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1

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

NASA Astrophysics Data System (ADS)

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

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

2004-06-01

2

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

PubMed

The fate of fuel oxygenates such as methyl tert-butyl ether (MTBE) in the subsurface is governed by their degradability under various redox conditions. The key intermediate in degradation of MTBE and ethyl tert-butyl ether (ETBE) is tert-butyl alcohol (TBA) which was often found as accumulating intermediate or dead-end product in lab studies using microcosms or isolated cell suspensions. This review discusses in detail the thermodynamics of the degradation processes utilizing various terminal electron acceptors, and the aerobic degradation pathways of MTBE and TBA. It summarizes the present knowledge on MTBE and TBA degradation gained from either microcosm or pure culture studies and emphasizes the potential of compound-specific isotope analysis (CSIA) for identification and quantification of degradation processes of slowly biodegradable pollutants such as MTBE and TBA. Microcosm studies demonstrated that MTBE and TBA may be biodegradable under oxic and nearly all anoxic conditions, although results of various studies are often contradictory, which suggests that site-specific conditions are important parameters. So far, TBA degradation has not been shown under methanogenic conditions and it is currently widely accepted that TBA is a recalcitrant dead-end product of MTBE under these conditions. Reliable in situ degradation rates for MTBE and TBA under various geochemical conditions are not yet available. Furthermore, degradation pathways under anoxic conditions have not yet been elucidated. All pure cultures capable of MTBE or TBA degradation isolated so far use oxygen as terminal electron acceptor. In general, compared with hydrocarbons present in gasoline, fuel oxygenates biodegrade much slower, if at all. The presence of MTBE and related compounds in groundwater therefore frequently limits the use of in situ biodegradation as remediation option at gasoline-contaminated sites. Though degradation of MTBE and TBA in field studies has been reported under oxic conditions, there is hardly any evidence of substantial degradation in the absence of oxygen. The increasing availability of field data from CSIA will foster our understanding and may even allow the quantification of degradation of these recalcitrant compounds. Such information will help to elucidate the crucial factors of site-specific biogeochemical conditions that govern the capability of intrinsic oxygenate degradation. PMID:15134874

Schmidt, Torsten C; Schirmer, Mario; Weiss, Holger; Haderlein, Stefan B

2004-06-01

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

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

Microsoft Academic Search

Fuel oxygenates, mainly methyl tert-butyl ether (MTBE) but also ethyl tert-butyl ether (ETBE), are added to gasoline in replacement of lead tetraethyl to enhance its octane index. Their addition also improves the combustion efficiency and therefore decreases the emission of pollutants (CO and hydrocarbons). On the other hand, MTBE, being highly soluble in water and recalcitrant to biodegradation, is a

Nicolas Lopes Ferreira; Cédric Malandain; Françoise Fayolle-Guichard

2006-01-01

5

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

PubMed Central

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

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

1997-01-01

6

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). ...

7

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 (...

8

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

PubMed

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

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

2008-11-01

9

Isotopic fractionation of methyl tert-butyl ether suggests different initial reaction mechanisms during aerobic biodegradation.  

PubMed

Carbon isotopic enrichment factors (epsilonC) measured during cometabolic biodegradation of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) by Pseudonocardia tetrahydrofuranoxydans strain K1 were -2.3 +/- 0.2 per thousand, -1.7 +/- 0.2 per thousand, and -1.7 +/- 0.3 per thousand, respectively. The measured carbon apparent kinetic isotope effect was 1.01 for all compounds, consistent with the expected kinetic isotope effects for both oxidation of the methoxy (or ethoxy) group and enzymatic SN1 biodegradation mechanisms. Significantly, delta13C measurements of the tert-butyl alcohol and tert-amyl alcohol products indicated that the tert-butyl and tert-amyl groups do not participate in the reaction and confirmed that ether biodegradation by strain K1 involves oxidation of the methoxy (or ethoxy) group. Measured hydrogen isotopic enrichment factors (epsilonH) were -100 +/- 10 per thousand, -73 +/- 7 per thousand, and -72 +/- 20 per thousand for MTBE, ETBE, and TAME respectively. Previous results reported for aerobic biodegradation of MTBE by Methylibium petroleiphilum PM1 and Methylibium R8 showed smaller epsilonH values (-35 per thousand and -42 per thousand, respectively). Plots of Delta2H/Delta13C show different slopes for strain K1 compared with strains PM1 and R8, suggesting that different mechanisms are utilized by K1 and PM1/R8 during aerobic MTBE biodegradation. PMID:19475952

McKelvie, Jennifer R; Hyman, Michael R; Elsner, Martin; Smith, Christy; Aslett, Denise M; Lacrampe-Couloume, Georges; Lollar, Barbara Sherwood

2009-04-15

10

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

E-print Network

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

Dandy, David

11

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-...

12

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...

13

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...

14

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...

15

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...

16

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...

17

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...

18

WATER QUALITY AT FIVE MARINAS IN LAKE TEXOMA AS RELATED TO METHYL TERT-BUTYL ETHER (MTBE): JOURNAL ARTICLE  

EPA Science Inventory

NRMRL-ADA- 02224 An, Y, Kampbell*, D.H., and Sewell*, G.W. WATER QUALITY AT FIVE MARINAS IN LAKE TEXOMA AS RELATED TO METHYL TERT-BUTYL ETHER (MTBE). Environmental Pollution118: 331-336 (2002). 600/J-02/230. Occurrence of methyl tert-but...

19

Biodegradation of methyl tert -butyl ether by newly identified soil microorganisms in a simple mineral solution  

Microsoft Academic Search

Methyl tert-butyl ether (MTBE) is a widely used fuel ether, which has become a soil and water contaminant. In this study, 12 microbial\\u000a strains were isolated from gasoline-contaminated soils and selected because of their capacity to grow in MTBE. The strains\\u000a were identified by 16S\\/ITS rDNA gene sequencing and screened for their ability to consume MTBE aerobically in a simple

Maria José Barberà; Estíbaliz Mateo; Rasa MonkaityteMagda; Magda Constantí

2011-01-01

20

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

Microsoft Academic Search

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

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

1997-01-01

21

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

PubMed

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

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

2012-04-01

22

ETBE (ethyl tert butyl ether) and TAME (tert amyl methyl ether) affect microbial community structure and function in soils.  

PubMed

Ethyl tert butyl ether (ETBE) and tert amyl methyl ether (TAME) are oxygenates used in gasoline in order to reduce emissions from vehicles. The present study investigated their impact on a soil microflora that never was exposed to any contamination before. Therefore, soil was artificially contaminated and incubated over 6 weeks. Substrate induced respiration (SIR) measurements and phospholipid fatty acid (PLFA) analysis indicated shifts in both, microbial function and structure during incubation. The results showed an activation of microbial respiration in the presence of ETBE and TAME, suggesting biodegradation by the microflora. Furthermore, PLFA concentrations decreased in the presence of ETBE and TAME and Gram-positive bacteria became more dominant in the microbial community. PMID:21288640

Bartling, Johanna; Esperschütz, Jürgen; Wilke, Berndt-Michael; Schloter, Michael

2011-03-15

23

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

Microsoft Academic Search

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

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

2002-01-01

24

Single-walled carbon nanotubes as an effective adsorbent in solid-phase microextraction of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether from human urine.  

PubMed

Carbon nanotubes (CNTs) are a kind of new carbon-based nano-materials which have drawn great attention in many application fields. The potential single-walled carbon nanotubes (SWCNTs) as solid-phase microextraction (SPME) adsorbents for the preconcentration of environmental pollutants have been investigated in recent years. The goal of this work was to investigate the feasibility of SWCNTs used as adsorbents for solid-phase microextraction of methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) in human urine. SWCNTs were attached onto a stainless steel wire through organic binder. Potential factors affecting the extraction efficiency were optimized, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity. The developed method showed good performance according to the ICH performance criteria for bioanalytical methods. The calibration curves of the ethers were linear (r(2)>or=0.992) in the range from 10 to 5000 ng L(-1). The limits of detection at a signal-to-noise (S/N) ratio of 3 were 10 ng L(-1) for all the analytes. In addition, compared with the commercial carboxen/polydimethylsiloxane (CAR/PDMS) fiber, the SWCNT fiber showed better thermal stability (over 350 degrees C) and longer life span (over 150 times). The developed method was applied successfully to determine trace level of the ethers in urine of 10 healthy male volunteers. PMID:19395320

Rastkari, Noushin; Ahmadkhaniha, Reza; Yunesian, Masud

2009-05-15

25

Determination of low level methyl tert-butyl ether, ethyl tert-butyl ether and methyl tert-amyl ether in human urine by HS-SPME gas chromatography/mass spectrometry.  

PubMed

Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME) are oxygenated compounds added to gasoline to enhance octane rating and to improve combustion. They may be found as pollutants of living and working environments. In this work a robotized method for the quantification of low level MTBE, ETBE and TAME in human urine was developed and validated. The analytes were sampled in the headspace of urine by SPME in the presence of MTBE-d12 as internal standard. Different fibers were compared for their linearity and extraction efficiency: carboxen/polydimethylsiloxane, polydimethylsiloxane/divinylbenzene, and polydimethylsiloxane. The first, although highly efficient, was discarded due to deviation of linearity for competitive displacement, and the polydimethylsiloxane/divinylbenzene fiber was chosen instead. The analysis was performed by GC/MS operating in the electron impact mode. The method is very specific, with range of linearity 30-4600 ng L(-1), within- and between-run precision, as coefficient of variation, <22 and <16%, accuracy within 20% the theoretical level, and limit of detection of 6 ng L(-1) for all the analytes. The influence of the matrix on the quantification of these ethers was evaluated analysing the specimens of seven traffic policemen exposed to autovehicular emissions: using the calibration curve and the method of standard additions comparable levels of MTBE (68-528 ng L(-1)), ETBE (<6 ng L(-1)), and TAME (<6 ng L(-1)) were obtained. PMID:17386425

Scibetta, Licia; Campo, Laura; Mercadante, Rosa; Foà, Vito; Fustinoni, Silvia

2007-01-01

26

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

PubMed Central

Biodegradation of methyl tert-butyl ether (MTBE) by the hydrogen-oxidizing bacterium Hydrogenophaga flava ENV735 was evaluated. ENV735 grew slowly on MTBE or tert-butyl alcohol (TBA) as sole sources of carbon and energy, but growth on these substrates was greatly enhanced by the addition of a small amount of yeast extract. The addition of H2 did not enhance or diminish MTBE degradation by the strain, and MTBE was only poorly degraded or not degraded by type strains of Hydrogenophaga or hydrogen-oxidizing enrichment cultures, respectively. MTBE degradation activity was constitutively expressed in ENV735 and was not greatly affected by formaldehyde, carbon monoxide, allyl thiourea, or acetylene. MTBE degradation was inhibited by 1-amino benzotriazole and butadiene monoepoxide. TBA degradation was inducible by TBA and was inhibited by formaldehyde at concentrations of >0.24 mM and by acetylene but not by the other inhibitors tested. These results demonstrate that separate, independently regulated genes encode MTBE and TBA metabolism in ENV735. PMID:11722912

Hatzinger, Paul B.; McClay, Kevin; Vainberg, Simon; Tugusheva, Marina; Condee, Charles W.; Steffan, Robert J.

2001-01-01

27

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

PubMed

Fuel oxygenates, mainly methyl tert-butyl ether (MTBE) but also ethyl tert-butyl ether (ETBE), are added to gasoline in replacement of lead tetraethyl to enhance its octane index. Their addition also improves the combustion efficiency and therefore decreases the emission of pollutants (CO and hydrocarbons). On the other hand, MTBE, being highly soluble in water and recalcitrant to biodegradation, is a major pollutant of water in aquifers contaminated by MTBE-supplemented gasoline during accidental release. MTBE was shown to be degraded through cometabolic oxidation or to be used as a carbon and energy source by a few microorganisms. We have summarized the present state of knowledge about the microorganisms involved in MTBE degradation and the MTBE catabolic pathways. The role of the different enzymes is discussed as well as the rare and recent data concerning the genes encoding the enzymes involved in the MTBE pathway. The phylogeny of the microorganisms isolated for their capacity to grow on MTBE is also described. PMID:16804692

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

2006-09-01

28

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...

29

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...

30

Enhancing Transport of Hydrogenophagaflava ENV735 for Bioaugmentation of Aquifers Contaminated with Methyl tertButyl Ether  

Microsoft Academic Search

The gasoline oxygenate methyl tert-butyl ether (MTBE) has become a widespread contaminant in ground- water 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

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

2002-01-01

31

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...

32

Biodegradation of Methyl tert-Butyl Ether and Other Fuel Oxygenates by a New Strain, Mycobacterium austroafricanum IFP 2012  

PubMed Central

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

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

2002-01-01

33

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

EPA Science Inventory

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

34

Methyl tert -butyl ether biodegradation by microbial consortia obtained from soil samples of gasoline-polluted sites in Mexico  

Microsoft Academic Search

Microbial consortia obtained from soil samples of gasoline-polluted sites were individually enriched with pentane, hexane, isooctane and toluene. Cometabolism with methyl tert-butyl ether, (MTBE), gave maximum degradation rates of 49, 12, 32 and 0 mg gprotein-1 h-1, respectively. MTBE was fully degraded even when pentane was completely depleted with a cometabolic coefficient of 1 mgMTBE mgpentane-1. The analysis of 16S rDNA from isolated microorganisms in

Marcia Morales; Elia Velázquez; Janet Jan; Sergio Revah; Uriel González; Elías Razo-Flores

2004-01-01

35

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

PubMed

To provide guidance on the selection of proper persulfate processes for the remediation of MTBE contaminated groundwater, MTBE aqueous solutions were treated with three common field persulfate processes including heat activated persulfate, Fe(III)-EDTA activated persulfate and alkaline persulfate, respectively. The results were compared with MTBE oxidation by Fenton's reagent and persulfate alone at 25°C. The impact of the activating conditions on the fate of MTBE and its daughter products was investigated. Heat activation at 40°C offered the most rapid removal of MTBE and its daughter products, while Fe(III)-EDTA activation showed higher efficiency of MTBE removal but low removal efficiency of its daughter products. On the other hand, alkaline persulfate showed slower kinetics for the removal of MTBE and less accumulation of the daughter products. Furthermore, tert-butyl alcohol and acetone were observed as the main purgeable daughter products along with a small amount of tert-butyl formate in persulfate oxidation of MTBE, while tert-butyl formate, tert-butyl alcohol and acetone were the main products in Fenton oxidation. Mechanistic analysis suggests that degradation of MTBE by persulfate most likely happens via non-oxygen demand pathways, different from the dominant oxygen demand degradation pathways observed in Fenton oxidation. PMID:24246442

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

2014-01-15

36

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

PubMed

The inhibitory effects of the fuel additive methyl tert-butyl ether (MTBE) and potential degradation products tert-butanol (TBA) and formaldehyde was examined using mixed microbial biomass, and six strains of bioluminescent bacteria and yeast. The purpose was to assess microbial toxicity with quantitative bioluminescent and fluorescent endpoints, and to identify sensitive proxies suitable for monitoring MTBE contamination. Bioluminescent Aliivibrio fischeri DSM 7151 (formerly Vibrio fischeri) appeared highly sensitive to MTBE exposure, and was a superior test organisms compared to lux-tagged Escherichia coli DH5?, Pseudomonas fluorescens DF57-40E7 and Saccharomyces cerevisiae BLYR. EC10 and EC50 for acute MTBE toxicity in A. fischeri were 1.1 and 10.9mgL(-1), respectively. Long term (24h) MTBE exposure resulted in EC10 values of 0.01mgL(-1). TBA was significantly less toxic with EC10 and EC50 for acute and chronic toxicity >1000mgL(-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 ?3.7g 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 0.5-787mgL(-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?64.8mgL(-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

Roslev, Peter; Lentz, Trine; Hesselsoe, Martin

2015-02-01

37

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

PubMed Central

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 ?g ml?1 h?1 for initial concentrations of 5, 50, and 500 ?g MTBE ml?1, respectively. When incubated with 20 ?g 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 ?g of MTBE ml?1 added to the core material. The rate of MTBE removal increased with additional inputs of 20 ?g of MTBE ml?1. These results suggest that PM1 has potential for use in the remediation of MTBE-contaminated environments. PMID:10543787

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

1999-01-01

38

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

PubMed

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

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

2006-12-01

39

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

USGS Publications Warehouse

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.

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

2001-01-01

40

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

SciTech Connect

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

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

1999-11-01

41

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

USGS Publications Warehouse

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.

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

1998-01-01

42

Mineralization of methyl tert -butyl ether and other gasoline oxygenates by Pseudomonads using short n -alkanes as growth source  

Microsoft Academic Search

Biodegradation of methyl tert-butyl ether (MTBE) by cometabolism has shown to produce recalcitrant metabolic intermediates that often accumulate. In this\\u000a work, a consortium containing Pseudomonads was studied for its ability to fully degrade oxygenates by cometabolism. This consortium\\u000a mineralized MTBE and TBA with C3–C7 n-alkanes. The highest degradation rates for MTBE (75 ± 5 mg gprotein\\u000a ?1 h?1) and TBA (86.9 ± 7.3 mg gprotein\\u000a ?1 h?1) were obtained with

Marcia Morales; Verónica Nava; Elia Velásquez; Elías Razo-Flores; Sergio Revah

2009-01-01

43

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

USGS Publications Warehouse

Thirty-one monitoring wells in the Windham aquifer in North Windham, Maine, were sampled for methyl tert-butyl ether (MTBE) from July 1998 to May 1999. MTBE was detected in 35 percent of the wells sampled in the Windham aquifer. MTBE was detected in 64 percent of wells in the high-yielding part of the aquifer; these wells account for 82 percent of all wells with detectable MTBE. Land cover also was found to be associated with MTBE in the wells in the study area, with the urban and low-density residential areas having more MTBE than undeveloped areas. The median concentration in wells with detectable MTBE was 1.13 micrograms per liter. Air and precipitation samples were collected in North Windham along with ground-water samples. Air samples were collected every 10 days from December 1998 to July 1999 (20 samples). MTBE was present in all 20 air samples collected, at concentrations ranging from 0.03 ppbv (parts per billion by volume) to 1.0 ppbv. Before Maine opted out of the reformulated gasoline (RFG) program in the spring of 1999, median concentrations in air at the North Windham site were 0.25 ppbv. After Maine stopped using RFG, the median concentration in air dropped to 0.09 ppbv. No MTBE was detected in four samples of precipitation at North Windham. The lack of rainfall during the study period prevented the collection of an adequate number of samples, and technical difficulties negated the results of some of the analyses of the samples that were collected. Based on the equilibrium partitioning of MTBE from the air into rain, the hypothetical average concentration of MTBE in rainfall during months when recharge typically occurs (March-April and October-December) would be approximately 0.3 to 0.4 micrograms per liter during the time that RFG was being used in Maine. After the phaseout of RFG, the maximum average concentration of MTBE in rainfall during these months would be approximately 0.1 micrograms per liter. The distribution and concentrations of MTBE that were detected in ground water indicate that recharge from precipation containing MTBE is not a likely explanation for the occurrence of MTBE in the Windham aquifer.

Nielsen, Martha G.; Peckenham, John M.

2000-01-01

44

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

PubMed

An overview of methyl tert-butyl ether (MTBE) concentrations in German river water (315 samples) and wastewater (82 samples) is given. In the agglomerated area of Frankfurt/M, several samples of surface water, wastewater, and industrial effluents were analyzed for its MTBE content from 1999 to 2001. MTBE was analyzed by a combination of headspace-solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME/GC-MS). Rhine and Main water concentrations of MTBE in the lower parts of the rivers were approximately 250 ng/L and 200 ng/L, respectively. The concentrations increased from the upper parts of the rivers to its mouths. Water from the Elbe, Neckar, and Weser rivers showed lower MTBE concentrations, and the ether was not detected in the Danube river. Generally, higher MTBE concentrations were detected at urban agglomerations compared to rural areas. Small urban creeks without significant industrial input showed MTBE concentrations of approximately 50 ng/L, and it was hardly detectable in small rural creeks. Higher MTBE concentrations in river water were correlated with increased concentrations of the oxygenate measured in precipitation. Most MTBE concentrations in river water fell in the range of 50-200 ng/L (32%), 10-50 ng/L (28%), and 200-1000 ng/L (26%). MTBE concentrations in German surface water and air are 3-17 times lower compared to Californian data. Wastewater samples from influents of two sewage plants showed MTBE concentrations of approximately 100-300 ng/L, and a loading of 2-37 kg/a was calculated. An eliminated MTBE percentage of roughly 30-35% of MTBE in the plants was estimated. Industrially influenced samples of river water or public wastewater and industrial effluents showed MTBE concentrations of up to 2267 ng/L and 28 microg/L, respectively. This input has not been considered before because only 1.5% of the produced amount of MTBE in Germany is used for industrial processes, but it should not be neglected because MTBE is very persistent in water. PMID:12322734

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

2002-09-01

45

Comparative transcriptome analysis of Methylibium petroleiphilum PM1 exposed to the fuel oxygenates methyl tert-butyl ether and ethanol.  

PubMed

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

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

2007-11-01

46

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

PubMed Central

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

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

47

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

PubMed

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, which can be converted to 2-hydroxyisobutyric acid and further metabolized. Developments in microbiology make biological treatment of water contaminated with MTBE and other oxygenates an attractive possibility. Work concerning ex situ treatment in biofilters by consortia and by pure strains, and involving or not cometabolism, is under way. Furthermore, the development of in situ treatment processes is a promisinggoal. PMID:11549000

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

2001-08-01

48

Aerobic Biodegradation of Methyl tert-Butyl Ether by Aquifer Bacteria from Leaking Underground Storage Tank Sites  

PubMed Central

The potential for aerobic methyl tert-butyl ether (MTBE) degradation was investigated with microcosms containing aquifer sediment and groundwater from four MTBE-contaminated sites characterized by oxygen-limited in situ conditions. MTBE depletion was observed for sediments from two sites (e.g., 4.5 mg/liter degraded in 15 days after a 4-day lag period), whereas no consumption of MTBE was observed for sediments from the other sites after 75 days. For sediments in which MTBE was consumed, 43 to 54% of added [U-14C]MTBE was mineralized to 14CO2. Molecular phylogenetic analyses of these sediments indicated the enrichment of species closely related to a known MTBE-degrading bacterium, strain PM1. At only one site, the presence of water-soluble gasoline components significantly inhibited MTBE degradation and led to a more pronounced accumulation of the metabolite tert-butyl alcohol. Overall, these results suggest that the effects of oxygen and water-soluble gasoline components on in situ MTBE degradation will vary from site to site and that phylogenetic analysis may be a promising predictor of MTBE biodegradation potential. PMID:11722940

Kane, S. R.; Beller, H. R.; Legler, T. C.; Koester, C. J.; Pinkart, H. C.; Halden, R. U.; Happel, A. M.

2001-01-01

49

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

Microsoft Academic Search

An aerobic microbial consortium able to biodegrade methyl tert-butyl ether (MTBE) was enriched in two waste air biotrickling filters after continuous operation for 6 months. After this acclimation phase, the two laboratory-scale biotrickling filters were able to degrade up to 50 g of MTBE per cubic meter of reactor per hour, a value comparable to other gasoline constituents. Such high

N. Y. Fortin; M. A. Deshusses

1999-01-01

50

RELATIONS BETWEEN THE DETECTION OF METHYL TERT-BUTYL ETHER (MTBE) IN SURFACE AND GROUND WATER AND ITS CONTENT IN GASOLINE  

E-print Network

RELATIONS BETWEEN THE DETECTION OF METHYL TERT-BUTYL ETHER (MTBE) IN SURFACE AND GROUND WATER soil adsorption, and low biodegradability, has resulted in its detection in many ground- and surface-water systems. Sampling of ground water at a national scale by the U.S. Geological Survey's (USGS) National

51

The first non-acid catalytic synthesis of tert-butyl ether from tert-butyl alcohol using ionic liquid as dehydrator.  

PubMed

Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and isopropyl tert-butyl ether (IPTBE) have been synthesized for the first time over a non-acid ionic liquid as catalyst and dehydrator with high conversion (> 90%) and selectivity (> 90%) under mild conditions. PMID:12772899

Shi, Feng; Xiong, Hai; Gu, Yanlong; Guo, Shu; Deng, Youquan

2003-05-01

52

Mineralization of methyl tert-butyl ether and other gasoline oxygenates by Pseudomonads using short n-alkanes as growth source.  

PubMed

Biodegradation of methyl tert-butyl ether (MTBE) by cometabolism has shown to produce recalcitrant metabolic intermediates that often accumulate. In this work, a consortium containing Pseudomonads was studied for its ability to fully degrade oxygenates by cometabolism. This consortium mineralized MTBE and TBA with C3-C7 n-alkanes. The highest degradation rates for MTBE (75 +/- 5 mg g(protein) (-1) h(-1)) and TBA (86.9 +/- 7.3 mg g(protein) (-1) h(-1)) were obtained with n-pentane and n-propane, respectively. When incubated with radiolabeled MTBE and n-pentane, it converted more than 96% of the added MTBE to (14)C-CO(2). Furthermore, the consortium degraded tert-amyl methyl ether, tert-butyl alcohol (TBA), tert-amyl alcohol, ethyl tert-butyl ether (ETBE) when n-pentane was used as growth source. Three Pseudomonads were isolated but only two showed independent MTBE degradation activity. The maximum degradation rates were 101 and 182 mg g(protein) (-1) h(-1) for Pseudomonas aeruginosa and Pseudomonas citronellolis, respectively. The highest specific affinity (a degrees (MTBE)) value of 4.39 l g(protein) (-1) h(-1) was obtained for Pseudomonas aeruginosa and complete mineralization was attained with a MTBE: n-pentane ratio (w/w) of 0.7. This is the first time that Pseudomonads have been reported to fully mineralize MTBE by cometabolic degradation. PMID:18814038

Morales, Marcia; Nava, Verónica; Velásquez, Elia; Razo-Flores, Elías; Revah, Sergio

2009-04-01

53

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

PubMed Central

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

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

2014-01-01

54

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

E-print Network

. Introduction Methyltert-butyl ether (MTBE) was first introduced in United States in the late 1970s as an octane among all chemicals in 1993. At the same time, an increasing number of groundwater contaminations

55

Methylibium petroleiphilum gen. nov., sp. nov., a novel methyl tert-butyl ether-degrading methylotroph of the Betaproteobacteria.  

PubMed

A Gram-negative, rod-shaped, motile, non-pigmented, facultative aerobe that grew optimally at pH 6.5 and 30 degrees C (strain PM1T) was isolated for its ability to completely degrade the gasoline additive methyl tert-butyl ether. Analysis of the 16S rRNA gene sequence indicated that this bacterium was a member of the class Betaproteobacteria in the Sphaerotilus-Leptothrix group. The 16S rRNA gene sequence identity to other genera in this group, Leptothrix, Aquabacterium, Roseateles, Sphaerotilus, Ideonella and Rubrivivax, ranged from 93 to 96 %. The chemotaxonomic data including Q-8 as the major quinone, C16 : 1omega7c and C16 : 0 as the major fatty acids and a DNA G+C content of 69 mol%, support the inclusion of strain PM1T in the class Betaproteobacteria. It differed from other members of the Sphaerotilus-Leptothrix group by being a facultative methylotroph that used methanol as a sole carbon source, and by also being able to grow heterotrophically in defined media containing ethanol, toluene, benzene, ethylbenzene and dihydroxybenzoates as sole carbon sources. On the basis of the morphological, physiological, biochemical and genetic information, a new genus and species, Methylibium petroleiphilum gen. nov., sp. nov., is proposed, with PM1T (=ATCC BAA-1232T=LMG 22953T) as the type strain. PMID:16627642

Nakatsu, Cindy H; Hristova, Krassimira; Hanada, Satoshi; Meng, Xian-Ying; Hanson, Jessica R; Scow, Kate M; Kamagata, Yoichi

2006-05-01

56

Fast detection of methyl tert-butyl ether from water using solid phase microextraction and ion mobility spectrometry.  

PubMed

Methyl tert-butyl ether (MTBE) is commonly used as chemical additive to increase oxygen content and octane rating of reformulated gasoline. Despite its impact on enhancing cleaner combustion of gasoline, MTBE poses a threat to surface and ground water when gasoline is released into the environment. Methods for onsite analysis of MTBE in water samples are also needed. A less common technique for MTBE detection from water is ion mobility spectrometry (IMS). We describe a method for fast sampling and screening of MTBE from water by solid phase microextraction (SPME) and IMS. MTBE is adsorbed from the head space of a sample to the coating of SPME fiber. The interface containing a heated sample chamber, which couples SPME and IMS, was constructed and the SPME fiber was introduced into the sample chamber for thermal desorption and IMS detection of MTBE vapors. The demonstrated SPME-IMS method proved to be a straightforward method for the detection of trace quantities of MTBE from waters including surface and ground water. We determined the relative standard deviation of 8.3% and detection limit of 5 mg L(-1) for MTBE. Because of short sampling, desorption, and detection times, the described configuration of combined SPME and IMS is a feasible method for the detection of hazardous substances from environmental matrices. PMID:21482276

Nousiainen, Marjaana; Holopainen, Sanna; Puton, Jaroslaw; Sillanpää, Mika

2011-05-15

57

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

PubMed Central

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

Sun, Weimin; Sun, Xiaoxu

2012-01-01

58

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

USGS Publications Warehouse

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.

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

2008-01-01

59

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

USGS Publications Warehouse

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.

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

2005-01-01

60

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

PubMed

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

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

2002-11-15

61

Atmospheric and Potable Water Exposures to Methyl tertButyl Ether (MTBE)  

Microsoft Academic Search

This paper presents information on the ways in which people can be exposed to methyltert-butyl ether (MTBE) via air and water and on the distribution of doses that can result from those exposures. Data on concentrations of MTBE in air were compiled for 15 different occupational, commuting, or residential exposure categories, and concentrations in potable water were compiled from five

Stephen L. Brown

1997-01-01

62

Oxidation of Methyl tert-Butyl Ether by Alkane Hydroxylase in Dicyclopropylketone-Induced and n-Octane-Grown Pseudomonas putida GPo1  

PubMed Central

The alkane hydroxylase enzyme system in Pseudomonas putida GPo1 has previously been reported to be unreactive toward the gasoline oxygenate methyl tert-butyl ether (MTBE). We have reexamined this finding by using cells of strain GPo1 grown in rich medium containing dicyclopropylketone (DCPK), a potent gratuitous inducer of alkane hydroxylase activity. Cells grown with DCPK oxidized MTBE and generated stoichiometric quantities of tert-butyl alcohol (TBA). Cells grown in the presence of DCPK also oxidized tert-amyl methyl ether but did not appear to oxidize either TBA, ethyl tert-butyl ether, or tert-amyl alcohol. Evidence linking MTBE oxidation to alkane hydroxylase activity was obtained through several approaches. First, no TBA production from MTBE was observed with cells of strain GPo1 grown on rich medium without DCPK. Second, no TBA production from MTBE was observed in DCPK-treated cells of P. putida GPo12, a strain that lacks the alkane-hydroxylase-encoding OCT plasmid. Third, all n-alkanes that support the growth of strain GPo1 inhibited MTBE oxidation by DCPK-treated cells. Fourth, two non-growth-supporting n-alkanes (propane and n-butane) inhibited MTBE oxidation in a saturable, concentration-dependent process. Fifth, 1,7-octadiyne, a putative mechanism-based inactivator of alkane hydroxylase, fully inhibited TBA production from MTBE. Sixth, MTBE-oxidizing activity was also observed in n-octane-grown cells. Kinetic studies with strain GPo1 grown on n-octane or rich medium with DCPK suggest that MTBE-oxidizing activity may have previously gone undetected in n-octane-grown cells because of the unusually high Ks value (20 to 40 mM) for MTBE. PMID:15294784

Smith, Christy A.; Hyman, Michael R.

2004-01-01

63

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

PubMed

The alkane hydroxylase enzyme system in Pseudomonas putida GPo1 has previously been reported to be unreactive toward the gasoline oxygenate methyl tert-butyl ether (MTBE). We have reexamined this finding by using cells of strain GPo1 grown in rich medium containing dicyclopropylketone (DCPK), a potent gratuitous inducer of alkane hydroxylase activity. Cells grown with DCPK oxidized MTBE and generated stoichiometric quantities of tert-butyl alcohol (TBA). Cells grown in the presence of DCPK also oxidized tert-amyl methyl ether but did not appear to oxidize either TBA, ethyl tert-butyl ether, or tert-amyl alcohol. Evidence linking MTBE oxidation to alkane hydroxylase activity was obtained through several approaches. First, no TBA production from MTBE was observed with cells of strain GPo1 grown on rich medium without DCPK. Second, no TBA production from MTBE was observed in DCPK-treated cells of P. putida GPo12, a strain that lacks the alkane-hydroxylase-encoding OCT plasmid. Third, all n-alkanes that support the growth of strain GPo1 inhibited MTBE oxidation by DCPK-treated cells. Fourth, two non-growth-supporting n-alkanes (propane and n-butane) inhibited MTBE oxidation in a saturable, concentration-dependent process. Fifth, 1,7-octadiyne, a putative mechanism-based inactivator of alkane hydroxylase, fully inhibited TBA production from MTBE. Sixth, MTBE-oxidizing activity was also observed in n-octane-grown cells. Kinetic studies with strain GPo1 grown on n-octane or rich medium with DCPK suggest that MTBE-oxidizing activity may have previously gone undetected in n-octane-grown cells because of the unusually high K(s) value (20 to 40 mM) for MTBE. PMID:15294784

Smith, Christy A; Hyman, Michael R

2004-08-01

64

Enhancing transport of hydrogenophaga flava ENV735 for bioaugmentation of aquifers contaminated with methyl tert-butyl ether.  

PubMed

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

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

2002-11-01

65

Whole-Genome Analysis of the Methyl tert-Butyl Ether-Degrading Beta-Proteobacterium Methylibium petroleiphilum PM1? †  

PubMed Central

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 (C5 to C12) hydrocarbons present in petroleum products. Whole-genome analysis of PM1 revealed an ?4-Mb circular chromosome and an ?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 (?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. PMID:17158667

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

2007-01-01

66

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

PubMed Central

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 hypoxia inducible factor (HIF)-regulated pathways were affected. HIF-driven angiogenesis via vascular endothelial growth factor (vegf) is essential to the developing vasculature of an embryo. Three rescue studies were designed to rescue MTBE-induced vascular lesions: pooled blood in the common cardinal vein (CCV), cranial hemorrhages (CH), and abnormal intersegmental vessels (ISV), and test the hypothesis that MTBE toxicity was HIF-Vegf dependent. First, zebrafish vegf-a over-expression via plasmid injection, resulted in significantly fewer CH and ISV lesions, 46 and 35% respectively, in embryos exposed to 10mM MTBE. Then HIF degradation was inhibited in two ways. Chemical rescue by N-oxaloylglycine significantly reduced CCV and CH lesions by 30 and 32% in 10mM exposed embryos, and ISV lesions were reduced 24% in 5mM exposed zebrafish. Finally, a morpholino designed to knockdown ubiquitin associated von Hippel-Lindau protein, significantly reduced CCV lesions by 35% in 10mM exposed embryos. In addition, expression of some angiogenesis related genes altered by MTBE exposure were rescued. These studies demonstrated that MTBE vascular toxicity is mediated by a down regulation of HIF-Vegf driven angiogenesis. The selective toxicity of MTBE toward developing vasculature makes it a potentially useful chemical in the designing of new drugs or in elucidating roles for specific angiogenic proteins in future studies of vascular development. PMID:24128854

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

2014-01-01

67

Carbon Conversion Efficiency and Limits of Productive Bacterial Degradation of Methyl tert-Butyl Ether and Related Compounds?  

PubMed Central

The utilization of the fuel oxygenate methyl tert-butyl ether (MTBE) and related compounds by microorganisms was investigated in a mainly theoretical study based on the YATP concept. Experiments were conducted to derive realistic maintenance coefficients and Ks values needed to calculate substrate fluxes available for biomass production. Aerobic substrate conversion and biomass synthesis were calculated for different putative pathways. The results suggest that MTBE is an effective heterotrophic substrate that can sustain growth yields of up to 0.87 g g?1, which contradicts previous calculation results (N. Fortin et al., Environ. Microbiol. 3:407-416, 2001). Sufficient energy equivalents were generated in several of the potential assimilatory routes to incorporate carbon into biomass without the necessity to dissimilate additional substrate, efficient energy transduction provided. However, when a growth-related kinetic model was included, the limits of productive degradation became obvious. Depending on the maintenance coefficient ms and its associated biomass decay term b, growth-associated carbon conversion became strongly dependent on substrate fluxes. Due to slow degradation kinetics, the calculations predicted relatively high threshold concentrations, Smin, below which growth would not further be supported. Smin strongly depended on the maximum growth rate ?max, and b and was directly correlated with the half maximum rate-associated substrate concentration Ks, meaning that any effect impacting this parameter would also change Smin. The primary metabolic step, catalyzing the cleavage of the ether bond in MTBE, is likely to control the substrate flux in various strains. In addition, deficits in oxygen as an external factor and in reduction equivalents as a cellular variable in this reaction should further increase Ks and Smin for MTBE. PMID:17220260

Müller, Roland H.; Rohwerder, Thore; Harms, Hauke

2007-01-01

68

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

PubMed Central

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

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

2002-01-01

69

Process for the preparation of a mixture consisting essentially of iso-butene oligomers and methyl tert. -butyl ether, its use, and fuels containing such mixture  

SciTech Connect

A fuel for a carburetor type engine consisting essentially of isobutene oligomers and methyl tert.-butyl ether, said fuel prepared by a process comprising: (A) in a first step contacting a mixture of straight chain and branched butanes and butenes with an acid catalyst whereby to oligomerize 50% to 90% by weight of the isobutene contained therein: (B) contacting the reaction mixture from step (A) with at least a molar amount of methanol, relative to the residual isobutene, in the presence of an acid catalyst; and (C) separating off from the reaction mixture unreacted butanes and butenes.

Schleppinghoff, B.

1983-03-22

70

Isolate PM1 populations are dominant and novel methyl tert-butyl ether-degrading bacterial in compost biofilter enrichments.  

PubMed

The gasoline additive MTBE, methyl tert-butyl ether, is a widespread and persistent groundwater contaminant. MTBE undergoes rapid mineralization as the sole carbon and energy source of bacterial strain PM1, isolated from an enrichment culture of compost biofilter material. In this report, we describe the results of microbial community DNA profiling to assess the relative dominance of isolate PM1 and other bacterial strains cultured from the compost enrichment. Three polymerase chain reaction (PCR)-based profiling approaches were evaluated: denaturing gradient gel electrophoresis (DGGE) analysis of 230 bp 16S rDNA fragments; thermal gradient gel electrophoresis (TGGE) analysis of 575 bp 16S rDNA fragments; and non-denaturing polyacrylamide gel electrophoresis of 300-1,500 bp fragments containing 16S/23S ribosomal intergenic transcribed spacer (ITS) regions. Whereas all three DNA profiling approaches indicated that PM1-like bands predominated in mixtures from MTBE-grown enrichments, ITS profiling provided the most abundant and specific sequence data to confirm strain PM1's presence in the enrichment. Moreover, ITS profiling did not produce non-specific PCR products that were observed with T/DGGE. A further advantage of ITS community profiling over other methods requiring restriction digestion (e.g. terminal restriction fragment length polymorphisms) was that it did not require an additional digestion step or the use of automated sequencing equipment. ITS bands, excised from similar locations in profiles of the enrichment and PM1 pure culture, were 99.9% identical across 750 16S rDNA positions and 100% identical across 691 spacer positions. BLAST comparisons of nearly full-length 16S rDNA sequences showed 96% similarity between isolate PM1 and representatives of at least four different genera in the Leptothrix subgroup of the beta-Proteobacteria (Aquabacterium, Leptothrix, Rubrivivax and Ideonella). Maximum likelihood and parsimony analyses of 1,249 nucleotide positions supported isolate PM1's position in a separate lineage within the Leptothrix subgroup. PMID:11321538

Bruns, M A; Hanson, J R; Mefford, J; Scow, K M

2001-03-01

71

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

SciTech Connect

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

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

2013-12-15

72

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

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

Oh, Keun-Chan; Stringfellow, William T.

2003-10-02

73

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

USGS Publications Warehouse

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.

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

2001-01-01

74

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

PubMed

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 (???? consumption in ?mol = 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

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

2014-11-29

75

Rotational Spectra, Structure, and Electric Dipole Moments of Methyl and Ethyl tert-Butyl Ether (MTBE and ETBE)  

NASA Astrophysics Data System (ADS)

The rotational spectra of methyl and ethyl tertiary butyl ether (MTBE and ETBE) have been observed and analyzed using a pulsed-molecular-beam Fabry-Perot cavity microwave spectrometer. Both a- and b-type transitions are observed for each compound. Small CH 3internal rotation splittings from the OCH 3group of ˜1 MHz are observed for MTBE. The high sensitivity of the Fourier transform microwave (FTMW) technique allows observation and analysis of the rotational spectra of all 13C isotopes and the 18O isotopic species in natural abundance. For ETBE, the structural analysis indicates that the lowest energy form of the molecule is the completely extended conformer with C ssymmetry. For both compounds, the bulkiness of the t-butyl group causes the COC angle to be 6° to 7° larger than that found in most other ethers.

Suenram, R. D.; Lovas, F. J.; Pereyra, W.; Fraser, G. T.; Walker, A. R. Hight

1997-01-01

76

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...

77

Methyl ether derivatives of p-tert-Butyl[3.1.3.1]homooxacalixarene. Formation, structure, and complexes with quaternary ammonium ions.  

PubMed

[structure: see text] The whole set (five compounds) of partially O-methylated products of p-tert-butyl[3.1.3.1]homooxacalixarene, currently named p-tert-butyltetrahomodioxacalix[4]arene, have been prepared. Their structure has been investigated in solution through NMR techniques and in the solid state by single-crystal X-ray diffraction. A systematic investigation, extended to the parent tetraphenol and to the tetramethyl ether derivative, has been carried out on the complexation of tetramethylammonium, acetylcholine, N-methylpyridinium, and tetraethylammonium picrate in CDCl3. The observed trends in the binding and in the selectivity of the strictly related hosts could be analyzed on the basis of the varying importance of intramolecular hydrogen bonding and its effects on the conformation of the free and of the complexed ligands. On increasing the number of methyl ether functions, the cone conformation appears to be relatively less stable but deeper, so small organic cations can be more effectively encircled. PMID:16408957

Masci, Bernardo; Mortera, Stefano Levi; Persiani, Daniela; Thuéry, Pierre

2006-01-20

78

4-[(tert-Butyl­dimethyl­sil­yl)­oxy]-6-meth­oxy-7-methyl-5-(oxiran-2-ylmeth­yl)-2-benzofuran-3(1H)-one  

PubMed Central

The title compound, C19H28O5Si, was obtained in the reaction of 1,3-dihydro-4-[(tert-butyl­dimethyl­sil­yl)­oxy]-6-meth­oxy-7-methyl-3-oxo-5-(prop-2-en­yl)isobenzofuran with meta-chloro­perbenzoic acid. This reaction is one of the stages of the total synthesis of mycophenolic acid, which we attempted to modify. The title compound forms crystals with only weak inter­molecular inter­actions. The strongest stacking inter­action is found between the benzene and furan rings of inversion-related mol­ecules with a distance of 3.8773?(13)?Å between the ring centroids. PMID:22199882

Malachowska-Ugarte, Magdalena; Cholewinski, Grzegorz; Chojnacki, Jaroslaw; Dzierzbicka, Krystyna

2011-01-01

79

Use of proteomics and physiological characteristics to elucidate ecotoxic effects of methyl tert-butyl ether in Pseudomonas putida KT2440.  

PubMed

We monitored rates of growth, ATP-synthesis, respiration, and death to assess the sensitivity of the model organism Pseudomonas putida KT2440 to methyl tert-butyl ether (MTBE), and its degree of toxicity. The physiological data obtained suggested that the energy conservation system was the most sensitive site. However, with the help of proteomic analysis we obtained further information and deeper insight into the molecular mechanisms involved. This analysis indicated that sensitivity involves oxidative stress since alkylhydroperoxide reductase C (AhpC) and two superoxide dismutases (SodM, SodF) were amplified in the presence of MTBE. Thus, proteomics has major advantages in ecotoxicological investigations where the aims include elucidation of the molecular mechanisms as well as characterization of the ecostress and the potency of the stressor(s). PMID:12923780

Krayl, Martin; Benndorf, Dirk; Loffhagen, Norbert; Babel, Wolfgang

2003-08-01

80

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

PubMed

In Catalonia (northeast Spain), a monitoring program was carried out to determine methyl tert.-butyl ether (MTBE), its main degradation products, tert.-butyl alcohol (TBA), tert.-butyl formate (TBF), and other gasoline additives, the oxygenate dialkyl ethers ethyl tert.-butyl ether, tert.-amyl methyl ether and diisopropyl ether and the aromatic compounds benzene, toluene, ethylbenzene and xylene (BTEX) in 21 groundwater wells that were located near different gasoline point sources (a gasoline spill and underground storage tank leakage). Purge-and-trap coupled to gas chromatography-mass spectrometry was optimised for the simultaneous determination of the above mentioned compounds and enabled to detect concentrations at ng/l or sub-microg/l concentrations. Special attention was given to the determination of polar MTBE degradation products, TBA and TBF, since not much data on method performance and environmental levels are given on these compounds in groundwater. All samples analysed contained MTBE at levels between 0.3 and 70 microg/l. Seven contaminated hot spots were identified with levels up to US Environmental Protection Agency drinking water advisory (20-40 microg/l) and a maximum concentration of 670 microg/l (doubling the Danish suggested toxicity level of 350 microg/l). Samples with high levels of MTBE contained 0.1-60 microg/l of TBA, indicating (but not proving) in situ degradation of parent compound. In all cases, BTEX was at low concentrations or not detected showing less solubility and persistence than MTBE. This fact confirms the suitability of MTBE as a tracer or indicator of long-term gasoline contamination than the historically used BTEX. PMID:12800934

Rosell, Mònica; Lacorte, Sílvia; Ginebreda, Antoni; Barceló, Damià

2003-05-01

81

Simultaneous determination of methyl tert-butyl ether, its degradation products and other gasoline additives in soil samples by closed-system purge-and-trap gas chromatography-mass spectrometry.  

PubMed

A new protocol for the simultaneous determination of methyl tert-butyl ether (MTBE); its main degradation products: tert-butyl alcohol (TBA) and tert-butyl formate (TBF); other gasoline additives, oxygenate dialkyl ethers: ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE); aromatics: benzene, toluene, ethylbenzene and xylenes (BTEX) and other compounds causing odour events such as dicyclopentadiene (DCPD) and trichloroethylene (TCE) in soils has been developed. On the basis of US Environmental Protection Agency (EPA) method 5035A, a fully automated closed-system purge-and-trap coupled to gas chromatography/mass spectrometry (P&T-GC/MS) was optimised and permitted to detect microg/kg concentrations in solid matrices avoiding losses of volatile compounds during operation processes. Parameters optimised were the sampling procedure, sample preservation and storage, purging temperature, matrix effects and quantification mode. Using 5 g of sample, detection limits were between 0.02 and 1.63 microg/kg and acceptable method precision and accuracy was obtained provided quantification was performed using adequate internal standards. Soil samples should be analysed as soon as possible after collection, stored under -15 degrees C for not longer than 7 days if degradation products have to be analysed. The non-preservative alternative (empty vial) provided good recoveries of the most analytes when freezing the samples up to 7 day holding time, however, if biologically active soil are analysed the preservation with trisodium phosphate dodecahydrate (Na(3)PO(4).12H(2)O or TSP) is strongly recommended more than sodium bisulphate (NaHSO(4)). The method was finally applied to provide threshold and background levels of several gasoline additives in a point source and in sites not influenced by gasoline spills. The proposed method provides the directions for the future application on real samples in current monitoring programs at gasoline pollution risk sites where till now little monitoring data for MTBE in soils are available. PMID:16904119

Rosell, Mònica; Lacorte, Sílvia; Barceló, Damià

2006-11-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

83

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

SciTech Connect

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

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

1999-09-01

84

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

PubMed Central

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

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

2001-01-01

85

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

PubMed

The optimized molecular structure and corresponding vibrational assignments of 2-tert-butyl-5-methyl anisole (TBMA) have been investigated using density functional theory (DFT)/B3LYP with 6-31G(d,p) and 6-311++G(d,p) basis sets investigation of the relative orientation of the methoxy group has shown two conformers (O-cis) and (O-trans) exist. The vibrational analysis of the stable conformer of the title compound is performed by means of infrared absorption and Raman spectroscopy in combination with theoretical simultaneously. The natural bond orbital (NBO) analysis is useful to understand the intra-molecular hyper conjugative interaction lone pair and ?(?)(CC), ?(?)(CH) bond orbital. HOMO and LUMO energies show that charge transfer occurs in the molecule, therefore; HOMO, LUMO and molecular electrostatic potential (MEP) were calculated and analyzed. (1)H and (13)C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data. The thermodynamic functions of TBMA were calculated by B3LYP/6-311+G(d,p) basis set. PMID:25448946

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

2015-02-01

86

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

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

Ghasemi, Sahar; Ahmadi, Farhad

2014-11-15

87

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

PubMed

The symmetric title mol-ecule, [Hf(C26H40N4Si)Cl4], lies about a twofold rotation axis. The Hf(IV) and Si atoms lie on the rotation axis with all other atoms being in general positions. The Hf(IV) atom is six-coordinated by two N atoms from the N (2),N (2')-(di-methyl-silanedi-yl)bis-(N-tert-butyl-3-methyl-benz-imid-amidate) ligand and four Cl(-) ions in a slightly distorted octa-hedral geometry. The two amidinate moieties are connected through the central Si atom with Si-N bond length of 1.762?(3)?Å, generating the characteristic N-C-N-Si-N-C-N skeleton of a silyl-linked ansa-bis-(amidine) species. PMID:24454166

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

2013-11-13

88

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

PubMed Central

The symmetric title mol­ecule, [Hf(C26H40N4Si)Cl4], lies about a twofold rotation axis. The HfIV and Si atoms lie on the rotation axis with all other atoms being in general positions. The HfIV atom is six-coordinated by two N atoms from the N 2,N 2?-(di­methyl­silanedi­yl)bis­(N-tert-butyl-3-methyl­benz­imid­amidate) ligand and four Cl? ions in a slightly distorted octa­hedral geometry. The two amidinate moieties are connected through the central Si atom with Si—N bond length of 1.762?(3)?Å, generating the characteristic N—C—N—Si—N—C—N skeleton of a silyl-linked ansa-bis­(amidine) species. PMID:24454166

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

2013-01-01

89

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

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

Delzer, Gregory C.; Ivahnenko, Tamara

2003-01-01

90

Safety of same-day sequential extracorporeal shock wave lithotripsy and dissolution of gallstones by methyl tert-butyl ether in dogs.  

PubMed

Passage of stone fragments after extracorporeal shock wave lithotripsy (ESWL) of gallstones has resulted in biliary colic, duct obstruction, and pancreatitis in some patients. Rapid dissolution of these fragments with methyl tert-butyl ether (MTBE) may prevent such side effects and achieve complete clearance of gallstones within hours rather than several months to a year or longer. This study examines the safety of same-day ESWL fragmentation and MTBE dissolution of surgically implanted human gallstones in 15 dogs. The animals were randomly assigned to one of four treatment groups to assess MTBE absorption from the gallbladder and to observe hematology and chemistry profiles after 0, 400, and 1,200 shock waves from a lithotriptor followed by MTBE dissolution therapy. They were sacrificed either immediately after treatment (12 dogs) or 2 weeks later (3 dogs). The results demonstrated that although ESWL causes moderate trauma to the gallbladder, this did not result in increased MTBE absorption or histologic evidence of mucosal disruption. Blood profiles demonstrated an increase in only the level of aspartate aminotransferase. The three dogs that were sacrificed 2 weeks after the combined treatment had no residual evidence of gallbladder injury or remaining stone material. In all animals, severe injury occurred where shock waves passed through lung or air-filled colon. This study suggests that same-day sequential fragmentation of gallstones by ESWL followed by dissolution of stone fragments with use of MTBE may be associated with only mild to moderate and reversible gallbladder trauma and can rapidly achieve clearance of gallstones. PMID:2255218

Peine, C J; May, G R; Nagorney, D M; Patterson, D E; Segura, J W; Thistle, J L

1990-12-01

91

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...

92

1,3-Alternate conformer 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra­kis­(4-methyl­sulfanylbenz­yloxy)-2,8,14,20-tetra­thia­calix[4]arene  

PubMed Central

The title thia­calix[4]arene derivative, C72H80O4S8, adopts a 1,3-alternate conformation, where the four 4-methyl­sul­fan­yl­benzyl groups are located alternately at the two sides of a virtual plane defined by the four bridging S atoms. In the crystal, there are no significant inter­molecular inter­actions present. Some of the peripheral tert-butyl and methyl­sulfanyl groups are disordered over two positions. A region of disordered electron density, occupying voids of ca 700?Å3 for an electron count of 124, was treated using the SQUEEZE routine in PLATON [Spek (2009 ?). Acta Cryst. D65, 148–155]. PMID:24046595

Gao, Qingsong; Xie, Dexun; An, Delie

2013-01-01

93

4-tert-Butyl­pyridinium chloride–4,4?-(propane-2,2-di­yl)bis­(2,6-di­methyl­phenol)–toluene (2/2/1)  

PubMed Central

In the title solvated salt, C9H14N+·Cl?·C19H24O2·0.5C7H7, two mol­ecules of 4,4?-(propane-2,2-di­yl)bis­(2,6-di­methyl­phenol) 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-butyl­pyridinium cation, giving a cyclic hydrogen-bonded entity centred at 1/2, 1/2, 1/2. The toluene solvent mol­ecule 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

Nielson, Alastair J.; Waters, Joyce M.

2014-01-01

94

7-[(3,5-Di-tert-butyl-2-hy­droxy­benzyl­idene)amino]-4-methyl-2H-chromen-2-one  

PubMed Central

The title compound, C25H29NO3, is a Schiff base derivative of coumarin 120. There are two structurally similar but crystallographically independent mol­ecules in the asymmetric unit. Both mol­ecules exist in E configurations with respect to the C=N double bonds. The dihedral angles between the coumarin and 3,5-di-tert-butyl-2-hy­droxy­benzyl­idene ring planes are 4.62?(7) and 14.62?(7)° for the two mol­ecules. Intra­molecular O—H?N hydrogen bonding involving the O—H groups and the azomethine N atoms generate S(6) rings. In the crystal structure, independent mol­ecules are linked by C—H?? inter­actions, with groups of four mol­ecules stacked along the c axis. PMID:21587568

Aazam, Elham S.; Büyükgüngör, Orhan

2010-01-01

95

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

Methyl tert-butyl ether (MTBE) was detected in source water used by 8.7 percent of randomly selected community water systems (CWSs) in the United States at concentrations that ranged from 0.2 to 20 micrograms per liter (?g/L). The Random Survey conducted by the U.S. Geological Survey, in cooperation with the Metropolitan Water District of Southern California and the Oregon Health & Science University, was designed to provide an assessment of the frequency of detection, concentration, and distribution of MTBE, three other ether gasoline oxygenates, and 62 other volatile organic compounds (VOCs) in ground- and surface-water sources used for drinking-water supplies. The Random Survey was the first of two components of a national assessment of the quality of source water supplying CWSs sponsored by the American Water Works Association Research Foundation. A total of 954 CWSs were selected for VOC sampling from the population of nearly 47,000 active, self-supplied CWSs in all 50 States, Native American Lands, and Puerto Rico based on a statistical design that stratified on CWS size (population served), type of source water (ground and surface water), and geographic distribution (State).At a reporting level of 0.2 ?g/L, VOCs were detected in 27 percent of source-water samples collected from May 3, 1999 through October 23, 2000. Chloroform (in 13 percent of samples) was the most frequently detected of 42 VOCs present in the source-water samples, followed by MTBE. VOC concentrations were generally less than 10 ?g/L?95 percent of the 530 detections?and 63 percent were less than 1.0 ?g/L. Concentrations of 1,1-dichloroethene, tetrachloroethene, trichloroethene, vinyl chloride, and total trihalomethanes (TTHMs), however, exceeded drinking-water regulations in eight samples.Detections of most VOCs were more frequent in surface-water sources than in ground-water sources, with gasoline compounds collectively and MTBE individually detected significantly more often in surface water. Use of personal and commercial motorized watercraft on surface-water bodies that are drinking-water sources is probably the reason for the elevated detections of gasoline contaminants relative to ground water. MTBE detections demonstrated a seasonal pattern with more frequent detections in surface water in summer months, which is consistent with seasonal watercraft use.The detection frequency of most VOCs was significantly related to urban land use and population density. Detections of any VOC, non-trihalo-methane compounds, gasoline compounds collectively, the specific gasoline compounds benzene, toluene, ethylbenzene, and xylenes (BTEX), MTBE, solvents, and refrigerants were significantly greater in areas with more than 60 percent urban land use and (or) population density greater than 1,000 people per square mile than in source waters from less urbanized or lower population-density areas. MTBE detections were five times more frequent in source waters from areas with high MTBE use than in source waters from low or no MTBE use, but, unlike other gasoline compounds, MTBE detections were not significantly related to the density of gasoline storage tanks near drinking-water sources.

Grady, Stephen J.

2002-01-01

96

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

USGS Publications Warehouse

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.

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

1999-01-01

97

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

PubMed Central

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

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

2007-01-01

98

Study of fuel oxygenates solubility in aqueous media as a function of temperature and tert-butyl alcohol concentration.  

PubMed

Methyl tert-butyl ether (MTBE) is the most widely used oxygenate in gasoline blending and has become one of the world's most widespread groundwater and surface water pollutants. Alternative oxygenates to MTBE, namely ethyl tert-butyl ether (ETBE), tert-amyl ether (TAME) and diisopropyl ether (DIPE) have been hardly studied yet. The solubility of these chemicals is a key thermodynamic information for the assessment of the fate and transport of these pollutants. This work reports experimental data of water solubility at the range from 278.15 to 313.15K and atmospheric pressure of ethers used in fuels (MTBE, ETBE, TAME and DIPE) due to the strong influence of temperature on its trend. From the experimental data, temperature dependent polynomials were fitted, thermodynamic parameters were calculated and theoretical models were used for prediction. Finally, the tert-butyl alcohol (TBA) influence in the solubility of MTBE and ETBE in aqueous media was studied. PMID:18299142

Gonzalez-Olmos, R; Iglesias, M

2008-05-01

99

Effect of Parameters on Oxychlorination of Tert-Butyl Ethers  

PubMed Central

The effect of concentration, molar ratios of reagents, pH, and temperature on formation of chloro-organic products in reaction of tert-butyl ethers with chloride ions and hydrogen peroxide has been determined. A significant effect of Cl? ions and H2O2 molar ratios on the rate of chloro-organic product formation has been observed. Studies on oxychlorination of tert-butylethyl ether (ETBE) at pH 7, 3.5, and 2.5 have been carried out. It was found that introduction of hydronium ions into the reaction system considerably hastened the process of chloro-organic product formation. Hydronium ions contribute to the formation of the reactive tert-butyl carbocation, which undergoes secondary reactions in the presence of reactive forms of chlorine and oxygen. Moreover, the effect of temperature on ETBE (tert-butylethyl ether) and MTBE (tert-butylmethyl ether) conversions was verified. The reactions of MTBE and ETBE oxychlorination were carried out at temperatures of 5°C, 20°C, and 35°C. PMID:19696944

Gaca, Jerzy; Gackowska, Alicja; Belt, Natalia

2008-01-01

100

Effect of Parameters on Oxychlorination of Tert-Butyl Ethers.  

PubMed

The effect of concentration, molar ratios of reagents, pH, and temperature on formation of chloro-organic products in reaction of tert-butyl ethers with chloride ions and hydrogen peroxide has been determined. A significant effect of Cl(-) ions and H(2)O(2) molar ratios on the rate of chloro-organic product formation has been observed. Studies on oxychlorination of tert-butylethyl ether (ETBE) at pH 7, 3.5, and 2.5 have been carried out. It was found that introduction of hydronium ions into the reaction system considerably hastened the process of chloro-organic product formation. Hydronium ions contribute to the formation of the reactive tert-butyl carbocation, which undergoes secondary reactions in the presence of reactive forms of chlorine and oxygen. Moreover, the effect of temperature on ETBE (tert-butylethyl ether) and MTBE (tert-butylmethyl ether) conversions was verified. The reactions of MTBE and ETBE oxychlorination were carried out at temperatures of 5 degrees C, 20 degrees C, and 35 degrees C. PMID:19696944

Gaca, Jerzy; Gackowska, Alicja; Belt, Natalia

2008-07-01

101

Reactivities of substituted ?-phenyl-N-tert-butyl nitrones.  

PubMed

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

Rosselin, Marie; Choteau, Fanny; Zéamari, Kamal; Nash, Kevin M; Das, Amlan; Lauricella, Robert; Lojou, Elisabeth; Tuccio, Béatrice; Villamena, Frederick A; Durand, Grégory

2014-07-18

102

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

NASA Astrophysics Data System (ADS)

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

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

2002-06-01

103

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

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.

Grady, Stephen J.; Casey, George D.

1999-01-01

104

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

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 [?C] of ?0.37‰ ± 0.05‰ and no significant hydrogen isotopic enrichment factor [?H]) observed in microcosm experiments to expression of the ethB gene encoding a cytochrome P450 monooxygenase able to catalyze the oxidation of MTBE in biofilm samples both from the microcosms and directly from the ponds. 16S rRNA-specific primers revealed the presence of a sequence 100% identical to that of Methylibium petroleiphilum PM1, a well-characterized MTBE degrader. However, neither expression of the mdpA genes encoding the alkane hydroxylase-like enzyme responsible for MTBE oxidation in this strain nor the related MTBE isotope fractionation pattern produced by PM1 could be detected, suggesting that this enzyme was not active in this system. Additionally, observed low inverse fractionation of carbon (?C of +0.11‰ ± 0.03‰) and low fractionation of hydrogen (?H of ?5‰ ± 1‰) in laboratory experiments simulating MTBE stripping from an open surface water body suggest that the application of CSIA in field investigations to detect biodegradation may lead to false-negative results when volatilization effects coincide with the activity of low-fractionating enzymes. As shown in this study, complementary examination of expression of specific catabolic genes can be used as additional direct evidence for microbial degradation activity and may overcome this problem. PMID:21148686

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

2011-01-01

105

he increasing frequency of detection of the widely used gasoline additive methyl tert-  

E-print Network

T he increasing frequency of detection of the widely used gasoline additive methyl tert- butyl ether (MTBE) in both ground and sur- face waters is receiving much attention from the media and 10% of community drinking water sup- plies in high MTBE use areas show at least detectable

106

Aerobic degradation of ethyl-tert-butyl ether by a microbial consortium: selection and evaluation of biodegradation ability.  

PubMed

A microbial consortium that degrades ethyl-tert-butyl ether (ETBE) as the sole source of carbon and energy under aerobic conditions was selected from a gasoline-polluted soil. This consortium consists of a variety of microorganisms with a predominance of filamentous morphology. Degradation of ETBE was found to be solely related to bacterial activity. After prolonged cultivation followed by successive transfers, the consortium's degradation ability was improved and reached a specific degradation rate of 95 mg/g(protein)/h (about 146 mg/g(dry wt)/h). This exceeds the previously reported rates in the literature for ETBE-degrading microorganisms as pure or mixed cultures. Furthermore, a stoichiometric balance of chemical oxygen demand (COD) removal and oxygen uptake with ETBE removal provides indirect evidence of complete degradation. The consortium's activity was not inhibited by high ETBE concentrations (< or = 1,600 mg/L), and large inoculum sizes (> or = 120 mg(protein)/L) were desirable for a faster and complete degradation of ETBE. The enriched consortium was also able to completely degrade methyl-tert-butyl ether (MTBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA). both alone and in mixture with ETBE, without any measurable release of major degradation intermediates. In each case, MTBE and TAME exhibited the most significant resistance to degradation while TBA was rapidly degraded. PMID:12371480

Kharoune, Mourad; Kharoune, Lynda; Lebault, Jean-Michael; Pauss, André

2002-10-01

107

Synthesis of 1-tert-butyl-4-chloropiperidine: generation of an N-tert-butyl group by the reaction of a dimethyliminium salt with methylmagnesium chloride.  

PubMed

Two efficient routes to 1-tert-butyl-4-chloropiperidine are described. In the first route, the key thionyl chloride mediated chlorination reaction features the use of tetrabutylammonium chloride as an additive that effectively suppresses the formation of an elimination-derived side product. In the second route, a novel alternative synthesis of 1-tert-butyl-4-chloropiperidine was developed in which the tertiary butyl group on the nitrogen is efficiently generated through the addition of methylmagnesium chloride to a dimethyliminium salt in 71% overall yield. PMID:15730326

Amato, Joseph S; Chung, John Y L; Cvetovich, Raymond J; Gong, Xiaoyi; McLaughlin, Mark; Reamer, Robert A

2005-03-01

108

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

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 probability of MTBE contamination. Ground water from public-supply wells and shallow ground water underlying urban land-use areas has a greater probability of MTBE contamination compared to ground water from domestic wells and ground water underlying rural land-use areas.

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

2004-01-01

109

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

PubMed

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

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

2007-06-01

110

Hydrogen Atom Reactivity toward Aqueous tert-Butyl Alcohol  

SciTech Connect

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.

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

2012-02-09

111

catena-Poly[[di-tert-butyl­tin(IV)]-?-oxalato  

PubMed Central

The title compound, [Sn(C4H9)2(C2O4)]n, an unexpected side product in the reaction of di-tert-butyl­tin(IV) oxide with nitric acid, represents the first diorganotin(IV) oxalate to be structurally characterized. The SnIV atom of the one-dimensional coordination polymer is located on a mirror plane and is coordinated by two chelating oxalate ions with two rather different Sn—O bond lengths of 2.150?(1) and 2.425?(1)?Å, and two t-butyl groups with Sn—C bond lengths of 2.186?(2) and 2.190?(2)?Å. The coordination polyhedron around the SnIV atom is a distorted tetra­gonal disphenoid. The centrosymmetric oxalate ion also has an asymmetric coordination geometry, as reflected by the two slightly different C—O bond lengths of 1.242?(2) and 1.269?(2)?Å. The chains of the polymer propagate along the b-axis direction. Only van der Waals inter­actions are observed between the chains. PMID:24826096

Reichelt, Martin; Reuter, Hans

2014-01-01

112

catena-Poly[[di-tert-butyl-tin(IV)]-?-oxalato].  

PubMed

The title compound, [Sn(C4H9)2(C2O4)] n , an unexpected side product in the reaction of di-tert-butyl-tin(IV) oxide with nitric acid, represents the first diorganotin(IV) oxalate to be structurally characterized. The Sn(IV) atom of the one-dimensional coordination polymer is located on a mirror plane and is coordinated by two chelating oxalate ions with two rather different Sn-O bond lengths of 2.150?(1) and 2.425?(1)?Å, and two t-butyl groups with Sn-C bond lengths of 2.186?(2) and 2.190?(2)?Å. The coordination polyhedron around the Sn(IV) atom is a distorted tetra-gonal disphenoid. The centrosymmetric oxalate ion also has an asymmetric coordination geometry, as reflected by the two slightly different C-O bond lengths of 1.242?(2) and 1.269?(2)?Å. The chains of the polymer propagate along the b-axis direction. Only van der Waals inter-actions are observed between the chains. PMID:24826096

Reichelt, Martin; Reuter, Hans

2014-04-01

113

Influence of cobalt(III) dimethyldithiocarbamate complexes on styrene polymerization initiated by tert -butyl perbenzoate  

Microsoft Academic Search

Kinetic features of radical polymerization of styrene initiated by tert-butyl perbenzoate in the presence of tris(N,N-dimethyldithiocarbamato)cobalt(III) (CoL3) and its adduct with iodine (CoL3 · 2I2) were studied. The optimal concentration ratios of the activators and tert-butyl perbenzoate, providing fast styrene polymerization at 338–368 K, were determined.

N. V. Khitrich; I. I. Seifullina; Yu. K. Epimakhov; P. A. Ivanchenko

2006-01-01

114

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

PubMed

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

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

2010-06-15

115

Stability testing of the plastics additives 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-ethoxy-2-ethyloxanilide (tinuvin 312) and 2,2'-methylenebis(4-methyl-t-tert-butyl phenol) in aqueous and fatty food simulants.  

PubMed

The stability of five additives used in the manufacture of plastics materials intended to be in contact with foodstuffs was tested in two EU aqueous food simulants (3% acidic acid and 15% ethanol), in olive oil and in two alternative fatty food simulants (95% ethanol and isooctane) under various conditions of temperature and time established for migration testing. The additives were the following: 2,4-dihydroxybenzophenone, 2-2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-ethoxy-2-ethyloxanilide and 2,2'-methylenebis(4-methyl-6-tert-butyl phenol). The additives were spiked into the simulants at their anticipated Specific Migration Limit (SML) and submitted to time-temperature conditions used in the migration testing. The test samples were analysed against fresh samples of the additives spiked at the same concentration just before the analysis. All samples were analysed with HPLC, using an ODS2 column and mobile phase of methanol-water or acetonitrile-water. The results were statistically evaluated by applying a two-tailed F-test (at 95% confidence level) to the variances and onetailed t-test (at 90% confidence level) to the means of the control and the test samples. The statistical evaluation of the results showed that the additives were stable in all simulants within the statistical allowances. Only the 2.2'-methylenebis(4-methyl-6-tert-butyl phenol) showed a loss of about 20% in olive oil and 17% in 3% aqueous acetic acid. The results of the study will be used by the Commission, DG III-C-I. to help to determine whether legislative restrictions in the additives Directive should be applied to the finished material or article (QM) or to migration to simulants (SML). PMID:9666896

Spyropoulos, D V

1998-04-01

116

A cataluminescence gas sensor based on nanosized V2O5 for tert-butyl mercaptan.  

PubMed

This work proposed a gas sensor for the determination of tert-butyl mercaptan, one of the highly toxic volatile sulfur compounds, which was based on cataluminescence emission during its catalytic oxidation on the surface of nanosized V(2)O(5). The cataluminescence characteristics and the optimum conditions, including the morphology of sensing material, the wavelength of cataluminescence emission, the oxygen flow rate and working temperature were investigated in detail. Under the optimized conditions, the calibration curve of the relative cataluminescence intensity versus the concentration of tert-butyl mercaptan vapor was made, with the linear range of 5.6-196 microg mL(-1) and the detection limit of 0.5 microg mL(-1) (S/N=3). The relative standard deviation (R.S.D.) (n=5) of relative cataluminescence intensity for 84 microg mL(-1) tert-butyl mercaptan was 3.6%. There is no or weak response to some common substances, such as formic acid, alcohol (methanol, ethanol, propanol, isopropanol, n-butanol, isoamyl alcohol), o-dichlorobenzene, acetonitrile, ethyl acetate, aldehyde (formaldehyde, acetaldehyde and propanal), 1,2-dichloroethane and ammonia. Furthermore, the proposed sensor was successfully used for determining tert-butyl mercaptan in four artificial samples, with a good recovery. The results demonstrated that the proposed gas sensor had a promising capability for the tert-butyl mercaptan in routine monitoring. PMID:20602962

Zhang, Huili; Zhang, Lichun; Hu, Jing; Cai, Pingyang; Lv, Yi

2010-07-15

117

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

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

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

2001-01-01

118

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

USGS Publications Warehouse

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.

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

1956-01-01

119

Depigmentation with tert-butyl hydroquinone using black guinea pigs.  

PubMed

tert-Butyl hydroquinone (TBHQ) has important and functional uses in consumer and commercial applications, some of which involve human exposure primarily through dermal contact. To assist in the safety evaluation of TBHQ, this study was conducted to determine whether TBHQ would produce changes in skin pigmentation after repeated dermal application to black guinea pigs. Hydroquinone (HQ) and hydroquinone monomethyl ether (HQMME) were used as positive controls. TBHQ and HQ were tested at concentrations of 0.1, 1.0 and 5.0%, while HQMME was tested at a concentration of 10.0%. Groups of five males and five females were dosed with TBHQ, HQ, or the vehicle (hydrophilic ointment) daily (M-F) for 13 weeks. In addition, animals (five males, five females) treated with HQMME received 13 doses over a 3-week period. The application site was evaluated weekly for degree of pigmentation loss and irritation. Twenty-four hours after final application, sites were evaluated for depigmentation, irritation and hyperpigmentation. Subsequently, the application site was depilated and re-evaluated for the same endpoints. Repetitive exposure to concentrations of 1.0% and 5.0% TBHQ and HQ were slightly to moderately irritating, while 0.1% of each of these test materials produced only weak irritant responses. No irritant responses to hydrophilic ointment were observed and HQMME produced weak irritant responses after 2 weeks. Neither 0.1% TBHQ nor HQ produced depigmentation, while 20% of animals dosed with 1.0% TBHQ and 30% of animals dosed with 1.0% HQ had spotty or uniform loss of pigment at the site of treatment. Approximately 40% of animals dosed with 5% TBHQ or HQ were depigmented at the treatment site at the final evaluation. HQMME produced complete depigmentation of the skin and hair in all animals. Hyperpigmentation of the treatment site was observed in 80-100% of animals in all groups (with the exception of HQMME-treated animals, treated for only 3 weeks), which may be attributable to the use of hydrophilic ointment as the vehicle, the application procedure, or simply clipping hair from the skin. Thus, this study showed that TBHQ causes depigmentation in black guinea pigs at concentrations of 1% or greater, but that a no-effect threshold for this endpoint exists at a concentration between 0.1 and 1.0%. PMID:10227740

Patrick, E; Juberg, D R; O'Donoghue, J; Maibach, H I

1999-01-01

120

Quantitative determination of butylated hydroxyanisole, butylated hydroxytoluene, and tert -butyl hydroquinone in oils, foods, and biological fluids by high-performance liquid chromatography with fluorometric detection  

Microsoft Academic Search

Concentrations of synthetic antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone were quantified using a high-performance liquid chromatograph with spectrofluorometric detector. The antioxidants\\u000a were separated and eluted on a reversed-phase column by gradient of a mixture of H2O\\/acetonitrile\\/acetic acid (66.5: 28.5?5, by vol) and a mixture of acetonitrile\\/acetic acid (95?5, vol\\/vol). The eluants were\\u000a monitored at emission and excitation wavelengths

Vivienne V. Yankah; Hideki Ushio; Toshiaki Ohshima; Chiaki Koizumi

1998-01-01

121

Methyl Tertiary Butyl Ether (MTBE): Drinking Water  

NSDL National Science Digital Library

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

122

Tandem cyclization of ?-cyano ?-alkynyl aryl ketones induced by tert-butyl hydroperoxide and tetrabutylammonium iodide.  

PubMed

The radical cascade protocol of the ?-cyano ?-TMS/aryl-capped alkynyl aryl ketones promoted by tert-butyl hydroperoxide under catalysis with tetrabutylammonium iodide in refluxing benzene has been developed, leading to the construction of a variety of highly functionalized [6,6,5] tricyclic frameworks in an efficient manner. PMID:23190145

Wong, Ying-Chieh; Tseng, Chen-Tso; Kao, Tzu-Ting; Yeh, Yu-Cheng; Shia, Kak-Shan

2012-12-01

123

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

PubMed Central

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

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

2006-01-01

124

The alkyl tert-butyl ether intermediate 2-hydroxyisobutyrate is degraded via a novel cobalamin-dependent mutase pathway.  

PubMed

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

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

2006-06-01

125

Methyl Tertiary Butyl Ether (MTBE) Groundwater Contamination  

NSDL National Science Digital Library

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

126

Comparative metabolism of 3,5-di-tert-butyl-4-hydroxytoluene (BHT) in mice and rats.  

PubMed

In male and female DDY/Slc mice given single oral doses (20 or 500 mg/kg body weight) of 3,5-di-tert-butyl-4-hydroxytoluene (BHT) labelled with 14C at the p-methyl group, 14C was distributed mainly in the stomach, intestines, liver and kidney, and then excreted in the urine, faeces and expired air. During the 7 days after treatment, 41-65, 26-50 and 6-9% of the 14C dose was excreted in faeces, urine and expired air, respectively, and the total recovery was 96-98%. Levels of 14C in 21 male and 22 female tissues 7 days after treatment were less than 1 microgram BHT equivalents/g tissue (ppm) in mice given 20 mg/kg and less than 11 ppm in mice given 500 mg/kg. When [14C]BHT was given orally to male mice at 20 mg/kg/day for 10 days, 14C was rapidly excreted and did not exhibit any tendency to accumulate in any tissues. Thin-layer chromatography and high-performance liquid chromatography analyses showed that more than 43 metabolites were present in the urine and faeces of both species, and all of these were identified to determine metabolic pathways for BHT in mice and rats. Major metabolic reactions of [14C]BHT in mice were the oxidation of the p-methyl group attached to the benzene ring and of the tert-butyl groups. The products from the latter reaction were cyclized to some extent by reacting with the adjacent phenolic OH group to give hemiacetals or lactones. The carboxyl derivatives from the p-methyl oxidation were conjugated with glucuronic acid. When single oral doses of 20 or 500 mg [14C]BHT/kg were given to male Sprague-Dawley rats, metabolites similar to those in mice were found. However, the major biotransformation was oxidation of the p-methyl group, and oxidation of the tert-butyl groups was a minor reaction in rats. PMID:6539284

Matsuo, M; Mihara, K; Okuno, M; Ohkawa, H; Miyamoto, J

1984-05-01

127

Kinetics of proton transfer from tetra(4-nitro-5- tert-butyl)phthalocyanine to nitrogen-containing bases in benzene  

NASA Astrophysics Data System (ADS)

The acid-basic interaction between tetra(4-nitro-5- tert-butyl)phthalocyanine and pyridine, 2-methylpyridine, morpholine, piperidine, n-butylamine, diethylamine, and triethylamine in benzene is studied. It is found that the intermolecular transfer of protons of NH groups from tetra(4-nitro-5- tert-butyl)phthalocyanine to morpholine and diethylamine is characterized by unusually low values of the reaction constant rates. The effect of the structure of tetra(4-nitro-5- tert-butyl)phthalocyanine and tetra(3-nitro-5- tert-butyl)phthalocyanine, and of the nature of the base on the kinetic parameters of acid-base interaction is demonstrated. A structure is proposed for complexes with the transfer of displaced phthalocyanines' protons. It is found that they undergo decomposition over time.

Petrov, O. A.; Kuzmina, E. L.; Maizlish, V. E.; Rodionov, A. V.

2014-01-01

128

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

NASA Astrophysics Data System (ADS)

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 ?M 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.

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

1984-03-01

129

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

Microsoft Academic Search

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

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

2000-01-01

130

Inhibitory effect of berberine on tert -butyl hydroperoxide-induced oxidative damage in rat liver  

Microsoft Academic Search

Berberine, a main protoberberine component of Coptidis Rhizoma, was studied for the mechanism of its inhibitory effects on the tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity and lipid peroxidation in rat liver. In the preliminary study, berberine expressed an antioxidant property by its capacity for quenching the free radicals of 1,1-diphenyl-2-picrylhydrazyl (DPPH). Further investigations were conducted using t-BHP-induced cytotoxicity in rat primary hepatocytes

Jin-Ming Hwang; Chau-Jong Wang; Feu-Pi Chou; Tsui-Hwa Tseng; Yih-Shou Hsieh; Wea-Lung Lin; Chia-Yih Chu

2002-01-01

131

Experimental Pathology Laboratories, Inc. Methyl-Tertiary-Butyl Ether  

E-print Network

Experimental Pathology Laboratories, Inc. Methyl-Tertiary-Butyl Ether C00117F/00117-69 AMENDED PATHOLOGY QUALITY ASSESSMENT REVIEW AND PWG Toxicology Program Research Triangle Park, NC 27709 Submitted by: Experimental Pathology Laboratories, Inc

Baker, Chris I.

132

Regioselective acylation of disaccharides in tert-butyl alcohol catalyzed by Candida antarctica lipase.  

PubMed

The acylation of several disaccharides by ethyl butanoate and ethyl dodecanoate was catalyzed by Candida antarctica lipase in tert-butyl alcohol, at temperatures ranging from 40 degrees to 82 degrees C (reflux temperature). The relative reaction rates of the various disaccharides were directly related to their solubility. The primary products were the monoesters derived from acylation of the primary alcohol groups. At higher conversions diesters were formed, and the ratio of diester to monoester was markedly dependent on the structure of the disaccharide. Thus, reaction of maltose with ethyl dodecanoate in refluxing tert-butyl alcohol afforded the 6'-monododecanoate even at high conversions. Trehalose, in contrast, afforded the 6,6'-diester. Acylation of the less soluble sucrose and lactose was much slower, but a moderate (37%) conversion of sucrose was observed after a prolonged reaction time (7 days). A number of other lipases and proteases were tested but C. antarctica lipase was unique in catalyzing the acylation of sucrose in refluxing tert-butyl alcohol. (c) 1996 John Wiley & Sons, Inc. PMID:18623584

Woudenberg-van Oosterom, M; van Rantwijk, F; Sheldon, R A

1996-02-01

133

Degradation pathway of 2,5-di- tert-butyl-1,4-dimethoxybenzene at high potential  

Microsoft Academic Search

2,5-Di-tert-butyl-1,4-dimethoxybenzene is a redox shuttle for overcharge protection of LiFePO4-based lithium-ion batteries with a working potential lower than 4.2V versus Li+\\/Li. However, an irreversible decomposition occurs when the working potential is higher than 4.2V versus Li+\\/Li. 2,3,5,6-Tetrafluoro-1,4-di-tert-butoxybenzene was also investigated as a model molecule to further understand the possible degradation pathway of 2,5-di-tert-butyl-1,4-dimethxybenzene. The experimental results strongly suggest that the

Zonghai Chen; K. Amine

2007-01-01

134

O-Benzyl-N-tert-butoxycarbonyl-N-methyl-L-tyrosine.  

PubMed

The crystal structure of the title compound, alternatively called 3-[4-(benzyloxy)phenyl]-2-(N-tert-butoxycarbonyl-N-methylamino)propionic acid, C(22)H(27)NO(5), has been studied in order to examine the role of N-methylation as a determinant of peptide conformation. The conformation of the tert-butoxycarbonyl group is trans-trans. The side chain has a folded conformation and the two phenyl rings are effectively perpendicular to one another. The carboxylate hydroxyl group and the urethane carbonyl group form a strong intermolecular O[bond]H...O hydrogen bond. PMID:12050440

Jankowska, Elzbieta; Gilski, Miros?aw; Jaskólski, Mariusz; Grzonka, Zbigniew; ?ankiewicz, Leszek

2002-06-01

135

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

USGS Publications Warehouse

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.

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

136

Thermal and photochemistry of tert-butyl iodide on rutile TiO2(110).  

PubMed

The thermal and photochemistry of tert-butyl iodide (t-buI) dosed at 100 K on rutile TiO2(110) has been studied using isothermal and temperature programmed desorption mass spectrometry. Nondissociative adsorption and desorption dominate the thermal behavior with dose-dependent t-buI desorption peaks at nominally 220 and 150 K. Ultraviolet photochemistry occurs readily, but the behavior of submonolayers and multilayers differ qualitatively. Ejection of t-buI and i-C4H8 dominate during submonolayer photolysis at 100 K. Multilayer photolysis results are also dominated by ejection during irradiation, but the t-buI component is strongly suppressed, and the maximum rates of i-C4H8 and HI ejection did not occur at the outset. A mechanistic model capturing the observations involves both direct and substrate-mediated electronic excitation of t-buI. According to this model, ejection of t-buI occurs only from transient substrate-mediated formation of anionic t-buI. For either excitation path, the C-I dissociation probability is significant, and the excited tert-butyl product rearranges readily to form i-C4H8 that is ejected. For any local region where there is multilayer coverage, products formed at the adsorbate-vacuum interface are ejected promptly, but products formed within the multilayer are trapped. Thus, ejection of t-buI is suppressed, and trapped primary photodissociation products, tert-butyl and I, react to either reform t-buI or rearrange to i-C4H8 and HI. The latter two products remain trapped and are subsequently induced to desorb by acquisition of momentum from collisions with subsequently formed translationally excited photodissociation products. PMID:16852898

White, J M; Henderson, Michael A

2005-08-11

137

tert-Butyl N-(thio-phen-2-yl)carbamate.  

PubMed

In the title compound, C9H13NO2S, the dihedral angle between the thiophene ring and the carbamate group is 15.79?(14)°. In the crystal structure, intra-molecular C-H?O inter-actions in tandem with the tert-butyl groups render the packing of adjacent mol-ecules in the [001] direction nearly perpendicular [the angle between adjacent thio-phene rings is 74.83?(7)°]. An inter-molecular N-H?O hydrogen bond gives rise to a chain extending along [001]. The crystal studied was found to be a racemic twin. PMID:24427049

Hsu, Gene C; Singer, Laci M; Cordes, David B; Findlater, Michael

2013-01-01

138

(3S*,4S*,E)-tert-Butyl 3,4-dibromo-5-oxo­cyclo­oct-1-ene­carboxyl­ate  

PubMed Central

The title compound, C13H18Br2O3, was prepared by a bromination reaction of (1E,3Z)-methyl 5-oxocyclo­octa-1,3-diene­carboxyl­ate, which was obtained by an ep­oxy­dation reaction of tert-butyl cyclo­oct-1,3-diene­carboxyl­ate. The crystal structure confirms unequivocally the absolute configuration of both chiral centres to be S. In the crystal, C—H?O inter­actions link the mol­ecules into chains running along the c axis. PMID:22259514

Blanco, Magda; Garrido, Narciso M.; Sanz, Francisca; Diez, David

2012-01-01

139

Crystal structure of catena-poly[[(3-tert-butyl­pyridine-?N)(4-tert-butyl­pyridine-?N)cadmium]-di-?-thio­cyanato-?2 N:S;?2 S:N  

PubMed Central

In the crystal structure of the title compound, [Cd(NCS)2(C9H13N)2]n, the CdII cations are coordinated in a slightly distorted octa­hedral geometry by one 3-tert-butyl­pyridine ligand, one 4-tert-butyl­pyridine ligand and two pairs of translationally-equivalent ?-1,3-bridging thio­cyanate ligands, all of which are in general positions. These ?-1,3-bridging thio­cyante anions bridge the CdII cations, forming chains that propagate parallel to the b axis. PMID:25553011

Werner, Julia; Reinert, Thorben; Jess, Inke; Näther, Christian

2014-01-01

140

Crystal structure of catena-poly[[(3-tert-butyl-pyridine-?N)(4-tert-butyl-pyridine-?N)cadmium]-di-?-thio-cyanato-?(2) N:S;?(2) S:N].  

PubMed

In the crystal structure of the title compound, [Cd(NCS)2(C9H13N)2] n , the Cd(II) cations are coordinated in a slightly distorted octa-hedral geometry by one 3-tert-butyl-pyridine ligand, one 4-tert-butyl-pyridine ligand and two pairs of translationally-equivalent ?-1,3-bridging thio-cyanate ligands, all of which are in general positions. These ?-1,3-bridging thio-cyante anions bridge the Cd(II) cations, forming chains that propagate parallel to the b axis. PMID:25553011

Werner, Julia; Reinert, Thorben; Jess, Inke; Näther, Christian

2014-12-01

141

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

ERIC Educational Resources Information Center

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.…

Hairfield, E. M.; And Others

1985-01-01

142

Quantitative determination of butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone in oils, foods, and biological fluids by high-performance liquid chromatography with fluorometric detection.  

PubMed

Concentrations of synthetic antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tert-butyl hydroquinone were quantified using a high-performance liquid chromatograph with spectrofluorometric detector. The antioxidants were separated and eluted on a reversed-phase column by gradient of a mixture of H2O/acetonitrile/acetic acid (66.5: 28.5:5, by vol) and a mixture of acetonitrile/acetic acid (95:5, vol/vol). The eluants were monitored at emission and excitation wavelengths of 310 and 280 nm, respectively. Calibration curves obtained using peak areas against concentration showed high coefficients of multiple determination (R2 > 0.99) for all antioxidants. Known concentrations of added antioxidant standards were recoverable within 98-99% from oils and over 93% from mouse blood. This method requires minimum sample extraction and purification before analysis and provides a relatively high percentage recovery. The method has been applied successfully for the measurement of antioxidant concentrations in oils, dried foods, and biological fluids. PMID:9870910

Yankah, V V; Ushio, H; Ohshima, T; Koizumi, C

1998-11-01

143

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

PubMed

(2S,4R)- and (2S,4S)-perfluoro-tert-butyl 4-hydroxyproline were synthesized (as Fmoc-, Boc-, and free amino acids) in 2-5 steps. The key step of each synthesis was a Mitsunobu reaction with perfluoro-tert-butanol, which incorporated a perfluoro-tert-butyl group, with nine chemically equivalent fluorines. Both amino acids were incorporated in model ?-helical and polyproline helix peptides. Each amino acid exhibited distinct conformational preferences, with (2S,4R)-perfluoro-tert-butyl 4-hydroxyproline promoting polyproline helix. Peptides containing these amino acids were sensitively detected by (19)F NMR, suggesting their use in probes and medicinal chemistry. PMID:24870929

Tressler, Caitlin M; Zondlo, Neal J

2014-06-20

144

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

PubMed

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

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

2014-08-30

145

Selectivity of large pore zeolites in the alkylation of naphthalene with tert-butyl alcohol: analysis of experimental results by computational modelling  

Microsoft Academic Search

Liquid phase alkylation of naphthalene with tert-butanol has been studied using HY and H-beta zeolites with varying silicon to aluminium ratios. Both series of zeolites underwent efficient activities and high selectivities for the mono- and di-(tert-butyl) derivatives. In all cases, 2-(tert-butyl)naphthalene (2-TBN) was the only monoalkylated product (100%,?-selectivity). Over H-beta zeolites, 2-TBN was obtained as the main product with relatively

Patrice Moreau; Zhongmin Liu; François Fajula; Jacques Joffre

2000-01-01

146

Further metabolism of 3,5-di-tert-butyl-4-hydroxybenzoic acid, a major metabolite of butylated hydroxytoluene, in rats.  

PubMed

The metabolic pathway of butylated hydroxytoluene (BHT) to the ring-oxygenated metabolites 2,6-di-tert-butylhydroquinone (BHQ) and 2,6-di-tert-butyl-p-benzoquinone (BBQ) was examined in rats. After intraperitoneal administration of 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-acid), which had been regarded as one of the major metabolic end-products of BHT, 2,6-di-tert-butylphenol (DBP) and BBQ were identified in the feces by gas chromatography and gas chromatography-mass spectrometry (GC-MS). The biliary excretion of BBQ, BHQ glucuronide and BHT-acid glucuronide was also confirmed by GC-MS and high-performance liquid chromatography methods. The excretion rate of BHQ glucuronide for 24h after dosing with BHT-acid was about 9-fold higher than that after dosing with BHT. In addition, the formation of BBQ was confirmed in the urine after dosing with DBP. These results suggest that BHT is metabolized to BHQ and BBQ through DBP formed by decarboxylation of BHT-acid. PMID:2054880

Yamamoto, K; Tajima, K; Takemura, M; Mizutani, T

1991-02-01

147

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

SciTech Connect

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.

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

2006-04-15

148

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

PubMed Central

The title compound, C10H12N2S, does not contain any strong hydrogen-bond donors but two long C—H?N contacts are observed in the crystal structure, with the most linear inter­action linking mol­ecules along [010]. The ellipsoids of the tert-butyl group indicate large librational motion. PMID:25309261

El-Hiti, Gamal A.; Smith, Keith; Hegazy, Amany S.; Masmali, Ali M.; Kariuki, Benson M.

2014-01-01

149

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

Microsoft Academic Search

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

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

2005-01-01

150

Substituted 2,2?-bipyridines by nickel-catalysis: 4,4?-di-tert-butyl-2,2?-bipyridine  

PubMed Central

A simple, ligand-free synthesis of the important bipyridyl ligand 4,4?-di-tert-butyl-2,2?-bipyridine is presented. 5,5?-bis(trifluoromethyl)-2,2?-bipyridine is also synthesized by the same protocol. The syntheses efficiently couple the parent 2-chlorpyridies by a nickel-catalyzed dimerization with manganese powder as the terminal reductant. PMID:25221358

Buonomo, Joseph A.; Everson, Daniel A.; Weix, Daniel J.

2014-01-01

151

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

PubMed Central

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

Vlad, Elena; Bozga, Grigore

2012-01-01

152

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

PubMed

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

Vlad, Elena; Bildea, Costin Sorin; Bozga, Grigore

2012-01-01

153

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

SciTech Connect

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})

Hu, Andrew Teh; Hu Tenyi; Liu Lungchang

2003-12-10

154

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

PubMed

Novel A3B-type 8(9),13(14),18(19)-tri-tert-butyl-2(5),4(7)-bis(4-tert-butylphenyl)tribenzo[g,l,q]-6H-1,4-diazepino[2,3-b]porphyrazine, which has high solubility in organic solvents, was obtained by template co-condensation of 2,3-dicyano-5,7-bis(4-tert-butylphenyl)-6H-1,4-diazepine and 4-tert-butylphthalonitrile. It was characterized by UV/Vis, (1)H, (13)C NMR spectroscopy, and MALDI-TOF/TOF mass spectrometry. We have demonstrated for the first time using fluorescence spectroscopy measurements and quantum-chemical calculations that the complicated UV/Vis spectrum of A3B-type tribenzodiazepinoporphyrazine is due to the formation of stable H-type aggregates. PMID:25576944

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

2015-03-15

155

Correlation of the rates of solvolysis of tert-butyl chlorothioformate and observations concerning the reaction mechanism  

PubMed Central

The “parent” tertiary alkyl chloroformate, tert-butyl chloroformate, is unstable, but the tert-butyl chlorothioformate (1) is of increased stability and a kinetic investigation of the solvolyses is presented. Analyses in terms of the simple and extended Grunwald-Winstein equations are carried out. The original one-term equation satisfactorily correlates the data with a sensitivity towards changes in solvent ionizing power of 0.73 ±0.03. When the two-term equation is applied, the sensitivity towards changes in solvent nucleophilicity of 0.13 ± 0.09 is associated with a high (0.17) probability that the term that it governs is not statistically significant. PMID:23538747

Kyong, Jin Burm; Lee, Yelin; D’Souza, Malcolm John; Kevill, Dennis Neil; Kevill, Dennis Neil

2012-01-01

156

Di-tert-butyl N,N?-(octa­hydro­penta­lene-2,5-di­yl)dicarbamate  

PubMed Central

In the molecule of the title compound, C18H32N2O4, the central bicyclo­[3.3.0]octane (octa­hydro­penta­lene) has a rigid ring junction. Both rings of the bicyclo­[3.3.0]octane unit adopt an envelope conformation, and the flexible tert-butyl­carbamoyl side chains each have an extended conformation. Such a constrained bicyclo­[3.3.0]octane aliphatic template is of inter­est with respect to the design of novel self-assembling motifs. Mol­ecules related by c-glide symmetry are linked via inter­molecular N—H?O hydrogen bonds, forming a two-dimensional layer structure. Neighboring layers are weakly associated along the a axis due to the close approach of the tert-butyl­carbamoyl groups (2.55?Å). PMID:21202657

Kendhale, Amol M.; Gonnade, Rajesh G.; Sanjayan, Gangadhar J.

2008-01-01

157

Di-tert-butyl N,N'-(octa-hydro-penta-lene-2,5-di-yl)dicarbamate.  

PubMed

In the molecule of the title compound, C(18)H(32)N(2)O(4), the central bicyclo-[3.3.0]octane (octa-hydro-penta-lene) has a rigid ring junction. Both rings of the bicyclo-[3.3.0]octane unit adopt an envelope conformation, and the flexible tert-butyl-carbamoyl side chains each have an extended conformation. Such a constrained bicyclo-[3.3.0]octane aliphatic template is of inter-est with respect to the design of novel self-assembling motifs. Mol-ecules related by c-glide symmetry are linked via inter-molecular N-H?O hydrogen bonds, forming a two-dimensional layer structure. Neighboring layers are weakly associated along the a axis due to the close approach of the tert-butyl-carbamoyl groups (2.55?Å). PMID:21202657

Kendhale, Amol M; Gonnade, Rajesh G; Sanjayan, Gangadhar J

2008-01-01

158

A New GC-MS Experiment for the Undergraduate Instrumental Analysis Laboratory in Environmental Chemistry: Methyl-t-butyl Ether and Benzene in Gasoline  

Microsoft Academic Search

With the recent ACS approval of an option in environmental chemistry at the undergraduate level, there is a need for new experiments that illustrate fundamental principles of instrumental analysis in the context of environmental chemistry. We describe an experiment that utilizes combined gas chromatography-mass spectrometry (GC-MS) in the qualitative and quantitative analysis of methyl tert-butyl ether (MTBE) and benzene in

Dinh T. Quach; Nancy A. Ciszkowski; Barbara J. Finlayson-Pitts

1998-01-01

159

Glutathione protection against hydrogen peroxide, tert-butyl hydroperoxide and diamide cytotoxicity in rat hepatoma-derived Fa32 cells  

Microsoft Academic Search

1 Several ozonides, peroxides and aldehydes are formed during ozone therapy, recently introduced in medicine. tert-Butyl hydroperoxide (t-BHP), H2O2 and diamide were investigated as model substrate in rat hepatoma-derived Fa32 cells.2 The cytotoxicity was measured by the neutral red uptake inhibition assay after 1 h or 24 h treatment. The relative toxicities were quantified by the determination of the NI50.

P. J. Dierickx; G. van Nuffel; I. Alvarez

1999-01-01

160

Radical production and cytotoxic activity of tert-butyl-substituted phenols.  

PubMed

2,4,6-Tri-tert-butylphenol (TBP)-related compounds are used for stabilizing plastics by making them resistant to oxidation. However, the cytotoxic activity of these compounds has not yet been established. TBP produced phenoxyl radicals at pH >or= 9.0 and 2,4-di-t-butylphenol (DBP) at pH 12.5, but 3,3',5,5'-tetra-t-butyl-1,1'-biphenyl-2,2'-diol (bisDBP) did not, using ESR spectroscopy. Both superoxide anion radical (O(2)(-)) scavenging activity and reactive oxygen species (ROS) production activity declined in the order of TBP > DBP > bisDBP. The cytotoxic activity against human oral tumor cell lines (HSC-2, HSG) and human gingival fibroblast cells (HGF) declined in the order of DBP > bisDBP = TBP = TBP-OOH (2,4,6-tri-t-butyl-4-hydroperoxy-2,5-cyclohexadiene-1-one). The cytotoxic activity of TBP, but not of DBP or bisDBP was significantly enhanced after visible light (VL)-irradiation for 10 min. The cytotoxicity of irradiated TBP was significantly higher than that of either original TBP or TBP-OOH, the oxidative metabolite of TBP, possibly due to the formation of TBP stable radical and ROS via oxidation. In contrast, the cytotoxic activity of DBP and bisDBP was independent of radical production, and therefore, may be intrinsic. A non-enzymatic oxidation decomposition of DBP or TBP was estimated from the formation of reaction enthalpy (DeltaH) using a modified neglect of diatomic overlap, parametric method 3 (MNDO-PM3) semi-empirical method, suggesting that O(2) is capable of activating DBP to a reactive quinone or dimer and that TBP phenoxyl radicals via oxidation directly affect extra- or intracellular bioactive materials, resulting in the induction of cytotoxicity. PMID:11689156

Saito, M; Atsumi, T; Satoh, K; Ishihara, M; Iwakura, I; Sakagami, H; Yokoe, I; Fujisawa, S

2001-01-01

161

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

PubMed Central

Butane-oxidizing Arthrobacter (ATCC 27778) bacteria were shown to degrade low concentrations of methyl t-butyl ether (MTBE; range, 100 to 800 ?g/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

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

2001-01-01

162

Entanglement Dynamics in Miscible Polyisoprene / Poly(p-tert-butyl styrene) Blends  

NASA Astrophysics Data System (ADS)

Viscoelastic and dielectric behavior was examined for well entangled, miscible blends of high-M cis-polyisoprene (PI) and poly(p-tert-butyl styrene) (PtBS). The dielectric data of the blends, reflecting the global motion of the PI chains having the type-A dipoles, indicated that PI and PtBS were the fast and slow components therein. At high temperatures T, the blends exhibited two-step entanglement plateau. The high frequency (?) plateau height was well described by a simple mixing rule of the entanglement length based on the number fraction of the Kuhn segments. At low T, the blend exhibited the Rouse-like power-law behavior of storage and loss moduli, G' = G" ˜0.5?, in the range of ? where the high-? plateau was supposed to emerge. This lack of the high-? plateau was attributed to retardation of the Rouse equilibration of the PI chain over the entanglement length due to the hindrance from the slow PtBS chains: The PI and PtBS chains were equilibrated cooperatively, and the retardation due to PtBS shortened the plateau for PI to a width not resolved experimentally. A simple model for this cooperative equilibration formulated on the basis of the dielectric data described the viscoelastic data surprisingly well.

Watanabe, Hiroshi

2011-03-01

163

Predicted and experimental crystal structures of ethyl-tert-butyl ether.  

PubMed

Possible crystal structures of ethyl-tert-butyl ether (ETBE) were predicted by global lattice-energy minimizations using the force-field approach. 33 structures were found within an energy range of 2 kJmol(-1) above the global minimum. Low-temperature crystallization experiments were carried out at 80-160 K. The crystal structure was determined from X-ray powder data. ETBE crystallizes in C2/m, Z = 4, with molecules on mirror planes. The ETBE molecule adopts a trans conformation with a (CH(3))(3)C-O-C-C torsion angle of 180°. The experimental structure corresponds with high accuracy to the predicted structure with energy rank 2, which has an energy of 0.54 kJmol(-1) above the global minimum and is the most dense low-energy structure. In some crystallization experiments a second polymorph was observed, but the quality of the powder data did not allow the determination of the crystal structure. Possibilities and limitations are discussed for solving crystal structures from powder diffraction data by real-space methods and lattice-energy minimizations. PMID:21422614

Hammer, Sonja M; Alig, Edith; Fink, Lothar; Schmidt, Martin U

2011-04-01

164

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

PubMed

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

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

2009-08-15

165

Protective mechanisms of anthocyanins from purple sweet potato against tert-butyl hydroperoxide-induced hepatotoxicity.  

PubMed

Anthocyanins have been shown to exert anti-proliferative, anti-inflammatory effects and anti-carcinogenic activity. In the present work, we investigated the protective effects of anthocyanin fraction (AF) from purple sweet potato on tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in HepG2 cell line and in rat liver. The result showed that the oral pretreatment of AF before t-BHP treatment significantly lowered the serum levels of the hepatic enzyme markers (ALT and AST) and reduced oxidative stress of the liver by evaluation of malondialdehyde and glutathione. Histopathological evaluation of the livers also revealed that AF reduced the incidence of liver lesions. The in vitro result showed that AF significantly reduced t-BHP-induced oxidative injury, as determined by cell cytotoxicity, intracellular glutathione content, lipid peroxidation, reactive oxygen species (ROS) levels, and caspases activation. Also, AF up-regulated antioxidant enzymes including heme oxygenase-1 (HO-1), NAD(P)H:quinone reductase, and glutathione S-transferase. Moreover, AF induced Nrf2 nuclear translocation and Akt and ERK1/2 activation, pathways that are involved in inducing Nrf2 nuclear translocation. Taken together, these results suggest that the protective effects of AF against t-BHP-induced hepatotoxicity may, at least in part, be due to its ability to scavenge ROS and to regulate the antioxidant enzyme HO-1 via the Akt and ERK1/2/Nrf2 signaling pathways. PMID:21640154

Hwang, Yong Pil; Choi, Jae Ho; Choi, Jun Min; Chung, Young Chul; Jeong, Hye Gwang

2011-09-01

166

Emulsion Polymerization of Butyl Acrylate: Spin Trapping and EPR Study  

NASA Technical Reports Server (NTRS)

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.

Kim, S.; Westmoreland, D.

1994-01-01

167

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

PubMed

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

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

2014-09-01

168

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

PubMed

The effect of tert-butyl alcohol (TBA) on isothermal crystallization kinetics of gemcitabine hydrochloride (GHCl) in frozen aqueous solutions was assessed by cold-stage microscopy. Addition of TBA (0%-5%, w/w) increased the value of Johnson-Mehl-Avrami rate constant (1.3-33.3 h(-1) ) and reduced the Avrami exponent (2.5-1.0). Thermodynamic parameters [enthalpy (?H(‡) ), entropy (?S(‡) ), and free energy (?G(‡) ) of activation], calculated using Arrhenius and Eyring-Polanyi equations, established that TBA (2%, w/w) accelerated GHCl crystallization by reducing its ?H(‡) (53.9 cf. 96.5 kJ/mol(-1) ) and ?G(‡) (68.5 cf. 74.9 kJ/mol(-1) ). Further, to explore insights into the effect of TBA on nucleation and crystal growth of GHCl, crystallization kinetics data were deconvolved using Finke-Watzky model. This revealed that addition of TBA decreased ?H(‡) of nucleation and increased ?S(‡) of crystal growth, thereby reducing ?G(‡) of nucleation and crystal growth by 11.7% and 4.2%, respectively. Finkey-Watzky model also predicted a reduction in the crystal size upon TBA addition, which was confirmed by comparing particle size of GHCl lyophilized in the presence and absence of TBA. In conclusion, TBA reduces ?G(‡) of nucleation and crystal growth in a differential manner, thereby enhancing the crystallization kinetics of GHCl and affecting its morphological features. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:87-97, 2015. PMID:25393155

Munjal, Bhushan; Bansal, Arvind K

2015-01-01

169

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

PubMed

This study demonstrates the utility of the sequencing batch reactor (SBR) to adapt microorganisms towards biological removal of tert-butyl alcohol (TBA). The reactor was inoculated with activated sludge and fed with TBA as the sole carbon source. Start-of-cycle TBA concentrations were initially set at 100 mgL(-1) with a cycle time of 24 h and a volumetric exchange ratio of 50% to maintain a TBA loading rate of not more than 100 mgL(-1)d(-1). Step increases in TBA loading rates up to 600 mgL(-1)d(-1) were achieved by first raising the start-of-cycle TBA concentration to 150 mgL(-1) on day 90 and subsequently by reducing the cycle time from 24 to 12, 8 and 6h on days 100, 121 and 199, respectively. This acclimation strategy favored the retention of increasingly higher densities of well-adapted microbial populations in the reactor. The increases in TBA loading produced better settling biomass and higher biomass concentrations with higher specific TBA biodegradation rates. Effluent TBA concentrations were consistently below the detection limit of 25 microgL(-1). The use of progressively shorter cycle times created selection pressures that fostered the self-immobilization of the reactor microorganisms into aerobic granules which first appeared on day 125. Specific TBA biodegradation rates in the granules followed the Haldane model for substrate inhibition, and peaked at 13.8 mgTBAgVSS(-1)h(-1) at a TBA concentration of 300 mgL(-1). Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes from granules sampled between days 220 and 247 confirmed the existence of a highly stable microbial community with members belonging to the alpha, beta and delta subdivisions of Proteobacteria and the Cytophaga-Flavobacteria-Bacteroides (CFB) group. PMID:15899532

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

2005-07-21

170

LC50 Determination of tert-Butyl Acetate using a Nose Only Inhalation Exposure in Rats  

PubMed Central

tert-Butyl acetate (TBAc) is an organic solvent, which is commonly used in architectural coatings and industrial solvents. It has recently been exempted from the definition of a volatile organic compound (VOC) by the Air Resources Board (ARB) . Since the use of TBAc as a substitute for other VOCs has increased, thus its potential risk in humans has also increased. However, its inhalation toxicity data in the literature are very limited. Hence, inhalation exposure to TBAc was carried out to investigate its toxic effects in this study. Adult male rats were exposed to TBAc for 4 h for 1 day by using a nose-only inhalation exposure chamber (low dose, 2370 mg/m3 (500 ppm) ; high dose, 9482 mg/m3 (2000 ppm) ) . Shamtreated control rats were exposed to clean air in the inhalation chamber for the same period. The animals were killed at 2, 7, and 15 days after exposure. At each time point, body weight measurement, bronchoalveolar lavage fluid (BALF) analysis, histopathological examination, and biochemical assay were performed. No treatment-related abnormal effects were observed in any group according to time course. Based on those findings, the median lethal concentration (LC50) of TBAc was over 9482 mg/m3 in this study. According to the MSDS, the 4 h LC50 for TBAc for rats is over 2230 mg/m3. We suggested that this value is changed and these findings may be applied in the risk assessment of TBAc which could be beneficial in a sub-acute study. PMID:24278537

Yang, Young-Su; Lee, Jinsoo; Kwon, Soonjin; Seo, Heung-Sik; Choi, Seong-Jin; Yu, Hee-Jin; Song, Jeong-Ah; Lee, Kyuhong; Lee, Byoung-Seok; Heo, Jeong-Doo; Cho, Kyu-Hyuk

2010-01-01

171

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

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…

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

2004-01-01

172

Tandem mass spectrometry study of C-phenyl-N-tert-butyl nitrone spin adducts from in vitro rat liver microsomal metabolism of bromotrichloromethane and carbon tetrachloride.  

PubMed

Electron ionization and thermospray were used in conjunction with tandem mass spectrometry methods to identify trichloromethyl/C-phenyl-N-tert-butyl nitrone (PBN) spin adducts produced in rat liver microsomal dispersions that had been treated with reduced nicotinamide adenine dinucleotide phosphate (NADPH)-generating system and BrCCl3 (or CCl4). In the identification of PBN spin adducts, a scan of precursors of m / z 57 was utilized to confirm the presence of PBN spin adducts, because PBN spin adducts produce m / z 57 from tert-butyl as a characteristic fragment. Use of deuterated PBN (PBN-d9 deuterated at tert-butyl; PBN-d 14 deuterated at both phenyl and tert-butyl) improved the recognition of PBN adducts in mixtures by precursor ion scans, because m / z 66 (which corresponds to the deuterated tert-butyl group) is characteristic and, unlike m / z 57, it is not a common fragment for any other compounds. Two new PBN spin adducts that were not detected before by electron paramagnetic resonance or mass spectrometry were identified by these methods for the first time. PMID:24214427

Janzen, E G; Sang, H; Kotake, Y; Dubose, C M; Poyer, J L; Arimura, M

1995-09-01

173

Diode laser probes of tert-butyl radical reaction kinetics: Reaction of C(CH sub 3 ) sub 3 with HBr, DBr, and HI  

SciTech Connect

The rate constants for reaction of tert-butyl radical with HBr, DBr, and HI have been measured by use of a tunable infrared diode laser probe. The measured rate constants at room temperature are 1.0 {times} 10{sup {minus}11}, 8 {times} 10{sup {minus}12}, and 2.5 {times} 10{sup {minus}11} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}, respectively. The reaction with HI exhibits a negative activation energy of 1.5 kcal mol{sup {minus}1}. The reaction rates of HBr and DBr with tert-butyl radical at elevated temperatures are also slower than the corresponding rates at room temperature. The rate constant for reaction of tert-butyl radicals with HBr is in excellent agreement with the faster of the two conflicting previously reported measurements for the tert-butyl-HBr system. From this study the heat of formation of the tert-butyl radical has been calculated to be 11.5 {plus minus} 0.8 kcal mol{sup {minus}1}.

Richards, P.D.; Ryther, R.J.; Weitz, E. (Northwestern Univ., Evanston, IL (USA))

1990-05-03

174

Selective epoxidation of allyl acetate with tert-butyl hydroperoxide over MoO 3\\/MgO  

Microsoft Academic Search

Highly selective epoxidation of allyl acetate was carried out over MoO3\\/MgO using tert-butyl hydroperoxide as an oxidizing agent. The catalytically active species was identified as monolayer MgMoO4 on MgO. MgO with large pores is suitable for selective epoxide formation. The highest yield of glycidyl acetate was obtained over 7wt.% MoO3\\/MgO, in which MgMoO4 species were highly dispersed on the surface

Kenta Shimura; Hiroyoshi Kanai; Kazunori Utani; Kazuo Matsuyama; Seiichiro Imamura

2005-01-01

175

Ion kinetic energy distributions and cross sections for the electron impact ionization of ethyl tert-butyl ether  

NASA Astrophysics Data System (ADS)

The kinetic energy distributions and the cross sections of the ions produced in the electron impact of ethyl tert-butyl ether (ETBE) have been studied by time of flight (TOF) mass spectrometry. The kinetic energy distributions have been deduced from the TOF peak shape analysis and a Montecarlo simulation method of the ion trajectories has been used to evaluate the collection efficiency of the spectrometer as a function of the ion initial kinetic energy. The measured ion yields have been corrected for the collection efficiency and the partial and total ionization cross sections of ETBE determined in the range 20-150 eV.

Di Palma, T. M.; Apicella, B.; Armenante, M.; Velotta, R.; Wang, X.; Spinelli, N.

2005-11-01

176

Red fluorescent emitting materials based on di-tert-butyl chromene derivatives for organic light-emitting diodes.  

PubMed

In this paper are described two di-tert-butyl chromene-containing red fluorescent materials (Red 1 and Red 2). To explore the electroluminescence properties of these materials, multilayered OLEDs using these materials as dopants in a Alq3 host were fabricated. In particular, a device using Red 2 as the dopant material showed maximum luminous efficiencies and power efficiencies of 1.14 cd/A and 0.58 Im/W, respectively. The CIEx,y coordinates of this device were (0.67, 0.32) at 7.0 V. PMID:23646772

Na, Eun Jae; Lee, Kum Hee; Han, Hoon; Kim, Young Kwan; Yoon, Seung Soo

2013-01-01

177

Development of cellulose acetate propionate membrane for separation of ethanol and ethyl tert-butyl ether mixtures  

SciTech Connect

For pervaporation separation of ethanol and ethyl tert-butyl ether mixtures, a cellulose acetate propionate membrane was chosen as the experimental membrane because of its high selectivity and good mass fluxes. The properties of the membranes were evaluated by the pervaporation separation of mixtures of ethyl tert-butyl ether/ethanol and the sorption experiments. The experimental results showed that the selectivity and the permeates depend on the ethanol concentration in the feed and the experimental temperature. With increases of the ethanol weight fraction in the feed and the temperature, the total and partial mass fluxes increased. With respect to the temperature, ethanol mass flux obeys the Arrhenius equation. The selectivity of this membrane decreases as the temperature and the ethanol concentration in the feed increase. This membrane shows special characteristics at the azeotropic composition. In the vicinity of the azeotropic point, minimum values of ethanol concentration in the permeate and in sorption solution are obtained. The swelling ratios increase when temperature and the ethanol concentration in the feed are increasing. The ethanol concentration in the sorption solution is also influenced by the temperature and the mixture`s composition. When the temperature increases, the sorption selectivity of the membrane decreases.

Luo, G.S.; Niang, M.; Schaetzel, P. [Laboratoire D`Automatique et de Procedes, Caen (France)

1997-04-01

178

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

PubMed

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 ?-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

Ratnikov, Maxim O; Doyle, Michael P

2013-01-30

179

Mono-, di-, and tri-tert-butyl ethers of glycerol. A molecular spectroscopic study.  

PubMed

MS, NMR, IR and Raman molecular spectroscopy techniques were applied to characterize 3-tert-butoxy-propane-1,2-diol, 1,3-di-tert-butoxy-propan-2-ol, and 1,2,3-tri-tert-butoxy-propane. These ethers are the main products of glycerol etherification reaction and are excellent oxygen additives for diesel fuel. Computational DFT/ B3LYP/6-31G** studies were performed to support and rationalize both vibrational spectroscopy analysis and the isomer ratio. PMID:17085068

Jamróz, Ma?gorzata E; Jarosz, Ma?gorzata; Witowska-Jarosz, Janina; Bednarek, Elzbieta; Tecza, Witold; Jamróz, Micha? H; Dobrowolski, Jan Cz; Kije?ski, Jacek

2007-07-01

180

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

EIA Publications

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

2006-01-01

181

Heterolytic CH Activation with a Cyclometalated Platinum(II) 6-Phenyl-4,4-di-tert-butyl-2,2-Bipyridine Complex  

E-print Network

tridentate amido NNN platinum pincer complex that activates the CH bond of benzene in the presence of a bulkyHeterolytic CH Activation with a Cyclometalated Platinum(II) 6-Phenyl-4,4-di-tert-butyl-2,2-Bipyridine Complex Kenneth J. H. Young, Steven K. Meier, Jason M. Gonzales, Jonas Oxgaard, William A. Goddard

Goddard III, William A.

182

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)

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.

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

2014-10-01

183

Poly[(?3-5-tert-butyl­benzene-1,3-di­carboxyl­ato)di­pyridine­cobalt(II)  

PubMed Central

In the title compound, [Co(C12H12O4)(C5H5N)2]n, the CoII cation is coordinated by four O atoms from three 5-tert-butyl­benzene-1,3-di­carboxyl­ate anions and two N atoms from pyridine mol­ecules in a distorted octa­hedral geometry. One carboxyl­ate group of the anionic ligand chelates a CoII cation while another carboxyl­ate group bridges two CoII cations, resulting in a polymeric layer parallel to (101). Weak C—H?O hydrogen bonds occur between adjacent polymeric layers. In the crystal, one of pyridine mol­ecules is equally disordered over two positions. PMID:24526931

Noh, Kyungkyou; Kim, Jaheon

2013-01-01

184

[Contribution to the migration and toxicology of 2-(2'-hydroxy-3'-tert-butyl-5'-methylpheny)-5-chlorobenzotriazole].  

PubMed

Studies on the use of an ultraviolet-absorbing agent based on hydroxybenzotriazole for commodities of low-pressure and high-pressure polyethylene and polypropylene show that the migration is only slight in aqueous and acidic foods and in foodstuffs with low alcohol content. Sunflower oil, n-heptane (as a fat-stimulating test solution) and 50% ethanol as test solutions yielded higher migration values. Gas chromatographic, polarographic and thin-layer chromatographic methods were used to determine the ultraviolet-absorbing agent. Concerns about a possible photosensitizing effect of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole were experimentally tested and turned out to be unfounded. From the viewpoint of safety, there are no contraindications to the use of polyolefines in packing materials for most foods. As to fat-containing and strongly alcoholic foodstuffs, the authorization should be conditioned on the circumstances of use. PMID:927485

Uhde, W J; Horácek, J

1977-01-01

185

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

PubMed Central

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

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

2014-01-01

186

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

PubMed

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

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

2013-10-01

187

Study of an aquifer contaminated by ethyl tert-butyl ether (ETBE): site characterization and on-site bioremediation.  

PubMed

Ethyl tert-butyl ether (ETBE) was detected at high concentration (300mgL(-1)) in the groundwater below a gas-station. No significant carbon neither hydrogen isotopic fractionation of ETBE was detected along the plume. ETBE and BTEX biodegradation capacities of the indigenous microflora Pz1-ETBE and of a culture (MC-IFP) composed of Rhodococcus wratislaviensis IFP 2016, Rhodococcus aetherivorans IFP 2017 and Aquincola tertiaricarbonis IFP 2003 showed that ETBE and BTEX degradation rates were in the same range (ETBE: 0.91 and 0.83 mg L(-1)h(-1) and BTEX: 0.64 and 0.82 mg L(-1)h(-1), respectively) but tert-butanol (TBA) accumulated transiently at a high level using Pz1-ETBE (74 mg L(-1)). An on-site pilot plant (2m(3)) filled with polluted groundwater and inoculated by MC-IFP, successfully degraded four successive additions of ETBE and gasoline. However, an insignificant ETBE isotopic fractionation was also accompanying this decrease which suggested the involvement of low fractionating-strains using EthB enzymes, but required of additional proofs. The ethB gene encoding a cytochrome P450 involved in ETBE biodegradation (present in R. aetherivorans IFP 2017) was monitored by quantitative real-time polymerase chain reaction (q-PCR) on DNA extracted from water sampled in the pilot plant which yield up to 5×10(6) copies of ethB gene per L(-1). PMID:22177017

Fayolle-Guichard, Françoise; Durand, Jonathan; Cheucle, Mathilde; Rosell, Mònica; Michelland, Rory Julien; Tracol, Jean-Philippe; Le Roux, Françoise; Grundman, Geneviève; Atteia, Olivier; Richnow, Hans H; Dumestre, Alain; Benoit, Yves

2012-01-30

188

Electrorheological Properties of Suspensions Prepared from Poly(Li-tert-butyl methacrylate) Ionomer  

Microsoft Academic Search

The synthesis, characterisation and partial hydrolysis of poly(tert-butylmethacrylate), (PTBMA), and the electrorheological (ER) properties of its suspensions were investigated. The polymer was syn- thesised by radical polymerisation and partially hydrolysed by para-toluenesulphonic acid monohydrate (PTSA.H2O), and then converted to a lithium salt (PTBMA-Li) by washing with a LiOH(aq) solution. From particle size measurements, the average particle size of PTBMA-Li was

Mustafa YAVUZ

189

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

USGS Publications Warehouse

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

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

2001-01-01

190

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...

191

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

PubMed Central

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

Herath, Ananda; Cosford, Nicholas D. P.

2010-01-01

192

31-Benz­yloxy-5,11,17,23,29-penta-tert-butyl­calix[5]arene-32,33,34,35-tetra­ol  

PubMed Central

The title compound, C62H76O5, known to be one of the most versatile synthetic precursors/inter­mediates of calix[5]arene derivatives, adopts an approximate C s-symmetric cone-in conformation. The aryl­oxybenzyl ring is tilted in such a way that the p-tert-butyl group fills the macrocycle cavity, while the benzyl group moves away from the cavity axis. In the crystal, this conformational arrangement is secured by intra- and inter­molecular O—H?O hydrogen bonds forming inversion dimers. Four tert-butyl groups are disordered over two orientations, with occupancy ratios of 0.745?(6):0.255?(6), 0.837?(5):0.163?(5), 0.850?(5):0.150?(5) and 0.845?(8):0.155?(8). PMID:23476242

Gargiulli, Claudia; Gattuso, Giuseppe; Notti, Anna; Nicoló, Francesco; Pappalardo, Andrea

2012-01-01

193

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

PubMed

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

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

2013-07-01

194

Free radical scavenging abilities of flavonoids as mechanism of protection against mutagenicity induced by tert-butyl hydroperoxide or cumene hydroperoxide in Salmonella typhimurium TA102  

Microsoft Academic Search

Mutagenicity induced by tert-butyl hydroperoxide (BHP) or cumene hydroperoxide (CHP) in Salmonella typhimurium TA102 was effectively reduced by flavonols with 3?,4?-hydroxyl groups such as fisetin, quercetin, rutin, isoquercitrin, hyperoxide, myricetin, myricitrin, robinetin, and to a lesser extent also by morin and kaempferol (ID50=0.25–1.05?mol per plate). With the exception of isorhamnetin, rhamnetin, morin, and kaempferol, closely similar results were obtained with

R. Edenharder; D. Grünhage

2003-01-01

195

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

Microsoft Academic Search

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

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

1988-01-01

196

3-tert-Butyl-5,6,8-trinitro­naphtho[1,8a,8-cd][1,2]dithiole  

PubMed Central

Nitration of 2,7-di-tert-butyl­naphthalene 1,8-disulfide with fuming nitric acid in 1:3 molar ratio gives the title compound, C14H11N3O6S2. A tape motif is formed by weak head-to-tail inter­actions (3.131?Å) between S and NO2 O atoms of a symmetry-related mol­ecule. PMID:21202319

Jiang, Yuqin; Wan, Xiangjian; Chen, Yongsheng

2008-01-01

197

An analysis of 2,6-di-tert-butyl-p-cresol in insulating oils by high-performance liquid chromatography  

Microsoft Academic Search

The presence of antioxidant is the key factor in controlling the oxidation of an insulating oil. Any monitoring program set up to keep track of its concentration could result in substantial savings by prolonging the oil service life and slowing down the transformer aging process. This paper describes a method for measuring the amount of the antioxidant 2,6-di-tert-butyl-para-cresol (DBPC) in

C. Lamarre; A. Gendron

1995-01-01

198

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

PubMed

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 (19)F-NMR signal in D2O, with T1 and T2 parameters of approximately 500 and 100 ms, respectively. (19)F-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

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

2014-11-21

199

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

PubMed

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

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

2015-01-25

200

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

201

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

PubMed Central

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

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

2008-01-01

202

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

PubMed

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

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

2004-05-01

203

Enhanced diisobutene production in the presence of methyl tertiary butyl ether  

DOEpatents

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.

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

1983-01-01

204

Enhanced diisobutene production in the presence of methyl tertiary butyl ether  

DOEpatents

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.

Smith, L.A. Jr.

1983-03-01

205

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

PubMed Central

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

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

2009-01-01

206

Protective effect of Mesona procumbens against tert-butyl hydroperoxide-induced acute hepatic damage in rats.  

PubMed

The protective effect of Hsian-tsao (Mesona procumbens Hemsl.) and its active compounds on liver damage was evaluated using the model of tert-butyl hydroperoxide (t-BHP)-induced acute hepatic damage in rats. Male Sprague-Dawley rats (200 +/- 10 g) were orally pretreated with a water extract of Hsian-tsao (WEHT) (0.1, 0.5, and 1.0 g/kg) or caffeic acid (0.1 g/kg of body weight) for 13 days before a single dose of t-BHP (0.2 mmol/kg, intraperitoneally) to each animal, and the rats were sacrificed 18 h later by decapitation; blood samples were collected for the assays of serum biochemical values. The livers were excised from the animals and assayed for oxidative injury, antioxidant enzyme, and pathological histology. The result showed that the oral pretreatment of WEHT (0.1, 0.5, and 1.0 g/kg) or caffeic acid (0.10 g/kg) before t-BHP (0.2 mmol/kg) treatment significantly lowered the serum levels of the hepatic enzyme markers (alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase) and reduced oxidative stress of the liver by evaluation of malondialdehyde, glutathione, 8-hydroxy-2'-deoxyguanosine, glutathione peroxidase, and glutathione reductase. The histopathological evaluation of the rat livers showed that WEHT and caffeic acid reduced the incidence of liver lesions including cloudy swelling, pyknosis, and cytolysis induced by t-BHP in rats. On the basis of the results of this study, it can be speculated that M. procumbens protects liver against t-BHP-induced hepatic damage in rats. PMID:15212457

Yen, Gow-Chin; Yeh, Chi-Tai; Chen, Yen-Ju

2004-06-30

207

The standard enthalpy of formation and low-temperature heat capacity of 1,1',3,3'-tetra-( tert-butyl)ferrocene  

NASA Astrophysics Data System (ADS)

The heat capacity of crystalline 1,1',3,3'-tetra-( tert-butyl)ferrocene (TTBF) was measured in an adiabatic vacuum calorimeter over the temperature range 5-302 K. The thermodynamic functions of TTBF in the crystalline state were calculated from T?0 to 302 K. The enthalpy of combustion of TTBF was determined in an isothermal calorimeter with a stationary bomb. The standard thermodynamic functions of formation of the compound in the crystalline state at 298.15 K were calculated.

Kozlova, M. S.; Larina, V. N.; Karyakin, N. V.; Sheiman, M. S.

2008-12-01

208

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

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

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

2013-01-01

209

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...

210

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

211

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

PubMed

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

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

2013-08-01

212

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

Microsoft Academic Search

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

YONGHONG WANG; XINGRONG ZENG; HONGQIANG LI; JIANHUA GUO

2012-01-01

213

Coordination Chemistry of a 5-tert-Butyl-2-[(2,6-diisopropylphenyl)aldimino]- pyrrolate Ligand.  

E-print Network

??The Vilsmeier-Haack reaction of pyrrole with oxalyl chloride and N,N-dimethylformaldehyde followed by Friedel-Crafts alkylation with Me3CCl in the presence of AlCl3 afforded 5-tert-butylpyrrole-2- carbal- dehyde… (more)

Yang, Chih-Wei

2002-01-01

214

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

PubMed

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

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

2013-12-01

215

Comprehensive experimental and theoretical study of chemical equilibria in the reacting system of the tert-amyl methyl ether synthesis.  

PubMed

The chemical equilibrium of the reactive system (methanol+isoamylenes<-->methyl tert-amyl ether) was studied in the temperature range 298-393 K in the liquid phase using the method of sealed ampoules as well as in the gaseous phase using a tubular flow reactor in the temperature range 355-378 K. In both cases, a cation exchanger Amberlist-15 was used as a heterogeneous catalyst. The reactive system of the methyl tert-amyl ether synthesis exhibits a strong nonideal behavior of the mixture compounds in the liquid phase. The knowledge of the activity coefficients is required in order to obtain the thermodynamic equilibrium constants Ka. Two well-established procedures, UNIFAC and COSMO-RS, have been used to assess activity coefficients of the reaction participants in the liquid phase. Thermodynamic equilibrium constants KP measured in the gaseous phase together with the vapor pressures of the pure compounds have been used to obtain Ka in the liquid phase on a consistent experimental basis in order to check the results obtained from the UNIFAC and COSMO-RS methods. Enthalpies of reactions DeltarH degrees of the methyl tert-amyl ether synthesis reaction in the gaseous and in the liquid phase were obtained from temperature dependences of the corresponding thermodynamic equilibrium constants. Consistency of the experimental data of DeltarH degrees was verified with help of enthalpies of formation and enthalpies of vaporization of methyl tert-amyl ether, methanol, and methyl-butenes, available from the literature. For the sake of comparison, high-level ab initio calculations of the reaction participants have been performed using the Gaussian-03 program package. Absolute electronic energy values, normal frequencies (harmonic approximation), and moments of inertia of the molecules have been obtained using G2(MP2), G3(MP2), and G3 levels. Using these results, calculated equilibrium constants and the enthalpy of reaction of the methyl tert-amyl ether synthesis in the gaseous phase based on the principles of statistical thermodynamics are found to be in acceptable agreement with the data obtained from the thermochemical measurements. PMID:17722908

Heintz, Andreas; Kapteina, Simon; Verevkin, Sergey P

2007-09-20

216

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

SciTech Connect

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

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

2011-08-15

217

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

E-print Network

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

Dandy, David

218

REMOVAL OF METHYL T-BUTYL ETHER (MTBE) FROM WATER BY PERVAPORATION: BENCH-SCALE AND PILOT SCALE EVALUATIONS  

EPA Science Inventory

The ability of pervaporation to remove methyl t-butyl ether (MTBE) from water was evaluated at bench- and pilot-scales. Process parameters studied included flow rate, temperature, MTBE concentration, membrane module type, and permeate pressure. Pervaporation performance was ass...

219

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

EPA Science Inventory

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

220

IN-SITU BIOREMEDIATION OF METHYL TERTIARY BUTYL ETHER (MTBE) - ADVANCED FUEL HYDROCARBON REMEDIATION NATIONAL TEST LOCATION.  

EPA Science Inventory

Equilon's Westhollow Technology Center teamed with Arizona State University to evaluate an in-situ process for bioremediation of methyl tertiary butyl ether (MTBE). MTBE is a gasoline additive that was introduced in fuels to reduce emission of a number of air pollutants including...

221

Bacterial Degradation of tert-Amyl Alcohol Proceeds via Hemiterpene 2-Methyl-3-Buten-2-ol by Employing the Tertiary Alcohol Desaturase Function of the Rieske Nonheme Mononuclear Iron Oxygenase MdpJ  

PubMed Central

Tertiary alcohols, such as tert-butyl alcohol (TBA) and tert-amyl alcohol (TAA) and higher homologues, are only slowly degraded microbially. The conversion of TBA seems to proceed via hydroxylation to 2-methylpropan-1,2-diol, which is further oxidized to 2-hydroxyisobutyric acid. By analogy, a branched pathway is expected for the degradation of TAA, as this molecule possesses several potential hydroxylation sites. In Aquincola tertiaricarbonis L108 and Methylibium petroleiphilum PM1, a likely candidate catalyst for hydroxylations is the putative tertiary alcohol monooxygenase MdpJ. However, by comparing metabolite accumulations in wild-type strains of L108 and PM1 and in two mdpJ knockout mutants of strain L108, we could clearly show that MdpJ is not hydroxylating TAA to diols but functions as a desaturase, resulting in the formation of the hemiterpene 2-methyl-3-buten-2-ol. The latter is further processed via the hemiterpenes prenol, prenal, and 3-methylcrotonic acid. Likewise, 3-methyl-3-pentanol is degraded via 3-methyl-1-penten-3-ol. Wild-type strain L108 and mdpJ knockout mutants formed isoamylene and isoprene from TAA and 2-methyl-3-buten-2-ol, respectively. It is likely that this dehydratase activity is catalyzed by a not-yet-characterized enzyme postulated for the isomerization of 2-methyl-3-buten-2-ol and prenol. The vitamin requirements of strain L108 growing on TAA and the occurrence of 3-methylcrotonic acid as a metabolite indicate that TAA and hemiterpene degradation are linked with the catabolic route of the amino acid leucine, including an involvement of the biotin-dependent 3-methylcrotonyl coenzyme A (3-methylcrotonyl-CoA) carboxylase LiuBD. Evolutionary aspects of favored desaturase versus hydroxylation pathways for TAA conversion and the possible role of MdpJ in the degradation of higher tertiary alcohols are discussed. PMID:22194447

Schuster, Judith; Schäfer, Franziska; Hübler, Nora; Brandt, Anne; Rosell, Mònica; Härtig, Claus; Harms, Hauke; Müller, Roland H.

2012-01-01

222

Trichloromethylation and tert-butylation of 2,4-disubstituted thiophenes: Electrophilic substitution reactions with sterically hindered rearomatization stages  

Microsoft Academic Search

The interaction of 2,4-disubstituted thiophenes with AlCl3 and CCl4 or tert-BuCl proceeds through cationic ?-complexes corresponding to electrophilic substitution; the deprotonation of these\\u000a complexes to form 2,3,5-trisubstituted products is sterically hindered, since this stage (rearomatization) involves a change\\u000a in hybridization of the C(2) atom from sp3 to sp2, which leads to an increase of repulsion between the substituent R in

L. I. Belen'kii; G. P. Gromova; B. V. Lichitskii; M. M. Krayushkin

1997-01-01

223

N-4TertButyl Benzyl Haloperidol Chloride Suppresses Ca2+-dependent Egr1 Expression and Subsequently Inhibits Vascular Smooth Muscle Cell Proliferation Induced by Angiotensin II  

Microsoft Academic Search

Background: N-4-Tert-Butyl benzyl haloperidol chloride (C3) was a novel calcium antagonist synthesized in our laboratory. The present study is to explore the effect of C3 on vascular smooth muscle cell proliferation and the mechanism involved. Methods: The effects of C3 on Ang II-induced cytosolic free Ca2+ concentration change, VSMC proliferation, the key early growth response factor 1 (Egr-1) were evaluated

Yicun Chen; Jinhong Zheng; Yanmei Zhang; Jinzhi Wang; Qing Liu; Zhanqin Huang; Fenfei Gao; Yanqiong Zhou; Ganggang Shi

2009-01-01

224

5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetra­propyn­yloxy-2,8,14,20-tetra­thia­calix[4]arene  

PubMed Central

The title compound [systematic name: 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra­propyn­yloxy-2,8,14,20-tetra­thia­calix[4]arene], C52H56O4S4, is an alkyl­ated product bearing four propyne groups at the lower rim of a 5,11,17,23-tetra-tert-butyl-tetrathia­calix[4]arene. The mol­ecule is located on a crystallographic twofold rotation axis, running through two S atoms and perpendicular to the long axis of the mol­ecule. The four propyne groups, located in an alternate fashion above and below the mean plane of the four S atoms, are almost parallel to the calixarene long axis. The dihedral angle between the two crystallographically independent benzene rings is 86.77?(14)°. Two tert-butyl groups are disordered over two positions with site occupancies of 0.59?(2) and 0.41?(2). PMID:21578745

Li, Xiong; Han, Hong-Wei; Meng, Xiang-Gao

2009-01-01

225

tertButyl hydroperoxide-induced lipid signaling in hepatocytes: involvement of glutathione and free radicals 1 1 Abbreviations: [ 14C]AA, [ 14C]-arachidonic acid; DCF, 2?,7?-dichlorofluorescein; DCFDA, 2?,7?-dichlorofluorescin diacetate; DTT, 1,4-dithiothreitol; MDA, malondialdehyde; PLA 2, phospholipase A 2; ROS, reactive oxygen species; TBARS, thiobarbituric acid reactive substances; and TBHP, tert-butyl hydroperoxide  

Microsoft Academic Search

tert-Butyl hydroperoxide (TBHP) mobilizes arachidonic acid (AA) from membrane phospholipids in rat hepatocytes under cytotoxic conditions, thus leading to an increase in intracellular AA, which precedes cell death. In the present work, the involvement of lipid peroxidation, thiol status, and reactive oxygen species (ROS) in the intracellular AA accumulation induced by 0.5 mM TBHP was studied in rat hepatocytes. Cells

César Mart??n; Rosa Mart??nez; Rosaura Navarro; José Ignacio Ruiz-Sanz; Mercedes Lacort; M. Begoña Ruiz-Larrea

2001-01-01

226

Di­chlorido­(4,4?-di-tert-butyl-2,2?-bi­pyridine-?2 N,N?)palladium(II) dimethyl sulfoxide monosolvate monohydrate  

PubMed Central

The title compound, [PdCl2(C18H24N2)]·(CH3)2SO·H2O, the PdII ion is in a distorted square-planar geometry. The Pd—N bond distances are 2.022?(2) and 2.027?(2)?Å, the Pd—Cl bond distances are 2.2880?(7) and 2.2833?(7)?Å, and the ligand bite angle is 80.07?(9)°. The dimethyl sulfoxide and water mol­ecules form linear chains along [100] by O—H?O and O—H?S hydrogen bonds, generating eight- and 12-membered rings. C—H?Cl inter­actions link the chains, forming a three-dimensional arrangement. In addition, the 4,4-di-tert-butyl-2,2?-bi­pyridine ligand exhibits ?–? stacking inter­actions [centroid–centroid distances = 3.8741?(15) and 3.8353?(15)?Å]. The DMSO solvent is disordered and was refined with an occupancy ratio of 0.866?(3):0.134?(3). PMID:24940194

Gutiérrez-Márquez, Ricardo A.; Crisóstomo-Lucas, Carmela; Reyes-Martínez, Reyna; Hernández-Ortega, Simón; Morales-Morales, David

2014-01-01

227

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

PubMed Central

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

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

2014-01-01

228

Comparative study on thiol drugs' effect on tert-butyl hydroperoxide induced luminol chemiluminescence in human erythrocyte lysate and hemoglobin oxidation.  

PubMed

The current studies have investigated the effect of heterocyclic drugs with the single thiol group (thiamazole, mercaptopurine) and dithiol aliphatic drugs (dimercaptosuccinic acid, dithiothreitol) under oxidative stress conditions, using tert-butyl hydroperoxide (t-BuOOH), in human erythrocyte lysate with the luminol-enhanced chemiluminescence technique. Knowing that oxidative processes induced by t-BuOOH are triggered by (oxy)hemoglobin (Hb), the effect of different thiol drugs (RSH) on isolated human Hb oxidation to methemoglobin (MHb) and hemichromes (HChr) was further considered. Three types of chemiluminescence curves, fitting to logistic-exponential model, have been revealed under influence of RSH. Structure of the data (MHb and HChr production, and free radical activity of RSH) in Principal Component Analysis visualization and kinetic profiles of chemiluminescence integrate information in terms of the diversity of RSH reaction mechanisms depending on the specific molecular context of the given thiol: aliphatic or aromatic nature as well as the number and position of the -SH groups in the molecule. The study conducted in presented in vitro systems indicates the potential role of thiol drugs mediated toxicity in an oxidative stress dependent mechanism. PMID:25308193

Sajewicz, Waldemar; Zalewska, Marta; Milnerowicz, Halina

2015-02-01

229

Antioxidant activity and protective effect of extract of Celosia cristata L. flower on tert-butyl hydroperoxide-induced oxidative hepatotoxicity.  

PubMed

This study was undertaken to evaluate the antioxidant potential and protective effects of Celosia cristata L. (Family: Amaranthaceae) flower (CCF) extracts on tert-butyl-hydroperoxide (t-BHP)-induced oxidative damage in the hepatocytes of Chang cells and rat livers. In vitro, CCF extracts exhibited protective effect through their radical scavenging ability to enhance cell viability, prevent reactive oxygen species (ROS) generation, and inhibit mitochondrial membrane depolarisation in t-BHP-induced hepatotoxicity in Chang cells. In vivo, oral feeding of CCF (100mg and 500mg/kg of body weight) to rats for five consecutive days before a single dose of t-BHP (2mmol/kg, i.p.) showed a significant (p<0.05) protective effect by lowering serum levels of glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT). The extract decreased the hepatic levels of lipid peroxidation (MDA) and serum level of triglyceride (TG) against t-BHP-induced oxidative stress. These results indicate that CCF extract prevented oxidative stress-induced liver injury by enhancing hepatocyte antioxidant abilities. PMID:25172750

Kim, Yon-Suk; Hwang, Jin-Woo; Sung, Si-Heung; Jeon, You-Jin; Jeong, Jae-Hyun; Jeon, Byong-Tae; Moon, Sang-Ho; Park, Pyo-Jam

2015-02-01

230

Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia  

SciTech Connect

Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300?°C from three recently synthesized M[N(t-Bu){sub 2}]{sub 2} precursors, where M?=?Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200?°C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18?nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities.

Cloud, Andrew N.; Abelson, John R., E-mail: abelson@illinois.edu [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 W. Green St., Urbana, Illinois 61801 (United States); Davis, Luke M.; Girolami, Gregory S., E-mail: girolami@scs.illinois.edu [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801 (United States)

2014-03-15

231

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

PubMed Central

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

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

2014-01-01

232

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

PubMed Central

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

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

2015-01-01

233

Vibrational frequency analysis, FT-IR, DFT and M06-2X studies on tert-Butyl N-(thiophen-2yl)carbamate  

NASA Astrophysics Data System (ADS)

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized tert-Butyl N-(thiophen-2yl)carbamate have been investigated. The experimental FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with the 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The vibrational frequencies have been assigned using potential energy distribution (PED) analysis by using VEDA 4 software. The computational optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data, and with related literature results. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and are depicted.

Sert, Yusuf; Singer, L. M.; Findlater, M.; Do?an, Hatice; Ç?rak, Ç.

2014-07-01

234

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

PubMed

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

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

2014-12-01

235

Vibrational frequency analysis, FT-IR, DFT and M06-2X studies on tert-Butyl N-(thiophen-2yl)carbamate.  

PubMed

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized tert-Butyl N-(thiophen-2yl)carbamate have been investigated. The experimental FT-IR (4000-400 cm(-1)) spectrum of the molecule in the solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with the 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The vibrational frequencies have been assigned using potential energy distribution (PED) analysis by using VEDA 4 software. The computational optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data, and with related literature results. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and are depicted. PMID:24657467

Sert, Yusuf; Singer, L M; Findlater, M; Do?an, Hatice; Ç?rak, Ç

2014-07-15

236

Non-Specific Inhibition of Ischemia- and Acidosis-Induced Intracellular Calcium Elevations and Membrane Currents by ?-Phenyl-N-tert-butylnitrone, Butylated Hydroxytoluene and Trolox  

PubMed Central

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

Katnik, Christopher; Cuevas, Javier

2014-01-01

237

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies  

SciTech Connect

Water–tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with x{sub TBA} ? 0.03–0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at x{sub TBA} ? 0.05. We note that “islands” of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, x{sub TBA} ? 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman, E-mail: bbagchi@sscu.iisc.ernet.in [SSCU, Indian Institute of Science, Bangalore 560012 (India)] [SSCU, Indian Institute of Science, Bangalore 560012 (India)

2014-05-21

238

Antioxidative effects of cherry leaves extract on tert-butyl hydroperoxide-mediated cytotoxicity through regulation of thioredoxin-2 protein expression levels.  

PubMed

Components of cherry trees have been used as traditional herbal remedies for various diseases. These components are known to possess antioxidative effects. However, the mechanisms underlying cherry tree component-mediated antioxidative effects remain largely unknown. This study focused on cherry leaves extract (CLE) and examined the mechanism underlying the effect of CLE on tert-butyl hydroperoxide (t-BOOH)-induced melanocytic cell death with DNA damage. Interestingly, CLE prevented t-BOOH-induced cell death with reduction in DNA damage, p38 kinase activation, and reactive oxygen species (ROS) production. CLE-mediated suppression of cell death with reduction of DNA damage, p38 kinase activity and ROS production was prevented by a thioredoxin (Trx) system inhibitor but not by a glutathione (GSH) system inhibitor. Finally, data showed that CLE prevented t-BOOH-induced reduction of Trx2 but not Trx1 and Trx reductases (TrxR1 and TrxR2) protein expression. Thus, our results suggest that CLE prevents t-BOOH-induced reduction in Trx2 expression, promotion of ROS production, activation of p38 kinase, and increase in DNA damage and that it protects against cell death. PMID:21797775

Taguchi, Nobuhiko; Uemura, Noriyuki; Goto, Yuji; Sakura, Masaaki; Hara, Kazuhiro; Niwa, Masanao; Iida, Machiko; Yanagishita, Takeshi; Watanabe, Daisuke; Kato, Masashi

2011-01-01

239

Donepezil, tacrine and alpha-phenyl-n-tert-butyl nitrone (PBN) inhibit choline transport by conditionally immortalized rat brain capillary endothelial cell lines (TR-BBB).  

PubMed

In the present study, we have characterized the choline transport system and examined the influence of various amine drugs on the choline transporter using a conditionally immortalized rat brain capillary endothelial cell line (TR-BBB) in vitro. The cell-to-medium (C/M) ratio of [3H]choline in TR-BBB cells increased time-dependently. The initial uptake rate of [3H]choline was concentration-dependent with a Michaelis-Menten value, Km, of 26.2 +/- 2.7 microM. The [3H]choline uptake into TR-BBB was Na+-independent, but was membrane potential-dependent. The [3H]choline uptake was susceptible to inhibition by hemicholinium-3, and tetraethylammonium (TEA), which are organic cation transporter substrates. Also, the uptake of [3H]choline was competitively inhibited with Ki values of 274 microM, 251 microM and 180 microM in the presence of donepezil hydrochloride, tacrine and alpha-phenyl-n-tert-butyl nitrone (PBN), respectively. These characteristics of choline transport are consistent with those of the organic cation transporter (OCT). OCT2 mRNA was expressed in TR-BBB cells, while the expression of OCT3 or choline transporter (CHT) was not detected. Accordingly, these results suggest that OCT2 is a candidate for choline transport at the BBB and may influence the BBB permeability of amine drugs. PMID:15918518

Kang, Young-Sook; Lee, Kyeong-Eun; Lee, Na-Young; Terasaki, Tetsuya

2005-04-01

240

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

PubMed

Four derivatives of N-trimellitylimido-L-amino acid (4a-4d) were prepared by the reaction of trimellitic anhydride (1) with the L-amino acids (2a-2d) in acetic acid as diacid monomers and were used with the aim to obtain a new family of amino acid based poly(ester-imide)s (PEI)s. The polymerization was performed by direct polycondensation of chiral diacids (4a-4d) with 4,4'-thiobis(2-tert-butyl-5-methylphenol) (5) in the presence of tosyl chloride (TsCl), pyridine and N,N-dimethyl formamide (DMF). Step-growth polymerization was carried out by varying the time of heating and the molar ratio of TsCl/diacid and the optimum conditions were achieved. The synthesized polymers were characterized by means of specific rotation experiments, FT-IR, 1H-NMR, X-ray diffraction techniques and elemental analysis. The surface morphology of the obtained polymers was studied by field emission scanning electron microscopy. The result showed nanostructure morphology of the resulting polymers. The obtained PEIs were soluble in polar aprotic solvents such as DMF, N,N-dimethyl acetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone and protic solvents such as sulfuric acid. Thermal stability and the weight-loss behavior of the PEIs were studied by thermal gravimetric analysis (TGA) techniques. TGA showed that the 10% weight loss temperature in a nitrogen atmosphere was more than 402°C, therefore they had useful levels of thermal stability associated with excellent solubility. PMID:21691754

Mallakpour, Shadpour; Soltanian, Samaneh

2012-06-01

241

Magnetic scanometric DNA microarray detection of methyl tertiary butyl ether degrading bacteria for environmental monitoring.  

PubMed

A magnetoresistive biosensing platform based on a single magnetic tunnel junction (MTJ) scanning probe and DNA microarrays labeled with magnetic particles has been developed to provide an inexpensive, sensitive and reliable detection of DNA. The biosensing platform was demonstrated on a DNA microarray assay for quantifying bacteria capable of degrading methyl tertiary butyl ether (MTBE), where concentrations as low as 10 pM were detectable. Synthetic probe bacterial DNA was immobilized on a microarray glass slide surface, hybridized with the 48 base pair long biotinylated target DNA and subsequently incubated with streptavidin-coated 2.8 ?m diameter magnetic particles. The biosensing platform then makes use of a micron-sized MTJ sensor that was raster scanned across a 3 mm by 5 mm glass slide area to capture the stray magnetic field from the tagged DNA and extract two dimensional magnetic field images of the microarray. The magnetic field output is then averaged over each 100 ?m diameter DNA array spot to extract the magnetic spot intensity, analogous to the fluorescence spot intensity used in conventional optical scanners. The magnetic scanning result is compared with results from a commercial laser scanner and particle coverage optical counting to demonstrate the dynamic range and linear sensitivity of the biosensing platform as a potentially inexpensive, sensitive and portable alternative for DNA microarray detection for field applications. PMID:20889328

Chan, Mei-Lin; Jaramillo, Gerardo; Hristova, Krassimira R; Horsley, David A

2011-01-15

242

Magnetic Scanometric DNA Microarray Detection of Methyl Tertiary Butyl Ether Degrading Bacteria for Environmental Monitoring  

PubMed Central

A magnetoresistive biosensing platform based on a single magnetic tunnel junction (MTJ) scanning probe and DNA microarrays labeled with magnetic particles has been developed to provide an inexpensive, sensitive and reliable detection of DNA. The biosensing platform was demonstrated on a DNA microarray assay for quantifying bacteria capable of degrading methyl tertiary-butyl ether (MTBE), where concentrations as low as 10 pM were detectable. Synthetic probe bacterial DNA was immobilized on a microarray glass slide surface, hybridized with the 48 base pair long biotinylated target DNA and subsequently incubated with streptavidin-coated 2.8 ?m diameter magnetic particles. The biosensing platform then makes use of a micron-sized MTJ sensor that was raster scanned across a 3 mm by 5 mm glass slide area to capture the stray magnetic field from the tagged DNA and extract two dimensional magnetic field images of the microarray. The magnetic field output is then averaged over each 100 ?m diameter DNA array spot to extract the magnetic spot intensity, analogous to the fluorescence spot intensity used in conventional optical scanners. The magnetic scanning result is compared with results from a commercial laser scanner and particle coverage optical counting to demonstrate the dynamic range and linear sensitivity of the biosensing platform as a potentially inexpensive, sensitive and portable alternative for DNA microarray detection for field applications. PMID:20889328

Chan, Mei-Lin; Jaramillo, Gerardo; Hristova, Krassimira R.; Horsley, David A.

2010-01-01

243

Adsorption of Methyl Tertiary Butyl Ether on Granular Zeolites: Batch and Column Studies  

PubMed Central

Methyl tertiary butyl ether (MTBE) has been shown to be readily removed from water with powdered zeolites, but the passage of water through fixed beds of very small powdered zeolites produces high friction losses not encountered in flow through larger sized granular materials. In this study, equilibrium and kinetic adsorption of MTBE onto granular zeolites, a coconut shell granular activated carbon (CS-1240), and a commercial carbon adsorbent (CCA) sample was evaluated. In addition, the effect of natural organic matter (NOM) on MTBE adsorption was evaluated. Batch adsorption experiments determined that ZSM-5 was the most effective granular zeolite for MTBE adsorption. Further equilibrium and kinetic experiments verified that granular ZSM-5 is superior to CS-1240 and CCA in removing MTBE from water. No competitive-adsorption effects between NOM and MTBE were observed for adsorption to granular ZSM-5 or CS-1240, however there was competition between NOM and MTBE for adsorption onto the CCA granules. Fixed-bed adsorption experiments for longer run times were performed using granular ZSM-5. The bed depth service time model (BDST) was used to analyze the breakthrough data. PMID:20153106

Abu-Lail, Laila; Bergendahl, John A.; Thompson, Robert W.

2010-01-01

244

Toxicity of methyl tertiary butyl ether to Daphnia magna and photobacterium phosphoreum  

SciTech Connect

Methyl tertiary butyl ether (MTBE) is a liquid organic compound added to gasoline to increase its oxygen content and to reduce the emission of carbon monoxide during combustion in many urban areas. In order to meet the 1990 Clean Air Act amendments, gasoline must contain 2.7% oxygen (by weight) or 15% (by volume) of MTBE in gasoline to meet the regulations for the control of carbon monoxide emissions. Health effects caused by inhalation of MTBE include headaches, dizziness, irritated eyes and nausea; MTBE is one of cancer--causing chemicals. Intracaval injection of MTBE (0.2 mg/kg) caused the highest mortality (100%) in rats. General anesthetic effect induced by MTBE was found at or above 1200 mg/kg body weight; Rosenkranz and Klopman (1991) predicted that MTBE is neither a genotoxicant nor a carcinogen. Nevertheless, the safety of using MTBE in oxygenated fuels is now being questioned from its potential as groundwater pollutant. This study measures the toxicity of MTBE to Daphnia magna and Photobacterium phosphoreum. 13 refs.

Gupta, G.; Lin, Y.J. [Univ. of Maryland Eastern Shore, Princess Anne, MD (United States)

1995-10-01

245

1,3-Bis(4-tert-butyl­benz­yl)pyrimidine-2,4(1H,3H)-dione  

PubMed Central

In the crystal structure of the title mol­ecule, C26H32N2O2, the six methyl groups are disordered over two positions, with site-occupancy ratios of 0.665?(8):0.335?(8) and 0.639?(8):0.361?(8). The central pyrimidine ring is almost planar with an r.m.s. deviation of 0.009?Å. The dihedral angles formed by the two benzene rings with the pyrimidine ring are 70.70?(8) and 88.02?(9)°. The dihedral angle between two benzene rings is 46.67?(10)°. PMID:21837016

Li, Gong-Chun; Wang, Hong-Sheng; Zhu, Feng-Xiang; Niu, Yu-Jiao

2011-01-01

246

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

PubMed Central

Background The study was carried out to determine the cytotoxic, antioxidant and gastro-protective effect of ethyl-4-[(3,5-di-tert-butyl-2-hydroxybenzylid ene)amino] benzoate (ETHAB) in rats. Methodology/Principal Findings The cytotoxic effect of ETHAB was assessed using a MTT cleavage assay on a WRL68 cell line, while its antioxidant activity was evaluated in vitro. In the anti-ulcer study, rats were divided into six groups. Group 1 and group 2 received 10% Tween 20 (vehicle). Group 3 received 20 mg/kg Omeprazole. Groups 4, 5 and 6 received ETHAB at doses of 5, 10, and 20 mg/kg, respectively. After an hour, group 1 received the vehicle. Groups 2–6 received absolute ethanol to induce gastric mucosal lesions. In the WRL68 cell line, an IC50 of more than 100 µg/mL was observed. ETHAB results showed antioxidant activity in the DPPH, FRAP, nitric oxide and metal chelating assays. There was no acute toxicity even at the highest dosage (1000 mg/kg). Microscopy showed that rats pretreated with ETHAB revealed protection of gastric mucosa as ascertained by significant increases in superoxide dismutase (SOD), pH level, mucus secretion, reduced gastric lesions, malondialdehyde (MDA) level and remarkable flattened gastric mucosa. Histologically, pretreatment with ETHAB resulted in comparatively better gastric protection, due to reduction of submucosal edema with leucocyte infiltration. PAS staining showed increased intensity in uptake of Alcian blue. In terms of immunohistochemistry, ETHAB showed down-expression of Bax proteins and over-expression of Hsp70 proteins. Conclusion/Significance The gastroprotective effect of ETHAB may be attributed to antioxidant activity, increased gastric wall mucus, pH level of gastric contents, SOD activity, decrease in MDA level, ulcer area, flattening of gastric mucosa, reduction of edema and leucocyte infiltration of the submucosal layer, increased PAS staining, up-regulation of Hsp70 protein and suppressed expression of Bax. Key words: ethyl 4-(3, 5-di-ter-butyl-2-hydroxybenzylamino) benzoate; toxicity; antioxidant; gastric-ulcer; anti-ulcer; histology; immunohistochemistry. PMID:24800807

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

2014-01-01

247

Dynamics of Back Electron Transfer in Dye-Sensitized Solar Cells Featuring 4-tert-Butyl-Pyridine and Atomic-Layer-Deposited Alumina as Surface Modifiers.  

PubMed

A series of dye-sensitized solar cells (DSCs) was constructed with TiO2 nanoparticles and N719 dye. The standard I3(-)/I(-) redox shuttle and the Co(1,10-phenanthroline)3(3+/2+) shuttle were employed. DSCs were modified with atomic-layered-deposited (ALD) coatings of Al2O3 and/or with the surface-adsorbing additive 4-tert-butyl-pyridine. Current-voltage data were collected to ascertain the influence of each modification upon the back electron transfer (ET) dynamics of the DSCs. The primary effect of the additives alone or in tandem is to increase the open-circuit voltage. A second is to alter the short-circuit current density, JSC. With dependence on the specifics of the system examined, any of a myriad of dynamics-related effects were observed to come into play, in both favorable (efficiency boosting) and unfavorable (efficiency damaging) ways. These effects include modulation of (a) charge-injection yields, (b) rates of interception of injected electrons by redox shuttles, and (c) rates of recombination of injected electrons with holes on surface-bound dyes. In turn, these influence charge-collection lengths, charge-collection yields, and onset potentials for undesired dark current. The microscopic origins of the effects appear to be related mainly to changes in driving force and/or electronic coupling for underlying component redox reactions. Perhaps surprisingly, only a minor role for modifier-induced shifts in conduction-band-edge energy was found. The combination of DSC-efficiency-relevant effects engendered by the modifiers was found to vary substantially as a function of the chemical identity of the redox shuttle employed. While types of modifiers are effective, a challenge going forward will be to construct systems in ways in which the benefits of organic and inorganic modifiers can be exploited in fully additive, or even synergistic, fashion. PMID:25127076

Katz, Michael J; DeVries Vermeer, Michael J; Farha, Omar K; Pellin, Michael J; Hupp, Joseph T

2014-08-25

248

Simultaneous determination of organotin compounds in textiles by gas chromatography-flame photometry following liquid/liquid partitioning with tert-butyl ethyl ether after reflux-extraction.  

PubMed

A rapid and relatively clean method for determining six organotin compounds (OtC) in textile goods with a gas chromatograph equipped with a conventional flame photometric detector (GC-FPD) has been developed. After the reflux-extraction to use methanol containing 1% (v/v) of hydrochloric acid, five hydrophobic OtC (e.g. tributyltin: TBT) and slightly less hydrophobic dibutyltin (DBT) could be drawn out through partitioning between the methanolic buffer solution and tert-butyl ethyl ether instead of hazardous dichloromethane, of which usage is provided by the official-methods notified in Japan, and following the ethylation procedure to use sodium tetraethylborate, the OtC were determined with the GC-FPD. The recoveries of DBT, TBT, tetrabutyltin, triphenyltin, dioctyltin, and trioctyltin from textile products (cloth diaper, socks, and undershirt) were 60-77, 89-98, 86-94, 71-78, 85-109, and 70-79% respectively, and their coefficients of variation were 2.5-16.5%. Calibration curves for OtC were linear (0.01-0.20 ?g as Sn mL(-1)), and the correlation coefficients were 0.9922-1.0000. Their detection limits were estimated to be 2.7-9.7 n gas Sn g(-1). These data suggested that this method would be applicable to their simultaneous determination. Five retailed textile goods were analyzed by this proposed method, and 0.013-0.65 µg as Sn g(-1) of OtC (e.g. DBT) were determined in three. Moreover, a possibility that various OtC including non-targeted species in textile would be specifically detected by applying the studying speciation-technique of controlling signal intensity-flame fuel gas pressures of the GC-FPD was found. PMID:24054605

Hamasaki, Tetsuo

2013-10-15

249

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

PubMed Central

Rhodococcus ruber (formerly Gordonia terrae) IFP 2001 is one of a few bacterial strains able to degrade ethyl tert-butyl ether (ETBE), which is a major pollutant from gasoline. This strain was found to undergo a spontaneous 14.3-kbp chromosomal deletion, which results in the loss of the ability to degrade ETBE. Sequence analysis of the region corresponding to the deletion revealed the presence of a gene cluster, ethABCD, encoding a ferredoxin reductase, a cytochrome P-450, a ferredoxin, and a 10-kDa protein of unknown function, respectively. The EthB and EthD proteins could be easily detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were induced by ETBE in the wild-type strain. Upstream of ethABCD lies ethR, which codes for a putative positive transcriptional regulator of the AraC/XylS family. Transformation of the ETBE-negative mutant by a plasmid carrying the ethRABCD genes restored the ability to degrade ETBE. Complementation was abolished if the plasmid carried ethRABC only. The eth genes are located in a DNA fragment flanked by two identical direct repeats of 5.6 kbp. The ETBE-negative mutants carry a single copy of this 5.6-kbp repeat, suggesting that the 14.3-kbp chromosomal deletion resulted from a recombination between the two identical sequences. The 5.6-kbp repeat is a class II transposon carrying a TnpA transposase, a truncated form of the recombinase TnpR, and a terminal inverted repeat of 38 bp. The truncated TnpR is encoded by an IS3-interrupted tnpR gene. PMID:11673424

Chauvaux, Sylvie; Chevalier, Fabien; Le Dantec, Corinne; Fayolle, Françoise; Miras, Isabelle; Kunst, Frank; Beguin, Pierre

2001-01-01

250

?-Phenyl-n-tert-butyl-nitrone Attenuates Lipopolysaccharide-induced Brain Injury and Improves Neurological Reflexes and Early Sensorimotor Behavioral Performance in Juvenile Rats  

PubMed Central

Our previous study showed that treatment with ?-phenyl-n-tert-butyl-nitrone (PBN) after exposure to lipopolysaccharide (LPS) reduced LPS-induced white matter injury in the neonatal rat brain. The object of the current study was to further examine whether PBN has long-lasting protective effects and ameliorates LPS-induced neurological dysfunction. Intracerebral (i.c.) injection of LPS (1 mg/kg) was performed in postnatal day (P) 5 Sprague Dawley rat pups and PBN (100 mg/kg) or saline was administered intraperitoneally 5 min after LPS injection. The control rats were injected (i.c.) with sterile saline. Neurobehavioral tests were carried out from P3 to P21, and brain injury was examined after these tests. LPS exposure resulted in severe brain damage, including enlargement of ventricles bilaterally, loss of mature oligodendrocytes, impaired myelination as indicated by the decrease in myelin basic protein immunostaining, and alterations in dendritic processes in the cortical gray matter of the parietal cortex. Electron microscopic examination showed that LPS exposure caused impaired myelination as indicated by the disintegrated myelin sheaths in the juvenile rat brain. LPS administration also significantly affected neurobehavioral functions such as performance in righting reflex, wire hanging maneuver, cliff avoidance, negative geotaxis, vibrissa-elicited forelimb-placing test, beam walking, and gait test. Treatment with PBN, a free radical scavenger and antioxidant, provided protection against LPS-induced brain injury and associated neurological dysfunction in juvenile rats, suggesting that antioxidation might be an effective approach for therapeutic treatment of neonatal brain injury induced by infection/inflammation. PMID:18683243

Fan, Lir-Wan; Chen, Ruei-Feng; Mitchell, Helen J.; Lin, Rick C. S.; Simpson, Kimberly L.; Rhodes, Philip G.; Cai, Zhengwei

2010-01-01

251

Coordination effects on electron distributions for rhodium complexes of the redox-active bis(3,5-di-tert-butyl-2-phenolate)amide ligand.  

PubMed

New rhodium complexes of bis(3,5-di-tert-butyl-2-phenol)amine ([ONO(cat)]H(3)) were synthesized, and their electronic properties were investigated. These compounds were prepared by combining [ONO(q)]K and [(cod)Rh(?-Cl)](2) in the presence of an auxiliary donor ligand to yield complexes of the type [ONO]RhL(n) (n = 3, L = py (1); n = 2, L = PMe(3) (2a), L = PMe(2)Ph (2b), PMePh(2) (2c), PPh(3) (2d)). Single-crystal X-ray diffraction studies on [ONO]Rh(py)(3) (1) revealed a six-coordinate, octahedral rhodium complex. In the case of [ONO]Rh(PMe(3))(2) (2a), X-ray diffraction showed a five-coordinate, distorted square-pyramidal coordination environment around the rhodium center. While 1 is static on the NMR time scale, complexes 2a-d are fluxional, displaying both rapid isomerization of the square-pyramidal structure and exchange of coordinated and free phosphine ligands. UV-vis spectroscopy shows stark electronic differences between 1 and 2a-d. Whereas 1 displays a strong absorbance at 380 nm with a much weaker band at 585 nm in the absorption spectrum, complexes 2a-d display an intense (? > 10(4) M(-1) cm(-1)), low-energy absorption band in the region 580-640 nm; however, in the cases of 2a and 2b, the addition of excess phosphine resulted in changes to the UV-vis spectrum indicating the formation of six-coordinate adducts [ONO]Rh(PMe(3))(3) (3a) and [ONO]Rh(PMe(2)Ph)(3) (3b), respectively. The experimental and DFT computational data for the six-coordinate complexes 1, 3a, and 3b are consistent with their formulation as classical, d(6), pseudo-octahedral, coordination complexes. In the five-coordinate complexes 2a-2d, ?-bonding between the rhodium center and the [ONO] ligand leads to a high degree of covalency and metal-ligand electron distributions that are not accurately described by formal oxidation state assignments. PMID:22482509

Szigethy, Géza; Shaffer, David W; Heyduk, Alan F

2012-12-01

252

Tris(4,4?-di-tert-butyl-2,2?-bipyridine-?2 N,N?)molybdenum(II) ?6-oxido-dodeca-?2-oxido-hexa­oxidohexa­molybdate(VI) acetonitrile tetra­solvate  

PubMed Central

The asymmetric unit of the title compound, [Mo(C18H24N2)3][Mo6O19]·4CH3CN, comprises an [Mo(di-t-Bu-bipy)3]2+ cation (di-t-Bu-bipy is 4,4?-di-tert-butyl-2,2?-bipyridine), two halves of Lindqvist-type [Mo6O19]2? anions (with each anion completed by the application of a center of inversion) and four acetonitrile solvent mol­ecules. The geometry around the metal atom of the cation resembles a distorted octa­hedron, with each of the three di-t-Bu-bipy ligands being almost planar [deviation from planarity < 6.3?(2)°]. Supra­molecular inter­actions, namely Mo=O??, C N??, C—H?O and C—H?N, along with electrostatic forces, mediate the crystal packing. Two of the tert-butyl groups are affected by rotational disorder which was modeled over two distinct positions with major site occupancies of 0.707?(9) and 0.769?(8). PMID:22199605

Amarante, Tatiana R.; Fernandes, José A.; Gonçalves, Isabel S.; Almeida Paz, Filipe A.

2011-01-01

253

Induction of Methyl Tertiary Butyl Ether (MTBE)-Oxidizing Activity in Mycobacterium vaccae JOB5 by MTBE  

PubMed Central

Alkane-grown cells of Mycobacterium vaccae JOB5 cometabolically degrade the gasoline oxygenate methyl tertiary butyl ether (MTBE) through the activities of an alkane-inducible monooxygenase and other enzymes in the alkane oxidation pathway. In this study we examined the effects of MTBE on the MTBE-oxidizing activity of M. vaccae JOB5 grown on diverse nonalkane substrates. Carbon-limited cultures were grown on glycerol, lactate, several sugars, and tricarboxylic acid cycle intermediates, both in the presence and absence of MTBE. In all MTBE-containing cultures, MTBE consumption occurred and tertiary butyl alcohol (TBA) and tertiary butyl formate accumulated in the culture medium. Acetylene, a specific inactivator of alkane- and MTBE-oxidizing activities, fully inhibited MTBE consumption and product accumulation but had no other apparent effects on culture growth. The MTBE-dependent stimulation of MTBE-oxidizing activity in fructose- and glycerol-grown cells was saturable with respect to MTBE concentration (50% saturation level = 2.4 to 2.75 mM), and the onset of MTBE oxidation in glycerol-grown cells was inhibited by both rifampin and chloramphenicol. Other oxygenates (TBA and tertiary amyl methyl ether) also induced the enzyme activity required for their own degradation in glycerol-grown cells. Presence of MTBE also promoted MTBE oxidation in cells grown on organic acids, compounds that are often found in anaerobic, gasoline-contaminated environments. Experiments with acid-grown cells suggested induction of MTBE-oxidizing activity by MTBE is subject to catabolite repression. The results of this study are discussed in terms of their potential implications towards our understanding of the role of cometabolism in MTBE and TBA biodegradation in gasoline-contaminated environments. PMID:14766585

Johnson, Erika L.; Smith, Christy A.; O'Reilly, Kirk T.; Hyman, Michael R.

2004-01-01

254

Experimental neuropathy produced by 2,5-hexanedione--a major metabolite of the neurotoxic industrial solvent methyl n-butyl ketone  

Microsoft Academic Search

Chronic exposure of rats to 2,5-hexanedione (CH3COCH2CH2COCH3), a major metabolite of the neurotoxic industrial solvent methyl n-buryl ketone (CH3COCH2CH2CH2CH3), has been shown to cause a clinical peripheral neuropathy with dying-back peripheral and central nervous system degeneration characterized by giant axonal swellings filled with neurofilaments. This pattern of disease is similar to that produced by methyl n-butyl ketone.

P S Spencer; H H Schaumburg

1975-01-01

255

AN EXPERIMENTAL STUDY OF PHYTOREMEDIATION OF METHYL-TERT-BUTYL-ETHER (MTBE) IN GROUNDWATER. (R825549C062)  

EPA Science Inventory

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

256

IDENTIFYING THE USAGE PATTERNS OF METHYL TERT-BUTYL ETHER (MTBE) AND OTHER OXYGENATES IN GASOLINE USING GASOLINE  

E-print Network

to reduce levels of ozone and carbon monoxide in areas where air quality standards have not been attained in areas that do not meet National Ambient Air Quality Standards (NAAQS) for carbon monoxide and ozone if regulations meant to improve the Nation's air quality have resulted in inadvertent, detrimental effects

257

Spectroscopic (FT-IR, FT-Raman), first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 5-tert-Butyl-6-chloro-N-[(4-(trifluoromethyl)phenyl]pyrazine-2-carboxamide  

NASA Astrophysics Data System (ADS)

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-tert-Butyl-6-chloro-N-[(4-(trifluoromethyl)phenyl]pyrazine-2-carboxamide have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of normal modes of vibrations was done using GAR2PED program. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. From the NBO analysis it is evident that the increased electron density at the nitrogen, carbon atoms leads to the elongation of respective bond length and a lowering of the corresponding stretching wave number. The calculated geometrical parameters are in agreement with that of similar derivatives. The calculated first hyperpolarizability is high and the calculated data suggest an extended ?-electron delocalization over the pyrazine ring and carboxamide moiety which is responsible for the nonlinearity of the molecule.

Bhagyasree, J. B.; Varghese, Hema Tresa; Panicker, C. Yohannan; Van Alsenoy, Christian; Al-Saadi, Abdulaziz A.; Dolezal, Martin; Samuel, Jadu

2015-02-01

258

Effects of bile salts and other carboxylates on the reactions of N-tert-butyl-2,4,6-trinitrobenzamide in dimethyl sulfoxide-water solutions  

E-print Network

. Interactions in DMSO/H 0 solutions of sodium deoxycholate . Rate of appearance of hitrite ion in sodium deoxycholate solutions. Thermodynamic parameters for complex formation in solutions of sodium deoxycholate . Complex formation in DMSO/H 0 solutions...-t-Butyl-2, 4, 6-trinitrobenzamide and its Meisenheimer Complexes in DMSO-d6 XVII Rate of Complex Decomposition in Sodium Deoxycholate 103 Solution at 25. 0'C. . . 104 XVIII Rate Constants for Complex Formation at 25. 0'C in Sodium Deoxycholate...

Koranek, David James

2012-06-07

259

Concentration fluctuations and collective properties in mixed liquid systems: Rayleigh-Brillouin spectra of tert-butyl alcohol\\/ 2,2'-dimethylbutane liquid mixture  

Microsoft Academic Search

Rayleigh-Brillouin spectra have been measured in a range of temperatures and compositions of t-butyl alcohol\\/2,2'-dimethylbutane liquid mixture. The mixture mole fraction has been varied from pure alkane (xTBA=0) to pure alcohol (xTBA=1) at temperatures between 283 and 323 K. In the same composition and temperature ranges the authors also executed measurements of mass density, shear viscosity, and refractive index. From

Rosario Sergio Cataliotti; Francesca Palombo; Marco Paolantoni; Poala Sassi; Antonio Raudino

2007-01-01

260

The Role of Metabolism in Establishing Chemical-Specific Adjustment Factors for n-Hexane and Methyl n-Butyl Ketone  

Microsoft Academic Search

This paper focuses on the derivation of chemical-specific adjustment factors (CSAFs) for two neurotoxic solvents, n-hexane and methyl n-butyl ketone (MBK). Workers are exposed to the chemicals mainly via inhalation when they are used, for example, as solvents in adhesives. In order to derive CSAFs for n-hexane and MBK, research data were used from animal studies conducted in our laboratory.

Gloria A. Skowronski; Mohamed S. Abdel-Rahman

2004-01-01

261

Structural Characterization of Hydroxyl-Terminated Polybutadiene-Bound 2, 2-Thiobis(4-methyl-6-tert-butylphenol) and Its Thermo-Oxidative Aging Resistance for Natural Rubber Vulcanizates  

Microsoft Academic Search

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

Yonghong Wang; Xingrong Zeng; Hongqiang Li; Jianhua Guo

2012-01-01

262

Seasonal and daily variations in concentrations of methyl-tertiary-butyl ether (MTBE) at Cranberry Lake, New Jersey  

USGS Publications Warehouse

Methyl-tertiary-butyl ether (MTBE), an additive used to oxygenate gasoline, has been detected in lakes in northwestern New Jersey. This occurrence has been attributed to the use of gasoline-powered watercraft. This paper documents and explains both seasonal and daily variations in MTBE concentrations at Cranberry Lake. During a recent boating season (late April to September 1999), concentrations of MTBE typically exceeded 20??g/L. MTBE concentrations varied daily from 12 to 24??g/L over a 2-week period that included the Labor Day holiday. Concentrations were highest on weekends when there is more boat traffic, which had an immediate effect on MTBE mass throughout the lake. MTBE concentrations decreased to about 2??g/L shortly after the end of the summer recreational season. The loss of MTBE can be accounted for by volatilization, with a half-life on the order of 10 days. The volatilization rate was modeled with the daily decrease in MTBE then the modeled rate was validated using the data from the seasonal decline. ?? 2003 Elsevier Science Ltd. All rights reserved.

Toran, L.; Lipka, C.; Baehr, A.; Reilly, T.; Baker, R.

2003-01-01

263

Speciated hydrocarbon and carbon monoxide emissions from an internal combustion engine operating on methyl tertiary butyl ether-containing fuels.  

PubMed

In the present work, engine and tailpipe (after a three-way catalytic converter) emissions from an internal combustion engine operating on two oxygenated blend fuels [containing 2 and 11% weight/weight (w/w) methyl tertiary butyl ether (MTBE)] and on a nonoxygenated base fuel were characterized. The engine (OPEL 1.6 L) was operated under various conditions, in the range of 0-20 HP. Total unburned hydrocarbons, carbon monoxide, methane, hexane, ethylene, acetaldehyde, acetone, 2-propanol, benzene, toluene, 1,3-butadiene, acetic acid, and MTBE were measured at each engine operating condition. As concerns the total HC emissions, the use of MTBE was beneficial from 1.90 to 3.81 HP, which were by far the most polluting conditions. Moreover, CO emissions in tailpipe exhaust were decreased in the whole operation range with increasing MTBE in the fuel. The greatest advantage of MTBE addition to gasoline was the decrease in ethylene, acetaldehyde, benzene, toluene, and acetic acid emissions in engine exhaust, especially when MTBE content in the fuel was increased to 11% w/w. In tailpipe exhaust, the catalyst operation diminished the observed differences. Ethylene, methane, and acetaldehyde were the main compounds present in exhaust gases. Ethylene was easily oxidized over the catalyst, while acetaldehyde and methane were quite resistant to oxidation. PMID:15658218

Poulopoulos, S G; Philippopoulos, C J

2001-07-01

264

Formation of Alkenes via Degradation of tert-Alkyl Ethers and Alcohols by Aquincola tertiaricarbonis L108 and Methylibium spp. ?†  

PubMed Central

Bacterial degradation pathways of fuel oxygenates such as methyl tert-butyl and tert-amyl methyl ether (MTBE and TAME, respectively) have already been studied in some detail. However, many of the involved enzymes are still unknown, and possible side reactions have not yet been considered. In Aquincola tertiaricarbonis L108, Methylibium petroleiphilum PM1, and Methylibium sp. strain R8, we have now detected volatile hydrocarbons as by-products of the degradation of the tert-alkyl ether metabolites tert-butyl and tert-amyl alcohol (TBA and TAA, respectively). The alkene isobutene was formed only during TBA catabolism, while the beta and gamma isomers of isoamylene were produced only during TAA conversion. Both tert-alkyl alcohol degradation and alkene production were strictly oxygen dependent. However, the relative contribution of the dehydration reaction to total alcohol conversion increased with decreasing oxygen concentrations. In resting-cell experiments where the headspace oxygen content was adjusted to less than 2%, more than 50% of the TAA was converted to isoamylene. Isobutene formation from TBA was about 20-fold lower, reaching up to 4% alcohol turnover at low oxygen concentrations. It is likely that the putative tert-alkyl alcohol monooxygenase MdpJ, belonging to the Rieske nonheme mononuclear iron enzymes and found in all three strains tested, or an associated enzymatic step catalyzed the unusual elimination reaction. This was also supported by the detection of mdpJK genes in MTBE-degrading and isobutene-emitting enrichment cultures obtained from two treatment ponds operating at Leuna, Germany. The possible use of alkene formation as an easy-to-measure indicator of aerobic fuel oxygenate biodegradation in contaminated aquifers is discussed. PMID:21742915

Schäfer, Franziska; Muzica, Liudmila; Schuster, Judith; Treuter, Naemi; Rosell, Mònica; Harms, Hauke; Müller, Roland H.; Rohwerder, Thore

2011-01-01

265

Generation of reactive intermediates from the tumor promoter butylated hydroxytoluene hydroperoxide in isolated murine keratinocytes or by hematin.  

PubMed

BHTOOH (2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone), a metabolite of the food antioxidant BHT (2,6-di-tert-butyl-4-methylphenol), has previously been shown to function as a tumor promoter in mouse skin. The metabolism of BHTOOH was examined to assess the role of reactive intermediates in mediating tumor promotion in this tissue. Free radical metabolites of BHTOOH were characterized in either isolated neonatal mouse keratinocytes or a cell-free hematin system using electron paramagnetic resonance (EPR) spectroscopy while non-radical, EPR silent products were characterized using HPLC separation coupled with UV or mass spectral detection. Incubation of BHTOOH with keratinocytes or hematin resulted in the generation of the BHT-phenoxyl radical detectable by EPR spectroscopy. Formation of the BHT-phenoxyl radical was prevented by heat inactivation of the cells prior to exposure to BHTOOH. Only one non-radical metabolite of BHTOOH was detected in keratinocytes: BHT-quinol (2,6-di-tert-butyl-4-methyl-4-hydroxyl-2,5-cyclohexadienone), while incubation of BHTOOH with hematin produced several metabolites: oxacyclopentenone (2,5-di-tert-butyl-5-(2'-oxopropyl)-4-oxa-2-cyclopentenone), BHT-quinone (2,6-di-tert-butyl-p-benzoquinone), BHT, BHT-stilbenequinone (3,5,3',5'-tetra-tert-butylstilbene-4,4'-quinone), and BHT-quinone methide (2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone). Thus, radical as well as non-radical reactive intermediates can be formed during metabolism of BHTOOH. Several of the stable metabolites of BHTOOH were evaluated for possible promoter activity in a short-term bioassay, induction of ornithine decarboxylase (ODC) activity in mouse skin. In contrast to the action of BHTOOH, topical application of equimolar doses of BHT-quinol, BHT-quinone, BHT-stilbenequinone, as well as BHT itself, did not induce epidermal ODC activity. Thus, reactive metabolites of BHTOOH such as the BHT-phenoxyl radical or BHT-quinone methide may be involved in the molecular mechanisms of action of this hydroperoxide tumor promoter. PMID:2472232

Taffe, B G; Zweier, J L; Pannell, L K; Kensler, T W

1989-07-01

266

Kit-like 18F-labeling of proteins: synthesis of 4-(di-tert-butyl[18F]fluorosilyl)benzenethiol (Si[18F]FA-SH) labeled rat serum albumin for blood pool imaging with PET.  

PubMed

Radiosyntheses of 18F-radiopharmaceuticals for positron emission tomography (PET) normally require an extraordinarily high effort of technical equipment and specially trained personnel. We recently reported a novel method for the introduction of fluorine-18 into peptides for PET-imaging based on silicon-18F-chemistry (SiFA technique). We herewith introduce the first SiFA-based Kit-like radio-fluorination of a protein (rat serum albumin,RSA) and demonstrate its usefulness for in vivo imaging with microPET in normal rats as well as in a rat heterotropic transplanted heart model. As a labeling agent, we prepared 4-(di-tert-butyl[18F]fluorosilyl)benzenethiol (Si[18F]FASH)by simple isotopic exchange in 40-60% radiochemical yield (RCY) and coupled it directly to a Sulfo-SMCC derivatized RSA in an overall RCY of 12% within 20-30 min. The technically simple labeling procedure does not require any elaborated purification procedures and is a straightforward example of a successful application of Si-18F chemistry for in vivo imaging with PET. PMID:19132825

Wängler, Björn; Quandt, Gabriele; Iovkova, Ljuba; Schirrmacher, Esther; Wängler, Carmen; Boening, Guido; Hacker, Marcus; Schmoeckel, Michael; Jurkschat, Klaus; Bartenstein, Peter; Schirrmacher, Ralf

2009-02-01

267

Enantioselective Synthesis of (2R, 3S)- and (2S, 3R)-4,4,4-trifluoro-N-Fmoc-O-tert-butyl-threonine and their Racemization-free Incorporation into Oligopeptides via Solid-phase Synthesis  

PubMed Central

An efficient method for the enantioselective synthesis of (2R, 3S)- and (2S, 3R)-4,4,4-trifluoro-N-Fmoc-O-tert-butyl-threonine (tfT) on multi-gram scales was developed. Absolute configurations of the two stereoisomers were ascertained by X-ray crystallography. Racemization-free coupling conditions for the incorporation of tfT into oligopeptides were then explored. For solution-phase synthesis, tfT racemization was not an issue under conventional coupling conditions. For solid-phase synthesis, the following conditions were identified to achieve racemization-free synthesis: if tfT (3.0 eq.) was not the first amino acid to be linked to the resin (1.0 eq.), the condition is: 2.7 eq. DIC/3.0 eq. HOBt as the coupling reagent at 0 °C for 20 h; if tfT (3.0 eq.) was the first amino acid to be linked to the resin (1.0 eq.), then 1.0 eq. of CuCl2 needs to be added to the coupling reagent. PMID:17702025

Xiao, Nu; Jiang, Zhong-Xing; Yu, Y. Bruce

2010-01-01

268

FT-IR and Raman vibrational analysis, B3LYP and M06-2X simulations of 4-bromomethyl-6-tert-butyl-2H-chromen-2-one  

NASA Astrophysics Data System (ADS)

In this study, the experimental and theoretical vibrational frequencies of a newly synthesized bacteriostatic and anti-tumor molecule namely, 4-bromomethyl-6-tert-butyl-2H-chromen-2-one have been investigated. The experimental FT-IR (4000-400 cm-1) and Raman spectra (4000-100 cm-1) of the compound in solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters have been calculated using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr and DFT/M06-2X: highly parametrized, empirical exchange correlation function) with 6-311++G(d, p) basis set by Gaussian 03 software, for the first time. The assignments of the vibrational frequencies have been done by potential energy distribution (PED) analysis using VEDA 4 software. The theoretical optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data and results in the literature. In addition, the highest occupied molecular orbital (HOMO) energy, the lowest unoccupied molecular orbital (LUMO) energy and the other related molecular energy values of the compound have been investigated using the same theoretical calculations.

Sert, Yusuf; Puttaraju, K. B.; Keskino?lu, Sema; Shivashankar, K.; Ucun, Fatih

2015-01-01

269

Spectroscopic (FT-IR, FT-Raman), first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 5-tert-Butyl-6-chloro-N-[(4-(trifluoromethyl)phenyl]pyrazine-2-carboxamide.  

PubMed

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-tert-Butyl-6-chloro-N-[(4-(trifluoromethyl)phenyl]pyrazine-2-carboxamide have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of normal modes of vibrations was done using GAR2PED program. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. From the NBO analysis it is evident that the increased electron density at the nitrogen, carbon atoms leads to the elongation of respective bond length and a lowering of the corresponding stretching wave number. The calculated geometrical parameters are in agreement with that of similar derivatives. The calculated first hyperpolarizability is high and the calculated data suggest an extended ?-electron delocalization over the pyrazine ring and carboxamide moiety which is responsible for the nonlinearity of the molecule. PMID:25218229

Bhagyasree, J B; Varghese, Hema Tresa; Panicker, C Yohannan; Van Alsenoy, Christian; Al-Saadi, Abdulaziz A; Dolezal, Martin; Samuel, Jadu

2015-02-25

270

Automated radiosynthesis of N-succinimidyl 3-(di-tert-butyl[(18)F]fluorosilyl)benzoate ([(18)F]SiFB) for peptides and proteins radiolabeling for positron emission tomography.  

PubMed

Recently, silicon fluoride building blocks (SiFA) have emerged as valuable and promising tools to overcome challenges in the labeling of peptides and proteins for positron emission tomography (PET). Herein, we report a fully automated synthesis of N-succinimidyl 3-(di-tert-butyl[(18)F]fluorosilyl)benzoate ([(18)F]SiFB) by a commercially available Scintomics Hot Box 3 synthesis module, to be used as a prosthetic group for peptide and protein labeling. The drying of K2.2.2./K (18)F complex was performed according to the Munich method modified by our group (avoiding azeotropic drying) using oxalic acid to neutralize the base from the (18)F(-) containing QMA eluent. This K2.2.2./K (18)F complex was then used for SiFA (18)F-(19)F isotopic exchange followed by a fast purification by a solid-phase-extraction (SPE) to afford [(18)F]SiFB with an average preparative radiochemical yield (RCY) of 24±1% (non-decay corrected (NDC)) within a synthesis time of 30 min. The [(18)F]SiFB produced by automated synthesis was then used for the (18)F-labeling of rat serum albumin (RSA) as a proof of applicability. PMID:24631747

Koudih, R; Kostikov, A; Kovacevic, M; Jolly, D; Bernard-Gauthier, V; Chin, J; Jurkschat, K; Wängler, C; Wängler, B; Schirrmacher, R

2014-07-01

271

Gymnaster koraiensis and its major components, 3,5-di-O-caffeoylquinic acid and gymnasterkoreayne B, reduce oxidative damage induced by tert-butyl hydroperoxide or acetaminophen in HepG2 cells  

PubMed Central

We investigated the protective effects of Gymnaster koraiensis against oxidative stress-induced hepatic cell damage. We used two different cytotoxicity models, i.e., the administration of tert-butyl hydroperoxide (t-BHP) and acetaminophen, in HepG2 cells to evaluate the protective effects of G. koraiensis. The ethyl acetate (EA) fraction of G. koraiensis and its major compound, 3,5-di-O-caffeoylquinic acid (DCQA), exerted protective effects in the t-BHP-induced liver cytotoxicity model. The EA fraction and DCQA ameliorated t-BHP-induced reductions in GSH levels and exhibited free radical scavenging activity. The EA fraction and DCQA also significantly reduced t-BHP-induced DNA damage in HepG2 cells. Furthermore, the hexane fraction of G. koraiensis and its major compound, gymnasterkoreayne B (GKB), exerted strong hepatoprotection in the acetaminopheninduced cytotoxicity model. CYP 3A4 enzyme activity was strongly inhibited by the extract, hexane fraction, and GKB. The hexane fraction and GKB ameliorated acetaminophen-induced reductions in GSH levels and protected against cell death. [BMB Reports 2013; 46(10): 513-518] PMID:24148773

Jho, Eun Hye; Kang, Kyungsu; Oidovsambuu, Sarangerel; Lee, Eun Ha; Jung, Sang Hoon; Shin, Il-Shik; Nho, Chu Won

2013-01-01

272

Chronic Carcinogenicity Study of Gasoline Vapor Condensate (GVC) and GVC Containing Methyl Tertiary-Butyl Ether in F344 Rats  

PubMed Central

Chronic inhalation studies were conducted to compare the toxicity and potential carcinogenicity of evaporative emissions from unleaded gasoline (GVC) and gasoline containing the oxygenate methyl tertiary-butyl ether (MTBE; GMVC). The test materials were manufactured to mimic vapors people would be exposed to during refueling at gas stations. Fifty F344 rats per gender per exposure level per test article were exposed 6 h/d, 5 d/wk for 104 wk in whole body chambers. Target total vapor concentrations were 0, 2, 10, or 20 g/m3 for the control, low-, mid-, and high-level exposures, respectively. Endpoints included survival, body weights, clinical observations, organs weights, and histopathology. GVC and GMVC exerted no marked effects on survival or clinical observations and few effects on organ weights. Terminal body weights were reduced in all mid- and high-level GVC groups and high-level GMVC groups. The major proliferative lesions attributable to gasoline exposure with or without MTBE were renal tubule adenomas and carcinomas in male rats. GMV exposure led to elevated testicular mesothelioma incidence and an increased trend for thyroid carcinomas in males. GVMC inhalation caused an increased trend for testicular tumors with exposure concentration. Mid- and high-level exposures of GVC and GMVC led to elevated incidences of nasal respiratory epithelial degeneration. Overall, in these chronic studies conducted under identical conditions, the health effects in F344 rats following 2 yr of GVC or GMVC exposure were comparable in the production of renal adenomas and carcinomas in male rats and similar in other endpoints. PMID:21432714

Benson, Janet M.; Gigliotti, Andrew P.; March, Thomas H.; Barr, Edward B.; Tibbetts, Brad M.; Skipper, Betty J.; Clark, Charles R.; Twerdok, Lorraine

2011-01-01

273

tert-Butyl N-[(3R,4R)-1-(2-cyano­acet­yl)-4-methyl­piperidin-3-yl]-N-methyl­carbamate  

PubMed Central

The piperidine ring of the title compound, C15H25N3O3, adopts a slightly distorted chair conformation with the cis substituents displaying an N—C—C—C torsion angle of 43.0?(3)°. The cyano group (plane defined by C—C—C N atoms) is bent slightly out of the plane of the amide group by 13.3?(2)°. The carbamate group is oriented at a dihedral angle of 60.3?(5)° relative to the amide group. PMID:23795101

Gehringer, Matthias; Forster, Michael; Schollmeyer, Dieter; Laufer, Stefan

2013-01-01

274

Solid state {sup 1}H spin-lattice relaxation and isolated-molecule and cluster electronic structure calculations in organic molecular solids: The relationship between structure and methyl group and t-butyl group rotation  

SciTech Connect

We report ab initio density functional theory electronic structure calculations of rotational barriers for t-butyl groups and their constituent methyl groups both in the isolated molecules and in central molecules in clusters built from the X-ray structure in four t-butyl aromatic compounds. The X-ray structures have been reported previously. We also report and interpret the temperature dependence of the solid state {sup 1}H nuclear magnetic resonance spin-lattice relaxation rate at 8.50, 22.5, and 53.0 MHz in one of the four compounds. Such experiments for the other three have been reported previously. We compare the computed barriers for methyl group and t-butyl group rotation in a central target molecule in the cluster with the activation energies determined from fitting the {sup 1}H NMR spin-lattice relaxation data. We formulate a dynamical model for the superposition of t-butyl group rotation and the rotation of the t-butyl group's constituent methyl groups. The four compounds are 2,7-di-t-butylpyrene, 1,4-di-t-butylbenzene, 2,6-di-t-butylnaphthalene, and 3-t-butylchrysene. We comment on the unusual ground state orientation of the t-butyl groups in the crystal of the pyrene and we comment on the unusually high rotational barrier of these t-butyl groups.

Wang, Xianlong, E-mail: WangXianlong@uestc.edu.cn, E-mail: pbeckman@brynmawr.edu [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China)] [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China); Mallory, Frank B. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States)] [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Mallory, Clelia W. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States) [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Odhner, Hosanna R.; Beckmann, Peter A., E-mail: WangXianlong@uestc.edu.cn, E-mail: pbeckman@brynmawr.edu [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States)

2014-05-21

275

DIPPR Project 871 For 1995 - Thermodynamic Properties and Ideal-Gas Enthalpies of Formation for Methyl Benzoate, Ethyl Benzoate, (R)-(+)-Limonene, Tert-Amyl Methyl Ether, Trans-Crotonaldehyde, and  

SciTech Connect

Ideal-gas enthalpies of formation of methyl benzoate, ethyl benzoate, (R)-(+)-limonene, tert-amyl methyl ether, trans-crotonaldehyde, and diethylene glycol are reported. The standard energy of combustion and hence standard enthalpy of formation of each compound in the liquid phase has been measured using an oxygen rotating-bomb calorimeter without rotation. Vapor pressures were measured to a pressure limit of 270 kPa or the lower decomposition point for each of the six compounds using a twin ebulliometric apparatus. Liquid-phase densities along the saturation line were measured for each compound over a range of temperature (ambient to a maximum of 548 K). A differential scanning calorimeter was used to measure two-phase (liquid + vapor) heat capacities for each compound in the temperature region ambient to the critical temperature or lower decomposition point. For methyl benzoate and tert-amyl methyl ether, 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 each of the remaining compounds. The results of the measurements were combined to derive a series of thermophysical properties including critical temperature, critical density, critical pressure, acentric factor, enthalpies of vaporization (restricted to within {+-}50 K of the temperature region of the experimentally determined vapor pressures), and heat capacities along the saturation line. Wagner-type vapor-pressure equations were derived for each compound. All measured and derived values were compared with those obtained in a search of the literature. Recommended critical parameters are listed for each of the compounds studied. Group-additivity parameters, useful in the application of the Benson gas-phase group-contribution correlations, were derived.

Steele, W.V.

2002-07-01

276

Access to “Friedel-Crafts-restricted” tert-alkyl aromatics by activation/methylation of tertiary benzylic alcohols  

PubMed Central

Herein we describe a two-step protocol to prepare m-tert-alkylbenzenes. The appropriate 3° benzylic alcohols are activated with SOCl2 or concentrated HCl, and then treated with trimethylaluminum, affording the desired products in 68–97% yields (22 examples). This reaction sequence is successful in the presence of a variety of functional groups, including acid-sensitive and Lewis-basic groups. In addition to t-Bu groups, 1,1-dimethylpropyl and 1-ethyl-1-methylpropyl groups can also be installed using this method. PMID:22394317

Hartsel, Joshua A.; Craft, Derek T.; Chen, Qiao-Hong; Ma, Ming

2012-01-01

277

Access to "Friedel-Crafts-restricted" tert-alkyl aromatics by activation/methylation of tertiary benzylic alcohols.  

PubMed

Herein we describe a two-step protocol to prepare m-tert-alkylbenzenes. The appropriate tertiary benzylic alcohols are activated with SOCl(2) or concentrated HCl and then treated with trimethylaluminum, affording the desired products in 68-97% yields (22 examples). This reaction sequence is successful in the presence of a variety of functional groups, including acid-sensitive and Lewis-basic groups. In addition to t-Bu groups, 1,1-dimethylpropyl and 1-ethyl-1-methylpropyl groups can also be installed using this method. PMID:22394317

Hartsel, Joshua A; Craft, Derek T; Chen, Qiao-Hong; Ma, Ming; Carlier, Paul R

2012-04-01

278

Concentration fluctuations and collective properties in mixed liquid systems: Rayleigh-Brillouin spectra of tert-butyl alcohol/ 2,2'-dimethylbutane liquid mixture  

NASA Astrophysics Data System (ADS)

Rayleigh-Brillouin spectra have been measured in a range of temperatures and compositions of t-butyl alcohol/2,2'-dimethylbutane liquid mixture. The mixture mole fraction has been varied from pure alkane (xTBA=0) to pure alcohol (xTBA=1) at temperatures between 283 and 323K. In the same composition and temperature ranges the authors also executed measurements of mass density, shear viscosity, and refractive index. From light scattering spectra the authors have extracted the hypersound velocities and adiabatic compressibilities and evaluated their excess values. Moreover, the authors attempted to evaluate the isothermal (40°C) Landau-Placzek ratios at various mole fractions, but these values proved to be subject to significant errors due to great uncertainty in the central component intensity measurements. Thus, in discussing the results, this latter quantity was considered only from a qualitative point of view. These results highlight a nonideal behavior of the studied liquid mixture with a probable azeotropic composition around xTBA=0.7 due to formation of small clusters of hydrogen-bonded alcohol tetramers that are completely surrounded by solvent molecules and analogous or smaller clusters. These clusters, shaped as inverse micelles, offer their hydrophobic moiety towards the molecules that constitute the solvation shell, resulting in a low polarity solution structure that minimizes the solute-solvent interactions. Differences in thermal and compositional behavior of excess molar volumes and adiabatic compressibilities have been interpreted by attributing different weights to the solute-solvent interaction forces and to the hydrogen bond connectivity effects.

Cataliotti, Rosario Sergio; Palombo, Francesca; Paolantoni, Marco; Sassi, Poala; Raudino, Antonio

2007-01-01

279

Enhanced enantioselectivity of lipase from Pseudomonas sp. at high temperatures and fixed water activity in the ionic liquid, 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide  

Microsoft Academic Search

The water activity equilibration over saturated salt solutions was monitored in the ionic liquid 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide and in two organic solvents (methyl tert-butylether and n-hexane). Water uptake by the ionic liquid was comparable to that in polar organic solvents. Furthermore, the kinetic resolution of (R,S)-1-phenylethanol catalysed by a lipase from Pseudomonas sp. had a higher selectivity in the ionic liquid

Marrit Eckstein; Peter Wasserscheid; Udo Kragl

2002-01-01

280

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods.  

PubMed

This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined. PMID:24813291

Saravanan, S; Balachandran, V

2014-09-15

281

Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods  

NASA Astrophysics Data System (ADS)

This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm-1 and 3500-100 cm-1, respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (?0) and related properties (?, ?0 and ??) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined.

Saravanan, S.; Balachandran, V.

2014-09-01

282

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

SciTech Connect

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

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

1991-05-01

283

tert-Butyl 4-{[2-amino-4-(2-hy-droxy-phen-yl)pyrimidin-5-yl]meth-yl}piperazine-1-carboxyl-ate.  

PubMed

In the title compound, C20H27N5O3, the central piperazine ring adopts a chair conformation, with the N-bound carboxyl-ate and methyl-ene substituents occupying bis-ectional and equatorial orientations, respectively. A twist is evident between the aromatic rings [dihedral angle = 25.61?(9)°] but an intra-molecular O-H?N hydrogen bond persists between these. Supra-molecular tapes along [1-10] are formed in the crystal packing through N(amino)-H?O(hydrox-yl) and N(amino)-H?N(pyrimidin-yl) hydrogen bonds, and these are linked into layers in the ab plane by ?-? inter-actions [inter-centroid distance between pyrimidinyl rings = 3.5919?(9)?Å]. PMID:24098254

Gajera, Nilesh N; Patel, Mukesh C; Jotani, Mukesh M; Tiekink, Edward R T

2013-01-01

284

tert-Butyl 4-{[2-amino-4-(2-hy­droxy­phen­yl)pyrimidin-5-yl]meth­yl}piperazine-1-carboxyl­ate  

PubMed Central

In the title compound, C20H27N5O3, the central piperazine ring adopts a chair conformation, with the N-bound carboxyl­ate and methyl­ene substituents occupying bis­ectional and equatorial orientations, respectively. A twist is evident between the aromatic rings [dihedral angle = 25.61?(9)°] but an intra­molecular O—H?N hydrogen bond persists between these. Supra­molecular tapes along [1-10] are formed in the crystal packing through N(amino)—H?O(hydrox­yl) and N(amino)—H?N(pyrimidin­yl) hydrogen bonds, and these are linked into layers in the ab plane by ?–? inter­actions [inter-centroid distance between pyrimidinyl rings = 3.5919?(9)?Å]. PMID:24098254

Gajera, Nilesh N.; Patel, Mukesh C.; Jotani, Mukesh M.; Tiekink, Edward R. T.

2013-01-01

285

Oxalic acid supported Si-18F-radiofluorination: one-step radiosynthesis of N-succinimidyl 3-(di-tert-butyl[18F]fluorosilyl)benzoate ([18F]SiFB) for protein labeling.  

PubMed

N-Succinimidyl 3-(di-tert-butyl[(18)F]fluorosilyl)benzoate ([(18)F]SiFB), a novel synthon for one-step labeling of proteins, was synthesized via a simple (18)F-(19)F isotopic exchange. A new labeling technique that circumvents the cleavage of the highly reactive active ester moiety under regular basic (18)F-labeling conditions was established. In order to synthesize high radioactivity amounts of [(18)F]SiFB, it was crucial to partially neutralize the potassium oxalate/hydroxide that was used to elute (18)F(-) from the QMA cartridge with oxalic acid to prevent decomposition of the active ester moiety. Purification of [(18)F]SiFB was performed by simple solid-phase extraction, which avoided time-consuming HPLC and yielded high specific activities of at least 525 Ci/mmol and radiochemical yields of 40-56%. In addition to conventional azeotropic drying of (18)F(-) in the presence of [K(+)?2.2.2.]C(2)O(4), a strong anion-exchange (SAX) cartridge was used to prepare anhydrous (18)F(-) for nucleophilic radio-fluorination omitting the vacuum assisted drying of (18)F(-). Using a lyophilized mixture of [K(+)?2.2.2.]OH resolubilized in acetonitrile, the (18)F(-) was eluted from the SAX cartridge and used directly for the [(18)F]SiFB synthesis. [(18)F]SiFB was applied to the labeling of various proteins in likeness to the most commonly used labeling synthon in protein labeling, N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB). Rat serum albumin (RSA), apo-transferrin, a ?-cell-specific single chain antibody, and erythropoietin were successfully labeled with [(18)F]SiFB in good radiochemical yields between 19% and 36%. [(18)F]SiFB- and [(18)F]SFB-derivatized RSA were directly compared as blood pool imaging agents in healthy rats using small animal positron emission tomography. Both compounds demonstrated identical biodistributions in healthy rats, accurately visualizing the blood pool with PET. PMID:22148255

Kostikov, Alexey P; Chin, Joshua; Orchowski, Katy; Niedermoser, Sabrina; Kovacevic, Miriam M; Aliaga, Antonio; Jurkschat, Klaus; Wängler, Bjoern; Wängler, Carmen; Wester, Hans-Jürgen; Schirrmacher, Ralf

2012-01-18

286

Fate of 3-tert-Butyl-4-hydroxyanisole, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8- hexamethylcyclopenta(g)-2-benzopyrane and chlorpyrifos in a Conventional Wastewater Treatement Plant  

NASA Astrophysics Data System (ADS)

Emerging contaminants (ECs) are a major concern in the environment, particularly those found in waters. Wastewater treatment plants (WWTPs) play a key role in reducing the concentrations in the environment because compounds may be transformed under either aerobic or anaerobic conditions or may sorb to wastewater sludges and therefore be removed from waters. If these ECs are not contained or treated then effluent discharged from the WWTP and to a receiving stream may contain hazardous levels of these contaminants. Reported here is a study of the fate of three emerging contaminants (ECs): 3-tert-Butyl-4-hydroxyanisole (BHA), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyrane (HHCB) and chlorpyrifos. Experiments were conducted on a laboratory scale by emulating conditions of a conventional WWTP in San Antonio, TX. The goal of the research was to determine general characteristics for both sorption (to wastewater sludges) and degradation. The sorption experiments were performed by exposing the sludge to a variety of initial concentration of ECs for 24 hours. After exposure these three ECs were extracted and analyzed using gas chromatography followed by flame ionization detector (GC/FID). Sorption experiments indicated that HHCB and chlorpyrifos are more hydrophobic than BHA and, therefore, would be mostly contained in the sludges. The degradation rates for these ECs were also considered for both aerobic and anaerobic conditions using different bench-scale reactor setups for 21 days. The differences between the reactor setups included volume of reactor, amount of sludge, mode of supply of nutrients and acclimatization of sludge to the ECs. One sludge was first acclimated to EC concentrations and then used in the experiment. The acclimated reactor had reaction rate constants approximately double that of the non-acclimated sludge reactor setups and followed first order reaction kinetics. Aerobic degradation occurred more readily for all three compounds than anaerobic degradation. These experiments supported the hypothesis that the WWTPs do capture and transform most of these compounds and, therefore, limit their reach to the effluent. However it cannot be supported that the compounds in the sludge phase are degraded to very low concentrations. Because of the changing dynamics of the sludge phase with time, further work needs to be conducted on the influence of time on sorption coefficients and, subsequently the effect of these temporal changes on degradation of these compounds.

Thomas, S. M.; Bodour, A.; Inniss, E. C.; Murray, K. E.

2007-12-01

287

Cometabolism of Methyl tertiary Butyl Ether and Gaseous n-Alkanes by Pseudomonas mendocina KR-1 Grown on C5 to C8 n-Alkanes  

PubMed Central

Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1° alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2° alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 ?mol) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1° alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 ± 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 ?M) and n-butane (Ki = 16 ?M) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism. PMID:14660389

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

2003-01-01

288

Cometabolism of methyl tertiary butyl ether and gaseous n-alkanes by Pseudomonas mendocina KR-1 grown on C5 to C8 n-alkanes.  

PubMed

Pseudomonas mendocina KR-1 grew well on toluene, n-alkanes (C5 to C8), and 1 degrees alcohols (C2 to C8) but not on other aromatics, gaseous n-alkanes (C1 to C4), isoalkanes (C4 to C6), 2 degrees alcohols (C3 to C8), methyl tertiary butyl ether (MTBE), or tertiary butyl alcohol (TBA). Cells grown under carbon-limited conditions on n-alkanes in the presence of MTBE (42 micromoles) oxidized up to 94% of the added MTBE to TBA. Less than 3% of the added MTBE was oxidized to TBA when cells were grown on either 1 degrees alcohols, toluene, or dextrose in the presence of MTBE. Concentrated n-pentane-grown cells oxidized MTBE to TBA without a lag phase and without generating tertiary butyl formate (TBF) as an intermediate. Neither TBF nor TBA was consumed by n-pentane-grown cells, while formaldehyde, the expected C1 product of MTBE dealkylation, was rapidly consumed. Similar Ks values for MTBE were observed for cells grown on C5 to C8 n-alkanes (12.95 +/- 2.04 mM), suggesting that the same enzyme oxidizes MTBE in cells grown on each n-alkane. All growth-supporting n-alkanes (C5 to C8) inhibited MTBE oxidation by resting n-pentane-grown cells. Propane (Ki = 53 micromoles) and n-butane (Ki = 16 micromoles) also inhibited MTBE oxidation, and both gases were also consumed by cells during growth on n-pentane. Cultures grown on C5 to C8 n-alkanes also exhibited up to twofold-higher levels of growth in the presence of propane or n-butane, whereas no growth stimulation was observed with methane, ethane, MTBE, TBA, or formaldehyde. The results are discussed in terms of their impacts on our understanding of MTBE biodegradation and cometabolism. PMID:14660389

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

2003-12-01

289

Identification of 1-butyl-3-(1-(4-methyl)naphtoyl)indole detected for the first time in "herbal high" products on the Italian market.  

PubMed

The results of the analysis of some herbal products and powders adulterated with alkylindoles recovered on the Italian market between 2010 and 2011 are reported. Besides the well-known alkyindoles JWH-018 and JWH-073, other derivatives such as JWH-250 and AM-694 have been detected and for the first time in Italy 1-butyl-3-(1-(4-methyl)naphthoyl)indole (compound 1), the 4-methylnaphthoyl analogue of JWH-073. This compound as well as the other alkylindoles has been synthesized and characterized by (1)H NMR, (13)C NMR, DSC, GC/MS, and elemental analysis. The quantitative analyses of the samples have been carried out by means of the GC/FID method developed in our laboratory for the analysis of herbal high products containing naphthoylindoles; the quantity of the cannabimimetic substances ranged from 6 mg/g to 47 mg/g. PMID:22939184

Valoti, Ermanno; Casagni, Eleonora; Dell'Acqua, Lucia; Pallavicini, Marco; Roda, Gabriella; Rusconi, Chiara; Straniero, Valentina; Gambaro, Veniero

2012-11-30

290

Effects of 2- and 3tertButyl4-hydroxyanisole on Glutathione S-Transferase and Epoxide Hydrolase Activities and Sulfhydryl Levels in Liver and Forestomach of Mice1  

Microsoft Academic Search

Butylated hydroxyanisole,a food additive, has beenfound to inhibit the neoplastia effects of a wide variety of chemical carcinogens. The commercially available preparations of bu- tylated hydroxyanisole contain two isomers, 2-ferf-butyl-4-hy- droxyanisole (2-BHA) and 3-ferf-butyl-4-hydroxyanisole (3- BHA). Both isomers induce increased activities of glutathione (GSH)S-transferaseand epoxide hydrolaseand increaseacid- soluble sulfhydryl concentration in hepatic and forestomach tissues of A\\/HeJ mice. The inductions

Luke K. T. Lam; Velta L. Sparnins; J. Bradley Hochalter; Lee W. Wattenberg

291

EFFECT OF METHYL TERT-BUTYL ETHER ON THE BIOCONCENTRATION AND PHOTOINDUCED TOXICITY OF FLUORANTHENE IN FATHEAD MINNOW LARVAE (PIMEPHALES PROMELAS). (R823873)  

EPA Science Inventory

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

292

SIMULATION OF A METHYL TERT-BUTYL ETHER (MTBE) PLUME WITH MODFLOW, MT3D AND THE HYDROCARBON SPILL SCREENING MODEL (HSSM)  

EPA Science Inventory

An MTBE plume in the Upper Glacial Aquifer of Long Island, NY was simulated by combining MODFLOW and MT3D with a semi-analytical model for a gasoline release. The first step was to develop and calibrate a 3-dimensional steady-state numerical ground water flow model of the aquife...

293

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

USGS Publications Warehouse

The mathematical model, R-UNSAT, developed to simulate the transport of benzene and MTBE in representative sand and clay hydrogeologic systems was evaluated. The effects on groundwater were simulated for small, chronic-, and single-volume releases of gasoline trapped in unsaturated soil. Hydrocarbon biodegradation was simulated by using a dual Monod-type kinetics model that includes oxygen and the reactive constituents. MTBE was assumed to be non-reactive. For MTBE, infiltration had the greatest effect on transport to groundwater. Infiltration also affected mass losses of MTBE to the atmosphere, particularly, in fine-grained soils. Depth to groundwater and soil type primarily affected travel times of MTBE to groundwater, but could affect mass-loading rates to groundwater if infiltration is insignificant. For benzene, transport to groundwater was significant only if the depth to the water table was < 1 m or biodegradation was assumed to be negligible. Mass fluxed to groundwater were generally smaller for benzene than for MTBE by more than two orders of magnitude. Thus, water that recharges an aquifer beneath a spill can be enriched in MTBE relative to benzene when compared to the composition of water in equilibrium with gasoline.

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

1999-01-01

294

Synthesis and X-ray structural characterization of a series of dimeric [Hg2(SePh)2X2(PR2R?)2] compounds (R = tert-butyl; R? = 4-N,N-dimethylaniline and X = Cl, Br, I, SCN, SePh)  

NASA Astrophysics Data System (ADS)

This article presents the syntheses and characterization of five new compounds with the general formula [Hg2(SePh)2X2(PR2R?)2] (R = tert-butyl; R? = 4-N,N-dimethylaniline), where X = Cl (1a), Br (1b), I (1c), SCN (2), SePh (3). The compounds crystallized as dimeric {HgSe} units, although most of these chalcogenolate compounds appeared to be polymeric adamantanoid or fused adamantanoid species. The ligand structures of these compounds limited the growth of the molecular structures and promoted the formation of the dimeric form alone. The mercury centers were connected to one another through one ?-Cl and one ?-SePh bridge in 1a, and through two ?-SePh bridges in 1b, 1c, 2, and 3. The compounds were characterized by single crystal X-ray diffractometry, TGA, elemental analysis, and infrared spectroscopy.

Stieler, Rafael; Faoro, Eliandro; Cechin, Camila Nunes; Floriano, Luana; Lang, Ernesto Schulz

2015-01-01

295

The influence of the R group in the thermal stability of Sn{sub 4}R{sub 4}O{sub 6} (R = methyl, n-butyl or phenyl)  

SciTech Connect

Pyrolysis experiments were carried out with Sn{sub 4}R{sub 4}O{sub 6} (R=methyl (1), butyl (2) and phenyl (3)). The thermal behaviour of the organotin oxides was studied by Thermogravimetric Analysis (TG) with simultaneous Differential Thermal Analysis (DTA) and the residues obtained after decomposition were characterised by X-ray electron probe microanalysis (EPMA), Scanning Electron Microscopy (SEM), X-ray diffraction and {sup 119}Sn Moessbauer spectroscopy. The results have shown that the methyl derivative is the best precursor, producing nanoparticles of pure phase rutile-type tetragonal SnO{sub 2} in O{sub 2} with a yield up to 90%.

Pereira, A.G.; Batalha, L.A.R.; Porto, A.O.; Lima, G.M. de; Silva, G.G.; Ardisson, J.D.; Siebald, H.G.L

2003-11-26

296

Effect of ethylene glycol and its derivatives on the aggregation behavior of an ionic liquid 1-butyl-3-methyl imidazolium octylsulfate in aqueous medium.  

PubMed

The effect of ethylene glycol (EG) and its derivatives, ethylene glycol monomethyl ether (EGMME), or ethylene glycol dimethyl ether (EGDME), on the aggregation behavior of a surfactant-like ionic liquid (IL), 1-butyl-3-methyl imidazolium octylsulfate, [C(4)mim][C(8)OSO(3)], in aqueous solutions is investigated using conductivity, surface tension, fluorescence, (1)H NMR, and dynamic light scattering (DLS) measurements. Thermodynamic parameters such as Gibbs free energy (?G(m)°), standard enthalpy (?H(m)°), and standard entropy (?S(m)°) of aggregation are determined from the temperature dependence of conductivity. The interfacial properties of IL at the air/water interface in various mixed solvents are evaluated from surface tension measurements. Information about the local microenvironment and size of the aggregates is obtained from steady-state fluorescence using pyrene as a polarity probe and DLS measurements, respectively. (1)H NMR data has been employed to get detailed insight into the effect of organic additives on the IL aggregate structure and aggregation number. It has been observed that the addition of organic additives to water decreases the spontaneity of aggregation of IL. PMID:22239544

Singh, Tejwant; Rao, K Srinivasa; Kumar, Arvind

2012-02-01

297

Comparative analysis of skin sensitization potency of acrylates (methyl acrylate, ethyl acrylate, butyl acrylate, and ethylhexyl acrylate) using the local lymph node assay.  

PubMed

There are currently available no systematic experimental data on the skin sensitizing properties of acrylates that are of relevance in occupational settings. Limited information from previous guinea-pig tests or from the local lymph node assay (LLNA) is available; however, these data are incomplete and somewhat contradictory. For those reasons, we have examined in the LLNA 4 acrylates: butyl acrylate (BA), ethyl acrylate (EA), methyl acrylate (MA), and ethylhexyl acrylate (EHA). The LLNA data indicated that all 4 compounds have some potential to cause skin sensitization. In addition, the relative potencies of these acrylates were measured by derivation from LLNA dose-response analyses of EC3 values (the effective concentration of chemical required to induce a threefold increase in proliferation of draining lymph node cells compared with control values). On the basis of 1 scheme for the categorization of skin sensitization potency, BA, EA, and MA were each classified as weak sensitizers. Using the same scheme, EHA was considered a moderate sensitizer. However, it must be emphasized that the EC3 value for this chemical of 9.7% is on the borderline between moderate (<10%) and weak (>10%) categories. Thus, the judicious view is that all 4 chemicals possess relatively weak skin sensitizing potential. PMID:17868217

Dearman, Rebecca J; Betts, Catherine J; Farr, Craig; McLaughlin, James; Berdasco, Nancy; Wiench, Karin; Kimber, Ian

2007-10-01

298

Discovery, synthesis, and structure-based optimization of a series of N-(tert-butyl)-2-(N-arylamido)-2-(pyridin-3-yl) acetamides (ML188) as potent non-covalent small molecule inhibitors of the severe acute respiratory syndrome coronavirus (SARS-CoV) 3CL protease  

PubMed Central

A high-throughput screen of the NIH molecular libraries sample collection and subsequent optimization of a lead dipeptide-like series of severe acute respiratory syndrome (SARS) main protease (3CLpro) inhibitors led to the identification of probe compound ML188 (16-(R), (R)-N-(4-(tert-butyl)phenyl)-N-(2-(tert-butylamino)-2-oxo-1-(pyridin-3-yl)ethyl)furan-2-carboxamide, Pubchem CID: 46897844). Unlike the majority of reported coronavirus 3CLpro inhibitors that act via covalent modification of the enzyme, 16-(R) is a non-covalent SARS-CoV 3CLpro inhibitor with moderate MW and good enzyme and antiviral inhibitory activity. A multi-component Ugi reaction was utilized to rapidly explore structure activity relationships within S1?, S1, and S2 enzyme binding pockets. The X-ray structure of SARS-CoV 3CLpro bound with 16-(R) was instrumental in guiding subsequent rounds of chemistry optimization. 16-(R) provides an excellent starting point for the further design and refinement of 3CLpro inhibitors that act by a non-covalent mechanism of action. PMID:23231439

Jacobs, Jon; Tokars, Valerie; Zhou, Ya; Turlington, Mark; Saldanha, S. Adrian; Chase, Peter; Eggler, Aimee; Dawson, Eric S.; Baez-Santos, Yahira M.; Tomar, Sakshi; Mielech, Anna M.; Baker, Susan C.; Lindsley, Craig W.; Hodder, Peter; Mesecar, Andrew; Stauffer, Shaun R.

2013-01-01

299

Comparative study of the hydrolytic metabolism of methyl-, ethyl-, propyl-, butyl-, heptyl- and dodecylparaben by microsomes of various rat and human tissues.  

PubMed

Hydrolytic metabolism of methyl-, ethyl-, propyl-, butyl-, heptyl- and dodecylparaben by various tissue microsomes and plasma of rats, as well as human liver and small-intestinal microsomes, was investigated and the structure-metabolic activity relationship was examined. Rat liver microsomes showed the highest activity toward parabens, followed by small-intestinal and lung microsomes. Butylparaben was most effectively hydrolyzed by the liver microsomes, which showed relatively low hydrolytic activity towards parabens with shorter and longer alkyl side chains. In contrast, small-intestinal microsomes exhibited relatively higher activity toward longer-side-chain parabens, and showed the highest activity towards heptylparaben. Rat lung and skin microsomes showed liver-type substrate specificity. Kidney and pancreas microsomes and plasma of rats showed small-intestinal-type substrate specificity. Liver and small-intestinal microsomal hydrolase activity was completely inhibited by bis(4-nitrophenyl)phosphate, and could be extracted with Triton X-100. Ces1e and Ces1d isoforms were identified as carboxylesterase isozymes catalyzing paraben hydrolysis by anion exchange column chromatography of Triton X-100 extract from liver microsomes. Ces1e and Ces1d expressed in COS cells exhibited significant hydrolase activities with the same substrate specificity pattern as that of liver microsomes. Small-intestinal carboxylesterase isozymes Ces2a and Ces2c expressed in COS cells showed the same substrate specificity as small-intestinal microsomes, being more active toward longer-alkyl-side-chain parabens. Human liver microsomes showed the highest hydrolytic activity toward methylparaben, while human small-intestinal microsomes showed a broadly similar substrate specificity to rat small-intestinal microsomes. Human CES1 and CES2 isozymes showed the same substrate specificity patterns as human liver and small-intestinal microsomes, respectively. PMID:23742084

Ozaki, Hitomi; Sugihara, Kazumi; Watanabe, Yoko; Fujino, Chieri; Uramaru, Naoto; Sone, Tomomichi; Ohta, Shigeru; Kitamura, Shigeyuki

2013-12-01

300

40 CFR Table 4 to Subpart F of... - Organic Hazardous Air Pollutants Subject to Cooling Tower Monitoring Requirements in § 63.104  

Code of Federal Regulations, 2010 CFR

... 78591 Methanol 67561 Methyl bromide (Bromomethane) 74839 Methyl chloride (Chloromethane) 74873 Methyl hydrazine 60344 Methyl isobutyl ketone (Hexone) 108101 Methyl methacrylate 80626 Methyl tert-butyl ether...

2010-07-01

301

Molecular restructuring at poly(n-butyl methacrylate) and poly(methyl methacrylate) surfaces due to compression by a sapphire prism studied by infrared-visible sum frequency generation vibrational spectroscopy.  

PubMed

Infrared-visible sum frequency generation (SFG) vibrational spectroscopy, performed in visible wavelength total internal reflection (TIR) geometry, was used to determine the molecular structures of poly(n-butyl methacrylate) (PBMA) and poly(methyl methacrylate) (PMMA) surfaces in air and in contact with a smooth sapphire surface with and without the application of pressure. C-H vibrational resonances were probed optically to nondestructively examine the buried polymer/sapphire interfaces and obtain information about the molecular orientation in situ. These findings are contrasted with those of the same polymers cast from a toluene solution directly on the sapphire prism surface and annealed. Compared to polymer surface conformation in air, the SFG spectra of the deformed (compressed) PBMA at the sapphire interface illustrate that the ester butyl side chain restructures and tilts away from the surface normal. However, the molecular conformation in the similarly deformed PMMA at the sapphire interface is identical to that obtained in air, which is dominated by the upright-oriented ester methyl side chains. For PBMA and PMMA spin cast on sapphire and annealed, the surface structure of the undeformed PBMA at the sapphire interface is identical to that of the deformed PBMA at the sapphire interface, while the PMMA conformation is different and shows alpha-methyl group ordering. Since the glass transition temperature of PBMA is below room temperature, the rubbery state of PBMA demonstrates a melt-like behavior, evidenced by the fact that PBMA is in conformation chemical equilibrium at the sapphire surface even under compression. Due to the high glass transition temperature of PMMA, compression freezes PMMA in a metastable state, revealed by the restructured molecular conformation when annealed against the sapphire surface. The results of this study demonstrate that structural changes at buried polymer surfaces due to the application of contact pressure can be detected in situ by TIR-SFG vibrational spectroscopy. PMID:15807615

Kweskin, S J; Komvopoulos, K; Somorjai, G A

2005-04-12

302

Differential effect of methyl-, butyl- and propylparaben and 17?-estradiol on selected cell cycle and apoptosis gene and protein expression in MCF-7 breast cancer cells and MCF-10A non-malignant cells.  

PubMed

Parabens are alkyl esters of p-hydroxybenzoic acid used widely as antimicrobial preservatives in consumer products, including pharmaceuticals, foods and cosmetics. We showed previously that methyl-, butyl- and propylparaben parabens, even at low doses, stimulate the proliferation of MCF-7 breast cancer cells and non-transformed MCF-10A breast epithelial cells. The present study was undertaken to determine whether this represents a direct effect on cell cycle and apoptotic gene expression. MCF-7 and MCF-10A cells were exposed to methyl, butyl- and propylparaben (20?nm) or 17?-estradiol (10?nm). Cell cycle and apoptotic gene expression were evaluated by real-time polymerase chain reaction and protein expression by Western blot. 17?-estradiol upregulated G1 /S phase genes and downregulated cell cycle progression inhibitors in both MCF-7 and MCF-10A. Upregulation of Bcl-xL and downregulation of caspase 9 was observed in MCF-7, while upregulation of Bcl-xL, BCL2L2 and caspase 9 was noted in MCF-10A. Cyclins in MCF-7 cells were not affected by any of the parabens. Methyl- and butylparaben had no effect on the expression of selected apoptotic genes in MCF-7. In MCF-10A, all parabens tested increased the expression of G1 /S phase genes, and downregulated cell cycle inhibitors. Methylparaben increased pro-survival gene. Butylparaben increased BCL2L1 gene, as did 17?-estradiol, while propylparaben upregulated both the extrinsic and intrinsic apoptotic pathways. There are differences in cell cycle and apoptosis gene expression between parabens and 17?-estradiol in MCF-7 cells. In MCF-10A cells, most of the genes activated by parabens were comparable to those activated by 17?-estradiol. PMID:24481588

Wróbel, Anna Maria; Gregoraszczuk, Ewa ?ucja

2014-09-01

303

Structure and spectral properties of a squarylium dye, 2,4-bis((1-n-butyl-2(1H)-quinolylidene)methyl)-1,3-cyclobutadienediylium-1,3-diolate  

SciTech Connect

Structural and spectral characterizations of the title compound, 2,4-bis((1-n-butyl-2(1H)-quinolylidene)methyl)-1,3-cyclobutadienediylium-1,3-diolate (BQMS), a prime candidate for a solar energy material, have been carried out. Crystals are monoclinic, P2/sub 1//n with a = 9.586 (2) A, b = 9.730 (2) A, c = 13.894 (3) A, ..beta.. = 99.77 (9)/sup 0/, and Z = 2. The structure has been solved by direct methods and refined by using 1078 reflections for which F > 2 sigma (F) with anisotropic temperature factors on the non-hydrogen atoms to R = 0.098 and R/sub w/ = 0.074. Quasi-metallic reflection is observed along both principal directions for the (101) and (001) faces. The transition moment is found to be polarized along the long axis of the molecule. 16 references, 5 figures, 1 table.

Bernstein, J.; Tristani-Kendra, M.; Eckhardt, C.J.

1986-03-13

304

3-(4-Bromo­phen­yl)-1-butyl-5-[1-(2-chloro-6-methyl­phen­yl)-1H-tetra­zol-5-yl]imidazolidine-2,4-dione  

PubMed Central

In the title mol­ecule, C21H20BrClN6O2, the chloro-substituted benzene ring forms a dihedral angle of 77.84?(7)° with the tetra­zole ring and the bromo-substituted ring forms a dihedral angle of 43.95?(6)° with the imidazole ring. The dihedral angle between the tetra­zole and imidazole rings is 67.42?(8)°. The terminal methyl group of the butyl substituent is disordered over two sets of sites, with refined occupancies 0.67?(3) and 0.33?(3). In the crystal, there is a short Br?N contact of 3.183?(2)?Å. PMID:24046663

Hall, Gabriel B.; Medda, Federico; Roberts, Sue A.; Hulme, Christopher

2013-01-01

305

Studies of the degradation mechanism of organic light-emitting diodes based on tris(8-quinolinolate)aluminum Alq and 2-tert-butyl-9,10-di(2-naphthyl)anthracene TBADN  

NASA Astrophysics Data System (ADS)

Previously, radical cation of tris(8-quinolinolate)aluminum (Alq•+) has been associated with the instability of Alq films subjected to holes-only electrical current. Yet, the questions remain (i) whether Alq•+ is the primary source of the intrinsic degradation of bipolar organic light-emitting diodes (OLEDs) based on Alq, (ii) whether Alq•+ reactions result in deep charge traps in holes-only devices as found in bipolar counterparts, and (iii) whether radical cations can be a common source of degradation of OLEDs irrespective of materials. With regards to generality of hole-current-related degradation, it is interesting to examine the behavior of 9,10-diarylanthracenes (DAAs)—the practically important class of blue-fluorescing light-emitting-layer hosts. These questions prompted our comparative study of the effects of unipolar currents in Alq and 2-t-butyl-9,10-di(2-naphthyl)anthracene (TBADN), which was chosen as a representative material of the DAA class. First, we identified device structures allowing for rigorous and stable unipolar conduction. Interestingly, even in pristine holes-only devices, our voltammetric measurements indicated that Alq contains a substantial density of deep hole traps (far deeper than what can be explained by energetic disorder), which can be charged by passing holes-only current and seemingly discharged by exposure to white light. As for aged holes-only Alq devices, they exhibited symptoms qualitatively matching those of aged bipolar Alq devices, viz., photoluminescence (PL) loss, transition voltage (V0) rise, and drive voltage (Vd) rise. Notably, PL and V0 are linearly correlated in both holes-only and bipolar devices, which reinforces the supposed link between Alq•+ and the degradation in both types of devices. Yet, there are indications the Alq•+ instability may not be the only degradation pathway in bipolar devices. Even though our observations for holes-only Alq devices agree qualitatively with previously reported ones, we observe far slower degradation rates [Alq PL fades up to ˜500 times slower in holes-only devices, while Alq electroluminescence (EL) fades ˜50 times slower in bipolar control devices]. It is possible that impurities play a significant, perhaps crucial role in the degradation mechanism of both bipolar and holes-only devices, especially the relatively shorter-lived ones. In sharp contrast to Alq, all three observables (PL, V0, and Vd) indicate that holes-only current in TBADN (neat or doped with a perylene-based blue dopant) does not result in degradation in the time that is sufficient for the corresponding bipolar control devices to lose 60%-80% of EL and 20%-30% of PL. We find that the electrons-only current in Alq or TBADN does not result in degradation either. Thus, the degradation of Alq and DAA bipolar devices may be caused by fundamentally dissimilar mechanisms: while hole current may damage the former, it does not appear to affect the latter, suggesting that the initiation step is different.

Jarikov, Viktor V.; Kondakov, Denis Y.

2009-02-01

306

Mechanism and selectivity of methyl and phenyl migrations in hypervalent silylated iminoquinones.  

PubMed

Chlorosilanes R(X)(Y)SiCl (R = Me, Ph; X, Y = Me, Ph, Cl) have been reported to react with Pb(ONO(Q))2 (ONO(Q) = 3,5-di-tert-butyl-1,2-quinone-(3,5-di-tert-butyl-2-oxy-1-phenyl)imine) to give five-coordinate (X)(Y)Si(ON[R]O), in which the R group has migrated from silicon to nitrogen. This migration is intramolecular, as confirmed by the lack of crossover between (CH3)3SiCl and (CD3)3SiCl in their reaction with Pb(ONO(Q))2. Reaction of PhSiMeCl2 takes place with high kinetic stereoselectivity to produce isomer Ph(Cl)Si(ON[Me]O) in which the phenyl is axial in the trigonal bipyramid, which subsequently isomerizes to the thermodynamic isomer with axial chlorine. This indicates that migration takes place preferentially from the stereoisomer of the octahedral intermediate, ?(3)-Ph(CH3)(Cl)Si(ONO(Q)), in which the phenyl and methyl groups are mutually trans, indicating that the observed complete selectivity for methyl over phenyl migration is due to intrinsic differences in migratory aptitude. DFT calculations suggest that migration takes place from this isomer not because it undergoes migration faster than other possible stereoisomers, but because it is formed most rapidly, and migration occurs faster than isomerization. PMID:25289545

Shekar, Sukesh; Brown, Seth N

2014-12-19

307

27 CFR 21.101 - tert-Butyl alcohol.  

Code of Federal Regulations, 2013 CFR

...Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. ...add this solution to 80 ml of distilled water, and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A...

2013-04-01

308

27 CFR 21.101 - tert-Butyl alcohol.  

Code of Federal Regulations, 2012 CFR

...Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. ...add this solution to 80 ml of distilled water, and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A...

2012-04-01

309

27 CFR 21.101 - tert-Butyl alcohol.  

...Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. ...add this solution to 80 ml of distilled water, and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A...

2014-04-01

310

27 CFR 21.101 - tert-Butyl alcohol.  

Code of Federal Regulations, 2010 CFR

...Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. ...add this solution to 80 ml of distilled water, and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A...

2010-04-01

311

27 CFR 21.101 - tert-Butyl alcohol.  

Code of Federal Regulations, 2011 CFR

...Bé1. gasoline. (e) Freezing point (first needle). Above 20 °C. ...add this solution to 80 ml of distilled water, and filter when cool). Heat the mixture just to the boiling point and remove from the flame. A...

2011-04-01

312

A new mono-functionalized organoimido hexa­molybdate derivative: bis­(tetra-n-butyl­ammonium) (5-chloro-2-methyl­phenyl­imido)-?6-oxido-dodeca-?2-oxido-penta­oxidohexa­molybdate(VI)  

PubMed Central

The title complex, [(C4H9)4N]2[Mo6(C7H6ClN)O18], was prepared by the reaction of (Bu4N)4[?-Mo8O26] and 2-methyl-5-chloro­aniline hydro­chloride with N,N?-dicyclo­hexyl­carbodiimide as dehydrating agent in dry acetonitrile solution. The aryl­imido ligand is linked to an Mo atom of the Lindqvist-type hexamolybdate anion by an Mo N triple bond, with a bond length of 1.732?(4)?Å and an Mo N—C bond angle of 169.1?(4)°, typical for monodentate imido groups in such hybrid complexes. Due to the inter­action between one H atom in the aryl group and an O atom of a symmetry-related hexa­molybdate cluster, the anions form centrosymmetric dimers in the crystal structure. Weak C—H?O contacts are observed between the cations and anions. Unresolved disorder in some of the butyl chains of the ammonium cation is noted. PMID:22058705

Li, Qiang; Xiao, Zichen; Chen, Liye; Zhang, Jin

2011-01-01

313

Toxicology and biochemistry of butylated hydroxyanisole and butylated hydroxytoluene  

Microsoft Academic Search

Butylated hydroxyanisole and butylated hydroxytoluene are used extensively as food antioxidants. It is estimated that man\\u000a consumes ca. 0.1 mg\\/kg body wt daily of these antioxidants. At levels 500 times this level (50 mg\\/kg\\/day), both butylated\\u000a hydroxyanisole and butylated hydroxytoluene appear to be free of any obviously injurious effects. However, at larger doses\\u000a (500 mg\\/kg\\/day), both butylated hydroxyanisole and butylated

A. L. Branen

1975-01-01

314

(5-n-Butyl-10,20-diiso­butyl­porphyrin­ato)nickel(II)  

PubMed Central

The asymmetric unit of the title compound, [Ni(C32H36N4)], contains two independent mol­ecules exhibiting an overall ruffled conformation of the porphyrin macrocycle and differing mainly in the positions of the methyl groups. The average Ni—N bond lengths are 1.912?(2) and 1.910?(2)?Å in the two mol­ecules. The mol­ecules form a closely spaced lattice structure in which neighbouring porphyrins are oriented in a nearly perpendicular fashion to each other. The compound was prepared via nucleophilic substitution of (5,15-diiso­butyl­porphyrinato)nickel(II) with n-butyl­lithium. PMID:25161518

Senge, Mathias O.; Dahms, Katja

2014-01-01

315

Optimization of silylation using N-methyl-N-(trimethylsilyl)-trifluoroacetamide, N,O-bis-(trimethylsilyl)-trifluoroacetamide and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide for the determination of the estrogens estrone and 17alpha-ethinylestradiol by gas chromatography-mass spectrometry.  

PubMed

This paper reports an improved silylation procedure for simultaneous determination of the steroid hormones 17alpha-ethinylestradiol (EE2) and estrone (E1) using gas chromatography-mass spectrometry (GC-MS). This follows a re-assessment of some of the popular silylation procedures using N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), N-O-bis-(trimethylsilyl)-trifluoroacetamide (BSTFA) and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA), which lead to the formation of trimethylsilyl (TMS) and tert-butyldimethylsilyl (TBS) derivatives. Silylation of EE2 using MSTFA or BSTFA+1% TMCS in ethyl acetate, acetonitrile and dichloromethane solvents produced multiple peaks corresponding to TMS-E1, and 3-mono-TMS-EE2 and/or 3,17-di-TMS-EE2 in variable proportions depending on the solvent used. When pyridine or dimethyl formamide solvents were used in the silylation of EE2 under the same reaction conditions, only 3,17-di-TMS-EE2 derivative was formed. Derivatization using MTBSTFA reagents using ethyl acetate, acetonitrile, dichloromethane, pyridine and dimethyl formamide resulted in almost 100% conversion of mono-TBS-EE2 to the TBS-E1. Therefore, typical methods used in some previous GC-MS determinations of E1 and EE2 in environmental water and/or sediment samples are subject to speculation. However, we can confirm that any of the TMS reagents can be used with either pyridine or dimethyl formamide under suitable reaction conditions. PMID:16445920

Shareef, Ali; Angove, Michael J; Wells, John D

2006-03-01

316

Aquincola tertiaricarbonis gen. nov., sp. nov., a tertiary butyl moiety-degrading bacterium.  

PubMed

Strains L10(T), L108 and CIP I-2052 were originally obtained from methyl tert-butyl ether (MTBE)-contaminated groundwater and from a wastewater treatment plant, respectively. All share the ability to grow on tert-butanol, an intermediate of MTBE degradation. Cells are strictly aerobic, motile by a polar flagellum and exhibit strong pili formation. Poly beta-hydroxybutyrate (PHB) granules are formed. The DNA G+C content is 69-70.5 mol% and the main ubiquinone is Q-8. The major cellular fatty acids are 16 : 1 cis-9 and 16 : 0 and the only hydroxy fatty acid is 10 : 0 3-OH. The major phospholipids are phosphatidylethanolamine (PE) 16 : 1/16 : 1 and phosphatidylglycerol 16 : 0/16 : 1. A significant amount of PE 17 : 0/16 : 1 is present. The 16S rRNA gene sequences of these strains are almost identical and form a separate line of descent in the Rubrivivax-Roseateles-Leptothrix-Ideonella-Aquabacterium branch of the Betaproteobacteria with 97 % similarity to 16S rRNA genes of the type strains of Rubrivivax gelatinosus, Leptothrix mobilis and Ideonella dechloratans. However, physiological properties, DNA-DNA relatedness values and the phospholipid and cellular fatty acid profiles distinguish the novel isolates from the three closely related genera. Therefore, it is concluded that strains L10(T), L108 and CIP I-2052 represent a new genus and novel species for which the name Aquincola tertiaricarbonis gen. nov., sp. nov., is proposed. The type strain is strain L10(T) (=DSM 18512(T)=CIP 109243(T)). PMID:17551046

Lechner, Ute; Brodkorb, Danny; Geyer, Roland; Hause, Gerd; Härtig, Claus; Auling, Georg; Fayolle-Guichard, Françoise; Piveteau, Pascal; Müller, Roland H; Rohwerder, Thore

2007-06-01

317

Subchronic exposure to ethyl tertiary butyl ether resulting in genetic damage in Aldh2 knockout mice.  

PubMed

Ethyl tertiary butyl ether (ETBE) is biofuel additive recently used in Japan and some other countries. Limited evidence shows that ETBE has low toxicity. Acetaldehyde (AA), however, as one primary metabolite of ETBE, is clearly genotoxic and has been considered to be a potential carcinogen. The aim of this study was to evaluate the effects of ALDH2 gene on ETBE-induced genotoxicity and metabolism of its metabolites after inhalation exposure to ETBE. A group of wild-type (WT) and Aldh2 knockout (KO) C57BL/6 mice were exposed to 500ppm ETBE for 1-6h, and the blood concentrations of ETBE metabolites, including AA, tert-butyl alcohol and 2-methyl-1,2-propanediol, were measured. Another group of mice of WT and KO were exposed to 0, 500, 1750, or 5000ppm ETBE for 6h/day with 5 days per weeks for 13 weeks. Genotoxic effects of ETBE in these mice were measured by the alkaline comet assay, 8-hydroxyguanine DNA-glycosylase modified comet assay and micronucleus test. With short-term exposure to ETBE, the blood concentrations of all the three metabolites in KO mice were significantly higher than the corresponding concentrations of those in WT mice of both sexes. After subchronic exposure to ETBE, there was significant increase in DNA damage in a dose-dependent manner in KO male mice, while only 5000ppm exposure significantly increased DNA damage in male WT mice. Overall, there was a significant sex difference in genetic damage in both genetic types of mice. These results showed that ALDH2 is involved in the detoxification of ETBE and lack of enzyme activity may greatly increase the sensitivity to the genotoxic effects of ETBE, and male mice were more sensitive than females. PMID:23810710

Weng, Zuquan; Suda, Megumi; Ohtani, Katsumi; Mei, Nan; Kawamoto, Toshihiro; Nakajima, Tamie; Wang, Rui-Sheng

2013-09-15

318

Microsolvation and sp(2)-stereoinversion of monomeric ?-(2,6-di-tert-butylphenyl)vinyllithium as measured by NMR.  

PubMed

The ?-unsubstituted title compound dissolves in THF as a uniformly trisolvated monomer, whereas it forms exclusively disolvated monomers in tert-butyl methyl ether, Et2O, TMEDA, or toluene with TMEDA (1.4 equiv). This was established at low temperatures through the observation of separated NMR signals for free and lithium-coordinated ligands and/or through the patterns and magnitudes of (13)C,(6)Li NMR coupling constants. An aggregated form was observed only with Et2O (2 equiv) in toluene as the solvent. The olefinic geminal interproton coupling constants of the H2C= part can be used as a secondary criterion to differentiate between these differently solvated ground-states (3, 2, or <2 coordinated ligands per Li). Due to a kinetic trisolvation privilege of THF, the cis/trans sp(2)-stereoinversion rates could be measured through analyses of (1)H NMR line broadening and coalescence only in THF as the solvent: The pseudomonomolecular (because THF-catalyzed), ionic mechanism is initialized by a C-Li bond heterolysis with the transient immobilization of one additional THF ligand, followed by stereoinversion of the quasi-sp(2)-hybridized carbanionic center in cooperation with a "conducted tour" migration of Li(+)(THF)4 along the ?-aryl group within the solvent-separated ion pair. PMID:25383123

Knorr, Rudolf; Knittl, Monika; Rossmann, Eva C

2014-01-01

319

Microsolvation and sp2-stereoinversion of monomeric ?-(2,6-di-tert-butylphenyl)vinyllithium as measured by NMR  

PubMed Central

Summary The ?-unsubstituted title compound dissolves in THF as a uniformly trisolvated monomer, whereas it forms exclusively disolvated monomers in tert-butyl methyl ether, Et2O, TMEDA, or toluene with TMEDA (1.4 equiv). This was established at low temperatures through the observation of separated NMR signals for free and lithium-coordinated ligands and/or through the patterns and magnitudes of 13C,6Li NMR coupling constants. An aggregated form was observed only with Et2O (2 equiv) in toluene as the solvent. The olefinic geminal interproton coupling constants of the H2C= part can be used as a secondary criterion to differentiate between these differently solvated ground-states (3, 2, or <2 coordinated ligands per Li). Due to a kinetic trisolvation privilege of THF, the cis/trans sp2-stereoinversion rates could be measured through analyses of 1H NMR line broadening and coalescence only in THF as the solvent: The pseudomonomolecular (because THF-catalyzed), ionic mechanism is initialized by a C–Li bond heterolysis with the transient immobilization of one additional THF ligand, followed by stereoinversion of the quasi-sp2-hybridized carbanionic center in cooperation with a “conducted tour” migration of Li+(THF)4 along the ?-aryl group within the solvent-separated ion pair. PMID:25383123

Knittl, Monika; Rossmann, Eva C

2014-01-01

320

40 CFR 414.70 - Applicability; description of the bulk organic chemicals subcategory.  

...Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n-Butyraldehyde n-Butyric Acid n-Butyric Anhydride *n-Paraffins...

2014-07-01

321

40 CFR 414.70 - Applicability; description of the bulk organic chemicals subcategory.  

Code of Federal Regulations, 2011 CFR

...Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n-Butyraldehyde n-Butyric Acid n-Butyric Anhydride *n-Paraffins...

2011-07-01

322

40 CFR 414.70 - Applicability; description of the bulk organic chemicals subcategory.  

Code of Federal Regulations, 2012 CFR

...Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n-Butyraldehyde n-Butyric Acid n-Butyric Anhydride *n-Paraffins...

2012-07-01

323

40 CFR 414.70 - Applicability; description of the bulk organic chemicals subcategory.  

Code of Federal Regulations, 2013 CFR

...Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n-Butyraldehyde n-Butyric Acid n-Butyric Anhydride *n-Paraffins...

2013-07-01

324

Autoxidation of methyl linoleate initiated by the ozonide of allylbenzene  

SciTech Connect

Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18:2 ME) at 37 degrees C under 760 torr of oxygen. This process is inhibited by d-alpha-tocopherol (alpha-T) and 2,6-di-tert-butyl-4-methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen-uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N2 in the presence of radical scavengers and found to be Ea = 28.2 +/- 0.3 kcal mol-1 and log A = 13.6 +/- 0.2; kd (37 degrees C) is calculated to be (5.1 +/- 0.3) X 10(-7) sec-1. Autoxidation data are also reported for ozonides of 18:2 ME and methyl oleate (18:1 ME).

Ewing, J.C.; Cosgrove, J.P.; Giamalva, D.H.; Church, D.F.; Pryor, W.A. (Louisiana State Univ., Baton Rouge (USA))

1989-07-01

325

Analysis of Organic Molecules Extracted from Mars Analogues and Influence of Their Mineralogy Using N-Methyl-N-(tert-butyldimethylsilyl)Trifluoroacetamide Derivatization Coupled with Gas Chromatography Mass Spectrometry in Preparation for the Sample Analysis at Mars Derivatization Experiment on the Mars Science Laboratory Mission  

NASA Technical Reports Server (NTRS)

The search for complex organic molecules on Mars, including important biomolecules such as amino acids and carboxylic acids will require a chemical extraction and derivatization step to transform these organic compounds into species that are sufficiently volatile to be detected by gas chromatography mass spectrometry (GCMS). We have developed, a one-pot extraction and chemical derivatization protocol using N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and dimethylformamide (DMF) for the Sample Analysis at Mars (SAM) experiment on the Mars Science Laboratory (MSL). The temperature and duration the derivatization reaction, pre-concentration of chemical derivatives, and gas chromatographic separation parameters have been optimized under SAM instrument design constraints. MTBSTFA/DMF extraction and derivatization at 300 C for several minutes of a variety of terrestrial Mars analogue materials facilitated the detection of amino acids and carboxylic acids in a surface soil sample collected from the Atacama Desert and a carbonate-rich stromatolite sample from Svalbard. However, the rapid reaction of MTBSTFA with water in several analogue materials that contained high abundances of hydrated minerals and the possible deactivation of derivatized compounds by iron oxides, as detected by XRD/XRF using the CheMin field unit Terra, proved to be highly problematic for the direct extraction of organics using MTBSTFA, The combination of pyrolysis and two different chemical derivatization methods employed by SAM should enable a wide range of organic compounds to be detected by GCMS if present on Mars,

Stalport, F.; Glavin, D. P.; Eigenbrode, J. L.; Bish, D.; Blake, D.; Coll, P.; Szopa, C.; Buch, A.; McAdam, A.; Dworkin, J. P.; Mahaffy, P. R.

2012-01-01

326

Identification of tertiary butyl alcohol (TBA)-utilizing organisms in BioGAC reactors using 13 CDNA stable isotope probing  

Microsoft Academic Search

Biodegradation of the gasoline oxygenates methyl tertiary-butyl ether (MTBE) and ethyl tertiary-butyl ether (ETBE) can cause tertiary butyl alcohol (TBA) to accumulate in gasoline-impacted environments. One remediation option for TBA-contaminated groundwater\\u000a involves oxygenated granulated activated carbon (GAC) reactors that have been self-inoculated by indigenous TBA-degrading\\u000a microorganisms in ground water extracted from contaminated aquifers. Identification of these organisms is important for

Denise Aslett; Joseph Haas; Michael Hyman

2011-01-01

327

Crystal structure of hexa­kis­(?2-4-tert-but­oxy-4-oxobut-2-en-2-olato)trizinc  

PubMed Central

The title complex, systematic name hexa­kis­(?2-4-tert-but­oxy-4-oxobut-2-en-2-olato)-1:2?9 O 2,O 4:O 2;2:3?9 O 2,O 4:O 2-trizinc, [Zn3(C8H13O3)6], syn­the­sized from tert-butyl aceto­acetate and di­ethyl­zinc, consists of trinuclear centrosymmetric mol­ecules of an approximate C 3i symmetry. The three metal cations are arranged in a linear fashion, with the central ZnII atom located on a centre of symmetry. All three metal cations exhibit a distorted octa­hedral coordination geometry. The terminal ZnII cations are chelated by three tert-butyl aceto­acetate ligands and these units are connected to the central ZnII atom by the bridging enolate O atoms. PMID:25552972

Shtokvish, Olgerd O.; Koval, Lyudmila I.; Pekhnyo, Vasyl I.

2014-01-01

328

Three TERT genes in Nicotiana tabacum.  

PubMed

Telomerase is essential for proper functioning of telomeres in eukaryotes. We cloned and characterised genes for the protein subunit of telomerase (TERT) in the allotetraploid Nicotiana tabacum (tobacco) and its diploid progenitor species Nicotiana sylvestris and Nicotiana tomentosiformis with the aim of determining if allopolyploidy (hybridisation and genome duplication) influences TERT activity and divergence. Two of the three sequence variants present in the tobacco genome (NtTERT-C/s and NtTERT-D) revealed similarity to two sequence variants found in N. sylvestris and another variant (NtTERT-C/t) was similar to TERT of N. tomentosiformis. Variants of N. sylvestris origin showed less similarity to each other (80.5 % in the genomic region; 90.1 % in the coding sequence) than that between the NtTERT-C/s and NtTERT-C/t variants (93.6 and 97.2 %, respectively). The NtTERT-D variant was truncated at the 5' end, and indels indicated that it was a pseudogene. All tobacco variants were transcribed and alternatively spliced sequences were detected. Analysis of gene arrangements uncovered a novel exon in the N-terminal domain of TERT variants, a feature that is likely to be commonly found in Solanaceae species. In addition, species-specific duplications were observed within exon 5. The putative function, copy number and evolutionary origin of these NtTERT sequence variants are discussed. PMID:22543812

Sýkorová, Eva; Fulne?ková, Jana; Mokroš, Petr; Fajkus, Ji?í; Fojtová, Miloslava; Peška, Vratislav

2012-05-01

329

N-tert-Butoxycarbonylation of Structurally Diverse Amines and Sulfamides under Water-Mediated Catalyst-Free Conditions  

PubMed Central

A simple, efficient, and eco-friendly protocol for the N-Boc protection of the amine moiety in a variety of compounds with di-tert-butyl dicarbonate under water-acetone catalyst-free conditions is described. The corresponding monocarbamate is obtained in excellent yields on short reaction times. No competitive side reactions such as isocyanate urea and O-Boc were observed. This method represents a reasonable alternative to the previous reported protection procedures. PMID:24052842

Cheraiet, Zinelaabine; Ouarna, Souad; Hessainia, Sihem; Berredjem, Malika; Aouf, Nour-Eddine

2012-01-01

330

Reaction of tert-butoxy radicals with phenols. Comparison with the reactions of carbonyl triplets  

SciTech Connect

Tert-butoxy radicals generated in the photodecomposition of di-tert-butyl peroxide react efficiently with phenols to yield the corresponding phenoxy radicals. Typical rate constants in benzene at 22/sup 0/C are 3.3 x 10/sup 8/ and 1.6 x 10/sup 9/ M/sup -1/ s/sup -1/ for phenol and p-methoxyphenol, respectively. The process is considerably slower in polar solvents; e.g., when pyridine is used as cosolvent, the rate constant for phenol drops to 4.1 x 10/sup 6/ M/sup -1/ s/sup -1/ as a result of strong hydrogen bonding which decreases the reactivity of the phenolic O-H group. Isotope effects (H/D) are typically in the 3 to 5 range. 5 figures, 4 tables.

Das, P.K.; Encinas, M.V.; Steenken, S.; Scaiano, J.C.

1981-07-15

331

Synthesis and properties of phosphono-derivatives of methyl stearate  

Technology Transfer Automated Retrieval System (TEKTRAN)

A series of phosphono-derivatives of methyl stearate (PhDMS) were synthesized from methyl oleate and dialkyl H-phosphonates (dialkyl-phosphites). The alkyl groups in the phosphonates were methyl, ethyl, and butyl. The reaction can be carried to 98+% completion with a radical initiator. It is possibl...

332

Synthesis and in vivo evaluation of [18F]2-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)-dione ([18F]FECUMI-101) as an imaging probe for 5-HT1A receptor agonist in nonhuman primates  

PubMed Central

The 5-HT1AR partial agonist PET radiotracer, [11C]CUMI-101, has advantages over an antagonist radiotracer as it binds preferentially to the high affinity state of the receptor and thereby provides more functionally meaningful information. The major drawback of C-11 tracers is the lack of cyclotron facility in many health care centers thereby limiting widespread clinical or research use. We identified the fluoroethyl derivative, 2-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)dione (FECUMI-101) (Ki = 0.1 nM; Emax = 77%; EC50 = 0.65 nM) as a partial agonist 5-HT1AR ligand of the parent ligand CUMI-101. FECUMI-101 is radiolabeled with F-18 by O-fluoroethylation of the corresponding desmethyl analogue (1) with [18F]fluoroethyltosylate in DMSO in the presence of 1.6 equiv. of K2CO3 in 45 ± 5% yield (EOS). PET shows [18F]FECUMI-101 binds specifically to 5-HT1AR enriched brain regions of baboon. The specificity of [18F]FECUMI-101 binding to 5-HT1AR was confirmed by challenge studies with the known 5-HT1AR ligand WAY100,635. These findings indicate that [18F]FECUMI-101 can be a viable agonist ligand for the in vivo quantification of high affinity 5-HT1AR with PET. PMID:23816046

Majo, Vattoly J.; Milak, Matthew S.; Prabhakaran, Jaya; Mali, Pratap; Savenkova, Lyudmila; Simpson, Norman R.; Mann, J. John; Parsey, Ramin V.; Dileep Kumar, J. S.

2013-01-01

333

Di-n-butyl­ammonium 2-(3,5-di-tert-butyl-4-hydroxy­benzyl­sulfan­yl)nicotinate  

PubMed Central

The asymmetric unit of the title compound, C8H20N+·C21H26NO3S?, contains two indpendent ion pairs which are disposed about a psuedo-inversion center, generating an ammonium–carboxylate N—H?O hydrogen-bonded four-component cluster. In the crystal structure, adjacent clusters are linked by hydr­oxy–carboxylate O—H?O hydrogen bonds, forming a chain. PMID:21201778

Mansor, Shahirah; Yehye, Wagee A.; Ariffin, Azhar; Rahman, Noorsaadah Abdul; Ng, Seik Weng

2008-01-01

334

Comparative cytotoxicity between butylated hydroxytoluene and its methylcarbamate derivative, terbucarb, on isolated rat hepatocytes  

SciTech Connect

Butylated hydroxytoluene (3,5-di-tert-butyl-4-hydroxytoluene; BHT) is widely used as phenolic antioxidant in processed foods, cosmetics and petroleum products. It is well known that high doses of BHT cause acute hepatic damage accompanied by centrilobular necrosis in rats. The hepatic damage is associated with prolonged depletion of glutathione (GSH). Terbucarb (2,6-di-tert-butyl-para-tolyl-methylcarbamate), which has a methylcarbamate group substituted for the phenol group on BHT, was developed as an insecticide and is also presently used as a herbicide on turfgrass. Despite the metabolic and toxicological details known about BHT in vivo and in vitro, no extensive studies have been reported on the metabolism and toxicity of Terbucarb. The isolated hepatocyte system provides a very useful system for the study of the temporal sequences leading to cell damage caused by chemicals and drugs. Here, using freshly isolated rat hepatocytes, we report on the comparative toxic effects of BHT and its methylcarbamate derivative, Terbucarb. 17 refs., 2 figs., 2 tabs.

Nakagawa, Y.; Yaguchi, K.; Suzuki, T. (Tokyo Metropolitan Research Lab. of Public Health (Japan))

1994-08-01

335

Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes Bearing 2-Pyrazolato Ligands: Development of a New Class of Precursors for  

E-print Network

Synthesis, Structure, and Molecular Orbital Studies of Yttrium, Erbium, and Lutetium Complexes procedure, the reaction of erbium metal with 3,5-dialkylpyrazole (alkyl ) methyl or tert-butyl), bis-tert-butylpyrazole) yielded tris(3,5-di-tert-butylpyrazolato)bis(4-tert-butylpy- ridine)erbium(III) (63%), tris(3,5-di-tert-butylpyrazolato)bis(pyridine)erbium

Schlegel, H. Bernhard

336

TERT promoter mutations and gene amplification: promoting TERT expression in Merkel cell carcinoma.  

PubMed

Telomerase activation through the induction of its catalytic component TERT is essential in carcinogenesis. The regulatory mechanism and clinical significance underlying cancer-specific TERT expression have been extensively investigated in various human malignancies, but little is known about these in Merkel cell carcinoma (MCC), an aggressive neuroendocrine skin tumor. Here we addressed these issues by determining TERT promoter mutations, gene amplification, mRNA expression and association with clinical variables in MCC. TERT mRNA was expressed in 6/6 MCC cell lines and 41 of 43 tumors derived from 35 MCC patients. Telomerase activity was detectable in all 6 cell lines and 11 tumors analyzed. TERT promoter mutations were identified in 1/6 cell lines and 4/35 (11.4%) MCC cases. The mutation exhibited UV signature and occurred in sun-exposed areas. Increased TERT gene copy numbers were observed in 1/6 cell lines and 11/14 (79%) tumors, and highly correlated with its mRNA expression (r = 0.7419, P = 0.0024). Shorter overall survival was significantly associated with higher TERT mRNA levels in MCC patients (P = 0.032). Collectively, TERT expression and telomerase activity is widespread in MCC, and may be attributable to TERT promoter mutations and gene amplification. Higher TERT expression predicts poor patient outcomes. PMID:25301727

Xie, Hong; Liu, Tiantian; Wang, Na; Björnhagen, Viveca; Höög, Anders; Larsson, Catharina; Lui, Weng-Onn; Xu, Dawei

2014-10-30

337

Inhibition of cell proliferation and induction of apoptosis by oleanane triterpenoid (CDDO-Me) in pancreatic cancer cells is associated with the suppression of hTERT gene expression and its telomerase activity  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT gene expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT protein expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT telomerase activity. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT regulatory proteins. -- Abstract: Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a multifunctional oleanane synthetic triterpenoid with potent anti-inflammatory and antitumorigenic properties. The mechanisms of the antisurvival and apoptosis-inducing activities of CDDO-Me and related derivatives of oleanolic acid have been defined; however, to date, no study has been carried out on the effect of CDDOs on human telomerase reverse transcriptase (hTERT) gene or telomerase activity. Here we report for the first time that inhibition of cell proliferation and induction of apoptosis by CDDO-Me in pancreatic cancer cell lines is associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT expression and activity. Furthermore, abrogation or overexpression of hTERT protein altered the susceptibility of tumor cells to CDDO-Me. These findings suggest that telomerase (hTERT) is a relevant target of CDDO-Me in pancreatic cancer cells.

Deeb, Dorrah; Gao, Xiaohua; Liu, Yongbo [Department of Surgery, Henry Ford Health System, Detroit, MI (United States)] [Department of Surgery, Henry Ford Health System, Detroit, MI (United States); Kim, Sahn-Ho [Department of Urology, Henry Ford Health System, Detroit, MI (United States)] [Department of Urology, Henry Ford Health System, Detroit, MI (United States); Pindolia, Kirit R. [Department of Medical Genetics, Henry Ford Health System, Detroit, MI (United States)] [Department of Medical Genetics, Henry Ford Health System, Detroit, MI (United States); Arbab, Ali S. [Department of Radiology, Henry Ford Health System, Detroit, MI (United States)] [Department of Radiology, Henry Ford Health System, Detroit, MI (United States); Gautam, Subhash C., E-mail: sgautam1@hfhs.org [Department of Surgery, Henry Ford Health System, Detroit, MI (United States)

2012-06-15

338

Hydrogenophaga carboriunda sp. nov., a tertiary butyl alcohol-oxidizing, psychrotolerant aerobe derived from granular-activated carbon (GAC).  

PubMed

A Gram-negative, rod-shaped bacterium was isolated from a mixed culture that degraded tert-butyl alcohol (TBA) in a granular-activated carbon (GAC) sample from a Biological-GAC reactor. Strain YZ2(T) was assigned to the Betaproteobacteria within the family Comamonadaceae based on 16S rRNA gene similarities. The nearest phylogenetic relative (95.0 % similarity) with a valid name was Hydrogenophaga taeniospiralis. The DNA G+C content was 66.4 mol%. DNA:DNA hybridization indicated that the level of relatedness to members of the genus Hydrogenophaga ranged from 1.1 to 10.8 %. The dominant cellular fatty acids were: 18:1 w7c (75 %), 16:0 (4.9 %), 17:0 (3.85 %), 18:0 (2.93 %), 11 methyl 18:1 w7c (2.69 %), Summed Feature 2 (2.27 %), and 18:0 3OH (1.35 %). The primary substrate used was TBA, which is a fuel oxygenate and groundwater contaminant. YZ2(T) was non-motile, without apparent flagella. It is a psychrotolerant, facultative aerobe that grew between pH 6.5 and 9.5, and 4 and 30 °C. The culture grew on and mineralized TBA at 4 °C, which is the first report of psychrotolerant TBA degradation. Hydrogen was used as an alternative electron donor. The culture also grew well in defined freshwater medium with ethanol, butanol, hydroxy isobutyric acid, acetate, pyruvate, citrate, lactate, isopropanol, and benzoic acid as electron donors. Nitrate was reduced with hydrogen as the sole electron donor. On the basis of morphological, physiological, and chemotaxonomic data, a new species, Hydrogenophaga carboriunda is proposed, with YZ2(T) as the type strain. PMID:24343174

Reinauer, Kimberly M; Popovic, Jovan; Weber, Christopher D; Millerick, Kayleigh A; Kwon, Man Jae; Wei, Na; Zhang, Yang; Finneran, Kevin T

2014-04-01

339

BORIS/CTCFL-mediated transcriptional regulation of the hTERT telomerase gene in testicular and ovarian tumor cells  

PubMed Central

Telomerase activity, not detectable in somatic cells but frequently activated during carcinogenesis, confers immortality to tumors. Mechanisms governing expression of the catalytic subunit hTERT, the limiting factor for telomerase activity, still remain unclear. We previously proposed a model in which the binding of the transcription factor CTCF to the two first exons of hTERT results in transcriptional inhibition in normal cells. This inhibition is abrogated, however, by methylation of CTCF binding sites in 85% of tumors. Here, we showed that hTERT was unmethylated in testicular and ovarian tumors and in derivative cell lines. We demonstrated that CTCF and its paralogue, BORIS/CTCFL, were both present in the nucleus of the same cancer cells and bound to the first exon of hTERT in vivo. Moreover, exogenous BORIS expression in normal BORIS-negative cells was sufficient to activate hTERT transcription with an increasing number of cell passages. Thus, expression of BORIS was sufficient to allow hTERT transcription in normal cells and to counteract the inhibitory effect of CTCF in testicular and ovarian tumor cells. These results define an important contribution of BORIS to immortalization during tumorigenesis. PMID:20876690

Renaud, Stéphanie; Loukinov, Dmitri; Alberti, Loredana; Vostrov, Alexander; Kwon, Yoo-Wook; Bosman, Fred T.; Lobanenkov, Victor; Benhattar, Jean

2011-01-01

340

MONITORED NATURAL ATTENUATION OF TERTIARY BUTYL ALCOHOL (TBA) IN GROUND WATER AT GASOLINE SPILL SITES  

EPA Science Inventory

The state agencies that implement the Underground Storage Tank program rely heavily on Monitored Natural Attenuation (MNA) to clean up contaminants such as benzene and methyl tertiary butyl ether (MTBE) at gasoline spill sites. This is possible because the contaminants are biolo...

341

Enantiodifferentiation of 3-sec-butyl-2-methoxypyrazine in different species using multidimensional and comprehensive two-dimensional gas chromatographic approaches.  

PubMed

With respect to the current hypothesis that natural amino acids may serve as starting material for the biosynthesis of alkyl-methoxypyrazines, the enantiomeric distribution of the potent aroma compound 3-sec-butyl-2-methoxypyrazine (SBMP) was determined in various species using heart-cut multidimensional gas chromatography (H/C MDGC) or comprehensive two-dimensional gas chromatography (GC?×?GC). Complementary to an earlier described separation on octakis-(6-O-methyl-2,3-di-O-pentyl)-?-cyclodextrin used as chiral stationary phase, we found a reversal of the elution order of SBMP enantiomers on heptakis-(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-?-cyclodextrin, providing further confirmation options for that type of analysis. Optimization of the enantioseparation of SBMP in a single-oven H/C enantio-MDGC system involved the use of a dual-jet cryo modulator for trapping of analytes transferred from the achiral (1)D column to the chiral (2)D column before starting the (2)D enantioseparation with an independent temperature ramp. For the enantiodifferentiation by enantio-GC?×?GC, the modulation period had to be significantly shortened to avoid loss of chiral resolution gained in (1)D. H/C MDGC with mass spectrometric detection (MS) using selected ion monitoring (SIM) was sufficient for parts per billion level analysis, whereas H/C MDGC-MS/MS or GC?×?GC time-of-flight (TOF) MS were necessary for parts per trillion level analysis. In various vegetables, lady beetles and Vitis vinifera species analyzed, only (S)-SBMP was detected, supporting the hypothesis of natural amino acids serving as starting material for the biosynthesis of alkyl-methoxypyrazines. PMID:25146352

Legrum, Charlotte; Slabizki, Petra; Schmarr, Hans-Georg

2015-01-01

342

Mechanisms of cytotoxicity of 2- or 2,6-di- tert-butylphenols and 2-methoxyphenols in terms of inhibition rate constant and a theoretical parameter  

Microsoft Academic Search

To clarify the mechanism of phenol toxicity, the radical-scavenging activity of 2- or 2,6-di-tert-butyl- and 2-methoxy-substituted phenols was investigated by combining two distinct approaches: first, the induction period method for methacrylate polymerization initiated by benzoyl peroxide or 2,2?-azobisisobutyronitrile; and secondly, 1,1?-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging test. The homolytic bond dissociation enthalpy (BDE) and ionization potential (IPkoopman) were calculated by the DFT\\/B3LYP

Yoshinori Kadoma; Shigeru Ito; Toshiko Atsumi; Seiichiro Fujisawa

2009-01-01

343

MLH1 mediates PARP-dependent cell death in response to the methylating agent N-methyl-N-nitrosourea  

Microsoft Academic Search

Background:Methylating agents such as N-methyl-N-nitrosourea (MNU) can cause cell cycle arrest and death either via caspase-dependent apoptosis or via a poly(ADP-ribose) polymerase (PARP)-dependent form of apoptosis. We wished to investigate the possible role of MLH1 in signalling cell death through PARP.Methods:Fibroblasts are particularly dependent on a PARP-mediated cell death response to methylating agents. We used hTERT-immortalised normal human fibroblasts (WT)

J R McDaid; J Loughery; P Dunne; J C Boyer; C S Downes; R A Farber; C P Walsh

2009-01-01

344

40 CFR 704.33 - P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB).  

Code of Federal Regulations, 2013 CFR

...33 P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene...substance p-tert-butylbenzoic acid, also identified as 4-(1,1-dimethylethyl)benzoic acid, CAS No. 98-73-7. ...purposes during the person's latest complete corporate...

2013-07-01

345

40 CFR 704.33 - P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB).  

...33 P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene...substance p-tert-butylbenzoic acid, also identified as 4-(1,1-dimethylethyl)benzoic acid, CAS No. 98-73-7. ...purposes during the person's latest complete corporate...

2014-07-01

346

40 CFR 704.33 - P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB).  

Code of Federal Regulations, 2011 CFR

...33 P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene...substance p-tert-butylbenzoic acid, also identified as 4-(1,1-dimethylethyl)benzoic acid, CAS No. 98-73-7. ...purposes during the person's latest complete corporate...

2011-07-01

347

40 CFR 704.33 - P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene (P-TBT) and p-tert-butylbenzaldehyde (P-TBB).  

Code of Federal Regulations, 2012 CFR

...33 P-tert-butylbenzoic acid (P-TBBA), p-tert-butyltoluene...substance p-tert-butylbenzoic acid, also identified as 4-(1,1-dimethylethyl)benzoic acid, CAS No. 98-73-7. ...purposes during the person's latest complete corporate...

2012-07-01

348

Isolation and characterization of a new Mycobacterium austroafricanum strain, IFP 2015, growing on MTBE  

Microsoft Academic Search

A new Mycobacterium austroafricanum strain, IFP 2015, growing on methyl tert-butyl ether (MTBE) as a sole carbon source was isolated from an MTBE-degrading microcosm inoculated with drain water of an MTBE-supplemented gasoline storage tank. M. austroafricanum IFP 2015 was able to grow on tert-butyl formate, tert-butyl alcohol (TBA) and ?-hydroxyisobutyrate. 2-Methyl-1,2-propanediol was identified as the TBA oxidation product in M.

Nicolas Lopes Ferreira; Helena Maciel; Hugues Mathis; Frédéric Monot; Françoise Fayolle-Guichard; Charles W. Greer

2006-01-01

349

Bis(?5-1-tert-butyl­inden­yl)nickel(II)  

PubMed Central

The title compound, [Ni(C13H15)2], shows a slightly distorted sandwich structure with two independent mol­ecules in the asymmetric unit. Both Ni atoms are located on crystallographic centres of inversion. PMID:22065650

Bauer, Heiko; Sun, Yu; Sitzmann, Helmut

2011-01-01

350

Toxicity of 2,6-Di-tert-butyl-4-Nitrophenol (DBNP).  

PubMed

U.S. Navy submarines reported a yellowing of metal surfaces on their internal surfaces. The yellowing was initially identified on the painted steel bulkheads but further examination indicated that it was not limited to steel surfaces and included bedding, thread tape, Formica, plastisol covered hand-wheels, and aluminum lockers. Crew members also reported to the medical department that their skin turned yellow when they came in contact with these contaminated surfaces and requested information on the effects of exposure. Studies conducted by General Dynamics' Electric Boat Division (EBD) determined that the agent was 2,6-Di-tertbutyl-4-Nitrophenol (DBNP). 2,6-Di-butylphenol (DBP) is an antioxidant additive used in lubricating oils and hydraulic fluids. In the enclosed atmosphere of a submarine, the oil mist could be spread throughout the boat by venting the lube oil to the atmosphere. Submarines use electrostatic precipitators (ESP) to clean the air of particulate materials. During passage through the ESP, oil mist containing DBP is nitrated to DBNP, which is then moved throughout the boat in the ventilation system. Analysis of the EBD data indicated 24-hour exposure concentrations to be in the range of <3.0 to 122 ppb in the laboratory and submarine settings. Submarine crews may be exposed to these concentrations for as many as 24 hours/ day for 90 days during underway periods. Toxicity studies regarding the oral and dermal uptake of DBNP were conducted. From the literature the lethal dose to 50 percent of the population (LD50) of DBNP (rat) was reported by Vesselinovitch et al. in 1961 to be 500 mg/kg. Our studies indicated that the LD50 is in the range of 80 mg/kg in the rat. Our work also includes dermal absorption studies, which indicated that DBNP is not well absorbed through intact skin. Within this study, no no-observable adverse effect level (NOAEL) or lowest observable adverse effect level (LOAEL) was identified. Calculation of a reference dose was completed using standard methods based on the LD50 as a numerator with several uncertainty and modifying factors. EBD's determination of airborne concentrations aboard submarines fall in the range of these anticipated allowable concentrations and could indicate significant chronic exposures. No adverse effects from DBNP exposures have been reported to date. PMID:11318392

Alexander, W K; Briggs, G B; Still, K R; Jederberg, W W; MacMahon, K; Baker, W H; Mackerer, C

2001-04-01

351

Control Study of Ethyl tert-Butyl Ether Reactive Distillation Muhammad A. Al-Arfaj  

E-print Network

feed stream contains both isobutene and normal butene, and the latter does not participate in the reaction. The chemically inert normal butene is much lighter than ETBE, so the distillate is mostly nC4 d the butene product contains isobutene, normal butene, and other light hydrocarbons. Therefore, the butene

Al-Arfaj, Muhammad A.

352

IRIS Toxicological Review of Tert-Butyl Alcohol (Tba) (Preliminary Draft Materials)  

EPA Science Inventory

In August 2013, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for TBA to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in c...

353

An effective method for allylic oxidation of Delta5-steroids using tert-butyl hydroperoxide.  

PubMed

An allylic oxidation method for Delta(5)-steroids using TBHP as oxidant with a 2-quinoxalinol salen Cu(II) complex as catalyst is reported. A variety of Delta(5)-steroidal substrates are selectively oxidized to the corresponding enones. Excellent yields are achieved (up to 99% under optimized conditions) while significantly reducing reaction times required as compared to other current methods. PMID:20141120

Li, Yuancheng; Wu, Xianghong; Lee, Tae Bum; Isbell, Eleanor K; Parish, Edward J; Gorden, Anne E V

2010-03-01

354

EFFECT OF BTEX ON THE DEGRADATION OF MTBE AND TBA BY MIXED BACTERIAL CONSORTIUM  

EPA Science Inventory

Methyl tert -butyl ether (MTBE) contamination in groundwater often coexists with benzene, toluene, ethylbenzene, and xylene (BTEX) near the source of the plume. Tertiary butyl alcohol (TBA) is a prevalent intermediate of MTBE degradation. Therefore, there is a significant p...

355

Kinetics of the heterogeneously catalyzed formation of tert-amyl ethyl ether  

SciTech Connect

In this work, the kinetics and equilibrium of the heterogeneously catalyzed liquid-phase formation of tert-amyl ethyl ether (TAEE) were studied. The catalyst used was a commercial sulfonic acid ion-exchange resin (Amberlyst 16W). The experiments were carried out in a continuous stirred-tank reactor, measuring stationary reaction rates. The measured reaction rates were fitted to three kinetic models; homogeneous, Eley-Rideal type, and Langmuir-Hinshelwood type. Of these, the Langmuir-Hinshelwood type model described the experimental results best. This model is based on single-site adsorption of every component, with the surface reaction being the rate-limiting step. The activation energies for the formation of tert-amyl ethyl ether from 2-methyl-1-butene were 90 and from 2-methyl-2-butene 108 kJ/mol. For the isomerization of 2-methyl-1-butene to 2-methyl-2-butene, an activation energy of 82 kJ/mol was obtained.

Linnekoski, J.A.; Krause, A.O. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Industrial Chemistry] [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Industrial Chemistry; Rihko, L.K. [Neste Oy, Porvoo (Finland). Technology Center] [Neste Oy, Porvoo (Finland). Technology Center

1997-02-01

356

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

PubMed Central

We studied customer exposure during refueling by collecting air samples from customers' breathing zone. The measurements were carried out during 4 days in summer 1996 at two Finnish self-service gasoline stations with "stage I" vapor recovery systems. The 95-RON (research octane number) gasoline contained approximately 2.7% methyl tert-butyl ether (MTBE), approximately 8.5% tert-amyl methyl ether (TAME), approximately 3.2% C6 alkyl methyl ethers (C6 AMEs), and 0.75% benzene. The individual exposure concentrations showed a wide log-normal distribution, with low exposures being the most frequent. In over 90% of the samples, the concentration of MTBE was higher (range <0.02-51 mg/m3) than that of TAME. The MTBE values were well below the short-term (15 min) threshold limits set for occupational exposure (250-360 mg/m3). At station A, the geometric mean concentrations in individual samples were 3.9 mg/m3 MTBE and 2. 2 mg/m3 TAME. The corresponding values at station B were 2.4 and 1.7 mg/m3, respectively. The average refueling (sampling) time was 63 sec at station A and 74 sec at station B. No statistically significant difference was observed in customer exposures between the two service stations. The overall geometric means (n = 167) for an adjusted 1-min refueling time were 3.3 mg/m3 MTBE and 1.9 mg/m3 TAME. Each day an integrated breathing zone sample was also collected, corresponding to an arithmetic mean of 20-21 refuelings. The overall arithmetic mean concentrations in the integrated samples (n = 8) were 0.90 mg/m3 for benzene and 0.56 mg/m3 for C6 AMEs calculated as a group. Mean MTBE concentrations in ambient air (a stationary point in the middle of the pump island) were 0.16 mg/m3 for station A and 0.07 mg/m3 for station B. The mean ambient concentrations of TAME, C6 AMEs, and benzene were 0.031 mg/m3, approximately 0.005 mg/m3, and approximately 0.01 mg/m3, respectively, at both stations. The mean wind speed was 1.4 m/sec and mean air temperature was 21 degreesC. Of the gasoline refueled during the study, 75% was 95 grade and 25% was 98/99 grade, with an oxygenate (MTBE) content of 12.2%. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:9924009

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

1999-01-01

357

Bidentate urea derivatives of p-tert-butyldihomooxacalix[4]arene: neutral receptors for anion complexation.  

PubMed

Three new bidentate ureidodihomooxacalix[4]arene derivatives (phenyl 5a, n-propyl 5b, and tert-butyl 5c) were synthesized in four steps from the parent compound p-tert-butyldihomooxacalix[4]arene and obtained in the cone conformation, as shown by NMR studies. The binding ability of these neutral receptors toward spherical, linear, trigonal planar, and tetrahedrical anions was assessed by (1)H NMR and UV-vis titrations. The structures and complexation energies of some complexes were also studied by DFT methods. The data showed that the association constants are strongly dependent on the nature of the substituent (aryl/alkyl) at the urea moiety. In general, for all the receptors, the association constants decrease with decrease of anion basicity. Ph-urea 5a is the best anion receptor, showing the strongest complexation for F(-) (log K(assoc) = 3.10 in CDCl3) and also high binding affinity for the carboxylates AcO(-) and BzO(-). Similar results were obtained by UV-vis studies and were also corroborated by DFT calculations. PMID:24358937

Marcos, Paula M; Teixeira, Filipa A; Segurado, Manuel A P; Ascenso, José R; Bernardino, Raul J; Michel, Sylvia; Hubscher-Bruder, Véronique

2014-01-17

358

Paradoxical cytotoxicity of tert-butylhydroquinone in vitro: What kills the untreated cells?  

PubMed

At high concentrations, tert-butylhydroquinone (tBHQ), a phenolic antioxidant frequently used as a food preservative, exerts cytotoxic effects, which are closely linked to its ability to form reactive oxygen species as a consequence of redox cycling processes. Here we describe that treatment of murine 3T3 cells with 300 ?g/ml of tBHQ in 96-well culture plates induces the death of untreated cells in neighboring wells on the same plate. The mechanisms underlying that effect were investigated. Death of the seemingly untreated neighboring cells was caused by the more toxic and volatile tBHQ oxidation product tert-butyl-p-benzoquinone (tBQ) present at up to 3 ?g/ml in the untreated neighboring wells. tBQ was formed from tBHQ in a non-enzymatic process involving copper ions and oxygen. The unexpected perturbation of cytotoxicity testing following treatment with tBHQ by its volatile metabolite tBQ shows that not only metabolic processes but also non-enzymatic mechanisms have to be considered as important parameters for in vitro assays. Furthermore, our data show that even cells several wells away from the treated wells do not necessarily constitute proper "untreated" controls when cells are treated with the frequently used compound tBHQ. This might lead to an underestimation of the effects observed on the Nrf2 signaling pathway, where tBHQ is frequently used as an inductor in vitro. PMID:22466069

Braeuning, Albert; Vetter, Silvia; Orsetti, Silvia; Schwarz, Michael

2012-09-01

359

In situ formation of silver nanoparticles in PMMA via reduction of silver ions by butylated hydroxytoluene  

Microsoft Academic Search

Silver nanoparticles (Ag NPs) were efficiently generated by in situ reduction of silver ions via butylated hydroxytoluene\\u000a (BHT), in poly(methyl methacrylate). The characterization of Ag\\/PMMA by TEM, SEM, XRD, and FTIR indicated that Ag NPs with\\u000a a face center cubic (fcc) crystal structure and a mean diameter of about 30 nm were dispersed in PMMA matrix with a relatively\\u000a uniform distribution.

M. Z. Kassaee; M. Mohammadkhani; A. Akhavan; R. Mohammadi

2011-01-01

360

The Rotational Spectrum of Tertiary-Butyl Alcohol  

NASA Astrophysics Data System (ADS)

Tertiary-butyl alcohol is a nearly spherical rotor for which the internal rotation axis of the t-butyl group is close to the c molecular axis in the ac plane. Methyl group torsional spittings are not observed in the ground state. Its 8 to 40 GHz rotational spectrum was reported at this meeting by Valenzuela and Woods in 1974 and in more detail in 1975. The parameters derived at that time from a fit to the E states with J,K? 20 have provided the basis for extending the measurements to > 500 GHz. The combined data set extends to J,K > 50 and is fit with the program SPFIT using a common set of parameters for both the A and E states. The general features of the spectrum and the fitting procedure will be described. The resulting molecular constants and their interpretation will be discussed. E.A. Valenzuela, and R. C. Woods, Abstract MF6, International Symposium on Molecular Spectroscopy, Columbus, OH, 1974 E.A. Valenzuela, and R. C. Woods, Abstract RG15, International Symposium on Molecular Spectroscopy, Columbus, OH, 1975 E.A. Valenzuela, Ph.D. Thesis, University of Wisconsin-Madison, 1975. H. M. Pickett, J. Mol. Spectrosc. 148 (1991) 271-377.

Cohen, E. A.; Drouin, B. J.; Valenzuela, E. A.; Woods, R. C.; Caminati, W.; Maris, A.; Melandri, S.

2009-06-01

361

Synthesis and evaluation of novel 2-butyl-4-chloro-1-methylimidazole embedded chalcones and pyrazoles as angiotensin converting enzyme (ACE) inhibitors.  

PubMed

A series of novel 2-butyl-4-chloro-1-methylimidazole embedded aryl and heteroaryl derived chalcones and pyrazoles were synthesized and evaluated for their angiotensin converting enzyme (ACE) inhibitory activity. The condensation of 2-butyl-4-chloro-1-methylimidazole-5-carboxaldehyde with various aryl and heteroaryl methyl ketones in the presence of 10% aqueous NaOH in methanol proceeded efficiently to give the respective chalcones in very good yields. Further, the reaction of chalcones with hydrazine hydrate in acetic acid gave substituted pyrazole analogues. Screening all 36 new compounds using ACE inhibition assay, resulted chalcones with better ACE inhibitory activity compared to the respective pyrazole analogues. Among the chalcones 4a-r, three compounds, (E)-3-(2-butyl-4-chloro-1-methyl-1H-imidazol-5-yl)-1-(5-chlorothiophen-2-yl)prop-2-enone 4i, (E)-3-(2-butyl-4-chloro-1-methyl-1H-imidazol-5-yl)-1-(1H-pyrrol-2-yl)prop-2-enone 4l, (E)-3-(2-butyl-4-chloro-1-methyl-1H-imidazol-5-yl)-1-(dibenzo[b,d] thiophen-2-yl)prop-2-enone 4q were resulted as most active ACE inhibitors with IC(50) of 3.60 ?M, 2.24 ?M, and 2.68 ?M, respectively. PMID:21782455

Kantevari, Srinivas; Addla, Dinesh; Bagul, Pankaj K; Sridhar, Balasubramanian; Banerjee, Sanjay K

2011-08-15

362

A novel method to quantify local CpG methylation density by regional methylation elongation assay on microarray  

PubMed Central

Background DNA methylation based techniques are important tools in both clinical diagnostics and therapeutics. But most of these methods only analyze a few CpG sites in a target region. Indeed, difference of site-specific methylation may also lead to a change of methylation density in many cases, and it has been found that the density of methylation is more important than methylation of single CpG site for gene silencing. Results We have developed a novel approach for quantitative analysis of CpG methylation density on the basis of microarray-based hybridization and incorporation of Cy5-dCTP into the Cy3 labeled target DNA by using Taq DNA Polymerase on microarray. The quantification is achieved by measuring Cy5/Cy3 signal ratio which is proportional to methylation density. This methylation-sensitive technique, termed RMEAM (regional methylation elongation assay on microarray), provides several advantages over existing methods used for methylation analysis. It can determine an exact methylation density of the given region, and has potential of high throughput. We demonstrate a use of this method in determining the methylation density of the promoter region of the tumor-related gene MLH1, TERT and MGMT in colorectal carcinoma patients. Conclusion This technique allows for quantitative analysis of regional methylation density, which is the representative of all allelic methylation patterns in the sample. The results show that this technique has the characteristics of simplicity, rapidness, specificity and high-throughput. PMID:18237388

Zhang, Dingdong; Wang, Yan; Bai, Yunfei; Ge, Qinyu; Qiao, Yingjuan; Luo, Junfeng; Jia, Chao; Lu, Zuhong

2008-01-01

363

Solubility and Excess Molar Properties of 1,3-Dimethylimidazolium Methylsulfate, or 1Butyl3-Methylimidazolium Methylsulfate, or 1Butyl3-Methylimidazolium Octylsulfate Ionic Liquids with n Alkanes and Alcohols: Analysis in Terms of the PFP and FBT Models 1  

Microsoft Academic Search

The solubility of 1-butyl-3-methylimidazolium octylsulfate, [BMIM][OcSO4], has been determined in hydrocarbon (n-hexane, n-heptane, n-octane or n-decane) solutions and alcohol (methanol, 1-butanol, 1-hexanol, 1-octanol or 1-decanol) solutions. Densities and excess molar\\u000a volumes, V\\u000a E\\u000a m, have been determined for 1-methyl-3-methylimidazolium methylsulfate, [MMIM][CH3SO4], solutions with an alcohol (methanol, ethanol or 1-butanol) and with water; for 1-butyl-3-methylimidazolium methylsulfate,\\u000a [BMIM][CH3SO4], with an alcohol (methanol,

U. Doma?ska; A. Pobudkowska; A. Wi?niewska

2006-01-01

364

Altered Histone Mark Deposition and DNA Methylation at Homeobox Genes in Human Oral Squamous Cell Carcinoma Cells  

PubMed Central

We recently reported a role of Polycomb repressive complex 2 (PRC2) and PRC2 trimethylation of histone 3 lysine 27 (H3K27me3) in the regulation of homeobox (HOX) (Marcinkiewicz and Gudas, 2013) gene transcript levels in human oral keratinocytes (OKF6-TERT1R) and tongue squamous cell carcinoma (SCC) cells. Here, we assessed both the levels of various histone modifications at a subset of homeobox genes and genome wide DNA methylation patterns in OKF6-TERT1R and SCC-9 cells by using ERRBS (enhanced reduced representation bisulfite sequencing). We detected the H3K9me3 mark at HOXB7, HOXC10, HOXC13 and HOXD8 at levels higher in OKF6-TERT1R than in SCC-9 cells; at IRX1 and SIX2 the H3K9me3 levels were conversely higher in SCC-9 than in OKF6-TERT1R. The H3K79me3 mark was detectable only at IRX1 in OKF6-TERT1R and at IRX4 in SCC-9 cells. The levels of H3K4me3 and H3K36me3 marks correlate with the transcript levels of the assessed homeobox genes in both OKF6-TERT1R and SCC-9. We detected generally lower CpG methylation levels on DNA in SCC-9 cells at annotated genomic regions which were differentially methylated between OKF6-TERT1R and SCC-9 cells; however, some genomic regions, including the HOX gene clusters, showed DNA methylation at higher levels in SCC-9 than OKF6-TERT1R. Thus, both altered histone modification patterns and changes in DNA methylation are associated with dysregulation of homeobox gene expression in human oral cavity SCC cells, and this dysregulation potentially plays a role in the neoplastic phenotype of oral keratinocytes. PMID:24519855

Marcinkiewicz, Katarzyna M.; Gudas, Lorraine J.

2014-01-01

365

Axial chirality control during Suzuki-Miyaura cross-coupling reactions: the tert-butylsulfinyl group as an efficient chiral auxiliary.  

PubMed

An efficient route to a new family of axially chiral biaryl ligands by a Suzuki-Miyaura cross-coupling reaction between ortho,ortho'-disubstituted aryl iodides bearing in ortho position a tert-butyl or p-tolylsulfinyl group and ortho-substituted phenyl boronic acids or esters is described. The comparison between the t-BuSO and p-TolSO groups as chiral controllers is reported. The modularity of the approach is demonstrated by the preparation of a variety of enantiopure axially chiral mixed S/N and S/P ligands. PMID:19839613

Colobert, Françoise; Valdivia, Victoria; Choppin, Sabine; Leroux, Frédéric R; Fernández, Inmaculada; Alvarez, Eleuterio; Khiar, Noureddine

2009-11-19

366

P. berghei Telomerase Subunit TERT is Essential for Parasite Survival  

PubMed Central

Telomeres define the ends of chromosomes protecting eukaryotic cells from chromosome instability and eventual cell death. The complex regulation of telomeres involves various proteins including telomerase, which is a specialized ribonucleoprotein responsible for telomere maintenance. Telomeres of chromosomes of malaria parasites are kept at a constant length during blood stage proliferation. The 7-bp telomere repeat sequence is universal across different Plasmodium species (GGGTTT/CA), though the average telomere length varies. The catalytic subunit of telomerase, telomerase reverse transcriptase (TERT), is present in all sequenced Plasmodium species and is approximately three times larger than other eukaryotic TERTs. The Plasmodium RNA component of TERT has recently been identified in silico. A strategy to delete the gene encoding TERT via double cross-over (DXO) homologous recombination was undertaken to study the telomerase function in P. berghei. Expression of both TERT and the RNA component (TR) in P. berghei blood stages was analysed by Western blotting and Northern analysis. Average telomere length was measured in several Plasmodium species using Telomere Restriction Fragment (TRF) analysis. TERT and TR were detected in blood stages and an average telomere length of ?950 bp established. Deletion of the tert gene was performed using standard transfection methodologies and we show the presence of tert? mutants in the transfected parasite populations. Cloning of tert- mutants has been attempted multiple times without success. Thorough analysis of the transfected parasite populations and the parasite obtained from extensive parasite cloning from these populations provide evidence for a so called delayed death phenotype as observed in different organisms lacking TERT. The findings indicate that TERT is essential for P. berghei cell survival. The study extends our current knowledge on telomere biology in malaria parasites and validates further investigations to identify telomerase inhibitors to induce parasite cell death. PMID:25275500

Religa, Agnieszka A.; Ramesar, Jai; Janse, Chris J.; Scherf, Artur; Waters, Andrew P.

2014-01-01

367

Isotope effects and the temperature dependences of the hyperfine coupling constants of muoniated sec-butyl radicals in condensed phases.  

PubMed

Reported here is the first ?SR study of the muon (A(?)) and proton (A(p)) ?-hyperfine coupling constants (Hfcc) of muoniated sec-butyl radicals, formed by muonium (Mu) addition to 1-butene and to cis- and trans-2-butene. The data are compared with in vacuo spin-unrestricted MP2 and hybrid DFT/B3YLP calculations reported in the previous paper (I), which played an important part in the interpretation of the data. The T-dependences of both the (reduced) muon, A(?)?(T), and proton, A(p)(T), Hfcc are surprisingly well explained by a simple model, in which the calculated Hfcc from paper I at energy minima of 0 and near ±120° are thermally averaged, assuming an energy dependence given by a basic 2-fold torsional potential. Fitted torsional barriers to A(?)?(T) from this model are similar (~3 kJ/mol) for all muoniated butyl radicals, suggesting that these are dominated by ZPE effects arising from the C?Mu bond, but for A(p)(T) exhibit wide variations depending on environment. For the cis- and trans-2-butyl radicals formed from 2-butene, A(?)?(T) exhibits clear discontinuities at bulk butene melting points, evidence for molecular interactions enhancing these muon Hfcc in the environment of the solid state, similar to that found in earlier reports for muoniated tert-butyl. In contrast, for Mu?sec-butyl formed from 1-butene, there is no such discontinuity. The muon hfcc for the trans-2-butyl radical are seemingly very well predicted by B3LYP calculations in the solid phase, but for sec-butyl from 1-butene, showing the absence of further interactions, much better agreement is found with the MP2 calculations across the whole temperature range. Examples of large proton Hfcc near 0 K are also reported, due to eclipsed C?H bonds, in like manner to C?Mu, which then also exhibit clear discontinuities in A(p)(T) at bulk melting points. The data suggest that the good agreement found between theory and experiment from the B3LYP calculations for eclipsed bonds in the solid phase may be fortuitous. For the staggered protons of the sec-butyl radicals formed, no discontinuities are seen at all in A(p)(T), also demonstrating no further effects of molecular interactions on these particular proton Hfcc. PMID:21395224

Fleming, Donald G; Bridges, Michael D; Arseneau, Donald J; Chen, Ya Kun; Wang, Yan Alexander

2011-04-01

368

Enantioselective Carbonyl Allylation, Crotylation and tert-Prenylation of Furan Methanols and Furfurals via Iridium Catalyzed Transfer Hydrogenation  

PubMed Central

5-Substituted-2-furan methanols 1a–1c are subject to enantioselective carbonyl allylation, crotylation and tert-prenylation upon exposure to allyl acetate, ?-methyl allyl acetate or 1,1,-dimethylallene in the presence of an ortho-cyclometallated iridium catalyst modified by (R)-Cl,MeO-BIPHEP, (R)-C3 -TUNEPHOS and (R)-C3-SEGPHOS, respectively. In the presence of isopropanol, but under otherwise identical conditions, the corresponding substituted furfurals 2a–2c are converted to identical products of allylation, crotylation and tert-prenylation. Optically enriched products carbonyl allylation, crotylation and reverse prenylation 3b, 4b and 5b were subjected to Achmatowicz rearrangement to furnish the corresponding ?-hydroxy-?-pyrones 6a–6c, respectively, with negligible erosion of enantiomeric excess. PMID:20131774

Bechem, Benjamin; Patman, Ryan L.; Hashmi, Stephen; Krische, Michael J.

2010-01-01

369

C-methylated dihydrochalcones from Myrica gale L: effects as antioxidants and as scavengers of 1,1-diphenyl-2-picrylhydrazyl.  

PubMed

A number of isomeric or chemically closely related C-methylated dihydrochalcones, which is a rare substance class, has been isolated from the fruit exudate of Myrica gale L. and subjected to the following tests: 1) inhibition of lipid peroxidation induced by tert-butyl hydroperoxide or bromotrichloromethane in isolated rat hepatocytes, 2) inhibition of peroxidation induced by Fe2+ ions in a cell free system with linolenic acid as substrate, 3) scavenging activity against the diphenylpicrylhydrazyl radical, and 4) inhibition of enzymatic lipid peroxidation in linoleic acid by soybean 15-lipoxy-genase. One of the compounds (myrigalone B = MyB; 2',6'-dihydroxy-4'-methoxy-3',5'-dimethyldihydrochalcone) showed good activity in all tests whereas the others were inactive or slightly active, except that myrigalone A (MyA; 3-(1-oxo-3-phenylpropyl)-1,1,5-trimethylcyclohexane-2,4,6-trione)) like its synthetic analogue MyA* (the polar part of MyA) was nearly as active as MyB in 4). The antioxidant properties of MyB are probably due to its radical scavenging activity and may be related to its conformation, which differs from that of the other compounds. PMID:8822045

Malterud, K E; Diep, O H; Sund, R B

1996-02-01

370

Synthesis and spectral characterization of methyl 9(10)-dialkylphosphonostearates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Dimethyl, diethyl, and di-n-butyl phosphites were reacted with methyl or ethyl oleates using thermally initiated radical reactions. Reactions were conducted with or without the presence of the lauroyl peroxide initiator. The reactions gave a mixture of isomers with the phosphorous attached at the 9 ...

371

Arco gets ETBE boost from excise tax break  

SciTech Connect

Arco Chemical of Newtown Square, PA, has been extended an excise tax exemption for using ethyl tert-butyl ether (ETBE) in gasoline blends. An exemption is already in force for ethanol. The tax break may still not make ETBE competitive with methanol-based methyl tert-butyl ether (MTBE).

Lucas, A.

1994-10-12

372

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

EPA Science Inventory

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

373

Influence of Polar Components in the Dimerization of Isobutene  

Microsoft Academic Search

Isooctane is seen as a potential replacement for methyl tert-butyl ether (MTBE) in gasoline. Isooctane can be produced via the indirect alkylation route in two steps. Isobutene is first dimerized to isooctenes, which are then further hydrogenated to isooctane. In the dimerization a polar component is used to enhance the selectivity for diisobutenes. In this study the effects of tert-butyl

M. L. Honkela; A. O. I. Krause

2003-01-01

374

Cytochrome P-450-catalyzed rearrangement of a peroxyquinol derived from butylated hydroxytoluene. Involvement of radical and cationic intermediates.  

PubMed

The p-peroxyquinol derived from butylated hydroxytoluene, 2,6-di-t-butyl-4-hydroperoxy-4-methyl-2,5-cyclohexadienone, was degraded by the ferric form of rat liver cytochrome P-450, and the resulting products and their mechanisms of formation were investigated. Quinoxy radical BO. from homolysis of the O-O bond reacted by competing pathways; beta-scission yielded 2,6-di-t-butyl-p-benzoquinone, and rearrangement with ring-expansion produced an oxacycloheptadienone free radical (X(.)). This rearranged radical was stabilized by the captodative effect that facilitated competitive interactions with the P-450 iron-oxo complexes formed during O-O bond scission. Approximately 15% of X(.) was captured by oxygen rebound with a hydroxyl radical from the P-450 complex (FeOH)3+ to form a hemiketal, that led to the ring-contracted product 2,5-di-t-butyl-5-(2'-oxopropyl)-4-oxa-2-cyclopentenone by spontaneous rearrangement. The major fraction of X(.), however, underwent electron transfer oxidation to form the corresponding cation. Hydration of this cation produced the ring-contracted product, and proton elimination (or, alternatively, direct H(.) removal from X(.) led to the product 2,7-di-t-butyl-4-methylene-5-oxacyclohepta-2,6-dienone. The findings indicate that cytochrome P-450 intermediate complexes are mainly responsible for oxidation of X(.). The results complement our previous study with 2,6-di-t-butyl-4-hydroperoxy-4-methyl-2,5-cyclohexadienone (Thompson, J. A., and Wand, M. D. (1985) J. Biol. Chem. 260, 10637-10644), demonstrating competitive heterolytic and homolytic mechanisms of O-O bond cleavage, and competitive rebound and oxidation processes when a substrate-derived radical interacts with P-450 complexes. PMID:3021725

Wand, M D; Thompson, J A

1986-10-25

375

Accelerated aging of EPDM and butyl elastomers  

SciTech Connect

This study was composed of three parts: a post cure study to optimize final properties of an ethylene-propylene-diene (EPDM) formulation, an accelerated aging study to compare the stress relaxation behavior of a butyl and an EPDM elastomer under compression, and a cursory evaluation of a new 70 Shore A EPDM. The optimum postcure for the EPDM was found to be 2 to 4 hours at 182{degrees}C in a vacuum. The EPDM was also shown to have superior aging characteristics compared to the butyl and is recommended for use instead of the butyl material. The physical properties for new 70 Shore A EPDM are satisfactory, and the stress relaxation behavior was only slightly inferior to the other EPDM.

Wilson, M.H.

1996-06-01

376

40 CFR 180.232 - Butylate; tolerances for residues.  

Code of Federal Regulations, 2013 CFR

...Tolerances § 180.232 Butylate; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide butylate, including its metabolites and degradates, in or on the commodities in the table in this paragraph....

2013-07-01

377

The Millimeterwave Spectrum of n-BUTYL Cyanide  

NASA Astrophysics Data System (ADS)

The rotational spectrum of n-butyl cyanide (C_4H_9CN) was measured between 75 and 130 GHz using a novel all-solid-state spectrometer with a total absorption path of 44 m. In the course of the analysis of the spectrum, about 3000 transitions were assigned and a full set of quartic centrifugal distortion parameters with some sextic and octic terms could be determined for each of the three known conformers (anti-anti, anti-gauche(methyl end) and gauche(CN end)-anti). The work was motivated by the fact that n-butyl cyanide is likely to be found in interstellar hot core environments. This is indicated by the discovery of n-propyl cyanide (C_3H_7CN), the next smaller alkyl cyanide, in the ISM. The increased accuracy of the model, which will be additionally extended by future laboratory measurements around 200 GHz, may now be employed for a prediction of the spectrum up to 300 GHz with a feasible uncertainty for astronomic line surveys. Furthermore, there are two less abundant conformers, cis-gauche-gauche and trans-gauche-gauche, which have not yet been detected in the rotational spectrum. Due to the increased sensitivity of the new spectrometer, it seems possible now for the first time to identify their sectroscopic fingerprints in the recorded data. A. Belloche, R. T. Garrod, H. S. P.Müller, K. M. Menten, C. Comito, and P. Schilke, Astronomy & Astrophysics 499, 215 (2009) R. K. Bohn, J. L. Pardus, J. August, T. Brupbacher, W. Jäger, J. Mol. Struct. 413-414, 293 (1997)

Ordu, Matthias H.; Müller, Holger S. P.; Lewen, Frank; Schlemmer, Stephan; Nez, Marc Nu; Walters, Adam

2011-06-01

378

An Improved Model for the hTERT Promoter Quadruplex  

PubMed Central

Mutations occur at four specific sites in the hTERT promoter in >75% of glioblastomas and melanomas, but the mechanism by which the mutations affect gene expression remains unexplained. We report biophysical computational studies that show that the hTERT promoter sequence forms a novel G-quadruplex structure consisting of three contiguous, stacked parallel quadruplexes. The reported hTERT mutations map to the central quadruplex within this structure, and lead to an alteration of its hydrodynamic properties and stability. PMID:25526084

Chaires, Jonathan B.; Trent, John O.; Gray, Robert D.; Dean, William L.; Buscaglia, Robert; Thomas, Shelia D.; Miller, Donald M.

2014-01-01

379

Synthesis, Characterization, Reactivity Ratio and Photo Crosslinking Properties of the Copolymer of 4-Cinnamoyl Phenyl Methacrylate with Butyl Methacrylate  

Microsoft Academic Search

Copolymers of 4-cinnamoyl phenyl methacrylate (4-CPMA) and n-butyl methacrylate (BMA) were prepared in a methyl ethyl ketone (MEK) solution with benzoyl peroxide (BPO) as an initiator at 70°C. They were characterized with UV, IR, H-NMR, C-NMR, TGA, DSC and gel permeation chromatography. Copolymers were prepared by using different feed ratio of monomers. The monomer reactivity ratios determined by the method

Govindasamy Kumar; Kathavarayan Subramanian

2010-01-01

380

Effect of Polymerization Conditions on the Rheological Behavior of Acrylic Polymer Solutions with 1Butyl3-Methylimidazolium Tetrafluoroborate as Solvent  

Microsoft Academic Search

Rheological behavior of concentrated acrylic polymer\\/1-butyl-3-methylimidazolium tetrafluoroborate (PAN\\/[BMIM]BF4) solutions, which were prepared by the radical copolymerization of acrylonitrile (AN) and methylate (MA) in ionic liquid, is reported. The effect of copolymerization conditions on the rheological behavior of the solutions is discussed in detail. The shear viscosity and structural viscosity index, ??, increases while the non-Newtonian index, n, decreases with increasing

Y. Zhang; X. Tu; D. Li; H. Wang

2008-01-01

381

Photoelectron-Photofragment Coincidence Spectroscopy of Tert-Butoxide and the Carbanion Isomer  

NASA Astrophysics Data System (ADS)

The photodetachment dynamics of the C4H9O- anion, produced by proton abstraction from tert-butanol has been studied using a cryogenically-cooled linear electrostatic ion trap to store a fast ion beam. The ion trap is coupled with a Photoelectron-Photofragment Coincidence spectrometer for a kinematically complete experiment in which dissociative neutral intermediates of known internal energy are created by photodetachment of a stable molecular anion. By collecting all resultant neutral fragments from the dissociation event in coincidence with the detached electron using time- and position-sensitive detectors, the correlated momenta and energies of all products can be determined. At 388, 537, and 600nm, both stable and dissociative photodeatchment processes of C4H9O- are observed. The stable channel is consistent with previous photodetachment spectrum from {tert}-butoxide anion as well as a Franck-Condon simulation of the photoelectron spectrum. The dissociative channel is consistent with a methyl loss from an alkylhydroxy radical. Results will be analyzed in the context of calculations employing MP2/6-311++G(d,p) and CBSQ level of theory. C. J. Johnson, B. B. Shen, B. L. J. Poad, and R. E. Continetti, Rev. Sci. Instrum., 82, 105105 (2011) T. M. Ramond, G. E. Davico, R. L. Schwartz, W. C. Lineberger, J. Chem. Phys., 112, 1158 (2000)

Shen, Ben B.; Poad, Berwyck L. J.; Ray, Amelia W.; Continetti, Robert E.

2012-06-01

382

Determining the fatty acid composition in plasma and tissues as fatty acid methyl esters using gas chromatography – a comparison of different derivatization and extraction procedures.  

PubMed

Analysis of the fatty acid (FA) composition in biological samples is commonly carried out using gas liquid chromatography (GC) after transesterification to volatile FA methyl esters (FAME). We compared the efficacy of six frequently used protocols for derivatization of different lipid classes as well as for plasma and tissue samples. Transesterification with trimethylsulfonium hydroxide (TMSH) led to insufficient derivatization efficacies for polyunsaturated FAs (PUFA, <50%). Derivatization in presence of potassium hydroxide (KOH) failed at derivatizing free FAs (FFAs). Boron trifluoride (BF3) 7% in hexane/MeOH (1:1) was insufficient for the transesterification of cholesterol ester (CE) as well as triacylglycerols (TGs). In contrast, methanolic hydrochloric acid (HCl) as well as a combination of BF3 with methanolic sodium hydroxide (NaOH+BF3) were suitable for the derivatization of FFAs, polar lipids, TGs, and CEs (derivatization rate >80% for all tested lipids). Regarding plasma samples, all methods led to an overall similar relative FA pattern. However, significant differences were observed, for example, for the relative amount of EPA+DHA (n3-index). Absolute FA plasma concentrations differed considerably among the methods, with low yields for KOH and BF3. We also demonstrate that lipid extraction with tert-butyl methyl ether/methanol (MTBE/MeOH) is as efficient as the classical method according to Bligh and Dyer, making it possible to replace (environmentally) toxic chloroform.We conclude that HCl-catalyzed derivatization in combination with MeOH/MTBE extraction is the most appropriate among the methods tested for the analysis of FA concentrations and FA pattern in small biological samples. A detailed protocol for the analysis of plasma and tissues is included in this article. PMID:25458899

Ostermann, Annika I; Müller, Maike; Willenberg, Ina; Schebb, Nils Helge

2014-12-01

383

Increasing the octane number of gasoline using functionalized carbon nanotubes  

Microsoft Academic Search

The octane number is one of the characteristics of spark-ignition fuels such as gasoline. Octane number of fuels can be improved by addition of oxygenates such as ethanol, MTBE (methyl tert-butyl ether), TBF (tertiary butyl formate) and TBA (tertiary butyl alcohol) as well as their blends with gasoline that reduce the cost impact of fuels. Carbon nanotubes (CNTs) are as

Sara Safari Kish; Alimorad Rashidi; Hamid Reza Aghabozorg; Leila Moradi

2010-01-01

384

Mitochondria-targeted peptide prevents mitochondrial depolarization and apoptosis induced by tert-butyl hydroperoxide in neuronal cell lines  

Microsoft Academic Search

Oxidative stress and mitochondrial oxidative damage have been implicated in aging and many common diseases. Mitochondria are a primary source of reactive oxygen species (ROS) in the cell, and are particularly susceptible to oxidative damage. Oxidative damage to mitochondria results in mitochondrial permeability transition (MPT), mitochondrial depolarization, further ROS production, swelling, and release of cytochrome c (cyt c). Cytosolic cyt

Kesheng Zhao; Guoxiong Luo; Serena Giannelli; Hazel H. Szeto

2005-01-01

385

3-tert-Butyl-2-oxo-1-oxaspiro­[4.5]dec-3-en-4-yl 4-chloro­benzoate  

PubMed Central

The title tetronic acid derivative, C20H23ClO4, which is a spiro­diclofen analogue, has two crystallographically independent mol­ecules in the asymmetric unit (Z? = 2). The cyclo­hexane rings in the respective mol­ecules A and B adopt chair conformations [four C atoms are planar with mean deviations of 0.013?(2) and 0.001?(2)?Å, and the flap positions deviate by 0.653?(4) and ?0.663?(3)?Å (mol­ecule A) and 0.642?(4) and ?0.643?(5)?Å (mol­ecule B) from the plane]. The furan ring makes dihedral angles of 86.9?(1) (mol­ecule A) and 85.4?(1)° (mol­ecule B) with the respective benzene rings. PMID:22058828

Wang, Zong-cheng; Cheng, Jing-li; Zhao, Jin-hao; Yu, Feng

2011-01-01

386

Influence of Ultrasonic Frequency on Swan Band Sonoluminescence and Sonochemical Activity in Aqueous tert-Butyl Alcohol Solutions.  

PubMed

The multibubble sonoluminescence (MBSL) spectra of t-BuOH aqueous solutions submitted to power ultrasound at 20, 204, 362, and 613 kHz show emissions for the ?? = -1 to ?? = +2 vibrational sequences of C2* Swan system (d(3)?g ? a(3)?u). The ??=+2 emission overlaps with the CH(A-X) emission band. The maximal Swan band emission is observed when the MBSL of water itself is almost completely quenched. In general, MBSL is more intense at high-frequency compared to 20 kHz ultrasound. However, in the presence of Xe, the MBSL of C2* at 20 kHz is so bright that it can be seen by the unaided eye as a blue glow in the close vicinity of the ultrasonic tip. The intensity of the C2* band emission exhibits a maximum vs t-BuOH concentration: 0.1-0.2 M at 20 kHz and (1-8) × 10(-3) M at high-frequency ultrasound. Such a huge difference is attributed to a much smaller bubble size at high ultrasonic frequency or, in other words, to a much higher bubble surface/volume ratio providing more efficient saturation of the bubble interior with t-BuOH vapors and to the fact that high frequency bubbles remain active for many more cycles than 20 kHz ones, thus accumulating more hydrocarbon decomposition products. Simulation of the emission spectra using Specair software demonstrated the absence of thermal equilibrium for C2* radicals (Tv > Tr), where Tv and Tr are the vibrational and the rotational temperature, respectively. In Ar, Tv decreases with increasing t-BuOH concentration reaching a steady value in the concentration domain that corresponds to C2* emission maximum intensity. In the presence of Xe an extremely high Tv is obtained, which is explained by the relatively low ionization potential of Xe providing a higher electron temperature of nonequilibrium plasma generated during bubble collapse. Analysis of the gaseous products of t-BuOH sonolysis reveals a significant sonochemical activity even at high t-BuOH concentration when MBSL is totally quenched, indicating that drastic conditions could be produced also within nonsonoluminescing cavitation bubbles. PMID:25494806

Pflieger, Rachel; Ndiaye, Abdoul Aziz; Chave, Tony; Nikitenko, Sergey I

2015-01-01

387

Diethyl 2,2-bis­(3,5-di-tert-butyl-4-hy­droxy­benz­yl)malonate  

PubMed Central

The title mol­ecule, C37H56O6, possesses twofold symmetry, with the twofold axis passing through the quaternary C atom. In the crystal, neighbouring mol­ecules are linked via O—H?O hydrogen bonds involving the phenol OH group and the carbonyl O atom, forming chains propagating in [101]. Within these chains, rings are formed with an R 2 2(20) motif. There are also C—H?O inter­actions present within the rings. PMID:22347059

Zeng, Tao; Hou, Yu-Ping; Ren, Wan-Zhong; Xu, Wen-You

2012-01-01

388

4,5-Dibromo-2,7-di-tert-butyl-9,9-dimethyl-9H-thioxanthene.  

PubMed

In the title compound, C(23)H(28)Br(2)S, the thioxanthene unit is twisted, showing a dihedral angle of 29.3?(5)° between the benzene rings. When projected along [001], the packing shows two types of channels. The crystal studied was a racemic twin. PMID:22719586

Rubio, Omayra H; Fuentes de Arriba, Angel L; Sanz, Francisca; Muniz, Francisco M; Morán, Joaquín R

2012-06-01

389

Hyperconjugation: equilibrium secondary isotope effect on the stability of the tert-butyl cation. Kinetics of thermoneutral hydride transfer  

SciTech Connect

The thermochemistry of the hydride transfer equilibrium (CD/sub 3/)/sub 3/C/sup +/ + (CH/sub 3/)/sub 3/CH reversible (CH/sub 3/)/sub 3/C/sup +/ + (CD/sub 3/)/sub 3/CH was measured by pulsed high-pressure mass spectrometry. Measurements over a wide temperature range, 145-600K, allowed an accurate determination of the values: ..delta..H/sup 0/ = -0.57 +- 0.02 kcalmol; ..delta..S/sup 0/ = -0.57 +- 0.08 cal(mol x K); ..delta..G/sup 0//sub 298/ = -0.40 +- 0.07 kcal x mol; and K/sub 298/ = 1.97 +- 0.20. The direction of the observed isotope effect is consistent with C-H bond weakening in the ion due to hyperconjugation. The kinetics of the reaction show a slow rate and a large negative temperature coefficient, with k/sub 300/ = 0.36 and k/sub 600/ = 0.00625 x 10/sup -10/ cm/sup 3/ s/sup -1/, i.e., reaction efficiencies of about 0.03 to 0.0005. The observed negative temperature coefficient, k = AT/sup -5.8/, is larger than those observed for more exothermic hydride transfer reactions. The approach to collision rate is abrupt.

Meot-Ner (Mautner), M.

1987-12-23

390

BioToolomics Butyl (400, 500, 600)  

E-print Network

-flow property* >1000 cm/h for 400 serials; >500 cm/h for 500 serials; >300 cm/h for 600 serials OperationalBioToolomics 1 Data sheet SepFastTM Butyl (400, 500, 600) SepFastTM Pentyl (400, 500, 600) SepFastTM Hexyl (400, 500, 600) SepFastTM Phenyl (400, 500, 600) SepFastTM Heptyl (400, 500, 600) SepFastTM Octyl

Lebendiker, Mario

391

Binding of Butyl Gallate to Isolated Mung Bean Mitochondria 1  

PubMed Central

The binding of radioactively labeled butyl gallate to sucrose gradient-purified mung bean (Vigna radiata L.) mitochondria was studied. Titrations showed the binding of [14C]butyl gallate to the mitochondria consisted of both reversible and irreversible components. The reversible component bound with a dissociation constant of approximately 1 micromolar which was comparable to the observed inhibition constant for the inhibition of the alternative pathway by butyl gallate. The reversible binding of labeled butyl gallate was also prevented by addition of excess, unlabeled salicylhydroxamic acid. The concentration of binding sites associated with reversible butyl gallate binding was around 0.5 nanomole per milligram of mitochondrial protein. These results were consistent with the reversible binding site being associated with the butyl gallate site of inhibition of the cyanide-resistant, alternative electron transfer pathway in mung bean mitochondria. In addition to the reversible butyl gallate binding site, a nonspecific, irreversible association of butyl gallate with the mitochondrial membrane was observed. The latter binding did not readily saturate at high butyl gallate concentrations and was not correlated with butyl gallate inhibition of the alternative pathway. PMID:16663003

Siedow, James N.; Bickett, D. Mark

1983-01-01

392

Cyclodimerization versus polymerization of methyl methacrylate induced by N-heterocyclic carbenes: a combined experimental and theoretical study.  

PubMed

The activation behavior of two N-heterocyclic carbenes (NHCs), namely, 1,3-bis(isopropyl)imidazol-2-ylidene(NHCiPr) and 1,3-bis(tert-butyl) imidazol-2-ylidene (NHCtBu), as organic nucleophiles in the reaction with methyl methacrylate (MMA) is described. NHCtBu allows the polymerization of MMA in DMF at room temperature and in toluene at 50?°C, whereas NHCiPr reacts with two molecules of MMA, forming an unprecedented imidazolium-enolate cyclodimer (NHCiPr/MMA=1:2). It is proposed that the reaction mechanism occurs by initial 1,4-nucleophilic addition of NHCiPr to MMA, generating a zwitterionic enolate 2, followed by addition of 2 to a second MMA molecule, forming a linear imidazolium-enolate 3 (NHCiPr/MMA=1:2). Proton transfer, generating intermediate 5, followed by cyclization and release of methanol yielded the aforementioned zwitterionic cyclodimer 1:2 adduct 7, the molecular structure of which has been established by NMR spectroscopy, X-ray diffraction, and mass spectrometry. This unexpected difference between NHCtBu and NHCiPr in the reaction with MMA (polymerization and cyclodimerization, respectively) can be rationalized by using DFT calculations. In particular, the nature of the NHC strongly influences the cyclodimerization pathway, the cyclization of 5 and the release of methanol are the discriminating step and limiting step, respectively. In the case of NHCtBu, both steps are strongly disfavoured compared with that of NHCiPr (energetic difference of around 14 and 9?kcal?mol(-1), respectively), preventing the cyclization mechanism from a kinetic viewpoint. Moreover, addition of a third molecule of MMA in the polymerization pathway results in a lower activation barrier than that of the limiting step in the cyclodimerization pathway (difference of around 14?kcal?mol(-1)), in agreement with the formation of polymethyl methacrylate (PMMA) by using NHCtBu as nucleophile. PMID:24604823

Nzahou Ottou, Winnie; Bourichon, Damien; Vignolle, Joan; Wirotius, Anne-Laure; Robert, Fredéric; Landais, Yannick; Sotiropoulos, Jean-Marc; Miqueu, Karinne; Taton, Daniel

2014-04-01

393

Telomere Lengths, Pulmonary Fibrosis and Telomerase (TERT) Mutations  

PubMed Central

Background Telomerase is an enzyme that catalyzes the addition of nucleotides on the ends of chromosomes. Rare loss of function mutations in the gene that encodes the protein component of telomerase (TERT) have been described in patients with idiopathic pulmonary fibrosis (IPF). Here we examine the telomere lengths and pulmonary fibrosis phenotype seen in multiple kindreds with heterozygous TERT mutations. Methods and Findings We have identified 134 individuals with heterozygous TERT mutations from 21 unrelated families. Available medical records, surgical lung biopsies and radiographs were evaluated retrospectively. Genomic DNA isolated from circulating leukocytes has been used to measure telomere lengths with a quantitative PCR assay. We find that telomere lengths of TERT mutation carriers decrease in an age-dependent manner and show progressive shortening with successive generations of mutation inheritance. Family members without TERT mutations have a shorter mean telomere length than normal, demonstrating epigenetic inheritance of shortened telomere lengths in the absence of an inherited TERT mutation. Pulmonary fibrosis is an age-dependent phenotype not seen in mutation carriers less than 40 years of age but found in 60% of men 60 years or older; its development is associated with environmental exposures including cigarette smoking. A radiographic CT pattern of usual interstitial pneumonia (UIP), which is consistent with a diagnosis of IPF, is seen in 74% of cases and a pathologic pattern of UIP is seen in 86% of surgical lung biopsies. Pulmonary fibrosis associated with TERT mutations is progressive and lethal with a mean survival of 3 years after diagnosis. Overall, TERT mutation carriers demonstrate reduced life expectancy, with a mean age of death of 58 and 67 years for males and females, respectively. Conclusions A subset of pulmonary fibrosis, like dyskeratosis congenita, bone marrow failure, and liver disease, represents a “telomeropathy” caused by germline mutations in telomerase and characterized by short telomere lengths. Family members within kindreds who do not inherit the TERT mutation have shorter telomere lengths than controls, demonstrating epigenetic inheritance of a shortened parental telomere length set-point. PMID:20502709

Diaz de Leon, Alberto; Cronkhite, Jennifer T.; Katzenstein, Anna-Luise A.; Godwin, J. David; Raghu, Ganesh; Glazer, Craig S.; Rosenblatt, Randall L.; Girod, Carlos E.; Garrity, Edward R.; Xing, Chao; Garcia, Christine Kim

2010-01-01

394

DNA Methylation  

PubMed Central

The DNA of E. coli contains 19,120 6-methyladenines and 12,045 5-methylcytosines in addition to the four regular bases and these are formed by the postreplicative action of three DNA methyltransferases. The majority of the methylated bases are formed by the Dam and Dcm methyltransferases encoded by the dam (DNA adenine methyltransferase) and dcm (DNA cytosine methyltransferase) genes. Although not essential, Dam methylation is important for strand discrimination during repair of replication errors, controlling the frequency of initiation of chromosome replication at oriC, and regulation of transcription initiation at promoters containing GATC sequences. In contrast, there is no known function for Dcm methylation although Dcm recognition sites constitute sequence motifs for Very Short Patch repair of T/G base mismatches. In certain bacteria (e.g., Vibrio cholerae, Caulobacter crescentus) adenine methylation is essential and in C. crescentus, it is important for temporal gene expression which, in turn, is required for coordinating chromosome initiation, replication and division. In practical terms, Dam and Dcm methylation can inhibit restriction enzyme cleavage; decrease transformation frequency in certain bacteria; decrease the stability of short direct repeats; are necessary for site-directed mutagenesis; and to probe eukaryotic structure and function. PMID:25405210

Marinus, M.G.; Løbner-Olesen, A.

2014-01-01

395

CHLORINATED SOLVENT PLUME CONTROL  

EPA Science Inventory

This lecture will cover recent success in controlling and assessing the treatment of shallow ground water plumes of chlorinated solvents, other halogenated organic compounds, and methyl tert-butyl ether (MTBE)....

396

FENTON-DRIVEN CHEMICAL REGENERATION OF MTBE-SPENT GAC  

EPA Science Inventory

Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was chemically regenerated utilizing the Fenton mechanism. Two successive GAC regeneration cycles were performed involving iterative adsorption and oxidation processes: MTBE was adsorbed to the GAC, oxidized, r...

397

Ethyl tertiary-butyl ether: a toxicological review.  

PubMed

A number of oxygenated compounds (oxygenates) are available for use in gasoline to reduce vehicle exhaust emissions, reduce the aromatic compound content, and avoid the use of organo-lead compounds, while maintaining high octane numbers. Ethyl tertiary-butyl ether (ETBE) is one such compound. The current use of ETBE in gasoline or petrol is modest but increasing, with consequently similar trends in the potential for human exposure. Inhalation is the most likely mode of exposure, with about 30% of inhaled ETBE being retained by the lungs and distributed around the body. Following cessation of exposure, the blood concentration of ETBE falls rapidly, largely as a result of its metabolism to tertiary-butyl alcohol (TBA) and acetaldehyde. TBA may be further metabolized, first to 2-methyl-1,2-propanediol and then to 2-hydroxyisobutyrate, the two dominant metabolites found in urine of volunteers and rats. The rapid oxidation of acetaldehyde suggests that its blood concentration is unlikely to rise above normal as a result of human exposure to sources of ETBE. Single-dose toxicity tests show that ETBE has low toxicity and is essentially nonirritant to eyes and skin; it did not cause sensitization in a maximization test in guinea pigs. Neurological effects have been observed only at very high exposure concentrations. There is evidence for an effect of ETBE on the kidney of rats. Increases in kidney weight were seen in both sexes, but protein droplet accumulation (with alpha(2u)-globulin involvement) and sustained increases in cell proliferation occurred only in males. In liver, centrilobular necrosis was induced in mice, but not rats, after exposure by inhalation, although this lesion was reported in some rats exposed to very high oral doses of ETBE. The proportion of liver cells engaged in S-phase DNA synthesis was increased in mice of both sexes exposed by inhalation. ETBE has no specific effects on reproduction, development, or genetic material. Carcinogenicity studies have been conducted with ETBE, TBA, and ethanol (included in this review as an endogenous precursor of acetaldehyde in the absence of TBA). A single experiment with ETBE in rats and several experiments with ethanol in rats and mice were not considered adequate for an evaluation of ETBE carcinogenicity. In male rats only, TBA induced alpha(2u)-globulin nephropathy-related renal tubule adenomas. These are generally considered to have no human relevance. In addition, increases in thyroid follicular cell adenoma incidence were associated with TBA treatment in female mice. This result lacks independent confirmation and is not supported by experiments in which similar or higher internal doses of TBA were delivered. PMID:17453936

McGregor, Douglas

2007-05-01

398

hTERT-based therapy: a universal anticancer approach (Review).  

PubMed

Human telomerase reverse transcriptase (hTERT) has been identi?ed as a major protein involved in aberrant cell proliferation, immortalization, metastasis and stemness maintenance in a majority of tumors, yet it has little or no expression in normal somatic cells. During the past few years, the development of hTERT-based therapies such as immunotherapy, suicide gene therapy and small-molecule interfering therapy have become critical and specific for eradicating all types of cancer. Here, current knowledge regarding hTERT and its involvement in various cancers and its role as a target of cancer therapies are reviewed. Additionally, hurdles to new cancer therapy development and new therapeutic opportunities are described, along with areas that require further investigation. PMID:22992764

Lü, Mu-Han; Liao, Zhong-Li; Zhao, Xiao-Yan; Fan, Ya-Han; Lin, Xian-Long; Fang, Dian-Chun; Guo, Hong; Yang, Shi-Ming

2012-12-01

399

TERT promoter mutations in clear cell renal cell carcinoma.  

PubMed

We screened promoter region of the telomerase reverse transcriptase (TERT) for activating somatic mutations in 188 tumors from patients with clear cell renal cell carcinoma (ccRCC). Twelve tumors (6.4%) carried a mutation within the core promoter region of the gene. The mutations were less frequent in high grade tumors compared to low grade tumors [odds ratio (OR)?=?0.15, 95% confidence interval (CI)?=?0.03-0.72, p?=?0.02]. Multivariate analysis for cause specific survival showed statistically significant poor outcome in patients with TERT promoter mutations [hazard ratio (HR)?=?2.90, 95% CI?=?1.13-7.39, p?=?0.03]. A common polymorphism (rs2853669) within the locus seemed to act as a modifier of the effect of the mutations on patient survival as the noncarriers of the variant allele with the TERT promoter mutations showed worst survival (HR?=?3.34, 95% CI?=?1.24-8.98, p?=?0.02). We also measured relative telomere length (RTL) in tumors and difference between tumors with and without the TERT promoter mutations was not statistically significant. Similarly, no difference in patient survival based on RTL in tumors was observed. Our study showed a relatively low frequency of TERT promoter mutations in ccRCC. Nevertheless, patients with the mutations, particularly in the absence of the rs2853669 variant showed the worst disease-specific survival. Thus, it is possible that the TERT promoter mutations define a small subset of tumors with an aggressive behavior. PMID:25331263

Hosen, Ismail; Rachakonda, P Sivaramakrishna; Heidenreich, Barbara; Sitaram, Raviprakash T; Ljungberg, Börje; Roos, Göran; Hemminki, Kari; Kumar, Rajiv

2014-10-21

400

The chicken telomerase reverse transcriptase (chTERT): molecular and cytogenetic characterization with a comparative analysis  

E-print Network

The chicken telomerase reverse transcriptase (chTERT): molecular and cytogenetic characterization was to determine the molecular and cytogenetic features of the chicken telomerase reverse transcriptase (chTERT) gene and protein. The TERT mRNA from gastrula stage embryos was found to be 4497 bp in length

Delany, Mary E.

401

Synthesis and characterization of copper(II) and cobalt(II) complexes with two new potentially hexadentate Schiff base ligands. X-ray crystal structure determination of one copper(II) complex  

Microsoft Academic Search

Two new potentially hexadentate N2O4 Schiff base ligands 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy) phenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H2L1] and 2-((z)-(2-(2-(2-((z)-3,5-di-tert-butyl-2-hydroxybenzylideneamino) phenoxy)-5-tert-butylphenoxy) phenylimino) methyl)-4,6-di-tert-butylphenol [H2L2] were prepared from the reaction of 3,5-di-tert-butyl-2-hydroxy benzaldehyde with 1,2-bis(2?-aminophenoxy)benzene or 1,2-bis(2?-aminophenoxy)-4-t-butylbenzene, respectively. From the direct reaction of ligands [H2L1] and [H2L2] with copper(II) and cobalt(II) salts in methanolic solution and in the presence of N(Et)3 the neutral [CuL1], [CuL2],

Hassan Keypour; Maryam Shayesteh; Abdolhossein Sharifi-Rad; Sadegh Salehzadeh; Hamidreza Khavasi; Laura Valencia

2008-01-01

402

Blue-colored tert-butylamine clathrate hydrate.  

PubMed

Clathrate hydrates preserve active species more stably than the other icy materials and investigation of the behavior of the active species elucidates the physicochemical properties of clathrate hydrates like guest-guest interaction. Color of the tert-butylamine clathrate hydrate changes to blue after gamma irradiation and is bleachable with visible light. The electron spin resonance (ESR) spectrum at 120 K mainly consists of a triplet signal of the C-centered radical NH2C(CH3)2CH2• together with a single signal at g = 2.0008. The latter signal disappears after light exposure. These results indicate that both the blue color and the single ESR signal are derived from trapped electrons in the hydrate. They thermally decay around 140-160 K by the first-order reaction, and the activation energy is 27 kJ/mol. Since tert-butylamine molecules can capture protons due to the high proton affinity, electrons may remain in the hydrate without reacting with protons, making the hydrate blue after gamma irradiation. The long-lived trapped electrons in the tert-butylamine hydrate have an advantage to investigate those in icy materials because tert-butylamine hydrate is nonionic and has a tetra-coordinated host water network like crystalline ice without any substitution for water molecules. PMID:25139225

Tani, Atsushi; Koyama, Satoshi; Urabe, Yusuke; Takato, Kenji; Sugahara, Takeshi; Ohgaki, Kazunari

2014-11-26

403

Comparing photochemistry of n- and tert-butylamine all-trans retinal protonated Schiff-base: Effects of C dbnd N configurational inhomogeneity  

NASA Astrophysics Data System (ADS)

Photochemistry of all-trans tert-butylamine retinal protonated Schiff-base (TB-RPSB) is investigated by femtosecond pump-hyperspectral probe spectroscopy. Unlike the n-butyl analogue (NB-RPSB) no shifting of the transient spectral bands is observed upon tuning the excitation pulses from 395 to 475 nm. The 15 nm shift observed for NB-RPSB in similar experiments was assigned to unspecified ground state structural inhomogeneity. Present results indicate that is most likely due to the coexistence of C 15dbnd N double bond isomers in NB-RPSB. Elimination of this inhomogeneity in TB-RPSB makes it a more appropriate model for appreciating protein effects on RPSB photochemistry in retinal proteins.

Zhu, Jingyi; Bismuth, Oshrat; Gdor, Itay; Wand, Amir; Friedman, Noga; Sheves, Mordechai; Ruhman, Sanford

2009-09-01

404

Methyl eucomate  

PubMed Central

The crystal structure of the title compound [systematic name: methyl 3-carboxy-3-hydr­oxy-3-(4-hydroxy­benz­yl)propanoate], C12H14O6, is stabilized by inter­molecular O—H?O and C—H?O hydrogen bonds. The mol­ecules are arranged in layers, parallel to (001), which are inter­connected by the O—H?O hydrogen bonds. PMID:21202973

Li, Linglin; Zhou, Guang-Xiong; Jiang, Ren-Wang

2008-01-01

405

Structure and generation mechanism of a novel degradation product formed by oxidatively induced coupling of miconazole nitrate with butylated hydroxytoluene in a topical ointment studied by HPLC-ESI-MS and organic synthesis.  

PubMed

In a petrolatum based topical ointment formulation containing miconazole nitrate (1) as the active ingredient and 2,6-di-t-butyl-4-methylphenol (BHT) as a vehicle antioxidant, an oxidatively induced coupling reaction between miconazole nitrate and BHT occurred to form a novel adduct 1-(3,5-di-tert-butyl-4-hydroxy-benzyl)-3-[2-(2,4-dichloro-benzyloxy)-2-(2,4-dichloro-phenyl)-ethyl]-3H-imidazol-1-ium nitrate (2). The structure of 2 was established using high-performance liquid chromatography coupled with electrospray ionization mass spectrometry and was confirmed by comparing with a synthesized reference compound. The reaction proceeded through a quinone methide intermediate from BHT. Two synthetic methods were established for preparing 2. PMID:14705188

Zhang, Fa; Nunes, Mathews

2004-02-01

406

Chromatin redistribution of the DEK oncoprotein represses hTERT transcription in leukemias.  

PubMed

Although numerous factors have been found to modulate hTERT transcription, the mechanism of its repression in certain leukemias remains unknown. We show here that DEK represses hTERT transcription through its enrichment on the hTERT promoter in cells from chronic and acute myeloid leukemias, chronic lymphocytic leukemia, but not acute lymphocytic leukemias where hTERT is overexpressed. We isolated DEK from the hTERT promoter incubated with nuclear extracts derived from fresh acute myelogenous leukemia (AML) cells and from cells expressing Tax, an hTERT repressor encoded by the human T cell leukemia virus type 1. In addition to the recruitment of DEK, the displacement of two potent known hTERT transactivators from the hTERT promoter characterized both AML cells and Tax-expressing cells. Reporter and chromatin immunoprecipitation assays permitted to map the region that supports the repressive effect of DEK on hTERT transcription, which was proportionate to the level of DEK-promoter association but not with the level of DEK expression. Besides hTERT repression, this context of chromatin redistribution of DEK was found to govern about 40% of overall transcriptional modifications, including those of cancer-prone genes. In conclusion, DEK emerges as an hTERT repressor shared by various leukemia subtypes and seems involved in the deregulation of numerous genes associated with leukemogenesis. PMID:24563617

Karam, Maroun; Thenoz, Morgan; Capraro, Valérie; Robin, Jean-Philippe; Pinatel, Christiane; Lancon, Agnès; Galia, Perrine; Sibon, David; Thomas, Xavier; Ducastelle-Lepretre, Sophie; Nicolini, Franck; El-Hamri, Mohamed; Chelghoun, Youcef; Wattel, Eric; Mortreux, Franck

2014-01-01

407

Chromatin Redistribution of the DEK Oncoprotein Represses hTERT Transcription in Leukemias12  

PubMed Central

Although numerous factors have been found to modulate hTERT transcription, the mechanism of its repression in certain leukemias remains unknown. We show here that DEK represses hTERT transcription through its enrichment on the hTERT promoter in cells from chronic and acute myeloid leukemias, chronic lymphocytic leukemia, but not acute lymphocytic leukemias where hTERT is overexpressed. We isolated DEK from the hTERT promoter incubated with nuclear extracts derived from fresh acute myelogenous leukemia (AML) cells and from cells expressing Tax, an hTERT repressor encoded by the human T cell leukemia virus type 1. In addition to the recruitment of DEK, the displacement of two potent known hTERT transactivators from the hTERT promoter characterized both AML cells and Tax-expressing cells. Reporter and chromatin immunoprecipitation assays permitted to map the region that supports the repressive effect of DEK on hTERT transcription, which was proportionate to the level of DEK-promoter association but not with the level of DEK expression. Besides hTERT repression, this context of chromatin redistribution of DEK was found to govern about 40% of overall transcriptional modifications, including those of cancer-prone genes. In conclusion, DEK emerges as an hTERT repressor shared by various leukemia subtypes and seems involved in the deregulation of numerous genes associated with leukemogenesis. PMID:24563617

Karam, Maroun; Thenoz, Morgan; Capraro, Valérie; Robin, Jean-Philippe; Pinatel, Christiane; Lancon, Agnès; Galia, Perrine; Sibon, David; Thomas, Xavier; Ducastelle-Lepretre, Sophie; Nicolini, Franck; El-Hamri, Mohamed; Chelghoun, Youcef; Wattel, Eric; Mortreux, Franck

2014-01-01

408

Tert-butylhydroquinone induces mitochondrial oxidative stress causing Nrf2 activation.  

PubMed

Tert-butylhydroquinone (tBHQ), the major metabolite of butylated hydroxyanisole, induces an antioxidant response through the redox-sensitive transcription factor, nuclear factor-E2-related factor-2 (Nrf2). However, the mechanism by which tBHQ induces Nrf2 activity is not entirely understood. Here, we show that tBHQ preferentially alters the redox status in the mitochondrial compartment in HeLa cells. HeLa cells treated with tBHQ showed a preferential oxidation of mitochondrial thioredoxin-2 (Trx2), while cellular glutathione and cytosolic thioredoxin-1 were not affected. Preferential mitochondrial oxidation by tBHQ was supported by detection of reactive oxygen species (ROS) specific to this compartment. To determine the role of Trx2 in regulating downstream effects of tBHQ, HeLa cells were transiently transfected with an empty, Trx2, or C93S (Cys93Ser) Trx2 dominant-negative mutant expression vector. Overexpression of Trx2 decreased basal mitochondrial ROS production, whereas expression of C93S Trx2 enhanced it. In addition, under untreated conditions, expression of C93S Trx2 led to an increase in the basal activities of Nrf2. With tBHQ treatments, Trx2 overexpression suppressed Nrf2 accumulation and activity, whereas expression of C93S Trx2 had no effect on the degree of inducibility or Nrf2 accumulation but did increase the overall activity of Nrf2. Quantitative polymerase chain reaction analysis of Nrf2-regulated gene expression corroborate Trx2 control of tBHQ-mediated Nrf2 activation. These data show a compartment-specific effect where tBHQ-induced Nrf2 signaling is mediated by Trx2 and suggest that antioxidant status in various compartments would provide different levels of control of redox signaling. PMID:20429028

Imhoff, Barry R; Hansen, Jason M

2010-12-01

409

Cordyceptin induces apoptosis through repressing hTERT expression and inducing extranuclear export of hTERT.  

PubMed

Cordycepin is an adenosine analog originally extracted from Cordyceps militaris that possesses many pharmacological effects including immune activation and antioxidant and antitumor effects. However, the underlying relationship between apoptosis and telomerase activity in response to cordycepin exposure has not been investigated. In this study, we found that cordycepin-induced apoptosis of human leukemia cells (H937 and THP-1 cells) was associated with inactivation of telomerase and downregulation of human telomerase reverse transcriptase (hTERT) as well as the transcription factors c-Myc and Sp1, which are required for basal transcription from the hTERT gene promoter. Cordycepin also attenuated the activation of phosphoinositide-3-kinase (PI3K)/Akt signaling, thereby reducing phosphorylation and nuclear translocation of hTERT. We further showed that the PI3K inhibitor LY29004 significantly decreased telomerase activity in cordycepin-treated cells and increased cordycepin-induced cell death. These findings demonstrate that cordycepin is cytotoxic to human leukemia cells and suppresses telomerase activity through transcriptional and post-translational suppression of hTERT by inactivating the PI3K/Akt signaling pathway. PMID:25282637

Jang, Kyung-Jun; Kwon, Gi-Sun; Jeong, Jin-Woo; Kim, Cheol-Hong; Yoon, Hyun-Min; Kim, Gi-Young; Shim, Jung-Hyun; Moon, Sung-Kwon; Kim, Wun-Jae; Choi, Yung Hyun

2015-03-01

410

Synthesis of Poly (Butyl Methacrylate/Butyl Acrylate) Highly Absorptive Resin Using Glow Discharge Electrolysis  

NASA Astrophysics Data System (ADS)

A highly absorptive resin poly (butyl methacrylate (BMA)-co-butyl acrylate (BA)) was prepared by emulsion polymerization, which was initiated by glow discharge electrolysis plasma (GDEP). The effects of discharge voltage, discharge time, monomer ratio and the amounts of cross-linking agent were examined and discussed in detail. The chemical structure of the obtained resin was characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The optimal conditions were obtained as: discharge voltage was 600 V, discharge time was 8 min, the ratios of BMA:BA being 2:1 for chloroform and 3:1 for xylene, with 2% N, N'-methylenebis. Under optimal conditions, the oil absorbency was 70 g/g for chloroform and 46 g/g for xylene. Moreover, the absorptive dynamical behavior of the resulting resin was also investigated.

Li, Yan; Yao, Mengqi; Liao, Ruirui; Yang, Wu; Gao, Jinzhang; Ren, Jie

2014-08-01

411

Methemoglobin formation from butylated hydroxyanisole and oxyhemoglobin. Comparison with butylated hydroxytoluene and p-hydroxyanisole.  

PubMed

The widely used food additives butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) react with oxyhemoglobin, thereby forming methemoglobin. The reaction rates were measured using visible spectroscopy, and second order rate constants were established for BHA and compared with p-hydroxyanisole. Using ESR we investigated the involvement of free radical reaction intermediates. The expected one-electron oxidation product of BHA and BHT, the phenoxyl radical, could only be detected with pure 3-t-butyl-4-hydroxyanisole and oxyhemoglobin. With the commercial mixture of 2- and 3-t-butyl-4-hydroxyanisole a very strong ESR signal of a secondary free radical species was observed, similar to the one observed earlier with p-hydroxyanisole and dependent on the presence of free thiol groups, so that we assumed the intermediate existence of a perferryl species, the MetHb-H2O2 adduct. In a second series of experiments we investigated the reactivity of this postulated intermediate with BHA and BHT, starting with a pure MetHb/H2O2-phenol mixture in a stopped-flow apparatus linked to the ESR spectrometer, detecting the expected phenoxyl radicals from BHA and p-hydroxyanisole. Due to the low solubility and decreased reactivity of BHT only traces of phenoxyl type radical were found together with a high concentration of unreacted perferryl species. The reactivity of BHA, BHT and p-hydroxyanisole with free thiol groups is demonstrated by an increased reaction rate in the presence of the thiol group blocking substance NEM. PMID:1318249

Stolze, K; Nohl, H

1992-01-01

412

Bivalent sequential binding of docetaxel to methyl-?-cyclodextrin.  

PubMed

New docetaxel (Dtx) and cyclodextrin (CD) inclusion complexes having improved apparent water solubility (up to 9.98mgmL(-1)) were obtained from phase solubility diagrams. ?-CD and SBE-?-CD offered only poor solubility enhancements while considerable increases in apparent solubility were obtained with Me-?-CD (20%, w/w) and HP-?-CD (40%, w/w) (9.98mgmL(-1) and 7.43mgmL(-1), respectively). The complexation mechanism between Dtx and Me-?-CD was investigated by circular dichroism spectrometry, two-dimensional (1)H NMR (NOESY) in D(2)O, isothermal titration calorimetry (ITC) and molecular docking calculations. Circular dichroism and NOESY confirmed the existence of non-covalent interactions between Dtx and Me-?-CD and suggested that the tert-butyl group (C(6)-C(9)) and two aromatic groups (C(24)-C(29) and C(30)-C(35)) of Dtx interacted with the Me-?-CD molecules. The combination of ITC results to molecular docking calculations led to the identification of an unconventional sequential binding mechanism between Me-?-CD and Dtx. In this sequential binding, a Me-?-CD molecule first interacted with both tert-butyl and C(30)-C(35) aromatic groups (K(1): 744M(-1)). Then a second Me-?-CD molecule interacted with the C(24)-C(29) aromatic group (K(2): 202M(-1)). The entropy of the first interaction was positive, whereas a negative value of entropy was found for the second interaction. The opposite behavior observed for these two sites was explained by differences in the hydrophobic contact surface and functional group flexibility. PMID:21736931

Mazzaferro, Silvia; Bouchemal, Kawthar; Gallard, Jean-François; Iorga, Bogdan I; Cheron, Monique; Gueutin, Claire; Steinmesse, Claire; Ponchel, Gilles

2011-09-15

413

Efficiency of solvent extraction methods for the determination of methyl mercury in forest soils.  

PubMed

Methyl mercury was determined by gas chromatography, microwave induced plasma, atomic emission spectrometry (GC-MIP-AES) using two different methods. One was based on extraction of mercury species into toluene, pre-concentration by evaporation and butylation of methyl mercury with a Grignard reagent followed by determination. With the other, methyl mercury was extracted into dichloromethane and back extracted into water followed by in situ ethylation, collection of ethylated mercury species on Tenax and determination. The accuracy of the entire procedure based on butylation was validated for the individual steps involved in the method. Methyl mercury added to various types of soil samples showed an overall average recovery of 87.5%. Reduced recovery was only caused by losses of methyl mercury during extraction into toluene and during pre-concentration by evaporation. The extraction of methyl mercury added to the soil was therefore quantitative. Since it is not possible to directly determine the extraction efficiency of incipient methyl mercury, the extraction efficiency of total mercury with an acidified solution containing CuSO4 and KBr was compared with high-pressure microwave acid digestion. The solvent extraction efficiency was 93%. For the IAEA 356 sediment certified reference material, mercury was less efficiently extracted and determined methyl mercury concentrations were below the certified value. Incomplete extraction could be explained by the presence of a large part of inorganic sulfides, as determined by x-ray absorption near-edge structure spectroscopy (XANES). Analyses of sediment reference material CRM 580 gave results in agreement with the certified value. The butylation method gave a detection limit for methyl mercury of 0.1 ng g(-1), calculated as three times the standard deviation for repeated analysis of soil samples. Lower values were obtained with the ethylation method. The precision, expressed as RSD for concentrations 20 times above the detection limit, was typically 5%. PMID:11227478

Qian, J; Skyllberg, U; Tu, Q; Bleam, W F; Frech, W

2000-07-01

414

Exposure to mono-n-butyl phthalate disrupts the development of preimplantation embryos.  

PubMed

Dibutyl phthalate (DBP), a widely used phthalate, is known to cause many serious diseases, especially in the reproductive system. However, little is known about the effects of its metabolite, mono-n-butyl phthalate (MBP), on preimplantation embryo development. In the present study, we found that treatment of embryos with 10?³ M MBP impaired developmental competency, whereas exposure to 10?? M MBP delayed the progression of preimplantation embryos to the blastocyst stage. Furthermore, reactive oxygen species (ROS) levels in embryos were significantly increased following treatment with 10?³ M MBP. In addition, 10?³ M MBP increased apoptosis via the release of cytochrome c, whereas immunofluorescent analysis revealed that exposure of preimplantation embryos to MBP concentration-dependently (10??, 10?? and 10?³ M) decreased DNA methylation. Together, the results indicate a possible relationship between MBP exposure and developmental failure in preimplantation embryos. PMID:23231764

Chu, Da-Peng; Tian, Shi; Sun, Da-Guang; Hao, Chan-Juan; Xia, Hong-Fei; Ma, Xu

2013-01-01

415

Regiochemical variations in reactions of methylcubane with tert-butoxyl radical, cytochrome P-450 enzymes, and a methane monooxygenase system  

SciTech Connect

Reactions of methylcubane (1) with the tert-butoxyl radical (t-BuO{sup .}), with cytochrome P-450 enzymes, and with a methane monooxygenase (MMO) system have been studied. 2-Methylcubanecarboxylic acid (9b) is a new compound prepared from cubanecarboxylic acid. The key synthetic reactions were (1) metalation and subsequent iodination of the 2-position of (diisopropylcarbamoyl)cubane to effect the initial functionalization, (2) lithium-for-iodine exchange and methylation followed by reduction to give 2-methyl-l-[(diisopropylamino)methyl]-cubane, and (3) dimethyldioxirane oxidation of this amine to give 9b. Reaction of 1 with t-BuO{sup .} in the presence of 2,2,5,5-tetramethylisoindole-N-oxyl radical (TMIO{sup .}) at 40-55{degree}C gave mainly cube-substituted products in confirmation of the report that hydrogen atom abstraction by the electrophilic alkoxyl radical at low temperature occurs at the cubyl C-H positions. In a competition experiment at 42{degree}C, methylcubane was at least 3.5 times more reactive toward t-BuO{sup .} than cyclohexane, indicating that the cubyl positions in 1 are >= 40 times more reactive than the methyl positions in 1 (per hydrogen) toward the alkoxyl radical. Oxidation of 1 by enzymes gave alcohol products that were converted to their acetate derivatives for identification and quantitation. Microsomal cytochrome P-450 enzymes from rat and the rat purified P-450 isozyme CYP2B1 hydroxylated 1 at all positions, whereas the reconstituted MMO system from Methylococcus capsulatus (Bath) hydroxylated l only at the methyl position. 78 refs., 1 tab.

Choi, S.Y.; Hollenberg, P.F.; Newcomb, M.; Putt, D.A. [Wayne State Univ., Detroit, MI (United States)] [Wayne State Univ., Detroit, MI (United States); Eaton, P.E.; Upadhyaya, S.P.; Xiong, Y. [Univ. of Chicago, IL (United States)] [Univ. of Chicago, IL (United States); Liu, K.E.; Lippard, S.J. [Massachusetts Inst. of Technology, Cambridge, MA (United States)] [Massachusetts Inst. of Technology, Cambridge, MA (United States)

1996-07-17

416

Synthesis, structural characterization and in vitro inhibitory studies against human breast cancer of the bis-(2,6-di-tert-butylphenol)tin(IV) dichloride and its complexes.  

PubMed

Four new organotin(IV) complexes of bis-(2,6-di-tert-butylphenol)tin(IV) dichloride [(tert-Bu-)(2)(HO-Ph)](2)SnCl(2) (1) with the heterocyclic thioamides 2-mercapto-pyrimidine (PMTH), 2-mercapto-4-methyl-pyrimidine (MPMTH), 2-mercapto-pyridine (PYTH) and 2-mercapto-benzothiazole (MBZTH), of formulae {[(tert-Bu-)(2)(HO-Ph)](2)Sn(PMT)(2)} (2), {[(tert-Bu-)(2)(HO-Ph)](2)Sn(MPMT)(2)} (3), {[(tert-Bu-)(2)(HO-Ph)](2)SnCl(PYT)} (4) and {[(tert-Bu-)(2)(HO-Ph)](2)SnCl(MBZT)} (5), have been synthesized and characterized by elemental analysis, (1)H-, (13)C-, (119)Sn-NMR, EPR, FT-IR, Raman and Mössbauer spectroscopic techniques. The crystal and molecular structures of compounds 1–5 have been determined by X-ray diffraction. The geometries around the metal center adopted in complexes 1–5 varied between tetrahedral in 1, trigonal bipyramidal in 3, 4, 5 and distorted octahedral in 2. Two carbon atoms from aryl groups and two chlorine atoms form a distorted tetrahedron in the case of 1. Two carbon, two sulfur and two nitrogen atoms from thione ligands form a distorted octahedral geometry around tin(IV) with trans-C(2), cis-N(2), cis-S(2)-configurations in 2. However, in the case of 4 and 5 complexes two carbon, one sulfur, one nitrogen and one chloride atom form a distorted trigonal bipyramidal arrangement. Finally, in the case of 3 the trigonal bipyramidal geometry is achieved by two carbon, two sulfur and one nitrogen atom in a unique coordination mode of thioamides toward the tin(IV) cation. Compounds 1–5 were tested for their in vitro cytotoxicity against the human breast adenocarcinoma (MCF-7) cell line. Compound 3 exhibits strong cytotoxic activity against MCF-7 cells (IC(50) = 0.58 ± 0.1 ?M). PMID:23052471

Shpakovsky, D B; Banti, C N; Beaulieu-Houle, G; Kourkoumelis, N; Manoli, M; Manos, M J; Tasiopoulos, A J; Hadjikakou, S K; Milaeva, E R; Charalabopoulos, K; Bakas, T; Butler, I S; Hadjiliadis, N

2012-12-28

417

CTCF mediates the TERT enhancer-promoter interactions in lung cancer cells: identification of a novel enhancer region involved in the regulation of TERT gene.  

PubMed

Telomerase activation is a hallmark of cancer. Although the regulation of the telomerase reverse transcriptase catalytic subunit (TERT), the rate-limiting factor for telomerase activity, has been studied intensively it remains incompletely understood. In cells devoid of telomerase activity, TERT is embedded in a region of condensed chromatin and the chromatin remodeling protein CCCTC-binding factor (CTCF) has been implicated in the inhibition of TERT expression. The importance of TERT activation for cellular immortalization and carcinogenesis is attested by the fact that the gene is expressed in more than 90% of immortal cell lines and tumors and that gain of TERT is the most frequent amplification event in early stage lung cancer. This study was designed to study the mechanisms of regulation of the TERT gene expression by the CTCF transcription factor in three human lung cancer cell lines, A427, A549 and H838. Depletion of CTCF by siRNA resulted in reduced TERT mRNA levels in two (A427 and A549) of the three cell lines. A novel enhancer element was identified approximately 4.5 kb upstream of the TERT transcription start site. Chromatin immunoprecipitation experiments revealed recruitment of CTCF to this enhancer element. Chromosome conformation capture experiments demonstrated the presence of CTCF-dependent chromatin loops between this enhancer element and the TERT proximal promoter in A427 and A549 cell lines. In summary, the results show that CTCF plays an important role in maintaining TERT expression in a subset of human lung cancer cell lines. This role may be due to CTCF-dependent enhancer-promoter interactions. PMID:24174344

Eldholm, Vegard; Haugen, Aage; Zienolddiny, Shanbeh

2014-05-15

418

X-ray structural study of lanthanide complexes with a p- tert-butylthiacalix[4]arene bearing phosphoryl pendant arms  

NASA Astrophysics Data System (ADS)

A new lower-rim substituted thiacalix[4]arene, 5,11,17,23-tetra- tert-butyl-25,26,27,28-tetrakis(diphenylphosphinoylmethoxy) thiacalix[4]arene ( L) has been synthesized and structurally characterized as an adduct L·0.5MeOH·1.5H 2O, monoclinic, space group P2 1/n . The ligand adopts a cone conformation. Trivalent lanthanide ion complexes of this ligand have been synthesized and characterized by elemental analysis and IR spectra. The crystal structures of La 3+ and Nd 3+ complexes were determined by X-ray diffraction method. They are isostructural and belong to tetragonal system, I4 1/acd space group. In each complex, the calixarene retains the cone conformation, the metal ion is nine-coordinated to four oxygen atoms from phosphine oxide substituents, four oxygen atoms from two bidentate nitrate anions and one oxygen atom from a hydroxyl ion. The coordination polyhedron is a single-capped square antiprism. The complex assembles to a novel infinitely 1D helical structure through ?-? stacking, and further crosses each other forming a nanometer scale chessboard-like pore structure along c direction.

Guo, Qian-Ling; Yuan, Da-Qiang; Ma, Shu-Lan; Liu, Ying-Chun; Zhu, Wen-Xiang

2005-10-01

419

Experimental Pathology Laboratories, Inc. Ethyl-Tertiary-Butyl Ether  

E-print Network

Experimental Pathology Laboratories, Inc. Ethyl-Tertiary-Butyl Ether C00117/00117-64 AMENDED PATHOLOGY QUALITY ASSESSMENT REVIEW AND PWG COORDINATOR'S REPORT Park, NC 27709 Submitted by: Experimental Pathology Laboratories, Inc. Street Address: Mailing Address

Baker, Chris I.

420

NMR study of cation dynamics in three crystalline states of 1-butyl-3-methylimidazolium hexafluorophosphate exhibiting crystal polymorphism.  

PubMed

We investigate the cation rotational dynamics of a room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim]PF(6)) in its three crystalline states by (1)H NMR spectroscopy. Spin-lattice and spin-spin relaxation time (T(1) and T(2), respectively) measurements as a function of temperature confirm the presence of three polymorphic crystals of [C(4)mim]PF(6): crystals ?, ?, and ?, which we previously discovered using Raman spectroscopy and calorimetry. Second moment calculations of (1)H NMR spectra reveal that certain segmental motions of the butyl group in addition to the rapid rotation of the two methyl groups in the cation occur in all the crystals. The trend in the mobility of the segmental motions is ? < ? ? ?, which is consistent with the strength of cation-anion interactions (or crystal packing density) estimated from high-frequency Raman scattering experiments. T(1) measurements demonstrate two types of rotational motions on the nanosecond time scale in all three crystals: fast and slow motions. The three crystals have similar activation energies of 12.5-15.1 kJ mol(-1) for the fast motion, which is assigned to the rotation of the methyl group at the terminal of the butyl group. These observed activation energies were consistent with that estimated by quantum chemical calculations in the gas phase (11.9 kJ mol(-1)). In contrast, the slow motions of crystals ? and ? are attributed to different segmental motions of the butyl group and that of crystal ? to either a little segmental motion or a certain PF(6)(-) rotational motion. These nanosecond rotational motions obtained from the T(1) measurements do not appear to be affected by crystal packing density because local interactions in the crystalline state rather than packing density govern such nanosecond motions. With respect to the segmental motions, the mobility is likely to change significantly with the conformation of the butyl group. On the basis of these findings, crystal ?, which is the only crystalline phase previously determined using single-crystal X-ray diffraction, is considered to be the most stable phase because of the slowest segmental motions and the strongest cation-anion interactions. PMID:22380424

Endo, Takatsugu; Murata, Hiroki; Imanari, Mamoru; Mizushima, Noriko; Seki, Hiroko; Nishikawa, Keiko

2012-03-29

421

AVOIDING HYDROLYSIS OF FUEL ETHER OXYGENATES DURING STATIC HEADSPACE ANALYSIS  

EPA Science Inventory

A headspace autosampler, gas chromatograph and ion trap mass spectrometer (headspace GC/MS) were used for trace analysis of fuel oxygenates and related compounds and aromatics in water. A method has been developed for determination of methyl tert-butyl ether (MTBE), ethyl tert-b...

422

Human chromosome 5 carries a transcriptional regulator of human telomerase reverse transcriptase ( hTERT)  

Microsoft Academic Search

Telomerase activation is crucial for cells that tend to be immortalized. Increased telomerase activity is correlated with upregulation of telomerase reverse transcriptase (TERT) expression. In most human somatic cells, hTERT expression is suppressed by multiple factors. We have previously shown that human chromosome 5 carries a possible suppressor of mouse tert mtert expression in a mouse melanoma cell line, B16-F10

Dong-Lai Qi; Takahito Ohhira; Mitsuo Oshimura; Hiroyuki Kugoh

2010-01-01

423

Isolation and characterization of a new Mycobacterium austroafricanum strain, IFP 2015, growing on MTBE.  

PubMed

A new Mycobacterium austroafricanum strain, IFP 2015, growing on methyl tert-butyl ether (MTBE) as a sole carbon source was isolated from an MTBE-degrading microcosm inoculated with drain water of an MTBE-supplemented gasoline storage tank. M. austroafricanum IFP 2015 was able to grow on tert-butyl formate, tert-butyl alcohol (TBA) and alpha-hydroxyisobutyrate. 2-Methyl-1,2-propanediol was identified as the TBA oxidation product in M. austroafricanum IFP 2015 and in the previously isolated M. austroafricanum IFP 2012. M. austroafricanum IFP 2015 also degraded ethyl tert-butyl ether more rapidly than M. austroafricanum IFP 2012. Specific primers designed to monitor the presence of M. austroafricanum strains could be used as molecular tools to detect similar strains in MTBE-contaminated environment. PMID:16028043

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

2006-04-01

424

Lipase-catalyzed naproxen methyl ester hydrolysis in water-saturated ionic liquid: significantly enhanced enantioselectivity and stability  

Microsoft Academic Search

The lipase selective hydrolysis of Naproxen methyl ester was explored in both water-saturated isooctane and water-saturated ionic liquid 1-butyl-3-methylimidazolium hexafluoro-phoshate ([bmim]PF6) to see any significant differences in terms of enantioselectivity and stability between two different classes of reaction media. It is shown that polar and hydrophobic of [bmim]PF6 made it an unearthly reaction medium for hydrolysis of Naproxen methyl ester.

Jia-Ying Xin; Yong-Jie Zhao; Yan-Guo Shi; Chun-Gu Xia; Shu-Ben Li

2005-01-01

425

Embryolethality of butyl benzyl phthalate in rats  

SciTech Connect

The developmental toxicity of butyl benzyl phthalate (BBP) was studied in Wistar rats. Pregnant rats were given BBP at a dosage of 0, 0.25, 0.5, 1.0 or 2.0% in the diet from day 0 to day 20 of pregnancy. Morphological examinations of the fetuses revealed no evidence of teratogenesis. In the 2.0% group, all dams exhibited complete resorption of all the implanted embryos, and their food consumption, body weight gain and adjusted weight gain during pregnancy were markedly lowered. To determine whether the embryolethality was the result of reduced food consumption during pregnancy, a pair-feeding study was performed in which the pregnant rats received the same amount of diet consumed by the 2.0% BBP-treated pregnant rats. The pair-fed and 2.0 % BBP-treated pregnant rats showed significant and comparable reductions in the adjusted weight gain. The number of live fetuses was lowered in the pair-fed group. However, the complete resorption of all the implanted embryos was not found in any of the pair-fed pregnant rats. The data suggest that the embryolethality observed in the 2.0 % BBP-treated pregnant rats is attributable to the effects o dietary BBP.

Ema, N.; Itami, T.; Kawasaki, H. (National Inst. Hyg. Science, Osaka (Japan))

1991-03-15

426

Comparative developmental toxicity of n-butyl benzyl phthalate and di-n-butyl phthalate in rats  

Microsoft Academic Search

n-Butyl benzyl phthalate (BBP) and di-n-butyl phthalate (DBP) were evaluated and compared for their developmental toxic potential. Pregnant rats were given either BBP or DBP by gastric intubation at a dose of 0.75, 1.0 and 1.25 g\\/kg on days 7–9, days 10–12 and days 13–15 of pregnancy. Regardless of the days of treatment, a significantly increased incidence of postimplantation loss

M. Ema; R. Kurosaka; H. Amano; Y. Ogawa

1995-01-01

427

Surface tension and viscosity of 1-butyl-3-methylimidazolium iodide and 1-butyl-3-methylimidazolium tetrafluoroborate, and solubility of lithium bromide+1-butyl-3-methylimidazolium bromide in water  

Microsoft Academic Search

The surface tension and viscosity of 1-butyl-3-methylimidazolium iodide ([bmim][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate\\u000a ([bmim][BF4]) were measured over a temperature range of 298. 15 to 323.15 K. It was found that both the viscosity and surface tension\\u000a decrease with increasing temperature and that the surface tension and viscosity values of [bmim][I] were higher than those\\u000a of [bmim][BF4]. Additionally, the solubility of lithium

Ki-Sub Kim; Dorjnamjin Demberelnyamba; Bae-Kun Shin; Sun-Hwa Yeon; Sukjeong Choi; Jong-Ho Cha; Huen Lee; Chul-Soo Lee; Jae-Jin Shim

2006-01-01

428

Determination of oxygenates in gasoline by FTIR  

Microsoft Academic Search

Oxygenates of the type C1 to C4 alcohols and MTBE have been used for improving the octane number of gasoline and helping in reduction of emissions. These oxygenates are used as substitutes for the poisonous tetraethyl lead. The ASTM D-4815 method utilizes a GC method for determining methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol (2-methyl-1-propanol), tert-butanol (2-methyl-2-propanol) and methyl tert-butyl

Asfaha Iob; Rick Buenafe; Nurredin M Abbas

1998-01-01

429