Sample records for methyl tert butyl

  1. Microbial degradation of methyl tert-butyl ether and tert-butyl alcohol in the subsurface

    Microsoft Academic Search

    Torsten C. Schmidt; Mario Schirmer; Holger Weiß; Stefan B. Haderlein

    2004-01-01

    The fate of fuel oxygenates such as methyl tert-butyl ether (MTBE) in the subsurface is governed by their degradability under various redox conditions. The key intermediate in degradation of MTBE and ethyl tert-butyl ether (ETBE) is tert-butyl alcohol (TBA) which was often found as accumulating intermediate or dead-end product in lab studies using microcosms or isolated cell suspensions. This review

  2. Photocatalytic oxidation of gas-phase methyl tert-butyl ether and tert-butyl alcohol

    Microsoft Academic Search

    Sergei Preis; John L. Falconer; Raquel del Prado Asensio; Nuria Capdet Santiago; Anna Kachina; Juha Kallas

    2006-01-01

    Adsorbed methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) were oxidized at room temperature by transient photocatalytic oxidation (PCO) on TiO2 and Pt-TiO2 catalysts; carbon dioxide, water, and acetone were the main gas-phase products. TBA oxidized faster than MTBE. Reaction products such as formic acid, which remained on the surface, were characterized by temperature-programmed desorption (TPD) and oxidation (TPO). The

  3. Sorption of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) to synthetic resins

    Microsoft Academic Search

    Erping Bi; Stefan B. Haderlein; Torsten C. Schmidt

    2005-01-01

    Methyl tert-butyl ether (MTBE) is a widely used gasoline oxygenate. Contamination of MTBE and its major degradation product tert-butyl alcohol (TBA) in groundwater and surface water has received great attention. However, sorption affinity and sorption mechanisms of MTBE and TBA to synthetic resins, which can be potentially used in removal of these contaminants from water, in passive sampling, or in

  4. Methyl tert-butyl ether (MTBE) bioremediation studies

    Microsoft Academic Search

    E. ZANARDINI; C. PISONI; G. RANALLI; M. ZUCCHI; C. SORLINI

    The massive production of methyl tert-butyl ether (MTBE), a primary con- stituent of reformulated gasoline, combined with its mobility, persistence and toxicity, makes it an important pollutant. It was considered recalcitrant until a few years ago, but recently MTBE biodegradation in aerobic conditions has been demonstrated with both mixed and pure cultures. Mixed cultures are generally the more effective for

  5. Analysis of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) in ground and surface water

    Microsoft Academic Search

    Torsten C. Schmidt

    2003-01-01

    The fuel oxygenate methyl tert-butyl ether (MTBE) is one of the most frequently detected volatile organic compounds in groundwater and, thus, has become a priority groundwater pollutant over the last decade. Methods for the quantitative determination and for compound-specific isotope analysis (CSIA) of MTBE and its key degradation intermediate, tert-butyl alcohol (TBA), in ground and surface water are reviewed. These

  6. Cometabolism of methyl tert-butyl ether (MTBE) with alkanes

    Microsoft Academic Search

    Verónica Nava; Marcia Morales; Sergio Revah

    2007-01-01

    The release of methyl tert-butyl ether (MTBE) to the environment, mainly from damaged gasoline underground storage tanks or\\u000a distribution systems spills, has provoked extended groundwater pollution. Biological treatments are, in general, a good alternative\\u000a for bioremediation of polluted sites; however, MTBE elimination from environment has constituted a challenge because of its\\u000a chemical structure and physicochemical properties. The combination of a

  7. Microbial degradation of methyl tert-butyl ether and tert-butyl alcohol in the subsurface

    NASA Astrophysics Data System (ADS)

    Schmidt, Torsten C.; Schirmer, Mario; Weiß, Holger; Haderlein, Stefan B.

    2004-06-01

    The fate of fuel oxygenates such as methyl tert-butyl ether (MTBE) in the subsurface is governed by their degradability under various redox conditions. The key intermediate in degradation of MTBE and ethyl tert-butyl ether (ETBE) is tert-butyl alcohol (TBA) which was often found as accumulating intermediate or dead-end product in lab studies using microcosms or isolated cell suspensions. This review discusses in detail the thermodynamics of the degradation processes utilizing various terminal electron acceptors, and the aerobic degradation pathways of MTBE and TBA. It summarizes the present knowledge on MTBE and TBA degradation gained from either microcosm or pure culture studies and emphasizes the potential of compound-specific isotope analysis (CSIA) for identification and quantification of degradation processes of slowly biodegradable pollutants such as MTBE and TBA. Microcosm studies demonstrated that MTBE and TBA may be biodegradable under oxic and nearly all anoxic conditions, although results of various studies are often contradictory, which suggests that site-specific conditions are important parameters. So far, TBA degradation has not been shown under methanogenic conditions and it is currently widely accepted that TBA is a recalcitrant dead-end product of MTBE under these conditions. Reliable in situ degradation rates for MTBE and TBA under various geochemical conditions are not yet available. Furthermore, degradation pathways under anoxic conditions have not yet been elucidated. All pure cultures capable of MTBE or TBA degradation isolated so far use oxygen as terminal electron acceptor. In general, compared with hydrocarbons present in gasoline, fuel oxygenates biodegrade much slower, if at all. The presence of MTBE and related compounds in groundwater therefore frequently limits the use of in situ biodegradation as remediation option at gasoline-contaminated sites. Though degradation of MTBE and TBA in field studies has been reported under oxic conditions, there is hardly any evidence of substantial degradation in the absence of oxygen. The increasing availability of field data from CSIA will foster our understanding and may even allow the quantification of degradation of these recalcitrant compounds. Such information will help to elucidate the crucial factors of site-specific biogeochemical conditions that govern the capability of intrinsic oxygenate degradation.

  8. Biodegradation of Methyl tertButyl Ether and Other Fuel Oxygenates by a New Strain, Mycobacterium austroafricanum IFP 2012

    Microsoft Academic Search

    A. Francois; Hugues Mathis; Davy Godefroy; Pascal Piveteau; Françoise Fayolle; Frédéric Monot

    2002-01-01

    A strain that efficiently degraded methyl tert-butyl ether (MTBE) was obtained by initial selection on the recalcitrant compound tert-butyl alcohol (TBA). This strain, a gram-positive methylotrophic bacterium iden- tified as Mycobacterium austroafricanum IFP 2012, was also able to degrade tert-amyl methyl ether and tert-amyl alcohol. Ethyl tert-butyl ether was weakly degraded. tert-Butyl formate and 2-hydroxy isobutyrate (HIBA), two intermediates in

  9. Effect of water presence on methyl tert-butyl ether and ethyl tert-butyl ether liquid-phase syntheses

    SciTech Connect

    Cunill, F.; Vila, M.; Izquierdo, J.F.; Iborra, M.; Tejero, J. (Univ. of Barcelona (Spain))

    1993-03-01

    Equilibrium constants for the liquid-phase synthesis of methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) were determined experimentally in the temperature range 40-80 C, using an initial water percentage range in the alcohol of 1.4-5 wt%. The initial molar alcohol-isobutylene ratio varied from 0.8 to 1.44. Both systems behave nonideally, and the equilibrium constants found agree with those determined without initial water quoted in the literature. In experimental kinetic runs performed at 40 C, ETBE and MTBE production rates are strongly lowered by the initial water presence. This inhibitor effect disappears as water is converted into tert-butyl alcohol (TBA). The TBA equilibrium is reached faster than those of the ethers, and the residual water is rather small.

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

    PubMed

    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. PMID:23240186

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

    Microsoft Academic Search

    Nicolas Lopes Ferreira; Cédric Malandain; Françoise Fayolle-Guichard

    2006-01-01

    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

  12. REDUCTIVE ACTIVATION OF DIOXYGEN FOR DEGRADATION OF METHYL TERT-BUTYL ETHER BY BIFUNCTION

    EPA Science Inventory

    Bifunctional aluminum is prepared by sulfating aluminum metal with sulfuric acid. The use of bifunctional aluminum to degrade methyl tert-butyl ether (MTBE) in the presence of dioxygen has been examined using batch systems. Primary degradation products were tert-butyl alcohol, ...

  13. INFLUENCE OF METHYL TERT-BUTYL ETHER (MTBE) ON LAKE WATER ALGAE: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-ADA-01209 Kampbell*, D.H., An, Y, and Williams, VR. Influence of Methyl tert-Butyl Ether (MTBE) on Lake Water Algae. Bulletin of Environmental Contamination and Toxicology 57 (4):675-681 (2001). ...

  14. A review of literature for methyl tert-butyl ether (MTBE) in...

    Science.gov Websites

    Documentation Other Resources Descriptions of US Geological Survey Report Series Contact Search: thumbnail A review of literature for methyl tert-butyl ether (MTBE) in sources of...

  15. Enzymatic resolution of Z- ?, ??-di- tert-butyl-D,L-carboxyglutamic acid methyl ester

    Microsoft Academic Search

    Pere Clapés; Isabel Valverde; Carles Jaime; Josep Lluís Torres

    1996-01-01

    A rapid and simple method for the resolution of Z-?,??-di-tert-butyl-D,L-carboxyglutamic acid methyl ester is described. The new procedure is based on the enzymatic enantioselective saponification of the methyl ester by the endoprotease papain. Using a simple HPLC protocol the enantiomeric excess of Z-di-tert-butyl-L-Gla-OH has been shown to be higher than 99.5%. The procedures described in this communication allow the resolution,

  16. Selection and identification of bacterial strains with methyl-tert-butyl ether, ethyl-tert-butyl ether, and tert-amyl methyl ether degrading capacities.

    PubMed

    Purswani, Jessica; Pozo, Clementina; Rodríguez-Díaz, Marina; González-López, Jesús

    2008-11-01

    Nine bacterial strains isolated from two hydrocarbon-contaminated soils were selected because of their capacity for growth in culture media amended with 200 mg/L of one of the following gasoline oxygenates: Methyl-tert-butyl ether (MTBE), ethyl-tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). These strains were identified by amplification of their 16S rRNA gene, using fDl and rD1 primers, and were tested for their capacity to grow and biotransform these oxygenates in both mineral and cometabolic media. The isolates were classified as Bacillus simplex, Bacillus drentensis, Arthrobacter sp., Acinetobacter calcoaceticus, Acinetobacter sp., Gordonia amicalis (two strains), Nocardioides sp., and Rhodococcus ruber. Arthrobacter sp. (strain MG) and A. calcoaceticus (strain M10) consumed 100 (cometabolic medium) and 82 mg/L (mineral medium) of oxygenate TAME in 21 d, respectively, under aerobic conditions. Rhodococcus ruber (strain E10) was observed to use MTBE and ETBE as the sole carbon and energy source, whereas G. amicalis (strain T3) used TAME as the sole carbon and energy source for growth. All the bacterial strains transformed oxygenates better in the presence of an alternative carbon source (ethanol) with the exception of A. calcoaceticus (strain M10). The capacity of the selected strains to remove MTBE, ETBE, and TAME looks promising for application in bioremediation technologies. PMID:18522454

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

    Microsoft Academic Search

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

    2011-01-01

    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

  18. Method for determination of methyl tert-butyl ether and its degradation products in water

    USGS Publications Warehouse

    Church, C.D.; Isabelle, L.M.; Pankow, J.F.; Rose, D.L.; Tratnyek, P.G.

    1997-01-01

    An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.An analytical method is described that can detect the major alkyl ether compounds that are used as gasoline oxygenates (methyl tert-butyl ether, MTBE; ethyl tert-butyl ether, ETBE; and tert-amyl methyl ether, TAME) and their most characteristic degradation products (tert-butyl alcohol, TBA; tert-butyl formate, TBF; and tert-amyl alcohol, TAA) in water at sub-ppb concentrations. The new method involves gas chromatography (GC) with direct aqueous injection (DAI) onto a polar column via a splitless injector, coupled with detection by mass spectrometry (MS). DAI-GC/MS gives excellent agreement with conventional purge-and-trap methods for MTBE over a wide range of environmentally relevant concentrations. The new method can also give simultaneous identification of polar compounds that might occur as degradation products of gasoline oxygenates, such as TBA, TBF, TAA, methyl acetate, and acetone. When the method was applied to effluent from a column microcosm prepared with core material from an urban site in New Jersey, conversion of MTBE to TBA was observed after a lag period of 35 days. However, to date, analyses of water samples from six field sites using the DAI-GC/MS method have not produced evidence for the expected products of in situ degradation of MTBE.

  19. Effect of Benzene, Toluene, Ethylbenzene, and p Xylene (BTEX) Mixture on Biodegradation of Methyl tert Butyl Ether (MTBE) and tert Butyl Alcohol (TBA) by Pure Culture UC1

    Microsoft Academic Search

    Amy Pruden; Makram Suidan

    2004-01-01

    The effect of a BTEX mixture on the biodegradation of methyl tert-butyl ether (MTBE) and its degradation intermediate, tert-butyl alcohol (TBA) was investigated in the pure bacterial culture UC1, which has been identified to be a strain of the known MTBE-degrader PM1 based on greater than 99% 16S rDNA similarity. Several degradation studies were carried out on UC1 at three

  20. Accurate Computer Simulation of Phase Equilibrium for Complex Fluid Mixtures. Application to Binaries Involving Isobutene, Methanol, Methyl tert-Butyl Ether, and

    E-print Network

    Lisal, Martin

    to Binaries Involving Isobutene, Methanol, Methyl tert-Butyl Ether, and n-Butane Martin Li´sal,*,, William R + methyl tert-butyl ether (MTBE) and the binaries formed by methanol with isobutene, MTBE, and n

  1. 13 C NMR Study of the Acid-Catalyzed Carbonylation of Methyl tert Butyl Ether (MTBE)

    Microsoft Academic Search

    Ned C. Haubein; Linda J. Broadbelt; Edmund J. Mozeleski; Richard H. Schlosberg; Raymond A. Cook; Christian P. Mehnert; Dan F?rca?iu

    2002-01-01

    Methyl tert-butyl ether (MTBE) is a widely used additive in oxygenated gasoline that has recently been identified as a potential health threat to the drinking water supply due to leaking underground storage tanks. One alternate use for MTBE is the production of methyl 2,2-dimethylpropanoate (methyl pivalate) via Koch carbonylation chemistry. BF3\\/H2O catalysts are employed in industrial applications of Koch chemistry,

  2. Rapid Biodegradation of Methyl tertButyl Ether (MTBE) by Pure Bacterial Cultures

    Microsoft Academic Search

    Rahele Arabi; Shahnaz Bemanian

    Two pure bacterial strains capable of rapid degrading methyl tert-butyl ether (MTBE) were isolated from an industrial wastewater treatment plant, identified and characterized. These strains are able to grow on MTBE as the sole carbon and energy sources and completely mineralize it to the biomass and carbon dioxide. The strains were identified as Bacillus cereus and Klebsiella terrigena. Both strains

  3. Treatment of Methyl tert-Butyl Ether Contaminated Water Using a Dense

    E-print Network

    Dandy, David

    Treatment of Methyl tert-Butyl Ether Contaminated Water Using a Dense Medium Plasma Reactor 53706 Plasma treatment of contaminated water appears to be a promising alternative for the oxidation. The oxidation products from the treatment of MTBE-contaminated water in the DMP reactor were found

  4. PHOTOCATALYTIC OXIDATION OF METHYL-TERT-BUTYL ETHER FOR DRINKING WATER TREATMENT

    EPA Science Inventory

    The photo-oxidation of methyl tert-butyl ether (MTBE) in water was investigated to determine the feasibility of using photocatalysis for the treatment of MTBE-contaminated drinking water. The feasibility assessment was conducted using slurries of titanium dioxide in both a photo-...

  5. INHALATION EXPOSURE TO METHYL TERT-BUTYL ETHER (MTBE) AND DIBROMOCHLOROMETHANE (DBCM) USING CONTINUOUS BREATH ANALYSIS

    EPA Science Inventory

    The oxygenate methyl tert -butyl ether (MTBE) has been added to gasoline to help meet national ambient air quality standards in those parts of the U.S. that are non-compliant for carbon monoxide. Although MTBE has provided important health benefits in terms of reduced haza...

  6. INFLUENCE OF METHYL TERT-BUTYL ETHER (MTBE) ON LAKE WATER ALGAE

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) has been used as an octane booster in gasoline in the United States since the 1970s. MTBE use increased greatly in the 1990s with the implementation of the Clean Air Act Amendments of 1990. The MTBE enhanced a more complete combustion of fuel hydroc...

  7. BIODEGRADATION OF METHYL TERT-BUTYL ETHER AND BTEX AT VARYING HYDRAULIC RETENTION TIMES

    EPA Science Inventory

    The feasibility of biologically degrading methyl tert-butyl ether (MTBE) contaminated groundwater is dependent on the ability to degrade MTBE and its byproducts in the presence of other gasoline contaminants. This study investigates a mixed culture degrading both MTBE and benzene...

  8. BIODEGRADATION OF METHYL TERT-BUTYL ETHER USING AN INNOVATIVE BIOMASS CONCENTRATOR REACTOR

    EPA Science Inventory

    The aerobic biodegradation of methyl tert-butyl ether (MTBE) was investigated using a pilot-scale Biomass Concentrator Reactor (BCR). The reactor was operated for a year at a flow rate of 2500 L/d of Cincinnati dechlorinated tap water and an influent MTBE concentration o...

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

    PubMed

    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. PMID:24053017

  10. Exposure to methyl tert-butyl ether and benzene among service station attendants and operators

    Microsoft Academic Search

    Hartle

    1993-01-01

    Concerns for atmospheric pollution from auto exhaust have led to the blending of {open_quotes}oxygenates{close_quotes} with motor fuels. The most common oxygenate, methyl tert-butyl ether (MTBE) is currently required within several metropolitan areas (Denver and Phoenix) in the range of 12% of the motor fuel. Amendments to the Clean Air Act may expand this requirement to as many as 44 other

  11. Biodegradation of methyl tert-butyl ether by a bacterial pure culture

    Microsoft Academic Search

    JESSICA R. HANSON; CORINNE E. ACKERMAN; KATE M. SCOW

    1999-01-01

    A bacterial strain, PM1, which is able to utilize methyl tert-butyl ether (MTBE) as its sole carbon and energy source, was isolated from a mixed microbial consortium in a compost biofilter capable of degrading MTBE. Initial linear rates of MTBE degradation by 2 x 10⁶ cells ml⁻¹ were 0.07, 1.17, and 3.56 μg ml⁻¹ h⁻¹ for initial concentrations of 5,

  12. Review of the environmental behavior and fate of methyl tert-butyl ether

    Microsoft Academic Search

    Paul J. Squillace; J. S. Zogorski; J. F. Pankow; N. E. Korte

    1997-01-01

    A review of pertinent equations and current research indicates that when gasoline oxygenated with methyl tert-butyl ether (MTBE) comes into contact with water, large amounts of MTBe can dissolve. At 25 C, the water solubility of MTBE is about 5,000 mg\\/L for a gasoline that is 10% MTBE by weight, whereas for a nonoxygenated gasoline, the total hydrocarbon solubility in

  13. Aerobic biodegradation of methyl tert -butyl ether (MTBE) by pure bacterialcultures isolated from contaminated soil

    Microsoft Academic Search

    L. N. Muñoz-Castellanos; J. V. Torres-Muñoz; A. Keer-Rendón; L. I. Manzanares-Papayanopoulos; G. V. Nevárez-Moorillón

    2006-01-01

    Summary  Methyl tert-Butyl Ether (MTBE) has been used in gasoline as a substitute for lead-based additives, which have been demonstrated to be toxic. MTBE however, is persistent in soil and water, showing high affinity for water and low affinity for soil, and has become an important contaminant. Therefore, the aim of this work was to isolate and identify soil microorganisms capable

  14. Biodegradation of methyl tert-butyl ether by Methylibium petroleiphilum PM1 in poor nutrition solution

    Microsoft Academic Search

    Jianmeng Chen; Dongzhi Chen; Weihong Zhong; Jingxiao Zhang; Xiao Chen

    2007-01-01

    In this study, degradation of methyl tert-butyl ether (MTBE) by resting cells of Methylibium petroleiphilum PM1 was performed in poor nutrition solution, major component of which was MTBE. It was found that the biomass was hard to increase in poor nutrition, and the MTBE degradation activity was enhanced by 4.65-fold when 1 mM of Ba was added into deionized water.

  15. Biodegradation of Methyl Tert -butyl Ether in a Bioreactor using Immobilized Methylibium petroleiphilum PM1 Cells

    Microsoft Academic Search

    Zhuo-Wei Cheng; Jian-Meng Chen; Dong-Zhi Chen; Li-Li Zhang

    2011-01-01

    Methylibium petroleiphilum PM1, which is capable of degrading of methyl tert-butyl ether (MTBE), was immobilized in calcium alginate gel beads. Various applications were explored to increase the mechanical\\u000a strength of these gel beads. The introduction of 0.3 mol\\/L calcium chloride into the crosslinking solution, 0.002 mol\\/L calcium\\u000a chloride into the growth medium, and 0.2% polyethyleneimine (PEI) as chemical crosslinking agent increased the

  16. Determination of Methyl tertButyl Ether and tertButyl Alcohol in Water by SolidPhase Microextraction\\/Head Space Analysis in Comparison to EPA Method 5030\\/8260B

    Microsoft Academic Search

    Keun-Chan Oh; William T. Stringfellow

    2003-01-01

    Methyl tert-butyl ether (MTBE) is now one of the most common groundwater contaminants in the United States. Groundwater contaminated with MTBE is also likely to be contaminated with tert-butyl alcohol (TBA), because TBA is a component of commercial grade MTBE, TBA can also be used as a fuel oxygenate, and TBA is a biodegradation product of MTBE. In California, MTBE

  17. Biodegradation of methyl tert-butyl ether by cometabolism with hexane in biofilters inoculated with Pseudomonas aeruginosa

    Microsoft Academic Search

    Margarita Salazar; Marcia Morales; Sergio Revah

    2012-01-01

    Biodegradation of methyl tert-butyl ether (MTBE) vapors by cometabolism with gaseous hexane (n-hexane > 95%) was investigated using Pseudomonas aeruginosa utilizing short chain aliphatic hydrocarbon (C5-C8). Kinetic batch experiments showed that MTBE was degraded even when hexane was completely exhausted with a cometabolic coefficient of 1.06 ± 0.16 mg MTBE mg hexane. Intermediate tert-butyl alcohol (TBA) accumulation was observed followed

  18. Kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE)

    Microsoft Academic Search

    Kun-Chang Huang; Richard A Couttenye; George E Hoag

    2002-01-01

    The kinetics of heat-assisted persulfate oxidation of methyl tert-butyl ether (MTBE) in aqueous solutions at various pH, temperature, oxidant concentration and ionic strength levels was studied. The MTBE degradation was found to follow a pseudo-first-order decay model. The pseudo-first-order rate constants of MTBE degradation by persulfate (31.5 mM) at pH 7.0 and ionic strength 0.11 M are ?0.13×10?4, 0.48×10?4, 2.4×10?4

  19. Review of the environmental behavior and fate of methyl tert-butyl ether

    SciTech Connect

    Squillace, P.J.; Zogorski, J.S. [Geological Survey, Rapid City, SD (United States); Pankow, J.F. [Oregon Graduate Inst. of Science and Technology, Beaverton, OR (United States). Dept. of Environmental Science and Engineering; Korte, N.E. [Oak Ridge National Lab., TN (United States). Environmental Science Div.

    1997-09-01

    A review of pertinent equations and current research indicates that when gasoline oxygenated with methyl tert-butyl ether (MTBE) comes into contact with water, large amounts of MTBe can dissolve. At 25 C, the water solubility of MTBE is about 5,000 mg/L for a gasoline that is 10% MTBE by weight, whereas for a nonoxygenated gasoline, the total hydrocarbon solubility in water is typically about 120 mg/L. Methyl tert-butyl ether sorbs only weakly to subsurface solids; therefore, sorption does not substantially retard the transport of MTBE by ground water. In addition, MTBE generally resists biodegradation in ground water. The half-life of MTBE in the atmosphere can be as short as 3 d in a regional airshed. In the air, MTBE tends to partition into atmospheric water, including precipitation. However, the washing out of gas-phase MTBE by precipitation will not, by itself, greatly alter the gas-phase concentration of the compound in the air. The partitioning of MTBE to precipitation can nevertheless result in concentrations as high as 3 {micro}g/L or more in urban precipitation and can contribute to the presence of MTBE in surface and ground water.

  20. Decreased toxicity to terrestrial plants associated with a mixture of methyl tert-butyl ether and its metabolite tert-butyl alcohol.

    PubMed

    An, Youn-Joo; Lee, Woo-Mi

    2007-08-01

    The influence of the main fuel oxygenate methyl tert-butyl ether (MTBE) and its key metabolite, tert-butyl alcohol (TBA), on the growth of a plant seedling was studied separately and in combination. The test plants were mung bean (Phaseolus radiatus), cucumber (Cucumis sativus), wheat (Triticum aestivum), sorghum (Sorghum bicolor), kale (Brassica alboglabra), Chinese cabbage (Brassica campestris), and sweet corn (Zea mays). The growth of all the plants was adversely affected by TBA and MTBE. The 5-d median effective concentration (EC50) for the plants exposed to MTBE and TBA were in the range of 680 to 1,000 mg MTBE/kg soil (dry wt) and 1,200 to 3,500 mg TBA/kg soil (dry wt), respectively. The relative order of the sensitivity rankings is almost the same for MTBE and TBA. Methyl tert-butyl ether is more toxic than TBA to most of the test species. Based on the EC50 values, MTBE is approximately 1.5 to 3 times more potent than TBA. The sum of the toxic unit (TU) at 50% inhibition of the mixture (EC50mix) was calculated from the dose (TU-based)-response relationships using the trimmed Spearman-Karber method. The combined effect of MTBE + TBA on the plant growth was less than additive because the EC50mix values were greater than I TU. This phenomenon may be due to the competition of MTBE and TBA in terms of their intake by plants. The combined effects of MTBE and TBA should be taken into account to assess their risk in gasoline-contaminated sites. PMID:17702346

  1. Simultaneous determination of methyl tert.-butyl ether and its degradation products, other gasoline oxygenates and benzene, toluene, ethylbenzene and xylenes in Catalonian groundwater by purge-and-trap-gas chromatography–mass spectrometry

    Microsoft Academic Search

    Mònica Rosell; S??lvia Lacorte; Antoni Ginebreda; Damià Barceló

    2003-01-01

    In Catalonia (northeast Spain), a monitoring program was carried out to determine methyl tert.-butyl ether (MTBE), its main degradation products, tert.-butyl alcohol (TBA), tert.-butyl formate (TBF), and other gasoline additives, the oxygenate dialkyl ethers ethyl tert.-butyl ether, tert.-amyl methyl ether and diisopropyl ether and the aromatic compounds benzene, toluene, ethylbenzene and xylene (BTEX) in 21 groundwater wells that were located

  2. Characterization of the Initial Reactions during the Cometabolic Oxidation of Methyl tertButyl Ether by Propane-Grown Mycobacterium vaccae JOB5

    Microsoft Academic Search

    Christy A. Smith; Kirk T. O'Reilly; Michael R. Hyman

    2003-01-01

    The initial reactions in the cometabolic oxidation of the gasoline oxygenate, methyl tert-butyl ether (MTBE), by Mycobacterium vaccae JOB5 have been characterized. Two products, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), rapidly accumulated extracellularly when propane-grown cells were incubated with MTBE. Lower rates of TBF and TBA production from MTBE were also observed with cells grown on 1- or 2-propanol,

  3. Biodegradation of methyl tert-butyl ether by Methylibium petroleiphilum PM1 in poor nutrition solution.

    PubMed

    Chen, Jianmeng; Chen, Dongzhi; Zhong, Weihong; Zhang, Jingxiao; Chen, Xiao

    2007-12-01

    In this study, degradation of methyl tert-butyl ether (MTBE) by resting cells of Methylibium petroleiphilum PM1 was performed in poor nutrition solution, major component of which was MTBE. It was found that the biomass was hard to increase in poor nutrition, and the MTBE degradation activity was enhanced by 4.65-fold when 1 mM of Ba(2+) was added into deionized water. It was also found that the MTBE degradation could be significantly improved by the dissolved oxygen level. All of 50 mg L(-1) MTBE could be degraded under aerobic condition, while only 5% was degraded under anaerobic condition by resting cells in poor nutrition solution after 12 h. In the above solution, the degradation of tert-butyl alcohol (TBA) was found to be faster than that of MTBE, which suggested that TBA degradation might not be the limiting step in MTBE metabolism. While in the poor nutrition solution with the mixture of MTBE and TBA, the addition of TBA did not affect MTBE degradation while MTBE inhibited TBA degradation weakly, which suggested that different and independent enzymes were responsible for degrading such compounds. The success of MTBE degradation by PM1 cells in real contaminated groundwater demonstrated its feasibility to biodegrade MTBE under poor environment, and it also indicated the great potential of MTBE bioremediation by entrapped cells in future application. PMID:18074284

  4. DERMAL EXPOSURE TO METHYL TERT-BUTYL ETHER (MTBE) AND DIBROMOCHLOROMETHANE (DBCM) WHILE BATHING WITH CONTAMINATED WATER

    EPA Science Inventory

    The oxygenate methyl tert-butyl ether (MTBE) has been added to gasoline to help meet national ambient air quality standards in those parts of the U.S. that are non-compliant for carbon monoxide. Although MTBE has provided important health benefits in terms of reduced hazardous a...

  5. Enhanced bioremediation of methyl tert-butyl ether (MTBE) by microbial consortia obtained from contaminated aquifer material

    Microsoft Academic Search

    Angela Volpe; Guido Del Moro; Simona Rossetti; Valter Tandoi; Antonio Lopez

    2009-01-01

    A microcosm study was carried out to evaluate the potential for biodegradation of methyl tert-butyl ether (MTBE) impacting groundwater at a former oil refinery site located in Naples (SW Italy). A screening of aerobic, anaerobic and co-metabolic aerobic conditions was carried out by triplicate batch reactors, using contaminated soil and groundwater from the study site. All microcosms were amended with

  6. CO-OCCURRENCE OF METHYL- TERT-BUTYL ETHER (MTBE) AND BTEX COMPOUNDS AT MARINAS IN A LARGE RESEVOIR

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) is released into the environment as one of some gasoline components, not as a pure compound. BTEX compounds (benzene, tolune, ethylbenzene, and xylenes) are major volatile constituents found in gasoline and are water soluble and mobile. This study...

  7. Anaerobic Biodegradation Of Methyl tert -Butyl Ether Under Iron-Reducing Conditions In Batch And Continuous-Flow Cultures

    EPA Science Inventory

    The feasibility of biodegradation of the fuel oxygenate methyl tert -butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing...

  8. INTERACTION OF METHYL-TERT BUTYL ETHER AND WATER STRESS ON SEED GERMINATION AND SEEDLING GROWTH IN SOIL MICROCOSMS

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) is a widespread contaminant in surface and ground water in the United States. Frequently irrigation is used to water fields to germinate planted seeds and sustain plant growth. A likely possibility exists that water used may have some MTBE. Our s...

  9. EVALUATION OF METHYL TERT-BUTYL ETHER (MTBE) AS AN INTERFERENCE ON COMMERCIAL BREATH-ALCOHOL ANALYZERS

    EPA Science Inventory

    Anecdotal reports suggest that high environmental or occupational exposures to the fuel oxygenate methyl tert-butyl ether (MTBE) may result in breath concentrations that are sufficiently elevated to cause a false positive on commercial breath-alcohol analyzers. We evaluated th...

  10. Combined toxicities of methyl tert-butyl ether and its metabolite tert-butyl alcohol on earthworms via different exposure routes.

    PubMed

    Lee, Woo-Mi; Yoon, Youngdae; An, Youn-Joo

    2015-06-01

    Methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) are among the major soil contaminants that threaten the health of soil ecosystems. Many MTBE-contaminated sites accumulate TBA, because TBA is the intermediate of MTBE biodegradation. To access the risk of MTBE and TBA in soil, we investigated the combined toxicities of MTBE and TBA using two earthworm species, Perionyx excavatus and Eisenia andrei, as well as the toxic effects via different exposure routes. The combined toxicity showed weak antagonistic effects (LC50mix values were slightly greater than 1.0), and sensitivity toward same pollutants differed in the two earthworm species. Moreover, the toxicity of MTBE and TBA was also affected by the exposure route; both filter paper and artificial soil tests showed that dermal-only exposure to MTBE had an even greater toxic effect than combined dermal and oral exposure. Thus, we suggest that diverse environmental factors including organic materials, the physicochemical properties of the contact media, and the exposure routes of the organism, should be taken into consideration when assessing the effects of pollutants on organisms in diverse environmental systems. PMID:25706436

  11. Uptake, metabolism, and toxicity of methyl tert-butyl ether (MTBE) in weeping willows.

    PubMed

    Yu, Xiao-Zhang; Gu, Ji-Dong

    2006-10-11

    Methyl tert-butyl ether (MTBE) is a high volume production chemical and the most commonly used gasoline oxygenate. Uptake, metabolism and toxicity of MTBE in trees were investigated in this study. Pre-rooted weeping willows (Salix babylonica L.) were exposed to hydroponic solution spiked with MTBE and incubated at 25.0+/-1 degrees C for 168 h. The normalized relative transpiration (NRT) rate of weeping willows was used to determine toxicity. MTBE and possible intermediate tert-butyl alcohol (TBA) in solution, tissues of aerial parts of plants, and air were analyzed. Results from the toxicity test showed that severe signs of toxicity (the reduction of the NRT >or=35%) were only found at the treatment group with high doses of MTBE 400 mg L(-1). Neither chlorosis of leaves nor large reduction in the NRT was observed at MTBE exposure to weeping willows

  12. Synthesis and cytotoxic properties of derivatives of the tert -butyl ester of 7-alkylidene-3-methyl-3-cepheme-4-carboxylic acid

    Microsoft Academic Search

    M. Vorona; I. Potorocina; G. Veinberg; I. Shestakova; I. Kanepe; E. Lukevics

    2008-01-01

    Sulfones of the tert-butyl esters of 7-arylmethylene-and 7-(2-furyl)methylene-3-methyl-3-cepheme-4-carboxylic acid were obtained\\u000a by the condensation of the tert-butyl ester of 3-methyl-7-oxo-3-cepheme-4-carboxylic acid with arylmethylene-and 2-furylidenetriphenylphosphoranes\\u000a and subsequent oxidation of the intermediate products by meta-chloroperbenzoic acid. The combination of the tert-butyl esters\\u000a of 7E-bromomethylene-and 7,7-dibromomethylene-3-methyl-1,1-dioxo-3-cepheme-4-carboxylic acids with trimethylsilylacetylene\\u000a under conditions of the Sonogashira reaction gave the tert-butyl esters of 3-methyl-1,1-dioxo-7E-(3-trimethylsilyl-2-propynylidene)-3-cepheme-4-carboxylic\\u000a acid and

  13. CONCENTRATIONS, SOURCES, AND FATE OF THE GASOLINE OXYGENATE METHYL TERT-BUTYL ETHER (MTBE) IN A MULTIPLE-USE LAKE. (R826282)

    EPA Science Inventory

    Discovery of the fuel additive methyl tert -butyl ether (MTBE) in drinking water supplies is of concern to public health officials, water suppliers, and the public. Despite recent policy decisions, few published studies exist on the concentrations, sources, a...

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

    PubMed

    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. PMID:24246442

  15. Dissolution of Gallbladder Stones with Methyl tertButyl Ether and Stone Recurrence (A European Survey)

    Microsoft Academic Search

    Alfred Hellstern; Ulrich Leuschner; Ala Benjaminov; Hanns Ackermann; Thomas Heine; Davide Festi; Monica Orsini; Enrico Roda; Tim C. Northfield; Riadh Jazrawi; Winfried Kurtz; Hans Joachim Schmeck-Lindenau; Jochen Stumpf; Britt E. Eidsvoll; Erling Aadland; Gerd Lux; Eckhart Boehnke; Ditmar Wurbs; Myriam Delhaye; Michel Cremer; Ingolf Sinn; Erich Horing; Ulrich V. Gaisberg; Michael Neubrand; Tilmann Sauerbruch; Vladimir Salamon; Werner Swobodnik; Hasko V. Sanden; Wolfgang Schmitt; Thomas Kaser; Hans Schomerus; Johannes Georg Wechsler; Paul Janowitz; Jorn Lohmann; Heiner Porst; Adolfo Francesco Attili; Eberhard Bartels; Wolfgang Arnold Wolf; Dieter Strohm; Fred Paul

    1998-01-01

    Since there are now several ways to treatsymptomatic gallstone disease, one is able to selecttreatment on the basis of the patient's comfort, thepracticability, effectiveness, and side effects of the technique, and the relative costs. In order toassess the present status of contact dissolution withmethyl tert-butyl ether with regard to these aspects,the present enquiry reports the data of 21 European hospitals.

  16. Microbial toxicity of methyl tert-butyl ether (MTBE) determined with fluorescent and luminescent bioassays.

    PubMed

    Roslev, Peter; Lentz, Trine; Hesselsoe, Martin

    2015-02-01

    The inhibitory effects of the fuel additive methyl tert-butyl ether (MTBE) and potential degradation products tert-butanol (TBA) and formaldehyde was examined using mixed microbial biomass, and six strains of bioluminescent bacteria and yeast. The purpose was to assess microbial toxicity with quantitative bioluminescent and fluorescent endpoints, and to identify sensitive proxies suitable for monitoring MTBE contamination. Bioluminescent Aliivibrio fischeri DSM 7151 (formerly Vibrio fischeri) appeared highly sensitive to MTBE exposure, and was a superior test organisms compared to lux-tagged Escherichia coli DH5?, Pseudomonas fluorescens DF57-40E7 and Saccharomyces cerevisiae BLYR. EC10 and EC50 for acute MTBE toxicity in A. fischeri were 1.1 and 10.9 mg L(-1), respectively. Long term (24h) MTBE exposure resulted in EC10 values of 0.01 mg L(-1). TBA was significantly less toxic with EC10 and EC50 for acute and chronic toxicity >1000 mg L(-1). Inhibition of bioluminescence was generally a more sensitive endpoint for MTBE toxicity than measuring intracellular ATP levels and heterotrophic CO2 assimilation. A weak estrogenic response was detected for MTBE at concentrations ? 3.7 g L(-1) using an estrogen inducible bioluminescent yeast strain (S. cerevisiae BLYES). Microbial hydrolytic enzyme activity in groundwater was affected by MTBE with EC10 values of 0.5-787 mg L(-1), and EC50 values of 59-3073 for alkaline phosphatase, arylsulfatase, beta-1,4-glucanase, N-acetyl-beta-d-glucosaminidase, and leucine-aminopeptidase. Microbial alkaline phosphatase and beta-1,4-glucanase activity were most sensitive to MTBE exposure with EC50 ? 64.8 mg L(-1). The study suggests that bioassays with luminescent A. fischeri, and fluorescent assays targeting hydrolytic enzyme activity are good candidates for monitoring microbial MTBE toxicity in contaminated water. PMID:25128634

  17. Methyl tert butyl ether targets developing vasculature in zebrafish (Danio rerio) embryos

    PubMed Central

    Bonventre, Josephine A.; White, Lori A.; Cooper, Keith R.

    2015-01-01

    Disruption of vascular endothelial growth factor (VEGF) signaling during early development results in abnormal angiogenesis and increased vascular lesions. Embryonic exposure to 0.625 to 10 mM methyl tert butyl ether (MTBE), a highly water soluble gasoline additive, resulted in a dose dependent increase in pooled blood in the common cardinal vein (CCV), cranial hemorrhages and abnormal intersegmental vessels (ISVs). The EC50s for the lesions ranked in terms of likelihood to occur with MTBE exposure were: pooled blood in the CCV, 3.2 mM [95 % CI: 2.2 – 4.7] > cranial hemorrhage, 11 mM [5.9 – 20.5] > abnormal ISV, 14.5 mM [6.5 – 32.4]. Organ systems other than the vascular system appear to develop normally, which suggests MTBE toxicity targets developing blood vessels. Equal molar concentrations (0.625 to 10 mM) of the primary metabolites, tertiary butyl alcohol (TBA) and formaldehyde, did not result in vascular lesions, which suggested that the parent compound is responsible for the toxicity. Stage specific exposures were carried out to determine the developmental period most sensitive to MTBE vascular disruption. Embryos treated until 6-somites or treated after Prim-5 stages did not exhibit a significant increase in lesions, while embryos treated between 6-somites and Prim-5 had a significant increase in vascular lesions (p ? 0.05). During the critical window for MTBE-induced vascular toxicity, expression of vegfa, vegfc, and flk1/kdr were significantly decreased 50, 70 and 40%, respectively. This is the first study to characterize disruption in vascular development following embryonic exposure to MTBE. The unique specificity of MTBE to disrupt angiogenesis may be mediated by the down regulation of critical genes in the VEGF pathway. PMID:21684239

  18. Enhanced biodegradation of methyl tert-butyl-ether by a microbial consortium.

    PubMed

    Li, Shan-shan; Zhang, Di; Yan, Wei

    2014-03-01

    The widespread use of Methyl tert-butyl-ether (MTBE) as a gasoline additive has resulted in a higher detection rate of MTBE in groundwater systems. Therefore, the researchers show more concern about the bioremediation of MTBE-impacted aquifers. In this paper, a MTBE-direct-degrading bacterial consortium was enriched (named RS1) and further studied. In order to identify the microbial community of the consortium, 17 and 12 different single strains were isolated from nutrient medium and MSM media (with MTBE as the sole carbon source), respectively. 16S rDNA-based phylogenetic analysis revealed that these diverse bacteria belonged to 14 genera, in which Pseudomonas was dominant. Several strains which can grow with MTBE as the sole carbon and energy source were also identified, such as M1, related to MTBE-degrading Arthrobacter sp. ATCC27778. Furthermore, the appropriate addition of certain single strain in consortium RS1 (M1:RS1 = 1:2) facilitates MTBE degradation by increasing the quantity of efficient MTBE-degrading bacteria. This work will provide microbial source and theoretical fundament for further bioremediation of MTBE-contaminated aquifers, which has applied potential and environmental importance. PMID:24162446

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

    PubMed

    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. PMID:25697553

  20. Biodegradation of methyl tert-butyl ether by a bacterial pure culture

    SciTech Connect

    Hanson, J.R.; Ackerman, C.E.; Scow, K.M.

    1999-11-01

    A bacterial strain, PM1, which is able to utilize methyl tert-butyl ether (MTBE) as its sole carbon and energy source, was isolated from a mixed microbial consortium in a compost biofilter capable of degrading MTBE. Initial linear rates of MTBE degradation by 2 x 10{sup 6} cells ml{sup {minus}1} were 0.07, 1.17, and 3.56 {mu}g ml{sup {minus}1} h{sup {minus}1} for initial concentrations of 5, 50, and 500 {mu}g MTBE ml{sup {minus}1}, respectively. When incubated with 20 {mu}g of uniformly labeled [{sup 14}C]MTBE ml{sup {minus}1}, strain PM1 converted 46% to {sup 14}CO{sub 2} and 19% to {sup 14}C-labeled cells within 120 h. This yield is consistent with the measurement of protein accumulation at different MTBE concentrations from which was estimated a biomass yield of 0.18 of cells mg MTBE{sup {minus}1}. Strain PM1 was inoculated into sediment core material collected from a contaminated groundwater plume at Port Hueneme, California, in which there was no evidence of MTBE degradation. Strain PM1 readily degraded 20 {micro}g of MTBE ml{sup {minus}1} added to the core material. The rate of MTBE removal increased with additional inputs of 20 {micro}g of MTBE ml{sup {minus}1}. These results suggest that PM1 has potential for use in the remediation of MTBE-contaminated environments.

  1. Methyl tert-butyl ether biodegradation by indigenous aquifer microorganisms under natural and artificial oxic conditions

    USGS Publications Warehouse

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

    2001-01-01

    Microbial communities indigenous to a shallow groundwater system near Beaufort, SC, degraded milligram per liter concentrations of methyl tert-butyl ether (MTBE) under natural and artificial oxic conditions. Significant MTBE biodegradation was observed where anoxic, MTBE-contaminated groundwater discharged to a concrete-lined ditch. In the anoxic groundwater adjacent to the ditch, concentrations of MTBE were > 1 mg/L. Where groundwater discharge occurs, dissolved oxygen (DO) concentrations beneath the ditch exceeded 1.0 mg/L to a depth of 1.5 m, and MTBE concentrations decreased to <1 ??g/L prior to discharge. MTBE mass flux calculations indicate that 96% of MTBE mass loss occurs in the relatively small oxic zone prior to discharge. Samples of a natural microbial biofilm present in the oxic zone beneath the ditch completely degraded [U-14C]MTBE to [14C]CO2 in laboratory liquid culture studies, with no accumulation of intermediate compounds. Upgradient of the ditch in the anoxic, MTBE and BTEX-contaminated aquifer, addition of a soluble oxygen release compound resulted in oxic conditions and rapid MTBE biodegradation by indigenous microorganisms. In an observation well located closest to the oxygen addition area, DO concentrations increased from 0.4 to 12 mg/L in <60 days and MTBE concentrations decreased from 20 to 3 mg/L. In the same time period at a downgradient observation well, DO increased from <0.2 to 2 mg/L and MTBE concentrations decreased from 30 to <5 mg/L. These results indicate that microorganisms indigenous to the groundwater system at this site can degrade milligram per liter concentrations of MTBE under natural and artificial oxic conditions.

  2. Advanced oxidation and reduction process chemistry of methyl tert-butyl ether (MTBE) reaction intermediates in aqueous solution: 2Methoxy2-methyl-propanal, 2-methoxy-2-methyl-propanol, and 2-methoxy-2-methyl-propanoic acid

    Microsoft Academic Search

    Stephen P. Mezyk; D. Rance Hardison; Weihua Song; Kevin E. O’Shea; David M. Bartels; William J. Cooper

    2009-01-01

    Absolute rate constants for the reaction of three important degradation products of methyl-tert-butyl ether (MTBE) with the hydroxyl radical, hydrated electron and hydrogen atom were determined in aqueous solution at room temperature. These three intermediate species; 2-methoxy-2-methyl propanal (MMP), 2-methoxy-2-methyl-propanol (MMP-OH) and 2-methoxy-2-methyl-propionic acid (MMP-acid), are formed in the degradation of MTBE under advanced oxidation and reduction process conditions. The

  3. Responses of the steroidogenic pathway from exposure to methyl-tert-butyl ether and tert-butanol.

    PubMed

    de Peyster, Ann; Mihaich, Ellen; Kim, Do Hyung; Elyea, William A; Nemec, Matthew J; Hirakawa, Brad P; Leggieri, Shannon E

    2014-05-01

    Methyl tertiary-butyl ether (MTBE) is a solvent and fuel additive included in reformulated gasoline to increase combustion efficiency. While widespread use in motor fuels in the U.S. was discontinued after MTBE was detected in surface and ground waters due to concerns about environmental persistence and water quality, it is still manufactured in the U.S. for export. Questions concerning the etiology of rat Leydig cell and mouse liver tumors identified in extremely high dose cancer studies have led to an interest in evaluating potential hormonal imbalances and endocrine system involvement. To address the possibility that MTBE or its metabolite, tert-butanol (TBA), are interacting with components of the endocrine system that are involved in steroidogenesis a number of targeted experiments were performed focusing mostly on the primary gonadal steroids, estradiol and testosterone. The goal of the experiments was to gain a better understanding of potential interactions with the steroidogenic pathway, including effects specifically on aromatase, the P450 enzyme that converts testosterone to estradiol. In three GLP-compliant in vitro guideline studies, MTBE and TBA were classified as non-binders to the androgen receptor, were classified negative for effects on testosterone and estradiol in the steroidogenesis assay, and were classified as non-inhibitors of aromatase activity. In three 14-day in vivo experiments involving gavaging of male Sprague-Dawley rats with doses of MTBE ranging from 400 to 1,500 mg/kg bw/day, the lack of definitive and consistent supporting statistically significant findings in steroid hormone measurements and aromatase activity and mRNA measured in liver and testis microsomes further suggested that it is unlikely that MTBE is interacting with the endocrine system directly. Evidence of other underlying systemic effects were also seen, including reduced body weight gain, increased adrenal weights, and elevated corticosterone suggestive of a more general stress response. Taken together, the results from these studies suggest that MTBE and TBA do not directly impact the steroidogenic pathways involved in estrogen and androgen production. PMID:24560773

  4. Toxicokinetics of methyl tert-butyl ether and its metabolites in humans after oral exposure.

    PubMed

    Amberg, A; Rosner, E; Dekant, W

    2001-05-01

    Methyl tert-butyl ether (MTBE) is widely used as an additive to gasoline, to increase oxygen content and reduce tailpipe emission of pollutants. Widespread human exposure to MTBE may occur due to leakage of gasoline storage tanks and a high stability and mobility of MTBE in ground water. To compare disposition of MTBE after different routes of exposure, its biotransformation was studied in humans after oral administration in water. Human volunteers (3 males and 3 females, identical individuals, exposures were performed 4 weeks apart) were exposed to 5 and 15 mg 13C-MTBE dissolved in 100 ml of water. Urine samples from the volunteers were collected for 96 h after administration in 6-h intervals and blood samples were taken in intervals for 24 h. In urine, MTBE and the MTBE-metabolites tert-butanol (t-butanol), 2-methyl-1,2-propane diol, and 2-hydroxyisobutyrate were quantified, MTBE and t-butanol were determined in blood samples and in exhaled air in a limited study of 3 male volunteers given 15 mg MTBE in 100 ml of water. MTBE blood concentrations were 0.69 +/- 0.25 microM after 15 mg MTBE and 0.10 +/- 0.03 microM after 5 mg MTBE. MTBE was rapidly cleared from blood with terminal half-lives of 3.7 +/- 0.9 h (15 mg MTBE) and 8.1 +/- 3.0 h (5 mg MTBE). The blood concentrations of t-butanol were 1.82 +/- 0.63 microM after 15 mg MTBE and 0.45 +/- 0.13 microM after 5 mg MTBE. Approximately 30% of the MTBE dose was cleared by exhalation as unchanged MTBE and as t-butanol. MTBE exhalation was rapid and maximal MTBE concentrations (100 nmol/l) in exhaled air were achieved within 10-20 min. Clearance of MTBE by exhalation paralleled clearance of MTBE from blood. T-butanol was cleared from blood with half-lives of 8.5 +/- 2.4 h (15 mg MTBE) and 8.1 +/- 1.6 h (5 mg MTBE). In urine samples, 2-hydroxyisobutyrate was recovered as major excretory product, t-butanol and 2-methyl-1,2-propane diol were minor metabolites. Elimination half-lives for the different urinary metabolites of MTBE were between 7.7 and 17.8 h. Approximately 50% of the administered MTBE was recovered in urine of the volunteers after both exposures, another 30% was recovered in exhaled air as unchanged MTBE and t-butanol. The obtained data indicate that MTBE-biotransformation and excretion after oral exposure is similar to inhalation exposure and suggest the absence of a significant first-pass metabolism of MTBE in the liver after oral administration. PMID:11294975

  5. Crystal structure of 4-azido­methyl-6-tert-butyl-2H-chromen-2-one

    PubMed Central

    El-Khatatneh, Nasseem; Chandra; Shamala, D.; Shivashankar, K.; Panzi, Mukhokosi Emma; Mahendra, M.

    2015-01-01

    In the title compound, C14H15N3O2, one of the methyl C atoms of the tert-butyl group lies almost in the plane of the chromene ring system [deviation = ?0.097?(2)?Å], one lies above and one lies below [deviations = 1.460?(3) and 1.006?(3)?Å, respectively]. The C—C—N—N torsion angle is 142.33?(17)°. In the crystal, moelcules are linked by weak C—H?O hydrogen bonds to generate C(6) chains propagating in the [010] direction.

  6. U.S. Geological Survey laboratory method for methyl tert-Butyl ether and other fuel oxygenates

    USGS Publications Warehouse

    Raese, Jon W.; Rose, Donna L.; Sandstrom, Mark W.

    1995-01-01

    Methyl tert-butyl ether (MTBE) was found in shallow ground-water samples in a study of 8 urban and 20 agricultural areas throughout the United States in 1993 and 1994 (Squillace and others, 1995, p. 1). The compound is added to gasoline either seasonally or year round in many parts of the United States to increase the octane level and to reduce carbon monoxide and ozone levels in the air. The U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL), near Denver, uses state-of-the-art technology to analyze samples for MTBE as part of the USGS water-quality studies. In addition, the NWQL offers custom analyses to determine two other fuel oxygenates--ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME). The NWQL was not able to obtain a reference standard for tert-amyl ethyl ether (TAEE), another possible fuel oxygenate (Shelley and Fouhy, 1994, p. 63). The shallow ground-water samples were collected as part of the USGS National Water-Quality Assessment Program. These samples were collected from 211 urban wells or springs and 562 agricultural wells sampled by the USGS in 1993 and 1994. The wells were keyed to specific land-use areas to assess the effects of different uses on ground-water quality (Squillace and others, 1995, p. 2). Ground-water samples were preserved on site to pH less than or equal to 2 with a solution of 1:1 hydrochloric acid. All samples were analyzed at the NWQL within 2 weeks after collection. The purpose of this fact sheet is to explain briefly the analytical method implemented by the USGS for determining MTBE and other fuel oxygenates. The scope is necessarily limited to an overview of the analytical method (instrumentation, sample preparation, calibration and quantitation, identification, and preservation of samples) and method performance (reagent blanks, accuracy, and precision).

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

    USGS Publications Warehouse

    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 were detected in ground water indicate that recharge from precipation containing MTBE is not a likely explanation for the occurrence of MTBE in the Windham aquifer.

  8. Role of cytochromes P450 in the metabolism of methyl tert-butyl ether in human livers.

    PubMed

    Hong, J Y; Yang, C S; Lee, M; Wang, Y Y; Huang, W Q; Tan, Y; Patten, C J; Bondoc, F Y

    1997-01-01

    Methyl tert-butyl ether (MTBE) is widely used as a gasoline oxygenate for more complete combustion in order to reduce the air pollution caused by motor vehicle exhaust. The possible adverse effects of MTBE on human health is a major public concern. However, information on the metabolism of MTBE in human tissues is lacking. The present study demonstrates that human liver is active in metabolizing MTBE to tert-butyl alcohol (TBA), a major circulating metabolite and a marker for exposure to MTBE. The activity is localized in the microsomal fraction (125 +/- 11 pmol TBA/ min per mg protein, n = 8) but not in the cytosol. This activity level in human liver microsomes is approximately one-half of the value in rat and mouse liver microsomes. Formation of TBA in human liver microsomes is NADPH-dependent, and is significantly inhibited by carbon monoxide (CO), an inhibitor of cytochrome P450 (CYP) enzymes, suggesting that CYP enzymes play a critical role in the metabolism of MTBE in human livers. Both CYP2A6 and 2E1 are known to be constitutively expressed in human livers. To examine their involvement in MTBE metabolism, human CYP2A6 and 2E1 cDNAs were individually co-expressed with human cytochrome P450 reductase by a baculovirus expression system and the expressed enzymes were used for MTBE metabolism. The turnover number for CYP2A6 and 2E1 was 6.1 and 0.7 nmol TBA/min per nmol P450, respectively. The heterologously expressed human CYP2A6 was also more active than 2E1 in the metabolism of two other gasoline ethers, ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME). Although the contributions of other human CYP forms to MTBE metabolism remain to be determined, these results strongly suggest that CYP enzymes play an important role in the metabolism of MTBE in human livers. PMID:9101044

  9. Biodegradation of methyl tert-butyl ether by cometabolism with hexane in biofilters inoculated with Pseudomonas aeruginosa.

    PubMed

    Salazar, Margarita; Morales, Marcia; Revah, Sergio

    2012-01-01

    Biodegradation of methyl tert-butyl ether (MTBE) vapors by cometabolism with gaseous hexane (n-hexane > 95%) was investigated using Pseudomonas aeruginosa utilizing short chain aliphatic hydrocarbon (C(5)-C(8)). Kinetic batch experiments showed that MTBE was degraded even when hexane was completely exhausted with a cometabolic coefficient of 1.06 ± 0.16 mg MTBE mg hexane(-1). Intermediate tert-butyl alcohol (TBA) accumulation was observed followed by its gradual consumption. A maximum MTBE elimination capacity (EC(MAX)) of 35 g m(-3) h(-1) and removal efficiency (RE) of 70% were attained in mineral medium amended biofilters having an empty bed residence time (EBRT) of 1 min. For these experimental conditions, a maximum hexane EC of approximately 60 g m(-3) h(-1) was obtained at a load of 75 g m(-3) h(-1). Experiments under transient conditions revealed a competitive substrate interaction between MTBE and hexane. Biomass densities between 5.8 and 12.6 g L(biofilter) (-1) were obtained. Nevertheless, production of biopolymers caused non-uniform distribution flow rates that reduced the performance. Residence time distribution profiles showed an intermediate dispersion flow rate with a dispersion coefficient of 0.8 cm(2) s(-1). PMID:22486671

  10. Groundwater remediation by an in situ biobarrier: A bench scale feasibility test for methyl tert-butyl ether and other gasoline compounds

    Microsoft Academic Search

    Sabrina Saponaro; Marco Negri; Elena Sezenna; Luca Bonomo; Claudia Sorlini

    2009-01-01

    Most gasoline contains high percentages of methyl tert-butyl ether (MTBE) as an additive. The physico-chemical properties of this substance (high water solubility, low sorption in soil) result in high mobility and dissolved concentrations in soil. In situ permeable biological barriers (biobarriers, BBs) can remediate MTBE polluted groundwater by allowing pure cultures or microbial consortia to degrade MTBE when aerobic conditions

  11. Oxidation of Methyl tertButyl Ether by Alkane Hydroxylase in Dicyclopropylketone-Induced and n-Octane-Grown Pseudomonas putida GPo1

    Microsoft Academic Search

    Christy A. Smith; Michael R. Hyman

    2004-01-01

    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

  12. Arbuscular mycorrhizal fungi in a wetland constructed for benzene-, methyl tert-butyl ether- and ammonia-contaminated groundwater bioremediation.

    PubMed

    Fester, Thomas

    2013-01-01

    Arbuscular mycorrhizal fungi (AMF), which are present in most natural environments, have demonstrated capacity to promote biodegradation of organic pollutants in the greenhouse. However, it is not certain whether AMF can spontaneously establish in phytoremediation systems constructed to decontaminate groundwater, because of the unusual conditions during the construction and operation of such systems. To assess this possibility, root samples from a wetland constructed for the phytoremediation of groundwater contaminated with benzene, methyl tert-butyl ether and ammonia were analysed. Substantial AMF colonization was observed in plant roots sampled close to the inlet of a basin filled with fine gravel and planted with Phragmites australis. In addition, analysis of a fragment of the nuclear large ribosomal subunit, amplified by nested PCR, revealed the presence of AMF molecular operational taxonomic units closely related to Funneliformis mosseae and Rhizophagus irregularis in the samples. These findings demonstrate the capacity of generalist AMF strains to establish spontaneously, rapidly and extensively in groundwater bioremediation technical installations. PMID:22846140

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

    PubMed

    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 (3-30min) and at a fixed pressure of 20MPa 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 20MPa, canola oil was completely converted to biodiesel after 10, 30, and 30min 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. PMID:26004381

  14. Crystal structure of (1,3-di-tert-butyl-?5-cyclo­penta­dien­yl)tri­methyl­hafnium(IV)

    PubMed Central

    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(?5-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

  15. 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

    USGS Publications Warehouse

    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 ether was detected as deep as ?9.5 feet mean sea level. Increased methane concentrations and decreased dissolved oxygen concentrations that were found in association with the ground-water samples that contained methyl tert-butyl ether are preliminary indicators that will assist in determining if natural attenuation of methyl tert-butyl ether is occurring in the surficial aquifer. A full assessment of natural attenuation of methyl tert-butyl ether at the site is beyond the scope of this study, but the data collected during the study will be useful in selecting appropriate remedial methyl tert-butyl ether demonstrations.

  16. Synthesis and cytotoxic activity of derivatives of the tert -butyl ester of 7 Z -acetylmethylene-3-methyl-3-cephem-4-carboxylic acid

    Microsoft Academic Search

    I. Potorocina; M. Vorona; G. Veinberg; I. Shestakova; I. Kanepe; M. Petrova; E. Liepinsh; E. Lukevics

    2009-01-01

    The condensation of the acetylmethylene group in the tert-butyl esters of 7Z-acetylmethylene-3-methyl-3-cephem-4-carboxylic acid and 7Z-acetylmethylene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid and in 7Z-acetylmethylene-3-methylene-1,1-dioxo-3-cephem with arylmethoxyamines and O-alkylation of the tert-butyl ester of 7Z-(2-hydroxyimino)propylidene-3-methyl-1,1-dioxo-3-cephem-4-carboxylic acid using substituted benzyl bromides as well as pyridylmethyl\\u000a chlorides gave arylmethoxyimino and pyridylmethoxyimino derivatives of these compounds in the syn and anti isomeric forms.\\u000a The Vilsmaier reagent was used to

  17. Reaction of Unsaturated Esters with the Oxidative System Aluminum Tri-tert-Butoxide-tert-Butyl Hydroperoxide

    Microsoft Academic Search

    L. P. Stepovik; I. M. Martynova; V. A. Dodonov

    2002-01-01

    Unsaturated esters containing double bonds in the acyl (methyl acrylate) or in the alcohol (vinyl and allyl acetates) fragments are cleaved under mild conditions (20°C) by the system aluminum tri-tert-butoxide-tert-butyl hydroperoxide to give tert-butyl esters of peroxycarboxylic acids and unsymmetrical aluminum alkoxides. The double bond in the acyl fragment is inert to this oxidation system. Vinyloxy- and allyloxy derivatives are

  18. Evaluation of the intrinsic methyl tert-butyl ether (MTBE) biodegradation potential of hydrocarbon contaminated subsurface soils in batch microcosm systems

    Microsoft Academic Search

    David Moreels; Leen Bastiaens; Frans Ollevier; Roel Merckx; Ludo Diels; Dirk Springael

    2004-01-01

    Eleven soil samples (contaminated and non-contaminated top soils and aquifers) from seven different locations in Belgium were examined in lab-scale batch microcosms simulating in situ conditions for their indigenous capacity to biodegrade methyl tert-butyl ether (MTBE). The effect of implementing nutrients or additional oxygen and of the presence of co-contaminants on MTBE degradation was investigated. All soils showed rapid degradation

  19. Detection and Quantification of Methyl tertButyl Ether-Degrading Strain PM1 by Real-Time TaqMan PCR

    Microsoft Academic Search

    KRASSIMIRA R. HRISTOVA; CHRISTIAN M. LUTENEGGER; KATE M. SCOW

    2001-01-01

    The fuel oxygenate methyl tert-butyl ether (MTBE), a widely distributed groundwater contaminant, shows potential for treatment by in situ bioremediation. The bacterial strain PM1 rapidly mineralizes and grows on MTBE in laboratory cultures and can degrade the contaminant when inoculated into groundwater or soil microcosms. We applied the TaqMan quantitative PCR method to detect and quantify strain PM1 in labora-

  20. Crystal structure of 2,3-bis-[(4-tert-butyl-2,6-di-methyl-phen-yl)imino]-butane.

    PubMed

    Zhao, Sheng-Lan; Yuan, Jian-Chao; Zhao, Yan

    2015-04-01

    The title compound, C28H40N2, was obtained from the condensation reaction of 4-tert-butyl-2,6-di-methyl-aniline and butane-2,3-dione. The mol-ecule lies on an inversion centre. The C=N bond has an E conformation. The plane of the benzene ring is almost perpendicular to the 1,4-di-aza-butadiene mean plane [dihedral angle = 89.8?(9)°]. PMID:26029444

  1. Crystal structure of 2,3-bis­[(4-tert-butyl-2,6-di­methyl­phen­yl)imino]­butane

    PubMed Central

    Zhao, Sheng-Lan; Yuan, Jian-Chao; Zhao, Yan

    2015-01-01

    The title compound, C28H40N2, was obtained from the condensation reaction of 4-tert-butyl-2,6-di­methyl­aniline and butane-2,3-dione. The mol­ecule lies on an inversion centre. The C=N bond has an E conformation. The plane of the benzene ring is almost perpendicular to the 1,4-di­aza­butadiene mean plane [dihedral angle = 89.8?(9)°].

  2. Di-tert-butyl 1-[2-hy­droxy-3-(methyl­sulfan­yl)prop­yl]hydrazine-1,2-di­carboxyl­ate

    PubMed Central

    Bai, Xiao-Guang; Yang, Xiao-Yu; Wang, Ju-Xian

    2014-01-01

    The title compound, C14H28N2O5S, was synthesized by the reaction of 2-[(methyl­sulfan­yl)meth­yl]oxirane with di-tert-butyl oxalate in hydrazine hydrate. In the crystal, mol­ecules are linked by N—H?O and O—H?O hydrogen bonds into supra­molecular chains propagating along the b-axis direction. PMID:25249896

  3. Anaerobic methyl tert-butyl ether-degrading microorganisms identified in wastewater treatment plant samples by stable isotope probing.

    PubMed

    Sun, Weimin; Sun, Xiaoxu; Cupples, Alison M

    2012-04-01

    Anaerobic methyl tert-butyl ether (MTBE) degradation potential was investigated in samples from a range of sources. From these 22 experimental variations, only one source (from wastewater treatment plant samples) exhibited MTBE degradation. These microcosms were methanogenic and were subjected to DNA-based stable isotope probing (SIP) targeted to both bacteria and archaea to identify the putative MTBE degraders. For this purpose, DNA was extracted at two time points, subjected to ultracentrifugation, fractioning, and terminal restriction fragment length polymorphism (TRFLP). In addition, bacterial and archaeal 16S rRNA gene clone libraries were constructed. The SIP experiments indicated bacteria in the phyla Firmicutes (family Ruminococcaceae) and Alphaproteobacteria (genus Sphingopyxis) were the dominant MTBE degraders. Previous studies have suggested a role for Firmicutes in anaerobic MTBE degradation; however, the putative MTBE-degrading microorganism in the current study is a novel MTBE-degrading phylotype within this phylum. Two archaeal phylotypes (genera Methanosarcina and Methanocorpusculum) were also enriched in the heavy fractions, and these organisms may be responsible for minor amounts of MTBE degradation or for the uptake of metabolites released from the primary MTBE degraders. Currently, limited information exists on the microorganisms able to degrade MTBE under anaerobic conditions. This work represents the first application of DNA-based SIP to identify anaerobic MTBE-degrading microorganisms in laboratory microcosms and therefore provides a valuable set of data to definitively link identity with anaerobic MTBE degradation. PMID:22327600

  4. Anaerobic Methyl tert-Butyl Ether-Degrading Microorganisms Identified in Wastewater Treatment Plant Samples by Stable Isotope Probing

    PubMed Central

    Sun, Weimin; Sun, Xiaoxu

    2012-01-01

    Anaerobic methyl tert-butyl ether (MTBE) degradation potential was investigated in samples from a range of sources. From these 22 experimental variations, only one source (from wastewater treatment plant samples) exhibited MTBE degradation. These microcosms were methanogenic and were subjected to DNA-based stable isotope probing (SIP) targeted to both bacteria and archaea to identify the putative MTBE degraders. For this purpose, DNA was extracted at two time points, subjected to ultracentrifugation, fractioning, and terminal restriction fragment length polymorphism (TRFLP). In addition, bacterial and archaeal 16S rRNA gene clone libraries were constructed. The SIP experiments indicated bacteria in the phyla Firmicutes (family Ruminococcaceae) and Alphaproteobacteria (genus Sphingopyxis) were the dominant MTBE degraders. Previous studies have suggested a role for Firmicutes in anaerobic MTBE degradation; however, the putative MTBE-degrading microorganism in the current study is a novel MTBE-degrading phylotype within this phylum. Two archaeal phylotypes (genera Methanosarcina and Methanocorpusculum) were also enriched in the heavy fractions, and these organisms may be responsible for minor amounts of MTBE degradation or for the uptake of metabolites released from the primary MTBE degraders. Currently, limited information exists on the microorganisms able to degrade MTBE under anaerobic conditions. This work represents the first application of DNA-based SIP to identify anaerobic MTBE-degrading microorganisms in laboratory microcosms and therefore provides a valuable set of data to definitively link identity with anaerobic MTBE degradation. PMID:22327600

  5. Methyl tert-butyl ether occurrence and related factors in public and private wells in Southeast New Hampshire

    USGS Publications Warehouse

    Ayotte, J.D.; Argue, D.M.; McGarry, F.J.

    2005-01-01

    The occurrence of methyl tert-butyl ether (MTBE) in water from public wells in New Hampshire has increased steadily over the past several years. Using a laboratory reporting level of 0.2 ??g/L, 40% of samples from public wells and 21% from private wells in southeast New Hampshire have measurable concentrations of MTBE. The rate of occurrence of MTBE varied significantly for public wells by establishment type; for example, 63% of public wells serving residential properties have MTBE concentrations above 0.2 ??g/L, whereas lower rates were found for schools (21%). MTBE concentrations correlate strongly with urban factors, such as population density. Surprisingly, MTBE was correlated positively with well depth for public supply wells. Well depth is inversely related to yield in New Hampshire bedrock wells, which may mean that there is less opportunity for dilution of MTBE captured by deep wells. Another possibility is that the source(s) of water to low-yield wells may be dominated by leakage from potentially contaminated shallow groundwater through near-surface fractures or along the well casing. These wells may also have relatively large contributing areas (due to low recharge at the bedrock surface) and therefore have a greater chance of intersecting MTBE sources. This finding is significant because deep bedrock wells are often considered to be less vulnerable to contamination than shallow wells, and in southeast New Hampshire, wells are being drilled deeper in search of increased supply.

  6. Methyl tert-butyl ether (MTBE) in public and private wells in New Hampshire: Occurrence, factors, and possible implications

    USGS Publications Warehouse

    Ayotte, J.D.; Argue, D.M.; McGarry, F.J.; Degnan, J.R.; Hayes, L.; Flanagan, S.M.; Helsel, D.R.

    2008-01-01

    Methyl tert-butyl ether (MTBE) concentrations ???0.2 ??g/L were found in samples of untreated water in 18% of public-supply wells (n = 284) and 9.1% of private domestic wells (n = 264) sampled in 2005 and 2006 in New Hampshire. In counties that used reformulated gasoline (RFG), MTBE occurred at or above 0.2 ??g/L in 30% of public- and 17% of private-supply wells. Additionally, 52% of public-supply wells collocated with fuel storage and 71% of mobile home park wells had MTBE. MTBE occurrence in public-supply wells was predicted by factors such as proximity to sources of fuel, land use, and population density, as well as low pH and distance from mapped lineaments. RFG use, land-use variables, and pH were important predictors of private-well MTBE occurrence. Variables representing sources of MTBE, such as the distance to known fuel sources, were not significant predictors of MTBE occurrence in private-supply wells. It is hypothesized that private wells may become contaminated from the collective effects of sources in high population areas and from undocumented incidental releases from onsite or proximal gasoline use. From 2003 to 2005, MTBE occurrence decreased in 63 public-supply wells and increased in 60 private-supply wells, but neither trend was statistically significant. ?? 2008 American Chemical Society.

  7. Evaluating UV/H2O2 processes for methyl tert-butyl ether and tertiary butyl alcohol removal: effect of pretreatment options and light sources.

    PubMed

    Li, Ke; Hokanson, David R; Crittenden, John C; Trussell, Rhodes R; Minakata, Daisuke

    2008-12-01

    In this paper, we evaluate the efficiency of UV/H2O2 process to remove methyl tert-butyl ether (MtBE) and tertiary butyl alcohol (tBA) from a drinking water source. Kinetic models were used to evaluate the removal efficiency of the UV/H2O2 technologies with different pretreatment options and light sources. Two commercial UV light sources, i.e. low pressure, high intensity lamps and medium pressure, high intensity lamps, were evaluated. The following pretreatment alternatives were evaluated: (1) ion exchange softening with seawater regeneration (NaIX); (2) Pellet Softening; (3) weak acid ion exchange (WAIX); and (4) high pH lime softening followed by reverse osmosis (RO). The presence or absence of a dealkalization step prior to the UV/H2O2 Advanced Oxidation Process (AOP) was also evaluated for each pretreatment possibility. Pretreatment has a significant impact on the performance of UV/H2O2 process. The NaIX with dealkalization was shown to be the most cost effective. The electrical energy per order (EEO) values for MtBE and tBA using low pressure high output UV lamps (LPUV) and 10mg/LH2O2 are 0.77 and 3.0 kWh/kgal-order, or 0.20 and 0.79 kWh/m3-order, respectively. For medium pressure UV high output lamps (MPUV), EEO values for MtBE and tBA are 4.6 and 15 kWh/kgal-order, or 1.2 and 4.0 kWh/m3-order, for the same H2O2 dosage. PMID:18951605

  8. Gene mdpC plays a regulatory role in the methyl-tert-butyl ether degradation pathway of Methylibium petroleiphilum strain PM1.

    PubMed

    Joshi, Geetika; Schmidt, Radomir; Scow, Kate M; Denison, Michael S; Hristova, Krassimira R

    2015-04-01

    Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes. Our results indicate that gene mdpC is involved in the induction of both mdpA and mdpJ in response to MTBE and tert-butyl alcohol (TBA) exposure in PM1. An additional independent mechanism may be involved in the induction of mdpJ in the presence of TBA. PMID:25724531

  9. Convenient preparation of tert-butyl esters

    Microsoft Academic Search

    Douglass F. Taber; David A. Gerstenhaber; Xia Zhao

    2006-01-01

    A general method is presented for the preparation of tert-butyl esters by the gentle warming of the carboxylic acid in the presence of excess of tert-butyl acetoacetate and a catalytic amount of acid. This method generates only low pressures, and is therefore suitable for laboratory scale pressure glassware.

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

    PubMed

    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. PMID:24128854

  11. Whole-genorne analysis of the methyl tert-butyl ether-degrading beta-proteobacterium Methylibium petroleiphilum PM1

    SciTech Connect

    Kane, Staci R. [Lawrence Livermore National Laboratory (LLNL); Chakicherla, Anu Y. [Lawrence Livermore National Laboratory (LLNL); Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Schmidt, Radomir [University of California, Davis; Shin, M [U.S. Department of Energy, Joint Genome Institute; Legler, Tina C. [Lawrence Livermore National Laboratory (LLNL); Scow, Kate M. [University of California, Davis; Larimer, Frank W [ORNL; Lucas, Susan [Joint Genome Institute, Walnut Creek, California; Richardson, P M [U.S. Department of Energy, Joint Genome Institute; Hristova, Krassimira R. [University of California, Davis

    2007-03-01

    Methylibium petroleiphilum PM1 is a methylotroph distinguished by its ability to completely metabolize the fuel oxygenate methyl tert-butyl ether (MTBE). Strain PM1 also degrades aromatic (benzene, toluene, and xylene) and straight-chain (C, to C,,) hydrocarbons present in petroleum products. Whole-genome analysis of PM1 revealed an similar to 4-Mb circular chromosome and an similar to 600-kb megaplasmid, containing 3,831 and 646 genes, respectively. Aromatic hydrocarbon and alkane degradation, metal resistance, and methylotrophy are encoded on the chromosome. The megaplasmid contains an unusual t-RNA island, numerous insertion sequences, and large repeated elements, including a 40-kb region also present on the chromosome and a 29-kb tandem repeat encoding phosphonate transport and cobalamin biosynthesis. The megaplasmid also codes for alkane degradation and was shown to play an essential role in MTBE degradation through plasmid-curing experiments. Discrepancies between the insertion sequence element distribution patterns, the distributions of best BLASTP hits among major phylogenetic groups, and the G+C contents of the chromosome (69.2%) and plasmid (66%), together with comparative genome hybridization experiments, suggest that the plasmid was recently acquired and apparently carries the genetic information responsible for PM1's ability to degrade MTBE. Comparative genomic hybridization analysis with two PM1-like MTBE-degrading environmental isolates (similar to 99% identical 16S rRNA gene sequences) showed that the plasmid was highly conserved (ca. 99% identical), whereas the chromosomes were too diverse to conduct resequencing analysis. PM1's genome sequence provides a foundation for investigating MTBE biodegradation and exploring the genetic regulation of multiple biodegradation pathways in M. petroleiphilum and other MTBE-degrading beta-proteobacteria.

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

    SciTech Connect

    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.

  13. Enhancing Transport of Hydrogenophaga flava ENV735 for Bioaugmentation of Aquifers Contaminated with Methyl tert-Butyl Ether

    PubMed Central

    Streger, Sheryl H.; Vainberg, Simon; Dong, Hailiang; Hatzinger, Paul B.

    2002-01-01

    The gasoline oxygenate methyl tert-butyl ether (MTBE) has become a widespread contaminant in groundwater throughout the United States. Bioaugmentation of aquifers with MTBE-degrading cultures may be necessary to enhance degradation of the oxygenate in some locations. However, poor cell transport has sometimes limited bioaugmentation efforts in the past. The objective of this study was to evaluate the transport characteristics of Hydrogenophaga flava ENV735, a pure culture capable of growth on MTBE, and to improve movement of the strain through aquifer solids. The wild-type culture moved only a few centimeters in columns of aquifer sediment. An adhesion-deficient variant (H. flava ENV735:24) of the wild-type strain that moved more readily through sediments was obtained by sequential passage of cells through columns of sterile sediment. Hydrophobic and electrostatic interaction chromatography revealed that the wild-type strain is much more hydrophobic than the adhesion-deficient variant. Electrophoretic mobility assays and transmission electron microscopy showed that the wild-type bacterium contains two distinct subpopulations, whereas the adhesion-deficient strain has only a single, homogeneous population. Both the wild-type strain and adhesion-deficient variant degraded MTBE, and both were identified by 16S rRNA analysis as pure cultures of H. flava. The effectiveness of surfactants for enhancing transport of the wild-type strain was also evaluated. Many of the surfactants tested were toxic to ENV735; however, one nonionic surfactant, Tween 20, enhanced cell transport in sand columns. Improving microbial transport may lead to a more effective bioaugmentation strategy for MTBE-contaminated sites where indigenous oxygenate degraders are absent. PMID:12406751

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

    SciTech Connect

    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-induced vascular lesions. • Inhibiting PHD or knocking down VHL rescues MTBE-induced vascular lesions. • HIF1-Vegf driven angiogenesis is a target for MTBE vascular toxicity.

  15. Biodegradation of tert -butyl alcohol and related xenobiotics by a methylotrophic bacterial isolate

    Microsoft Academic Search

    P. Piveteau; F. Fayolle; J.-P. Vandecasteele; F. Monot

    2001-01-01

    A new aerobic bacterial strain, CIP I-2052, isolated from an activated sludge sample, was able to use tert-butyl alcohol (TBA), a product of methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) degradation, as its sole carbon and energy source. Cobalt ions stimulated TBA mineralization. The maximum growth and TBA degradation rates were 0.032ǂ.004 h-1 and 35.8NJ.5 mg TBA·g-1 (cell

  16. Determination of Methyl tert-Butyl Ether and tert-Butyl Alcohol in Water by Solid-Phase Microextraction/Head Space Analysis in Comparison to EPA Method 5030/8260B

    SciTech Connect

    Oh, Keun-Chan; Stringfellow, William T.

    2003-10-02

    Methyl tert-butyl ether (MTBE) is now one of the most common groundwater contaminants in the United States. Groundwater contaminated with MTBE is also likely to be contaminated with tert-butyl alcohol (TBA), because TBA is a component of commercial grade MTBE, TBA can also be used as a fuel oxygenate, and TBA is a biodegradation product of MTBE. In California, MTBE is subject to reporting at concentrations greater than 3 {micro}g/L. TBA is classified as a ''contaminant of current interest'' and has a drinking water action level of 12 {micro}g/L. In this paper, we describe the development and optimization of a simple, automated solid phase microextraction (SPME) method for the analysis of MTBE and TBA in water and demonstrate the applicability of this method for monitoring MTBE and TBA contamination in groundwater, drinking water, and surface water. In this method, the headspace (HS) of a water sample is extracted with a carboxen/polydimethylsiloxane SPME fiber, the MTBE and TBA are desorbed into a gas chromatograph (GC), and detected using mass spectrometry (MS). The method is optimized for the routine analysis of MTBE and TBA with a level of quantitation of 0.3 {micro}g/L and 4 {micro}g/L, respectively, in water. MTBE quantitation was linear for over two orders of concentration (0.3 {micro}g/L -80 {micro}g/L). TBA was found to be linear within the range of 4 {micro}g/L-7,900 {micro}g/L. The lower level of detection for MTBE is 0.03 {micro}g/L using this method. This SPME method using headspace extraction was found to be advantageous over SPME methods requiring immersion of the fiber into the water samples, because it prolonged the life of the fiber by up to 400 sample analyses. This is the first time headspace extraction SPME has been shown to be applicable to the measurement of both MTBE and TBA at concentrations below regulatory action levels. This method was compared with the certified EPA Method 5030/8260B (purge-and-trap/GC/MS) using split samples from laboratory bioreactors treating MTBE contaminated water and applied to environmental samples collected throughout the East Bay area of California. Results from the SPME-HS/GC/MS method were directly comparable to the EPA Method 5030/8260B. This method provides an simple, inexpensive, accurate, and sensitive alternative to EPA Method 5030/8260B for the analysis of MTBE and TBA in water samples.

  17. Decomposition rates of methyl tert-butyl ether and its by-products by the Fenton system in saline wastewaters

    Microsoft Academic Search

    E. M. Siedlecka; P. Stepnowski

    2006-01-01

    The primary aim of this study was to gain an understanding of how different concentrations of chloride ions affect the oxidation of methyl t-butyl ether (MTBE) in the Fenton system. Oxidation of MTBE in a chloride-free reaction mixture was rapid and very effective, but was inhibited even by the lowest chloride concentrations employed. After 90min of reaction in the presence

  18. Methyl tert-butyl ether degradation in the unsaturated zone and the relation between MTBE in the atmosphere and shallow groundwater

    NASA Astrophysics Data System (ADS)

    Baehr, Arthur L.; Charles, Emmanuel G.; Baker, Ronald J.

    2001-02-01

    Atmospheric methyl tert-butyl ether (MTBE) concentrations in southern New Jersey generally exceeded concentrations in samples taken from the unsaturated zone. A simple unsaturated zone transport model indicates that MTBE degradation can explain the attenuation with half-lives from a few months to a couple of years. Tert-butyl alcohol (TBA), a possible degradation product of MTBE, was detected in unsaturated-zone samples at concentrations exceeding atmospheric levels at some sites, suggesting the possible conversion of MTBE to TBA. At sites where MTBE was detected in shallow groundwater, the concentration was typically higher than the overlying unsaturated-zone concentration. This observation is consistent with outgassing from the aquifer and combined with the unsaturated-zone attenuation suggests some of the MTBE detections in shallow groundwater are nonatmospheric in origin, coming from leaking tanks, road runoff, or other sources. The identification of sources of MTBE in groundwater and attenuation mechanisms through the hydrologic cycle is critical in developing an understanding of the long-term effect of MTBE releases.

  19. Methyl tert-butyl ether degradation in the unsaturated zone and the relation between MTBE in the atmosphere and shallow groundwater

    USGS Publications Warehouse

    Baehr, A.L.; Charles, E.G.; Baker, R.J.

    2001-01-01

    Atmospheric methyl tert-butyl ether (MTBE) concentrations in southern New Jersey generally exceeded concentrations in samples taken from the unsaturated zone. A simple unsaturated zone transport model indicates that MTBE degradation can explain the attenuation with half-lives from a few months to a couple of years. Tert-butyl alcohol (TBA), a possible degradation product of MTBE, was detected in unsaturated-zone samples at concentrations exceeding atmospheric levels at some sites, suggesting the possible conversion of MTBE to TBA. At sites where MTBE was detected in shallow groundwater, the concentration was typically higher than the overlying unsaturated-zone concentration. This observation is consistent with outgassing from the aquifer and combined with the unsaturated-zone attenuation suggests some of the MTBE detections in shallow groundwater are nonatmospheric in origin, coming from leaking tanks, road runoff, or other sources. The identification of sources of MTBE in groundwater and attenuation mechanisms through the hydrologic cycle is critical in developing an understanding of the long-term effect of MTBE releases.

  20. 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.

    PubMed

    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 <10%. Analysis with a headspace gas chromatography revealed methyl tert-butyl ether (MTBE) concentrations of 185 mg/L (female victim) and 115 mg/L (male victim) in peripheral blood. The urine MTBE concentrations were 150 mg/L and 256 mg/L, respectively. MTBE is a synthetic chemical which is added to 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. PMID:23879346

  1. Treatment of methyl tert-butyl ether vapors in a biotrickling filters. 2. Analysis of the rate-limiting step and behavior under transient conditions

    SciTech Connect

    Fortin, N.Y.; Deshusses, M.A. [Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering] [Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering

    1999-09-01

    Detailed experiments were performed with gas phase biotrickling filters treating vapors of methyl tert-butyl ether (MTBE), a gasoline additive of great environmental concern. A particular emphasis was placed on the analysis of the rate-limiting step, and it was found that the process was mostly limited by the biological reaction rather than by mass transfer. Further experiments involved the study of the dynamic behavior of the biotrickling filters under simulated field conditions. In all cases, the biotrickling filters adapted rapidly to the new conditions, and new steady states were obtained within hours. The relevance of the results and the implications as far as implementation of biotrickling filters for field MTBE treatment are discussed.

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

    SciTech Connect

    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.

  3. Differential toxic effects of methyl tertiary butyl ether and tert-butanol on rat fibroblasts in vitro.

    PubMed

    Sgambato, A; Iavicoli, I; De Paola, B; Bianchino, G; Boninsegna, A; Bergamaschi, A; Pietroiusti, A; Cittadini, A

    2009-03-01

    Methyl tertiary butyl ether (MTBE) is the most widely used motor vehicle fuel oxygenate since it reduces harmful emissions due to gasoline combustion. However, the significant increase in its use in recent years has raised new questions related to its potential toxicity. In fact, although available data are somehow conflicting, there is evidence that MTBE is a toxic substance that may have harmful effects on both animals and humans and an unresolved problem is the role played by MTBE metabolites, especially tertiary butyl alcohol (TBA), in determining toxic effects due to MTBE exposure. In this study, the toxic effects of MTBE have been analyzed on a normal diploid rat fibroblast cell line (Rat-1) and compared to the effects of TBA. The results obtained suggest that both MTBE and TBA inhibit cell growth in vitro but with different mechanisms in terms of effects on the cell cycle progression and on the modulation of cell cycle regulatory proteins. In fact, MTBE caused an accumulation of cells in the S-phase of the cell cycle, whereas TBA caused an accumulation in the G0/G1-phase with different effects on the expression of cyclin D1, p27Kip1, and p53. Moreover, both MTBE and TBA were also shown to induce DNA damage, as assessed in terms of oxidative DNA damage and nuclear DNA fragmentation, that appeared to be susceptible of repair by the cell DNA-repair machinery. In conclusion, these findings suggest that both MTBE and TBA can exert, by acting through different molecular mechanisms, important biological effects on fibroblasts in vitro. Further studies are warranted to shed light on the mechanisms responsible for the observed effects and on their potential significance for the in-vivo exposure. PMID:19458137

  4. Tetra­chlorido­[N 2,N 2?-(di­methyl­silanedi­yl)bis­(N-tert-butyl-3-methyl­benzimid­amid­ato)-?2 N 2,N 2?]hafnium(IV)

    PubMed Central

    Wang, Tao; Zhao, Jian-Ping; Bai, Sheng-Di

    2013-01-01

    The symmetric title mol­ecule, [Hf(C26H40N4Si)Cl4], 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 N 2,N 2?-(di­methyl­silanedi­yl)bis­(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. PMID:24454166

  5. Tetra-chlorido-[N (2),N (2')-(di-methyl-silanedi-yl)bis-(N-tert-butyl-3-methyl-benzimid-amid-ato)-?(2) N (2),N (2')]hafnium(IV).

    PubMed

    Wang, Tao; Zhao, Jian-Ping; Bai, Sheng-Di

    2013-11-13

    The symmetric title mol-ecule, [Hf(C26H40N4Si)Cl4], lies about a twofold rotation axis. The Hf(IV) and Si atoms lie on the rotation axis with all other atoms being in general positions. The Hf(IV) atom is six-coordinated by two N atoms from the N (2),N (2')-(di-methyl-silanedi-yl)bis-(N-tert-butyl-3-methyl-benz-imid-amidate) ligand and four Cl(-) ions in a slightly distorted octa-hedral 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. PMID:24454166

  6. Treatment of methyl tert-butyl ether vapors in biotrickling filters. 1. Reactor startup, steady-state performance, and culture characteristics

    SciTech Connect

    Fortin, N.Y.; Deshusses, M.A. [Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering] [Univ. of California, Riverside, CA (United States). Dept. of Chemical and Environmental Engineering

    1999-09-01

    An aerobic microbial consortium able to biodegrade methyl tert-butyl ether (MTBE) was enriched in two waste air biotrickling filters after continuous operation for 6 months. After this acclimation phase, the two laboratory-scale biotrickling filters were able to degrade up to 50 g of MTBE per cubic meter of reactor per hour, a value comparable to other gasoline constituents. Such high performance could be sustained for at least 4--6 weeks. After the acclimation phase, the MTBE degrading biotrickling filters were characterized by their almost full conversion of MTBE to carbon dioxide and the absence of any degradation byproducts in either the gas or the liquid phase. They also exhibited a very high specific degradation activity per amount of biomass, and a low rate of biomass accumulation. An observed biomass yield of 0.1 g g{sup {minus}1} and a specific growth rate of 0.025 day{sup {minus}1} were determined for the biotrickling filter process culture. Further data on MTBE mass transfer and on the dynamic behavior of the biotrickling filter are presented in part 2 of this paper. Overall, the results demonstrate that MTBE can be effectively biodegraded under carefully controlled environmental conditions.

  7. Simultaneous extraction of metabolome and lipidome with methyl tert-butyl ether from a single small tissue sample for ultra-high performance liquid chromatography/mass spectrometry.

    PubMed

    Chen, Shili; Hoene, Miriam; Li, Jia; Li, Yanjie; Zhao, Xinjie; Häring, Hans-Ulrich; Schleicher, Erwin D; Weigert, Cora; Xu, Guowang; Lehmann, Rainer

    2013-07-12

    A common challenge for scientists working with animal tissue or human biopsy samples is the limitation of material and consequently, the difficulty to perform comprehensive metabolic profiling within one experiment. Here, we present a novel approach to simultaneously perform targeted and non-targeted metabolomics as well as lipidomics from one small piece of liver or muscle tissue by ultra-high performance liquid chromatography/mass spectrometry (UHPLC/MS) following a methyl tert-butyl ether (MTBE)-based extraction. Equal relative amounts of the resulting polar and non-polar fractions were pooled, evaporated and reconstituted in the appropriate solvent for UHPLC/MS analysis. This mix was comparable or superior in yield and reproducibility to a standard 80% methanol extraction for the profiling of polar and lipophilic metabolites (free carnitine, acylcarnitines and FFA). The mix was also suitable for non-targeted metabolomics, an easy measure to increase the metabolite coverage by 30% relative to using the polar fraction alone. Lipidomics was performed from an aliquot of the non-polar fraction. This novel strategy could successfully be applied to one mouse soleus muscle with a dry weight of merely 2.5 mg. By enabling a simultaneous profiling of lipids and metabolites with mixed polarity while saving material for molecular, biochemical or histological analyses, our approach may open up new perspectives toward a comprehensive investigation of small, valuable tissue samples. PMID:23743007

  8. Spectroscopic investigation, natural bond orbital analysis, HOMO-LUMO and thermodynamic functions of 2-tert-butyl-5-methyl anisole using DFT (B3LYP) calculations

    NASA Astrophysics Data System (ADS)

    Balachandran, V.; Santhi, G.; Karpagam, V.; Revathi, B.; Karabacak, M.

    2015-02-01

    The optimized molecular structure and corresponding vibrational assignments of 2-tert-butyl-5-methyl anisole (TBMA) have been investigated using density functional theory (DFT)/B3LYP with 6-31G(d,p) and 6-311++G(d,p) basis sets investigation of the relative orientation of the methoxy group has shown two conformers (O-cis) and (O-trans) exist. The vibrational analysis of the stable conformer of the title compound is performed by means of infrared absorption and Raman spectroscopy in combination with theoretical simultaneously. The natural bond orbital (NBO) analysis is useful to understand the intra-molecular hyper conjugative interaction lone pair and ??(Csbnd C), ??(Csbnd H) bond orbital. HOMO and LUMO energies show that charge transfer occurs in the molecule, therefore; HOMO, LUMO and molecular electrostatic potential (MEP) were calculated and analyzed. 1H and 13C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data. The thermodynamic functions of TBMA were calculated by B3LYP/6-311+G(d,p) basis set.

  9. Occurrence and temporal variability of methyl tert-butyl ether (MTBE) and other volatile organic compounds in select sources of drinking water : results of the focused survey

    USGS Publications Warehouse

    Delzer, Gregory C.; Ivahnenko, Tamara

    2003-01-01

    The large-scale use of the gasoline oxygenate methyl tert-butyl ether (MTBE), and its high solubility, low soil adsorption, and low biodegradability, has resulted in its detection in ground water and surface water in many places throughout the United States. Studies by numerous researchers, as well as many State and local environmental agencies, have discovered high levels of MTBE in soils and ground water at leaking underground gasoline-storage-tank sites and frequent occurrence of low to intermediate levels of MTBE in reservoirs used for both public water supply and recreational boating.In response to these findings, the American Water Works Association Research Foundation sponsored an investigation of MTBE and other volatile organic compounds (VOCs) in the Nation?s sources of drinking water. The goal of the investigation was to provide additional information on the frequency of occurrence, concentration, and temporal variability of MTBE and other VOCs in source water used by community water systems (CWSs). The investigation was completed in two stages: (1) reviews of available literature and (2) the collection of new data. Two surveys were associated with the collection of new data. The first, termed the Random Survey, employed a statistically stratified design for sampling source water from 954 randomly selected CWSs. The second, which is the focus of this report, is termed the Focused Survey, which included samples collected from 134 CWS source waters, including ground water, reservoirs, lakes, rivers, and streams, that were suspected or known to contain MTBE. The general intent of the Focused Survey was to compare results with the Random Survey and provide an improved understanding of the occurrence, concentration, temporal variability, and anthropogenic factors associated with frequently detected VOCs. Each sample collected was analyzed for 66 VOCs, including MTBE and three other ether gasoline oxygenates (hereafter termed gasoline oxygenates). As part of the Focused Survey, 451 source-water samples and 744 field quality-control (QC) samples were collected from 78 ground-water, 39 reservoir and (or) lake, and 17 river and (or) stream source waters at fixed intervals for a period of 1 year.Using a common assessment level of 0.2 ?g/L (micrograms per liter) (2.0 ?g/L for methyl ethyl ketone), 37 of the 66 VOCs analyzed were detected in both surveys. However, VOCs, especially MTBE and other gasoline oxygenates, were detected more frequently in the Focused Survey than in the Random Survey. MTBE was detected in 55.5 percent of the CWSs sampled in the Focused Survey and in 8.7 percent of those sampled in the Random Survey. Little difference in occurrence, however, was observed for trihalomethanes (THMs), which were detected in 16.4 and 14.8 percent of Focused Survey and The large-scale use of the gasoline oxygenate methyl tert-butyl ether (MTBE), and its high solubility, low soil adsorption, and low biodegradability, has resulted in its detection in ground water and surface water in many places throughout the United States. Studies by numerous researchers, as well as many State and local environmental agencies, have discovered high levels of MTBE in soils and ground water at leaking underground gasoline-storage-tank sites and frequent occurrence of low to intermediate levels of MTBE in reservoirs used for both public water supply and recreational boating.In response to these findings, the American Water Works Association Research Foundation sponsored an investigation of MTBE and other volatile organic compounds (VOCs) in the Nation?s sources of drinking water. The goal of the investigation was to provide additional information on the frequency of occurrence, concentration, and temporal variability of MTBE and other VOCs in source water used by community water systems (CWSs). The investigation was completed in two stages: (1) reviews of available literature and (2) the collection of new data. Two surveys wer

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

    PubMed

    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. PMID:18082954

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

    USGS Publications Warehouse

    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 mg/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 mg/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 mg/L on June 24 and from 0.2 to 0.69 mg/L on September 8. The highest concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) were 0.18, 1.2, 0.18, and 0.97 mg/L, respectively, on June 24. All BTEX concentrations in Cranberry Lake on September 8 were less than 0.2 mg/L. Samples were collected from Lake Lackawanna on September 9. Concentrations of MTBE and TAME ranged from 3.7 to 14.0 mg/L and from 0.17 to 0.38 mg/L, respectively. Like those in Cranberry Lake the previous day, BTEX concentrations were less than 0.2 mg/L, and VOC concentrations and water temperatures were nearly uniform with depth. The mass of MTBE in Lake Lackawanna on September 9 was estimated to be 6 kilograms, which is equal to the amount of MTBE in 21 gallons of gasoline that contains10 percent MTBE by volume. All VOC concentrations were less than 0.2 mg/L in samples collected from Forest Lake on September 8, 1998, and from Stag Pond on the following day. Oxygenated gasoline is used in watercraft on lakes across northern New Jersey. Many of these lakes are surrounded by communities similar to those at Cranberry Lake and at Lake Lackawanna, which depend largely on wells for water supply. Therefore, a regional assessment of the occurrence of these compounds in lakes and ground water is needed to determine the effect of the use of oxygenated gasoline on water quality in lakeside environments throughout northern New Jersey.

  12. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.101 tert -Butyl alcohol. (a) Acidity (as acetic acid). 0.003 percent by weight maximum. (b) Color. Colorless. (c) Distillation range....

  13. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.101 tert -Butyl alcohol. (a) Acidity (as acetic acid). 0.003 percent by weight maximum. (b) Color. Colorless. (c) Distillation range....

  14. Characterization of tertButyl Alcohol Binding to alpha2u-Globulin in F-344 Rats

    Microsoft Academic Search

    T. M. Williams; S. J. Borghoff

    2001-01-01

    tert-Butyl alcohol (TBA) is widely used in the manufacturing of certain perfumes, cosmetics, drugs, paint removers, methyl tert- butyl ether (MTBE), and industrial solvents. In both rodents and humans, TBA is a major metabolite of MTBE, an oxygenated fuel additive. Chronic TBA exposure causes protein droplet nephrop- athy, a2u-globulin (a2u) accumulation, renal cell proliferation, and with chronic exposure, renal tumors

  15. Aerobic biodegradation of tert -butyl alcohol (TBA) by psychro- and thermo-tolerant cultures derived from granular activated carbon (GAC)

    Microsoft Academic Search

    Kimberly M. Reinauer; Yang Zhang; Xiaomin Yang; Kevin T. Finneran

    2008-01-01

    Tert-butyl alcohol (TBA) is a metabolite of methyl tert-butyl ether and is itself possibly a fuel oxygenate. The goals of this study were to enrich and characterize TBA-degrading\\u000a micro-organism(s) from a granular activated carbon (GAC) unit currently treating TBA. The results reported herein describe\\u000a the first aerobic, TBA-degrading cultures derived from GAC. Strains KR1 and YZ1 were enriched from a

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

    USGS Publications Warehouse

    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 water. Use of personal and commercial motorized watercraft on surface-water bodies that are drinking-water sources is probably the reason for the elevated detections of gasoline contaminants relative to ground water. MTBE detections demonstrated a seasonal pattern with more frequent detections in surface water in summer months, which is consistent with seasonal watercraft use.The detection frequency of most VOCs was significantly related to urban land use and population density. Detections of any VOC, non-trihalo-methane compounds, gasoline compounds collectively, the specific gasoline compounds benzene, toluene, ethylbenzene, and xylenes (BTEX), MTBE, solvents, and refrigerants were significantly greater in areas with more than 60 percent urban land use and (or) population density greater than 1,000 people per square mile than in source waters from less urbanized or lower population-density areas. MTBE detections were five times more frequent in source waters from areas with high MTBE use than in source waters from low or no MTBE use, but, unlike other gasoline compounds, MTBE detections were not significantly related to the density of gasoline storage tanks near drinking-water sources.

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

    USGS Publications Warehouse

    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.

  18. Effective Synthesis of tert-Butyl-Substituted 3Carboxy Coumarins in Water Using TEBAC as Catalyst

    Microsoft Academic Search

    Yang Li; Wentao Gao

    2012-01-01

    A facile synthesis of novel tert-butyl substituted 3-carboxycoumarin derivatives is described, featuring the one-pot reaction of tert-butyl substituted salicylaldehydes with Meldrum's acid in water using triethylbenzyl ammonium chloride (TEBAC) as catalyst.

  19. Thermal decomposition of tert-butyl ester of triethylsilylperacetic acid

    Microsoft Academic Search

    T. N. Brevnova; N. S. Vyazankin; A. M. Rabinovich; O. F. Rachkova

    1971-01-01

    A study was made of the decomposition products of the tert-butyl ester of triethylsilylperacetic acid in cumene, n-nonane and tetraethylstannane. In the latter case the processes of generating the free radicals (C2H5)3SiCH2COO and (CH3)3CO, and their subsequent decomposition, are markedly suppressed.

  20. Bromination of tert Butyl Esters of 7?-Chloro and 7-Alkylidenedeacetoxycephalosporanic Acid Sulfones

    Microsoft Academic Search

    M. Vorona; G. Veinberg; I. Turovskis; E. Lukevics

    2005-01-01

    The action of N-bromosuccinimide on tert-butyl esters of 7?-chloro- and 7-alkylidenedeacetoxycephalosporanic acid sulfones upon irradiation with visible light leads to the formation of a mixture of the product of allylic bromination of the 3-methyl group, namely, 3-bromomethyldeacetoxycephalosporanate, and the product of replacement of a proton at C(2) in the latter, namely, 2-bromo-3-bromomethyldeacetoxycephalosporanate. Small amounts of E-isomers were also obtained in

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

    SciTech Connect

    Bradley, P.M.; Landmeyer, J.E.; Chapelle, F.H. [Geological Survey, Columbia, SC (United States)] [Geological Survey, Columbia, SC (United States)

    1999-06-01

    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-{sup 14}C]-MTBE and 84% of [U-{sup 14}C]-TBA were degraded to {sup 14}CO{sub 2} 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.

  2. Tris(tert-butyl)phosphine selenide, the missing link in tris(tert-butyl)phosphine chalcogenide structures (t)Bu(3)P==X (X = O, S, Se, Te).

    PubMed

    Steinberger, H U; Ziemer, B; Meisel, M

    2001-03-01

    In tris(tert-butyl)phosphine selenide, C(12)H(27)PSe, all the methyl ligands are disordered over two sites in the ratio 70/30. The molecule displays crystallographic C(3) symmetry. The bond angles at the P atom are distorted tetrahedral [C--P--C 110.02 (5) degrees and Se==P--C 108.91 (5) degrees ]. The P--C and P==Se bond lengths are 1.908 (1) and 2.1326 (6) A, respectively. A comparison of the structural data of the complete series of tris(tert-butyl)phosphine chalcogenides ((t)Bu(3)PO, (t)Bu(3)PS, (t)Bu(3)PSe and (t)Bu(3)PTe) with the corresponding data of other phosphine chalcogenides substituted by smaller organic groups shows the great influence of the bulky tert-butyl ligands. PMID:11250595

  3. Reactivities of Substituted ?-Phenyl-N-tert-butyl Nitrones

    PubMed Central

    2015-01-01

    In this work, a series of ?-phenyl-N-tert-butyl nitrones bearing one, two, or three substituents on the tert-butyl group was synthesized. Cyclic voltammetry (CV) was used to investigate their electrochemical properties and showed a more pronounced substituent effect for oxidation than for reduction. Rate constants of superoxide radical (O2•–) reactions with nitrones were determined using a UV–vis stopped-flow method, and phenyl radical (Ph•) trapping rate constants were measured by EPR spectroscopy. The effect of N-tert-butyl substitution on the charge density and electron density localization of the nitronyl carbon as well as on the free energies of nitrone reactivity with O2•– and HO2• were computationally rationalized at the PCM/B3LYP/6-31+G**//B3LYP/6-31G* level of theory. Theoretical and experimental data showed that the rates of the reaction correlate with the nitronyl carbon charge density, suggesting a nucleophilic nature of O2•– and Ph• addition to the nitronyl carbon atom. Finally, the substituent effect was investigated in cell cultures exposed to hydrogen peroxide and a correlation between the cell viability and the oxidation potential of the nitrones was observed. Through a combination of computational methodologies and experimental methods, new insights into the reactivity of free radicals with nitrone derivatives have been proposed. PMID:24968285

  4. A novel reusable ionic liquid chemically bonded fused-silica fiber for headspace solid-phase microextraction/gas chromatography-flame ionization detection of methyl tert-butyl ether in a gasoline sample.

    PubMed

    Amini, Ramin; Rouhollahi, Ahmad; Adibi, Mina; Mehdinia, Ali

    2011-01-01

    A novel ionic liquid (IL) bonded fused-sil-ica fiber for headspace solid-phase microextraction (HS-SPME)/gas chromatography-flame ionization detection (GC-FID) of methyl tert-butyl ether (MTBE) in a gasoline sample was prepared and used. The new proposed chemically bonded fiber has better thermal stability and durability than its corresponding physically coated fiber. Another advantage is that no spacer was used for the purpose of bonding the IL to the surface of the fused-silica. The latter advantage makes the preparation of these fibers easier with lower cost than those prepared using sol-gel method. The ionic liquid 1-methyl-3-(3-trimethoxysilyl propyl) imidazolium bis(trifluoromethylsulfonyl) imide was synthesized and cross linked to the surface of the fused-silica fiber. Then, the chemically IL-modified fibers were applied to the headspace extraction of MTBE. The chemically IL-modified fibers showed improved thermal stability at temperatures up to 220 °C relative to the physically IL-modified fibers (180 °C). The chemically bonded IL film on the surface of the fused-silica fiber was durable over 16 headspace extractions without any significant loss of the IL film. The calibration graph was linear in a concentration range of 2-240 ?g L?¹ (R²=0.996) with the detection limit of 0.1 ?g L?¹ level. The reproducibility (RSD %, n=6) of the new IL bonded fused-silica fiber (8.9%) was better than the physically coated fiber (12%) suggesting that the proposed chemically IL-modified fiber is more robust than the physically IL-modified fiber. The optimum extraction conditions were the followings: 40 °C extraction temperature, 12 min extraction time, 30s desorption time and sample agitation at 200 rpm. PMID:21130999

  5. Deprotection of N- tert-butoxycarbonyl (Boc) groups in the presence of tert-butyl esters

    Microsoft Academic Search

    Linus S Lin; Thomas Lanza; Stephen E de Laszlo; Quang Truong; Theodore Kamenecka; William K Hagmann

    2000-01-01

    Deprotection of Boc groups in the presence of tert-butyl esters was achieved by using concentrated H2SO4 (1.5–3.0 equiv.) in tBuOAc or MeSO3H (1.5–3.0 equiv.) in tBuOAc:CH2Cl2 (4:1 v\\/v). The yields ranged from 70 to 100% for a variety of amino acid and dipeptide substrates.

  6. A plan for assessing the occurrence and distribution of methyl tert-butyl ether and other volatile organic compounds in drinking water and ambient ground water in the Northeast and Mid-Atlantic regions of the United States

    USGS Publications Warehouse

    Grady, Stephen J.; Casey, George D.

    1999-01-01

    A plan to assess the occurrence and distribution of methyl tert-butyl ether (MTBE) and other volatile organic compounds (VOCs) in drinking water and ambient ground water in the Northeast and Mid-Atlantic regions of the United States was designed to meet two primary objectives. This study will provide the U.S. Environmental Protection Agency with information on potential human exposure to MTBE and other VOCs from drinking water. In addition, the study will further the goals of the U.S. Geological Survey's (USGS) National Water Quality Assessment Program (NAWQA) by providing additional information on the occurrence and distribution of VOCs in ambient ground water beneath a large, highly urbanized part of the Nation. The study will proceed in two phases-a drinking-water assessment (phase 1) and an ambient ground-water assessment (phase 2). The drinking-water assessment will involve compilation, review, and analysis of available water- quality and ancillary data for approximately 20 percent of the community water systems in 12 States in the Northeast and Mid-Atlantic regions. This effort will summarize the occurrence and distribution of MTBE and other VOCs in drinking water supplied by 2,110 community water systems. The ambient ground-water assessment will involve compilation, review, and analysis of data on MTBE and other VOCs from previous USGS studies in the 12-State area, including regional water-quality assessments conducted for the USGS's NAWQA, plus other available State or local datasets. These data will be related, to the extent allowed by the completeness and quality of the data, to land-use patterns, population density, and other anthropogenic and natural factors using statistical tests. The occurrence and distribution of MTBE and other VOCs in ambient ground water and, to the extent possible, drinking water in relation to such factors, will be evaluated.

  7. 1-[(4-tert-Butyl­phen­yl)sulfon­yl]-1H-benzimidazole

    PubMed Central

    Abdireymov, K. B.; Mukhamedov, N. S.; Okmanov, R. Ya.; Ayimbetov, M. J.; Shakhidoyatov, Kh. M.

    2011-01-01

    The title compound, C17H18N2O2S, was synthesized by aryl­sulfonyl­ation of 1-hy­droxy­methyl-1H-benzimidazole in the presence of triethyl­amine. The benzimidazole and benzene rings form a dihedral angle of 84.1?(1)°. The tert-butyl group was treated as rotationally disordered over two orientations in a 0.51?(2):0.49?(2) ratio. In the crystal, weak inter­molecular C—H?O hydrogen bonds link the mol­ecules into chains propagating in [010]. PMID:21522452

  8. An Effective Synthesis of tert-Butyl-Substituted 3Carboxy Coumarins in Water Using TEBAC as Catalyst

    Microsoft Academic Search

    Yang Li; Wentao Gao

    2011-01-01

    A facile synthesis of novel tert-butyl substituted 3-carboxycoumarin derivatives is described, featuring the one-pot reaction of tert-butyl substituted salicylaldehydes with Meldrum's acid in water using triethylbenzyl ammonium chloride (TEBAC) as catalyst.

  9. Enantiomeric enrichment of ?-amino acid derivatives: recrystallization of N-Fmoc ?-amino acid tert-butyl esters

    Microsoft Academic Search

    Martin J O'Donnell; Francisca Delgado

    2001-01-01

    The optical purity of products derived from enantioselective reactions of the benzophenone imine of glycine tert-butyl esters can often be improved by conversion to the N-Fmoc ?-amino acid tert-butyl esters followed by simple recrystallization.

  10. Azobenzene versus 3,30 -tetra-tert-butyl-azobenzene (TBA)

    E-print Network

    Azobenzene versus 3,30 ,5,50 -tetra-tert-butyl-azobenzene (TBA) at Au(111): characterizing the role-tert-butyl-azobenzene (TBA) adsorbed at Au(111). Particular emphasis is placed on exploring the accuracy of the semi geometry as far as can be judged from the experimental data. Comparing the trans adsorption geometry of TBA

  11. Oxidation of ?-dicarbonyl compounds with tert -butyl hydroperoxide in the presence of vanadyl acetylacetonate

    Microsoft Academic Search

    L. P. Stepovik; M. V. Gulenova; I. A. Kalacheva; A. Yu. Potkina

    2011-01-01

    Oxidation of ?-dicarbonyl compounds with tert-butyl hydroperoxide in the presence of vanadyl acetylacetonate (benzene, 20°C) involves the activated methylene group with\\u000a intermediate formation of trioxo derivatives and is accompanied by decomposition of carbon skeleton. The oxidation products\\u000a are carbon dioxide, carboxylic acids, and tert-butyl and peroxy esters derived from the latter.

  12. Reaction of phenanthrene with tert-butylating agents under Friedel-Craft conditions

    SciTech Connect

    Pozdnyakovich, Yu.V.

    1988-10-20

    The alkylation of phenanthrene with tert-butyl alcohol in the presence of trifluoroacetic acid or with tert-butyl chloride, catalyzed by the TiCl/sub 4/, FeCl/sub 3/-CH/sub 3/NO/sub 2/, and AlCl/sub 3/-CH/sub 3/NO/sub 2/, leads to formation of 2- and 3-tert-butylphenanthrene and also 2,6-, 2,7-, and 3,6-di-tert-butylphenanthrene. The exhaustive alkylation of phenanthrene leads to the formation of the above-mentioned isomeric di-tert-butylphenanthrenes, the ratios of which depend on the nature of the catalyst.

  13. Mobility of solid tert-butyl alcohol studied by deuterium NMR.

    PubMed

    Nishchenko, Alena M; Kolokolov, Daniil I; Stepanov, Alexander G

    2011-07-01

    The molecular mobility of solid deuterated tert-butyl alcohol (TBA) has been studied over a broad temperature range (103–283 K) by means of solid-state 2H NMR spectroscopy, including both line shape and anisotropy of spin–lattice relaxation analyses. It has been found that, while the hydroxyl group of the TBA molecule is immobile on the 2H NMR time scale (?C > 10(–5) s), its butyl group is highly mobile. The mobility is represented by the rotation of the methyl [CD3] groups about their 3-fold axes (C3 rotational axis) and the rotation of the entire butyl [(CD3)3-C] fragment about its 3-fold axis (C3? rotational axis). Numerical simulations of spectra line shapes reveal that the methyl groups and the butyl fragment exhibit three-site jump rotations about their symmetry axes C3 and C3? in the temperature range of 103–133 K, with the activation energies and preexponential factors E1 = 21 ± 2 kJ/mol, k(01) = (2.6 ± 0.5) × 10(12) s(–1) and E2 = 16 ± 2 kJ/mol, k(02) = (1 ± 0.2) × 10(12) s(–1), respectively. Analysis of the anisotropy of spin–lattice relaxation has demonstrated that the reorientation mechanism of the butyl fragment changes to a free diffusion rotational mechanism above 173 K, while the rotational mechanism of the methyl groups remains the same. The values of the activation barriers for both rotations at T > 173 K have the values, which are similar to those at 103–133 K. This indicates that the interaction potential defining these motions remains unchanged. The obtained data demonstrate that the detailed analysis of both line shape and anisotropy of spin–lattice relaxation represents a powerful tool to follow the evolution of the molecular reorientation mechanisms in organic solids. PMID:21627153

  14. Trapping free radicals formed in the reaction of ozone with simple olefins using 2,6-Di-tert-butyl-4-cresol (BHT). [3,3-dimethylbutene

    SciTech Connect

    Pryor, W.A.; Gu, J.; Church, D.F.

    1985-01-25

    Free radicals are detected from the ozonation of a series of olefins using a BHT trapping technique. We have determined the structure of the adduct when 3,3-dimethylbutene (tert-butylethylene) is ozonated at -78/sup 0/C and then warmed in the presence of BHT. The adduct can be rationalized as arising from trapping tert-butylperoxyl radicals by BHT to give 2,6-di-tert-butyl-4-(tert-butylperoxy)-4-methyl-2,5-cyclohexadienone. 17 references, 4 figures, 4 tables.

  15. Trapping free radicals formed in the reaction of ozone with simple olefins using 2,6-Di-tert-butyl-4-cresol (BHT). [3,3-dimethylbutene

    Microsoft Academic Search

    W. A. Pryor; J. Gu; D. F. Church

    1985-01-01

    Free radicals are detected from the ozonation of a series of olefins using a BHT trapping technique. We have determined the structure of the adduct when 3,3-dimethylbutene (tert-butylethylene) is ozonated at -78°C and then warmed in the presence of BHT. The adduct can be rationalized as arising from trapping tert-butylperoxyl radicals by BHT to give 2,6-di-tert-butyl-4-(tert-butylperoxy)-4-methyl-2,5-cyclohexadienone. 17 references, 4 figures,

  16. 2-Oxo-2H-chromen-4-yl 4-tert-butyl­benzoate

    PubMed Central

    Abou, Akoun; Sessouma, Bintou; Djandé, Abdoulaye; Saba, Adama; Kakou-Yao, Rita

    2012-01-01

    In the title mol­ecule, C20H18O4, the three methyl groups of the tert-butyl substituent show rotational disorder. Each methyl group is split over three positions, with refined site-occupation factors of 0.711?(4), 0.146?(3) and 0.144?(4). The benzene ring of the benzoate group is oriented at a dihedral angle of 60.70?(7)° with respect to the planar chromene ring [maximum deviation = 0.046?(2)?Å]. The crystal structure features centrosymmetric R 2 2(8) dimers formed via C—H?O inter­actions, and these dimeric aggregates are connected by C—H?? inter­actions. PMID:22347133

  17. Reaction of perfluoro-tert-butyl carbanion with olefins, containing an activated double bond, and with three-membered heterocycles and various halo derivatives

    Microsoft Academic Search

    N. I. Delyagina; E. Ya. Pervova; I. L. Knunyants

    1972-01-01

    1.The alkylation of the perfluoro-tert-butyl carbanion with acrylonitrile and the esters of acrylic acid is a convenient method for the preparation ofß-(perfluoro-tert-butyl)propionic acid derivatives.2.The alkylation of the perfluoro-tert-butyl carbanion with ethylene oxide gaveß-(perfluoro-tert-butyl) ethanol.3.The alkylation of the perfluoro-tert-butyl carbanion with ethylene thiooxide gaveß-(perfluoro-tert-butyl)ethyl perfluoroisobutenyl sulfide and the bis-[ß-(perfluoro-tert-butyl)ethyl] dithioacetal of hexa-fluorodimethylketone.4.The reaction of perfluoroisobutylene with halo derivatives in the presence

  18. Hydrogen Atom Reactivity toward Aqueous tert-Butyl Alcohol

    SciTech Connect

    Lymar S. V.; Schwarz, H.A.

    2012-02-09

    Through a combination of pulse radiolysis, purification, and analysis techniques, the rate constant for the H + (CH{sub 3}){sub 3}COH {yields} H{sub 2} + {sm_bullet}CH{sub 2}C(CH{sub 3}){sub 2}OH reaction in aqueous solution is definitively determined to be (1.0 {+-} 0.15) x 10{sup 5} M{sup -1} s{sup -1}, which is about half of the tabulated number and 10 times lower than the more recently suggested revision. Our value fits on the Polanyi-type, rate-enthalpy linear correlation ln(k/n) = (0.80 {+-} 0.05){Delta}H + (3.2 {+-} 0.8) that is found for the analogous reactions of other aqueous aliphatic alcohols with n equivalent abstractable H atoms. The existence of such a correlation and its large slope are interpreted as an indication of the mechanistic similarity of the H atom abstraction from {alpha}- and {beta}-carbon atoms in alcohols occurring through the late, product-like transition state. tert-Butyl alcohol is commonly contaminated by much more reactive secondary and primary alcohols (2-propanol, 2-butanol, ethanol, and methanol), whose content can be sufficient for nearly quantitative scavenging of the H atoms, skewing the H atom reactivity pattern, and explaining the disparity of the literature data on the H + (CH{sub 3}){sub 3}COH rate constant. The ubiquitous use of tert-butyl alcohol in pulse radiolysis for investigating H atom reactivity and the results of this work suggest that many other previously reported rate constants for the H atom, particularly the smaller ones, may be in jeopardy.

  19. Synthesis and cytotoxic activity of derivatives of 6 Z -acetylmethylenepenicillanic acid tert -butyl ester

    Microsoft Academic Search

    M. Vorona; I. Potorochina; G. Veinberg; S. Belyakov; I. Shestakova; I. Kanepe; E. Lukevics

    2009-01-01

    The sulfoxide of 6Z-[2-(methoxyimino)propylidene]penicillanic acid tert-butyl ester and the sulfones of 6Z-[2-(hydroxyimino-, methoxyimino-, benzyloxyimino-, 2-bromo- and 4-bromobenzyloxyimino)-propylidene]penicillanic acid in the\\u000a syn and anti forms have been synthesized by the condensation of the sulfoxide and sulfone of 6Z-acetylmethylenepenicillanic acid tert-butyl ester with hydroxylamine, methoxyamine, benzyloxyamine, 2-bromo- and 4-bromobenzyloxyamines. The syn and anti isomers\\u000a of 3Z-(2-methoxyiminopropylidene)-4R-(benzothiazolyl-2-dithio)-2-oxoazetidinyl-1R-(2-propenyl)acetic acid tert-butyl ester were obtained by

  20. Crystal structure of 1,2-bis­[(2-tert-butyl­phen­yl)imino]­ethane

    PubMed Central

    Silvino, Alexandre C.; Torres, Juliana M.

    2015-01-01

    The whole molecule of the title compound, C22H28N2, (I), is generated by inversion symmetry. The mol­ecule is rather similar to that of 2,3-bis­[(2-tert-butyl­phen­yl)imino]­butane, (II), a di­imine ligand comprising similar structural features [Ferreira et al. (2006 ?). Acta Cryst. E62, o4282–o4284]. Both ligands crystallize with the –N=C(R)—C(R)=N– group around an inversion centre, in a trans configuration. Comparing the two structures, it may be noted that the independent planar groups in both mol­ecules [the central link, –N=C(R)—C(R)=N–, and the terminal aromatic ring] subtend an angle of 69.6?(1)° in (II) and 49.4?(2)° in (I). Ferreira and co-workers proposed that such angle deviation may be ascribed to the presence of two non-classical intra­molecular hydrogen bonds and steric factors. In fact, in (I), similar non-classical hydrogen bonds are observed, and the larger angular deviation in (II) may be assigned to the presence of methyl groups in the di­imino fragment, which can cause steric hindrance due to the presence of bulky tert-butyl substituents in the aromatic rings. The C=N bond lengths are similar in both compounds and agree with comonly accepted values.

  1. Crystal structure of 1,2-bis-[(2-tert-butyl-phen-yl)imino]-ethane.

    PubMed

    Silvino, Alexandre C; Torres, Juliana M

    2015-06-01

    The whole molecule of the title compound, C22H28N2, (I), is generated by inversion symmetry. The mol-ecule is rather similar to that of 2,3-bis-[(2-tert-butyl-phen-yl)imino]-butane, (II), a di-imine ligand comprising similar structural features [Ferreira et al. (2006 ?). Acta Cryst. E62, o4282-o4284]. Both ligands crystallize with the -N=C(R)-C(R)=N- group around an inversion centre, in a trans configuration. Comparing the two structures, it may be noted that the independent planar groups in both mol-ecules [the central link, -N=C(R)-C(R)=N-, and the terminal aromatic ring] subtend an angle of 69.6?(1)° in (II) and 49.4?(2)° in (I). Ferreira and co-workers proposed that such angle deviation may be ascribed to the presence of two non-classical intra-molecular hydrogen bonds and steric factors. In fact, in (I), similar non-classical hydrogen bonds are observed, and the larger angular deviation in (II) may be assigned to the presence of methyl groups in the di-imino fragment, which can cause steric hindrance due to the presence of bulky tert-butyl substituents in the aromatic rings. The C=N bond lengths are similar in both compounds and agree with comonly accepted values. PMID:26090180

  2. The tert-butyl cation on zeolite Y: A theoretical and experimental study

    NASA Astrophysics Data System (ADS)

    Rosenbach, Nilton, Jr.; dos Santos, Alex P. A.; Franco, Marcelo; Mota, Claudio J. A.

    2010-01-01

    The structure and energy of the tert-butyl cation on zeolite Y were calculated at ONIOM(MP2(FULL)/6-31G( d, p):MNDO) level. The results indicated that the tert-butyl cation is a minimum and lies between 40 and 51 kJ mol -1 above in energy to the tert-butoxide, depending on the level of calculation. Both species are stabilized through hydrogen bonding interactions with the framework oxygen atoms. Experimental data of nucleophilic substitution of tert-butylchloride and bromide over NaY impregnated with NaCl or NaBr give additional support for the formation of the tert-butyl cation as a discrete intermediate on zeolite Y, in agreement with the calculations.

  3. Decomposition mechanism of the tert-butyl esters of carboxylic acids

    Microsoft Academic Search

    V. G. Avakyan; A. D. Litmanovich; V. O. Cherkezyan

    1984-01-01

    1.It has been shown by quantum-chemical calculations that the monomolecular decomposition of tert-butyl esters ot carboxylic acids, which involves the detachment of isobutylene, takes place as the result of the transfer of a proton from the closest CH3 group of the tert-butyl substituent to the carbonyl O atom.2.The catalytic action of carboxylic acids on this reaction is exhibited by the

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

    EPA Science Inventory

    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,...

  5. 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

    USGS Publications Warehouse

    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 Lackawanna in summer 1999;concentrations ranged from 0.05 to 0.19 ug/L. Lake/ground water interaction is a feasible explanation for the nearly ubiquitous presence of MTBE in ground water. The movement of water from lakes to wells is feasible because many static water levels and essentially all pumped water levels in the wells were below lake levels. Furthermore, diatom fragments were present in samples from the wells. Ambient ground water at Cranberry Lake also may be affected by septic-tank effluent, as indicated by the relation among concentrations of nitrate, boron, and chloroform. This result indicates potential vulnerability of the water supply to contamination by other chemicals and pathogens. Radon in ambient ground water is a concern throughout northern New Jersey. In particular, the median radon concentrations in ground-water samples collected from 14 wells at Cranberry Lake in 1998 and 1999 were 1,282 and 1,046 pCi/L, respectively. The median radon concentration in five ground-water samples collected at Lake Lackawanna in 1999 was 340 pCi/L. Although these values exceed regulatory levels, they are not high relative to radon concentrations measured in northwestern New Jersey. Eight wells in a neighborhood of Cranberry Lake with known MTBE contamination were sampled by the U.S. Geological Survey in summer 1998. MTBE was detected at concentrations greater than or equal to 40 ug/L in five of the wells. Concentrations of TAME, another gasoline oxygenate, were highly correlated with concentrations of MTBE; MTBE concentrations were about 10 times the TAME concentrations. In all samples, however, the concentrations of the BTEX compounds were less than 0.05 ug/L, and the sample from the most highly contaminated well, where the MTBE concentration was 900 ug/L, had no detectable BTEX.

  6. Occurrence and distribution of methyl tert-butyl ether and other volatile organic compounds in drinking water in the Northeast and Mid-Atlantic regions of the United States, 1993-98

    USGS Publications Warehouse

    Grady, S.J.; Casey, G.D.

    2001-01-01

    Data on volatile organic compounds (VOCs) in drinking water supplied by 2,110 randomly selected community water systems (CWSs) in 12 Northeast and Mid-Atlantic States indicate 64 VOC analytes were detected at least once during 1993-98. Selection of the 2,110 CWSs inventoried for this study targeted 20 percent of the 10,479 active CWSs in the region and represented a random subset of the total distribution by State, source of water, and size of system. The data include 21,635 analyses of drinking water collected for compliance monitoring under the Safe Drinking Water Act; the data mostly represent finished drinking water collected at the pointof- entry to, or at more distal locations within, each CWS?s distribution system following any watertreatment processes. VOC detections were more common in drinking water supplied by large systems (serving more than 3,300 people) that tap surface-water sources or both surface- and groundwater sources than in small systems supplied exclusively by ground-water sources. Trihalomethane (THM) compounds, which are potentially formed during the process of disinfecting drinking water with chlorine, were detected in 45 percent of the randomly selected CWSs. Chloroform was the most frequently detected THM, reported in 39 percent of the CWSs. The gasoline additive methyl tert-butyl ether (MTBE) was the most frequently detected VOC in drinking water after the THMs. MTBE was detected in 8.9 percent of the 1,194 randomly selected CWSs that analyzed samples for MTBE at any reporting level, and it was detected in 7.8 percent of the 1,074 CWSs that provided MTBE data at the 1.0-?g/L (microgram per liter) reporting level. As with other VOCs reported in drinking water, most MTBE concentrations were less than 5.0 ?g/L, and less than 1 percent of CWSs reported MTBE concentrations at or above the 20.0-?g/L lower limit recommended by the U.S. Environmental Protection Agency?s Drinking-Water Advisory. The frequency of MTBE detections in drinking water is significantly related to high- MTBE-use patterns. Detections are five times more likely in areas where MTBE is or has been used in gasoline at greater than 5 percent by volume as part of the oxygenated or reformulated (OXY/RFG) fuels program. Detection frequencies of the individual gasoline compounds (benzene, toluene, ethylbenzene, and xylenes (BTEX)) were mostly less than 3 percent of the randomly selected CWSs, but collectively, BTEX compounds were detected in 8.4 percent of CWSs. BTEX concentrations also were low and just three drinkingwater samples contained BTEX at concentrations exceeding 20 ?g/L. Co-occurrence of MTBE and BTEX was rare, and only 0.8 percent of CWSs reported simultaneous detections of MTBE and BTEX compounds. Low concentrations and cooccurrence of MTBE and BTEX indicate most gasoline contaminants in drinking water probably represent nonpoint sources. Solvents were frequently detected in drinking water in the 12-State area. One or more of 27 individual solvent VOCs were detected at any reporting level in 3,080 drinking-water samples from 304 randomly selected CWSs (14 percent) and in 206 CWSs (9.8 percent) at concentrations at or above 1.0 ?g/L. High co-occurrence among solvents probably reflects common sources and the presence of transformation by-products. Other VOCs were relatively rarely detected in drinking water in the 12-State area. Six percent (127) of the 2,110 randomly selected CWSs reported concentrations of 16 VOCs at or above drinking-water criteria. The 127 CWSs collectively serve 2.6 million people. The occurrence of VOCs in drinking water was significantly associated (p<0.0001) with high population- density urban areas. New Jersey, Massachusetts, and Rhode Island, States with substantial urbanization and high population density, had the highest frequency of VOC detections among the 12 States. More than two-thirds of the randomly selected CWSs in New Jersey reported detecting VOC concentrations in drinking water at or above 1

  7. Solvent-controlled chemoselective palladium-catalyzed oligomerization of tert-butyl acetylene

    Microsoft Academic Search

    Jin-Sheng Cheng; Guo-Feng Wei; Shi-Wen Huang; Jin-Zhao; Huan-Feng Jiang

    2007-01-01

    A solvent-controlled chemoselective palladium-catalyzed oligomerization of tert-butyl acetylene was reported in this paper. The reaction was carried out smoothly in benzene\\/n-BuOH binary solvents system. When benzene, unpolar aprotic solvent, became preponderating in the binary solvents system, a cyclotrimerization process occurred to produce 1,3,5-tri-tert-butylbenzene via a mechanism of three acetylene molecular to insert step by step forming ?-butadienyl-Pd and ?-hexatrienyl-Pd intermediates,

  8. Regioisomer-Free C 4h ?-Tetrakis(tert-butyl)metallo-phthalocyanines: Regioselective Synthesis and Spectral Investigations.

    PubMed

    Iida, Norihito; Tanaka, Kenta; Tokunaga, Etsuko; Takahashi, Hiromi; Shibata, Norio

    2015-04-01

    Metal ?-tetrakis(tert-butyl)phthalocyanines are the most commonly used phthalocyanines due to their high solubility, stability, and accessibility. They are commonly used as a mixture of four regioisomers, which arise due to the tert-butyl substituent on the ?-position, and to the best of our knowledge, their regioselective synthesis has yet to be reported. Herein, the C 4h -selective synthesis of ?-tetrakis(tert-butyl)metallophthalocyanines is disclosed. Using tetramerization of ?-trialkylsilyl phthalonitriles with metal salts following acid-mediated desilylation, the desired metallophthalocyanines were obtained in good yields. Upon investigation of regioisomer-free zinc ?-tetrakis(tert-butyl)phthalocyanine using spectroscopy, the C 4h single isomer described here was found to be distinct in the solid state to zinc ?-tetrakis(tert-butyl)phthalocyanine obtained by a conventional method. PMID:25969805

  9. Methyl Tertiary Butyl Ether (MTBE): Drinking Water

    NSDL National Science Digital Library

    MTBE, a gasoline oxygenater additive, has been detected in ground water sources throughout different parts of the country. These ground water sources are often the source of drinking water, and the presence of methyl tertiary butyl ether in even minute quantities can make the water undrinkable. Research to date has not conclusively identified any quantitative level at which serious health risks may occur. This site provides information on behalf of the Environmental Protection Agency on the concerns and occurence of MTBE in drinking water.

  10. The Alkyl tert-Butyl Ether Intermediate 2-Hydroxyisobutyrate Is Degraded via a Novel Cobalamin-Dependent Mutase Pathway†

    PubMed Central

    Rohwerder, Thore; Breuer, Uta; Benndorf, Dirk; Lechner, Ute; Müller, Roland H.

    2006-01-01

    Fuel oxygenates such as methyl and ethyl tert-butyl ether (MTBE and ETBE, respectively) are degraded only by a limited number of bacterial strains. The aerobic pathway is generally thought to run via tert-butyl alcohol (TBA) and 2-hydroxyisobutyrate (2-HIBA), whereas further steps are unclear. We have now demonstrated for the newly isolated ?-proteobacterial strains L108 and L10, as well as for the closely related strain CIP I-2052, that 2-HIBA was degraded by a cobalamin-dependent enzymatic step. In these strains, growth on substrates containing the tert-butyl moiety, such as MTBE, TBA, and 2-HIBA, was strictly dependent on cobalt, which could be replaced by cobalamin. Tandem mass spectrometry identified a 2-HIBA-induced protein with high similarity to a peptide whose gene sequence was found in the finished genome of the MTBE-degrading strain Methylibium petroleiphilum PM1. Alignment analysis identified it as the small subunit of isobutyryl-coenzyme A (CoA) mutase (ICM; EC 5.4.99.13), which is a cobalamin-containing carbon skeleton-rearranging enzyme, originally described only in Streptomyces spp. Sequencing of the genes of both ICM subunits from strain L108 revealed nearly 100% identity with the corresponding peptide sequences from M. petroleiphilum PM1, suggesting a horizontal gene transfer event to have occurred between these strains. Enzyme activity was demonstrated in crude extracts of induced cells of strains L108 and L10, transforming 2-HIBA into 3-hydroxybutyrate in the presence of CoA and ATP. The physiological and evolutionary aspects of this novel pathway involved in MTBE and ETBE metabolism are discussed. PMID:16751524

  11. Methyl Tertiary Butyl Ether (MTBE) Groundwater Contamination

    NSDL National Science Digital Library

    Methyl tertiary-butyl ether (MTBE), a fuel additive, is highly mobile in groundwater, dissolving and traveling faster than the other petroleum constituents which tend to biodegrade and adsorb to soil particles. This unit will introduce the problem of pollutants as they move through the various soil layers and contaminate the groundwater and challenge the students to investigate the effects of MTBE spills in the environment by researching the available literature on fuel oxygenates and learning their mode of transport through the soil. Experimentally determined data, obtained in lab activities, will facilitate building models of the contamination process of the groundwater. Mathematics modeling will involve the use of spreadsheet analysis of real-world-data obtained online.

  12. Neuroprotection by 2-h Postischemia Administration of Two Free Radical Scavengers, ?-phenyl- n-tert-butyl-nitrone (PBN) and N-tert-butyl-(2-sulfophenyl)-nitrone (S-PBN), in Rats Subjected to Focal Embolic Cerebral Ischemia

    Microsoft Academic Search

    Yi Yang; Qiu Li; Ashfaq Shuaib

    2000-01-01

    Oxygen free radical generation may have important secondary damaging effects after the onset of cerebral ischemia. Free radical scavengers have been used successfully in attenuating neuronal damage in the reperfusion period in transient forebrain ischemia. There are limited data on effectiveness in models of focal ischemia. Two free radical scavengers, ?-phenyl-n-tert-butyl-nitrone (PBN) and N-tert-butyl-(2-sulfophenyl)-nitrone (S-PBN), have been shown to reduce

  13. Conformation of the piperidine ring. Part IV. Investigations of 4-tert-butyl-4-hydroxy-2,2,6,6-tetramethylpiperidine derivatives *

    NASA Astrophysics Data System (ADS)

    Cygler, M.; Markowicz, T.; Skolimowski, J.; Skowro?ski, R.

    1980-11-01

    Methods of synthesis of 4-tert-butyl-4-hydroxy-2,2,6,6-tetramethylpiperidine(1), 4-tert-butyl-4-hydroxy-1,2,2,6,6-pentamethylpiperidine (2) and 4-tert-butyl-4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl( 3) are described. Interaction of the axial hydroxyl group with axial methyl groups in a chair form of these compounds causes a downfield shift of the methyl proton NMR signal of about 0.2 ppm. IR spectra of 1 and 2 indicate a considerable contribution in solution of non-chair forms stabilized by intramolecular hydrogen bonds. In 3 only intermolecular hydrogen bonds were found. The crystal and molecular structure of 2 have been determined by direct methods and refined to R = 0.0468. The molecules exist in the solid state in a chair conformation only. Van der Waals interactions of bulky substituents hinder a close approach of neighbouring molecules necessary for the formation of intermolecular hydrogen bonds.

  14. Novel solvent-controlled chemoselective palladium\\/copper(II) halide catalyzed oligomerization of tert -butyl acetylene

    Microsoft Academic Search

    Jin-Sheng Cheng; Guo-Feng Wei; Zu-Liang Huang

    2007-01-01

    Solvent-controlled chemoselective palladium-catalyzed oligomerization of tert-butyl acetylene is reported in this paper. The reaction was carried out smoothly in benzene\\/n-BuOH binary solvent system. When unpolar aprotic benzene was the preponderating component in the binary system, a cyclotrimerization\\u000a process occurred to produce 1,3,5-tri-tert-butylbenzene via a mechanism of three acetylene molecules, inserted step by step, forming ?-butadienyl-Pd and ?-hexatrienyl-Pd intermediates. While when

  15. Identification of tert-Butyl Cations in Zeolite H-ZSM-5: Evidence from NMR Spectroscopy and DFT Calculations.

    PubMed

    Dai, Weili; Wang, Chuanming; Yi, Xianfeng; Zheng, Anmin; Li, Landong; Wu, Guangjun; Guan, Naijia; Xie, Zaiku; Dyballa, Michael; Hunger, Michael

    2015-07-20

    Experimental evidence for the presence of tert-butyl cations, which are important intermediates in acid-catalyzed heterogeneous reactions, on solid acids has still not been provided to date. By combining density functional theory (DFT) calculations with (1) H/(13) C magic-angle-spinning NMR spectroscopy, the tert-butyl cation was successfully identified on zeolite H-ZSM-5 upon conversion of isobutene by capturing this intermediate with ammonia. PMID:26096840

  16. Efficient large (ca. 40 g) laboratory scale preparation of ( S)- and ( R)-valine tert-butyl esters

    Microsoft Academic Search

    Victor P. Krasnov; Galina L. Levit; Iraida M. Bukrina; Alexander M. Demin; Oleg N. Chupakhin; Ji Uk Yoo

    2002-01-01

    A large laboratory scale (ca. 40 g) method for the preparation of enantiomerically pure (S)- and (R)-valine tert-butyl esters has been developed. The method involves three steps: preparation of N-TFA-valines, preparation of valine tert-butyl esters using 2-methylpropene in dioxane in the presence of sulfuric acid, and isolation of the target compounds as the acetate derivative. The overall yield is up

  17. Atomic Force Microscopy Based Thermal Lithography of Poly(tert-butyl acrylate) Block Copolymer Films for Bioconjugation

    Microsoft Academic Search

    Joost Duvigneau; Holger Schönherr; G. Julius Vancso

    2008-01-01

    In this paper, we report on the local thermal activation of thin polymer films for area-selective surface chemical modification on micrometer and nanometer length scales. The thermally induced activation of tert-butyl ester moieties in polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) block copolymer films leads to the formation of pending carboxylic acid groups, which are among the versatile functionalities for subsequent bioconjugation. From Fourier

  18. Kinetics of the acid-catalyzed acylation of tert-butyl hydroperoxide by acetic and caproic acids

    Microsoft Academic Search

    V. L. Antonovskii; O. K. Yanaeva

    1981-01-01

    Conclusions 1.Formation of a peroxy ester from tert-butyl hydroperoxide and caproic acid proceeds through rupture of the H-OO bond.2.Rate constants for the formation of peroxy exters from tert-butyl hydroperoxide and acetic and caproic acids in the presence of mineral acids have been determined as a function of the acidity. These relations are explained in terms of the limiting step in

  19. 27 CFR 21.118 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.118 Methyl n -butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color. Colorless. (c) Odor. Characteristic...

  20. 27 CFR 21.118 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.118 Methyl n -butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color. Colorless. (c) Odor. Characteristic...

  1. 27 CFR 21.118 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.118 Methyl n -butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color. Colorless. (c) Odor. Characteristic...

  2. 27 CFR 21.118 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.118 Methyl n -butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color. Colorless. (c) Odor. Characteristic...

  3. Modulatory effect of cyclosporin A on tert-butyl hydroperoxide-induced oxidative damage in hepatocytes.

    PubMed

    Kmonícková, E; Drahota, Z; Kameníková, L; Cervinková, Z; Masek, K; Farghali, H

    2001-02-01

    In the present work, we followed an in vitro protective action of cyclosporin A (CsA) against tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in hepatocytes. Various parameters (cell viability, cytosolic calcium level, rhodamine 123 accumulation as indicator of mitochondrial membrane potential and alanine-aminotransferase leakage from cells) were measured as an index of cytotoxicity. Tert-butyl hydroperoxide (1 mM) significantly increased cytosolic Ca2+ and affected mitochondrial membrane potential. Pretreatment with cyclosporin A (0.5 microM) reduced t-BHP-induced cytosolic Ca2+ increase and ALT (alanine-aminotransferase) leakage, but had no protective effect on t-BHP-induced changes of mitochondrial membrane potential. Our data thus suggest that the mechanism of cytoprotection of CsA on the cytosolic Ca2+ changes and ALT leakage induced by t-BHP, does not directly correlate with protection of t-BHP-induced changes of mitochondrial membrane potential. PMID:11322648

  4. Palladium-catalyzed carbonylation of tert-butyl alcohol to esters of iso-valeric acid

    Microsoft Academic Search

    Hongying Zhou; Shijie Lu; Hongqi Li; Jing Chen; Hongxiang Fu; Hanqing Wang

    1997-01-01

    Tert-butyl alcohol was carbonylated to esters of iso-valeric acid in the presence of a tris(dibenzylideneacetone)dipalladium(0)–triphenylphosphine–p-Ts catalytic system without any halogen promoter or other extreme conditions. Typical reaction conditions are: temperature 120–160°C; p(CO)=4.0–7.0 MPa; tert-butyl alcohol\\/ROH\\/Pd=400\\/3280\\/1; [Pd]=4.3×10?3 mol\\/l; Pd\\/PPh3\\/p-Ts=1\\/24\\/65; reaction time 6–24 h. Under these experimental conditions a high yield (98.9%) and selectivity (99.2%) for esters are obtained. The carbonylation of

  5. Thermal radiation of di-tert-butyl peroxide pool fires—Experimental investigation and CFD simulation

    Microsoft Academic Search

    Hyunjoo Chun; Klaus-Dieter Wehrstedt; Iris Vela; Axel Schönbucher

    2009-01-01

    Instantaneous and time averaged flame temperatures T¯, surface emissive power SEP¯ and time averaged irradiances E¯ of di-tert-butyl peroxide (DTBP) pool fires with d=1.12 and 3.4m are investigated experimentally and by CFD simulation. Predicted centerline temperature profiles for d=1.12m are in good agreement with the experimental emission temperature profiles for x\\/d>0.9. For d=3.4m the CFD predicted maximum centerline temperature at

  6. Microbial adaptation to biodegradation of tert-butyl alcohol in a sequencing batch reactor

    Microsoft Academic Search

    Wei-Qin Zhuang; Joo-Hwa Tay; Shan Yi; Stephen Tiong-Lee Tay

    2005-01-01

    This study demonstrates the utility of the sequencing batch reactor (SBR) to adapt microorganisms towards biological removal of tert-butyl alcohol (TBA). The reactor was inoculated with activated sludge and fed with TBA as the sole carbon source. Start-of-cycle TBA concentrations were initially set at 100mgL?1 with a cycle time of 24h and a volumetric exchange ratio of 50% to maintain

  7. Copolymers from tert-butyl methacrylate and 2-propenyl isocyanate—polymers for photoresist application

    Microsoft Academic Search

    Jens Ferbitz; Werner Mormann

    2003-01-01

    Free radical copolymerisation of tert-butyl methacrylate (1) with 2-isopropenyl isocyanate (2) has been investigated. Reactivity ratios of r1=3.48±0.60 for 1 and r2=0.004±0.04 for 2 were obtained. As 2-propenyl isocyanate has almost no tendency to homopolymerise maximum isocyanate content is reached in an alternating copolymer. The reaction of the isocyanate functionality with morpholine was used to obtain compounds for determination of

  8. Protective effect of Hibiscus anthocyanins against tert-butyl hydroperoxide-induced hepatic toxicity in rats

    Microsoft Academic Search

    Chau-Jong Wang; Jin-Ming Wang; Wea-Lung Lin; Chia-Yih Chu; Fen-Pi Chou; Tsui-Hwa Tseng

    2000-01-01

    Hibiscus anthocyanins (HAs), a group of natural pigments occurring in the dried flowers of Hibiscus sabdariffa L., which is a local soft drink material and medical herb, were studied for antioxidant bioactivity. The preliminary study showed that HAs were able to quench the free radicals of 1,1-diphenyl-2-picrylhydrazyl. This antioxidant bioactivitiy was further evaluated using the model of tert-butyl hydroperoxide (t-BHP)-induced

  9. Activation of carboxylic acids as their active esters by means of tert-butyl 3-(3,4-dihydrobenzotriazine-4-on)yl carbonate

    Microsoft Academic Search

    Yochai Basel; Alfred Hassner

    2002-01-01

    Carboxylic acids were activated in the presence of DMAP with tert-butyl carbonates (BOC-OX) 1, which were prepared in situ by reaction of X-OH and di-tert-butyl dicarbonate (BOC2O). The most efficient active carbonate proved to be tert-butyl 3-(3,4-dihydrobenzotriazine-4-on)yl carbonate 1a, leading to efficient formation of benzotriazinonyl esters 3 and 6, which are intermediates in reactions with primary and secondary amines to

  10. The metabolism of di-(3,5-di-tert.-butyl-4-hydroxybenzyl) ether (Ionox 201) in the rat

    PubMed Central

    Wright, A. S.; Crowne, R. S.; Hathway, D. E.

    1967-01-01

    1. Up to one-third of a single oral dose of Ionox 201 was absorbed in rats. 2. In rats dosed with [14C]Ionox 201 86·8–97·2% of the label is excreted in the faeces in 24 days (much of this is eliminated in the first 4 days after dosage), 5·6% in the urine and not more than 0·8% in the exhaled air; 5·0% of 14C is present in the carcass and viscera after removal of the gut, and most of this is in the fatty tissues. 3. About 65·0% of 14C in the faeces is due to unchanged antioxidant, 30·0% to 3,5-di-tert.-butyl-4-hydroxybenzoic acid, 3·5% to unidentified polar constituent(s), 1·4% to 3,5-di-tert.-butyl-4-hydroxybenzaldehyde and 0·1% to 3,3?,5,5?-tetra-tert.-butyl-4-,4?-stilbenequinone. A variable proportion of 14C in the urine is due to 3,5-di-tert.-butyl-4-hydroxybenzoic acid (40–60%) and the remainder (60–40%) to the ester glucuronide, when the animals were treated with different doses of antioxidant. In eight individual animals dosed with 6·78mg. of [14C]Ionox 201, one-third of 14C in the bile is due to the free acid, 45% to the ester glucuronide, 20% to an unidentified constituent and 2% to unchanged antioxidant, and, in two animals dosed with 13·56mg., there is a small proportion of free acid and a larger proportion of ester glucuronide. About 80% of 14C in the body fat is due to unchanged antioxidant, 19% to the free acid and 1% to 3,5-di-tert.-butyl-4-hydroxybenzaldehyde. 4. At least 36·2% of a single oral dose of Ionox 201 is metabolized: 3,5-di-tert.-butyl-4-hydroxybenzoic acid accounts for 30·2% of a dose, (3,5-di-tert.-butyl-4-hydroxybenzoyl ?-d-glucopyranosid)uronic acid for 1·4%, 3,5-di-tert.-butyl-4-hydroxybenzaldehyde for 1·3%, 3,3?,5,5?-tetra-tert.-butyl-4,4?-stilbenequinone for 0·1% and unidentified polar metabolite(s) for 3·2%. 5. The metabolism of Ionox 201 in vivo is closely related to its antioxidant action in vitro. PMID:6030293

  11. Methotrexate analogues. 25. Chemical and biological studies on the gamma-tert-butyl esters of methotrexate and aminopterin.

    PubMed

    Rosowsky, A; Freisheim, J H; Bader, H; Forsch, R A; Susten, S S; Cucchi, C A; Frei, E

    1985-05-01

    gamma-tert-Butylaminopterin (gamma-tBAMT), the first example of an aminopterin (AMT) gamma-monoester, was synthesized, and new routes to the known N10-methyl analogue gamma-tert-butyl methotrexate (gamma-tBMTX) were developed. The inhibitory effects of gamma-tBAMT on the activity of purified dihydrofolate reductase (DHFR) from L1210 murine leukemia cells, the growth of L1210 cells and CEM human leukemic lymphoblasts in suspension culture, and the growth of several lines of human squamous cell carcinoma of the head and neck in monolayer culture were compared with the effects of gamma-tBMTX and the parent acids AMT and methotrexate (MTX). Patterns of cross-resistance to gamma-tBAMT, gamma-tBMTX, and AMT among several MTX-resistant cell lines were examined. In vivo antitumor activities of gamma-tBAMT and gamma-tBMTX were compared in mice with L1210 leukemia. While the activity of gamma-tBAMT was very close to that of gamma-tBMTX in the DHFR inhibition assay, the AMT ester was more potent than the MTX ester against cells in culture and against L1210 leukemia in vivo. Only partial cross-resistance was shown against gamma-tBMTX and gamma-tBAMT in cultured cells that were resistant to MTX by virtue of a transport defect or a combination of defective transport and elevated DHFR activity. PMID:3872941

  12. Characterization of tert-butyl alcohol binding to alpha2u-globulin in F-344 rats.

    PubMed

    Williams, T M; Borghoff, S J

    2001-08-01

    tert-Butyl alcohol (TBA) is widely used in the manufacturing of certain perfumes, cosmetics, drugs, paint removers, methyl tert-butyl ether (MTBE), and industrial solvents. In both rodents and humans, TBA is a major metabolite of MTBE, an oxygenated fuel additive. Chronic TBA exposure causes protein droplet nephropathy, alpha2u-globulin (alpha2u) accumulation, renal cell proliferation, and with chronic exposure, renal tumors in male, but not female, rats. These effects suggest an alpha2u-mediated mechanism for renal tumors. The objective of the present study was to determine whether TBA or its metabolites bind to alpha2u. Mature male and female F-344 rats were administered a single gavage dose of 500 mg/kg TBA, 500 mg/kg (14)C-TBA, or corn oil. TBA equivalents/gram or ml of tissue in the male rat kidney, liver, and blood were higher than the levels measured in female rat tissue 12 h after (14)C-TBA administration. Gel filtration and anion-exchange chromatography demonstrated that (14)C-TBA-derived radioactivity co-eluted with alpha2u from male kidney cytosol. Protein dialysis studies demonstrated that the interaction between (14)C-TBA-derived radioactivity and alpha2u was reversible. Incubations of the low-molecular-weight protein fraction (LMWPF) isolated from (14)C-TBA-treated male rat kidneys with d-limonene oxide (a chemical with a high affinity to alpha2u) demonstrated that (14)C-TBA-derived radioactivity was displaced. Gas chromatography-mass spectrometry analysis confirmed that TBA was present in this LMWPF fraction. These results demonstrate that TBA interacts with alpha2u, which explains the accumulation of alpha2u in the male rat kidney following TBA exposure. PMID:11452135

  13. Molecular Dynamics and Partitioning of Di tert -butyl Nitroxide in Stratum Corneum Membranes: Effect of Terpenes

    Microsoft Academic Search

    Heverton Silva Camargos; Adolfo Henrique Moraes Silva; Jorge Luiz Vieira Anjos; Antonio Alonso

    2010-01-01

    In this work, we have used electron paramagnetic resonance (EPR) spectroscopy of the small spin label di-tert-butyl nitroxide (DTBN), which partitions the aqueous and hydrocarbon phases, to study the interaction of the terpenes ?-terpineol,\\u000a 1,8-cineole, l(?)-carvone and (+)-limonene with the uppermost skin layer, the stratum corneum, and the membrane models of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The EPR spectra indicated

  14. The Epoxidation of 2,5-Di-tert-butyl-1,4-benzoquinone: A Consecutive Reaction for the Physical Chemistry Laboratory.

    ERIC Educational Resources Information Center

    Hairfield, E. M.; And Others

    1985-01-01

    Reports a consecutive first-order reaction for which the concentrations of reactant, intermediate, and products can be determined simulataneously. This reaction is the epoxidation of 2,5-di-tert-butyl-1,4-benzoquinone (I) by alkaline hydroperoxidation using tert-butyl hydroperoxide and benzyltrimethylammonium hydroxide (Triton B) catalyst.…

  15. Analysis of molecular species of peroxide adducts of triacylglycerols following treatment of corn oil with tert -butyl hydroperoxide

    Microsoft Academic Search

    O. Sjövall; A. Kuksis; H. Kallio

    2001-01-01

    We recently demonstrated that exposure of synthetic mono-and diunsaturated triacylglycerols to tert-butylhy-droperoxide (TBHP) leads to formation of stable adducts of the oxidizing agent and the unsaturated esters (Sjvall,\\u000a O., Kuksis, A., and Kallio, H., Reversed Phase High-Performance Liquid Chromatographic Separation of tert-Butyl Hydroperoxide Oxidation Products of Unsaturated Triacylglycerols. J. Chromatogr. A 905, 119–132, 2001). In the present study we isolated

  16. Atmospheric Methyl Tertiary Butyl Ether (MTBE) at a Rural Mountain Site in California

    E-print Network

    Cohen, Ronald C.

    Atmospheric Methyl Tertiary Butyl Ether (MTBE) at a Rural Mountain Site in California Gunnar W in 1995­ 1996, reporting a range of 0.4 to 13.2 ppbv in the LosMethyl tertiary butyl ether (MTBE in surface Methyl tertiary butyl ether (MTBE) is widely waters. If the latter is true, concentrations

  17. Ethyl tert-butyl ether (ETBE)-degrading microbial communities in enrichments from polluted environments.

    PubMed

    Le Digabel, Yoann; Demanèche, Sandrine; Benoit, Yves; Fayolle-Guichard, Françoise; Vogel, Timothy M

    2014-08-30

    The ethyl tert-butyl ether (ETBE) degradation capacity and phylogenetic composition of five aerobic enrichment cultures with ETBE as the sole carbon and energy source were studied. In all cases, ETBE was entirely degraded to biomass and CO2. Clone libraries of the 16S rRNA gene were prepared from each enrichment. The analyses of the DNA sequences obtained showed different taxonomic compositions with a majority of Proteobacteria in three cases. The two other enrichments have different microbiota with an abundance of Acidobacteria in one case, whereas the microbiota in the second was more diverse (majority of Actinobacteria, Chlorobi and Gemmatimonadetes). Actinobacteria were detected in all five enrichments. Several bacterial strains were isolated from the enrichments and five were capable of degrading ETBE and/or tert-butyl alcohol (TBA), a degradation intermediate. The five included three Rhodococcus sp. (IFP 2040, IFP 2041, IFP 2043), one Betaproteobacteria (IFP 2047) belonging to the Rubrivivax/Leptothrix/Ideonella branch, and one Pseudonocardia sp. (IFP 2050). Quantification of these five strains and two other strains, Rhodococcus sp. IFP 2042 and Bradyrhizobium sp. IFP2049, which had been previously isolated from one of the enrichments was carried out on the different enrichments based on quantitative PCR with specific 16S rRNA gene primers and the results were consistent with the hypothesized role of Actinobacteria and Betaproteobacteria in the degradation of ETBE and the possible role of Bradyrhizobium strains in the degradation of TBA. PMID:25108826

  18. Singlet Exciton Fission in Thin Films of tert-Butyl-Substituted Terrylenes.

    PubMed

    Eaton, Samuel W; Miller, Stephen A; Margulies, Eric A; Shoer, Leah E; Schaller, Richard D; Wasielewski, Michael R

    2015-05-01

    Two terrylene chromophores, 2,5,10,13-tetra(tert-butyl)terrylene (1) and 2,5-di(tert-butyl)terrylene (2), were synthesized and studied to determine their singlet exciton fission (SF) efficiencies. Compound 1 crystallizes in one-dimensional stacks, whereas 2 packs in a slip-stacked, herringbone pattern of dimers motif. Strongly quenched fluorescence and rapid singlet exciton decay dynamics are observed in vapor-deposited thin films of 1 and 2. Phosphorescence measurements on thin films of 1 and 2 show that SF is only 70 meV endoergic for these chromophores. Femtosecond transient absorption experiments using low laser fluences on these films reveal rapid triplet exciton formation for both 1 (? = 120 ± 10 ps) and 2 (? = 320 ± 20 ps) that depends strongly on film crystallinity. The transient absorption data are consistent with formation of an excimer state prior to SF. Triplet exciton yield measurements indicate nearly quantitative SF in thin films of both chromophores in highly crystalline solvent-vapor-annealed films: 170 ± 20% for 1 and 200 ± 30% for 2. These results show that significantly different crystal morphologies of the same chromophore can both result in high-efficiency SF provided that the energetics are favorable. PMID:25856414

  19. Quercetin protects human hepatoma HepG2 against oxidative stress induced by tert-butyl hydroperoxide

    SciTech Connect

    Alia, Mario [Departamento de Metabolismo y Nutricion, Instituto del Frio (CSIC), C/Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid (Spain); Ramos, Sonia [Departamento de Metabolismo y Nutricion, Instituto del Frio (CSIC), C/Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid (Spain); Mateos, Raquel [Departamento de Metabolismo y Nutricion, Instituto del Frio (CSIC), C/Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid (Spain); Granado-Serrano, Ana Belen [Departamento de Metabolismo y Nutricion, Instituto del Frio (CSIC), C/Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid (Spain); Bravo, Laura [Departamento de Metabolismo y Nutricion, Instituto del Frio (CSIC), C/Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid (Spain); Goya, Luis [Departamento de Metabolismo y Nutricion, Instituto del Frio (CSIC), C/Jose Antonio Novais, 10, Ciudad Universitaria, 28040 Madrid (Spain)]. E-mail: luisgoya@if.csic.es

    2006-04-15

    Flavonols such as quercetin, have been reported to exhibit a wide range of biological activities related to their antioxidant capacity. The objective of the present study was to investigate the protective effect of quercetin on cell viability and redox status of cultured HepG2 cells submitted to oxidative stress induced by tert-butyl hydroperoxide. Concentrations of reduced glutathione and malondialdehyde, generation of reactive oxygen species and activity and gene expression of antioxidant enzymes were used as markers of cellular oxidative status. Pretreatment of HepG2 with 10 {mu}M quercetin completely prevented lactate dehydrogenase leakage from the cells. Pretreatment for 2 or 20 h with all doses of quercetin (0.1-10 {mu}M) prevented the decrease of reduced glutathione and the increase of malondialdehyde evoked by tert-butyl hydroperoxide in HepG2 cells. Reactive oxygen species generation induced by tert-butyl hydroperoxide was significantly reduced when cells were pretreated for 2 or 20 h with 10 {mu}M and for 20 h with 5 {mu}M quercetin. Finally, some of the quercetin treatments prevented the significant increase of glutathione peroxidase, superoxide dismutase, glutathione reductase and catalase activities induced by tert-butyl hydroperoxide. Gene expression of antioxidant enzymes was also affected by the treatment with the polyphenol. The results of the biomarkers analyzed clearly show that treatment of HepG2 cells in culture with the natural dietary antioxidant quercetin strongly protects the cells against an oxidative insult.

  20. Facile synthesis of l-Dopa tert-butyl ester by catalytic enantioselective phase-transfer alkylation

    Microsoft Academic Search

    Takashi Ooi; Minoru Kameda; Hidenori Tannai; Keiji Maruoka

    2000-01-01

    Facile asymmetric synthesis of l-Dopa and related amino acid esters has been achieved by phase-transfer catalysis of the rationally designed C2-symmetric chiral quaternary ammonium salts 1. The ‘scale-up’ experiment performed with 5.00 g of tert-butyl glycinate-benzophenone Schiff base (2) represents the practical aspect of our approach.

  1. Gold-catalyzed cyclization of tert-butyl allenoate: general synthesis of 2,4-functionalized butenolides

    Microsoft Academic Search

    Ji-Eun Kang; Eun-Sun Lee; Sang-Il Park; Seunghoon Shin

    2005-01-01

    AuCl3 efficiently catalyzes cyclization of tert-butyl allenoates into ?-butenolides. Advantage of directly using allenic ester precursor instead of corresponding acid is demonstrated in the synthesis of a variety of 2,4-disubstituted butenolides. A low catalyst loading and mild reaction condition makes this process an attractive alternative over conventional methods using strong Lewis acids.

  2. Regioselective vinylation of kojic acid using acetylenic esters in the presence of triphenylphosphine or tert -butyl isocyanide

    Microsoft Academic Search

    Sakineh Asghari; Maryam Faraji-Najjarkolaee; Mohammad Ahmadipour

    2010-01-01

    \\u000a Abstract  The 1:1 reactive intermediates generated by addition of tert-butyl isocyanide or triphenylphosphine to acetylenic esters were trapped by kojic acid to yield O-vinylated and C-vinylated\\u000a kojic acid, respectively.\\u000a \\u000a \\u000a \\u000a \\u000a Graphical abstract  

  3. Chemoselective hydrolysis of tert-butyl esters in acetonitrile using molecular iodine as a mild and efficient catalyst

    Microsoft Academic Search

    J. S. Yadav; E. Balanarsaiah; S. Raghavendra; M. Satyanarayana

    2006-01-01

    A simple, mild and efficient method for the hydrolysis of tert-butyl esters using molecular iodine as a catalyst is described. Acid labile protecting groups, such as N-Boc, OBn, OAc and double bonds, are compatible under the reaction conditions.

  4. Inhibition of radical reactions for an improved potassium tert-butoxide-promoted (11) C-methylation strategy for the synthesis of ?-(11) C-methyl amino acids.

    PubMed

    Suzuki, Chie; Kato, Koichi; Tsuji, Atsushi B; Zhang, Ming-Rong; Arano, Yasushi; Saga, Tsuneo

    2015-03-01

    ?-(11) C-Methyl amino acids are useful tools for biological imaging studies. However, a robust procedure for the labeling of amino acids has not yet been established. In this study, the (11) C-methylation of Schiff-base-activated ?-amino acid derivatives has been optimized for the radiosynthesis of various ?-(11) C-methyl amino acids. The benzophenone imine analog of methyl 2-amino butyrate was (11) C-methylated with [(11) C]methyl iodide following its initial deprotonation with potassium tert-butoxide (KOtBu). The use of an alternative base such as tetrabutylammonium fluoride, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene did not result in the (11) C-methylated product. Furthermore, the KOtBu-promoted (11) C-methylation of the Schiff-base-activated amino acid analog was enhanced by the addition of 1,2,4,5-tetramethoxybenzene or 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and inhibited by the addition of 1,10-phenanthroline. These results suggest that inhibition of radical generation induced by KOtBu improves the ?-(11) C-methylation of the Schiff-base-activated amino acids. The addition of a mixture of KOtBu and TEMPO to a solution of Schiff-base-activated amino acid ester and [(11) C]methyl iodide provided optimal results, and the tert-butyl ester and benzophenone imine groups could be readily hydrolyzed to give the desired ?-(11) C-methyl amino acids with a high radiochemical conversion. This strategy could be readily applied to the synthesis of other ?-(11) C-methyl amino acids. PMID:25690316

  5. Inhibition of palmityl carnitine oxidation in rat liver mitochondria by tert-butyl hydroperoxide.

    PubMed

    Cervinková, Z; Rauchová, H; Kriváková, P; Drahota, Z

    2008-01-01

    Mitochondria as an energy generating cell device are very sensitive to oxidative damage. Our previous findings obtained in hepatocytes demonstrated that Complex I of the respiratory chain is more sensitive to oxidative damage than other respiratory chain complexes. We present additional data on isolated mitochondria showing that palmityl carnitine oxidation is strongly depressed at a low (200 microM) tert-butyl hydroperoxide (tBHP) concentration, while oxidation of the flavoprotein-dependent substrate-succinate is not affected and neither is ATP synthesis inhibited by tBHP. In the presence of tBHP, the respiratory control index for palmityl carnitine oxidation is strongly depressed, but when succinate is oxidized the respiratory control index remains unaffected. Our findings thus indicate that flavoprotein-dependent substrates could be an important nutritional factor for the regeneration process in the necrotic liver damaged by oxidative stress. PMID:17465699

  6. Tert-butyl hydroperoxide selectively inhibits mitochondrial respiratory-chain enzymes in isolated rat hepatocytes.

    PubMed

    Drahota, Z; Kriváková, P; Cervinková, Z; Kmonícková, E; Lotková, H; Kucera, O; Houstek, J

    2005-01-01

    Sensitivity of various mitochondrial enzymes to oxidative damage was tested on isolated rat liver hepatocytes permeabilized by digitonin. In permeabilized hepatocytes normal respiratory control values were obtained and mitochondrial membranes remained intact. Respiratory rates of NADH-dependent (glutamate + malate, palmitylcarnitine + malate) and flavoprotein-dependent (succinate) substrates were determined in hepatocytes exposed for 5 min to 0.5-3 mM tert-butyl hydroperoxide before addition of digitonin. Our data showed that oxidation of NADH-dependent substrates is much more sensitive to oxidative stress than oxidation of flavoprotein-dependent ones, evidently due to the modification of iron-sulfur clusters or SH groups in the NADH dehydrogenase enzyme complex (Complex I). PMID:15717843

  7. Design and control of glycerol-tert-butyl alcohol etherification process.

    PubMed

    Vlad, Elena; Bildea, Costin Sorin; 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

  8. Photoelectric conversion and electrochromic properties of lutetium tetrakis(tert-butyl)bisphthalocyaninate

    SciTech Connect

    Hu, Andrew Teh; Hu Tenyi; Liu Lungchang

    2003-12-10

    Both photoelectric and electrochromic effects on lutetium tetrakis(tert-butyl)bisphthalocyaninate (Lu(TBPc){sub 2}) have been carried out in this study. Lu(TBPc){sub 2} is known for its electrochromic performance, but its photoelectric effect has not mentioned in the literature. The electrochromic properties of Lu(TBPc){sub 2} have been measured by cyclic voltammetry (CV) and UV-Vis spectrometer at the same time. It takes less than 1.5 s for the color to change from red to green under 0.9 V. Its cycle life is at least over 500 times. Furthermore, we also investigate its photoelectric conversion properties. Its photoelectric cell exhibits a positive photo-electricity conversion effect with a short-circuit photocurrent (46.4 {mu}A/cm{sup 2}) under illumination of white light (1.201 mW/cm{sup 2})

  9. Novel A3B-type tert-butyl-substituted tribenzodiazepinoporphyrazine: Synthesis, spectral properties and DFT study

    NASA Astrophysics Data System (ADS)

    Tarakanov, Pavel A.; Simakov, Anton O.; Tolbin, Alexandr Yu.; Balashova, Irina O.; Shestov, Vladimir I.; Tomilova, Larisa G.

    2015-03-01

    Novel A3B-type 8(9),13(14),18(19)-tri-tert-butyl-25,47-bis(4-tert-butylphenyl)tribenzo[g,l,q]-6H-1,4-diazepino[2,3-b]porphyrazine, which has high solubility in organic solvents, was obtained by template co-condensation of 2,3-dicyano-5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepine and 4-tert-butylphthalonitrile. It was characterized by UV/Vis, 1H, 13C NMR spectroscopy, and MALDI-TOF/TOF mass spectrometry. We have demonstrated for the first time using fluorescence spectroscopy measurements and quantum-chemical calculations that the complicated UV/Vis spectrum of A3B-type tribenzodiazepinoporphyrazine is due to the formation of stable H-type aggregates.

  10. Activating tert-butyl hydroperoxide by chelated vanadates for stereoselectively preparing sidechain-functionalized tetrahydrofurans.

    PubMed

    Dönges, Maike; Amberg, Matthias; Niebergall, Mark; Hartung, Jens

    2015-06-01

    tert-Butyl hydroperoxide (TBHP) stereoselectively oxidizes substituted 4-pentenols, when activated by (ethyl)[cis-(piperidine-2,6-diyl)dimethyl] vanadates. The reaction affords (tetrahydrofuran-2-yl)methanols in up to 89% yield, and in stereoselectivity ranging between moderate (cis:trans=32:68) to excellent (>99:1). Correlating structures of 4-pentenols, differing by substitution at tetragonal and trigonal stereocenters, to configuration of products obtained from oxidative cyclization provides a reaction model explaining the origin of stereoselectivity by (i) intramolecular oxygen atom transfer to (ii) a chair-like folded alkenol, being (iii) hydrogen-bonded to one of the two aminodiolate oxygens of the chelated vanadate, having (iv) substituents in the chair-like transition structure preferentially aligned equatorially. Substituents at trigonal stereocenters improve 2,5-cis- and 2,4-trans-selectivity for oxidative 4-pentenol cyclization in case of (Z)-configuration. An (E)-substituent does not alter selectivity exerted by a terminal (Z)-substituent of similar steric size. Larger (E)-groups increase the fraction of 2,5-trans-cyclized products. The reaction model additionally implements results from vanadium-51 NMR spectroscopy and density functional theory. According to theory, the (dialkoxy)(oxo)vanadium substituent exerts in the preferred end-on conformation almost no effect on structure and bonding of the peroxide group in tert-butylperoxy vanadates. Changing conformation to a higher in energy side-on arrangement puts the vanadate-bound tert-butylperoxy group into a position to serve in a concerted reaction as combined electron acceptor and oxygen atom donor. PMID:25958253

  11. Structure of organophosphorus compounds. Part XLII. The molecular structure of the 2,6-di-tert-butyl-4-methylphenyl ester of N-[2,4,6-tri(tert-butyl)-phenyl]phosphenimidous acid

    Microsoft Academic Search

    A. N. Chernega; M. Yu. Antipin; Yu. T. Struchkov; A. V. Ruban; V. D. Romanenko

    1989-01-01

    This is the first x-ray diffraction structural analysis of a dicoordinated phosphorus derivative with an N=P?O group, namely, the 2,6-di-tert-butylmethylphenyl ester of N-[2,4,6-tri(tert-butyl)phenyl]phosphenimidous acid (I) using ?Mo radiation and 6552 reflections to R=0.045. The unit cell parameters of the triclinic crystals are as follows: a=9.297, b=12.004, c=15.031, ?=107.87, ?=101.50, ?=95.50°, V=1542 Å3, dcalc=1.1 g\\/cm3, Z=2, space group P\\u000a

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

    PubMed

    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. PMID:23873782

  13. O3\\/H2O2 Treatment of Methyl-terf-Butyl Ether in Contaminated Waters: Effect of Background COD on the O3Dose

    Microsoft Academic Search

    Ali Safarzadeh-Amiri

    2002-01-01

    The destruction of methyl-tert-butyl ether (MTBE) in contaminated waters by O3\\/H202 process was studied and the influence background COD, alkalinity, and hydrogen peroxide and MTBE concentrations on process treatment efficiency and ozone dosage was investigated. The treatment efficiency was evaluated by an Efficiency Index, which is based on electrical energy requirement for ozone production. It was found that the treatment

  14. Tailored interfaces for biosensors and cell-surface interaction studies via activation and derivatization of polystyrene- block-poly( tert-butyl acrylate) thin films

    Microsoft Academic Search

    Chuan Liang Feng; Anika Embrechts; Ilona Bredebusch; Anita Bouma; Jürgen Schnekenburger; María García-Parajó; Wolfram Domschke; G. Julius Vancso; Holger Schönherr

    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 and (bio)reactivity due to the presence of a glassy PS and a reactive PtBA block, respectively. The selective deprotection of the tert-butyl-ester groups in the

  15. A synthesis of bicyclo[ n.1.0]alkanes having tert-butyl carboxylate or acetamide moiety via the intramolecular 1,3CH insertion of magnesium carbenoids

    Microsoft Academic Search

    Shingo Ogata; Hideki Saitoh; Daisuke Wakasugi; Tsuyoshi Satoh

    2008-01-01

    Treatment of 1-chlorovinyl p-tolyl sulfoxides, derived from various cyclic ketones and chloromethyl p-tolyl sulfoxide, with lithium enolate of carboxylic acid tert-butyl esters or N,N-dimethylacetamide gave adducts in high yields. The adducts were treated with ether solution of isopropylmagnesium chloride in dry toluene to give bicyclo[n.1.0]alkane derivatives having tert-butyl carboxylate or acetamide moiety on the bridgehead carbon in high to quantitative

  16. Indium(III) chloride-catalyzed oxidative cleavage of carbon–carbon multiple bonds by tert-butyl hydroperoxide in water—a safer alternative to ozonolysis

    Microsoft Academic Search

    Brindaban C. Ranu; Sukalyan Bhadra; Laksmikanta Adak

    2008-01-01

    An efficient and general method for the oxidative cleavage of alkenes and alkynes using tert-butyl hydroperoxide and indium(III) chloride as catalyst in water to give the corresponding carboxylic acids or ketones has been achieved. The reaction conditions are compatible with sensitive moieties such as peptide bonds, tert-butyl carboxylic esters and N-Boc-protected tryptophan. The catalyst could be recycled.

  17. Poly[(?2-4,4?-bipyridine)bis­(?4-5-tert-butyl­isophthalato)bis­(?3-5-tert-butyl­isophthalato)di-?3-hydroxido-penta­zinc(II)

    PubMed Central

    Zhou, Dong-Sheng; Sun, Di; Yang, Shi-Yao; Huang, Rong-Bin

    2009-01-01

    The asymmetric unit of the title compound, [Zn5(C12H12O4)4(OH)2(C10H8N2)]n, consists of three ZnII ions (one of which is located on a twofold rotation axis), two 5-tert-butyl­isophthalate ligands, one 4,4?-bipyridine ligand and one hydroxide group. The five ZnII ions form a penta­nuclear zinc cluster, which is further bridged by ten organic ligands, forming two-dimensional sheets. The central zinc ion of the cluster has site symmetry 2 and is octahedrally coordinated in a N2O4 donor set, whereas the other four zinc atoms are tetrahedrally coordinated by four O atoms. The coordination modes for the 5-tert-butyl­isophthalates are bis­(bidentate) or bidentate-monodentate. Hydrogen bonds are formed between adjacent sheets through the hydroxide groups and the O atoms of the monodentate carboxyl­ate groups. The two tert-butyl groups are disordered over two positions with ratios of 0.64?(2):0.36?(2) and 0.85?(3):0.15?(3). PMID:21577432

  18. Reactive distillation for synthesizing ethyl tert-butyl ether from low-grade alcohol catalyzed by potassium hydrogen sulfate

    SciTech Connect

    Matouq, M.; Quitain, A.T.; Takahashi, Katsuroku; Goto, Shigeo [Nagoya Univ. (Japan). Dept. of Chemical Engineering] [Nagoya Univ. (Japan). Dept. of Chemical Engineering

    1996-03-01

    Synthesis of ethyl tert-butyl ether (ETBE) from the reaction between ethanol (EtOH) and tert-butyl alcohol (TBA) in the presence of different acid catalysts (KHSO{sub 4}, NaHSO{sub 4}, H{sub 2}SO{sub 4}, and Amberlyst 15) was investigated at low alcohol grade (mixture of 80 mol % water). Potassium hydrogen sulfate (KHSO{sub 4}) showed the highest selectivity among the tested catalysts. Other catalysts caused the dehydration of TBA into water (H{sub 2}O) and isobutene (IB). In the top of the reactive distillation column with total reflux, the condensate was split into two layers. The upper layer contained ETBE with a more than 60 mole fraction.

  19. Ethers from ethanol. 1: Equilibrium thermodynamic analysis of the liquid-phase ethyl tert-butyl ether reaction

    Microsoft Academic Search

    Kyle L. Jensen; Ravindra Datta

    1995-01-01

    The equilibrium-limited liquid-phase synthesis of ethyl tert-butyl ether (ETBE) from the combination of ethanol and isobutylene over an ion-exchange resin catalyst, typically Amberlyst 15, is a reaction of considerable industrial importance now. An equilibrium constant relationship is developed here for the liquid-phase ETBE reaction by following three alternative thermodynamic pathways and critically evaluating the resulting expressions. The final theoretical expression

  20. Antioxidant treatment with phenyl-?- tert-butyl nitrone (PBN) improves the cognitive performance and survival of aging rats

    Microsoft Academic Search

    Candice A. Sack; Debra J. Socci; Blane M. Crandall; Gary W. Arendash

    1996-01-01

    Accumulating evidence has implicated free radical production and resultant oxidative damage as a major contributing factor in brain aging and cognitive decline. In the present study, aging 24-month-old rats were chronically treated with the synthetic spin-trapping antioxidant phenyl-?-tert-butyl nitrone (PBN) for up to 9.5 months. Chronic PBN treatment (1) improved the cognitive performance of aged rats in several tasks, (2)

  1. The effects of ?-phenyl- tert-butyl nitrone (PBN) on copper-induced rat fulminant hepatitis with jaundice

    Microsoft Academic Search

    Tadashi Yamashita; Hideki Ohshima; Taketoshi Asanuma; Naoko Inukai; Ichiro Miyoshi; Noriyuki Kasai; Yasuhiro Kon; Tomomasa Watanabe; Fumiaki Sato; Mikinori Kuwabara

    1996-01-01

    In the present study we demonstrated the protective effects of the spin-trapping agent ?-phenyl-tert-butyl nitrone (PBN) against fulminant hepatitis with jaundice in LEC rats. In LEC rats an excess amount of copper is accumulated in the liver and causes hepatitis with severe jaundice. PBN was subcutaneously administered every 2 d at the concentration of 128 mg\\/kg, beginning with 13-week-old rats

  2. N-tert-butyl-alpha-phenylnitrone protects against 3,4-methylenedioxymethamphetamine-induced depletion of serotonin in rats

    Microsoft Academic Search

    S. Y. Yeh

    1999-01-01

    The present study examined the effect of N-tert-butyl-alpha-phenylni- trone (PBN) on 3,4-methylenedioxmathamphetamine (MDMA)-induced depletion of serotonin in the CNS. Rats were treated with two concurrent injections of MDMA (20 mg\\/kg, s.c.), PBN (50-400 mg\\/kg dissolved in ethanol, 50 mg\\/ml of 25% ethanol, i.p.), saline or 25% ethanol, alone or in combination, 6 h apart, and sacrificed 5 days later. Rectal

  3. ?-Phenyl- N- tert-butyl nitrone (PBN) derivatives: Synthesis and protective action against microvascular damages induced by ischemia\\/reperfusion

    Microsoft Academic Search

    Sothea Kim; Guilherme V. M. de A. Vilela; Jalloul Bouajila; Ayres G. Dias; Fatima Z. G. A. Cyrino; Eliete Bouskela; Paulo R. R. Costa; Françoise Nepveu

    2007-01-01

    Nitrones 4–7, structurally related to PBN (1), were prepared by reaction of the corresponding aromatic aldehydes with N-tert-butyl hydroxylamine. The protective effects of these nitrones against microvascular damages in ischemia\\/reperfusion in the ‘hamster cheek pouch’ assay were studied and 1, as well as 4a, 4b, and 7 (derived from piperonal, O-benzyl vanillin, and furfural, respectively), showed to be more active

  4. ?-Phenyl-tert-N-Butyl Nitrone (PBN) Improves Functional and Morphological Outcome After Cortical Contusion Injury in the Rat

    Microsoft Academic Search

    N. Marklund; F. Clausen; A. Lewén; D. A. Hovda; Y. Olsson; L. Hillered

    2001-01-01

    Summary  ??-Phenyl-tert-N-butyl nitrone (PBN), a potent reactive oxygen species (ROS) scavenger, has shown robust neuroprotective properties in several\\u000a models of acute brain injury, although not previously evaluated in traumatic brain injury (TBI). In this study, we assessed\\u000a the potential efficacy of PBN in a weight drop model producing a controlled cortical contusion. Sham operation, mild or severe\\u000a injury was induced in

  5. On the Langmuir–Blodgett transfer of copper tetra- tert-butyl phthalocyanine monolayers in the presence of arachidic acid

    Microsoft Academic Search

    Ching-Wen Sheu; Kuen-Mo Lin; I-Hsun Ku; Chien-Hsiang Chang; Yuh-Lang Lee; Yu-Min Yang; Jer-Ru Maa

    2002-01-01

    This study investigated the influence of arachidic acid as a transfer promoter on the deposition of multilayer copper tetra-tert-butyl phthalocyanine (CuTTBPc) Langmuir–Blodgett (L–B) films on both hydrophilic glass and hydrophobic silanized-glass substrates. With the addition of arachidic acid in a CuTTBPc monolayer at the air\\/water interface, two transitions corresponding to monolayer collapse were observed in the surface pressure–area isotherm. However,

  6. Formation of triacylglycerol core aldehydes during rapid oxidation of corn and sunflower oils with tert -butyl hydroperoxide\\/Fe 2+

    Microsoft Academic Search

    Olli Sjövall; Arnis Kuksis; Heikki Kallio

    2002-01-01

    The lipid ester core aldehydes formed during a rapid oxidation (7.8 M tert-butyl hydroperoxide, 90 min at 37°C) of the triacylglycerols of purified corn and sunflower oils were isolated as dinitrophenylhydrazones\\u000a by preparative thin-layer chromatography and identified by reversed-phase high-performance liquid chromatography with on-line\\u000a electrospray ionization mass spectrometry and by reference to standards. A total of 113 species of triacylglycerol

  7. Grafting of end-functionalized poly( tert-butyl acrylate) to poly(ethylene- co-acrylic acid) film

    Microsoft Academic Search

    Keisha B. Walters; Douglas E. Hirt

    2006-01-01

    Poly(tert-butyl acrylate) (PtBA) was grafted to the surface of poly(ethylene-co-acrylic acid) (EAA) film and the pendant groups of the tethered PtBA were modified to create chemically tailored surface modifying layers. The carboxylic acid groups in the copolymer film served as the grafting sites for the covalent tethering of end-functionalized PtBA. The progression of these reactions was monitored using attenuated total

  8. Reactive Imprint Lithography: Combined Topographical Patterning and Chemical Surface Functionalization of Polystyrene-block-poly(tert-butyl acrylate) Films

    Microsoft Academic Search

    Joost Duvigneau; Stijn Cornelissen; Nuria Bardaj?´Valls; Holger Schönherr; G. Julius Vancso

    2009-01-01

    Here, reactive imprint lithography (RIL) is introduced as a new, one-step lithographic tool for the fabrication of large-area topographically patterned, chemically activated polymer platforms. Films of polystyrene-block-poly(tert-butyl acrylate) (PS-b-PtBA) are imprinted with PDMS master stamps at temperatures above the corresponding glass transition and chemical deprotection temperatures to yield structured films with exposed carboxylic acid and anhydride groups. Faithful pattern transfer

  9. Highly enantioselective monoalkylation of p-chlorobenzaldehyde imine of glycine tert-butyl ester under mild phase-transfer conditions

    Microsoft Academic Search

    Takashi Ooi; Yuichiro Arimura; Yukihiro Hiraiwa; Lin Ming Yuan; Taichi Kano; Toru Inoue; Jun Matsumoto; Keiji Maruoka

    2006-01-01

    The selective monoalkylation of glycine tert-butyl ester aldimine Schiff base 3 has been realized in high chemical yield with excellent enantioselectivity under mild liquid–liquid phase-transfer conditions by the use of binaphthyl-derived chiral quaternary ammonium bromides 7 and 8 as catalysts. This achievement demonstrates that 3 can be used as a cost-effective substrate for the preparation of optically active ?-alkyl-?-amino acid

  10. Synthesis and lithographic evaluation of poly[(methacrylic acid tert-butyl cholate ester)- co-(?-butyrolactone-2-yl methacrylate)

    Microsoft Academic Search

    Jin-Baek Kim; Jong-Sung Ko; Jae-Hak Choi; Ji-Hyun Jang; Tae-Hwan Oh; Hyun-woo Kim; Bum-wook Lee

    2004-01-01

    Poly[(methacrylic acid tert-butyl cholate ester)-co-(?-butyrolactone-2-yl methacrylate)] was synthesized and evaluated as a new 193-nm chemically amplified photoresist. This polymer showed good thermal stability up to 240 °C and had a good transmittance at 193 nm. This material showed good resistance to CF4-reactive ion etching. The resist patterns of 0.15 ?m feature size were obtained at a dose of 11mJcm?2 using

  11. Protective effect of caffeic acid phenethyl ester on tert-butyl hydroperoxide-induced oxidative hepatotoxicity and DNA damage

    Microsoft Academic Search

    Kyung Jin Lee; Jae Ho Choi; Yong Pil Hwang; Young Chul Chung; Hye Gwang Jeong

    2008-01-01

    Increased oxidative stress and associated high levels of free radical generation have been described to occur during the pathogeneses of various diseases in animal models. In the present work, we investigated the protective effects of the phenethyl ester of caffeic acid (CAPE), an active component of honeybee propolis, on tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in a cultured HepG2 cell line and

  12. Palladium-catalyzed chemoselective synthesis of indane-1,3-dione derivatives via tert-butyl isocyanide insertion.

    PubMed

    Duan, Huaqing; Chen, Zhong; Han, Li; Feng, Yulin; Zhu, Yongming; Yang, Shilin

    2015-06-10

    A simple and efficient strategy for the synthesis of indane-1,3-dione derivatives through a palladium(0)-catalyzed reaction incorporating tert-butyl isocyanide has been developed. In addition, by applying this protocol as the key step, indenopyrazole derivatives can be easily synthesized in high yields in a one-pot procedure. This methodology is tolerant of a wide range of substrates and applicable to library synthesis. PMID:26007325

  13. Biodegradation of ethyl t -butyl ether (ETBE), methyl t -butyl ether (MTBE) and t -amyl methyl ether (TAME) by Gordonia terrae

    Microsoft Academic Search

    Guillermina Hernandez-Perez; Françoise Fayolle; Jean-Paul Vandecasteele

    2001-01-01

    Gordonia terrae strain IFP 2001 was selected from activated sludge for its capacity to grow on ethyl t-butyl ether (ETBE) as sole carbon and energy source. ETBE was stoichiometrically degraded to t-butyl alcohol (TBA) and the activity was inducible. A constitutive strain, G. terrae IFP 2007, derived from strain IFP 2001, was also selected. Methyl t-butyl ether (MTBE) and t-amyl

  14. Highly efficient blue organic light-emitting diodes based on 2-(diphenylamino)fluoren-7-ylvinylarene derivatives that bear a tert-butyl group.

    PubMed

    Lee, Kum Hee; Kwon, Young Soo; Lee, Jin Yong; Kang, Sunwoo; Yook, Kyoung Soo; Jeon, Soon Ok; Lee, Jun Yeob; Yoon, Seung Soo

    2011-11-11

    Blue fluorescent materials with a 2-(diphenylamino)fluoren-7-ylvinylarene emitting unit and tert-butyl-based blocking units were synthesized. The photophysical properties of these materials, including UV/Vis absorption, photoluminescent properties, and HOMO-LUMO energy levels, were characterized and rationalized with quantum-mechanical DFT calculations. The electroluminescent properties of these molecules were examined through the fabrication of multilayer devices with a structure of indium-tin oxide, 4,4'-bis{N-[4-(N,N-di-m-tolylamino)phenyl]-N-phenylamino}biphenyl, 4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl, and blue materials doped in 2-methyl-9,10-di(2-naphthyl)anthracene/tris(8-quinolinolato)aluminum/LiF/Al. All devices exhibit highly efficient blue electroluminescence with high external quantum efficiency (3.20-7.72?% at 20?mA?cm(-2)). A deep-blue device with Commission Internationale de l'Eclairage (CIE) coordinates of (0.15, 0.11) that uses 7-[2-(3',5'-di-tert-butylbiphenyl-4-yl)vinyl]-9,9-diethyl-2-N-(3,5-di-tert-butylphenyl)-2,4-difluorobenzenamino-9H-fluorene as a dopant in the emitting layer showed a luminous efficiency and external quantum efficiency of 3.95?cd?A(-1) and 4.23?% at 20?mA?cm(-2), respectively. Furthermore, a highly efficient sky-blue device that uses the dopant 7-{2-[2-(3,5-di-tert-butylphenyl)-9,9'-spirobifluorene-7-yl]vinyl}-9,9-diethyl-2-N,N-diphenylamino-9H-fluorene exhibited a luminous efficiency and high quantum efficiency of 10.3?cd?A(-1) and 7.7?% at 20?mA?cm(-2), respectively, with CIE coordinates of (0.15, 0.20). PMID:21956775

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

    PubMed

    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 (?H(‡) ), entropy (?S(‡) ), and free energy (?G(‡) ) of activation], calculated using Arrhenius and Eyring-Polanyi equations, established that TBA (2%, w/w) accelerated GHCl crystallization by reducing its ?H(‡) (53.9 cf. 96.5 kJ/mol(-1) ) and ?G(‡) (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 ?H(‡) of nucleation and increased ?S(‡) of crystal growth, thereby reducing ?G(‡) 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 ?G(‡) of nucleation and crystal growth in a differential manner, thereby enhancing the crystallization kinetics of GHCl and affecting its morphological features. PMID:25393155

  16. Dynamic light scattering study of the tert-butyl alcohol-water system

    SciTech Connect

    Bender, T.M.; Pecora, R.

    1986-04-10

    The hypersonic speed of sound (C/sub h/) has been measured in the tert-butyl alcohol-water system (TBA/water) from 0.0 to 0.16 mole fraction of TBA at 10-45 /sup 0/C by Brillouin scattering. Considerable dispersion in the C/sub h/ as compared to that found in the zero frequency and ultrasonic range is observed. The isentropic compressibilities in the hypersonic range are also presented for 10, 20, and 25 /sup 0/C. Photon correlation spectroscopy (PCS) gave no evidence of the presence of oligimers in the system and depolarized interferometry measurements detected no rotational diffusion by species in the system. The acoustic relaxation times calculated at mole fraction of TBA equal to 0.105 were found to be in agreement with literature values of both NMR and dielectric relaxation measurements on this system. The results obtained were interpreted from the view point that the relaxation time observed was due to a structural relaxation. 46 references, 4 figures, 2 tables.

  17. Hydrophobic hydration of tert-butyl alcohol studied by Brillouin light and inelastic ultraviolet scattering.

    PubMed

    Lupi, L; Comez, L; Masciovecchio, C; Morresi, A; Paolantoni, M; Sassi, P; Scarponi, F; Fioretto, D

    2011-02-01

    The longitudinal viscosity of diluted water-tert-butyl alcohol solutions in the 10 GHz frequency region has been measured by means of Brillouin light scattering and inelastic ultraviolet scattering. The main advantage of our hypersonic investigation compared to more traditional ultrasonic measurements is that in the gigahertz frequency range slow relaxation processes involving the alcohol dynamics are completely unrelaxed, so that the measured viscosity mainly originates from the hydrogen bond restructuring of water. In contrast with previous determinations, we estimate an activation energy which is independent from the alcohol mole fraction up to X = 0.1, and comparable to that of bulk water. A simple two-component model is used to describe the steep increase of viscosity with increasing alcohol mole fraction, and a retardation factor 1.7 ± 0.2 is found between the relaxation times of hydration and bulk water. These findings endorse a dynamic scenario where the slowing down of hydration water is mainly due to a reduction of configurational entropy and does not involve an arrested, icelike, dynamics. PMID:21303164

  18. Hydrophobic Hydration in Water-tert-Butyl Alcohol Solutions by Extended Depolarized Light Scattering.

    PubMed

    Comez, L; Paolantoni, M; Lupi, L; Sassi, P; Corezzi, S; Morresi, A; Fioretto, D

    2015-07-23

    Molecular dynamics and structural properties of water-tert-butyl alcohol (TBA) mixtures are studied as a function of concentration by extended depolarized light scattering (EDLS) experiments. The wide frequency range, going from fraction to several thousand GHz, explored by EDLS allows distinguishing TBA rotational dynamics from structural relaxation of water and intermolecular vibrational and librational modes of the solution. Contributions to the water relaxation originating from two distinct populations, i.e. hydration and bulk water, are clearly identified. The dynamic retardation factor of hydration water with respect to the bulk, ? ? 4, almost concentration independent, is one of the smallest found by EDLS among a variety of systems of different nature and complexity. This result, together with the small number of water molecules perturbed by the presence of TBA, supports the idea that hydrophobic simple molecules are less effective than hydrophilic and more complex molecules in perturbing the H-bond network of liquid water. At increasing TBA concentrations the average number of perturbed water molecules shows a pronounced decrease and the characteristic frequency of librational motions reduces significantly, both of which are results consistent with the occurrence of self-aggregation of TBA molecules. PMID:25436859

  19. Emulsion Polymerization of Butyl Acrylate: Spin Trapping and EPR Study

    NASA Technical Reports Server (NTRS)

    Kim, S.; Westmoreland, D.

    1994-01-01

    The propagating radical in the emulsion polymerization reaction of butyl acrylate was detected by Electron Paramagnetic Resonance spectroscopy using two spin trapping agents, 2-methyl-2nitrosopropane and alpha -N-tert-butylnitrone.

  20. Gasohol, TBA, and MTBE effects on light-duty emissions. [Gasoline mixtures of ethanol, test-butyl alcohol, and methyl test-butylether

    SciTech Connect

    Bykowski, B.B.; Garbe, R.J.

    1981-01-01

    This article summarizes a report prepared for the Emission Control Technology Division, Environmental Protection Agency, Ann Arbor, Michigan. The report describes the laboratory testing of unleaded gasoline and gasoline mixtures containing ethanol, tert- butyl alcohol (TBA), and methyl tert-butyl ether (MTBE). Four different vehicles were employed in this study. Analytical procedures for the measurement of TBA and ethanol in exhaust and evaporative emissions were developed. Regulated and unregulated emission rate were determined during the entire Federal Test Procedure (FTP) for each vehicle using several gasoline blends. Exhaust emission rates of hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), individual hydrocarbons (IHC), and aldehydes are reported in grams per kilometer. Evaporative emissions of total hydrocarbons, TBA, and ethanol are reported in grams. (Refs. 3).

  1. ?-PHENYL-N-TERT-BUTYL-NITRONE ATTENUATES LIPOPOLYSACCHARIDE- INDUCED NEURONAL INJURY IN THE NEONATAL RAT BRAIN

    PubMed Central

    Fan, Lir-Wan; Mitchell, Helen J.; Rhodes, Philip G.; Cai, Zhengwei

    2008-01-01

    Although white matter damage is a fundamental neuropathological feature of periventricular leukomalacia (PVL), the motor and cognitive deficits observed later in infants with PVL indicate the possible involvement of cerebral neuronal dysfunction. Using a previously developed rat model of white matter injury induced by cerebral lipopolysaccharide (LPS) injection, we investigated whether LPS exposure also results in neuronal injury in the neonatal brain and whether ?-phenyl-n-tert-butyl-nitrone (PBN), an antioxidant, offers protection against LPS-induced neuronal injury. A stereotactic intracerebral injection of LPS (1 mg/kg) was performed in Sprague-Dawley rats (postnatal day 5) and control rats were injected with sterile saline. LPS exposure resulted in axonal and neuronal injury in the cerebral cortex as indicated by elevated expression of ?-amyloid precursor protein, altered axonal length and width, and increased size of cortical neuronal nuclei. LPS exposure also caused loss of tyrosine hydroxylase positive neurons in the substantia nigra and the ventral tegmental areas of the rat brain. Treatments with PBN (100 mg/kg) significantly reduced LPS-induced neuronal and axonal damage. The protection of PBN was associated with an attenuation of oxidative stress induced by LPS as indicated by the reduced number of 4-hydroxynonenal, malondialdehyde or nitrotyrosine positive cells in the cortical area following LPS exposure, and with the reduction in microglial activation stimulated by LPS. The finding that an inflammatory environment may cause both white matter and neuronal injury in the neonatal brain supports the possible anatomical correlate for the intellectual deficits and the other cortical and deep gray neuronal dysfunctions associated with PVL. The protection of PBN may indicate the potential usefulness of antioxidants for treatment of these neuronal dysfunctions. PMID:18191905

  2. Ring-expansion reactions in the thermal decomposition of tert-butyl-1,3-cyclopentadiene.

    PubMed

    McGivern, W Sean; Manion, Jeffrey A; Tsang, Wing

    2006-11-30

    The thermal decomposition of tert-butyl-1,3-cyclopentadiene has been investigated in single-pulse shock-tube studies at shock pressures of 182-260 kPa and temperatures of 996-1127 K. Isobutene (2-methylpropene), 1,3-cyclopentadiene, and toluene were observed as the major stable products in the thermolysis of dilute mixtures of the substrate in the presence of a free-radical scavenger. Hydrogen atoms were also inferred to be a primary product of the decomposition and could be quantitatively determined on the basis of products derived from the free-radical scavenger. Of particular interest is the formation of toluene, which involves the expansion of the ring from a five- to a six-membered system. The overall reaction mechanism is suggested to include isomerization of the starting material; a molecular elimination channel; and C-C bond fission reactions, with toluene formation occurring via radical intermediates formed in the latter pathway. These radical intermediates are analogous to those believed to be important in soot formation reactions occurring during combustion. Molecular and thermodynamic properties of key species were determined from G3MP2B3 quantum chemistry calculations and are reported. The temperature dependence of the product spectrum was fit with a detailed chemical kinetic model, and best-fit kinetic parameters were derived using a Nelder-Mead simplex minimization algorithm. Our mechanism and rate constants are consistent with and provide experimental support for the H-atom-assisted routes to the conversion of fulvene to benzene that have been proposed in the literature on the basis of theoretical investigations. PMID:17125296

  3. Phospholes with Reduced Pyramidal Character from Steric Crowding. 1. Synthesis and NMR Characterization of 1-(2,4-Di-tert-butyl-6-methylphenyl)-3-methylphosphole.

    PubMed

    Quin, Louis D.; Keglevich, György; Ionkin, Alexey S.; Kalgutkar, Rajdeep; Szalontai, Gábor

    1996-11-01

    The sterically crowded 1-(2,4-di-tert-butyl-6-methylphenyl)-3-methylphosphole was synthesized by dehydrohalogenation of the corresponding 3,4-dibromophospholane, in order to probe the possibility that the steric congestion would cause some flattening of the phosphorus pyramid and an increase in electron delocalization. The phosphole was a recrystallizable solid with (31)P NMR delta 1.8. Semiempirical calculations indicated that the pyramidal shape was retained but was noticeably flatter than in 1-phenylphosphole. In the low energy conformation, the phosphole and phenyl ring planes are approximately orthogonal, with the 2-tert-butyl group in the less crowded position that is syn to the lone pair on phosphorus. The 6-methyl group is positioned under the phosphole ring. This conformational prediction was amply confirmed by several chemical shift and coupling effects in the (13)C NMR spectrum. The (1)H NMR spectrum displayed an unusually large four-bond coupling (6 Hz) of (31)P to the m-phenyl proton syn to the lone pair (and none to the anti-meta proton), consistent with the orthogonal conformation. The oxide of the phosphole showed more stability than that of less crowded phospholes and gave a (31)P NMR signal that was detectable over a several hour period at room temperature. The oxide proceeded to give the usual Diels-Alder dimer and also formed a cycloadduct with N-phenylmaleimide. The phosphoryl group of the latter was reduced with trichlorosilane to give the phosphine. This new 7-phosphanorbornene derivative gave the most downfield (31)P NMR shift (delta 153.3) of any member of this family, all of which are characterized by remarkable deshielding in the syn isomer. PMID:11667736

  4. Biotransformation of [(12)C]- and [(13)C]-tert-amyl methyl ether and tert-amyl alcohol.

    PubMed

    Amberg, A; Bernauer, U; Scheutzow, D; Dekant, W

    1999-10-01

    tert-Amyl methyl ether (TAME) is intended for use as a gasoline additive to increase oxygen content. Increased oxygen content in gasoline reduces tailpipe emissions of hydrocarbons and carbon monoxide from cars. Due to possible widespread use of TAME, the toxicity of TAME is under investigation. We studied the biotransformation of TAME in rats and one human volunteer after inhalation of (12)C- or (13)C-labeled TAME. In addition, the biotransformation of [(13)C]-tert-amyl alcohol was studied in rats after gavage. Urinary metabolites were identified by GC/MS and (13)C NMR. Rats (two males and two females) were individually exposed to 2000 ppm [(12)C]- or [(13)C]TAME for 6 h, and urine was collected for 48 h. Free and glucuronidated 2-methyl-2,3-butanediol and a glucuronide of tert-amyl alcohol were identified by (13)C NMR, GC/MS, and LC/MS/MS as major urinary metabolites on the basis of the relative intensities of the (13)C NMR signals. The presence of several minor metabolites was also indicated by (13)C NMR; they were identified as tert-amyl alcohol, 2-hydroxy-2-methylbutyric acid, and 3-hydroxy-3-methylbutyric acid. One human volunteer was exposed to an initial concentration of 27 000 ppm [(13)C]TAME by inhalation for 4 min from a 2 L gas sampling bag, and metabolites of TAME excreted in urine were analyzed by (13)C NMR. All TAME metabolites identified in rats were also present in the human urine samples. To study tert-amyl alcohol biotransformation, male rats (n = 3) were treated with 250 mg/kg [(13)C]-tert-amyl alcohol dissolved in corn oil by gavage, and urine was collected for 48 h. (13)C NMR of the urine samples showed the presence of metabolites identical to those in the urine of [(13)C]TAME-treated rats. Our results suggest that TAME is extensively metabolized by rats and humans to tert-amyl alcohol which may be further oxidized to diols and carboxylic acids. These reactions are likely mediated by cytochrome P450-dependent oxidations. PMID:10525272

  5. Formation of Zinc–Peptide Spherical Microparticles During Lyophilization from tert Butyl Alcohol\\/Water Cosolvent System

    Microsoft Academic Search

    Feng Qian; Nina Ni; Jia-Wen Chen; Sridhar Desikan; Vijay Naringrekar; Munir A. Hussain; Nancy P. Barbour; Ronald L. Smith

    2008-01-01

    Purpose  To understand the mechanism of spherical microparticle formation during lyophilizing a tert-Butyl alcohol (TBA)\\/water solution of a zinc peptide adduct.\\u000a \\u000a \\u000a \\u000a Method  A small peptide, PC-1, as well as zinc PC-1 at (3:2) and (3:1) ratios, were dissolved in 44% (wt.%) of TBA\\/water, gradually\\u000a frozen to ?50°C over 2 h (“typical freezing step”), annealed at ?20°C for 6 h (“annealing step”), and subsequently lyophilized

  6. Cytoprotective effects of pu-erh tea on hepatotoxicity in vitro and in vivo induced by tert-butyl-hydroperoxide

    Microsoft Academic Search

    Pin-Der Duh; Bor-Sen Wang; Shiou-Jen Liou; Chia-Jung Lin

    2010-01-01

    The in vitro and in vivo protective effects of water extract of pu-erh tea (WEPT) on tert-butyl-hydroperoxide (t-BHP)-induced oxidative damage in hepatocytes of HepG2 cells and in rat livers were investigated. After treatment with 200?g\\/ml of samples, the survival rate of HepG2 cells induced by t-BHP increased. WEPT concentration-dependently inhibited reactive oxygen species (ROS) generation in HepG2 cells in response

  7. Synthesis and characterization of novel acid-sensitive tert-butyl methacrylate and isobutyl methacrylate containing star-shaped polymers

    Microsoft Academic Search

    Timothy E. Long; Lars Kilian; Zhen-He Wang; Alan R. Esker

    2001-01-01

    Star-shaped polymers containing poly(isobutyl methacrylate) (iBMA) and poly(tert-butyl methacrylate) (t-BMA) arms coupled to a 2,5-dimethyl-2,5-hexanediol dimethacrylate (DHDMA) core were synthesized using arm-first living anionic polymerization. Gel permeation chromatography (GPC) indicated that coupling efficiencies were high and coupled products exhibited a monomodal molecular weight distribution. The star-shaped polymer number--average molecular weights were 8-10 times higher than the precursor arm molecular weights.

  8. A mild and selective method for the cleavage of tert-butyl esters

    Microsoft Academic Search

    Randy W Jackson

    2001-01-01

    A method for the cleavage of t-butyl esters using silica gel in refluxing toluene is reported. Good yields of the corresponding carboxylic acids are obtained, and the reaction is selective for t-butyl esters over t-butyl ethers and trimethylsilylethyl (TMSE) esters.

  9. Selective tert-butyl ester deprotection in the presence of acid labile protecting groups with use of ZnBr2.

    PubMed

    Kaul, Ramesh; Brouillette, Yann; Sajjadi, Zohreh; Hansford, Karl A; Lubell, William D

    2004-09-01

    Chemoselective hydrolysis of tert-butyl esters in the presence of other acid-labile groups has been explored by employing alpha-amino esters and ZnBr(2) in DCM. Although N-Boc and N-trityl groups were found to be labile, PhF protected amines were compatible with these Lewis acid deprotection conditions such that a variety of N-(PhF)amino acids were prepared in good yields from their corresponding tert-butyl esters. PMID:15373501

  10. Aggregation in dilute aqueous tert-butyl alcohol solutions: Insights from large-scale simulations

    NASA Astrophysics Data System (ADS)

    Gupta, Rini; Patey, G. N.

    2012-07-01

    Molecular dynamics simulations employing up to 64 000 particles are used to investigate aggregation and microheterogeneity in aqueous tert-butyl alcohol (TBA) solutions for TBA mole fractions Xt ? 0.1. Four different force fields are considered. It is shown that the results obtained can be strongly dependent on the particular force field employed, and can be significantly influenced by system size. Two of the force fields considered show TBA aggregation in the concentration range Xt ? 0.03 - 0.06. For these models, systems of 64 000 particles are minimally sufficient to accommodate the TBA aggregates. The structures resulting from TBA aggregation do not have a well-defined size and shape, as one might find in micellar systems, but are better described as TBA-rich and water-rich regions. All pair correlation functions exhibit long-range oscillatory behavior with wavelengths that are much larger than molecular length scales. The oscillations are not strongly damped and the correlations can easily exceed the size of the simulation cell, even for the low TBA concentrations considered here. We note that these long-range correlations pose a serious problem if one wishes to obtain certain physical properties such as Kirkwood-Buff integrals from simulation results. In contrast, two other force fields that we consider show little sign of aggregation for Xt ? 0.08. In our 64 000 particle simulations all four models considered show demixing-like behavior for Xt ? 0.1, although such behavior is not evident in smaller systems of 2000 particles. The meaning of the demixing-like behavior is unclear. Since real TBA-water solutions do not demix, it might be an indication that all four models we consider poorly represent the real system. Alternatively, it might be an artifact of finite system size. Possibly, the apparent demixing indicates that for Xt ? 0.1, the stable TBA aggregates are simply too large to fit into the simulation cell. Our results provide a view of the possible nature of microheterogeneity in dilute TBA-water solutions, and of the associated long correlation lengths. It is clear that system size can be a very important factor in simulations of these solutions, and must be taken into account in the evaluation and development of TBA-water force fields.

  11. Aggregation in dilute aqueous tert-butyl alcohol solutions: insights from large-scale simulations.

    PubMed

    Gupta, Rini; Patey, G N

    2012-07-21

    Molecular dynamics simulations employing up to 64,000 particles are used to investigate aggregation and microheterogeneity in aqueous tert-butyl alcohol (TBA) solutions for TBA mole fractions X(t) ? 0.1. Four different force fields are considered. It is shown that the results obtained can be strongly dependent on the particular force field employed, and can be significantly influenced by system size. Two of the force fields considered show TBA aggregation in the concentration range X(t) ? 0.03 - 0.06. For these models, systems of 64,000 particles are minimally sufficient to accommodate the TBA aggregates. The structures resulting from TBA aggregation do not have a well-defined size and shape, as one might find in micellar systems, but are better described as TBA-rich and water-rich regions. All pair correlation functions exhibit long-range oscillatory behavior with wavelengths that are much larger than molecular length scales. The oscillations are not strongly damped and the correlations can easily exceed the size of the simulation cell, even for the low TBA concentrations considered here. We note that these long-range correlations pose a serious problem if one wishes to obtain certain physical properties such as Kirkwood-Buff integrals from simulation results. In contrast, two other force fields that we consider show little sign of aggregation for X(t) ? 0.08. In our 64,000 particle simulations all four models considered show demixing-like behavior for X(t) ? 0.1, although such behavior is not evident in smaller systems of 2000 particles. The meaning of the demixing-like behavior is unclear. Since real TBA-water solutions do not demix, it might be an indication that all four models we consider poorly represent the real system. Alternatively, it might be an artifact of finite system size. Possibly, the apparent demixing indicates that for X(t) ? 0.1, the stable TBA aggregates are simply too large to fit into the simulation cell. Our results provide a view of the possible nature of microheterogeneity in dilute TBA-water solutions, and of the associated long correlation lengths. It is clear that system size can be a very important factor in simulations of these solutions, and must be taken into account in the evaluation and development of TBA-water force fields. PMID:22830713

  12. Photoionization of methyl t-butyl ether (MTBE) and t-octyl methyl ether (TOME) and analysis of their pyrolyses by

    E-print Network

    Morton, Thomas Hellman

    Photoionization of methyl t-butyl ether (MTBE) and t-octyl methyl ether (TOME) and analysis 1999; accepted 20 July 1999 Abstract The pyrolysis products of neutral methyl-d3 t-butyl ether (MTBE-d3), its undeuterated analogue, and t-octyl methyl ether (TOME) have been analyzed by means of supersonic

  13. A novel practical cleavage of tert-butyl esters and carbonates using fluorinated alcohols

    Microsoft Academic Search

    Jason Choy; Saul Jaime-Figueroa; Teresa Lara-Jaime

    2010-01-01

    Thermolytic cleavage of t-butyl esters and t-butyl carbonates was accomplished using TFE (2,2,2-trifluoroethanol) or HFIP (hexafluoroisopropanol) as solvent. Thus, a practical method to cleanly convert t-butyl esters and carbonates into the corresponding carboxylic acids, decarboxylated products, or alcohols in nearly quantitative yields was developed. The product is recovered by a simple solvent evaporation. The practicality of this methodology was demonstrated

  14. Flame-ionization detector response to methyl, ethyl, propyl, and butyl esters of fatty acids

    Microsoft Academic Search

    Franz Ulberth; Robert G. Gabernig; Franz Schrammel

    1999-01-01

    The concept of theoretical response factors is not directly applicable to methyl esters of short-chain fatty acids (FA), since\\u000a their carbon deficiency is larger than expected from theory. Substituting the methyl group by an ethyl, propyl, or butyl group\\u000a improved the flame-ionization efficiency of fatty acid esters gradually, up to the point where the empirical response factors\\u000a of the butyl

  15. State Restrictions on Methyl Tertiary Butyl Ether (released in AEO2006)

    EIA Publications

    2006-01-01

    By the end of 2005, 25 states had barred, or passed laws banning, any more than trace levels of methyl tertiary butyl ether (MTBE) in their gasoline supplies, and legislation to ban MTBE was pending in 4 others. Some state laws address only MTBE; others also address ethers such as ethyl tertiary butyl ether (ETBE) and tertiary amyl methyl ether (TAME). Annual Energy Outlook 2006 assumes that all state MTBE bans prohibit the use of all ethers for gasoline blending.

  16. Sulfuric acid functional zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts for alkylation of phenol with tert-butyl alcohol

    NASA Astrophysics Data System (ADS)

    Jiang, Tingshun; Cheng, Jinlian; Liu, Wangping; Fu, Lie; Zhou, Xuping; Zhao, Qian; Yin, Hengbo

    2014-10-01

    Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO42-/Zr-MCM-48 and SO42-/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH3-TPD and N2 physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO42-/Zr-MCM-48 and SO42-/Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)-MCM-48 samples, SO42-/Zr-MCM-48 and SO42-/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO42-/Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h-1 and the reaction temperature is 140 °C.

  17. Delayed Treatment with ?-Phenyl- N- tert-butyl Nitrone (PBN) Attenuates Secondary Mitochondrial Dysfunction after Transient Focal Cerebral Ischemia in the Rat

    Microsoft Academic Search

    Satoshi Kuroda; Ken-ichiro Katsura; Lars Hillered; Timothy E. Bates; Bo K. Siesjö

    1996-01-01

    The present experiments were undertaken to explore the mechanisms of secondary brain damage in focal ischemia of long duration (2 h), followed by recirculation. Recirculation has previously been found to cause partial recovery and secondary deterioration of cellular bioenergetic state, the subsequent damage being ameliorated by a free radical spin trap, ?-phenyl-N-tert-butyl nitrone (PBN), even when the drug was given

  18. Singlet oxygen reactions of 3-methoxy-2-pyrrole carboxylic acid tert-butyl esters. A route to 5-substituted pyrrole precursors of prodigiosin and analogs

    Microsoft Academic Search

    Harry H. Wasserman; Mingde Xia; Jianji Wang; Anders K. Petersen; Michael Jorgensen; Patricia Power; Jonathan Parr

    2004-01-01

    Reaction of the tert-butyl ester of 3-methoxy-2-pyrrole carboxylic acid with singlet oxygen yields a peroxidic intermediate which undergoes coupling with a range of nucleophiles to yield 5-substituted pyrroles. Among these products are ?,??-bipyrroles which serve as precursors of prodigiosin, including A-ring substituted analogues.

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

    PubMed Central

    Ishida, Y.I.; Takikawa, M.; Suzuki, T.; Nagahama, M.; Ogasawara, Y.

    2014-01-01

    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. PMID:25379381

  20. Cytotoxicity of dihydroartemisinin toward Molt-4 cells attenuated by N-tert-butyl-alpha-phenylnitrone and deferoxamine.

    PubMed

    Chan, Ho Wing; Singh, Narendra P; Lai, Henry C

    2013-10-01

    Derivatives of artemisinin, a compound extracted from the wormwood Artemisia annua L, have potent anticancer properties. The anticancer mechanisms of artemisinin derivatives have not been fully-elucidated. We hypothesize that the cytotoxicity of these compounds is due to the free radicals formed by interaction of their endoperoxide moiety with intracellular iron in cancer cells. The effects of N-tert-butyl-alpha-phenylnitrone (PBN), a spin-trap free radical scavenger, and deferoxamine (DX), an iron chelating agent, on the in vitro cytotoxicity of dihyroartemisinin (DHA) toward Molt-4 human T-lymphoblastoid leukemia cells were investigated in the present study. Dihydroartemisinin effectively killed Molt-4 cells in vitro. Its cytotoxicity was significantly attenuated by PBN and DX. Based on the data of our present and previous studies, we conclude that one anticancer mechanism of dihydroartemisinin is the formation of toxic-free radicals via an iron-mediated process. PMID:24123007

  1. Carcinogenicity of methyl-tertiary butyl ether in gasoline.

    PubMed

    Mehlman, Myron A

    2002-12-01

    Methyl tertiary butyl ether (MTBE) was added to gasoline on a nationwide scale in 1992 without prior testing of adverse, toxic, or carcinogenic effects. Since that time, numerous reports have appeared describing adverse health effects of individuals exposed to MTBE, both from inhalation of fumes in the workplace and while pumping gasoline. Leakage of MTBE, a highly water-soluble compound, from underground storage tanks has led to contamination of the water supply in many areas of the United States. Legislation has been passed by many states to prohibit the addition of MTBE to gasoline. The addition of MTBE to gasoline has not accomplished its stated goal of decreasing air pollution, and it has posed serious health risks to a large portion of the population, particularly the elderly and those with respiratory problems, asthma, and skin sensitivity. Reports of animal studies of carcinogenicity of MTBE began to appear in the 1990s, prior to the widespread introduction of MTBE into gasoline. These reports were largely ignored. In ensuing years, further studies have shown that MTBE causes various types of malignant tumors in mice and rats. The National Toxicology Program (NTP) Board of Scientific Counselors' Report on Carcinogens Subcommittee met in December 1998 to consider listing MTBE as "reasonably anticipated to be a human carcinogen." In spite of recommendations from Dr. Bailer, the primary reviewer, and other scientists on the committee, the motion to list MTBE in the report was defeated by a six to five vote, with one abstention. On the basis of animal studies, it is widely accepted that if a chemical is carcinogenic in appropriate laboratory animal test systems, it must be treated as though it were carcinogenic in humans. In the face of compelling evidence, NTP Committee members who voted not to list MTBE as "reasonably anticipated to be a human carcinogen" did a disservice to the general public; this action may cause needless exposure of many to health risks and possibly cancers. PMID:12562634

  2. Regioselective hydrolysis of ketenimines derived from NH-acids and acetylenic esters in the presence of tert -butyl isocyanide under neutral conditions

    Microsoft Academic Search

    Farough Nasiri; Samiyeh Yosefdad

    2008-01-01

    The regioselective hydrolysis of ketenimines derived from NH-acids, such as 2,2,2-trichloro-N-phenylacetamide or ethyl-2-anilino-2-oxoacetates and acetylenic esters in the presence of tert-butyl isocyanide in a THF\\/H2O system (1\\/1) without any catalysis leads to a diastereomeric mixture of dialkyl 2-[(tert-butylamino)carbonyl]-3-[(2,2,2-trichloroacetyl)anilino]succinates and dialkyl 2-[(tert-butylamino)carbonyl]-3-[2-ethoxy-2-oxoacetyl)anilino]-succinates in good yields. Dynamic NMR effects were observed in the\\u000a 13C NMR spectra of diethyl 2-[(tert-butylamino)carbonyl]-3-[(2,2,2-trichloroacetyl)anilino]succinate as a result

  3. Separation of methyl t-butyl ether from close boiling C[sub 5] hydrocarbons by extractive distillation

    SciTech Connect

    Berg, L.

    1993-07-20

    A method for recovering methyl t-butyl ether from a mixture of methyl t-butyl ether and 1-pentene which comprises distilling a mixture of methyl t-butyl ether and 1-pentene in the presence of about one part of an extractive agent per part of methyl t-butyl ether -- 1-pentene mixture, recovering the 1-pentene as overhead product and obtaining the methyl t-butyl ether and the extractive agent from the still pot, wherein said extractive agent consists of one material selected from the group consisting of sulfolane, nitroethane, t-butanol, ethylene glycol diacetate, 1-methoxy-2-propanol acetate, methyl isoamyl ketone, ethylene glycol methyl ether, propylene glycol phenyl ether and diethyl malonate.

  4. Methyl t-Butyl Ether Mineralization in Surface-Water Sediment Microcosms under Denitrifying Conditions

    USGS Publications Warehouse

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

    2001-01-01

    Mineralization of [U-14C] methyl t-butyl ether (MTBE) to 14CO2 without accumulation of t-butyl alcohol (TBA) was observed in surface-water sediment microcosms under denitrifying conditions. Methanogenic activity and limited transformation of MTBE to TBA were observed in the absence of denitrification. Results indicate that bed sediment microorganisms can effectively degrade MTBE to nontoxic products under denitrifying conditions.

  5. HIGH LEVELS OF MONOAROMATIC COMPOUNDS LIMIT THE USE OF SOLID-PHASE MICROEXTRACTION OF METHYL TERTIARY BUTYL ETHER AND TERTIARY BUTYL ALCOHOL

    EPA Science Inventory

    Recently, two papers reported the use of solid-phase microextraction (SPME) with polydimethylsiloxane(PDMS)/Carboxen fibers to determine trace levels of methyl tertiary butyl ether (MTBE) and tertiary butyl alcohol (tBA) in water. Attempts were made to apply this technique to th...

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

    PubMed

    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. PMID:22161475

  7. Synthesis of high molecular weight poly(dialkyl fumarate)s bearing n -alkyl side chains from poly(di- tert -butyl fumarate) via olefin elimination and reesterification in a one-pot

    Microsoft Academic Search

    Takayuki Otsu; Masahiro Yoshioka; Akikazu Matsumoto; Kohei Shiraishi

    1991-01-01

    High molecular weight poly(dialkyl fumarate)s bearing n-alkyl esters such as an octadecyl group were prepared efficiently from poly(di-tert-butyl fumarate) by the one-pot synthesis, i.e. both elimination of isobutene from the tert-butyl ester and the subsequent esterification were performed in a corresponding alcohol at 170–180°C in a one-pot without isolating poly(fumaric acid). The resulting polymers were characterized by IR and NMR

  8. Neuroprotective effects of pterin-6-aldehyde in gerbil global brain ischemia: comparison with those of ?-phenyl- N- tert-butyl nitrone

    Microsoft Academic Search

    Hiroko Mori; Toshiyuki Arai; Hisanari Ishii; Takehiko Adachi; Nobuyuki Endo; Keisuke Makino; Kenjiro Mori

    1998-01-01

    The superoxide (O2??) scavenging activity and the neuroprotective effects of pterin-6-aldehyde (P6A), a xanthine oxidase inhibitor, were examined and compared with those of ?-phenyl-N-tert-butyl nitrone (PBN), a spin trapping agent. The scavenging activity of P6A was more potent than that of PBN by 150-fold in neutrophil\\/phorbol myristate acetate O2?? generating system. P6A attenuated the neuronal damage with a much smaller

  9. Combination Therapy with MK-801 and ?-Phenyl- tert-butyl-nitrone Enhances Protection against Ischemic Neuronal Damage in Organotypic Hippocampal Slice Cultures

    Microsoft Academic Search

    Alain Barth; Laurence Barth; David W. Newell

    1996-01-01

    In vitrocombinations of MK-801, an NMDA receptor antagonist, and ?-phenyl-tert-butyl-nitrone (PBN), a free radical scavenger, have been tested for possible additive neuroprotective effects against anoxia\\/hypoglycemia (Ax\\/Hg)-induced neuronal damage. Rat organotypic hippocampal slice cultures were exposed to Ax\\/Hg for different lengths of time to vary the severity of the insult. Cell death (CD) was assessed using propidium iodide fluorescence and expressed

  10. Neuroprotective effects of the novel brain-penetrating antioxidant U-101033E and the spin-trapping agent ?-phenyl- N - tert -butyl nitrone (PBN)

    Microsoft Academic Search

    Robert Schmid-Elsaesser; Edwin Hungerhuber; Stefan Zausinger; Alexander Baethmann; Hanns-Juergen Reulen

    2000-01-01

    Literature on the therapeutic efficacy of free radical scavengers suggests that drugs that are able to cross the blood-brain\\u000a barrier are more effective in protecting the brain from ischemic damage. However, the exact mechanisms by which brain-penetrating\\u000a antioxidants act have yet not been delineated. We compared the neuroprotective potential of the newly discovered pyrrolopyrimidine\\u000a U-101033E with that of ?-phenyl-N-tert-butyl nitrone

  11. Optimal Time and Dosage of Phenyl N- TertButyl Nitrone (PBN) for the Inhibition of Nitric Oxide Synthase Induction in Mice

    Microsoft Academic Search

    Takashi Miyajima; Yashige Kotake

    1997-01-01

    We have previously reported that phenyl N-tert-butyl nitrone (PBN) inhibits the induction of inducible nitric oxide synthase (iNOS) and, thus, prevents the overproduction of nitric oxide (NO), resulting in the reduction of endotoxin-mediated death in mice. In this study, to examine the effect of PBN in detail, we investigated the dose- and administration-timing dependence of PBN on endotoxin-induced NO generation

  12. Effects of combined postischemic hypothermia and delayed N- tert-butyl- a-pheylnitrone (PBN) administration on histopathological and behavioral deficits associated with transient global ischemia in rats

    Microsoft Academic Search

    Alejandra J. Pazos; Edward J. Green; Raul Busto; Philip M. McCabe; R. C. Baena; Myron D. Ginsberg; Mordecai Y.-T. Globus; Neil Schneiderman; W. Dalton Dietrich

    1999-01-01

    Previous cerebral ischemia studies have reported the limitations of restricted periods of postischemic hypothermia in producing long-term neuroprotection. The present experiment attempts to determine whether delayed treatment with the free radical scavenger N-tert-butyl-a-phenylnitrone (PBN) is protective at 2 months following transient global forebrain ischemia, and whether additive effects can be observed when PBN is administered in combination with moderate hypothermia.

  13. Effect of free radical spin trap N- tert-butyl-?-phenylnitrone (PBN) on seizures induced in immature rats by homocysteic acid

    Microsoft Academic Search

    Jaroslava Folbergrová; Rastislav Druga; Jakub Otáhal; Renata Haugvicová; Pavel Mareš; Hana Kubová

    2006-01-01

    The present study has examined the effect of free radical spin trap N-tert-butyl-?-phenylnitrone (PBN) in the model of seizures induced in immature 12-day-old rats by bilateral intracerebroventricular infusion of dl-homocysteic acid (dl-HCA, 600 nmol\\/side). PBN was given i.p. in two doses (100 mg\\/kg each), 30 min prior and 30 min after dl-HCA infusion. PBN did not significantly influence the severity of seizures, evident both

  14. Cloning of a Genetically Unstable Cytochrome P-450 Gene Cluster Involved in Degradation of the Pollutant Ethyl tertButyl Ether by Rhodococcus ruber

    Microsoft Academic Search

    SYLVIE CHAUVAUX; FABIEN CHEVALIER; CORINNE LE DANTEC; FRANCOISE FAYOLLE; ISABELLE MIRAS; FRANK KUNST; PIERRE BEGUIN

    2001-01-01

    Rhodococcus ruber (formerly Gordonia terrae) IFP 2001 is one of a few bacterial strains able to degrade ethyl tert-butyl ether (ETBE), which is a major pollutant from gasoline. This strain was found to undergo a spontaneous 14.3-kbp chromosomal deletion, which results in the loss of the ability to degrade ETBE. Sequence analysis of the region corresponding to the deletion revealed

  15. Demonstration of free radical generation in stunned myocardium of intact dogs with the use of the spin trap alpha-phenyl N-tert-butyl nitrone

    Microsoft Academic Search

    R. Bolli; B. S. Patel; M. O. Jeroudi; E. K. Lai; P. B. McCay

    1988-01-01

    Recent studies suggest that oxygen free radicals may mediate postischemic myocardial dysfunction (stunning), but all the evidence for this hypothesis is indirect. Thus, we used electron paramagnetic resonance (EPR) spectroscopy and the spin trap, alpha-phenyl N-tert-butyl nitrone (PBN), to directly investigate whether free radicals are produced after a 15-min coronary artery occlusion and subsequent reperfusion in 30 open-chest dogs. After

  16. Effect of anion fluorination in 1-ethyl-3-methylimidazolium as solvent for the liquid extraction of ethanol from ethyl tert-butyl ether

    Microsoft Academic Search

    Alberto Arce; Héctor Rodríguez; Ana Soto

    2006-01-01

    In this work, we have studied the use of homologous imidazolium-based ionic liquids (i.e. with the same fluorinated and non-fluorinated anion) to perform the separation of an ether and an alcohol. Concretely, we have selected ethyl tert-butyl ether (ETBE) and ethanol due to the capital interest of their industrial separation. Liquid–liquid equilibrium (LLE) data for the ternary systems involved are

  17. XPS study of the assembling morphology of 3-hydroxy-3-phosphono-butiric acid tert -butyl ester on variously pretreated Al surfaces

    Microsoft Academic Search

    O. L. Blajiev; A. Ithurbide; A. Hubin; C. Van Haesendonck; H. Terryn

    2008-01-01

    X-ray Photoelectron Spectroscopy (XPS) was used to study the deposition morphology of 3-hydroxy-3-phosphono-butiric acid tert-butyl ester on aluminium oxide. The deposition was investigated in connection with the acid–base properties of the oxide surface as defined by its hydroxyl concentration. Various pretreatments were applied on pure aluminium, and the XPS analysis showed that the hydroxyl content depended significantly on the pretreatment

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

    Microsoft Academic Search

    Chuan Liang Feng; G. Julius Vancso; Holger Schönherr

    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 angle measurements, a skin layer of acid-sensitive PtBA is present on the surface of PSn-b-PtBAm films, consistent with the lower surface

  19. Mechanistic Basis for Inflammation and Tumor Promotion in Lungs of 2,6Di tert -butyl-4-methylphenol-Treated Mice:  Electrophilic Metabolites Alkylate and Inactivate Antioxidant Enzymes

    Microsoft Academic Search

    Brent W. Meier; Jose D. Gomez; Oleg V. Kirichenko; John A. Thompson

    2007-01-01

    An established model for mechanistic analysis of lung carcinogenesis involves administration of 3-methylcholanthrene to mice followed by several weekly injections of the tumor promoter 2,6-di-tert- butyl-4-methylphenol (BHT). BHT is metabolized to quinone methides (QMs) responsible for promoting tumor formation. QMs are strongly electrophilic and readily form adducts with proteins. The goal of the present study was to identify adducted proteins

  20. Chlorido[2,3,5,6-tetra­kis­(tert-butyl­sulfanylmeth­yl)phenyl-?3 S 2,C 1,S 6]palladium(II) dichloro­methane monosolvate

    PubMed Central

    Paz-Morales, Evelyn; Hernández-Ortega, Simón; Morales-Morales, David

    2013-01-01

    The title compound, [Pd(C26H45S4)Cl]·CH2Cl2, crystallizes with a disordered dichloro­methane solvent mol­ecule [occupancy ratio = 0.67?(4):0.33?(4)]. Two of the tert-butyl groups are also disordered [occupancy ratios = 0.70?(5):0.30?(5) and 0.63?(4):0.37?(4)]. Although the pincer ligand offers the possibility for coordination of two different metal atoms, the present structure shows only the coordination of a single PdII atom in a typical S—C—S tridentate pincer manner. The PdII atom is in a slightly distorted square-planar environment with the two tert-butyl­sulfanyl groups arranged in a trans con­formation and with a chloride ligand trans to the ?-bonded aromatic C atom. The structure exhibits a durene-like ligand frame, forming a dihedral angle of 13.6?(4)° with the metal coordination (Pd/S/S/Cl/C) environment. It is noteworthy that the tert-butyl groups are found in a syn arrangement, this being different to that found previously by Loeb, Shimizu & Wisner [(1998). Organometallics, 17, 2324–2327]. PMID:23476488

  1. Chlorido[2,3,5,6-tetra-kis-(tert-butyl-sulfanylmeth-yl)phenyl-?(3) S (2),C (1),S (6)]palladium(II) dichloro-methane monosolvate.

    PubMed

    Paz-Morales, Evelyn; Hernández-Ortega, Simón; Morales-Morales, David

    2013-03-01

    The title compound, [Pd(C26H45S4)Cl]·CH2Cl2, crystallizes with a disordered dichloro-methane solvent mol-ecule [occupancy ratio = 0.67?(4):0.33?(4)]. Two of the tert-butyl groups are also disordered [occupancy ratios = 0.70?(5):0.30?(5) and 0.63?(4):0.37?(4)]. Although the pincer ligand offers the possibility for coordination of two different metal atoms, the present structure shows only the coordination of a single Pd(II) atom in a typical S-C-S tridentate pincer manner. The Pd(II) atom is in a slightly distorted square-planar environment with the two tert-butyl-sulfanyl groups arranged in a trans con-formation and with a chloride ligand trans to the ?-bonded aromatic C atom. The structure exhibits a durene-like ligand frame, forming a dihedral angle of 13.6?(4)° with the metal coordination (Pd/S/S/Cl/C) environment. It is noteworthy that the tert-butyl groups are found in a syn arrangement, this being different to that found previously by Loeb, Shimizu & Wisner [(1998). Organometallics, 17, 2324-2327]. PMID:23476488

  2. Biotic and Abiotic Transformations of Methyl tertiary Butyl Ether (MTBE) * (6 pp)

    Microsoft Academic Search

    Axel Fischer; Claudia Oehm; Michael Selle; Peter Werner

    2005-01-01

    Background. Methyl tertiary butyl ether (MTBE) is a fuel additive which is used all over the world. In recent years it has often been found in groundwater, mainly in the USA, but also in Europe. Although MTBE seems to be a minor toxic, it affects the taste and odour of water at concentrations of < 30 µg\\/L. Although MTBE is

  3. DERMAL, ORAL AND INHALATION PHARMACOKINETICS OF METHYL TERTIARY-BUTYL ETHER (MTBE) IN HUMAN VOLUNTEERS

    EPA Science Inventory

    Methyl tertiary butyl ether (MTBE), a gasoline additive used to increase octane and reduce carbon monoxide emissions and ozone precursors, has contaminated drinking water and can lead to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhal...

  4. REFINED PBPK MODEL OF AGGREGATE EXPOSURE TO METHYL TERTIARY-BUTYL ETHER

    EPA Science Inventory

    Aggregate (multiple pathway) exposures to methyl tertiary-butyl ether (MTBE) in air and water occur via dermal, inhalation, and oral routes. Previously, physiologically-based pharmacokinetic (PBPK) models have been used to quantify the kinetic behavior of MTBE and its primary met...

  5. DERMAL, ORAL, AND INHALATION PHARMACOKINETICS OF METHYL TERTIARY BUTYL ETHER (MTBE) IN HUMAN VOLUNTEERS

    EPA Science Inventory

    Methyl tertiary butyl ether (MTBE), a gasoline additive, used to increase octane and reduce carbon monoxide emissions and ozone precursors has contaminated drinking water leading to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhalation ki...

  6. Enhanced diisobutene production in the presence of methyl tertiary butyl ether

    DOEpatents

    Smith, L.A. Jr.

    1983-03-01

    In the liquid phase reaction of isobutene in the presence of resin cation exchange resins with itself in a C[sub 4] hydrocarbon stream to form dimers, the formation of higher polymers, oligomers, and co-dimer by-products is suppressed by the presence of 0.0001 to 1 mole per mole of isobutene of methyl tertiary butyl ether. 1 fig.

  7. Enhanced diisobutene production in the presence of methyl tertiary butyl ether

    DOEpatents

    Smith, Jr., Lawrence A. (Bellaire, TX)

    1983-01-01

    In the liquid phase reaction of isobutene in the presence of resin cation exchange resins with itself in a C.sub.4 hydrocarbon stream to form dimers, the formation of higher polymers, oligomers, and co-dimer by-products is suppressed by the presence of 0.0001 to 1 mole per mole of isobutene of methyl tertiary butyl ether.

  8. Effect of lithium chloride on the living polymerization of tert-butyl methacrylate and polymer microstructure using monofunctional initiators

    SciTech Connect

    Varshney, S.K. (Rt Polymer Source Inc., Pointe-Claire, Quebec (Canada)); Gao, Z. (Imperial Oil Ltd., Sarnia, Ontario (Canada). Research Dept.); Zhong, Xing Fu; Eisenberg, A. (McGill Univ., Montreal, Quebec (Canada). Dept. of Chemistry)

    1994-02-28

    The effect of LiCl on the anionic polymerization of tert-butyl methacrylate (tBuMA) initiated with monofunctional alkali metal-based carbanionic species was investigated at [minus]78 C in THF. The propagation rate of the polymerization process was determined by gas chromatography and by gravimetry. It was found that, in the presence of LiCl in a molar ratio of 5 with respect to the initiator, the rate constant, k[sub p], is 20 times lower than that in the absence of LiCl. The polymers and oligomers were analyzed by size exclusion chromatography (SEC) and [sup 13]C NMR spectroscopy. The polymers obtained in the absence of LiCl had broad molecular weight distributions and contained significant amounts of oligomers, while those obtained in the presence of LiCl were monodisperse, without any noticeable oligomers. [sup 13]C NMR showed that the isotactic content of the polymers increased significantly when the molar ratio of LiCl to the initiator was higher than 2. The effect of LiCl on the rate constant and on the microstructure of the polymers was attributed to complex formation between LiCl and the living polymer chains.

  9. The effect of tert-butyl hydroperoxide-induced oxidative stress on lean and steatotic rat hepatocytes in vitro.

    PubMed

    Ku?era, Otto; Endlicher, René; Roušar, Tomáš; Lotková, Halka; Garnol, Tomáš; Drahota, Zden?k; Cervinková, Zuzana

    2014-01-01

    Oxidative stress and mitochondrial dysfunction play an important role in the pathogenesis of nonalcoholic fatty liver disease and toxic liver injury. The present study was designed to evaluate the effect of exogenous inducer of oxidative stress (tert-butyl hydroperoxide, tBHP) on nonfatty and steatotic hepatocytes isolated from the liver of rats fed by standard and high-fat diet, respectively. In control steatotic hepatocytes, we found higher generation of ROS, increased lipoperoxidation, an altered redox state of glutathione, and decreased ADP-stimulated respiration using NADH-linked substrates, as compared to intact lean hepatocytes. Fatty hepatocytes exposed to tBHP exert more severe damage, lower reduced glutathione to total glutathione ratio, and higher formation of ROS and production of malondialdehyde and are more susceptible to tBHP-induced decrease in mitochondrial membrane potential. Respiratory control ratio of complex I was significantly reduced by tBHP in both lean and steatotic hepatocytes, but reduction in NADH-dependent state 3 respiration was more severe in fatty cells. In summary, our results collectively indicate that steatotic rat hepatocytes occur under conditions of enhanced oxidative stress and are more sensitive to the exogenous source of oxidative injury. This confirms the hypothesis of steatosis being the first hit sensitizing hepatocytes to further damage. PMID:24847414

  10. The Effect of tert-Butyl Hydroperoxide-Induced Oxidative Stress on Lean and Steatotic Rat Hepatocytes In Vitro

    PubMed Central

    Ku?era, Otto; Endlicher, René; Roušar, Tomáš; Lotková, Halka; Garnol, Tomáš; Drahota, Zden?k

    2014-01-01

    Oxidative stress and mitochondrial dysfunction play an important role in the pathogenesis of nonalcoholic fatty liver disease and toxic liver injury. The present study was designed to evaluate the effect of exogenous inducer of oxidative stress (tert-butyl hydroperoxide, tBHP) on nonfatty and steatotic hepatocytes isolated from the liver of rats fed by standard and high-fat diet, respectively. In control steatotic hepatocytes, we found higher generation of ROS, increased lipoperoxidation, an altered redox state of glutathione, and decreased ADP-stimulated respiration using NADH-linked substrates, as compared to intact lean hepatocytes. Fatty hepatocytes exposed to tBHP exert more severe damage, lower reduced glutathione to total glutathione ratio, and higher formation of ROS and production of malondialdehyde and are more susceptible to tBHP-induced decrease in mitochondrial membrane potential. Respiratory control ratio of complex I was significantly reduced by tBHP in both lean and steatotic hepatocytes, but reduction in NADH-dependent state 3 respiration was more severe in fatty cells. In summary, our results collectively indicate that steatotic rat hepatocytes occur under conditions of enhanced oxidative stress and are more sensitive to the exogenous source of oxidative injury. This confirms the hypothesis of steatosis being the first hit sensitizing hepatocytes to further damage. PMID:24847414

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

    PubMed Central

    Ivanova, Elena P; Mitik-Dineva, Natasa; Mocanasu, Radu C; Murphy, Sarah; Wang, James; van Riessen, Grant; Crawford, Russell J

    2008-01-01

    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. PMID:24198459

  12. Protective effects of alkaloid compounds from Nelumbinis Plumula on tert-butyl hydroperoxide-induced oxidative stress.

    PubMed

    Xie, Yong; Zhang, Yi; Zhang, Long-Tao; Zeng, Shao-Xiao; Guo, Ze-Bin; Zheng, Bao-Dong

    2013-01-01

    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. PMID:24064445

  13. Conformational stability, vibrational and NMR analysis, chemical potential and thermodynamical parameter of 3-tert-butyl-4-hydroxyanisole.

    PubMed

    Balachandran, V; Karpagam, V; Revathi, B; Kavimani, M; Santhi, G

    2015-01-25

    The FT-IR and FT-Raman spectra of 3-tert-butyl-4-hydroxyanisole (TBHA) molecule have been recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. Optimized geometrical structure, harmonic vibrational frequencies has been computed by B3LYP level using 6-31G (d,p) and 6-311+G (d,p) basis sets. The observed FT-IR and FT-Raman vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The Mulliken charges, the natural bonding orbital (NBO) analysis, the first-order hyperpolarizability of the investigated molecule were computed using DFT calculations. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) were calculated and analyzed. The isotropic chemical shift computed by (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the TBHA calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations. PMID:25173520

  14. Conformational stability, vibrational and NMR analysis, chemical potential and thermodynamical parameter of 3-tert-butyl-4-hydroxyanisole

    NASA Astrophysics Data System (ADS)

    Balachandran, V.; Karpagam, V.; Revathi, B.; Kavimani, M.; Santhi, G.

    2015-01-01

    The FT-IR and FT-Raman spectra of 3-tert-butyl-4-hydroxyanisole (TBHA) molecule have been recorded in the region 4000-400 cm-1 and 3500-100 cm-1, respectively. Optimized geometrical structure, harmonic vibrational frequencies has been computed by B3LYP level using 6-31G (d, p) and 6-311 + G (d, p) basis sets. The observed FT-IR and FT-Raman vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The Mulliken charges, the natural bonding orbital (NBO) analysis, the first-order hyperpolarizability of the investigated molecule were computed using DFT calculations. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) were calculated and analyzed. The isotropic chemical shift computed by 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the TBHA calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations.

  15. A COMPARISON OF LIQUID AND GAS-PHASE PHOTOOXIDATION TREATMENT OF METHYL TERTIARY BUTYL ETHER: SYNTHETIC AND FIELD SAMPLES

    EPA Science Inventory

    The feasibility of photo-oxidation treatment of metyl tert-butyl either (MTBE) in water was investigated using two systems, 1) a slurry falling film photo-reactor, and 2) an integrated air-stripping with gas phase photooxidation system. MTBE-contaminated synthetic water and field...

  16. Hydrogen Oxidation Catalysis by a Nickel Diphosphine Complex with Pendant tert-Butyl Amines

    SciTech Connect

    Yang, Jenny Y.; Chen, Shentan; Dougherty, William G.; Kassel, W. S.; Bullock, R. Morris; DuBois, Daniel L.; Raugei, Simone; Rousseau, Roger J.; Dupuis, Michel; Rakowski DuBois, Mary

    2010-11-09

    A bis-diphosphine nickel complex with t-butyl functionalized pendant amines [Ni(PCy2Nt-Bu2)2]2+ has been synthesized. It is a highly active electrocatalyst for the oxidation of hydrogen in the presence of base. The turn-over rate of 50 s 1 under 1.0 atm H2 at a potential of –0.77 V vs the ferrocene couple is 5 times faster than the rate reported heretofore for any other molecular H2 oxidation catalyst. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. Computational resources were provided by the Environmental Molecular Science Laboratory (EMSL) and the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory.

  17. In vivo protective effect of protocatechuic acid on tert-butyl hydroperoxide-induced rat hepatotoxicity.

    PubMed

    Liu, Chuen-Lan; Wang, Jin-Ming; Chu, Chia-Yih; Cheng, Ming-Tzong; Tseng, Tsui-Hwa

    2002-05-01

    Increasing evidence regarding free-radical generating agents and the inflammatory process suggests that accumulation of reactive oxygen species (ROS) can involve hepatotoxicity. Previously, we found that protocatechuic acid (PCA), a polyphenolic compound from Hibiscus sabdariffa L. possessing free radical-scavenging capacity, protected against oxidative damage induced by tert-butylhydroperoxide (t-BHP) in rat primary hepatocytes. In this study, first PCA was evaluated by its capacity of inhibiting xanthine oxidase (XO) and lipoxygenase (LO) activity in vitro, then it was used to induce hepatotoxicity to assess the antioxidant and anti-inflammatory bioactivity of PCA in vivo. Our investigation showed that pretreatment with PCA (50-100 mg/kg) by gavage for 5 days before a single dose of t-BHP (ip; 0.2 mmol/kg ) significantly lowered serum levels of the hepatic enzyme markers lactate dehydrogenase (LDH) and alanine (ALT) and aspartate (AST) aminotransferase, and reduced oxidative stress of the liver by evaluating malondialdehyde (MDA) and glutathione (GSH). Histopathological evaluation of the rat livers revealed that PCA reduced the incidence of liver lesions, including hepatocyte swelling, leukocyte infiltration, and necrosis induced by t-BHP. In addition, PCA inhibited t-BHP-induced tyrosine phosphorylation, an implication of the activation of a stress signal pathway, in the liver. These results indicate that PCA protects against t-BHP-induced hepatotoxicity by its antioxidant and anti-inflammatory characteristics accompanied by blocking of stress signal transduction. PMID:11955669

  18. Gamma radiolysis of methyl t-butyl ether: a study of hydroxyl radical mediated reaction pathways

    NASA Astrophysics Data System (ADS)

    Wu, Taixing; Cruz, Vivian; Mezyk, Stephen; Cooper, William J.; O'Shea, Kevin E.

    2002-11-01

    The reactions of hydroxyl radicals with methyl t-butyl ether (MTBE) were studied using gamma radiolysis. Aqueous solutions of 100 ppm MTBE were saturated with 4:1 N 2O/O 2 gas mixture prior to irradiation. Under these conditions hydroxyl radical is the predominant reactive species generated during gamma radiolysis. Complete degradation of MTBE is achieved within ˜30 min of irradiation at a dose rate of 0.21 kGy/min. The major volatile organic compounds (VOCs) produced are t-butyl formate (TBF), t-butyl alcohol (TBA), acetone, and methyl acetate. Under the reaction conditions, TBF does not yield TBA, but rather acetone as the primary reaction product. The formation of TBA by hydrolysis of TBF and a hemiacetal formed during the initial oxidative processes of MTBE appear to be minor reaction pathways. Although 2-methyl-2-methoxyl-propionaldehyde (MMP) has been proposed as a reaction product, we were unable to confirm its existence and we therefore, propose a reaction pathway, which does not involve MMP, as the predominant path leading to the formation of methyl acetate. The overall yields of VOCs are low with maximum individual yields between 4% and 13%. Upon extended treatment with gamma radiolysis the VOCs can be completely degraded. These studies contribute to a better fundamental understanding of the reactions of hydroxyl radicals with MTBE, and the resulting oxidation products, TBF and TBA.

  19. Interleukin-1?-induced brain injury in the neonatal rat can be ameliorated by ?-phenyl-n-tert-butyl-nitrone

    PubMed Central

    Fan, Lir-Wan; Mitchell, Helen J.; Tien, Lu-Tai; Rhodes, Philip G.; Cai, Zhengwei

    2009-01-01

    To examine the possible role of inflammatory cytokines in mediating perinatal brain injury, we investigated effects of intracerebral injection of interleukin-1beta (IL-1?) on brain injury in the neonatal rat and the mechanisms involved. Intracerebral administration of IL-1? (1 ?g/kg) resulted in acute brain injury, as indicated by enlargement of ventricles bilaterally, apoptotic death of oligodendrocytes (OLs) and loss of OL immunoreactivity in the neonatal rat brain. IL-1? also induced axonal and neuronal injury in the cerebral cortex as indicated by elevated expression of ?-amyloid precursor protein, short beaded axons and dendrites, and loss of tyrosine hydroxylase positive neurons in the substantia nigra and the ventral tegmental areas. Administration of ?-phenyl-n-tert-butyl-nitrone (PBN, 100 mg/kg i.p.) immediately after the IL-1? injection protected the brain from IL-1?-induced injury. Protection of PBN was linked with the attenuated oxidative stress induced by IL-1?, as indicated by decreased elevation of 8-isoprostane content and by the reduced number of 4-hydroxynonenal or malondialdehyde or nitrotyrosine positive cells following IL-1? exposure. PBN also attenuated IL-1?-stimulated inflammatory responses as indicated by the reduced activation of microglia. The finding that IL-1? induced perinatal brain injury was very similar to that induced by lipopolysaccharide (LPS), as we previously reported and that PBN was capable to attenuate the injury induced by either LPS or IL-1? suggests that IL-1? may play a critical role in mediating brain injury associated with perinatal infection/inflammation. PMID:19682987

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

    NASA Astrophysics Data System (ADS)

    Nielsen, Ole J.; Sehested, Jens; Langer, Sarka; Ljungström, Evert; Wängberg, Ingvar

    1995-06-01

    Alkyl, (CH 3) 3COC(CH 3) 2CH 2, and alkyl peroxy, (CH 3) 3COC(CH 3) 2CH 2O 2, 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, ?(CH 3) 3COC(CH 3) 2CH 2 = (3.6 ± 0.4) × 10 -18 cm 2 molecule -1 and at 260 nm, ?(CH 3) 3COC(CH 3) 2CH 2O 2 = (3.8 ± 0.3) × 10 -18 cm 2 molecule -1 have been obtained. The observed rate constants for the self-reaction of (CH 3) 3COC(CH 3) 2CH 2 and (CH 3) 3COC(CH 3) 2CH 2O 2 radicals were found to be (2.9 ± 0.2) × 10 -11 cm 3 molecule -1 s -1 and (2.7 ± 0.2) × 10 -12 cm 3 molecule -1 s -1, respectively. For the reaction of the alkyl radical with O 2 in 1 atm pressure of SF 6 a rate constant of (7.2 ± 1.1) × 10 -13 cm 3 molecule -1 s -1 was found. The rate constants for the reaction of the alkyl peroxy radicals with NO and NO 2 were determined to be (1.8 ± 0.2) × 10 -12 and (9.9 ± 1.3) × 10 -12 cm 3 molecule -1 s -1, respectively. As a part of the work the rate constants k(F + DTBE) and k(O + DTBE) were determined to be (2.6 ± 0.6) × 10 -10 and (4.0 ± 0.9) × 10 -12 cm 3 molecule -1 s -1, respectively.

  1. Chemical Synthesis of beta-Homonojirimycin, of Its N-Butyl Derivative, and of "Methyl Homoazacellobioside"

    PubMed

    Saavedra, Oscar M.; Martin, Olivier R.

    1996-10-01

    beta-Homonojirimycin (2) was prepared by the highly stereoselective double reductive amination of a 2,6-heptodiulose derivative (6 or 13) using ammonium formate and NaBH(3)CN. The process was unsuccessful with primary amines. The synthesis of N-butyl-beta-homonojirimycin (19) was achieved by the N-butanoylation of a derivative of 2 followed by the reduction of the resulting tertiary amide. Compound 19 was found to be completely devoid of anti-HIV activity, in marked contrast with N-butyl-1-deoxynojirimycin. The coupling of the 1-O-p-toluenesulfonyl derivative of 2, compound 20, with methyl 2,3,6-tri-O-benzyl-alpha-D-glucopyranoside, followed by a deprotection step, provided pseudodisaccharide 23, the "homoaza" analog of methyl alpha-cellobioside and a potential inhibitor of beta-glucan-processing enzymes. PMID:11667597

  2. Biodegradation of methyl t-butyl ether by pure bacterial cultures

    Microsoft Academic Search

    K. Mo; C. O. Lora; A. E. Wanken; M. Javanmardian; X. Yang; C. F. Kulpa

    1997-01-01

    Three pure bacterial cultures degrading methyl t-butyl ether (MTBE) were isolated from activated sludge and fruit of the Gingko tree. They have been classified as belonging\\u000a to the genuses Methylobacterium, Rhodococcus, and Arthrobacter. These cultures degraded 60?ppm MTBE in 1–2 weeks of incubation at 23–25?°C. The growth of the isolates on MTBE as sole carbon\\u000a source is very slow compared

  3. Dermal, Oral, and Inhalation Pharmacokinetics of Methyl Tertiary Butyl Ether (MTBE) in Human Volunteers

    Microsoft Academic Search

    James Prah; David Ashley; Benjamin Blount; Martin Case; Teresa Leavens; Joachim Pleil; Frederick Cardinali

    2004-01-01

    Methyl tertiary butyl ether (MTBE), a gasoline additive used to increase octane and reduce carbon monoxide emissions and ozone precursors, has contaminated drinking water and can lead to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhalation kinetics, 14 volunteers were exposed to 51.3 g\\/ml MTBE dermally in tap water for 1 h, drank 2.8

  4. Tetra-n-butyl­ammonium iodido(pyrrolidine-1-carbodithio­ato-?2 S,S?)(tris-tert-butoxy­silanethiol­ato-?S)cadmate(II)

    PubMed Central

    Kropid?owska, Anna; Chojnacki, Jaros?aw; Becker, Barbara

    2008-01-01

    In the anion of the title compound, (C16H36N)[Cd(C5H8NS2)(C12H27O3SSi)I], the Cd atom is four-coordinated by S,S?-chelating dithio­carbamate, S–donating silanethiol­ate and iodide ligands in a distorted tetrahedral environment . Inter­molecular C—H? S and C—H?I inter­actions between cations and anions are present. Two C atoms of a tert-butyl group are disordered over two positions; the site occupancies are ca 0.65 and 0.35. PMID:21202513

  5. Synthesis and properties of optically active nanostructured polymers bearing amino acid moieties by direct polycondensation of 4,4?-thiobis(2- tert -butyl-5-methylphenol) with chiral diacids

    Microsoft Academic Search

    Shadpour Mallakpour; Samaneh Soltanian

    Four derivatives of N-trimellitylimido-l-amino acid (4a–4d) were prepared by the reaction of trimellitic anhydride (1) with the l-amino acids (2a–2d) in acetic acid as diacid monomers and were used with the aim to obtain a new family of amino acid based\\u000a poly(ester-imide)s (PEI)s. The polymerization was performed by direct polycondensation of chiral diacids (4a–4d) with 4,4?-thiobis(2-tert-butyl-5-methylphenol) (5) in the presence

  6. Fabrication and in vitro degradation study of novel optically active polymers derived from amino acid containing diacids and 4,4?-thiobis(2-tert-butyl-5-methylphenol)

    Microsoft Academic Search

    Shadpour Mallakpour; Samaneh Soltanian; Mohammad Reza Sabzalian

    Chiral bioactive poly(ester-imide)s (PEI)s were synthesized from N,N?-(pyromellitoyl)-bis-(L-phenylalanine) and N,N?-(pyromellitoyl)-bis-(L-leucine) diacids derived from amino acids with 4,4?-thiobis(2-tert-butyl-5-methylphenol) via direct\\u000a polycondensation reaction in a system of tosyl chloride, pyridine and N,N-dimethylformamide as a condensing agent. The structures of these polymers were confirmed by FT-IR, 1H-NMR, specific rotation, elemental and thermogravimetric analysis (TGA) techniques. TGA showed that the 10% weight loss temperature

  7. Synthesis of substituted ( S)-2-aminotetralins via ring-opening of aziridines prepared from l-aspartic acid ?- tert-butyl ester

    Microsoft Academic Search

    Jon Erik Aaseng; Odd R. Gautun

    2010-01-01

    This paper describes the total synthesis of the hydrochloride salts of (2S)-2-amino-7-methoxytetralin (21-HCl) and (2S)-2-amino-6-fluoro-7-methoxytetralin (ST1214), from a common enantiomerically pure aziridine 4b, which was available from l-aspartic acid ?-tert-butyl ester. The synthesis of 21-HCl and ST1214 proceeded in nine steps and 5 and 6% overall yields, respectively. Key steps are the regioselective ring-opening of 4b with ArMgBr\\/CuBr·SMe2 and the

  8. Azobenzene versus 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) at Au(111): Characterizing the role of spacer groups

    E-print Network

    McNellis, Erik R; Meyer, Jorg; Weinelt, Martin; Tegeder, Petra; Reuter, Karsten; 10.1039/c001978j

    2011-01-01

    We present large-scale density-functional theory (DFT) calculations and temperature programmed desorption measurements to characterize the structural, energetic and vibrational properties of the functionalized molecular switch 3,3',5,5'-tetra-tert-butyl-azobenzene (TBA) adsorbed at Au(111). Particular emphasis is placed on exploring the accuracy of the semi-empirical dispersion correction approach to semi-local DFT (DFT-D) in accounting for the substantial van der Waals component in the surface chemical bond. In line with previous findings for benzene and pure azobenzene at coinage metal surfaces, DFT-D significantly overbinds the molecule, but seems to yield an accurate adsorption geometry as far as can be judged from the experimental data. Comparing the trans adsorption geometry of TBA and azobenzene at Au(111) reveals a remarkable insensitivity of the structural and vibrational properties of the -N=N- moiety. This questions the established view of the role of the bulky tert-butyl-spacer groups for the swit...

  9. Solid phase microextraction procedure for the determination of alkylphenols in water by on-fiber derivatization with N-tert-butyl-dimethylsilyl-N-methyltrifluoroacetamide.

    PubMed

    Pan, Yi-Ping; Tsai, Shih-Wei

    2008-08-29

    The solid phase microextraction (SPME) technique with on-fiber derivatization was evaluated for the analysis of alkylphenols (APs), including 4-tert-octylphenol (4-t-OP), technical nonylphenol isomers (t-NPs) and 4-nonylphenol (4-NP), in water. The 85 microm polyacrylate (PA) fiber was used and a two-step sample preparation procedure was established. In the first step, water sample of 2 mL was placed in a 4 mL PTFE-capped glass vial. Headspace extraction of APs in water was then performed under 65 degrees C for 30 min with 800 rpm magnetic stirring and the addition of 5% of sodium chloride. In the second step, the SPME fiber was placed in another 4 mL vial, which contained 100 microL of N-tert-butyl-dimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) with 1% tert-butyl-dimethylchlorosilane (TBDMCS). Headspace extraction of MTBSTFA and on-fiber derivatization with APs were performed at 45 degrees C for 10 min. Gas chromatography/mass spectrometry (GC/MS) was used for the analysis of derivatives formed on-fiber. The adsorption-time profiles were also examined. The precision, accuracy and method detection limits (MDLs) for the analysis of all the APs were evaluated with spiked water samples, including detergent water, chlorinated tap water, and lake water. The relative standard deviations were all less than 10% and the accuracies were 100+/-15%. With 2 mL of water sample, MDLs were in the range of 1.58-3.85 ng L(-1). Compared with other techniques, the study described here provided a simple, fast and reliable method for the analysis of APs in water. PMID:18706331

  10. Ab initio study of the selective alkylation of m-cresol with tert-butanol catalyzed by SO 3H-functionalized ionic liquids

    Microsoft Academic Search

    Jinxia Zhou; Xiumei Liu; Shuguang Zhang; Jingbo Mao; Xinwen Guo

    2010-01-01

    Our previous work showed that for catalytic alkylation of m-cresol with tert-butanol (TBA) SO3H-functionalized ionic liquids exhibited several characteristic advantages over conventional catalysts. This work investigated the reaction mechanism of the alkylation of m-cresol with tert-butanol catalyzed by the SO3H-functionalized ionic liquid (IL) through quantum chemical calculation in combination with the experimental studies. The experimental results showed that 2-tert-butyl-5-methyl phenol

  11. Pharmacokinetics and disposition of methyl t-butyl ether in Fischer-344 rats.

    PubMed

    Miller, M J; Ferdinandi, E S; Klan, M; Andrews, L S; Douglas, J F; Kneiss, J J

    1997-05-01

    Methyl t-butyl ether (MTBE) is a commonly used octane booster in gasoline. This study examines the pharmacokinetics and disposition of MTBE in Fischer-344 rats after i.v., oral, dermal and inhalation routes of administration. Groups of male and female rats were given single i.v. (40 mg kg-1), oral (40 and 400 mg kg-1) and dermal (40 and 400 mg kg-1 in occluded chambers) doses of [14C]MTBE. For inhalation studies, rats were exposed nose-only for 6 h to low (400 ppm), high (8000 ppm) and repeated daily 6-h low (400 ppm x 15 days) chamber concentrations of [14C]MTBE. Blood, expired air, and excreta (urine and feces) were collected at selected times up to 7 days post-dose and quantified for 14C content. Plasma concentrations of MTBE and t-butyl alcohol (TBA) were quantified and mean values used for pharmacokinetic analysis. The mean total recoveries of 14C ranged from 91 to 105%. Methyl t-butyl ether was rapidly and completely absorbed after oral and inhalation exposures; dermal absorption was low. After all routes, MTBE was rapidly eliminated from blood (ti = 0.5 h) by exhalation and metabolism to TBA. At the high doses, metabolism was saturated and the proportion of renal 14C excretion decreased relative to the pulmonary route. At 48 h post-exposure, virtually all of the 14C was eliminated. The major metabolites recovered in urine were 2-methyl-1,2-propanediol and alpha-hydroxyisobutyric acid. There were no significant gender or route-dependent differences in the pharmacokinetics and disposition of MTBE. PMID:9179722

  12. Isobaric vapor-liquid equilibria in the system methyl propanoate + n-butyl alcohol

    SciTech Connect

    Susial, P.; Ortega, J. (Univ. de Las Palmas de Gran Canaria, Canary Islands (Spain). Lab. de Termodinamica y Fisicoquimica)

    1993-10-01

    Isobaric vapor-liquid equilibria were determined at 74.66, 101.32, and 127.99 kPa for binary mixtures containing methyl propanoate + n-butyl alcohol by using a dynamic still with vapor and liquid circulation. No azeotrope was detected. The data were found to be thermodynamically consistent according to the point to point test. Application of the group-contribution models ASOG, UNIFAC, and modified UNIFAC to the activity coefficients at the three pressures studied gives average errors of less than 10%, 11%, and 3%, respectively.

  13. Oxidation of methyl- and ethyl- tertiary-butyl ethers in rat liver microsomes: role of the cytochrome P450 isoforms

    Microsoft Academic Search

    Alessandra Turini; Giada Amato; Vincenzo Longo; Pier Giovanni Gervasi

    1998-01-01

    Methyl t-butyl ether (MTBE) and ethyl t-butyl ether (ETBE) are commonly used in unleaded gasoline to increase the oxygen\\u000a content of fuel and to reduce carbon monoxide emissions from motor vehicles. This study was undertaken to investigate: (1)\\u000a the effect of administration to rats of ETBE and its metabolite, t-butanol, on the induction and\\/or inhibition of hepatic\\u000a P450 isoenzymes; (2)

  14. Activation of a carboxy group by dialkyl pyrocarbonates. Synthesis of symmetrical anhydrides and aryl esters of N-protected amino acids using di-tert-butyl pyrocarbonate as condensing reagent

    Microsoft Academic Search

    V. F. Pozdnev; M. Yu. Chernaya

    1984-01-01

    It has been shown that di-tert-butyl pyrocarbonate can be used as a condensing reagent in the production of anhydrides and some aryl esters of carboxylic acids. The synthesis of anhydrides and of phenyl, p-nitrophenyl, ß-naphthyl, and quinolin-8-yl esters of N-protected amino acids is described.

  15. Structural characterization of hydroxyl terminated polybutadiene bound 2, 2-thiobis (4-methyl-6-tert-butylphenol) and its thermo-oxidative aging resistance for natural rubber vulcanizates

    Microsoft Academic Search

    YONGHONG WANG; XINGRONG ZENG; HONGQIANG LI; JIANHUA GUO

    2012-01-01

    A novel polymeric antioxidant, hydroxyl terminated polybutadiene bound 2, 2-thiobis (4-methyl-6-tert-butylphenol) (HTPB-IPDI-TPH), was prepared by binding 2, 2-thiobis (4-methyl-6-tert-butylphenol) (TPH) onto hydroxyl terminated polybutadiene (HTPB) with isophorone diisocyanate (IPDI). Fourier-transform infrared spectroscopy (FTIR), C nuclear magnetic resonance spectroscopy (C NMR) and gel permeation chromatography (GPC) were used to characterize the structure of HTPB-IPDI-TPH. The thermal stability of HTPB-IPDI-TPH was studied

  16. Protective effect of ganodermanondiol isolated from the Lingzhi mushroom against tert-butyl hydroperoxide-induced hepatotoxicity through Nrf2-mediated antioxidant enzymes.

    PubMed

    Li, Bin; Lee, Dong-Sung; Kang, Yue; Yao, Nai-Qi; An, Ren-Bo; Kim, Youn-Chul

    2013-03-01

    Ganodermanondiol, a biologically active compound, was isolated from the Lingzhi mushroom (Ganoderma lucidum). The present study examined the protective effects of ganodermanondiol against tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity. Ganodermanondiol protected human liver-derived HepG2 cells through nuclear factor-E2-related factor 2 (Nrf2) pathway-dependent heme oxygenase-1 expressions. Moreover, ganodermanondiol increased cellular glutathione levels and the expression of the glutamine-cysteine ligase gene in a dose-dependent manner. Furthermore, ganodermanondiol exposure enhanced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its upstream kinase activators, LKB1 and Ca(2+)/calmodulin-dependent protein kinase-II (CaMKII). This study indicates that ganodermanondiol exhibits potent cytoprotective effects on t-BHP-induced hepatotoxicity in human liver-derived HepG2 cells, presumably through Nrf2-mediated antioxidant enzymes and AMPK. PMID:23266269

  17. Growth and characterization of 2,6-Di-tert-butyl-4-(dimethylaminomethyl)phenol single crystal by the vertical Bridgman method

    NASA Astrophysics Data System (ADS)

    Siva Bala Solanki, S.; Perumal, Rajesh Narayana; Basheer Ahamed, M.

    2015-02-01

    Single crystal of 2,6-Di-tert-butyl-4-(dimethylaminomethyl)phenol has been grown by the modified vertical Bridgman method. Single crystal X-ray diffraction studies of the crystal confirm that the material belongs to the monoclinic system and space group C2. Fourier Transform Infrared Spectroscopy (FTIR) analysis ascertains the functional group of grown crystal. Thermogravimetric and differential scanning calorimetric analyses are used to assess the thermal characteristics. The surface laser damage value was determined using Q-switched Nd:YAG laser at a wavelength of 1064 nm, which is a positive property for nonlinear optical applications. Vickers's indentation test is performed to analyze the mechanical behavior of the materials. An optical transmission study is used to compute optical band gap and cutoff wavelength. Fluorescence studies were performed to the grown crystal. The Kurtz and Perry powder technique is used to determine the second harmonic conversion efficiency of the sample.

  18. Stopped-flow study of the kinetics of the reaction of Rh (PPh/sub 3/) /sub 2/COC1 with cumyl and tert-butyl hydroperoxides

    SciTech Connect

    Tyutchenkova, L.D.; Malievskii, A.D.; Vinogradova, V.G.

    1986-11-01

    A spectroscopic study showed the formation of complexes of bis (triphenylphosphine) carbonylrhodium chloride with cumyl hydroperoxide (CHP) and tert-butyl hydroperoxide (TBHP) in toluene solution at 20/sup 0/C. The equilibrium constants were found for the formation of these complexes (57.5 and 160 liters/mole, respectively) at different CHP and TBHP concentrations relative to the change in intensity of the absorption bands. The stopped-flow method was used to determine the rate constants for the formation (k/sub 1/) and decomposition (k/sub 2/) of these complexes: k/sub 1/, CHP = 2.0, k/sub 1/, TBHP = 0.55 liters/mole.sec and k/sub 2/CHP = 0.035, k/sub 2/, tbhp = 0.003 sec /sup -//sub 1/. It was proposed that ternary complexes are formed upon the addition of an olefin (cyclohexane) to the bis(triphenylphosphine) carbonylrhodium chloride-CHP system.

  19. Treatment of Methyl tert-Butyl Ether Vapors in Biotrickling Filters. 1.

    E-print Network

    S * Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521 odor threshold is 45 to 95 ppb and taste threshold is about 135 ppb) target levels as low as 5 or 14 solutionstopreventcontaminationofdrinkingwatersupplies with the oxygenate while mitigating existing contaminations from leaking underground storage tanks

  20. Treatment of Methyl tert-Butyl Ether Vapors in Biotrickling Filters. 2.

    E-print Network

    . This is an important procedure which has often been overlooked. This is unfortunate since a clear under- standing beds was 0.5 m, and the bed volume was 9 L. Reactor 1 was filled with 8.81 kg of wet lava rock (1-3 cm

  1. IRIS TOXICOLOGICAL REVIEW AND SUMMARY DOCUMENTS FOR METHYL TERT-BUTYL ETHER (MTBE)

    EPA Science Inventory

    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. Effect of p-tert-butyl group substitution on the quantum tunneling rate in quadruple proton rearrangement of calix[4]arene.

    PubMed

    Ueda, Kouhei; Oguni, Masaharu

    2013-11-14

    Glass-transition behaviors concerning the quadruple proton/deuteron rearrangements in the crystalline p-tert-butylcalix[4]arene-toluene (BC4A·T) host-guest compound were studied by adiabatic calorimetry. The glass-transition temperatures (Tg's) of the hydrated BC4A·T-h and deuterated BC4A·T-d were found to be around 90 and 181 K, respectively. The difference of 90 K is too big to be recognized as the ordinary isotope effect, which is about 5 K in classical thermal activation processes. The temperature interval over which the enthalpy relaxation effect was observed was beyond 50 K, being too wide, in BC4A·T-h, while it was 20-30 K in BC4A·T-d; the latter is the one ordinarily observed in the classical processes. The associated equilibration rate in BC4A·T-h was evaluated from the enthalpy relaxation curve observed at 62 K to evidence the non-Arrhenius nature of the temperature dependence. The relaxation effect was detected even at 20 K. These are quite the same behaviors as observed in calix[4]arene, and the quantum tunneling rate in the quadruple proton rearrangement was concluded to be only a little affected by the substitution of the tert-butyl group at the para-position of each phenol moiety. PMID:24144320

  3. Ethyl tert-butyl ether (ETBE) biodegradation by a syntrophic association of Rhodococcus sp. IFP 2042 and Bradyrhizobium sp. IFP 2049 isolated from a polluted aquifer.

    PubMed

    Le Digabel, Yoann; Demanèche, Sandrine; Benoit, Yves; Vogel, Timothy M; Fayolle-Guichard, Françoise

    2013-12-01

    Ethyl tert-butyl ether (ETBE) enrichment was obtained by adding contaminated groundwater to a mineral medium containing ETBE as the sole carbon and energy source. ETBE was completely degraded to biomass and CO2 with a transient production of tert-butanol (TBA) and a final biomass yield of 0.37 ± 0.08 mg biomass (dry weight).mg(-1) ETBE. Two bacterial strains, IFP 2042 and IFP 2049, were isolated from the enrichment, and their 16S rRNA genes (rrs) were similar to Rhodococcus sp. (99 % similarity to Rhodococcus erythropolis) and Bradyrhizobium sp. (99 % similarity to Bradyrhizobium japonicum), respectively. Rhodococcus sp. IFP 2042 degraded ETBE to TBA, and Bradyrhizobium sp. IFP 2049 degraded TBA to biomass and CO2. A mixed culture of IFP 2042 and IFP 2049 degraded ETBE to CO2 with a biomass yield similar to the original ETBE enrichment (0.31 ± 0.02 mg biomass.mg(-1) ETBE). Among the genes previously described to be involved in ETBE, MTBE, and TBA degradation, only alkB was detected in Rhodococcus sp. IFP 2042 by PCR, and none were detected in Bradyrhizobium sp. IFP 2049. PMID:23474617

  4. Participation of covalent modification of Keap1 in the activation of Nrf2 by tert-butylbenzoquinone, an electrophilic metabolite of butylated hydroxyanisole

    SciTech Connect

    Abiko, Yumi; Miura, Takashi [Doctoral Programs in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Phuc, Bui Hoang [Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Shinkai, Yasuhiro [Doctoral Programs in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Kumagai, Yoshito, E-mail: yk-em-tu@md.tsukuba.ac.jp [Doctoral Programs in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan); Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 (Japan)

    2011-08-15

    Butylated hydroxyanisole (BHA) is an antioxidant and class-2B carcinogen. It is biotransformed to tert-butylhydroquinone (TBHQ), which readily auto-oxidizes to the electrophilic metabolite tert-butylbenzoquinone (TBQ). BHA and TBHQ activate Nrf2, a transcription factor that is negatively regulated by Keap1 and plays a role in the initial response to chemicals causing oxidative or electrophilic stress, although, the exact mechanism of Nrf2 activation remains unclear. Here, we examined the role of TBQ in Nrf2 activation. Exposure of RAW264.7 cells to TBQ activated Nrf2 and up-regulated its downstream proteins; under these conditions, TBQ produced cellular reactive oxygen species (ROS). However, while pretreatment with catalase conjugated with polyethylene glycol (PEG-CAT) did not affect the TBQ-induced activation of Nrf2, the ROS generation caused by TBQ was entirely abolished by PEG-CAT, suggesting that ROS is not the dominant factor for TBQ-dependent Nrf2 activation. A click chemistry technique indicated that TBQ chemically modifies Keap1. Furthermore, ultrahigh performance liquid chromatography-tandem mass spectrometry analysis with purified Keap1 revealed that TBQ covalently binds to Keap1 through Cys23, Cys151, Cys226, and Cys368. These results suggest that TBQ derived from BHA activates Nrf2 through electrophilic modification of Keap1 rather than ROS formation. - Research Highlights: > tert-Butylbenzoquinone (TBQ) activates Nrf2 in RAW264.7 cells. > ROS is not essential factor for Nrf2 activation caused by TBQ. > TBQ covalently binds to Keap1 through reactive thiols, resulting in Nrf2 activation.

  5. Interaction of Keap1 modified by 2-tert-butyl-1,4-benzoquinone with GSH: evidence for S-transarylation.

    PubMed

    Abiko, Yumi; Kumagai, Yoshito

    2013-07-15

    2-tert-Butyl-1,4-benzoquinone (TBQ), an electrophilic metabolite of butylated hydroxyanisole (BHA), causes activation of Nrf2 together with S-arylation of its negative regulator Keap1 in RAW264.7 cells. In a previous study, we found that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) covalently modified with 1,2-naphthoquinone (1,2-NQ) undergoes S-transarylation by GSH, resulting in a decline of the GAPDH-1,2-NQ adduct and formation of a 1,2-NQ-SG adduct ( Miura , T. et al. ( 2011 ) Chem. Res. Toxicol. 24 , 1836 -1844 ). In the present study, we explored the possibility of GSH-dependent S-transarylation of the Keap1-TBQ adduct. Pretreatment with l-buthionine-(S,R)-sulfoximine and N-acetylcysteine prior to TBQ exposure of HepG2 cells suggested that the Keap1-TBQ adduct appears to undergo GSH-mediated S-transarylation because the resulting alterations in the intracellular GSH concentration affected Nrf2 activation caused by TBQ. In support of this hypothesis, a cell-free study demonstrated that incubation of the Keap1-TBQ adduct with GSH results in the removal of TBQ from Keap1 with the production of mono- and di-GSH adducts of TB(H)Q. These results suggest that GSH plays a role in reversible covalent modification of TBQ derived from BHA to Keap1 through the formation of a C-S bond. PMID:23718696

  6. A Field Application of Hydrogen-Releasing Compound (HRC) for the Enhanced Bioremediation of Methyl Tertiary Butyl Ether (MTBE)

    Microsoft Academic Search

    Joseph E. Haas; Donald A. Trego

    2001-01-01

    Due to a greater understanding of the behavior of the fuel oxygenate Methyl Tertiary Butyl Ether (MTBE) in groundwater, the United States Environmental Protection Agency (EPA) and the American Petroleum Institute (API) recently have acknowledged the need for the development and application of additional remedial strategies to address the more extensive, longer lived, and faster moving dissolved MTBE plumes often

  7. Treatment of methyl t-butyl ether contaminated water using a dense medium plasma reactor, a mechanistic and kinetic investigation

    E-print Network

    Dandy, David

    1 Treatment of methyl t-butyl ether contaminated water using a dense medium plasma reactor-7369 Email: david.dandy@colostate.edu Abstract Plasma treatment of contaminated water appears reactor configurations and two pin array spin rates. The oxidation products from the treatment of MTBE

  8. Assessment of Occupational Methyl Tertiary Butyl Ether Vapor Exposures to Petroleum Refinery and Transport Loading Rack Facility Employees

    Microsoft Academic Search

    Dean R. Lillquist; Kevin L. Zeigle

    1998-01-01

    The use of oxygenated gasoline is required for metropolitan areas which exceed the carbon monoxide nonattainment standard as specified by the Clean Air Act Amendments of 1990. Many petroleum refineries blend methyl tertiary butyl ether (MTBE) with gasoline to make oxygenated fuel, which burns cleaner and reduces carbon monoxide emissions from motor vehicle exhaust. MTBE has a low acute toxicity

  9. DEVELOPMENT OF PHYSIOLOGICAL-BASED PHARMACOKINETIC MODEL FOR DERMAL ABSORPTION NAD PENETRATION OF METHYL TERTIARY BUTYL ETHER IN HUMANS

    EPA Science Inventory

    Background: Methyl tertiary butyl ether (MTBE) is a volatile organic chemical that is added to gasoline as an octane booster and to reduce vehicular emissions of carbon monoxide. MTBE is introduced into the environment through fuel spills, leakage of storage tanks, and evaporat...

  10. Overview of Methyl Tertiary Butyl Ether (MTBE) Detections in Public Drinking Water Supplies in the United States

    Microsoft Academic Search

    Pamela R. D. Williams; Jennifer S. Pierce

    2009-01-01

    We provide a review and summary of methyl tertiary butyl ether (MTBE) water monitoring data that have been collected as part of national, multi-state, and state-wide assessments in the United States. Specifically, we summarize the key attributes of 24 publicly available studies or data sets and characterize the detection frequency and detected concentrations of MTBE for different water types based

  11. Refined PBPK model of aggregate exposure to methyl tertiary-butyl ether.

    PubMed

    Kim, David; Andersen, Melvin E; Pleil, Joachim D; Nylander-French, Leena A; Prah, James D

    2007-03-30

    Aggregate (multiple pathway) exposures to methyl tertiary-butyl ether (MTBE) in air and water occur via dermal, inhalation, and oral routes. Previously, physiologically based pharmacokinetic (PBPK) models have been used to quantify the kinetic behavior of MTBE and its primary metabolite, tertiary-butyl alcohol (TBA), from inhalation exposures. However, the contribution of dermal and oral exposures to the internal dose of MTBE and TBA were not characterized well. The objective of this study was to develop a multi-route PBPK model of MTBE and TBA in humans. The model was based entirely on blood MTBE and TBA measurements from controlled human exposures. The PBPK model consists of nine primary compartments representing the lungs, skin, fat, kidney, stomach, intestine, liver, rapidly perfused tissue, and slowly perfused tissue. The MTBE and TBA models are linked by a single metabolic pathway. Although the general structure of the model is similar to previously published models of volatile organic compounds, we have now developed a detailed mathematical description of the lung, skin, and gastrointestinal tract. This PBPK model represents the most comprehensive and accurate description of MTBE and TBA pharmacokinetics in humans to date. The aggregate exposure model application for MTBE can be generalized to other environmental chemicals under this framework given appropriate empirical measurement data. PMID:17336003

  12. Progressive Effect of ?-Phenyl-N- TertButyl Nitrone (PBN) on Rat Embryo Development in Vitro

    Microsoft Academic Search

    Tadashi Yamashita; Hidetoshi Yamazaki; Yasuhiro Kon; Tomomasa Watanabe; Jiro Arikawa; Ichiro Miyoshi; Noriyuki Kasai; Mikinori Kuwabara

    1997-01-01

    In the present study we demonstrated the effects of the spin-trapping agent ?-phenyl-N-tert-butylnitrone (PBN) on the in vitro development of rat embryos at the early stage. In rat embryos, PBN increased the speed of the first cleavage and had no toxicity during pregnancy after embryo culture. These results showed that reactive oxygen species (ROIs) that were formed by activating molecular

  13. hTERT Is Expressed in Cancer Cell Lines Despite Promoter DNA Methylation by Preservation of Unmethylated DNA and Active Chromatin around the Transcription Start Site

    Microsoft Academic Search

    Rebekah L. Zinn; Kevin Pruitt; Sayaka Eguchi; Stephen B. Baylin

    hTERT, which encodes the catalytic subunit of telomerase and is expressed in most immortalized and cancer cells, has been reported to have increased DNA methylation in its promoter region in many cancers. This pattern is inconsis- tent with observations that DNA methylation of promoter CpG islands is typically associated with gene silencing. Here, we provide a comprehensive analysis of promoter

  14. Vapour pressure and enthalpy of vaporization of di-iso-propyl and di-tert-butyl esters of dicarboxylic acids

    Microsoft Academic Search

    Svetlana V. Portnova; Eugen L. Krasnykh; Sergey P. Verevkin

    2011-01-01

    Molar enthalpies of vaporization of the branched aliphatic alkyl esters of dicarboxylic acids R-CO2-(CH2)n-CO2-R with n=(0–4) with R=iso-C3H7, tert-C4H9 were obtained from the temperature dependence of the vapour pressure measured by the transpiration method. These experimental results were checked for internal consistency and compared with the data available from the literature. A linear correlation of enthalpies of vaporization ?lgHm (298.15K)

  15. Dermal, oral, and inhalation pharmacokinetics of methyl tertiary butyl ether (MTBE) in human volunteers.

    PubMed

    Prah, James; Ashley, David; Blount, Benjamin; Case, Martin; Leavens, Teresa; Pleil, Joachim; Cardinali, Frederick

    2004-02-01

    Methyl tertiary butyl ether (MTBE), a gasoline additive used to increase octane and reduce carbon monoxide emissions and ozone precursors, has contaminated drinking water and can lead to exposure by oral, inhalation, and dermal routes. To determine its dermal, oral, and inhalation kinetics, 14 volunteers were exposed to 51.3 microg/ml MTBE dermally in tap water for 1 h, drank 2.8 mg MTBE in 250 ml Gatorade(R), and inhaled 3.1 ppm. MTBE for 1 h. Blood and exhaled breath samples were then obtained. Blood MTBE peaked between 15 and 30 min following oral exposure, at the end of inhalation exposure, and ~5 min after dermal exposure. Elimination by each route was described well by a three-compartment model (Rsq >0.9). The Akaike Information Criterion for the three-compartment model was smaller than the two-compartment model, supporting it over the two-compartment model. One metabolite, tertiary butyl alcohol (TBA), measured in blood slowly increased and plateaued, but it did not return to the pre-exposure baseline at the 24-h follow-up. TBA is very water-soluble and has a blood:air partition ratio of 462, reducing elimination by exhalation. Oral exposure resulted in a significantly greater MTBE metabolism into TBA than by other routes based on a greater blood TBA:MTBE AUC ratio, implying significant first-pass metabolism. The slower TBA elimination may make it a better biomarker of MTBE exposure, though one must consider the exposure route when estimating MTBE exposure from TBA because of first-pass metabolism. Most subjects had a baseline blood TBA of 1-3 ppb. Because TBA is found in consumer products and can be used as a fuel additive, it is not a definitive marker of MTBE exposure. These data provide the risk assessment process of pharmacokinetic information relevant to the media through which most exposures occur-air and drinking water. PMID:14600279

  16. The Cytoprotective Effect of Sulfuretin against tert-Butyl Hydroperoxide-Induced Hepatotoxicity through Nrf2/ARE and JNK/ERK MAPK-Mediated Heme Oxygenase-1 Expression

    PubMed Central

    Lee, Dong-Sung; Kim, Kyoung-Su; Ko, Wonmin; Li, Bin; Jeong, Gil-Saeng; Jang, Jun-Hyeog; Oh, Hyuncheol; Kim, Youn-Chul

    2014-01-01

    Sulfuretin is one of the major flavonoid components in Rhus verniciflua Stokes (Anacardiaceae) isolates. In this study, we investigated the protective effects of sulfuretin against tert-butyl hydroperoxide (t-BHP)-induced oxidative injury. The results indicated that the addition of sulfuretin before t-BHP treatment significantly inhibited cytotoxicity and reactive oxygen species (ROS) production in human liver-derived HepG2 cells. Sulfuretin up-regulated the activity of the antioxidant enzyme heme oxygenase (HO)-1 via nuclear factor E2-related factor 2 (Nrf2) translocation into the nucleus and increased the promoter activity of the antioxidant response element (ARE). Moreover, sulfuretin exposure enhanced the phosphorylation of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase 1/2 (ERK1/2), which are members of the mitogen-activated protein kinase (MAPK) family. Furthermore, cell treatment with a JNK inhibitor (SP600125) and ERK inhibitor (PD98059) reduced sulfuretin-induced HO-1 expression and decreased its protective effects. Taken together, these results suggest that the protective effect of sulfuretin against t-BHP-induced oxidative damage in human liver-derived HepG2 cells is attributable to its ability to scavenge ROS and up-regulate the activity of HO-1 through the Nrf2/ARE and JNK/ERK signaling pathways. Therefore, sulfuretin could be advantageous as a bioactive source for the prevention of oxidative injury. PMID:24857917

  17. Non-specific inhibition of ischemia- and acidosis-induced intracellular calcium elevations and membrane currents by ?-phenyl-N-tert-butylnitrone, butylated hydroxytoluene and trolox.

    PubMed

    Katnik, Christopher; Cuevas, Javier

    2014-01-01

    Ischemia, and subsequent acidosis, induces neuronal death following brain injury. Oxidative stress is believed to be a key component of this neuronal degeneration. Acute chemical ischemia (azide in the absence of external glucose) and acidosis (external media buffered to pH 6.0) produce increases in intracellular calcium concentration ([Ca2+]i) and inward membrane currents in cultured rat cortical neurons. Two ?-tocopherol analogues, trolox and butylated hydroxytoluene (BHT), and the spin trapping molecule ?-Phenyl-N-tert-butylnitrone (PBN) were used to determine the role of free radicals in these responses. PBN and BHT inhibited the initial transient increases in [Ca2+]i, produced by ischemia, acidosis and acidic ischemia and increased steady state levels in response to acidosis and the acidic ischemia. BHT and PBN also potentiated the rate at which [Ca2+]i increased after the initial transients during acidic ischemia. Trolox inhibited peak and sustained increases in [Ca2+]i during ischemia. BHT inhibited ischemia induced initial inward currents and trolox inhibited initial inward currents activated by acidosis and acidic ischemia. Given the inconsistent results obtained using these antioxidants, it is unlikely their effects were due to elimination of free radicals. Instead, it appears these compounds have non-specific effects on the ion channels and exchangers responsible for these responses. PMID:24583849

  18. The synergistic effects of heat shock protein 70 and ginsenoside Rg1 against tert-butyl hydroperoxide damage model in vitro.

    PubMed

    Lu, Dan; Xu, Anding; Mai, Hongcheng; Zhao, Jiayi; Zhang, Chanjuan; Qi, Renbin; Wang, Huadong; Lu, Daxiang; Zhu, Lihong

    2015-01-01

    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. PMID:25685255

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

    PubMed Central

    Canda, B. D.; Oguntibeju, O. O.; Marnewick, J. L.

    2014-01-01

    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. PMID:24738022

  20. Protective Effects of Black Rice Extracts on Oxidative Stress Induced by tert-Butyl Hydroperoxide in HepG2 Cells

    PubMed Central

    Lee, Seon-Mi; Choi, Youngmin; Sung, Jeehye; Kim, Younghwa; Jeong, Heon-Sang; Lee, Junsoo

    2014-01-01

    Black rice contains many biologically active compounds. The aim of this study was to investigate the protective effects of black rice extracts (whole grain extract, WGE and rice bran extract, RBE) on tert-butyl hydroperoxide (TBHP)-induced oxidative injury in HepG2 cells. Cellular reactive oxygen species (ROS), antioxidant enzyme activities, malondialdehyde (MDA) and glutathione (GSH) concentrations were evaluated as biomarkers of cellular oxidative status. Cells pretreated with 50 and 100 ?g/mL of WGE or RBE were more resistant to oxidative stress in a dose-dependent manner. The highest WGE and BRE concentrations enhanced GSH concentrations and modulated antioxidant enzyme activities (glutathione reductase, glutathione-S-transferase, catalase, and superoxide dismutase) compared to TBHP-treated cells. Cells treated with RBE showed higher protective effect compared to cells treated with WGE against oxidative insult. Black rice extracts attenuated oxidative insult by inhibiting cellular ROS and MDA increase and by modulating antioxidant enzyme activities in HepG2 cells. PMID:25580401

  1. Stability of fluctuating and transient aggregates of amphiphilic solutes in aqueous binary mixtures: Studies of dimethylsulfoxide, ethanol, and tert-butyl alcohol

    NASA Astrophysics Data System (ADS)

    Banerjee, Saikat; Bagchi, Biman

    2013-10-01

    In aqueous binary mixtures, amphiphilic solutes such as dimethylsulfoxide (DMSO), ethanol, tert-butyl alcohol (TBA), etc., are known to form aggregates (or large clusters) at small to intermediate solute concentrations. These aggregates are transient in nature. Although the system remains homogeneous on macroscopic length and time scales, the microheterogeneous aggregation may profoundly affect the properties of the mixture in several distinct ways, particularly if the survival times of the aggregates are longer than density relaxation times of the binary liquid. Here we propose a theoretical scheme to quantify the lifetime and thus the stability of these microheterogeneous clusters, and apply the scheme to calculate the same for water-ethanol, water-DMSO, and water-TBA mixtures. We show that the lifetime of these clusters can range from less than a picosecond (ps) for ethanol clusters to few tens of ps for DMSO and TBA clusters. This helps explaining the absence of a strong composition dependent anomaly in water-ethanol mixtures but the presence of the same in water-DMSO and water-TBA mixtures.

  2. Conformational stability, molecular orbital studies (chemical hardness and potential), vibrational investigation and theoretical NBO analysis of 4-tert-butyl-3-methoxy-2,6-dinitrotoluene.

    PubMed

    Saravanan, S; Balachandran, V; Vishwanathan, K

    2014-04-24

    The FT-IR and FT-Raman spectra of 4-tert-butyl-3-methoxy-2,6-dinitrotoluene (musk ambrette) have been recorded in the regions 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The total energy calculations of musk ambrette were tried for the possible conformers. The molecular structure, geometry optimization, vibrational frequencies were obtained by the density functional theory (DFT) using B3LYP and LSDA method with 6-311G(d,p) basis set for the most stable conformer "C1". The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated and the scaled values were compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The stability of the molecule arising from hyper conjugate interactions and the charge delocalization has been analyzed using bond orbital (NBO) analysis. The HOMO and LUMO energy gap reveals that the energy gap reflects the chemical activity of the molecule. The dipole moment (?), polarizability (?), anisotropy polarizability (??) and first hyperpolarizability (?tot) of the molecule have been reported. The thermodynamic functions (heat capacity, entropy and enthalpy) were obtained for the range of temperature 100-1000 K. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP). PMID:24508884

  3. Oxidative transformation of 2-acetylaminofluorene by a chemical model for cytochrome P450: A water-insoluble porphyrin and tert-butyl hydroperoxide.

    PubMed

    Inami, Keiko; Mochizuki, Masataka

    2008-07-15

    Oxidation of 2-acetylaminofluorene (AAF), a carcinogen, by a chemical model for cytochrome P450 was investigated to identify an active mutagen and elucidate the oxidation pathway. The oxidation system consisted of a water-insoluble tetrakis(pentafluorophenyl)porphyrinatoiron(III) chloride and tert-butyl hydroperoxide. The mutagen derived from AAF by the chemical model was 2-nitro-9-fluorenone (NO(2)=FO), which was mutagenic in Salmonella typhimurium TA1538. AAF was oxidized initially at position 9 of the fluorene carbon by the chemical model forming 2-acetylamino-9-fluorenol (AAF-OH), and then oxidized further to 2-acetylamino-9-fluorenone (AAF=O) as a major product. Initial oxidation of the nitrogen formed 2-nitrofluorene (NO(2)F), and further oxidation yielded 2-nitro-9-fluorenol (NO(2)F-OH) as a minor product. These products, AAF-OH, AAF=O, NO(2)F, and NO(2)F-OH, and their presumable common intermediate, N-hydroxy-2-acetylaminofluorene, were oxidized by the chemical model, and the formation of NO(2)F=O was determined. These results showed that NO(2)F=O was the mutagen derived from AAF in the presence of the chemical model and was formed via oxidation of N-OH-AAF, NO(2)F, and NO(2)F-OH. These results may lead to a new metabolic pathway of AAF. PMID:18586499

  4. Environmentally responsive self-assembly of mixed poly(tert-butyl acrylate)-polystyrene brush-grafted silica nanoparticles in selective polymer matrices.

    PubMed

    Tang, Saide; Fox, Tara L; Lo, Ting-Ya; Horton, Jonathan M; Ho, Rong-Ming; Zhao, Bin; Stewart, Phoebe L; Zhu, Lei

    2015-07-01

    Environmentally responsive self-assembly of nearly symmetric mixed poly(tert-butyl acrylate) (PtBA, 22.2 kDa)/polystyrene (PS, 23.4 kDa) brushes grafted onto 67 nm silica nanoparticles in selective homopolymer matrices [PtBA for the grafted PtBA chains and poly(cyclohexyl methacrylate) (PCHMA) for the grafted PS chains] was investigated using both conventional transmission electron microscopy (TEM) and electron tomography (i.e., 3D TEM). A variety of self-assembled phase morphologies were observed for the mixed brushes in selective polymer matrices with different molecular weights, and these can be explained by entropy-driven wet- and dry-brush theories. In a low molecular weight selective matrix, the wet-brush regime was formed with the miscible chains stretching out and the immiscible chains collapsing into isolated domains. In contrast, when the molecular weight of the selective matrix was higher than that of the compatible grafted polymer chains, the dry-brush regime was formed with the mixed brushes exhibiting the unperturbed morphology. In addition to the molecular weight, the size of nanoparticles (or the substrate curvature) was also observed to play an important role. For small particles (core size less than 50 nm), the wet brush-like morphology with a surface-tethered micellar structure was observed. Finally, the wet- and dry-brush regimes also significantly affected the dispersion of mixed brush particles in selective polymer matrices. PMID:26061172

  5. Induction of Methyl Tertiary Butyl Ether (MTBE)Oxidizing Activity in Mycobacterium vaccae JOB5 by MTBE

    Microsoft Academic Search

    Erika L. Johnson; Christy A. Smith; Kirk T. O'Reilly; Michael R. Hyman

    2004-01-01

    Alkane-grown cells of Mycobacterium vaccae JOB5 cometabolically degrade the gasoline oxygenate methyl tertiary butyl ether (MTBE) through the activities of an alkane-inducible monooxygenase and other enzymes in the alkane oxidation pathway. In this study we examined the effects of MTBE on the MTBE-oxidizing activity of M. vaccae JOB5 grown on diverse nonalkane substrates. Carbon-limited cultures were grown on glycerol, lactate,

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

    Microsoft Academic Search

    CATHERINE Y. LIU; GERALD E. SPEITEL; G. Georgiou

    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 mg\\/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

  7. Disposition, metabolism, and toxicity of methyl tertiary butyl ether, an oxygenate for reformulated gasoline

    SciTech Connect

    Hutcheon, D.E.; Hove, W. ten; Boyle, J. III [UMDNJ, New Jersey Medical Schook, Newark, NJ (United States)] [UMDNJ, New Jersey Medical Schook, Newark, NJ (United States); Arnold, J.D. [Arnold & Arnold, Inc., Kansas City, MO (United States)] [Arnold & Arnold, Inc., Kansas City, MO (United States)

    1996-04-05

    Studies of the toxicology of methyl tertiary butyl ether (MTBE) were reviewed as a possible information base for evaluating the health effects of evaporative emissions from reformulated gasoline (RFG). Perirenal fat/blood MTBE concentration ratios ranged from 9.7 to 11.6 after 15 wk of intermittent exposure. During an oxyfuels program in Fairbanks, AK, blood levels of occupationally exposed workers were 0.2-31.5 {mu}g/L MTBE and 1.6 to 72.2 {mu}g/L TBA with a mean TBA:MTBE blood concentration ratio of 4.2. In patients who received MTBE by percutaneous, transhepatic puncture for the dissolution of cholesterol gallstones, concentrations of MTBE in fat tissue reached 60 and 300 {mu}g/g at a treatment time when mean blood MTBE was less than 20 {mu}g/ml. The results of laboratory and clinical studies indicate that metabolites of MTBE may contribute to the nephropathy, neoplasms, and other pathological changes associated with repeated exposure to MTBE in experimental animals. It is concluded that such studies can provide a well-defined database for quantitatitive safety comparisons and health risk-benefit analyses of MTBE and other oxygenates in RFG. 39 refs., 1 tab.

  8. Observation on the biodegradation and bioremediation potential of methyl t-butyl ether

    SciTech Connect

    Salanitro, J.; Wisniewski, H.; McAllister, P. [Shell Development Co., Houston, TX (United States)

    1995-12-31

    There have been few reports documenting evidence for the biodegradation of the fuel oxygenate alkyl ether, methyl t-butyl ether (MTBE) in groundwater, soils, and biosludges. Partial (or complete) microbial breakdown of MTBE has been observed in an anaerobic subsoil, a river sediment under methanogenic conditions, a cyclohexane-degrading bacterial consortium and a pure culture of the methylotroph, Methylisnus trichosporium OB3b. An aerobic bacterial enrichment (BC-1) isolated from an industrial transient (non-accumulating) metabolic intermediate. The studies suggest that MTBE is cleaved by BC-1 to TBA which is then metabolized via isopropanol and acetone. There is little information on the occurrence of indigenous MTBE-degraders in groundwater, soils and activated sludges. Preliminary evidence has been obtained, however, from a marketing terminal groundwater site that naturally-occurring MTBE-degraders are present in some monitoring wells. Microcosm experiments with groundwater from this aquifer show that MTBE is aerobically degraded (no TBA formed) with a first-order decay rate (0.31/day) similar to BTEX. Also, MTBE did not inhibit the intrinsic biodegradation potential of BTEX in groundwater microcosms. In summary, the data presented indicate that MTBE biodegradation has been observed in some environmental media. Further work is needed to assess the feasibility of using indigenous or derived aerobic and anaerobic MTBE-degrading cultures for treating fuel ethers in groundwaters or wastewater with in-situ or ex-situ bioremediation technologies.

  9. Biochemical effects of methyl tertiary-butyl ether in extended vapour exposure of rats.

    PubMed

    Savolainen, H; Pfäffli, P; Elovaara, E

    1985-09-01

    Male Wistar rats exposed to 50, 100 or 300 ppm methyl tertiary-butyl ether vapour for 2-15 weeks, 6 h daily, 5 days a week, showed a dose-dependent blood ether concentration after 2 weeks' exposure. Blood concentrations of tertiary-butanol, were also dose dependent indicating metabolic breakdown of the ether in vivo. The blood ether concentrations decreased after 6 weeks of exposure at the 50 ppm dose level and remained unaffected at higher doses while tertiary-butanol concentrations increased after 6 weeks with all doses, and began to decrease thereafter. Exposure caused a transient increase in UDP-glucuronosyltransferase activities in liver and kidney microsomes, almost no effects on hepatic cytochrome P-450 concentrations and a minor induction of kidney microsomal cytochrome P-450 content. Exposure produced almost no effect on brain succinate dehydrogenase, creatine kinase or acetylcholinesterase activities, while early inhibition of muscle creatine kinase activity was noted, accompanied by increased activity at the end of exposure. PMID:4091653

  10. Disposition, metabolism, and toxicity of methyl tertiary butyl ether, an oxygenate for reformulated gasoline.

    PubMed

    Hutcheon, D E; Arnold, J D; ten Hove, W; Boyle, J

    1996-04-01

    Studies of the toxicology of methyl tertiary butyl ether (MTBE) were reviewed as a possible information base for evaluating the health effects of evaporative emissions from reformulated gasoline (RFG). The major metabolites of the oxidative demethylation of MTBE in vivo were methanol and tertiary butyl alcohol (TBA), whereas formaldehyde and TBA were the principal products of hepatic microsomal oxidation by cytochrome P-450. Pharmacokinetic studies in rats treated with intragastric MTBE in corn oil gave an initial disposition T1/2 for MTBE of 0.32 h. The decline in the serum drug versus time curve for MTBE in rats was accompanied by a progressive increase in serum methanol concentrations to levels more than 50-200 times those of the parent compound. Repeated exposure of MTBE vapor by inhalation in rats resulted in dose-dependent increases in MTBE in the blood, brain, and adipose tissue compartments. Blood concentrations of TBA were also dose dependent and provided an estimate of the total amount of MTBE distributed to peripheral drug metabolizing compartments. Perirenal fat/blood MTBE concentration ratios ranged from 9.7 to 11.6 after 15 wk of intermittent exposure. During an oxyfuels program in Fairbanks, AK, blood levels of occupationally exposed workers were 0.2-31.5 microgram/L MTBE and 1.6 to 72.2 microgram/L TBA with a mean TBA:MTBE blood concentration ratio of 4.2. In patients who received MTBE by percutaneous, transhepatic puncture for the dissolution of cholesterol gallstones, concentrations of MTBE in fat tissue reached 60 and 300 microgram/g at a treatment time when mean blood MTBE was less than 20 microgram/ml. The results of laboratory and clinical studies indicate that metabolites of MTBE may contribute to the nephropathy, neoplasms, and other pathological changes associated with repeated exposure to MTBE in experimental animals. It is concluded that such studies can provide a well-defined database for quantitative safety comparisons and health risk-benefit analyses of MTBE and other oxygenates in RFG. PMID:8614015

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

    PubMed Central

    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: ethyl 4-(3, 5-di-ter-butyl-2-hydroxybenzylamino) benzoate; toxicity; antioxidant; gastric-ulcer; anti-ulcer; histology; immunohistochemistry. PMID:24800807

  12. Protection against oxidative damage to CNS by alpha-phenyl-tert-butyl nitrone (PBN) and other spin-trapping agents: A novel series of nonlipid free radical scavengers

    SciTech Connect

    Carney, J.M.; Floyd, R.A. (Department of Pharmacology, Chandler Medical Center, University of Kentucky, Lexington (United States))

    1991-01-01

    Brain is extremely susceptible to oxidative damage. Utilizing a series of novel approaches, the authors have demonstrated that oxidative damage occurs during an ischemia/reperfusion insult (IRI) to brain. Thus, they have demonstrated that an IRI to Mongolian gerbil brain results in: (1) an enhanced rate of salicylate hydroxylation, implicating an increased flux of hydroxyl free radicals; (2) an enhanced flux of free radicals as determined by spin-trapping; (3) an enhanced level of endogenous protein oxidation; (4) a decrease in glutamine synthetase (GS) activity, an enzyme very sensitive to oxidative damage; and (5) demonstration of protection from an IRI by administering the spin-trapping agent alpha-phenyl-tert-butyl nitrone (PBN). The novel observation that PBN offers protection from the lethality brought on by a brain IRI appears to be clearly linked to the ability of the administered spin-trap to inhibit oxidative damage as evidenced by the decreased amount of brain protein oxidation and the prevention of an IRI-mediated loss of GS activity in treated animals. Aged gerbils are more sensitive to the lethal action of a brain IRI than younger animals, but they are protected by PBN administration as are the younger animals. Older gerbils have a significantly higher level of oxidized protein in the brain. Older gerbils have decreased activities of GS and neutral protease, the enzyme that removes oxidized protein, than younger animals. Chronic twice daily administration of PBN (32 mg/kg) for 14 days to older animals significantly lowered brain oxidized protein levels and raised GS and neutral protease activity to those observed in younger animals. Cessation of PBN administration resulted in a time-dependent restoration of protein oxidation levels and enzyme activities back to those observed prior to spin-trap administration.

  13. Demonstration of free radical generation in stunned myocardium of intact dogs with the use of the spin trap alpha-phenyl N-tert-butyl nitrone

    SciTech Connect

    Bolli, R.; Patel, B.S.; Jeroudi, M.O.; Lai, E.K.; McCay, P.B.

    1988-08-01

    Recent studies suggest that oxygen free radicals may mediate postischemic myocardial dysfunction (stunning), but all the evidence for this hypothesis is indirect. Thus, we used electron paramagnetic resonance (EPR) spectroscopy and the spin trap, alpha-phenyl N-tert-butyl nitrone (PBN), to directly investigate whether free radicals are produced after a 15-min coronary artery occlusion and subsequent reperfusion in 30 open-chest dogs. After intracoronary infusion of PBN, EPR signals characteristic of oxygen- and carbon-centered radical adducts were detected in the venous blood draining from the ischemic/reperfused vascular bed. The myocardial release of PBN adducts began during coronary occlusion but increased dramatically in the first few minutes after reperfusion. After this initial burst, the production of radicals abated but did not cease, persisting up to 3 h after reflow. The EPR spectra were consistent with the trapping by PBN of secondary oxygen- and carbon-centered radicals, such as alkoxy and alkyl radicals, which could be formed by reactions of primary oxygen radicals with membrane lipids. There was a linear, direct relationship between the magnitude of PBN adduct production and the degree of ischemic flow reduction. Recovery of contractile function after reperfusion was greater (P less than 0.05) in dogs given PBN than in controls. This study demonstrates that reversible regional myocardial ischemia in the intact animal is associated with prolonged free radical generation, and that the intensity of such generation is related to the severity of ischemia. The results provide direct evidence to support the hypothesis that reactive oxygen metabolites contribute to the persistent contractile dysfunction observed after brief ischemia in vivo.

  14. Study on the chromatographic behavior of water-soluble vitamins on p-tert-butyl-calix[8]arene-bonded silica gel stationary phase by HPLC.

    PubMed

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

    2004-10-01

    In this paper, the chromatographic behavior of some water-soluble vitamins was studied on a new p-tert-butyl-calix[8]arene-bonded silica gel stationary phase (CABS, 5mum particle size, the bonded amount 0.071mmolg(-1)) by using vitamin standards as probes for HPLC. The comparative study of the separation of these compounds was done by using CABS and ODS as stationary phases under the same chromatographic conditions. The better separation of six vitamins including: B(1), B(2), B(6), B(12), C, and nicotinic acid (B(5)), on CABS can be achieved by using isocratic mode with methanol-phosphate buffer (25:75, (v/v)) as mobile phase within 20min. The results show that the calix[8]arene-bonded phase exhibits high selectivity for water-soluble vitamins. We found that the elution order of B(2) (12.08min) and B(12) (16.42min) on CABS was very different from that of B(12) (7.76min) and B(2) (18.47min) on ODS, which indicate that different retention mechanisms exist in the chromatographic processes of the two stationary phases. According to the chromatographic data, it can be concluded that various chromatographic retention mechanisms are responsible for the separation of above compounds on CABS, such as hydrophobic interaction, hydrogen bonding interaction, and pi-pi interaction. The new packing has two advantages over ODS. On one hand, the polar and ionized analytes, such as C and B(5), exhibited stronger affinities to CABS because of hydrogen bonding interaction. On the other hand, the retention of B(2) and B(12) became shorter on CABS with weaker hydrophobicity in comparison with ODS. The new material exhibits the promising application in the separation of water-soluble vitamins. PMID:18969614

  15. Dynamics of Back Electron Transfer in Dye-Sensitized Solar Cells Featuring 4-tert-Butyl-Pyridine and Atomic-Layer-Deposited Alumina as Surface Modifiers.

    PubMed

    Katz, Michael J; DeVries Vermeer, Michael J; Farha, Omar K; Pellin, Michael J; Hupp, Joseph T

    2015-06-18

    A series of dye-sensitized solar cells (DSCs) was constructed with TiO2 nanoparticles and N719 dye. The standard I3(-)/I(-) redox shuttle and the Co(1,10-phenanthroline)3(3+/2+) shuttle were employed. DSCs were modified with atomic-layered-deposited (ALD) coatings of Al2O3 and/or with the surface-adsorbing additive 4-tert-butyl-pyridine. Current-voltage data were collected to ascertain the influence of each modification upon the back electron transfer (ET) dynamics of the DSCs. The primary effect of the additives alone or in tandem is to increase the open-circuit voltage. A second is to alter the short-circuit current density, JSC. With dependence on the specifics of the system examined, any of a myriad of dynamics-related effects were observed to come into play, in both favorable (efficiency boosting) and unfavorable (efficiency damaging) ways. These effects include modulation of (a) charge-injection yields, (b) rates of interception of injected electrons by redox shuttles, and (c) rates of recombination of injected electrons with holes on surface-bound dyes. In turn, these influence charge-collection lengths, charge-collection yields, and onset potentials for undesired dark current. The microscopic origins of the effects appear to be related mainly to changes in driving force and/or electronic coupling for underlying component redox reactions. Perhaps surprisingly, only a minor role for modifier-induced shifts in conduction-band-edge energy was found. The combination of DSC-efficiency-relevant effects engendered by the modifiers was found to vary substantially as a function of the chemical identity of the redox shuttle employed. While types of modifiers are effective, a challenge going forward will be to construct systems in ways in which the benefits of organic and inorganic modifiers can be exploited in fully additive, or even synergistic, fashion. PMID:25127076

  16. The effect of an N-substituent on the recyclization of (2-aminoaryl)bis(5- tert-butyl-2-furyl)methanes: synthesis of 3-furylindoles and triketoindoles

    Microsoft Academic Search

    Alexander V. Butin; Sergey K. Smirnov; Igor V. Trushkov

    2008-01-01

    The recyclization of (2-aminophenyl)bis(5-tert-butyl-2-furyl)methane derivatives has been studied. It was shown that the acid-catalyzed recyclization of N-tosylamides leads to the formation of 2-(3-oxoalkyl)-3-(2-furyl)indoles. In contrast, under the same reaction conditions, acetamides are transformed into indoles containing three keto groups. The acid-catalyzed removal of the acetyl group from these substrates facilitated protolytic furan ring opening. The same triketones can be directly

  17. An octanuclear molybdenum(VI) complex containing coordinatively bound 4,4'-di-tert-butyl-2,2'-bipyridine, [Mo8O22(OH)4(di-tBu-bipy)4]: synthesis, structure, and catalytic epoxidation of bio-derived olefins.

    PubMed

    Amarante, Tatiana R; Neves, Patrícia; Tomé, Cátia; Abrantes, Marta; Valente, Anabela A; Paz, Filipe A Almeida; Pillinger, Martyn; Gonçalves, Isabel S

    2012-03-19

    The reaction of [MoO(2)Cl(2)(di-tBu-bipy)] (1) (di-tBu-bipy = 4,4'-di-tert-butyl-2,2'-bipyridine) with water at 100-120 °C in a Teflon-lined stainless steel autoclave, in an open reflux system, or in a microwave synthesis system gave the octanuclear complex [Mo(8)O(22)(OH)(4)(di-tBu-bipy)(4)] (2) as a microcrystalline powder in good yields. Single crystals of 2 suitable for X-ray diffraction were obtained by the reaction of MoO(3) and di-tBu-bipy in water at 160 °C for 3 days. The molecular structure of 2 comprises a purely inorganic core, Mo(4)O(8)(?(3)-OH)(2)(?(2)-O)(2), attached to two peripheral oxo-bridged binuclear units, Mo(2)O(4)(?(2)-O)(2)(OH)(di-tBu-bipy)(2). The inorganic core is composed of a unique assembly of four {MoO(5)} distorted square pyramids connected to each other via edge-sharing. Overall, the octanuclear complex adopts a highly distorted form strongly resembling an "S"-shaped molecular unit. Complex 2 was applied in the catalytic epoxidation of the biorenewable olefins DL-limonene (Lim) and methyl oleate (Ole), using tert-butylhydroperoxide (TBHP) as an oxygen donor, under mild reaction conditions (55 °C, air). The reactions of Lim and Ole gave the respective epoxide monomers in fairly high selectivities at high conversions (89% 1,2-epoxy-p-menth-8-ene selectivity at 96% Lim conversion; 99% methyl 9,10-epoxystearate selectivity at 94% Ole conversion, reached within 24 h reaction). Iodometric titrations revealed no measurable "non-productive" decomposition of TBHP. PMID:22372402

  18. Synthesis of 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic Acid and (E)-3-(1-Methyl-1H-imidazol-2-ylthio)acrylic Acid.

    PubMed

    Hattan, Christopher M; Shojaie, Jalil; Lau, Serrine S; Anders, M W

    2013-01-01

    The syntheses of 3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid and 3-(1-methyl-1H-imidazol-2-ylthio)propanoic acid, mitochondria-targeted prodrugs of the antioxidant methimazole, are described. The method of Fan et al. (Fan et al., Synthesis 2006, 2286) for the reaction of phenols with propiolic acid and propiolate esters was modified to synthesize (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid. The intermediate tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate was prepared by the reaction of tert-butyl propiolate with methimazole; the use of tert-butyl propiolate rather than methyl propiolate gave tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate as the predominant isomer. Acid hydrolysis of the intermediate ester afforded the target compound. 3-(1-Methyl-1H-imidazol-2-ylthio)propanoic acid was synthesized from 3-bromopropanoic acid and methimazole under conditions that gave preferential substitution on sulfur and minimized substitution on nitrogen. PMID:24882887

  19. Coordination effects on electron distributions for rhodium complexes of the redox-active bis(3,5-di-tert-butyl-2-phenolate)amide ligand.

    PubMed

    Szigethy, Géza; Shaffer, David W; Heyduk, Alan F

    2012-12-01

    New rhodium complexes of bis(3,5-di-tert-butyl-2-phenol)amine ([ONO(cat)]H(3)) were synthesized, and their electronic properties were investigated. These compounds were prepared by combining [ONO(q)]K and [(cod)Rh(?-Cl)](2) in the presence of an auxiliary donor ligand to yield complexes of the type [ONO]RhL(n) (n = 3, L = py (1); n = 2, L = PMe(3) (2a), L = PMe(2)Ph (2b), PMePh(2) (2c), PPh(3) (2d)). Single-crystal X-ray diffraction studies on [ONO]Rh(py)(3) (1) revealed a six-coordinate, octahedral rhodium complex. In the case of [ONO]Rh(PMe(3))(2) (2a), X-ray diffraction showed a five-coordinate, distorted square-pyramidal coordination environment around the rhodium center. While 1 is static on the NMR time scale, complexes 2a-d are fluxional, displaying both rapid isomerization of the square-pyramidal structure and exchange of coordinated and free phosphine ligands. UV-vis spectroscopy shows stark electronic differences between 1 and 2a-d. Whereas 1 displays a strong absorbance at 380 nm with a much weaker band at 585 nm in the absorption spectrum, complexes 2a-d display an intense (? > 10(4) M(-1) cm(-1)), low-energy absorption band in the region 580-640 nm; however, in the cases of 2a and 2b, the addition of excess phosphine resulted in changes to the UV-vis spectrum indicating the formation of six-coordinate adducts [ONO]Rh(PMe(3))(3) (3a) and [ONO]Rh(PMe(2)Ph)(3) (3b), respectively. The experimental and DFT computational data for the six-coordinate complexes 1, 3a, and 3b are consistent with their formulation as classical, d(6), pseudo-octahedral, coordination complexes. In the five-coordinate complexes 2a-2d, ?-bonding between the rhodium center and the [ONO] ligand leads to a high degree of covalency and metal-ligand electron distributions that are not accurately described by formal oxidation state assignments. PMID:22482509

  20. Conformational preferences of sterically congested 2-imidazolidinone using X-ray analysis and computational studies. Part 1: Trans-1-acetyl-4,5-di- tert-butyl-2-imidazolidinone

    NASA Astrophysics Data System (ADS)

    Abdel-Aziz, Alaa A.-M.; Al-Omar, Mohamed A.; El-Azab, Adel S.; Kunieda, Takehisa

    2010-04-01

    The X-ray crystal structure of trans-1-acetyl-4,5-di- tert-butyl-2-imidazolidinone 2 [C 13H 24N 2O 2: MF = 240.34, monoclinic, P2 1/c (#14) , a = 12.313(4) Å ,b = 15.090(2) Å, c = 16.246(2) Å, ? = 98.33(1)°, V = 2986.8(9) Å 3, Z = 8, Dcalc = 1.069 g/cm 3, ?(Cu-K?) = 5.74 cm -1, F000 = 1056.00, T = 25.0 °C, R = 0.040] was determined, and confirmed the occurrence of two molecules of the s- transoid2a and 2b which are connected together by two hydrogen bonds. The crystal cohesion is ensured by a network of intermolecular hydrogen bonding. The conformational analysis of the s- transoid2a and 2b was performed by molecular mechanic, and showed the occurrence of one minimum for each molecule. Moreover RM1 semi-empirical and DFT/B3LYP calculations were applied to investigate the conformational preferences of the trans-1-acetyl-4,5-di- tert-butyl-2-imidazolidinone 2 and to correlate between calculated conformations and the structure in solid state. It has been found that the lowest energetic conformer computed gives the greatest correspondence with experimental solid state data.

  1. Isolation and characterization of 4-tert-butylphenol-utilizing Sphingobium fuliginis strains from Phragmites australis rhizosphere sediment.

    PubMed

    Toyama, Tadashi; Momotani, Naonori; Ogata, Yuka; Miyamori, Yuji; Inoue, Daisuke; Sei, Kazunari; Mori, Kazuhiro; Kikuchi, Shintaro; Ike, Michihiko

    2010-10-01

    We isolated three Sphingobium fuliginis strains from Phragmites australis rhizosphere sediment that were capable of utilizing 4-tert-butylphenol as a sole carbon and energy source. These strains are the first 4-tert-butylphenol-utilizing bacteria. The strain designated TIK-1 completely degraded 1.0 mM 4-tert-butylphenol in basal salts medium within 12 h, with concomitant cell growth. We identified 4-tert-butylcatechol and 3,3-dimethyl-2-butanone as internal metabolites by gas chromatography-mass spectrometry. When 3-fluorocatechol was used as an inactivator of meta-cleavage enzymes, strain TIK-1 could not degrade 4-tert-butylcatechol and 3,3-dimethyl-2-butanone was not detected. We concluded that metabolism of 4-tert-butylphenol by strain TIK-1 is initiated by hydroxylation to 4-tert-butylcatechol, followed by a meta-cleavage pathway. Growth experiments with 20 other alkylphenols showed that 4-isopropylphenol, 4-sec-butylphenol, and 4-tert-pentylphenol, which have alkyl side chains of three to five carbon atoms with ?-quaternary or ?-tertiary carbons, supported cell growth but that 4-n-alkylphenols, 4-tert-octylphenol, technical nonylphenol, 2-alkylphenols, and 3-alkylphenols did not. The rate of growth on 4-tert-butylphenol was much higher than that of growth on the other alkylphenols. Degradation experiments with various alkylphenols showed that strain TIK-1 cells grown on 4-tert-butylphenol could degrade 4-alkylphenols with variously sized and branched side chains (ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-heptyl, n-octyl, tert-octyl, n-nonyl, and branched nonyl) via a meta-cleavage pathway but not 2- or 3-alkylphenols. Along with the degradation of these alkylphenols, we detected methyl alkyl ketones that retained the structure of the original alkyl side chains. Strain TIK-1 may be useful in the bioremediation of environments polluted by 4-tert-butylphenol and various other 4-alkylphenols. PMID:20802076

  2. Isolation and Characterization of 4-tert-Butylphenol-Utilizing Sphingobium fuliginis Strains from Phragmites australis Rhizosphere Sediment? †

    PubMed Central

    Toyama, Tadashi; Momotani, Naonori; Ogata, Yuka; Miyamori, Yuji; Inoue, Daisuke; Sei, Kazunari; Mori, Kazuhiro; Kikuchi, Shintaro; Ike, Michihiko

    2010-01-01

    We isolated three Sphingobium fuliginis strains from Phragmites australis rhizosphere sediment that were capable of utilizing 4-tert-butylphenol as a sole carbon and energy source. These strains are the first 4-tert-butylphenol-utilizing bacteria. The strain designated TIK-1 completely degraded 1.0 mM 4-tert-butylphenol in basal salts medium within 12 h, with concomitant cell growth. We identified 4-tert-butylcatechol and 3,3-dimethyl-2-butanone as internal metabolites by gas chromatography-mass spectrometry. When 3-fluorocatechol was used as an inactivator of meta-cleavage enzymes, strain TIK-1 could not degrade 4-tert-butylcatechol and 3,3-dimethyl-2-butanone was not detected. We concluded that metabolism of 4-tert-butylphenol by strain TIK-1 is initiated by hydroxylation to 4-tert-butylcatechol, followed by a meta-cleavage pathway. Growth experiments with 20 other alkylphenols showed that 4-isopropylphenol, 4-sec-butylphenol, and 4-tert-pentylphenol, which have alkyl side chains of three to five carbon atoms with ?-quaternary or ?-tertiary carbons, supported cell growth but that 4-n-alkylphenols, 4-tert-octylphenol, technical nonylphenol, 2-alkylphenols, and 3-alkylphenols did not. The rate of growth on 4-tert-butylphenol was much higher than that of growth on the other alkylphenols. Degradation experiments with various alkylphenols showed that strain TIK-1 cells grown on 4-tert-butylphenol could degrade 4-alkylphenols with variously sized and branched side chains (ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-heptyl, n-octyl, tert-octyl, n-nonyl, and branched nonyl) via a meta-cleavage pathway but not 2- or 3-alkylphenols. Along with the degradation of these alkylphenols, we detected methyl alkyl ketones that retained the structure of the original alkyl side chains. Strain TIK-1 may be useful in the bioremediation of environments polluted by 4-tert-butylphenol and various other 4-alkylphenols. PMID:20802076

  3. Synthesis of hybrid TiO 2 nanoparticles with well-defined poly(methyl methacrylate) and poly(tert-butyldimethylsilyl methacrylate) via the RAFT process

    Microsoft Academic Search

    Van Giang Ngo; Christine Bressy; Christine Leroux; André Margaillan

    2009-01-01

    Surface of titania nanoparticles (TiO2) was modified by a coupling agent as 3-(trimethoxysilyl)propyl methacrylate (MPS) to form TiO2-MPS polymerizable particles. Methyl methacrylate (MMA) and tert-butyldimethylsilyl methacrylate (MASi) were radically polymerized through the immobilized vinyl bond on the surface in the presence of the reversible addition-fragmentation chain transfer (RAFT) agent 2-cyanoprop-2-yl dithiobenzoate using 2,2?-azobisisobutylnitrile (AIBN) as an initiator. FTIR spectroscopy confirmed

  4. SENSORY, SYMPTOMATIC, INFLAMMATORY, AND OCULAR RESPONSES TO AND THE METABOLISM OF METHYL TERTIARY BUTYL ETHER IN A CONTROLLED HUMAN EXPOSURE EXPERIMENT

    EPA Science Inventory

    In response to elevated ambient carbon monoxide (CO) due to incomplete combustion of automotive fuels, the Clear Air Act mandates that CO reduction be obtained by adding oxygenates to the fuel (oxyfuel) in areas of non-attainment. In 1992 the addition of methyl tertiary butyl eth...

  5. Tetra­butyl­ammonium tris­(methyl­sulfanylmeth­yl)phenyl­borate

    PubMed Central

    Tillmann, Jan; Lerner, Hans-Wolfram; Bolte, Michael

    2010-01-01

    In the title molecular salt, C16H36N+·C12H20BS3 ?, three of the four n-butyl chains show a trans conformation, whereas the fourth has the C—C—C—C torsion angle in a gauche conformation [?77.8?(5)°]. In the crystal, mol­ecules are packed in layers parallel to the (101) plane. PMID:21580088

  6. Microcosm and Column Studies on the Biodegradation of Methyl TertButyl Ether (MTBE) in Soil-Water Systems

    Microsoft Academic Search

    Marcia Morales; Marc A. Deshusses; Sergio Revah

    Microcosms and column experiments were carried out using soil and groundwater from a MTBE contaminated site or using distilled water amended with mineral salts. The biodegradation of MTBE was tested under aerobic and anaerobic conditions with an initial MTBE concentration of 25 mg\\/L. The water to soil ratio in the microcosm experiments was 1:2 by mass and the inoculum size

  7. tert-Butyl 4-(4-chloro­anilino)-6-methyl-2-oxocyclo­hex-3-ene­carboxyl­ate

    PubMed Central

    Alexander, Mariano S.; North, Henry; Scott, Kenneth R.; Butcher, Ray J.

    2011-01-01

    In the title compound, C18H22ClNO3, the dihedral angle between the benzene ring and the conjugated part of the enaminone ring is 55.19?(9)°. The ester substituent makes a dihedral angle of 81.0?(2)° with this latter moiety. The crystal structure features N—H?O and weak C—H?O inter­molecular inter­actions. PMID:21522723

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

    PubMed

    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. PMID:24275473

  9. AN EXPERIMENTAL STUDY OF PHYTOREMEDIATION OF METHYL-TERT-BUTYL-ETHER (MTBE) IN GROUNDWATER. (R825549C062)

    EPA Science Inventory

    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...

  10. Synthesis, characterization, antifungal and anti-HIV activities of metal(II) complexes of 4,6-di-tert-butyl-3-[(2-hydroxyethyl)thio]benzene-1,2-diol.

    PubMed

    Loginova, Natalia V; Koval'chuk, Tat'yana V; Polozov, Genrikh I; Osipovich, Nikolai P; Rytik, Pyotr G; Kucherov, Igor I; Chernyavskaya, Anna A; Sorokin, Victor L; Shadyro, Oleg I

    2008-07-01

    Co(II) and Ni(II) complexes with 4,6-di-tert-butyl-3-[(2-hydroxyethyl)thio]benzene-1,2-diol (L) have been synthesized and characterized by means of elemental analysis, TG/DTA, FT-IR, ESR, UV-vis, XRD, magnetic susceptibility, cyclic voltammetry and conductance measurements. According to the data obtained the organic compound acts as a bidentate O,S-coordinated ligand and yields Co(II) and Ni(II) complexes of the stoichiometry ML(2) which is characterized by square planar geometry. Antifungal and anti-HIV activities of the ligand and its metal(II) complexes were found to decrease in the sequence CuL(2)>CoL(2) ~ NiL(2)>HL, along with their reducing ability (determined electrochemically). PMID:17996335

  11. Solution and solid-state study of the structure of azo-coupling products from isomeric enaminones possessing tert-butyl group: An unprecedented observation of pure hydrazo form in azo coupled N-alkyl ?-enaminones

    NASA Astrophysics Data System (ADS)

    Šim?nek, Petr; Pad?lková, Zde?ka; Machá?ek, Vladimír

    2014-10-01

    The structure of the azo-coupling products from enaminones derived from 4,4-dimethyl-1-phenylpentane-1,3-dione has been studied by means of solution-state 1H, 13C and 15N NMR spectroscopy and X-ray diffractometry. The presence of bulky tert-butyl group hinders or even prevents from the formation of planar conjugated heterodiene system Hsbnd Nsbnd Cdbnd Csbnd Ndbnd N with an intramolecular hydrogen bond Nsbnd H⋯Ndbnd which is the prerequisite for fast tautomeric exchange imino-hydrazo - enamino-azo. The minor amount of azo compounds is formed by a proton exchange through a hydrogen bond Nsbnd H⋯N, which is either intramolecular (in solution) or intermolecular (solid state). The intermolecular exchange proceeds via the dimers of the azo coupling products. This is unprecedented result among the similar molecules hitherto studied.

  12. A general one-pot synthesis for elusive 2-substituted indenes: does bis[2-(tert-butyl)indenyl]zirconium(IV) dichloride/MAO polymerise ethene?

    PubMed

    Möller, Andreas C; Blom, Richard; Heyn, Richard H; Swang, Ole; Kopf, Jürgen; Seraidaris, Tanja

    2006-05-01

    Among the 2-substituted indenes, 2-trifluoroindene and 2-tert-butylindene are poorly or incompletely described in the open literature. We herein describe an efficient one-pot synthesis of these compounds as a variation of the Perkin reaction which allows us to refute an earlier claim that bis(2-tert-butylindenyl)zirconium(IV) dichloride (2a) will not polymerise ethene. In fact, 2a/MAO polymerises ethene to extremely high molecular weights. Extensive DFT calculations on the polymerisation mechanism revealed an unprecedented suppression of the otherwise predominant chain termination by beta-hydride transfer due to steric congestion of the active site. PMID:16625254

  13. Metal-Free Preparation of Cycloalkyl Aryl Sulfides via Di-tert-butyl Peroxide-Promoted Oxidative C(sp3)[BOND]H Bond Thiolation of Cycloalkanes

    PubMed Central

    Zhao, Jincan; Fang, Hong; Han, Jianlin; Pan, Yi; Li, Guigen

    2014-01-01

    A concise thiolation of C(sp3)–H bond of cycloalkanes with diaryl disulfides in the presence of oxidant of di-tert-butylperoxide (DTBP) has been developed. This reaction without using any of metal catalyst, tolerates varieties of disulfides and cycloalkanes substrates, giving good to excellent chemical yields, which provides a useful approach to cycloalkyl aryl sulfides from unactivated cycloalkanes. PMID:25505857

  14. ELECTROCHEMICAL BEHAVIOR OF METHYL TERTBUTYL ETHER (MTBE) OXIDATION ON AN IRIDIUM DIOXIDE (IrO2) COATED ELECTRODE

    Microsoft Academic Search

    Ting-Nien Wu; Zong-Chih Lin

    Methyl tert-butyl ether (MTBE), the most widely used unleaded gasoline additive, has higher water solubility, lower air-water partition, lower organic carbon sorption, and less biodegradability than other gasoline constituents, such as benzene, toluene, ethylbenzene, and xylene. According to its chemical characteristics, MTBE is always the most likely found compound at the front of a gasoline plume. The presence of MTBE

  15. Enantioseparation of the compounds of technical toxaphene (CTTs) on 35% heptakis (6- O-tert -butyldimethylsilyl-2,3-di- O Methyl)-?-cyclodextrin in OV1701

    Microsoft Academic Search

    U. Klobes; W. Vetter; B. Luckas; G. Hottinger

    1998-01-01

    Summary  The separation of the enantiomers of the compounds of technical toxaphene (CTTs) on heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-?-cyclodextrin (?-TBDM) has been studied by gas chromatography with electron-capture detection (GC-ECD). Enantiomers\\u000a of eight of the nine CTTs under investigation were separated on this chiral stationary phase. Separations of the enantioners\\u000a of CTTs have hitherto been achieved ontert-butyldimethylsilylated ?-cyclodextrin (?-BSCD). The chiral resolution values and separation

  16. Extraction of RadioStrontium from Nitric Acid Medium Using Di-tert-Butyl Cyclohexano18Crown6 (DTBCH18C6) in Toluene–1Octanol Diluent Mixture

    Microsoft Academic Search

    D. R. Raut; P. K. Mohapatra; V. K. Manchanda

    2010-01-01

    An alternative extraction system to the SREX solvent using a diluent mixture comprising 4,4?(5?)di-tert-butylcyclohexano-18-crown-6 (DTBCH18C6) in 80% toluene–20% 1-octanol was developed and evaluated for Sr(II) extraction from pressurized heavy water reactor simulated high level waste (PHWR-SHLW). The acid uptake (5.7%) by the present solvent was significantly lower as compared to that by the SREX solvent (21%) which used 100% 1-octanol

  17. The uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether inhaled alone and in combination with gasoline vapor.

    PubMed

    Benson, Janet M; Tibbetts, Brad M; Barr, Edward B

    2003-06-13

    The purpose of these studies was to evaluate the tissue uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether (MTBE) in rats and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on these parameters. Male F344 rats were exposed nose-only once for 4 h to 4, 40, or 400 ppm 14C-MTBE and to 20 and 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 and 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on the fate of inhaled MTBE, rats were exposed for 7 consecutive days to 20 and 200 ppm LFG followed on d 8 by exposure to LFG containing 14C-MTBE. Three subgroups of rats were included for evaluation of respiratory parameters, rates and routes of excretion, and tissue distribution and elimination. MTBE and its chief metabolite, tertiary-butyl alcohol, were quantitated in blood and kidney (immediately after exposure), and the major urinary metabolites, 2-hydroxyisobutyric acid and 2-methyl-1,2- propanediol, were identified and quantified in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens (IBBs) of MTBE equivalents achieved after 4 h of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. Between 40 and 400 ppm, there was a significant reduction in percentage of the IBB present in the major organs examined, both immediately and 72 h after exposure. At 400 ppm, the elimination rates of MTBE equivalents from tissues changed significantly. Furthermore, at 400 ppm there was a significant decrease in the elimination half-time of volatile organic compounds (VOCs) in breath and a significant increase in the percentage of the IBB of MTBE equivalents eliminated as VOCs in breath. LFG coexposure significantly decreased the percentage of the MTBE equivalent IBBs in tissues and increased rates of elimination of MTBE equivalents. The study results indicate that the uptake and fate of inhaled MTBE are altered upon increasing exposure levels from 4 to 400 ppm, suggesting that toxic effects observed previously upon repeated inhalation of concentrations of 400 ppm or greater may not necessarily be linearly extrapolated to effects that might occur at lower concentrations. Furthermore, coexposure to LFG, whether acute or repeated, decreases tissue burdens of MTBE equivalents and enhances the elimination rate of MTBE and its metabolites, thereby potentially reducing the toxic effects of the MTBE compared to when it is inhaled alone. PMID:12775515

  18. Preparation and Characterization of Styrene\\/Butyl Acrylate Emulsifier-Free Latex with 2-Acrylamido-2Methyl Propane Sulfonic Acid as a Reactive Emulsifier

    Microsoft Academic Search

    Wei Chang; Lijuan Liu; Jin Zhang; Qiwei Pan; Meishan Pei

    2009-01-01

    A kind of emulsifier-free latex (FL) was successfully synthesized from styrene (St) and butyl acrylate (BA) with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) as a reactive emulsifier. The particle size of latex particles, stability against electrolytes, minimum film forming temperature (MFT) and water contact angle (CA) were evaluated and compared with a conventional latex (CL). Test results show that FL has

  19. Crystal structure of 3-methyl-5-tri­methyl­silyl-1H-pyrazole

    PubMed Central

    Ferrence, Gregory M.; Kocher, Joshua L.

    2015-01-01

    The title compound, C7H14N2Si, crystallizes in a tetra­gonal space group and exists as an N—H?N hydrogen-bonded tetra­mer, formed around the crystallographic fourfold rotoinversion axis. The mol­ecular identity is clearly the 5-tri­methyl­silyl-3-methyl-1H-pyrazole tautomer and the structure is isomorphous with that of 5-tert-butyl-3-methyl-1H-pyrazole [Foces-Foces & Trofimenko (2001 ?). Acta Cryst. E57, o32–o34].

  20. Structural Characterization of Hydroxyl-Terminated Polybutadiene-Bound 2, 2-Thiobis(4-methyl-6-tert-butylphenol) and Its Thermo-Oxidative Aging Resistance for Natural Rubber Vulcanizates

    Microsoft Academic Search

    Yonghong Wang; Xingrong Zeng; Hongqiang Li; Jianhua Guo

    2012-01-01

    A novel polymeric antioxidant, hydroxyl-terminated polybutadiene-bound 2,2-thiobis(4-methyl-6-tert-butylphenol) (HTPB-IPDI-TPH), was prepared by binding 2, 2-thiobis(4-methyl-6-tert-butylphenol) (TPH) onto hydroxyl-terminated polybutadiene (HTPB) with isophorone diisocyanate (IPDI). Fourier-transform infrared spectroscopy (FTIR), C nuclear magnetic resonance spectroscopy (C NMR), and gel permeation chromatography (GPC) were used to characterize the structure of HTPB-IPDI-TPH. The thermal stability of HTPB-IPDI-TPH was studied by thermogravimetry analysis (TGA). The effect

  1. Distribution of organic solutes in biphasic 1-n-butyl-3-methylimidazolium methyl sulfate-supercritical CO(2) system.

    PubMed

    Planeta, Josef; Karásek, Pavel; Roth, Michal

    2009-07-16

    Interphase distribution of organic nonelectrolytes can be important in applications of biphasic solvent systems composed of a room-temperature ionic liquid and supercritical carbon dioxide (scCO(2)). Here, open tubular capillary-column supercritical fluid chromatography (SFC) with 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][MeSO(4)]) as the stationary liquid and scCO(2) as the carrier fluid was employed to measure retention factors of organic solutes within 313-353 K and 8.5-23.2 MPa. Solute selection included 18 compounds of diverse volatilities and chemical functionalities. The retention factors were converted to infinite-dilution solute partition coefficients in the biphasic [bmim][MeSO(4)]-scCO(2) system. At a constant temperature, an increase in scCO(2) density produced distinct shifts in relative retention (= separation factor), thus providing some pressure-tunable selectivity. At a particular temperature and density of CO(2), solute partition coefficients can be correlated in terms of linear solvation energy relationships. Analysis of the relative retention data by regular solution theory resulted in approximate values of the solubility parameter of CO(2)-expanded [bmim][MeSO(4)]. PMID:19537694

  2. Methyl ethyl ketone+water+secondary butyl alcohol: A potential system for the exploration of a quadruple critical point

    NASA Astrophysics Data System (ADS)

    Madhavan Unni, P. K.

    2006-03-01

    We report preliminary experiments on the ternary-liquid mixture, methyl ethyl ketone (MEK)+water(W)+secondary butyl alcohol (sBA)—a promising system for the realization of the quadruple critical point (QCP). The unusual tunnel-shaped phase diagram shown by this system is characterized and visualized by us in the form of a prismatic phase diagram. Light-scattering experiments reveal that (MEK+W+sBA) shows near three-dimensional-Ising type of critical behavior near the lower critical solution temperatures, with the susceptibility exponent (?) in the range of 1.217???1.246. The correlation length amplitudes (?o) and the critical exponent (?) of the correlation length (?) are in the ranges of 3.536??o?4.611Å and 0.619???0.633, respectively. An analysis in terms of the effective susceptibility exponent (?eff) shows that the critical behavior is of the Ising type for MEK concentrations in the ranges of 0.1000?X?0.1250 and X ?0.3000. But, for the intermediate range of 0.1750?X<0.3000, the system shows a tendency towards mean-field type of critical behavior. The advantages of the system (MEK+W+sBA) over the system (3-methylpyridine+water+heavywater+potassiumIodide) for the realization of a QCP are outlined.

  3. Seasonal and daily variations in concentrations of methyl-tertiary-butyl ether (MTBE) at Cranberry Lake, New Jersey

    USGS Publications Warehouse

    Toran, L.; Lipka, C.; Baehr, A.; Reilly, T.; Baker, R.

    2003-01-01

    Methyl-tertiary-butyl ether (MTBE), an additive used to oxygenate gasoline, has been detected in lakes in northwestern New Jersey. This occurrence has been attributed to the use of gasoline-powered watercraft. This paper documents and explains both seasonal and daily variations in MTBE concentrations at Cranberry Lake. During a recent boating season (late April to September 1999), concentrations of MTBE typically exceeded 20??g/L. MTBE concentrations varied daily from 12 to 24??g/L over a 2-week period that included the Labor Day holiday. Concentrations were highest on weekends when there is more boat traffic, which had an immediate effect on MTBE mass throughout the lake. MTBE concentrations decreased to about 2??g/L shortly after the end of the summer recreational season. The loss of MTBE can be accounted for by volatilization, with a half-life on the order of 10 days. The volatilization rate was modeled with the daily decrease in MTBE then the modeled rate was validated using the data from the seasonal decline. ?? 2003 Elsevier Science Ltd. All rights reserved.

  4. Formation of Alkenes via Degradation of tert-Alkyl Ethers and Alcohols by Aquincola tertiaricarbonis L108 and Methylibium spp. ?†

    PubMed Central

    Schäfer, Franziska; Muzica, Liudmila; Schuster, Judith; Treuter, Naemi; Rosell, Mònica; Harms, Hauke; Müller, Roland H.; Rohwerder, Thore

    2011-01-01

    Bacterial degradation pathways of fuel oxygenates such as methyl tert-butyl and tert-amyl methyl ether (MTBE and TAME, respectively) have already been studied in some detail. However, many of the involved enzymes are still unknown, and possible side reactions have not yet been considered. In Aquincola tertiaricarbonis L108, Methylibium petroleiphilum PM1, and Methylibium sp. strain R8, we have now detected volatile hydrocarbons as by-products of the degradation of the tert-alkyl ether metabolites tert-butyl and tert-amyl alcohol (TBA and TAA, respectively). The alkene isobutene was formed only during TBA catabolism, while the beta and gamma isomers of isoamylene were produced only during TAA conversion. Both tert-alkyl alcohol degradation and alkene production were strictly oxygen dependent. However, the relative contribution of the dehydration reaction to total alcohol conversion increased with decreasing oxygen concentrations. In resting-cell experiments where the headspace oxygen content was adjusted to less than 2%, more than 50% of the TAA was converted to isoamylene. Isobutene formation from TBA was about 20-fold lower, reaching up to 4% alcohol turnover at low oxygen concentrations. It is likely that the putative tert-alkyl alcohol monooxygenase MdpJ, belonging to the Rieske nonheme mononuclear iron enzymes and found in all three strains tested, or an associated enzymatic step catalyzed the unusual elimination reaction. This was also supported by the detection of mdpJK genes in MTBE-degrading and isobutene-emitting enrichment cultures obtained from two treatment ponds operating at Leuna, Germany. The possible use of alkene formation as an easy-to-measure indicator of aerobic fuel oxygenate biodegradation in contaminated aquifers is discussed. PMID:21742915

  5. Formation of alkenes via degradation of tert-alkyl ethers and alcohols by Aquincola tertiaricarbonis L108 and Methylibium spp.

    PubMed

    Schäfer, Franziska; Muzica, Liudmila; Schuster, Judith; Treuter, Naemi; Rosell, Mònica; Harms, Hauke; Müller, Roland H; Rohwerder, Thore

    2011-09-01

    Bacterial degradation pathways of fuel oxygenates such as methyl tert-butyl and tert-amyl methyl ether (MTBE and TAME, respectively) have already been studied in some detail. However, many of the involved enzymes are still unknown, and possible side reactions have not yet been considered. In Aquincola tertiaricarbonis L108, Methylibium petroleiphilum PM1, and Methylibium sp. strain R8, we have now detected volatile hydrocarbons as by-products of the degradation of the tert-alkyl ether metabolites tert-butyl and tert-amyl alcohol (TBA and TAA, respectively). The alkene isobutene was formed only during TBA catabolism, while the beta and gamma isomers of isoamylene were produced only during TAA conversion. Both tert-alkyl alcohol degradation and alkene production were strictly oxygen dependent. However, the relative contribution of the dehydration reaction to total alcohol conversion increased with decreasing oxygen concentrations. In resting-cell experiments where the headspace oxygen content was adjusted to less than 2%, more than 50% of the TAA was converted to isoamylene. Isobutene formation from TBA was about 20-fold lower, reaching up to 4% alcohol turnover at low oxygen concentrations. It is likely that the putative tert-alkyl alcohol monooxygenase MdpJ, belonging to the Rieske nonheme mononuclear iron enzymes and found in all three strains tested, or an associated enzymatic step catalyzed the unusual elimination reaction. This was also supported by the detection of mdpJK genes in MTBE-degrading and isobutene-emitting enrichment cultures obtained from two treatment ponds operating at Leuna, Germany. The possible use of alkene formation as an easy-to-measure indicator of aerobic fuel oxygenate biodegradation in contaminated aquifers is discussed. PMID:21742915

  6. Toxicokinetics of human exposure to methyl tertiary-butyl ether (MTBE) following short-term controlled exposures.

    PubMed

    Lee, C W; Mohr, S N; Weisel, C P

    2001-01-01

    Methyl tertiary-butyl ether (MTBE) is an oxygenated compound added to gasoline to improve air quality as part of the US Federal Clean Air Act. Due to the increasing and widespread use of MTBE and suspected health effects, a controlled, short-term MTBE inhalation exposure kinetics study was conducted using breath and blood analyses to evaluate the metabolic kinetics of MTBE and its metabolite, tertiary-butyl alcohol (TBA), in the human body. In order to simulate common exposure situations such as gasoline pumping, subjects were exposed to vapors from MTBE in gasoline rather than pure MTBE. Six subjects (three females, three males) were exposed to 1.7 ppm of MTBE generated by vaporizing 15 LV% MTBE gasoline mixture for 15 min. The mean percentage of MTBE absorbed was 65.8 +/- 5.6% following exposures to MTBE. The mean accumulated percentages expired through inhalation for 1 and 8 h after exposure for all subjects were 40.1% and 69.4%, respectively. The three elimination half-lives of the triphasic exponential breath decay curves for the first compartment was 1-4 min, for the second compartment 9-53 min, and for the third compartment 2-8 h. The half-lives data set for the breath second and blood first compartments suggested that the second breath compartment rather than the first breath compartment is associated with a blood compartment. Possible locations for the very short breath half-life observed are in the lungs or mucous membranes. The third compartment calculated for the blood data represent the vessel poor tissues or adipose tissues. A strong correlation between blood MTBE and breath MTBE was found with mean blood-to-breath ratio of 23.5. The peak blood TBA levels occurred after the MTBE peak concentration and reached the highest levels around 2-4 h after exposures. Following the exposures, immediate increases in MTBE urinary excretion rates were observed with lags in the TBA excretion rate. The TBA concentrations reached their highest levels around 6-8 h, and then gradually returned to background levels around 20 h after exposure. Approximately 0.7-1.5% of the inhaled MTBE dose was excreted as unchange urinary MTBE, and 1-3% was excreted as unconjugated urinary TBA within 24 h after exposure. PMID:11409007

  7. COMPLEXATION OF METAL IONS WITH 3,5-DI-TERT-BUTYL-1,2BENZOQUINONE1-MONOOXIME, ESR STUDIES OF RADICAL INTERMEDIATES

    Microsoft Academic Search

    Veli T. Kasumov; E?ref Ta?; Ibrahim Kartal; Fatih Ucun; Fevzi Köksal; Alaaddin Çukurovali

    2001-01-01

    The possibility of chelate formation of 3,5-di-terf-butyl-o-benzoquinone-1-monooxime with Cu(II), Co(II), Ni(II), Mn(II), Pd(II) metal ions under N2 and in air have been investigated. It was found that complexation of metals except Cu(II) and Mn(II) was accompanied by formation of various stable radical species under air. The complexation of Co(II) even under N2 unlike other metal ions, results in the formation

  8. Solid state ¹H spin-lattice relaxation and isolated-molecule and cluster electronic structure calculations in organic molecular solids: the relationship between structure and methyl group and t-butyl group rotation.

    PubMed

    Wang, Xianlong; Mallory, Frank B; Mallory, Clelia W; Odhner, Hosanna R; Beckmann, Peter A

    2014-05-21

    We report ab initio density functional theory electronic structure calculations of rotational barriers for t-butyl groups and their constituent methyl groups both in the isolated molecules and in central molecules in clusters built from the X-ray structure in four t-butyl aromatic compounds. The X-ray structures have been reported previously. We also report and interpret the temperature dependence of the solid state (1)H nuclear magnetic resonance spin-lattice relaxation rate at 8.50, 22.5, and 53.0 MHz in one of the four compounds. Such experiments for the other three have been reported previously. We compare the computed barriers for methyl group and t-butyl group rotation in a central target molecule in the cluster with the activation energies determined from fitting the (1)H NMR spin-lattice relaxation data. We formulate a dynamical model for the superposition of t-butyl group rotation and the rotation of the t-butyl group's constituent methyl groups. The four compounds are 2,7-di-t-butylpyrene, 1,4-di-t-butylbenzene, 2,6-di-t-butylnaphthalene, and 3-t-butylchrysene. We comment on the unusual ground state orientation of the t-butyl groups in the crystal of the pyrene and we comment on the unusually high rotational barrier of these t-butyl groups. PMID:24852535

  9. Solid state {sup 1}H spin-lattice relaxation and isolated-molecule and cluster electronic structure calculations in organic molecular solids: The relationship between structure and methyl group and t-butyl group rotation

    SciTech Connect

    Wang, Xianlong, E-mail: WangXianlong@uestc.edu.cn, E-mail: pbeckman@brynmawr.edu [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China)] [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China); Mallory, Frank B. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States)] [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Mallory, Clelia W. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States) [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Odhner, Hosanna R.; Beckmann, Peter A., E-mail: WangXianlong@uestc.edu.cn, E-mail: pbeckman@brynmawr.edu [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States)

    2014-05-21

    We report ab initio density functional theory electronic structure calculations of rotational barriers for t-butyl groups and their constituent methyl groups both in the isolated molecules and in central molecules in clusters built from the X-ray structure in four t-butyl aromatic compounds. The X-ray structures have been reported previously. We also report and interpret the temperature dependence of the solid state {sup 1}H nuclear magnetic resonance spin-lattice relaxation rate at 8.50, 22.5, and 53.0 MHz in one of the four compounds. Such experiments for the other three have been reported previously. We compare the computed barriers for methyl group and t-butyl group rotation in a central target molecule in the cluster with the activation energies determined from fitting the {sup 1}H NMR spin-lattice relaxation data. We formulate a dynamical model for the superposition of t-butyl group rotation and the rotation of the t-butyl group's constituent methyl groups. The four compounds are 2,7-di-t-butylpyrene, 1,4-di-t-butylbenzene, 2,6-di-t-butylnaphthalene, and 3-t-butylchrysene. We comment on the unusual ground state orientation of the t-butyl groups in the crystal of the pyrene and we comment on the unusually high rotational barrier of these t-butyl groups.

  10. Crystal structure of bis­(?5-cyclo­penta­dien­yl)(1,4-di-tert-butyl­buta-1-en-3-yn-1-yl)zirconium(IV) ?2-hydroxido-bis­[tris(penta­fluoro­phen­yl)borate

    PubMed Central

    Burlakov, Vladimir V.; Spannenberg, Anke; Arndt, Perdita; Rosenthal, Uwe

    2015-01-01

    Alkyl zirconocene cations have been of considerable inter­est as reactive species in many polymerization processes. In the crystal structure of the title compound, [Zr(C12H19)(C5H5)2](C36HB2F30O), the [Zr(C5H5)2((t-Bu)C=C(H)—C2(t-Bu))]+ cation displays a buta-1-en-3-yne ligand side-on coordinated to a typical bent zirconocene [centroid(cp)—Zr—centroid(cp) = 131.4?(3)°, Zr—C(buta-1-en-3-yne) = 2.255?(3), 2.597?(3) and 2.452?(2)?Å]. In the [HO(B(C6F5)3)2]? anion, intra­molecular O—H?F hydrogen bonds are observed. One tert-butyl group in the complex cation is disordered over two sets of sites with occupancies 0.701(4):0.299(4). PMID:25844214

  11. Relative potency of the atropine-like effects of a new parasympatholytic drug, scopolamine-N-(cyclopropyl methyl) bromide and those of hyoscine-N-butyl bromide.

    PubMed

    Litta-Modignani, R; Mazzolari, M; Barantani, E; Bertoli, D; Vibelli, C

    A double-blind crossover trial with a 4-point bioassay was carried out in 8 convalescent in-patients to study the relative potency of scopolamine-N-(cyclopropyl methyl) bromide (DA 3177), a new parasympatholytic drug, administered at doses of 2.5 mg and 5 mg i.v., and hyoscine-N-butyl bromide, administered at doses of 10 mg and 20 mg i.v., in producing atropine-like effects. The results showed that the effects on heart rate and near point of accommodation were slightly less with DA 3177, while its effects on salivary secretion were a little greater than those of hyoscine-N-butyl bromide. It is suggested that study of the pharmacodynamic effects of parasympatholytic drugs is a relatively simple way of predicting which doses should be effective spasmolytically. PMID:343994

  12. Henry’s law constants and infinite dilution activity coefficients of cis-2-butene, dimethylether, chloroethane, and 1,1-difluoroethane in methanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-methyl-2-butanol

    Microsoft Academic Search

    Yoshimori Miyano; Takahiro Kobashi; Hiroshi Shinjo; Shinya Kumada; Yusuke Watanabe; Wataru Niya; Yoko Tateishi

    2006-01-01

    Henry’s law constants and infinite dilution activity coefficients of cis-2-butene, dimethylether, chloroethane, and 1,1-difluoroethane in methanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, and 2-methyl-2-butanol in the temperature range of 250K to 330K were measured by a gas stripping method and partial molar excess enthalpies were calculated from the activity coefficients. A rigorous formula for evaluating

  13. Access to “Friedel-Crafts-restricted” tert-alkyl aromatics by activation/methylation of tertiary benzylic alcohols

    PubMed Central

    Hartsel, Joshua A.; Craft, Derek T.; Chen, Qiao-Hong; Ma, Ming

    2012-01-01

    Herein we describe a two-step protocol to prepare m-tert-alkylbenzenes. The appropriate 3° benzylic alcohols are activated with SOCl2 or concentrated HCl, and then treated with trimethylaluminum, affording the desired products in 68–97% yields (22 examples). This reaction sequence is successful in the presence of a variety of functional groups, including acid-sensitive and Lewis-basic groups. In addition to t-Bu groups, 1,1-dimethylpropyl and 1-ethyl-1-methylpropyl groups can also be installed using this method. PMID:22394317

  14. 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

    SciTech Connect

    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.

  15. 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.

    PubMed

    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. PMID:25958557

  16. Octacoordinated Dioxo-Molybdenum Complex via Formal Oxidative Addition of Molecular Oxygen. Studies of Chemical Reactions Between M(CO)6 (M = Cr, Mo) and 2,4-Di-tert-butyl-6-(pyridin-2-ylazo)-phenol.

    PubMed

    Chatterjee, Ipsita; Saha Chowdhury, Nabanita; Ghosh, Pradip; Goswami, Sreebrata

    2015-06-01

    Reactions of M(CO)6 (M = Mo, Cr) and 2 mol of 2,4-di-tert-butyl-6-(pyridin-2-ylazo)-phenol ligand (HL) in air yielded [Mo(VI)O2(L(1)¯)2], 1, and [Cr(III)(L(1)¯)(L(•2)¯)], 2, respectively, in high yields. Formation of the Cr-complex is a substitution reaction, which is associated with electron transfer, while that of Mo is an example of molecular oxygen activation. Isolated monoradical chromium complex 2 is susceptible to oxidation. Accordingly the reaction of 2 with the oxidant, I2 produces a cationic nonradical complex of chemical composition [Cr(III)(L(1)¯)2]I3, [2]I3 in almost quantitative yield. All the isolated complexes are primarily characterized by various spectroscopic techniques and magnetic measurements. While the molybdenum complex is diamagnetic, the two chromium complexes behave as simple paramagnets: ?eff (295 K), 2.81 ?B and 3.79 ?B for 2 and [2]I3, respectively. Single-crystal three-dimensional X-ray structures of 1, 2, [2]I3 are reported. The geometry of the Mo-complex is square antiprism (octacoordination), and that of the Cr-complexes is distorted octahedral. Redox properties of the complexes are studied by cyclic voltammetry and constant potential coulometry. The data are analyzed based on density functional theoretical calculations of molecular orbitals of redox isomers of the Cr complexes. The results indicated that the redox events in the complexes occur at the ligand center. The oxidation state of Cr in 2 is further assessed by XPS measurements and compared with the reported systems. PMID:25978689

  17. Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods

    NASA Astrophysics Data System (ADS)

    Saravanan, S.; Balachandran, V.

    2014-09-01

    This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm-1 and 3500-100 cm-1, respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined.

  18. Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods.

    PubMed

    Saravanan, S; Balachandran, V

    2014-09-15

    This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined. PMID:24813291

  19. Crystal structure of 1-butyl-2,3-di-methyl-imidazolium dicarba-7,8-nido-undeca-borate.

    PubMed

    Klemes, M J; Soderstrom, L; Hunting, J L; Larsen, A S

    2015-03-01

    In the title mol-ecular salt, C9H17N2 (+)·C2H12B9 (-), the carborane cage has a bridging B-H-B bond on the open B3C2 face. The butyl side chain of the cation adopts an extended conformation [C-C-C-C = 179.6?(1)°]. In the crystal, the imidazolium ring is almost coplanar with the open face of the carborane anion. The cations stack in the [010] direction and the dihedral angle between the imidazolium rings of adjacent cations is 68.45?(6)°. The butyl chains extend into the space between carborane anions. PMID:25844238

  20. CYP2C8- and CYP3A-mediated C-demethylation of (3-{[(4-tert-butylbenzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (CP-533,536), an EP2 receptor-selective prostaglandin E2 agonist: characterization of metabolites by high-resolution liquid chromatography-tandem mass spectrometry and liquid chromatography/mass spectrometry-nuclear magnetic resonance.

    PubMed

    Prakash, Chandra; Wang, Weiwei; O'Connell, Thomas; Johnson, Kim A

    2008-10-01

    CP-533,536, (3-{[(4-tert-butyl-benzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (1), an EP2 receptor-selective prostaglandin E2 agonist, is being developed to aid in the healing of bone fractures. To support the development of this program, in vitro metabolism of 1 was investigated in human liver microsomes and major recombinant human cytochrome P450 (P450) isoforms. 1 was metabolized in vitro by at least three recombinant human P450s: CYP3A4, CYP3A5, and CYP2C8. The turnover of 1 was NADPH-dependent and was completely inhibited by ketoconazole and quercetin in the CYP3A4/5 and CYP2C8 incubations, respectively. The major metabolic pathways were caused by oxidation of the tert-butyl moiety to form the omega-hydroxy metabolite (M4), oxidation of the pyridine moiety, and/or N-dealkylation of the methylphenoxy acetic acid moiety. The alcohol metabolite M4 was further oxidized to the corresponding carboxylic acid M3. In addition to these pathways, three unusual metabolites (M22, M23, and M26) resulting from C-demethylation of the tert-butyl group were identified using high-resolution liquid chromatography/tandem mass spectrometry and liquid chromatography/mass spectrometry/NMR. The C-demethylated metabolites were not detected on incubation of carboxylic acid metabolite M3 with either human liver microsomes or CYP3A/2C8 isoforms, suggesting that these metabolites were not derived from decarboxylation of M3. A possible mechanism for C-demethylation may involve the oxidation of M4 to form an aldehyde metabolite (M24), followed by P450-mediated deformylation, to give an unstable carbon-centered radical and formic acid. The carbon-centered radical intermediate then undergoes either oxygen rebound to form an alcohol metabolite M23 or hydrogen abstraction leading to an olefin metabolite M26. PMID:18653741

  1. Effects of the Spin Trap Agent Disodium ((tert-butylimino)methyl)benzene-1,3-disulfonate N-Oxide (Generic NXY-059) on Intracerebral Hemorrhage in a Rabbit Large Clot Embolic Stroke Model Combination Studies With Tissue Plasminogen Activator

    Microsoft Academic Search

    Paul A. Lapchak; Dalia M. Araujo; Donghuan Song; Jiandong Wei; Robert Purdy; Justin A. Zivin

    Background and Purpose—It has been proposed that the novel spin trap agent disodium-((tert- butylimino)methyl)benzene-1,3-disulfonate N-oxide (NXY-059) may be useful in the treatment of ischemia and stroke. To date, there is little information concerning the safety of NXY-059 when administered in combination with the only Food and Drug Administration-approved pharmacological agent for the treatment of stroke, the thrombolytic tissue plasminogen activator

  2. Neuroprotective Effects of the Spin Trap Agent Disodium((tert-butylimino)methyl)benzene-1,3-disulfonate N-Oxide (Generic NXY-059) in a Rabbit Small Clot Embolic Stroke Model Combination Studies With the Thrombolytic Tissue Plasminogen Activator

    Microsoft Academic Search

    Paul A. Lapchak; Dalia M. Araujo; Donghuan Song; Jiandong Wei; Justin A. Zivin

    Background and Purpose—It has been proposed that the novel spin trap agent disodium-((tert-butylimino)methyl)benzene- 1,3-disulfonate N-oxide (NXY-059) may be useful in the treatment of ischemic stroke. However, there is little information concerning the neuroprotective properties of NXY-059 when administered after an embolic stroke. Moreover, there is no information available concerning the combination of NXY-059 with the only Food and Drug Administration-approved

  3. Effect of ionic liquids on (vapor + liquid) equilibrium behavior of (water + 2-methyl-2-propanol)

    Microsoft Academic Search

    Lianzhong Zhang; Bingbang Qiao; Yun Ge; Dongshun Deng; Jianbing Ji

    2009-01-01

    Isobaric T, x, y data were reported for ternary systems of {water+2-methyl-2-propanol (tert-butyl alcohol, TBA)+ionic liquid (IL)} at p=100kPa. When the mole fraction of TBA on IL-free basis was fixed at 0.95, measurements were performed at IL mass fractions from 0.6 down to 0.05, in a way of repeated synthesis. The vapor-phase compositions were obtained by analytical methods and the

  4. Oxidative metabolism of butylated hydroxytoluene by hepatic and pulmonary microsomes from rats and mice.

    PubMed

    Thompson, J A; Malkinson, A M; Wand, M D; Mastovich, S L; Mead, E W; Schullek, K M; Laudenschlager, W G

    1987-01-01

    Metabolism of the antioxidant butylated hydroxytoluene (BHT; 2,6-di-tert-butyl-4-methylphenol) has been studied with liver and lung microsomes from rats and mice. The structures of several previously reported metabolites were confirmed, the identities of four new metabolites were determined, pathways of oxidation were investigated, and quantitative data were obtained for several of the products. Two main metabolic processes occur, hydroxylation of alkyl substituents and oxidation of the aromatic pi electron system. The former leads to the 4-hydroxymethyl product (BHT-BzOH) and a primary alcohol resulting from hydroxylation of a t-butyl group (BHT-tBuOH). Additional metabolites were produced by oxidation of BHT-BzOH to the corresponding benzaldehyde and benzoic acid derivatives. Hydroxylation of BHT-tBuOH occurs at the benzylic methyl position, and the resulting diol is oxidized further to the hydroxybenzaldehyde derivative. Oxidation of the pi system leads to the quinol, 2,6-di-t-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone, the quinone, 2,6-di-t-butyl-4-benzoquinone, and the quinone methide, 2,6-di-t-butyl-4-methylene-2,5-cyclohexadienone. Derivatives of the quinol and quinone with a hydroxylated t-butyl group were also formed. Quantitative data demonstrate that BHT-BzOH is the principal metabolite in rat liver and lung microsomes. On the other hand, mice produce large amounts of both BHT-BzOH and BHT-tBuOH in these tissues. The metabolite profile was similar in rat liver and lung. Mouse lung, however, produced more quinone relative to other metabolites than mouse liver.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2893710

  5. EXTRACTION OF RARE-EARTH ELEMENTS AND YTTRIUM FROM NITRIC ACID SOLUTIONS BY BUTYL(DIPHENYLPHOSPHINYL-METHYL)PHENYLPHOSPHINATE

    Microsoft Academic Search

    A. N. Turanov; V. K. Karandashev; A. N. Yarkevich

    2002-01-01

    The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 solutions by butyl(diphenylphosphinylmethyl)phenylphosphinate in organic diluents or on macroporous polymeric supports has been studied.The effect of HNO3 concentration in the aqueous phase and that of the extractant in the organic phase on the extraction of rare-earth elements

  6. 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.

    PubMed Central

    Carney, J M; Starke-Reed, P E; Oliver, C N; Landum, R W; Cheng, M S; Wu, J F; Floyd, R A

    1991-01-01

    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. These data can be interpreted to indicate that oxidation of cellular proteins may be a critical determinant of brain function. Moreover, it also implies that there is an age-related increase in vulnerability of tissue to oxidation that can be modified by free radical trapping compounds. PMID:1673789

  7. Thermally Switchable Thin Films of an ABC Triblock Copolymer of Poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate)

    SciTech Connect

    Zhang, Shanju [Georgia Institute of Technology; Liu, Zhan [Georgia Institute of Technology; Bucknall, David G. [Georgia Institute of Technology; He, Lihong [ORNL; Hong, Kunlun [ORNL; Mays, Jimmy [ORNL; Allen, Mark [Georgia Institute of Technology

    2011-01-01

    The thermo-responsive behavior of polymer films consisting of novel linear triblock copolymers of poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate) (PnBuMA-PMMA-P2FEMA) are reported using differential scanning calorimetry (DSC), atomic forcing microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contacting angle (CA) measurements. The surface morphology, wettability and chemical structure of thin films of these triblock copolymers on silicon wafers as a function of temperature have been investigated. It has been shown that the wettability of the films is thermally switchable. Detailed structural analysis shows that thermo-responsive surface composition changes are produced. The underlying mechanism of the thermoresponsive behavior is discussed.

  8. Identification of 1-butyl-3-(1-(4-methyl)naphtoyl)indole detected for the first time in "herbal high" products on the Italian market.

    PubMed

    Valoti, Ermanno; Casagni, Eleonora; Dell'Acqua, Lucia; Pallavicini, Marco; Roda, Gabriella; Rusconi, Chiara; Straniero, Valentina; Gambaro, Veniero

    2012-11-30

    The results of the analysis of some herbal products and powders adulterated with alkylindoles recovered on the Italian market between 2010 and 2011 are reported. Besides the well-known alkyindoles JWH-018 and JWH-073, other derivatives such as JWH-250 and AM-694 have been detected and for the first time in Italy 1-butyl-3-(1-(4-methyl)naphthoyl)indole (compound 1), the 4-methylnaphthoyl analogue of JWH-073. This compound as well as the other alkylindoles has been synthesized and characterized by (1)H NMR, (13)C NMR, DSC, GC/MS, and elemental analysis. The quantitative analyses of the samples have been carried out by means of the GC/FID method developed in our laboratory for the analysis of herbal high products containing naphthoylindoles; the quantity of the cannabimimetic substances ranged from 6 mg/g to 47 mg/g. PMID:22939184

  9. Fungal metabolism of tert-butylphenyl diphenyl phosphate.

    PubMed

    Heitkamp, M A; Freeman, J P; McMillan, D C; Cerniglia, C E

    1985-08-01

    The fungal metabolism of tert-butylphenyl diphenyl phosphate (BPDP) was studied. Cunninghamella elegans was incubated with BPDP for 7 days, and the metabolites formed were separated by thin-layer, gas-liquid, or high-pressure liquid chromatography and identified by 1H nuclear magnetic resonance and mass spectral techniques. C. elegans metabolized BPDP predominantly at the tert-butyl moiety to form the carboxylic acid 4-(2-carboxy-2-propyl)triphenyl phosphate. In addition, 4-hydroxy-4'-(2-carboxy-2-propyl)triphenyl phosphate, triphenyl phosphate, diphenyl phosphate, 4-(2-carboxy-2-propyl)diphenyl phosphate, 2-(4-hydroxyphenyl)-2-methyl propionic acid, and phenol were detected. Similar metabolites were found in the 28 fungal cultures which were examined for their ability to metabolize BPDP. Experiments with [14C]BPDP indicated that C. elegans metabolized 70% of the BPDP after 7 days and that the ratio of organic-soluble metabolites to water-soluble metabolites was 8:2. The results indicate that fungi preferentially oxidize BPDP at the alkyl side chain and at the aromatic rings to form hydroxylated derivatives. The trace levels of mono- and diaryl metabolites and the low level of phosphotriesterase activity measured in C. elegans indicate that phosphatase cleavage is a minor pathway for fungal metabolism of BPDP. PMID:4051482

  10. Aerobic Biodegradation of Per-Treated Methyl TertButyl Ether By Ozonation in an Up-Flow-Fixed-Bed Reactor

    Microsoft Academic Search

    M. Sadeghi; M. Arbabi; A. Nikpey; G. Mardani

    2009-01-01

    Problem Statement: MTBE is a common pollution of environmental and has become an issue of considerable concern in recent years. It i s not readily amenable to remove MTBE by conventional techniques in water treatment. In the present study, the feasibility of the continuous aerobic biodegradation of MTBE, was evaluated in an Up- Flow Fixed Bed Reactor (UFBR ). Approach:

  11. (6R)-2-tert-Butyl-6-[(4R,5S)-3-isopropyl-4-methyl-5-phenyl­oxazolidin-2-yl]phenol

    PubMed Central

    Koyanagi, Takaoki; Edler, Kate L.; Parrott, Raleigh W.; Hitchcock, Shawn R.; Ferrence, Gregory M.

    2010-01-01

    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. PMID:21580714

  12. 3-tert-Butyl 5-methyl (2R,4S,5R)-2-(4-methoxyphenyl)-4-(3-nitrophenyl)-1,3-oxazolidine-3,5-dicarboxylate

    PubMed Central

    Montiel-Smith, Sara; Bernès, Sylvain; Sandoval-Ramírez, Jesús; Meza-Reyes, Socorro; Dubois, Joëlle

    2012-01-01

    The title mol­ecule, C23H26N2O8, was synthesized in three steps starting from m-nitro­cinnamic acid. The central oxazolidine ring adopts an almost perfect envelope conformation with the O atom as the flap [puckering parameter ? = 0.3?(6)°]. The dihedral angle formed by the benzene rings is 61.81?(9)°. In the crystal, mol­ecules are connected into double chains parallel to [010] by C—H?O hydrogen bonds. The absolute configuration was assigned from the synthetic procedure. PMID:23284466

  13. Crystal structure of 5,5'-di-bromo-3,3'-di-tert-butyl-6,6'-di-methyl-biphenyl-2,2'-diol.

    PubMed

    Obata, Rika; Ohba, Shigeru; Einaga, Yasuaki; Nishiyama, Shigeru

    2015-05-01

    The whole mol-ecule of the title compound, C22H28Br2O2, is generated by twofold rotation symmetry. The dihedral angle of the biphenyl moiety is 85.05?(11)°. The hy-droxy groups show intra-molecular O-H?? inter-actions without any other hydrogen-bond acceptors. In the crystal, there are no other significant inter-molecular inter-actions present. PMID:25995903

  14. Characterization of Redox States of Ru(OH2)(Q)(tpy)2+ (Q = 3,5-di-tert-butyl-1,2-benzoquinone, tpy = 2,2#:6#,2#-terpyridine)and Related Species through Experimental and Theoretical Studies

    SciTech Connect

    Muckerman, J.T.; Tsai, M.-K.; , Rochford, J.; Polyansky, D.E.; Wada, T.; Tanaka, K.; Fujita, E.

    2009-04-27

    The redox states of Ru(OH{sub 2})(Q)(tpy){sup 2+} (Q = 3,5-di-tert-butyl-1,2-benzoquinone, tpy = 2,2':6',2''-terpyridine) are investigated through experimental and theoretical UV-vis spectra and Pourbaix diagrams. The electrochemical properties are reported for the species resulting from deprotonation and redox processes in aqueous solution. The formal oxidation states of the redox couples in the various intermediate complexes are systematically assigned using electronic structure theory. The controversy over the electronic assignment of ferromagnetic vs. antiferromagnetic coupling is investigated through comparison of ab initio methods and the broken-symmetry density functional theory (DFT) approach. The various pK{sub a} values and reduction potentials, including the consideration of proton-coupled electron-transfer (PCET) processes, are calculated, and the theoretical version of the Pourbaix diagram is constructed in order to elucidate and assign several previously ambiguous regions in the experimental diagram.

  15. Synthesis and X-ray structural characterization of a series of dimeric [Hg2(SePh)2X2(PR2R?)2] compounds (R = tert-butyl; R? = 4-N,N-dimethylaniline and X = Cl, Br, I, SCN, SePh)

    NASA Astrophysics Data System (ADS)

    Stieler, Rafael; Faoro, Eliandro; Cechin, Camila Nunes; Floriano, Luana; Lang, Ernesto Schulz

    2015-01-01

    This article presents the syntheses and characterization of five new compounds with the general formula [Hg2(SePh)2X2(PR2R?)2] (R = tert-butyl; R? = 4-N,N-dimethylaniline), where X = Cl (1a), Br (1b), I (1c), SCN (2), SePh (3). The compounds crystallized as dimeric {HgSe} units, although most of these chalcogenolate compounds appeared to be polymeric adamantanoid or fused adamantanoid species. The ligand structures of these compounds limited the growth of the molecular structures and promoted the formation of the dimeric form alone. The mercury centers were connected to one another through one ?-Cl and one ?-SePh bridge in 1a, and through two ?-SePh bridges in 1b, 1c, 2, and 3. The compounds were characterized by single crystal X-ray diffractometry, TGA, elemental analysis, and infrared spectroscopy.

  16. Crosslinked superhydrophobic films fabricated by simply casting poly(methyl methacrylate-butyl acrylate-hydroxyethyl methacrylate)-b-poly(perfluorohexylethyl methacrylate) solution

    NASA Astrophysics Data System (ADS)

    Wen, Xiufang; Ye, Chao; Cai, Zhiqi; Xu, Shouping; Pi, Pihui; Cheng, Jiang; Zhang, Lijuan; Qian, Yu

    2015-06-01

    This study focuses on the preparation of superhydrophobic films by crosslinkable polymer material-Poly(methyl methacrylate-butyl acrylate-hydroxyethyl methacrylate)-b-Poly(perfluorohexylethyl methacrylate) (P (MMA-BA-HEMA)-b-PFMA) with a simple one-step casting process. Nanoscale micelle particles with core-shell structure was obtained by dissolving the polymer and curing agent in the mixture of acetone and 1H, 1H, 5H octafluoropentyl-1,1,2,2 tetrafluoroethyl ether (FHT). Superhydrophobic films were fabricated by casting the micelle solution on the glass slides. By controlling the polymer concentration and acetone/FHT volume ratio, superhydrophobic polymer film with water contact angle of 153.2 ± 2.1° and sliding angle of 4° was obtained. By introducing a curing agent into the micelle solution, mechanical properties of the films can be improved. The adhension grade and hardness of the crosslinked superhydrophobic films reached 2 grade and 3H, respectively. The hydrophobicity is attributed to the synergistic effect of micro-submicro-nano-meter scale roughness by nanoscale micelle particles and low surface energy of fluoropolymer. This procedure makes it possible for widespread applications of superhydrophobic film due to its simplicity and practicability.

  17. Comparative analysis of skin sensitization potency of acrylates (methyl acrylate, ethyl acrylate, butyl acrylate, and ethylhexyl acrylate) using the local lymph node assay.

    PubMed

    Dearman, Rebecca J; Betts, Catherine J; Farr, Craig; McLaughlin, James; Berdasco, Nancy; Wiench, Karin; Kimber, Ian

    2007-10-01

    There are currently available no systematic experimental data on the skin sensitizing properties of acrylates that are of relevance in occupational settings. Limited information from previous guinea-pig tests or from the local lymph node assay (LLNA) is available; however, these data are incomplete and somewhat contradictory. For those reasons, we have examined in the LLNA 4 acrylates: butyl acrylate (BA), ethyl acrylate (EA), methyl acrylate (MA), and ethylhexyl acrylate (EHA). The LLNA data indicated that all 4 compounds have some potential to cause skin sensitization. In addition, the relative potencies of these acrylates were measured by derivation from LLNA dose-response analyses of EC3 values (the effective concentration of chemical required to induce a threefold increase in proliferation of draining lymph node cells compared with control values). On the basis of 1 scheme for the categorization of skin sensitization potency, BA, EA, and MA were each classified as weak sensitizers. Using the same scheme, EHA was considered a moderate sensitizer. However, it must be emphasized that the EC3 value for this chemical of 9.7% is on the borderline between moderate (<10%) and weak (>10%) categories. Thus, the judicious view is that all 4 chemicals possess relatively weak skin sensitizing potential. PMID:17868217

  18. A DFT study on the insertion of CO2 into styrene oxide catalyzed by 1-butyl-3-methyl-Imidazolium bromide ionic liquid.

    PubMed

    Marmitt, Sandro; Gonçalves, Paulo F B

    2015-06-30

    Green systems able to capture or fix CO2 are becoming more important specially to reduce environmental impacts. In this work, the mechanism of insertion of CO2 into styrene oxide (STYO) both in the absence and presence of the catalyst 1-butyl-3-methyl-imidazolium bromide (BMIm Br) was investigated through calculations based on density functional theory in the ?B97X-D level. Two different routes were considered and it was shown they are energetically available and compete against each other. For both routes, the rate-determinant step is the ring opening of STYO resulting from the nucleophilic attack of the Br(-) on the C atom from STYO and is associated mainly to the participation of the cation and the anion from the catalyst in the reaction. Reactive indices and noncovalent interaction analysis were used as a tool to investigate this reason. This work allowed a better comprehension of the underlying mechanism and the supplied data provide valuable support for the design of new more efficient ionic liquid catalyst. © 2015 Wiley Periodicals, Inc. PMID:25975698

  19. Physiologically based pharmacokinetic rat model for methyl tertiary-butyl ether; comparison of selected dose metrics following various MTBE exposure scenarios used for toxicity and carcinogenicity evaluation.

    PubMed

    Borghoff, Susan J; Parkinson, Horace; Leavens, Teresa L

    2010-09-10

    There are a number of cancer and toxicity studies that have been carried out to assess hazard from methyl tertiary-butyl ether (MTBE) exposure via inhalation and oral administration. MTBE has been detected in surface as well as ground water supplies which emphasized the need to assess the risk from exposure via drinking water contamination. This model can now be used to evaluate route-to-route extrapolation issues concerning MTBE exposures but also as a means of comparing potential dose metrics that may provide insight to differences in biological responses observed in rats following different routes of MTBE exposure. Recently an updated rat physiologically based pharmacokinetic (PBPK) model was published that relied on a description of MTBE and its metabolite tertiary-butyl alcohol (TBA) binding to alpha 2u-globulin, a male rat-specific protein. This model was used to predict concentrations of MTBE and TBA in the kidney, a target tissue in the male rat. The objective of this study was to use this model to evaluate the dosimetry of MTBE and TBA in rats following different exposure scenarios, used to evaluate the toxicity and carcinogenicity of MTBE, and compare various dose metrics under these different conditions. Model simulations suggested that although inhalation and drinking water exposures show a similar pattern of MTBE and TBA exposure in the blood and kidney (i.e. concentration-time profiles), the total blood and kidney levels following exposure of MTBE to 7.5mg/ml MTBE in the drinking water for 90 days is in the same range as administration of an oral dose of 1000 mg/kg MTBE. Evaluation of the dose metrics also supports that a high oral bolus dose (i.e. 1000 mg/kg MTBE) results in a greater percentage of the dose exhaled as MTBE with a lower percent metabolized to TBA as compared to dose of MTBE that is delivered over a longer period of time as in the case of drinking water. PMID:20561556

  20. Controlled human exposure to methyl tertiary butyl ether in gasoline: symptoms, psychophysiologic and neurobehavioral responses of self-reported sensitive persons.

    PubMed Central

    Fiedler, N; Kelly-McNeil, K; Mohr, S; Lehrer, P; Opiekun, R E; Lee, C; Wainman, T; Hamer, R; Weisel, C; Edelberg, R; Lioy, P J

    2000-01-01

    The 1990 Clean Air Act mandated oxygenation of gasoline in regions where carbon monoxide standards were not met. To achieve this standard, methyl tertiary butyl ether (MTBE) was increased to 15% by volume during winter months in many locations. Subsequent to the increase of MTBE in gasoline, commuters reported increases in symptoms such as headache, nausea, and eye, nose, and throat irritation. The present study compared 12 individuals selected based on self-report of symptoms (self-reported sensitives; SRSs) associated with MTBE to 19 controls without self-reported sensitivities. In a double-blind, repeated measures, controlled exposure, subjects were exposed for 15 min to clean air, gasoline, gasoline with 11% MTBE, and gasoline with 15% MTBE. Symptoms, odor ratings, neurobehavioral performance on a task of driving simulation, and psychophysiologic responses (heart and respiration rate, end-tidal CO(2), finger pulse volume, electromyograph, finger temperature) were measured before, during, and immediately after exposure. Relative to controls, SRSs reported significantly more total symptoms when exposed to gasoline with 15% MTBE than when exposed to gasoline with 11% MTBE or to clean air. However, these differences in symptoms were not accompanied by significant differences in neurobehavioral performance or psychophysiologic responses. No significant differences in symptoms or neurobehavioral or psychophysiologic responses were observed when exposure to gasoline with 11% MTBE was compared to clean air or to gasoline. Thus, the present study, although showing increased total symptoms among SRSs when exposed to gasoline with 15% MTBE, did not support a dose-response relationship for MTBE exposure nor the symptom specificity associated with MTBE in epidemiologic studies. Images Figure 1 Figure 2 PMID:10964796

  1. Development of physiologically based pharmacokinetic model for methyl tertiary-butyl ether and tertiary-butanol in male Fisher-344 rats.

    PubMed

    Borghoff, S J; Murphy, J E; Medinsky, M A

    1996-04-01

    Methyl tertiary-butyl ether (MTBE) and its metabolite tertiary-butanol (TBA) both cause renal tumors in chronically exposed male rats. Knowledge of the kinetic behavior of MTBE and TBA in rats and its comparison to the kinetics of these chemicals in humans will aid in assessing human risk. The objective of this study was to develop a physiologically based pharmacokinetic (PBPK) model for MTBE and TBA in rats that will form the basis for a human model. Physiological parameters such as blood flows, tissue volumes, and alveolar ventilation were obtained from the literature. Chemical-specific parameters such as the solubility of MTBE and TBA in blood and selected tissues and metabolic rate constants to describe whole-body metabolism of MTBE in rats were measured using vial equilibration and gas uptake techniques, respectively. MTBE metabolism was described in the model as occurring through two saturable pathways. The model was able to predict gas uptake data (100 to 2000 ppm starting concentrations) and levels of MTBE in blood of rats exposed to MTBE by inhalation (400 to 8000 ppm, 6 hr), i.v. (40 mg/kg), and oral (40 or 400 mg/kg) administration. Two different models to describe the dosimetry of TBA in a rat were tested for their ability to predict TBA blood levels after MTBE exposure. TBA blood levels were predicted best at low MTBE exposure concentrations using a two-compartment model. The pharmacokinetics of TBA appear to be far more complex than those of MTBE, and additional experimental data on TBA distribution and elimination will be necessary to refine the submodel. With a quantitative description of the important determinants of MTBE and TBA dosimetry understood, a better assessment of the potential toxic and cancer risk for humans exposed to MTBE can be made. PMID:8812274

  2. Saponification rates of isomeric butyl esters in aqueous 1,4-dioxane 

    E-print Network

    Ruhnke, Edward Vincent

    1954-01-01

    mixture. Unfortunately, this method cannot be used where tert-butyl alcohol is involved. For these cases, either method (l) with the silver salt or a modification of the acid chloride method was * 28 used. There are a number of ways by which...-valerate and other materials are given in Table I. All of these materials were purified by distillation in the Todd column. Isobutyl n-Valerate and sec-Butyl n-Valerate. - These two esters were prepared in a manner similar to that for the n-butyl ester. tert-Butyl...

  3. Formation of 8-methylguanine as a result of DNA alkylation by methyl radicals generated during horseradish peroxidase-catalyzed oxidation of methylhydrazine.

    PubMed

    Augusto, O; Cavalieri, E L; Rogan, E G; RamaKrishna, N V; Kolar, C

    1990-12-25

    Methylhydrazine oxidation promoted by horseradish peroxidase-H2O2 or ferricyanide led to the generation of high yields of methyl radicals and to the formation of 7-methylguanine and 8-methylguanine upon interaction with calf thymus DNA. Methyl radicals were identified by spin-trapping experiments with alpha-(4-pyridyl-1-oxide)-N-tert-butyl nitrone and tert-nitrosobutane. The methylated guanine products were identified in the neutral hydrolysates of treated DNA by high pressure liquid chromatography (HPLC) analysis and spiking with authentic samples. The structure of 8-methylguanine, a product not previously reported in enzymatic systems, was confirmed by HPLC chromatography, UV absorbance, and mass spectrometry. The formation of 8-methylguanine suggests a possible role for carbon-centered radicals as DNA-alkylating agents. PMID:2176204

  4. EPR Equilibration Measurement of the C–H Bond Enthalpy in the Methylene Groups of 1,3,5Trimethyl2,4,6-tris(3,5-di- tert -butyl-4-hydroxybenzyl)benzene (Irganox)

    Microsoft Academic Search

    Sara Noemí Mendiara; Marta E. J. Coronel

    2010-01-01

    On the basis of previous and current studies, it has been possible to evaluate and compare the bond dissociation energies\\u000a of the phenol (O–H) bond and of the methylene and methyl (C–H) bonds in Irganox (trade name) by means of electron paramagnetic\\u000a resonance records of galvinoxyl–irganoxyl hydrogen transfer reaction equilibria. The bond dissociation enthalpy of the C–H\\u000a methylene and methyl

  5. 2-[4-(2-{5-tert-Butyl-2-chloro-3-[2-(3-pentyl-1,3-benzothia­zol-2-yl­idene)ethyl­idene]cyclo­hex-1-en­yl}ethen­yl)-3-cyano-5,5-dimethyl­furan-2-yl­idene]malono­nitrile

    PubMed Central

    Gainsford, Graeme J.; Ashraf, Mohamed; Kay, Andrew J.

    2013-01-01

    In the title mol­ecule, C36H39ClN4OS, the non-aromatic part of the cyclo­hex-1-enyl ring and the attached tert-butyl group are disordered over two conformations with occupancy ratios of 0.52?(3):0.48?(3) and 0.53?(3):0.47?(3), respectively. The polyene chain single- and double-bond dimensions contrast with a closely related compound [Bouit et al. (2007 ?). Chem. Mater. 19, 5325–5335] with an approximate 19° twist between donor and acceptor ends of the mol­ecule, related to the additional intra­molecular C—H?S inter­action. In the title compound, the mol­ecules pack into dimeric units about centres of symmetry utilizing weak C—H?N(cyano) and C—H?O attractive inter­actions, building both chain and ring motifs about the centres [R 2 2(8) and R 2 2(9)]. Adjacent dimeric sets then form a herringbone configuration. PMID:23476383

  6. Development of a Physiologically Based Pharmacokinetic Model for Methyl tertiary-Butyl Ether and tertiary-Butanol in Male Fischer344 Rats

    Microsoft Academic Search

    S. J. Borghoff; J. E. Murphy; M. A. Medinsky

    1996-01-01

    Methyltertiary-butyl ether (MTBE) and its metabolitetertiary-butanol (TBA) both cause renal tumors in chronically exposed male rats. Knowledge of the kinetic behavior of MTBE and TBA in rats and its comparison to the kinetics of these chemicals in humans will aid in assessing human risk. The objective of this study was to develop a physiologically based pharmacokinetic (PBPK) model for MTBE

  7. X-ray diffraction and IR spectral characteristics of zinc(II)tetra- tert-butylphthalocyanine

    NASA Astrophysics Data System (ADS)

    Lebedeva, Nataliya Sh.; Parfenyuk, Elena V.; Malkova, Elena A.

    2007-11-01

    According to well-known procedures, ?- and ?-crystal polymorphic modifications of zinc(II)tetra- tert-butylphthalocianine (Zn( t-Bu) 4Pc) were prepared and X-ray analysis of their powders was carried out. It was found that four tert-butyl groups in Zn( t-Bu) 4Pc molecule do not prevent the formation of the ?- and ?-polymorphs. The ?- and ?-polymorphs differ from each other mainly by a mutual arrangement of neighboring metallophthalocyenine molecules in ?-stacking. Comparison of IR spectra of the ?- and ?-polymorphs of ZnPc and Zn( t-Bu) 4Pc was carried out. It was indicated that new bands appear at 670-690, 1256 and 1362 cm -1 in the spectrum of Zn( t-Bu) 4Pc in comparison with that of ZnPc. The appearance of new band at 1256 cm -1 is assigned to rocking C-CH 3 vibrations and the band at 1362 cm -1 to symmetrical deformational C-H vibrations of methyl groups of the peripheral substitutes. The main spectral characteristics for identification of the polymorphic modifications of Zn( t-Bu) 4Pc are listed.

  8. 5-tert-Butyl 3-ethyl 1-isopropyl-4,5,6,7-tetra­hydro-1H-pyrazolo­[4,3-c]pyridine-3,5-dicarboxyl­ate

    PubMed Central

    Guo, Huan-Mei

    2011-01-01

    In the title compound, C17H27N3O4, the six-membered ring adopts a half-chair conformation with the N atom and the adjacent methyl­ene C atom displaced by ?0.391?(2) and 0.358?(2)?Å, respectively, from the plane of the other four atoms. In the crystal, mol­ecules are linked by weak C—H?O inter­actions. PMID:22199750

  9. An X-ray crystallographic and density functional theory study of (3Z)-4-(5-ethylsulfonyl-2-hydroxyanilino)pent-3-en-2-one and (3Z)-4-(5-tert-butyl-2-hydroxyanilino)pent-3-en-2-one.

    PubMed

    Akerman, Kate J; Munro, Orde Q

    2013-03-01

    The Schiff base enaminones (3Z)-4-(5-ethylsulfonyl-2-hydroxyanilino)pent-3-en-2-one, C13H17NO4S, (I), and (3Z)-4-(5-tert-butyl-2-hydroxyanilino)pent-3-en-2-one, C15H21NO2, (II), were studied by X-ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C-C=C-N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino-phenol group canted relative to the rest of the molecule; the twist about the N(enamine)-C(aryl) bond leads to dihedral angles of 40.5?(2) and -116.7?(1)° for (I) and (II), respectively. Compound (I) has a bifurcated intramolecular hydrogen bond between the N-H group and the flanking carbonyl and hydroxy O atoms, as well as an intermolecular hydrogen bond, leading to an infinite one-dimensional hydrogen-bonded chain. Compound (II) has one intramolecular hydrogen bond and one intermolecular C=O...H-O hydrogen bond, and consequently also forms a one-dimensional hydrogen-bonded chain. The DFT-calculated structures [in vacuo, B3LYP/6-311G(d,p) level] for the keto tautomers compare favourably with the X-ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86?kJ?mol(-1) lower in energy than the enol tautomers for (I) and (II), respectively. PMID:23459351

  10. 76 FR 77709 - Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ...FRL-9327-6] Butyl acrylate-methacrylic acid-styrene polymer; Tolerance Exemption...tolerance for residues of 2-Propenoic acid, 2-methyl-, polymer with butyl 2-propenoate...also known as butyl acrylate-methacrylic acid-styrene polymer when used as an...

  11. MP2, CCSD(T), and Density Functional Theory Study of the 2-Butyl Cation: New Insight into the Methyl- and Hydrogen-Bridged Structures.

    PubMed

    Rasul, Golam; Prakash, G K Surya; Olah, George A

    2015-06-01

    Using the MP2, CCSD(T), and DFT (B3LYP) methods, the structures and energies of the 2-butyl cation (C4H9(+)) were calculated. Energetically, the C-C hyperconjugated structure 1 and hydrogen-bridged structure 2 were found to be almost identical at all levels. The (13)C NMR chemical shifts of 1 and 2 were computed by the GIAO-CCSD(T) method using different geometries. On the basis of calculated relative energies and calculated (13)C NMR chemical shifts, an equilibrium involving 1 and 2 (in a 50:50 ratio) seemed likely responsible for the experimentally observed (13)C NMR chemical shifts in superacid solutions at -80 °C. However, on the basis of computed and experimental frequencies the hydrogen-bridged structure 2 is most likely responsible for the experimentally observed frequencies in the solid state at -125 °C. PMID:25964993

  12. Hydrogen Bonding and Solvent Effects on Complexation of Alkali Metal Cations by Lower Rim Calix[4]arene Tetra( O -[ N -acetyl- D -phenylglycine methyl ester]) Derivative

    Microsoft Academic Search

    VLADISLAV TOMISIC ´; NIVES GALIC ´; Branimir Bertoša; Leo Frkanec; Vladimir Simeon; Mladen Žini?

    2005-01-01

    Complexation of alkali metal cations with 5,11,17,23-tetra-tert-butyl-26,28,25,27-tetrakis(O-methyl-D-?-phenylglycylcarbonylmethoxy)calix[4]arene (L) was studied by means of spectrophotometric, conductometric and potentiometric titrations at 25 °C. The solvent effect on the binding ability of L was examined by using two solvents with different affinities for hydrogen bonding, viz. methanol and acetonitrile. Despite the presence of intramolecular NH···O=C hydrogen bonds in L, which need to be disrupted

  13. A study on the solvent extraction of Pd\\/II\\/ with 1,2,3-benzotriazole into methyl iso-butyl ketone

    Microsoft Academic Search

    I. A. Mendes; Z. R. Turel

    1986-01-01

    A novel method has been developed for the extraction of Pd\\/II\\/ with 1,2,3-benzotriazole \\/1,2,3-BT\\/ into methyl isobutyl ketone \\/MIBK\\/ at a pH of 4.0. The effects of pH, time of equilibration, solvent, anions and cations on the extraction coefficient have been evaluated. The stoichiometry of the extracted species of 12 was obtained by the slope ratio method and by the

  14. 5-Lipoxygenase-activating protein inhibitors. Part 3: 3-{3- tert-Butylsulfanyl-1-[4-(5-methoxy-pyrimidin-2-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1 H-indol-2-yl]-2,2-dimethyl-propionic acid (AM643)—A potent FLAP inhibitor suitable for topical administration

    Microsoft Academic Search

    Nicholas Stock; Christopher Baccei; Gretchen Bain; Charles Chapman; Lucia Correa; Janice Darlington; Christopher King; Catherine Lee; Daniel S. Lorrain; Pat Prodanovich; Angelina Santini; Kevin Schaab; Jilly F. Evans; John H. Hutchinson; Peppi Prasit

    2010-01-01

    AM643 (compound 6, 3-{3-tert-butylsulfanyl-1-[4-(5-methoxy-pyrimidin-2-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid) was identified as a potential candidate for formulation as a topical agent for the treatment of skin disorders involving leukotriene production. Dermal application of 6 using a prototypical vehicle in a murine ear arachidonic acid model showed significant reduction in the concentrations of leukotrienes in mouse skin with concomitant reduction in ear swelling.

  15. 5-Lipoxygenase-activating protein inhibitors. Part 3: 3-{3-tert-Butylsulfanyl-1-[4-(5-methoxy-pyrimidin-2-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid (AM643)-A potent FLAP inhibitor suitable for topical administration.

    PubMed

    Stock, Nicholas; Baccei, Christopher; Bain, Gretchen; Chapman, Charles; Correa, Lucia; Darlington, Janice; King, Christopher; Lee, Catherine; Lorrain, Daniel S; Prodanovich, Pat; Santini, Angelina; Schaab, Kevin; Evans, Jilly F; Hutchinson, John H; Prasit, Peppi

    2010-08-01

    AM643 (compound 6, 3-{3-tert-butylsulfanyl-1-[4-(5-methoxy-pyrimidin-2-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid) was identified as a potential candidate for formulation as a topical agent for the treatment of skin disorders involving leukotriene production. Dermal application of 6 using a prototypical vehicle in a murine ear arachidonic acid model showed significant reduction in the concentrations of leukotrienes in mouse skin with concomitant reduction in ear swelling. PMID:20566292

  16. A magnetically separable biocatalyst for resolution of racemic naproxen methyl ester.

    PubMed

    Ozyilmaz, Elif; Sayin, Serkan

    2013-11-01

    Candida rugosa lipase (CRL) was encapsulated via the sol-gel method, using 5, 11, 17, 23-tetra-tert-butyl-25,27-bis(2-aminopyridine)carbonylmethoxy-26, 28-dihydroxy-calix[4]arene-grafted magnetic Fe3O4 nanoparticles (Calix-M-E). The catalytic activity of encapsulated lipase (Calix-M-E) was tested both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic naproxen methyl ester. The present study demonstrated that the calixarene-based compound has the potential to enhance both reaction rate and enantioselectivity of the lipase-catalyzed hydrolysis of racemic naproxen methyl ester. The encapsulated lipase (Calix-M-E) had great catalytic activity and enantioselectivity (E > 400), as well as remarkable reusability as compared to the encapsulated lipase without supports (E = 137) for S-Naproxen. PMID:23525833

  17. Crystal structure of an unknown solvate of bis-(tetra-n-butyl-ammonium) [N,N'-(4-tri-fluoro-methyl-1,2-phenyl-ene)bis-(oxamato)-?(4) O,N,N',O']nickelate(II).

    PubMed

    Eya'ane Meva, François; Schaarschmidt, Dieter; Rüffer, Tobias

    2015-06-01

    In the title compound, [N(C4H9)4]2[Ni(C11H3F3N2O6)] or [N(n-Bu)4]2[Ni(topbo)] [n-Bu = n-butyl and topbo = 4-tri-fluoro-methyl-1,2-phenyl-enebis(oxamate)], the Ni(2+) cation is coordinated by two deprotonated amido N atoms and two carboxyl-ate O atoms, setting up a slightly distorted square-planar coordination environment. The [Ni(topbo](2-) anion lies on a twofold rotation axis. Due to an incompatibility with the point-group symmetry of the complete mol-ecule, orientational disorder of the CF3 group is observed. The tetra-hedral ammonium cations and the anion are linked by weak inter-molecular C-H?O and C-H?F hydrogen-bonding inter-actions into a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9-18] following unsuccessful attempts to model it as plausible solvent mol-ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol-ecule. PMID:26090126

  18. Crystal structure of an unknown solvate of bis­(tetra-n-butyl­ammonium) [N,N?-(4-tri­fluoro­methyl-1,2-phenyl­ene)bis­(oxamato)-?4 O,N,N?,O?]nickelate(II)

    PubMed Central

    Eya’ane Meva, François; Schaarschmidt, Dieter; Rüffer, Tobias

    2015-01-01

    In the title compound, [N(C4H9)4]2[Ni(C11H3F3N2O6)] or [N(n-Bu)4]2[Ni(topbo)] [n-Bu = n-butyl and topbo = 4-tri­fluoro­methyl-1,2-phenyl­enebis(oxamate)], the Ni2+ cation is coordinated by two deprotonated amido N atoms and two carboxyl­ate O atoms, setting up a slightly distorted square-planar coordination environment. The [Ni(topbo]2? anion lies on a twofold rotation axis. Due to an incompatibility with the point-group symmetry of the complete mol­ecule, orientational disorder of the CF3 group is observed. The tetra­hedral ammonium cations and the anion are linked by weak inter­molecular C—H?O and C—H?F hydrogen-bonding inter­actions into a three-dimensional network. A region of electron density was treated with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18] following unsuccessful attempts to model it as plausible solvent mol­ecule(s). The given chemical formula and other crystal data do not take into account the unknown solvent mol­ecule. PMID:26090126

  19. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...19 volumes of 60° Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. (f) Identification...and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A yellow precipitate...

  20. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...dissolve 5 grams of red mercuric oxide in 20 ml of concentrated sulfuric acid; add this solution to 80 ml of distilled water, and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A yellow precipitate forms...

  1. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...above 85 °C. More than 95 percent should distill between 81 °?83 °C. (d) Dryness at 20 °C. Miscible without turbidity with 19 volumes of 60° Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. (f)...

  2. IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (Preliminary Assessment Materials)

    EPA Science Inventory

    In August 2013, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for TBA to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in c...

  3. Methylation Status and Expression of Human Telomerase Reverse Transcriptase mRNA in Relation to Hypermethylation of the p16 gene in Colorectal Cancers as Analyzed by Bisulfite PCR-SSCP

    Microsoft Academic Search

    Kiyoaki Nomoto; Masato Maekawa; Kokichi Sugano; Mineko Ushiama; Noriko Fukayama; Shin Fujita; Tadao Kakizoe

    2002-01-01

    Background: The expression level of human telomerase reverse transcriptase (hTERT) is correlated with telomerase activity and is expressed at high levels in malignant tumors. It is of interest whether expression of hTERT is regulated by methylation of the CpG island in the promoter of the hTERT gene. We examined hTERT expression and methylation status of the hTERT and other genes

  4. Subchronic exposure to ethyl tertiary butyl ether resulting in genetic damage in Aldh2 knockout mice.

    PubMed

    Weng, Zuquan; Suda, Megumi; Ohtani, Katsumi; Mei, Nan; Kawamoto, Toshihiro; Nakajima, Tamie; Wang, Rui-Sheng

    2013-09-15

    Ethyl tertiary butyl ether (ETBE) is biofuel additive recently used in Japan and some other countries. Limited evidence shows that ETBE has low toxicity. Acetaldehyde (AA), however, as one primary metabolite of ETBE, is clearly genotoxic and has been considered to be a potential carcinogen. The aim of this study was to evaluate the effects of ALDH2 gene on ETBE-induced genotoxicity and metabolism of its metabolites after inhalation exposure to ETBE. A group of wild-type (WT) and Aldh2 knockout (KO) C57BL/6 mice were exposed to 500ppm ETBE for 1-6h, and the blood concentrations of ETBE metabolites, including AA, tert-butyl alcohol and 2-methyl-1,2-propanediol, were measured. Another group of mice of WT and KO were exposed to 0, 500, 1750, or 5000ppm ETBE for 6h/day with 5 days per weeks for 13 weeks. Genotoxic effects of ETBE in these mice were measured by the alkaline comet assay, 8-hydroxyguanine DNA-glycosylase modified comet assay and micronucleus test. With short-term exposure to ETBE, the blood concentrations of all the three metabolites in KO mice were significantly higher than the corresponding concentrations of those in WT mice of both sexes. After subchronic exposure to ETBE, there was significant increase in DNA damage in a dose-dependent manner in KO male mice, while only 5000ppm exposure significantly increased DNA damage in male WT mice. Overall, there was a significant sex difference in genetic damage in both genetic types of mice. These results showed that ALDH2 is involved in the detoxification of ETBE and lack of enzyme activity may greatly increase the sensitivity to the genotoxic effects of ETBE, and male mice were more sensitive than females. PMID:23810710

  5. para-Selective t-butylation of phenol over mesoporous H-AlMCM-41

    Microsoft Academic Search

    A Sakthivel; S. K Badamali; P Selvam

    2000-01-01

    Vapour phase alkylation of phenol with t-butyl alcohol (2-methyl-2-propanol) was carried out over mesoporous H-AlMCM-41 in the temperature range 448?498 K. In this reaction, p-t-butyl phenol was obtained as a major product with high selectivity. While the phenol conversion increases with a decrease in phenol-to-t-butyl alcohol ratio, the catalytic activity decreases with time-on-stream due to deactivation of the catalyst. At

  6. Hydrosilylation reactions of hydrosilatrane and 2-methyl-6-ethyl-1,3-dioxa-6-aza-2-silacyclooctane

    SciTech Connect

    Voronkov, M.G.; Rakhlin, V.I.; Adamovich, S.N.; Petukhov, L.P.; Mirskov, R.G.; Yarosh, N.K.; Kuznetsov, A.L.; Sigalov, M.V.

    1986-10-20

    The authors have investigated the reaction of 1-hydrosilatrane (I) with a series of unsaturated compounds in benzene (1-hexene, 1-vinylsilatrane, 1-hexyne, phenylacetylene, propargyl chloride, and vinyl acetylene) using known methods for inducing hydrosilylation. The catalysts used included H/sub 2/PtCl/sub 6/, Et/sub 3/N, palladium and rhodium complexes and tert-butyl and benzoyl peroxides. Neither these nor thermal or photochemical initiation led to the expected result, and in no case did (I) take part in the reaction. 1-Hydrosilatrane does not react with monosubstituted ethylenes (or acetylenes) either in the presence of platinum or rhodium complexes or upon initiation of the reactions using organic peroxides, UV irradiation, or thermal methods. By contrast, 2-methyl-6-ethyl-1,3-dioxa-6-aza-2-silacyclooctane readily takes part in hydrosilylation of the indicated unsaturated compounds when Rhacac (CO)/sub 2/ is present.

  7. Identification of tertiary butyl alcohol (TBA)-utilizing organisms in BioGAC reactors using 13 CDNA stable isotope probing

    Microsoft Academic Search

    Denise Aslett; Joseph Haas; Michael Hyman

    2011-01-01

    Biodegradation of the gasoline oxygenates methyl tertiary-butyl ether (MTBE) and ethyl tertiary-butyl ether (ETBE) can cause tertiary butyl alcohol (TBA) to accumulate in gasoline-impacted environments. One remediation option for TBA-contaminated groundwater\\u000a involves oxygenated granulated activated carbon (GAC) reactors that have been self-inoculated by indigenous TBA-degrading\\u000a microorganisms in ground water extracted from contaminated aquifers. Identification of these organisms is important for

  8. LIQUID PHASE OXIDATION OF THIOPHENOL AND INDENE BY t-BUTYL HYDROPEROXIDE AND OXYGEN

    Microsoft Academic Search

    George W. Mushrush; John M. Watkinsa; Robert N. Hazlett; Dennis R. Hardy; Harold G. Eaton

    1988-01-01

    The tert-butyl hydroperoxide (tBHP) or oxygen initiated oxidation of thiophenol in the presence of the active olefin indene was examined in benzene at 120C. The reaction is kinetically complex, but it was possible to relate the product distribution to a few competing reactions. The product mix was determined for several reaction time periods. The product slate was similar for all

  9. Comparison of stabilization by Vitamin E and 2,6-di-tert-butylphenols during polyethylene radio-thermal-oxidation

    NASA Astrophysics Data System (ADS)

    Richaud, Emmanuel

    2014-10-01

    This paper reports a compilation of data for PE+Vitamin E and 2,6-di-tert-butylphenols oxidation in radio-thermal ageing. Data unambiguously show that Vitamin E reacts with Prad and POOrad whereas 2,6-di-tert-butyl phenols only react with POOrad . Kinetic parameters of the stabilization reactions for both kinds of antioxidants were tentatively extracted from phenol depletion curves, and discussed regarding the structure of the stabilizer. They were also used for completing an existing kinetic model used for predicting the stabilization by antioxidants. This one permits to compare the efficiency of stabilizer with dose rate or sample thickness.

  10. Butyl methoxy dibenzoylmethane.

    PubMed

    Kockler, Jutta; Robertson, Sherryl; Oelgemöller, Michael; Davies, Murray; Bowden, Bruce; Brittain, Harry G; Glass, Beverley D

    2013-01-01

    A comprehensive profile on Butyl methoxy dibenzoylmethane, one of the most commonly used ultraviolet (UV) filters in topical sunscreen products, is prepared. This UV filter, often referred to as Avobenzone, has its main absorbance in the UVA I region of the spectrum and is susceptible to photodegradation. The profile contains the following sections: general information, use and mechanism of action, method of preparation, physical characteristics, methods of analysis, stability, and toxicity. The physical characteristics section includes the melting range, differential scanning calorimetry, partition coefficient, ionization constant, solubility, and UV, infrared, nuclear magnetic resonance ((1)H NMR and (13)C NMR) and mass spectrometry and X-ray powder diffractometry. The method of analysis section in addition to compendial identification and purity and assay methods includes thin-layer gas and high-performance liquid chromatography. The photostability and photostabilization of Butyl methoxy dibenzoylmethane, in addition to its toxicity, are also documented. PMID:23668403

  11. Analysis of Organic Molecules Extracted from Mars Analogues and Influence of Their Mineralogy Using N-Methyl-N-(tert-butyldimethylsilyl)Trifluoroacetamide Derivatization Coupled with Gas Chromatography Mass Spectrometry in Preparation for the Sample Analysis at Mars Derivatization Experiment on the Mars Science Laboratory Mission

    NASA Technical Reports Server (NTRS)

    Stalport, F.; Glavin, D. P.; Eigenbrode, J. L.; Bish, D.; Blake, D.; Coll, P.; Szopa, C.; Buch, A.; McAdam, A.; Dworkin, J. P.; Mahaffy, P. R.

    2012-01-01

    The search for complex organic molecules on Mars, including important biomolecules such as amino acids and carboxylic acids will require a chemical extraction and derivatization step to transform these organic compounds into species that are sufficiently volatile to be detected by gas chromatography mass spectrometry (GCMS). We have developed, a one-pot extraction and chemical derivatization protocol using N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide (DMF) for the Sample Analysis at Mars (SAM) experiment on the Mars Science Laboratory (MSL). The temperature and duration the derivatization reaction, pre-concentration of chemical derivatives, and gas chromatographic separation parameters have been optimized under SAM instrument design constraints. MTBSTFA/DMF extraction and derivatization at 300 C for several minutes of a variety of terrestrial Mars analogue materials facilitated the detection of amino acids and carboxylic acids in a surface soil sample collected from the Atacama Desert and a carbonate-rich stromatolite sample from Svalbard. However, the rapid reaction of MTBSTFA with water in several analogue materials that contained high abundances of hydrated minerals and the possible deactivation of derivatized compounds by iron oxides, as detected by XRD/XRF using the CheMin field unit Terra, proved to be highly problematic for the direct extraction of organics using MTBSTFA, The combination of pyrolysis and two different chemical derivatization methods employed by SAM should enable a wide range of organic compounds to be detected by GCMS if present on Mars,

  12. Crystal structure of hexa­kis­(?2-4-tert-but­oxy-4-oxobut-2-en-2-olato)trizinc

    PubMed Central

    Shtokvish, Olgerd O.; Koval, Lyudmila I.; Pekhnyo, Vasyl I.

    2014-01-01

    The title complex, systematic name hexa­kis­(?2-4-tert-but­oxy-4-oxobut-2-en-2-olato)-1:2?9 O 2,O 4:O 2;2:3?9 O 2,O 4:O 2-trizinc, [Zn3(C8H13O3)6], syn­the­sized from tert-butyl aceto­acetate and di­ethyl­zinc, consists of trinuclear centrosymmetric mol­ecules of an approximate C 3i symmetry. The three metal cations are arranged in a linear fashion, with the central ZnII atom located on a centre of symmetry. All three metal cations exhibit a distorted octa­hedral coordination geometry. The terminal ZnII cations are chelated by three tert-butyl aceto­acetate ligands and these units are connected to the central ZnII atom by the bridging enolate O atoms. PMID:25552972

  13. An electrospray ionization tandem mass spectrometric study of p-tert-butylcalix[6]arene complexation with ammonium hydroxide, and ammonium and sodium ions.

    PubMed

    Sassine, André; Martins-Júnior, Helio A; Lebre, Daniel T; Valli, Felipe; Pires, Maria A F; Vega, Oscar; Felinto, Maria C F C

    2008-01-01

    The formation of complexes involving p-tert-butylcalix[6]arene with neutral and charged species has been investigated by tandem mass spectrometry combined with electrospray ionization. Complexes of p-tert-butylcalix[6]arene with NH4+ ions were observed in the ratios 1:1, 2:1, and 3:1, together with the complexes of p-tert-butylcalix[6]arene with NH4OH and Na+ ions in the ratios 1:1:1, 2:1:1, and 3:1:1. A single 1:1 complex of p-tert-butylcalix[6]arene with Na+ ions was observed. In addition, a doubly charged complex of p-tert-butylcalix[6]arene with NH4OH, Na+, and NH4+ ions in the ratio 6:1:1:1 was observed. The identity of each complex was determined by mass analysis of product ions formed by the application of a declustering potential over the range 20-220 V and by observation of product ion mass spectra wherein the collision energy was varied from 5 to 50 eV. Fragmentation of the complexes is characterized by the facile loss of the ammonia molecule, sodium and ammonium ions, loss of neutral p-tert-butylcalix[6]arene, and successive neutral losses of C4H8 from the six tert-butyl groups in each p-tert-butylcalix[6]arene molecule. PMID:18181224

  14. Polyfluoro-tert-alkylsulfenyl chlorides

    Microsoft Academic Search

    A. Yu. Sizov; A. F. Kolomiets; A. V. Fokin

    1988-01-01

    Polyfluoroalkylsulfenyl chlorides with tert-alkyl groups were obtained and these compounds were found to be similar to sulfenyl chlorides with primary polyfluoroalkyl groups in electrophilic addition at the C=C bond and are distinguished only in somewhat reduced reactivity.

  15. N-tert-Butoxycarbonylation of Structurally Diverse Amines and Sulfamides under Water-Mediated Catalyst-Free Conditions.

    PubMed

    Cheraiet, Zinelaabine; Ouarna, Souad; Hessainia, Sihem; Berredjem, Malika; Aouf, Nour-Eddine

    2012-01-01

    A simple, efficient, and eco-friendly protocol for the N-Boc protection of the amine moiety in a variety of compounds with di-tert-butyl dicarbonate under water-acetone catalyst-free conditions is described. The corresponding monocarbamate is obtained in excellent yields on short reaction times. No competitive side reactions such as isocyanate urea and O-Boc were observed. This method represents a reasonable alternative to the previous reported protection procedures. PMID:24052842

  16. N-tert-Butoxycarbonylation of Structurally Diverse Amines and Sulfamides under Water-Mediated Catalyst-Free Conditions

    PubMed Central

    Cheraiet, Zinelaabine; Ouarna, Souad; Hessainia, Sihem; Berredjem, Malika; Aouf, Nour-Eddine

    2012-01-01

    A simple, efficient, and eco-friendly protocol for the N-Boc protection of the amine moiety in a variety of compounds with di-tert-butyl dicarbonate under water-acetone catalyst-free conditions is described. The corresponding monocarbamate is obtained in excellent yields on short reaction times. No competitive side reactions such as isocyanate urea and O-Boc were observed. This method represents a reasonable alternative to the previous reported protection procedures. PMID:24052842

  17. Synthesis and properties of phosphono-derivatives of methyl stearate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of phosphono-derivatives of methyl stearate (PhDMS) were synthesized from methyl oleate and dialkyl H-phosphonates (dialkyl-phosphites). The alkyl groups in the phosphonates were methyl, ethyl, and butyl. The reaction can be carried to 98+% completion with a radical initiator. It is possibl...

  18. TERT promoter mutations in cancer development.

    PubMed

    Heidenreich, Barbara; Rachakonda, P Sivaramakrishna; Hemminki, Kari; Kumar, Rajiv

    2014-02-01

    Human telomerase reverse transcriptase (TERT) encodes a rate-limiting catalytic subunit of telomerase that maintains genomic integrity. TERT expression is mostly repressed in somatic cells with exception of proliferative cells in self-renewing tissues and cancer. Immortality associated with cancer cells has been attributed to telomerase over-expression. The precise mechanism behind the TERT activation in cancers has mostly remained unknown. The newly described germline and recurrent somatic mutations in melanoma and other cancers in the TERT promoter that create de novo E-twenty six/ternary complex factors (Ets/TCF) binding sites, provide an insight into the possible cause of tumor-specific increased TERT expression. In this review we discuss the discovery and possible implications of the TERT promoter mutations in melanoma and other cancers. PMID:24657534

  19. Molecular Structure of Di-t-butyl-peroxide

    NSDL National Science Digital Library

    2002-09-27

    Di-tert-Butyl Peroxide is used as a polymerization initiator, curing agent and cross-linking agent. It is a highly reactive compound, which can be flammable when exposed to open flames and sparks. Upon exposure to heat, it undergoes gaseous decomposition. Its vapors are denser than air, hence it travels along the ground. It should be kept away from combustible material like wood, clothing, oil, and paper. This material may form flammable dust-air mixtures. Potential for a dust explosion may exist. Exposure to humans is mainly through inhalation, dermal contact. It can cause irritation to eye and skin, inhalation can cause cough, shortness of breath and sore throat, and ingestion can cause vomiting and abdominal cramps.

  20. Crystal structure of chlorido-{5,10,15,20-tetra-kis-[2-(2,2-di-methyl-propanamido)-phen-yl]porphyrinato-?(4) N}iron(III).

    PubMed

    Awasabisah, Dennis; Powell, Douglas R; Richter-Addo, George B

    2015-02-01

    The title compound, [Fe(C64H64N8O4)Cl], is a five-coordinate square-pyramidal porphyrin complex with a chloride ion in the axial position, being coordinated from the protected side of the porphyrin; the Fe(III) atom is displaced by 0.474?(5)?Å from the 24-atom mean plane of the porphyrin core towards the chloride. The porphyrin moiety is a 'picket-fence' 5,10,15,20-tetra-kis-[2-(2,2-di-methyl-propanamido)-phen-yl]porph-yrinate (por) group. The Fe-Cl bond length is 2.221?(2)?Å and the Fe-N(por) bond lengths are in the range 2.043?(5)-2.063?(5)?Å. The supra-molecular architecture of the crystal is sustained by C-H?O inter-actions between the pyrrolic and phenyl H atoms of one mol-ecule and the carbonyl O atoms of the 2,2-di-methyl-propanamido groups of adjacent mol-ecules. The methyl groups of three of the four tert-butyl substituents exhibited rotational disorder over two positions. The investigated crystal was twinned by a twofold rotation about the (001) axis with a refined twin ratio of 0.4086?(16). PMID:25878847

  1. Inhibition of cell proliferation and induction of apoptosis by oleanane triterpenoid (CDDO-Me) in pancreatic cancer cells is associated with the suppression of hTERT gene expression and its telomerase activity

    SciTech Connect

    Deeb, Dorrah; Gao, Xiaohua; Liu, Yongbo [Department of Surgery, Henry Ford Health System, Detroit, MI (United States)] [Department of Surgery, Henry Ford Health System, Detroit, MI (United States); Kim, Sahn-Ho [Department of Urology, Henry Ford Health System, Detroit, MI (United States)] [Department of Urology, Henry Ford Health System, Detroit, MI (United States); Pindolia, Kirit R. [Department of Medical Genetics, Henry Ford Health System, Detroit, MI (United States)] [Department of Medical Genetics, Henry Ford Health System, Detroit, MI (United States); Arbab, Ali S. [Department of Radiology, Henry Ford Health System, Detroit, MI (United States)] [Department of Radiology, Henry Ford Health System, Detroit, MI (United States); Gautam, Subhash C., E-mail: sgautam1@hfhs.org [Department of Surgery, Henry Ford Health System, Detroit, MI (United States)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT gene expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT protein expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT telomerase activity. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT regulatory proteins. -- Abstract: Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a multifunctional oleanane synthetic triterpenoid with potent anti-inflammatory and antitumorigenic properties. The mechanisms of the antisurvival and apoptosis-inducing activities of CDDO-Me and related derivatives of oleanolic acid have been defined; however, to date, no study has been carried out on the effect of CDDOs on human telomerase reverse transcriptase (hTERT) gene or telomerase activity. Here we report for the first time that inhibition of cell proliferation and induction of apoptosis by CDDO-Me in pancreatic cancer cell lines is associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT expression and activity. Furthermore, abrogation or overexpression of hTERT protein altered the susceptibility of tumor cells to CDDO-Me. These findings suggest that telomerase (hTERT) is a relevant target of CDDO-Me in pancreatic cancer cells.

  2. MONITORED NATURAL ATTENUATION OF TERTIARY BUTYL ALCOHOL (TBA) IN GROUND WATER AT GASOLINE SPILL SITES

    EPA Science Inventory

    The state agencies that implement the Underground Storage Tank program rely heavily on Monitored Natural Attenuation (MNA) to clean up contaminants such as benzene and methyl tertiary butyl ether (MTBE) at gasoline spill sites. This is possible because the contaminants are biolo...

  3. Carbolithiation of cinnamyl methyl ethers and 2-cinnamyl-2-methyl-1,3-dioxolane: High diastereoselectivity after electrophilic substitution

    Microsoft Academic Search

    Christian Mück-Lichtenfeld; Hubertus Ahlbrecht

    1999-01-01

    The carbolithiation of cinnamyl methyl ether 4 with tert-butyllithium, benzyllithium, and allyllithium is achieved in good yields. Consecutive treatment with electrophiles yields in all three cases a good diastereoselectivity thus confirming earlier results obtained in the reaction of secondary and tertiary cinnamyl amines. The ethylene acetal of 4-phenyl-3-buten-2-one 20 can also be carbolithiated with tert-butyllithium and the products exhibit even

  4. Hydrogen Oxidation Catalysis by a Nickel Diphosphine Complex with Pendant t-Butyl Amines

    SciTech Connect

    Yang, Jenny Y.; Chen, Shentan; Dougherty, William G.; Kassel, W. Scott; Bullock, R. Morris; DuBois, Daniel L.; Raugei, Simone; Rousseau, Roger; Dupuis, Michel; DuBois, M. Rakowski

    2010-01-01

    A bis-diphosphine nickel complex with tert-butyl functionalized pendant amines [Ni(P{sup Cy}{sub 2}N{sup t-Bu}{sub 2}){sub 2}]{sup 2+} has been synthesized. It is a highly active electrocatalyst for the oxidation of hydrogen in the presence of base. The turnover rate of 50 s{sup ?1} under 1.0 atm H{sub 2} at a potential of ?0.77 V vs. the ferrocene couple is 5 times faster than the rate reported heretofore for any other synthetic molecular H{sub 2} oxidation catalyst.

  5. Identification of a fragment-like small molecule ligand for the methyl-lysine binding protein, 53BP1.

    PubMed

    Perfetti, Michael T; Baughman, Brandi M; Dickson, Bradley M; Mu, Yunxiang; Cui, Gaofeng; Mader, Pavel; Dong, Aiping; Norris, Jacqueline L; Rothbart, Scott B; Strahl, Brian D; Brown, Peter J; Janzen, William P; Arrowsmith, Cheryl H; Mer, Georges; McBride, Kevin M; James, Lindsey I; Frye, Stephen V

    2015-04-17

    Improving our understanding of the role of chromatin regulators in the initiation, development, and suppression of cancer and other devastating diseases is critical, as they are integral players in regulating DNA integrity and gene expression. Developing small molecule inhibitors for this target class with cellular activity is a crucial step toward elucidating their specific functions. We specifically targeted the DNA damage response protein, 53BP1, which uses its tandem tudor domain to recognize histone H4 dimethylated on lysine 20 (H4K20me2), a modification related to double-strand DNA breaks. Through a cross-screening approach, we identified UNC2170 (1) as a micromolar ligand of 53BP1, which demonstrates at least 17-fold selectivity for 53BP1 as compared to other methyl-lysine (Kme) binding proteins tested. Structural studies revealed that the tert-butyl amine of UNC2170 anchors the compound in the methyl-lysine (Kme) binding pocket of 53BP1, making it competitive with endogenous Kme substrates. X-ray crystallography also demonstrated that UNC2170 binds at the interface of two tudor domains of a 53BP1 dimer. Importantly, this compound functions as a 53BP1 antagonist in cellular lysates and shows cellular activity by suppressing class switch recombination, a process which requires a functional 53BP1 tudor domain. These results demonstrate that UNC2170 is a functionally active, fragment-like ligand for 53BP1. PMID:25590533

  6. Mechanisms of cytotoxicity of 2- or 2,6-di- tert-butylphenols and 2-methoxyphenols in terms of inhibition rate constant and a theoretical parameter

    Microsoft Academic Search

    Yoshinori Kadoma; Shigeru Ito; Toshiko Atsumi; Seiichiro Fujisawa

    2009-01-01

    To clarify the mechanism of phenol toxicity, the radical-scavenging activity of 2- or 2,6-di-tert-butyl- and 2-methoxy-substituted phenols was investigated by combining two distinct approaches: first, the induction period method for methacrylate polymerization initiated by benzoyl peroxide or 2,2?-azobisisobutyronitrile; and secondly, 1,1?-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test. The homolytic bond dissociation enthalpy (BDE) and ionization potential (IPkoopman) were calculated by the DFT\\/B3LYP

  7. Substituent-Induced Perturbation Symmetries and Distortions of meso-tert-Butylporphyrins.

    PubMed

    Song, Xing-Zhi; Jentzen, Walter; Jaquinod, Laurent; Khoury, Richard G.; Medforth, Craig J.; Jia, Song-Ling; Ma, Jian-Guo; Smith, Kevin M.; Shelnutt, John A.

    1998-05-01

    The out-of-plane and in-plane distortions of a series of nickel(II) meso-substituted porphyrins with 0, 1, 2, or 4 tert-butyl groups [nickel(II) porphine (NiP), nickel(II) mono-tert-butylporphyrin (NiMtBuP), nickel(II) di-tert-butylporphyrin (NiDtBuP), and nickel(II) tetra-tert-butylporphyrin (NiTtBuP)] are investigated using molecular mechanics (MM) calculations, X-ray crystallography, UV-visible absorption spectroscopy, and resonance Raman spectroscopy. MM calculations are used to predict the stable conformations for this series of porphyrins. The out-of-plane distortions are then analyzed in terms of displacements along the normal coordinates of the porphyrin macrocycle using a new normal-coordinate structural decomposition method. As expected, the distortions are found to occur primarily along the lowest-frequency normal coordinate of each symmetry type and the distortions could be adequately simulated using only the lowest-frequency normal coordinates as a basis (the minimal basis). However, the distortions could be simulated significantly more accurately by extending the minimal basis by including the second-lowest-frequency normal coordinate of all symmetries. Using the extended basis is most important for the in-plane distortions. Detailed analysis of the types of distortion revealed that both the out-of-plane and the in-plane distortions depend on the perturbation symmetry of the peripheral substituents. The symmetry primarily depends on the pattern of substitution (number and positions of substituents) and the orientations of substituents. Often the perturbation symmetry can be predicted for a given porphyrin simply from the possible orientations of the substituents. Then, the main type(s) of symmetric deformation occurring for each possible molecular symmetry can be readily predicted from a D(4)(h)() correlation table. The stable conformers predicted by MM for the series of tert-butyl-substituted porphyrins confirm this simple but informative approach. Experimental verification of the calculated contributions of the symmetric deformations is provided by normal-coordinate structural decomposition of the available X-ray crystal structures of NiP, NiMtBuP, and NiDtBuP. The solid-state results are also supported by the resonance Raman and UV-visible absorption spectroscopic characterization of the porphyrins in solutions. The X-ray crystal structure of NiMtBuP is reported here for the first time. PMID:11670364

  8. MLH1 mediates PARP-dependent cell death in response to the methylating agent N-methyl-N-nitrosourea

    Microsoft Academic Search

    J R McDaid; J Loughery; P Dunne; J C Boyer; C S Downes; R A Farber; C P Walsh

    2009-01-01

    Background:Methylating agents such as N-methyl-N-nitrosourea (MNU) can cause cell cycle arrest and death either via caspase-dependent apoptosis or via a poly(ADP-ribose) polymerase (PARP)-dependent form of apoptosis. We wished to investigate the possible role of MLH1 in signalling cell death through PARP.Methods:Fibroblasts are particularly dependent on a PARP-mediated cell death response to methylating agents. We used hTERT-immortalised normal human fibroblasts (WT)

  9. Mechanistic studies of coenzyme B?? model systems 

    E-print Network

    Robinson, John Walter

    1988-01-01

    involved a 2-step synthesis of first, tert-butyl chloromethyl ether, and secondly, alkylation of the ether with dimethyl methyl malonate. The synthesis of tert-butyl chloromethyl ether proved more diffucult than anticipated. After irradiating a soludon... of tert-butyl methyl ether and n-chlorosuccinimide 31 in trichlorofluoromethane with a low pressure lamp for nine hours, a HNMR of the mixture was taken and showed considerable evidence of a reaction taking place. The spectrum revealed starting...

  10. Isolation and characterization of a new Mycobacterium austroafricanum strain, IFP 2015, growing on MTBE

    Microsoft Academic Search

    Nicolas Lopes Ferreira; Helena Maciel; Hugues Mathis; Frédéric Monot; Françoise Fayolle-Guichard; Charles W. Greer

    2006-01-01

    A new Mycobacterium austroafricanum strain, IFP 2015, growing on methyl tert-butyl ether (MTBE) as a sole carbon source was isolated from an MTBE-degrading microcosm inoculated with drain water of an MTBE-supplemented gasoline storage tank. M. austroafricanum IFP 2015 was able to grow on tert-butyl formate, tert-butyl alcohol (TBA) and ?-hydroxyisobutyrate. 2-Methyl-1,2-propanediol was identified as the TBA oxidation product in M.

  11. EFFECT OF BTEX ON THE DEGRADATION OF MTBE AND TBA BY MIXED BACTERIAL CONSORTIUM

    EPA Science Inventory

    Methyl tert -butyl ether (MTBE) contamination in groundwater often coexists with benzene, toluene, ethylbenzene, and xylene (BTEX) near the source of the plume. Tertiary butyl alcohol (TBA) is a prevalent intermediate of MTBE degradation. Therefore, there is a significant p...

  12. Electrochemical Sulfonylation of 4-tert-Butylcatechol

    Microsoft Academic Search

    Davood Nematollahi; Ramazanali Rahchamani; Maryam Malekzadeh

    2003-01-01

    Electrochemical oxidation of 4-tert-butylcatechol (1) has been studied in the presence of benzenesulfinic acids (2a and 2b) as nucleophiles in aqueous solution, using cyclic voltammetry and controlled-potential coulometry. The results indicate that the quinone derived from 4-tert-butylcatechol (1) participates in Michael addition reaction with 2 of form the corresponding arylsulfonylbenzenediols (3a and 3b). The electrochemical synthesis of 3a and 3b

  13. S-15176 and its methylated derivative suppress the CsA-insensitive mitochondrial permeability transition and subsequent cytochrome c release induced by silver ion, and show weak protonophoric activity.

    PubMed

    Kawashima, Satoshi; Yamamoto, Takenori; Horiuchi, Yuka; Fujiwara, Kengo; Gouda, Shunichi; Yoshimura, Yuya; Yamamoto, Atsushi; Inotani, Yuki; Yamashita, Kikuji; Kitamura, Seiichiro; Terada, Hiroshi; Kanematsu, Makoto; Shishido, Kozo; Shinohara, Yasuo

    2011-12-01

    A recent report has described that S-15176 (N-[(3,5-di-tert-butyl-4-hydroxy-1-thiophenyl)]-3-propyl-N'-(2,3,4-trimethoxybenzyl) piperazine), an anti-ischemic agent, inhibits the mitochondrial permeability transition (PT) induced by not only Ca(2+) and inorganic phosphate, but also by tert-butylhydroperoxide or phenylarsine oxide [Morin et al. (Biochem Pharmacol 72:911-918, 2006)]. In the present study, we tested the effects of S-15176 on the PT induced by Ag(+), PT of which is not suppressed by cyclosporin A or oligomycin. S-15176 was effective in suppressing the PT and the subsequent cytochrome c release induced by Ag(+), and hence, it was concluded to be a more universal PT inhibitor than cyclosporin A or oligomycin. In addition to the PT-suppression activity, S-15176 also showed weak protonophoric activity. Thus, we further tested to investigate whether the hydroxyl group of S-15176 was involved in its PT-suppression or weak protonophoric activities. The methylated derivative of S-15176 also showed both PT suppression and weak protonophoric activities; hence, the hydroxyl group of S-15176 was concluded not to be involved in these activities. PMID:21688046

  14. Study on the thermal stability of 2-hexyne, 1-pentyne, ethyl isocyanide, and n -butyl isocyanide as sulfur-free gas odorants

    Microsoft Academic Search

    Yasushi Oka; Toru Yoshida; Takeshi Kondo; Shunsuke Ito; Katsumi Katoh

    2010-01-01

    In Japan, tert-butyl mercaptan (TBM) is mainly employed as an odorant of LPG. However, the sulfur component in TBM gives the adverse effect\\u000a for environment and human body and\\/or has a negative impact on reforming catalyst of fuel cell and other types of cogeneration\\u000a systems. In this way, the development of sulfur-free odorant is expected. This study focuses on the

  15. Synthesis of the optical isomers of 4-[1-(4-tert-butylphenyl)-2-oxo- pyrrolidine-4-yl]methyloxybenzoic acid (S-2) and their biological evaluation as antilipidemic agent.

    PubMed

    Ohno, T; Yano, S; Yamada, H; Shirasaka, T; Yamamoto, A; Kobayashi, K; Ogawa, K

    1999-11-01

    The enantiomers of (+/-)-4-[1-(4-tert-butylphenyl)-2-oxo-pyrrolidine- 4-yl]methyloxybenzoic acid (S-2), a new antilipidemic agent having dual action on the plasma triglyceride (TG) and cholesterol (Cho) lowering effects, were prepared via separation by Chiralcel OJ column chromatography of their methyl ester and also by the same method as the described racemate's synthesis from optically active 1-(4-tert-butylphenyl)-2-oxo-pyrrolidine-4-carboxylic acid respectively. These optically active carboxylic acids were prepared by the resolution of diastereomeric N-[(S)-(-)-[4-methyl-(alpha-methyl)benzyl

  16. Preparation of tert-butyl-capped polyenes containing up to 15 double bonds

    SciTech Connect

    Knoll, K.; Schrock, R.R. (Massachusetts Institute of Technology, Cambridge (USA))

    1989-11-27

    7,8-Bis(trifluoromethyl)tricyclo(4.2.2.0{sup 2.5})deca-3,7,9-triene (TCDT) can be ring-opened in a controlled manner by W(CH-t-Bu)(NAr)(O-t-Bu){sub 2} (Ar = 2,6-C{sub 6}H{sub 3}-i-Pr{sub 2}) to give living oligomers from which the metal can be removed in a Wittig-like reaction with pivaldehyde or 4,4-dimethyl-trans-2-pentenal. Mixtures of odd and even polyenes have been analyzed by reversed-phase HPLC methods, and those having as many as 13 double bonds have been isolated by column chromatography on silica gel under dinitrogen at {minus}40{degree}C and characterized by {sup 1}H and {sup 13}C NMR and UV-vis studies. The 17-ene has been observed by HPLC. Polyenes containing more than 17 double bonds are relatively unstable under the reaction and subsequent isolation conditions; those containing between 11 and 15 double bonds decompose thermally progressively more readily. UV-vis and {sup 13}C and {sup 1}H NMR data have been collected and analyzed in detail for the trans(cis,trans){sub x} isomers for x = 1-5 (up to 11 double bonds) and for the odd and even all-trans forms containing up to nine double bonds.

  17. Di-tert-butyl cyclo­hex-2-ene-1,4-diyl dicarbonate

    PubMed Central

    Ali, Syed Nawazish; Winnik, Mitchell A.; Begum, Sabira; Lough, Alan J.

    2009-01-01

    In the title mol­ecule, C16H26O6, the central cyclo­hexene ring is in a half-chair conformation. The carbonyl groups are in a trans arrangement with respect to each other and the dihedral angle between the mean planes of the carbonate groups is 10.8?(2)°. PMID:21578295

  18. Allylic oxidation of steroidal olefins by vanadyl acetylacetonate and tert-butyl hydroperoxide.

    PubMed

    Grainger, Wendell S; Parish, Edward J

    2015-09-01

    Readily available vanadyl acetylacetonate was found to oxidize the allylic sites of ?(5) steroidal alcohols without protection of hydroxyl groups. Cholesterol, dehydroepiandrosterone, cholesterol benzoate, cholesterol acetate, pregnenolone, and 5-pregnen-3,20-diene were oxidized to 7-keto products using vanadyl acetylacetonate in one pot reactions at room temperature in the presence of oxygen and water. PMID:26091580

  19. 3-Bromo-N-(3,5-di-tert-butyl­phen­yl)propanamide

    PubMed Central

    Abo-Amer, Anwar; Al-Refai, Mahmoud; Puddephatt, Richard J.; Ali, Basem F.

    2014-01-01

    The title compound, C17H26BrNO, exhibits a small twist between the amide residue and the benzene ring [C—N—C—C torsion angle = 29.4?(5)°]. In the crystal, the amido NH group is involved in N—H?O hydrogen bonding, which connects mol­ecules into chains parallel to the c axis. PMID:25161559

  20. Oxidative Processes Induced by tert Butyl Hydroperoxide in Human Red Blood Cells: Chemiluminescence Studies

    Microsoft Academic Search

    A. V. Domanski; E. A. Lapshina; I. B. Zavodnik

    2005-01-01

    The erythrocyte is a good model for investigation of the mechanisms of cell damage induced by oxidizing agents. Oxidative damage to cell components and cellular metabolism results in impaired rheological properties of circulating red blood cells and is involved in the development of some pathologies. The aim of the present study was to elucidate further the oxidative processes induced by

  1. 2-tert-Butyl-6-(cyclo­hexyl­imino­meth­yl)-4-meth­oxy­phenol

    PubMed Central

    Jamjah, Roghayieh; Nekoomanesh, Mehdi; Pourjafar, Tayebeh; Zohuri, Gholam Hossein; Afshartaromi, Faramarz; Notash, Behrouz

    2011-01-01

    The asymmetric unit of the title Schiff base compound, C18H27NO2, contains two independent mol­ecules in which the C=N bond lengths are 1.278?(2) and 1.280?(2)?Å and the cyclo­hexane rings adopt chair conformations. Intra­molecular O—H?N hydrogen bonding between hy­droxy and imine groups and weak C—H?O hydrogen bonds help to stabilize the mol­ecular structure. PMID:21837152

  2. tert-Butyl N-[(S)-3-isopropyl-2-oxo­oxetan-3-yl]carbamate

    PubMed Central

    Siero?, Les?aw; Kudaj, Adam; Olma, Aleksandra; Karolak-Wojciechowska, Janina

    2008-01-01

    The structure of the title compound, C11H19NO4, contains two crystallographically independent mol­ecules in the asymmetric unit. Both adopt the same conformation and they form pseudosymmetric R 2 2(8) dimers via two N—H?O hydrogen bonds. The dimers are linked by weak C—H?O inter­actions and are stacked in columns along the a axis. PMID:21201893

  3. Palladium-catalyzed formylation of aryl halides with tert-butyl isocyanide.

    PubMed

    Jiang, Xiao; Wang, Jin-Mei; Zhang, Ying; Chen, Zhong; Zhu, Yong-Ming; Ji, Shun-Jun

    2014-07-01

    A novel palladium-catalyzed formylation of aryl halides with isocyanide in the presence of Et3SiH has been demonstrated, which provides a strategy toward important aldehydes with moderate to excellent yield. The advantage of this reaction includes milder conditions, convenient operation, lower toxicity, and wide functional group tolerance. PMID:24956352

  4. Crystal structure of tert-butyl-N-phenyl-carbonitrilium tetra-chlorido-aluminate.

    PubMed

    van Dijk, Tom; Zant, Dirk W; Wolf, Robert; Lammertsma, Koop; Slootweg, J Chris

    2014-11-01

    In the title compound, (C11H14N)[AlCl4], the nitrilium (systematic name: 2,2-dimethyl-N-phenyl-propane-nitrilium) ion adopts a slightly distorted linear configuration [C-N C = 178.87?(16) and N C-C = 179.13?(17)°]. In the crystal, while there are no inter-molecular hydrogen bonds, pairs of nitrilium ions are linked through ?-? inter-actions [inter-centroid distance = 3.8091?(13)?Å]. PMID:25484737

  5. Crystal structure of tert-butyl-N-phenyl­carbonitrilium tetra­chlorido­aluminate

    PubMed Central

    van Dijk, Tom; Zant, Dirk W.; Wolf, Robert; Lammertsma, Koop; Slootweg, J. Chris

    2014-01-01

    In the title compound, (C11H14N)[AlCl4], the nitrilium (systematic name: 2,2-dimethyl-N-phenyl­propane­nitrilium) ion adopts a slightly distorted linear configuration [C—N C = 178.87?(16) and N C—C = 179.13?(17)°]. In the crystal, while there are no inter­molecular hydrogen bonds, pairs of nitrilium ions are linked through ?–? inter­actions [inter–centroid distance = 3.8091?(13)?Å]. PMID:25484737

  6. Binding properties and structure-affinity relationships of food antioxidant butylated hydroxyanisole and its metabolites with lysozyme.

    PubMed

    Wu, Di; Yan, Jin; Tang, Peixiao; Li, Shanshan; Xu, Kailin; Li, Hui

    2015-12-01

    Considering the harmful impact of food antioxidants on human bodies, thoroughly exposing their potential effects at the molecular level is important. In this study, the binding interactions of butylated hydroxyanisole (BHA), a phenolic antioxidant, and its different major metabolites tert-butylhydroquinone (TBHQ) and tert-butylbenzoquinone (TBQ) with lysozyme were examined via fluorescence, three-dimensional fluorescence, circular dichroism (CD), and ligand-protein docking studies. The three compounds caused strong quenching of lysozyme fluorescence by a static quenching mechanism but with different quenching efficiencies and different effects on the ?-helix content of the lysozyme. The order of binding affinity of lysozyme for all test compounds is as follows: BHA>TBQ>TBHQ. Thermodynamic parameters indicated that hydrogen bonding and van der Waals forces perform dominant functions in the binding between these compounds and lysozyme. Furthermore, structure-affinity relationships between the model compounds and lysozyme were established on the basis of computational analyses. PMID:26041206

  7. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 false Chlorohydroxyalkyl butyl ether (generic). 721.3438 Section 721...721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance...generically as chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to...

  8. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 false Chlorohydroxyalkyl butyl ether (generic). 721.3438 Section 721...721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance...generically as chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to...

  9. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 false Chlorohydroxyalkyl butyl ether (generic). 721.3438 Section 721...721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance...generically as chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to...

  10. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 false Chlorohydroxyalkyl butyl ether (generic). 721.3438 Section 721...721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance...generically as chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to...

  11. 40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 false Chlorohydroxyalkyl butyl ether (generic). 721.3438 Section 721...721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance...generically as chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to...

  12. Carbon­yl{3,3?-di-tert-butyl-5,5?-dimeth­oxy-2,2?-bis­[(4,4,5,5-tetra­methyl-1,3,2-dioxaphospho­lan-2-yl)­oxy]biphenyl-?2 P,P?}hydrido(triphenyl­phosphane-?P)rhodium(I) diethyl ether tris­olvate

    PubMed Central

    Selent, Detlef; Spannenberg, Anke; Börner, Armin

    2013-01-01

    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]. PMID:23476316

  13. Cancer-associated TERT promoter mutations abrogate telomerase silencing.

    PubMed

    Chiba, Kunitoshi; Johnson, Joshua Z; Vogan, Jacob M; Wagner, Tina; Boyle, John M; Hockemeyer, Dirk

    2015-01-01

    Mutations in the human telomerase reverse transcriptase (TERT) promoter are the most frequent non-coding mutations in cancer, but their molecular mechanism in tumorigenesis has not been established. We used genome editing of human pluripotent stem cells with physiological telomerase expression to elucidate the mechanism by which these mutations contribute to human disease. Surprisingly, telomerase-expressing embryonic stem cells engineered to carry any of the three most frequent TERT promoter mutations showed only a modest increase in TERT transcription with no impact on telomerase activity. However, upon differentiation into somatic cells, which normally silence telomerase, cells with TERT promoter mutations failed to silence TERT expression, resulting in increased telomerase activity and aberrantly long telomeres. Thus, TERT promoter mutations are sufficient to overcome the proliferative barrier imposed by telomere shortening without additional tumor-selected mutations. These data establish that TERT promoter mutations can promote immortalization and tumorigenesis of incipient cancer cells. PMID:26194807

  14. Cuprate-Mediated Synthesis and Biological Evaluation of Cyclopropyl- and tert-Butylfarnesyl Diphosphate Analogs.

    PubMed

    Mu, YongQi; Gibbs, Richard A.; Eubanks, Lisa M.; Poulter, C. Dale

    1996-11-15

    The novel farnesyl diphosphate (FPP) analog 3-cyclopropyl-3-desmethylfarnesyl diphosphate (3-cpFPP, 1) was designed as a potential mechanism-based inhibitor of the FPP-utilizing enzyme protein-farnesyl transferase (PFTase). The key step in the synthesis of 1 involved the stereoselective coupling of vinyl triflate 8 with a lower order cyclopropyl cyanocuprate to afford the desired cyclopropyl ester 13. The sterically encumbered analog 3-desmethyl-3-tert-butylfarnesyl diphosphate (3-tbFPP, 7) was synthesized via a similar route. The use of the more reactive higher order tert-butyl cyanocuprate led to lower yields of ester 11, the key intermediate in the synthesis of 7. Biological evaluation of 3-cpFPP demonstrates that it is not a time-dependent inhibitor of recombinant yeast PFTase. Instead, 3-cpFPP is an alternative substrate for this enzyme that exhibits a K(m) comparable to FPP and a k(cat) only 5-fold lower than the natural substrate. In contrast, 3-tbFPP is an exceptionally poor substrate for yeast PFTase and acts as an inhibitor of this enzyme. PMID:11667783

  15. Anaerobic biotransformation of fuel oxygenates under sulfate-reducing conditions

    Microsoft Academic Search

    Piyapawn Somsamak; Robert M Cowan; Max M Häggblom

    2001-01-01

    The anaerobic biotransformation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and methyl tert-amyl ether (TAME) was evaluated under different anoxic electron-accepting conditions. Enrichments were established with a polluted estuarine sediment inoculum under conditions promoting denitrification, sulfate reduction, Fe(III) reduction, or methanogenesis. Complete loss of MTBE and TAME was observed under sulfate-reducing conditions, concomitant with the reduction of sulfate.

  16. Aerobic biodegradation of an oxygenates mixture: ETBE, MTBE and TAME in an upflow fixed-bed reactor

    Microsoft Academic Search

    M Kharoune; A Pauss; J. M Lebeault

    2001-01-01

    Aerobic degradation of ethyl tert-butyl ether (ETBE), Methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME), as tertiary-substrates, was studied in a continuous upflow fixed-bed reactor (UFBR) using an external oxygenator and sintered glass rings as biomass carriers. The UFBR has been shown to be an effective system for the simultaneous and continuous long-term degradation of the three-oxygenates mixture as

  17. The Rotational Spectrum of Tertiary-Butyl Alcohol

    NASA Astrophysics Data System (ADS)

    Cohen, E. A.; Drouin, B. J.; Valenzuela, E. A.; Woods, R. C.; Caminati, W.; Maris, A.; Melandri, S.

    2009-06-01

    Tertiary-butyl alcohol is a nearly spherical rotor for which the internal rotation axis of the t-butyl group is close to the c molecular axis in the ac plane. Methyl group torsional spittings are not observed in the ground state. Its 8 to 40 GHz rotational spectrum was reported at this meeting by Valenzuela and Woods in 1974 and in more detail in 1975. The parameters derived at that time from a fit to the E states with J,K? 20 have provided the basis for extending the measurements to > 500 GHz. The combined data set extends to J,K > 50 and is fit with the program SPFIT using a common set of parameters for both the A and E states. The general features of the spectrum and the fitting procedure will be described. The resulting molecular constants and their interpretation will be discussed. E.A. Valenzuela, and R. C. Woods, Abstract MF6, International Symposium on Molecular Spectroscopy, Columbus, OH, 1974 E.A. Valenzuela, and R. C. Woods, Abstract RG15, International Symposium on Molecular Spectroscopy, Columbus, OH, 1975 E.A. Valenzuela, Ph.D. Thesis, University of Wisconsin-Madison, 1975. H. M. Pickett, J. Mol. Spectrosc. 148 (1991) 271-377.

  18. Use of butyl-2-cyanoacrylate in rabbit auricular cartilage.

    PubMed

    Fung, R Q; Ronis, M L; Mohr, R M

    1985-07-01

    Since the nonsuture repair of blood vessels with methyl-2-cyanoacrylate was described in 1960, the advantages of a tissue adhesive over conventional sutures became evident. A survey of 115 otolaryngology programs showed that cyanoacrylates, mainly butyl-2-cyanoacrylate (B2C), are used more extensively than indicated in the literature. Cartilage grafts are commonly used in facial plastic procedures. In a study comparing B2C with conventional suture techniques in securing rabbit auricular cartilage autografts, sutures were used in the left control ear and B2C was used in the right experimental ear. Rabbits sacrificed at two weeks to 12 months showed graft viability in all samples and no statistically significant histologic difference between the grafts secured by either method. PMID:3893400

  19. The effects of PBN (phenyl-butyl-nitrone) on GLT-1 levels and on the extracellular levels of amino acids and energy metabolites in a model of iron-induced posttraumatic epilepsy

    Microsoft Academic Search

    Carolina Samuelsson; Eva Kumlien; Åse Elfving; Dan Lindholm; Elisabeth Ronne-Engström

    2003-01-01

    This study investigates astrocytic glutamate uptake in the iron-induced animal model of posttraumatic epilepsy. Since formation of free radicals may be involved in epileptogenesis after brain trauma and hemorrhage the effects of the nitrone radical scavenger ?-phenyl-tert-N-butyl nitrone (PBN) were also studied. Animals received an intracortical iron injection, or were sham-operated. They were given PBN intraperitoneally or saline as control.

  20. Cure kinetics, morphological and dynamic mechanical analysis of diglycidyl ether of bisphenol-A epoxy resin modified with hydroxyl terminated poly(ether ether ketone) containing pendent tertiary butyl groups

    Microsoft Academic Search

    Bejoy Francis; V. Lakshmana Rao; Geert Vanden Poel; Fabrice Posada; Gabriel Groeninckx; R. Ramaswamy; Sabu Thomas

    2006-01-01

    Hydroxyl terminated poly(ether ether ketone) based on tert-butyl hydroquinone (PEEKTOH) was used to modify a diglycidyl ether of bisphenol-A epoxy resin. A diamine, 4,4?-diaminodiphenylsulfone was used as the curing agent. Isothermal differential scanning calorimetric measurements of the blends were carried out at 180, 165 and 150°C. The extent of reaction was found to decrease with the addition of PEEKTOH. The

  1. Metsulfuron-methyl-based herbicidal ionic liquids.

    PubMed

    Pernak, Juliusz; Niemczak, Micha?; Shamshina, Julia L; Gurau, Gabriela; G?owacki, Grzegorz; Praczyk, Tadeusz; Marcinkowska, Katarzyna; Rogers, Robin D

    2015-04-01

    Ten sulfonylurea-based herbicidal ionic liquids (HILs) were prepared by combining the metsulfuron-methyl anion with various cation types including quaternary ammonium ([bis(2-hydroxyethyl)methyloleylammonium](+), [2-hydroxyethyltrimethylammonium](+)), pyridinium ([1-dodecylpyridinium](+)), piperidinium ([1-methyl-1-propylpiperidinium](+)), imidazolium ([1-allyl-3-methylimidazolium](+), [1-butyl-3-methylimidazolium](+)), pyrrolidinium ([1-butyl-1-methylpyrrolidinium](+)), morpholinium ([4-decyl-4-methylmorpholinium](+)), and phosphonium ([trihexyltetradecylphosphonium](+) and [tetrabutylphosphonium](+)). Their herbicidal efficacy was studied in both greenhouse tests and field trials. Preliminary results for the greenhouse tests showed at least twice the activity for all HILs when compared to the activity of commercial Galmet 20 SG, with HILs with phosphonium cations being the most effective. The results of two-year field studies showed significantly less enhancement of activity than observed in the greenhouse; nonetheless, it was found that the herbicidal efficacy was higher than that of the commercial analog, and efficacy varied depending on the plant species. PMID:25734891

  2. Methylation matters

    PubMed Central

    Costello, J.; Plass, C.

    2001-01-01

    DNA methylation is not just for basic scientists any more. There is a growing awareness in the medical field that having the correct pattern of genomic methylation is essential for healthy cells and organs. If methylation patterns are not properly established or maintained, disorders as diverse as mental retardation, immune deficiency, and sporadic or inherited cancers may follow. Through inappropriate silencing of growth regulating genes and simultaneous destabilisation of whole chromosomes, methylation defects help create a chaotic state from which cancer cells evolve. Methylation defects are present in cells before the onset of obvious malignancy and therefore cannot be explained simply as a consequence of a deregulated cancer cell. Researchers are now able to detect with exquisite sensitivity the cells harbouring methylation defects, sometimes months or years before the time when cancer is clinically detectable. Furthermore, aberrant methylation of specific genes has been directly linked with the tumour response to chemotherapy and patient survival. Advances in our ability to observe the methylation status of the entire cancer cell genome have led us to the unmistakable conclusion that methylation abnormalities are far more prevalent than expected. This methylomics approach permits the integration of an ever growing repertoire of methylation defects with the genetic alterations catalogued from tumours over the past two decades. Here we discuss the current knowledge of DNA methylation in normal cells and disease states, and how this relates directly to our current understanding of the mechanisms by which tumours arise.???Keywords: methylation; cancer PMID:11333864

  3. Role of back diffusion and biodegradation reactions in sustaining an MTBE\\/TBA plume in alluvial media

    Microsoft Academic Search

    Ehsan Rasa; Steven W. Chapman; Barbara A. Bekins; Graham E. Fogg; Kate M. Scow; Douglas M. Mackay

    2011-01-01

    A methyl tert-butyl ether (MTBE) \\/ tert-butyl alcohol (TBA) plume originating from a gasoline spill in late 1994 at Vandenberg Air Force Base (VAFB) persisted for over 15years within 200 feet of the original spill source. The plume persisted until 2010 despite excavation of the tanks and piping within months after the spill and excavations of additional contaminated sediments from

  4. STABLE ISOTOPE ANALYSIS OF MTBE TO EVALUATE THE SOURCE OF TBA IN GROUND WATER

    EPA Science Inventory

    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 those of the conventional fuel oxygenate methyl tert-butyl ether (MTBE). In the year 2002, th...

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

    EPA Science Inventory

    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...

  6. Arco gets ETBE boost from excise tax break

    SciTech Connect

    Lucas, A.

    1994-10-12

    Arco Chemical of Newtown Square, PA, has been extended an excise tax exemption for using ethyl tert-butyl ether (ETBE) in gasoline blends. An exemption is already in force for ethanol. The tax break may still not make ETBE competitive with methanol-based methyl tert-butyl ether (MTBE).

  7. The chicken telomerase reverse transcriptase (chTERT): molecular and cytogenetic characterization with a comparative analysis

    E-print Network

    Delany, Mary E.

    (hTERT). A distinctive feature of chTERT, as compared to human and other vertebrate TERTs to those found associated with hTERT (E-box, Ik1, MAZ, Sp1 sites), whereas several c-Myb sites were found associated with chTERT only and c-Ets-2 and WT1 were associated with hTERT only. Results presented here

  8. Synthetic approaches to the activation of substituted 2-methyl pyridines 

    E-print Network

    Cancanon, Fernadina de la Caridad

    1993-01-01

    route that was investigated to synthesize the his-picolinic acid (6) was based on the retro-synthesis outlined in Scheme 1: O N N COSH H 2 (6) N N CHs H '2 (15) HzN N CHs HO++~OH (13) (14) Scheme 1 Thus, in the first step of the synthesis... 2) (22), ZnCla, No Reaction 0 Bu'Ph SiO N N H 2 (23) Scheme 4 After protecting the alcohol (19) with tert-butyl diphenylsilyl chloride'6, the resulting protected alcohol (22) was added to 3, 3-dimethyl glutaroyl dichloride to form the cyclic...

  9. Longitudinal assessment of DNA methylation changes during HPVE6E7-induced immortalization of primary keratinocytes.

    PubMed

    Schütze, Denise M; Kooter, Jan M; Wilting, Saskia M; Meijer, Chris J L M; Quint, Wim; Snijders, Peter J F; Steenbergen, Renske D M

    2015-01-01

    High-risk human papillomavirus (hrHPV)-induced immortalization and malignant transformation are accompanied by DNA methylation of host genes. To determine when methylation is established during cell immortalization and whether it is hrHPV-type dependent, DNA methylation was studied in a large panel of HPVE6E7-immortalized keratinocyte cell lines. These cell lines displayed different growth behaviors, i.e., continuous growth versus crisis period prior to immortalization, reflecting differential immortalization capacities of the 7 HPV-types (16/18/31/33/45/66/70) studied. In this study, cells were monitored for hypermethylation of 14 host genes (APC, CADM1, CYGB, FAM19A4, hTERT, mir124-1, mir124-2, mir124-3, MAL, PHACTR3, PRDM14, RASSF1A, ROBO3, and SFRP2) at 4 different stages during immortalization. A significant increase in overall methylation levels was seen with progression through each stage of immortalization. At stage 1 (pre-immortalization), a significant increase in methylation of hTERT, mir124-2, and PRDM14 was already apparent, which continued over time. Methylation of ROBO3 was significantly increased at stage 2 (early immortal), followed by CYGB (stage 3) and FAM19A4, MAL, PHACTR3, and SFRP2 (stage 4). Methylation patterns were mostly growth behavior independent. Yet, hTERT methylation levels were significantly increased in cells that just escaped from crisis. Bisulfite sequencing of hTERT confirmed increased methylation in immortal cells compared to controls, with the transcription core and known repressor sites remaining largely unmethylated. In conclusion, HPV-induced immortalization is associated with a sequential and progressive increase in promoter methylation of a subset of genes, which is mostly independent of the viral immortalization capacity. PMID:25580631

  10. The DNA methylation inhibitor induces telomere dysfunction and apoptosis of leukemia cells that is attenuated by telomerase over-expression

    PubMed Central

    de Jonge, Nick; Björkholm, Magnus; Xu, Dawei

    2015-01-01

    DNA methyltransferase inhibitors (DNMTIs) such as 5-azacytidine (5-AZA) have been used for treatment of acute myeloid leukemia (AML) and other malignancies. Although inhibiting global/gene-specific DNA methylation is widely accepted as a key mechanism behind DNMTI anti-tumor activity, other mechanisms are likely involved in DNMTI's action. Because telomerase reverse transcriptase (TERT) plays key roles in cancer through telomere elongation and telomere lengthening-independent activities, and TERT has been shown to confer chemo- or radio-resistance to cancer cells, we determine whether DNMTIs affect telomere function and whether TERT/telomerase interferes with their anti-cancer efficacy. We showed that 5-AZA induced DNA damage and telomere dysfunction in AML cell lines by demonstrating the presence of 53-BP1 foci and the co-localization of 53-BP1 foci with telomere signals, respectively. Telomere dysfunction was coupled with diminished TERT expression, shorter telomere and apoptosis in 5-AZA-treated cells. However, 5-AZA treatment did not lead to changes in the methylation status of subtelomere regions. Down-regulation of TERT expression similarly occurred in primary leukemic cells derived from AML patients exposed to 5-AZA. TERT over-expression significantly attenuated 5-AZA-mediated DNA damage, telomere dysfunction and apoptosis of AML cells. Collectively, 5-AZA mediates the down-regulation of TERT expression, and induces telomere dysfunction, which consequently exerts an anti-tumor activity. PMID:25682873

  11. Methylated Host Cell Gene Promoters and Human Papillomavirus Type 16 and 18 Predicting Cervical Lesions and Cancer

    PubMed Central

    Milutin Gašperov, Nina; Sabol, Ivan; Planini?, Pavao; Grubiši?, Goran; Fistoni?, Ivan; ?oruši?, Ante; Grce, Magdalena

    2015-01-01

    Change in the host and/or human papillomavirus (HPV) DNA methylation profile is probably one of the main factors responsible for the malignant progression of cervical lesions to cancer. To investigate those changes we studied 173 cervical samples with different grades of cervical lesion, from normal to cervical cancer. The methylation status of nine cellular gene promoters, CCNA1, CDH1, C13ORF18, DAPK1, HIC1, RAR?2, hTERT1, hTERT2 and TWIST1, was investigated by Methylation Specific Polymerase Chain Reaction (MSP). The methylation of HPV18 L1-gene was also investigated by MSP, while the methylated cytosines within four regions, L1, 5’LCR, enhancer, and promoter of the HPV16 genome covering 19 CpG sites were evaluated by bisulfite sequencing. Statistically significant methylation biomarkers distinguishing between cervical precursor lesions from normal cervix were primarily C13ORF18 and secondly CCNA1, and those distinguishing cervical cancer from normal or cervical precursor lesions were CCNA1, C13ORF18, hTERT1, hTERT2 and TWIST1. In addition, the methylation analysis of individual CpG sites of the HPV16 genome in different sample groups, notably the 7455 and 7694 sites, proved to be more important than the overall methylation frequency. The majority of HPV18 positive samples contained both methylated and unmethylated L1 gene, and samples with L1-gene methylated forms alone had better prognosis when correlated with the host cell gene promoters’ methylation profiles. In conclusion, both cellular and viral methylation biomarkers should be used for monitoring cervical lesion progression to prevent invasive cervical cancer. PMID:26057381

  12. Calorimetric investigations of hydrogen bonding in binary mixtures containing pyridine and its methyl-substituted derivatives. II. The dilute solutions of methanol and 2-methyl-2-propanol

    Microsoft Academic Search

    Wojciech Marczak; Andreas Heintz; Monika Bucek

    2004-01-01

    Enthalpies of solution of methanol and 2-methyl-2-propanol (tert-butanol) in pyridine and its methyl derivatives were investigated in the range of mole fractions of alcohol x?0.02 at temperature 298.15 K by a titration calorimeter. Dissolution of methanol is an exothermic process, with heat effects very close to those for water reported in part I of this study. The negative enthalpy of

  13. Accelerated aging of EPDM and butyl elastomers

    SciTech Connect

    Wilson, M.H.

    1996-06-01

    This study was composed of three parts: a post cure study to optimize final properties of an ethylene-propylene-diene (EPDM) formulation, an accelerated aging study to compare the stress relaxation behavior of a butyl and an EPDM elastomer under compression, and a cursory evaluation of a new 70 Shore A EPDM. The optimum postcure for the EPDM was found to be 2 to 4 hours at 182{degrees}C in a vacuum. The EPDM was also shown to have superior aging characteristics compared to the butyl and is recommended for use instead of the butyl material. The physical properties for new 70 Shore A EPDM are satisfactory, and the stress relaxation behavior was only slightly inferior to the other EPDM.

  14. 40 CFR 180.232 - Butylate; tolerances for residues.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Tolerances § 180.232 Butylate; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide butylate, including its metabolites and degradates, in or on the commodities in the table in this paragraph....

  15. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

  16. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...HEALTH AND HUMAN SERVICES (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

  17. 21 CFR 172.270 - Sulfated butyl oleate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

  18. Tricarbonyltechnetium(I) and tricarbonylrhenium(I) complexed with N-methyl-2-pyridinecarboxyamide as potential radiopharmaceuticals: a computational study

    Microsoft Academic Search

    L. Fuks; E. Gniazdowska; N. Sadlej-Sosnowska

    2010-01-01

    The electronic and thermodynamic properties of the ‘2 + 1’ tricarbonyltechnetium(I) and -rhenium(I) mixed ligand complexes\\u000a with N-methylpyridine-2-carboxyamide (MPCA) as a bidentate ligand and chloride, water, or tert-butyl-3-isocyanopropanoate (BCP), were investigated within the framework of Density Functional Theory. The atomic charges\\u000a of all complexes, polarization of the CO groups, as well as the effect of transfer of ?-electron density between the ligands

  19. Methyl Iodide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl iodide (MeI, iodomethane, CH3I) was reported as a potential alternative to the stratospheric ozone-depleting fumigant methyl bromide (MeBr) in the mid-1990s (Sims et al., 1995; Ohr et al., 1996). It has since received significant research attention to determine its environmental fate and tran...

  20. Synthesis of methyl glycosides of some alpha-isomalto oligosaccharides specifically deoxygenated at position C-2.

    PubMed

    Petráková, E; Glaudemans, C P

    1995-03-01

    Methyl alpha-isomaltoside and methyl alpha-isomaltotrioside analogues specifically deoxygenated at position C-2 of various glucopyranosyl units were synthesized by condensation of either 6-O-acetyl-3-O-benzoyl-4-O-benzyl-1-O-tert-butyldimethylsilyl-2-deoxy- beta-D-arabino-hexopyranose (trimethylsilyl triflate mediated) or 6-O-acetyl-2,3,4-tri-O-benzyl-alpha-D-glucopyranosyl chloride (mediated by silver carbonate and silver triflate) with suitably blocked derivatives of methyl alpha-D-glucopyranoside, its 2-deoxy analogue, or methyl 2'-deoxy-alpha-isomaltoside. PMID:7736465