincreasing concentration trends. Three published studies addressing TBA found TBA plumes to be of comparable length to MTBE and benzene plumes, with 86% of wells in one study showing nonincreasing concentration trends. © 2014 GSI Environmental Inc. Groundwater published by Wiley Periodicals, Inc. on behalf of National Ground Water Association.

  15. Effect of tert-Butyl Functionalization on the Photoexcited Decay of a Fe(II)-N-Heterocyclic Carbene Complex

    DEFF Research Database (Denmark)

    Pápai, Mátyás Imre; Penfold, Thomas J.; Møller, Klaus Braagaard

    2016-01-01

    . This occurs because the tert-butyl functionalization stabilizes the 1MC states, enabling the 1,3MLCT → 1MC population transfer to occur close to the Franck-Condon geometry, making the conversion very efficient. Subsequently, a spin cascade occurs within the MC manifold, leading to the population of triplet...

  16. Crystal structure of 2-tert-butyl-1,3-thiazolo[4,5-b]pyridine

    Directory of Open Access Journals (Sweden)

    Gamal A. El-Hiti

    2014-09-01

    Full Text Available The title compound, C10H12N2S, does not contain any strong hydrogen-bond donors but two long C—H...N contacts are observed in the crystal structure, with the most linear interaction linking molecules along [010]. The ellipsoids of the tert-butyl group indicate large librational motion.

  17. Crystal structure of (1,3-di-tert-butyl-η5-cyclopentadienyltrimethylhafnium(IV

    Directory of Open Access Journals (Sweden)

    Adrián Pérez-Redondo

    2015-05-01

    Full Text Available The molecule of the title organometallic hafnium(IV compound, [Hf(CH33(C13H21] or [HfMe3(η5-C5H3-1,3-tBu2], adopts the classical three-legged piano-stool geometry for monocyclopentadienylhafnium(IV derivatives with the three methyl groups bonded to the Hf(IV atom at the legs. The C atoms of the two tert-butyl group bonded to the cyclopentadienyl (Cp ring are 0.132 (5 and 0.154 (6 Å above the Cp least-squares plane. There are no significant intermolecular interactions present between the molecules in the crystal structure.

  18. Pressure effect on water dynamics in tert-butyl alcohol/water solutions

    Science.gov (United States)

    Calandrini, Vania; Deriu, Antonio; Onori, Giuseppe; Paciaroni, Alessandro; Telling, Mark T. F.

    2006-09-01

    We report here a quasi-elastic neutron scattering (QENS) investigation of the effect of pressure on the diffusivity properties of water in a dilute aqueous solution of hydrophobic molecules (tert-butyl alcohol, TBA). The experiment was performed at fixed TBA concentration (0.02 molar fraction) by varying pressure from 1 to 2000 bar at two different temperatures (268 and 278 K). The quasi-elastic line-shapes have been analysed in terms of a model based on the memory function formalism. Our data indicate that, on increasing pressure up to 2000 bar, the diffusion coefficient of water in the TBA/water mixture exhibits a relative increase larger than that of pure water under the same thermodynamic conditions. The extent of this effect increases with decreasing temperature. The observed behaviour is described in terms of pressure-induced distortions of the H-bonded random network of liquid water.

  19. (2S,4R)- and (2S,4S)-perfluoro-tert-butyl 4-hydroxyproline: two conformationally distinct proline amino acids for sensitive application in 19F NMR.

    Science.gov (United States)

    Tressler, Caitlin M; Zondlo, Neal J

    2014-06-20

    (2S,4R)- and (2S,4S)-perfluoro-tert-butyl 4-hydroxyproline were synthesized (as Fmoc-, Boc-, and free amino acids) in 2-5 steps. The key step of each synthesis was a Mitsunobu reaction with perfluoro-tert-butanol, which incorporated a perfluoro-tert-butyl group, with nine chemically equivalent fluorines. Both amino acids were incorporated in model α-helical and polyproline helix peptides. Each amino acid exhibited distinct conformational preferences, with (2S,4R)-perfluoro-tert-butyl 4-hydroxyproline promoting polyproline helix. Peptides containing these amino acids were sensitively detected by (19)F NMR, suggesting their use in probes and medicinal chemistry.

  20. TRANSPORT OF METHYL TERT-BUTYL ETHER THROUGH ALFALFA PLANTS. (R825549C062)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  1. IRIS Toxicological Review and Summary Documents for Methyl Tert-Butyl Ether (MTBE)

    Science.gov (United States)

    MTBE is a volatile organic chemical used to oxygenate gasoline. Oxygenated gasoline improves the exhaust emissions from gasoline engines. Since 1992 it has been used to comply with the Federal Reformulated Gasoline (begun in 1995) and Wintertime Oxygenated Fuel (begun in 1992) p...

  2. Redox Regulation of the Tumor Suppressor PTEN by Hydrogen Peroxide and Tert-Butyl Hydroperoxide

    Directory of Open Access Journals (Sweden)

    Ying Zhang

    2017-05-01

    Full Text Available Organic peroxides and hydroperoxides are skin tumor promoters. Free radical derivatives from these compounds are presumed to be the prominent mediators of tumor promotion. However, the molecular targets of these species are unknown. Phosphatase and tensin homologs deleted on chromosome 10 (PTEN are tumor suppressors that play important roles in cell growth, proliferation, and cell survival by negative regulation of phosphoinositol-3-kinase/protein kinase B signaling. PTEN is reversibly oxidized in various cells by exogenous and endogenous hydrogen peroxide. Oxidized PTEN is converted back to the reduced form by cellular reducing agents, predominantly by the thioredoxin (Trx system. Here, the role of tert-butyl hydroperoxide (t-BHP in redox regulation of PTEN was analyzed by using cell-based and in vitro assays. Exposure to t-BHP led to oxidation of recombinant PTEN. In contrast to H2O2, PTEN oxidation by t-BHP was irreversible in HeLa cells. However, oxidized PTEN was reduced by exogenous Trx system. Taken together, these results indicate that t-BHP induces PTEN oxidation and inhibits Trx system, which results in irreversible PTEN oxidation in HeLa cells. Collectively, these results suggest a novel mechanism of t-BHP in the promotion of tumorigenesis.

  3. Acute toxicity and cancer risk assessment values for tert-butyl acetate.

    Science.gov (United States)

    Budroe, John D; Brown, Joseph P; Salmon, Andrew G; Salsmon, Andrew G; Marty, Melanie A

    2004-10-01

    tert-Butyl acetate (TBAc) is an industrial chemical with potential uses as a degreaser and in architectural coatings. Limited chronic toxicity data exist for TBAc. However, acute inhalation exposure data are available for TBAc. Additionally, TBAc has been demonstrated to be substantially metabolized to tert-butanol (TBA) in rats, and a positive TBA genotoxicity study suggests that TBA may cause oxidative DNA damage. TBA has been shown to induce tumors in both rats and mice, and the Office of Environmental Health Hazard Assessment has calculated an oral cancer potency factor (CSF) for TBA of 3 x 10(-3)(mg/kg-day)(-1). Therefore, TBAc should be considered to pose a potential cancer risk to humans because of the metabolic conversion to TBA. An acute 1-h reference exposure level of 1 mg/m3 can be calculated from the extrapolated no observed adverse effect level of 50 mg/m3. A CSF of 0.002(mg/kg-day)(-1) can be derived for TBAc, assuming 100% metabolism of TBAc to TBA. An inhalation unit risk value for TBAc of 4 x 10(-7)(microg/m(3))(-1) can then be derived from the CSF value for TBAc by assuming a human breathing rate of 20 m3/day, 70% fractional absorption, and an average human body weight of 70 kg.

  4. (RSS)-[N-Hydroxyethyloxy]-hexafluoroVal-MeLeu-Ala tert-butyl ester.

    Science.gov (United States)

    Eberle, Marcel K; Stoeckli-Evans, Helen; Keese, Reinhart

    2009-10-28

    THE TITLE COMPOUND [SYSTEMATIC NAME: (2S,5S,8R)-tert-butyl 8-(1,1,1,3,3,3-hexafluoropropan-2-yl)-12-hydroxy-5-isobutyl-2,6-dimethyl-4,7-dioxo-10-oxa-3,6,9-triazadodecanoate], C(21)H(36)F(6)N(3)O(6), is a tripeptide crystallizing in the chiral ortho-rhom-bic spacegroup P2(1)2(1)2(1). The absolute configuration (R) of the chiral center in the hexa-fluoro-valine unit is based on the known stereochemistry of MeLeu and Ala (SS). The N-hydroxy-ethyl-oxy substituent of hexa-fluoro-valine is positionally disordered [occupancy ratio 0.543 (9):0.457 (9)]. In the solid state structure there are N-H⋯F and N-H⋯O intra-molecular hydrogen bonds supporting the coiled structure of this tripeptide with the three hydro-phobic substituents on the outside.

  5. Determination of fuel dialkyl ethers and BTEX in water using headspace solid-phase microextraction and gas chromatography-flame ionization detection.

    Science.gov (United States)

    Arambarri, Idoia; Lasa, Maitena; Garcia, Rosa; Millán, Esmeralda

    2004-04-16

    A simple procedure for the determination of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), ethyl butyl ether (EBE), tert-amyl methyl ether (TAME), benzene, toluene, ethylbenzene, and xylenes (BTEX) in water using headspace (HS) solid-phase microextraction (HS-SPME) was developed. The analysis was carried out by gas chromatography (GC) equipped with flame ionization detector (FID) and 100% dimethylpolysiloxane fused capillary column. A 2 Plackett-Burman design for screening and a central composite design (CCD) for optimizing the significant variables were applied. Fiber type, extraction temperature, sodium chloride concentration, and headspace volume were the significant variables. A 65 microm poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) SPME fiber, 10 degrees C, 300 g/l, and 20 ml of headspace (in 40 ml vial) were respectively chosen for the best extraction response. An extraction time of 10 min was enough to extract the ethers and BTEX. The relative standard deviation (R.S.D.) for the procedure varied from 2.6 (benzene) to 8.5% (ethylbenzene). The method detection limits (MDLs) found were from 0.02 (toluene, ethylbenzene, and xylenes) to 1.1 microg/l (MTBE). The optimized method was applied to the analysis of the rivers, marinas and fishing harbors surface waters from Gipuzkoa (North Spain). Three sampling were done in 1 year from June 2002 to June 2003. Toluene was the most detected analyte (in 90% of the samples analyzed), with an average concentration of 0.56 microg/l. MTBE was the only dialkyl ether detected (in 15% of the samples) showing two high levels over 400 microg/l that were related to accidental fuel spill.

  6. Synthesis and Molecular Structure of Chiral (2S, 5S-tert-Butyl 3-Oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate

    Directory of Open Access Journals (Sweden)

    Tetsuji Moriguchi

    2014-01-01

    Full Text Available The title compound (2S, 5S-tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate was synthesized as a chiral cyclic amino acid ester from the corresponding cis- and trans-5-hydroxypipecolic acid ethyl esters via an intramolecular lactonization reaction without using chiral catalyst or enzyme and without separation by chiral column chromatography. The chiral compound was characterized using 1H NMR spectroscopy and high-resolution mass spectrometry. Its exact structure was then determined via single crystal X-ray diffraction analysis of a single crystal obtained after recrystallization of the compound from ethyl acetate/diethyl ether. The crystal was found to be of the orthorhombic space group P212121 (No. 19, noncentrosymmetric, chiral with a=9.6402(10 Å, b=9.7026(10 Å, c=12.2155(12 Å, Dcalc=1.3194 g/cm3, and a Flack parameter of 0.0(5 at 90 K. The compound has a bicyclo[2.2.2]octane structure comprised of lactone and piperidine groups.

  7. Ethyl[tris(3-tert-butyl-5-methylpyrazol-1-yl)hydridoborato]zinc(II).

    Science.gov (United States)

    Kumar, Mukesh; Papish, Elizabeth T; Zeller, Matthias

    2010-08-01

    The X-ray crystal structure of the title compound, [Zn(C(2)H(5))(C(24)H(40)BN(6))], or Tp(tBu,Me)ZnEt [Tp(tBu,Me) is tris(3-tert-butyl-5-methylpyrazolyl)hydridoborate], reveals a distorted tetrahedral geometry around the Zn atom. The Zn center is coordinated by three N atoms of the borate ligand and by one C atom of the ethyl group. The present structure and other tetrahedral Tp zinc alkyl complexes are compared with similar Ttz ligands (Ttz is 1,2,4-triazolylborate), but no major differences in the structures are noted, and it can be assumed that variation of the substitution pattern of Tp or Ttz ligands has little or no influence on the geometry of alkylzinc complexes. Refinement of the structure is complicated by a combination of metric pseudosymmetry and twinning. The metrics of the structure could also be represented in a double-volume C-centered orthorhombic unit cell, and the structure is twinned by one of the orthorhombic symmetry operators not present in the actual structure. The twinning lies on the borderline between pseudomerohedral and nonmerohedral. The data were refined as being nonmerohedrally twinned, pseudomerohedrally twinned and untwinned. None of the approaches yielded results that were unambiguously better than any of the others: the best fit between structural model and data was observed using the nonmerohedral approach which also yielded the best structure quality indicators, but the data set is less than 80% complete due to rejected data. The pseudomerohedral and the untwinned structures are complete, but relatively large residual electron densities that are not close to the metal center are found with values up to three times higher than in the nonmerohedral approach.

  8. Impact of tert-butyl alcohol on crystallization kinetics of gemcitabine hydrochloride in frozen aqueous solutions.

    Science.gov (United States)

    Munjal, Bhushan; Bansal, Arvind K

    2015-01-01

    The effect of tert-butyl alcohol (TBA) on isothermal crystallization kinetics of gemcitabine hydrochloride (GHCl) in frozen aqueous solutions was assessed by cold-stage microscopy. Addition of TBA (0%-5%, w/w) increased the value of Johnson-Mehl-Avrami rate constant (1.3-33.3 h⁻¹) and reduced the Avrami exponent (2.5-1.0). Thermodynamic parameters [enthalpy (ΔH(‡)), entropy (ΔS(‡)), and free energy (ΔG(‡)) of activation], calculated using Arrhenius and Eyring-Polanyi equations, established that TBA (2%, w/w) accelerated GHCl crystallization by reducing its ΔH(‡) (53.9 cf. 96.5 kJ/mol⁻¹) and ΔG(‡) (68.5 cf. 74.9 kJ/mol⁻¹). Further, to explore insights into the effect of TBA on nucleation and crystal growth of GHCl, crystallization kinetics data were deconvolved using Finke-Watzky model. This revealed that addition of TBA decreased ΔH(‡) of nucleation and increased ΔS(‡) of crystal growth, thereby reducing ΔG(‡) of nucleation and crystal growth by 11.7% and 4.2%, respectively. Finkey-Watzky model also predicted a reduction in the crystal size upon TBA addition, which was confirmed by comparing particle size of GHCl lyophilized in the presence and absence of TBA. In conclusion, TBA reduces ΔG(‡) of nucleation and crystal growth in a differential manner, thereby enhancing the crystallization kinetics of GHCl and affecting its morphological features. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  9. 40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

    Science.gov (United States)

    2010-07-01

    ... PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES... chemical substance generically identified as disubstituted benzene ether, polymer with substituted phenol... A of this part apply to this section except as modified by this paragraph. (1) Recordkeeping...

  10. Complexes of tetra-tert-butyl-tetraazaporphine with Al(III) and Zr(IV) cations as fluoride selective ionophores.

    Science.gov (United States)

    Górski, Lukasz; Mroczkiewicz, Monika; Pietrzak, Mariusz; Malinowska, Elzbieta

    2009-02-09

    In this work, complexes of Zr(IV) and Al(III) cations with 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraazaporphine (TAP) were tested as ionophores in plasticized PVC membranes of ion-selective electrodes. It was found that both tested ionophores show enhanced affinity towards fluoride anion. High fluoride selectivity was observed in the presence of anionic or cationic additives in the membrane, which indicates that proposed compounds work according to charged or neutral carrier mechanism, depending on membrane composition and pretreatment. tert-Butyl substituents, present in the structure of tested compounds, were supposed to prevent formation of ionophore dimers within the membrane phase. This process was found to be responsible for some unfavorable potentiometric properties of electrodes based on complexes of Zr(IV) and Al(III) cations with porphyrins (compounds closely related to tetra-tert-butyl-5,10,15,20-tetraazaporphine). As it was shown using spectrophotometrical measurements, Al(III)-TAP was not susceptible to dimerization, while dimer formation was observed for Zr(IV)-TAP. In full agreement with these observations, electrodes with membranes containing Al(III)-TAP responded in near-Nernstian and fast manner towards fluoride anion, while the employment of Zr(IV)-TAP as ionophore resulted in super-Nernstian and sluggish response. Plasticized PVC membranes doped with Al(III)-TAP and 20mol% of lipophilic anionic additives shown remarkable F(-) selectivity, with selectivity coefficients, logK(F-pot.).(Y-), as follows: -4.4 (Y(-)Br(-)), -4.3 (Cl(-)), -4.2 (NO(3)(-)), -3.6 (SCN(-)), -2.9 (ClO(4)(-)).

  11. Scanning thermal lithography of tailored tert-butyl ester protected carboxylic acid functionalized (meth)acrylate polymer platforms.

    Science.gov (United States)

    Duvigneau, Joost; Schönherr, Holger; Vancso, G Julius

    2011-10-01

    In this paper, we report on the development of tailored polymer films for high-resolution atomic force microscopy based scanning thermal lithography (SThL). In particular, full control of surface chemical and topographical structuring was sought. Thin cross-linked films comprising poly(tert-butyl methacrylate) (MA(20)) or poly(tert-butyl acrylate) (A(20)) were prepared via UV initiated free radical polymerization. Thermogravimetric analysis (TGA) and FTIR spectroscopy showed that the heat-induced thermal decomposition of MA(20) by oxidative depolymerization is initially the primary reaction followed by tert-butyl ester thermolysis. By contrast, no significant depolymerization was observed for A(20). For A(20) and MA(20) (at higher temperatures and/or longer reaction times) the thermolysis of the tert-butyl ester liberates isobutylene and yields carboxylic acid groups, which react further intramolecularly to cyclic anhydrides. The values of the apparent activation energies (E(a)) for the thermolysis were calculated to be 125 ± 13 kJ mol(-1) and 116 ± 7 kJ mol(-1) for MA(20) and A(20), respectively. Both MA(20) and A(20) films showed improved thermomechanical stability during SThL compared to non cross-linked films. Carboxylic acid functionalized lines written by SThL in A(20) films had a typically ~10 times smaller width compared to those written in MA(20) films regardless of the tip radius of the heated probe and did not show any evidence for thermochemically or thermomechanically induced modification of film topography. These observations and the E(a) of 45 ± 3 kJ mol(-1) for groove formation in MA(20) estimated from the observed volume loss are attributed to oxidative thermal depolymerization during SThL of MA(20) films, which is considered to be the dominant reaction mechanism for MA(20). The smallest line width values obtained for MA(20) and A(20) films with SThL were 83 ± 7 nm and 21 ± 2 nm, whereas the depth of the lines was below 1 nm, respectively.

  12. Characterizing Effects of Nitric Oxide Sterilization on tert-Butyl Acrylate Shape Memory Polymers

    Science.gov (United States)

    Phillippi, Ben

    As research into the potential uses of shape memory polymers (SMPs) as implantable medical devices continues to grow and expand, so does the need for an accurate and reliable sterilization mechanism. The ability of an SMP to precisely undergo a programmed shape change will define its ability to accomplish a therapeutic task. To ensure proper execution of the in vivo shape change, the sterilization process must not negatively affect the shape memory behavior of the material. To address this need, this thesis investigates the effectiveness of a benchtop nitric oxide (NOx) sterilization process and the extent to which the process affects the shape memory behavior of a well-studied tert-Butyl Acrylate (tBA) SMP. Quantifying the effects on shape memory behavior was performed using a two-tiered analysis. A two-tiered study design was used to determine if the sterilization process induced any premature shape recovery and to identify any effects that NOx has on the overall shape memory behavior of the foams. Determining the effectiveness of the NOx system--specially, whether the treated samples are more sterile/less contaminated than untreated--was also performed with a two-tiered analysis. In this case, the two-tiered analysis was employed to have a secondary check for contamination. To elaborate, all of the samples that were deemed not contaminated from the initial test were put through a second sterility test to check for contamination a second time. The results of these tests indicated the NOx system is an effective sterilization mechanism and the current protocol does not negatively impact the shape memory behavior of the tBA SMP. The samples held their compressed shape throughout the entirety of the sterilization process. Additionally, there were no observable impacts on the shape memory behavior induced by NOx. Lastly, the treated samples demonstrated lower contamination than the untreated. This thesis demonstrates the effectiveness of NOx as a laboratory scale

  13. Formation of Germa-ketenimine on the Ge(100) Surface by Adsorption of tert-Butyl Isocyanide.

    Science.gov (United States)

    Shong, Bonggeun; Yoo, Jong Suk; Sandoval, Tania E; Bent, Stacey F

    2017-06-28

    Reactions of the (100) surfaces of Ge and Si with organic molecules have been generally understood within the concept of "dimers" formed by the 2 × 1 surface reconstruction. In this work, the adsorption of tert-butyl isocyanide on the Ge(100)-2 × 1 surface at large exposures is investigated under ultrahigh vacuum conditions. A combination of infrared spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed desorption experiments along with dispersion-corrected density functional theory calculations is used to determine the surface products. Upon adsorption of a dense monolayer of tert-butyl isocyanide, a product whose structure resembles a germa-ketenimine (N=C=Ge) with σ donation toward and π back-donation from the Ge(100) surface appears. Formation of this structure involves divalent-type surface Ge atoms that arise from cleavage of the Ge(100)-2 × 1 surface dimers. Our results reveal an unprecedented class of reactions of organic molecules at the Ge(100) surface.

  14. Electrochemical nucleophilic synthesis of di-tert-butyl-(4-[18F]fluoro-1,2-phenylene)-dicarbonate.

    Science.gov (United States)

    He, Qinggang; Wang, Ying; Alfeazi, Ines; Sadeghi, Saman

    2014-09-01

    An electrochemical method with the ability to conduct (18)F-fluorination of aromatic molecules through direct nucleophilic fluorination of cationic intermediates is presented in this paper. The reaction was performed on a remote-controlled automatic platform. Nucleophilic electrochemical fluorination of tert-butyloxycarbonyl (Boc) protected catechol, an intermediate model molecule for the positron emission tomography (PET) probe (3,4-dihydroxy-6-[(18)F]fluoro-L-phenylalanine), was performed. Fluorination was achieved under potentiostatic anodic oxidation in acetonitrile containing Et3N·3HF and other supporting electrolytes. Radiofluorination efficiency was influenced by a number of variables, including the concentration of the precursor, concentration of Et3N·3HF, type of supporting electrolyte, temperature and time, as well as applied potentials. Radio-fluorination efficiency of 10.4±0.6% (n=4) and specific activity of up to 43GBq/mmol was obtained after 1h electrolysis of 0.1M of 4-tert-butyl-diboc-catechol in the acetonitrile solution of Et3N·3HF (0.033M) and NBu4PF6 (0.05M). Density functional theory (DFT) was employed to explain the tert-butyl functional group facilitation of electrochemical oxidation and subsequent fluorination. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Synthesis of tert-butyl (substituted benzamido)phenylcarbamate derivatives: anti-inflammatory activity and docking studies.

    Science.gov (United States)

    Bhookya, Shankar; Pochampally, Jalapathi; Valeru, Anil; Sunitha, Vianala; Balabadra, Saikrishna; Manga, Vijjulatha; Kudle, Karunakar Rao

    2017-07-01

    A series of new tert-butyl 2-(substituted benzamido) phenylcarbamate (4a-4j) were synthesized by the condensation of tert-butyl 2-amino phenylcarbamate (3) with various substituted carboxylic acid in the presence of EDCI and HOBt as coupling reagent, obtain in excellent yields. The structures of all newly synthesized compounds were characterized spectroscopically and evaluated for in vivo anti-inflammatory activity compared to the standard drug, indomethacin, by using the carrageenan-induced rat paw edema protocol. Most of the compounds exhibited a promising anti-inflammatory activity within 9 to 12 h, the percentage of inhibition values ranging from 54.239 to 39.021%. The results revealed that the compounds 4i and 4a exhibited better or equivalent anti-inflammatory activity with the percentage of inhibition of 54.239 and 54.130%, respectively, which was comparable to standard drug. In addition to experimental results, in silico docking studies was used as a tool to verify and expand the experimental outcomes.

  16. Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111).

    Science.gov (United States)

    Schuler, A; Greif, M; Seitsonen, A P; Mette, G; Castiglioni, L; Osterwalder, J; Hengsberger, M

    2017-01-01

    Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3',5,5'-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111) in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

  17. Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111

    Directory of Open Access Journals (Sweden)

    A. Schuler

    2017-01-01

    Full Text Available Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3′,5,5′-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111 in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

  18. Ferric chloride-catalyzed reaction of [60]fullerene with tert-butyl N-substituted carbamates: synthesis of oxazolidino[4,5:1,2][60]fullerenes.

    Science.gov (United States)

    You, Xun; Wang, Guan-Wu

    2014-01-03

    The rare oxazolidinofullerenes have been prepared by the ferric chloride-catalyzed reaction of [60]fullerene with various tert-butyl N-substituted carbamates via t-Bu-O bond cleavage and heteroannulation under mild conditions. A possible mechanism for the formation of oxazolidinofullerenes is proposed.

  19. Intra-arterial tert-Butyl-hydroperoxide infusion induces an exacerbated sensory response in the rat hind limb and is associated with an impaired tissue oxygen uptake.

    NARCIS (Netherlands)

    Tan, E.C.T.H.; Goor, H. van; Bahrami, S.; Kozlov, A.V.; Leixnering, M.; Redl, H.; Goris, R.J.A.

    2011-01-01

    The objective of this study was to investigate oxidative stress and oxygen extraction mechanisms in an animal model of continuous intra-arterial infusion of a free radical donor and in an in vitro model using isolated mitochondria. tert-Butyl-hydroperoxide (tert-BuOOH, 25 mM) was infused for 24 h in

  20. Interfacial Reactions in Confinement: Kinetics and Temperature Dependence of the Surface Hydrolysis of Polystyrene-block-poly(tert-butyl acrylate) Thin Films

    NARCIS (Netherlands)

    Feng, C.L.; Vancso, Gyula J.; Schönherr, Holger

    2005-01-01

    The effect of confinement on the kinetics of the surface hydrolysis of polystyrene-block-poly(tert-butyl acrylate) (PSn-b-PtBAm) thin films on oxidized silicon substrates in 3 M aqueous hydrochloric acid was systematically investigated. As shown by X-ray photoelectron spectroscopy (XPS) and contact

  1. Tailored Interfaces for Biosensors and Cell-Surface Interaction Studies via Activation and Derivatization of Polystyrene-block-poly(tert-butyl acrylate) Thin Films

    NARCIS (Netherlands)

    Feng, C.L.; Embrechts, A.; Bredebusch, Ilona; Bouma, Anita; Schnekenburger, Jürgen; Garcia Parajo, M.F.; Domschke, Wolfram; Vancso, Gyula J.; Schönherr, Holger

    2007-01-01

    Thin spin-coated films of polystyrene-block-poly(tert-butyl acrylate) (PS690-b-PtBA1210) on various substrates are introduced as versatile, robust reactive platform for the immobilization of (bio)molecules for the fabrication of tailored biointerfaces. The films are characterized by high stability

  2. Biological monitoring of exposure to low concentrations of benzene in workers at a metallurgical coke production plant: new insights into S-phenylmercapturic acid and urinary benzene.

    Science.gov (United States)

    Lovreglio, Piero; De Palma, Giuseppe; Barbieri, Anna; Andreoli, Roberta; Drago, Ignazio; Greco, Luciano; Gallo, Elisabetta; Diomede, Laura; Scaramuzzo, Pietro; Ricossa, Maria Cristina; Fostinelli, Jacopo; Apostoli, Pietro; Soleo, Leonardo

    2018-02-01

    Urinary S-phenylmercapturic acid (SPMA) and benzene (U-Ben) are usually measured at the end of the work shift (ES), although their kinetic of elimination is not clearly known. To investigate SPMA and U-Ben elimination 16 h after the ES, in 93 coke production workers exposed to low benzene concentrations. Airborne benzene (A-Ben) was measured by passive samplings, while SPMA, U-Ben, methyl-tert-butyl ether (U-MTBE), cotinine (U-Cot) and creatinine were determined on urine samples collected at ES and before the beginning of the next work shift (next BS). Median A-Ben concentrations were 17.2 µg/m 3 in the personal and 34.7 µg/m 3 in the stationary samplings. SPMA was always detectable, whereas U-Ben was below the limit of quantification in 26.7% of the ES and 35.6% of the next BS samples, and U-MTBE in more than the 80.0% of the samples. At both the sampling times, SPMA and U-Ben showed a positive dependence on personal A-Ben, as well as on creatinine and U-Cot values. SPMA and U-Ben at the next BS were dependent on the exposure to low benzene concentrations suffered in the previous work shift, prompting a reconsideration of the urine sampling time recommended by the American Conference Governmental Industrial Hygienists (ACGIH).

  3. Ambient air benzene at background sites in China's most developed coastal regions: exposure levels, source implications and health risks.

    Science.gov (United States)

    Zhang, Zhou; Wang, Xinming; Zhang, Yanli; Lü, Sujun; Huang, Zhonghui; Huang, Xinyu; Wang, Yuesi

    2015-04-01

    Benzene is a known human carcinogen causing leukemia, yet ambient air quality objectives for benzene are not available in China. The ambient benzene levels at four background sites in China's most developed coastal regions were measured from March 2012 to February 2013. The sites are: SYNECP, in the Northeast China Plain (NECP); YCNCP, in the North China Plain (NCP); THYRD, in the Yangtze River Delta (YRD) and DHPRD, in the Pearl River Delta (PRD). It was found that the mean annual benzene levels (578-1297 ppt) at the background sites were alarmingly higher, especially when compared to those of 60-480 pptv monitored in 28 cities in the United States. Wintertime benzene levels were significantly elevated at both sites (SYNECP and YCNCP) in northern China due to heating with coal/biofuels. Even at these background sites, the lifetime cancer risks of benzene (1.7-3.7E-05) all exceeded 1E-06 set by USEPA as acceptable for adults. At both sites in northern China, good correlations between benzene and CO or chloromethane, together with much lower toluene/benzene (T/B) ratios, suggested that benzene was largely related to coal combustion and biomass/biofuel burning. At the DHPRD site in the PRD, benzene revealed a highly significant correlation with methyl tert-butyl ether (MTBE), indicating that its source was predominantly from vehicle emissions. At the THYRD site in the YRD, higher T/B ratios and correlations between benzene and tetrachloroethylene, or MTBE, implied that benzene levels were probably affected by both traffic-related and industrial emissions. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Structure-Dependent 4-Tert-Butyl Pyridine-Induced Band Bending at TiO2 Surfaces

    Directory of Open Access Journals (Sweden)

    Mats Göthelid

    2011-01-01

    Full Text Available The role of 4-tert butyl pyridine (4TBP adsorption on TiO2 surface band bending has been studied using photoelectron spectroscopy. Surface oxygen vacancies pin the Fermi level near the conduction band edge on rutile (110. 4TBP preferentially adsorbs in those vacancies and shift the Fermi level to lower binding energy in the band gap. This is done by transferring vacancy excess charge into the empty π∗ orbital in the pyridine ring. The anatase (100 surface contains much less oxygen vacancies although the surface is much rougher than the rutile (110. 4TBP adsorption does not have any significant effect on the surface band bending. Thus the positive role associated with 4TBP addition to solar cell electrolytes is suggested to protection against adsorption of other electrolyte components such as Li and I.

  5. Irreversible hyperoxidation of peroxiredoxin 2 is caused by tert-butyl hydroperoxide in human red blood cells

    Directory of Open Access Journals (Sweden)

    Y.I. Ishida

    2014-01-01

    Full Text Available Peroxiredoxin 2 (Prx2 is the third most abundant protein in red blood cells (RBCs. In this study, we have succeeded in implementing the rapid and simultaneous detection of the hyperoxidized (Prx2-SO2/3 and reduced (Prx2-SH forms of Prx2 in human RBCs using reverse phase high-performance liquid chromatography. The detection of a peak corresponding to Prx2-SO2/3 was clearly observed following treatment of tert-butyl hydroperoxide (t-BHP, but not H2O2, and was found to be dose-dependent. The identity of the peak was confirmed as Prx2 by immunoblotting and mass spectrometry analysis. Our results suggest that t-BHP hyperoxidizes cysteine residues in Prx2 more readily than H2O2, and that accumulation of hyperoxidized Prx2 might reflect disruption of redox homeostasis in RBCs.

  6. (1S,3S,4S-tert-Butyl N-[1-benzyl-3-hydroxy-5-phenyl-4-(picolinamidopentyl]carbamate

    Directory of Open Access Journals (Sweden)

    Jian-Feng Zheng

    2008-07-01

    Full Text Available The title compound, C29H35N3O4, was obtained by the reaction of (2S,4S,5S-tert-butyl N-(4-amino-1-benzyl-3-hydroxy-5-phenylpentylcarbamate and picolinic acid using oxalyl chloride as a chlorinating reagent to activate the carboxyl group. In the crystal structure there are two molecules in the asymmetric unit, which are aligned edge-to-face. In one molecule, the pyridyl ring forms a dihedral angle of 22.0 (1° with the phenyl ring of the terminal benzyl group and 14.3 (1° with the other phenyl ring; in the other molecule, the corresponding angles are 12.1 (1 and 10.6 (1°, respectively. The packing is stabilized by intermolecular hydrogen bonds and C—H...π interactions.

  7. 7-[(3,5-Di-tert-butyl-2-hydroxybenzylideneamino]-4-methyl-2H-chromen-2-one

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    Orhan Büyükgüngör

    2010-10-01

    Full Text Available The title compound, C25H29NO3, is a Schiff base derivative of coumarin 120. There are two structurally similar but crystallographically independent molecules in the asymmetric unit. Both molecules exist in E configurations with respect to the C=N double bonds. The dihedral angles between the coumarin and 3,5-di-tert-butyl-2-hydroxybenzylidene ring planes are 4.62 (7 and 14.62 (7° for the two molecules. Intramolecular O—H...N hydrogen bonding involving the O—H groups and the azomethine N atoms generate S(6 rings. In the crystal structure, independent molecules are linked by C—H...π interactions, with groups of four molecules stacked along the c axis.

  8. Fate of MTBE relative to benzene in a gasoline-contaminated aquifer (1993-98):

    Science.gov (United States)

    Landmeyer, James E.; Chapelle, Francis H.; Bradley, Paul M.; Pankow, James F.; Church, Clinton D.; Tratnyek, Paul G.

    1998-01-01

    Methyl tert-butyl ether (MTBE) and benzene have been measured since 1993 in a shallow, sandy aquifer contaminated by a mid-1980s release of gasoline containing fuel oxygenates. In wells downgradient of the release area, MTBK was detected before benzene, reflecting a chromatographic-like separation of these compounds in the direction of ground water flow. Higher concentrations of MTBE and benzene were measured in the deeper sampling ports of multilevel sampling wells located near the release area, and also up to 10 feet (3 m) below the water table surface in nested wells located farther from the release area. This distribution of higher concentrations at depth is caused by recharge events that deflect originally horizontal ground water flowlines. In the laboratory, microcosms containing aquifer material incubated with uniformly labeled 14C-MTBE under aerobic and anaerobic. Fe(III)-reducing conditions indicated a low but measurable biodegradation potential (MTBE transformation intermediate, was detected in MTBE-contaminated wells, but TBA was also measured in unsaturated release area sediments. This suggests that TBA may have been present in the original fuel spilled and does not necessarily reflect microbial degradation of MTBE. Combined, these data suggest that milligram per liter to microgram per liter decreases in MTBE concentrations relative to benzene are caused by the natural attenuation processes of dilution and dispersion with less-contaminated ground water in the direction of flow rather than biodegradation at this point source gasoline release site.

  9. Anti-inflammatory activity of the artificial antioxidants 2-tert-butyl-4-methoxyphenol (BHA), 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4,6-tri-tert-butylphenol (TBP), and their various combinations.

    Science.gov (United States)

    Murakami, Yukio; Kawata, Akifumi; Katayama, Tadashi; Fujisawa, Seiichiro

    2015-01-01

    The artificial complex phenols, 2-tert-butyl-4-methoxyphenol (BHA), 2,6-di-tert-butyl-4-methylphenol (BHT) and 2,4,6-tri-tert-butylphenol (TBP) exert efficient antioxidant activity; however, they are considerable toxic and potentially tumor-promoting. These phenols, particularly in combinations, have enhanced antioxidant activity due to synergistic interactions and produce bioactive intermediates such as quinone methide. We investigated the anti-inflammatory activity of BHA, BHT and TBP, and combinations of BHT/BHA (in molar ratios of 1:1, 1:2, 1:3 and 2:1), BHT/TBP (1:1), and BHA/TBP (1:1), using gene-expression systems for cyclooxygenase-2 (Cox2) and tumor necrosis facto-alpha (Tnfa) in RAW264.7 cells. The inhibitory effects of BHA, BHT and TBP on expression of Cox2 and Tnfa genes upon stimulation with Escherichia coli lipopolysaccharide (LPS) or Porphyomonas gingivalis (Pg) fimbriae were determined using real-time polymerase chain reaction. The inhibitory effect on expression of Cox2 and Tnfa genes upon stimulation with LPS and fimbriae was greatly enhanced by the combination of two antioxidants (molar ratio 1:1), BHT/BHA. In addition, that of the Cox2 gene, but not of Tnfa gene was slightly enhanced by a combination of equimolar BHT/TBP and BHA/TBP. None of the antioxidants alone exerted any anti-inflammatory activity upon stimulation with LPS, but a slight anti-inflammatory activity was observed upon stimulation with Pg fimbriae. The inhibitory effect of the BHT/BHA combination on expression of Cox2 mRNA upon stimulation with LPS was investigated at afferent molar ratios, and a molar ratio of 1:1 was found to have considerably less effect than a molar ratio of 1:2 or 2:1. The 1:3 combination had no effect. The combination of BHT and BHA at a molar ratio of 0.5-2 exerts potent anti-inflammatory activity. This anti-inflammatory activity on the generation of inflammatory mediators in LPS-activated RAW264.7 cells may be attributable to complex synergistic

  10. Diafenthiuron: 1-tert-butyl-3-(2,6-diisopropyl-4-phenoxyphenylthiourea

    Directory of Open Access Journals (Sweden)

    Youngeun Jeon

    2014-07-01

    Full Text Available The title compound, C23H32N2OS, is a thiourea-based insecticide. The dihedral angle between the phenyl ring and the diisopropyl benzene ring plane is 73.18 (6°, while that between the plane of the thiourea group and the diisopropyl benzene ring is 86.00 (5°. Disorder was modelled for the S atom and the two methyl C atoms of the isopropyl group over two sets of sites with an occupancy ratio of 0.742 (4:0.258 (4. In the crystal, N—H...S hydrogen bonds link adjacent molecules, forming R22(8 inversion dimers that pack into chains along the b-axis direction.

  11. INFLUENCE OF THE ISOBUTENE METHANOL RATIO AND OF THE METHYL TERT-BUTYL ETHER CONTENT ON THE REACTION-RATE OF THE SYNTHESIS OF METHYL TERT-BUTYL ETHER

    NARCIS (Netherlands)

    PANNEMAN, HJ; BEENACKERS, AACM

    1995-01-01

    The forward reaction rate constant of the MtBE synthesis was determined for different reaction mixture compositions. The forward rate constant decreases continuously with increasing isobutene/methanol ratio, while an increase in reaction rate constant is observed with an increasing amount of MtBE in

  12. tert-Butyl 3-[2,2-bis-(ethoxy-carbon-yl)vin-yl]-2-bromo-methyl-1H-indole-1-carboxyl-ate.

    Science.gov (United States)

    Thenmozhi, M; Kavitha, T; Dhayalan, V; Mohanakrishnan, A K; Ponnuswamy, M N

    2009-10-17

    In the title compound, C(22)H(26)BrNO(6), the indole ring system is planar [maximum deviation 0.029 (2) Å]. The tert-butyl bound carboxyl-ate group forms a dihedral angle of 17.54 (8)° with the indole ring system. In the crystal, mol-ecules are linked into centrosymmetric R(2) (2)(10) dimers by paired C-H⋯O hydrogen bonds.

  13. Preparation and characterization of Pd doped ceria-ZnO nanocomposite catalyst for methyl tert-butyl ether (MTBE) photodegradation.

    Science.gov (United States)

    Seddigi, Zaki S; Bumajdad, Ali; Ansari, Shahid P; Ahmed, Saleh A; Danish, Ekram Y; Yarkandi, Naeema H; Ahmed, Shakeel

    2014-01-15

    A series of binary oxide catalysts (ceria-ZnO) were prepared and doped with different amounts of palladium in the range of 0.5%-1.5%. The prepared catalysts were characterized by SEM, TEM, XRD and XPS, as well as by N2 sorptiometry study. The XPS results confirmed the structure of the Pd CeO2-x-ZnO. The photocatalytic activity of these catalysts was evaluated for degradation of MTBE in water. These photocatalyst efficiently degrade a 100ppm aqueous solution of MTBE upon UV irradiation for 5h in the presence of 100mg of each of these photocatalysts. The removal of 99.6% of the MTBE was achieved with the ceria-ZnO catalyst doped with 1% Pd. In addition to the Pd loading, the N2 sorptiometry study introduced other factors that might affect the catalytic efficiency is the catalyst average pore sizes. The photoreaction was determined to be a first order reaction. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Kinetics and Photodegradation Study of Aqueous Methyl tert-Butyl Ether Using Zinc Oxide: The Effect of Particle Size

    Directory of Open Access Journals (Sweden)

    Zaki S. Seddigi

    2013-01-01

    Full Text Available Zinc oxide of different average particle sizes 25 nm, 59 nm, and 421 nm as applied in the photodegradation of MTBE. This study was carried out in a batch photoreactor having a high pressure mercury lamp. Zinc oxide of particle size of 421 nm was found to be the most effective in degrading MTBE in an aqueous solution. On using this type of ZnO in a solution of 100 ppm MTBE, the concentration of MTBE has decreased to 5.1 ppm after a period of five hours. The kinetics of the photocatalytic degradation of MTBE was found to be a first order reaction.

  15. Preparation and characterization of Pd doped ceria–ZnO nanocomposite catalyst for methyl tert-butyl ether (MTBE) photodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Seddigi, Zaki S. [Chemistry Department, Umm Al-Qura University, Makkah (Saudi Arabia); Bumajdad, Ali [Chemistry Department, Faculty of Science, Kuwait University (Kuwait); Ansari, Shahid P. [Chemistry Department, Umm Al-Qura University, Makkah (Saudi Arabia); Ahmed, Saleh A., E-mail: saleh_63@hotmail.com [Chemistry Department, Umm Al-Qura University, Makkah (Saudi Arabia); Danish, Ekram Y. [Chemistry Department, King Abdulaziz University, Jeddah (Saudi Arabia); Yarkandi, Naeema H. [Chemistry Department, Umm Al-Qura University, Makkah (Saudi Arabia); Ahmed, Shakeel [Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

    2014-01-15

    Highlights: • Novel Pd supported ceria–ZnO photocatalysts were prepared with different amounts of palladium. • The photocatalytic activity of these catalysts was evaluated for degradation of MTBE in water. • Near complete removal of MTBE was achieved using 1% Pd doped ceria–ZnO catalyst and UV irradiation. • Highest rate constant was obtained in case of 1% Pd doped ceria–ZnO catalyst. • Shape and size of pores are important factors for high photoactivity of catalyst. -- Abstract: A series of binary oxide catalysts (ceria–ZnO) were prepared and doped with different amounts of palladium in the range of 0.5%–1.5%. The prepared catalysts were characterized by SEM, TEM, XRD and XPS, as well as by N{sub 2} sorptiometry study. The XPS results confirmed the structure of the Pd CeO{sub 2−x}-ZnO. The photocatalytic activity of these catalysts was evaluated for degradation of MTBE in water. These photocatalyst efficiently degrade a 100 ppm aqueous solution of MTBE upon UV irradiation for 5 h in the presence of 100 mg of each of these photocatalysts. The removal of 99.6% of the MTBE was achieved with the ceria–ZnO catalyst doped with 1% Pd. In addition to the Pd loading, the N{sub 2} sorptiometry study introduced other factors that might affect the catalytic efficiency is the catalyst average pore sizes. The photoreaction was determined to be a first order reaction.

  16. EXPERIMENTAL MEASUREMENT OF THE RATE OF METHYL TERT-BUTYL ETHER HYDROLYSIS IN SUB- AND SUPERCRITICAL WATER. (R826738)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  17. Vibrio fischeri and Escherichia coli adhesion tendencies towards photolithographically modified nanosmooth poly (tert-butyl methacrylate polymer surfaces

    Directory of Open Access Journals (Sweden)

    Elena P Ivanova

    2008-09-01

    Full Text Available Elena P Ivanova1, Natasa Mitik-Dineva1, Radu C Mocanasu1, Sarah Murphy1, James Wang2, Grant van Riessen3, Russell J Crawford11Faculty Life and Social Sciences; 2IRIS, Swinburne University of Technology, Hawthorn, Victoria, Australia; 3Centre for Materials and Surface Science, La Trobe University, Melbourne, Victoria, AustraliaAbstract: This study reports the adhesion behavior of two bacterial species, Vibrio fischeri and Escherichia coli, to the photoresistant poly(tert-butyl methacrylate (P(tBMA polymer surface. The data has demonstrated that ultraviolet irradiation of P(tBMA was able to provide control over bacterial adhesion tendencies. Following photolithography, several of the surface characteristics of P(tBMA were found to be altered. Atomic force microscopy analysis indicated that photolithographically modified P(tBMA (henceforth termed ‘modified polymer’ appeared as a ‘nanosmooth’ surface with an average surface roughness of 1.6 nm. Although confocal laser scanning microscopy and scanning electron microscopy analysis clearly demonstrated that V. fischeri and E. coli presented largely different patterns of attachment in order to adhere to the same surfaces, both species exhibited a greater adhesion propensity towards the ‘nanosmooth’ surface. The adhesion of both species to the modified polymer surface appeared to be facilitated by an elevated production of extracellular polymeric substances when in contact with the substrate.Keywords: poly(tert-butylmethacrylate polymeric surfaces, surface nanotopography, bacterial attachment, extracellular polymeric substances

  18. Protective Effects of Alkaloid Compounds from Nelumbinis Plumula on tert-Butyl Hydroperoxide-Induced Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Ze-Bin Guo

    2013-08-01

    Full Text Available This study was conducted to investigate the effect of Nelumbinis Plumula total alkaloid (NPA and its main alkaloid components on oxidative stress induced by tert-butyl hydroperoxide (t-BHP in the human hepatocellular HepG2 cell line. According to HPLC analysis, several major alkaloid compounds such as liensinine, isoliensinine and neferine were present in NPA. The cytotoxic effects in 0.55 mM t-BHP-induced HepG2 cells were significantly inhibited by NPA and the major compound in NPA, neferine, showed the strongest activities. The protective effect of neferine against oxidative stress induced by t-BHP may be associated with decreased ROS formation, TBARS generation, LDH release and increased GSH levels, suggesting their involvement of the cytoprotective on oxidative stress. The effects were comparable with quercetin, which was used as positive control. Overall, total alkaloid and alkaloid compounds from Nelumbinis Plumula displayed a significant cytoprotective effect against oxidative stress. Further study is needed to elucidate the relationship between the chemical structures of the components in NPA and their protective effect on oxidative stress.

  19. 2,4-Di-tert-butyl phenol as the antifungal, antioxidant bioactive purified from a newly isolated Lactococcus sp.

    Science.gov (United States)

    Varsha, Kontham Kulangara; Devendra, Leena; Shilpa, Ganesan; Priya, Sulochana; Pandey, Ashok; Nampoothiri, Kesavan Madhavan

    2015-10-15

    The volatile organic compound 2,4-di-tert-butyl phenol (2,4 DTBP) was purified from the cell free supernatant of a newly isolated Lactococcus sp. by solvent extraction and chromatographic techniques. Molecular characterization of the compound by ESI-MS, (1)H NMR and FTIR analysis revealed the structure, C14H22O. Fungicidal activity was demonstrated against Aspergillus niger, Fusarium oxysporum and Penicillium chrysogenum by disc diffusion assay. Among the cell lines tested for cytotoxicity of this compound (normal cell line H9c2 and cancer cell lines HeLa and MCF-7), a remarkable cytotoxicity against HeLa cells with an IC50 value of 10 μg/mL was shown. A biocontrol experiment with 2,4 DTBP supplemented fraction prevented growth of the abovementioned fungi on wheat grains. The study further strengthens the case for development of biopreservatives and dietary antioxidants from lactic acid bacteria for food applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Crystal structure of trans-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyloxamide methanol monosolvate

    Directory of Open Access Journals (Sweden)

    Miguel-Ángel Velázquez-Carmona

    2016-07-01

    Full Text Available The here crystallized oxamide was previously characterized as an unsolvated species [Jímenez-Pérez et al. (2000. J. Organomet. Chem. 614–615, 283–293], and is now reported with methanol as a solvent of crystallization, C30H44N2O4·CH3OH, in a different space group. The introduction of the solvent influences neither the molecular symmetry of the oxamide, which remains centrosymmetric, nor the molecular conformation. However, the unsolvated molecule crystallized as an ordered system, while many parts of the solvated crystal are disordered. The hydroxy group in the oxamide is disordered over two chemically equivalent positions, with occupancies 0.696 (4:0.304 (4; one tert-butyl group is disordered by rotation about the C—C bond, and was modelled with three sites for each methyl group, each one with occupancy 1/3. Finally, the methanol solvent, which lies on a twofold axis, is disordered by symmetry. The disorder affecting hydroxy groups and the solvent of crystallization allows the formation of numerous supramolecular motifs using four hydrogen bonds, with N—H and O—H groups as donors and the oxamide and methanol molecule as acceptors.

  1. Bis(formylphenolatocobalt(II-Mediated Alternating Radical Copolymerization of tert-Butyl 2-Trifluoromethylacrylate with Vinyl Acetate

    Directory of Open Access Journals (Sweden)

    Sanjib Banerjee

    2017-12-01

    Full Text Available The organometallic-mediated radical polymerization (OMRP of vinyl acetate (VAc and its OMR copolymerization (OMRcoP with tert-butyl 2-trifluoromethylacrylate (MAF-TBE mediated by Co(SAL2 (SAL = 2-formylphenolato or deprotonated salicylaldehyde produced relatively well-defined PVAc and poly(VAc-alt-MAF-TBE copolymers at moderate temperature (<40 °C in bulk. The resulting alternating copolymer was characterized by 1H-, 13C- and 19F-nuclear magnetic resonance (NMR spectroscopies, and by size exclusion chromatography. The linear first-order kinetic plot, the linear evolutions of the molar mass with total monomer conversion, and the relatively low dispersity (Đ~1.55 of the resulting copolymers suggest that this cobalt complex provides some degree of control over the copolymerization of VAc and MAF-TBE. Compared to the previously investigated cobalt complex OMRP mediators having a fully oxygen-based first coordination sphere, this study emphasizes a few peculiarities of Co(SAL2: a lower ability to trap radical chains as compared to Co(acac2 and the absence of catalytic chain transfer reactions, which dominates polymerizations carried in the presence of 9-oxyphenalenone cobalt derivative.

  2. Mechanism-based inactivation of cytochromes P450 2E1 and 2E1 T303A by tert-butyl acetylenes: characterization of reactive intermediate adducts to the heme and apoprotein.

    Science.gov (United States)

    Blobaum, Anna L; Kent, Ute M; Alworth, William L; Hollenberg, Paul F

    2002-12-01

    The kinetics for the inactivation of cytochrome P450 2E1 and the mutant P450 2E1 T303A by tert-butyl acetylene (tBA) and tert-butyl 1-methyl-2-propynyl ether (tBMP) were investigated. The two acetylenes inactivated the 7-ethoxy-4-(trifluoromethyl)coumarin (7-EFC) O-deethylation activity of purified rabbit P450s 2E1 and 2E1 T303A in a reconstituted system in a time-, concentration-, and NADPH-dependent manner. The K(I) values for the inactivation of P450s 2E1 and 2E1 T303A by tBA were 1.0 and 2.0 mM, the k(inact) values were 0.20 and 0.38 min(-)(1), and the t(1/2) values were 3.5 and 1.8 min, respectively. The K(I) values for the tBMP-inactivated P450s were 0.1 and 1.0 mM, the k(inact) values were 0.12 and 0.07 min(-)(1), and the t(1/)(2) values were 5.9 and 10.2 min, respectively. Losses in enzyme activity occurred with concurrent losses in the P450 CO spectrum and P450 heme, which were accompanied by the appearance of two different tBA- or tBMP-modified heme products in each inactivated sample. LC-MS analysis of the adducts showed masses of 661 or 705 Da, consistent with the mass of an iron-depleted heme plus the masses of a tBA or tBMP reactive intermediate and one oxygen atom, respectively. Only the tBA-inactivated P450 2E1 revealed a tBA-adducted apoprotein with an increase in mass of 99 Da, corresponding to the mass of tBA plus one oxygen atom. Surprisingly, the inactivation, CO spectral and heme loss, and heme adduct formation of the tBA-inactivated T303A mutant were completely reversible after dialysis. In addition, metabolism of para-nitrophenol was not compromised by the tBA-inactivated T303A mutant. Therefore, our studies on the inactivation of P450s 2E1 and 2E1 T303A by tBA and tBMP suggest the existence of three distinct mechanisms for inactivation, among which includes a novel, reversible heme alkylation that has not been previously described with P450 enzymes.

  3. Long term studies on the anaerobic biodegradability of MTBE and other gasoline ethers

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2009-01-01

    to investigate the anaerobic biodegradability of MTBE and other gasoline ethers. Inoculums collected from various environments were used, along with different electron acceptors. Only one set of the batch experiments showed a 30-60% conversion of MTBE to tert-butyl alcohol under Fe(III)-reducing conditions...

  4. The Chemistry and Flow Dynamics of Molecular Biological Tools Used to Confirm In Situ Bioremediation of Benzene, TBA, and MTBE

    Science.gov (United States)

    North, K. P.; Mackay, D. M.; Scow, K. M.

    2010-12-01

    In situ bioremediation has typically been confirmed by collecting sediment and groundwater samples to directly demonstrate a degradation process in a laboratory microcosm. However, recent advances in molecular biological tools present options for demonstrating degradation processes with field-based tools that are less time-consuming. We have been investigating the capability of some of these molecular biological tools to evaluate in situ biodegradation of tert-butyl alcohol (TBA), methyl tert-butyl ether (MTBE), and benzene at two field sites in California. At both sites, we have deployed Bio-Traps® (“traps”), made of Bio-Sep® beads in slotted PVC pipe, which provide ideal environments for microbial colonization. Stable Isotope Probing can be accomplished by sorbing the13C-labeled organic contaminant of concern onto Bio-Sep® beads (“baiting”); incorporation of 13C into the biomass collected by the trap would indicate that the microbial community was capable of degrading the labeled compound. In addition, we examined the chemistry and flow dynamics of these traps and present those results here. We performed a field experiment and a lab experiment to, in part, define the rate that different baits leached off various traps. At a TBA- and MTBE-contaminated site at Vandenberg AFB, Lompoc, CA, the TBA-dominant plume was effectively treated by recirculation/oxygenation of groundwater, decreasing TBA and MTBE concentrations to detection limits along predicted flowpaths created by two pairs of recirculation wells. We used the generated aerobic treatment zone to deploy traps baited with 13C-labeled MTBE or TBA in a novel, ex situ experimental setup. The groundwater flow extracted from the aerobic treatment zone was split through several chambers, each containing a trap and monitoring of influent and effluent. The chamber effluent was measured throughout a six-week deployment and analyzed for both TBA and MTBE; the majority of mass leached from the baited traps did

  5. TOXICITY OF METHYL-TERT BYTYL ETHER (MTBE) TO PLANTS (AVENA SATIVA, ZEA MAYS, TRITICUM AESTIVUM, AND LACTUCA SATIVA)

    Science.gov (United States)

    Effects of Methyl tert-butyl ether (MTBE) on the germination of seeds and growth of the plant were studied in some laboratory experiments. Test plants were wild oat (Avena sative), sweet corn (Zea mays), wheat (Triticum aestivum), and lettuce (Lactuca sativa). Seed germination,...

  6. Synthesis and characterization of cationic selenium-nitrogen heterocycles from tert-butyl-DAB (DAB = 1,4-di-tert-butyl-1,3-diazabutadiene) and SeX4 via the reductive elimination of X2 (X = Cl, Br): a distinct contrast with tellurium.

    Science.gov (United States)

    Dutton, Jason L; Sutrisno, Andre; Schurko, Robert W; Ragogna, Paul J

    2008-07-14

    The synthesis and comprehensive characterisation of a series of 1,2,5-selenadiazolium salts, which were generated from the direct reaction between the neutral bidentate ligand tert-butyl-DAB and a variety of heavy chalcogen halides, are reported. The formation of the cationic heterocycle from the reaction of SeX4 (X = Cl, Br) and the ligand results in a two electron redox process where the chalcogen undergoes a two electron reduction concomitant with the elimination of X2, the oxidation by-product. A reaction pathway for this chemistry has been proposed necessitating several key intermediates. These species have been synthesized and used in a stepwise series of transformations that strongly supports this very unusual reactivity for the chalcogens. In contrast, the reaction between tert-butyl DAB and TeX4 (X = Cl, Br, I), does not result in redox, rather an octahedral Te(iv) x DAB complex is formed or no reaction was observed.

  7. Complexation study of a tert-butyl-calix[4]arene-based 2-hydroxynaphthalene ligand with uranium(VI) in non-aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Anne; Schmeide, Katja [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    The actinide uranium, well known from nuclear power cycle, plays also a role in rare earth production as it is an undesired constituent of the respective ores. To facilitate the production of rare earth elements, uranium has to be removed. Due to their modifiable selectivity and solubility calix[n]arenes are interesting compounds for the extraction of actinides and lanthanides. The mechanism of uranium(VI) interaction with a tert-butyl-calix[4]arene-based 2-hydroxynaphthalene ligand (L1) was studied by TRLFS, UV-vis spectroscopy and isothermal calorimetry.

  8. Red fluorescent materials based on julolidine/chromene with the bulky tert-butyl and trimethylsilyl substituents for organic light-emitting diodes.

    Science.gov (United States)

    Na, Eun Jae; Kim, Hye Jeong; Lee, Kum Hee; Lee, Seok Jae; Kim, Young Kwan; Yoon, Seung Soo

    2014-08-01

    In this work, we designed and synthesized two red emitters 2-(6,8-di-tert-butyl-2-(2-(1,1-dimethyl-7-(trimethylsilyl)-7-((trimethylsilyl)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-4H-chromen-4-ylidene)malononitrile (Red 1) and 2-(6,8-di-tert-butyl-2-(2-(1,1,7-trimethyl-7-t-butyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-4H-chromen-4-ylidene)malononitrile (Red 2). To explore the electro-luminescence properties of these materials, multilayered OLEDs using these materials as dopants in a Alq3 host were fabricated. Particularly, by using Red 1 as a dopant in emitting layer, device 1 showed the luminous and power efficiencies of 0.81 cd/A and 0.43 lm/W at 20 mA/cm2, respectively. The CIE coordinates of this device was (0.65, 0.34) at 7.0 V, which is close to the NTSC standard CIE coordinates of (0.67,0.32) for red emission.

  9. Protective Effects of Rooibos (Aspalathus linearis and/or Red Palm Oil (Elaeis guineensis Supplementation on tert-Butyl Hydroperoxide-Induced Oxidative Hepatotoxicity in Wistar Rats

    Directory of Open Access Journals (Sweden)

    Olawale R. Ajuwon

    2013-01-01

    Full Text Available The possible protective effects of an aqueous rooibos extract (Aspalathus linearis, red palm oil (RPO (Elaeis guineensis, or their combination on tert-butyl-hydroperoxide-(t-BHP-induced oxidative hepatotoxicity in Wistar rats were investigated. tert-butyl hydroperoxide caused a significant (P<0.05 elevation in conjugated dienes (CD and malondialdehyde (MDA levels, significantly (P<0.05 decreased reduced glutathione (GSH and GSH : GSSG ratio, and induced varying changes in activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase in the blood and liver. This apparent oxidative injury was associated with histopathological changes in liver architecture and elevated levels of serum alanine aminotransferase (ALT, aspartate aminotransferase (AST, and lactate dehydrogenase (LDH. Supplementation with rooibos, RPO, or their combination significantly (P<0.05 decreased CD and MDA levels in the liver and reduced serum level of ALT, AST, and LDH. Likewise, changes observed in the activities of antioxidant enzymes and impairment in redox status in the erythrocytes and liver were reversed. The observed protective effects when rooibos and RPO were supplemented concomitantly were neither additive nor synergistic. Our results suggested that rooibos and RPO, either supplemented alone or combined, are capable of alleviating t-BHP-induced oxidative hepatotoxicity, and the mechanism of this protection may involve inhibition of lipid peroxidation and modulation of antioxidants enzymes and glutathione status.

  10. Protective Effects of Rooibos (Aspalathus linearis) and/or Red Palm Oil (Elaeis guineensis) Supplementation on tert-Butyl Hydroperoxide-Induced Oxidative Hepatotoxicity in Wistar Rats.

    Science.gov (United States)

    Ajuwon, Olawale R; Katengua-Thamahane, Emma; Van Rooyen, Jacques; Oguntibeju, Oluwafemi O; Marnewick, Jeanine L

    2013-01-01

    The possible protective effects of an aqueous rooibos extract (Aspalathus linearis), red palm oil (RPO) (Elaeis guineensis), or their combination on tert-butyl-hydroperoxide-(t-BHP-)induced oxidative hepatotoxicity in Wistar rats were investigated. tert-butyl hydroperoxide caused a significant (P < 0.05) elevation in conjugated dienes (CD) and malondialdehyde (MDA) levels, significantly (P < 0.05) decreased reduced glutathione (GSH) and GSH : GSSG ratio, and induced varying changes in activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase in the blood and liver. This apparent oxidative injury was associated with histopathological changes in liver architecture and elevated levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). Supplementation with rooibos, RPO, or their combination significantly (P < 0.05) decreased CD and MDA levels in the liver and reduced serum level of ALT, AST, and LDH. Likewise, changes observed in the activities of antioxidant enzymes and impairment in redox status in the erythrocytes and liver were reversed. The observed protective effects when rooibos and RPO were supplemented concomitantly were neither additive nor synergistic. Our results suggested that rooibos and RPO, either supplemented alone or combined, are capable of alleviating t-BHP-induced oxidative hepatotoxicity, and the mechanism of this protection may involve inhibition of lipid peroxidation and modulation of antioxidants enzymes and glutathione status.

  11. Biosynthesis of tert-butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate by carbonyl reductase from Rhodosporidium toruloides in mono and biphasic media.

    Science.gov (United States)

    Liu, Zhi-Qiang; Wu, Lin; Zheng, Ling; Wang, Wen-Zhong; Zhang, Xiao-Jian; Jin, Li-Qun; Zheng, Yu-Guo

    2017-10-05

    tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is the key intermediate for synthesis of atorvastatin and rosuvastatin. Carbonyl reductase exhibits excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH) to synthesize (3R,5S)-CDHH. In this study, a whole cell biosynthesis reaction system to produce (3R,5S)-CDHH was constructed in organic solvents. A solution of 10% (v/v) Tween-80 was introduced to the reaction system as a co-solvent, which greatly enhanced biotransformation process, giving 98.9% yield, >99% ee and 1.8-fold higher space time yield in 5 h bioconversion of 1 M (S)-CHOH, compared with 98.7% yield and >99% ee in 9 h bioconversion of a purely aqueous reaction system. Moreover, a water-octanol biphasic reaction system was built and 20% of octanol was added as reservoir of substrate resulting in 98% yield, >99% ee and 4.08 mmol L-1 h-1 g-1 (wet cell weight) space time yield. This study paved a way for the whole cell biosynthesis of (3R,5S)-CDHH in mono and biphasic media. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Directed Evolution of Carbonyl Reductase from Rhodosporidium toruloides and Its Application in Stereoselective Synthesis of tert-Butyl (3R,5S)-6-Chloro-3,5-dihydroxyhexanoate.

    Science.gov (United States)

    Liu, Zhi-Qiang; Wu, Lin; Zhang, Xiao-Jian; Xue, Ya-Ping; Zheng, Yu-Guo

    2017-05-10

    tert-Butyl (3R,5S)-6-chloro-3,5-dihydroxyhexanoate ((3R,5S)-CDHH) is a key intermediate of atorvastatin and rosuvastatin synthesis. Carbonyl reductase RtSCR9 from Rhodosporidium toruloides exhibited excellent activity toward tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH). For the activity of RtSCR9 to be improved, random mutagenesis and site-saturation mutagenesis were performed. Three positive mutants were obtained (mut-Gln95Asp, mut-Ile144Lys, and mut-Phe156Gln). These mutants exhibited 1.94-, 3.03-, and 1.61-fold and 1.93-, 3.15-, and 1.97-fold improvement in the specific activity and kcat/Km, respectively. Asymmetric reduction of (S)-CHOH by mut-Ile144Lys coupled with glucose dehydrogenase was conducted. The yield and enantiomeric excess of (3R,5S)-CDHH reached 98 and 99%, respectively, after 8 h bioconversion in a single batch reaction with 1 M (S)-CHOH, and the space-time yield reached 542.83 mmol L-1 h-1 g-1 wet cell weight. This study presents a new carbonyl reductase for efficient synthesis of (3R,5S)-CDHH.

  13. Sterically directed nitronate complexes of 2,6-di-tert-butyl-4-nitrophenoxide with Cu(ii) and Zn(ii) and their H-atom transfer reactivity.

    Science.gov (United States)

    Porter, Thomas R; Hayes, Ellen C; Kaminsky, Werner; Mayer, James M

    2017-02-21

    The bulky 2,6-di-tert-butyl-4-nitrophenolate ligand forms complexes with [TptBuCuII]+ and [TptBuZnII]+ binding via the nitro group in an unusual nitronato-quinone resonance form (TptBu = hydro-tris(3-tert-butyl-pyrazol-1-yl)borate). The Cu complex in the solid state has a five-coordinate κ2-nitronate structure, while the Zn analogue has a four-coordinate κ1-nitronate ligand. 4-Nitrophenol, without the 2,6-di-tert-butyl substituents, instead binds to [TptBuCuII]+ through the phenolate oxygen. This difference in binding is very likely due to the steric difficulty in binding a 2,6-di-tert-butyl-phenolate ligand to the [TptBuMII]+ unit. TptBuCuII(κ2-O2NtBu2C6H2O) reacts with the hydroxylamine TEMPO-H (2,2,6,6-tetramethylpiperidin-1-ol) by abstracting a hydrogen atom. This system thus shows an unusual sterically enforced transition metal-ligand binding motif and a copper-phenolate interaction that differs from what is typically observed in biological and chemical catalysis.

  14. Crystal structure of (1,3-di-tert-butyl-η(5)-cyclo-penta-dien-yl)tri-methyl-hafnium(IV).

    Science.gov (United States)

    Pérez-Redondo, Adrián; Varela-Izquierdo, Víctor; Yélamos, Carlos

    2015-05-01

    The mol-ecule of the title organometallic hafnium(IV) com-pound, [Hf(CH3)3(C13H21)] or [HfMe3(η(5)-C5H3-1,3- (t) Bu2)], adopts the classical three-legged piano-stool geometry for mono-cyclo-penta-dienylhafnium(IV) derivatives with the three methyl groups bonded to the Hf(IV) atom at the legs. The C atoms of the two tert-butyl group bonded to the cyclo-penta-dienyl (Cp) ring are 0.132 (5) and 0.154 (6) Å above the Cp least-squares plane. There are no significant inter-molecular inter-actions present between the mol-ecules in the crystal structure.

  15. Crystal structure of (1,3-di-tert-butyl-η5-cyclo­penta­dien­yl)tri­methyl­hafnium(IV)

    Science.gov (United States)

    Pérez-Redondo, Adrián; Varela-Izquierdo, Víctor; Yélamos, Carlos

    2015-01-01

    The mol­ecule of the title organometallic hafnium(IV) com­pound, [Hf(CH3)3(C13H21)] or [HfMe3(η5-C5H3-1,3-tBu2)], adopts the classical three-legged piano-stool geometry for mono­cyclo­penta­dienylhafnium(IV) derivatives with the three methyl groups bonded to the Hf(IV) atom at the legs. The C atoms of the two tert-butyl group bonded to the cyclo­penta­dienyl (Cp) ring are 0.132 (5) and 0.154 (6) Å above the Cp least-squares plane. There are no significant inter­molecular inter­actions present between the mol­ecules in the crystal structure. PMID:25995884

  16. Tetrachlorido[N2,N2′-(dimethylsilanediylbis(N-tert-butyl-3-methylbenzimidamidato-κ2N2,N2′]hafnium(IV

    Directory of Open Access Journals (Sweden)

    Sheng-Di Bai

    2013-12-01

    Full Text Available The symmetric title molecule, [Hf(C26H40N4SiCl4], lies about a twofold rotation axis. The HfIV and Si atoms lie on the rotation axis with all other atoms being in general positions. The HfIV atom is six-coordinated by two N atoms from the N2,N2′-(dimethylsilanediylbis(N-tert-butyl-3-methylbenzimidamidate ligand and four Cl− ions in a slightly distorted octahedral geometry. The two amidinate moieties are connected through the central Si atom with Si—N bond length of 1.762 (3 Å, generating the characteristic N—C—N—Si—N—C—N skeleton of a silyl-linked ansa-bis(amidine species.

  17. Poly[[[diisothiocyanatocobalt(II]-bis[μ-4-tert-butyl-2,6-bis(1,2,4-triazol-1-ylmethylphenol

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available In the title compound, {[Co(NCS2(C16H20N6O2]·2C3H7NO·2H2O}n, each CoII ion located on an inversion center is six-coordinated by four equatorial N atoms from four different 4-tert-butyl-2,6-bis(1,2,4-triazol-1-ylmethylphenol (L ligands, and by two N atoms from two axial thiocyanate anions [Co—N = 2.104 (3–2.144 (3 Å]. The metal centres are connected via the bidentate L ligands into two-dimensional polymeric layers parallel to bc plane. The dimethylformamide and solvent water molecules participate in intermolecular O—H...O and O—H...S hydrogen bonds, which consolidate the crystal packing.

  18. Crystal structure and DFT study of (E-2,6-di-tert-butyl-4-{[2-(pyridin-2-ylhydrazin-1-ylidenemethyl}phenol

    Directory of Open Access Journals (Sweden)

    Md. Serajul Haque Faizi

    2017-10-01

    Full Text Available The title compound, C20H27N3O, was synthesized by condensation reaction of 3,5-di-tert-butyl-4-hydroxybenzaldehyde and 2-hydrazinylpyridine, and crystallizes in the centrosymmetric monoclinic space group C2/c. The conformation about the C=N bond is E. The dihedral angle between the rings is 18.1 (3°. An intermolecular N—H...N hydrogen bond generates an R22(8 ring motif. In the crystal, N—H...N hydrogen bonds connect pairs of molecules, forming dimers. Density functional theory (DFT optimized structures at the B3LYP/6–311 G(d,p level are compared with the experimentally determined molecular structure in the solid state.

  19. Crystal structure of (tert-butyl-carbamo-yl)(4-chloro-2-oxo-2H-chromen-3-yl)methyl acetate.

    Science.gov (United States)

    Moriguchi, Tetsuji; Jalli, Venkataprasad; Krishnamurthy, Suvratha; Tsuge, Akihiko; Yoja, Kenji

    2015-12-01

    In the title compound, C17H18ClNO5, which was synthesized by reacting 4-chloro-3-formyl-coumarin, acetic acid and tert-butyl isocyanide, the acetamido side chain is convoluted with ring-to-side chain C-C-C-C, C-C-C-N and C-C-N-C torsion angles of -123.30 (14), -135.73 (12) and 176.10 (12)°, respectively. In the crystal, N-H⋯O and weak C-H⋯O hydrogen bonds are present, which together with π-π coumarin-ring inter-actions [ring centroid separations = 3.4582 (8) and 3.6421 (9) Å], give rise to a layered structure lying parallel to (001).

  20. tert-Butyl (2S-2-{3-[(R-bis(tert-butoxycarbonylamino]-2-oxopiperidin-1-yl}-3-methylbutanoateCAS Registry Number 500222-63-9.

    Directory of Open Access Journals (Sweden)

    Michael J. Kangas

    2011-11-01

    Full Text Available The title compound, C24H42N2O7, is a chiral lactam-constrained amino acid with a six-membered ring backbone and isopropyl and tert-butyl ester side chains. The conformation of the six-membered ring can be described as a half chair, with two CH2 C atoms lying 0.443 (1 and −0.310 (1 Å out of the best plane of the other four atoms (mean deviation = 0.042 Å. Both N atoms are sp2 hybridized, lying 0.0413 (9 and 0.067 (1 Å out of the planes defined by the three C atoms bonded to them. The absolute configuration was determined, based on resonant scattering of light atoms in Cu Kα radiation.

  1. 5-tert-Butyl-2-(4'-[{sup 18}F]fluoropropynylphenyl)-1,3-dithiane oxides: potential new GABA{sub A} receptor radioligands

    Energy Technology Data Exchange (ETDEWEB)

    Li Xuehe; Jung, Yong-Woon; Snyder, Scott E.; Blair, Joseph; Sherman, Philip S.; Desmond, Timothy; Frey, Kirk A. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48109 (United States); Kilbourn, Michael R. [Department of Radiology, University of Michigan Medical School, Ann Arbor, MI 48109 (United States)], E-mail: mkilbour@umich.edu

    2008-07-15

    As potential new ligands targeting the binding site of {gamma}-aminobutyric acid (GABA) receptor ionophore, trans-5-tert-butyl-2-(4'-fluoropropynylphenyl)-2-methyl-1,1-dioxo-1, 3-dithiane (1) and cis/trans-5-tert-butyl-2-(4'-fluoropropynylphenyl)-2-methyl-1,1,3, 3-tetroxo-1,3-dithiane (2) were selected for radiolabeling and initial evaluation as in vivo imaging agents for positron emission tomography (PET). Both compounds exhibited identical high in vitro binding affinities (K{sub i}=6.5 nM). Appropriate tosylate-substituted ethynyl precursors were prepared by multistep syntheses involving stepwise sulfur oxidation and chromatographic isolation of desired trans isomers. Radiolabeling was accomplished in one step using nucleophilic [{sup 18}F]fluorination. In vivo biodistribution studies with trans-[{sup 18}F]1 and trans-[{sup 18}F]2 showed significant initial uptake into mouse brain and gradual washout, with heterogeneous regional brain distributions and higher retention in the cerebral cortex and cerebellum and lower retention in the striatum and pons-medulla. These regional distributions of the new radioligands correlated with in vitro and ex vivo measures of standard radioligands binding to the ionophore- and benzodiazepine-binding sites of GABA{sub A} receptor in rodent brain. A comparison of these results with previously prepared radiotracers for other neurochemical targets, including successes and failures as in vivo radioligands, suggests that higher-affinity compounds with increased retention in target brain tissues will likely be needed before a successful radiopharmaceutical for human PET imaging can be identified.

  2. Light-emitting thin films of glassy forming organic compounds containing 2-tert-butyl-6-methyl-4H-pyran-4-ylidene

    Science.gov (United States)

    Vembris, Aivars; Pudzs, Kaspars; Muzikante, Inta

    2012-06-01

    Low molecular mass organic compounds which make thin films from volatile organic solutions would be great benefit in future organic light emitting systems. Two most important advantages could be mentioned. First - the repetition of synthesis of small molecules is better than for polymers. Second - wet casting methods could be used. In this work we are presenting optical, electroluminescence and amplified spontaneous emission properties of four original glassy forming compounds containing 2-tert-butyl-6-methyl-4H-pyran-4-ylidene fragment as backbone of the molecule. They has the same N,N-dialkylamino electron donating group with incorporated bulky trityloxy ethyl groups. The difference of these compounds is in electron acceptor group. One has 1H-indene-1,3(2H)-dione group, second has pyrimidine-2,4,6(1H,3H,5H)-trione group, third has malononitrile group and fourth has 2-ethyl-2-cyanoacetate. Absorption maximum of the compounds is between 420 and 500 nm and is red shifted from weaker acceptor group to stronger one. The electroluminescence efficiency for simple device ITO/PEDOT:PSS/Organic compound/BaF/Al is low. For the best one with malononitrile group it was 0.13 cd/A and 0.036 lm/W. It could be increased by optimising the sample geometry or adding addition layers for charge carrier transport and exciton blocking. But nevertheless the use of these compounds in organic light emitting devices in neat films is unlikely. Attached bulky trityloxy ethyl groups and tert-butyl group decrease interaction between the molecules thus allowing to obtain amplified spontaneous emission in neat thin films for all investigated compounds.

  3. N-tert-Butyl-2-[4-(dimethylaminophenyl]imidazo[1,2-a]pyrazin-3-amine

    Directory of Open Access Journals (Sweden)

    Zeenat Fatima

    2013-04-01

    Full Text Available In the title compound, C18H23N5, the imidazole ring makes a dihedral angles of 3.96 (8 and 19.02 (8°, respectively, with the pyrazine and benzene rings while the dihedral angle between the pyrazine and benzene rings is 16.96 (7°. In the crystal, molecules are linked via N—H...N hydrogen bonds, forming chains along [010]. These chains are linked by C—H...N hydrogen bonds, forming two-dimensional networks lying parallel to (001.

  4. Simultaneous analysis of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils by normal-phase high performance liquid chromatography.

    Science.gov (United States)

    Li, Jun; Bi, Yanlan; Sun, Shangde; Peng, Dan

    2017-11-01

    A normal-phase high performance liquid chromatography method for the simultaneous determination of tert-butylhydroquinone, tert-butylquinone, butylated hydroxytoluene, 2-tert-butyl-4-hydroxyanisole, 3-tert-butyl-4-hydroxyanisole, α-tocopherol, γ-tocopherol, and δ-tocopherol in edible oils was investigated. A silica column was used to separate the analytes with the gradient elution. An ultraviolet-visible detector was set at dual wavelengths mode (280 and 310nm). The column temperature was 30°C. The analytes were directly extracted with methanol. Results showed that the normal-phase high performance liquid chromatography method performed well with wide liner ranges (0.10∼500.00μg/mL, R2>0.9998), low limits of detection and quantitation (below 0.40 and 1.21μg/mL, respectively), and good recoveries (81.38∼102.34% in soybean oils and 83.03∼100.79% in lard, respectively). The reduction of tert-butylquinone caused by the reverse-phase high performance liquid chromatography during the injection was avoided with the current normal-phase method. The two isomers of butylated hydroxyanisole can also be separated with good resolution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Phase equilibrium properties of binary and ternary systems containing di-isopropyl ether + 1-butanol + benzene at 313.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Villamanan, Rosa M. [Grupo de Termodinamica y Calibracion TERMOCAL, Dpto. Ingenieria Energetica y Fluidomecanica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, E-47071 Valladolid (Spain)]. E-mail: rvillama@dce.uva.es; Martin, M. Carmen [Grupo de Termodinamica y Calibracion TERMOCAL, Dpto. Ingenieria Energetica y Fluidomecanica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, E-47071 Valladolid (Spain)]. E-mail: mcmg@eis.uva.es; Chamorro, Cesar R. [Grupo de Termodinamica y Calibracion TERMOCAL, Dpto. Ingenieria Energetica y Fluidomecanica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, E-47071 Valladolid (Spain)]. E-mail: cescha@eis.uva.es; Villamanan, Miguel A. [Grupo de Termodinamica y Calibracion TERMOCAL, Dpto. Ingenieria Energetica y Fluidomecanica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, E-47071 Valladolid (Spain)]. E-mail: miguel.villamanan@eis.uva.es; Segovia, Jose J. [Grupo de Termodinamica y Calibracion TERMOCAL, Dpto. Ingenieria Energetica y Fluidomecanica, E.T.S. de Ingenieros Industriales, Universidad de Valladolid, Paseo del Cauce s/n, E-47071 Valladolid (Spain)]. E-mail: josseg@eis.uva.es

    2006-05-15

    (Vapour + liquid) equilibria data of (di-isopropyl ether + 1-butanol + benzene) (di-isopropyl ether + 1-butanol) and (1-butanol + benzene) have been measured at T = 313.15 K using an isothermal total pressure cell. Data reduction by Barker's method provides correlations for the excess molar Gibbs energy using the Margules equation for the binary systems and the Wohl expansion for the ternary. The Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems reported here.

  6. Acyloxylation of 1-methoxycyclohex-1-ene and other enol ethers with dimethyl peroxydicarbonate

    OpenAIRE

    Schank, Kurt; Beck, Horst; Pistorius, Susanne; Rapold, Thomas

    1995-01-01

    Acyloxylation of different types of enol ethers (derived from aldehydes and ketones) by dimethyl peroxydicarbonate (DPDC) results in either addition to the double bond or in a formal replacement of an allylic hydrogen by a methoxycarbonyloxy group forming vicinal oxygenated hydrocarbons. 1,3-oxygenated products via monoacyloxylation could not be observed. The results with 1-methoxycyclohex-1-ene (1a) are compared with copper(I)-salt catalyzed acyloxylations by means of tert. butyl peroxycarbo...

  7. On the competition between weak Osbnd H⋯F and Csbnd H⋯F hydrogen bonds, in cooperation with Csbnd H⋯O contacts, in the difluoromethane - tert-butyl alcohol cluster

    Science.gov (United States)

    Spada, Lorenzo; Tasinato, Nicola; Bosi, Giulio; Vazart, Fanny; Barone, Vincenzo; Puzzarini, Cristina

    2017-07-01

    The 1:1 complex of tert-butyl alcohol with difluoromethane has been characterized by means of a joint experimental-computational investigation. Its rotational spectrum has been recorded by using a pulsed-jet Fourier-Transform microwave spectrometer. The experimental work has been guided and supported by accurate quantum-chemical calculations. In particular, the computed potential energy landscape pointed out the formation of three stable isomers. However, the very low interconversion barriers explain why only one isomer, showing one Osbnd H⋯F and two Csbnd H⋯O weak hydrogen bonds, has been experimentally characterized. The effect of the H → tert-butyl-group substitution has been analyzed from the comparison to the difluoromethane-water adduct.

  8. Synthesis of [[sup 123]I]tert-Butyl 8-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiaze pine 3-carboxylate, a potential SPECT imaging agent for diazepam-intensive (DI) benzodiazepine receptors

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoshu He; Matecka, Dorota; Ziqiang Gu; Rice, K.C.; Costa, B.R. de (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States)); Lee, K.S. (National Inst. of Mental Health, Washington, DC (United States)); Wong, Garry; Skolnick, Phil (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States). Lab. of Neuroscience)

    1994-01-01

    [[sup 123]I]tert-Butyl 8-iodo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5-a] [1,4]benzodiazepine 3-carboxylate ([[sup 123]I]3), a high affinity and selective radioligand for the diazepam insensitive (DI) benzodiazepine receptor was synthesized in 2 steps from tert-butyl 8-bromo-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodiaz epine 3-carboxylate. (Author).

  9. Contact allergy to 2-hydroxy-5-tert-butyl benzylalcohol and 2,6-bis(hydroxymethyl)-4-tert-butylphenol, components of a phenolic resin used in marking pens

    DEFF Research Database (Denmark)

    Hagdrup, H; Egsgaard, H; Carlsen, L

    1994-01-01

    2-hydroxy-5-tert-butyl benzylalcohol and 2,6-bis(hydroxymethyl)-4-tert-butylphenol were identified as contact allergens in a phenolic resin used as a tackifier in the ink of a marking pen, which, after being used directly on the skin, caused an acute contact dermatitis on the hand of a 13-year......-old boy. The patient also reacted to 4-tert-butylphenol-formaldehyde resin (BPF resin) 1% pet. included in the European standard series....

  10. Characterization of Individual Isopropylated and tert-Butylated Triarylphosphate (ITP and TBPP) Isomers in Several Commercial Flame Retardant Mixtures and House Dust Standard Reference Material SRM 2585.

    Science.gov (United States)

    Phillips, Allison L; Hammel, Stephanie C; Konstantinov, Alex; Stapleton, Heather M

    2017-11-21

    Since the phase-out of pentaBDE in the early 2000s, replacement flame-retardant mixtures including Firemaster 550 (FM 550), Firemaster 600 (FM 600), and organophosphate aryl ester technical mixtures have been increasingly used to treat polyurethane foam in residential upholstered furniture. These mixtures contain isomers of isopropylated and tert-butylated triarylphosphate esters (ITPs and TBPPs), which have similar or greater neuro- and developmental toxicity compared to BDE 47 in high-throughput assays. Additionally, human exposure to ITPs and TBPPs has been demonstrated to be widespread in several recent studies; however, the relative composition of these mixtures has remained largely uncharacterized. Using available authentic standards, the present study quantified the contribution of individual ITP and TBPP isomers in four commercial flame retardant mixtures: FM 550, FM 600, an ITP mixture, and a TBPP mixture. Findings suggest similarities between FM 550 and the ITP mixture, with 2-isopropylphenyl diphenyl phosphate (2IPPDPP), 2,4-diisopropylphenyl diphenyl phosphate (24DIPPDPP), and bis(2-isopropylphenyl) phenyl phosphate (B2IPPPP) being the most prevalent ITP isomers in both mixtures. FM 600 differed from FM 550 in that it contained TBPP isomers instead of ITP isomers. These analytes were also detected and quantified in a house dust standard reference material, SRM 2585, demonstrating their environmental relevance.

  11. Effects of Consumption of Rooibos (Aspalathus linearis and a Rooibos-Derived Commercial Supplement on Hepatic Tissue Injury by tert-Butyl Hydroperoxide in Wistar Rats

    Directory of Open Access Journals (Sweden)

    B. D. Canda

    2014-01-01

    Full Text Available This study investigated the antioxidative effect of rooibos herbal tea and a rooibos-derived commercial supplement on tert-butyl hydroperoxide- (t-BHP- induced oxidative stress in the liver. Forty male Wistar rats consumed fermented rooibos, unfermented rooibos, a rooibos-derived commercial supplement, or water for 10 weeks, while oxidative stress was induced during the last 2 weeks via intraperitoneal injection of 30 µmole of t-BHP per 100 g body weight. None of the beverages impaired the body weight gain of the respective animals. Rats consuming the rooibos-derived commercial supplement had the highest (P<0.05 daily total polyphenol intake (169 mg/day followed by rats consuming the unfermented rooibos (93.4 mg/day and fermented rooibos (73.1 mg/day. Intake of both the derived supplement and unfermented rooibos restored the t-BHP-induced reduction and increased (P<0.05 the antioxidant capacity status of the liver, while not impacting on lipid peroxidation. The rooibos herbal tea did not affect the hepatic antioxidant enzymes, except fermented rooibos that caused a decrease (P<0.05 in superoxide dismutase activity. This study confirms rooibos herbal tea as good dietary antioxidant sources and, in conjunction with its many other components, offers a significantly enhanced antioxidant status of the liver in an induced oxidative stress situation.

  12. The Synergistic Effects of Heat Shock Protein 70 and Ginsenoside Rg1 against Tert-Butyl Hydroperoxide Damage Model In Vitro

    Directory of Open Access Journals (Sweden)

    Dan Lu

    2015-01-01

    Full Text Available Neural stem cells (NSCs transplanted is one of the hottest research to treat Alzheimer’s disease (AD, but cholinergic neurons from stem cells were also susceptible to cell death which Heat shock protein 70 (HSP70 was affirmed to reverse. Related to cognitive impairment, cholinergic nervous cells should be investigated and ginsenoside Rg1 (G-Rg1 was considered to increase them. We chose tert-butyl hydroperoxide (t-BHP damage model to study in vitro. Functional properties of our recombination plasmid pEGFP-C2-HSP70 were affirmed by SH-SY5Y cells. To opposite the transitory appearance of HSP70, NSCs used as the vectors of HSP70 gene overexpressed HSP70 for at least 7 days in vitro. After transfection for 3 days, G-Rg1 pretreatment for 4 hours, and coculture for 3 days, the expression of acetylcholinesterase (ChAT, synaptophysin, and the ratio of NeuN and GFAP were assessed by western blot; Morphological properties were detected by 3D reconstruction and immunofluorescence. ChAT was markedly improved in the groups contained G-Rg1. In coculture system, the ratio of neurons/astrocytes and the filaments of neurons were increased; apoptosis cells were decreased, compared to monotherapy (P<0.05. In conclusion, we demonstrated that, as a safe cotreatment affirmed in vitro, overexpression of HSP70 in NSCs plus G-Rg1 promoted nervous cells regeneration from chronic oxidative damage.

  13. Effects of colored and noncolored phenolics of Echium plantagineum L. bee pollen in Caco-2 cells under oxidative stress induced by tert-butyl hydroperoxide.

    Science.gov (United States)

    Sousa, Carla; Moita, Eduarda; Valentão, Patrícia; Fernandes, Fátima; Monteiro, Pedro; Andrade, Paula B

    2015-02-25

    Bee pollen is used as a dietary supplement, being promoted as a health food. Echium plantagineum L. bee pollen fractions enriched in flavonols (fraction I) or anthocyanins (fraction II) and the whole extract were characterized by HPLC-DAD. Both in the whole extract and in fraction II seven flavonols and five anthocyanins were identified, while fraction I contained six flavonols (in higher levels than fraction II) and small amounts of petunidin-3-O-rutinoside. Antioxidant capacity was evaluated in Caco-2 cells under oxidative stress induced by tert-butyl hydroperoxide (t-BHP). Fraction I pre-exposure imparted a tendency to protect cells, while fraction II and the whole extract aggravated t-BHP toxicity at some concentrations. The protective effects seem to be correlated with the levels of total glutathione, while no correlation between cellular viability and reactive species was seen. The extracts displayed no significant effect on antioxidant enzymes activity. Overall, anthocyanins seem to abrogate the antioxidant potential of flavonoid-rich extracts.

  14. Smart polymeric cathode material with intrinsic overcharge protection based on a 2,5-di-tert-butyl- 1,4-dimethoxybenzene core structure

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Wei; Zhang, Zhengcheng; Abouimrane, Ali; Redfern, Paul C.; Curtiss, Larry A.; Amine, Khalil [Chemical Sciences and Engineering, Division and Material Sciences Division, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, IL 60439 (United States)

    2012-11-07

    Polymer-based electroactive materials have been studied and applied in energy storage systems as a valid replacement for transition metal oxides. As early as 1999, Hass et al. proposed an interesting concept on the possible incorporation of both charge storage and overcharge protection functionality into a single material. However, there are virtually no examples of polymeric materials that can not only store the charge, but also consume the overcharge current. Herein, a new material based on a cross-linked polymer (I) with 2,5-di-tert-butyl-1,4-dimethoxybenzene as the core structure is reported. The cyclic voltammogram of the synthesized polymer shows a single oxidation/reduction peak at 3.9-4.0 V. At 1C rate (56 mA/g), polymer I shows stable cycling up to 200 cycles with <10% capacity loss. The redox shuttle mechanism remarkably can be activated when cell voltage is elevated to 4.3 V and the overcharge plateau at 4.2 V (2{sup nd} plateau) is persistent for more than 100 hours. The overcharge protection was due to the release of a chemical redox shuttle species in the electrolyte during the initial charging process. Both DFT calculations and NMR analysis of the aromatic signals in the {sup 1}H-NMR spectrum of electrolytes from ''overcharged'' cells provide evidence for this hypothesis. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Molecular structure, vibrational, UV, NMR, HOMO-LUMO, MEP, NLO, NBO analysis of 3,5 di tert butyl 4 hydroxy benzoic acid

    Science.gov (United States)

    Mathammal, R.; Sangeetha, K.; Sangeetha, M.; Mekala, R.; Gadheeja, S.

    2016-09-01

    In this study, we report a combined experimental and theoretical study on molecular structure and vibrational spectra of 3,5 di tert butyl 4 hydroxy benzoic acid. The properties of title compound have been evaluated by quantum chemical calculation (DFT) using B3LYP functional and 6-31 + G (d, p) as basis set. IR Spectra has been recorded using Fourier transform infrared spectroscopy (FT-IR) in the region 4000-400 cm-1. The vibrational assignment of the calculated normal modes has been made on the basis set. The isotropic chemical shifts computed by 13C and 1H NMR (Nuclear Magnetic Resonance) analyses also show good agreement with experimental observations. The theoretical UV-Vis spectrum of the compound are used to study the visible absorption maxima (λ max). The structure activity relationship have been interpreted by mapping electrostatic potential surface (MEP), which is valuable information for the quality control of medicines and drug receptor interactions. The Mullikan charges, HOMO (Highest Occupied Molecular Orbital) - LUMO (Lowest Unoccupied Molecular Orbital) energy are analyzed. HOMO-LUMO energy gap and other related molecular properties are also calculated. The Natural Bond Orbital (NBO) analysis is carried out to investigate the various intra and inter molecular interactions of molecular system. The Non-linear optical properties such as dipole moment (μ), polarizability (αtot) and molecular first order hyperpolarizability (β) of the title compound are computed with B3LYP/6-31 + G (d,p) level of theory.

  16. Synthesis and molecular structure of indium complexes based on 3,6-di-tert-butyl-o-benzoquinone. Looking for indium(I) o-semiquinolate.

    Science.gov (United States)

    Piskunov, Alexandr V; Maleeva, Aryna V; Fukin, Georgii K; Baranov, Evgenii V; Bogomyakov, Artem S; Cherkasov, Vladimir K; Abakumov, Gleb A

    2011-01-21

    The interaction of 3,6-di-tert-butyl-o-benzoquinone (3,6-Q) with indium in toluene leads to the tris-o-semiquinolate derivative (3,6-SQ)(3)In (3,6-SQ - radical-anion of 3,6-Q). According to single-crystal X-ray diffraction analysis, this complex has a trigonal prismatic structure. Magnetic measurements revealed that the exchange interactions between odd electrons of the paramagnetic ligands in (3,6-SQ)(3)In are antiferromagnetic in character. The treatment of (3,6-SQ)(3)In with 2,2'-dipyridyl (Dipy) causes the displacement of one o-quinone ligand and the formation of the (3,6-SQ)In(Dipy)(3,6-Cat) (3,6-Cat - dianion of 3,6-Q) derivative containing mixed charged o-quinoid ligands. The reaction of InI with (3,6-SQ)K in THF solution is accompanied by a redox process and the potassium-indium(iii) catecholate derivative was obtained as a result. The oxidation of InI with 3,6-Q in THF produces the dimeric In(iii) iodo-catecholate complex [(3,6-Cat)(2)In·2THF]InI(2). The same derivative can be synthesized by the interaction of indium metal with a mixture of I(2) and 3,6-Q.

  17. Studies on the separation of {sup 89}Sr(II) from irradiated yttria target using 4, 4{sup '}(5{sup '}) di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6) by solvent extraction technique

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Debasish; Vithya, Jayagopal; Kumar, Ramalingam; Venkata Subramani, Canchipuram Ramamoorthy; Vasudeva Rao, Polur Ranga [Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam (India). Chemistry Group

    2016-07-01

    The radioisotope {sup 89}Sr as {sup 89}SrCl{sub 2} is medically useful for bone pain palliation and is produced in fast reactors using the {sup 89}Y(n, p){sup 89}Sr reaction. A procedure for isolation of the radionuclide {sup 89}Sr by chemical processing of the irradiated Y{sub 2}O{sub 3} target has been standardised and trial runs have been carried out at the Fast Breeder Test Reactor (FBTR), Kalpakkam. The chemical processing of the irradiated Y{sub 2}O{sub 3} target involves (i) the removal of target Y(III) by TBP extraction and (ii) further purification of the separated {sup 89}Sr fraction by cationic exchange chromatography. However a selective isolation of {sup 89}Sr by the Sr-specific crown ether makes the above chemical processing faster and relatively simple. This work presents a study on the selective removal of Sr from the irradiated target dissolver solution using the Sr-specific crown ether 4,4{sup '}(5{sup '}) di-tert-butyl-cyclohexano-18-crown-6 (DtBuCH18C6) in octanol medium. The separation behaviour of the other impurities such as Ce(IV), Y(III), Tb(III), Eu(III), Zn(II), Mn(II) and Rb(I) present along with Sr(II) in the irradiated sample was also investigated. The method of separation by using the crown ether DtBuCH18C6 is proved to be a potential tool for the purification of {sup 89}Sr(II) source produced from yttria target in fast reactors.

  18. Rotational Investigation of the Adducts of Formic Acid with Alcohols, Ethers and Esters

    Science.gov (United States)

    Evangelisti, Luca; Spada, Lorenzo; Li, Weixing; Caminati, Walther

    2016-06-01

    Mixtures of formic acid with methyl alcohol, with isopropyl alcohol, with tert-butyl alcohol, with dimethylether and with isopropylformiate have been supersonically expanded as pulsed jets. The obtained cool plumes have been analyzed by Fourier transform microwave spectroscopy. It has been possible to assign the rotational spectra of the 1:1 adducts of formic acid with tert-butyl alcohol, with dimethyl ether and with isopropylformiate. The conformational shapes and geometries of these adducts, as well as the topologies of their itermolecular hydrogen bonds will be presented. An explanation is given of the failure of the assignments of the rotational spectra of the adducts of formic acid with methyl alcohol and isopropyl alcohol.

  19. Relationship between Sublethal Injury and Microbial Inactivation by the Combination of High Hydrostatic Pressure and Citral or tert-Butyl Hydroquinone ▿

    Science.gov (United States)

    Somolinos, Maria; García, Diego; Pagán, Rafael; Mackey, Bernard

    2008-01-01

    The aim was to investigate (i) the occurrence of sublethal injury in Listeria monocytogenes, Escherichia coli, and Saccharomyces cerevisiae after high hydrostatic pressure (HHP) treatment as a function of the treatment medium pH and composition and (ii) the relationship between the occurrence of sublethal injury and the inactivating effect of a combination of HHP and two antimicrobial compounds, tert-butyl hydroquinone (TBHQ) and citral. The three microorganisms showed a high proportion of sublethally injured cells (up to 99.99% of the surviving population) after HHP. In E. coli and L. monocytogenes, the extent of inactivation and sublethal injury depended on the pH and the composition of the treatment medium, whereas in S. cerevisiae, inactivation and sublethal injury were independent of medium pH or composition under the conditions tested. TBHQ alone was not lethal to E. coli or L. monocytogenes but acted synergistically with HHP and 24-h refrigeration, resulting in a viability decrease of >5 log10 cycles of both organisms. The antimicrobial effect of citral depended on the microorganism and the treatment medium pH. Acting alone for 24 h under refrigeration, 1,000 ppm of citral caused a reduction of 5 log10 cycles of E. coli at pH 7.0 and almost 3 log10 cycles of L. monocytogenes at pH 4.0. The combination of citral and HHP also showed a synergistic effect. Our results have confirmed that the detection of sublethal injury after HHP may contribute to the identification of those treatment conditions under which HHP may act synergistically with other preserving processes. PMID:18952869

  20. Incorporation of the hydrophobic probe N-t-BOC-L-tyrosine tert-butyl ester to red blood cell membranes to study peroxynitrite-dependent reactions.

    Science.gov (United States)

    Romero, Natalia; Peluffo, Gonzalo; Bartesaghi, Silvina; Zhang, Hao; Joseph, Joy; Kalyanaraman, Balaraman; Radi, Rafael

    2007-11-01

    We have previously demonstrated that red blood cells (RBC) are an important sink of intravascularly generated peroxynitrite even in the presence of physiological concentrations of CO2 or other plasmatic biotargets. Once inside erythrocytes, peroxynitrite reacts fast with oxyhemoglobin (oxyHb; k2=2 x 10(4) M(-1) s(-1) at 37 degrees C and pH 7.4) and isomerizes to nitrate. Herein, we investigated whether, in spite of the fast diffusion and consumption of extracellularly added peroxynitrite by intraerythrocytic oxyHb, peroxynitrite-dependent radical processes could occur at the RBC membrane, focusing on tyrosine nitration. For this purpose, the hydrophobic tyrosine analogue N-t-BOC-L-tyrosine tert-butyl ester (BTBE) was successfully incorporated for the first time to a biological membrane, that is, RBC membrane, with incorporation yields approximately 1-3 x 10(7) molecules per RBC. The membrane integrity of BTBE-containing RBC was not significantly altered after BTBE incorporation as demonstrated by permeability studies. The probe was then used to study peroxynitrite-dependent reactions. The addition of peroxynitrite to BTBE-containing RBC suspensions resulted in BTBE nitration and dimerization to 3-nitro-BTBE and 3,3'-di-BTBE, respectively, indicative of peroxynitrite-derived radicals reactions in the membrane. Peroxynitrite addition to RBC also caused tyrosine nitration of membrane-associated proteins. The free radical nature of the process was also shown by the detection of protein-derived radicals by DMPO-immunospin trapping. While the presence of extracellular CO2 was potently inhibitory of intracellular oxyHb oxidation, membrane protein and BTBE nitration by peroxynitrite at membrane, in spite of the significant peroxynitrite scavenging activity of oxyHb inside the RBC.

  1. Simultaneous Analysis of Tertiary Butylhydroquinone and 2-tert-Butyl-1,4-benzoquinone in Edible Oils by Normal-Phase High-Performance Liquid Chromatography.

    Science.gov (United States)

    Li, Jun; Bi, Yanlan; Liu, Wei; Sun, Shangde

    2015-09-30

    During the process of antioxidation of tertiary butylhydroquinone (TBHQ) in oil and fat systems, 2-tert-butyl-1,4-benzoquinone (TQ) can be formed. The toxicity of TQ was much more than that of TBHQ. In the work, a normal-phase high-performance liquid chromatography (NP-HPLC) method for the accurate and simultaneous detection of TBHQ and TQ in edible oils was investigated. A C18 column was used to separate TBHQ and TQ, and the gradient elution solutions consisted of n-hexane containing 5% ethyl acetate and n-hexane containing 5% isopropanol. The ultraviolet (UV) detector was set at dual wavelength mode (280 nm for TBHQ and 310 nm for TQ). The column temperature was 30 °C. Before the NP-HPLC analysis, TBHQ and TQ were first extracted by methanol, subjected to vortex treatment, and then filtered through a 0.45 μm membrane filter. Results showed that linear ranges of TBHQ and TQ were both within 0.10-500.00 μg/mL (R(2) > 0.9999). The limit of detection (LOD) and limit of quantification (LOQ) of TBHQ and TQ were below 0.30 and 0.91 μg/mL and below 0.10 and 0.30 μg/mL, respectively. The recoveries of TBHQ and TQ were 98.92-102.34 and 96.28-100.58% for soybean oil and 96.11-99.42 and 98.83-99.24% for lard, respectively. These results showed that NP-HPLC can be successfully used to analyze simultaneously TBHQ and TQ in the oils and fats.

  2. The studies on complex formation of metal borides in the reaction system of epoxidation of 1-octene with tert-butyl hydroperoxide by IR spectroscopy

    OpenAIRE

    Makota, Oksana; Trach, Yuriy

    2007-01-01

    Вивчено комплексоутворення боридів молібдену і ванадію в реакційній системі епоксидування октену-1 гідропероксидом трет-бутилу методом інфрачервоної спектроскопії. Показано, що октен-1 утворює комплекс з металевою складовою у випадку бориду молібдену і з боридною складовою у випадку бориду ванадію.The complex formation of molybdenum and vanadium borides in the reaction system of 1-octene epoxidation with tert -butyl hydroperoxide by infrared spectroscopic analysis was studied. It was sh...

  3. Gastroprotective activity of ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylidene amino]benzoate against ethanol-induced gastric mucosal ulcer in rats.

    Directory of Open Access Journals (Sweden)

    Mohammed Farouq Halabi

    Full Text Available BACKGROUND: The study was carried out to determine the cytotoxic, antioxidant and gastro-protective effect of ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylid eneamino] benzoate (ETHAB in rats. METHODOLOGY/PRINCIPAL FINDINGS: The cytotoxic effect of ETHAB was assessed using a MTT cleavage assay on a WRL68 cell line, while its antioxidant activity was evaluated in vitro. In the anti-ulcer study, rats were divided into six groups. Group 1 and group 2 received 10% Tween 20 (vehicle. Group 3 received 20 mg/kg Omeprazole. Groups 4, 5 and 6 received ETHAB at doses of 5, 10, and 20 mg/kg, respectively. After an hour, group 1 received the vehicle. Groups 2-6 received absolute ethanol to induce gastric mucosal lesions. In the WRL68 cell line, an IC50 of more than 100 µg/mL was observed. ETHAB results showed antioxidant activity in the DPPH, FRAP, nitric oxide and metal chelating assays. There was no acute toxicity even at the highest dosage (1000 mg/kg. Microscopy showed that rats pretreated with ETHAB revealed protection of gastric mucosa as ascertained by significant increases in superoxide dismutase (SOD, pH level, mucus secretion, reduced gastric lesions, malondialdehyde (MDA level and remarkable flattened gastric mucosa. Histologically, pretreatment with ETHAB resulted in comparatively better gastric protection, due to reduction of submucosal edema with leucocyte infiltration. PAS staining showed increased intensity in uptake of Alcian blue. In terms of immunohistochemistry, ETHAB showed down-expression of Bax proteins and over-expression of Hsp70 proteins. CONCLUSION/SIGNIFICANCE: The gastroprotective effect of ETHAB may be attributed to antioxidant activity, increased gastric wall mucus, pH level of gastric contents, SOD activity, decrease in MDA level, ulcer area, flattening of gastric mucosa, reduction of edema and leucocyte infiltration of the submucosal layer, increased PAS staining, up-regulation of Hsp70 protein and suppressed expression of

  4. Study of Methyl tert-butyl Ether (MTBE Photocatalytic Degradation with UV/TiO2-ZnO-CuO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mohsen Mansouri

    2017-01-01

    Full Text Available In this study, the TiO2-ZnO-CuO nanoparticles were primed by sol-gel method characterized by X-ray diffraction (XRD and Scanning Electron Microscopy (SEM, for degradation of MTBE solution in water. The effectiveness of the treatment method applied for the degradation of MTBE based on an advanced photocatalytic oxidation process was investigated. The three various key parameters were optimized using response surface modeling namely: pH, TiO2-ZnO-CuO concentration and the initial MTBE concentrations. The optimized values were obtained at the PH (7, TiO2-ZnO-CuO concentration (1.49 g/L, and the initial MTBE concentration (31.46 mg/L. Finally, kinetics reaction of degradtion MTBE was carried in the optimum conditions.

  5. Methyl tert-butyl ether (MTBE) detected in abnormally high concentrations in postmortem blood and urine from two persons found dead inside a car containing a gasoline spill.

    Science.gov (United States)

    Karinen, Ritva; Vindenes, Vigdis; Morild, Inge; Johnsen, Lene; Le Nygaard, Ilah; Christophersen, Asbjørg S

    2013-09-01

    Two deep frozen persons, a female and a male, were found dead in a car. There had been an explosive fire inside the car which had extinguished itself. On the floor inside the car were large pools of liquid which smelled of gasoline. The autopsy findings and routine toxicological analyses could not explain the cause of death. Carboxyhemoglobin levels in the blood samples were gasoline as a fuel oxygenate. Gasoline poisoning is likely to be the cause of the death in these two cases, and MTBE can be a suitable marker of gasoline exposure, when other volatile components have vaporized. © 2013 American Academy of Forensic Sciences.

  6. Structure of the mercury(II mixed-halide (Br/Cl complex of 2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzo[d]imidazole

    Directory of Open Access Journals (Sweden)

    Varsha Rani

    2017-03-01

    Full Text Available The mercury(II complex of 2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzimidazole, namely catena-poly[[dihalogenidomercury(II]-μ-2,2′-(5-tert-butyl-1,3-phenylenebis(1-pentyl-1H-benzimidazole-κ2N3:N3′], [HgBr1.52Cl0.48(C34H42N4], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the orthorhombic space group Pca21 and is a racemic twin [BASF = 0.402 (9]. The geometry around the HgII atom is distorted tetrahedral, with the HgII atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl. For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2:0.43 (2 for the tert-butyl group and 0.73 (3:0.27 (3 for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4:0.177 (4:0.154 (4 and 0.662 (4:0.224 (4:0.154 (4, respectively. The molecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C—H...Br and C—H...Cl interactions. Each strand is further linked by inter-strand C—H...Br and C—H...Cl interactions. In addition, there are weak C—H...N inter-strand interactions which further stabilize the structural arrangement.

  7. Ground-State Distortion in N-Acyl-tert-butyl-carbamates (Boc) and N-Acyl-tosylamides (Ts): Twisted Amides of Relevance to Amide N-C Cross-Coupling.

    Science.gov (United States)

    Szostak, Roman; Shi, Shicheng; Meng, Guangrong; Lalancette, Roger; Szostak, Michal

    2016-09-02

    Amide N-C(O) bonds are generally unreactive in cross-coupling reactions employing low-valent transition metals due to nN → π*C═O resonance. Herein we demonstrate that N-acyl-tert-butyl-carbamates (Boc) and N-acyl-tosylamides (Ts), two classes of acyclic amides that have recently enabled the development of elusive amide bond N-C cross-coupling reactions with organometallic reagents, are intrinsically twisted around the N-C(O) axis. The data have important implications for the design of new amide cross-coupling reactions with the N-C(O) amide bond cleavage as a key step.

  8. Gastroprotective Activity of Ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylidene) Amino]benzoate against Ethanol-Induced Gastric Mucosal Ulcer in Rats

    Science.gov (United States)

    Halabi, Mohammed Farouq; Shakir, Raied Mustafa; Bardi, Daleya Abdulaziz; Al-Wajeeh, Nahla Saeed; Ablat, Abdulwali; Hassandarvish, Pouya; Hajrezaie, Maryam; Norazit, Anwar; Abdulla, Mahmood Ameen

    2014-01-01

    Background The study was carried out to determine the cytotoxic, antioxidant and gastro-protective effect of ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylid ene)amino] benzoate (ETHAB) in rats. Methodology/Principal Findings The cytotoxic effect of ETHAB was assessed using a MTT cleavage assay on a WRL68 cell line, while its antioxidant activity was evaluated in vitro. In the anti-ulcer study, rats were divided into six groups. Group 1 and group 2 received 10% Tween 20 (vehicle). Group 3 received 20 mg/kg Omeprazole. Groups 4, 5 and 6 received ETHAB at doses of 5, 10, and 20 mg/kg, respectively. After an hour, group 1 received the vehicle. Groups 2–6 received absolute ethanol to induce gastric mucosal lesions. In the WRL68 cell line, an IC50 of more than 100 µg/mL was observed. ETHAB results showed antioxidant activity in the DPPH, FRAP, nitric oxide and metal chelating assays. There was no acute toxicity even at the highest dosage (1000 mg/kg). Microscopy showed that rats pretreated with ETHAB revealed protection of gastric mucosa as ascertained by significant increases in superoxide dismutase (SOD), pH level, mucus secretion, reduced gastric lesions, malondialdehyde (MDA) level and remarkable flattened gastric mucosa. Histologically, pretreatment with ETHAB resulted in comparatively better gastric protection, due to reduction of submucosal edema with leucocyte infiltration. PAS staining showed increased intensity in uptake of Alcian blue. In terms of immunohistochemistry, ETHAB showed down-expression of Bax proteins and over-expression of Hsp70 proteins. Conclusion/Significance The gastroprotective effect of ETHAB may be attributed to antioxidant activity, increased gastric wall mucus, pH level of gastric contents, SOD activity, decrease in MDA level, ulcer area, flattening of gastric mucosa, reduction of edema and leucocyte infiltration of the submucosal layer, increased PAS staining, up-regulation of Hsp70 protein and suppressed expression of Bax. Key words

  9. Mono- and Dinuclear Transition Metal Complexes of the Hexadentate Ligand Tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane (L).

    Science.gov (United States)

    Beissel, Thomas; Glaser, Thorsten; Kesting, Frank; Wieghardt, Karl; Nuber, Bernhard

    1996-06-19

    The hexadentate, pendant arm macrocycle 1,4,7-tris(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane (H(3)L) has been synthesized and isolated as its trihydrochloride, H(3)L.3HCl, or sodium salt, Na(3)L, and its coordination chemistry with first-row transition metals has been studied. Mononuclear complexes of the type [LM(III)] (M = Ga (1), In (2), V (3), Cr (4), Mn (5), Fe,Co (6)) have been isolated as have the one-electron-oxidized forms [LM]PF(6) (M = V(IV) (3a), Mn(IV) (5a)). The crystal structure of 6 has been determined by single-crystal X-ray crystallography. Complex 6 crystallizes in the orthorhombic space group Iba2, with cell constants a = 14.206(8) Å, b = 22.53(1) Å, c = 26.07(1) Å, V = 8344.0(3) Å(3), and Z = 8. The cobalt(III) ion is in a distorted octahedral fac-N(3)S(3) donor set. The reaction of L with divalent metal chlorides in a 1:2 ratio in methanol affords the homodinuclear complexes [LM(II)(2)Cl] (M = Mn (7), Co (8), Ni (9), Zn (10), Cd (11)) where one metal is six- (N(3)MS(3)) and the other is four-coordinate (S(3)MCl); the two polyhedra are linked by three &mgr;(2)-thiolato bridges. Heterodinuclear complexes of the type [LM(1)M(2)Cl] have been obtained from [LM(2)Cl] species by abstraction of the four-coordinate metal ion and replacement by a different metal ion. The complexes [LZn(II)M(II)Cl] (M = Fe (12), Co (13), Ni (14)), [LNi(II)M(II)Cl] (M = Co (15), Zn (16)), and [LMn(II)M(II)Cl] (M = Fe (17), Co (18), Ni (19), Zn (20), Cd (21), Hg (22)) have been isolated as solid materials. The crystal structure of 14 has been determined by X-ray crystallography. Complex 14 crystallizes in the orthorhombic space group P2(1)2(1)2(1), with cell constants a = 15.45(1) Å, b = 17.77(1) Å, c = 17.58(1) Å, V = 4826.5(4) Å(3), and Z = 4. The linkage isomers 14 and 16 show characteristic electronic spectra for octahedrally and tetrahedrally coordinated Ni(II), respectively. The electronic structures of new complexes have been investigated by UV

  10. Determination of fuel ethers in water by membrane extraction ion mobility spectrometry.

    Science.gov (United States)

    Holopainen, Sanna; Nousiainen, Marjaana; Sillanpää, Mika

    2013-03-15

    Fuel oxygenates are environmentally detrimental compounds due to their rapid migration to groundwater. Fuel oxygenates have been reported to cause taste and odour problems in drinking water, and they also have long-term health effects. Feasible analytical methods are required to observe the presence of fuel oxygenates in drinking and natural water. The authors studied ion mobility spectrometry (IMS) to determinate isomeric fuel ether oxygenates; ethyl tert-butyl ether (ETBE), diisopropyl ether (DIPE), and tert-amyl methyl ether (TAME), separated from aqueous matrices with a pervaporation membrane module. Methyl tert-butyl ether (MTBE) was also membrane extracted and detected with IMS. The authors demonstrated that fuel ethers (MTBE, ETBE, DIPE, and TAME) can be quantified at μg/L level with membrane extraction IMS. A membrane extraction module coupled to IMS is a time and cost effective analysis method because sampling can be performed in a single procedure and from different natural water matrices within a few minutes. Consequently, IMS combined with membrane extraction is suitable not only for waterworks and other online applications but also in the field monitoring the quality of drinking and natural water. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Thermally Activated Paramagnets from Diamagnetic Polymers of Biphenyl-3,5-diyl Bis(tert-butyl Nitroxides Carrying Methyl and Fluoro Groups at the 2’- and 5’-Positions

    Directory of Open Access Journals (Sweden)

    Toru Yoshitake

    2016-03-01

    Full Text Available Three new biradicals—2’,5’-dimethyl-, 2’-fluoro-5’-methyl-, and 5’-fluoro-2’-methyl- biphenyl-3,5-diyl bis(tert-butyl nitroxides—were synthesized. The magnetic susceptibility measurements revealed their diamagnetism below and around room temperature. The nitroxide groups are located close to each other in an intermolecular fashion to form a weakly covalent head-to-tail (NO2 ring. Biradical molecules are connected on both radical sites, constructing a diamagnetic chain. The dimethyl derivative underwent a structural phase transition at 83 °C, clarified via differential scanning calorimetry and powder X-ray diffraction, and a paramagnetic solid phase with S = 1 irreversibly appeared. The other analogues exhibited a similar irreversible upsurge of the magnetic susceptibility on heating, but the transition was characterized as the melting.

  12. Synthesis and self-assembly of 2,9,16-tri(tert-butyl)-23-(10-mercaptodecyloxy)phthalocyanine and the application of its self-assembled monolayers in organic light-emitting diodes.

    Science.gov (United States)

    Huang, Xuebin; Liu, Yunqi; Wang, Shuai; Zhou, Shuqin; Zhu, Daoben

    2002-09-16

    2,9,16-Tri(tert-butyl)-23-(10-mercaptodecyloxy)phthalocyanine (8) and its disulfide (9) have been synthesized and characterized, and their self-assembling behaviors on gold substrates have been studied. Characteristic Q-bands were observed at about 630 nm in the UV/visible spectra of the self-assembling monolayers (SAMs). They were broadened and blue-shifted relative to those observed in solution. Binding energies for S2p have the same values (161.70 eV) and are in accord with those for gold thiolates. The application of the SAMs in organic light-emitting diode was investigated. It shows that the SAM promotes the hole injection process from the anode.

  13. Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene; Synthese et proprietes complexantes vis-a-vis de l'ion uranyle de derives carboxyliques du p-tert-butyl-calix[6]arene

    Energy Technology Data Exchange (ETDEWEB)

    Souane, R

    2005-03-15

    In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO{sub 2}{sup 2+} form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO{sub 2}) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO{sub 2}L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid ({delta}log{beta}110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO{sub 2}{sup 2+}. This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23

  14. Biodegradability of fuel-ethers in environment; Biodegradabilite des ethers-carburants dans l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    Fayolle-Guichard, F.

    2005-04-01

    Fuel ethers (methyl tert-butyl ether or MTBE, ethyl tert-butyl ether or ETBE and tert-amyl methyl ether or TAME have been used as gasoline additives since about twenty years in order to meet the requirements for the octane index and to limit the polluting emission in exhaust pipe gas (unburnt hydrocarbons and carbon monoxide). The high water solubility and the poor biodegradability of these compounds make them pollutants frequently encountered in aquifers. The present manuscript summarizes the knowledge concerning the biodegradability of fuel ethers obtained both at IFP and during collaborations with the Pasteur Institute (Paris), the Biotechnology Research Institute (Montreal, Canada) and the Center for Environmental Biotechnology (University of Tennessee, USA). Rhodococcus ruber IFP 2001 and Mycobacterium austroafricanum IFP 2012, two microorganisms isolated at IFP for their ability to grow, respectively, on ETBE and MTBE, were studied in order to determine the intermediates produced during MTBE and ETBE biodegradation and the enzymes required for each biodegradation step, thus allowing us to propose MTBE and ETBE catabolic pathways. A proteomic approach, from the protein induced during the degradation of ETBE or MTBE to the genes encoding these different enzymes, was carried out. The isolation of such genes is required:1) to use them for help in determining the bio-remediation capacities in polluted aquifers (DNA micro-arrays), 2) to monitor the microorganisms isolated for their degradative capacities during bio-remediation processes (fluorescent in situ hybridization or FISH) and 3) to create new tools for the detection and the quantification of ETBE or MTBE in contaminated aquifers (bio-sensor). The manuscript also describes the different ways for the adaptation of microorganisms to the presence of a xenobiotic compound. (author)

  15. Zn(tbip) (H2tbip= 5-tert-butyl isophthalic acid): a highly stable guest-free microporous metal organic framework with unique gas separation capability.

    Science.gov (United States)

    Pan, Long; Parker, Brett; Huang, Xiaoying; Olson, David H; Lee, Jeongyong; Li, Jing

    2006-04-05

    A novel guest-free metal organic framework (GFMMOF) is synthesized and structurally characterized. It contains one-dimensional close-packed open channels with a pore diameter of 4.5 A. It demonstrates a remarkable thermal stability, a unique ability to separate methanol from dimethyl ether or water, and is among the microporous MOFs having the highest adsorbed hydrogen density (0.054 g/cm3 at 77 K and 1 atm).

  16. Selective liquid phase oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide over γ-Al{sub 2}O{sub 3} supported copper and gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ndolomingo, Matumuene Joe; Meijboom, Reinout, E-mail: rmeijboom@uj.ac.za

    2017-03-15

    Highlights: • Cu and Au on γ-Al{sub 2}O{sub 3} catalysts were prepared and characterized. • Benzyl alcohol oxidation to benzaldehyde was performed by tert-butyl hydroperoxide in the absence of any solvent using the prepared catalysts. • The as prepared catalysts exhibited good performance in terms of conversion and selectivity towards benzaldehyde. • The kinetics of the reaction was investigated; k{sub app} was proportional to the amount of nano catalyst and oxidant present in the system. • The catalysts was recycled and reused with neither significant loss of activity nor selectivity. - Abstract: Benzyl alcohol oxidation to benzaldehyde was performed by tert-butyl hydroperoxide (TBHP) in the absence of any solvent using γ-Al{sub 2}O{sub 3} supported copper and gold nanoparticles. Li{sub 2}O and ionic liquids were used as additive and stabilizers for the synthesis of the catalysts. The physico-chemical properties of the catalysts were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction spectroscopy (XRD), N{sub 2} absorption/desorption (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and temperature programmed reduction (TPR), whereas, the oxidation reaction was followed by gas chromatography with a flame ionization detector (GC-FID). The as prepared catalysts exhibited good catalytic performance in terms of conversion and selectivity towards benzaldehyde. The performance of the Au-based catalysts is significantly higher than that of the Cu-based catalysts. For both Cu and Au catalysts, the conversion of benzyl alcohol increased as the reaction proceeds, while the selectivity for benzaldehyde decreased. Moreover, the catalysts can be easily recycled and reused with neither significant loss of activity nor selectivity. A kinetic study for the Cu and Au-catalyzed oxidation of benzyl alcohol to benzyldehyde is reported. The rate at which the oxidation of benzyl alcohol

  17. Polystyrene-b-poly(tert-butyl acrylate) and polystyrene-b-poly(acrylic acid) dendrimer-like copolymers: two-dimensional self-assembly at the air-water interface.

    Science.gov (United States)

    Joncheray, Thomas J; Bernard, Sophie A; Matmour, Rachid; Lepoittevin, Bénédicte; El-Khouri, Rita J; Taton, Daniel; Gnanou, Yves; Duran, Randolph S

    2007-02-27

    The two-dimensional self-assembly at the air/water (A/W) interface of two dendrimer-like copolymers based on polystyrene and poly(tert-butyl acrylate) (PS-b-PtBA) or poly(acrylic acid) (PS-b-PAA) was investigated through surface pressure measurements (isotherms, isochores, and compression-expansion hysteresis experiments) and atomic force microscopy (AFM) imaging. The two dendrimer-like block copolymers have an 8-arm PS core (Mn = 10 000 g/mol, approximately 12 styrene repeat units per arm) with a 16-arm PtBA (Mn = 230 000 g/mol, approximately 112 tert-butyl acrylate repeat units per arm) or PAA (Mn = 129 000 g/mol, approximately 112 acrylic acid repeat units per arm) corona. The PS-b-PtBA sample forms stable Langmuir monolayers and aggregates into circular surface micelles up to a plateau observed in the corresponding isotherm around 24 mN/m. Beyond this threshold, the monolayers collapse above the interface, resulting in the formation of large and irregular desorbed aggregates. The PS-b-PAA sample has ionizable carboxylic acid groups, and its A/W interfacial self-assembly was therefore investigated for various subphase pH values. Under basic conditions (pH = 11), the carboxylic acid groups are deprotonated, and the PS-b-PAA sample is therefore highly water-soluble and does not form stable monolayers, instead irreversibly dissolving in the aqueous subphase. Under acidic conditions (pH = 2.5), the PS-b-PAA sample is less water-soluble and becomes surface-active. The pseudoplateau observed in the isotherm around 5 mN/m corresponds to a pancake-to-brush transition with the PAA chains dissolving in the water subphase and stretching underneath the anchoring PS cores. AFM imaging revealed the presence of circular surface micelles for low surface pressures, whereas the biphasic nature of the pseudoplateau region was confirmed with the gradual aggregation of the micellar PS cores above the PAA chains. The aggregation numbers for both samples were estimated around 3

  18. A Study of the Curing and Flammability Properties of Bisphenol A Epoxy Diacrylate Resin Utilizing a Novel Flame Retardant Monomer, bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl Phosphate

    Directory of Open Access Journals (Sweden)

    Syang-Peng Rwei

    2017-02-01

    Full Text Available A UV-curable, flame-retardant monomer, DAPP (bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl-phosphate, was synthesized based on BPDCP (4-tert-butylphenyl-dichloro phosphate and HEA (2-hydroxy ethyl acrylate. DAPP was blended with regular bisphenol A epoxy acrylate (BAEA in various ratios to yield various phosphorus contents. The TGA-IR (thermogravimetric analyzer interface with an infrared spectrometer results demonstrate that compounding 30 mol % DAPP with BAEA significantly reduced the amount of released CO gas. In contrast, the peak intensity of CO2 is independent of phosphorus content. The limiting oxygen index (LOI, reaching the saturated value of 26, and the heat release rate (HRR measured using a cone-calorimeter, 156.43 KW/m2, confirm the saturation point when 30 mol % DAPP was compounded into BAEA. A study of the kinetics of pyrolysis reveals that Ea decreases as the phosphorus content increases. Both the TGA-IR and pyrolysis results reveal that the phosphorus compound DAPP is easily decomposed during the initial stage of burning to form an insulating layer, which inhibits further burning of the resin and the consequent release of other flammable gases.

  19. Synthesis, spectroscopy, magnetic and redox behaviors of copper(II) complexes with tert-butylated salen type ligands bearing bis(4-aminophenyl)ethane and bis(4-aminophenyl)amide backbones

    Science.gov (United States)

    Kasumov, Veli T.; Yerli, Yusuf; Kutluay, Aysegul; Aslanoglu, Mehmet

    2013-03-01

    New salen type ligands, N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-ethylenedianiline [(X = H (1), 5-tert-butyl (2)] and N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-amidedianiline [X = H (3), 5-tert (4)] and their copper(II) complexes 5-8, have been synthesized. Their spectroscopic (IR, 1H NMR, UV/vis, ESR) properties, as well as magnetic and redox-reactivity behavior are reported. IR spectra of 7 and 8 indicate the coordination of amide oxygen atoms of 3 and 4 ligands to Cu(II). The solid state ESR spectra of 5-8 exhibits less informative exchange narrowed isotropic or anisotropic signals with weak unresolved low field patterns. The magnetic moments of 5 (2.92 μB per CuII) and 6 (2.79 μB per CuII) are unusual for copper(II) complexes and considerably higher than those for complexes 7 and 8. Cryogenic measurements (300-10 K) show weak antiferromagnetic exchange interactions between the copper(II) centers in complexes 6 and 8. The results of electrochemical and chemical redox-reactivity studies are discussed.

  20. Renal histopathology in toxicity and carcinogenicity studies with tert-butyl alcohol administered in drinking water to F344 rats: a pathology working group review and re-evaluation.

    Science.gov (United States)

    Hard, Gordon C; Bruner, Richard H; Cohen, Samuel M; Pletcher, John M; Regan, Karen S

    2011-04-01

    An independent Pathology Working Group (PWG) re-evaluated the kidney changes in National Toxicology Program (NTP) toxicology/carcinogenicity studies of tert-butyl alcohol (TBA) in F344/N rats to determine possible mode(s) of action underlying renal tubule tumors in male rats at 2-years. In the 13-week study, the PWG confirmed that the normal pattern of round hyaline droplets in proximal convoluted tubules was replaced by angular droplet accumulation, and identified precursors of granular casts in the outer medulla, changes typical of alpha(2u)-globulin (α(2u)-g) nephropathy. In the 2-year study, the PWG confirmed the NTP observation of increased renal tubule tumors in treated male groups. Linear papillary mineralization, another hallmark of the α(2u)-g pathway was present only in treated male rats. Chronic progressive nephropathy (CPN) was exacerbated in high-dose males and females, with a relationship between advanced grades of CPN and renal tumor occurrence. Hyperplasia of the papilla lining was a component of CPN in both sexes, but there was no pelvic urothelial hyperplasia. High-dose females showed no TBA-related nephrotoxicity. The PWG concluded that both α(2u)-g nephropathy and exacerbated CPN modes of action were operative in TBA renal tumorigenicity in male rats, neither of which has relevance for human cancer risk. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Kinetic study of the 7-endo selective radical cyclization of N-tert-butyl-o-bromobenzylmethacryl amides: kinetic investigation of the cyclization and 1,7-hydrogen transfer of aromatic radicals.

    Science.gov (United States)

    Kamimura, Akio; Kotake, Tomoko; Ishihara, Yuriko; So, Masahiro; Hayashi, Takahiro

    2013-04-19

    A kinetic investigation of the radical cyclization of N-tert-butyl-o-bromobenzylmethacryl amides to give 2-benzazepines via 7-endo selective cyclization was undertaken. The aryl radical generated from the amide precursor by treatment with Bu3SnH gave the three compounds, which are a 7-endo cyclized adduct, a 6-exocyclized adduct, and a reduced product. The cyclization reactions under various Bu3SnH concentrations were traced by GC analysis. The 7-endo/6-exo selectivity was constant irrespective of variation in Bu3SnH concentration. These results revealed that regioselectivity is controlled in a kinetic manner and that there is no possibility of a neophyl rearrangement. The use of Bu3SnD revealed that 1,7-hydrogen transfer, in which an aryl radical abstracts a hydrogen atom from the methallylic methyl group, occurs during the reaction. Hydrogen abstraction from toluene, the reaction solvent, was also observed. The 1,7-transfer rate depended on the Bu3SnX (X = H or D), and the reaction kinetics was examined. The k(H)/k(D) value for the hydrogen abstraction of aryl radical from Bu3SnX (X = H or D) was estimated using 4-bromoanisol. The utilization of these values revealed the overall reaction kinetics and relative rates for the cyclization and reduction by Bu3SnX (X = H or D). Kinetic parameters for hydrogen abstraction from toluene by aryl radicals were also estimated.

  2. Benzene and MTBE Sorption in Fine Grain Sediments

    Science.gov (United States)

    Leal-Bautista, R. M.; Lenczewski, M. E.

    2003-12-01

    The practice of adding methyl tert-butyl ether (MTBE) to gasoline started in the late 1970s and increased dramatically in the 1990s. MTBE first was added as a substitute for tetra-ethyl lead then later as a fuel oxygenate. Although the use of MTBE has resulted in significant reduction in air pollution, it has become a significant groundwater contaminant due to its high solubility in water, high environmental mobility, and low potential for biodegradation. A recent report (1999-2001) by the Metropolitan Water District of Southern California in collaboration with United State Geological Survey and the Oregon Health and Science University found that MTBE was the second most frequent detected volatile organic compound in groundwater. In Illinois, MTBE has been found in 26 of the 1,800 public water supplies. MTBE has also been blended in Mexico into two types of gasoline sold in the country by the state oil company (PEMEX) but is not monitored in groundwater at this time. Early research on MTBE considered it unable to adsorb to soils and sediments, however, by increasing the organic matter and decreasing the size of the grains (silts or clays) this may increase sorption. The objective of this study is to determine if fine grained materials have the potential for sorption of MTBE due to its high specific surface area (10-700 m 2/g) and potentially high organic matter (0.5-3.8%). The experiment consisted of sorption isotherms to glacial tills from DeKalb, Illinois and lacustrine clays from Chalco, Mexico. Experiments were performed with various concentrations of MTBE and benzene (10, 50, 100, 500 and 1000 ug/L) at 10° C and 25° C. Results showed a range of values for the distribution coefficient (Kd, linear model). At 10° C the Kd value for MTBE was 0.187 mL/g for lacustrine clay while the glacial loess had a value of 0.009 mL/g. The highest Kd values with MTBE were 0.2859 mL/g for organic rich lacustrine clays and 0.014 mL/g for glacial loess at 25° C. The highest

  3. High functional nano materials for ophthalmic lenses containing silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) and silicon 2,9,16,23-tetra-tert-butyl-29H31 H-phthalocyanine dihydroxide.

    Science.gov (United States)

    Sung, A-Young; Kim, Tae-Hun

    2014-11-01

    High functional ophthalmic lens materials, poly(HEMA-co-GMA)s were prepared by the copolymerization of HEMA, MMA, NVP, EDGMA and GMA in the presence of SiNc [silicon 2,3-naphthalocyanine bis(trihexylsilyloxide)] and SiPc (silicon 2,9,16,23-tetra-tert-butyl-29H31H-phthalocyanine dihydroxyde). Also, the physical and optical characteristics of the produced polymers were analyzed to investigate UV-blocking capabilities of these functional ophthalmic dyes and their applicability as materials for colored hydrogel contact lenses. For G_SN samples to which GMA was added to the Ref._SN combination, the transmittance for visible ray, UV-B and UV-A was in the range of 86.0-89.4%, 63.0-67.6% and 62.5-66.0% respectively. Also, for G_SP samples, the transmittance for visible ray, UV-B and UV-A was in the range of 85.2-87.0%, 70.0-72.6 and 68.0-70.2% respectively. The measurement of the spectral transmittance showed that both SiNc and SiPc absorbed a small amount of UV light, but the absorption pattern for UV light differed for each material. Based on the results, the addition of SiNc and SiPc to ophthalmic polymer materials can be used for various purposes in colored ophthalmic lens that are capable of offering protection from UV and infrared light without significant change of the physical properties.

  4. Reversal of age-related increase in brain protein oxidation, decrease in enzyme activity, and loss in temporal and spatial memory by chronic administration of the spin-trapping compound N-tert-butyl-alpha-phenylnitrone

    Energy Technology Data Exchange (ETDEWEB)

    Carney, J.M.; Starke-Reed, P.E.; Oliver, C.N.; Landum, R.W.; Cheng, M.S.; Wu, J.F.; Floyd, R.A. (Univ. of Kentucky, Lexington (USA))

    1991-05-01

    Oxygen free radicals and oxidative events have been implicated as playing a role in bringing about the changes in cellular function that occur during aging. Brain readily undergoes oxidative damage, so it is important to determine if aging-induced changes in brain may be associated with oxidative events. Previously we demonstrated that brain damage caused by an ischemia/reperfusion insult involved oxidative events. In addition, pretreatment with the spin-trapping compound N-tert-butyl-alpha-phenylnitrone (PBN) diminished the increase in oxidized protein and the loss of glutamine synthetase (GS) activity that accompanied ischemia/reperfusion injury in brain. We report here that aged gerbils had a significantly higher level of oxidized protein as assessed by carbonyl residues and decreased GS and neutral protease activities as compared to young adult gerbils. We also found that chronic treatment with the spin-trapping compound PBN caused a decrease in the level of oxidized protein and an increase in both GS and neutral protease activity in aged Mongolian gerbil brain. In contrast to aged gerbils, PBN treatment of young adult gerbils had no significant effect on brain oxidized protein content or GS activity. Male gerbils, young adults (3 months of age) and retired breeders (15-18 months of age), were treated with PBN for 14 days with twice daily dosages of 32 mg/kg. If PBN administration was ceased after 2 weeks, the significantly decreased level of oxidized protein and increased GS and neutral protease activities in old gerbils changed in a monotonic fashion back to the levels observed in aged gerbils prior to PBN administration. We also report that old gerbils make more errors than young animals and that older gerbils treated with PBN made fewer errors in a radial arm maze test for temporal and spatial memory than the untreated aged controls.

  5. Discovery of 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride as a deoxofluorinating agent with high thermal stability as well as unusual resistance to aqueous hydrolysis, and its diverse fluorination capabilities including deoxofluoro-arylsulfinylation with high stereoselectivity.

    Science.gov (United States)

    Umemoto, Teruo; Singh, Rajendra P; Xu, Yong; Saito, Norimichi

    2010-12-29

    Versatile, safe, shelf-stable, and easy-to-handle fluorinating agents are strongly desired in both academic and industrial arenas, since fluorinated compounds have attracted considerable interest in many areas, such as drug discovery, due to the unique effects of fluorine atoms when incorporated into molecules. This article describes the synthesis, properties, and reactivity of many substituted and thermally stable phenylsulfur trifluorides, in particular, 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead, 1k), as a crystalline solid having surprisingly high stability on contact with water and superior utility as a deoxofluorinating agent compared to current reagents, such as DAST and its analogues. The roles of substituents on 1k in thermal and hydrolytic stability, fluorination reactivity, and the high-yield fluorination mechanism it undergoes have been clarified. In addition to fluorinations of alcohols, aldehydes, and enolizable ketones, 1k smoothly converts non-enolizable carbonyls to CF(2) groups, and carboxylic groups to CF(3) groups, in high yields. 1k also converts C(=S) and CH(3)SC(=S)O groups to CF(2) and CF(3)O groups, respectively, in high yields. In addition, 1k effects highly stereoselective deoxofluoro-arylsulfinylation of diols and amino alcohols to give fluoroalkyl arylsulfinates and arylsulfinamides, with complete inversion of configuration at fluorine and the simultaneous, selective formation of one conformational isomer at the sulfoxide sulfur atom. Considering the unique and diverse properties, relative safety, and ease of handling of 1k in addition to its convenient synthesis, it is expected to find considerable use as a novel fluorinating agent in both academic and industrial arenas.

  6. Simultaneous liquid-liquid extraction of dibenzyl disulfide, 2,6-di-tert-butyl-p-cresol, and 1,2,3-benzotriazole from power transformer oil prior to GC and HPLC determination.

    Science.gov (United States)

    Jaber, Abdul Muttaleb Yousef; Mehanna, Nemr Ahmed; Abulkibash, Abdalla Mahmoud

    2012-03-01

    2,6-Di-tert-butyl-p-cresol (DBPC), dibenzyl disulfide (DBDS), and 1,2,3-benzotriazole (BTA) are additives that may be found concomitantly in the oil matrix of power transformer. DBPC and DBDS act as antioxidants while, BTA is a corrosion inhibitor that protects copper conductors inside the transformer unit from corrosion. A powerful analytical method is, therefore, required to determine these additives at trace levels in the transformer oil. This work describes a unique single liquid-liquid extraction pretreatment step prior to the determination of the components by gas chromatography (GC) and high-performance liquid chromatography (HPLC) techniques. The optimum volume ratio used in the pretreatment step was determined as 5:2:5 for mineral oil/n-hexane/acetonitrile, respectively. Relatively, the method is simple and quick with a minimal use of solvents. Analytical results indicate that the method is relatively sensitive, accurate, and precise for each of the three components in fresh and used mineral oil. The calibration curves for the three components demonstrate a significant increase in sensitivities. Detection limits found were, 100 mg L(-1) (0.01% w/v), 0.80 mg L(-1) , and 2.04 mg L(-1) for DBPC, DBDS, and BTA, respectively. The Student's t values determined at 95% confidence level indicate that there is no significant difference between the experimental means obtained by this method and the standard method for each component. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. EFFECT OF DE-tert-BUTYLATION AND FUNCTIONALIZATION WITH AMINE GROUPS AT THE UPPER RIM OF p-tert-BUTYLCALIX[4]ARENE TO THE EXTRACTABILITY FOR Cr3+, Cd2+ and Pb2+ IONS

    Directory of Open Access Journals (Sweden)

    Firdaus Firdaus

    2010-06-01

    Full Text Available The effects to the extractability forwards Cr3+, Cd2+, and Pb2+ ions of de-tert-butylation and functionalization with amine groups at the upper rim of p-tert-butylcalix[4]arene had been studied by applied the p-tert-butylcalix[4]arene (1, tetrahydroxycalix[4]arene (2, and p-(aminobutoxycalixarene (3 compounds as extractants for the heavy metals ions. The extraction involved optimise of three parameters, i.e. pH, time, and concentration of extractants. The extraction degrees of the heavy metals ions at optimum conditions were compared each other to decide the effects. Compound 1 showed high extractability to Cr3+ and Pb2+ ions over Cd2+ ion, but compound 2 as the debutylated product of compound 1 showed low extractability to the all of the heavy metals ions. Compound 3 as product of etherification with butyl groups of the lower rim followed functionalization with amine groups of the upper rim of compound 1 showed high extractability to Pb2+, but low to Cr3+ and Cd2+. Pursuant to the facts it was concluded that debutylation of compound 1 to compound 2 causing decrease drastically of extractability to the heavy metals ions; functionalization of the upper with amine groups as ionophore (compound 3 causing increase of the extractability to Pb2+ ion and decrease of the extractability to Cr3+ with increasing of separation factor value β(Pb2+/Cr3+ from 1.74 by compound 1 to 48.00 by compound 3. By slope analysis, the extracted species and mechanisms of the extractions have been confirmed.   Keywords: p-tert-butylcalix[4]arene, debutylation, p-(aminobutoxycalix[4]arene, extractability, heavy metals, extraction mechanisms.

  8. In Vitro Formation of 8-hydroxy-2-deoxyguanosine (8-OHdG in Calf Thymus DNA upon Treatment of 2-deoxyguanosine with Propyl Gallate and 2,6-di-tert-butyl-p-benzoquinone

    Directory of Open Access Journals (Sweden)

    Budiawan Budiawan

    2015-12-01

    Full Text Available Oxidative DNA damage caused by propyl gallate (PG and 2,6-di-tert-butyl-p-benzoquinone (BHT-quinone, a metabolite of butylated hydroxytoluene (BHT was analyzed from the 8-hydroxy-2¢-deoxyguanosine (8-OHdG formation in calf thymus DNA and DNA base, 2¢-deoxyguanosine (dG. PG in the presence of CuCl2 increased the 8-OHdG formation in calf thymus DNA by around 9.17 times as compared to the control (untreated DNA. In the presence of CuCl2 at 1.28×10-5 M, the 8-OHdG per dG ratio resulting from the reaction of dG with PG at various concentrations (20–150 ppm ranged from 75.50 to 312.06 8-OHdG per 105 dG. The 8-OHdG formation increased when the PG concentration was increased from 20 ppm to 80 ppm, and then, it began to plateau around 80 ppm. On the other hand, BHT-quinone increased the formation of 8-OHdG in the presence of CuCl2 by 0.05 times as compared to the control (untreated DNA. LC-MS/MS analysis was used to identify the molecular structure of 8-OHdG, which had a base peak (M+. + 1 at m/z = 284 and two main fragments at m/z = 167.9 and m/z = 139.9.

  9. Synthesis of [[sup 3]H]tert-butyl 8-chloro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a][1,4]benzodia zepine 3-carboxylate, a selective, high affinity ligand for the diazepam insensitive (DI) subtype of the benzodiazepine receptor

    Energy Technology Data Exchange (ETDEWEB)

    Ziqiang Gu; Costa, B.R. de; Wong, Garry; Rice, K.C.; Skolnick, Phil (National Inst. of Diabetes and Digestive and Kidney Diseases, Bethesda, MD (United States))

    1992-12-01

    The preparation of [[sup 3]H]-labelled tert-butyl 8-chloro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5-a]benzodiazepine 3-carboxylate (TCIB, 6), a high affinity ligand for the diazepam insensitive (DI) subtype of the benzodiazepine receptor (BZR) is described. Synthesis of [[sup 3]H]TCIB was accomplished in 4 steps starting from 5-chloroisatoic anhydride. Tritium-label introduction was achieved in the final step by selective catalytic tritiolysis in 62% radiochemical yield with quantitative isotopic incorporation. (Author).

  10. Structural and functional changes in proteins induced by free radical-mediated oxidative stress and protective action of the antioxidants N-tert-butyl-alpha-phenylnitrone and vitamin E.

    Science.gov (United States)

    Butterfield, D A; Koppal, T; Howard, B; Subramaniam, R; Hall, N; Hensley, K; Yatin, S; Allen, K; Aksenov, M; Aksenova, M; Carney, J

    1998-11-20

    The free radical theory of aging proposes that reactive oxygen species (ROS) cause oxidative damage over the lifetime of the subject. It is the cumulative and potentially increasing amount of accumulated damage that accounts for the dysfunctions and pathologies seen in normal aging. We have previously demonstrated that both normal rodent brain aging and normal human brain aging are associated with an increase in oxidative modification of proteins and in changes in plasma membrane lipids. Several lines of investigation indicate that one of the likely sources of ROS is the mitochondria. There is an increase in oxidative damage to the mitochondrial genome in aging and a decreased expression of mitochondrial mRNA in aging. We have used a multidisciplinary approach to the characterization of the changes that occur in aging and in the modeling of brain aging, both in vitro and in vivo. Exposure of rodents to acute normobaric hyperoxia for up to 24 h results in oxidative modifications in cytosolic proteins and loss of activity for the oxidation-sensitive enzymes glutamine synthetase and creatine kinase. Cytoskeletal protein spin labeling also reveals synaptosomal membrane protein oxidation following hyperoxia. These changes are similar to the changes seen in senescent brains, compared to young adult controls. The antioxidant spin-trapping compound N-tert-butyl-alpha-phenylnitrone (PBN) was effective in preventing all of these changes. In a related study, we characterized the changes in brain protein spin labeling and cytosolic enzyme activity in a series of phenotypically selected senescence-accelerated mice (SAMP), compared to a resistant line (SAMR1) that was derived from the same original parents. In general, the SAM mice demonstrated greater oxidative changes in brain proteins. In a sequel study, a group of mice from the SAMP8-sensitive line were compared to the SAMR1-resistant mice following 14 days of daily PBN treatment at a dose of 30 mg/kg. PBN treatment resulted

  11. N-tert-Butyl-2-methylpropanamide

    Directory of Open Access Journals (Sweden)

    Kelly A. Kluge

    2011-08-01

    Full Text Available The title compound, C8H17NO, crystallizes with two independent molecules in the asymmetric unit. In the crystal, intermolecular N—H...O hydrogen bonding is observed between neighboring molecules, forming continuous molecular chains along the c-axis direction.

  12. Phenoxaphosphine-based diphosphine ligands. Synthesis and application in the hydroformylation reaction

    NARCIS (Netherlands)

    Zuidema, E.; Goudriaan, P.E.; Swennenhuis, B.H.G.; Kamer, P.C.J.; van Leeuwen, P.W.N.M.; Lutz, M.; Spek, A.L.

    2010-01-01

    The synthesis of a new series of diphosphine ligands based on 2,7-di-tert-butyl-9,9-dimethylxanthene (1), p-tolyl ether (2), ferrocene (3), and benzene (4) backbones, containing one or two 2,8-dimethylphenoxaphosphine moieties, is reported. The ligands were employed in the rhodium-catalyzed

  13. Coal liquefaction model studies: radical-initiated and phenol-inhibited decompostition of 1,3-diphenylpropane, dibenzyl ether, and phenethyl phenyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, K.E.

    1984-01-13

    The thermal decompositions of 1,3-diphenylpropane (1), dibenzyl ether (2), and phenethyl phenyl ether (3) have been studied in the temperature range of 138-250 /sup 0/C in the presence of various free-radical initiators. Thermodynamic calculations of the conversion of 1 to toluene and styrene indicate the reaction is unfavorable below 330/sup 0/C, and 1 was found to be unreactive with di-tert-butyl peroxide (TPO) at 138 /sup 0/C, di-tert-butyldiazene (TBD) at 200 /sup 0/C, and 1,1,2,2-tetraphenylethane (TPE) at 250 /sup 0/C. Reaction of 2 to toluene and benzaldehyde and of 3 to phenol and styrene were calculated to be energetically favorable at these temperatures. 2 reacted in the presence of TPO, TBD, and TPE to give toluene, benzaldehyde, and 1,2-diphenylethane in a free-radical chain process. 3 reacted in the presence of TBD and TPE to give phenol and styrene but did not react with TPO. Reaction of 2 can be inhibited with 2,6-di-tert-butyl-4-methylphenol. With TPO as the initiator the reaction was -0.61 order in phenol, while with TBD as the initiator the reaction was -1.1 order in phenol. The change in reaction order is due to changes in the rates of the various hydrogen-transfer reaction. The hindered phenol did not inhibit reaction of 2 at temperatures above 200 /sup 0/C. The mechanisms of these reactions and the implications for coal liquification processes are discussed.

  14. Evaluation of an Innovative Technology for Treatment of Water Contaminated with Perchlorate and Organic Compounds

    Science.gov (United States)

    2009-03-26

    109  Figure 4-5: Relationship between Influent Concentrations [µg/L] for 2- Nitrotoluene ...diverse group of organics: benzene, toluene , n-hexane, n-heptane, 1-hexanol, 1-heptanol, diethyl ether, methy tert-butyl ether, diisopropyl ether, 3...chloride (VC) 8800 9,442.24 0.4916 TCE 1100 47,720.62 0.4442 PCE 150 74,344.71 0.3814 Nitrobenzene 2000 85,497.49 0.0938 2- Nitrotoluene 650

  15. Gabapentin-base synthesis and theoretical studies of biologically active compounds: N-cyclohexyl-3-oxo-2-(3-oxo-2-azaspiro[4.5] decan-2-yl)-3-arylpropanamides and N-(tert-butyl)-2-(3-oxo-2-azaspiro[4.5]decan-2-yl)-2-arylacetamide derivatives

    Science.gov (United States)

    Amirani Poor, Mahboobe; Darehkordi, Ali; Anary-Abbasinejad, Mohammad; Mohammadi, Marziyeh

    2018-01-01

    An intermolecular Ugi reaction of 2-(1-(aminomethyl)cyclohexyl)acetic acid (gabapentin) with glyoxal and cyclohexyl isocyanide or aromatic aldehyde and tertbutyl isocyanide under mild conditions in ethanol have been developed to produce two novel class of N-cyclohexyl-3-(aryl)-3-oxo-2-(3-oxo-2-azaspiro[4.5]decan-2-yl)propanamideins and N-(tert-butyl)-2-(3-oxo-2-azaspiro[4.5]decan-2-yl)-2-arylacetamide derivatives in good to excellent yields. This presents the first report for the intermolecular Ugi three component reaction of gabapentin, glyoxal, and an isocyanide. Also according to the theoretical studies the electron-donating groups increase the strength of intramolecular hydrogen bond and electron-withdrawing groups decrease the strength of intramolecular hydrogen bond.

  16. Extraction of Sodium Picrate by 3m-Crown-m Ethers and Their Monobenzo Derivatives (m = 5, 6 into Benzene: Estimation of Their Equilibrium-Potential Differences at the Less-Polar Diluent/Water Interface by an Extraction Method

    Directory of Open Access Journals (Sweden)

    Yoshihiro Kudo

    2016-01-01

    Full Text Available Individual distribution constants (KD,A of picrate ion (Pic− and extraction constants (Kex± of NaPic by some crown ethers (L into benzene (Bz at 25°C were calculated from data reported previously. These constants were defined as KD,Pic=Pic-o/[Pic-] and Kex±=NaL+oPic-o/(Na+Lo[Pic-], respectively. Here, the subscript “o” denotes an organic (o phase and practically o = Bz. 15-Crown-5 ether (15C5, 18-crown-6 one (18C6, and their monobenzo (B derivatives (B15C5 and B18C6 were selected as L. Interfacial equilibrium-potential differences (Δϕeq at extraction were estimated at 298 K. A plot of log⁡Kex± versus -Δϕeq for the four L extraction systems gave a straight line with slope = 84 V−1. This slope was compared with those, reported before, of the dichloromethane (DCM, 1,2-dichloroethane (DCE, and nitrobenzene (NB extraction systems. The slopes of the regression lines were in the order NB < DCM ≤ DCE < Bz. Also, the individual distribution constants of the complex ion NaL+ and an ion-pair complex (NaL+Pic- into Bz phase were calculated from the above extraction data. At least, a comparison between these values suggests that Bz molecules mainly interact with NaL+ moiety of NaL+Pic-.

  17. Kinetics of Methyl t-Butyl Ether Cometabolism at Low Concentrations by Pure Cultures of Butane-Degrading Bacteria

    Science.gov (United States)

    Liu, Catherine Y.; Speitel, Gerald E.; Georgiou, George

    2001-01-01

    Butane-oxidizing Arthrobacter (ATCC 27778) bacteria were shown to degrade low concentrations of methyl t-butyl ether (MTBE; range, 100 to 800 μg/liter) with an apparent half-saturation concentration (Ks) of 2.14 mg/liter and a maximum substrate utilization rate (kc) of 0.43 mg/mg of total suspended solids per day. Arthrobacter bacteria demonstrated MTBE degradation activity when grown on butane but not when grown on glucose, butanol, or tryptose phosphate broth. The presence of butane, tert-butyl alcohol, or acetylene had a negative impact on the MTBE degradation rate. Neither Methylosinus trichosporium OB3b nor Streptomyces griseus was able to cometabolize MTBE. PMID:11319100

  18. [Determination of the migration of bisphenol diglycidyl ethers from food contact materials by high performance chromatography-tandem mass spectrometry coupled with multi-walled carbon nanotubes solid phase extraction].

    Science.gov (United States)

    Wu, Xinhua; Ding, Li; Li, Zhonghai; Zhang, Yanli; Liu, Xiaoxia; Wang, Libing

    2010-11-01

    A comprehensive analytical method based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for measuring 6 exogenous endocrine disruptors--bisphenol diglycidyl ethers, including bisphenol A diglycidyl ether (BADGE), bisphenol A glycidyl (2,3-dihydroxypropyl) ether (BADGE x H2O), bisphenol A glycidyl (3-chloro-2-hydroxypropyl) ether ( BADGE x HCl), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) ether (BADGE x H2O x HCl), bisphenol F diglycidyl ether (BFDGE) and bisphenol F bis (3-chloro-2-hydroxypropyl) ether (BFDGE x 2HCl). The samples were extracted with methyl tert-butyl ether (MTBE) by ultrasonic wave assistant extraction. The extracts were cleaned up and concentrated on multi-walled carbon nanotubes (MWCNTs). The target compounds were analyzed by HPLC-MS/MS under positive ion mode using a COSMOSIL C18 column as analytical column. Under the optimal conditions, the calibration curves showed a good linearity in the concentration range of 1.0-100.0 microg/L for 6 target compounds. The correlation coefficients (r2) were higher than 0.999 1. Recoveries of 6 analytes at three spiked levels ranged from 78.6% to 89.9%, with relative standard deviations (RSDs) less than 10%. The detection limits of the method ranged from 0.5 to 1.5 microg/L. The method is sensitive and simple, and is suitable for the rapid determination of the migration of bisphenol diglycidyl ethers from food contact materials.

  19. Discovery, Synthesis, And Structure-Based Optimization of a Series of N-(tert-Butyl)-2-(N-arylamido)-2-(pyridin-3-yl) Acetamides (ML188) as Potent Noncovalent Small Molecule Inhibitors of the Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) 3CL Protease

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Jon [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Grum-Tokars, Valerie [Northwestern Univ., Chicago, IL (United States); Zhou, Ya [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Turlington, Mark [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Saldanha, S. Adrian [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Chase, Peter [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Eggler, Aimee [Purdue Univ., West Lafayette, IN (United States); Dawson, Eric S. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Baez-Santos, Yahira M. [Purdue Univ., West Lafayette, IN (United States); Tomar, Sakshi [Purdue Univ., West Lafayette, IN (United States); Mielech, Anna M. [Loyola Univ. Medical Center, Maywood, IL (United States); Baker, Susan C. [Loyola Univ. Medical Center, Maywood, IL (United States); Lindsley, Craig W. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States); Hodder, Peter [Sripps Research Inst. Molecular Screening Center, Jupiter, FL (United States); Mesecar, Andrew [Purdue Univ., West Lafayette, IN (United States); Stauffer, Shaun R. [Vanderbilt Univ., Nashville, TN (United States); Vanderbilt Specialized Chemistry Center for Probe Development (MLPCN), Nashville, TN (United States)

    2012-12-11

    A high-throughput screen of the NIH molecular libraries sample collection and subsequent optimization of a lead dipeptide-like series of severe acute respiratory syndrome (SARS) main protease (3CLpro) inhibitors led to the identification of probe compound ML188 (16-(R), (R)-N-(4-(tert-butyl)phenyl)-N-(2-(tert-butylamino)-2-oxo-1-(pyridin-3-yl)ethyl)furan-2-carboxamide, Pubchem CID: 46897844). But, unlike the majority of reported coronavirus 3CLpro inhibitors that act via covalent modification of the enzyme, 16-(R) is a noncovalent SARS-CoV 3CLpro inhibitor with moderate MW and good enzyme and antiviral inhibitory activity. A multicomponent Ugi reaction was utilized to rapidly explore structure–activity relationships within S1', S1, and S2enzyme binding pockets. Moreover, the X-ray structure of SARS-CoV 3CLpro bound with 16-(R) was instrumental in guiding subsequent rounds of chemistry optimization. 16-(R) provides an excellent starting point for the further design and refinement of 3CLpro inhibitors that act by a noncovalent mechanism of action.

  20. 4-tert-Butyl-3′,4′-bis(4-methylphenyl-3,4-dihydro-1H,4′H-spiro[naphthalene-2,5′-[1,2]oxazol]-1-one

    Directory of Open Access Journals (Sweden)

    Mohamed Akhazzane

    2011-07-01

    Full Text Available In the title compound, C30H31NO2, the cyclohexanone ring in the naphthalene fused-ring system adopts a half-chair conformation, presumably due to conjugation of the benzene ring. The naphthalene ring system makes dihedral angles of 86.63 (7, 65.15 (8 and 63.18 (8° with respect to the two methylbenzene planes and the 1,2-oxazole ring system. Intermolecular C—H...O and C—H...N hydrogen bonding and C—H...π interactions stabilize the crystal structure. The H atoms of the two methyl groups of the methylphenyl groups are disordered over two positions with equal occupancies.

  1. Synthesis of highly reactive polyisobutylene catalyzed by EtAlCl 2/Bis(2-chloroethyl) ether soluble complex in hexanes

    KAUST Repository

    Kumar, Rajeev Ananda

    2014-03-25

    The polymerization of isobutylene (IB) to yield highly reactive polyisobutylene (HR PIB) with high exo-olefin content using GaCl3 or FeCl3·diisopropyl ether complexes has been previously reported.1 In an effort to further improve polymerization rates and exo-olefin content, we have studied ethylaluminum dichloride (EADC) complexes with diisopropyl ether, 2-chloroethyl ethyl ether (CEEE), and bis(2-chloroethyl) ether (CEE) as catalysts in conjunction with tert-butyl chloride as initiator in hexanes at different temperatures. All three complexes were readily soluble in hexanes. Polymerization, however, was only observed with CEE. At 0 °C polymerization was complete in 5 min at [t-BuCl] = [EADC·CEE] = 10 mM and resulted in PIB with ∼70% exo-olefin content. Studies on complexation using ATR FTIR and 1H NMR spectroscopy revealed that at 1:1 stoichiometry a small amount of EADC remains uncomplexed. By employing an excess of CEE, exo-olefin contents increased up to 90%, while polymerization rates decreased only slightly. With decreasing temperature, polymerization rates decreased while molecular weights as well as exo-olefin contents increased, suggesting that isomerization has a higher activation energy than β-proton abstraction. Density functional theory (DFT) studies on the Lewis acid·ether binding energies indicated a trend consistent with the polymerization results. The polymerization mechanism proposed previously for Lewis acid·ether complexes1 adequately explains all the findings. © 2014 American Chemical Society.

  2. Determination of the extractive capacity of para-tert butyl calix[8]arene octa-phosphinoylated towards uranyl ions from an aqueous-acidic-salty medium; Determinacion de la capacidad extractiva del p-ter-butilocalix[8]areno octa-fosfinoilado hacia iones uranilo de un medio acuo-acido salino

    Energy Technology Data Exchange (ETDEWEB)

    Serrano V, E. C.

    2011-07-01

    The extraction properties of octa-phosphinoylated para-tert butyl calix[8]arene (prepared in the laboratory) in chloroform towards uranyl ions from an aqueous-acidic-salty medium (HNO{sub 3}-3.5 NaNO{sub 3}) containing uranyl nitrate salt, was investigated. Two spectroscopic techniques UV/Vis and Luminescence were used for this study. The latter permitted analyze the fluorescence from the uranyl ions influenced by the surrounding medium. Both permitted to learn about the power of this calixarene as extractant towards the mentioned ions. Its extraction ability or capability using this calixarene at 5.91 x 10{sup -4} M towards the uranyl ions was 400% as determined by UV/Vis while fluorescence revealed 100% of uranyl ion extraction. A closed analysis of the results obtained by using these techniques revealed that the stoichiometry of the main extracted species was 1calixarene:2 uranyl ions. The loading capacity of the calixarene ligand towards the uranyl ions was also investigated using both techniques. UV/Vis resulted to be inadequate for quantifying exactly the loading capacity of the calixarene whereas luminescence was excellent indeed, using a 5.91 x 10{sup -4} M calixarene concentration, its loading capacity was 0.157 M of free uranyl ions from 0.161 M of uranyl ions present in the aqueous-acidic-salty medium. The extracts from the ability and capacity studies were concentrated to dryness, purified and the dried extracts were analyzed by infrared and neutron activation analysis. By these techniques it was demonstrated that during the extraction of the uranyl ions by the calixarene ligand they form thermodynamically and kinetically stable complexes, since in the solid state, the 1:2, calixarene; uranyl ions stoichiometry was kept with the minimum formula: (UO{sub 2}){sub 2}B{sub 8}bL{sup 8}(NO{sub 3}){sub 4}(H{sub 2}O){sub 4}CHCl{sub 3}(CH{sub 3}OH){sub 3} the methanol molecules come from its purification. It is proposed that B{sub 8}bL{sup 8} calixarene in

  3. 7-tert-Butyl-6-(4-chloro-phenyl)-2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one, a classic polymodal inhibitor of transient receptor potential vanilloid type 1 with a reduced liability for hyperthermia, is analgesic and ameliorates visceral hypersensitivity.

    Science.gov (United States)

    Nash, Mark S; McIntyre, Peter; Groarke, Alex; Lilley, Elliot; Culshaw, Andrew; Hallett, Allan; Panesar, Moh; Fox, Alyson; Bevan, Stuart

    2012-08-01

    The therapeutic potential of transient receptor potential vanilloid type 1 (TRPV1) antagonists for chronic pain has been recognized for more than a decade. However, preclinical and clinical data revealed that acute pharmacological blockade of TRPV1 perturbs thermoregulation, resulting in hyperthermia, which is a major hurdle for the clinical development of these drugs. Here, we describe the properties of 7-tert-butyl-6-(4-chloro-phenyl)-2-thioxo-2,3-dihydro-1H-pyrido[2,3-d]pyrimidin-4-one (BCTP), a TRPV1 antagonist with excellent analgesic properties that does not induce significant hyperthermia in rodents at doses providing maximal analgesia. BCTP is a classic polymodal inhibitor of TRPV1, blocking activation of the human channel by capsaicin and low pH with IC(50) values of 65.4 and 26.4 nM, respectively. Similar activity was observed with rat TRPV1, and the inhibition by BCTP was competitive and reversible. BCTP also blocked heat-induced activation of TRPV1. In rats, the inhibition of capsaicin-induced mechanical hyperalgesia was observed with a D(50) value of 2 mg/kg p.o. BCTP also reversed visceral hypersensitivity and somatic inflammatory pain, and using a model of neuropathic pain in TRPV1 null mice we confirmed that its analgesic properties were solely through the inhibition of TRPV1. We were surprised to find that BCTP administered orally induced only a maximal 0.6°C increase in core body temperature at the highest tested doses (30 and 100 mg/kg), contrasting markedly with N-[4-({6-[4-(trifluoromethyl)phenyl]pyrimidin-4-yl}oxy)-1,3-benzothiazol-2-yl]acetamide (AMG517), a clinically tested TRPV1 antagonist, which induced marked hyperthermia (>1°C) at doses eliciting submaximal reversal of capsaicin-induced hyperalgesia. The combined data indicate that TRPV1 antagonists with a classic polymodal inhibition profile can be identified where the analgesic action is separated from the effects on body temperature.

  4. The chemical behavior of terminally tert-butylated polyolefins

    Directory of Open Access Journals (Sweden)

    Dagmar Klein

    2015-07-01

    Full Text Available The chemical behavior of various oligoenes 2 has been studied. The catalytic hydrogenation of diene 3 yielded monoene 4. Triene 7 was hydrogenated to diene 8, monoene 9 and saturated hydrocarbon 10. Bromine addition to 3 and 7 yielded the dibromides 17 and 18, respectively, i.e., the oligoene system has been attacked at its terminal olefinic carbon atoms. Analogously, the higher vinylogs 19 and 20 yielded the 1,8- and 1,10-bromine adduts 23 and 24, respectively, when less than 1 equivalent of bromine was employed. Treatment of tetraene 19 with excess bromine provided tetrabromide 25. In epoxidation reactions, both with meta-chloroperbenzoic acid (MCPBA and dimethyldioxirane (DMDO two model oligoenes were studied: triene 7 and tetraene 19. Whereas 7 furnished the rearrangement product 31 with MCPBA, it yielded the symmetrical epoxide 32 with DMDO. Analogously, 19 was converted to mono-epoxide 33 with MCPBA and to 34 with DMDO. Diels–Alder addition of 7 with N-phenyltriazolinedione (PTAD did not take place. Extension of the conjugated π-system to the next higher vinylog, 19, caused NPTD-addition to the symmetrical adduct 37 in good yield. Comparable results were observed on adding NPTD (equivalent amount to pentaene 20 and hexaene 21. Using 36 in excess provided the 2:1-adduct 40 from 21 and led to a complex mixture of adducts from heptaene 22. With tetracyanoethylene (TCNE as the dienophile, tetraolefin 19 yielded the symmetrical adduct 43, although the reaction temperature had to be increased. Pentaene 20 and hexaene 21 led to corresponding results, adducts 44 and 45 being produced in acceptable yields. With nonaene 42 and TCNE the 2:1-adduct 48 was generated according to its spectroscopic data. Exploratory photochemical studies were carried out with tetraene 19 as the model compound. On irradiation this reacted with oxygen to the stable endo-peroxide 52.

  5. N-tert-Butyl-2-methyl­propanamide

    Science.gov (United States)

    Kluge, Kelly A.; Fridyland, Diana; MacBeth, Cora E.; Hardcastle, Kenneth I.

    2011-01-01

    The title compound, C8H17NO, crystallizes with two independent mol­ecules in the asymmetric unit. In the crystal, inter­molecular N—H⋯O hydrogen bonding is observed between neighboring mol­ecules, forming continuous mol­ecular chains along the c-axis direction. PMID:22091159

  6. Occurrence and transport of MTBE in a contaminated groundwater plume from Duesseldorf

    Energy Technology Data Exchange (ETDEWEB)

    Rosell, M.; Lacorte, S.; Barcelo, D. [Dept. of Environmental Chemistry, Barcelona (Spain); Rohns, H.P.; Forner, C. [Stadtwerke Duesseldorf AG (Germany)

    2003-07-01

    In a contaminated site of Duesseldorf (middle-west of Germany), a one-year monitoring program has been carried to determine the presence and evolution of some gasoline additives in groundwater. The origin of contamination was a spill or underground storage tank leakage from a gas station. The target compounds were: methyl tert-butyl ether (MTBE), its main degradation products, tert-butyl alcohol (TBA) and tert-butyl formate (TBF); other gasoline additives, oxygenate dialkyl ethers: ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE); aromatics: benzene, toluene, ethylbenzene and xylenes (BTEX) and other compounds causing odor events in groundwater such as dicyclopentadiene (DCPD) and trichloroethylene (TCE). Purge and trap coupled to gas chromatography - mass spectrometry (P and T-GC/MS) method was used for the simultaneous determination of the above mentioned compounds and permitted to detect concentrations at ng/L (ppt) or sub-ppb concentrations. All samples analysed contained MTBE at levels varied between 0.05 -645 {micro}g/L (ppb). Three contaminated hot spots were identified with levels up to US. Environmental Protection Agency drinking water advisory (20 - 40 {micro}g/L) and one of them doubling Danish suggested toxicity level of 350 {micro}g/L. Samples with high levels of MTBE contained 0.1 - 440 {micro}g/L of TBA, indicating (but not proving) in situ degradation of parent compound. In all cases, BTEX were at low concentrations or not detected showing less solubility and persistence than MTBE.

  7. Diaqua[μ-11,23-di-tert-butyl-3,7,15,19-tetraazatricyclo[19.3.1.19,13]tetracosa-1(25,2,6,9,11,13(26,14,19,21,23-dodecaene-25,26-diolato-κ4N3,N7,O25,O26:κ4N15,N19,O25,O26]dicopper(II bis(perchlorate

    Directory of Open Access Journals (Sweden)

    Qiang Xu

    2012-08-01

    Full Text Available In the dinuclear title complex, [Cu2(C30H38N4O2(H2O2](ClO42, the coordination cation has crystallographically imposed twofold rotational symmetry. The CuII ion is five-coordinated by two N and two O atoms from the macrocylic ligand and one O atom from a water molecule, forming a square-pyramidal N2O3 geometry with the water molecule in the apical position. The distance between the two CuII atoms is 3.0930 (5 Å. Hydrogen bonds between water molecules and between water molecules and perchlorate anions assemble two cations and four anions into discrete supermolecules of S4 symmetry. Intramolecular O—H...N hydrogen bonds are also observed. The perchlorate anion and the tert-butyl group are disordered over two positions, with occupancies of the major positions of 0.527 (11 and 0.592 (9, respectively.

  8. Ceria Zirconia Mixed Oxides Prepared by Hydrothermal Templating Method for the Oxidation of Ethyl Benzene

    Directory of Open Access Journals (Sweden)

    Cimi A Daniel

    2013-12-01

    Full Text Available CeO2–ZrO2 oxides were prepared by the surfactant-templated method using cetyl trimethyl ammonium bromide (CTAB as template. These were characterized by XRD, FT-IR, TEM, SEM, BET and TPD-CO2. The XRD data showed that as prepared CeO2-ZrO2 powder particles have single phase cubic fluorite structure. HRTEM shows mesoscopic ordering. Average particle size is 12-13 nm as calculated from particle histogram. The nitrogen adsorption/desorption isotherm were classified to be type IV isotherm, typical of mesoporous material. The presence of uni-modal mesopores are confirmed by the pore size distribution which shows pore distribution at around 60 A°. The catalytic activities of the prepared material were tested in liquid phase oxidation of ethylbenzene with tert-butyl hydroperoxide (TBHP as an oxidant. Ceria zirconia catalyst modified with chromium was active for ethylbenzene conversion (65.3% with 77% selectivity towards acetophenone.  © 2013 BCREC UNDIP. All rights reservedReceived: 4th June 2013; Revised: 20th July 2013; Accepted: 18th August 2013[How to Cite: Daniel, C.A., Sugunan, S. (2013. Ceria Zirconia Mixed Oxides Prepared by Hydrothermal Templating Method for the Oxidation of Ethyl Benzene. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (2: 97-104. (doi:10.9767/bcrec.8.2.5053.97-104][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.2.5053.97-104

  9. 1-tert-butyl-3-[6-(3,5-dimethoxy-phenyl)-2-(4-diethylamino-butylamino)-pyrido[2,3-d]pyrimidin-7-yl]-urea (PD173074), a selective tyrosine kinase inhibitor of fibroblast growth factor receptor-3 (FGFR3), inhibits cell proliferation of bladder cancer carrying the FGFR3 gene mutation along with up-regulation of p27/Kip1 and G1/G0 arrest.

    Science.gov (United States)

    Miyake, Makito; Ishii, Masazumi; Koyama, Naoki; Kawashima, Kiyotaka; Kodama, Tetsuro; Anai, Satoshi; Fujimoto, Kiyohide; Hirao, Yoshihiko; Sugano, Kokichi

    2010-03-01

    Activating mutation of the fibroblast growth factor receptor-3 (FGFR3) gene is known as a key molecular event in both oncogenesis and cell proliferation of low-grade noninvasive human bladder urothelial carcinoma (UC), which is characterized by frequent intravesical recurrence. In this study, we investigated the antitumor potentiality of 1-tert-butyl-3-[6-(3,5-dimethoxy-phenyl)-2-(4-diethylamino-butylamino)-pyrido[2,3-d]pyrimidin-7-yl]-urea (PD173074), a small-molecule FGFR3-selective tyrosine kinase inhibitor (TKI), as a therapeutic modality using eight UC cell lines. In our in vitro cell proliferation assay, PD173074 suppressed cell proliferation remarkably in two cell lines, namely, UM-UC-14 and MGHU3, which expressed mutated FGFR3 protein. In contrast, the other six cell lines expressing wild-type FGFR3 or without FGFR3 expression were resistant to PD173074 treatment. Cell cycle analysis revealed the growth inhibitory effect of PD173074 was associated with arrest at G(1)-S transition in a dose-depending manner. Furthermore, we observed an inverse relationship between Ki-67 and p27/Kip1 expression after PD173074 treatment, suggesting that up-regulation of p27 recruited UC cells harboring activating FGFR3 mutations in G(1) that was analogous with the other receptor TKIs acting on the epidermal growth factor receptors. In the mouse xenograft models using subcutaneously transplanted UM-UC-14 and MGHU3, orally administered PD173074 suppressed tumor growth and induced apoptotic changes comparable with the results of our in vitro assay. These findings elucidated the effectiveness of molecular targeted approach for bladder UC harboring FGFR3 mutations and the potential utility to decrease the intravesical recurrence of nonmuscle invasive bladder UC after transurethral surgical resection.

  10. Two-year drinking water carcinogenicity study of methyl tertiary-butyl ether (MTBE) in Wistar rats.

    Science.gov (United States)

    Dodd, Darol; Willson, Gabrielle; Parkinson, Horace; Bermudez, Edilberto

    2013-07-01

    Methyl tertiary-butyl ether (MTBE) has been used as a gasoline additive to reduce tailpipe emissions and its use has been discontinued. There remains a concern that drinking water sources have been contaminated with MTBE. A two-year drinking water carcinogenicity study of MTBE was conducted in Wistar rats (males, 0, 0.5, 3, 7.5 mg ml(-1); and females, 0, 0.5, 3, and 15 mg ml(-1)). Body weights were unaffected and water consumption was reduced in MTBE-exposed males and females. Wet weights of male kidneys were increased at the end of two years of exposure to 7.5 mg ml(-1) MTBE. Chronic progressive nephropathy was observed in males and females, was more severe in males, and was exacerbated in the high MTBE exposure groups. Brain was the only tissue with a statistically significant finding of neoplasms. One astrocytoma (1/50) was found in a female rat (15 mg ml(-1)). The incidence of brain astrocytomas in male rats was 1/50, 1/50, 1/50 and 4/50 for the 0, 0.5, 3 and 7.5 mg ml(-1) exposure groups, respectively. This was a marginally significant statistical trend, but not statistically significant when pairwise comparisons were made or when multiple comparisons were taken into account. The incidence of astrocytoma fell within historical control ranges for Wistar rats, and the brain has not been identified as a target organ following chronic administration of MTBE, ethyl tert-butyl ether, or tertiary butyl alcohol (in drinking water) to mice and rats. We conclude that the astrocytomas observed in this study are not associated with exposure to MTBE. Copyright © 2011 John Wiley & Sons, Ltd.

  11. Alkaline-side extraction of technetium from tank waste using crown ethers and other extractants

    Energy Technology Data Exchange (ETDEWEB)

    Bonnesen, P.V.; Moyer, B.A.; Presley, D.J.; Armstrong, V.S.; Haverlock, T.J.; Counce, R.M.; Sachleben, R.A.

    1996-06-01

    The chemical development of a new crown-ether-based solvent-extraction process for the separation of (Tc) from alkaline tank-waste supernate is ready for counter-current testing. The process addresses a priority need in the proposed cleanup of Hanford and other tank wastes. This need has arisen from concerns due to the volatility of Tc during vitrification, as well as {sup 99}Tc`s long half-life and environmental mobility. The new process offers several key advantages that direct treatability--no adjustment of the waste composition is needed; economical stripping with water; high efficiency--few stages needed; non-RCRA chemicals--no generation of hazardous or mixed wastes; co-extraction of {sup 90}Sr; and optional concentration on a resin. A key concept advanced in this work entails the use of tandem techniques: solvent extraction offers high selectivity, while a subsequent column sorption process on the aqueous stripping solution serves to greatly concentrate the Tc. Optionally, the stripping solution can be evaporated to a small volume. Batch tests of the solvent-extraction and stripping components of the process have been conducted on actual melton Valley Storage Tank (MVST) waste as well as simulants of MVST and Hanford waste. The tandem process was demonstrated on MVST waste simulants using the three solvents that were selected the final candidates for the process. The solvents are 0.04 M bis-4,4{prime}(5{prime})[(tert-butyl)cyclohexano]-18-crown-6 (abbreviated di-t-BuCH18C6) in a 1:1 vol/vol blend of tributyl phosphate and Isopar{reg_sign} M (an isoparaffinic kerosene); 0.02 M di-t-BuCH18C6 in 2:1 vol/vol TBP/Isopar M and pure TBP. The process is now ready for counter-current testing on actual Hanford tank supernates.

  12. ANAEROBIC DEGRADATION OF MTBE TO TBA IN GROUND WATER AT GASOLINE SPILL SITES IN ORANGE COUNTY, CALIFORNIA

    Science.gov (United States)

    Although tert-Butyl Alcohol (TBA) has not been used as a fuel oxygenate in Orange County, California, the concentrations of TBA in ground water at gasoline spill sites are high compared to the concentrations of the conventional fuel oxygenate Methyl tert-Butyl Ether (MTBE). In t...

  13. Benzene from Traffic

    DEFF Research Database (Denmark)

    Palmgren, F.; Berkowicz, R.; Skov, H.

    The measurements of benzene showed very clear decreasing trends in the air concentrations and the emissions since 1994. At the same time the measurements of CO and NOx also showed a decreasing trend, but not so strong as for benzene. The general decreasing trend is explained by the increasing...... number of petrol vehicles with three way catalysts, 60-70% in 1999. The very steep decreasing trend for benzene at the beginning of the period from 1994 was explained by the combination of more catalyst vehicles and reduced benzene content in Danish petrol. The total amount of aromatics in petrol......, including toluene, increased only weakly. The analyses of air concentrations were confirmed by analyses of petrol sold in Denmark. The concentration of benzene at Jagtvej in Copenhagen is still in 1998 above the expected new EU limit value, 5 µg/m3 as annual average. However, the reduced content of benzene...

  14. Direct measurement of VOC diffusivities in tree tissues

    DEFF Research Database (Denmark)

    Baduru, K.K.; Trapp, Stefan; Burken, Joel G.

    2008-01-01

    fundamental terminal fate processes for VOCs that have been translocated from contaminated soil or groundwater, and diffusion constitutes the mass transfer mechanism to the plant−atmosphere interface. Therefore, VOC diffusion through woody plant tissues, that is, xylem, has a direct impact on contaminant fate......, and tetrachloroethane and aromatic hydrocarbons such as benzene, toluene, and methyl tert-butyl ether. All compounds tested are currently being treated at full scale with tree-based phytoremediation. Diffusivities were determined by modeling the diffusive transport data with a one-dimensional diffusive flux model...

  15. Ethyleneglycol ethers (ethyleneglycol monomethyl ether, ethyleneglycol monomethyl ether acetate, diethyleneglycol monomethyl ether, diethyleneglycol monoethyl ether and diethyleneglycol monobutyl ether).

    NARCIS (Netherlands)

    Maclaine Pont, M.A.

    1996-01-01

    The committee recommends the following exposure limits as concentrations in air averaged over 8 hours (8 h TWA): - ethyleneglycol monomethyl ether: 1 mg/m3 (0.3 ppm) - ethyleneglycol monomethyl ether acetate: 1.5 mg/3 (0.3 ppm) - diethyleneglycol monomethyl ether: 45 mg/m3 (9 ppm) - diethyleneglycol

  16. Benzene and its Isomers

    Indian Academy of Sciences (India)

    Compared to our present vast knowledge of extremely complex structures of thousands of organic compounds, the struc- .... None of the isomers, except benzene, has much practical applica- tion. Yet the fascination of both synthetic and theoretical chemists for the isomers of benzene is so great that even after about 140 ...

  17. Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

    Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...... a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means of the GC...

  18. Facts about Benzene

    Science.gov (United States)

    ... phosphorus List by Category Chemical-Specific Fact Sheets Toxicology FAQs Case Definitions Toxic Syndrome Descriptions Toxicological Profiles ... types of lubricants, rubbers, dyes, detergents, drugs, and pesticides. How you could be exposed to benzene Outdoor ...

  19. Ether: a forgotten addiction.

    Science.gov (United States)

    Krenz, Sonia; Zimmermann, Grégoire; Kolly, Stéphane; Zullino, Daniele Fabio

    2003-08-01

    Among abused inhalants, ether has recently received little attention. The case of a patient suffering from ether dependence is reported. Whereas several features of DSM-IV dependence were fulfilled, no physical withdrawal signs were observed.

  20. Leukemia and Benzene

    Directory of Open Access Journals (Sweden)

    Robert Snyder

    2012-08-01

    Full Text Available Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the numbers of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow injury, the more subtle mechanisms leading to leukemia have yet to be critically dissected. This problem appears to have more general interest because of the recognition that so-called “second cancer” that results from prior treatment with alkylating agents to yield tumor remissions, often results in a type of leukemia reminiscent of benzene-induced leukemia. Furthermore, there is a growing literature attempting to characterize the fine structure of the marrow and the identification of so called “niches” that house a variety of stem cells and other types of cells. Some of these “niches” may harbor cells capable of initiating leukemias. The control of stem cell differentiation and proliferation via both inter- and intra-cellular signaling will ultimately determine the fate of these transformed stem cells. The ability of these cells to avoid checkpoints that would prevent them from contributing to the leukemogenic response is an additional area for study. Much of the study of benzene-induced bone marrow damage has concentrated on determining which of the benzene metabolites lead to leukemogenesis. The emphasis now should be directed to understanding how benzene metabolites alter bone marrow cell biology.

  1. Leukemia and Benzene

    Science.gov (United States)

    Snyder, Robert

    2012-01-01

    Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the numbers of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow injury, the more subtle mechanisms leading to leukemia have yet to be critically dissected. This problem appears to have more general interest because of the recognition that so-called “second cancer” that results from prior treatment with alkylating agents to yield tumor remissions, often results in a type of leukemia reminiscent of benzene-induced leukemia. Furthermore, there is a growing literature attempting to characterize the fine structure of the marrow and the identification of so called “niches” that house a variety of stem cells and other types of cells. Some of these “niches” may harbor cells capable of initiating leukemias. The control of stem cell differentiation and proliferation via both inter- and intra-cellular signaling will ultimately determine the fate of these transformed stem cells. The ability of these cells to avoid checkpoints that would prevent them from contributing to the leukemogenic response is an additional area for study. Much of the study of benzene-induced bone marrow damage has concentrated on determining which of the benzene metabolites lead to leukemogenesis. The emphasis now should be directed to understanding how benzene metabolites alter bone marrow cell biology. PMID:23066403

  2. On Benzene and Aromaticity

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 4. On Benzene and Aromaticity History and Some Folklore. M V Bhatt. General Article Volume 3 Issue 4 April 1998 pp 88-93. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/003/04/0088-0093 ...

  3. Benzene and its Isomers

    Indian Academy of Sciences (India)

    At this time the concept of writing structural formulae for organic compounds had not yet been developed, ... In 1862, Loschmidt started writing a sort of ring structure for benzene with a circle symbolizing the six .... the difficult C6H6 molecules for purely academic reasons. * All the 217 structures will be given in the form of a ...

  4. benzene structure a

    African Journals Online (AJOL)

    Preferred Customer

    METHODOLOGY. Implementation of bodily-kinesthetic, musical-rhythmic and inter-personal beside logical- mathematical, visual-spatial, intelligences and systemic approach in designing benzene structure activity. This activity was designed and prepared on the basis of cooperation between Chemistry,. Sports, and Music ...

  5. Simultaneous quantification of polar and non-polar volatile organic compounds in water samples by direct aqueous injection-gas chromatography/mass spectrometry.

    Science.gov (United States)

    Aeppli, Christoph; Berg, Michael; Hofstetter, Thomas B; Kipfer, Rolf; Schwarzenbach, René P

    2008-02-15

    A direct aqueous injection-gas chromatography/mass spectrometry (DAI-GC/MS) method for trace analysis of 24 volatile organic compounds (VOCs) in water samples is presented. The method allows for the simultaneous quantification of benzene, toluene, ethyl benzene, and xylenes (BTEX), methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA), as well as a variety of chlorinated methanes, ethanes, propane, enthenes and benzenes. Applying a liquid film polyethylene glycol or a porous layer open tubular (PLOT) divinylbenzene GC capillary column to separate the water from the VOCs, volumes of 1-10 microL aqueous sample are directly injected into the GC. No enrichment or pretreatment steps are required and sample volumes as low as 100 microL are sufficient for accurate quantification. Method detection limits determined in natural groundwater samples were between 0.07 and 2.8 microg/L and instrument detection limits of water disinfection (advanced oxidation of MTBE) and for VOC concentration measurements in a polluted aquifer. The wide range of detectable compounds and the lack of labor-intensive sample preparation illustrate that the DAI method is robust and easily applicable for the quantification of important organic groundwater contaminants.

  6. Anaerobic benzene degradation by bacteria

    Science.gov (United States)

    Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans‐Hermann

    2011-01-01

    Summary Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation. PMID:21450012

  7. Kinetics and mechanism of thermolysis of dibenzyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Korobov, V.Yu.; Grigorieva, E.N.; Senko, O.V.; Kalechitz, I.V.

    1988-10-01

    The kinetics of thermolysis of dibenzyl ether in tetralin have been studied at 350-410 degrees C in a hydrogen atmosphere at 8.5 MPa pressure. A kinetic model has been proposed that satisfactorily describes the process and takes into account both the known transformation of ethers into toluene and benzaldehyde and the direct destruction of ether to benzene and toluene with elimination of CO and secondary conversions of benzaldehyde. It has been shown that at lower temperatures the first reaction prevails whereas at higher temperatures both reactions become competitive. The kinetic parameters support an intramolecular rearrangement as a pathway of the first reaction and a radical mechanism as a pathway of the second. 16 refs., 4 figs., 1 tab.

  8. Preparation and Characterization of Sulfonated Poly (ether ether ...

    African Journals Online (AJOL)

    Proton-conducting membranes of organic–inorganic (sulfonated poly (ether ether ketone)/phosphated zirconia nanoparticles) composite were prepared by incorporating various ratios of phosphated zirconia nanoparticles (ZP) in sulfonated poly (ether ether ketone) (SPEEK). SPEEK/ZP showed an improvement of ...

  9. Ether formulations of relativity

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, M.C.

    1980-12-01

    Contemporary ether theories are surveyed and criticized, especially those formally identical to orthodox Relativity. The historical development of Relativity, Special and General, in terms of an ether, is briefly indicated. Classical interpretations of Generalized Relativity using ether are compared to Euclidean formulations using a background space. The history of a sub-group of theories, formulating a 'new' Relativity involving modified transforms, is outlined. According to the theory with which they agree, recent supposed detections of drift are classified and criticized. Cosmological evidence suggesting an ether is mentioned. Only ether theories formally identical to Relativity have been published in depth. They stand criticized as being contrary to the positivist spirit. The history of mechanical analogues is traced, from Hartley's representing gravitating matter as spherical standing waves, to recent suggestions that vortex-sponge might model electromagnetic, quantum, uncertainty and faster-than-light phenomena. Contemporary theories are particular physical theories, themselves 'second interpretations' of a primary mathematical model. Mechanical analogues are auxiliary, not necessary, to other theory, disclosing relationships between classical and non-classical descriptions of assemblies charging state. The ether-relativity polemic, part of a broader dispute about relativity, is founded on mistaken conceptions of the roles of mathematical and physical models, mechanical analogues; and a distored view of history, which indicates that ether theories have become relativistic. 103 references.

  10. 4-tert-Butyl-2-[2-(1,3,3-trimethylindolin-2-ylideneethylidene]cyclohexanone

    Directory of Open Access Journals (Sweden)

    Graeme J. Gainsford

    2011-05-01

    Full Text Available The title molecule, C23H31NO, has two alternative cyclohexanone configurations at the 4-position in a ratio of 0.663 (3:0.337 (3. The plane of the five-membered planar ring in the indolin-2-ylidene subtends an angle of 2.19 (7° with its fused aromatic ring, an angle of 16.24 (8° with the plane of the major cyclohexanone configuration and an angle of 8.54 (15° with the bridging planar ethylidene C atoms. These last atoms subtend an angle of 8.37 (16° with the mean plane through the major cyclohexanone configuration. The molecules pack approximately parallel to the (overline{1}01 plane via C—H...π and C—H...O interactions.

  11. tert-Butyl 2-{[5-(4-cyanophenylpyridin-3-yl]sulfonyl}acetate

    Directory of Open Access Journals (Sweden)

    H. C. Devarajegowda

    2014-04-01

    Full Text Available In the title compound, C18H18N2O4S, the dihedral angle between the aromatic rings is 33.71 (9° and an intramolecular C—H...O hydrogen bond closes an S(6 ring. In the crystal, molecules are linked by C—H...O and C—H...N hydrogen bonds to generate a three-dimensional network. A very weak aromatic π–π stacking interction is also observed [centroid–centroid separation = 3.9524 (10 Å].

  12. N-(Fluoren-9-ylmethoxycarbonyl-l-aspartic acid 4-tert-butyl ester

    Directory of Open Access Journals (Sweden)

    Kazuhiko Yamada

    2009-11-01

    Full Text Available The bond distances and bond angles of the title compound, C23H25NO6, are consistent with values typically found for fluoren-9-ylmethoxycarbonyl-protected amino acids. The conformations of the backbone and the side chain are slightly different from those of l-aspartic acid. The crystal structure exhibits two intermolecular hydrogen bonds, forming a two-dimensional sheet structure parallel to the ab plane.

  13. 3-tert-Butyl-4-oxo-3,4-dihydrophthalazin-1-yl 3,5-dimethylbenzoate

    Directory of Open Access Journals (Sweden)

    Dao-Xin Wu

    2008-01-01

    Full Text Available The title compound, C21H22N2O3, was synthesized by the reaction of tert-butylhydrazine with phthalic anhydride and further O-benzoylation of the resulting intermediate by 3,5-dimethylbenzoyl chloride. Intermolecular C—H...O=C interactions link the molecules into layers.

  14. 4,4′-Di-tert-butyl-2,2′-bipyridine

    Directory of Open Access Journals (Sweden)

    Tatiana R. Amarante

    2009-08-01

    Full Text Available In the title compound, C18H24N2, the molecular unit adopts a trans conformation around the central C—C bond [N—C—C—N torsion angle of 179.2 (3°], with the two aromatic rings almost coplanar [dihedral angle of only 0.70 (4°]. The crystal packing is driven by co-operative contacts involving weak C—H...N and C—H...π interactions, and also the need to fill effectively the available space.

  15. 4,6-Di-tert-butyl-2,3-di-hydroxy-benzalde-hyde.

    Science.gov (United States)

    Arsenyev, Max; Baranov, Eugene; Chesnokov, Sergey; Abakumov, Gleb

    2013-01-01

    The title compound, C15H22O3, crystallizes with two independent mol-ecules in the asymmetric unit. In each mol-ecule, one hy-droxy group (at position 2) is involved in an intra-molecular O-H⋯O hydrogen bond, and another one (at position 3) exhibits bifurcated hydrogen-bonding being involved in intra- and inter-molecular O-H⋯O inter-actions. In the crystal, O-H⋯O hydrogen bonds link alternating independent mol-ecules into chains running along [010].

  16. 4,6-Di-tert-butyl-2,3-dihydroxybenzaldehyde

    Directory of Open Access Journals (Sweden)

    Max Arsenyev

    2013-10-01

    Full Text Available The title compound, C15H22O3, crystallizes with two independent molecules in the asymmetric unit. In each molecule, one hydroxy group (at position 2 is involved in an intramolecular O—H...O hydrogen bond, and another one (at position 3 exhibits bifurcated hydrogen-bonding being involved in intra- and intermolecular O—H...O interactions. In the crystal, O—H...O hydrogen bonds link alternating independent molecules into chains running along [010].

  17. Substituent Effect in Benzene Dication

    NARCIS (Netherlands)

    Palusiak, M.; Domagala, M.; Dominikowska, J.E.; Bickelhaupt, F.M.

    2014-01-01

    It was recently postulated that the benzene ring and its 4n + 2 π-electron analogues are resistant to the substituent effect due to the fact that such systems tend to retain their delocalized character. Therefore, the 4n π-electron dicationic form of benzene should appear to be less resistant to the

  18. Study of the interaction of some unsaturated hydrocarbons, simple ethers, and alcohols with sputtered iron surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Losev, V.V.; Chechel, O.V.; Kumpanenko, I.V.; Entelis, S.G.

    1989-01-01

    The method of temperature-programmed reduction has been used to study the interaction of hydrogen, ethylene, acetylene, benzene, water ethanol, ethyl ether, and ethylene oxide with sputtered iron surfaces. For the majority of compounds studied, the sole product of thermal desorption is hydrogen. The stability of the surface compounds formed was evaluated.

  19. Benzene Oxidation Coupled to Sulfate Reduction

    OpenAIRE

    Lovley, D. R.; Coates, J D; Woodward, J. C.; Phillips, E

    1995-01-01

    Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to 1 (mu)M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [(sup14)C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as (sup14)CO(inf2). Molybdate, an inhibitor of sulfate r...

  20. Activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate.

    Science.gov (United States)

    Domańska, Urszula; Marciniak, Andrzej

    2008-09-04

    The activity coefficients at infinite dilution, gamma 13 (infinity) for 32 solutes: alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofurane, tert-butyl methyl ether, and water in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate [BMIM][CF3SO3] were determined by gas-liquid chromatography at the temperatures from 298.15 to 368.15 K. The partial molar excess enthalpies at infinite dilution values Delta H 1 (E,infinity) were calculated from the experimental gamma 13 (infinity) values obtained over the temperature range. The selectivities for the hexane/benzene, cyclohexane/benzene, n-hexane/thiophene, n-decane/thiophene, cyclohexane/thiophene, toluene/thiophene, and oct-1-ene/thiophene separation problems were calculated from the gamma 13 (infinity). Obtained values were compared to the literature values for the other ionic liquids, NMP, and sulfolane.

  1. Benzene formation in electronic cigarettes.

    Directory of Open Access Journals (Sweden)

    James F Pankow

    Full Text Available The heating of the fluids used in electronic cigarettes ("e-cigarettes" used to create "vaping" aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen from e-cigarette fluids containing propylene glycol (PG, glycerol (GL, benzoic acid, the flavor chemical benzaldehyde, and nicotine.Three e-cigarette devices were used: the JUULTM "pod" system (provides no user accessible settings other than flavor cartridge choice, and two refill tank systems that allowed a range of user accessible power settings. Benzene in the e-cigarette aerosols was determined by gas chromatography/mass spectrometry. Benzene formation was ND (not detected in the JUUL system. In the two tank systems benzene was found to form from propylene glycol (PG and glycerol (GL, and from the additives benzoic acid and benzaldehyde, especially at high power settings. With 50:50 PG+GL, for tank device 1 at 6W and 13W, the formed benzene concentrations were 1.9 and 750 μg/m3. For tank device 2, at 6W and 25W, the formed concentrations were ND and 1.8 μg/m3. With benzoic acid and benzaldehyde at ~10 mg/mL, for tank device 1, values at 13W were as high as 5000 μg/m3. For tank device 2 at 25W, all values were ≤~100 μg/m3. These values may be compared with what can be expected in a conventional (tobacco cigarette, namely 200,000 μg/m3. Thus, the risks from benzene will be lower from e-cigarettes than from conventional cigarettes. However, ambient benzene air concentrations in the U.S. have typically been 1 μg/m3, so that benzene has been named the largest single known cancer-risk air toxic in the U.S. For non-smokers, chronically repeated exposure to benzene from e-cigarettes at levels such as 100 or higher μg/m3 will not be of negligible risk.

  2. Benzene formation in electronic cigarettes.

    Science.gov (United States)

    Pankow, James F; Kim, Kilsun; McWhirter, Kevin J; Luo, Wentai; Escobedo, Jorge O; Strongin, Robert M; Duell, Anna K; Peyton, David H

    2017-01-01

    The heating of the fluids used in electronic cigarettes ("e-cigarettes") used to create "vaping" aerosols is capable of causing a wide range of degradation reaction products. We investigated formation of benzene (an important human carcinogen) from e-cigarette fluids containing propylene glycol (PG), glycerol (GL), benzoic acid, the flavor chemical benzaldehyde, and nicotine. Three e-cigarette devices were used: the JUULTM "pod" system (provides no user accessible settings other than flavor cartridge choice), and two refill tank systems that allowed a range of user accessible power settings. Benzene in the e-cigarette aerosols was determined by gas chromatography/mass spectrometry. Benzene formation was ND (not detected) in the JUUL system. In the two tank systems benzene was found to form from propylene glycol (PG) and glycerol (GL), and from the additives benzoic acid and benzaldehyde, especially at high power settings. With 50:50 PG+GL, for tank device 1 at 6W and 13W, the formed benzene concentrations were 1.9 and 750 μg/m3. For tank device 2, at 6W and 25W, the formed concentrations were ND and 1.8 μg/m3. With benzoic acid and benzaldehyde at ~10 mg/mL, for tank device 1, values at 13W were as high as 5000 μg/m3. For tank device 2 at 25W, all values were ≤~100 μg/m3. These values may be compared with what can be expected in a conventional (tobacco) cigarette, namely 200,000 μg/m3. Thus, the risks from benzene will be lower from e-cigarettes than from conventional cigarettes. However, ambient benzene air concentrations in the U.S. have typically been 1 μg/m3, so that benzene has been named the largest single known cancer-risk air toxic in the U.S. For non-smokers, chronically repeated exposure to benzene from e-cigarettes at levels such as 100 or higher μg/m3 will not be of negligible risk.

  3. Cation permeable membranes from blends of sulfonated poly(ether ether ketone) and poly (ether sulfone)

    NARCIS (Netherlands)

    Wilhelm, F.G.; Punt, Ineke G.M.; van der Vegt, N.F.A.; Strathmann, H.; Wessling, Matthias

    2002-01-01

    Sulfonated poly(aryl ether ether ketone), S-PEEK, is blended with non-sulfonated poly(ether sulfone) (PES) to adjust the properties of ion permeable and ion selective membranes. In this study, membranes are prepared from blends with (i) a S-PEEK content between 10 and 100 wt.% using one S-PEEK batch

  4. 46 CFR 30.25-3 - Benzene.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more benzene...

  5. 27 CFR 21.97 - Benzene.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Benzene. 21.97 Section 21... TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled...

  6. Species differences in the metabolism of benzene

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, R.F. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States)

    1996-12-01

    The pathways of metabolism of benzene appear to be qualitatively similar in all species studied thus far. However, there are quantitative differences in the fraction of benzene metabolized by the different pathways. These species differences become important for risk assessments based on animal data. Mice have a greater overall capacity to metabolize benzene than rats or primates, based on mass balance studies conducted in vivo using radiolabled benzene. Mice and monkeys metabolize more of the benzene to hydroquinone metabolites than do rats or chimpanzees, especially at low doses. Nonhuman primates metabolize less of the benzene to muconic acid than do rodents or humans. In all species studied, a greater proportion of benzene is converted to hydroquinone and ring-breakage metabolites at low doses than at high doses. This finding should be considered in attempting to extrapolate the toxicity of benzene observed at high doses to predicted toxicity at low doses. Because ring-breakage metabolites and hydroquinone have both been implicated in the toxicity of benzene, the higher formation of those metabolites in the mouse may partially explain why mice are more sensitive to benzene than are rats. Metabolism of benzene in humans, the species of interest, does not exactly mimic that of any animal species studied. More information on the urinary and blood metabolites of occupationally exposed people is required to determine the fractional conversion of benzene to putative toxic metabolites and the degree of variability present in human subjects. 12 refs., 4 tabs.

  7. Story of skeletally substituted benzenes

    Indian Academy of Sciences (India)

    Unknown

    Indian Institute of Chemical Technology, Hyderabad 500 007, India e-mail: ... The relative energy ordering in skeletally disubstituted benzenes displays trends that are inexplicable based on conventional wisdom. In general, the ortho- ... important concept, precise definition and characterization of the concept of aromaticity is.

  8. Benzene-1,3,5-triyl tribenzoate

    Directory of Open Access Journals (Sweden)

    Amy M. Balija

    2013-12-01

    Full Text Available The title compound, C27H18O6, commonly known as phloroglucinol tribenzoate, is a standard unit for the family of benzyl ether dendrimers. The central phloroglucinol residue is close to planar, with out-of-plane distances for the three oxygen atoms of up to 0.095 (3 Å, while the three attached benzoate groups are approximately planar. One benzoate group is twisted [C—C—O—C torsion angle = 98.2 (3°] from the central plane, with its carbonyl O atom 2.226 (4 Å above that plane, while the other two benzoate groups are twisted in the opposite direction [C—C—O—C torsion angles = 24.7 (2 and 54.8 (2°], so that their carbonyl O atoms are on the other side of, and closer to the central plane, with distances from the plane of 1.743 (4 and 1.206 (4 Å. One benzoate group is disordered between two conformers, with occupancies of 86.9 (3 and 13.1 (3%, related by a 143 (1° rotation about the bond to the central benzene ring. The phenyl groups of the two conformers occupy the same space. The molecule packs in the crystal with two of the three benzoate phenyl rings stacked parallel to symmetry-related counterparts, with perpendicular distances of 3.715 (5 and 3.791 (5 Å. The parallel rings are slipped away from each other, however, with centroid–centroid distances of 4.122 (2 and 4.363 (2 Å, respectively.

  9. 46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

    Science.gov (United States)

    2010-10-01

    ... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or butyl...

  10. Ether space-time & cosmology

    CERN Document Server

    Levy, Joseph

    2008-01-01

    The aim of this first volume of papers is to examine the different paths by which the modern ether concept has been developed and to highlight the part it plays in major departments of 21st century physics. The evidence for its existence is reviewed, and it is hoped, widespread misconceptions concerning ether are corrected. It is anticipated that the emerging modern concept of ether will play a fundamental part in the development of 21st century physical science.

  11. Exogenous ether lipids predominantly target mitochondria

    DEFF Research Database (Denmark)

    Kuerschner, Lars; Richter, Doris; Hannibal-Bach, Hans Kristian

    2012-01-01

    Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high...... amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically labeled using the corresponding lyso-ether lipids, which we established as supreme precursors for lipid tagging. Polyfosine, a fluorescent analogue of the anti-neoplastic ether lipid edelfosine...... in ether lipid metabolism and intracellular ether lipid trafficking....

  12. On the Use of Potential Denaturing Agents for Ethanol in Direct Ethanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Domnik Bayer

    2011-01-01

    Full Text Available Acidic or alkaline direct ethanol fuel cells (DEFCs can be a sustainable alternative for power generation if they are fuelled with bio-ethanol. However, in order to keep the fuel cheap, ethanol has to be exempted from tax on spirits by denaturing. In this investigation the potential denaturing agents fusel oil, tert-butyl ethyl ether, and Bitrex were tested with regard to their compatibility with fuel cells. Experiments were carried out both in sulphuric acid and potassium hydroxide solution. Beside, basic electrochemical tests, differential electrochemical mass spectrometry (DEMS and fuel cell tests were conducted. It was found that fusel oil is not suitable as denaturing agent for DEFC. However, tert-butyl ethyl ether does not seem to hinder the ethanol conversion as much. Finally, a mixture of tert-butyl ethyl ether and Bitrex can be proposed as promising candidate as denaturing agent for use in acidic and alkaline DEFC.

  13. The atmosphere can be a source of certain water soluble volatile organic compounds in urban streams

    Science.gov (United States)

    Kenner, Scott J.; Bender, David A.; Zogorski, John S.; ,; James F. Pankow,

    2014-01-01

    Surface water and air volatile organic compound (VOC) data from 10 U.S. Geological Survey monitoring sites were used to evaluate the potential for direct transport of VOCs from the atmosphere to urban streams. Analytical results of 87 VOC compounds were screened by evaluating the occurrence and detection levels in both water and air, and equilibrium concentrations in water (Cws) based on the measured air concentrations. Four compounds (acetone, methyl tertiary butyl ether, toluene, and m- & p-xylene) were detected in more than 20% of water samples, in more than 10% of air samples, and more than 10% of detections in air were greater than long-term method detection levels (LTMDL) in water. Benzene was detected in more than 20% of water samples and in more than 10% of air samples. Two percent of benzene detections in air were greater than one-half the LTMDL in water. Six compounds (chloroform, p-isopropyltoluene, methylene chloride, perchloroethene, 1,1,1-trichloroethane, and trichloroethene) were detected in more than 20% of water samples and in more than 10% of air samples. Five VOCs, toluene, m- & p-xylene, methyl tert-butyl ether (MTBE), acetone, and benzene were identified as having sufficiently high concentrations in the atmosphere to be a source to urban streams. MTBE, acetone, and benzene exhibited behavior that was consistent with equilibrium concentrations in the atmosphere.

  14. Biodegradation of gasoline ether oxygenates.

    Science.gov (United States)

    Hyman, Michael

    2013-06-01

    Ether oxygenates such as methyl tertiary butyl ether (MTBE) are added to gasoline to improve fuel combustion and decrease exhaust emissions. Ether oxygenates and their tertiary alcohol metabolites are now an important group of groundwater pollutants. This review highlights recent advances in our understanding of the microorganisms, enzymes and pathways involved in both the aerobic and anaerobic biodegradation of these compounds. This review also aims to illustrate how these microbiological and biochemical studies have guided, and have helped refine, molecular and stable isotope-based analytical approaches that are increasingly being used to detect and quantify biodegradation of these compounds in contaminated environments. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. 21 CFR 868.5420 - Ether hook.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ether hook. 868.5420 Section 868.5420 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5420 Ether hook. (a) Identification. An ether hook is a device that fits inside a patient's mouth and that is intended to deliver vaporized ether. (b) Classification...

  16. Ether the nothing that connects everything

    CERN Document Server

    Milutis, Joe

    2006-01-01

    In Ether, the histories of the unseen merge with discussions of the technology of electromagnetism. Navigating more than three hundred years of the ether''s cultural and artistic history, Joe Milutis reveals its continuous reinvention and tangible impact without ever losing sight of its ephemeral, elusive nature. The true meaning of ether, Milutis suggests, may be that it can never be fully grasped.

  17. Anaerobic Benzene Oxidation by Geobacter Species

    Science.gov (United States)

    Bain, Timothy S.; Nevin, Kelly P.; Barlett, Melissa A.; Lovley, Derek R.

    2012-01-01

    The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 109 and 8.4 × 109 cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 109 cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated. PMID:23001648

  18. Rearrangements of Cycloalkenyl Aryl Ethers

    Directory of Open Access Journals (Sweden)

    Mercedesz Törincsi

    2016-04-01

    Full Text Available Rearrangement reactions of cycloalkenyl phenol and naphthyl ethers and the acid-catalyzed cyclization of the resulting product were investigated. Claisen rearrangement afforded 2-substituted phenol and naphthol derivatives. Combined Claisen and Cope rearrangement resulted in the formation of 4-substituted phenol and naphthol derivatives. In the case of cycloocthylphenyl ether the consecutive Claisen and Cope rearrangements were followed by an alkyl migration. The mechanism of this novel rearrangement reaction is also discussed.

  19. 46 CFR 151.50-60 - Benzene.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of a...

  20. 46 CFR 153.1060 - Benzene.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060 Benzene...

  1. 29 CFR 1915.1028 - Benzene.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical to...

  2. 29 CFR 1926.1128 - Benzene.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene. Note...

  3. Benzene degradation in a denitrifying biofilm reactor

    NARCIS (Netherlands)

    Waals, van der Marcelle J.; Atashgahi, Siavash; Rocha, da Ulisses Nunes; Zaan, van der Bas M.; Smidt, Hauke; Gerritse, Jan

    2017-01-01

    Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more

  4. Volatilization of Benzene in a River

    Directory of Open Access Journals (Sweden)

    Eric Dunlop

    2013-01-01

    Full Text Available Benzene is a volatile organic compound: when it contaminates a river, some of the substance will evaporate as it flows through. We examine the volumetric flow rate to find how volatilization affects the concentration levels of benzene as the substance flows through several consecutive sections of a river, using a specific example to illustrate the general method.

  5. Protective effect of nuclear factor E2-related factor 2 on inflammatory cytokine response to brominated diphenyl ether-47 in the HTR-8/SVneo human first trimester extravillous trophoblast cell line

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hae-Ryung, E-mail: heaven@umich.edu; Loch-Caruso, Rita

    2014-11-15

    Polybrominated diphenyl ethers (PBDEs) are widely used flame retardants, and BDE-47 is a prevalent PBDE congener detected in human tissues. Exposure to PBDEs has been linked to adverse pregnancy outcomes in humans. Although the underlying mechanisms of adverse birth outcomes are poorly understood, critical roles for oxidative stress and inflammation are implicated. The present study investigated antioxidant responses in a human extravillous trophoblast cell line, HTR-8/SVneo, and examined the role of nuclear factor E2-related factor 2 (Nrf2), an antioxidative transcription factor, in BDE-47-induced inflammatory responses in the cells. Treatment of HTR-8/SVneo cells with 5, 10, 15, and 20 μM BDE-47 for 24 h increased intracellular glutathione (GSH) levels compared to solvent control. Treatment of HTR-8/SVneo cells with 20 μM BDE-47 for 24 h induced the antioxidant response element (ARE) activity, indicating Nrf2 transactivation by BDE-47 treatment, and resulted in differential expression of redox-sensitive genes compared to solvent control. Pretreatment with tert-butyl hydroquinone (tBHQ) or sulforaphane, known Nrf2 inducers, reduced BDE-47-stimulated IL-6 release with increased ARE reporter activity, reduced nuclear factor kappa B (NF-κB) reporter activity, increased GSH production, and stimulated expression of antioxidant genes compared to non-Nrf2 inducer pretreated groups, suggesting that Nrf2 may play a protective role against BDE-47-mediated inflammatory responses in HTR-8/SVneo cells. These results suggest that Nrf2 activation significantly attenuated BDE-47-induced IL-6 release by augmentation of cellular antioxidative system via upregulation of Nrf2 signaling pathways, and that Nrf2 induction may be a potential therapeutic target to reduce adverse pregnancy outcomes associated with toxicant-induced oxidative stress and inflammation. - Highlights: • BDE-47 stimulated ARE reporter activity and GSH production. • BDE-47 resulted in differential

  6. Current collapse in tunneling transport through benzene.

    Science.gov (United States)

    Hettler, M H; Wenzel, W; Wegewijs, M R; Schoeller, H

    2003-02-21

    We investigate the electrical transport through a system of benzene coupled to metal electrodes by electron tunneling. Using electronic structure calculations, a semiquantitative model for the pi electrons of the benzene is derived that includes general two-body interactions. After exact diagonalization of the benzene model the transport is computed using perturbation theory for weak electrode-benzene coupling (golden rule approximation). We include the effect of an applied electric field on the molecular states, as well as radiative relaxation. We predict a current collapse and strong negative differential conductance due to a "blocking" state when the electrode is coupled to the para-position of benzene. In contrast, for coupling to the meta-position, a series of steps in the I-V curve is found.

  7. The mechanism of hyperoside protection of ECV-304 cells against tert-butyl hydroperoxide-induced injury.

    Science.gov (United States)

    Li, Hai Bo; Yi, Xin; Gao, Jian Mei; Ying, Xi Xiang; Guan, Hong Quan; Li, Jian Chun

    2008-01-01

    The aim of the present study was to investigate the mechanism of hyperoside protecting ECV-304 cells against tertbutyl hydroperoxide (TBHP)-induced injury. ECV-304 cell viability was measured by MTT assay. Cellular morphologic changes were observed using phase contrast microscopy. The genotoxic effects of TBHP and the protective ability of hyperoside were assessed by the Comet test. Lipid peroxidation was measured by HPLC method. The cellular redox status was determined from GSH/GSSG ratios. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay. Western blot analysis was used to evaluate the levels of cytochrome c, p53, SIRT1, Bax and Bcl-2 expression. The results showed that 128 mumol/l hyperoside could effectively protect TBHP-treated ECV-304 cells from death, increase superoxide dismutase activity and significantly decrease malondialdehyde production. Hyperoside was effective in protecting against the induction of oxidized DNA bases and redox state alterations induced by TBHP. Furthermore, the release of proapoptotic cytochrome c from mitochondria was reduced by hyperoside, which increased the expression of antiapoptotic SIRT1 and inhibited the translocation of Bax from cytoplasm to mitochondria. Taken together, these results indicate that hyperoside is effective in protecting against the oxidative damage induced by TBHP. The mechanism of hyperoside protecting against ECV-304 cell apoptosis by TBHP is related with resuming mitochondrial function and regulating the expression of SIRT1 and Bcl-2 family members. Copyright 2008 S. Karger AG, Basel.

  8. Synthesis of Hindered Anilines: Three-Component Coupling of Arylboronic Acids, tert-Butyl Nitrite, and Alkyl Bromides.

    Science.gov (United States)

    Fisher, David J; Shaum, James B; Mills, C Landon; Read de Alaniz, Javier

    2016-10-07

    The synthesis of sterically hindered amines has been a significant challenge in organic chemistry. Herein, we report a modular, three-component coupling that constructs two carbon-nitrogen bonds including a sterically hindered C sp 3 -N bond using commercially available materials. This process uses an earth-abundant copper catalyst and mild reaction conditions, allowing access to a variety of complex aromatic amines.

  9. Synthesis of Hindered Anilines: Three-Component Coupling of Arylboronic Acids, tert-Butyl Nitrite, and Alkyl Bromides.

    OpenAIRE

    Fisher, DJ; Shaum, JB; Mills, CL; Read de Alaniz, J

    2016-01-01

    The synthesis of sterically hindered amines has been a significant challenge in organic chemistry. Herein, we report a modular, three-component coupling that constructs two carbon-nitrogen bonds including a sterically hindered Csp(3)-N bond using commercially available materials. This process uses an earth-abundant copper catalyst and mild reaction conditions, allowing access to a variety of complex aromatic amines.

  10. tert-Butyl N-((1S-2-hydroxy-1-{N′-[(1E-4-methoxybenzylidene]hydrazinecarbonyl}ethylcarbamate

    Directory of Open Access Journals (Sweden)

    Alessandra C. Pinheiro

    2011-07-01

    Full Text Available The molecule of the title compound, C16H23N3O5, is twisted about the chiral C atom, the dihedral angle formed between the amide residues being 79.6 (3°. The conformation about the imine bond [1.278 (5 Å] is E. In the crystal, O—H...O and N—H...O hydrogen bonding between the hydroxy, amine and carbonyl groups leads to the formation of supramolecular layers, which stack along the c-axis direction.

  11. 4,6-Di-tert-butyl-2,3-di­hydroxy­benzalde­hyde

    Science.gov (United States)

    Arsenyev, Max; Baranov, Eugene; Chesnokov, Sergey; Abakumov, Gleb

    2013-01-01

    The title compound, C15H22O3, crystallizes with two independent mol­ecules in the asymmetric unit. In each mol­ecule, one hy­droxy group (at position 2) is involved in an intra­molecular O—H⋯O hydrogen bond, and another one (at position 3) exhibits bifurcated hydrogen-bonding being involved in intra- and inter­molecular O—H⋯O inter­actions. In the crystal, O—H⋯O hydrogen bonds link alternating independent mol­ecules into chains running along [010]. PMID:24098244

  12. 2-tert-Butyl-1-(4-nitroamino-1,2,5-oxadiazol-3-yldiazene 1-oxide

    Directory of Open Access Journals (Sweden)

    Xiang-Zhi Li

    2012-07-01

    Full Text Available In the title compound, C6H10N6O4, the nitroamine –NHNO2 substituent and the C–N=N(→ O unit of the other substituent of the oxadiazole ring are nearly coplanar with the five-membered ring [dihedral angles = 5.7 (1 and 3.0 (1°]. The amino group of the –NHNO2 substituent is a hydrogen-bond donor to the two-coordinate N atom of the C—N=N(→ O unit.

  13. Simultaneous Removal of MTBE and Benzene from Contaminated Groundwater Using Ultraviolet-Based Ozone and Hydrogen Peroxide

    Directory of Open Access Journals (Sweden)

    Bassam S. Tawabini

    2014-01-01

    Full Text Available Efficiency of ultraviolet-ozone (UV/O3 and ultraviolet-hydrogen peroxide (UV/H2O2 processes was investigated for simultaneous removal of methyl tertiary butyl ether (MTBE and benzene from contaminated ground water. The photoreactor employed housed 15-watt low pressure (LP and 150-watt medium pressure (MP mercury UV lamps. Oxidation of contaminants was studied at two different levels of ozone and hydrogen peroxide. Brackish groundwater samples were spiked with MTBE and benzene up to a concentration of 500 μg L−1. Removal potential was evaluated at different parameters such as UV type and intensity and peroxide and ozone dosages, as well as contact time. Results indicated that no removal of the contaminants was attained when treated with hydrogen peroxide or ozone alone. However, about 50% and 30% removal of MTBE were achieved in 30 minutes when irradiated with MP-UV and LP-UV lamps, respectively. On the other hand, UV/H2O2 process was found to be superior in removal of MTBE (90% in 10 min. and benzene (95% in 5 min. compared to UV/O3 process. Furthermore, removal of benzene was comparatively easier than MTBE in both approaches. It is hence concluded that higher UV intensities and elevated doses of H2O2 accelerate simultaneous removal of MTBE and benzene from water.

  14. Interphase cytogenetics of workers exposed to benzene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.; Wang, Yunxia; Venkatesh, P. [Univ. of California, Berkeley, CA (United States)] [and others

    1996-12-01

    Fluorescence in situ hybridization (FISH) is a powerful new technique that allows numerical chromosome aberrations (aneuploidy) to be detected in interphase cells. In previous studies, FISH has been used to demonstrate that the benzene metabolites hydroquinone and 1,2,4-benzenetriol induce aneuploidy of chromosomes 7 and 9 in cultures of human cells. In the present study, we used an interphase FISH procedure to perform cytogenetic analyses on the blood cells of 43 workers exposed to benzene (median=31 ppm, 8-hr time-weighted average) and 44 matched controls from Shanghai, China. High benzene exposure (>31 ppm, n=22) increased the hyperdiploid frequency of chromosome 9 (p<0.01), but lower exposure (<31 ppm, n=21) did not. Trisomy 9 was the major form of benzene-induced hyperdiploidy. The level of hyperdiploidy in exposed workers correlated with their urinary phenol level (r= 0.58, p < 0.0001), a measure of internal benzene close. A significant correlation was also found between hyperdiploicly and decreased absolute lymphocyte count, an indicator of benzene hematotoxicity, in the exposed group (r=-0.44, p=0.003) but not in controls (r=-0.09, P=0.58). These results show that high benzene exposure induces aneuploidy of chromosome 9 in nondiseased individuals, with trisomy being the most prevalent form. They further highlight the usefulness of interphase cytogenetics and FISH for the rapid and sensitive detection of aneuploidy in exposed human populations. 35 refs., 3 figs., 2 tabs.

  15. Recent Advances of Poly(ether-ether) and Poly(ether-ester) Block Copolymers in Biomedical Applications.

    Science.gov (United States)

    He, Zhi-Yao; Shi, Kun; Wei, Yu-Quan; Qian, Zhi-Yong

    2016-01-01

    Poly(ether-ether) and poly(ether-ester) block copolymers have been widely applied in biomedical fields over two decades due to their good safety and biocompatibility. Poly(ethylene glycol), poly(ethylene glycol)-poly(propylene glycol) and poly(lactic-co-glycolic acid) have been approved as excipients by Food and Drug Administration. Because of the broad perspective in biomedical fields, many novel poly(etherether) and poly(ether-ester) block copolymers have been developed for drug delivery, gene therapy and tissue engineering in recent years. This review focuses on active targeting theranostic systems, gene delivery systems and tissue engineering based on poly(ether-ether) and poly(ether-ester) block copolymers. We perform a structured search of bibliographic databases for peer-reviewed scientific reports using a focused review question and inclusion/exclusion criteria. The literatures related to the topics of this review are cataloged according to the developed copolymers or their applications such as active targeting theranostic systems, gene delivery systems and tissue engineering. Some important advances and new trends are summarized in this review. Some commercial poly(ether-ether) copolymers have been used as excipients for drug research and development. Amphiphilic and biodegradable poly(ether-ester) diblock copolymers are capable of formulating biomedical nanoparticulate theranostic systems, and targeting moiety-functionalized poly(ether-ester) diblock copolymers will be further developed and applied in biomedical nanotechnology fields in the near future. Meanwhile, triblock or multiblock poly(ether-ether) and poly(ether-ester) copolymers with environmentsensitive properties are suitable for gene delivery and tissue engineering. Poly(ether-ether) and poly(ether-ester) copolymers are being extensively applied in active targeting theranostic systems, gene delivery systems and tissue engineering. Biodegradable, environment-sensitive and targeting moiety

  16. Benzene formation in Titan's lower atmosphere

    Science.gov (United States)

    Plane, J. M. C.; Douglas, K.; Blitz, M. A.; Heard, D. E.; Seakins, P. W.; Feng, W.; Willacy, K.

    2017-09-01

    The most distinctive feature of Saturn's moon Titan is that it is covered in a thick haze. The haze consists of organic particles called tholins, of which benzene is thought to be an important precursor. Here we examine two pathways to form benzene. The first involves reactions on cosmic dust particles, which mostly do not ablate when entering Titan's atmosphere and accumulate in the lower atmosphere. We have shown in the laboratory that acetylene molecules stick on synthetic cosmic dust at low temperatures, and react efficiently to make benzene. The second pathway is through gas phase reactions involving radical species formed through methane photochemistry. A new lab study shows that the rates of critical reactions involving these radicals vary unexpectedly at low temperatures, leading to significant changes in important benzene precursors.

  17. Exogenous ether lipids predominantly target mitochondria.

    Directory of Open Access Journals (Sweden)

    Lars Kuerschner

    Full Text Available Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically labeled using the corresponding lyso-ether lipids, which we established as supreme precursors for lipid tagging. Polyfosine, a fluorescent analogue of the anti-neoplastic ether lipid edelfosine, accumulated to mitochondria and induced morphological changes and cellular apoptosis. These data indicate that edelfosine could exert its pro-apoptotic power by targeting and damaging mitochondria and thereby inducing cellular apoptosis. In general, this study implies an important role of mitochondria in ether lipid metabolism and intracellular ether lipid trafficking.

  18. Monovalent cation selective crown ether containing poly(arylene ether ketone)/SPEEK blend membranes

    NARCIS (Netherlands)

    Tas, Sinem; Zoetebier, Bram; Hempenius, Mark A.; Vancso, Gyula J.; Nijmeijer, Dorothea C.

    2016-01-01

    Blend membranes of sulfonated poly(ether ether ketone) (SPEEK) and poly(arylene ether ketone) (PAEK) derivatives containing crown ether units in the main chain (CPAEK) were prepared and characterized in terms of water swelling and ion exchange capacity (IEC). The miscibility of the polymers was

  19. Perfluorocyclobutyl Aryl Ether-Based ABC Amphiphilic Triblock Copolymer

    Science.gov (United States)

    Xu, Binbin; Yao, Wenqiang; Li, Yongjun; Zhang, Sen; Huang, Xiaoyu

    2016-12-01

    A series of fluorine-containing amphiphilic ABC triblock copolymers comprising hydrophilic poly(ethylene glycol) (PEG) and poly(methacrylic acid) (PMAA), and hydrophobic poly(p-(2-(4-biphenyl)perfluorocyclobutoxy)phenyl methacrylate) (PBPFCBPMA) segments were synthesized by successive atom transfer radical polymerization (ATRP). First, PEG-Br macroinitiators bearing one terminal ATRP initiating group were prepared by chain-end modification of monohydroxy-terminated PEG via esterification reaction. PEG-b-PBPFCBPMA-Br diblock copolymers were then synthesized via ATRP of BPFCBPMA monomer initiated by PEG-Br macroinitiator. ATRP polymerization of tert-butyl methacrylate (tBMA) was directly initiated by PEG-b-PBPFCBPMA-Br to provide PEG-b-PBPFCBPMA-b-PtBMA triblock copolymers with relatively narrow molecular weight distributions (Mw/Mn ≤ 1.43). The pendant tert-butyoxycarbonyls were hydrolyzed to carboxyls in acidic environment without affecting other functional groups for affording PEG-b-PBPFCBPMA-b-PMAA amphiphilic triblock copolymers. The critical micelle concentrations (cmc) were determined by fluorescence spectroscopy using N-phenyl-1-naphthylamine as probe and the self-assembly behavior in aqueous media were investigated by transmission electron microscopy. Large compound micelles and bowl-shaped micelles were formed in neutral aqueous solution. Interestingly, large compound micelles formed by triblock copolymers can separately or simultaneously encapsulate hydrophilic Rhodamine 6G and hydrophobic pyrene agents.

  20. 40 CFR 721.3437 - Dialkyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dialkyl ether. 721.3437 Section 721... Dialkyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as dialkyl ether (PMN P-93-1308) is subject to reporting under this section...

  1. 40 CFR 721.3374 - Alkylenediolalkyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkylenediolalkyl ether. 721.3374... Substances § 721.3374 Alkylenediolalkyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as an alkylenediolalkyl ether (PMN P-93-362) is subject to...

  2. 40 CFR 721.3380 - Anilino ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Anilino ether. 721.3380 Section 721... Anilino ether. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as anilino ether (P-83-910) is subject to reporting under this section for...

  3. 40 CFR 721.3364 - Aliphatic ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aliphatic ether. 721.3364 Section 721... Aliphatic ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as an aliphatic ether (PMN P-93-1381) is subject to reporting under this...

  4. Rhodium-catalyzed synthesis of diaryl sulfides using aryl fluorides and sulfur/organopolysulfides.

    Science.gov (United States)

    Arisawa, Mieko; Ichikawa, Takuya; Yamaguchi, Masahiko

    2012-10-19

    Substituted pentafluorobenzenes react with sulfur to give bis(4-substituted 2,3,5,6-tetrafluorophenyl) sulfides in the presence of RhH(PPh(3))(4), 1,2-bis(diphenylphosphino)benzene (dppBz), and tributylsilane. The reaction proceeds efficiently between room temperature and 80 °C. A comparative study of the reactivities of an organic trisulfide and a tetrasulfide showed notable substrate specificity. Di-tert-butyl tetrasulfide reacted with reactive aryl monofluorides and substituted pentafluorobenzenes. Di-tert-butyl trisulfide reacted with aryl monofluorides. The reactivity was explained on the basis of the difference in S-S bond energy.

  5. Isotope fractionation of benzene during partitioning - Revisited.

    Science.gov (United States)

    Kopinke, F-D; Georgi, A; Imfeld, G; Richnow, H-H

    2017-02-01

    Isotope fractionation between benzene-D0 and benzene-D6 caused by multi-step partitioning of the benzenes between water and two organic solvents, n-octane and 1-octanol, as well as between water and the gas phase, was measured. The obtained fractionation factors αH = KH/KD are αH = 1.080 ± 0.015 and αH = 1.074 ± 0.015 for extraction into n-octane and 1-octanol, respectively, and αH = 1.049 ± 0.010 for evaporation from aqueous solution. The comparison of solvent- and gas-phase partitioning reveals that about 2/3 of the driving force of fractionation is due to different interactions in the aqueous phase, whereas 1/3 is due to different interactions in the organic phase. The heavy benzene isotopologue behaves more 'hydrophilically' and the light one more 'hydrophobically'. This synergistic alignment gives rise to relatively large fractionation effects in partitioning between water and non-polar organic matter. In contrast to a previous study, there is no indication of strong fractionation by specific interactions between benzene and octanol. Partitioning under non-equilibrium conditions yields smaller apparent fractionation effects due to opposite trends of thermodynamic and kinetic fractionation parameters, i.e. partition and diffusion coefficients of the isotopologues. This may have consequences which should be taken into account when considering isotope fractionation due to sorption in environmental compartments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Anaerobic Benzene Oxidation via Phenol in Geobacter metallireducens

    Science.gov (United States)

    Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar; Smith, Jessica A.; Bain, Timothy S.; Lovley, Derek R.

    2013-01-01

    Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with 18O during growth in H218O, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation. PMID:24096430

  7. Hydrogen storage by functionalised Poly(ether ether ketone)

    Energy Technology Data Exchange (ETDEWEB)

    Pedicini, R.; Giacoppo, G.; Carbone, A.; Passalacqua, E. [CNR-ITAE, Messina (Italy). Inst. for Advanced Energy Technologies

    2010-07-01

    In this work a functionalised polymer was studied as potential material for hydrogen storage in solid state. A Poly(ether ether ketone) (PEEK) matrix was modified by a manganese oxide in situ formation. Here we report the functionalisation process and the preliminary results on hydrogen storage capability of the synthesised polymer. The polymer was characterized by Scanning Electron Microscopy, X-ray diffraction, Transmission Electron Microscopy and Gravimetric Hydrogen Adsorption measurements. In the functionalised PEEK, morphological changes occur as a function of oxide precursor concentration and reaction time. Promising results by gravimetric measurements were obtained with a hydrogen sorption of 0.24%wt/wt at 50 C and 60 bar, moreover, reversibility hydrogen adsorption and desorption in a wide range of both temperature and pressure was confirmed. (orig.)

  8. Benzene monitoring at CPPI service stations

    Energy Technology Data Exchange (ETDEWEB)

    Davis, C.S. [Bovar, Inc., Calgary, AB (Canada)

    1996-03-01

    A study was conducted in which ambient airborne concentration levels of benzene were measured at a representative set of gasoline service stations in Toronto and Vancouver. Benzene is considered to be toxic under the Canadian Environmental Protection Act (CEPA). It is a component in gasoline (0.1 to 4.7 per cent by volume) and is present in vehicle evaporative and exhaust emissions. Measurements were made every 18 days at each station for one year. The objective of the study was to assess the ambient and employee exposure levels of benzene at service stations and to determine whether the levels were typical of those published in the literature. In a 1986 PACE (Petroleum Association for Conservation of the Canadian Environment) survey of exposure to gasoline hydrocarbon vapours at Canadian service stations, airborne benzene concentration data was inconsistent with similar ambient and personal exposure data in the international literature. It was concluded that both the mean ambient benzene concentration and the personal exposure level measurements in this study were generally lower than similar measurements made in other countries. The same observation was made with respect to ambient and personal exposure levels measured in this study vis-a-vis those measured during the PACE study conducted in 1985/86. . 31 refs., 24 tabs., 5 figs.

  9. CHEMOMETRICS IN BIOANALYTICAL SAMPLE PREPARATION - A FRACTIONATED COMBINED MIXTURE AND FACTORIAL DESIGN FOR THE MODELING OF THE RECOVERY OF 5 TRICYCLIC AMINES FROM PLASMA AFTER LIQUID-LIQUID-EXTRACTION PRIOR TO HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

    NARCIS (Netherlands)

    WIELING, J; MENSINK, CK; JONKMAN, JHG; COENEGRACHT, PMJ; DUINEVELD, CAA; DOORNBOS, DA

    1993-01-01

    A general systematic approach is described for the chemometric modelling of liquid-liquid extraction data of drugs from biological fluids. Extraction solvents were selected from Snyder's solvent selectivity triangle: methyl tert.-butyl ether, methylene chloride and chloroform. The composition of a

  10. Quantifying residues from postharvest fumigation of almonds and walnuts with propylene oxide

    Science.gov (United States)

    A novel analytical approach, involving solvent extraction with methyl tert-butyl ether (MTBE) followed by gas chromatography (GC), was developed to quantify residues that result from the postharvest fumigation of almonds and walnuts with propylene oxide (PPO). Verification and quantification of PPO,...

  11. Iron Amendment and Fenton Oxidation of MTBE-Spent Granular Activated Carbon

    Science.gov (United States)

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves Fe amendment to the GAC to catalyze H2O2 reactions and to enhance the rate of MTBE oxidation and GAC regeneration. Four forms of iron (ferric sulfate, ferric chloride, fer...

  12. Persulfate Oxidation of MTBE- and Chloroform-Spent Granular Activated Carbon

    Science.gov (United States)

    Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2–persulfate binary mixtur...

  13. Fenton-like Degradation of MTBE: Effects of Iron Counter Anion and Radical Scavengers

    Science.gov (United States)

    Fenton-driven oxidation of Methyl tert-butyl ether (MTBE) (0.11-0.16 mM) in batch reactors containing ferric iron (5 mM), hydrogen peroxide (H2O2) (6 mM) (pH=3) was performed to investigate MTBE transformation mechanisms. Independent variables included the form of iron (Fe) (Fe2(...

  14. Fenton-Driven Regeneration of MTBE-spent Granular Activated Carbon

    Science.gov (United States)

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto activated carbon and Fenton-driven oxidation regeneration of the spent-GAC...

  15. SUMMARY OF WORKSHOP ON BIODEGRADATION OF MTBE FEBRUARY 1-3, 2000

    Science.gov (United States)

    A workshop on biodegradation of methyl tert butyl ether (MTBE) contaminated soils and groundwater was held in Cincinnati, Ohio, February 1-2, 2000, and was sponsored by the USEPA's NRMRL and the American Petroleum Institute. Researchers in academia, industry, and government were ...

  16. Conversion of methanol and isobutanol to MTBE

    CSIR Research Space (South Africa)

    Nicolaides, CP

    1993-09-24

    Full Text Available Over the resin catalyst Amberlyst 15, and under our reaction conditions, the yield of MTBE (methyl tert-butyl ether), from the reaction of methanol and isobutene, is at a maximum in the temperature rang of 40-60-degrees-C. Slightly higher...

  17. The industrial production of dimethyl carbonate from methanol and carbon dioxide

    NARCIS (Netherlands)

    De Groot, Frank F T; Lammerink, Roy R G J; Heidemann, Casper; Van Der Werff, Michiel P M; Garcia, Taiga Cafiero; Van Der Ham, Louis A G J; Van Den Berg, Henk

    2014-01-01

    This work discusses the design of a dimethyl carbonate (DMC) production plant based on methanol and CO2 as feed materials, which are a cheap and environment-friendly feedstock. DMC is a good alternative for methyl-tert-butyl ether (MTBE) as a fuel oxygenating agent, due to its low toxicity and fast

  18. An on-line normal-phase high performance liquid chromatography method for the rapid detection of radical scavengers in non-polar food matrixes

    NARCIS (Netherlands)

    Zhang, Q.; van der Klift, E.J.C.; Janssen, H.-G.; van Beek, T.A.

    2009-01-01

    An on-line method for the rapid pinpointing of radical scavengers in non-polar mixtures like vegetable oils was developed. To avoid problems with dissolving the sample, normal-phase chromatography on bare silica gel was used with mixtures of hexane and methyl tert-butyl ether as the eluent. The high

  19. De aanwezigheid van methyl tert-butylether (MTBE) in drinkwater en drinkwaterbronnen

    NARCIS (Netherlands)

    Morgenstern PP; Korte GAL de; Hogendoorn EA; Versteegh JFM; LWD; IEM

    2002-01-01

    In 2001 the National Institute for Public Health and the Environment (RIVM) in the Netherlands conducted a drinking water measurement programme in co-operation with the Netherlands Waterworks Association (VEWIN) for methyl tert-butyl ether (MTBE) in drinking water and the corresponding sources. This

  20. Analysis of Fluorotelomer Alcohols in Soils: Optimization of Extraction and Chromatography

    Science.gov (United States)

    This article describes the development of an analytical method for the determination of fluorotelomer alcohols (FTOHs) in soil. The sensitive and selective determination of the telomer alcohols was performed by extraction with mthyl tert-butyl ether (MTBE) and analysis of the ext...

  1. Effect of Water Clustering on the Activity of Candida antarctica Lipase B in Organic Medium

    DEFF Research Database (Denmark)

    Banik, Sindrila Dutta; Nordblad, Mathias; Woodley, John M.

    2017-01-01

    The effect of initial water activity of MTBE (methyl tert-butyl ether) medium on CALB (Candida antarctica lipase B) catalyzed esterification reaction is investigated using experimental methods and classical molecular dynamics (MD) simulations. The experimental kinetic studies show that the initial...

  2. Model description and kinetic parameter analysis of MTBE biodegradation in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A dynamic modeling approach was used to estimate in-situ model parameters, which describe the degradation of methyl tert-butyl ether (MTBE) in a laboratory packed bed reactor. The measured dynamic response of MTBE pulses injected at the reactor's inlet was analyzed by least squares and parameter...

  3. An Efficient Method for the Preparative Isolation and Purification of Flavonoid Glycosides and Caffeoylquinic Acid Derivatives from Leaves of Lonicera japonica Thunb. Using High Speed Counter-Current Chromatography (HSCCC) and Prep-HPLC Guided by DPPH-HPLC Experiments

    National Research Council Canada - National Science Library

    Wang, Daijie; Du, Ning; Wen, Lei; Zhu, Heng; Liu, Feng; Wang, Xiao; Du, Jinhua; Li, Shengbo

    2017-01-01

    .... japonica using high speed counter-current chromatography (HSCCC) and prep-HPLC. The n-butanol extract was firstly isolated by HSCCC using methyl tert-butyl ether/n-butanol/acetonitrile/water (0.5% acetic acid) (2:2:1:5, v/v...

  4. Peer Review Comments on the IRIS Assessment of Benzene

    Science.gov (United States)

    Attachment to IRIS file for benzene, January 19, 2000, RESPONSE TO THE PEER REVIEW COMMENTS, II. Extrapolation of the Benzene Inhalation Unit Risk Estimate to the Oral Route of Exposure (EPA/NCEA-W-0517, July 1999)

  5. Ruthenium ammine/crown ether interactions in solution: Effects of modification of both guest and host on the strength of second-sphere complexation

    Energy Technology Data Exchange (ETDEWEB)

    Todd, M.D.; Yuhua Dong; Horney, J.; Yoon, D.I.; Hupp, J.T. (Northwestern Univ., Evanston, IL (United States))

    1993-05-12

    Charge-transfer absorption, electrochemical, and NMR-NOE studies of monomeric and dimeric (ligand-bridged) ruthenium ammine guest interactions with several crown ether hosts show that second-sphere complexation is prevalent in nitromethane as solvent and that complexation or binding constants can be varied by ca. 10[sup 8]-fold by modifying both guest and host properties. For hosts, larger binding constants are obtained with larger macrocycles and with more flexible macrocycles (i.e. dicyclohexano vs dibenzo crowns). For guests, larger binding constants are observed in higher oxidation states and in the presence of strongly electron-withdrawing ancillary ligands. In all cases, binding appears to be driven primarily by ammine hydrogen/ether oxygen (Lewis acid/base) interactions. Evidence is also found, however, for contributions from favorable benzene(crown)/pyridine(complex) interactions and (apparently) benzene(crown) [yields] Ru(III) charge-transfer (donor/acceptor) interactions. 17 refs., 3 figs., 2 tabs.

  6. Evaluation of benzene-related petroleum processing operations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Briggs; Patel, V.P.

    1978-10-01

    This report describes refinery processing of liquids with high benzene concentrations. Processes which are addressed include aromatics extraction (both sulfolane and glycol solvent processes), toluene dealkylation, and toluene disproportionation. Each process is described and modeled. In addition, a list and characterization of the 45 plants in the United States processing liquids with high benzene concentrations is presented. Characteristics include, where possible, company name, plant location, benzene process, and benzene production rate.

  7. Benzene derivatives produced by Fusarium graminearum - Short communication.

    Science.gov (United States)

    Ntushelo, Khayalethu; Setshedi, Itumeleng

    2015-06-01

    Using NMR spectroscopy benzene derivatives were detected in mycelia of Fusarium graminearum, a pathogen of wheat and maize. In previous studies F. graminearum was found to cause cancer to humans and benzene derivatives were detected in breath of cancer sufferers. Surprisingly, no study found benzene derivatives to be the cancerous agents in F. graminearum. In this study we detected benzene derivatives in F. graminearum and propose to study their role as cancer agents.

  8. 40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (1-methylethyl)(2...

  9. 40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject to...

  10. 40 CFR 721.1187 - Bis(imidoethylene) benzene.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to reporting...

  11. Vacuum ultraviolet photoabsorption spectroscopy of crystalline and amorphous benzene

    DEFF Research Database (Denmark)

    Dawes, Anita; Pascual, Natalia; Hoffmann, Soren V.

    2017-01-01

    We present the first high resolution vacuum ultraviolet photoabsorption study of amorphous benzene with com parisons to annealed crystalline benzene and the gas phase. Vapour deposited benzene layers w ere grow n at 25 K and annealed to 90 K under conditions pertinent to interstellaricy dust grains...

  12. Benzene reduction in RFG, a new low cost route

    Energy Technology Data Exchange (ETDEWEB)

    Gildert, R.; Gildert, G.

    1994-12-31

    Benzene has been targeted for reduction in reformulated gasoline because it is the largest single contributor to the toxic emissions group. This presentation describes processes of benzene removal for the petroleum refiner. By making maximum use of existing equipment, the refiner can minimize the changes necessary to produce reformulated gasoline with a reduction in benzene levels.

  13. 40 CFR 721.10028 - Disubstituted benzene metal salts (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Disubstituted benzene metal salts... Specific Chemical Substances § 721.10028 Disubstituted benzene metal salts (generic). (a) Chemical... as disubstituted benzene metal salts (PMNs P-01-901 and P-01-902) are subject to reporting under this...

  14. Formation of Benzene in the Interstellar Medium

    Science.gov (United States)

    Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.; Crim, F. Fleming (Editor)

    2010-01-01

    Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block-the aromatic benzene molecule-has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3- butadiene, C2H + H2CCHCHCH2 --> C6H6, + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadlene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium.

  15. Three coordination compounds based on benzene tetracarboxylate ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 129; Issue 8. Three coordination compounds based on benzene tetracarboxylate ligand: syntheses, structures, thermal behaviors and luminescence properties. YUNLONG WU CHANGKUN XIA JUN QIAN JIMIN XIE. REGULAR ARTICLE Volume 129 Issue 8 August ...

  16. Formation of benzene in the interstellar medium

    Science.gov (United States)

    Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.

    2011-01-01

    Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block—the aromatic benzene molecule—has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3-butadiene, C2H + H2CCHCHCH2 → C6H6 + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadiene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium. PMID:21187430

  17. Friction behavior of 304 stainless steel of varying hardness lubricated with benzene and some benzyl structures

    Science.gov (United States)

    Buckley, D. H.

    1974-01-01

    The lubricating properties of some benzyl and benzene structures were determined by using 304 stainless steel surfaces strained to various hardness. Friction coefficients and wear track widths were measured with a Bowden-Leben type friction apparatus by using a pin-on-disk specimen configuration. Results obtained indicate that benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol resulted in the lowest friction coefficients for 304 stainless steel, while benzyl ether provided the least surface protection and gave the highest friction. Strainhardening of the 304 stainless steel prior to sliding resulted in reduced friction in dry sliding. With benzyl monosulfide, dibenzyl disulfide, and benzyl alcohol changes in 304 stainless steel hardness had no effect upon friction behavior.

  18. Unusually high aromaticity and diatropicity of bond-alternate benzene.

    Science.gov (United States)

    Aihara, Jun-Ichi; Ishida, Toshimasa

    2010-01-21

    Enormous effort has been devoted to the elucidation of possible effects of bond-length alternation on the benzene pi-system. Benzene tends to stay highly aromatic and highly diatropic even if strong bond-length alternation is introduced artificially into the pi-system. Such peculiar aromatic and magnetic characters of benzene were justified consistently and unambiguously within a single theoretical framework. From all physically sound points of view, bond-alternate benzene is highly aromatic with a large aromatic stabilization energy. We confirmed that in the annulene family benzene is least sensitive in aromaticity to bond-length alternation.

  19. 54 FR 38044: National Emission Standards for Hazardous Air Pollutants; Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By- Product Recovery Plants

    Science.gov (United States)

    Final Rule on National Emission Standards for Hazardous Air Pollutants; Benzene Emissions From Maleic Anhydride Plants, Ethylbenzene/Styrene Plants, Benzene Storage Vessels, Benzene Equipment Leaks, and Coke By-Product Recovery Plants.

  20. Comparison of Properties among Dendritic and Hyperbranched Poly(ether ether ketones and Linear Poly(ether ketones

    Directory of Open Access Journals (Sweden)

    Atsushi Morikawa

    2016-02-01

    Full Text Available Poly(ether ether ketone dendrimers and hyperbranched polymers were prepared from 3,5-dimethoxy-4′-(4-fluorobenzoyldiphenyl ether and 3,5-dihydroxy-4′-(4-fluorobenzoyldiphenyl ether through aromatic nucleophilic substitution reactions. 1-(tert-Butyldimethylsiloxy-3,5-bis(4-fluorobenzoylbenzene was polycondensed with bisphenols, followed by cleavage of the protective group to form linear poly(ether ketones having the same hydroxyl groups in the side chains as the chain ends of the dendrimer and hyperbranched polymers. Their properties, such as solubilities, reduced viscosities, and thermal properties, were compared with one another. Similar comparisons were also carried out among the corresponding methoxy group polymers, and the size of the molecules was shown to affect the properties.

  1. Conformational Study of Dibenzyl Ether

    Science.gov (United States)

    Hernandez-Castillo, Alicia O.; Abeysekera, Chamara; Hewett, Daniel M.; Zwier, Timothy S.

    2017-06-01

    Understanding the initial stages of polycyclic aromatic hydrocarbon (PAH) aggregation, the onset of soot formation, is an important goal on the pathway to cleaner combustion processes. PAHs with short alkyl chains, present in fuel-rich combustion environments, can undergo reactions that will chemically link aromatic rings together. One such example of a linked diaryl compound is dibenzyl ether, C_{6}H_{5}-CH_{2}-O-CH_{2}-C_{6}H_{5}. The -CH_{2}-O-CH_{2}- linkage has a length and flexibility well-suited to forming a π-stacked conformation between the two phenyl rings. In this talk, we will explore the single-conformation spectroscopy of dibenzyl ether under jet-cooled conditions in the gas phase. Laser-induced fluorescence, chirped pulse Fourier transform microwave (8-18 GHz region), and single-conformation infrared spectroscopy in the alkyl CH stretch region were all carried out on the molecule, thereby interrogating its full array of electronic, vibrational and rotational degrees of freedom. This work is the first step in a broader study to determine the extent of π-stacking in linked aryl compounds as a function of linkage and PAH size.

  2. 27 CFR 21.108 - Ethyl ether.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ethyl ether. 21.108 Section 21.108 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT....108 Ethyl ether. (a) Odor. Characteristic odor. (b) Specific gravity at 15.56 °/15.56 °C. Not more...

  3. The synthesis of cholesteryl alkyl ethers.

    Science.gov (United States)

    Halperin, G; Gatt, S

    1980-01-01

    Seventeen cholesteryl alkyl ethers were synthesized through alcoholysis of cholesterol p-toluenesulfonate. This method was found superior to the etherification of sodium or potassium cholesterylate with alkyl halides or methanesulfonates, especially for the preparation of long-chain unsaturated aklyl ethers of [7(m)-3H]cholesterol of high specific activity.

  4. Metatranscriptome of an Anaerobic Benzene-Degrading, Nitrate-Reducing Enrichment Culture Reveals Involvement of Carboxylation in Benzene Ring Activation

    Science.gov (United States)

    Luo, Fei; Gitiafroz, Roya; Devine, Cheryl E.; Gong, Yunchen; Hug, Laura A.; Raskin, Lutgarde

    2014-01-01

    The enzymes involved in the initial steps of anaerobic benzene catabolism are not known. To try to elucidate this critical step, a metatranscriptomic analysis was conducted to compare the genes transcribed during the metabolism of benzene and benzoate by an anaerobic benzene-degrading, nitrate-reducing enrichment culture. RNA was extracted from the mixed culture and sequenced without prior mRNA enrichment, allowing simultaneous examination of the active community composition and the differential gene expression between the two treatments. Ribosomal and mRNA sequences attributed to a member of the family Peptococcaceae from the order Clostridiales were essentially only detected in the benzene-amended culture samples, implicating this group in the initial catabolism of benzene. Genes similar to each of two subunits of a proposed benzene-carboxylating enzyme were transcribed when the culture was amended with benzene. Anaerobic benzoate degradation genes from strict anaerobes were transcribed only when the culture was amended with benzene. Genes for other benzoate catabolic enzymes and for nitrate respiration were transcribed in both samples, with those attributed to an Azoarcus species being most abundant. These findings indicate that the mineralization of benzene starts with its activation by a strict anaerobe belonging to the Peptococcaceae, involving a carboxylation step to form benzoate. These data confirm the previously hypothesized syntrophic association between a benzene-degrading Peptococcaceae strain and a benzoate-degrading denitrifying Azoarcus strain for the complete catabolism of benzene with nitrate as the terminal electron acceptor. PMID:24795366

  5. Adsorption of benzene derivatives on allophane

    OpenAIRE

    Nishikiori, Hiromasa; Shindoh, Junichi; TAKAHASHI, Nobukazu; Takagi, Tomohiro; Tanaka, Nobuaki; Fujii, Tsuneo

    2009-01-01

    The adsorption properties of benzene derivatives from water on allophane, extracted from soil, have been investigated by UV and FTIR spectroscopic measurements. Allophane adsorbs benzoic acid, phthalic acid, benzaldehyde, ethyl benzoate, and diethyl phthalate. Benzoic acid, phthalic acid, and benzaldehyde formed carboxylate anions on the positive sites of the hydrated alumina surface of allophane. In the case of adsorption from an acidic solution (pH 2), a small amount of a neutral species of...

  6. Acetylcholinesterase and Acetylcholine Receptor

    Science.gov (United States)

    1985-01-21

    trimethylammonio- acetate, (CH 3 ) 3 N* CH2 CO2 CH3 , tert-butyl peracetate, (CH3) 3 C- OOCOCH3 , methyl methanesulfonate, CH3 SO2 0CH3 , methyl benzene - sulfonate ...recovered. Enzyme was assayed by the Ellman procedure (16). Sodium dodecyl sulfate (SDS) polyacrylamide gel equipment was assembled and procedures for assay...Other Potential Irreversible Inhibitors 13 Reversible Inhibitors 14 Benzene Derivatives as Inhibitors and Accelerators 15 Substrates 16 Discussion and

  7. Exposure Evaluation for Benzene, Lead and Noise in Vehicle and Equipment Repair Shops

    Energy Technology Data Exchange (ETDEWEB)

    Sweeney, Lynn C. [Washington State Univ., Pullman, WA (United States)

    2013-04-01

    An exposure assessment was performed at the equipment and vehicle maintenance repair shops operating at the U. S. Department of Energy Hanford site, in Richland, Washington. The maintenance shops repair and maintain vehicles and equipment used in support of the Hanford cleanup mission. There are three general mechanic shops and one auto body repair shop. The mechanics work on heavy equipment used in construction, cranes, commercial motor vehicles, passenger-type vehicles in addition to air compressors, generators, and farm equipment. Services include part fabrication, installation of equipment, repair and maintenance work in the engine compartment, and tire and brake services. Work performed at the auto body shop includes painting and surface preparation which involves applying body filler and sanding. 8-hour time-weighted-average samples were collected for benzene and noise exposure and task-based samples were collected for lead dust work activities involving painted metal surfaces. Benzene samples were obtained using 3M™ 3520 sampling badges and were analyzed for additional volatile organic compounds. These compounds were selected based on material safety data sheet information for the aerosol products used by the mechanics for each day of sampling. The compounds included acetone, ethyl ether, toluene, xylene, VM&P naphtha, methyl ethyl ketone, and trichloroethylene. Laboratory data for benzene, VM&P naphtha, methyl ethyl ketone and trichloroethylene were all below the reporting detection limit. Airborne concentrations for acetone, ethyl ether, toluene and xylene were all less than 10% of their occupational exposure limit. The task-based samples obtained for lead dusts were submitted for a metal scan analysis to identify other metals that might be present. Laboratory results for lead dusts were all below the reporting detection limit and airborne concentration for the other metals observed in the samples were less than 10% of the occupational exposure limit

  8. Benzene patterns in different urban environments and a prediction model for benzene rates based on NOx values

    Science.gov (United States)

    Paz, Shlomit; Goldstein, Pavel; Kordova-Biezuner, Levana; Adler, Lea

    2017-04-01

    Exposure to benzene has been associated with multiple severe impacts on health. This notwithstanding, at most monitoring stations, benzene is not monitored on a regular basis. The aims of the study were to compare benzene rates in different urban environments (region with heavy traffic and industrial region), to analyse the relationship between benzene and meteorological parameters in a Mediterranean climate type, to estimate the linkages between benzene and NOx and to suggest a prediction model for benzene rates based on NOx levels in order contribute to a better estimation of benzene. Data were used from two different monitoring stations, located on the eastern Mediterranean coast: 1) a traffic monitoring station in Tel Aviv, Israel (TLV) located in an urban region with heavy traffic; 2) a general air quality monitoring station in Haifa Bay (HIB), located in Israel's main industrial region. At each station, hourly, daily, monthly, seasonal, and annual data of benzene, NOx, mean temperature, relative humidity, inversion level, and temperature gradient were analysed over three years: 2008, 2009, and 2010. A prediction model for benzene rates based on NOx levels (which are monitored regularly) was developed to contribute to a better estimation of benzene. The severity of benzene pollution was found to be considerably higher at the traffic monitoring station (TLV) than at the general air quality station (HIB), despite the location of the latter in an industrial area. Hourly, daily, monthly, seasonal, and annual patterns have been shown to coincide with anthropogenic activities (traffic), the day of the week, and atmospheric conditions. A strong correlation between NOx and benzene allowed the development of a prediction model for benzene rates, based on NOx, the day of the week, and the month. The model succeeded in predicting the benzene values throughout the year (except for September). The severity of benzene pollution was found to be considerably higher at the

  9. Novel sulfonated poly(ether ether ketone ketone)s for direct methanol fuel cells usage: Synthesis, water uptake, methanol diffusion coefficient and proton conductivity

    Science.gov (United States)

    Zhang, Gang; Fu, Tiezhu; Shao, Ke; Li, Xianfeng; Zhao, Chengji; Na, Hui; Zhang, Hong

    A novel series of sulfonated poly(ether ether ketone ketone)s (SPEEKKs) with different degrees of sulfonation (Ds) were synthesized from 1,3-bis(3-sodium sulfonate-4-fluorobenzoyl)benzene (1,3-SFBB-Na), 1,3-bis(4-fluorobenzoyl)benzene (1,3-FBB) and 3,3‧,5,5‧-tetramethyl-4,4‧-biphenol (TMBP) by aromatic nucleophilic polycondensation. The chemical structures of SPEEKKs were confirmed by FT-IR spectroscopy and the Ds values of the polymers were calculated by 1H NMR and titration methods, respectively. The thermal stabilities of the SPEEKKs in acid and sodium forms were characterized by thermogravimetric analysis (TGA), which showed that SPEEKKs had excellent thermal properties at high temperatures. All the SPEEKK polymers were easily solution cast into tough membranes. Water uptakes, proton conductivities and methanol diffusion coefficients of the SPEEKK membranes were measured. Water uptake increased with Ds and temperature. Compared to Nafion, the SPEEKK-60, -70 and -80 membranes showed higher proton conductivities at 80 °C, while the other SPEEKK membranes showed relatively lower proton conductivities. This may be due to the different distribution of ion-conducting domains in membrane. However, these membranes showed lower methanol diffusions in the range of 8.32 × 10 -9 to 1.14 × 10 -7 cm 2 s -1 compared with that of Nafion (2 × 10 -6 cm 2 s -1) at the same temperature. The membranes also showed excellent mechanical properties (with a Young's modulus > 1 GPa and a tensile strength > 40 MPa). These results indicate that the SPEEKK membranes are promising materials for use in direct methanol fuel cell (DMFC) applications.

  10. Atmospheric lifetimes of selected fluorinated ether compounds

    DEFF Research Database (Denmark)

    Heathfield, A.E.; Anastasi, C.; Pagsberg, Palle Bjørn

    1998-01-01

    Atmospheric lifetimes have been estimated for a selection of ethers, the latter representing a class of compounds being considered as replacements for chlorofluorocarbons. The estimates are based on laboratory measurements of rate constants for the reaction of the OH radical with the ethers......, and a comparison with the behaviour of methyl chloroform in the atmosphere. The lifetimes for the ethers ranged from a few hours to half a year, significantly lower than those of chlorofluorocarbons and other replacements being considered. (C) 1998 Elsevier Science Ltd. All rights reserved....

  11. Stratospheric benzene and hydrocarbon aerosols observed in Saturn's upper atmosphere

    Science.gov (United States)

    Guerlet, S.; Koskinen, T.

    2017-09-01

    We review recent observations of benzene and hydrocarbon aerosols in Saturn's middle and upper atmosphere by Cassini/CIRS and Cassini/UVIS. These results support the link between the precipitation of energetic electrons (ion chemistry) and the production of benzene and aerosols in Saturn's polar regions, and that solar-driven ion chemistry could also play a significant role in producing benzene at low and mid-latitudes. We also evaluate the radiative impact of the haze on Saturn's stratospheric temperatures.

  12. The solubilities of benzene polycarboxylic acids in water

    Energy Technology Data Exchange (ETDEWEB)

    Apelblat, Alexander [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel)]. E-mail: apelblat@bgu.ac.il; Manzurola, Emanuel [Department of Chemical Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Abo Balal, Nazmia [Negev Academic College of Engineering, Beer Sheva (Israel)

    2006-05-15

    The solubilities in water of all benzene polycarboxylic acids are discussed, using data determined in this work (benzoic, terephthalic, trimellitic, trimesic, and pyromellitic acids) and available from the literature (benzoic, phthalic, isophthalic, terephthalic, hemimellitic, trimelitic, trimesic, mellophanic, prehnitic, pyromellitic, benzene-pentacarboxylic and mellitic acids). The apparent molar enthalpies of solution at the saturation point for these benzene polycarboxylic acids were determined from the temperature dependence of the solubilities.

  13. Clinical comparison of ethyl acetate and diethyl ether in the formalin-ether sedimentation technique.

    OpenAIRE

    Erdman, D D

    1981-01-01

    A substitute for the volatile solvent diethyl ether has been actively sought for the Formalin-ether sedimentation technique. Ethyl acetate has recently been shown to be a comparable substitute. In an effort to verify these findings and evaluate ethyl acetate under clinical conditions, comparison studies with 62 fresh human stool specimens were performed. Parallel concentrates with diethyl ether and ethyl acetate were prepared for each specimen, and the quantity and appearance of recovered par...

  14. Comparison of tanker drivers' occupational exposures before and after the installation of a vapour recovery system.

    Science.gov (United States)

    Saarinen, L; Hakkola, M; Kangas, J

    2000-12-01

    The purpose of this study was to compare tanker drivers' occupational exposure level before and after the installation of vapour recovery facilities at 14 service stations. Road tanker drivers are exposed when handling volatile petrol liquid in bulk in the distribution chain. The drivers' exposure was studied during the unloading operation as the bulk petrol flowed into underground storage tanks, displacing vapours in the tank space and causing emission to the environment and the drivers' work area. The exposures were measured again when the dual point Stage I vapour recovery systems were installed for recycling vapours. Short-term measurements were carried out in the drivers' breathing zones by drawing polluted air through a charcoal tube during unloading. The samples were analysed in the laboratory by gas chromatography for C3-C11 aliphatic hydrocarbons, tert-butyl methyl ether (MTBE), tert-amyl methyl ether (MTAE), benzene, toluene and xylene. The road tanker loads delivered consisted of oxygenated and reformulated petrol (E95 and E98 brands), which contained on average 13% oxygenates. Before the installation of the vapour recovery system, the geometric mean (GM) concentration of aliphatic hydrocarbons was 65 mg m-3 (range 6-645 mg m-3) in the drivers' breathing zones. After the installation at the same service stations, the corresponding exposure level was 8.3 mg m-3 (range tankers without and with vapour recovery were statistically significant (p < 0.05).

  15. Physiological and phylogenetic characterization of a stable benzene-degrading, chlorate-reducing microbial community

    NARCIS (Netherlands)

    Weelink, S.A.B.; Tan, N.C.G.; Broeke, H. ten; Doesburg, W. van; Langenhoff, A.A.M.; Gerritse, J.; Stams, A.J.M.

    2007-01-01

    A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene

  16. Structure and electronic properties of a benzene-water solution.

    Science.gov (United States)

    Mateus, Margarida P S; Galamba, Nuno; Cabral, Benedito J Costa

    2012-01-07

    Electronic properties of benzene in water were investigated by a sequential quantum mechanical/molecular dynamics approach. Emphasis was placed on the analysis of the structure, polarization effects, and ionization spectrum. By adopting a polarizable model for both benzene and water the structure of the benzene-water solution is in good agreement with data from first principles molecular dynamics. Further, strong evidence that water molecules acquire enhanced orientational order near the benzene molecule is found. Upon hydration, the quadrupole moment of benzene is not significantly changed in comparison with the gas-phase value. We are also reporting results for the dynamic polarizability of benzene in water. Our results indicate that the low energy behaviour of the dynamic polarizability of gas-phase and hydrated benzene is quite similar. Outer valence Green's function calculations for benzene in liquid water show a splitting of the gas-phase energy levels associated with the 1e(1g)(π), 2e(2g), and 2e(1u) orbitals upon hydration. Lifting of the orbitals degeneracy and redshift of the outer valence bands is related to symmetry breaking of the benzene structure in solution and polarization effects from the surrounding water molecules.

  17. Activity relationships for aromatic crown ethers

    CERN Document Server

    Wilson, M J

    1998-01-01

    This thesis involves an investigation of aromatic crown ethers and a study of their binding constants for alkali metals. The study was motivated by the current needs of the semiconductor industry to improve the scavenging of mobile ions from fabricated circuits. A number of aromatic crown ethers have been sulphonated in an attempt to improve their water solubility and cation binding activity. These materials have been extensively studied and their binding activity determined. In collaboration with a molecular modelling study, the effect of ionisable sulphonate groups on the macrocycles' behaviour has been investigated. The broader issue of the effect of substituents in aromatic crown ethers has also been studied with the preparation of a wide range of substituted crown ethers. The cation binding activity of these materials has been found to bear a simple relationship to the electron withdrawing nature of the aromatic substituents. This relationship can be accurately monitored using electronic charge densities...

  18. The resonance energy of benzene: a revisit.

    Science.gov (United States)

    Mo, Yirong

    2009-04-30

    Zielinski and van Lenthe recently extended the block-localized wave function (BLW) method by introducing the resonating BLW (RBLW) method and performed test calculations on hexagonal H(6) and benzene [J. Phys. Chem. A 2008, 112, 13197]. However, the Pauling's resonance energies from their RBLW and ab initio valence bond (VB) calculations were greatly underestimated largely due to the imperfect use of either one-electron orbitals (method = delocal) or resonance structures (method = local). Whereas it has been well recognized that electronic resonance within a molecular system plays a stabilizing role, there are many indirect experimental evidences available to evaluate the resonance energy and, thus, to justify computational results. Here we used the BLW method, which can be regarded as the simplest variant of modern ab initio VB theory, to re-evaluate the resonance energy of benzene at the B3LYP level, following the original definition by Pauling and Wheland, who obtained the resonance energy "by subtracting the actual energy of the molecule in question from that of the most stable contributing structure". The computed vertical resonance energy (or quantum mechanical resonance energy) in benzene is 88.8, 92.2, or 87.9 kcal/mol with the basis sets of 6-31G(d), 6-311+G(d,p), or cc-pVTZ, respectively, while the adiabatic resonance energy (or theoretical resonance energy) is 61.4, 63.2, or 62.4 kcal/mol, exhibiting insignificant basis set dependency for moderate basis sets. In line with predictions, the geometry optimization of the elusive cyclohexatriene (i.e., the Kekule structure) with the BLW method also resulted in carbon-carbon bond lengths (e.g., 1.322 and 1.523 A with the cc-pVTZ basis set) comparable to those in ethylene or ethane.

  19. Isomerization of allyl ethers initiated by lithium diisopropylamide.

    Science.gov (United States)

    Su, Chicheung; Williard, Paul G

    2010-12-03

    Lithium diisopropylamide (LDA) promotes virtually quantitative conversion of allylic ethers to (Z)-propenyl ethers. It was discovered that allylic ethers can be isomerized efficiently with very high stereoselectivity to (Z)-propenyl ethers by LDA in THF at room temperature. The reaction time for the conversion increases with more sterically hindered allylic ethers. Different amides were also compared with LDA for their ability to effect this isomerization.

  20. Determination of average molecular weights on organic reactor coolants. II.-Freezing point depression method for diphenyl-ether solutions; Determinacion de masas moleculares medias en refrigerantes nucleares organicos. II.- Crioscopia de disoluciones en eter difenilico

    Energy Technology Data Exchange (ETDEWEB)

    Carreira, M.

    1965-07-01

    In order to reduce limitations of solubility, the cryoscopic method developed for benzene solutions of polyphenyl mixtures has been extended to diphenyl-ether solutions by introducing some modifications imposed by the physico-chemical properties of this solvent. The Nernsto theory of Beckman's method has been revised, taking into account the heat-transfer characteristics of the system, and the results of that analysis have been used to fix upon the design parameters of a cryoscopic apparatus for measurements on diphenyl-ether solutions. (Author) 9 refs.

  1. Benzene and cyclohexane separation using 1-butyl-3-methylimidazolium thiocyanate

    Science.gov (United States)

    Gonfa, Girma; Ismail, Marhaina; Bustam, Mohamad Azmi

    2017-09-01

    Cyclohexane is mainly produced by catalytic hydrogenation of benzene. Removal of unreacted benzene from the product stream is very important in this process. However, due to their close boiling points and azeotrope formation, it is very difficult to separate cyclohexane and benzene by conventional distillation. Currently, special separation processes such as processes extractive distillation is commercially used for this separation. However, this extractive distillation suffers from process complexity and higher energy consumption due to their low extractive selectivity of molecular entrainers used. The aim of the present work is to investigate the applicability of ionic liquids as entrainer in extractive distillation of benzene and cyclohexane mixture. In this study, we investigated 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) ionic liquid for separation of benzene and cyclohexane by measuring the Vapor Liquid Equilibrium data of the two components in the presence of the ionic liquid. As green and potential environmentally friendly solvents, ionic liquids have attracted increasing attention as alternative conventional entrainers in extractive distillation. Isothermal Vapor Liquid Equilibrium for the benzene + cyclohexane + [BMIM][SCN] ternary system was obtained at 353.15 K using a Head Space Gas Chromatography. The addition of [BMIM][SCN] breaks the benzene-cyclohexane azeotrope and increased the relative volatility cyclohexane to benzene in the mixture. The effect of [BMIM][SCN] on the relative volatility cyclohexane to benzene was studied at various benzene and cyclohexane compositions and solvent to feed ratios. The performance of [BMIM][SCN] was compared with typical conventional solvents, dimethylformamide (DMF) and dimethylsulfoxide (DMSO). The results show that the relative volatility of cyclohexane to benzene in the presence of [BMIM][SCN] is higher compared that of DMSO and DMF.

  2. Final report on the safety assessment of PPG-2 methyl ether, PPG-3 methyl ether, and PPG-2 methyl ether acetate.

    Science.gov (United States)

    Robinson, Valerie; Bergfeld, Wilma F; Belsito, Donald V; Klaassen, Curtis D; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2009-01-01

    PPG-2 methyl ether, PPG-3 methyl ether, and PPG-2 methyl ether acetate are used in cosmetics as fragrance ingredients and/or solvents at concentrations of 0.4% to 2%. Propylene glycol ethers are rapidly absorbed and distributed throughout the body when introduced by inhalation or oral exposure, but the inhalation toxicity of PPG-2 methyl ether vapor, for example, is low. Aerosols, such as found with hair sprays, produce particle sizes that are not respirable. Because these ingredients are highly water-soluble, they are likely to be absorbed through the human skin only at slow rates, resulting in low blood concentrations and rapid removal by the kidney. These ingredients are not genotoxic and are not reproductive or developmental toxicants. Overall the data are sufficient to conclude that PPG-2 methyl ether, PPG-3 methyl ether, and PPG-2 methyl ether acetate are safe as used in cosmetics.

  3. Ethylene oligomerization promoted by chromium complexes bearing pyrrolide-imine-amine/ether tridentate ligands.

    Science.gov (United States)

    Pinheiro, A C; Roisnel, T; Kirillov, E; Carpentier, J-F; Casagrande, Osvaldo L

    2015-09-28

    Chromium(iii) complexes [CrCl2(L)(THF)] based on monoanionic tridentate ligands [, L = {2-(C4H3N-2'-CH[double bond, length as m-dash]N)C2H4NHPh}; , L = {5-tert-butyl-2-(C4H2N-2'-CH[double bond, length as m-dash]N)C2H3NHPh}; , L = {2-(C4H3N-2'-CH[double bond, length as m-dash]N)C2H4OPh}] have been prepared. Complexes and were converted into the monomeric acetonitrile adducts [CrCl2(L)(NCMe)] [, L = {2-(C4H3N-2'-CH[double bond, length as m-dash]N)C2H4NHPh}; , L = {5-tert-butyl-2-(C4H2N-2'-CH[double bond, length as m-dash]N)C2H3NHPh}] by reaction with acetonitrile at room temperature. All Cr complexes were characterized by IR spectroscopy, elemental analysis, magnetochemistry for , and by X-ray crystallography for and . Upon activation with methylaluminoxane (MAO), chromium precatalysts and showed good activity in ethylene oligomerization (TOF = 47.0-57.0 × 10(3) (mol ethylene)(mol Cr)(-1) h(-1) at 80 °C), producing mostly oligomers (93.0-95.6 wt% of total products). On the other hand, under identical oligomerization conditions, /MAO behaved as a polymerization catalyst generating predominantly polyethylene (73.0 wt%). However, the catalytic behavior of the precatalyst can be adjusted by varying the MAO-to-Cr ratio. Thus, the use of 500 equiv. causes a dramatic shift from polymerization to ethylene oligomerization, eventually producing mainly lighter α-olefin fractions [α-C4 (68.7 wt%) and α-C6 (19.2 wt%)]. A further increase in the amount of MAO (1000 equiv.) leads to a more balanced distribution of oligomers, with a drastic decrease in the α-C4 and increase in the α-C8 fractions.

  4. Sulfonated poly(ether ether ketone) based composite membranes for nanofiltration of acidic and alkaline media

    NARCIS (Netherlands)

    Dalwani, M.R.; Bargeman, Gerrald; Hosseiny, Seyed Schwan; Schwan Hosseiny, Seyed; Boerrigter, M.E.; Wessling, Matthias; Benes, Nieck Edwin

    2011-01-01

    Several thin film composite nanofiltration membranes have been prepared by spin coating a sulfonated poly(ether ether ketone) solution on a polyethersulfone support, followed by thermal treatment. The most optimal developed nanofiltration membrane shows a clean water permeance of ∼4.5 L m−2 h−1

  5. Novel crosslinked membranes based on sulfonated poly(ether ether ketone) for direct methanol fuel cells.

    Science.gov (United States)

    Zhu, Yuanqin; Zieren, Shelley; Manthiram, Arumugam

    2011-07-14

    Novel covalently crosslinked membranes based on sulfonated poly(ether ether ketone) and carboxylated polysulfone exhibit much lower methanol crossover and better performance in direct methanol fuel cells at 65 °C in 1 and 2 M methanol solutions compared to Nafion 115 membranes.

  6. Study of improved resins for advanced supersonic technology composites. Part 1: Heteroaromatic polymers containing ether groups. Part 2: Curing chemistry of aromatic polymers and composite studies

    Science.gov (United States)

    Takekoshi, T.; Hillig, W. B.; Mellinger, G. A.

    1975-01-01

    Fourteen ether-containing, aromatic dianhydrides have been synthesized from N-phenyl-3 or 4-nitrophthalimide and various bisphenols. The process involves nucleophilic displacement of activated nitro groups with bisphenolate ions. Ether-containing dianhydrides were indefinitely stable in the presence of atmospheric moisture. One-step, high temperature solution polymerization of the ether-containing dianhydrides with m-phenylene diamine, 4,4'-oxydianiline and 1, 3-bis(4-aminophenoxy)benzene afforded 42 polyetherimides. The polyetherimides were all soluble in m-cresol except two which were found to be crystalline. The glass transition temperatures of the polyetherimides ranged from 178 to 277 C. Soluble polybenzimidazopyrrolones containing ether groups were also prepared from the same ether-containing dianhydrides and aromatic tetraamines by one-step solution polymerization. Using low molecular weight polyetherimides, various thermoset resin systems were developed and tested as matrices for fiber-reinforced composites. The curing chemistry involving reaction of the phthalonitrile group and the o-diaminophenyl group was found to be generally applicable to crosslinking various aromatic polymers other than polyimides.

  7. The excited state antiaromatic benzene ring: a molecular Mr Hyde?

    Science.gov (United States)

    Papadakis, Raffaello; Ottosson, Henrik

    2015-09-21

    The antiaromatic character of benzene in its first ππ* excited triplet state (T1) was deduced more than four decades ago by Baird using perturbation molecular orbital (PMO) theory [J. Am. Chem. Soc. 1972, 94, 4941], and since then it has been confirmed through a range of high-level quantum chemical calculations. With focus on benzene we now first review theoretical and computational studies that examine and confirm Baird's rule on reversal in the electron count for aromaticity and antiaromaticity of annulenes in their lowest triplet states as compared to Hückel's rule for the ground state (S0). We also note that the rule according to quantum chemical calculations can be extended to the lowest singlet excited state (S1) of benzene. Importantly, Baird, as well as Aihara [Bull. Chem. Soc. Jpn. 1978, 51, 1788], early put forth that the destabilization and excited state antiaromaticity of the benzene ring should be reflected in its photochemical reactivity, yet, today these conclusions are often overlooked. Thus, in the second part of the article we review photochemical reactions of a series of benzene derivatives that to various extents should stem from the excited state antiaromatic character of the benzene ring. We argue that benzene can be viewed as a molecular "Dr Jekyll and Mr Hyde" with its largely unknown excited state antiaromaticity representing its "Mr Hyde" character. The recognition of the "Jekyll and Hyde" split personality feature of the benzene ring can likely be useful in a range of different areas.

  8. Benzene degradation coupled with chlorate reduction in soil column study

    NARCIS (Netherlands)

    Tan, N.C.G.; Doesburg, van W.C.J.; Langenhoff, A.A.M.; Stams, A.J.M.

    2006-01-01

    Perchlorate and chlorate are electron acceptors that during reduction result in the formation of molecular oxygen. The produced oxygen can be used for activation of anaerobic persistent pollutants, like benzene. In this study chlorate was tested as potential electron acceptor to stimulate benzene

  9. Cytokine Network Involvement in Subjects Exposed to Benzene

    Science.gov (United States)

    Gangemi, Sebastiano

    2014-01-01

    Benzene represents an ubiquitous pollutant both in the workplace and in the general environment. Health risk and stress posed by benzene have long been a concern because of the carcinogenic effects of the compound which was classified as a Group 1 carcinogen to humans and animals. There is a close correlation between leukemia, especially acute myeloid leukemia, and benzene exposure. In addition, exposure to benzene can cause harmful effects on immunological, neurological, and reproductive systems. Benzene can directly damage hematopoietic progenitor cells, which in turn could lead to apoptosis or may decrease responsiveness to cytokines and cellular adhesion molecules. Alternatively, benzene toxicity to stromal cells or mature blood cells could disrupt the regulation of hematopoiesis, including hematopoietic commitment, maturation, or mobilization, through the network of cytokines, chemokines, and adhesion molecules. Today there is mounting evidence that benzene may alter the gene expression, production, or processing of several cytokines in vitro and in vivo. The purpose of this review was to systematically analyze the published cases of cytokine effects on human benzene exposure, particularly hematotoxicity, and atopy, and on lungs. PMID:25202711

  10. Evidence that humans metabolize benzene via two pathways.

    NARCIS (Netherlands)

    Rappaport, S.M.; Kim, S.; Lan, Q.; Vermeulen, R.C.H.; Waidyanatha, S.; Zhang, L.; Li, G.; Yin, S.; Hayes, R.B.; Rothman, N.; Smith, M.T.

    2009-01-01

    BACKGROUND: Recent evidence has shown that humans metabolize benzene more efficiently at environmental air concentrations than at concentrations > 1 ppm. This led us to speculate that an unidentified metabolic pathway was mainly responsible for benzene metabolism at ambient levels. OBJECTIVE: We

  11. Small-angle neutron scattering studies of sodium butyl benzene ...

    Indian Academy of Sciences (India)

    shape and size of the aggregates of sodium n-butyl benzene sulfonate in aqueous solutions. To the best of our knowledge this is the first SANS report on the aggre- gation behaviour of a hydrotrope in aqueous solutions. 2. Materials and methods n-Butyl benzene, procured from Herdilia Chemicals, Mumbai, was sulfonated ...

  12. In situ synthesis of silver benzene-dithiolate hybrid films

    Energy Technology Data Exchange (ETDEWEB)

    Brenier, Roger, E-mail: roger.brenier@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Piednoir, Agnès, E-mail: agnes.piednoir@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Bertorelle, Franck, E-mail: franck.bertorelle@univ-lyon1.fr [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, Domaine Scientifique de La Doua, Batiment Kastler, 10 rue Ada Byron, 69622 Villeurbanne, Cedex (France); Penuelas, José, E-mail: jose.penuelas@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France); Grenet, Geneviève, E-mail: genevieve.grenet@ec-lyon.fr [Université de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, CNRS, UMR 5270, 36 rue Guy de Collongues, F69134 Ecully (France)

    2016-02-01

    In this article, a method for in situ synthesis of silver benzene-dithiolate hybrid films is presented. Silver nanoparticles, generated on ZrO{sub 2} films, are transformed into silver benzene 1,4-dithiolate or, partially, into silver benzene 1,2-dithiolate after sample immersion in the corresponding thiol solutions. These transformations occur at room temperature owing to the catalytic action of ZrO{sub 2}. It is also shown that TiO{sub 2} in place of ZrO{sub 2} is very efficient, both for the catalytic generation of silver nanoparticles and for their further transformation in benzene 1,4-dithiolate compound. This latter semiconductor has an optical bandgap of about 3 eV and the film is made of touching nanoparticles in an amorphous state. Our work has potential applications in the electronic and photovoltaic fields. - Highlights: • A method for in situ synthesis of silver benzene-dithiolate hybrid semiconductor films is presented. • Silver nanoparticles are, first, generated on ZrO{sub 2} or on TiO{sub 2} coated silica substrates. • The samples are immersed in benzene dithiol solution for two days at room temperature. • During the immersion, the silver nanoparticles are transformed into silver benzene dithiolate. • The silver benzene dithiolate film is made of amorphous nanoparticles with a banbgap of 3 eV.

  13. Benzene as a Chemical Hazard in Processed Foods

    Directory of Open Access Journals (Sweden)

    Vânia Paula Salviano dos Santos

    2015-01-01

    Full Text Available This paper presents a literature review on benzene in foods, including toxicological aspects, occurrence, formation mechanisms, and mitigation measures and analyzes data reporting benzene levels in foods. Benzene is recognized by the IARC (International Agency for Research on Cancer as carcinogenic to humans, and its presence in foods has been attributed to various potential sources: packaging, storage environment, contaminated drinking water, cooking processes, irradiation processes, and degradation of food preservatives such as benzoates. Since there are no specific limits for benzene levels in beverages and food in general studies have adopted references for drinking water in a range from 1–10 ppb. The presence of benzene has been reported in various food/beverage substances with soft drinks often reported in the literature. Although the analyses reported low levels of benzene in most of the samples studied, some exceeded permissible limits. The available data on dietary exposure to benzene is minimal from the viewpoint of public health. Often benzene levels were low as to be considered negligible and not a consumer health risk, but there is still a need of more studies for a better understanding of their effects on human health through the ingestion of contaminated food.

  14. 46 CFR 197.565 - Notifying personnel of benzene hazards.

    Science.gov (United States)

    2010-10-01

    ..., control measures such as personal protection equipment, and first aid procedures for benzene. A copy of...) Material safety data sheet. A material safety data sheet (MSDS) addressing benzene must be made available... personal protective equipment in emergency situations; (vi) The meaning of a regulated area and the means...

  15. Surface-Enhanced Raman Spectroscopy as a Probe or Adsorbate-Surface Bonding: Benzene and Monosubstituted Benzenes Adsorbed at Gold Electrodes

    Science.gov (United States)

    1985-08-01

    Absorption at Gold and Corresponding SERS Bandwidth for eenzene and Monosubstituted Benzenes Adsorbt -te Potential a -AV b F H mV vs sce cm cm cm C6H6 500 978...Bonding: Benzene and Monosubstituted Benzenes Adsorbed at Gold Electrodes by Ping Gao and Michael J. Weaver Prepared for Publication in the Journal of...Raman Spectroscopy as a Probe of Adsorbate-Surface Bonding: Benzene and Mono- Technical Report No. 51 substituted Benzenes Adsorbed at Gold Electrodes

  16. Anaerobic benzene degradation under denitrifying conditions: Peptococcaceae was identified as dominant benzene degrader by Stable Isotope Probing (SIP)

    NARCIS (Netherlands)

    Zaan, van der B.M.; Talarico Saia, F.; Plugge, C.M.; Vos, de W.M.; Smidt, H.; Stams, A.J.M.; Langenhoff, A.A.M.; Gerritse, J.

    2012-01-01

    An anaerobic microbial community was enriched in a chemostat that was operated for more than 8 years with benzene and nitrate as electron acceptor. The coexistence of multiple species in the chemostat and the presence of a biofilm, led to the hypothesis that benzene-degrading species coexist in a

  17. Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC

    Science.gov (United States)

    Blankespoor, Ronald L.; Hogendoorn, Stephanie; Pearson, Andrea

    2007-01-01

    The reactivity and orientation effects of a substituent are analyzed by using HPLC to determine the competitive nitration of the benzene-toluene and benzene-fluorobenzene mixtures. The results have shown that HPLC is an excellent instrumental method to use in analyzing these mixtures.

  18. Atmospheric degradation of 2-chloroethyl vinyl ether, allyl ether and allyl ethyl ether: Kinetics with OH radicals and UV photochemistry.

    Science.gov (United States)

    Antiñolo, M; Ocaña, A J; Aranguren, J P; Lane, S I; Albaladejo, J; Jiménez, E

    2017-08-01

    Unsaturated ethers are oxygenated volatile organic compounds (OVOCs) emitted by anthropogenic sources. Potential removal processes in the troposphere are initiated by hydroxyl (OH) radicals and photochemistry. In this work, we report for the first time the rate coefficients of the gas-phase reaction with OH radicals (k OH ) of 2-chloroethyl vinyl ether (2ClEVE), allyl ether (AE), and allyl ethyl ether (AEE) as a function of temperature in the 263-358 K range, measured by the pulsed laser photolysis-laser induced fluorescence technique. No pressure dependence of k OH was observed in the 50-500 Torr range in He as bath gas, while a slightly negative T-dependence was observed. The temperature dependent expressions for the rate coefficients determined in this work are: The estimated atmospheric lifetimes (τ OH ) assuming k OH at 288 K were 3, 2, and 4 h for 2ClEVE, AE and AEE, respectively. The kinetic results are discussed in terms of the chemical structure of the unsaturated ethers by comparison with similar compounds. We also report ultraviolet (UV) and infrared (IR) absorption cross sections (σ λ and σ(ν˜), respectively). We estimate the photolysis rate coefficients in the solar UV actinic region to be less than 10 -7 s -1 , implying that these compounds are not removed from the atmosphere by this process. In addition, from σ(ν˜) and τ OH , the global warming potential of each unsaturated ether was calculated to be almost zero. A discussion on the atmospheric implications of the titled compounds is presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Benzene adsorption on two-dimensional silica films - Benzene on silicatene

    Science.gov (United States)

    Nayakasinghe, M. T.; Sivapragasam, N.; Burghaus, U.

    2017-10-01

    The kinetics of benzene adsorption on monatomic crystalline silica films (silicatene) was studied, employing temperature programmed desorption (TPD). In addition, the precursor of the silica film formation, a Mo(1 1 2)-p(1 × 3)-O missing row reconstruction, and Mo(1 1 2) were considered. Benzene adsorbed molecularly on all surfaces. Judged by the desorption temperatures, the adsorption on the Mo oxygen phase is stronger than on silica. Two binding sites were evident for the oxygen induced reconstruction, but only one for silica. Thus, the adsorption kinetics on the support and the monoatomic thin silica film were quite different. In addition, the surfaces were characterized by Auger electron spectroscopy and low energy electron diffraction (LEED).

  20. Inhalation anaesthesia: from diethyl ether to xenon.

    Science.gov (United States)

    Bovill, J G

    2008-01-01

    Modern anaesthesia is said to have began with the successful demonstration of ether anaesthesia by William Morton in October 1846, even though anaesthesia with nitrous oxide had been used in dentistry 2 years before. Anaesthesia with ether, nitrous oxide and chloroform (introduced in 1847) rapidly became commonplace for surgery. Of these, only nitrous oxide remains in use today. All modern volatile anaesthetics, with the exception of halothane (a fluorinated alkane), are halogenated methyl ethyl ethers. Methyl ethyl ethers are more potent, stable and better anaesthetics than diethyl ethers. They all cause myocardial depression, most markedly halothane, while isoflurane and sevoflurane cause minimal cardiovascular depression. The halogenated ethers also depress the normal respiratory response to carbon dioxide and to hypoxia. Other adverse effects include hepatic and renal damage. Hepatitis occurs most frequently with halothane, although rare cases have been reported with the other agents. Liver damage is not caused by the anaesthetics themselves, but by reactive metabolites. Type I hepatitis occurs fairly commonly and takes the form of a minor disturbance of liver enzymes, which usually resolves without treatment. Type II, thought to be immune-mediated, is rare, unpredictable and results in a severe fulminant hepatitis with a high mortality. Renal damage is rare, and was most often associated with methoxyflurane because of excessive plasma fluoride concentrations resulting from its metabolism. Methoxyflurane was withdrawn from the market because of the high incidence of nephrotoxicity. Among the contemporary anaesthetics, the highest fluoride concentrations have been reported with sevoflurane, but there are no reports of renal dysfunction associated with its use. Recently there has been a renewed interest in xenon, one of the noble gases. Xenon has many of the properties of an ideal anaesthetic. The major factor limiting its more widespread is the high cost, about

  1. A technique to anesthetize turtles with ether.

    Science.gov (United States)

    Belló, A A; Belló-Klein, A

    1991-10-01

    A technique to anesthetize turtles with ether is presented, in which a plastic cannula is passed through the glottis into the trachea. This procedure avoids apnea and allows ether vapours obtained from a chamber to be introduced, by the animal respiratory movements or by means of a pump, into the animal lungs. The anesthesia is rapidly obtained and lasts from 45-90 minutes. The time of recovery from anesthesia ranged from 60-90 minutes. With this technique no deaths were observed and the same animal could be anesthetized repeatedly.

  2. Benzene exposure is associated with cardiovascular disease risk.

    Science.gov (United States)

    Abplanalp, Wesley; DeJarnett, Natasha; Riggs, Daniel W; Conklin, Daniel J; McCracken, James P; Srivastava, Sanjay; Xie, Zhengzhi; Rai, Shesh; Bhatnagar, Aruni; O'Toole, Timothy E

    2017-01-01

    Benzene is a ubiquitous, volatile pollutant present at high concentrations in toxins (e.g. tobacco smoke) known to increase cardiovascular disease (CVD) risk. Despite its prevalence, the cardiovascular effects of benzene have rarely been studied. Hence, we examined whether exposure to benzene is associated with increased CVD risk. The effects of benzene exposure in mice were assessed by direct inhalation, while the effects of benzene exposure in humans was assessed in 210 individuals with mild to high CVD risk by measuring urinary levels of the benzene metabolite trans,trans-muconic acid (t,t-MA). Generalized linear models were used to assess the association between benzene exposure and CVD risk. Mice inhaling volatile benzene had significantly reduced levels of circulating angiogenic cells (Flk-1+/Sca-1+) as well as an increased levels of plasma low-density lipoprotein (LDL) compared with control mice breathing filtered air. In the human cohort, urinary levels of t,t-MA were inversely associated several populations of circulating angiogenic cells (CD31+/34+/45+, CD31+/34+/45+/AC133-, CD34+/45+/AC133+). Although t,t-MA was not associated with plasma markers of inflammation or thrombosis, t,t-MA levels were higher in smokers and in individuals with dyslipidemia. In smokers, t,t-MA levels were positively associated with urinary metabolites of nicotine (cotinine) and acrolein (3-hydroxymercapturic acid). Levels of t,t-MA were also associated with CVD risk as assessed using the Framingham Risk Score and this association was independent of smoking. Thus, benzene exposure is associated with increased CVD risk and deficits in circulating angiogenic cells in both smokers and non-smokers.

  3. Benzene exposure: An overview of monitoring methods and their findings

    Science.gov (United States)

    Weisel, Clifford P.

    2014-01-01

    Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person’s total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t,t-muconic acid (t,tMA) and S-phenylmercapturic acid (sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites, differences in metabolic rates compared to occupational or animal doses, and the presence of polymorphisms need to be considered when

  4. Synthesis of alkynyl ethers and low-temperature sigmatropic rearrangement of allyl and benzyl alkynyl ethers.

    Science.gov (United States)

    Sosa, Juan R; Tudjarian, Armen A; Minehan, Thomas G

    2008-11-06

    Alpha-alkoxy ketones 3 can be transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead gamma,delta-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at -78 degrees C and trapping of the subsequently formed ketene with nucleophiles (Nu-H). Benzyl alkynyl ether 5 (R2 = benzyl) rearranges to indanone 7 upon heating to 60 degrees C.

  5. Synthesis of Alkynyl Ethers and Low Temperature Sigmatropic Rearrangement of Allyl and Benzyl Alkynyl Ethers

    Science.gov (United States)

    Sosa, Juan R.; Tudjarian, Armen A.; Minehan, Thomas G.

    2009-01-01

    α–Alkoxy ketones 3 can be transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead γ,δ-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at −78 °C and trapping of the subsequently formed ketene with nucleophiles (Nu-H). Benzyl alkynyl ether 5 (R2 = benzyl) rearranges to indanone 7 upon heating to 60 °C. PMID:18847213

  6. Syntheses of Diazadithiacrown Ethers Containing Two 8-Hydroxyquinoline Side Arms

    National Research Council Canada - National Science Library

    Song, H

    2001-01-01

    Ten new diazadithiacrown ethers containing two 8-hydroxyquinoline (HQ) sidearms attached through the HQ 7-positions and four new diazadithiacrown ethers containing two HQ sidearms attached through the HQ 2-positions have been prepared...

  7. IRIS Toxicological Review of Decabromodiphenyl Ether (Final Report)

    Science.gov (United States)

    EPA announced the release of the final report, Toxicological Review of Decabromodiphenyl Ether: in support of the Integrated Risk Information System (IRIS). The updated Summary for Decabromodiphenyl Ether and accompanying toxicological review have been added to the IRIS Da...

  8. Thermodynamic and chemical behavior of benzene under shock conditions

    Science.gov (United States)

    Maillet, Jean-Bernard; Pineau, Nicolas; Bourasseau, Emeric

    2007-06-01

    The thermodynamic and chemical behavior of benzene along its hugoniot curve is investigated using Molecular Dynamics simulations with reactive potentials. The simulated hugoniot curve is in good agreement with experimental data at low pressures. Moreover, the decomposition threshold is well reproduced. In the high pressure regime, reactive simulations show that benzene rapidly decomposes, but resulting pressures do not match experimental ones anymore. Simulations starting with diamond nanoparticules and hydrogen gas give good pressures along the hugoniot. These simulations seem to confirm the existence of carbon clusters with diamond structure in the decomposition products of benzene.

  9. Formation of amorphous hydrogenated carbon from compression of benzene

    Science.gov (United States)

    Shinozaki, Ayako; Kagi, Hiroyuki; Mimura, Koichi

    2017-10-01

    Infrared spectra of benzene were measured at pressures up to 25.3 GPa at room temperature using a diamond anvil cell. With decompression from pressures above 18.7 GPa, a new peak of C-H vibration mode appeared at a lower frequency than that of benzene. This indicates that an irreversible chemical change occurred at a pressure that was lower than that reported in previous studies. The IR spectra of the recovered sample after compression up to 20.3 GPa are comparable with those of the amorphous hydrogenated carbon reported in the previous study that was formed by compression of benzene up to approximately 30 GPa.

  10. 40 CFR 721.3486 - Polyglycerin mono(4-nonylphenyl) ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polyglycerin mono(4-nonylphenyl) ether... Substances § 721.3486 Polyglycerin mono(4-nonylphenyl) ether. (a) Chemical substance and significant new uses...-nonylphenyl) ether (PMN P-94-2230) is subject to reporting under this section for the significant new uses...

  11. 40 CFR 721.3500 - Perhalo alkoxy ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Perhalo alkoxy ether. 721.3500 Section... Substances § 721.3500 Perhalo alkoxy ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as perhalo alkoxy ether (PMN P-83-1227) is...

  12. 46 CFR 151.50-42 - Ethyl ether.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Ethyl ether. 151.50-42 Section 151.50-42 Shipping COAST... LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-42 Ethyl ether. (a)(1) Gravity tanks... liquid. (g) Precautions shall be taken to prevent the contamination of ethyl ether by strong oxidizing...

  13. 40 CFR 721.3435 - Butoxy-substituted ether alkane.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Butoxy-substituted ether alkane. 721... Substances § 721.3435 Butoxy-substituted ether alkane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as butoxy-substituted ether alkane...

  14. 40 CFR 799.4440 - Triethylene glycol monomethyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 31 2010-07-01 2010-07-01 true Triethylene glycol monomethyl ether... REQUIREMENTS Specific Chemical Test Rules § 799.4440 Triethylene glycol monomethyl ether. (a) Identification of test substance. (1) Triethylene glycol monomethyl ether (TGME, CAS No. 112-35-6) shall be tested in...

  15. 40 CFR 721.3485 - Hydrofluorocarbon alkyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Hydrofluorocarbon alkyl ether. 721... Substances § 721.3485 Hydrofluorocarbon alkyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as a hydrofluorocarbon alkyl ether...

  16. 40 CFR 721.3550 - Dipropylene glycol dimethyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Dipropylene glycol dimethyl ether. 721... Substances § 721.3550 Dipropylene glycol dimethyl ether. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as dipropylene glycol dimethyl ether (PMN P-93...

  17. 40 CFR 721.3420 - Brominated arylalkyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Brominated arylalkyl ether. 721.3420... Substances § 721.3420 Brominated arylalkyl ether. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified generically as brominated arylalkyl ether (P-83-906) is...

  18. 40 CFR 721.10069 - Ether amine phosphonate (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ether amine phosphonate (generic). 721... Substances § 721.10069 Ether amine phosphonate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as ether amine phosphonate (PMN P...

  19. 40 CFR 721.3465 - Stilbene diglycidyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Stilbene diglycidyl ether. 721.3465... Substances § 721.3465 Stilbene diglycidyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as stilbene diglycidyl ether (PMN P-96-1427) is subject to...

  20. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Chlorohydroxyalkyl butyl ether... Specific Chemical Substances § 721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance... chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to reporting under this section for the significant new use...

  1. 21 CFR 520.1846 - Polyoxyethylene (23) lauryl ether blocks.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Polyoxyethylene (23) lauryl ether blocks. 520.1846... Polyoxyethylene (23) lauryl ether blocks. (a) Specifications. Each molasses-based block contains 2.2 percent polyoxyethylene (23) lauryl ether. (b) Sponsor. See No. 067949 in § 510.600(c) of this chapter. (c) Conditions of...

  2. 40 CFR 721.3520 - Aliphatic polyglycidyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aliphatic polyglycidyl ether. 721.3520... Substances § 721.3520 Aliphatic polyglycidyl ether. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance aliphatic polyglycidyl ether (PMN P-89-1036) is subject to...

  3. 40 CFR 721.3430 - 4-Bromophenyl phenyl ether.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 4-Bromophenyl phenyl ether. 721.3430... Substances § 721.3430 4-Bromophenyl phenyl ether. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance 4-bromophenyl phenyl ether (CAS No. 101-55-3) is subject to reporting...

  4. 40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene baseline...

  5. Association between genetic variants in VEGF, ERCC3 and occupational benzene haematotoxicity.

    NARCIS (Netherlands)

    Hosgood 3rd, H.D.; Zhang, L.; Shen, M.; Berndt, S.I.; Vermeulen, R.; Li, G.; Yin, S.; Yeager, M.; Yuenger, J.; Rothman, N.; Chanock, S.; Smith, M.; Lan, Q.

    2009-01-01

    INTRODUCTION: Benzene is an established human haematotoxin, with substantial interindividual variation in benzene-induced toxicity. METHODS: To further examine if genetic variation contributes to benzene haematotoxicity, we analysed 1023 tagSNPs in 121 gene regions important for benzene metabolism,

  6. 40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL... Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program? (a) Benzene standard. (1) For the annual averaging period beginning January 1, 2011, and for each...

  7. 40 CFR 80.1356 - What are the attest engagement requirements for gasoline benzene compliance?

    Science.gov (United States)

    2010-07-01

    ... requirements for gasoline benzene compliance? 80.1356 Section 80.1356 Protection of Environment ENVIRONMENTAL... Benzene Attest Engagements § 80.1356 What are the attest engagement requirements for gasoline benzene... that contain gasoline benzene and gasoline volume information. (2) Agree the yearly volumes of gasoline...

  8. 40 CFR 80.1295 - How are gasoline benzene credits used?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline benzene...

  9. Sequential metalation of benzene: electronic, bonding, magnetotropic and spectroscopic properties of coinage metalated benzenes studied by DFT.

    Science.gov (United States)

    Tsipis, Athanassios C; Gkarbounis, Dimitrios N

    2015-06-01

    A series of coinage metalated benzenes formulated as C6H6-nMn (M = Cu, Ag, Au, n = 1-5) were investigated by means of density functional theory (DFT) calculations. The structural, energetic, magnetotropic and spectroscopic properties of the coinage metalated benzenes were analyzed thoroughly and compared to the respective properties of the archetype aromatic benzene molecule. In contrast to the latter, the C6H6-nMn (M = Cu, Ag, Au, n = 1-5) molecules are predicted to be aromatic even in their excited triplet state. Excellent linear correlations between (I) the zz component of the nucleus independent chemical shift [NICSzz(1)] values and the total negative natural charge acquired by the carbocyclic ring, and (ii) the NICSzz(1) vs wavelength (λ) of the HOMO → LUMO transitions in the absorption spectra of the coinage metalated benzenes were established. The emission spectra of the coinage metalated benzenes were characterized by high [Formula: see text] values, particularly for the di-substituted - and p-isomers, with the highest [Formula: see text] value of 67 kcal mol(-1) calculated for the m-M6H4Au2 species. The bonding pattern of the coinage metalated benzenes was analyzed thoroughly by means of a multitude of electronic structure calculation methods [natural bond orbital (NBO), atoms-in-molecules (AIM), electron localization function (ELF), reduced density gradient (RDG) and Sign(λ 2(r))ρ(r) functions]. Our findings indicate whole classes of new coinage metalated benzenes (mono-, di-, tri-, four- and five-substituted) opening a new chemistry for the coinage metalated benzenes, indicating that their chemistry will be worthwhile studying both experimentally and theoretically in the future. Graphical Abstract The complete series of coinage metalated benzenes were investigated by density functional theory methods. The structural, energetic, bonding, magnetotropic and spectroscopic properties of the coinage metalated benzenes were analyzed

  10. Biosynthesis of archaeal membrane ether lipids

    NARCIS (Netherlands)

    Jain, Samta; Caforio, Antonella; Driessen, Arnold J. M.

    2014-01-01

    A vital function of the cell membrane in all living organism is to maintain the membrane permeability barrier and fluidity. The composition of the phospholipid bilayer is distinct in archaea when compared to bacteria and eukarya. In archaea, isoprenoid hydrocarbon side chains are linked via an ether

  11. Children's exposure to polybrominated diphenyl ethers

    NARCIS (Netherlands)

    Zuurbier, M.; Leijs, M.; Schoeters, G.; Tusscher, G. Ten; Koppe, J.G.

    2006-01-01

    Background: Polybrominated biphenyl ethers (PBDEs), a class of brominated flame retardants, are frequently used in consumer products. PBDEs levels in environmental and human samples have increased in recent decades. Children are exposed to PBDEs through diet, mainly through fish, meat and milk.

  12. The Lubrication Qualities of Dimethyl Ether (DME)

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Sorenson, Spencer C; Jakobsen, J.

    2002-01-01

    Dimethyl Ether (DME) has been recognised as a clean alternative for diesel oil for some years now. Fuelling diesel engines with DME solves their two most significant problems: The emission of particulate matter is virtually eliminated and the level of NOx can be reduced considerably by exhaust gas......, as the clean emission advantage obtained when using DME will be lost....

  13. Vibrational energy flow in substituted benzenes

    Science.gov (United States)

    Pein, Brandt C.

    Using ultrafast infrared (IR) Raman spectroscopy, vibrational energy flow was monitored in several liquid-state substituted benzenes at ambient temperature. In a series of mono-halogenated benzenes, X-C6H 5 (X = F, Cl, Br, I), a similar CH-stretch at 3068 cm-1 was excited using picosecond IR pulses and the resulting vibrational relaxation and overall vibrational cooling processes were monitored with anti-Stokes spectroscopy. In the molecules with a heavier halide substituent the CH-stretch decayed slower while midrange vibrations decayed faster. This result was logical if the density of states (DOS) in the first few tiers, which is the DOS composed of vibrations with smaller quantum number, is what primarily determines energy flow. For tiers 1-4, the DOS was nearly identical in the CH-stretch region while it increased in the midrange region for heavier halide mass. Excitation spectroscopy, an extension of 3D IR-Raman spectroscopy, was developed and used to selectively pump vibrations localized to the substituent or the phenyl group in nitrobenzene (NB), o-fluoronitrobenzene (OFNB) and o-nitrotoluene (ONT) and in the alkylbenzene series toluene, isopropylbenzene (IPB), and t-butylbenzene (TBB). Using quantum chemical calculations, each Raman active vibration was sorted, according to their atomic displacements, into three classifications: substituent, phenyl, or global. Using IR pump wavenumbers that initially excited substituent or phenyl vibrations, IR-Raman spectroscopy was used to monitor energy flowing from the substituent to phenyl vibrations and vice versa. In NB nitro-to-phenyl and nitro-to-global energy flow was almost nonexistent while phenyl-to-nitro and phenyl-to-global was weak. When ortho substituents (-CH3, -F) were introduced, energy flow from nitro-to-phenyl and nitro-to-global was activated. In ONT, phenyl-to-nitro energy flow ceased possibly due to the added methyl group diverting energy from entering the nitro vibrations. Energy flow is therefore

  14. (4,4′-Di-tert-butyl-2,2′-bipyridine-κ2N,N′bis(nitrato-κ2O,O′copper(II

    Directory of Open Access Journals (Sweden)

    Zhu Tao

    2009-02-01

    Full Text Available In the crystal of the title compound, [Cu(NO32(C18H24N2], the CuII ion is coordinated by two N atoms of the bipyridine ligand and four O atoms from the two nitrate anions in a distorted octahedral fashion. The dihedral angle between the planes of the two pyridine rings is 11.52 (10°. In the crystal structure, weak C—H...O interactions may help to establish the packing.

  15. C-nitroso compounds. Part XIII: monomeric nitroso compounds by photochemical nitrosation of branched-chain hydrocarbons with tert-butyl nitrite

    NARCIS (Netherlands)

    Mackor, A.; Boer, T.J. de

    1970-01-01

    The photochemical nitrosation with t‐butyl nitrite of some branched‐chain hydrocarbons, containing tertiary hydrogen atoms leads to the formation of monomeric nitroso compounds in yields up to 78%, when a special Soxhlet technique is employed. The use of wavelengths around 400 nm is essential for

  16. Crystal structure of (1R,4R)-tert-butyl 3-oxo-2-oxa-5-aza-bicyclo-[2.2.2]octane-5-carboxyl-ate.

    Science.gov (United States)

    Krishnamurthy, Suvratha; Jalli, Venkataprasad; Vagvala, Tarun Chand; Moriguchi, Tetsuji; Tsuge, Akihiko

    2015-07-01

    In the title compound, C11H17NO4, commonly known as N-tert-but-oxy-carbonyl-5-hy-droxy-d-pipecolic acid lactone, the absolute configuration is (1R,4R) due to the enantiomeric purity of the starting material which remains unchanged during the course of the reaction. In the crystal there no inter-molecular hydrogen bonds.

  17. (6R-2-tert-Butyl-6-[(4R,5S-3-isopropyl-4-methyl-5-phenyloxazolidin-2-yl]phenol

    Directory of Open Access Journals (Sweden)

    Takaoki Koyanagi

    2010-04-01

    Full Text Available In the title compound, C23H31NO2, the lone pair on the nitrogen atom is oriented to facilitate intramolecular hydrogen bonding with the hydroxy group residing on the phenyl substituent. The five-membered ring adopts an envelope confornmation with the O atom at the flap. The absolute stereochemistry was verified by measurement of optical activity using a digital polarimeter.

  18. Dichlorido(4,4′-di-tert-butyl-2,2′-bipyridine-κ2N,N′gold(III tetrachloridoaurate(III acetonitrile solvate

    Directory of Open Access Journals (Sweden)

    Hamid Reza Khavasi

    2008-09-01

    Full Text Available In the title compound, [AuCl2(C9H12N2][AuCl4]·C2H3N, there is a mirror plane passing through Au and the central C—C bond of the bipyridyl ligand in the cation, and through Au and two Cl atoms of the anion. A cis-AuCl2N2 square-planar geometry for the cation and a square-planar AuCl4 geometry for the anion result. The two C atoms and the N atom of the acetonitrile molecule all have m site symmetries. In the crystal structure, weak C—H...Cl interactions may help to establish the packing.

  19. Tert-butyl 3-oxo-2,3,4,5,6,7-hexahydro-1H-pyrazolo[4,3-c]pyridine-5-carboxylate

    Directory of Open Access Journals (Sweden)

    Tara Shahani

    2010-01-01

    Full Text Available In the title compound, C11H17N3O3, the pyrazole ring is approximately planar, with a maximum deviation of 0.005 (2 Å, and forms a dihedral angle of 5.69 (13° with the plane through the six atoms of the piperidine ring. In the crystal, pairs of intermolecular N—H...O hydrogen bonds form dimers with neighbouring molecules, generating R22(8 ring motifs. These dimers are further linked into two-dimensional arrays parallel to the bc plane by intermolecular N—H...O and C—H...O hydrogen bonds.

  20. The Effect of Msh2 Knockdown on Toxicity Induced by tert-Butyl-hydroperoxide, Potassium Bromate, and Hydrogen Peroxide in Base Excision Repair Proficient and Deficient Cells

    Directory of Open Access Journals (Sweden)

    N. Cooley

    2013-01-01

    Full Text Available The DNA mismatch repair (MMR and base excision repair (BER systems are important determinants of cellular toxicity following exposure to agents that cause oxidative DNA damage. To examine the interactions between these different repair systems, we examined whether toxicity, induced by t-BOOH and KBrO3, differs in BER proficient (Mpg+/+, Nth1+/+ and deficient (Mpg−/−, Nth1−/− mouse embryonic fibroblasts (MEFs following Msh2 knockdown of between 79 and 88% using an shRNA expression vector. Msh2 knockdown in Nth1+/+ cells had no effect on t-BOOH and KBrO3 induced toxicity as assessed by an MTT assay; knockdown in Nth1−/− cells resulted in increased resistance to t-BOOH and KBrO3, a result consistent with Nth1 removing oxidised pyrimidines. Msh2 knockdown in Mpg+/+ cells had no effect on t-BOOH toxicity but increased resistance to KBrO3; in Mpg−/− cells, Msh2 knockdown increased cellular sensitivity to KBrO3 but increased resistance to t-BOOH, suggesting a role for Mpg in removing DNA damage induced by these agents. MSH2 dependent and independent pathways then determine cellular toxicity induced by oxidising agents. A complex interaction between MMR and BER repair systems, that is, exposure dependent, also exists to determine cellular toxicity.

  1. The Effect of Msh2 Knockdown on Toxicity Induced by tert-Butyl-hydroperoxide, Potassium Bromate, and Hydrogen Peroxide in Base Excision Repair Proficient and Deficient Cells

    Science.gov (United States)

    Cooley, N.; Elder, R. H.; Povey, A. C.

    2013-01-01

    The DNA mismatch repair (MMR) and base excision repair (BER) systems are important determinants of cellular toxicity following exposure to agents that cause oxidative DNA damage. To examine the interactions between these different repair systems, we examined whether toxicity, induced by t-BOOH and KBrO3, differs in BER proficient (Mpg +/+, Nth1 +/+) and deficient (Mpg −/−, Nth1 −/−) mouse embryonic fibroblasts (MEFs) following Msh2 knockdown of between 79 and 88% using an shRNA expression vector. Msh2 knockdown in Nth1 +/+ cells had no effect on t-BOOH and KBrO3 induced toxicity as assessed by an MTT assay; knockdown in Nth1 −/− cells resulted in increased resistance to t-BOOH and KBrO3, a result consistent with Nth1 removing oxidised pyrimidines. Msh2 knockdown in Mpg +/+ cells had no effect on t-BOOH toxicity but increased resistance to KBrO3; in Mpg −/− cells, Msh2 knockdown increased cellular sensitivity to KBrO3 but increased resistance to t-BOOH, suggesting a role for Mpg in removing DNA damage induced by these agents. MSH2 dependent and independent pathways then determine cellular toxicity induced by oxidising agents. A complex interaction between MMR and BER repair systems, that is, exposure dependent, also exists to determine cellular toxicity. PMID:23984319

  2. Crystal structure of (1R,4R-tert-butyl 3-oxo-2-oxa-5-azabicyclo[2.2.2]octane-5-carboxylate

    Directory of Open Access Journals (Sweden)

    Suvratha Krishnamurthy

    2015-07-01

    Full Text Available In the title compound, C11H17NO4, commonly known as N-tert-butoxycarbonyl-5-hydroxy-d-pipecolic acid lactone, the absolute configuration is (1R,4R due to the enantiomeric purity of the starting material which remains unchanged during the course of the reaction. In the crystal there no intermolecular hydrogen bonds.

  3. Toxicity of substituted benzene derivatives to four chemolithotrophic ...

    African Journals Online (AJOL)

    The toxicity of benzene, hydroxylbenzene (phenol), chlorobenzene, methylbenzene (toluene) and dimethylbenzene (xylene) to four chemolithotrophic bacteria (Nitrosomonas, Nitrobacter, Thiobacillus and Leptothrix isolated from the New Calabar River water was investigated. The static method for acute toxicity assessment ...

  4. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  5. Non-Collinearity in Small Magnetic Cobalt-Benzene Molecules

    CERN Document Server

    González, J W; Delgado, F; Aguilera-Granja, F; Ayuela, A

    2016-01-01

    Cobalt clusters covered with benzene in the form of rice-ball structures have recently been synthesized using laser ablation. Here, we investigate the types of magnetic order such clusters have, and whether they retain any magnetic order at all. We use different density functional theory (DFT) methods to study the experimentally relevant three cobalt atoms surrounded by benzene rings. We found that the benzene rings induce a ground state with non-collinear magnetization, with the magnetic moments localized on the cobalt centers and lying on the plane formed by the three cobalt atoms. This is surprising because nanostructures and small clusters based on pure cobalt typically have a predominantly ferromagnetic order, and additional organic ligands such as benzene tend to remove the magnetization. We analyze the magnetism of such a cluster using an anisotropic Heisenberg model where the involved parameters are obtained by a comparison with the DFT results. Moreover, we propose electron paramagnetic resonance as ...

  6. Intrinsic and enhanced biodegradation of benzene in strongly reduced aquifers

    NARCIS (Netherlands)

    Heiningen, W.N.M. van; Rijnaarts, H.H.M; Langenhoff, A.A.M.

    1999-01-01

    Laboratory microcosm studies were performed to examine intrinsic and enhanced benzene bioremediation using five different sediment and groundwater samples from three deeply anaerobic aquifers sited in northern Netherlands. The influence of addition of nitrate, sulfate, limited amounts of oxygen, and

  7. Perspectives on risk assessment impact of recent reports on benzene

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.S.; Lucier, G. (Division of Biometry and Risk Assessment, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC (United States))

    1992-01-01

    Very sensitive methods that can detect the benzene metabolite muconic acid (MA) in the urine of virtually all members of the general population have recently become available and have been used in a few occupational studies as a marker of benzene exposure. Preliminary findings from these studies suggest that urinary MA may be a reliable marker of occupational exposure to greater than 5 ppm benzene. It was also consistently observed that a certain proportion of the general population have urinary MA levels compatible with those seen in persons occupationally exposed to greater than 1 ppm benzene. It is unlikely that these elevated levels can be explained solely as being artifactual. The frequency with which they occur for a given individual, and the duration with which they are maintained, are not known. Information on these two factors is needed in order to adequately assess whether or not these levels present a significant risk for a segment of the general population.30 references.

  8. Ion-Selective Ionic Polymer Metal Composite (IPMC) Actuator Based on Crown Ether Containing Sulfonated Poly(Arylene Ether Ketone)

    NARCIS (Netherlands)

    Tas, Sinem; Zoetebier, Bram; Sardan Sukas, Ö.; Bayraktar, Muharrem; Hempenius, Mark A.; Vancso, Gyula J.; Nijmeijer, Dorothea C.

    This study introduces the concept of ion selective actuation in polymer metal composite actuators, employing crown ether bearing aromatic polyether materials. For this purpose, sulfonated poly(arylene ether ketone) (SPAEK) and crown ether containing SPAEK with molar masses suitable for membrane

  9. Preparation and characterization of monovalent ion selective cation exchange membranes based on sulphonated poly(ether ether ketone)

    NARCIS (Netherlands)

    Balster, J.H.; Krupenko, O.; Krupenko, O.; Punt, Ineke G.M.; Stamatialis, Dimitrios; Wessling, Matthias

    2005-01-01

    This paper analyses the separation properties of various commercial cation exchange membranes (CEMs) and tailor made membranes based on sulphonated poly(ether ether ketone) and poly(ether sulphone) for binary electrolyte solutions containing protons and calcium ions. All membranes are thoroughly

  10. Positronium quenching in liquid and solid octanol and benzene

    DEFF Research Database (Denmark)

    Shantarovich, V.P.; Mogensen, O.E.; Goldanskii, V.I.

    1970-01-01

    The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase.......The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase....

  11. Determination of benzene in exhaust gas from biofuels. Final report; Bestimmung von Benzol im Abgas von Biokraftstoffen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Dutz, M.; Buenger, J.; Gnuschke, H.; Halboth, H.; Gruedl, P.; Krahl, J.

    2001-10-01

    With the advance of environmental legislation and practices oriented towards sustainability renewable energy resources are becoming increasingly important. Use of replenishable raw materials helps preserve fossil resources. In the fuel sector the most widely used replenishable materials are rape methyl ester (RME) and ethyl tertiary butyl ether (ETBE). The purpose of the present project on the ''Determination of benzene in exhaust gas from biofuels'' was to generate orienting data on the potential health relevance of mixtures of fossil and renewable fuel intended for use in spark ignition and diesel engines. This included a determination of benzene emissions and the mutagenicity of particles. Beyond the applied-for scope of research measurements were also performed on the test engine's toluene, ethyl benzene and xylene emissions as well as on the smoke spot number and nitrogen oxide (NO{sub x}) and hydrocarbon (HC) emissions of the diesel engine. [German] Regenerative Energien gewinnen durch die Umweltgesetzgebungen und das Streben nach einer nachhaltigen Entwicklung zunehmend an Bedeutung. Durch die Verwendung nachwachsender Rohstoffe koennen die fossilen Ressourcen geschont werden. Im Kraftstoffsektor sind hier hauptsaechlich Rapsoelmethylester (RME) und optional Ethyltertiaerbutylether (ETBE) zu nennen. Um fuer Diesel- und Ottomotoren insbesondere mit Blick auf Kraftstoffgemische aus fossilen und regenerativen Komponenten orientierende Daten ueber eine potenzielle Gesundheitsrelevanz zu generieren, wurde das Projekt 'Bestimmung von Benzol im Abgas von Biokraftstoffen' durchgefuehrt. Neben der Benzolemission wurde die Mutagenitaet der Partikeln ermittelt. Ueber den beantragten Untersuchungsrahmen hinaus wurden die Tuluol-, Ethylbenzol-, und Xylolemissionen der eingesetzten Motoren, sowie die Russzahl (RZ) und die Stickoxid- (NO{sub x}) und Kohlenwasserstoffemissionen (HC) des Dieselmotors bestimmt. (orig.)

  12. Organometallic chemistry using partially fluorinated benzenes.

    Science.gov (United States)

    Pike, Sebastian D; Crimmin, Mark R; Chaplin, Adrian B

    2017-03-28

    Fluorobenzenes, in particular fluorobenzene (FB) and 1,2-difluorobenzene (1,2-DiFB), are increasingly becoming recognised as versatile solvents for conducting organometallic chemistry and transition-metal-based catalysis. The presence of fluorine substituents reduces the ability to donate π-electron density from the arene and consequently fluorobenzenes generally bind weakly to metal centres, allowing them to be used as essentially non-coordinating solvents or as readily displaced ligands. In this context, examples of well-defined complexes of fluorobenzenes are discussed, including trends in binding strength with increasing fluorination and different substitution patterns. Compared to more highly fluorinated benzenes, FB and 1,2-DiFB typically demonstrate greater chemical inertness, however, C-H and C-F bond activation reactions can be induced using appropriately reactive transition metal complexes. Such reactions are surveyed, including catalytic examples, not only to provide perspective for the use of FB and 1,2-DiFB as innocent solvent media, but also to highlight opportunities for their exploitation in contemporary organic synthesis.

  13. Perinatal immunotoxicity of benzene toward mouse B cell development

    Energy Technology Data Exchange (ETDEWEB)

    Wierda, D.; King, A.; Luebke, R.; Reasor, M.; Smialowicz, R.J.

    1989-01-01

    Benzene is widely used by chemical industries and exposure to benzene has been shown experimentally to be immunotoxic in adult animals. The present study addressed whether exposure of fetuses in utero to benzene compromises the development of fetal B lymphopoiesis and whether B-lymphocyte development recovers postnatally. Pregnant BALB/C dams were given intraperitoneal injections of benzene (100 mg/kg, twice daily) from day 12.5 of gestation through day 19.5 of gestation. Phenotypic analysis revealed that fetal liver cell suspensions from embryos exposed in utero contained fewer pre-B cells and B cells than corresponding controls. Fetal liver cell cultures established from these embryos also produced fewer B cells. In contrast, pre-B cells were elevated in the livers of 8-day-old neonates that had been exposed to benzene in utero. Moreover, responsiveness to the B-cell mitogen, LPS, was significantly decreased in spleen cell cultures derived from these neonates. The results indicate that in utero exposure to high concentrations of benzene alters fetal B lymphopoiesis and may compromise immune responsiveness postnatally.

  14. Monitoring of the Gasoline Oxygenate MTBE and BTEX Compounds in Groundwater in Catalonia (Northeast Spain

    Directory of Open Access Journals (Sweden)

    J. Fraile

    2002-01-01

    Full Text Available Headspace (HS gas chromatography with flame ionisation detection (HS-GC-FID and purge and trap (P gas chromatography-mass spectrometry (P were used for the determination of methyl-tert-butyl ether (MTBE and benzene, toluene, and xylenes (BTEX in groundwater. In this work, we present the first data on the levels of MTBE and BTEX in different groundwater wells in the area of Catalonia (northeast Spain. This monitoring campaign corresponded to 28 groundwater wells that were located near petrol service stations, oil refinery storage tanks, and/or chemical industry at different locations of Catalonia during the period of 1998/1999. The levels of MTBE detected varied between 4—300 μg/l, but two sites had MTBE levels up to 3 and 13 mg/l. In many cases, the BTEX levels were below 1 μg/l, whereas 7 sites had levels varying from 19 μg/l up to 3 mg/l. Most of them were related to leakage from underground tanks in petrol service stations, while the remaining three corresponded respectively to chemical industrial pollution of undetermined origin and to a leak from high-ground petrol tanks in petrochemical refinery factories. The aquifers involved were constituted by detritus coarse materials, sands, and conglomerates. Piezometric levels were roughly comprised between 3 and 40 m, and permeability (K and transmissivity (T values were estimated from field measurements.

  15. Calibration transfer for solving the signal instability in quantitative headspace-mass spectrometry.

    Science.gov (United States)

    Pérez Pavón, José Luis; del Nogal Sánchez, Miguel; García Pinto, Carmelo; Fernández Laespada, M Esther; Moreno Cordero, Bernardo

    2003-11-15

    It is reported that calibration transfer is able to compensate the variations in sensitivity in direct coupling of a headspace sampler to a mass spectrometer when used for quantification purposes using multivariate calibration techniques. This strategy of signal stability compensation allows the use of models constructed from large calibration standard sets without having to repeat their measurement even though variations occur in sensitivity, which may or may not be constant along the mass range. This technique offers advantages over the use of internal standards in this methodology and only requires the measurement of a small number of transfer samples with each set of unknown samples. The results obtained in the determination of six volatile organic compounds-benzene, toluene, ethylbenzene, and m-xylene (BTEX), methyl tert-butyl ether (MTBE), and mesitylene-are reported. To obtain an appropriate calibration set, a Plackett-Burman design with five levels of concentration for each component was employed. A PLS multivariate calibration model was constructed with a group of 25 samples. For selection of the optimum number of principal components, an external validation set (5 samples) was used and the prediction capacity of this set was checked with an additional group of samples that had not been used either in the construction or in the validation of the model. The results obtained can be considered highly satisfactory, and the methodology was successfully tested with natural matrixes (river and tap water).

  16. Determination of benzene, toluene ,ethyl benzene and xylene (BTEX) in ambient air painting workshops car compared to the air surrounding residential areas during winter 1394 in Yazd city

    National Research Council Canada - National Science Library

    MH Salmani; MH Ehrampoush; MH Mosadeg; S MH Sharifi

    2017-01-01

    Abstract Title: Determination of benzene, toluene ,ethyl benzene and xylene (BTEX) in ambient air painting workshops car compared to the air surrounding residential areas during winter 1394 in Yazd city...

  17. Low-temperature MTBE biodegradation in aquifer sediments with a history of low, seasonal ground water temperatures

    Science.gov (United States)

    Bradley, P.M.; Landmeyer, J.E.

    2006-01-01

    Sediments from two shallow, methyl tert-butyl ether (MTBE)-contaminated aquifers, with mean ground water temperatures ???10??C, demonstrated significant mineralization of [U-14C] MTBE to 14CO 2 at incubation temperatures as low as 4??C. These results indicate that microbial degradation can continue to contribute to the attenuation of MTBE in ground water under wintertime, low-temperature conditions. ?? 2006 National Ground Water Association.

  18. Highly efficient chemoselective deprotection of O,O-acetals and O,O-ketals catalyzed by molecular iodine in acetone.

    Science.gov (United States)

    Sun, Jianwei; Dong, Yanmei; Cao, Liya; Wang, Xinyan; Wang, Shaozhong; Hu, Yuefei

    2004-12-10

    An extremely convenient method for deprotection of acetals and ketals catalyzed by molecular iodine (10 mol %) in acetone is reported. The protocol achieved the deprotection of acyclic or cyclic O,O-acetals and O,O-ketals in excellent yields within a few minutes under neutral conditions. The double bond, hydroxyl group, and acetate group remained unchanged, and the highly acid-sensitive furyl, tert-butyl ethers, and ketone-oxime stayed intact under these conditions.

  19. Environmental Compliance Assessment and Management Program

    Science.gov (United States)

    1994-04-01

    grading of roads, or the clearing of land - application of asphalt , water, or suitable chemicals on roads, material stockpiles, and other surfaces... isocyanate 624839 Methyl methacrylate 80626 Methyl tert butyl ether 1634044 4,4-Methylene bis(2-chloroaniline) 101144 Methylene chloride (Dichloromethane... asphaltic pavement, steel, plaster, glass, and minor amounts of other metals, such as copper. Construc- tion and demolition waste does not include

  20. Ether bridge formation in loline alkaloid biosynthesis

    Science.gov (United States)

    Pan, Juan; Bhardwaj, Minakshi; Faulkner, Jerome R.; Nagabhyru, Padmaja; Charlton, Nikki D.; Higashi, Richard M.; Miller, Anne-Frances; Young, Carolyn A.; Grossman, Robert B.; Schardl, Christopher L.

    2014-01-01

    Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of a novel alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes differing in alkaloid profiles were sequenced, revealing that those with mutated lolO accumulated exo-1-acetamidopyrrolizidine but no lolines. Heterologous expression of wild-type lolO complemented a lolO mutant, resulting in the production of N-acetylnorloline. These results indicated that the non-heme iron oxygenase, LolO, is required for ether bridge formation, probably through oxidation of exo-1-acetamidopyrrolizidine. PMID:24374065

  1. Synthesis of New Liquid Crystalline Diglycidyl Ethers

    Directory of Open Access Journals (Sweden)

    Issam Ahmed Mohammed

    2012-01-01

    Full Text Available The phenolic Schiff bases I–VI were synthesized by condensation reactions between various diamines, namely o-dianisidine, o-tolidine and ethylenediamine with vanillin or p-hydroxybenzaldehyde and subsequent reactions between these phenolic Schiff bases and epichlorohydrin to produce new diglycidyl ethers Ia–VIa. The structures of these compounds were confirmed by CHN, FT-IR, 1H-NMR, and 13C-NMR spectroscopy. Their thermotropic liquid crystalline behavior was studied using differential scanning calorimetry (DSC and polarizing optical microscopy (POM. All the diglycidyl ethers prepared exhibit nematic mesophases, except for Va and VIa, which did not show any transition mesophases, but simply flow to liquids.

  2. Model for Photodegradation of Polybrominated Diphenyl Ethers

    Czech Academy of Sciences Publication Activity Database

    Veselý, M.; Vajglová, Zuzana; Kotas, Petr; Křišťál, Jiří; Ponec, Robert; Jiřičný, Vladimír

    2015-01-01

    Roč. 22, č. 7 (2015), s. 4949-4963 ISSN 0944-1344 R&D Projects: GA ČR GA104/09/0880; GA ČR(CZ) GAP105/12/0664 Institutional support: RVO:67985858 ; RVO:67179843 Keywords : polybrominated diphenyl ethers * photodegradation model * quantum chemical calculation Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.760, year: 2015

  3. Alkyl aryl ethers in lignite solubilization

    Energy Technology Data Exchange (ETDEWEB)

    Mustral, A.M.; Cebolla, V.L.; Gavilan, J.M.

    1985-03-01

    The FT-I.R. and /sup 1/H N.M.R. spectroscopic analyses of oils or maltenes from a Spanish lignite (Utrillas, Teruel), are reported. These oils were obtained by depolymerization with alkyl aromatic ethers (anisole, 3-methyl anisole and 1,3-dimethoxybenzene) catalyzed by Lewis acids ZnCl/sub 2/, AlCl/sub 3/, SbCl/sub 3/ and BF/sub 3/ (as boron trifluoride etherate), at atmospheric pressure and temperatures <220/sup 0/C. Bands due to aromatic ethers in the I.R. and N.M.R. spectra of the oils obtained by depolymerization indicate solvent incorporation. Oils obtained by direct lignite extraction showed 25% aromatic H and some H /sub i/ (approx. = 3%) without OH groups. These appeared in some oils obtained by depolymerization with AlCl/sub 3/ and were due to secondary reactions with the aromatic extract. Oils derived from processes with good yields showed increases in aromaticity. The extent of substitution of aromatic rings in oils obtained by depolymerization was less than for oils directly extracted. All the oils studied show a low degree of condensation.

  4. Nikola Tesla, the Ether and his Telautomaton

    Science.gov (United States)

    Milar, Kendall

    2014-03-01

    In the nineteenth century physicists' understanding of the ether changed dramatically. New developments in thermodynamics, energy physics, and electricity and magnetism dictated new properties of the ether. These have traditionally been examined from the perspective of the scientists re-conceptualizing the ether. However Nikola Tesla, a prolific inventor and writer, presents a different picture of nineteenth century physics. Alongside the displays that showcased his inventions he presented alternative interpretations of physical, physiological and even psychical research. This is particularly evident in his telautomaton, a radio remote controlled boat. This invention and Tesla's descriptions of it showcase some of his novel interpretations of physical theories. He offered a perspective on nineteenth century physics that focused on practical application instead of experiment. Sometimes the understanding of physical theories that Tesla reached was counterproductive to his own inventive work; other times he offered new insights. Tesla's utilitarian interpretation of physical theories suggests a more scientifically curious and invested inventor than previously described and a connection between the scientific and inventive communities.

  5. Synthesis of disodium [benzene-U-{sup 14}C]-(4-chlorophenylthio)methylenediphosphonate, [benzene-U-{sup 14}C]-tiludronate

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, Alain; Ellames, G.J. [Alnwick Research Centre (United Kingdom). Dept. of Metabolism and Pharmacokinetics

    1995-12-31

    Disodium [benzene-U-{sup 14}C]-(4-chlorophenylithio)methylenediphosphonate, [benzene-{sup 14}C]-Tiludronate, 2, has been prepared in six steps from [benzene-U-{sup 14}C]-acetanilide in an overall radiochemical yield of 41%. A key step in this transformation was the efficient conversion of [U-{sup 14}C]-4-chloroaniline to [benzene-U-{sup 14}C]-4-chlorophenylthiocyanate, 5, in 83% yield by treatment of the corresponding diazonium salt, 9 with iron(111) thiocyanate. It should be noted that formation of the isomeric [benzene-U-{sup 14}C]-4-chlorophenylisothiocyanate, 11, as a byproduct, was observed in only {approx} 1% yield. (author).

  6. Products of the Benzene + O(3P) Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Meloni, Giovanni; Trevitt, Adam J.; Epifanovsky, Evgeny; Krylov, Anna I.; Sirjean, Baptiste; Dames, Enoch; Wang, Hai

    2009-12-21

    The gas-phase reaction of benzene with O(3P) is of considerable interest for modeling of aromatic oxidation, and also because there exist fundamental questions concerning the prominence of intersystem crossing in the reaction. While its overall rate constant has been studied extensively, there are still significant uncertainties in the product distribution. The reaction proceeds mainly through the addition of the O atom to benzene, forming an initial triplet diradical adduct, which can either dissociate to form the phenoxy radical and H atom, or undergo intersystem crossing onto a singlet surface, followed by a multiplicity of internal isomerizations, leading to several possible reaction products. In this work, we examined the product branching ratios of the reaction between benzene and O(3P) over the temperature range of 300 to 1000 K and pressure range of 1 to 10 Torr. The reactions were initiated by pulsed-laser photolysis of NO2 in the presence of benzene and helium buffer in a slow-flow reactor, and reaction products were identified by using the multiplexed chemical kinetics photoionization mass spectrometer operating at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory. Phenol and phenoxy radical were detected and quantified. Cyclopentadiene and cyclopentadienyl radical were directly identified for the first time. Finally, ab initio calculations and master equation/RRKM modeling were used to reproduce the experimental branching ratios, yielding pressure-dependent rate expressions for the reaction channels, including phenoxy + H, phenol, cyclopentadiene + CO, which are proposed for kinetic modeling of benzene oxidation.

  7. Reductive dehalogenation of dichlorobenzenes and monochlorobenzene to benzene in microcosms.

    Science.gov (United States)

    Fung, Jennifer M; Weisenstein, Brian P; Mack, E Erin; Vidumsky, John E; Ei, Tom A; Zinder, Stephen H

    2009-04-01

    Anaerobic microcosms were constructed using sediments from a historically chlorobenzene-contaminated site and were provided with yeast extract as an electron donor. In these methanogenic microcosms, all three isomers of dichlorobenzene (DCB) were reductively dehalogenated to monochlorobenzene (MCB) when added together or individually, with 1,2-DCB dehalogenation being the most rapid and 1,4-DCB the slowest. When nearly all of the DCBs were consumed, benzene was detected and its accumulation was concomitant with MCB disappearance. Small amounts of toluene were also detected along with benzene. Subsequent MCB doses were also converted to benzene, and benzene reached levels in excess of 5000 micromol/L in some microcosms. An initial DCB dose stimulated, and in some cases was necessary for, MCB dehalogenation. Subsequent doses of DCB or MCB were dehalogenated more rapidly than previous ones, consistent with a growth-related process. Addition of a ca. 4% inoculum from microcosms that had consumed DCBs or MCB stimulated DCB and MCB dehalogenation in fresh microcosms, also indicative of growth and suggests thatthe chlorobenzene-dehalogenating microorganisms in these microcosms are candidates for bioaugmentation at anaerobic DCB or MCB contaminated sites. These studies add to evidence that benzene production from chlorobenzenes needs to be considered when modeling processes at contaminated sites.

  8. From ether theory to ether theology: Oliver Lodge and the physics of immortality.

    Science.gov (United States)

    Raia, Courtenay Grean

    2007-01-01

    This article follows the development of physicist Oliver Lodge's religio-scientific worldview, beginning with his reticent attraction to metaphysics in the early 1880s to the full formulation of his "ether theology" in the late 1890s. Lodge undertook the study of psychical phenomena such as telepathy, telekinesis, and "ectoplasm" to further his scientific investigations of the ether, speculating that electrical and psychical manifestations were linked phenomena that described the deeper underlying structures of the universe, beneath and beyond matter. For Lodge, to fully understand the ether was to force from the universe an ultimate Revelation, and psychical research, as the most modern and probatory science, was poised to replace religion as the means of that disclosure. (c) 2007 Wiley Periodicals, Inc.

  9. Rapid separation of cyanidin-3-glucoside and cyanidin-3-rutinoside from crude mulberry extract using high-performance countercurrent chromatography and establishment of a volumetric scale-up process.

    Science.gov (United States)

    Choi, Soo-Jung; Choi, Janggyoo; Lee, Chang Uk; Yoon, Shin Hee; Bae, Soo Kyung; Chin, Young-Won; Kim, Jinwoong; Yoon, Kee Dong

    2015-06-01

    This study describes the rapid separation of mulberry anthocyanins; namely, cyanidin-3-glucoside and cyanidin-3-rutinoside, using high-performance countercurrent chromatography, and the establishment of a volumetric scale-up process from semi-preparative to preparative-scale. To optimize the separation parameters, biphasic solvent systems composed of tert-butyl methyl ether/n-butanol/acetonitrile/0.01% trifluoroacetic acid, flow rate, sample amount and rotational speed were evaluated for the semi-preparative-scale high-performance countercurrent chromatography. The optimized semi-preparative-scale high-performance countercurrent chromatography parameters (tert-butyl methyl ether/n-butanol/acetonitrile/0.01% trifluoroacetic acid, 1:3:1:5, v/v; flow rate, 4.0 mL/min; sample amount, 200-1000 mg; rotational speed, 1600 rpm) were transferred directly to a preparative-scale (tert-butyl methyl ether/n-butanol/acetonitrile/0.01% trifluoroacetic acid, 1:3:1:5, v/v; flow rate, 28 mL/min; sample amount, 5.0-10.0 g; rotational speed, 1400 rpm) to achieve separation results identical to cyanidin-3-glucoside and cyanidin-3-rutinoside. The separation of mulberry anthocyanins using semi-preparative high-performance countercurrent chromatography and its volumetric scale-up to preparative-scale was addressed for the first time in this report. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Coupling of a headspace autosampler with a programmed temperature vaporizer for stable carbon and hydrogen isotope analysis of volatile organic compounds at microgram per liter concentrations.

    Science.gov (United States)

    Herrero-Martín, Sara; Nijenhuis, Ivonne; Richnow, Hans H; Gehre, Matthias

    2015-01-20

    One major challenge for the environmental application of compound-specific stable isotope analysis (CSIA) is the necessity of efficient sample treatment methods, allowing isolation of a sufficient mass of organic contaminants needed for accurate measurement of the isotope ratios. Here, we present a novel preconcentration technique--the coupling of a headspace (HS) autosampler with a programmed temperature vaporizer (PTV)--for carbon (δ(13)C) and hydrogen (δ(2)H) isotope analysis of volatile organic compounds in water at concentrations of tens of micrograms per liter. The technique permits large-volume injection of headspace samples, maintaining the principle of simple static HS extraction. We developed the method for multielement isotope analysis (δ(13)C and δ(2)H) of methyl tert-butyl ether (MTBE), benzene, toluene, ethylbenzene, and o-xylene (BTEX), and analysis of δ(13)C for chlorinated benzenes and ethenes. Extraction and injection conditions were optimized for maximum sensitivity and minimum isotope effects. Injection of up to 5 mL of headspace sample from a 20 mL vial containing 13 mL of aqueous solution and 5 g of NaCl (10 min of incubation at 90 °C) resulted in accurate δ(13)C and δ(2)H values. The method detection limits (MDLs) for δ(13)C were from 2 to 60 μg/L (MTBE, BTEX, chlorinated ethenes, and benzenes) and 60-97 μg/L for δ(2)H (MTBE and BTEX). Overall, the HS-PTV technique is faster, simpler, isotope effect-free, and requires fewer treatment steps and less sample volume than other extraction techniques used for CSIA. The environmental applicability was proved by the analysis of groundwater samples containing BTEX and chlorinated contaminants at microgram per liter concentrations.

  11. Comparative Environmental Performance of Two-Diesel-Fuel Oxygenates: Dibutyl Maleate (DBM) and Triproplyene Glycol Monomethyl Ether (TGME)

    Energy Technology Data Exchange (ETDEWEB)

    Layton, D.W.; Marchetti, A.A.

    2001-10-01

    Many studies have shown that the addition of oxygen bearing compounds to diesel fuel can significantly reduce particulate emissions. To assist in the evaluation of the environmental performance of diesel-fuel oxygenates, we have implemented a suite of diagnostic models for simulating the transport of compounds released to air, water, and soils/groundwater as well as regional landscapes. As a means of studying the comparative performance of DBM and TGME, we conducted a series of simulations for selected environmental media. Benzene and methyl tertiary butyl ether (MTBE) were also addressed because they represent benchmark fuel-related compounds that have been the subject of extensive environmental measurements and modeling. The simulations showed that DBM and TGME are less mobile in soil because of reduced vapor-phase transport and increased retention on soil particles. The key distinction between these two oxygenates is that DBM is predicted to have a greater potential than TGME for aerobic biodegradation, based on chemical structure.

  12. 1-[(3-Benzyloxy-2-nitrophenoxymethyl]benzene

    Directory of Open Access Journals (Sweden)

    Hoong-Kun Fun

    2012-08-01

    Full Text Available The asymmetric unit of the title compound, C20H17NO4, consists of two crystallographically independent molecules. In one of the molecules, the central benzene ring forms dihedral angles of 2.26 (6 and 58.68 (6° with the terminal benzene rings and the dihedral angle between the terminal benzene rings is 56.45 (6°. The corresponding values for the other molecule are 35.17 (6, 70.97 (6 and 69.62 (6°, respectively. In the crystal, an inversion dimer linked by a pair of C—H...O hydrogen bonds occurs for one of the unique molecules. C—H...π and π–π [centroid–centroid distances = 3.7113 (8 and 3.7216 (7 Å] interactions link the components into a three-dimensional network.

  13. [Myelofibrosis in a benzene-exposed cleaning worker].

    Science.gov (United States)

    Bausà, Roser; Navarro, Lydia; Cortès-Franch, Imma

    Long-term exposure to benzene has been associated with several blood malignancies, including aplastic anemia, myeloproliferative neoplasms, and different leukemias. We present a case of primary myelofibrosis in a 59-year-old woman who worked as a cleaner at a car dealership and automobile mechanic shop. For 25 years, she used gasoline as a degreaser and solvent to clean engine parts, floors and work desks on a daily basis. She was referred by her primary care provider to the Occupational Health Unit of Barcelona to assess whether her illness was work-related. Review of her job history and working conditions revealed chronic exposure to benzene in the absence of adequate preventive measures. An association between benzene exposure and myeloproliferative disease was established, suspicious for an occupational disease. Copyright belongs to the Societat Catalana de Salut Laboral.

  14. 40 CFR 721.10067 - Ether amine phosphonate salt (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ether amine phosphonate salt (generic... Specific Chemical Substances § 721.10067 Ether amine phosphonate salt (generic). (a) Chemical substances... ether amine phosphonate salt (PMNs P-05-57, P-05-58, P-05-59, P-05-61, P-05-62, P-05-63, P-05-64, and P...

  15. Draft Benzene Case Study Review - Second Prospective Report Study Science Advisory Board Review, March 2008

    Science.gov (United States)

    EPA developed a methodology for estimating the health benefits of benzene reductions and has applied it in a metropolitan-scale case study of the benefits of CAA controls on benzene emissions to accompany the main 812 analysis.

  16. Benzene solubility in ionic liquids: working toward an understanding of liquid clathrate formation.

    Science.gov (United States)

    Pereira, Jorge F B; Flores, Luis A; Wang, Hui; Rogers, Robin D

    2014-11-17

    The solubility of benzene in 15 imidazolium, pyrrolidinium, pyridinium, and piperidinium ionic liquids has been determined; the resulting, benzene-saturated ionic liquid solutions, also known as liquid clathrates, were examined with (1) H and (19) F nuclear magnetic resonance spectroscopy to try and understand the molecular interactions that control liquid clathrate formation. The results suggest that benzene interacts primarily with the cation of the ionic liquid, and that liquid clathrate formation (and benzene solubility) is controlled by the strength of the cation-anion interactions, that is, the stronger the cation-anion interaction, the lower the benzene solubility. Other factors that were determined to be important in the final amount of benzene in any given liquid clathrate phase included attractive interactions between the anion and benzene (when significant), and larger steric or free volume demands of the ions, both of which lead to greater benzene solubility. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Metagenomic and proteomic analyses to elucidate the mechanism of anaerobic benzene degradation

    Energy Technology Data Exchange (ETDEWEB)

    Abu Laban, Nidal [Helmholtz (Germany)

    2011-07-01

    This paper presents the mechanism of anaerobic benzene degradation using metagenomic and proteomic analyses. The objective of the study is to find out the microbes and biochemistry involved in benzene degradation. Hypotheses are proposed for the initial activation mechanism of benzene under anaerobic conditions. Two methods for degradation, molecular characterization and identification of benzene-degrading enzymes, are described. The physiological and molecular characteristics of iron-reducing enrichment culture are given and the process is detailed. Metagenome analysis of iron-reducing culture is presented using a pie chart. From the metagenome analysis of benzene-degrading culture, putative mobile element genes were identified in the aromatic-degrading configurations. Metaproteomic analysis of iron-reducing cultures and the anaerobic benzene degradation pathway are also elucidated. From the study, it can be concluded that gram-positive bacteria are involved in benzene degradation under iron-reducing conditions and that the catalysis mechanism of putative anaerobic benzene carboxylase needs further investigation.

  18. Characterization of changes in gene expression and biochemical pathways at low levels of benzene exposure

    NARCIS (Netherlands)

    Thomas, Reuben; Hubbard, Alan E.; McHale, Cliona M.; Zhang, Luoping; Rappaport, Stephen M.; Lan, Qing; Rothman, Nathaniel; Vermeulen, Roel|info:eu-repo/dai/nl/216532620; Guyton, Kathryn Z.; Jinot, Jennifer; Sonawane, Babasaheb R.; Smith, Martyn T.

    2014-01-01

    Benzene, a ubiquitous environmental pollutant, causes acute myeloid leukemia (AML). Recently, through transcriptome profiling of peripheral blood mononuclear cells (PBMC), we reported dose-dependent effects of benzene exposure on gene expression and biochemical pathways in 83 workers exposed across

  19. Benzene Case Study Final Report - Second Prospective Report Study Science Advisory Board Review, July 2009

    Science.gov (United States)

    EPA developed a methodology for estimating the health benefits of benzene reductions and has applied it in a metropolitan-scale case study of the benefits of CAA controls on benzene emissions to accompany the main 812 analysis.

  20. Silane Cross-Linked Sulfonted Poly(Ether Ketone/Ether Benzimidazoles for Fuel Cell Applications

    Directory of Open Access Journals (Sweden)

    Zilu Yao

    2017-11-01

    Full Text Available γ-(2,3-epoxypropoxy propyltrimethoxysilane (KH-560 was incorporated in various proportions into side-chain-type sulfonated poly(ether ketone/ether benzimidazole (SPEKEBI as a crosslinker, to make membranes with high ion exchange capacities and excellent performance for direct methanol fuel cells (DMFCs. Systematical measurements including Fourier transform infrared (FT-IR, scanning electron microscopy-energy-dispersive and X-ray photoelectron spectroscopy (XPS proved the complete disappearance of epoxy groups in KH-560 and the existence of Si in the membranes. The resulting membranes showed increased mechanical strength and thermal stability compared to the unmodified sulfonated poly(ether ketone/ether benzimidazole membrane in appropriate doping amount. Meanwhile, the methanol permeability has decreased, leading to the increase of relative selectivities of SPEKEBI-x-SiO2 membranes. Furthermore, the H2/O2 cell performance of SPEKEBI-2.5-SiO2 membrane showed a much higher peak power density compared with the pure SPEKEBI memrbrane.