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Sample records for methyl tert butyl

  1. Methyl tert-butyl ether (MTBE)

    Integrated Risk Information System (IRIS)

    Methyl tert - butyl ether ( MTBE ) ; CASRN 1634 - 04 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments f

  2. Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria.

    PubMed Central

    Steffan, R J; McClay, K; Vainberg, S; Condee, C W; Zhang, D

    1997-01-01

    Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in < 30 h. The initial oxidation of MTBE and ETBE resulted in the production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature. PMID:9361407

  3. 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, ...

  4. Roles of tert-butyl formate, tert-butyl alcohol and acetone in the regulation of methyl tert-butyl ether degradation by Mycobacterium austroafricanum IFP 2012.

    PubMed

    François, A; Garnier, L; Mathis, H; Fayolle, F; Monot, F

    2003-08-01

    Mycobacterium austroafricanum IFP 2012 is a Gram-positive strain able to grow on methyl tert-butyl ether (MTBE) as a sole carbon and energy source. The effect of two downstream metabolites of MTBE, tert-butyl formate (TBF) and tert-butyl alcohol (TBA) on MTBE degradation was investigated using resting cells. The addition of low concentrations of TBF decreased the MTBE degradation rate by about 30%. In contrast, the addition of TBA did not have a significant effect on MTBE degradation rate, even at high concentrations; and it was also shown that TBA degradation occurred only once MTBE was exhausted. At neutral pH, TBF hydrolysis involved mainly an esterase-type activity regulated by the presence of TBA. The TBF degradation rate was about four times lower than the MTBE degradation rate. Furthermore, acetone was identified as an intermediate during TBA degradation. An acetone mono-oxygenase activity, inhibited by methimazole but not by acetylene, was suggested. It was different from the MTBE/TBA mono-oxygenase and, thus, acetone did not appear to compete with MTBE and TBA for the same enzyme. These new results show that the metabolic regulation of the early steps of MTBE degradation by M. austroafricanum IFP 2012 is complex, involving inhibition and competition phenomena. PMID:12883872

  5. 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). ...

  6. 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

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

    EPA Science Inventory

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

  8. 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-...

  9. ATTENUATION OF METHYL TERT-BUTYL ETHER IN WATER USING SUNLIGHT AND A PHOTOCATALYST

    EPA Science Inventory

    The use of methyl tert-butyl ether (MTBE) as a gasoline additive has resulted in increasing pollution of ground water. Most of the conventional treatment technologies are inefficient or costly when the initial concentration of MTBE is low (<200 ug/L). In order to find an eco-frie...

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. ATTENUATION OF METHYL TERT-BUTYL ETHER IN WATER USING SUNLIGHT AND A PHOTOCATALYST: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-1535 Sahle-Demessie*, E., Enriquez*, J., and Gupta, G. Attenuation of Methyl tert-Butyl Ether in Water using Sunlight and a Photocatalyst. Water Environment Research (Virginia: Water Environment Federation) 74 (2):122-130 (2002). EPA/600/J-02/236. 07/19/2001 The use o...

  15. STRUCTURES AND BINDING ENERGIES OF METHYL TERT-BUTYL ETHER-WATER COMPLEXES

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) is a well-known environmental contaminant owing to its high solubility in water. Since the early 1990s, MTBE has been added to gasoline to improve air quality in some metropolitan areas of the United States. Improved air quality was, however, achiev...

  16. Biotransformation of methyl tert-butyl ether by human cytochrome P450 2A6.

    PubMed

    Shamsipur, Mojtaba; Miran Beigi, Ali Akbar; Teymouri, Mohammad; Poursaberi, Tahereh; Mostafavi, S Mojtaba; Soleimani, Parviz; Chitsazian, Fereshteh; Tash, Shahram Abolhassan

    2012-04-01

    Methyl tert-butyl ether (MTBE) is widely used as gasoline oxygenate and octane number enhancer 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 are of major public concern. However, information on the metabolism of MTBE in human tissues is scarce. The present study demonstrates that human cytochrome P450 2A6 is able to metabolize MTBE to tert-butyl alcohol (TBA), a major circulating metabolite and marker for exposure to MTBE. As CYP2A6 is known to be constitutively expressed in human livers, we infer that it may play a significant role in metabolism of gasoline ethers in liver tissue. PMID:21915685

  17. The sonolytic destruction of methyl tert-butyl ether present in contaminated groundwater.

    PubMed

    Hung, Hui-Ming; Kang, Joon-Wun; Hoffmann, Michael R

    2002-01-01

    Ultrasonic irradiation in the presence of ozone was used to efficiently eliminate methyl tert-butyl ether (MTBE) from groundwater. The sonolytic degradation of MTBE was investigated in three different reactor configurations and frequencies: vibrating-plate reactor (VPR, 358 kHz), near-field acoustical processor (NAP 20 and 16 kHz), and radial-tube resonator (RTR. 20 kHz). The sonochemical reactors can be ordered in terms of their efficiency with respect to the degradation of MTBE in the following way: VPR > RTR > NAP. The higher elimination rates of MTBE in groundwater by combined ultrasound-ozone systems are attributed to the effective conversion of ozone to the OH radical, even in the presence of high alkalinity. Carbonate radicals, which were formed from the oxidation of bicarbonate by hydroxyl radicals, are shown to react with MTBE via a hydrogen-atom abstraction pathway. Methyl-tert-butyl ether was also rapidly eliminated from the groundwater underlying a major intemational airport by direct chemical oxidation with a mixture of hydrogen peroxide and ozone. PMID:12540095

  18. Molecular structures of tert-butyl alcohol and tert-butyl methyl ether as studied by gas electron diffraction combined with vibrational spectroscopy

    NASA Astrophysics Data System (ADS)

    Suwa, Atsuhiko; Ohta, Hiroshi; Konaka, Shigehiro

    1988-02-01

    The molecular of tert-butyl alcohol (TBA) and tert-butyl methyl ether (TBME) have been determined by gas electron diffraction. Vibrational spectra have been measured for TBME. Normal coordinate analyses have been performed to obtain harmonic force fields and to calculate mean amplitudes and shrinkage corrections. Principal bond lengths ( rg) and angles ( rα are: r(OH) = 1.016(14) Å, r(CO) = 1.446(4) Å, r(CC) - 1.529(2) Å, ∠COH = 108(3)° and ∠CCC = 110.9(2)° for TBA r(C 2O) = 1.448(4) Å, r(CC) = 1.532(2) Å, ∠COC = 118.9(14)° and ∠CCC = 111.1(2)° for TBME. The results have been compared with values from molecular mechanics and SCF MO calculations. The observed geometry for TBA is consistent with the rotational constant reported by Valenzuela. The rg(CO) value of TBA is about 0.02 Å larger than that of methanol. The values of rg(C 2O) and ∠COC of TBME are about 0.03 Å and 7° larger than the corresponding values of dimethyl ether and ethyl methyl ether.

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

    PubMed

    Li, Shanshan; Wang, Shan; Yan, Wei

    2016-01-01

    Co-metabolic bioremediation is supposed to be an impressive and promising approach in the elimination technology of methyl tert-butyl ether (MTBE), which was found to be a common pollutant worldwide in the ground or underground water in recent years. In this paper, bacterial strain DZ13 (which can co-metabolically degrade MTBE) was isolated and named as Pseudomonas sp. DZ13 based on the result of 16S rRNA gene sequencing analysis. Strain DZ13 could grow on n-alkanes (C₅-C₈), accompanied with the co-metabolic degradation of MTBE. Diverse n-alkanes with different carbon number showed a significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA). When Pseudomonas sp. DZ13 co-metabolically degraded MTBE with n-pentane as the growth substrate, a higher MTBE-degrading rate (Vmax = 38.1 nmol/min/mgprotein, Ks = 6.8 mmol/L) and lower TBA-accumulation was observed. In the continuous degradation experiment, the removal efficiency of MTBE by Pseudomonas sp. Strain DZ13 did not show an obvious decrease after five times of continuous addition. PMID:27608032

  20. 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...

  1. Draft Genome Sequence of Paenibacillus etheri sp. nov. SH7T, a Methyl Tert-Butyl Ether Degrader.

    PubMed

    Purswani, Jessica; Guisado, Isabel M; Gonzalez-Lopez, Jesus; Pozo, Clementina

    2016-01-01

    We report here the draft genome sequence of Paenibacillus etheri sp. nov. SH7(T) (= CECT 8558(T) = DSM 29760(T)), isolated from a hydrocarbon-contaminated soil pilot plant in Granada, Spain. The bacterium was isolated and sequenced due to its methyl tert-butyl ether (MTBE)-degrading properties. PMID:26893420

  2. WATER QUALITY AT FIVE MARINAS IN LAKE TEXOMA AS RELATED TO METHYL TERT-BUTYL ETHER (MTBE)

    EPA Science Inventory

    Occurrence of methyl tert-butyl ether (MTBE) in five marinas was monitored between June 1999 and November 2000 in Lake Texoma located on the border of Oklahoma and Texas. MTBE is a commonly used gasoline additive and a suspected carcinogen. Lake water was collected at locations i...

  3. 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...

  4. 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...

  5. 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...

  6. 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...

  7. Draft Genome Sequence of Paenibacillus etheri sp. nov. SH7T, a Methyl Tert-Butyl Ether Degrader

    PubMed Central

    Guisado, Isabel M.; Gonzalez-Lopez, Jesus; Pozo, Clementina

    2016-01-01

    We report here the draft genome sequence of Paenibacillus etheri sp. nov. SH7T (= CECT 8558T = DSM 29760T), isolated from a hydrocarbon-contaminated soil pilot plant in Granada, Spain. The bacterium was isolated and sequenced due to its methyl tert-butyl ether (MTBE)-degrading properties. PMID:26893420

  8. 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

  9. Lipid extraction by methyl-tert-butyl ether for high-throughput lipidomics*s⃞

    PubMed Central

    Matyash, Vitali; Liebisch, Gerhard; Kurzchalia, Teymuras V.; Shevchenko, Andrej; Schwudke, Dominik

    2008-01-01

    Accurate profiling of lipidomes relies upon the quantitative and unbiased recovery of lipid species from analyzed cells, fluids, or tissues and is usually achieved by two-phase extraction with chloroform. We demonstrated that methyl-tert-butyl ether (MTBE) extraction allows faster and cleaner lipid recovery and is well suited for automated shotgun profiling. Because of MTBE's low density, lipid-containing organic phase forms the upper layer during phase separation, which simplifies its collection and minimizes dripping losses. Nonextractable matrix forms a dense pellet at the bottom of the extraction tube and is easily removed by centrifugation. Rigorous testing demonstrated that the MTBE protocol delivers similar or better recoveries of species of most all major lipid classes compared with the “gold-standard” Folch or Bligh and Dyer recipes. PMID:18281723

  10. The mechanism of catalytic methylation of 2-phenylpyridine using di-tert-butyl peroxide.

    PubMed

    Sharma, Akhilesh K; Roy, Dipankar; Sunoj, Raghavan B

    2014-07-14

    The mechanism of palladium chloride-catalyzed direct methylation of arenes with peroxides is elucidated by using the energetics computed at the M06 density functional theory. The introduction of a methyl group by tert-butyl peroxides at the ortho-position of a prototypical 2-phenyl pyridine, a commonly used substrate in directed C-H functionalization reactions, is examined in detail by identifying the key intermediates and transition states involved in the reaction sequence. Different possibilities that differ in terms of the site of catalyst coordination with the substrate and the ensuing mechanism are presented. The important mechanistic events involved are (a) an oxidative or a homolytic cleavage of the peroxide O-O bond, (b) C-H bond activation, (c) C-C bond activation, and (d) reductive elimination involving methyl transfer to the aromatic ring. We have examined both radical and non-radical pathways. In the non-radical pathway, the lowest energy pathway involves C-H bond activation prior to the coordination of the peroxide to palladium, which is subsequently followed by the O-O bond cleavage of the peroxide and the C-C bond activation. Reductive elimination in the resulting intermediate leads to the vital C-C bond formation between methyl and aryl carbon atoms. In the non-radical pathway, the C-C bond activation is higher in energy and has been identified as the rate-limiting step of this reaction. In the radical pathway, however, the activation barrier for the C-C bond cleavage is lower than for the peroxide O-O bond cleavage. A combination of a radical pathway up to the formation of a palladium methyl intermediate and a subsequent non-radical pathway has been identified as the most favored pathway for the title reaction. The predicted mechanism is in good agreement with the experimental observations on PdCl2 catalyzed methylation of 2-phenyl pyridine using tert-butyl peroxide. PMID:24875675

  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. Biodegradation of methyl tert-butyl ether and other fuel oxygenates by a new strain, Mycobacterium austroafricanum IFP 2012.

    PubMed

    François, Alan; Mathis, Hugues; Godefroy, Davy; Piveteau, Pascal; Fayolle, Françoise; Monot, Frédéric

    2002-06-01

    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 identified 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 the MTBE catabolism pathway, were detected during growth on MTBE. A positive effect of Co2+ during growth of M. austroafricanum IFP 2012 on HIBA was demonstrated. The specific rate of MTBE degradation was 0.6 mmol/h/g (dry weight) of cells, and the biomass yield on MTBE was 0.44 g (dry weight) per g of MTBE. MTBE, TBA, and HIBA degradation activities were induced by MTBE and TBA, and TBA was a good inducer. Involvement of at least one monooxygenase during degradation of MTBE and TBA was shown by (i) the requirement for oxygen, (ii) the production of propylene epoxide from propylene by MTBE- or TBA- grown cells, and (iii) the inhibition of MTBE or TBA degradation and of propylene epoxide production by acetylene. No cytochrome P-450 was detected in MTBE- or TBA-grown cells. Similar protein profiles were obtained after sodium dodecyl sulfate-polyacrylamide gel electrophoresis of crude extracts from MTBE- and TBA-grown cells. Among the polypeptides induced by these substrates, two polypeptides (66 and 27 kDa) exhibited strong similarities with known oxidoreductases. PMID:12039730

  13. 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 DH5α, 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

  14. Biodegradation of Methyl tert-Butyl Ether by a Bacterial Pure Culture

    PubMed Central

    Hanson, Jessica R.; Ackerman, Corinne E.; Scow, Kate M.

    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 × 106 cells ml−1 were 0.07, 1.17, and 3.56 μg ml−1 h−1 for initial concentrations of 5, 50, and 500 μg MTBE ml−1, respectively. When incubated with 20 μg of uniformly labeled [14C]MTBE ml−1, strain PM1 converted 46% to 14CO2 and 19% to 14C-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 mg of cells mg MTBE−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 μg of MTBE ml−1 added to the core material. The rate of MTBE removal increased with additional inputs of 20 μg of MTBE ml−1. These results suggest that PM1 has potential for use in the remediation of MTBE-contaminated environments. PMID:10543787

  15. Kinetics of the oxidation of methyl tert-butyl ether (MTBE) by potassium permanganate.

    PubMed

    Damm, Jochen H; Hardacre, Christopher; Kalin, Robert M; Walsh, Kayleen P

    2002-08-01

    The occurrence of the fuel oxygenate methyl tert-butyl ether (MTBE) in the environment has received considerable scientific attention. The pollutant is frequently found in the groundwater due to leaking of underground storage tanks or pipelines. Concentrations of more than several mg/L MTBE were detected in groundwater at several places in the US and Germany in the last few years. In situ chemical oxidation is a promising treatment method for MTBE-contaminated plumes. This research investigated the reaction kinetics for the oxidation of MTBE by permanganate. Batch tests demonstrated that the oxidation of MTBE by permanganate is second order overall and first order individually with respect to permanganate and MTBE. The second-order rate constant was 1.426 x 10(-6) L/mg/h. The influence of pH on the reaction rate was demonstrated to have no significant effect. However, the rate of MTBE oxidation by potassium permanganate is 2-3 orders of magnitude lower than of other advanced oxidation processes. The slower rates of MTBE oxidation by permanganate limit the applicability of this process for rapid MTBE cleanup strategies. However, permanganate oxidation of MTBE has potential for passive oxidation risk management strategies. PMID:12230210

  16. Effect of methyl tert-butyl ether in standard tests for mutagenicity and environmental toxicity.

    PubMed

    Vosahlikova, Miluse; Cajthaml, Tomas; Demnerova, Katerina; Pazlarova, Jarmila

    2006-12-01

    Methyl tert-butyl ether (MTBE) is a synthetic compound that is used as a technological solution to problems created by air pollution from vehicle emissions. An important source of MTBE in the environment is leakage from underground storage tanks at gasoline stations or accidents during gasoline transport. The aim of this study was to evaluate the risk of MTBE leakage for the environment using the Microtox (Vibrio fischeri) toxicity test, Lactuca sativa seed germination test, and Ames bacterial mutagenicity test with Salmonella typhimurium his(-) strains TA98, TA100, YG1041, and YG1042, using both standard plate and preincubation protocols. The result of Microtox expressed as EC(50) was 33 mg (MTBE)/L. The effect of all tested MTBE concentration (0.05, 0.50, and 1.00% v/v) on Lactuca sativa roots elongation was negative and proved its toxicity. The highest tested concentration of MTBE that could be tested in Ames test was 3 mg (MTBE)/plate, because of cytotoxicity. No mutagenic response was observed at this or lower concentrations in any of the four strains used. PMID:17091504

  17. Environmental behavior and fate of methyl tert-butyl ether (MTBE)

    USGS Publications Warehouse

    Squillace, Paul J.; Pankow, James F.; Korte, Nic E.; Zogorski, John S.

    1996-01-01

    When gasoline that has been oxygenated with methyl tert-butyl ether (MTBE) comes in contact with water, large amounts of MTBE can dissolve; at 25 degrees Celsius the water solubility of MTBE is about 5,000 milligrams per liter for a gasoline that is 10 percent MTBE by weight. In contrast, for a nonoxygenated gasoline, the total hydrocarbon solubility in water is typically about 120 milligrams per liter. MTBE sorbs only weakly to soil and aquifer materials; therefore, sorption will not significantly retard MTBE's transport by ground water. In addition, MTBE generally resists degradation in ground water. The half-life of MTBE in the atmosphere can be as short as 3 days in a regional airshed. MTBE in the air tends to partition into atmospheric water, including precipitation. However, washout of gas-phase MTBE by precipitation would not, by itself, greatly alter the gas-phase concentration of the compound in the air. The partitioning of MTBE to precipitation is nevertheless strong enough to allow for up to 3 micrograms per liter or more inputs of MTBE to surface and ground water.

  18. [Occupational exposure to methyl tert-butyl ether (MTBE) at an oil refinery].

    PubMed

    Perbellini, L; Pasini, F; Prigioni, P; Rosina, A

    2003-01-01

    Methyl tert-butyl ether (MTBE) is widely used as an additive to gasoline, to increase oxygen content and reduce tailpipe emission of carbon monoxide. Our research dealt with 37 refinery workers in order to measure their occupational exposure to MTBE during two different seasonal periods. They provided blood and urine samples before and after a work shift during which they wore an active charcoal sampler for solvents. All samples were analysed by a gas-chromatograph equipped with a mass spectrometer detector. The concentration in air of MTBE was very low (median: 25 micrograms/m3 in spring and 5 micrograms/m3 in autumn). The blood and urine concentrations of MTBE at the end of the work shift were higher than those found before the shift. The increment in biological samples confirmed a small intake of MTBE by refinery workers: the biological monitoring of occupational exposure to this solvent yielded reliable results. Blood and urinary concentrations of MTBE obtained from workers split in relation to their smoking habit did not give a statistic significance to say that cigarette smoke is not a confusion factor in monitoring exposure to MTBE. PMID:14979074

  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. 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.

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

    PubMed

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

    2001-03-15

    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/Lto a depth of 1.5 m, and MTBE concentrations decreased to <1 microg/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. PMID:11347923

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

    PubMed

    Hartle, R

    1993-12-01

    Concerns for atmospheric pollution from auto exhaust have led to the blending of "oxygenates" 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 areas of the United States in the near future. In consideration of the magnitude of potential uncontrolled exposures from its extensive use and a related concern involving the potential influence of MTBE blending on exposures to other constituents of gasoline (particularly benzene), an evaluation of exposures among service station attendants and operators was undertaken at the request, and in cooperation with, the American Petroleum Institute during the latter part of 1990. For application of the survey results to a broad audience, three categories or types of service stations were identified with regard to MTBE use and exposure potential: a) service stations that do not use MTBE or use it only as an octane enhancer, b) service stations with seasonal requirements to use 12-15% MTBE (the Denver, Colorado, and Phoenix, Arizona, metropolitan areas), and c) service stations equipped with stage II (active) vapor recovery systems (several coastal areas, most notably Southern California). At the two sampled service stations that use only minimal amounts of MTBE (less than 1%), only 1 of 32 personal breathing zone (PBZ) samples from attendants was above the analytical limit of detection, reported at 0.16 ppm. The geometric mean concentration of benzene among this same population (n = 32) was 0.04 ppm.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8020445

  3. Measurement of methyl tert-butyl ether and tert-butyl alcohol in human blood by purge-and-trap gas chromatography-mass spectrometry using an isotope-dilution method.

    PubMed

    Bonin, M A; Ashley, D L; Cardinali, F L; McCraw, J M; Wooten, J V

    1995-01-01

    We developed an isotope-dilution method for measuring methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) in whole human blood using a purge-and-trap gas chromatographic-mass spectrometric method. The labeled analogues for MTBE and TBA were [2H12]methyl tert-butyl ether and [2H9]-tert-butyl alcohol, respectively. Volatiles were removed from the blood by direct helium purging of the liquid; were trapped on a Tenax trap; and were desorbed, cryofocused, and chromatographed on a DB-624 capillary column that was connected directly to the ion source of a mass spectrometer. Detection was by mass analysis using a double-focusing magnetic-sector mass spectrometer operating in the full-scan mode at the medium mass resolution of 3000. For the isotope-dilution method, the minimum detection limits in blood (5-10 mL) are 0.01 microgram/L for MTBE and 0.06 microgram/L for TBA. The isotope-dilution method proved to be a big improvement in recovery, reproducibility, and sensitivity over our previous analytical method, which used the labeled ketone, [4-2H3]-2-butanone, as the internal standard for both MTBE and TBA. The isotope-dilution method has sufficient sensitivity for monitoring blood levels of MTBE and TBA in populations exposed to oxygenated fuels containing MTBE. PMID:7564298

  4. Simultaneous decontamination of hexavalent chromium and methyl tert-butyl ether by UV/TiO2 process.

    PubMed

    Xu, Xiang-Rong; Li, Hua-Bin; Gu, Ji-Dong

    2006-04-01

    Hexavalent chromium and methyl tert-butyl ether (MTBE) are two important environmental pollutants. Simultaneous decontamination of Cr(VI) and MTBE was studied by UV/TiO2 process. The influences of pH and the concentrations of pollutants on the kinetics of the photocatalytic reactions were evaluated. Dark adsorption tests showed that the acidic pH favored the adsorption of Cr(VI) while neutral pH favored the adsorption of MTBE. Under UV irradiation, Cr(VI) reduction was observed in Cr(VI)/TiO2 system, and MTBE oxidation was observed in MTBE/TiO2 system. The system containing Cr(VI) and MTBE by UV/TiO2 process demonstrated the synergistic effect between oxidation of MTBE and reduction of Cr(VI). The results demonstrated that two pollutants Cr(VI) and MTBE could be eliminated simultaneously by UV/TiO2 process. tert-Butyl formate, tert-butyl alcohol and acetone were identified as primary degradation products of MTBE by gas chromatography-mass spectrometry in the degradation of MTBE by UV/TiO2 process. PMID:16169572

  5. Laboratory Method for Analysis of Small Concentrations of Methyl tert-Butyl Ether and Other Ether Gasoline Oxygenates in Water

    USGS Publications Warehouse

    Rose, Donna L.; Connor, Brooke F.; Abney, Sonja R.; Raese, Jon W.

    1998-01-01

    This Fact Sheet presents data for analysis of nanogram-per-liter concentrations of methyl tert-butyl ether (MTBE) and three other ether gasoline oxygenates, including methyl tert-pentyl ether (TAME), diisopropyl ether (DIPE), and ethyl tert-butyl ether (ETBE), by purge- and-trap capillary-column gas chromatography. Long-term method detection levels (LT-MDLs) for MTBE, TAME, DIPE, and ETBE ranged from 15 to 83 nanograms per liter (0.015 to 0.083 microgram per liter). Nanogram-per-liter-concentration detections are reported if all of the identification criteria are met, whereas previous methods censored detections at a pre-determined method reporting level. The reporting level for this method is defined as two times the LT-MDL, does not censor detections at less than this concentration, and is referred to as the nondetection value (NDV). Bias and variability data from multiple analyses, analysts, and instruments over a 60-day period show the oxygenate recoveries ranging from 100 to 109 percent, with 6 to 8 percent relative standard deviation. MTBE, TAME, DIPE, and ETBE were not detected in the analysis of 225 laboratory reagent blanks from January to December 1997. A preservation study in ground water and surface water indicates that all the oxygenates are stable at pH 2 for up to 216 days, with recoveries ranging from 94 to 115 percent on day 216, and relative standard deviations ranging from 5 to 9 percent for the duration of the study.

  6. tert-Butyl cation affinities of maingroup-element hydrides: effect of methyl substituents at the protophilic center.

    PubMed

    Ruiz, Juan M; Guerra, Célia Fonseca; Bickelhaupt, F Matthias

    2011-07-28

    We have conducted an extensive computational exploration of how the gas-phase tert-butyl cation affinities (t-BCA) of archetypal anionic and neutral bases across the periodic system are affected by stepwise replacement of all hydrogen atoms at the protophilic center with methyl substituents. This study was conducted using zeroth-order regular approximation relativistic density functional theory (DFT) at the BP86/QZ4P//BP86/TZ2P level. The trends are interpreted in terms of the steric effects of methyl substituents at the protophilic center of the anionic (Me(m)XH(n-1-m)(-)) and neutral bases (Me(m)XH(n-m)). Besides insight, this work also provides an intrinsically consistent set of values of the 298 K tert-butyl cation affinities of all (partially) methyl-substituted or unsubstituted bases constituted by maingroup-element hydrides of groups 14-16 in anionic cases (Me(m)XH(n-1-m)(-)) and groups 15-17 in neutral ones (Me(m)XH(n-m)) along periods 2-6. The effect of long-range dispersion (van der Waals) interactions was estimated through dispersion-corrected density functional theory (DFT-D3) at the BP86-D3/QZ4P//BP86/TZ2P level. PMID:21718012

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

    PubMed

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

    2007-07-01

    The concentration of methyl tert-butyl ether (MTBE) and its spatio-temporal distribution were researched in atmosphere of the Pearl River Delta (PRD) by sampling with air sampling canisters and analyzing with pre-concentrator and gas chromatograph-mass spectrum instrument. The results showed that 1) MTBE could be prevalently checked in atmosphere of traffic area, industrial area, residential area and commercial area of the PRD, and its range of hourly average concentration in the long-term observation was from 0 - 1.250 microg m(-3), the summer had more serious pollution than the spring, and urban was the central area of high MTBE concentration, and suburban in the downwind was obviously polluted by the urban air. 2) During the enhanced observation in summertime, the diurnal average concentration of Guangzhou urban site was (1.520 +/- 0.370) microg m(-3), which was about 7 times of Huadou site in the downwind of Guangzhou and over 100 times of Conghua site in the background of Guangzhou. In urban, 2 peak values appeared in the period of 10:00 - 12:00 and 16:00 - 18:00 respectively, and the nighttime had the lowest average concentration, but the suburban in the downwind had the peak value in the nighttime. 3) During the enhanced observation in wintertime, the diurnal average concentration of Guangzhou urban site was (0.950 +/- 0.240) microg m(-3), which was 3.6 times of Xinken site in the downwind of Guangzhou. Several peak values appeared on the diurnal variation, the high concentration period of urban was in 18:00 - 22:00, and that of suburban was in 04:00 - 10:00 of the next day. 4) When it was weak sunshine, the concentration of MTBE beside the urban traffic roadside was decreasing with the height increasing, but when it was strong sunshine, it was increasing with the height increasing. So, except the original emission from the automobiles, MTBE still had the secondary pollution sources formed by air photochemical reaction. PMID:17891978

  8. Solubility of anthracene in binary alkane + methyl tert-butyl ether solvent mixtures at 298.15 K

    SciTech Connect

    McHale, M.E.R.; Kauppila, A.S.M.; Acree, W.E. Jr.

    1996-09-01

    Experimental solubilities are reported for anthracene dissolved in seven binary mixtures containing methyl tert-butyl ether (also called 2-methoxy-2-methylpropane) with hexane, heptane, octane, cyclohexane, methylcyclohexane, 2,2,4-trimethylpentane, and tert-butylcyclohexane (also called (1,1-dimethylethyl)-cyclohexane) at 25 C. Results of these measurements are used to test two mathematical representations based upon the combined nearly ideal binary solvent (NIBS)/Redlich-Kister equation and modified Wilson model. For the seven systems studied, both equations were found to provide an accurate mathematical representation of the experimental data, with an overall average absolute deviation between measured and calculated values being on the order of 0.5%.

  9. 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).

  10. Metabolism of Diethyl Ether and Cometabolism of Methyl tert-Butyl Ether by a Filamentous Fungus, a Graphium sp

    PubMed Central

    Hardison, L. K.; Curry, S. S.; Ciuffetti, L. M.; Hyman, M. R.

    1997-01-01

    In this study, evidence for two novel metabolic processes catalyzed by a filamentous fungus, Graphium sp. strain ATCC 58400, is presented. First, our results indicate that this Graphium sp. can utilize the widely used solvent diethyl ether (DEE) as the sole source of carbon and energy for growth. The kinetics of biomass accumulation and DEE consumption closely followed each other, and the molar growth yield on DEE was indistinguishable from that with n-butane. n-Butane-grown mycelia also immediately oxidized DEE without the extracellular accumulation of organic oxidation products. This suggests a common pathway for the oxidation of both compounds. Acetylene, ethylene, and other unsaturated gaseous hydrocarbons completely inhibited the growth of this Graphium sp. on DEE and DEE oxidation by n-butane-grown mycelia. Second, our results indicate that gaseous n-alkane-grown Graphium mycelia can cometabolically degrade the gasoline oxygenate methyl tert-butyl ether (MTBE). The degradation of MTBE was also completely inhibited by acetylene, ethylene, and other unsaturated hydrocarbons and was strongly influenced by n-butane. Two products of MTBE degradation, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), were detected. The kinetics of product formation suggest that TBF production temporally precedes TBA accumulation and that TBF is hydrolyzed both biotically and abiotically to yield TBA. Extracellular accumulation of TBA accounted for only a maximum of 25% of the total MTBE consumed. Our results suggest that both DEE oxidation and MTBE oxidation are initiated by cytochrome P-450-catalyzed reactions which lead to scission of the ether bonds in these compounds. Our findings also suggest a potential role for gaseous n-alkane-oxidizing fungi in the remediation of MTBE contamination. PMID:16535667

  11. Microbial degradation and fate in the environment of methyl tert-butyl ether and related fuel oxygenates.

    PubMed

    Fayolle, F; Vandecasteele, J P; Monot, F

    2001-08-01

    Oxygenates, mainly methyl tert-butyl ether (MTBE), are commonly added to gasoline to enhance octane index and improve combustion efficiency. Other oxygenates used as gasoline additives are ethers such as ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and alcohols such as tert-butyl alcohol (TBA). As a result of its wide use, MTBE has been detected, mainly in the USA, in groundwater and surface waters, and is a cause of concern because of its possible health effects and other undesirable consequences. MTBE is a water-soluble and mobile compound that generates long pollution plumes in aquifers impacted by gasoline releases from leaking tanks. Field observations concur in estimating that, because of recalcitrance to biodegradation, natural attenuation is slow (half-life of at least 2 years). However, quite significant advances have been made in recent years concerning the microbiology of the degradation of MTBE and other oxygenated gasoline additives. The recalcitrance of these compounds results from the presence in their structure of an ether bond and of a tertiary carbon structure. For the most part, only aerobic microbial degradation systems have been reported so far. Consortia capable of mineralizing MTBE have been selected. Multiple instances of the cometabolism of MTBE with pure strains or with microflorae, growing on n-alkanes, isoalkanes, cyclohexane or ethers (diethyl ether, ETBE), have been described. MTBE was converted into TBA in all cases and was sometimes further degraded, but it was not used as a carbon source by the pure strains. However, mineralization of MTBE and TBA by several pure bacterial strains using these compounds as sole carbon and energy source has recently been reported. The pathways of metabolism of MTBE involve the initial attack by a monooxygenase. In several cases, the enzyme was characterized as a cytochrome P-450. After oxygenation, the release of a C -unit as formaldehyde or formate leads to the production of TBA

  12. 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 (3-30 min) and at a fixed pressure of 20 MPa and an oil-to-reactant molar ratio of 1:40. The results showed that under the same reaction conditions, the supercritical methanol method provided the highest yield of biodiesel. At 350 °C and 20 MPa, canola oil was completely converted to biodiesel after 10, 30, and 30 min in the case of - supercritical methanol, ethanol, and MTBE, respectively. The reaction kinetics of biodiesel production was also compared for supercritical methanol, ethanol, and MTBE. PMID:26004381

  13. 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

  14. tert-butyl-substituted cyclooctatetraenes

    SciTech Connect

    Miller, M.J.; Lyttle, M.H.; Streitwieser, A. Jr.

    1981-05-08

    Reaction of cyclooctatetraene (COT) with tert-butyllithium provides a convenient synthesis of tert-butylcyclooctatetraene, 4. As a byproduct of the reaction mixture, 1,4-di-tert-butylcyclooctatriene has been isolated and converted to 1,4-di-tert-butylcyclooctatetraene, 5, by deprotonation with potassium amide and oxidation with iodine. An independent synthesis of 5 was developed from 9-oxabicyclo(6.1.0)octa-2,4,6-triene (cyclooctatetraene oxide), 9. The highly substituted compound 1,3,5,7-tetra-tert-butylcyclooctatetraene (6) has been prepared in 24% overall yield in four steps. The acetylenic ketone 27, prepared from (tert-butylethynyl)copper and pivaloyl chloride, undergoes condensation with dimethyl malonate to give the pyrone ester 28. This ester undergoes facile hydrolysis and decarboxylation in hot concentrated sulfuric acid to yield 4,6-di-tert-butyl-2H-pyran-2-one (22) which is converted to 6 in one step by photolysis in dilute solution.

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

    PubMed

    Ayotte, Joseph D; Argue, Denise M; McGarry, Frederick J; Degnan, James R; Hayes, Laura; Flanagan, Sarah M; Helsel, Dennis R

    2008-02-01

    Methyl tert-butyl ether (MTBE) concentrations > or = 0.2 /microg/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 microg/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. PMID:18323087

  16. 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

  17. Identification of a Ruminococcaceae Species as the Methyl tert-Butyl Ether (MTBE) Degrading Bacterium in a Methanogenic Consortium.

    PubMed

    Liu, Tong; Ahn, Hyeri; Sun, Weimin; McGuinness, Lora R; Kerkhof, Lee J; Häggblom, Max M

    2016-02-01

    The widespread use of methyl tert-butyl ether (MTBE) has caused major contamination of groundwater sources and is a concern due to its taste and odor problems, as well as its toxicity. MTBE can be degraded anaerobically which makes bioremediation of contaminated aquifers a potential solution. Nevertheless, the organisms and mechanisms that are responsible for anaerobic MTBE degradation are still unknown. The aim of our research was to identify the organisms actively degrading MTBE. For this purpose we characterized an anaerobic methanogenic culture enriched with MTBE as the sole carbon source from the New Jersey Arthur Kill intertidal strait sediment. The cultures were analyzed using stable isotope probing (SIP) combined with terminal restriction fragment length polymorphism (T-RFLP), high-throughput sequencing and clone library analysis of bacterial 16S rRNA genes. The sequence data indicated that phylotypes belonging to the Ruminococcaceae in the Firmicutes were predominant in the methanogenic cultures. SIP experiments also showed sequential incorporation of the (13)C labeled MTBE by the bacterial community with a bacterium most closely related to Saccharofermentans acetigenes identified as the bacterium active in O-demethylation of MTBE. Identification of the microorganisms responsible for the activity will help us better understand anaerobic MTBE degradation processes in the field and determine biomarkers for monitoring natural attenuation. PMID:26727046

  18. The efficient photocatalytic degradation of methyl tert-butyl ether under Pd/ZnO and visible light irradiation.

    PubMed

    Seddigi, Zaki S; Ahmed, Saleh A; Bumajdad, Ali; Danish, Ekram Y; Shawky, Ahmed M; Gondal, Mohammed A; Soylak, Mustafa

    2015-01-01

    Methyl tert-butyl ether is a commonly used fuel oxygenate that is present in gasoline. It was introduced to eliminate the use of leaded gasoline and to improve the octane quality because it aids in the complete combustion of fuel by supplying oxygen during the combustion process. Over the past decade, the use of MTBE has increased tremendously worldwide. For obvious reasons relating to accidental spillage, MTBE started to appear as an environmental and human health threat because of its nonbiodegradable nature and carcinogenic potential, respectively. In this work, MTBE was degraded with the help of an advanced oxidation process through the use of zinc oxide as a photocatalyst in the presence of visible light. A mixture of 200 mg of zinc oxide in 350 mL of 50 ppm MTBE aqueous solution was irradiated with visible light for a given time. The complete degradation of MTBE was recorded, and approximately 99% photocatalytic degradation of 100 ppm MTBE solution was observed. Additionally, the photoactivity of 1% Pd-doped ZnO was tested under similar conditions to understand the effect of Pd doping on ZnO. Our results obtained under visible light irradiation are very promising, and they could be further explored for the degradation of several nondegradable environmental pollutants. PMID:25400159

  19. 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.

  20. 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.

  1. Toxicity of methyl tert-butyl ether to plants (Avena sativa, Zea mays, Triticum aestivum, and Lactuca sativa).

    PubMed

    An, Youn-Joo; Kampbell, Donald H; McGill, Mary E

    2002-08-01

    Influence of methyl tert-butyl ether (MTBE) on the germination of seeds and growth of seedling plants were studied in laboratory experiments. Test plants were wild oats (Avena sativa), sweet corn (Zea mays), wheat (Triticum aestivum), and lettuce (Lactuca sativa). Seed germination, shoot growth, and root growth of plants exposed to different concentrations of MTBE in a moist soil were examined. Seed germination and seedling growth in MTBE-contaminated soil were markedly reduced in all test plants. The median lethal concentration values for seed germination tests and the median effective concentration values for shoot or root growth were calculated. The values for lettuce, wild oats, wheat, and sweet corn were in the range of 18 to 91, 362 to 459, 432 to 751, and 672 to 964 mg MTBE/kg soil as dry weight, respectively. Lettuce was most sensitive to MTBE, followed (in order of decreasing sensitivity) by wild oats, wheat, and sweet corn. Because MTBE can be readily absorbed by plants due to its high solubility in water, plant growth was a more sensitive endpoint than seed germination. Shoot length was more reduced in MTBE-contaminated soil than was the root length, which indicated that MTBE might be transported within the plant from the roots to the shoots. PMID:12152769

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

    PubMed

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

    2002-11-15

    Methyl tert-butyl ether (MTBE) is a common groundwater contaminant, introduced to the environment by leaking petroleum storage tanks, urban runoff, and motorized watercraft. In this study. a simplified (static) headspace analysis method was adapted for determination of MTBE in water samples and soil water extracts. The MDL of the headspace method was calculated to be 2.0 microg L(-1) by the EPA single-concentration design method(1) and 1.2 microg L(-1) by a calibration method developed by Hubaux and Vos (Hubaux, A.; Vos, G. Anal. Chem. 1970,42, 849-855). The MDL calculated with the Hubaux and Vos method was favored because it considers both a true positive and a false positive. The static headspace method was applied to analysis of a tap water sample and a monitoring well sample from a gasoline service station, a river sample, and aqueous extracts from soil excavated during removal of a leaking underground storage tank (LUST). The water samples examined in this study had MTTBE concentrations ranging from 6 to 19 microg L(-1). Aqueous extracts of a soil sample taken from the LUST site had 8 microg L(-1) MTBE. PMID:12463380

  3. Synthesis of octane enhancers during slurry-phase Fischer-Tropsch. [801Methyl tert-butyl ether

    SciTech Connect

    Marcelin, G.

    1992-06-24

    The objective of this project is to investigate three possible routes to the formation of ethers, in particular methyl tert-butyl ether (MTBE), during slurry phase Fischer-Tropsch reaction. The three reaction schemes to be investigated are: (1) Addition of isobutylene during the formation of methanol and/or higher alcohols directly from CO and H{sub 2} during slurry-phase Fischer-Tropsch. (2) Addition of isobutylene to FT liquid products including alcohols in a slurry-phase reactor containing an MTBE or other acid catalyst. (3) Addition of methanol to slurry phase FT synthesis making iso-olefins. During the sixth quarter we completed the construction of the slurry bubble column reactor (SBCR), conducted initial shake-down experiments in a cold-flow mode, and finalized the selection process of the acid catalysts for conversion of syngas-produced alcohols and isobutylene to MTBE (scheme 2). Tasks 3, 4, and 5 are awaiting complete implementation of the SBCR system.

  4. 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

  5. Genes involved in the methyl tert-butyl ether (MTBE) metabolic pathway of Mycobacterium austroafricanum IFP 2012.

    PubMed

    Lopes Ferreira, Nicolas; Labbé, Diane; Monot, Frédéric; Fayolle-Guichard, Françoise; Greer, Charles W

    2006-05-01

    Methyl tert-butyl ether (MTBE) is a persistent pollutant of surface and groundwater, and the reasons for its low biodegradability are poorly documented. Using one of the rare bacterial strains able to grow in the presence of MTBE, Mycobacterium austroafricanum IFP 2012, the protein profiles of crude extracts after growth in the presence of MTBE and glucose were compared by SDS-PAGE. Ten proteins with molecular masses of 67, 64, 63, 55, 50, 27, 24, 17, 14 and 11 kDa were induced after growth in the presence of MTBE. Partial amino acid sequences of N-terminal and internal peptide fragments of the 64 kDa protein were used to design degenerate oligonucleotide primers to amplify total DNA by PCR, yielding a DNA fragment that was used as a probe for cloning. A two-step cloning procedure was performed to obtain a 10 327 bp genomic DNA fragment containing seven ORFs, including a putative regulator, mpdR, and four genes, mpdC, orf1, mpdB and orf2, in the same cluster. The MpdB protein (64 kDa) was related to a flavoprotein of the glucose-methanol-choline oxidoreductase family, and the MpdC protein (55 kDa) showed a high similarity with NAD(P) aldehyde dehydrogenases. Heterologous expression of these gene products was performed in Mycobacterium smegmatis mc2 155. The recombinant strain was able to degrade an intermediate of MTBE biodegradation, 2-methyl 1,2-propanediol, to hydroxyisobutyric acid. This is believed to be the first report of the cloning and characterization of a cluster of genes specifically involved in the MTBE biodegradation pathway of M. austroafricanum IFP 2012. PMID:16622053

  6. (2-tert-Butyl-5-hy­droxy­methyl-1,3-dioxan-5-yl)methanol

    PubMed Central

    Vargas, Berenice; Olivas, Amelia; Aguirre, Gerardo; Madrigal, Domingo

    2012-01-01

    In the title compound, C10H20O4, the dioxane ring adopts a chair conformation. The tert-butyl group occupies an equatorial position, and is staggered with respect to the O atoms of the dioxane ring. In the crystal, mol­ecules are connected by O—H⋯O hydrogen-bonds into zigzag chains of R 4 4(8) and R 2 2(12) ring motifs that run parallel to the a axis. PMID:22807874

  7. 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

  8. 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.

    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.

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

    SciTech Connect

    Kane, Staci R.; Chakicherla, Anu Y.; Chain, Patrick S. G.; Schmidt, Radomir; Shin, M; Legler, Tina C.; Scow, Kate M.; Larimer, Frank W; Lucas, Susan; Richardson, P M; Hristova, Krassimira R.

    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.

  10. Carbon Isotope Fractionation during Anaerobic Degradation of Methyl tert-Butyl Ether under Sulfate-Reducing and Methanogenic Conditions

    PubMed Central

    Somsamak, Piyapawn; Richnow, Hans H.; Häggblom, Max M.

    2006-01-01

    Methyl tert-butyl ether (MTBE), an octane enhancer and a fuel oxygenate in reformulated gasoline, has received increasing public attention after it was detected as a major contaminant of water resources. Although several techniques have been developed to remediate MTBE-contaminated sites, the fate of MTBE is mainly dependent upon natural degradation processes. Compound-specific stable isotope analysis has been proposed as a tool to distinguish the loss of MTBE due to biodegradation from other physical processes. Although MTBE is highly recalcitrant, anaerobic degradation has been demonstrated under different anoxic conditions and may be an important process. To accurately assess in situ MTBE degradation through carbon isotope analysis, carbon isotope fractionation during MTBE degradation by different cultures under different electron-accepting conditions needs to be investigated. In this study, carbon isotope fractionation during MTBE degradation under sulfate-reducing and methanogenic conditions was studied in anaerobic cultures enriched from two different sediments. Significant enrichment of 13C in residual MTBE during anaerobic biotransformation was observed under both sulfate-reducing and methanogenic conditions. The isotopic enrichment factors (ɛ) estimated for each enrichment were almost identical (−13.4 to −14.6; r2 = 0.89 to 0.99). A ɛ value of −14.4 ± 0.7 was obtained from regression analysis (r2 = 0.97, n = 55, 95% confidence interval), when all data from our MTBE-transforming anaerobic cultures were combined. The similar magnitude of carbon isotope fractionation in all enrichments regardless of culture or electron-accepting condition suggests that the terminal electron-accepting process may not significantly affect carbon isotope fractionation during anaerobic MTBE degradation. PMID:16461662

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

    PubMed

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

    2013-08-28

    In this work, the interactions of methyl tert-butyl ether (MTBE) on different dealuminated high silica zeolites were studied by means of both experimental and computational approaches. Zeolites with different textural and surface features were selected as adsorbents and the effect of their physico-chemical properties (i.e. pore size architecture and type and amount of surface OH sites) on sorption capacity were studied. High silica mordenite (MOR) and Y zeolites (both with a SiO2/Al2O3 ratio of 200) and ZSM-5 solid (SiO2/Al2O3 ratio of 500) were selected as model sorbents. By combining FTIR and SS-NMR (both (1)H and (13)C CPMAS NMR) spectroscopy it was possible to follow accurately the MTBE adsorption process on highly defective MOR characterized by a high concentration of surface SiOH groups. The adsorption process is found to occur in different steps and to involve isolated silanol sites, weakly interacting silanols, and the siloxane network of the zeolite, respectively. H-bonding and van der Waals interactions occurring between the mordenite surface and MTBE molecules were modeled by DFT calculations using a large cluster of the MOR structure where two adjacent side-pockets were fused in a large micropore to simulate a dealumination process leading to silanol groups. This is the locus where MTBE molecules are more strongly bound and stabilized. FTIR spectroscopy and gravimetric measurements allowed determination of the interaction strength and sorption capacities of all three zeolites. In the case of both Y and MOR zeolites, medium-weak H-bonding with isolated silanols (both on internal and external zeolite surfaces) and van der Waals interactions are responsible for MTBE adsorption, whereas ZSM-5, in which a negligible amount of surface silanol species is present, displays a much lower amount of adsorbed MTBE retained mainly through van der Waals interactions with zeolite siloxane network. PMID:23860729

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

    PubMed Central

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

    2015-01-01

    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

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

    SciTech Connect

    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 0.00625–5 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

  14. 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

  15. Comparative Transcriptome Analysis of Methylibium petroleiphilum PM1 Exposed to the Fuel Oxygenates Methyl tert-Butyl Ether and Ethanol▿ †

    PubMed Central

    Hristova, Krassimira R.; Schmidt, Radomir; Chakicherla, Anu Y.; Legler, Tina C.; Wu, Janice; Chain, Patrick S.; Scow, Kate M.; Kane, Staci R.

    2007-01-01

    High-density whole-genome cDNA microarrays were used to investigate substrate-dependent gene expression of Methylibium petroleiphilum PM1, one of the best-characterized aerobic methyl tert-butyl ether (MTBE)-degrading bacteria. Differential gene expression profiling was conducted with PM1 grown on MTBE and ethanol as sole carbon sources. Based on microarray high scores and protein similarity analysis, an MTBE regulon located on the megaplasmid was identified for further investigation. Putative functions for enzymes encoded in this regulon are described with relevance to the predicted MTBE degradation pathway. A new unique dioxygenase enzyme system that carries out the hydroxylation of tert-butyl alcohol to 2-methyl-2-hydroxy-1-propanol in M. petroleiphilum PM1 was discovered. Hypotheses regarding the acquisition and evolution of MTBE genes as well as the involvement of IS elements in these complex processes were formulated. The pathways for toluene, phenol, and alkane oxidation via toluene monooxygenase, phenol hydroxylase, and propane monooxygenase, respectively, were upregulated in MTBE-grown cells compared to ethanol-grown cells. Four out of nine putative cyclohexanone monooxygenases were also upregulated in MTBE-grown cells. The expression data allowed prediction of several hitherto-unknown enzymes of the upper MTBE degradation pathway in M. petroleiphilum PM1 and aided our understanding of the regulation of metabolic processes that may occur in response to pollutant mixtures and perturbations in the environment. PMID:17890343

  16. Bis[μ-N-(tert-butyl­dimethyl­silyl)-N-(pyridin-2-ylmeth­yl)amido]­bis­[methyl­cobalt(II)

    PubMed Central

    Malassa, Astrid; Agthe, Christine; Görls, Helmar; Westerhausen, Matthias

    2012-01-01

    The green title complex, [Co2(CH3)2(C12H21N2Si)2], was obtained from bis­{[μ-N-tert-butyl­dimethyl­silyl-N-(pyridin-2-ylmeth­yl)amido]­chloridocobalt(II)} and methyl­lithium in diethyl ether at 195 K via a metathesis reaction. The dimeric cobalt(II) complex exhibits a crystallographic center of inversion in the middle of the Co2N2 ring (average Co—N = 2.050 Å). The CoII atom shows a distorted tetra­hedral coordination sphere. The exocyclic Co—N bond length to the pyridyl group shows a similar value of 2.045 (4) Å. The exocyclic methyl group has a rather long Co—C bond length of 2.019 (5) Å. PMID:22969464

  17. Expression of an alkane monooxygenase (alkB) gene and methyl tert-butyl ether co-metabolic oxidation in Pseudomonas citronellolis.

    PubMed

    Bravo, Ana Luisa; Sigala, Juan Carlos; Le Borgne, Sylvie; Morales, Marcia

    2015-04-01

    Pseudomonas citronellolis UAM-Ps1 co-metabolically transforms methyl tert-butyl ether (MTBE) to tert-butyl alcohol with n-pentane (2.6 mM), n-octane (1.5 mM) or dicyclopropylketone (DCPK) (4.4 mM), a gratuitous inducer of alkane hydroxylase (AlkB) activity. The reverse transcription quantitative real-time PCR was used to quantify the alkane monooxygenase (alkB) gene expression. The alkB gene was expressed in the presence of n-alkanes and DCPK and MTBE oxidation occurred only in cultures when alkB was transcribed. A correlation between the number of alkB transcripts and MTBE consumption was found (ΜΤΒΕ consumption in μmol = 1.44e(-13) x DNA copies, R(2) = 0.99) when MTBE (0.84 mM) was added. Furthermore, alkB was cloned and expressed into Escherichia coli and the recombinant AlkB had a molecular weight of 42 kDa. This is the first report where the expression of alkB is related to the co-metabolic oxidation of MTBE. PMID:25432418

  18. 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.

  19. METHYL TERT-BUTYLETHER-WATER INTERACTION

    EPA Science Inventory

    Methyl tert-butyl ether (MTBE) is a well-known environmental contaminant owing to its high solubility in water. Since the early 1990s, MTBE has been added to gasoline to improve air quality in some metropolitan areas of the United States. Improved air quality was, however, achiev...

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

    SciTech Connect

    Tang, G.H.; Shen, Y.; Shen, H.M.

    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.

  2. NQR in tert-butyl chloride

    NASA Astrophysics Data System (ADS)

    Brunetti, Aldo H.

    2004-03-01

    Tert-butyl chloride has been broadly studied experimentally through various techniques such as X-ray crystallography, DTA, and NMR. It was also studied experimentally through nuclear quadrupole resonance (NQR), but this study was limited and incomplete. In this paper, we present a more detailed study of TBC through the NQR of 35Cl. Our results show that near 120 K, the onset of the CH 3 groups semirotations around symmetry axis C3 takes place with an activation energy U=16.1 kJ mol -1. This intramolecular movement produces a T1 minimum near 148 K and is the dominant mechanism of the nuclear spin-lattice relaxation in phase III of this compound. In phase II of TBC, we show that there are not only methyl groups semirotations, but also semirotations of the whole molecule around a different axis from the symmetry axis C' 3 (C-Cl bond) with an activation energy of E=10.4 kJ mol -1.

  3. Thermodynamic properties and ideal-gas enthalpies of formation for butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol

    SciTech Connect

    Steele, W.V.; Chirico, R.D.; Knipmeyer, S.E.; Nguyen, A.; Smith, N.K.

    1996-11-01

    Ideal-gas enthalpies of formation of butyl vinyl ether, 1,2-dimethoxyethane, methyl glycolate, bicyclo-[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, di-tert-butyl ether, and hexane-1,6-diol are reported. Enthalpies of fusion were determined for bicyclo[2.2.1]hept-2-ene and trans-azobenzene. Two-phase (solid + vapor) or (liquid + vapor) heat capacities were determined from 300 K to the critical region or earlier decomposition temperature for each compound studied. Liquid-phase densities along the saturation line were measured for bicyclo[2.2.1]hept-2-ene. For butyl vinyl ether and 1,2-dimethoxyethane, critical temperatures and critical densities were determined from the dsc results and corresponding critical pressures derived from the fitting procedures. Fitting procedures were used to derive critical temperatures, critical pressures, and critical densities for bicyclo[2.2.1]hept-2-ene, 5-vinylbicyclo[2.2.1]hept-2-ene, trans-azobenzene, butyl acrylate, and di-tert-butyl ether. Group-additivity parameters or ring-correction terms useful in the application of the Benson group-contribution correlations were derived.

  4. Synthesis, optical, and thermal properties of glassy trityl group containing luminescent derivatives of 2-tert-butyl-6-methyl-4H-pyran-4-one

    NASA Astrophysics Data System (ADS)

    Zarins, Elmars; Siltane, Karina; Misina, Elina; Kokars, Valdis; Lazdovica, Kristine; Vembris, Aivars; Kampars, Valdis; Muzikante, Inta; Rutkis, Martins

    2012-06-01

    In this work we present simple preparation of original trityl group containing glassy luminescent 6-styryl substituted derivatives of 2-(2-tert-butyl-4H-pyran-4-ylidene)malononitrile (DWK-1TB), 2-(2-tert-butyl-4H-pyran-4-ylidene)-2- ethyl-2-cyanoacetate (KWK-1TB), 2-(2-tert-butyl-4H-pyran-4-ylidene)-1H-indene-1,3(2H)-dione (ZWK-1TB) and 5-(2-tert-butyl-4H-pyran-4-ylidene)pyrimidine-2,4,6(1H,3H,5H)-trione (JWK-1TB). Their optical properties have been investigated. The absorption maxima of synthesized glasses is in region from 425 nm to 515 nm and emission maxima is from 470 nm to 625 nm in solution of dichloromethane. But absorption maxima of their solid films is from 425 nm to 500 nm and emission maxima is in range from 570 nm to 710 nm. Incorporation of bulky trityloxy ethyl groups combining with existing tert-butyl groups results in thin solid films formation of synthesized glasses from volatile organic solvents (chloroform, dichloromethane) without them being doped in any polymer. This makes them perspective for potential applications in organic light-emitting diodes and organic lasers by simple luminescent layer composition with cheap wet-casting approaches. All glasses show good thermal stability with thermal decomposition temperatures from 264° to 318°C and glass transition values up to 158°C for DWK-1TB. These thermal properties of synthesized glasses could make them also useful for potential applications in other optical materials such as materials for nonlinear optics.

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

    PubMed

    Ghasemi, Sahar; Ahmadi, Farhad

    2014-11-15

    Methyl-tert-butyl ether (MTBE) is widely used as an antiknock additive for increasing octane number of gasoline. Recently, the in vivo studies demonstrated that MTBE has genotoxic potential and able to form adducts with DNA. In the work, the interactions of MTBE with calf thymus DNA (ct-DNA) and the Na(+) form of G-quadruplex DNA (wtTel22) were studied by using of head space-solid phase microextraction technique coupled to gas chromatography. The binding equilibrium constants were measured through the equilibriums of a four phase system. In addition, the MTBE Henry's law constants for two different buffers in the temperature range of 283-303K were measured. Thermodynamic studies revealed that the complexation of MTBE to both DNAs is enthalpy favored and entropy disfavored. The thermodynamic results revealed that MTBE may have interaction with ct-DNA via the minor groove of DNA. Also, MTBE may be complexed into the basket of G-quadruplex structure. In addition, the low difference in the binding constants of MTBE for both different DNA targets may confirm that MTBE is poorly selective for different conformations of DNA. PMID:25280162

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

    PubMed Central

    2014-01-01

    The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface modeling (RSM). Using the four-factor-three-level Box–Behnken design, 29 runs were designed considering the effective ranges of the influential factors. The optimized values for the operational parameters under the respective constraints were obtained at PH of 7.2, Fe3O4/ZnO concentration of 1.78 g/L, initial MTBE concentration of 89.14 mg/L and [H2O2]/ [MTBE] molar ratio of 2.33. Moreover, kinetics of MTBE degradation was determined under optimum condition. The study about core/shell magnetic nanoparticles (MNPs) recycling were also carried out and after about four times, the percentage of the photocatalytic degradation was about 70%. PMID:24393372

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

    PubMed

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

    2014-01-01

    The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface modeling (RSM). Using the four-factor-three-level Box-Behnken design, 29 runs were designed considering the effective ranges of the influential factors. The optimized values for the operational parameters under the respective constraints were obtained at PH of 7.2, Fe3O4/ZnO concentration of 1.78 g/L, initial MTBE concentration of 89.14 mg/L and [H2O2]/ [MTBE] molar ratio of 2.33. Moreover, kinetics of MTBE degradation was determined under optimum condition. The study about core/shell magnetic nanoparticles (MNPs) recycling were also carried out and after about four times, the percentage of the photocatalytic degradation was about 70%. PMID:24393372

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

    PubMed Central

    Kim, Gregory; Malayaman, Saninuj N.; Green, Michael Stuart

    2015-01-01

    Cholelithiasis is a prevalent problem in the United States with 14% or more adults affected. Definitive treatment of cholelithiasis is cholecystectomy. When cholecystectomy yields minimal resolution treatment options include expectant management of asymptomatic gallstones or endoscopic retrograde cholangiopancreatogram. We present a case of intrahepatic biliary casts where surgical option was not possible, interventional radiology was unsuccessful, and methyl tert-butyl ether was used to dissolve the biliary obstruction. Dissolution therapy of gallstones was first reported in 1722 when Vollisnieri used turpentine in vitro. While diethyl ether has excellent solubilizing capacity, its low boiling point limited its use surgically as it vaporizes immediately. Diethyl ether can expand 120-fold during warming to body temperature after injection into the biliary system making it impractical for routine use. The use of dissolution is out of favor due to the success of laparoscopic cholecystectomy. Epidemiological studies have shown the general population should have minimal concerns from passive exposure. Dissolution using MTBE remains a viable option if surgical or endoscopic options are not available. However, because of risks involved to both the patient and the staff, careful multidisciplinary team approach must be undertaken to minimize the risks and provide the best possible care to the patient. PMID:26236535

  9. Addition of dimethylsulphoxide to methyl-tert-butyl ether and ethyl propionate increases cholesterol dissolving capacity and cholesterol gall stone dissolution in vitro.

    PubMed Central

    Bergman, J J; Groen, A K; Huibregtse, K; Tytgat, G N

    1994-01-01

    There is a discrepancy between in vitro cholesterol dissolving efficacy of methyl-tert-butyl ether (MTBE) and ethyl propionate and cholesterol gall stone dissolution in vivo. This study investigated whether the presence of bile changes the cholesterol dissolving capacity of MTBE and ethyl propionate. The addition of dimethylsulphoxide to MTBE or ethyl propionate was also studied to discover if it improves the dissolving capacity for cholesterol gall stones. The presence of bile caused a 25% decrease in cholesterol dissolving capacity of both MTBE and ethyl propionate (p < 0.0001). This inhibitory effect of bile could be overcome by the addition of dimethyl-sulphoxide: dimethylsulphoxide caused an increase in cholesterol dissolving capacity of MTBE and ethyl propionate, the increase depending on the dimethyl-sulphoxide/bile ratio in the mixture. Mean dissolution time of weight, size, and patient matched cholesterol gall stones was 220 minutes in MTBE and 130 minutes in MTBE/dimethylsulphoxide (p < 0.0001). No stones dissolved completely in ethyl propionate or ethyl propionate/dimethyl-sulphoxide within 300 minutes. In conclusion, MTBE/dimethylsulphoxide is a more potent dissolving agent for cholesterol gall stones than MTBE, giving a 40% reduction in dissolution time. Addition of dimethylsulphoxide to ethyl propionate does not result in faster stone dissolution. MTBE and MTBE/dimethylsulphoxide are far superior to ethyl propionate as solvents for cholesterol gall stones. PMID:7828992

  10. Detection and Quantification of Methyl tert-Butyl Ether-Degrading Strain PM1 by Real-Time TaqMan PCR

    PubMed Central

    Hristova, Krassimira R.; Lutenegger, Christian M.; Scow, Kate M.

    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 laboratory and field samples. Specific primers and probes were designed for the 16S ribosomal DNA region, and specificity of the primers was confirmed with DNA from 15 related bacterial strains. A linear relationship was measured between the threshold fluorescence (CT) value and the quantity of PM1 DNA or PM1 cell density. The detection limit for PM1 TaqMan assay was 2 PM1 cells/ml in pure culture or 180 PM1 cells/ml in a mixture of PM1 with Escherichia coli cells. We could measure PM1 densities in solution culture, groundwater, and sediment samples spiked with PM1 as well as in groundwater collected from an MTBE bioaugmentation field study. In a microcosm biodegradation study, increases in the population density of PM1 corresponded to the rate of removal of MTBE. PMID:11679339

  11. Interaction of insulin with methyl tert-butyl ether promotes molten globule-like state and production of reactive oxygen species.

    PubMed

    Valipour, Masoumeh; Maghami, Parvaneh; Habibi-Rezaei, Mehran; Sadeghpour, Mostafa; Khademian, Mohamad Ali; Mosavi, Khadijeh; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2015-09-01

    Interaction of methyl tert-butyl ether (MTBE) with proteins is a new look at its potential adverse biological effects. When MTBE is released to the environment it enters the blood stream through inhalation, and could affect the properties of various proteins. Here we investigated the interaction of MTBE with insulin and its effect on insulin structural changes. Our results showed that insulin formed a molten globule (MG)-like structure in the presence of 8 μM MTBE under physiological pH. The insulin structural changes were studied using spectroscopy methods, viscosity calculation, dynamic light scattering and differential scanning calorimetry. To delineate the mechanisms involved in MTBE-protein interactions, the formation of reactive oxygen specious (ROS) and formation of protein aggregates were measured. The chemiluminscence experiments revealed an increase in ROS production in the presence of MTBE especially in the MG-like state. These results were further confirmed by the aggregation tests, which indicated more aggregation of insulin at 40 μM MTBE compared with 8 μM. Thus, the formation of initial aggregates and exposure of the hydrophobic patches upon formation of the MG-like state in the presence of MTBE drives protein oxidation and ROS generation. PMID:26193678

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

    PubMed

    Kim, Gregory; Malayaman, Saninuj N; Green, Michael Stuart

    2015-01-01

    Cholelithiasis is a prevalent problem in the United States with 14% or more adults affected. Definitive treatment of cholelithiasis is cholecystectomy. When cholecystectomy yields minimal resolution treatment options include expectant management of asymptomatic gallstones or endoscopic retrograde cholangiopancreatogram. We present a case of intrahepatic biliary casts where surgical option was not possible, interventional radiology was unsuccessful, and methyl tert-butyl ether was used to dissolve the biliary obstruction. Dissolution therapy of gallstones was first reported in 1722 when Vollisnieri used turpentine in vitro. While diethyl ether has excellent solubilizing capacity, its low boiling point limited its use surgically as it vaporizes immediately. Diethyl ether can expand 120-fold during warming to body temperature after injection into the biliary system making it impractical for routine use. The use of dissolution is out of favor due to the success of laparoscopic cholecystectomy. Epidemiological studies have shown the general population should have minimal concerns from passive exposure. Dissolution using MTBE remains a viable option if surgical or endoscopic options are not available. However, because of risks involved to both the patient and the staff, careful multidisciplinary team approach must be undertaken to minimize the risks and provide the best possible care to the patient. PMID:26236535

  13. 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

  14. OCCURRENCE OF METYL TERT-BUTYL ETHER (MTBE) AT FIVE MARINAS IN LAKE TEXOMA

    EPA Science Inventory



    Occurrence of methyl tert-butyl ether (MTBE) in five marinas was monitored between June 1999 and November 2000 in Lake Texoma located on the border of Oklahoma and Texas. MTBE is a commonly used gasoline additive and a suspected carcinogen. Lake water was collected at loc...

  15. 4-tert-Butyl-pyridinium chloride-4,4'-(propane-2,2-di-yl)bis-(2,6-di-methyl-phenol)-toluene (2/2/1).

    PubMed

    Nielson, Alastair J; Waters, Joyce M

    2014-04-01

    In the title solvated salt, C9H14N(+)·Cl(-)·C19H24O2·0.5C7H7, two mol-ecules of 4,4'-(propane-2,2-di-yl)bis-(2,6-di-methyl-phenol) are linked via O-H⋯Cl hydrogen bonds to two chloride ions, each of which is also engaged in N-H⋯Cl hydrogen bonding to a 4-tert-butyl-pyridinium cation, giving a cyclic hydrogen-bonded entity centred at 1/2, 1/2, 1/2. The toluene solvent mol-ecule resides in the lattice and resides on an inversion centre; the disorder of the methyl group requires it to have a site-occupancy factor of 0.5. No crystal packing channels are observed. PMID:24826127

  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

  17. Bis(μ-2-tert-butyl-phenyl-imido-1:2κN:N)chlorido-2κCl-(diethyl ether-1κO)(2η-penta-methyl-cyclo-penta-dien-yl)lithiumtantalum(V).

    PubMed

    Cole, Jacqueline M; Chan, Michael C W; Gibson, Vernon C; Howard, Judith A K

    2011-06-01

    In the title compound, [LiTa(C(10)H(15))(C(10)H(13)N)(2)Cl(C(4)H(10)O)], the Ta(V) atom is coordinated by a η(5)-penta-methyl-cyclo-penta-dienyl (Cp*) ligand, a chloride ion and two N-bonded 2-tert-butyl-phenyl-imide dianions. With respect to the two N atoms, the chloride ion and the centroid of the Cp* ring, the tantalum coordination geometry is approximately tetra-hedral. The lithium cation is bonded to both the 2-tert-butyl-phenyl-imide dianions and also a diethyl ether mol-ecule, in an approximate trigonal planar arrangement. The Ta⋯Li separation is 2.681 (15) Å. In the crystal, a weak C-H⋯Cl inter-action links the mol-ecules. When compared to the 2,6-diisopropyl-phenyl-imide analogue ('the Wigley derivative') of the title compound, the two structures are conformationally matched with an overall r.m.s. difference of 0.461Å. PMID:21754594

  18. IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (Interagency Science Consultation Draft)

    EPA Science Inventory

    On April 29, 2016, the Toxicological Review of tert-Butyl Alcohol (tert-Butanol) (Public Comment Draft) was released for public comment. The draft Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and the Executive Office ...

  19. IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (Public Comment Draft)

    EPA Science Inventory

    EPA is developing an Integrated Risk Information System (IRIS) assessment of tert-butyl Alcohol (tert-butanol) and has released the public comment draft assessment for public comment and external peer review. When final, the assessment will appear on the IRIS databa...

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

    USGS Publications Warehouse

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

    2002-01-01

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

  1. Synthesis, molecular structure, spectral analysis and nonlinear optical studies on 4-(4-bromophenyl)-1-tert-butyl-3-methyl-1H-pyrazol-5-amine: A combined experimental and DFT approach

    NASA Astrophysics Data System (ADS)

    Tamer, Ömer; Arslan, Barış Seçkin; Avcı, Davut; Nebioğlu, Mehmet; Atalay, Yusuf; Çoşut, Bünyemin

    2016-02-01

    4-(4-bromophenyl)-1-tert-butyl-3-methyl-1H-pyrazol-5-amine (BPTBMPA) crystal was synthesized for the first time and its structural characterization was performed by X-ray diffraction method. The spectroscopic characterization was also performed by the applying of FT-IR, UV-Vis, 1H and 13C NMR spectroscopies. In order to support experimental results, density functional theory calculations have been performed. All of the obtained theoretical results are in a perfect agreement with the experimental ones. The negative HOMO and LUMO energies demonstrated that the molecular structure of BPTBMPA is stable. The small energy gap between the HOMO and LUMO is an indicator of intramolecular charge transfer which is responsible for nonlinear optical properties. Natural bond orbital analysis also indicates the presence of molecular charge transfer within BPTBMPA. Obtained chemical hardness parameter demonstrates that BPTBMPA has considerable electron donor groups. Finally, it has been showed that BPTBMPA exhibits considerable nonlinear optical properties.

  2. 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.

  3. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

  4. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  5. 27 CFR 21.101 - tert-Butyl alcohol.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false tert-Butyl alcohol. 21.101 Section 21.101 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants §...

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

    PubMed

    Piveteau, P; Fayolle, F; Vandecasteele, J P; Monot, F

    2001-04-01

    A new aerobic bacterial strain, CIP 1-2052, 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 0.032 +/- 0.004 h(-1) and 35.8 +/- 8.5 mg TBA x g(-1) (cell dry mass) per h, respectively. The growth yield on TBA was 0.54 +/- 0.02 g x g(-1). Strain CIP 1-2052 exhibited a particular substrate specificity towards alcohols. It degraded tertiary alcohols, TBA and tert-amyl alcohol (TAA), but neither their primary and secondary alcohol homologues, nor ethanol. However, one-carbon compounds, namely methanol and formate, were degraded by strain CIP 1-2052, showing the methylotrophic nature of this isolate. The properties of this new strain suggest that it could be used for bioremediation of contaminated aquifers. PMID:11341321

  7. tert-Butyl Hydroperoxide Mediated Cascade Synthesis of 3-Arylsulfonylquinolines.

    PubMed

    Zhang, Liangliang; Chen, Su; Gao, Yuzhen; Zhang, Pengbo; Wu, Yile; Tang, Guo; Zhao, Yufen

    2016-03-18

    3-Arylsulfonylquinoline derivatives play important roles as pharmaceutical drugs. A new method for the synthesis of 3-arylsulfonylquinoline derivatives has been achieved through tert-butyl hydroperoxide mediated cycloaddition between N-propargyl aromatic amine derivatives and arylsulfonylhydrazides without the addition of any metals. This transformation offers a straightforward route to the formation of a C-S bond and quinoline ring in one step via a sulfonylation-cyclization-aromatization process. PMID:26959409

  8. {gamma}-aminobutyric acid{sub A} (GABA{sub A}) receptor regulates ERK1/2 phosphorylation in rat hippocampus in high doses of Methyl Tert-Butyl Ether (MTBE)-induced impairment of spatial memory

    SciTech Connect

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

    2009-04-15

    Experimental and occupational exposure to Methyl Tert-Butyl Ether (MTBE) has been reported to induce neurotoxicological and neurobehavioral effects, such as headache, nausea, dizziness, and disorientation, etc. However, the molecular mechanisms involved in MTBE-induced neurotoxicity are still not well understood. In the present study, we investigated the effects of MTBE on spatial memory and the expression and function of GABA{sub A} receptor in the hippocampus. Our results demonstrated that intraventricular injection of MTBE impaired the performance of the rats in a Morris water maze task, and significantly increased the expression of GABA{sub A} receptor {alpha}1 subunit in the hippocampus. The phosphorylation of ERK1/2 decreased after the MTBE injection. Furthermore, the decreased ability of learning and the reduction of phosphorylated ERK1/2 level of the MTBE-treated rats was partly reversed by bicuculline injected 30 min before the training. These results suggested that MTBE exposure could result in impaired spatial memory. GABA{sub A} receptor may play an important role in the MTBE-induced impairment of learning and memory by regulating the phosphorylation of ERK in the hippocampus.

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

    PubMed Central

    Greenwood, Mark H; Sims, Ronald C; McLean, Joan E; Doucette, William J

    2007-01-01

    Background Remediation of tert-butyl alcohol (TBA) in subsurface waters should be taken into consideration at reformulated gasoline contaminated sites since it is a biodegradation intermediate of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-butyl formate (TBF). The effect of temperature on TBA biodegradation has not been not been published in the literature. Methods Biodegradation of [U 14C] TBA was determined using hyporheic zone soil microcosms. Results First order mineralization rate constants of TBA at 5°C, 15°C and 25°C were 7.84 ± 0.14 × 10-3, 9.07 ± 0.09 × 10-3, and 15.3 ± 0.3 × 10-3 days-1, respectively (or 2.86 ± 0.05, 3.31 ± 0.03, 5.60 ± 0.14 years-1, respectively). Temperature had a statistically significant effect on the mineralization rates and was modelled using the Arrhenius equation with frequency factor (A) and activation energy (Ea) of 154 day-1 and 23,006 mol/J, respectively. Conclusion Results of this study are the first to determine mineralization rates of TBA for different temperatures. The kinetic rates determined in this study can be used in groundwater fate and transport modelling of TBA at the Ronan, MT site and provide an estimate for TBA removal at other similar shallow aquifer sites and hyporheic zones as a function of seasonal change in temperature. PMID:17877835

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

    PubMed Central

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

    2011-01-01

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

  11. 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.

  12. Allylic Oxidations Catalyzed by Dirhodium Caprolactamate via Aqueous tert-Butyl Hydroperoxide: The Role of the tert-Butylperoxy Radical

    PubMed Central

    McLaughlin, Emily C.; Choi, Hojae; Wang, Kan; Chiou, Grace; Doyle, Michael P.

    2009-01-01

    Dirhodium(II) caprolactamate exhibits optimal efficiency for the production of the tert-butylperoxy radical, which is a selective reagent for hydrogen atom abstraction. These oxidation reactions occur with aqueous tert-butyl hydroperoxide (TBHP) without rapid hydrolysis of the caprolactamate ligands on dirhodium. Allylic oxidations of enones yield the corresponding enedione in moderate to high yields, and applications include allylic oxidations of steroidal enones. Although methylene oxidation to a ketone is more effective, methyl oxidation to a carboxylic acid can also be achieved. The superior efficiency of dirhodium(II) caprolactamate as a catalyst for allylic oxidations by TBHP (mol % catalyst, % conversion) is described in comparative studies with other metal catalysts that are also reported to be effective for allylic oxidations. That different catalysts produce essentially the same mixture of products with the same relative yields suggests that the catalyst is not involved in product forming steps. Mechanistic implications arising from studies of allylic oxidation with enones provide new insights into factors that control product formation. A previously undisclosed disproportionation pathway, catalyzed by the tert-butoxy radical, of mixed peroxides for the formation of ketone products via allylic oxidation has been uncovered. PMID:19072696

  13. Isotope effects on the metabolism and pulmonary toxicity of butylated hydroxytoluene in mice by deuteration of the 4-methyl group

    SciTech Connect

    Mizutani, T.; Yamamoto, K.; Tajima, K.

    1983-06-30

    A comparative test in mice for pulmonary toxicity between butylated hydroxytoluene (2,6-di-tert.-butyl-4-methylphenol, BHT) and 2,6-di-tert.-butyl-4-(alpha, alpha, alpha-2H3)methylphenol (BHT-d3) showed a significantly lower toxic potency of the latter. The rate of in vitro BHT metabolism to 2,6-di-tert.-butyl-4-methylene-2,5-cyclohexadienone (BHT-QM) was slowed by deuterating BHT in the 4-methyl group. On the other hand, the rate of in vitro metabolism to 2,6-di-tert.-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-OH) was increased with the deuteration. A similar isotope effect of the deuterium substitution on the in vivo metabolic rates of BHT was observed. These observations support the concept that the lung damage caused by BHT is mediated by BHT-QM. The pulmonary toxicity of 2-tert.-butyl-4-ethylphenol (4-EP) and their deuterated analogs was also compared. 2-tert.-Butyl-4-(1,1-2H2)ethylphenol (4-EP-d2) showed a significantly lower toxic potency than 4-EP, whereas 2-tert.-butyl-4-(2,2,2-2H3)ethylphenol (4-EP-d3) showed a toxic potency comparable to that of 4-EP. This result is consistent with the hypothesis that a quinone methide metabolite is responsible for the onset of lung damage produced by 4-EP as well as BHT.

  14. 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.

  15. 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.

  16. Occurrence and implications of methyl tert-butyl ether and gasoline hydrocarbons in ground water and source water in the United States and in drinking water in 12 Northeast and Mid-Atlantic States, 1993-2002

    USGS Publications Warehouse

    Moran, Michael J.; Zogorski, John S.; Squillace, Paul J.

    2004-01-01

    The occurrence and implications of methyl tert-butyl ether (MTBE) and gasoline hydrocarbons were examined in three surveys of water quality conducted by the U.S. Geological Survey?one national-scale survey of ground water, one national-scale survey of source water from ground water, and one regional-scale survey of drinking water from ground water. The overall detection frequency of MTBE in all three surveys was similar to the detection frequencies of some other volatile organic compounds (VOCs) that have much longer production and use histories in the United States. The detection frequency of MTBE was higher in drinking water and lower in source water and ground water. However, when the data for ground water and source water were limited to the same geographic extent as drinking-water data, the detection frequencies of MTBE were comparable to the detection frequency of MTBE in drinking water. In all three surveys, the detection frequency of any gasoline hydrocarbon was less than the detection frequency of MTBE. No concentration of MTBE in source water exceeded the lower limit of U.S. Environmental Protection Agency's Drinking-Water Advisory of 20 ?g/L (micrograms per liter). One concentration of MTBE in ground water exceeded 20 ?g/L, and 0.9 percent of drinking-water samples exceeded 20 ?g/L. The overall detection frequency of MTBE relative to other widely used VOCs indicates that MTBE is an important concern with respect to ground-water management. The probability of detecting MTBE was strongly associated with population density, use of MTBE in gasoline, and recharge, and weakly associated with density of leaking underground storage tanks, soil permeability, and aquifer consolidation. Only concentrations of MTBE above 0.5 ?g/L were associated with dissolved oxygen. Ground water underlying areas with high population density, ground water underlying areas where MTBE is used as a gasoline oxygenate, and ground water underlying areas with high recharge has a greater

  17. n-Alkane assimilation and tert-butyl alcohol (TBA) oxidation capacity in Mycobacterium austroafricanum strains.

    PubMed

    Lopes Ferreira, Nicolas; Mathis, Hugues; Labbé, Diane; Monot, Frédéric; Greer, Charles W; Fayolle-Guichard, Françoise

    2007-06-01

    Mycobacterium austroafricanum IFP 2012, which grows on methyl tert-butyl ether (MTBE) and on tert-butyl alcohol (TBA), the main intermediate of MTBE degradation, also grows on a broad range of n-alkanes (C2 to C16). A single alkB gene copy, encoding a non-heme alkane monooxygenase, was partially amplified from the genome of this bacterium. Its expression was induced after growth on n-propane, n-hexane, n-hexadecane and on TBA but not after growth on LB. The capacity of other fast-growing mycobacteria to grow on n-alkanes (C1 to C16) and to degrade TBA after growth on n-alkanes was compared to that of M. austroafricanum IFP 2012. We studied M. austroafricanum IFP 2012 and IFP 2015 able to grow on MTBE, M. austroafricanum IFP 2173 able to grow on isooctane, Mycobacterium sp. IFP 2009 able to grow on ethyl tert-butyl ether (ETBE), M. vaccae JOB5 (M. austroaafricanum ATCC 29678) able to degrade MTBE and TBA and M. smegmatis mc2 155 with no known degradation capacity towards fuel oxygenates. The M. austroafricanum strains grew on a broad range of n-alkanes and three were able to degrade TBA after growth on propane, hexane and hexadecane. An alkB gene was partially amplified from the genome of all mycobacteria and a sequence comparison demonstrated a close relationship among the M. austroafricanum strains. This is the first report suggesting the involvement of an alkane hydroxylase in TBA oxidation, a key step during MTBE metabolism. PMID:17347817

  18. Metabolism of 3-tert-butyl-4-hydroxyanisole to 3-tert-butyl-4,5-dihydroxyanisole by rat liver microsomes.

    PubMed

    Armstrong, K E; Wattenberg, L W

    1985-04-01

    3-tert-Butylhydroxyanisole (3-BHA) is an antioxidant which can have a modulating effect on chemical carcinogenesis. Information concerning the metabolism of 3-BHA is incomplete. In the present study, the metabolites formed by incubating 3-BHA with liver microsomes from rats given beta-naphthoflavone by p.o. intubation were studied. Three metabolites were identified, two major metabolites and a minor metabolite. One of the major metabolites was the catechol of 3-BHA, i.e., 3-tert-butyl-4,5-dihydroxyanisole, which has not previously been reported. A characteristic of this compound is its capacity to be oxidized readily. The second major metabolite was tert-butyl hydroquinone which has been reported previously to be a liver microsomal metabolite of 3-BHA. The third metabolite, which occurred in small quantities, was 2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxydiphenyl. 2,2'-Dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxydiphenyl has been identified previously as a major metabolite of 3-BHA in the rat intestine. An understanding of the metabolism of 3-BHA may assist in elucidating the mechanism(s) of its biological effects. PMID:3978617

  19. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  20. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  1. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  2. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to...

  3. Preparation, characterization and application of p-tert-butyl-calix[4]arene-SBA-15 mesoporous silica molecular sieves.

    PubMed

    Huang, Huayu; Zhao, Chuande; Ji, Yongsheng; Nie, Rong; Zhou, Pan; Zhang, Haixia

    2010-06-15

    p-tert-Butyl-calix[4]arene-SBA-15 mesoporous silica molecular sieves have been prepared and characterized by Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD) and nitrogen adsorption-desorption measurements. FT-IR spectra showed the presence of methylene (-CH(2)-), methyl (-CH(3)) and phenyl bands on the modified SBA-15. Powder XRD data indicated the structure of p-tert-butyl-calix[4]arene-SBA-15 remained the host SBA-15 structure. Brunauer-Emmett-Teller (BET) surface area analysis revealed a decrease in surface area and pore size. The adsorption capacity of the materials to diethylstilbestrol and bisphenol A was studied via the dynamic adsorption experiments. The maximum dynamic adsorption capacity on modified materials was 34.8 and 2.9 times higher than SBA-15 particles for diethylstilbestrol and bisphenol A, respectively. The results indicated that p-tert-butyl-calix[4]arene-SBA-15 particles could be used to the enrich the various compounds in water samples before the further analysis. PMID:20185235

  4. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  5. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  6. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... substituted methyl styrene, methyl methacrylate, and substituted silane. 721.6920 Section 721.6920 Protection... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  7. 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

  8. 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,...

  9. 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

  10. The oxidation of 2,6-di-tert-butyl-4-methylphenol

    USGS Publications Warehouse

    Yohe, G.R.; Dunbar, J.E.; Pedrotti, R.L.; Scheidt, F.M.; Lee, F.G.H.; Smith, E.C.

    1956-01-01

    The products formed in the oxidation of 2,6-di-tert-butyl-4-methylphenol with oxygen and sodium hydroxide at about 100?? are 3,5-di-tert-butyl-4-hydroxybenzaldehyde, trimethylacetic acid, an acidic compound C14H22O3, and probably 2,6-di-tert-butylbenzoquinone (which was actually isolated in the similar oxidation of the above-named benzaldehyde), in addition to compounds previously reported. Some of the properties of C14H22O3 are given, and the oxidation of it to 2,3-di-tert-butylsuccinic anhydride is described, but assignment of structure is reserved pending the completion of more experimental work.

  11. Automatic mechanism generation for pyrolysis of di-tert-butyl sulfide.

    PubMed

    Class, Caleb A; Liu, Mengjie; Vandeputte, Aäron G; Green, William H

    2016-08-01

    The automated Reaction Mechanism Generator (RMG), using rate parameters derived from ab initio CCSD(T) calculations, is used to build reaction networks for the thermal decomposition of di-tert-butyl sulfide. Simulation results were compared with data from pyrolysis experiments with and without the addition of a cyclohexene inhibitor. Purely free-radical chemistry did not properly explain the reactivity of di-tert-butyl sulfide, as the previous experimental work showed that the sulfide decomposed via first-order kinetics in the presence and absence of the radical inhibitor. The concerted unimolecular decomposition of di-tert-butyl sulfide to form isobutene and tert-butyl thiol was found to be a key reaction in both cases, as it explained the first-order sulfide decomposition. The computer-generated kinetic model predictions quantitatively match most of the experimental data, but the model is apparently missing pathways for radical-induced decomposition of thiols to form elemental sulfur. Cyclohexene has a significant effect on the composition of the radical pool, and this led to dramatic changes in the resulting product distribution. PMID:27431650

  12. Studies on the Conformational Landscape of Tert-Butyl Acetate Using Microwave Spectroscopy and Quantum Chemical Calculations

    NASA Astrophysics Data System (ADS)

    Zhao, YueYue; Mouhib, Halima; Li, Guohua; Stahl, Wolfgang; Kleiner, Isabelle

    2014-06-01

    The tert-Butyl acetate molecule was studied using a combination of quantum chemical calculations and molecular beam Fourier transform microwave spectroscopy in the 9 to 14 GHz range. Due to its rather rigid frame, the molecule possesses only two different conformers: one of Cs and one of C1 symmetry. According to ab initio calculations, the Cs conformer is 46 kJ/mol lower in energy and is the one observed in the supersonic jet. We report on the structure and dynamics of the most abundant conformer of tert-butyl acetate, with accurate rotational and centrifugal distortion constants. Additionally, the barrier to internal rotation of the acetyl methyl group was determined. Splittings due to the internal rotation of the methyl group of up to 1.3 GHz were observed in the spectrum. Using the programs XIAM and BELGI-Cs, we determine the barrier height to be about 113 cm-1 and compare the molecular parameters obtained from these two codes. Additionally, the experimental rotational constants were used to validate numerous quantum chemical calculations. This study is part of a larger project which aims at determining the lowest energy conformers of organic esters and ketones which are of interest for flavor or perfume synthetic applications Project partly supported by the PHC PROCOPE 25059YB.

  13. Conformational analysis of tert-butyl acetate using a combination of microwave spectroscopy and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Zhao, Yueyue; Mouhib, Halima; Li, Guohua; Kleiner, Isabelle; Stahl, Wolfgang

    2016-04-01

    tert-Butyl acetate was investigated using a combination of quantum chemical calculations and molecular beam Fourier transform microwave spectroscopy. The microwave spectrum was recorded in the frequency range from 8.00 to 15.75 GHz. Due to its rather rigid frame, the molecule possesses only two conformers: one of Cs symmetry and one of C1 symmetry that appears as a pair of enantiomers. The Cs conformer is the most abundant in the supersonic jet and according to ab initio calculations at the MP2/6-311++G(d, p) level of theory it is 46 kJ/mol lower in energy than the C1 conformer. Here, we report on the structure and dynamics of the most abundant conformer of tert-butyl acetate, for which a set of rotational and centrifugal distortion constants, as well as the barrier to internal rotation of the acetyl methyl group were determined with high accuracy. Splittings due to the internal rotation of the methyl group of up to 1.3 GHz were observed in the spectrum. Using the programs XIAM and BELGI-Cs, we were able to determine a barrier height of about 113 cm-1 and subsequently compare the molecular parameters obtained from these two codes.

  14. 40 CFR 721.4925 - Methyl n-butyl ketone.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Methyl n-butyl ketone. 721.4925 Section 721.4925 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.4925 Methyl n-butyl ketone....

  15. tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding.

    PubMed

    Stoyanov, Evgenii S; Gomes, Gabriel dos Passos

    2015-08-13

    Despite the seeming similarity of the infrared (IR) spectra between tert-butyl cations (t-Bu(+)) in gaseous and condensed phases, there are important but so far unrecognized differences. The IR spectroscopic investigation of the hydrogen (H)-bonding of t-Bu(+) with the immediate environment together with the X-ray crystallographic data shows that one CH3 group of t-Bu(+) differs from the other two. In the Ar-tagged t-Bu(+) in vacuum, this group is predominantly polarized, showing three C-H stretch vibrations at 2913, 2965, and 3036 cm(-1) whereas the other two methyls are predominantly involved in strong hyperconjugation, yielding an intense triple IR band with a maximum at 2839 cm(-1). In a condensed phase, the bulk solvent effect promoted participation of the polarized CH3 group in additional hyperconjugation, decreasing its νCH3 frequencies by approximately 120 cm(-1), whereas frequencies of the other CH3 groups decreased by only ca. 4-10 cm(-1). This observation indicates that the influence of the condensed phase on t-Bu(+) stabilization is substantial. Thus, enhancement of H-bonding between t-Bu(+) and Anion(-) strengthens hyperconjugation and promotes further cation stabilization. PMID:26172244

  16. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  17. 40 CFR 721.6920 - Butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted...

  18. Alkylation of C60. Reaction between C60 anions and tert-butyl chloride and mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Bourcier, S.; Chaurand, P.; Ciot, C.; Della-Negra, S.; Fabre, C.; Greugny, V.; Marx, L.; Rassat, A.; Rousseau, A.

    1996-11-01

    Alkylation of C60 in tetrahydrofuran with tert-butyl chloride and lithium gives a variety of products. Adducts of general formula C60Hn(t-Bu)qOx(thf)y (where t-Bu is the tert-butyl group and thf the tetrahydrofuryl group (C4H7O)) have been detected by mass spectrometry, with n <= 8, q + y <= 18 and x = 0, 1, 2 depending on experimental conditions. IR and NMR spectra of products confirm these assignments.

  19. Bis(1-tert-butyl-1H-imidazole-κN3)dichloridocobalt(II).

    PubMed

    Herdtweck, Eberhardt; Zeller, Alexander; Strassner, Thomas

    2012-06-01

    In the crystal structure of the title compound, [CoCl(2)(C(7)H(12)N(2))(2)], molecular units are formed by coordination of the unsubstituted N atoms of two tert-butyl-substituted imidazole molecules and two chloride ligands, which distinguishes the complex from structures of imidazolium-based dications with tetrachloridocobaltate dianions. There are two crystallographically independent molecules in the asymmetric unit, related by a noncrystallographic inversion centre. PMID:22669189

  20. Stark effect in the J = 3 4 microwave line of tert-butyl chloride molecule

    NASA Astrophysics Data System (ADS)

    Gierszal, S.; Mis-Kuzminska, E.; Stankowski, J.; Galica, J.

    1984-03-01

    Stark effect in the J = 3 - 4 transition spectrum of the tert-butyl chloride has been investigated. The perturbation of the rotational levels by combined effect of the quadrupole and an intermediate electric fields was calculated and used for identify the Stark components. The rotational spectrum of tert-butyl chloride /CH 3/ 3CCl is characterised by the rotational constants A = 4518.70 MHz[1] and B = 3017.85 MHz, dipole moment U= 2.12 D, and quadrupole interaction constant eqQ = -67.58 MHz [2,3]. The energy of rotational states of the tert-butyl chloride molecule is described by the Hamiltonian ? where H 0 is the unperturbed rotational energy, H Q that of interaction of the angular momentum and quadrupole moment of the chlorine nucleus, and H E the Stark energy. Since H Q ˜ H E for the electric field strengths applied during the present investigation, we are dealing with the case of intermediate fields. To solve the problem theoretically we had recourse to the representation in F-space and calculated the energy for the perturbation H Q + H E as done by Low and Townes [4]. The theoretical distances of the Stark components from the absorption line of tert-butyl chloride for various electric field strengths at J = 3 - 4 and ΔM F = 0 is shown in Fig. 1a and 1b. We applied the theoretically calculated distances of the Stark components from the absorption line of /CH 3/ 3CCl as function of the electric field strength as well as the relative intensities of the components in order to interpret our experimental results concerning the Stark effect.

  1. Crystal structures of three complexes of zinc chloride with tri-tert-butyl­phosphane

    PubMed Central

    Finke, Aaron D.; Gray, Danielle L.; Moore, Jeffrey S.

    2016-01-01

    Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butyl­phosphane as the μ-bridged dimer is formed, viz. di-μ-chlorido-bis­[chlorido­bis­(tri-tert-butyl­phosphane)zinc], [ZnCl4(C12H27P)2], (1), which features a nearly square-shaped (ZnCl)2 cyclic core and whose Cl atoms inter­act weakly with C—H groups on the phosphane ligand. In the presence of THF, monomeric di­chlorido­(tetra­hydro­furan-κO)(tri-tert-butyl­phosphane-κP)zinc, [ZnCl2(C4H8O)(C12H27P)] or [P(tBu3)(THF)ZnCl2], (2), is formed. This slightly distorted tetra­hedral Zn complex has weak C—H⋯Cl inter­actions between the Cl atoms and phosphane and THF C—H groups. Under ambient conditions, the hydrolysed complex tri-tert-butyl­phospho­nium aqua­tri­chlorido­zincate 1,2-di­chloro­ethane monosolvate, (C12H28P)[ZnCl3(H2O)]·C2H4Cl2 or [HPtBu3]+ [(H2O)ZnCl3]−·C2H4Cl2, (3), is formed. This complex forms chains of [(H2O)ZnCl3]− anions from hydrogen-bonding inter­actions between the water H atoms and Cl atoms that propagate along the b axis. PMID:26870580

  2. Crystal structures of three complexes of zinc chloride with tri-tert-butyl-phosphane.

    PubMed

    Finke, Aaron D; Gray, Danielle L; Moore, Jeffrey S

    2016-01-01

    Under anhydrous conditions and in the absence of a Lewis-base solvent, a zinc chloride complex with tri-tert-butyl-phosphane as the μ-bridged dimer is formed, viz. di-μ-chlorido-bis-[chlorido-bis-(tri-tert-butyl-phosphane)zinc], [ZnCl4(C12H27P)2], (1), which features a nearly square-shaped (ZnCl)2 cyclic core and whose Cl atoms inter-act weakly with C-H groups on the phosphane ligand. In the presence of THF, monomeric di-chlorido-(tetra-hydro-furan-κO)(tri-tert-butyl-phosphane-κP)zinc, [ZnCl2(C4H8O)(C12H27P)] or [P(tBu3)(THF)ZnCl2], (2), is formed. This slightly distorted tetra-hedral Zn complex has weak C-H⋯Cl inter-actions between the Cl atoms and phosphane and THF C-H groups. Under ambient conditions, the hydrolysed complex tri-tert-butyl-phospho-nium aqua-tri-chlorido-zincate 1,2-di-chloro-ethane monosolvate, (C12H28P)[ZnCl3(H2O)]·C2H4Cl2 or [HPtBu3](+) [(H2O)ZnCl3](-)·C2H4Cl2, (3), is formed. This complex forms chains of [(H2O)ZnCl3](-) anions from hydrogen-bonding inter-actions between the water H atoms and Cl atoms that propagate along the b axis. PMID:26870580

  3. Discovery and application of new bacterial strains for asymmetric synthesis of L-tert-butyl leucine in high enantioselectivity.

    PubMed

    Jin, Jian-Zhong; Chang, Dong-Liang; Zhang, Jie

    2011-06-01

    Discovery of new bacterial strains with fast identification in a miniaturized system was performed for the synthesis of optically active L-tert-butyl leucine. With tert-butyl leucine amide as nitrogen source, one bacterial strain with high conversion and high enantioselectivity was discovered among 120 isolated microorganisms from local soils and identified as Mycobacterium sp. JX009. Glucose and ammonium chloride were examined as the good carbon source and nitrogen source for the cells' growth separately. The cells grew better at 30 °C and at pH 7.5 with higher activity of 2,650 U/l in comparison with other conditions. Cells' stability was improved by immobilization on synthetic resin 0730 without pretreatment. Tert-butyl leucine amide (30 mM) was successfully hydrolyzed by immobilized cells and examined as the highest chemical concentration that cells could endure. After six reaction cycles, the immobilized cells retained 90% activity with production of L-tert-butyl leucine in 98% ee. The results firstly reported the application of new bacterial strain in the hydrolysis of tert-butyl leucine amide to produce optically active L-tert-butyl leucine in an efficient way with investigation in detail. PMID:21153891

  4. A new amphiphilic derivative, N-{[4-(lactobionamido)methyl]benzylidene}-1,1-dimethyl-2-(octylsulfanyl)ethylamine N-oxide, has a protective effect against copper-induced fulminant hepatitis in Long-Evans Cinnamon rats at an extremely low concentration compared with its original form alpha-phenyl-N-(tert-butyl) nitrone.

    PubMed

    Asanuma, Taketoshi; Yasui, Hironobu; Inanami, Osamu; Waki, Kenji; Takahashi, Momoko; Iizuka, Daisuke; Uemura, Taketo; Durand, Grégory; Polidori, Ange; Kon, Yasuhiro; Pucci, Bernard; Kuwabara, Mikinori

    2007-09-01

    An amphiphilic alpha-phenyl-N-(tert-butyl) nitrone (PBN) derivative, N-{[4-(lactobionamido)methyl]benzylidene}-1,1-dimethyl-2-(octylsulfanyl)ethylamine N-oxide (LPBNSH), newly synthesized from its original form PBN in hopes of clinical use, was intraperitoneally administered to Long-Evans Cinnamon (LEC) rats every 2 days at the concentrations of 0.1, 0.5, 1.0, and 2.0 mg/kg. We found that LPBNSH protected against copper-induced hepatitis with jaundice in LEC rats at concentrations of 0.1 and 0.5 mg/kg, which were extremely low compared with that of PBN. It also effectively prevented the loss of body weight, reduced the death rate, and suppressed the increase in serum aspartate aminotransferase and alanine aminotransferase values arising from fulminant hepatitis with jaundice at the same concentrations. Similar results were observed when PBN was administered at the concentration of 150 mg/kg. Immunohistochemical analysis of 8-hydroxy-2'-deoxyguanosine and measurement of thiobarbituric acid-reactive substances in the liver showed that LPBNSH largely suppressed the formation of these oxidative products at same concentrations. No difference in the abnormal accumulation of copper in the liver between the LPBNSH administered and control groups was observed. From these results, it was concluded that LPBNSH exhibited liver-protective effects against fulminant hepatitis with jaundice at ca. 1/1000, 500 the molar concentration of PBN and, therefore, was clinically promising. PMID:17886845

  5. Oxidation of 2,6-di-tert-butyl-4-methylphenol. The structure of C14H22O3

    USGS Publications Warehouse

    Yohe, G.R.; Dunbar, J.E.; Lansford, M.W.; Pedrotti, R.L.; Scheidt, F.M.; Lee, F.G.H.; Smith, E.C.

    1959-01-01

    The acidic compound C14H22O3, previously reported without assignment of structure as an oxidation product of 2,6-di-tert-butyl-4-methylphenol, is now believed to be DL-trans-5,6-di-tert-butyl-2-hydroxy-1,4-diketo-2-cyclohexene (I). Chemical properties are described and infrared spectra are presented in support of this structure. This structure is of interest in relation to the problem of the existence of o-di-tert-alkylbenzene derivatives. The relatively easy racemization of optically active I suggests that its completely enolized form, 5,6-di-tert-butyl-1,2,4-trihydroxybenzene, is capable of transitory existence.

  6. Synthesis, structural characterization, electronic spectroscopy, and microfluidic detection of Cu+2 and UO2+2 [di-tert-butyl-salphenazine] complexes†

    PubMed Central

    Maynard, B. A.; Brooks, J. C.; Hardy, E. E.; Easley, C. J.; Gorden, A. E. V.

    2015-01-01

    Metal templation by condensation of 2,3-diaminophenazine with 3,5-di-tert-butyl-2-hydroxybenzaldehyde around the metal centers [M = Cu(ii), and UO2(vi)] affords a new class of M[di-tert-butyl sal-phenazine] metal complexes. Reported here is the synthesis, single crystal X-ray structural characterization, electronic spectroscopy, and microfluidic detection of the formation of these M[di-tert-butyl sal-phenazine] complexes. PMID:25657039

  7. Molecular Dynamics of Tert-butyl Chloride Confined to CPG (7.4, 15.6 nm)

    NASA Astrophysics Data System (ADS)

    Szutkowska, L.; Peplińska, B.; Jurga, S.

    2006-08-01

    The paper complements our earlier NMR investigation of molecular dynamics of tert-butyl chloride restricted by geometries of the type MCM-41 and CPG by the new sizes of CPG and by differential scanning calorimetry method. We report proton and deuteron NMR lineshapes and the spin-lattice relaxation results of tert-butyl chloride in CPG of the 15.6 nm and 7.4 nm pore diameter in the temperature range 70 K ≤ T ≤ 292 K. The bulk-like component of the confined tert-butyl chloride, in temperatures corresponding to phase III, is interpreted as a composition of two dynamically different subphases. The parameters of motions of both subphases are derived. The tert-butyl group motion in both subphases is more restricted than in the bulk tert-butyl chloride, although the activation energies are lower. Differential scanning calorimetry was used to determine temperatures of the phase transitions (140 K ≤T ≤292 K). The results show that the depression of the phase transition temperature is pore size dependent and that the confinement has less influence on transition to the plastic phase than on the freezing and on the solid II - solid III transition.

  8. 5,5'-Di-tert-butyl-2,2'-dihydroxy-3,3'-methylenedibenzaldehyde and 6,6'-di-tert-butyl-8,8'-methylenebis(spiro[4H-1,3-benzodioxin-2,1'-cyclohexane]).

    PubMed

    Masci, Bernardo; Mortera, Stefano Levi; Seralessandri, Luca; Thuéry, Pierre

    2004-02-01

    Two related compounds containing p-tert-butyl-o-methylene-linked phenol or phenol-derived subunits are described, namely 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-methylenedibenzaldehyde, C(23)H(28)O(4), (I), and 6,6'-di-tert-butyl-8,8'-methylenebis(spiro[4H-1,3-benzodioxin-2,1'-cyclohexane]), C(35)H(48)O(4), (II). Both compounds adopt a 'butterfly' shape, with the two phenol or phenol-derived O atoms in distal positions. Phenol and aldehyde groups in (I) are involved in intramolecular hydrogen bonds and the two dioxin rings in (II) are in distorted half-chair conformations. PMID:14767128

  9. Chemoselective Nitration of Phenols with tert-Butyl Nitrite in Solution and on Solid Support

    PubMed Central

    Koley, Dipankar; Colón, Olvia C.; Savinov, Sergey N

    2009-01-01

    tert-Butyl nitrite was identified as a safe and chemoselective nitrating agent that provides preferentially mononitro derivatives of phenolic substrates in the presence of potentially competitive functional groups. On the basis of our control experiments, we propose that the reaction proceeds through the formation of O-nitrosyl intermediates prior to C-nitration via homolysis and oxidation. The reported nitration method is compatible with tyrosine-containing peptides on solid support in the synthesis of fluorogenic substrates for characterization of proteases. PMID:19697919

  10. 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 (τ = 120 ± 10 ps) and 2 (τ = 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

  11. Phases and phase changes in clusters of tert-butyl thiol

    NASA Astrophysics Data System (ADS)

    Hovick, James W.; Bartell, Lawrence S.

    1997-09-01

    Clusters of tert-butyl thiol (TBT) were generated by condensation of vapor in supersonic flow under various expansion conditions, and their structures were examined during their free flight by electron diffraction. The system had been selected because of its similarity to tert-butyl chloride (TBC), a much more thoroughly studied material with an interesting solid-state chemistry. The warmest crystalline phase of TBT observed for the clusters (diameter, ≈ 130 Å) was the known high-temperature cubic phase I with a lattice constant of 8.609(5) Å at ≈ 160 K. A second phase into which phase I nucleated at a rate of ≈ 10 28 m -3 s -1 at about 157 K was also observed, as well as a third phase generated under conditions of very cold flow. All of the phases gave the rapidly damped, diffuse diffraction patterns characteristic of submicroscopic, poorly ordered, plastically crystalline materials. Patterns were far less distinct than those of TBC, and the structures of the colder two phases could not be determined. From the rapid nucleation rate of phase I into the second phase, it could be inferred that a major translational rearrangement of the molecules could not have been involved.

  12. 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.…

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

    SciTech Connect

    Alia, Mario . 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.

  14. Synthesis and Assembly of Dipolar Heterostructured Tetrapods: Colloidal Polymers with "Giant tert-butyl" Groups.

    PubMed

    Pavlopoulos, Nicholas G; Dubose, Jeffrey T; Pinna, Nicola; Willinger, Marc-Georg; Char, Kookheon; Pyun, Jeffrey

    2016-01-26

    We report on the first synthesis of a heterostructured semiconductor tetrapod from CdSe@CdS that carries a single dipolar nanoparticle tip from a core-shell colloid of Au@Co. A four-step colloidal total synthesis was developed, where the key step in the synthesis was the selective deposition of a single AuNP tip onto a CdSe@CdS tetrapod under UV-irradiation. Synthetic accessibility to this dipolar heterostructured tetrapod enabled the use of these as colloidal monomers to form colloidal polymers that carry the semiconductor tetrapod as a side chain group attached to the CoNP colloidal polymer main chain. The current report details a number of novel discoveries on the selective synthesis of an asymmetric heterostructured tetrapod that is capable of 1D dipolar assembly into colloidal polymers that carry tetrapods as side chain groups that mimic "giant tert-butyl groups". PMID:26696128

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

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

  16. 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})

  17. Kinetics and mechanism of alkane hydroperoxidation with tert-butyl hydroperoxide catalysed by a vanadate anion.

    PubMed

    Shul'pin, Georgiy B; Kozlov, Yuriy N

    2003-07-01

    tert-Butyl hydroperoxide oxidizes alkanes in acetonitrile at 60 degrees C if the soluble vanadium(v) salt, n-Bu4NVO3, is used as a catalyst. Alkyl hydroperoxides are formed as main products which decompose during the course of the reaction to produce the more stable corresponding alcohols and ketones. Turnover numbers (ie. numbers of moles of products per one mole of a catalyst) attained 250. The kinetics and selectivity of the reaction have been studied. The mechanism proposed involves the formation of a complex between the V(V) species and t-BuOOH (K5 was estimated to be 5 dm3 mol(-1)) followed by decomposition of this complex (k6 = 0.2 s(-1)). The generated V(IV) species reacts with another t-BuOOH molecule to produce an active t-BuO* radical which attacks the hydrocarbon. PMID:12945701

  18. Absolute rate constants of alkoxyl radical reactions in aqueous solution. [Tert-butyl hydroperoxide

    SciTech Connect

    Erben-Russ, M.; Michel, C.; Bors, W.; Saran, M.

    1987-04-23

    The pulse radiolysis technique was used to generate the alkoxyl radical derived from tert-butyl hydroperoxide (/sup t/BuOOH) in aqueous solution. The reactions of this radical with 2,2'-azinobis(3-ethyl-6-benzothiazolinesulfonate) (ABTS) and promethazine were monitored by kinetic spectroscopy. The unimolecular decay rate constant of the tert-butoxyl radical (/sup t/BuO) was determined to be 1.4 x 10/sup 6/ s/sup -1/. On the basis of this value, the rate constants for /sup t/BuO attack on quercetin, crocin, crocetin, ascorbate, isoascorbate, trolox c, glutathione, thymidine, adenosine, guanosine, and unsaturated fatty acids were determined. In addition, the reaction of /sup t/BuO with the polyunsaturated fatty acids (PUFA) was observed by directly monitoring the formation of the fatty acid pentadienyl radicals. Interestingly, the attack of /sup t/BuO on PUFA was found to be faster by about one order of magnitude as compared to the same reaction in a nonpolar solvent.

  19. 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

  20. Differential TERT promoter methylation and response to 5-aza-2'-deoxycytidine in acute myeloid leukemia cell lines: TERT expression, telomerase activity, telomere length, and cell death.

    PubMed

    Pettigrew, Kerry A; Armstrong, Richard N; Colyer, Hilary A A; Zhang, Shu-Dong; Rea, Irene Maeve; Jones, Rhiannon E; Baird, Duncan M; Mills, Ken I

    2012-08-01

    The catalytic subunit of human telomerase (TERT) is highly expressed in cancer cells, and correlates with complex cytogenetics and disease severity in acute myeloid leukemia (AML). The TERT promoter is situated within a large CpG island, suggesting that expression is methylation-sensitive. Studies suggest a correlation between hypermethylation and TERT overexpression. We investigated the relationship between TERT promoter methylation and expression and telomerase activity in human leukemia and lymphoma cell lines. DAC-induced demethylation and cell death were observed in all three cell lines, as well as telomere shortening in HL-60 cells. DAC treatment reduced TERT expression and telomerase activity in OCI/AML3 and HL-60 cells, but not in U937 cells. Control U937 cells expressed lower levels of TERT mRNA, carried a highly methylated TERT core promoter, and proved more resistant to DAC-induced repression of TERT expression and cell death. AML patients had significantly lower methylation levels at several CpGs than "well elderly" individuals. This study, the first to investigate the relationship between TERT methylation and telomerase activity in leukemia cells, demonstrated a differential methylation pattern and response to DAC in three AML cell lines. We suggest that, although DAC treatment reduces TERT expression and telomerase activity, this is unlikely to occur via direct demethylation of the TERT promoter. However, further investigations on the regions spanning CpGs 7-12 and 14-16 may reveal valuable information regarding transcriptional regulation of TERT. PMID:22517724

  1. N-tert-Butyl-2-methyl­propanamide

    PubMed Central

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

    2011-01-01

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

  2. N-tert-Butyl-2-methyl-propanamide.

    PubMed

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

    2011-08-01

    The title compound, C(8)H(17)NO, crystallizes with two independent mol-ecules in the asymmetric unit. In the crystal, inter-molecular N-H⋯O hydrogen bonding is observed between neighboring mol-ecules, forming continuous mol-ecular chains along the c-axis direction. PMID:22091159

  3. [[(tert-Butyl)dimethylsilyl]oxy]methyl group for sulfur protection.

    PubMed

    Wang, Lihong; Clive, Derrick L J

    2011-04-01

    Aromatic and aliphatic thiols can be protected by reaction with t-BuMe(2)SiOCH(2)Cl in DMF in the presence of a base (2,6-lutidine or proton sponge); the resulting t-BuMe(2)SiOCH(2)SR or t-BuMe(2)SiOCH(2)SAr are deprotected by sequential treatment with Bu(4)NF and I(2) to give symmetrical disulfides. Another mode of deprotection involves reaction with a sulfenyl chloride; this process gives an unsymmetrical disulfide and was examined with Me(CH(2))(11)SCH(2)OSiMe(2)Bu-t and three sulfenyl chlorides. PMID:21391576

  4. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2... 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2'-(1,2-diazenediyl)bis - and...

  5. Arylalkylation of 4-tert-butyltoluene with substituted benzyl chlorides

    SciTech Connect

    Pozdnyakovich Y.V.; Savyak, R.P.; Shein, S.M.

    1986-08-01

    The reaction of 4-alkylbenzyl chlorides with 4-tert-butyltoluene in the presence of titanium tetrachloride and ferric chloride leads to the formation of 2-methyl-4'-alkyl-5-tert-butyldiphenylmethanes. The arylalkylation of 4-tert-butyltoluene with 2- and 4-chlorobenzyl chlorides, catalyzed by titanium tetrachloride, leads to the formation of mixtures of 2-methyl-5-tert-butyldiphenylmethane, 2-tert-butyl-5-methyldiphenylmethane, and isomeric methyldiphenylmethanes containing a chloride atom in the benzyl fragment. The products of the reaction catalyzed by ferric chloride do not contain 2-tert-butyl-5-methylchlorodiphenylmethanes. The reaction of 4-nitrobenzyl chloride with 4-tert-butyltoluence in the presence of ferric chloride leads to the formation of a mixture of 2-methyl-4'-nitro-5-tert-butyldiphenylmethane and isomeric methylnitrodiphenylmethanes. Under the influence of AlCl/sub 3/-CH/sub 3/NO/sub 2/ in benzene 2,4'-dimethyl-5-tert-butyldiphenylmethane eliminates both the 4-methylbenzyl group and the tert-butyl group. Under analogous conditions 2-methyl-5-tert-butyldiphenylmethanes containing a chlorine atom or a nitro group in the benzyl fragment are dealkylated with the elimination of only the tert-butyl group.

  6. tert-Butyl N-[2-(N-isobutyl-4-meth-oxy-benzene-sulfonamido)-eth-yl]carbamate.

    PubMed

    Bai, Xiao-Guang; Wang, Ju-Xian

    2014-06-01

    The title compound, C18H30N2O5S, was synthesized by the reaction of tert-butyl 2-(iso-butyl-amino)-ethyl-carbamate with p-meth-oxy-phenyl-sulfonyl chloride. In the mol-ecule, two intra-molecular C-H⋯O hydrogen bonds are observed. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds involving the imino group N atom and the ester group O atom into chains running parallel to the b axis. The chains are further connected by C-H⋯O hydrogen bonds, forming layers parallel to the bc plane. PMID:24940254

  7. On the stoichiometry between uncouplers of oxidative phosphorylation and respiratory chains. The catalytic action of SF 6847 (3,5-di-tert-butyl-4-hydroxy-benzylidenemalononitrile).

    PubMed

    Terada, H; VAN Dam, K

    1975-06-17

    Titration of State 4 rat-liver mitochondria at pH 7.2 with the uncoupler 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile (SF 6847) at various concentrations of mitochondria and using various substrates indicates that under optimal conditions less than 0.2 molecule of 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile per respiratory chain is sufficient to induce complete uncoupling. This result suggests that there is not a stoichiometric relationship between uncoupler molecules and cytochrome c oxidase, involved in oxidative phosphorylation, or between the former and phosphorylation assemblies. Experiments on the release by 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile of azide-inhibited respiration of State 3 mitochondria and titrations with 5-chloro-3-tert-butyl-2'-chloro-4'-nitrosalicylanilide (S13) of State 4 mitochondria at various mitochondrial concentrations confirm this conclusion. PMID:1138887

  8. Features of the spectral dependences of transmittance of organic semiconductors based on tert-butyl substituted lutetium phthalocyanine molecules

    SciTech Connect

    Belogorokhov, I. A.; Tikhonov, E. V.; Dronov, M. A.; Belogorokhova, L. I.; Ryabchikov, Yu. V.; Tomilova, L. G.; Khokhlov, D. R.

    2011-11-15

    Vibronic properties of organic semiconductors based on tert-butyl substituted phthalocyanine lutetium diphthalocyanine molecules are studied by IR and Raman spectroscopy. It is shown that substitution of several carbon atoms in initial phthalocyanine (Pc) ligands with {sup 13}C isotope atoms causes a spectral shift in the main absorption lines attributed to benzene, isoindol, and peripheral C-H groups. A comparison of spectral characteristics showed that the shift can vary from 3 to 1 cm{sup -1}.

  9. ansa-Chromocene complexes. 1. Synthesis and characterization of Cr(II) carbonyl and tert-butyl isocyanide complexes

    SciTech Connect

    Matare, G.J.; Foo, D.M.; Kane, K.M.; Zehnder, R.; Wagener, M.; Shapiro, P.J.; Concolino, T.; Rheingold, A.L.

    2000-04-17

    ansa-Calcocene compounds are effective reagents for the synthesis of ansa-chromocene complexes from CrCl{sub 2} in the presence of a trapping ligand such as carbon monoxide or an isonitrile. A variety of ansa-chromocene carbonyl and tert-butyl isocyanide complexes have been prepared in this manner in high yields. The X-ray crystal structure of one of these complexes, [trans-1,2-(3,4-(CH{sub 3}O){sub 2}C{sub 6}H{sub 3}){sub 2}C{sub 2}H{sub 2}{l_brace}{eta}{sup 5}-C{sub 5}H{sub 4}{r_brace}{sub 2}]CrCO, is described. Electrochemical studies on these complexes show that the isonitrile derivatives are more easily oxidized than the carbonyl derivatives. Preliminary examination of the reactivity of these complexes indicates that the nature of the substitution along the ethanediyl ansa-bridge influences the relative stabilities of the carbonyl complexes to oxidation in air, the ease with which the carbonyl ligands undergo substitution with tert-butyl isocyanide, and the relative sensitivities of the tert-butyl isocyanide adducts to photodecomposition. The ansa-bridge substitution also appears to influence the ability of the complexes to undergo structural changes, such as ring slippage, as revealed in their cyclic voltammograms.

  10. 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

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

    PubMed

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

    2009-08-15

    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 x/d=1.4 is 1440 K whereas the emission temperature experimentally determined from thermograms at x/d approximately 1.3 is 1560 K. The predicted surface emissive power for d=1.12m is 115 kW/m(2) in comparison to the measured surface emissive power of 130 kW/m(2) whereas for d=3.4m these values are 180 and 250 kW/m(2). The predicted distance dependent irradiances agree well with the measured irradiances. PMID:19185989

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

    PubMed Central

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

    2001-01-01

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

  13. Insight into the formation of the tert-butyl cation confined inside H-ZSM-5 zeolite from NMR spectroscopy and DFT calculations.

    PubMed

    Huang, Mengdi; Wang, Qiang; Yi, Xianfeng; Chu, Yueying; Dai, Weili; Li, Landong; Zheng, Anmin; Deng, Feng

    2016-08-23

    Solid-state NMR experiments and DFT calculations have been carried out to determine the complex structures of coadsorbed (13)C-labeled tert-butanol and NH3 in acidic H-ZSM-5 zeolite. It is found, besides the physically adsorbed tert-butanol/NH4(+) complex on Brønsted acid sites, the tert-butylamine cation is formed as well, confirming the presence of the tert-butyl cation confined in zeolite channels. Furthermore, (13)C-(27)Al double-resonance solid-state NMR spectroscopy is adopted to determine the host/guest interaction between the carbocation and the zeolite framework. PMID:27400892

  14. 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 (ΔH(‡)), entropy (ΔS(‡)), and free energy (ΔG(‡)) of activation], calculated using Arrhenius and Eyring-Polanyi equations, established that TBA (2%, w/w) accelerated GHCl crystallization by reducing its ΔH(‡) (53.9 cf. 96.5 kJ/mol⁻¹) and ΔG(‡) (68.5 cf. 74.9 kJ/mol⁻¹). Further, to explore insights into the effect of TBA on nucleation and crystal growth of GHCl, crystallization kinetics data were deconvolved using Finke-Watzky model. This revealed that addition of TBA decreased ΔH(‡) of nucleation and increased ΔS(‡) of crystal growth, thereby reducing ΔG(‡) of nucleation and crystal growth by 11.7% and 4.2%, respectively. Finkey-Watzky model also predicted a reduction in the crystal size upon TBA addition, which was confirmed by comparing particle size of GHCl lyophilized in the presence and absence of TBA. In conclusion, TBA reduces ΔG(‡) of nucleation and crystal growth in a differential manner, thereby enhancing the crystallization kinetics of GHCl and affecting its morphological features. PMID:25393155

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

    PubMed

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

    2010-08-01

    The X-ray crystal structure of the title compound, [Zn(C(2)H(5))(C(24)H(40)BN(6))], or Tp(tBu,Me)ZnEt [Tp(tBu,Me) is tris(3-tert-butyl-5-methylpyrazolyl)hydridoborate], reveals a distorted tetrahedral geometry around the Zn atom. The Zn center is coordinated by three N atoms of the borate ligand and by one C atom of the ethyl group. The present structure and other tetrahedral Tp zinc alkyl complexes are compared with similar Ttz ligands (Ttz is 1,2,4-triazolylborate), but no major differences in the structures are noted, and it can be assumed that variation of the substitution pattern of Tp or Ttz ligands has little or no influence on the geometry of alkylzinc complexes. Refinement of the structure is complicated by a combination of metric pseudosymmetry and twinning. The metrics of the structure could also be represented in a double-volume C-centered orthorhombic unit cell, and the structure is twinned by one of the orthorhombic symmetry operators not present in the actual structure. The twinning lies on the borderline between pseudomerohedral and nonmerohedral. The data were refined as being nonmerohedrally twinned, pseudomerohedrally twinned and untwinned. None of the approaches yielded results that were unambiguously better than any of the others: the best fit between structural model and data was observed using the nonmerohedral approach which also yielded the best structure quality indicators, but the data set is less than 80% complete due to rejected data. The pseudomerohedral and the untwinned structures are complete, but relatively large residual electron densities that are not close to the metal center are found with values up to three times higher than in the nonmerohedral approach. PMID:20679703

  16. The Synthesis and Isolation of N-Tert-Butyl-2-Phenylsuccinamic Acid and N-Tert-Butyl-3-Phenylsuccinamic Acid: An Undergraduate Organic Chemistry Laboratory Experiment

    ERIC Educational Resources Information Center

    Cesare, Victor; Sadarangani, Ishwar; Rollins, Janet; Costello, Dennis

    2004-01-01

    The facile, high yielding synthesis of phenylsuccinamic acids is described and one of these syntheses, the reaction of phenylsuccinic anhydride with tert-butylamine, is successfully modified and adapted for use in the second-semester organic chemistry laboratory at St. John's University. Succinamic acids are compounds that contain both the amide…

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

    PubMed Central

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

    2015-01-01

    An electrochemical method with the ability to conduct 18F-fluorination of aromatic molecules through direct nucleophilic fluorination of cationic intermediates is presented in this paper. The reaction was performed on a remote-controlled automatic platform. Nucleophilic electrochemical fluorination of tert-butyloxycarbonyl (Boc) protected catechol, an intermediate model molecule for the positron emission tomography (PET) probe (3,4-dihydroxy-6-[18F]fluoro-l-phenylalanine), was performed. Fluorination was achieved under potentiostatic anodic oxidation in acetonitrile containing Et3N · 3HF and other supporting electrolytes. Radiofluorination efficiency was influenced by a number of variables, including the concentration of the precursor, concentration of Et3N · 3HF, type of supporting electrolyte, temperature and time, as well as applied potentials. Radiofluorination efficiency of 10.4 ± 0.6% (n = 4) and specific activity of up to 43 GBq/mmol was obtained after 1 h electrolysis of 0.1 M of 4-tert-butyl-diboc-catechol in the acetonitrile solution of Et3N · 3HF (0.033 M) and NBu4PF6 (0.05 M). Density functional theory (DFT) was employed to explain the tert-butyl functional group facilitation of electrochemical oxidation and subsequent fluorination. PMID:25000498

  18. 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.

  19. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2...-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2′-(1,2-diazenediyl)bis - and 2,2... butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2),...

  20. 40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2...-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2′-(1,2-diazenediyl)bis - and 2,2... butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2),...

  1. 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

  2. Computer-assisted automated synthesis. III. Synthesis of substituted N-(carboxyalkyl) amino-acid tert-butyl ester derivatives.

    PubMed

    Hayashi, N; Sugawara, T; Kato, S

    1991-01-01

    A versatile automated synthesis apparatus, equipped with a chemical artificial intelligence, was developed to prepare and isolate a wide variety of compounds. The apparatus was to the synthesis of substituted N-(carboxyalkyl)amino-acids. The apparatus [1,2] is composed of units for performing various tasks,for example reagent supply, reaction, purification and separation, each linked to a control system. All synthetic processes, including washing and drying of the apparatus after each synthetic run, were automatically performed from the mixing of the reactants to the isolation of the products as powders or crystals. The reaction of an amino-acid tertbutyl ester acetic acid salt with a 2-keto acid sodium salt produces an unstable intermediate, Schiff base, which is reduced with sodum cyanoborohydride to give a substituted N-(carboxyalkyl)aminoacid tert-butyl ester sodium salt. The equilibrium and the consecutive reactions were controlled by adding sodium cyanoborohydride using the artificial intelligence software, which contained novel kinetic equations [3] and substituent effects [4].Substitued N-(carboxyalkyl)amino-acid tert-butyl esters, 90 derivatives, were automatically synthesized using the computerassisted automated synthesis apparatus. The syntheses were performed unattended 24 hours a day, except for supplying the raw materials, reagents and solvents. The apparatus is extremely valuable for synthesizing many derivatives of a particular compound. The configurations of the products were determined by circular dichroism measurements. PMID:18924904

  3. Computer-assisted automated synthesis. III. Synthesis of substituted N-(carboxyalkyl) amino-acid tert-butyl ester derivatives

    PubMed Central

    Hayashi, Nobuyoshi; Sugawara, Tohru; Kato, Shinji

    1991-01-01

    A versatile automated synthesis apparatus, equipped with a chemical artificial intelligence, was developed to prepare and isolate a wide variety of compounds. The apparatus was to the synthesis of substituted N-(carboxyalkyl)amino-acids. The apparatus [1,2] is composed of units for performing various tasks,for example reagent supply, reaction, purification and separation, each linked to a control system. All synthetic processes, including washing and drying of the apparatus after each synthetic run, were automatically performed from the mixing of the reactants to the isolation of the products as powders or crystals. The reaction of an amino-acid tertbutyl ester acetic acid salt with a 2-keto acid sodium salt produces an unstable intermediate, Schiff base, which is reduced with sodum cyanoborohydride to give a substituted N-(carboxyalkyl)aminoacid tert-butyl ester sodium salt. The equilibrium and the consecutive reactions were controlled by adding sodium cyanoborohydride using the artificial intelligence software, which contained novel kinetic equations [3] and substituent effects [4]. Substitued N-(carboxyalkyl)amino-acid tert-butyl esters, 90 derivatives, were automatically synthesized using the computerassisted automated synthesis apparatus. The syntheses were performed unattended 24 hours a day, except for supplying the raw materials, reagents and solvents. The apparatus is extremely valuable for synthesizing many derivatives of a particular compound. The configurations of the products were determined by circular dichroism measurements. PMID:18924904

  4. Tert-butyl benzoquinone: mechanism of biofilm eradication and potential for use as a topical antibiofilm agent

    PubMed Central

    Ooi, N.; Eady, E. A.; Cove, J. H.; O'Neill, A. J.

    2016-01-01

    Objectives Tert-butyl benzoquinone (TBBQ) is the oxidation product of tert-butyl hydroquinone (TBHQ), an antimicrobial food additive with >40 years of safe use. TBBQ displays potent activity against Staphylococcus aureus biofilms in vitro. Here, we report on studies to further explore the action of TBBQ on staphylococcal biofilms, and provide a preliminary preclinical assessment of its potential for use as a topical treatment for staphylococcal infections involving a biofilm component. Methods The antibacterial properties of TBBQ were assessed against staphylococci growing in planktonic culture and as biofilms in the Calgary Biofilm Device. Established assays were employed to measure the effects of TBBQ on biofilm structure and bacterial membranes, and to assess resistance potential. A living-skin equivalent was used to evaluate the effects of TBBQ on human skin. Results TBBQ eradicated biofilms of S. aureus and other staphylococcal species at concentrations ≤64 mg/L. In contrast to other redox-active agents exhibiting activity against biofilms, TBBQ did not cause substantial destructuring of the biofilm matrix; instead, the antibiofilm activity of the compound was attributed to its ability to kill slow- and non-growing cells via membrane perturbation. TBBQ acted synergistically with gentamicin, did not damage a living-skin equivalent following topical application and exhibited low resistance potential. Conclusions The ability of TBBQ to eradicate biofilms appears to result from its ability to kill bacteria regardless of growth state. Preliminary evaluation suggests that TBBQ represents a promising candidate for development as a topical antibiofilm agent. PMID:27121399

  5. Inductive and steric effects on the gas-phase structure of tert-butyl acetate. Electron diffraction and ab initio MO investigations

    SciTech Connect

    Takeuchi, Hiroshi; Enmi, Jun-ichiro; Onozaki, Manabu; Egawa, Toru; Konaka, Shigehiro

    1994-09-01

    Gas electron diffusion and HF/4-21 G calculations on geometric parameters and harmonic force constants are used to study the molecular structure of tert-butyl acetate. This determined that C{sub 1} = O{sub 2} is (cis) to O{sub 4}-C{sub 5} and the tert-butyl group is staggered to the C{sub 1}-O{sub 4} bond. The structural parameters are also determined. C{sub 1}-O{sub 4} bond length shortening is rationalized in terms of the resonance effect and the electron-releasing inductive effect of substituents. 29 refs., 4 figs., 4 tabs.

  6. Mechanistic investigation of oxidative Mannich reaction with tert-butyl hydroperoxide. The role of transition metal salt.

    PubMed

    Ratnikov, Maxim O; Doyle, Michael P

    2013-01-30

    A general mechanism is proposed for transition metal-catalyzed oxidative Mannich reactions of N,N-dialkylanilines with tert-butyl hydroperoxide (TBHP) as the oxidant. The mechanism consists of a rate-determining single electron transfer (SET) that is uniform from 4-methoxy- to 4-cyano-N,N-dimethylanilines. The tert-butylperoxy radical is the major oxidant in the rate-determining SET step that is followed by competing backward SET and irreversible heterolytic cleavage of the carbon-hydrogen bond at the α-position to nitrogen. A second SET completes the conversion of N,N-dimethylaniline to an iminium ion that is subsequently trapped by the nucleophilic solvent or the oxidant prior to formation of the Mannich adduct. The general role of Rh(2)(cap)(4), RuCl(2)(PPh(3))(3), CuBr, FeCl(3), and Co(OAc)(2) in N,N-dialkylaniline oxidations by T-HYDRO is to initiate the conversion of TBHP to tert-butylperoxy radicals. A second pathway, involving O(2) as the oxidant, exists for copper, iron, and cobalt salts. Results from linear free-energy relationship (LFER) analyses, kinetic and product isotope effects (KIE and PIE), and radical trap experiments of N,N-dimethylaniline oxidation by T-HYDRO in the presence of transition metal catalysts are discussed. Kinetic studies of the oxidative Mannich reaction in methanol and toluene are also reported. PMID:23298175

  7. Photoinduced Reactivity of the Soft Hydrotris(6-tert-butyl-3-thiopyridazinyl)borate Scorpionate Ligand in Sodium, Potassium, and Thallium Salts.

    PubMed

    Tüchler, Michael; Belaj, Ferdinand; Raber, Georg; Neshchadin, Dmytro; Mösch-Zanetti, Nadia C

    2015-09-01

    The soft scorpionate ligand hydrotris(6-tert-butyl-3-thiopyridazinyl)borate (Tn) was found to exhibit pronounced photoreactivity. Full elucidation of this process revealed the formation of 6-tert-butylpyridazine-3-thione (PnH) and 4,5-dihydro-6-tert-butylpyridazine-3-thione (H2PnH). Under exclusion of light, no solvolytic reactions occur, allowing the development of high-yield preparation protocols for the sodium, potassium, and thallium salts and improving the yield for their derived copper boratrane complex. The photoreactivity is relevant for all future studies with electron-deficient scorpionate ligands. PMID:26260148

  8. Alkylation of 2'-deoxynucleosides and DNA by quinone methides derived from 2,6-di-tert-butyl-4-methylphenol.

    PubMed

    Lewis, M A; Yoerg, D G; Bolton, J L; Thompson, J A

    1996-12-01

    4-Alkylphenols, such as the antioxidant 2, 6-di-tert-butyl-4-methylphenol (BHT), exhibit toxicities that appear to be mediated by their oxidative metabolism to electrophilic quinone methides. Reactions of these Michael acceptors with simple nucleophiles and proteins have been reported, but little information is available on quinone methide binding to the competing nucleophilic sites in DNA. In the present investigation, 2'-deoxynucleoside adducts generated in vitro with two BHT-derived quinone methides, 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone and 6-tert-butyl-2- (2'-hydroxy-1',1'-dimethylethyl)-4-methylenecyclohexa-2,5-dieno ne (BHTOH-QM) were isolated and identified. Both quinone methides produced adducts at the 1- and N2-positions of deoxyguanosine (dG) and the N6-position of deoxyadenosine (dA). In addition, a labile adduct formed at the 7-position of dG, which degraded to the corresponding 7-alkylguanine derivative. Additional work was conducted with BHTOH-QM, the more reactive of the two quinone methides. This species also formed stable adducts at the N4-position of deoxycytosine (dC) and the 3-position of thymidine and formed a labile adduct at the 3-position of dC that underwent hydrolytic cleavage to regenerate dC. In mixtures of deoxynucleosides treated with [14C]BHTOH-QM, alkylation occurred primarily at the N2- and 7-positions of dG and the N6-position of dA and occurred secondarily at the 1-position of dG. Treatment of calf thymus DNA with this quinone methide yielded N6-dA and N2-dG adducts with the former predominating. The unstable 7-dG adduct was detected by analysis of the 7-alkylguanine product from depurination. These results demonstrate that quinone methides are most likely to damage DNA through alkylation of the exocyclic amino groups of purine residues and possibly also by attack at the 7-position of dG followed by depurination. PMID:8951242

  9. 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.

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

    PubMed

    You, Xun; Wang, Guan-Wu

    2014-01-01

    The rare oxazolidinofullerenes have been prepared by the ferric chloride-catalyzed reaction of [60]fullerene with various tert-butyl N-substituted carbamates via t-Bu-O bond cleavage and heteroannulation under mild conditions. A possible mechanism for the formation of oxazolidinofullerenes is proposed. PMID:24328055

  11. Conformations and Barriers to Methyl Group Internal Rotation in Two Asymmetric Ethers: Propyl Methyl Ether and Butyl Methyl Ether

    NASA Astrophysics Data System (ADS)

    Long, B. E.; Dechirico, F.; Cooke, S. A.

    2012-06-01

    The conformational preferences of the O-C-C-C unit are important in many biological systems with the unit generally preferring a gauche configuration compared to an anti configuration. Butyl methyl ether and propyl methyl ether provide very simple systems for this phenomenom to manifest. Pure rotational spectra of the title molecules have been recorded using chirped pulse Fourier transform microwave spectroscopy (CP-FTMW). In the case of butyl methyl ether, only one conformer has been observed. This conformer has torsional angles of COCC = 180°, OCCC = 62° and CCCC = 180° (anti-gauche-anti) and rotational constants of A = 10259.4591(33) MHz, B = 1445.6470(13) MHz, and C = 1356.2944(14) MHz. The rotational spectrum was doubled and has been analyzed to produce an effective barrier to methyl group internal rotation of 780(35) cm-1. A prior rotational spectroscopic study on propyl methyl ether had focused only on the high energy anti-anti conformer. We have analyzed spectra from the lowest energy anti-gauche conformer and the spectroscopic constants will be presented. A summary of the differences in conformational energies and methyl group internal rotation barriers for the class of aliphatic asymmetric ethers will be presented. K. N. Houk, J. E. Eksterowicz, Y.-D. Wu, C. D. Fuglesang, D. B. Mitchell. J. Am. Chem. Soc. 115 (4170), 1993. Hiroshi Kato, Jun Nakagawa, Michiro Hayashi. J. Mol. Spectrosc. 80 (272), 1980.

  12. Regulation of the unbalanced redox state in a Schizosaccharomyces pombe tert-butyl hydroperoxide-resistant mutant.

    PubMed

    Gazdag, Z; Kálmán, Nikoletta; Blaskó, Agnes; Virág, Eszter; Belágyi, J; Pesti, M

    2014-06-01

    The one-gene mutation in the tert-butyl hydroperoxide-resistant mutant hyd1-190 of the fission yeast Schizosaccharomyces pombe led to a 4-fold increase in resistance to t-BuOOH and decreased specific concentrations of superoxide and total thiols in comparison with the parental strain hyd+. It suggested an unbalanced redox state of the cells, which induced continuously increased specific activities of glutathione peroxidase, glutathione reductase and glutathione S-transferase and decreased activities of the antioxidant enzymes superoxide dismutases and glucose-6-phosphate dehydrogenase to regulate the redox balance of the mutation-induced permanent, low-level but tolerable internal stress. These results may contribute to the understanding of internal, oxidative stress-related human diseases. PMID:24873914

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

    PubMed

    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

  14. Preparation of N-tBoc L-glutathione dimethyl and di-tert-butyl esters: versatile synthetic building blocks.

    PubMed

    Falck, J R; Sangras, Bhavani; Capdevila, Jorge H

    2007-01-15

    The title l-glutathione derivatives, containing acid- and base-labile esters, respectively, were obtained in good overall yields. N-(t)Boc l-glutathione dimethyl ester was prepared via Fischer esterification of l-glutathione disulfide (GSSG) using HCl in dry methanol, protection of the amine with (t)Boc(2)O, and tributylphosphine cleavage of the disulfide in wet isopropanol. Alternatively, Fischer esterification and (t)Boc-protection of l-glutathione (GSH) also furnished N-(t)Boc glutathione dimethyl ester accompanied by a small amount of S-(t)Boc that was removed chromatographically. The di-tert-butyl ester was obtained by S-palmitoylation of GSH in TFA as solvent, N-(t)Boc-protection, esterification using (t)BuOH mediated by diisopropylcarbodiimide/copper(I) chloride, and saponification of the thioester. These l-glutathione derivatives are versatile synthetic building blocks for the preparation of S-glutathione adducts. PMID:17070060

  15. Ethyl tert-butyl ether (ETBE) synthesis on H-Mordenite: Gas-phase kinetics and DRIFTS studies

    SciTech Connect

    Larsen, G.; Lotero, E.; Marquez, M.

    1995-12-01

    The ethyl tert-butyl ether (ETBE) formation between 313 and 363 K over an H-mordenite catalyst was studied in a packed-bed flow catalytic reactor at atmospheric pressure. An activation energy of 82 kJ/mol and reaction orders in isobutene and ethanol of 0.8 and -0.8 were found. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was used to study the state of the catalyst under reaction conditions. The IR studies, coupled with the reaction kinetics information, are consistent with the idea that the stability of the H-mordenite catalyst requires the protective action of ethanol to prevent the occurrence of isobutene oligomerization products. The high ethanol concentrations found in the zeolite pores under the temperature and pressure conditions employed is also responsible for reaction inhibition. 27 refs., 13 figs., 1 tab.

  16. Photochemical transformations. 30. Photosolvolysis of benzyl chlorides in tert-butyl alcohol. 2. Nature of excited states

    SciTech Connect

    Cristol, S.J.; Bindel, T.H.

    1981-12-02

    The photosolvolysis of a number of benzyl chlorides in tert-butyl alcohol, both as a result of direct irradiation and ketone triplet sensitization, has been studied. A variety of sensitization and quenching techniques have been used. The results obtained are rationalized by the assumption that there are two triplet states of the benzyl chlorides accessible in these experiments-one a short-lived upper state, which leads to solvolysis product, and another a long-lived (lower energy) state, which reverts to ground-state reactant. Consistent with this idea, m-methoxybenzyl chloride is shown to quench the photoreactions of benzophenone with benzhydrol without the formation of a significant amount of reactive species. The effects of wavelength on the reactions of p-acetobenzyl chloride are measured and discussed in terms of the two-triplet concept.

  17. Isotetrandrine ameliorates tert-butyl hydroperoxide-induced oxidative stress through upregulation of heme oxygenase-1 expression.

    PubMed

    Wang, Lidong; Ci, Xinxin; Lv, Hongming; Wang, Xiaosong; Qin, F Xiaofeng; Cheng, Genhong

    2016-08-01

    1R, 1'S-isotetrandrine, a naturally occurring plant alkaloid found in Mahonia of Berberidaceae, possesses anti-inflammatory, antibacterial, and antiviral properties, but the antioxidative activity and mechanism action remain unclear. In this study, we demonstrated the antioxidative effect and mechanism of 1R, 1'S-isotetrandrine against tert-butyl hydroperoxide-induced oxidative damage in HepG2 cells. We found that 1R, 1'S-isotetrandrine suppressed cytotoxicity, reactive oxygen species generation, and glutathione depletion. Additionally, our study confirmed that 1R, 1'S-isotetrandrine significantly increased the antioxidant enzyme heme oxygenase-1 expression and nuclear translocation of factor-erythroid 2 p45-related factor 2 (Nrf2). Specifically, the nuclear translocation of Nrf2 induced by 1R, 1'S-isotetrandrine was associated with Nrf2 negative regulatory protein Keap1 inactivation and phosphorylation of both extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase. Preincubation with thiol-reducing agents reduced 1R, 1'S-isotetrandrine-induced heme oxygenase-1 expression, and treatment with either extracellular signal-regulated protein kinase or c-Jun NH2-terminal kinase inhibitors attenuated the levels of 1R, 1'S-isotetrandrine-induced Nrf2 activation and heme oxygenase-1 expression. Furthermore, the cytoprotective effect of 1R, 1'S-isotetrandrine was abolished by heme oxygenase-1, extracellular signal-regulated protein kinase, and c-Jun NH2-terminal kinase inhibitors. These results indicated that the 1R, 1'S-isotetrandrine ameliorated tert-butyl hydroperoxide-induced oxidative damage through upregulation of heme oxygenase-1 expression by the dissociation of Nrf2 from Nrf2-Keap1 complex via extracellular signal-regulated protein kinase and c-Jun NH2-terminal kinase activation and Keap1 inactivation. PMID:27190261

  18. N-Butyl-4-butyl­imino-2-methyl­pentan-2-aminium (E)-quercetinate

    PubMed Central

    Grosu, Ioana-Georgeta; Borodi, Gheorghe; Pop, Mihaela Maria

    2012-01-01

    The title salt, C14H31N2 +·C15H9O7 −, was obtained in the reaction of quercetin with n-butyl­amine in a mixture of acetone and hexane. The crystal structure determination shows that the quercetin donates one of its phenol H atoms to the N-butyl-4-butyl­imino-2-methyl­pentan-2-amine mol­ecule. The crystal structure of the salt is stabilized by intramolecular (N—H⋯N for the cation and O—H⋯O for the anion) and intermolecular hydrogen bonding (N—H⋯O between cation–anion pairs and O—H⋯O between anions). Quercetin molecules form dimers connected into a two-dimensional network. The dihedral angle between the quercetin ring systems is 19.61 (8)°. PMID:22904895

  19. A combination of TERT promoter mutation and MGMT methylation status predicts clinically relevant subgroups of newly diagnosed glioblastomas.

    PubMed

    Arita, Hideyuki; Yamasaki, Kai; Matsushita, Yuko; Nakamura, Taishi; Shimokawa, Asanao; Takami, Hirokazu; Tanaka, Shota; Mukasa, Akitake; Shirahata, Mitsuaki; Shimizu, Saki; Suzuki, Kaori; Saito, Kuniaki; Kobayashi, Keiichi; Higuchi, Fumi; Uzuka, Takeo; Otani, Ryohei; Tamura, Kaoru; Sumita, Kazutaka; Ohno, Makoto; Miyakita, Yasuji; Kagawa, Naoki; Hashimoto, Naoya; Hatae, Ryusuke; Yoshimoto, Koji; Shinojima, Naoki; Nakamura, Hideo; Kanemura, Yonehiro; Okita, Yoshiko; Kinoshita, Manabu; Ishibashi, Kenichi; Shofuda, Tomoko; Kodama, Yoshinori; Mori, Kanji; Tomogane, Yusuke; Fukai, Junya; Fujita, Koji; Terakawa, Yuzo; Tsuyuguchi, Naohiro; Moriuchi, Shusuke; Nonaka, Masahiro; Suzuki, Hiroyoshi; Shibuya, Makoto; Maehara, Taketoshi; Saito, Nobuhito; Nagane, Motoo; Kawahara, Nobutaka; Ueki, Keisuke; Yoshimine, Toshiki; Miyaoka, Etsuo; Nishikawa, Ryo; Komori, Takashi; Narita, Yoshitaka; Ichimura, Koichi

    2016-01-01

    The prognostic impact of TERT mutations has been controversial in IDH-wild tumors, particularly in glioblastomas (GBM). The controversy may be attributable to presence of potential confounding factors such as MGMT methylation status or patients' treatment. This study aimed to evaluate the impact of TERT status on patient outcome in association with various factors in a large series of adult diffuse gliomas. We analyzed a total of 951 adult diffuse gliomas from two cohorts (Cohort 1, n = 758; Cohort 2, n = 193) for IDH1/2, 1p/19q, and TERT promoter status. The combined IDH/TERT classification divided Cohort 1 into four molecular groups with distinct outcomes. The overall survival (OS) was the shortest in IDH wild-type/TERT mutated groups, which mostly consisted of GBMs (P < 0.0001). To investigate the association between TERT mutations and MGMT methylation on survival of patients with GBM, samples from a combined cohort of 453 IDH-wild-type GBM cases treated with radiation and temozolomide were analyzed. A multivariate Cox regression model revealed that the interaction between TERT and MGMT was significant for OS (P = 0.0064). Compared with TERT mutant-MGMT unmethylated GBMs, the hazard ratio (HR) for OS incorporating the interaction was the lowest in the TERT mutant-MGMT methylated GBM (HR, 0.266), followed by the TERT wild-type-MGMT methylated (HR, 0.317) and the TERT wild-type-MGMT unmethylated GBMs (HR, 0.542). Thus, patients with TERT mutant-MGMT unmethylated GBM have the poorest prognosis. Our findings suggest that a combination of IDH, TERT, and MGMT refines the classification of grade II-IV diffuse gliomas. PMID:27503138

  20. Crystal structure of trans-N,N'-bis-(3,5-di-tert-butyl-2-hy-droxy-phen-yl)oxamide methanol monosolvate.

    PubMed

    Velázquez-Carmona, Miguel-Ángel; Bernès, Sylvain; Ríos-Merino, Francisco Javier; Reyes Ortega, Yasmi

    2016-07-01

    The here crystallized oxamide was previously characterized as an unsolvated species [Jímenez-Pérez et al. (2000 ▸). J. Organomet. Chem. 614-615, 283-293], and is now reported with methanol as a solvent of crystallization, C30H44N2O4·CH3OH, in a different space group. The introduction of the solvent influences neither the mol-ecular symmetry of the oxamide, which remains centrosymmetric, nor the mol-ecular conformation. However, the unsolvated mol-ecule crystallized as an ordered system, while many parts of the solvated crystal are disordered. The hy-droxy group in the oxamide is disordered over two chemically equivalent positions, with occupancies 0.696 (4):0.304 (4); one tert-butyl group is disordered by rotation about the C-C bond, and was modelled with three sites for each methyl group, each one with occupancy 1/3. Finally, the methanol solvent, which lies on a twofold axis, is disordered by symmetry. The disorder affecting hy-droxy groups and the solvent of crystallization allows the formation of numerous supra-molecular motifs using four hydrogen bonds, with N-H and O-H groups as donors and the oxamide and methanol mol-ecule as acceptors. PMID:27555931

  1. Crystal structure of trans-N,N′-bis­(3,5-di-tert-butyl-2-hy­droxy­phen­yl)oxamide methanol monosolvate

    PubMed Central

    Velázquez-Carmona, Miguel-Ángel; Bernès, Sylvain; Ríos-Merino, Francisco Javier; Reyes Ortega, Yasmi

    2016-01-01

    The here crystallized oxamide was previously characterized as an unsolvated species [Jímenez-Pérez et al. (2000 ▸). J. Organomet. Chem. 614–615, 283–293], and is now reported with methanol as a solvent of crystallization, C30H44N2O4·CH3OH, in a different space group. The introduction of the solvent influences neither the mol­ecular symmetry of the oxamide, which remains centrosymmetric, nor the mol­ecular conformation. However, the unsolvated mol­ecule crystallized as an ordered system, while many parts of the solvated crystal are disordered. The hy­droxy group in the oxamide is disordered over two chemically equivalent positions, with occupancies 0.696 (4):0.304 (4); one tert-butyl group is disordered by rotation about the C—C bond, and was modelled with three sites for each methyl group, each one with occupancy 1/3. Finally, the methanol solvent, which lies on a twofold axis, is disordered by symmetry. The disorder affecting hy­droxy groups and the solvent of crystallization allows the formation of numerous supra­molecular motifs using four hydrogen bonds, with N—H and O—H groups as donors and the oxamide and methanol mol­ecule as acceptors. PMID:27555931

  2. 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

  3. ESR characterization of a novel spin-trapping agent, 15N-labeled N-tert-butyl-alpha-phenylnitrone, as a nitric oxide donor.

    PubMed

    Saito, Kieko; Yoshioka, Hisashi

    2002-10-01

    We previously found that one of the pharmacological effects of N-tert-butyl-alpha-phenylnitrone (PBN) is the release of nitric oxide (NO) under oxidative conditions. However, to confirm this hypothesis in vivo, NO released from PBN must be distinguished from NO produced in biological systems, and therefore we undertook the synthesis of PBN using labeled 15N to identify its corresponding 15NO in vivo. The properties were examined with an ESR spectrometer. To synthesize 15N-PBN, the starting material, ammonium-15N chloride, was converted to 2-amino-15N-2-methylpropane, oxidized to 2-methyl-2-nitropropane-15N, and finally reacted with benzaldehyde to give 15N-PBN. The final product was purified by repeated sublimation. With ferrous sulfate-methyl glucamine dithiocarbamate complex, Fe (MGD)2, as a trapping agent to measure the NO levels of 15N-PBN or 14N-PBN in vitro, the peak intensity of 15NO[Fe(MGD)2] was over 50% stronger than that of 14NO[Fe(MGD)2], and that 15NO and 14NO had the corresponding two-and three line hyperfine structures due to their nuclear spin quantum numbers. Subsequently, the ESR spectrum of 15NO derived from 15N-PBN was significantly different than that of lipopolysaccharide (LPS)-induced NO, which was derived from biological cells, and therefore we have demonstrated the possibility to distinguish 15NO from PBN and 14NO generated from cells. These results suggested that 15N-PBN is a useful molecule, not only as a spin-trapping agent, but also as an NO donor to explore the pharmacological mechanisms of PBN in vivo. PMID:12450131

  4. One Step Continuous Flow Synthesis of Highly Substituted Pyrrole-3-Carboxylic Acid Derivatives via in situ Hydrolysis of tert-Butyl Esters

    PubMed Central

    Herath, Ananda; Cosford, Nicholas D. P.

    2010-01-01

    The first one-step, continuous flow synthesis of pyrrole-3-carboxylic acids directly from tert-butyl acetoacetates, amines and 2-bromoketones is reported. The HBr generated as a by-product in the Hantzsch reaction was utilized in the flow method to saponify the t-butyl esters in situ to provide the corresponding acids in a single microreactor. The protocol was used in the multistep synthesis of pyrrole-3-carboxamides, including two CB1 inverse agonists, directly from commercially available starting materials in a single continuous process. PMID:20964284

  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. tert-Butyl 3-oxo-2-oxa-5-aza­bicyclo­[2.2.1]heptane-5-carboxyl­ate

    PubMed Central

    Lechner, Marie-Charlotte; Aubert, Emmanuel; Guichard, Gilles; Didierjean, Claude

    2008-01-01

    The title compound, C10H15NO4, also known as N-tert-butyl­oxycarbonyl-allohydr­oxy-l-proline lactone, is quite similar to N-acetyl-allohydr­oxy-l-proline lactone [Lenstra, Petit & Geise (1979 ▶). Cryst. Struct. Commun. 8, 1023–1029], whereby both carbonyl groups point roughly in the same direction because of the trans conformation of the peptide bond. PMID:21201231

  7. Formal [4+2] cycloaddition of di-tert-butyl 2-ethoxycyclobutane-1,1-dicarboxylate with ketones or aldehydes and tandem lactonization.

    PubMed

    Okado, Ryohei; Nowaki, Aya; Matsuo, Jun-Ichi; Ishibashi, Hiroyuki

    2012-01-01

    A catalytic amount of tin(IV) chloride catalyzed formal [4+2] cycloaddition reaction of di-tert-butyl 2-ethoxycyclobutane-1,1-carboxylate with ketones or aldehydes to give diethyl 6-ethoxydihydro-2H-pyran-3,3(4H)-dicarboxylates, whereas two equivalents of trimethylsilyl triflate promoted tandem [4+2] cycloaddition and lactonization to afford 3-oxo-2,6-dioxabicyclo[2.2.2]octane-4-carboxylate esters. PMID:22223370

  8. Contents of methyl-, ethyl-, propyl-, butyl- and benzylparaben in cosmetic products.

    PubMed

    Rastogi, S C; Schouten, A; de Kruijf, N; Weijland, J W

    1995-01-01

    The contents of methyl-, ethyl-, propyl-, butyl- and benzylparaben in 215 cosmetic products have been determined to elucidate the concentration and frequency of use of these parabens in cosmetic products, and to monitor whether the products complied with the Danish and EEC regulations. The results showed that 77% of the products investigated contained 0.01%-0.87% parabens. Nearly all (99%) of the leave-on cosmetics and 77% of rinse-off cosmetics were found to contain parabens. A maximum of 0.32% methyl- and propylparaben, 0.19% ethylparaben, and 0.07% butyl- and benzylparaben were present in paraben-positive cosmetics. A preferential use of methyl-/ethyl-/propyl-/butyl-/benzylparaben in various groups of cosmetic products was revealed. PMID:7720367

  9. 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

  10. Liquid phase oxidation of thiophene compounds by tert-butyl hydroperoxide

    SciTech Connect

    Mushrush, G.W.; Watkins, J.M. Jr.; Hazlett, R.N.; Hardy, D.R.; Eaton, H.G. )

    1987-08-01

    Oxidative instability problems in both shale and petroleum-derived middle distillate fuels are related to the presence of hydroperoxides. Although a good body of knowledge exists concerning the formation of peroxides in the liquid phase, relatively little is known about the reaction/decomposition pathways when other functional groups are present. One of the significant and undesirable problems is the formation of solid deposits which can plug nozzles and filters and coal heat exchanger surfaces. Deposit formation in fuels is triggered by autoxidation reactions and is closely associated with elemental oxygen and/or hydroperoxide concentration. This paper reports on the reaction between a primary autoxidation product, a hydroperoxide, and sulfur compounds of the type present in petroleum-derived middle distillate fuels. Specifically, we examine the t-butyl hydroperoxide oxidation of thiophene, 2, 5-dimethylthiophene, tetrahydrothiophene and benzothiophene in a deaerated model fuel, tetradecane, at 120{degree}C.

  11. 2-(3-aryl-3-oxopropen-1-yl)-9-tert-butyl-paullones: a new antileishmanial chemotype.

    PubMed

    Reichwald, Christina; Shimony, Orly; Dunkel, Ute; Sacerdoti-Sierra, Nina; Jaffe, Charles L; Kunick, Conrad

    2008-02-14

    A screening program directed to find new agents against Leishmania donovani, the parasite causing visceral leishmaniasis, revealed that paullones attenuate the proliferation of axenic amastigotes. Because these structures were not active in a test system involving infected macrophages, a structure optimization campaign was carried out. Concomitant introduction of an unsaturated side chain into the 2-position and a tert-butyl substituent into the 9-position of the parent scaffold led to compounds inhibiting also parasites dwelling in macrophages. By inclusion of the so elaborated scaffold into a chalcone substructure, the toxicity against uninfected host cells was significantly reduced. For the synthesis of this new compound class, a novel modification of the Heck-type palladium-catalyzed C,C-cross coupling strategy was used, employing a ketone Mannich base as precursor for the alkene reactant. The so-prepared compounds exhibited improved antileishmanial activity both on axenic amastigotes (GI50 < 1 microM) as well as on parasites in infected macrophages. PMID:18186603

  12. Mercury(II) ion-selective electrodes based on p-tert-butyl calix[4]crowns with imine units.

    PubMed

    Mahajan, Rakesh Kumar; Kaur, Ravneet; Kaur, Inderpreet; Sharma, Vandana; Kumar, Manoj

    2004-05-01

    A PVC membrane incorporating p-tert-butyl calix[4]crown with imine units as an ionophore was prepared and used in an ion-selective electrode for the determination of mercury(II) ions. An electrode based on this ionophore showed a good potentiometric response for mercury(II) ions over a wide concentration range of 5.0 x 10(-5) - 1.0 x 10(-1) M with a near-Nernstian slope of 27.3 mV per decade. The detection limit of the electrode was 2.24 x 10(-5) M and the electrode worked well in the pH range of 1.3 - 4.0. The electrode showed a short response time of less than 20 s. The electrode also showed better selectivity for mercury(II) ions over many of the alkali (Na+, -1.69; K+, -1.54), alkaline-earth (Ca2+, -3.30; Ba2+, -3.32), and heavy metal ions (Co2+, -3.67; Ni2+, -3.43; Pb2+, -3.31; Fe3+, -1.82). Ag+ ion was found to be the strongest interfering ion. Also, sharp end points were obtained when the sensor was used as an indicator electrode for the potentiometric titration of mercury(II) ions with iodide and dichromate ions. PMID:15171285

  13. Synthesis and characterization of perfluoro-tert-butyl semifluorinated amphiphilic polymers and their potential application in hydrophobic drug delivery

    PubMed Central

    Decato, Sarah; Bemis, Troy; Madsen, Eric; Mecozzi, Sandro

    2014-01-01

    Semifluorinated polymer surfactants, composed of a monomethyl poly(ethylene glycol) (mPEG) hydrophilic head group and either 1, 2, or 3 perfluoro-tert-butyl (PFtB) groups as the fluorophilic tail, were synthesized, and their aqueous self-assemblies were investigated as a potential design for theranostic nanoparticles. Polymers with three PFtB groups (PFtBTRI) solely formed stable, spherical micelles, approximately 12 nm in size. These PFtBTRI surfactants demonstrate similar characteristics with those of polymers with linear perfluorocarbon tails, despite large differences in tail structure. For example, PFtB polymer solutions stably emulsified 20 v/v% sevoflurane with perfluorooctyl bromide (PFOB) as a stabilizer. However, these PFtB polymers have the additional potential to serve as F-MRI contrast agents. PFtBTRI micelles gave one narrow 19F-NMR signal in D2O, with T1 and T2 parameters of approximately 500 and 100 ms, respectively. 19F-MR images of PFtB polymer solutions at 1 mM gave intense signal at 4.7 T without sensitizers or selective excitation sequences. These preliminary data demonstrate the potential of PFtB polymers as a basic design, which can be further modified to serve as dual drug-delivery and imaging vehicles. PMID:25383100

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

    PubMed

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

    2015-10-15

    The volatile organic compound 2,4-di-tert-butyl phenol (2,4 DTBP) was purified from the cell free supernatant of a newly isolated Lactococcus sp. by solvent extraction and chromatographic techniques. Molecular characterization of the compound by ESI-MS, (1)H NMR and FTIR analysis revealed the structure, C14H22O. Fungicidal activity was demonstrated against Aspergillus niger, Fusarium oxysporum and Penicillium chrysogenum by disc diffusion assay. Among the cell lines tested for cytotoxicity of this compound (normal cell line H9c2 and cancer cell lines HeLa and MCF-7), a remarkable cytotoxicity against HeLa cells with an IC50 value of 10 μg/mL was shown. A biocontrol experiment with 2,4 DTBP supplemented fraction prevented growth of the abovementioned fungi on wheat grains. The study further strengthens the case for development of biopreservatives and dietary antioxidants from lactic acid bacteria for food applications. PMID:26164257

  16. 4-(Tert-butyl)-2,6-bis(1-phenylethyl)phenol induces pro-apoptotic activity

    PubMed Central

    Kim, Jun Ho; Lee, Yunmi

    2016-01-01

    Previously, we found that KTH-13 isolated from the butanol fraction of Cordyceps bassiana (Cb-BF) displayed anti-cancer activity. To improve its antiproliferative activity and production yield, we employed a total synthetic approach and derivatized KTH-13 to obtain chemical analogs. In this study, one KTH-13 derivative, 4-(tert-butyl)-2,6-bis(1-phenylethyl)phenol (KTH-13-t-Bu), was selected to test its anti-cancer activity. KTH-13-t-Bu diminished the proliferation of C6 glioma, MDA-MB-231, LoVo, and HCT-15 cells. KTH-13-t-Bu induced morphological changes in C6 glioma cells in a dose-dependent manner. KTH-13-t-Bu also increased the level of early apoptotic cells stained with annexin V-FITC. Furthermore, KTH-13-t-Bu increased the levels of cleaved caspase-3 and -9. In contrast, KTH-13-t-Bu upregulated the levels of pro- and cleaved forms of caspase-3, -8, and -9 and Bcl-2. Phospho-STAT3, phospho-Src, and phospho-AKT levels were also diminished by KTH13-t-Bu treatment. Therefore, these results strongly suggest that KTH-13-t-Bu can be considered a novel anti-cancer drug displaying pro-apoptotic activity. PMID:27162479

  17. 4-(Tert-butyl)-2,6-bis(1-phenylethyl)phenol induces pro-apoptotic activity.

    PubMed

    Kim, Jun Ho; Lee, Yunmi; Kim, Mi-Yeon; Cho, Jae Youl

    2016-05-01

    Previously, we found that KTH-13 isolated from the butanol fraction of Cordyceps bassiana (Cb-BF) displayed anti-cancer activity. To improve its antiproliferative activity and production yield, we employed a total synthetic approach and derivatized KTH-13 to obtain chemical analogs. In this study, one KTH-13 derivative, 4-(tert-butyl)-2,6-bis(1-phenylethyl)phenol (KTH-13-t-Bu), was selected to test its anti-cancer activity. KTH-13-t-Bu diminished the proliferation of C6 glioma, MDA-MB-231, LoVo, and HCT-15 cells. KTH-13-t-Bu induced morphological changes in C6 glioma cells in a dose-dependent manner. KTH-13-t-Bu also increased the level of early apoptotic cells stained with annexin V-FITC. Furthermore, KTH-13-t-Bu increased the levels of cleaved caspase-3 and -9. In contrast, KTH-13-t-Bu upregulated the levels of pro- and cleaved forms of caspase-3, -8, and -9 and Bcl-2. Phospho-STAT3, phospho-Src, and phospho-AKT levels were also diminished by KTH13-t-Bu treatment. Therefore, these results strongly suggest that KTH-13-t-Bu can be considered a novel anti-cancer drug displaying pro-apoptotic activity. PMID:27162479

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

    SciTech Connect

    Varshney, S.K. ); Gao, Z. . Research Dept.); Zhong, Xing Fu; Eisenberg, A. . 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.

  19. 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

  20. Mechanism of induction of oxidative stress in liver mitochondria by low concentrations of tert-butyl hydroperoxide.

    PubMed

    Fedotcheva, N I; Mokhova, E N

    2013-01-01

    The mechanism of the effect of tert-butyl hydroperoxide (tBHP) on the kinetics of decrease in liver mitochondrial ΔΨ (transmembrane electric potential) in response to successive additions of tBHP in low concentrations has been studied. FeSO(4) was found to increase significantly the damaging effect of tBHP; this effect was shown to increase in the presence of low concentrations of Ca2+ starting from 2 µM CaCl(2). Cyclosporin A prevents these effects. The data show that the damaging effect of low concentrations of tBHP in the course of pyruvate oxidation in isolated liver mitochondria is caused by the opening of the nonspecific Ca2+-dependent cyclosporin A-sensitive pore in the inner mitochondrial membrane. Application of a method of studying oxidative stress regulators, developed in this work, is illustrated by an example of the prooxidant action of ascorbate. This method is proposed for studying mitochondria in hemochromatosis, a pathology caused by excessive accumulation of iron. PMID:23379562

  1. Temperature dependence of the rate and activation parameters for tert-butyl chloride solvolysis: Monte Carlo simulation of confidence intervals

    NASA Astrophysics Data System (ADS)

    Sung, Dae Dong; Kim, Jong-Youl; Lee, Ikchoon; Chung, Sung Sik; Park, Kwon Ha

    2004-07-01

    The solvolysis rate constants ( kobs) of tert-butyl chloride are measured in 20%(v/v) 2-PrOH-H 2O mixture at 15 temperatures ranging from 0 to 39 °C. Examination of the temperature dependence of the rate constants by the weighted least squares fitting to two to four terms equations has led to the three-term form, ln kobs= a1+ a2T-1+ a3ln T, as the best expression. The activation parameters, ΔH ‡ and ΔS ‡, calculated by using three constants a1, a2 and a3 revealed the steady decrease of ≈1 kJ mol -1 per degree and 3.5 J K -1 mol -1 per degree, respectively, as the temperature rises. The sign change of ΔS ‡ at ≈20.0 °C and the large negative heat capacity of activation, ΔC p‡=-1020 J K -1 mol -1, derived are interpreted to indicate an S N1 mechanism and a net change from water structure breaking to electrostrictive solvation due to the partially ionic transition state. Confidence intervals estimated by the Monte Carlo method are far more precise than those by the conventional method.

  2. Syntheses, properties, and reactions of transition metal complexes of di(tert-butyl)amide and 2,2,6,6-tetramethylpiperidide

    NASA Astrophysics Data System (ADS)

    Davis, Luke M.

    nitride. The XPS binding energies confirm that the nitrogen is present as nitride in all cases. The M:N ratio in the deposited films decreases from Mn (2.5) to Fe (4) to Co (4.6-6) to Ni (9). Carbon contamination in the films is minimal for the manganese, iron, and cobalt nitride films, but similar to the nitrogen content in the nickel nitride films. Comparing the growth onset temperatures with the decomposition temperatures of the compounds M(NH2)2 supports the intermediacy in the film growth of the latter species, which are the expected products of the transamination of M[N(t-Bu)2]2 compounds with NH3. Treatment of MnBr2(thf)2, FeBr2(dme), and CoBr2(dme) with two equivalents of lithium 2,2,6,6-tetramethylpiperidide, Li(tmp), in pentane, followed by sublimation in static vacuum, affords the new compounds M(tmp)2 (M = Mn, Fe, Co). The heteroleptic, dinuclear three-coordinate compounds Fe2(tmp)3(OEt) and [Li(dme)][CoBr(tmp)2] have also been isolated. Crystallographic studies of Fe(tmp)2 demonstrate that the tmp ligand, which is the cyclic analogue of di(tert-butyl)amide with a slightly compressed C-N-C angle, can also enforce two-coordination. The Fe-N bonds are similar to those in the linear compound Fe[N(t-Bu)2]2, although the N-Fe-N angle of 173° and ligand dihedral angle of 73° are smaller. Fe(tmp)2 might therefore be expected to have a less degenerate ground state. Treatment of TiCl4 with two equivalents of H(tmp) affords the new compound Ti2Cl6(tmp)2. In contrast, treatment of TiCl4 or TiCl4(thf)2 with three equivalents of Li(tmp) induces ring-opening dealkylation of one tmp ligand and formation of a 1,1,5-trimethyl-5-hexenylimido ligand. A similar reaction is known for the di(tert-butyl)amido ligand.We conclude that the synthesis of early transition metal tmp and di(tert-butyl)amide compounds is hampered by the high electropositivity of these metals, which activates the methyl protons towards gamma-deprotonation. (Abstract shortened by UMI.).

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

    SciTech Connect

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

    2014-10-15

    Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH{sub 3}-TPD and N{sub 2} 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 SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 still have good mesoporous structure and long range ordering. Compared with the Zr (or Al)–MCM-48 samples, SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO{sub 4}{sup 2−}/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{sup −1} and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO{sub 4}{sup 2−}/Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO{sub 4}{sup 2−}/Zr-MCM-48-25.

  4. Butylate

    Integrated Risk Information System (IRIS)

    Butylate ; CASRN 2008 - 41 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects

  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. 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...

  7. 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...

  8. 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.

  9. PHYSIOLOGICALLY BASED PHARMACOKINETIC MODEL FOR HUMAN EXPOSURES TO METHYL TERTIARY-BUTYL ETHER

    EPA Science Inventory

    Humans can be exposed by inhalation, ingestion, or dermal absorption to methyl tertiary-butyl ether (MTBE), an oxygenated fuel additive, from contaminated water sources. The purpose of this research was to develop a physiologically based pharmacokinetic model describing in human...

  10. 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...

  11. alpha-Phenyl-n-tert-butyl-nitrone attenuates hypoxic-ischemic white matter injury in the neonatal rat brain.

    PubMed

    Lin, Shuying; Rhodes, Philip G; Lei, Manping; Zhang, Feng; Cai, Zhengwei

    2004-05-01

    White matter of the neonatal brain is highly sensitive to hypoxic-ischemic insult. The susceptibility of premature oligodendrocytes (OLs) to free radicals (FRs) produced during hypoxia-ischemia (HI) has been proposed as one of the mechanisms involved. To test this hypothesis, and to further investigate if the FR scavenger alpha-phenyl-N-tert-butyl-nitrone (PBN) attenuates hypoxic-ischemic white matter damage (WMD), postnatal day 4 (P4) SD rats were subjected to bilateral common carotid artery ligation (BCAL), followed by 8% oxygen exposure for 20 min. Pathological changes were evaluated on P6 and P9, 2 and 5 days after the HI insult. HI caused severe WMD including rarefaction, necrosis and cavity formation in the corpus callosum, external and internal capsule areas. OL injury was evidenced by degeneration of O4 positive OLs on P6. Disrupted myelination was verified by decreased immunostaining of myelin basic protein (MBP) on P9. Axonal injury was demonstrated by increased amyloid precursor protein (APP) immunostaining on both P6 and P9. Two lipid peroxidation end products, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), showed a one-fold elevation within 1-24 h following HI. 4-HNE immunostaining was found to specifically localize in the white matter area. Furthermore, pyknotic O4+ OLs were double-labeled with 4-HNE. These findings suggest that FRs are involved in the pathogenesis of neonatal WMD. PBN (100 mg/kg, i.p.) treatment alleviated the pathological changes of WMD following HI. It improved the survival of O4 positive OLs, attenuated hypomyelination and reduced axonal damage. PBN treatment also decreased the brain concentration of MDA/4-HNE and positive 4-HNE staining in the white matter area. These findings indicate that in the current WMD model, PBN protects both OLs and axons, the two main components in the white matter, from neonatal HI insult. FR scavenging appears to be the primary mechanism underlying its neuroprotective effect. PMID:15064144

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

    PubMed

    Yeh, S Y

    1999-03-01

    The present study examined the effect of N-tert-butyl-alpha-phenylnitrone (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 temperature was measured prior to and hourly following the drug injection for 5 h. Monoamine levels in the tissue were measured by HPLC. Density of the 5-HT transporters was assayed by [3H]paroxetine binding. Rectal temperature of rats increased after MDMA, decreased after PBN, ethanol, PBN plus ethanol, and MDMA plus ethanol, and was not significantly altered after MDMA plus PBN. Levels of 5-HT and 5-HIAA in the frontal cortex, hippocampus, striatum, and brain stem of rats decreased significantly after MDMA or MDMA plus ethanol, but not after MDMA plus PBN, PBN plus ethanol (PBN dissolved in ethanol), or ethanol as compared to the saline controls. Levels of 5-HT and 5-HIAA in the brain tissues of rats treated with MDMA plus PBN were elevated as compared to those treated with MDMA plus saline. Similar results were observed in the density of 5-HT transporters in the frontal cortex and hippocampus. These results indicate that scavenging of free radicals of MDMA metabolites or reactive oxygen species by PBN and with lowering of body temperature protected against MDMA-induced depletion of serotonin transmitter. PMID:10029234

  13. tert-Butyl 6-bromo-1,4-dimethyl-9H-carbazole-9-carboxyl­ate

    PubMed Central

    Lohier, Jean-François; Caruso, Anna; Sopková-de Oliveira Santos, Jana; Lancelot, Jean-Charles; Rault, Sylvain

    2010-01-01

    The title compound, C19H20BrNO2, consists of a carbazole skeleton with methyl groups at positions 1 and 4, a protecting group located at the N atom and a Br atom at position 6. The pyrrole ring is oriented at dihedral angles of 1.27 (7) and 4.86 (7)° with respect to the adjacent benzene rings. The dihedral angle between the benzene rings is 5.11 (7). The crystal structure is determined mainly by intra­molecular C—H⋯O and inter­molecular π–π inter­actions. π-stacking between adjacent molecules forms columns with a parallel arrangement of the carbazole ring systems. The presence of the tert-but­oxy­carbonyl group on the carbazole N atom and the intra­molecular hydrogen bond induce a particular conformation of the exocyclic N—C bond within the mol­ecule. PMID:21588291

  14. Preparation of 5-Aryl-2-Alkyltetrazoles with Aromatic Aldehydes, Alkylhydrazine, Di-tert-butyl Azodicarboxylate, and [Bis(trifluoroacetoxy)iodo]benzene.

    PubMed

    Imai, Taro; Harigae, Ryo; Moriyama, Katsuhiko; Togo, Hideo

    2016-05-01

    A variety of 5-aryl-2-methyltetrazoles and 5-aryl-2-benzyltetrazoles were directly prepared in good to moderate yields by the reaction of aromatic aldehydes with methylhydrazine and benzylhydrazine, followed by treatment with di-tert-butyl azodicarboxylate and [bis(trifluoroacetoxy)iodo]benzene in a mixture of dichloromethane and 2,2,2-trifluoroethanol at room temperature. The present method is a novel one-pot preparation of 5-aryl-2-methyltetrazoles and 5-aryl-2-benzyltetrazoles through a [2N + 2N] combination under transition metal-free and mild conditions. PMID:27078200

  15. 1,1,4,4-Tetra-tert-butyl-1,4-dichloro-2,2,3,3-tetra-phenyl-tetra-silane.

    PubMed

    Otsuka, Kyohei; Ishida, Shintaro; Kyushin, Soichiro

    2012-02-01

    The title compound, C(40)H(56)Cl(2)Si(4), was synthesized by the coupling of 1,1-di-tert-butyl-1,2-dichloro-2,2-diphenyl-disilane with lithium. The asymmetric unit contains one half-mol-ecule, which is completed by an inversion centre. In the mol-ecule, the tetra-silane skeleton adopts a perfect anti conformation and the Si-Si bonds [2.4355 (5) and 2.4328 (7) Å] are longer than the standard Si-Si bond length (2.34 Å). The Si-Si-Si angle [116.09 (2)°] is larger than the tetra-hedral bond angle (109.5°). These long bond lengths and the wide angle are favorable for reducing the steric hindrance among the tert-butyl and the phenyl groups. The dihedral angle between the phenyl rings in the asymmetric unit is 37.36 (8)°. PMID:22347038

  16. 1,1,4,4-Tetra-tert-butyl-1,4-dichloro-2,2,3,3-tetra­phenyl­tetra­silane

    PubMed Central

    Otsuka, Kyohei; Ishida, Shintaro; Kyushin, Soichiro

    2012-01-01

    The title compound, C40H56Cl2Si4, was synthesized by the coupling of 1,1-di-tert-butyl-1,2-dichloro-2,2-diphenyl­disilane with lithium. The asymmetric unit contains one half-mol­ecule, which is completed by an inversion centre. In the mol­ecule, the tetra­silane skeleton adopts a perfect anti conformation and the Si—Si bonds [2.4355 (5) and 2.4328 (7) Å] are longer than the standard Si—Si bond length (2.34 Å). The Si—Si—Si angle [116.09 (2)°] is larger than the tetra­hedral bond angle (109.5°). These long bond lengths and the wide angle are favorable for reducing the steric hindrance among the tert-butyl and the phenyl groups. The dihedral angle between the phenyl rings in the asymmetric unit is 37.36 (8)°. PMID:22347038

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

    PubMed Central

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

    2013-01-01

    The possible protective effects of an aqueous rooibos extract (Aspalathus linearis), red palm oil (RPO) (Elaeis guineensis), or their combination on tert-butyl-hydroperoxide-(t-BHP-)induced oxidative hepatotoxicity in Wistar rats were investigated. tert-butyl hydroperoxide caused a significant (P < 0.05) elevation in conjugated dienes (CD) and malondialdehyde (MDA) levels, significantly (P < 0.05) decreased reduced glutathione (GSH) and GSH : GSSG ratio, and induced varying changes in activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase in the blood and liver. This apparent oxidative injury was associated with histopathological changes in liver architecture and elevated levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH). Supplementation with rooibos, RPO, or their combination significantly (P < 0.05) decreased CD and MDA levels in the liver and reduced serum level of ALT, AST, and LDH. Likewise, changes observed in the activities of antioxidant enzymes and impairment in redox status in the erythrocytes and liver were reversed. The observed protective effects when rooibos and RPO were supplemented concomitantly were neither additive nor synergistic. Our results suggested that rooibos and RPO, either supplemented alone or combined, are capable of alleviating t-BHP-induced oxidative hepatotoxicity, and the mechanism of this protection may involve inhibition of lipid peroxidation and modulation of antioxidants enzymes and glutathione status. PMID:23690869

  18. Demethylation of 5,n-di-tert-butyl-8,n-dimethoxy[2.n]metacyclophane-1-ynes with BBr3 to afford novel [n]benzofuranophanes

    NASA Astrophysics Data System (ADS)

    Akther, Thamina; Islam, Md Monarul; Matsumoto, Taisuke; Tanaka, Junji; Feng, Xing; Redshaw, Carl; Yamato, Takehiko

    2016-10-01

    Novel [n]benzofuranophanes (n = 8 & 10) 2a-b have been prepared by successive intramolecular cyclization from 5,19-di-tert-butyl-8,22-dimethoxy[n]metacyclophane-1-yne (syn-1a-b) by treatment with BBr3 in CH2Cl2 at room temperature for 8h. [2.n]Benzofuranophanes 2a-b were also obtained by treatment of 1,2-di-endo-bromo-5,19-di-tert-butyl-8,22-dimethoxy[n]metacyclophane (meso-3a-b) with BBr3 in CH2Cl2 by using the same reaction conditions. 1H NMR spectra of 2a-b reveals the formation of intramolecular hydrogen bonding between hydroxyl proton with the oxygen of the furan moiety and X-ray analysis shows that the lengths between H (OH) and O (furan) are 1.981 and 1.823 Å̊, respectively. The conformation of [8]benzofuranophane 2a in solution is rigid with restricted rotation around the diaryl linkage rather than [10]benzofuranophane 2b because of weak intramolecular hydrogen bonding and the short length of the cross-linking chain.

  19. 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

  20. Determination of S-methyl-, S-propyl-, and S-propenyl-L-cysteine sulfoxides by gas chromatography-mass spectrometry after tert-butyldimethylsilylation.

    PubMed

    Tsuge, Kouichiro; Kataoka, Mieko; Seto, Yasuo

    2002-07-31

    A gas chromatographic-mass spectrometric method for the determination of S-methyl-L-cysteine sulfoxide (1), S-propyl-L-cysteine sulfoxide (2), and S-propenyl-L-cysteine sulfoxide (3), specific marker compounds in the genus Allium, is described. The target amino acids were converted to the tert-butyldimethylsilyl derivatives. The products were silylated on the amino and carboxyl groups and on an additional oxygen atom and were separated on a nonpolar capillary column. That incorporation of three tert-butyldimethylsilyl groups had occurred was verified by mass spectrometry, which gave an m/z 302 fragment as base peak (amino acid side chain eliminated ion) and m/z 436 (1), 464 (2), or 462 (3) as major peaks (tert-butyl function eliminated ion), by electron impact ionization. The detection limits for 1 and 2 under selected ion monitoring at m/z 436 (1) and m/z 464 (2), respectively, were determined to be 0.3 and 1.8 ng per injection. To clean up the analytes from the solvent extract of onion, as a representative food material, onion, the sample solution was subjected to combined solid phase extraction. The eluate from a Sep-Pak C(18) cartridge was applied to a Bond Elut SCX cartridge (H(+) form), followed by washing with 0.1 M hydrochloric acid and elution with 0.5 M ammonia. From a simulated matrix solution containing 5% sucrose, 1 and 2 were extracted quantitatively, and the detection yield was approximately 75%. The contents of 1, 2, and 3 in commercial onion were estimated to be 0.3, 3.1, and 3.0 mg, respectively, per gram of fresh weight. PMID:12137458

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

    SciTech Connect

    Susial, P.; Ortega, J. . 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.

  2. Solid state proton spin relaxation and methyl and t-butyl reorientation

    NASA Astrophysics Data System (ADS)

    Beckmann, Peter A.; Al-Hallaq, Hania A.; Fry, Anne M.; Plofker, Amy L.; Roe, Brian A.; Weiss, Jessica A.

    1994-01-01

    We have measured the temperature T and Larmor frequency ω/2π dependence of the proton spin-lattice relaxation rate R in solid 1-hydroxy-2,4,6-tri-butylbenzene. The data is interpreted in terms of the rotational motion of the t-butyl groups and their constituent methyl groups. Our data is much more extensive than a previous report [J. Yamauchi and C. A. McDowell, J. Chem. Phys. 75, 1051 (1981)] resulting in a revised dynamical model and considerably larger rotational barriers. Interesting thermal history effects are discussed.

  3. Preparation of unconventional dendrimers that contain rigid NH-triazine linkages and peripheral tert-butyl moieties for CO2 -selective adsorption.

    PubMed

    Lee, Cheng-Hua; Tsai, Meng-Rong; Chang, Yen-Tzu; Lai, Long-Li; Lu, Kuang-Lieh; Cheng, Kung-Lung

    2013-08-01

    Three unconventional dendrimers that contained rigid NH-triazine linkages and peripheral tert-butyl moieties were prepared by using a convergent approach and characterized by (1)H and (13)C NMR spectroscopy, mass spectrometry, and elemental analysis. Based on a thermogravimetric analysis study, these dendrimers were observed to display thermal stability at about 300 °C. The NH-triazine moiety, which possessed protonated and proton-free nitrogen sites (like the imidazole unit), displayed the capture of polarizable CO2 molecules through hydrogen-bond and/or dipole-quadrupole interactions. In addition, the adsorption of various amounts of CO2 and N2 at different pressures suggests that the dendritic pores, which arise from the stacking of the middle co-planar and rim protuberant dendrimers, Gn -N∼N-Gn (n=1-3), either swell or shrink at high pressure, thus indicating that these dendrimers may have a breathing ability. PMID:23794529

  4. Microwave-assisted synthesis of sec/tert-butyl 2-arylbenzimidazoles and their unexpected antiproliferative activity towards ER negative breast cancer cells.

    PubMed

    Abdul Rahim, Aisyah Saad; Salhimi, Salizawati Muhamad; Arumugam, Natarajan; Pin, Lim Chung; Yee, Ng Shy; Muttiah, Nithya Niranjini; Keat, Wong Boon; Abd Hamid, Shafida; Osman, Hasnah; Mat, Ishak b

    2013-12-01

    A new series of N-sec/tert-butyl 2-arylbenzimidazole derivatives was synthesised in 85-96% yields within 2-3.5 min by condensing ethyl 3-amino-4-butylamino benzoate with various substituted metabisulfite adducts of benzaldehyde under focused microwave irradiation. The benzimidazole analogues were characterised using (1)H NMR, (13)C NMR, high resolution MS and melting points. Evaluation of antiproliferative activity of the benzimidazole analogues against MCF-7 and MDA-MB-231 revealed several compounds with unexpected selective inhibitions of MDA-MB-231 in micromolar range. All analogues were found inactive towards MCF-7. The most potent inhibition against MDA-MB-231 human breast cancer cell line came from the unsubstituted 2-phenylbenzimidazole 10a. PMID:23061895

  5. 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.

  6. Design, synthesis and antibacterial potential of 5-(benzo[d][1,3]dioxol-5-yl)-3-tert-butyl-1-substituted-4,5-dihydropyrazoles

    PubMed Central

    El-Behairy, Mohammed F.; Mazeed, Tarek E.; El-Azzouny, Aida A.; Aboul-Enein, Mohamed N.

    2014-01-01

    A series of 5-(benzo[d][1,3]dioxol-5-yl)-3-tert-butyl-1-substituted-4,5-dihydropyrazole derivatives 4a–e and 6a–g have been synthesized and spectrally characterized. The antibacterial activity of the novel candidates has been screened using the agar diffusion test. These compounds were endowed with high antibacterial activity against different Gram +ve and Gram −ve bacteria when compared with standard antibacterial drugs. In the light of zone of inhibition and MIC results, Sarcina and Staphylococcus aureus are the most sensitive bacteria where pyrrolidinomethanone derivative 4e showed MICs at 80 and 110 nM, respectively. While hydroxypiperidinoethanone derivative 6c showed MIC at 90 nM for Sarcina. PMID:25972742

  7. Preparation of Langmuir-Blodgett thin films of calix[6]arenes and p-tert butyl group effect on their gas sensing properties

    NASA Astrophysics Data System (ADS)

    Ozmen, Mustafa; Ozbek, Zikriye; Bayrakci, Mevlut; Ertul, Seref; Ersoz, Mustafa; Capan, Rifat

    2015-12-01

    Organic vapor sensing properties of Langmuir-Blodgett (LB) thin films of p-tert-butyl calix[6]arene and calix[6]arene, and their certain characterization are reported in this work. LB films of these calixarenes have been characterized by contact angle measurement, quartz crystal microbalance (QCM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). QCM system was used for the measurement of sensor response against chloroform, benzene, toluene and ethanol vapors. Forming of stable monolayers was observed at the water surface using surface pressure-area isotherm graph. The results indicate that good quality, uniform LB films can be prepared with a transfer ratio of over 0.95. Due to the adsorption of vapors into the LB film structures; they yield a response to all vapors as of large, fast, and reproducible.

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

    PubMed

    Mori, H; Arai, T; Ishii, H; Adachi, T; Endo, N; Makino, K; Mori, K

    1998-01-30

    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 alpha-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 dose and a greater efficiency than PBN in global brain ischemia in gerbils. These findings suggest that P6A is a more potent neuroprotective agent than PBN and has possible therapeutic effects against various diseases in which O2.- is involved. PMID:9507930

  9. 4-Bromo­methyl-6-tert-butyl-2H-chromen-2-one

    PubMed Central

    Nagarajaiah, H.; Puttaraju, K. B.; Shivashankar, K.; Begum, Noor Shahina

    2013-01-01

    In the crystal structure of the title compound, C14H15BrO2, weak C—H⋯O inter­actions link the mol­ecules into zigzag chains extending along the c-axis direction. These chains are further assembled into (100) layers via π–π stacking inter­actions between inversion-related chromenone fragments [inter­planar distance = 3.376 (2) Å]. PMID:24046630

  10. 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...