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1

Facile synthesis of enantiomerically pure tert-butyl(methyl)phenylsilanes  

Microsoft Academic Search

A method for the preparation of both enantiomers of tert-butyl(methyl)phenylsilane 2 is presented. Racemic tert-butyl(methyl)phenylsilyl chloride 3 was allowed to react with (R)-(?)-2-amino-1-butanol 4 to give hydrochloride 5. Diastereomer separation via treatment of the respective free amine 6 with 0.5 mol equivalent of HCl in hexane-2-propanol yielded crystalline diastereomerically pure hydrochloride (R)Si-5. The corresponding free amine (R)Si-6 was reduced with

Pawe? Jankowski; Ernst Schaumann; Jerzy Wicha; Andrzej Zarecki; Gunadi Adiwidjaja

1999-01-01

2

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

3

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). ...

4

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 (...

5

Environmental Microbiology (2001) 3(6), 407416 Methyl tert-butyl ether (MTBE) degradation by a  

E-print Network

is often proposed as the most promising alter- native after treatment. However, MTBE biodegradation appears of degrading a variety of hydrocarbons, including tert-butyl alcohol (TBA), tert-amyl methyl ether (TAME- tion. The evaluation of innovative and cost-effective treatment such as bioremediation for MTBE spills

6

The antioxidant methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.  

PubMed

The title compound, C18H28O3, was prepared by the reaction of 2,6-di-tert-butylphenol with methyl acrylate under basic conditions using dimethyl sulfoxide as the promoter. The structure of this antioxidant indicates significant strain between the ortho tert-butyl substituents and the phenolic OH group. In spite of the steric crowding of the OH group, it participates in intermolecular hydrogen bonding with the ester carbonyl O atom. PMID:25370105

Li, Xiang; Wang, Zhi Gang; Chen, Hou He; Liu, Sheng Gao

2014-11-15

7

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

PubMed

Methyl tert-butyl ether (MTBE) is a widely used gasoline oxygenate. Contamination of MTBE and its major degradation product tert-butyl alcohol (TBA) in groundwater and surface water has received great attention. However, sorption affinity and sorption mechanisms of MTBE and TBA to synthetic resins, which can be potentially used in removal of these contaminants from water, in passive sampling, or in enrichment of bacteria, have not been studied systemically. In this study, kinetic and equilibrium sorption experiments (single solute and binary mixtures) on four synthetic resins were conducted. The sorption affinity of the investigated sorbents for MTBE and TBA decreases in the order Ambersorb 563>Optipore L493>Amberlite XAD4>Amberlite XAD7, and all show higher sorption affinity for MTBE than for TBA. Binary experiments with o-xylene, a major compound of gasoline as co-contaminant, imply that all resins preferentially sorb o-xylene over MTBE or TBA, i.e., there is sorption competition. In the equilibrium aqueous concentration (Ceq) range (0.1-139.0 mg/L for MTBE, and 0.01-48.4 mg/L for TBA), experimental and modeling results as well as sorbent characteristics indicate that micropore filling and/or some other type of adsorption process (e.g., adsorption to specific sites of high sorption potential at low concentrations) rather than partitioning were the dominant sorption mechanisms. Optipore L493 has favourable sorption and desorption characteristics, and is a suitable sorbent, e.g., in bacteria enrichment or passive sampling for moderately polar compounds. However, for highly polar compounds such as TBA, Ambersorb 563 might be a better choice, especially in water treatment. PMID:16139865

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

2005-10-01

8

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

EPA Science Inventory

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

9

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

E-print Network

dioxide, making the DMP reactor a promising tool in the future remediation of water. Chemical and physical. It is anticipated that AOTs will be able to chemically treat organic pollutants such as MTBE that have physicalTreatment of Methyl tert-Butyl Ether Contaminated Water Using a Dense Medium Plasma Reactor

Dandy, David

10

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

EPA Science Inventory

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

11

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...

12

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...

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

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

EPA Science Inventory

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

15

The Knock-Limited Performance of Fuel Blends Containing Spiropentane, Methylenecyclobutane, Di-Tert-Butyl Ether, Methyl Tert-Butyl Ether, and Triptane  

NASA Technical Reports Server (NTRS)

Tests show that at inlet-air temperatures of 250 deg F and 100 deg F the knock-limited performance of the base fuel of blends, leaded with 4 ml TEL per gallon and containing 20 percent spiropentane, was reduced at fuel/air ratios below 0.085. The 20 percent methylenecyclobutane reduced the knock-limited power of the base fuel at fuel/air ratios below 0.112. Di-tert-butyl ether, methyl-tert-butyl ether, and triptane increased the knock-limited power of the base fuel at all fuel/air ratios and at both temperatures.

Meyer, Carl L.

1946-01-01

16

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...

17

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

PubMed

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

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

2002-01-01

18

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

Microsoft Academic Search

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

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

2003-01-01

19

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  

Microsoft Academic Search

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

Mònica Rosell; Sílvia Lacorte; Damià Barceló

2006-01-01

20

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

EPA Science Inventory

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

21

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

EPA Science Inventory

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

22

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...

23

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

EPA Science Inventory

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

24

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...

25

High levels of monoaromatic compounds limit the use of solid-phase microextraction of methyl tert-butyl ether and tert-butyl alcohol.  

PubMed

Recently, two papers reported the use of solid-phase microextraction (SPME) with poly(dimethylsiloxane)(PDMS)/Carboxen fibers to determine trace levels of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (tBA) in water. Attempts were made to apply this technique to the analysis of water samples containing high levels of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEXsTMBs) as would be expected at leaking underground storage tank sites. It was found that when the sample contained total aromatic compounds above 1 ppm, the response of the internal standards, deuterated MTBE and tBA, dropped by more than 65%. As this decrease in internal standard peak area was unacceptable, a static headspace method was used instead. This headspace method was used successfully to analyze groundwater from 670 monitoring wells at 74 service stations located in the northeast United States. In these monitoring wells, 30% of the samples contained total BTEXsTMBs above 1 ppm. If the SPME method was used to analyze these samples, dilution of more than 200 samples would be required to minimize the adverse matrix effect that high aromatic content had on the internal standard peak area. PMID:11506001

Black, L; Fine, D

2001-08-01

26

tert-Butyl 3-[N-(tert-butoxy-carbonyl)methyl-amino]-4-methoxy-imino-3-methyl-piperidine-1-carboxyl-ate  

PubMed Central

The title compound, C18H33N3O5, was prepared from N-tert-butoxy­carbonyl-4-piperidone using a nine-step reaction, including condensation, methyl­ation, oximation, hydrolysis, esterification, ammonolysis, Hoffmann degradation, tert-butoxy­carbonyl protection and methyl­ation. The E configuration of the methyl­oxime geometry of the compound is confirmed. PMID:21581872

Wan, Zhilong; Chai, Yun; Liu, Mingliang; Guo, Huiyuan

2009-01-01

27

tert-Butyl 3-[N-(tert-butoxy-carbonyl)methyl-amino]-4-methoxy-imino-3-methyl-piperidine-1-carboxyl-ate.  

PubMed

The title compound, C(18)H(33)N(3)O(5), was prepared from N-tert-butoxy-carbonyl-4-piperidone using a nine-step reaction, including condensation, methyl-ation, oximation, hydrolysis, esterification, ammonolysis, Hoffmann degradation, tert-butoxy-carbonyl protection and methyl-ation. The E configuration of the methyl-oxime geometry of the compound is confirmed. PMID:21581872

Wan, Zhilong; Chai, Yun; Liu, Mingliang; Guo, Huiyuan

2009-01-01

28

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...

29

Biomarkers of exposure to aromatic hydrocarbons and methyl tert-butyl ether in petrol station workers.  

PubMed

This cross-sectional study was aimed at reconstructing the exposure to gasoline in 102 petrol station attendants by environmental and biological monitoring of benzene, toluene, ethylbenzene and xylene (BTEX) and biomonitoring of methyl tert-butyl ether (MTBE). Airborne BTEX were higher for manual refuelers than self-service assistants and were highly correlated with each other. Significant relationships were found between airborne BTX and the corresponding urinary solvents (U-BTX) and beween airborne B and urinary MTBE (U-MTBE). Smokers eliminated higher values of U-B, trans,trans-muconic (t,t-MA) and S-phenylmercapturic (S-PMA) acids but not U-MTBE. All these biomarkers were, however, significantly raised during the shift, independently from smoking. Linear regression confirmed that occupational exposure was a main predictor of U-MTBE, U-B and S-PMA values, both the latter confounded by smoking habits. The study supports the usefulness of biomonitoring even at low exposure levels. PMID:22458326

De Palma, Giuseppe; Poli, Diana; Manini, Paola; Andreoli, Roberta; Mozzoni, Paola; Apostoli, Pietro; Mutti, Antonio

2012-06-01

30

Sources, distribution and behaviour of methyl tert-butyl ether (MTBE) in the Tamar Estuary, UK.  

PubMed

Negligible information is currently available concerning levels of the fuel additive methyl tert-butyl ether (MTBE) in European estuaries or coastal environments. MTBE was measured at selected potentially contaminated harbours and marinas, and throughout an axial transect of the Tamar Estuary, UK. Headspace solid-phase microextraction was used in combination with GC-MS for its determination. MTBE was detected in water samples from all stations at concentrations ranging from a few ng/l to a maximum of 194 ng/l (in a semi-enclosed harbour). Elevated levels were generally associated with motor vehicle and boating activities. The Tamar road and rail bridges provided a major input to the lower estuary, downstream of which conservative mixing appeared depressed, probably through volatilisation and possibly through salting-out. The selected analytical system (using a Carboxen/PDMS fiber) proved both rapid and highly sensitive (with a detection limit of 6 ng/l). During method development, salinity was shown to have a major influence in controlling the extraction efficiency and it was found necessary to adjust salinity in all samples (to 75% saturation) prior to extraction. From these tests, we (for the first time) estimated the Setschenow ("salting-out") constant of MTBE to be 0.11 l/mol. PMID:15350404

Guitart, Carlos; Bayona, Josep M; Readman, James W

2004-11-01

31

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

32

Reaction calorimetry study of the liquid-phase synthesis of tert-butyl methyl ether  

SciTech Connect

The liquid-phase addition of methanol to isobutene to give tert-butyl methyl ether (MTBE) on the ion-exchange resin Lewatit K2631 has been studied in a calorimetric reactor. Heat capacity of MTBE and enthalpy of the MTBE synthesis reaction in the temperature range 312--333 K have been determined. MTBE heat capacity in the liquid phase has been found to obey the equation c[sub P] (J/mol[center dot]K) = 472.34 [minus] 2.468(T/K) + 0.005071(T/K)[sup 2]. At 298 K the standard molar reaction enthalpy is [Delta]H[degree] = [minus]33.8 kJ/mol. A method to estimate apparent activation energies from heat flow rate in a given reaction has been developed and proved to be valid for the MTBE synthesis. Using this method, an apparent activation energy of 91.1--95.2 kJ/mol is calculated. A [minus]3.8 kJ/mol value has been found for the adsorption enthalpy of methanol on the ion-exchange resin Lewatit K2631 by a combination of reaction calorimetry and thermogravimetry. This allows the calculation of an activation energy on the gel phase of the resin of 91 kJ/mol.

Sola, L.; Pericas, M.A.; Cunill, F.; Iborra, M. (Univ. de Barcelona (Spain). Dept. d'Enginyeria Quimica)

1994-11-01

33

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

PubMed

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

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

2014-03-01

34

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

35

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

36

Biodegradation of methyl tert -butyl ether as a sole carbon source by aerobic granules cultivated in a sequencing batch reactor  

Microsoft Academic Search

Aerobic granules efficient at degrading methyl tert-butyl ether (MTBE) were successfully developed in a well-mixed sequencing batch reactor (SBR). Treatment efficiency of MTBE\\u000a in the reactor during the stable operations exceeded 99.8%, and effluent MTBE was consistently below 800 ?g\\/L. The specific\\u000a MTBE degradation rate was observed to increase with increasing MTBE initial concentrations from 25 to 400 mg\\/L, peaked at\\u000a 18.2 mg-MTBE\\/g-VSS h,

Li-Li Zhang; R. Y. Zhu; J. M. Chen; W. M. Cai

2008-01-01

37

Biofiltration and inhibitory interactions of gaseous benzene, toluene, xylene, and methyl tert-butyl ether.  

PubMed

This study evaluated the individual and combined removal capacities of benzene, toluene, and xylene (B, T, and X) in the presence and absence of methyl tert-butyl ether (MTBE) in a polyurethane biofilter inoculated with a BTX-degrading microbial consortium, and further examined their interactive effects in various mixtures. In addition, Polymerase chain reaction-denaturing gradient gel electrophoresis and phylogenetic analysis of 16S rRNA gene sequences were used to compare the microbial community structures found in biofilters exposed to the various gases and gas mixtures. The maximum individual elimination capacities (MECs) of B, T, and X were 200, 238, and 400 g m(-3) h(-1), respectively. There was no significant elimination of MTBE alone. Addition of MTBE decreased the MECs of B,T, and X to 75, 100, and 300 g m(-3) h(-1), respectively, indicating that benzene was most strongly inhibited by MTBE. When the three gases were mixed (B + T + X), the removal capacities of individual B, T, and X were 50, 90, and 200 g m(-3) h(-1), respectively. These capacities decreased to 40, 50, and 100 g m(-3) h(-1) when MTBE was added to the mix. The MEC of the three-gas mixture (B + T + X) was 340 g m(-3) h(-1), and that of the four-gas mixture was 200 g m(-3) h(-1). Although MTBE alone was not degraded by the biofilter, it could be co-metabolically degraded in the presence of toluene, benzene, or xylene with the MECs of 34, 23, and 14 g m(-3) h(-1), respectively. The microbial community structure analysis revealed that two large groups could be distinguished based on the presence or absence of MTBE, and many of the dominant bacteria in the consortia were closely related to bacteria isolated from aromatic hydrocarbon-contaminated sites and/ or oil wastewaters. These findings provide important new insights into biofiltration and may be used to improve the rational design of biofilters for remediation of petroleum gas-contaminated airstreams according to composition types of mixed gases. PMID:16719116

Shim, Eun-Hwa; Kim, Jaisoo; Cho, Kyung-Suk; Ryu, Hee Wook

2006-05-01

38

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

39

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

40

Aerobic biodegradation of methyl tert-butyl ether by aquifer bacteria from leaking underground storage tank sites.  

PubMed

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-(14)C]MTBE was mineralized to (14)CO(2). 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

2001-12-01

41

Involvement of a Novel Enzyme, MdpA, in Methyl tert-Butyl Ether Degradation in Methylibium petroleiphilum PM1 ?  

PubMed Central

Methylibium petroleiphilum PM1 is a well-characterized environmental strain capable of complete metabolism of the fuel oxygenate methyl tert-butyl ether (MTBE). Using a molecular genetic system which we established to study MTBE metabolism by PM1, we demonstrated that the enzyme MdpA is involved in MTBE removal, based on insertional inactivation and complementation studies. MdpA is constitutively expressed at low levels but is strongly induced by MTBE. MdpA is also involved in the regulation of tert-butyl alcohol (TBA) removal under certain conditions but is not directly responsible for TBA degradation. Phylogenetic comparison of MdpA to related enzymes indicates close homology to the short-chain hydrolyzing alkane hydroxylases (AH1), a group that appears to be a distinct subfamily of the AHs. The unique, substrate-size-determining residue Thr59 distinguishes MdpA from the AH1 subfamily as well as from AlkB enzymes linked to MTBE degradation in Mycobacterium austroafricanum. PMID:18791002

Schmidt, Radomir; Battaglia, Vince; Scow, Kate; Kane, Staci; Hristova, Krassimira R.

2008-01-01

42

Kinetics and modeling of mixture effects during complete catalytic oxidation of benzene and methyl tert-butyl ether  

SciTech Connect

The performance of a catalytic incinerator depends on the nature of the compounds being oxidized and cannot be predicted simply by knowing the performance of the incinerator with pure-component model compounds. Considering the importance of mixture effects, an attempt was made to develop a combined model to predict the conversion when benzene and methyl tert-butyl ether (MTBE) are simultaneously oxidized. Complete catalytic oxidation of benzene and MTBE, singly and in mixtures, was investigated over a platinum catalyst. No inhibition effects were seen with benzene, but MTBE conversion was distinctly inhibited by benzene. A Mars-van Krevelen rate model was used to explain the results. Model parameters were obtained from pure-component experiments and then incorporated into a multicomponent model without any adjustment or additional rate parameters. The multicomponent model was able to predict the conversion of benzene and MTBE oxidation in the binary mixture using the pure-component data without adjustable parameters.

Dangi, S.; Abraham, M.A. [Univ. of Tulsa, OK (United States). Dept. of Chemical Engineering] [Univ. of Tulsa, OK (United States). Dept. of Chemical Engineering

1997-06-01

43

tert-butyl-substituted cyclooctatetraenes  

SciTech Connect

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

Miller, M.J. (Univ. of California, Berkeley); Lyttle, M.H.; Streitwieser, A. Jr.

1981-05-08

44

Di-tert-butyl 1-[2-hy-droxy-3-(methyl-sulfan-yl)prop-yl]hydrazine-1,2-di-carboxyl-ate  

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.

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

2014-01-01

45

Di-tert-butyl 1-[2-hy-droxy-3-(methyl-sulfan-yl)prop-yl]hydrazine-1,2-di-carboxyl-ate.  

PubMed

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

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

2014-08-01

46

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

PubMed

Methyl tert-butyl ether (MTBE) concentrations > or = 0.2 /microg/L were found in samples of untreated water in 18% of public-supply wells (n = 284) and 9.1% of private domestic wells (n = 264) sampled in 2005 and 2006 in New Hampshire. In counties that used reformulated gasoline (RFG), MTBE occurred at or above 0.2 microg/L in 30% of public- and 17% of private-supply wells. Additionally, 52% of public-supply wells collocated with fuel storage and 71% of mobile home park wells had MTBE. MTBE occurrence in public-supply wells was predicted by factors such as proximity to sources of fuel, land use, and population density, as well as low pH and distance from mapped lineaments. RFG use, land-use variables, and pH were important predictors of private-well MTBE occurrence. Variables representing sources of MTBE, such as the distance to known fuel sources, were not significant predictors of MTBE occurrence in private-supply wells. It is hypothesized that private wells may become contaminated from the collective effects of sources in high population areas and from undocumented incidental releases from onsite or proximal gasoline use. From 2003 to 2005, MTBE occurrence decreased in 63 public-supply wells and increased in 60 private-supply wells, but neither trend was statistically significant. PMID:18323087

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

2008-02-01

47

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

48

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

49

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

SciTech Connect

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

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

2007-03-01

50

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

51

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

SciTech Connect

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

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

1996-12-31

52

Evaluation of methyl tert-butyl ether (MTBE) as an interference on commercial breath-alcohol analyzers.  

PubMed

Anecdotal reports suggest that high environmental or occupational exposures to the fuel oxygenate methyl tert-butyl ether (MTBE) may result in breath concentrations that are sufficiently elevated to cause a false positive on commercial breath-alcohol analyzers. We evaluated this possibility in vitro by establishing a response curve for simulated breath containing MTBE in ethanol. Two types of breath-alcohol analyzers were evaluated. One analyzer's principle of operation involves in situ wet chemistry (oxidation of ethanol in a potassium dichromate solution) and absorption of visible light. The second instrument uses a combination of infrared absorption and an electrochemical sensor. Both types of instruments are currently used, although the former method represents older technology while the latter method represents newer technology.The percent blood alcohol response curve was evaluated over a breath concentration range thought to be relevant to high-level environmental or occupational exposure (0-361 microg/l). Results indicate that MTBE positively biases the response of the older technology Breathalyzer when evaluated as a single constituent or in combination with ethanol. We conclude that a false positive is possible on this instrument if the MTBE exposure is very high, recent with respect to testing, and occurs in combination with ethanol consumption. The interference can be identified on the older technology instrument by a time dependent post-reading increase in the instrument response that does not occur for ethanol alone. In contrast, the newer technology instrument using infrared and electrochemical detectors did not respond to MTBE at lower levels (0-36 microg/l), and at higher levels (>72 microg/l) the instrument indicated an "interference" or "error". For this instrument, a false positive does not occur even at high MTBE levels in the presence of ethanol. PMID:11728735

Buckley, T J; Pleil, J D; Bowyer, J R; Davis, J M

2001-12-01

53

[Environmental and biological monitoring of exposure to monoaromatic hydrocarbons and to methyl tert-butyl ether in a group of petrol station workers].  

PubMed

The aim of the study was to evaluate biomarkers of exposure to gasoline in petrol station workers by a combined approach of environmental and biological monitoring. The personal exposure to benzene, toluene, ethylbenzene and xylene (BTEX) and the urinary levels of BTEX, methyl tert-butyl ether (U-MTBE), trans,trans-muconic (t,t-MA) and S-phenylmercapturic acids (S-PMA) and cotinine were determined by mass spectrometry coupled chromatographic techniques. U-MTBE levels were strictly influenced by occupational exposure to gasoline, whereas both U-B and S-PMA levels depended from smoking habits and occupational exposure. PMID:23393799

De Palma, G; Poli, D; Manini, P; Andreoli, R; Mozzoni, P; Apostoli, P; Mutti, A

2011-01-01

54

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

55

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

56

tert-Butyl 4-carbamoyl-3-methoxy-imino-4-methyl-piperidine-1-carboxyl-ate.  

PubMed

The title compound, C(13)H(23)N(3)O(4), was prepared starting from ethyl N-benzyl-3-oxopiperidine-4-carboxyl-ate through a nine-step reaction, including hydrogenation, Boc (tert-butoxy-carbon-yl) protection, methyl-ation, oximation, hydrolysis, esterification and ammonolysis. In the crystal structure, mol-ecules are linked by inter-molecular N-H?O hydrogen bonds to form a porous three-dimensional network with solvent-free hydro-phobic channels extending along the c axis. PMID:21581272

Wang, Juxian; Liu, Mingliang; Cao, Jue; Wang, Yucheng

2008-01-01

57

tert-Butyl 4-carbamoyl-3-methoxy-imino-4-methyl-piperidine-1-carboxyl-ate  

PubMed Central

The title compound, C13H23N3O4, was prepared starting from ethyl N-benzyl-3-oxopiperidine-4-carboxyl­ate through a nine-step reaction, including hydrogenation, Boc (tert-butoxy­carbon­yl) protection, methyl­ation, oximation, hydrolysis, esterification and ammonolysis. In the crystal structure, mol­ecules are linked by inter­molecular N—H?O hydrogen bonds to form a porous three-dimensional network with solvent-free hydro­phobic channels extending along the c axis. PMID:21581272

Wang, Juxian; Liu, Mingliang; Cao, Jue; Wang, Yucheng

2008-01-01

58

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...

59

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

60

tert-butyl-substituted cyclooctatetraenes  

Microsoft Academic Search

Reaction of cyclooctatetraene (COT) with tert-butyllithium provides a convenient synthesis of tert-butylcyclooctatetraene, 4. As a byproduct of the reaction mixture, 1,4-di-tert-butylcyclooctatriene has been isolated and converted to 1,4-di-tert-butylcyclooctatetraene, 5, by deprotonation with potassium amide and oxidation with iodine. An independent synthesis of 5 was developed from 9-oxabicyclo(6.1.0)octa-2,4,6-triene (cyclooctatetraene oxide), 9. The highly substituted compound 1,3,5,7-tetra-tert-butylcyclooctatetraene (6) has been prepared in

Michael J. Miller; Matthew H. Lyttle; Andrew Streitwieser

1981-01-01

61

Evaluation of standard methods for the analysis of methyl tert-butyl ether and related oxygenates in gasoline-contaminated groundwater.  

PubMed

The U.S. Environmental Protection Agency (EPA) now requires monitoring of oxygenate compounds in groundwater at leaking underground storage tank (LUST) sites nationwide. Three purge-and-trap gas chromatography methods most commonly employed for this purpose were tested, and their performance as a function of total petroleum hydrocarbon (TPH) content of the sample matrix was determined. Tests included a formal method evaluation, a round-robin study, and a split-sample study (424 groundwater samples). Consistently good results were achieved with EPA Method 8240B/60B (mass spectrometry) and ASTM Method D4815 (flame ionization detection) when five oxygenates were monitored in reagent water and gasoline. However, one protocol routinely employed for analysis of LUST samples had serious limitations: EPA Method 8020A/21B (photoiozination detection) was unfit for monitoring of tert-butyl alcohol (TBA) and frequently yielded false-positive (12-50% of samples) and inaccurate results when ether oxygenates were monitored in aqueous samples containing high concentrations of TPH (> 1,000 microg/ L). Thus, care should be taken in the analysis of LUST databases populated with EPA Method 8020/21 data because results reported for methyl tert-butyl ether (MTBE) in samples containing high levels of TPH have a high likelihood of being inaccurate or false-positive. For all three methods, detection limits determined in reagent water were sufficiently low for monitoring MTBE at the stringent primary (13 microg/L) and secondary (5 microg/L) action levels set by the state of California. PMID:11348088

Halden, R U; Happel, A M; Schoen, S R

2001-04-01

62

Structure of the acetylation and formylation products of 2-tert-butyl-5-methylthiophene and 2,5-di-tert-butylthiophene  

Microsoft Academic Search

Summary 1.It was shown that, in the formylation, acetylation, and bromination of 2-tert-butyl-5-methylthiophene, the new substituent enters the 4-position (the ß-position next to the methyl).2.It was shown that, in the acetylation of 2,5-di-tert-butylthiophene in presence of stannic chloride, no migration of the tert-butyl group occurs.3.It was shown that it is possible to prepare thiophenecarboxylic acids containing a-alkyl radicals (methyl, tert-butyl)

Ya. L. Goldfarb; P. A. Konstantinov

1957-01-01

63

N-(4-tert-Butyl-benz-yl)phthalimide  

PubMed Central

The mol­ecule of the title compound [systematic name: 2-(4-tert-butyl­benz­yl)isoindoline-1,3-dione], C19H19NO2, is V-shaped with a dihedral angle of 74.15?(7)° between the mean planes of the phthalimide unit and the benzene ring. The methyl groups of the tert-butyl substituent are disordered over two sets of positions, with an occupancy ratio of 0.700?(4):0.300?(4). In the crystal, inter­molecular C—H?O hydrogen bonds link adjacent mol­ecules into centrosymmetric dimers. An additional weak C—H?O contact, together with weak C—H?? and ?–? inter­actions [centroid–centroid distance = 3.961?(2)?Å] generate a three-dimensional network. PMID:21583486

Li, Jiang-Sheng; Simpson, Jim; Li, Xun

2009-01-01

64

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

65

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

PubMed Central

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

2014-01-01

66

Naturally Occurring Bacteria Similar to the Methyl tert-Butyl Ether (MTBE)-Degrading Strain PM1 Are Present in MTBE-Contaminated Groundwater  

PubMed Central

Methyl tert-butyl ether (MTBE) is a widespread groundwater contaminant that does not respond well to conventional treatment technologies. Growing evidence indicates that microbial communities indigenous to groundwater can degrade MTBE under aerobic and anaerobic conditions. Although pure cultures of microorganisms able to degrade or cometabolize MTBE have been reported, to date the specific organisms responsible for MTBE degradation in various field studies have not be identified. We report that DNA sequences almost identical (99% homology) to those of strain PM1, originally isolated from a biofilter in southern California, are naturally occurring in an MTBE-polluted aquifer in Vandenberg Air Force Base (VAFB), Lompoc, California. Cell densities of native PM1 (measured by TaqMan quantitative PCR) in VAFB groundwater samples ranged from below the detection limit (in anaerobic sites) to 103 to 104 cells/ml (in oxygen-amended sites). In groundwater from anaerobic or aerobic sites incubated in microcosms spiked with 10 ?g of MTBE/liter, densities of native PM1 increased to approximately 105 cells/ml. Native PM1 densities also increased during incubation of VAFB sediments during MTBE degradation. In controlled field plots amended with oxygen, artificially increasing the MTBE concentration was followed by an increase in the in situ native PM1 cell density. This is the first reported relationship between in situ MTBE biodegradation and densities of MTBE-degrading bacteria by quantitative molecular methods. PMID:12732529

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

2003-01-01

67

Aerobic degradation of methyl tert-butyl ether in a closed symbiotic system containing a mixed culture of Chlorella ellipsoidea and Methylibium petroleiphilum PM1.  

PubMed

The contamination of groundwater by methyl tert-butyl ether (MTBE) is one of the most serious environmental problems around the world. MTBE degradation in a closed algal-bacterial symbiotic system, containing a mixed culture of Methylibium petroleiphilum PM1 and Chlorella ellipsoidea, was investigated. The algal-bacterial symbiotic system showed increased MTBE degradation. The MTBE-degradation rate in the mixed culture (8.808 ± 0.007 mg l(-1) d(-1)) was higher than that in the pure bacterial culture (5.664 ± 0.017 mg l(-1) d(-1)). The level of dissolved oxygen was also higher in the mixed culture than that in the pure bacterial culture. However, the improved efficiency of MTBE degradation was not in proportional to the biomass of the alga. The optimal ratio of initial cell population of bacteria to algae was 100:1. An immobilized culture of mixed bacteria and algae also showed higher MTBE degradation rate than the immobilized pure bacterial culture. A mixed culture with algae and PM1 immobilized separately in different gel beads showed higher degradation rate (8.496 ± 0.636 mg l(-1) d(-1)) than that obtained with algae and PM1 immobilized in the same gel beads (5.424 ± 0.010 mg l(-1) d(-1)). PMID:21112690

Zhong, Weihong; Li, Yixiao; Sun, Kedan; Jin, Jing; Li, Xuanzhen; Zhang, Fuming; Chen, Jianmeng

2011-01-30

68

The relationship between crystal structure and NMR relaxation in molecular solids with tert-butyl groups  

NASA Astrophysics Data System (ADS)

We correlate an X-ray determination of the molecular and crystal structures of 2- tert-butylanthracene and 2- tert-butylanthraquinone reported here with the previously reported dynamical nuclear magnetic resonance determination of the motions of the tert-butyl groups and their resident methyl groups in the solid state [P.A. Beckmann, K.S. Burbank, M.M.W. Lau, J.N. Ree, T.L. Weber, Chem. Phys. 290 (2003) 241].

Rheingold, Arnold L.; DiPasquale, Antonio G.; Beckmann, Peter A.

2008-04-01

69

Headspace-solid-phase microextraction using a dodecylsulfate-doped polypyrrole film coupled to ion mobility spectrometry for analysis methyl tert-butyl ether in water and gasoline.  

PubMed

A simple and sensitive method for the determination of methyl tert-butyl ether (MTBE) in water using headspace-solid-phase microextraction (HS-SPME) at sub-ng mL(-1) concentrations is described. The analysis was carried out using a cooled SPME fiber coated with a film of dodecylsulfate-doped polypyrrole coupled to ion mobility spectrometry equipped with corona discharge ionization. The headspace-solid-phase microextraction experimental procedures to extract MTBE in water samples were optimized with a dodecylsulfate-doped polypyrrole coated fiber at a 30 min extraction time, extraction temperature of 40 degrees C, sodium chloride concentration of 2.5 mol L(-1) and desorption temperature of 140 degrees C. Two linear calibration curves respectively in the ranges of 2-17 ng mL(-1) and 10-70 ng mL(-1) with detection limits of 0.7 ng mL(-1) and 4.9 ng mL(-1) were obtained. Relative standard deviations for three replicates in water samples were <10%. The capability of dodecylsulfate-doped polypyrrole to extract MTBE has been compared with the results obtained based on the literature data for commercial fiber. The results shows that dodecylsulfate-doped polypyrrole, as a solid-phase microextraction fiber coating, is suitable for successful extraction of MTBE having detection limits comparable to what obtained with commercial fibers. Finally, the proposed method was applied to the analysis of MTBE in three ground water samples and regular unleaded gasoline from petrol station in Tehran central district, Iran. PMID:19427121

Alizadeh, Naader; Jafari, Mostafa; Mohammadi, Abdorreza

2009-09-30

70

Optically active 1,1?-di- tert-butyl-2,2?-dibenzophosphetenyl: a highly strained P-stereogenic diphosphine ligand  

Microsoft Academic Search

Both enantiomers of 1,1?-di-tert-butyl-2,2?-dibenzophosphetenyl were prepared from 2-bromobenzyl chloride and tert-butyldichlorophosphine. These ligands exhibited excellent enantioselectivity in the rhodium catalyzed asymmetric hydrogenation of methyl ?-acetylamidocinnamate.

Tsuneo Imamoto; Karen V. L Crépy; Kosuke Katagiri

2004-01-01

71

Bis-(3-tert-butyl-pyridine-?N)bis-(4-tert-butyl-pyridine-?N)bis(thio-cyanato-?N)cadmium  

PubMed Central

The asymmetric unit of the title compound, [Cd(NCS)2(C9H13N)4], consists of one CdII cation located on a centre of inversion, one thio­cyanate anion, one 3-tert-butyl­pyridine ligand and one 4-tert-butyl­pyridine ligand in general positions. The tert-butyl group of the 4-tert-butyl­pyridine ligand is disordered over two sets of sites in a 0.25:0.75 ratio and was refined using a split model. The CdII cation is coordinated by six N atoms of four tert-butyl­pyridine ligands and two N-bonded thio­cyanate anions within a slightly distorted octa­hedral coordination environment. PMID:23284351

Reinert, Thorben; Jess, Inke; Nather, Christian

2012-01-01

72

Vapor-Liquid Equilibrium in the Mixture 1,2-Dichloroethane C2H4Cl2 + C5H12O tert-Butyl methyl ether (EVLM1311, LB5739_E)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume C 'Binary Liquid Systems of Nonelectrolytes III' of Volume 26 'Heats of Mixing, Vapor-Liquid Equilibrium, and Volumetric Properties of Mixtures and Solutions' of Landolt-Börnstein Group IV 'Physical Chemistry'. It contains the Chapter 'vapor-Liquid Equilibrium in the Mixture 1,2-Dichloroethane C2H4Cl2 + C5H12O tert-Butyl methyl ether (EVLM1311, LB5739_E)' providing data from direct measurement of pressure at variable temperature and constant mole fraction in liquid phase.

Cibulka, I.; Fontaine, J.-C.; Sosnkowska-Kehiaian, K.; Kehiaian, H. V.

73

Synthesis, characterization, and reaction chemistry of tert-butyl hypofluorite  

SciTech Connect

tert-Butyl hypofluorite ((CH[sub 3])[sub 3]COF) can be synthesized by the low-temperature reaction of elemental fluorine with tert-butyl alcohol dissolved in propionitrile or acetonitrile. The isolated compound, which melts around -94[degrees]C and has an extrapolated boiling point of about +40[degrees]C, has been characterized by mass, NMR, and IR spectrometry. The [sup 19]F NMR shift of +67 ppm lies between the corresponding shifts of HOF and CH[sub 3]OF and implies a rather high O-F bond energy. Although sterically crowded, tert-butyl hypofluorite adds to olefins to form [beta]-fluoro-tert-butoxy compounds. Addition is mainly in an anti mode, and the regioselectivity corresponds to the action of a hitherto unknown tert-butoxylium electrophile. Also formed are adducts containing F and CH[sub 2]CN, the latter deriving from the acetonitrile solvent. 19 refs., 1 tab.

Appelman, E.H.; French, D. (Argonne National Lab., IL (United States)); Mishani, E.; Rozen, S. (Tel-Aviv Univ. (Israel))

1993-02-24

74

Bis(?-2-tert-butyl­phenyl­imido-1:2?2 N:N)chlorido-2?Cl-(diethyl ether-1?O)(2?5-penta­methyl­cyclo­penta­dien­yl)lithiumtantalum(V)  

PubMed Central

In the title compound, [LiTa(C10H15)(C10H13N)2Cl(C4H10O)], the TaV atom is coordinated by a ?5-penta­methyl­cyclo­penta­dienyl (Cp*) ligand, a chloride ion and two N-bonded 2-tert-butyl­phenyl­imide dianions. With respect to the two N atoms, the chloride ion and the centroid of the Cp* ring, the tantalum coordination geometry is approximately tetra­hedral. The lithium cation is bonded to both the 2-tert-butyl­phenyl­imide dianions and also a diethyl ether mol­ecule, in an approximate trigonal planar arrangement. The Ta?Li separation is 2.681?(15)?Å. In the crystal, a weak C—H?Cl inter­action links the mol­ecules. When compared to the 2,6-diisopropyl­phenyl­imide analogue (‘the Wigley derivative’) of the title compound, the two structures are conformationally matched with an overall r.m.s. difference of 0.461Å. PMID:21754594

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

2011-01-01

75

Estimated daily intakes of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) antioxidants in Korea  

Microsoft Academic Search

The study was conducted to establish the estimated daily intake (EDI) of antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tert-butyl hydroquinone (TBHQ) in Korea. The EDIs were obtained from two sources. One of the estimations was based on the analytical determination of BHA, BHT and TBHQ in 12 food categories (ten food categories for TBHQ) and on

H.-J. Suh; M.-S. Chung; Y.-H. Cho; J.-W. Kim; D.-H. Kim; K.-W. Han; C.-J. Kim

2005-01-01

76

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

USGS Publications Warehouse

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

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

2002-01-01

77

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

78

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

Microsoft Academic Search

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

Yang Li; Wentao Gao

2012-01-01

79

Chlorination of 3,6-di-tert-butyl-o-benzoquinone by sulfuryl chloride  

Microsoft Academic Search

1.A study of the chlorination of 3,6-di-tert-butylpyrocatechol and its corresponding quinone and 4-chloro-3,6-di-tert-butyl-o-benzoquinone by sulfuryl chloride showed that this method may serve as a preparative method for obtaining 4-chloro-3,6-di-tert-butyl-o-benzoquinone and 4,5-dichloro-3,6-di-tert-butyl-o-benzoquinone.2.A mechanism was established for the reaction of 4-X-3,6-di-tert-butyl-o-benzoquinone (X=H, Cl) with SO2Cl2 involving the protonation of SO2Cl2.

V. A. Garnov; V. I. Nevodchikov; G. A. Abakumov; V. K. Cherkasov; L. G. Abakumova; Yu. A. Kurskii

1985-01-01

80

Trans-bis-(3-tert-butyl-pyridine-?N)bis-(4-tert-butyl-pyridine-?N)bis-(thio-cyanato-?N)manganese(II)  

PubMed Central

The asymmetric unit of the title compound [Mn(NCS)2(C9H13N)4] consists of one MnII cation located on a center of inversion, one thio­cyanato anion, one 3-tert-butyl­pyridine ligand and one 4-tert-butyl­pyridine ligand in general positions. The tert-butyl group of the 4-tert-butyl­pyridine ligand is disordered over two sets of sites in a 0.60:0.40 ratio. The MnII cation is coordinated by six N atoms of four tert-butyl­pyridine ligands and two N-bonded thio­cyanato anions within a slightly distorted octa­hedral coordination environment. PMID:23284325

Reinert, Thorben; Jess, Inke; Nather, Christian

2012-01-01

81

Tris(tert-butyl isocyanide-?C)carbonylnickel(0)  

PubMed Central

The title compound, [Ni(C5H9N)3(CO)], was prepared from Ni(CO)4 and a tenfold excess of tert-butyl isocyanide. It crystallizes with two symmetry-independent mol­ecules per asymmetric unit. The central Ni atom of each independent mol­ecule has a nearly perfect tetra­hedral coordination environment, comprising one carbon monoxide and three isocyanide ligands. The title compound is the first structurally characterized Ni0 compound with a mixed CO/RNC coordination. PMID:21202996

Imhof, Wolfgang; Gorls, Helmar; Halbauer, Kathi

2008-01-01

82

Investigation of methyl tert-butyl ether levels in river-, ground-, and sewage-waters analyzed using a purge-and-trap interfaced to a gas chromatograph-mass spectrometer.  

PubMed

River water collected from 27 sites in 21 rivers, groundwater from 66 sites in 34 cities, and 2 sewage plants in the Niigata Prefecture, Japan (total 301 samples) were analyzed for methyl tert-butyl ether (MTBE) using an improved purge-and-trap-GC-MS method. The amount of MTBE found in water samples from the 27 river sites ranged from 0.003 to 5.3 microg l(-1). MTBE was found in all 27 sites during winter but it was found at only 9 sites and 14 sites, respectively, during the summer. MTBE was found most frequently (in 21 sites) at levels ranging from 0.003 to 0.009 microg l(-1) during February. The highest levels of MTBE were always found in the samples collected from the same site. The amount of MTBE found in sewage water samples ranged from <0.003 to 0.025 microgl(-1). No significant differences were observed between the amounts of MTBE recovered from inflow and outflow waters. Relatively high levels (0.02-0.034 microg l(-1) ) of MTBE were found in January at two sites, which were located on the upper course of the Shinano River. MTBE levels ranged from 0.004 to 0.035 microgl(-l) and from 0.005 to 0.041 microgl(-1) at the mouths of the Shinano River and Agano River, respectively. The levels of MTBE in groundwater collected from 66 sites in 34 cities in Niigata Prefecture ranged from <0.003 to 5.9 microg l(-1). PMID:15794567

Tanabe, Akiko; Tsuchida, Yuriko; Ibaraki, Tsuyoshi; Kawata, Kuniaki; Yasuhara, Akio; Shibamoto, Takayuki

2005-02-25

83

Bis(2-hydroxy-3-tert-butyl-5-methyl-phenyl)-methane (bis-phenol) is a potent and selective inhibitor of the secretory pathway Ca²? ATPase (SPCA1).  

PubMed

The secretory pathway Ca(2+) ATPase (SPCA) provides the Golgi apparatus with a Ca(2+) supply essential for Ca(2+)-dependent enzymes involved in the post-translational modification of proteins in transit through the secretory pathway. Ca(2+) in the Golgi apparatus is also agonist-releasable and plays a role in hormone-induced Ca(2+) transients. Although the Ca(2+) ATPase inhibitors thapsigargin is more selective for the sarcoplasmic-endoplasmic reticulum Ca(2+) ATPase (SERCA) than for SPCA, no inhibitor has been characterised that selectively inhibits SPCA. A number of inhibitors were assessed for their selectivity to the human SPCA1d compared to the more ubiquitous human SERCA2b. Each isoform was over-expressed in COS-7 cells and the Ca(2+)-dependent ATPase activity measured in their microsomal membranes. Both bis(2-hydroxy-3-tert-butyl-5-methyl-phenyl)methane(bis-phenol) and 2-aminoethoxydiphenylborate (2-APB) selectively inhibited SPCA1d (with IC(50) values of 0.13 ?M and 0.18 mM, respectively), which were of 62- and 8.3-fold greater potency than the values for hSERCA2b (IC(50) values; 8.1 ?M and 1.5mM, respectively). Other inhibitors tested such as bis-phenol-A, tetrabromobisphenol-A and trifluoperazine inhibited both Ca(2+) ATPases similarly. Furthermore, bis-phenol was able to mobilize Ca(2+) in cells that had been pre-treated with thapsigargin. Therefore we conclude that given the potency and selectivity of bis-phenol it may prove a valuable tool in further understanding the role of SPCA in cellular processes. PMID:22796571

Lai, Pei; Michelangeli, Francesco

2012-08-01

84

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

85

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

Microsoft Academic Search

A comparative test in mice for pulmonary toxicity between butylated hydroxytoluene (2,6-di-tert.-butyl-4-methylphenol, BHT) and 2,6-di-tert.-butyl-4-(alpha, alpha, alpha-2H3)methylphenol (BHT-d3) showed a significantly lower toxic potency of the latter. The rate of in vitro BHT metabolism to 2,6-di-tert.-butyl-4-methylene-2,5-cyclohexadienone (BHT-QM) was slowed by deuterating BHT in the 4-methyl group. On the other hand, the rate of in vitro metabolism to 2,6-di-tert.-butyl-4-hydroxy-4-methyl-2,5-cyclohexadienone (BHT-OH) was

T. Mizutani; K. Yamamoto; K. Tajima

1983-01-01

86

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

SciTech Connect

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

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

1983-06-30

87

1-[(4-tert-Butyl-phen-yl)sulfon-yl]-1H-benzimidazole  

PubMed Central

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

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

2011-01-01

88

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

Microsoft Academic Search

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

Yang Li; Wentao Gao

2011-01-01

89

Di-tert-butyl N-{[1-(pyridin-4-yl)-1H-1,2,3-triazol-4-yl]methyl}iminodiacetate  

PubMed Central

In the title compound, C20H29N5O4, the pyridine ring makes a dihedral angle of 10.41?(16)° with the triazole ring, which exhibits an azo-like character. In the crystal, mol­ecules are linked by C—H?O and C—H?N hydrogen bonds, and C—H?? inter­actions involving a methyl group and the pyridine ring of a neighbouring mol­ecule, leading to the formation of a three-dimensional network. PMID:23284477

Francois, Alison; Marty, Louise; Picard, Claude; Mallet-Ladeira, Sonia; Benoist, Eric

2012-01-01

90

Discovery of 2-(4-((1 H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1 H-pyrazol-3-yl)-5- tert-butyl-1,3,4-thiadiazole (GCC2680) as a potent, selective and orally efficacious cannabinoid-1 receptor antagonist  

Microsoft Academic Search

Structure–activity relationship studies in a series of diarylpyrazolyl thiadiazoles identified cannabinoid-1 receptor antagonists with excellent potency and selectivity. Based on its exceptional in vivo efficacy in animal models and its favorable pharmacokinetic and toxicological profiles, 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) was selected as a preclinical candidate for the treatment of obesity.

Jinhwa Lee; Hee Jeong Seo; Suk Ho Lee; Jeongmin Kim; Myung Eun Jung; Sung-Han Lee; Kwang-Seop Song; Junwon Lee; Suk Youn Kang; Min Ju Kim; Mi-Soon Kim; Eun-Jung Son; MinWoo Lee; Ho-Kyun Han

2010-01-01

91

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

SciTech Connect

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

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

1985-01-25

92

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

93

catena-Poly[[di-tert-butyl-tin(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

94

Influence of Temperature on Thermodynamic Properties of Methyl t-Butyl Ether (MTBE) + Gasoline Additives  

NASA Astrophysics Data System (ADS)

The densities and sound speeds of binary mixtures of methyl tert-butyl ether (MTBE) + (benzene, toluene, ethylbenzene, isooctane, tert-butyl alcohol) have been measured at temperatures from 288.15 to 323.15 K and at atmospheric pressure over the complete concentration range. The experimental excess volumes and deviations of isentropic compressibility were calculated. The deviation of isentropic compressibility data have been analyzed in terms of different theoretical models; adequate agreement between the experimental and predicted values is obtained. The data from this study improve the data situation related to gasoline additives and help to understand the MTBE volumetric and acoustic behavior for various chemical systems.

Gonzalez-Olmos, R.; Iglesias, M.; Goenaga, J. M.; Resa, J. M.

2007-08-01

95

Synthesis and Characterization of a Gasoline Oxygenate, Ethyl tertButyl Ether  

Microsoft Academic Search

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

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

2002-01-01

96

Formation of 8-hydroxydeoxyguanosine in calf thymus DNA treated with tert-butylhydroquinone, a major metabolite of butylated hydroxyanisole  

Microsoft Academic Search

Oxidative DNA damage caused by butylated hydroxyanisole (BHA), 2-tert-butyl(1,4)hydroquinone (TBHQ, a metabolite of BHA) and 2,5-di-tert-butyl(1,4)hydroquinone (DTBHQ), as well as 2,6-di-tert-butyl(1,4)benzoquinone (BHTQ, a metabolite of butylated hydroxytoluene), was evaluated by measuring the formation of 8-hydroxy-deoxyguanosine (80HdG) in calf thymus DNA. 80HdG formation was greatly increased by TBHQ in a concentration-dependent manner. This effect was strongly enhanced by CuCl2 and suppressed

Fumiko Nagai; Tomoko Okubo; Keiko Ushiyama; Kanako Satoh; Itsu Kano

1996-01-01

97

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

98

Synthesis and insecticidal evaluation of novel N'-tert-butyl-N'-substitutedbenzoyl-N-5-chloro-6-chromanecarbohydrazide derivatives.  

PubMed

A series of novel N'-tert-butyl- N'-substitutedbenzoyl-N-5-chloro-6-chromanecarbohydrazide derivatives were synthesized, and their larvicidal activities against Oriental armyworm were evaluated. The results of bioassays indicated that most of these title compounds exhibit higher larvicidal activities than RH-5849, and several of them somewhat lower than the commercial insecticide tebufenozide. The larvicidal activities are strongly associated with the types and patterns of substitution on the benzene, and 3,5-dimethyl, 2-nitro-4-chloro and 3-methyl derivatives are most prominent in increasing activity. Toxicity assays indicated that these derivatives could induce a premature, abnormal, and lethal larval moult. PMID:17897833

Mao, Chun-Hui; Wang, Kai-Liang; Wang, Zi-Wen; Ou, Xiao-Ming; Huang, Run-Qiu; Bi, Fu-Chun; Wang, Qing-Min

2008-01-01

99

N-4-Methansulfonamidobenzyl-N0 -2-substituted-4-tert-butyl-benzyl  

E-print Network

N-4-Methansulfonamidobenzyl-N0 -2-substituted-4-tert-butyl-benzyl thioureas as potent vanilloid of N-4-methansulfonamidobenzyl-N0 -2-substituted-4-tert-butylbenzyl thioureas were prepared, such as capsazepine6 (IC50=0.65 mM), N-alkyl glycine trimer7 (IC50=2 mM), pyrrolidine- thiourea8 (IC50=3 mM), and N,N0

Suh, Young-Ger

100

Temperature dependence of bromine kinetic isotope effects for reactions of n-butyl and tert-butyl bromides  

Microsoft Academic Search

Techniques for the measurement of bromine leaving group kinetic isotope effects (KIE) are described. Experimental values at 20°C for the solvolysis of tert-butyl bromide (0.045 M) in methanol with 0.3 M 2,6-lutidine and for the reaction of n-butyl bromide (0.047 M) with thiophenoxide anion (0.052 M) in 0.25 M lithium methoxide\\/methanol solvent are 1.003 10 (+-0.000 04) and 1.00l 69

John F. Willey; James W. Taylor

1980-01-01

101

Di-tert-butyl Peroxide-Promoted ?-Alkylation of ?-Amino Carbonyl Compounds by Simple Alkanes.  

PubMed

A di-tert butyl peroxide (DTBP)-promoted ?-alkylation of ?-amino carbonyl compounds by simple alkanes is developed, proceeding through dual sp(3) C-H bonds cleavage. The reaction was applicable for ?-amino ketones and ?-amino esters, providing a facile pathway for the ?-functionalization of these substrates. The radical pathway is involved in this transformation. PMID:25243610

Peng, Haibo; Yu, Jin-Tao; Jiang, Yan; Yang, Haitao; Cheng, Jiang

2014-10-17

102

Efficient indoles and anilines syntheses employing tert-butyl sulfinamide as ammonia surrogate  

Microsoft Academic Search

tert-Butyl sulfinamide is an ammonia equivalent for the palladium-catalyzed amination of aryl bromides and aryl chlorides. Using these amine derivatives, it has been observed that indoles and anilines with sensitive functional groups can be readily prepared. This surrogate has also been used for the synthesis of indoles from 2-halophenols using palladium catalyzed cross coupling reaction as the key step.

Anjanappa Prakash; Mullick Dibakar; Kumaravel Selvakumar; Kandasamy Ruckmani; Manickam Sivakumar

2011-01-01

103

Palladium/Tris(tert-butyl)phosphine-Catalyzed Suzuki Cross-Couplings in the Presence of Water  

E-print Network

Dipalladiumtris(dibenzylideneacetone)/tris(tert-butyl)phosphonium tetrafluoroborate/potassium fluoride dihydrate [Pd2(dba)3/[HP(t-Bu)3]BF4/KF?2?H2O] serves as a mild, robust, and user-friendly method for the efficient ...

Lou, Sha

104

1-[(E)-2-(5-tert-Butyl-2-hy-droxy-phen-yl)diazen-1-yl]naphthalen-2-ol  

PubMed Central

The non-H atoms of the title compound, C20H20N2O2, is located on a mirror plane except two methyl groups of the tert-butyl group. Intra­molecular N—H?O hydrogen bonds exist between the hy­droxy and diazenyl groups. In the crystal, mol­ecules are linked by weak C—H?O hydrogen bonds into supra­molecular chains running along the a-axis direction. PMID:24764925

Bougueria, Hassiba; Mili, Assia; Benosmane, Ali; Bouchoul, Abd el kader; Bouaoud, Salaheddine

2014-01-01

105

1-[(E)-2-(5-tert-Butyl-2-hy-droxy-phen-yl)diazen-1-yl]naphthalen-2-ol.  

PubMed

The non-H atoms of the title compound, C20H20N2O2, is located on a mirror plane except two methyl groups of the tert-butyl group. Intra-molecular N-H?O hydrogen bonds exist between the hy-droxy and diazenyl groups. In the crystal, mol-ecules are linked by weak C-H?O hydrogen bonds into supra-molecular chains running along the a-axis direction. PMID:24764925

Bougueria, Hassiba; Mili, Assia; Benosmane, Ali; Bouchoul, Abd El Kader; Bouaoud, Salaheddine

2014-02-01

106

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

107

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; Muller, Roland H.

2006-01-01

108

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.

109

Thin PDMS films using long spin times or tert-butyl alcohol as a solvent.  

PubMed

Thin polydimethylsiloxane (PDMS) films are frequently used in "lab on a chip" devices as flexible membranes. The common solvent used to dilute the PDMS for thin films is hexane, but hexane can swell the underlying PDMS substrate. A better solvent would be one that dissolves uncured PDMS but doesn't swell the underlying substrate. Here, we present protocols and spin curves for two alternatives to hexane dilution: longer spin times and dilution in tert-butyl alcohol. The thickness of the PDMS membranes under different spin speeds, spin times, and PDMS concentrations was measured using an optical profilometer. The use of tert-butyl alcohol to spin thin PDMS films does not swell the underlying PDMS substrate, and we have used these films to construct multilayer PDMS devices. PMID:19238212

Koschwanez, John H; Carlson, Robert H; Meldrum, Deirdre R

2009-01-01

110

Thin PDMS Films Using Long Spin Times or Tert-Butyl Alcohol as a Solvent  

PubMed Central

Thin polydimethylsiloxane (PDMS) films are frequently used in “lab on a chip” devices as flexible membranes. The common solvent used to dilute the PDMS for thin films is hexane, but hexane can swell the underlying PDMS substrate. A better solvent would be one that dissolves uncured PDMS but doesn't swell the underlying substrate. Here, we present protocols and spin curves for two alternatives to hexane dilution: longer spin times and dilution in tert-butyl alcohol. The thickness of the PDMS membranes under different spin speeds, spin times, and PDMS concentrations was measured using an optical profilometer. The use of tert-butyl alcohol to spin thin PDMS films does not swell the underlying PDMS substrate, and we have used these films to construct multilayer PDMS devices. PMID:19238212

Koschwanez, John H.; Carlson, Robert H.; Meldrum, Deirdre R.

2009-01-01

111

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

112

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

Microsoft Academic Search

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

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

2011-01-01

113

Voltammetric determination of the phenolic antioxidants 3-tert-butyl-4-hydroxyanisole and tert-butylhydroquinone at a polypyrrole electrode modified with a nickel phthalocyanine complex  

Microsoft Academic Search

The voltammetric behaviour of the antioxidants 3-tert-butyl-4-hydroxyanisole (BHA) and tert-butylhydroquinone (TBHQ), at a polymer electrode modified with nickel phthalocyanine as electron mediator, is described, and an electroanalytical method for the determination of these antioxidants based on their electrochemical oxidation on the modified electrode is proposed. Cyclic voltammograms showed well-defined oxidation peaks slightly shifted towards less positive potentials with respect to

C de la Fuente; J. A Acuña; M. D Vázquez; M. L Tascón; P Sánchez Batanero

1999-01-01

114

Cytoprotective and antioxidant activity of seabuckthorn (Hippophae rhamnoides L.) flavones against tert-butyl hydroperoxide-induced cytotoxicity in lymphocytes.  

PubMed

This study was designed to determine the cytoprotective activity of flavones of seabuckthorn (Hippophae rhamnoides L.) against tert-butyl hydroperoxide (tert-BOOH), used as an oxidant to induce oxidative damage, with lymphocytes as the model system. Addition of tert-BOOH (250 microM) to the cells resulted in enhanced cytotoxicity and free radical production. The intracellular calcium levels, caspase activity, and apoptosis were significantly increased following tert-BOOH treatment. Seabuckthorn flavones at the concentration of 100 microg/mL significantly inhibited tert-BOOH-induced cytotoxicity and free radical production and also restored the antioxidant status to that of control cells. Seabuckthorn flavones also significantly restricted tert-BOOH-induced apoptosis by decreasing intracellular calcium levels and caspase activity. The extract also decreased tert-BOOH-induced formation of DNA breaks by 30%. These observations suggest that the flavones of seabuckthorn have marked cytoprotective properties, which could be attributed to the antioxidant activity. PMID:19298209

Geetha, S; Ram, M Sai; Sharma, S K; Ilavazhagan, G; Banerjee, P K; Sawhney, R C

2009-02-01

115

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

116

Mechanism and temperature-dependent kinetics of the dehydration of tert-butyl alcohol in hot compressed liquid water  

SciTech Connect

In the presence of acid or base, or under neutral conditions, isobutylene is the only observed product of the reactions of tert-butyl alcohol in compressed liquid water at 225, 250, and 320 C. On the basis of a kinetic analysis of limited results at 250 C, an earlier paper concluded that tert-butyl alcohol dissociates as an Arrhenius acid at 250 C and thereby catalyzes its own dehydration to isobutylene. Kinetic analyses of the data sets contained in this paper do not corroborate the alleged ability of tert-butyl alcohol to protonate water. Instead, the authors find that hydronium ions formed by the ordinary dissociation of water are the primary catalytic agents for the dehydration reaction. In agreement with the earlier work, all three data sets are consistent with a heterolytic reaction mechanism involving protonated alcohol, carbocation, di-tert-butyl ether, and protonated ether as intermediates. The kinetics still suggest that tert-butyl alcohol weakly dissociated as a Bronsted acid at these conditions. Values of K{sub w} determined by the kinetic model enjoy good agreement with electrochemical values available in the literature. Values of the other parameters (rate constants) which compose the kinetic model are evaluated with less precision, and a novel method is proposed to estimate the uncertainty associated with each parameter.

Xu, X.; Antal, M.J. Jr. [Univ. of Hawaii, Honolulu, HI (United States)] [Univ. of Hawaii, Honolulu, HI (United States); Anderson, D.G.M. [Harvard Univ., Cambridge, MA (United States). Aiken Computation Lab.] [Harvard Univ., Cambridge, MA (United States). Aiken Computation Lab.

1997-01-01

117

The catalytic performances of silica supported aluminum, gallium and indium for the tert -butylation of aromatics  

Microsoft Academic Search

RHA-Al, RHA-Ga and RHA-In catalysts were synthesized by the direct incorporation of aluminum, gallium and indium ions, respectively,\\u000a into rice husk ash (RHA) silica at room temperature using the sol–gel method. The prepared catalysts were characterized by\\u000a physicochemical methods, viz. N2-adsorption, XRD, FT-IR, SEM-EDX, ICP-MS and Solid-state NMR. These catalysts were used to study the tert-butylation of benzene (Bz) and

Adil Elhag Ahmed; Farook Adam

2010-01-01

118

Phosphoamide – modified p- tert-butyl calix[4]arene and its sodium complexes  

Microsoft Academic Search

A new modified calix[4]arene, namely 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-bis[(tetramethyldiamidophosphinyl)oxy]calix[4]arene (L) has been prepared by reacting the parent calixarene with tetramethyldiamidophosphoric acid chloride, and its structure was solved by the X-ray diffraction method in the solid state and characterized in solution using 1H, 13C, 31P NMR and mass spectral (ES-MS and FAB-MS) data. The coordination ability of L towards Na+ showed the formation of

Vladimira Videva; Tania Tosheva; Anne-Sophie Chauvin; Stoycho Shenkov; Rosica Petrova; Rosario Scopelliti; Emil Tashev; Sabi Varbanov; Mariana Mitewa

2006-01-01

119

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

PubMed Central

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

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

2013-01-01

120

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

121

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

122

(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

123

Radical-scavenging activity of butylated hydroxytoluene (BHT) and its metabolites  

Microsoft Academic Search

To clarify the radical-scavenging activity of butylated hydroxytoluene (BHT), a food additive, stoichiometric factors (n) and inhibition rate constants (kinh) were determined for 2,6-di-tert-butyl-4-methylphenol (BHT) and its metabolites 2,6-di-tert-butyl-p-benzoquinone (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHA-CHO) and 3,5-di-tert-butyl-4-hydroperoxy-4-methyl-2,5-cyclohexadiene-1-one (BHT-OOH). Values of n and kinh were determined from differential scanning calorimetry (DSC) monitoring of the polymerization of methyl methacrylate (MMA) initiated by 2,2?-azobis(isobutyronitrile) (AIBN) or

Seiichiro Fujisawa; Yoshinori Kadoma; Ichiro Yokoe

2004-01-01

124

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

125

Synthesis and insecticidal activities of novel N-sulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. 1. N-alkoxysulfenate derivatives.  

PubMed

A series of novel N-alkoxysulfenyl-N'-tert-butyl-N, N'-diacylhydrazines were designed and synthesized as insect growth regulators by the key intermediates N-chlorosulfenyl-N'-tert-butyl-N, N'-diacylhydrazines, which were prepared for the first time. Compared to N'-tert-butyl-N, N'-diacylhydrazines, these N-alkoxysulfenyl derivatives displayed better solubility and improved hydrophobicities. The insecticidal activities of the new compounds were evaluated. The results of bioassays showed that the title compounds possessed a combination of strong stomach as well as contact poison property higher than the corresponding parent compounds. In particular, N-methoxysufenyl-N'-tert-butyl-N-4-ethylbenzoyl-N'-3,5-dimethylbenzoylhydrazide (IIIf) as a field testing candidate has higher stomach toxicities against oriental armyworm and beet armyworm than the corresponding parent compound RH-5992. Furthermore, the compound IIIf exhibits higher contact activities against oriental armyworm, Asian corn borer, tobacco cutworm, and cotton bollworm than RH-5992. The sulfenyl substituent was essential for high larvacidal activity. PMID:17941694

Zhao, Qiqi; Shang, Jian; Liu, Yuxiu; Wang, Kaiyun; Bi, Fuchun; Huang, Runqiu; Wang, Qingmin

2007-11-14

126

Ruthenium-catalyzed double-fold C-H tertiary alkoxycarbonylation of arenes using di-tert-butyl dicarbonate.  

PubMed

An efficient ruthenium-catalyzed double-fold C-H alkoxycarbonylation of arenes was developed using di-tert-butyl dicarbonate as the tertiary esterification reagent, which leads to a direct route to valuable 2,6-dicarboxylated products. PMID:25275272

Hong, Xiaohu; Wang, Hao; Liu, Bingxin; Xu, Bin

2014-10-21

127

Efficient One-Pot Synthesis of the GABAB Positive Allosteric Modulator (R,S)-5,7-Di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one  

Microsoft Academic Search

The GABAB positive allosteric modulator (R,S)-5,7-di-tert-butyl-3-hydroxy-3-trifluoromethyl-3H-benzofuran-2-one (1) was synthesized in one pot from the anhydrous lithium salt of 2,4-di-tert-butylphenol and methyl trifluoropyruvate mediated by a stoichiometric amount of anhydrous gallium(III) chloride in 64% overall yield. The enantiomers of 1 were separated by chiral-phase HPLC (Chiralpak AD®), and the absolute configuration was determined by X-ray crystallography.

Andre M. Alker; François Grillet; Pari Malherbe; Roger D. Norcross; Andrew W. Thomas; Raffaello Masciadri

2008-01-01

128

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

129

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

130

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

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

131

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

PubMed

Aerobic anoxygenic photosynthesis (AAP) is found in an increasing number of proteobacterial strains thriving in ecosystems ranging from extremely oligotrophic to eutrophic. Here, we have investigated whether the fuel oxygenate-degrading betaproteobacterium Aquincola tertiaricarbonis L108 can use AAP to compensate kinetic limitations at low heterotrophic substrate fluxes. In a fermenter experiment with complete biomass retention and also during chemostat cultivation, strain L108 was challenged with extremely low substrate feeding rates of tert-butyl alcohol (TBA), an intermediate of methyl tert-butyl ether (MTBE). Interestingly, formation of photosynthetic pigments, identified as bacteriochlorophyll a and spirilloxanthin, was only induced in growing cells at TBA feeding rates less than or equal to maintenance requirements observed under energy excess conditions. Growth continued at rates between 0.001 and 0.002 h(-1) even when the TBA feed was decreased to values close to 30?% of this maintenance rate. Partial sequencing of genomic DNA of strain L108 revealed a bacteriochlorophyll synthesis gene cluster (bchFNBHL) and photosynthesis regulator genes (ppsR and ppaA) typically found in AAP and other photosynthetic proteobacteria. The usage of light as auxiliary energy source enabling evolution of efficient degradation pathways for kinetically limited heterotrophic substrates and for lowering the threshold substrate concentration Smin at which growth becomes zero is discussed. PMID:23873782

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

2013-10-01

132

Total pressure measurements of binary mixtures containing tert-amyl methyl ether and tert-amyl alcohol  

Microsoft Academic Search

Vapor-liquid equilibrium data are needed for the reformulation of gasoline to meet Federal Clear Air Act standards. Oxygenates, such as ethers and alcohols, are known to reduce Co emissions from motor vehicles, and ethers are used as a substitute for aromatics in gasoline to improve the octane rating. The vapor pressure of pure tert-amyl methyl ether (TAME) was measured together

Stefan Semar; Stanley I. Sandler; Maria Antosik

1995-01-01

133

A physiological model for tert-amyl methyl ether and tert-amyl alcohol: hypothesis testing of model structures  

Microsoft Academic Search

The oxygenate tert-amyl methyl ether (TAME) is a gasoline fuel additive used to reduce carbon monoxide in automobile emissions. To evaluate the relative health risk of TAME as a gasoline addi- tive, information is needed on its pharmacokinetics and toxicity. The objective of this study was to use a physiologically-based pharmacokinetic (PBPK) model to describe the disposition of TAME and

Amy S. Collins; Susan C. J. Sumner; Susan J. Borghoff; Michele A. Medinsky

1999-01-01

134

Free radicals formed in the reaction of 1H-1-oxo-2,4,6,8-tetrakis-(tert-butyl)phenoxazine and 1-hydroxy-2,4,6,8-tetrakis(tert-butyl)-phenoxazinyl radical with certain organometallic compounds  

SciTech Connect

1H-1-Oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine undergoes ligand exchange reactions and behaves as a spin trap for metal-centered radicals, as a result of which stable paramagnetic complexes are formed with delocalization of the unpaired electron in the organic ligand. Paramagnetic complexes are also formed as the result of a reaction between potassium salt (IA) and triphenyl-tin and triphenyl-lead monochlorides.

Karsanov, I.V.; Ivakhnenko, E.P.; Khandkarova, V.S.; Rubezhov, A.Z.; Okhlobystin, O.Yu.; Minkin, V.I.; Prokof'ev, A.I.; Kabachnik, M.I.

1987-07-10

135

Enantioselective synthesis of (1 S,2 S)-1,2-di- tert-butyl and (1 R,2 R)-1,2-di-(1-adamantyl)ethylenediamines  

Microsoft Academic Search

An enantioselective synthesis of sterically congested 1,2-di-tert-butyl and 1,2-di-(1-adamantyl)ethylenediamines has been developed. Thus, diastereomerically pure trans-1-apocamphanecarbonyl-4,5-dimethoxy-2-imidazolidinones 6 and 7 were successfully prepared by optical resolution of (±)-trans-4,5-dimethoxy-2-imidazolidinone using apocamphanecarbonyl chloride (MAC-Cl) followed by stereospecific and stepwise substitution of the dimethoxyl groups using tert-butyl or 1-adamantyl cuprates to provide (4S,5S)-4,5-di-tert-butyl and (4R,5R)-4,5-di-(1-adamantyl)-2-imidazolidinones 12 and 15, respectively. Furthermore, N-acetyl 4,5-di-tert-butyl and 4,5-di-(1-adamantyl)-2-imidazolidinones

Alaa A.-M. Abdel-Aziz; Serry A. A. El Bialy; Fatma E. Goda; Takehisa Kunieda

2004-01-01

136

Synthesis and insecticidal activities of novel N-sulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. 3. N-(alkyldithio), n-(aminothio), and N,N-dithio derivatives.  

PubMed

A series of novel N-(alkyldithio) and N-aminothio derivatives of N'-tert-butyl-N,N'-diacylhydrazines were designed and synthesized as insect growth regulators via the key intermediates N-chlorosulfenyl-N'-tert-butyl-N,N'-diacylhydrazines. A series of novel N,N-dithio derivatives were also designed and synthesized with N'-tert-butyl-N,N'-diacylhydrazines and sulfur chloride in the presence of sodium hydride. Compared to the parent compounds, these derivatives displayed better solubility and improved hydrophobicities. The insecticidal activities of the target compounds were evaluated. The results of bioassays showed that the target compounds possessed comparable activities against oriental armyworm with the corresponding parent compounds. In particular, N-(morpholinosulfenyl)-N'-tert-butyl-N-4-ethylbenzoyl-N'-3,5-dimethylbenzoylhydrazide (IIIk) has higher toxicities against oriental armyworm and diamondback moth than the parent compound, RH-5992. PMID:18959411

Zhao, Qiqi; Ou, Xiaoming; Huang, Zhiqiang; Bi, Fuchun; Huang, Runqiu; Wang, Qingmin

2008-11-26

137

Cytotoxicity of 2- tert-butyl hydroquinone glutathione conjugates after apical and basolateral exposure of rat renal proximal tubular cell monolayers  

Microsoft Academic Search

Confluent monolayers of renal proximal tubular (RPT) cells cultured on porous supports were used to investigate the cytotoxicity induced by glutathione conjugates of 2-tert-butyl-(1,4)-hydroquinone (SG-TBHQ) after apical and basolateral exposure. As judged from lactate dehydrogenase (LDH) leakage, cytotoxicity was observed after basolateral exposure of monolayers to 250 and 500 ?m 2-tert-butyl-5-(glutathion-S-yl)hydroquinone (5SG-TBHQ). In these experiments, LDH leakage was 22.3 ±

H. E. M. G. Haenen; E. Bleijlevens; H. Elzerman; J. H. M. Temmink; J. H. Koeman; P. J. Van Bladeren

1996-01-01

138

A Convenient Synthesis of Novel N?-tert-Butyl-N?-Substituted Benzoyl-N-(Substituted Phenyl)aminocarbonylhydrazines and Their Derivatives  

Microsoft Academic Search

N-tert-butyl-N-substituted benzoylhydrazines were prepared in two convenient procedures with good yields, subsequent reaction with substituted phenylisocyanates in 1,2-dichloroethane provided a series of novel N?-tert-butyl-N?-substituted benzoyl-N-(substituted phenyl)aminocarbonylhydrazines. Further treatment with oxalyl chloride gave their derivatives in good yields. The title compounds exhibit moderate larvicidal activities and anticancer activities.

Qingmin Wang; Runqiu Huang

2004-01-01

139

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

140

Synthesis and insecticidal activity of N-tert-butyl-N,N'-diacylhydrazines containing 1,2,3-thiadiazoles.  

PubMed

N-tert-Butyl-N,N'-diacylhydrazines are nonsteroidal ecdysone agonists used as environmental benign pest regulators. In this paper, two series of new N-tert-butyl-N,N'-diacylhydrazine derivatives containing 1,2,3-thiadiazole were designed and synthesized. All structures of the synthesized compounds were confirmed by proton nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS). Bioasssay results indicated that most of the synthesized compounds possessed good insecticidal activities against Plutella xylostella L. and Culex pipiens pallens as compared with the positive control, tebufenozide. The results of this study indicated that 1,2,3-thiadiazoles, as an important active substructure, could improve or maintain the activity of the dicylhydrazines and favor novel pesticide development. PMID:21166420

Wang, Huan; Yang, Zhikun; Fan, Zhijin; Wu, Qingjun; Zhang, Youjun; Mi, Na; Wang, Shouxin; Zhang, Zhengcai; Song, Haibin; Liu, Feng

2011-01-26

141

Generation of (nonafluoro-tert-butoxy)methyl ponytails for enhanced fluorous partition of aromatics and heterocycles.  

PubMed

The reaction of sodium perfluoro-tert-butoxide with benzylic carbon-bromide bond(s) leads to the formation of (nonafluoro-tert-butoxy)methyl ponytail(s), which can enhance the fluorous solubility and partition of aromatics and heterocycles. PMID:22245936

Zhao, Xi; Ng, Wing Yan; Lau, Kai-Chung; Collis, Alana E C; Horváth, István T

2012-03-21

142

A rapid method for analysis of tert-butyl hydroquinone (TBHQ) in ethyl esters of fish oil  

Microsoft Academic Search

A rapid, quantitative gas Chromatographic method is described for quantitating the phenolic antioxidant,tert- butyl hydroquinone (TBHQ), in fish oil ethyl esters. The procedure entails silyl derivatization of TBHQ in an acetonitrile\\u000a solution of ethyl esters followed by capillary gas chromatography (GC) analysis with an internal standard method of quantitation.\\u000a Average recoveries of spiked samples were 98% at the legal limit

Teresa P. Icenhour; Frances M. Van Dolah

1991-01-01

143

Silver ion-selective electrodes employing Schiff base p- tert-butyl calix[4]arene derivatives as neutral carriers  

Microsoft Academic Search

The potentiometric response characteristics and selectivity properties of poly(vinylchloride) (PVC) matrix membrane ion-selective electrodes for silver(I) ion, based on Schiff base p-tert-butyl calix[4]arene derivatives containing N and O as binding sites, were examined. These derivatives proves to work well with silver ions and corresponding electrodes display an excellent response to this ion. These electrodes works well over wide range of

R. K. Mahajan; Inderpreet Kaur; Manoj Kumar

2003-01-01

144

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

SciTech Connect

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

Belogorokhov, I. A., E-mail: jugqwerty@mail.ru [State Research and Project Institute of Rare-Metal Industry GIREDMET (Russian Federation); Tikhonov, E. V. [Moscow State University (Russian Federation); Dronov, M. A. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Belogorokhova, L. I. [Moscow State University (Russian Federation); Ryabchikov, Yu. V. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Tomilova, L. G.; Khokhlov, D. R. [Moscow State University (Russian Federation)

2011-11-15

145

Reaction of zirconium alkoxides with tert -butyl hydroperoxide. Oxidative ability of the Zr(OBu- t ) 4 - t -BuOOH system  

Microsoft Academic Search

Oxidation of the isopropoxy group in the Zr(i-PrO)4i-PrOH complex involves both direct reaction with tert-butyl hydroperoxide and intermediate formation of zirconium peroxy compound. Zirconium tetra-tert-butoxide reacts with tert-bytyl hydroperoxide to form metal-containing peroxide and trioxide. Decomposition of the latter leads to oxygen evolution\\u000a and is accompanied by radical formation. The alkoxyl and peroxyl radicals formed were identified by ESR spectroscopy.

M. V. Gulenova; L. P. Stepovik; V. K. Cherkasov

2006-01-01

146

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

147

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

PubMed

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

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

2011-02-01

148

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

PubMed

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

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

2011-11-11

149

Microemulsion polymerization of butyl acrylate and methyl methacrylate  

Microsoft Academic Search

Microemulsions of n-butyl acrylate (BA) were prepared with the following surfactant\\/cosurfactant systems: ethoxylated nonylphenol (EONP30)\\/1-pentanol,\\u000a EONP30\\/acrylic acid, sodium dodecyl sulphate\\/ 1-pentanol and cetyltrimethylam-monium bromide (CTAB)\\/ 1-pentanol. Microemulsions\\u000a of BA and methyl methacrylate (MMA) were also prepared using CTAB without cosurfactant. Polymerizations were carried out by\\u000a both batch and semi continuous methods with the lipophilic initiators 2,2?-azobis(isobuty-ronitrile) and benzoyl peroxide\\u000a and

A. Hammond; P. Budd; C. Price

150

Di(tert-butyl) phosphate complexes of aluminum: Precursors to aluminum phosphate xerogels and thin films  

SciTech Connect

Aluminophosphates and related materials are useful in a number of applications, in particular as catalysts and catalyst supports. In addition, aluminophosphates have been shown to possess interesting ion exchange and adsorption properties. Reactions of HO(O)P(O{sup t}Bu){sub 2} with Al{sub 2}Me{sub 6} and [Al(O{sup i}Pr){sub 3}]{sub 4} gave the new molecular aluminum phosphate complexes [Me{sub 2}AlO{sub 2}P(O{sup t}Bu){sub 2}]{sub 2} (1) and [Al(O{sup i}Pr){sub 2}O{sub 2}P(O{sup t}Bu){sub 2}]{sub 4} (2), respectively. In the solid state, 1 exists as a centrosymmetric dimer consisting of two four-coordinate Al centers bridged by two phosphate groups. In the solid state 2 exists as a centrosymmetric tetramer in which the unique half of the tetramer consists of two aluminum atoms bridged by two di(tert-butyl)phosphate groups. The central part of the molecule contains a planar Al{sub 2}O{sub 2} four-membered ring containing two symmetry-related Al(1) atoms bridged by two {minus}O{sup i}Pr ligands. Solution-phase thermolyses of 1 and 2 in organic solvents led to the formation of transparent and opaque xerogels, respectively, after air-drying. The xerogel derived from 1 in 2-propanol had a surface area of 442 m{sup 2} g{sup {minus}1} after calcination to 600 C in air. Thin, transparent films of aluminum phosphate were prepared by chemical vapor deposition (CVD) using both 1 and 2 as molecular precursors.

Lugmair, C.G.; Tilley, T.D. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry] [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; [Lawrence Berkeley National Lab., CA (United States). Chemical Sciences Div.; Rheingold, A.L. [Univ. of Delaware, Newark, DE (United States). Dept. of Chemistry and Biochemistry] [Univ. of Delaware, Newark, DE (United States). Dept. of Chemistry and Biochemistry

1999-06-01

151

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

PubMed

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 and hepatotoxicity in rats to evaluate the antioxidative bioactivity of berberine. The results in rat primary hepatocytes demonstrated that berberine, at the concentrations of 0.01-1.0 mM, significantly decreased the leakage of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT), and the formation of malondialdehyde (MDA) induced by 30 min treatment of t-BHP (1.5 mM). Berberine also attenuated the t-BHP-induced depletion of glutathione (GSH) and induced a high level of DNA repair synthesis. The in vivo study showed that the intraperitoneal pretreatment with berberine (0.5 and 5 mg/kg) for 5 days before a single dose of t-BHP (0.1 mmol/kg) significantly lowered the serum levels of hepatic enzyme markers (ALT and aspartate aminotransferase) and reduced oxidative stress in the liver. The histopathological evaluation of the livers revealed that berberine reduced the incidence of liver lesions, including hepatocyte swelling, leukocyte infiltrations, and necrosis induced by t-BHP. These results lead us to speculate that berberine may play a chemopreventive role via reducing oxidative stress in living systems. PMID:12415430

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

2002-11-01

152

(4-Hydroxy-methyl-1H-imidazole-?N)bis-(tri-tert-butoxy-silanethiol-ato-?O,S)cadmium(II).  

PubMed

The Cd(II) atom in the title compound, [Cd(C(12)H(27)O(3)SSi)(2)(C(4)H(6)N(2)O)], is penta-coordinated by two O and two S atoms from the O,S-chelating silanethiol-ate residue and one N from the 4-hydroxy-methyl-imidazole ligand and shows a strongly distorted trigonal-bipyramidal geometry. The title complex is isostructural with its zinc analog. The hydroxy group of the ligand is involved in intra-molecular O-H?S hydrogen bonding and also acts as an acceptor in the formation of an inter-molecular N-H?O hydrogen bond, which links mol-ecules of the complex into zigzag chains parallel to the b axis. One of the tert-butyl groups is disordered over two orientations with occupancies of 0.557?(12):0.443?(12). PMID:21581133

Do??ga, Anna; Baranowska, Katarzyna; Jarz?bek, Zaneta

2008-01-01

153

Reactions of tert -butyl N,N -diethyl- N ?-(4-phenylthiazol-2-yl)-phosphorodiamidite with electrophilic reagents  

Microsoft Academic Search

Previously unknown amidophosphorous acid derivatives were prepared by transamidation of tert-butyl N,N-diethyl-N?-(4-phenylthiazolyl)phosphorodiamidite with 2-amino-4-phenylthiazole, and their reactions with acetyl and benzoyl chloride\\u000a were studied. These reactions are shown to proceed regioselectively according to the Arbuzov scheme to give the corresponding\\u000a ketophosphonates. The reaction of the phosphorodiamidite with acetyl chloride in a 1:2 molar ratio involves formation of acetophosphonate\\u000a that reacts

L. K. Sal’keeva; M. T. Nurmaganbetova; E. V. Minaeva; B. Z. Kokzhalova

2006-01-01

154

Total pressure measurements of binary mixtures containing tert-amyl methyl ether and tert-amyl alcohol  

SciTech Connect

Vapor-liquid equilibrium data are needed for the reformulation of gasoline to meet Federal Clear Air Act standards. Oxygenates, such as ethers and alcohols, are known to reduce Co emissions from motor vehicles, and ethers are used as a substitute for aromatics in gasoline to improve the octane rating. The vapor pressure of pure tert-amyl methyl ether (TAME) was measured together with isothermal P-x data for mixtures of pentane + TAME and pentane + tert-amyl alcohol (TAOH) at temperatures between 70 and 110 C. Also, activity coefficients at infinite dilution for the binary mixtures of TAME + TAOH were obtained in the 90--120 C temperature range. The P-T-x data were correlated using the Peng-Robinson equation of state separately with the van der Waals and Wong-Sandler mixing rules.

Semar, S.; Sandler, S.I. [Univ. of Delaware, Newark, DE (United States); Antosik, M. [Polish Academy of Sciences, Warszawa (Poland). Inst. of Physical Chemistry

1995-05-01

155

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

NASA Astrophysics Data System (ADS)

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

Gupta, Rini; Patey, G. N.

2012-07-01

156

Intra-arterial tert -Butyl-Hydroperoxide Infusion Induces an Exacerbated Sensory Response in the Rat Hind Limb and is Associated with an Impaired Tissue Oxygen Uptake  

Microsoft Academic Search

The objective of this study was to investigate oxidative stress and oxygen extraction mechanisms in an animal model of continuous\\u000a intra-arterial infusion of a free radical donor and in an in vitro model using isolated mitochondria. tert-Butyl-hydroperoxide (tert-BuOOH, 25 mM) was infused for 24 h in the left hind limb of rats to induce soft tissue damage (n?=?8). After 7 days, we assessed

Edward C. T. H. Tan; Harry van Goor; Soheyl Bahrami; Andrey V. Kozlov; Martin Leixnering; Heinz Redl; R. Jan A. Goris

2011-01-01

157

Structural effects on the C-S bond cleavage in aryl tert-butyl sulfoxide radical cations.  

PubMed

The oxidation of a series of aryl tert-butyl sulfoxides (4-X-C6H4SOC(CH3)3: 1, X = OCH3; 2, X = CH3; 3, X = H; 4, X = Br) photosensitized by 3-cyano-N-methylquinolinium perchlorate (3-CN-NMQ(+)) has been investigated by steady-state irradiation and nanosecond laser flash photolysis (LFP) under nitrogen in MeCN. Products deriving from the C-S bond cleavage in the radical cations 1(+•)-4(+•) have been observed in the steady-state photolysis experiments. By laser irradiation, the formation of 3-CN-NMQ(•) (?(max) = 390 nm) and 1(+•)-4(+•) (?(max) = 500-620 nm) was observed. A first-order decay of the sulfoxide radical cations, attributable to C-S bond cleavage, was observed with fragmentation rate constants (k(f)) that decrease by increasing the electron donating power of the arylsulfinyl substituent from 1.8 × 10(6) s(-1) (4(+•)) to 2.3 × 10(5) s(-1) (1(+•)). DFT calculations showed that a significant fraction of the charge is delocalized in the tert-butyl group of the radical cations, thus explaining the small substituent effect on the C-S bond cleavage rate constants. Via application of the Marcus equation to the kinetic data, a very large value for the reorganization energy (? = 62 kcal mol(-1)) has been calculated for the C-S bond scission reaction in 1(+•)-4(+•). PMID:23581281

Cavattoni, Tullio; Del Giacco, Tiziana; Lanzalunga, Osvaldo; Mazzonna, Marco; Mencarelli, Paolo

2013-05-17

158

Exposure to methyl tertiary-butyl ether from oxygenated gasoline in Stamford, Connecticut.  

PubMed

In 1993, state health officials in Connecticut invited the Centers for Disease Control and Prevention (CDC) to assist in an investigation of exposure to methyl tertiary-butyl ether in oxygenated gasoline in Stamford, Connecticut. Venous blood samples were collected from 14 commuters and from 30 other persons who worked in the vicinity of traffic or automobiles, and the samples were analyzed for methyl tertiary-butyl ether, tertiary-butyl alcohol, benzene, m-/p-xylene, o-xylene, and toluene. The highest levels of methyl tertiary-butyl ether in blood were measured among gasoline service station attendants (median = 15 micrograms/l, range = 7.6-28.9 micrograms/l). Blood levels of methyl tertiary-butyl ether were highly variable among persons who worked in car-repair shops (median = 1.73 micrograms/l, range = 0.17-36.7 micrograms/l) and were generally lowest among commuters (median = 0.11 micrograms/l, range = < 0.05-2.60 micrograms/l). Blood levels of methyl tertiary-butyl ether were correlated strongly with personal-breathing-zone samples of methyl tertiary-butyl ether and blood levels of other volatile organic compounds. This exposure information should prove useful to a future risk analysis of this high-volume chemical. PMID:7618951

White, M C; Johnson, C A; Ashley, D L; Buchta, T M; Pelletier, D J

1995-01-01

159

Copper redox-dependent activation of 2- tert-butyl(1,4)hydroquinone: formation of reactive oxygen species and induction of oxidative DNA damage in isolated DNA and cultured rat hepatocytes  

Microsoft Academic Search

The biotransformation of butylated hydroxyanisole (BHA), a possible carcinogenic food antioxidant, includes o-demethylation to 2-tert-butyl(1,4)hydroquinone (TBHQ) which can subsequently be oxidized to 2-tert-butyl(1,4)paraquinone (TBQ). In this study, we have examined the capacity of Cu, a nuclei- and DNA-associated transition metal, to mediate the oxidation of TBHQ. In phosphate buffered saline (PBS), autooxidation of TBHQ to TBQ was not detectable, while

Yunbo Li; Andrew Seacat; Periannan Kuppusamy; Jay L Zweier; James D Yager; Michael A Trush

2002-01-01

160

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

161

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

PubMed

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

You, Xun; Wang, Guan-Wu

2014-01-01

162

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

163

Synthesis, Characterization, and In Vitro Cytotoxicity of Triorganotin 3,5-Di-tert-butyl-4-hydroxybenzoates  

Microsoft Academic Search

The triorganotin 3,5-di-tert-butyl-4-hydroxybenzoates, 3,5-(t-Bu)2-4-HO-C6H2COOSnR3 (R = c-C6H11, 1; C6H5, 2; C6H5CH2, 3; C6H5C(CH3)2CH2, 4), have been synthesized and characterized by elemental analysis, IR, and H and C NMR spectra. The crystal structures of 1 and 4 have been determined by X-ray single crystal diffraction and show that the tin atom possesses a distorted tetrahedral geometry. Intermolecular O?H···O hydrogen bond in

Wenchao Ding; Zhi Liu; Laijin Tian; Xiangao Quan

2012-01-01

164

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

PubMed

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

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

2007-01-15

165

Vibrational spectroscopic investigations and computational study of 5-tert-butyl-N-(4-trifluoromethylphenyl)pyrazine-2-carboxamide.  

PubMed

Pyrazine and its derivatives form an important class of compounds present in several natural flavors and complex organic molecules. Quantum chemical calculations of the equilibrium geometry, harmonic vibrational frequencies, infrared intensities and Raman activities of 5-tert-Butyl-N-(4-trifluoromethylphenyl)pyrazine-2-carboxamide in the ground state were carried out by using density functional methods. Potential energy distribution of normal modes of vibrations was done using GAR2PED program. Nonlinear optical behavior of the examined molecule was investigated by the determination of first hyperpolarizability. The calculated HOMO and LUMO energies show the chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated geometrical parameters are in agreement with that of similar derivatives. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. PMID:23727674

Joseph, Tomy; Varghese, Hema Tresa; Yohannan Panicker, C; Viswanathan, K; Dolezal, Martin; Manojkumar, T K; Van Alsenoy, Christian

2013-09-01

166

Strong carbon-surface dative bond formation by tert-butyl isocyanide on the Ge(100)-2 × 1 surface.  

PubMed

Carbon dative bond formation between an organic molecule and a semiconductor surface is reported here for the first time. Our studies show that the adsorption of tert-butyl isocyanide on the (100) surface of germanium, measured using Fourier transform infrared spectroscopy, temperature-programmed desorption, and density functional theory calculations, occurs via formation of a dative bond to the surface through the isocyanide carbon. The experimentally observed adsorption energy of 26.8 kcal/mol is the largest among any organic molecule dative bonded on the Ge(100)-2 × 1 surface studied to date. The dative-bonded adsorbate is characterized by a N?C stretching frequency significantly blue-shifted from that of the free molecule. Moreover, the adsorbate N?C vibrational frequency red-shifts back toward that of the free molecule upon increasing coverage. These spectroscopic effects are attributed to ?-donation of the isocyanide lone pair electrons to the surface. PMID:24725248

Shong, Bonggeun; Wong, Keith T; Bent, Stacey F

2014-04-23

167

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

168

Oxidative DNA Damage and Apoptosis Induced by Metabolites of Butylated Hydroxytoluene  

Microsoft Academic Search

DNA damage by metabolites of a food additive, butylated hydroxytoluene (BHT), was investigated as a potential mechanism of carcinogenicity. The mechanism of DNA damage by 2,6-di-tert-butyl-p-benzoquinone (BHT-quinone), 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHT-OOH), and 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) in the presence of metal ions was investigated by using 32P-labeled DNA fragments obtained from the c-Ha-ras-1 proto-oncogene and the p53 tumor suppressor gene. BHT-OOH caused DNA damage

Saeko Oikawa; Kohsuke Nishino; Shinji Oikawa; Sumiko Inoue; Tamio Mizutani; Shosuke Kawanishi

1998-01-01

169

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

170

Percutaneous absorption of 2,6-di-tert-butyl-4-nitrophenol (DBNP) in isolated perfused porcine skin.  

PubMed

DBNP (2,6-di-tert-butyl-4-nitrophenol) has been reported as a potential contaminant in submarines. This yellow substance forms when lubrication oil mist containing the antioxidant additive 2,6-di-tert-butylphenol passes through an electrostatic precipitator and is nitrated. Percutaneous absorption of 14C-DBNP was assessed in the isolated perfused porcine skin flap (IPPSF). Four treatments were studied (n=4 flaps/treatment): 40.0 microgram/cm(2) in 100% ethanol; 40.0 microgram/cm(2) in 85% ethanol/15% H(2)O; 4.0 microgram/cm(2) in 100% ethanol; and 4.0 microgram/cm(2) in 85% ethanol/15% water. DBNP absorption was minimal across all treatment groups, with the highest absorption detected being only 1.08% applied dose in an aqueous ethanol group. The highest mass of 14C-DBNP absorbed was only 0.5 microgram. The majority of the applied dose remained on the surface of the skin. This suggests that there is minimal dermal exposure of DBNP when exposed topically to skin. PMID:12781207

Inman, Alfred O; Still, Kenneth R; Jederberg, Warren W; Carpenter, Robert L; Riviere, Jim E; Brooks, James D; Monteiro-Riviere, Nancy A

2003-06-01

171

Ferrocenylnaphthalene diimide-based electrochemical detection of aberrant methylation in hTERT gene.  

PubMed

Since aberrant methylation at CpG sites is linked to the silencing of tumor suppressor genes, DNA methylation analysis is important for cancer diagnosis. We developed ferrocenylnaphthalene diimide (FND), which has two ferrocenyl moieties at the substituent termini, as an electrochemical indicator for hybridized DNA duplexes. In this study, we attempted to detect aberrant methylation of human telomerase reverse transcriptase gene (hTERT), an efficient cancer marker, using FND-based hybridization coupled with electrochemical detection via a multi-electrode chip. PMID:24993489

Sato, Shinobu; Saeki, Toshiro; Tanaka, Tomoki; Kanezaki, Yusuke; Hayakawa, Mana; Haraguchi, Kazuya; Kodama, Masaaki; Nishihara, Tatsuji; Tominaga, Kazuhiro; Takenaka, Shigeori

2014-10-01

172

Kinetic study of gas-phase reactions of OH and NO3 radicals and O3 with iso-butyl and tert-butyl vinyl ethers.  

PubMed

Using a relative rate technique, kinetic studies on the gas-phase reactions of OH radicals, ozone, and NO(3) radicals with iso-butyl vinyl ether (iBVE) and tert-butyl vinyl ether (tBVE) have been performed in a 405 L Duran glass chamber at (298 ± 3) K and atmospheric pressure (750 ± 10 Torr) in synthetic air using in situ FTIR spectroscopy to monitor the reactants. The following rate coefficients (in units of cm(3) molecule(-1) s(-1)) have been obtained: (1.08 ± 0.23) × 10(-10) and (1.25 ± 0.32) × 10(-10) for the reactions of OH with iBVE and tBVE, respectively; (2.85 ± 0.62) × 10(-16) and (5.30 ± 1.07) × 10(-16) for the ozonolysis of iBVE and tBVE, respectively; and (1.99 ± 0.56) × 10(-12) and (4.81 ± 1.01) × 10(-12) for the reactions of NO(3) with iBVE and tBVE, respectively. The rate coefficients for the NO(3) reactions are first-time determinations. The measured rate coefficients are compared with estimates using current structure activity relationship (SAR) methods and the effects of the alkoxy group on the gas-phase reactivity of the alkyl vinyl ethers toward the oxidants are compared and discussed. In addition, estimates of the tropospheric lifetimes of iBVE and tBVE with respect to their reactions with OH, ozone, and NO(3) for typical OH radical, ozone, and NO(3) radical concentrations are made, and their relevance for the environmental fate of compounds is considered. PMID:22897604

Zhou, Shouming; Barnes, Ian; Zhu, Tong; Benter, Thorsten

2012-09-01

173

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

SciTech Connect

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

Berg, L.

1993-07-20

174

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...

175

Adiabatic compressibility of pseudo-binary aqueous solutions of tert-butyl alcohol and dimethylsulfoxide as a result of ultrasonic investigations  

Microsoft Academic Search

The tert-butyl alcohol (TBA) and dimethyl sulfoxide (DMSO) are two small molecules geometrically very similar, but having different polar groups. Taking into account the intermolecular interactions in the TBA\\/H2O and DMSO\\/H2O systems, especially in the water-rich region of concentration, the ultrasonic speeds (high accuracy resonance method at the frequency 7.5MHz) and densities in pseudo-binary mixtures of the system: (TBA+H2O+DMSO) with

Piotr Miecznik; Milena Kaczmarek

2006-01-01

176

Study on the chromatographic behavior of water-soluble vitamins on p- tert-butyl-calix[8]arene-bonded silica gel stationary phase by HPLC  

Microsoft Academic Search

In this paper, the chromatographic behavior of some water-soluble vitamins was studied on a new p-tert-butyl-calix[8]arene-bonded silica gel stationary phase (CABS, 5?m particle size, the bonded amount 0.071mmolg?1) by using vitamin standards as probes for HPLC. The comparative study of the separation of these compounds was done by using CABS and ODS as stationary phases under the same chromatographic conditions.

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

2004-01-01

177

Catalytic epoxidation of propylene with tert. -butyl hydroperoxide in the presence of modified carboxy cation-exchange resin 'Amberlite' IRC50  

Microsoft Academic Search

The heterogeneous expoxidation catalyst was prepared by treating Amberlite IRC-50, a styrene\\/acrylic acid copolymer, with an alcohol solution of molybdenyl chloride. The kinetics of the reaction of propylene in benzene or tetrachloromethane with tert.-butyl hydroperoxide at approx. 35 atm and 60°⁻⁹°sup 0\\/C in the presence of the modified Amberlite resembled the Michaelis-Menten kinetics of enzyme catalysis, i.e., the initial reaction

S. Tanielyan; S. Boeva; R. Ivanov

1979-01-01

178

SYNTHESIS AND MULTINUCLEAR MAGNETIC RESONANCE STUDY (H, C, N, Si, P NMR) OF BIS(AMINO)PHOSPHINYL- AND AMINO(tertBUTYL)PHOSPHINYL SULFUR DIIMIDES  

Microsoft Academic Search

Sulfur diimides bearing either bis(amino)phosphinyl (1,4,5) or amino(tert-butyl)phosphinyl substituents (2, 3) were prepared by salt elimination reactions from the potassium sulfur diimides K2SN2, KNSNtBu and KNSNSiMe3 and aminophosphinyl chlorides. Bulky amino groups are essential to prevent self-degradation of the sulfur diimides via sulfur abstraction. The compounds were characterized by multinuclear magnetic resonance (H, C, N, Si and P NMR). The

Max Herberhold; Christian Köhler; Bernd Wrackmeyer

1992-01-01

179

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

180

Reaction of 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine with certain group II-IV metals  

SciTech Connect

It has already been shown that 2-amino-4,6-di(tert-butyl)phenol reacts with 3,5-di(tert-butyl)-o-benzoquinone to form 1H-1-oxo-2,4,6,8-tetrakis(tert-butyl)phenoxazine (I), which is readily reduced by alkali metals to the corresponding semiquinone anion-radical (II), and further to the diamagnetic dianion (IIA). They made use of this ability of (I) to undergo reduction to prepare anion-radical salts with different group II-IV metals in the form of their amalgams. In the EPR spectrum of the anion-radical complex (III) formed in the reduction of (I) by a thallium amalgam, the HFI constants of the unpaired electron with magnetic nuclei of the organic ligand are close to those of the K-salt (II), and a substantial HFI is observed with the /sup 203,205/Tl nuclei. This unequivocally proves that the complex has a semiquinone structure, since an HFI on the /sup 203,205/Tl nuclei of such an order of magnitude is characteristic of o-benzoquinone salts with a thallium cation.

Karsanov, I.V.; Ivakhnenko, E.P.; Khandkarova, V.S.; Rubezhov, A.Z.; Okhlobystin, O.Yu.; Minkin, V.I.; Prokof'ev, A.I.; Kabachnik, M.I.

1987-07-10

181

Enantiomeric separation of N-protected amino acids by non-aqueous capillary electrophoresis using quinine or tert-butyl carbamoylated quinine as chiral additive.  

PubMed

A capillary electrophoretic (CE) method for the enantioseparation of N-protected chiral amino acids was developed using quinine and tert-butyl carbamoylated quinine as chiral selectors added to nonaqueous electrolyte solutions (NACE). A series of various N-derivatized amino acids were tested as chiral selectands, and in order to optimize the CE enantioseparation of these compounds, different parameters were investigated: the nature of the organic solvent, the combination of different solvents, the nature and the concentration of the background electrolyte, the selector concentration, the capillary temperature, and the applied voltage. The influence of these factors on the separation of the analyte enantiomers and the electroosmotic flow was studied. Generally, with tert-butyl carbamoylated quinine as chiral selector, better enantioseparations were achieved than with unmodified quinine. Optimum experimental conditions were found with a buffer made of 12. 5 mM ammonia, 100 mM octanoic acid, and 10 mM tert-butyl carbamoylated quinine in an ethanol-methanol mixture (60:40 v/v). Under these conditions, DNB-Leu enantiomers could be separated with a selectivity factor (alpha) of 1.572 and a resolution (Rs) of 64.3; a plate number (N) of 127,000 and an asymmetry factor (As) of 0.93 were obtained for the first migrating enantiomer. PMID:10467313

Piette, V; Lammerhofer, M; Lindner, W; Crommen, J

1999-01-01

182

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

183

Corilagin prevents tert-butyl hydroperoxide-induced oxidative stress injury in cultured N9 murine microglia cells.  

PubMed

Oxidative stress plays an important role in neurodegenerative diseases. Reactive oxygen species (ROS)-mediated stress in microglia in vivo could result in cellular injuries and preferentially induces neuronal injury. Corilagin, a novel member of the phenolic tannin family, has been shown to possess antioxidant properties. In this study, we investigated the effects of corilagin on tert-butyl hydroperoxide (TBHP)-induced injury in cultured N9 murine microglial cells and the underlying mechanisms by a methyltetrazolium assay and oxidative damage assay. We found that exposure of N9 cells to TBHP induced cytotoxicity as demonstrated by cell shrinkage, loss of cell viability, increased lactate dehydrogenase (LDH) leakage, and increased intracellular levels of ROS. By contrast, TBHP reduced both superoxide dismutase activity and total cell anti-oxidation capacity, but glutathione was not reduced. Moreover, TBHP treatment was associated with the loss of mitochondrial membrane potential, and it induced cell apoptosis through the mitochondrial-mediated pathway involving the down-regulation of Bcl-2 expression and up-regulation of the Bax/Bcl-2 ratio. Interestingly, pre-treatment with corilagin reversed these reactions. These data collectively indicated that corilagin could attenuate TBHP-induced oxidative stress injury in microglial cells, and its protective effects may be ascribed to its antioxidant and antiapoptotic properties. Our findings suggest that corilagin should be a potential candidate for the treatment of oxidative stress-induced neurodegenerative diseases. PMID:21683104

Chen, Yiyan; Chen, Chonghong

2011-08-01

184

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

PubMed Central

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

Kucera, Otto; Endlicher, Rene; Rousar, Tomas; Lotkova, Halka; Garnol, Tomas; Drahota, Zdenek

2014-01-01

185

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

186

Thermodynamic and kinetic studies of the liquid phase synthesis of tert-butyl ethyl ether using a reaction calorimeter  

SciTech Connect

The liquid-phase addition of ethanol to isobutene to give tert-butyl ethyl ether (ETBE) on the ion-exchange resin Lewatit K2631 has been studied in a calorimetric reactor. The heat capacity of ETBE and the enthalpy change of the ETBE synthesis reaction in the temperature range 312--333 K have been determined. ETBE heat capacity in the liquid phase has been found to follow the equation C{sub p} = 486.73 {minus} 2.253 (T/K) + 0.00479 (T/K){sup 2}. At 298 K the standard molar reaction enthalpy is {Delta}H{degree} = {minus}32.0 kJ/mol. A determination of the apparent activation energy of 86.5--89.2 kJ/mol has been performed graphically from the plots of heat flow rate versus time. An Eley-Rideal mechanism, with two active sites involved in the rate determining step, has been proved to be correct. From this model an apparent activation energy of 80.6 kJ/mol is deduced. A {minus}3.0 kJ/mol value has been found for the adsorption enthalpy of ethanol. This allows the estimation of the actual gel-phase activation energy of 77.6 kJ/mol.

Sola, L.; Pericas, M.A.; Cunill, F.; Tejero, J. [Univ. de Barcelona (Spain)

1995-11-01

187

[Protective and antioxidative effect of 2(3)tert-butyl-4-hydroxyanisole against cytotoxicity induced by doxorubicin in mice].  

PubMed

The protective and antioxidative effects of 2(3)tert-butyl-4-hydroxyanisole (BHA) against cardiotoxicity and hepatotoxicity induced by doxorubicin in mice were investigated. After pretreatment with different oral doses of BHA, doxorubicin 30 mg.kg-1 was given i.p. Serum GPT, GOT, LDH and CK were determined, and the mortality rate of animals was observed. Quinone reductase (QR), glutathione-S-transferases (GSTs) and glutathione reductase (GR) were determined on tissue cytosols with enzyme dynamic methods. Malondialdehyde (MDA) was measured by the method of thiobarbituric acid. Compared with the doxorubicin group, the serum GPT, GOT, LDH, CK and the mortality rate of mice were significantly decreased by BHA pretreatment, and BHA was shown to inhibit the increase of MDA induced by doxorubicin (P < 0.01 and P < 0.0001). Administration of BHA resulted in increased activities of QR, GSTs and GR in the myocardium and liver (P < 0.05 or P < 0.0001). These results suggest that BHA has protective effect against the toxicity induced by doxorubicin via the induction of QR, GSTs and GR activities and anti-lipid peroxidation. PMID:12016938

Wang, L; Lin, S

1998-11-01

188

The intricate paramagnetic state of [Os(Q)2(bpy)]+, Q = 4,6-di-tert-butyl-o-iminobenzoquinone.  

PubMed

The combination of two highly non-innocent ligands with a third-row transition metal produces the title complex ion which was crystallised as [Os(Q)(2)(bpy)](ClO(4))·C(6)H(6) (Q = 4,6-di-tert-butyl-o-iminobenzoquinones, bpy = 2,2'-bipyridine) and could be structurally characterised to exhibit a tris-chelate situation at the metal with trans-positioned N and cis-positioned O donor atoms. The metrical ligand parameters are in agreement with two partially reduced ligands. A 3-spin interaction (Q?(-))Os(III)(Q?(-)) can rationalise the observed S = 1/2 situation with ligand-centred resulting spin. Ligand-based spin is confirmed by DFT (calculated spin populations Q: 1.113; Os: -0.113; bpy: 0.001) and is also apparent from the EPR signal (g(1) 1.981, g(2) 1.955, g(3) 1.803, ?g 0.178, 1.915) which is influenced by the high spin-orbit coupling constant of the osmium centre. The susceptibility measurements reveal antiferromagnetic behaviour. A one-electron oxidation and two one-electron reductions could be monitored spectroelectrochemically (UV-VIS-NIR) and analysed by TD-DFT, in comparison with the results from the ruthenium analogue. The analysis reflects the strong orbital mixing between the metal and the two Q-ligand MOs. PMID:22874881

Das, Dipanwita; Scherer, Thomas Michael; Das, Amit; Mondal, Tapan Kumar; Mobin, Shaikh M; Fiedler, Jan; Priego, José Luis; Jiménez-Aparicio, Reyes; Kaim, Wolfgang; Lahiri, Goutam Kumar

2012-10-14

189

(4-Hydroxy­methyl-1H-imidazole-?N 3)bis­(tri-tert-butoxy­silanethiol­ato-?2 O,S)cadmium(II)  

PubMed Central

The CdII atom in the title compound, [Cd(C12H27O3SSi)2(C4H6N2O)], is penta­coordinated by two O and two S atoms from the O,S-chelating silanethiol­ate residue and one N from the 4-hydroxy­methyl­imidazole ligand and shows a strongly distorted trigonal-bipyramidal geometry. The title complex is isostructural with its zinc analog. The hydroxy group of the ligand is involved in intra­molecular O—H?S hydrogen bonding and also acts as an acceptor in the formation of an inter­molecular N—H?O hydrogen bond, which links mol­ecules of the complex into zigzag chains parallel to the b axis. One of the tert-butyl groups is disordered over two orientations with occupancies of 0.557?(12):0.443?(12). PMID:21581133

Do??ga, Anna; Baranowska, Katarzyna; Jarz?bek, ?aneta

2008-01-01

190

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

191

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

EPA Science Inventory

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

192

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

EPA Science Inventory

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

193

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

EPA Science Inventory

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

194

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

EPA Science Inventory

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

195

Kinetics of heterogeneously catalyzed tert-amyl methyl ether reactions in the liquid phase  

SciTech Connect

The kinetics of tert-amyl methyl ether (TAME, 2-methoxy-2-methylbutane) reactions was investigated using a commercial ion exchange resin (Amberlyst 16) as catalyst at temperatures between 324 and 354 K. The rates of reaction were determined experimentally in the liquid phase in a continuous stirred tank reactor at a pressure of 0.8 MPa. Kinetic equations derived for three different mechanisms were compared. In the forward reaction the adsorbed methanol reacted with isoamylene (2-methyl-l-butene or 2-methyl-2-butene) striking from the bulk liquid phase, and in the splitting reaction the adsorbed ether split to alcohol and isoamylene. The kinetic equations were written in terms of activities, and the activity coefficients were calculated by the UNIQUAC method. The activation energy was determined to be 95 kJ/mol for the splitting reaction of TAME to 2-methyl-l-butene and methanol and 100 kJ/mol for the splitting reaction of TAME to 2-methyl-2-butene and methanol.

Rihko, L.K.; Krause, A.O.I. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Industrial Chemistry

1995-04-01

196

Synergic effect of acetal-based resin by blending with poly[4-hydroxy styrene-co-tert-butyl acrylate-co-4-(3-cyano-1,5-di-tert-butyl carbonyl pentyl styrene)] (P(HS-TBA-CBPS)) on the profiles of 248 nm chemically amplified resist  

NASA Astrophysics Data System (ADS)

We prepared ter-polymer of hydroxystyrene, tert-butyl acrylate and 4-(3-cyano-1,5-di-tert-butyl carbonyl pentyl styrene) (P(HS-TBA-CBPS)) and discussed a characteristic of prepared polymer. As TBA, newly introduced monomer increases, contrast of resist is improved. And the prepared polymer was blended with poly(4-hydroxystyrene-co-4-(1-ethylethoxystyrene)) (EE-PHS). The synergic effect on a resist performance in KrF lithography by the combination of high and low activation energy system was shown. A resist using blending polymer was shown a good performance on resolution and LER(Line Edge Roughness) than resist using polymer separately. Based on the results, it was found that high performance KrF resist could be obtained by optimization of polymer blending.

Kim, Hyun-Jin; Chung, Yoon-Sik; Lee, Dong H.; Cho, Sook H.; Im, Kwang H.; Yim, Yun-Gill; Kim, Deog-Bae; Kim, Jae-Hyun

2002-07-01

197

Intramolecular interactions between chalcogen atoms: organoseleniums derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene.  

PubMed

[structure: see text] The synthesis and characterization of a series of low-valent organoselenium compounds derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene (22) is described. The synthesis of diselenide 25 was achieved by the lithiation route whereas bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) was synthesized by treating 22 with disodium diselenide. A series of monoselenides (27, 28, and 29) was obtained by facile nucleophilic substitution of bromine in 22, using the corresponding selenolates as nucleophiles. The halogenation reactions of bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) did not afford the corresponding selenenyl halides but resulted in the isolation of an unexpected cyclic selenenate ester 34 as a product. The selenide 32 was synthesized by the treatment of dimethoxymethyl diselenide with trilithiated 2-bromo-5-tert-butyl-N,N'-di(phenyl)isophthalamide. The existence of potential Se...O intramolecular nonbonding interactions was examined by IR, (1)H, and (77)Se NMR spectroscopy, X-ray crystallography, and computational studies. The X-ray crystal structures of 26 and 27, having two ortho formyl groups, reveal the absence of any Se...O interactions. However, the Se...O interactions were observed in the selenenate ester 34 where one of the formyl groups has been utilized for the selenenate ring formation. The crystal structures of 26 and 27 exhibited intermolecular short-range C-H...Se interactions (hydrogen bonding). Although there are four heteroatoms in carbamoyl moieties ortho to selenium capable of forming a five-membered ring on intramolecular coordination, no such intramolecular Se...X (X = N, O) interaction was observed in the crystal structure of 32. The density functional theory calculations at the B3LYP/6-31G* level predicted that for all the diformyl systems (47a-c, 48a-c), the anti,anti conformer (when both formyl oxygen atoms point away from the selenium) is more stable. This preference was found to be reversed in the monoformyl-substituted systems (50a,b, 51a,b), where the syn conformer (when formyl oxygen is near the selenium) is energetically more favorable than the anti conformer. PMID:15845009

Zade, Sanjio S; Panda, Snigdha; Singh, Harkesh B; Sunoj, Raghavan B; Butcher, Ray J

2005-04-29

198

N?-tert-Butyl-N?-(3,5-dimethyl­benzo­yl)-2,2-dimethyl-4-oxochroman-6-carbo­hydrazide  

PubMed Central

In the crystal structure of the title compound, C25H30N2O4, the steric size of the tert-butyl group causes the 3,5-dimethyl­phenyl ring to adopt a transoid geometry with respect to the N—C(O) bond. The six-membered heterocyclic ring is disordered over two sites, with occupancies of 0.553?(4) and 0.447?(4). Intra­molecular C—H?O inter­actions are present. In the crystal, mol­ecules are linked by inter­molecular N—H?O and C—H?O hydrogen bonds. PMID:21583686

Zhou, Zhongzhen; You, Wenwei; Tang, Zhongkun; Zhao, Peiliang

2009-01-01

199

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

200

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

Microsoft Academic Search

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

Shadpour Mallakpour; Samaneh Soltanian; Mohammad Reza Sabzalian

201

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

Microsoft Academic Search

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

Shadpour Mallakpour; Samaneh Soltanian

202

A New Way to tertButyl [(4R,6R)-6Aminoethyl2,2-dimethyl-1,3-dioxan-4-yl]acetate, a Key Intermediate of Atorvastatin Synthesis  

Microsoft Academic Search

A new synthesis of tert-butyl [(4R,6R)-6-aminoethyl-2,2-dimethyl-1,3-dioxan-4-yl]acetate, a key intermediate of the synthesis of an effective HMG-CoA reductase inhibitor atorvastatin, is described. The synthesis is based on the Henry reaction of nitromethane and tert-butyl [(4R,6S)-6-formyl-2,2-dimethyl-1,3-dioxan-4-yl] acetate. The formed nitroaldol was then O-acetylated and the sodium borohydride reduction of the intermediate provided tert-butyl [(4R,6R)-2,2-dimethyl-6-nitroethyl-1,3-dioxan-4-yl] acetate. Catalytic hydrogenation of the nitro group led

Stanislav Rádl

2003-01-01

203

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

Microsoft Academic Search

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

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

2004-01-01

204

Biotransformation and Kinetics of Excretion of tert-Amyl-methyl Ether in Humans and Rats after Inhalation Exposure  

Microsoft Academic Search

tert-Amyl methyl ether (TAME) may be widely used as an additive to gasoline in the future. The presence of this ether in gasoline reduces the tail pipe emission of pollutants. Therefore, widespread human exposure to TAME may occur. To contribute to the characterization of potential adverse effects of TAME, its biotransformation was compared in humans and rats after inhalation exposure.

Alexander Amberg; Elisabeth Rosner; Wolfgang Dekant

2000-01-01

205

Uterotrophic assay, Hershberger assay, and subacute oral toxicity study of 4,4?-butylidenebis(2- tert -butyl-5-methylphenol) and 3-(dibutylamino)phenol, based on the OECD draft protocols  

Microsoft Academic Search

We performed a uterotrophic assay, the Hershberger assay, and a 28-day repeated-dose toxicity study [enhanced Organization\\u000a for Economic Co-operation and Development (OECD) test guideline No. 407] of 4,4?-butylidenebis(2-tert-butyl-5-methylphenol)\\u000a and 3-(dibutylamino)phenol, based on the OECD draft protocols. In the uterotrophic assay of 4,4?-butylidenebis(2-tert-butyl-5-methylphenol),\\u000a female SD rats were subcutaneously injected with the chemical at doses of 0, 100, 300, and 1,000 mg\\/kg on

Kanji Yamasaki; Katusi Miyata; Keiji Shiraishi; Takako Muroi; Nobuhiko Higashihara; Hiroshi Oshima; Yasushi Minobe

2008-01-01

206

N?-Benzoyl-N-tert-butyl-2-chloro-N?-{[3-(6-chloro-3-pyrid-ylmethyl)-2-nitrimino-imidazolidin-1-yl]sulfan-yl}benzo-hydrazide  

PubMed Central

In the title compound, C27H27Cl2N7O4S, the amide groups bearing the N—S group and the tert-butyl group have s–trans conformations. The steric size of the tert-butyl and [(6-chloro-3-pyrid­yl)meth­yl]imidazolidin-2-yl­idene groups cause the 2-chloro­benzoyl group and the benzyol group to be directed away from one another, forming a dihedral angle of 60.62?(17)°. The central N—N bond adopts a gauche conformation with a C—N—N—C torsion angle of ?79.1?(2)°. PMID:21577543

Shang, Jian; Wang, Qing-min; Huang, Run-qiu; Chen, Li; Gao, Jianhua

2009-01-01

207

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

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

208

Synthesis and ESR studies of redox reactivity of bis (3,5-di-tert-butyl-1,2-benzoquinone-2-monooximato)Cu(II).  

PubMed

Complexing of 3,5-di-tert-butyl-1,2-benzoquinone-2-monooxime with Cu(II) in air and under N2 gave Cu(qo)2 and Cu(qo)2 x H2O (where qo is 3,5-di-tert-butyl-1,2-benzoquinone-2-monooximato-anion) complexes, respectively. The ESR spectroscopy showed that the reduction of these complexes with P(PhX)3 (X = H, m-Cl, m-CH3, p-Et2N-) and 1,4-bis(diphenyldiphosphino) butane (dppb) proceeds via the radical formation (phenoxazine, amino phenoxy and nitrene type radical intermediates) and pathways of reduction depend on the structure of these complexes. The reaction of Cu(qo), with dppb and P(PhX)3 phosphines gave essentially identical ESR spectra. At the same time, reduction of Cu(qo)2 x H2O with PPh3 result in entirely different unstable radical spectrum (g = 2.0046) which is further converted to another relatively stable Cu-containing radical signal (g = 2.0052). The unstable radical species attributed to nitrene type radicals. The initial complexes and all radical products were characterized by their ESR and optical spectra. PMID:10809059

Kasumov, V T; Kartal, I; Koksal, F

2000-04-01

209

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

210

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

PubMed

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

Pan, Yi-Ping; Tsai, Shih-Wei

2008-08-29

211

Cyclopalladation of the prochiral (di-tert-butyl)(diphenylmethyl)phosphine: kinetic lability of the corresponding (+)-phosphapalladacyclic Pd-C bond and the reluctance of the phosphine to bind in a monodentate fashion.  

PubMed

The ortho palladation of prochiral (di-tert-butyl)(diphenylmethyl)phosphine proceeded readily to give rise to the dimeric complex, di-mu-chlorobis{[(phenyl)(di-tert-butylphosphino)methyl]phenyl-C2, P}dipalladium(II). The (S,S)-(+)-dimer was subsequently obtained by optical resolution with sodium (S)-prolinate. The absolute configuration of the optically resolved (+)-dimer was concluded from the X-ray diffraction studies of the derivatized O,O-acetylacetonate complex. The availability of the (+)-dimer is crucial to the study of the properties of the Pd-C bond. The phosphapalladacycle Pd-C bond exhibited a remarkable thermodynamic stability. It could not be permanently ruptured to give rise to the eta1-P monodentate even in a refluxing acetone solution containing concentrated hydrochloric acid. Instead, the phosphine was noted to fluctuate between the ring closed and opened states via the reversible Pd-C bond cleavage/formation under this condition. Inevitably, this resulted in the racemization of the five-membered organopalladium ring structure. In contrast, such bond cleavage was not observed at room temperature in the absence of HCl. In fact, the phosphine was observed to readily ortho palladate even under conditions not favorable to cyclopalladation. Indeed, the difficulty of isolating the phosphine as a simple eta1-P monodentate coordination complex was further noted by its lack of reactivity toward the N,N-dimethyl-1-(1'naphthyl)ethylaminate palladacycle mu-chloro dimer. Only by enhancing the Lewis acidity of the palladacycle in the form of the positively charged bis(acetonitrile) complex could the phosphine be encouraged to participate in monodentate eta1-P bonding. Even then, this form of coordination was weak and was only observed by NMR spectroscopy. PMID:17489588

Ng, Joseph Kok-Peng; Chen, Shuli; Li, Yongxin; Tan, Geok-Kheng; Koh, Lip-Lin; Leung, Pak-Hing

2007-06-11

212

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

SciTech Connect

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

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

1993-10-01

213

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

E-print Network

beds was 0.5 m, and the bed volume was 9 L. Reactor 1 was filled with 8.81 kg of wet lava rock (1-3 cm of the rate-limiting step(s) is a necessity for accurate reactor control and for process optimization. Another). In summary, the biotricklingfilterswere1.5minheightand0.153mininternal diameter. The height of the packed

214

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

E-print Network

urban areas in nonattainment zones to oxygenate their gasoline in order to reduce tailpipe carbon among all chemicals in 1993. At the same time, an increasing number of groundwater contaminations was noticed over time, but it could not be firmly demonstrated that in situ biodegradation of MTBE occurred (5

215

Frontside versus backside reactivity in electron transfer to oriented tert butyl bromide and methyl bromide  

E-print Network

by bimolecular nucleophilic substitution (SN2) reactions, such as Cl CH3BrClCH3 Br . 1 These reactions proceedH9Br. © 2002 American Institute of Physics. DOI: 10.1063/1.1496477 I. INTRODUCTION Chemical reaction decreases the reaction rate by orders of magnitude because the larger CH3 groups impede the inversion

Brooks, Philip R.

216

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

217

Direct observation of the intermolecular triplet-triplet energy transfer from UV-A absorber 4- tert -butyl-4?-methoxydibenzoylmethane to UV-B absorber octyl methoxycinnamate  

NASA Astrophysics Data System (ADS)

Triplet energy transfer (TET) is an important photostabilization process for organic UV absorbers, such as 4- tert-butyl-4'-methoxydibenzoylmethane (BM-DBM) and octyl methoxycinnamate (OMC). To characterize interactions between UV absorbers as TET the interactions between BM-DBM and OMC have been studied through measurements of EPR and time-resolved phosphorescence spectra. The EPR Bmin signals and the phosphorescence of OMC were observed through the selective excitation of BM-DBM at 365 nm in EtOH at 77 K. These results indicate that the intermolecular TET occurs from BM-DBM to OMC. This is the first report of the experimental evidence of the TET between the organic UV absorbers.

Kikuchi, Azusa; Yagi, Mikio

2011-09-01

218

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

219

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

PubMed

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

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

2013-12-01

220

Determination of optical conductivity and different optical energy losses for non-crystalline Vanadyl tetra tert-butyl 2,3 Naphthalocyanine thinfilms  

SciTech Connect

Amorphous Vanadyl Tetra Tert Butyl 2, 3 naphthalocyanine thin films (VTTBNc) have been deposited using Physical Vapor Deposition technique. By analyzing the X-ray diffraction, the structure of as deposited films is found to be non-crystalline. Different optical properties of these thin films have been investigated by means of optical absorption and reflection spectra. Various optical constants like band gap energy, E{sub g} the width of band tails of localized states into the gap, E{sub U} and steepness parameter, {beta} gets calculated and the variation of different optical parameters like refractive index, extinction coefficient, dielectric constants, optical conductivity and surface and volume energy losses with photon energy are estimated.

Dhanya, I.; Menon, C. S. [School of Pure and Applied Physics, Mahatma Gandhi University, Priyadarshini Hills, Kottayam, Kerala, 686 560 (India)

2011-10-20

221

Excess enthalpies of binary and ternary mixtures containing tert-amyl methyl ether (TAME), tert-amyl alcohol (TAOH) and hexane at 298.15 and 313.15 K  

Microsoft Academic Search

Experimental excess enthalpies of the ternary system tert-amyl methyl ether (TAME)+tert-amyl alcohol (TAOH)+hexane and the corresponding binary subsystems at 313.15K are reported. Also the systems TAME + TAOH and TAOH + hexane have been measured at 298.15K. A quasi-isothermal flow calorimeter has been modified and tested to make the measurements. The experimental data have been fitted using a polynomial equation

Cristina Alonso; César R. Chamorro; José J. Segovia; Mar??a C. Mart??n; Eduardo A. Montero; Miguel A. Villamañán

2004-01-01

222

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

223

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

224

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

225

Supporting Information A scalable synthesis of the (S)-4-(tert-butyl)-2-(pyridin-2-yl)-4,5-dihydrooxazole  

E-print Network

with a three-pitched curved blade, an internal thermometer, and a reflux condenser equipped with a two a steam of N2. The flask was charged with (S)-tert-leucine (15.08 g, 115.0 mmol, 1.00 equv, 99% ee and replaced by a condenser and the reaction was heat to reflux (80 °C oil bath). After 20 h the reaction

Stoltz, Brian M.

226

Double-Addition Reaction of Aryl Methyl Sulfones with N-tert-Butylsulfinyl Imines: Diastereoselective and Concise Synthesis of 2-Sulfonylated 1,3-Diamines.  

PubMed

We report a double-addition reaction of methyl phenyl sulfone and methyl 2-pyridyl sulfone with N-tert-butylsulfinyl imines. This method provides concise access to 2-sulfonylated 1,3-anti diamines with good to excellent diastereoselectivities. This protocol has the benefit of using readily accessible starting materials and is operationally simple. PMID:25288374

Li, Ya; Li, Desheng; Zheng, Tao; Li, Hongsen; Ren, Xinfeng

2014-11-10

227

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...

228

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

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; Rohwerder, Thore

2012-03-01

229

Isolation of a Bacterial Culture That Degrades Methyl t-Butyl Ether  

PubMed Central

We have isolated a mixed bacterial culture (BC-1) which is capable of degrading the gasoline oxygenate methyl t-butyl ether (MTBE). BC-1 was developed from seed microorganisms present in a chemical plant biotreater sludge. This enrichment culture has been maintained in continuous culture treating high concentrations of MTBE (120 to 200 mg/liter) as the sole carbon source in a simple feed containing NH4+, PO43-, Mg2+, and Ca2+ nutrients. The unit had a stable MTBE removal rate when maintained with a long cell retention time (ca. 80 to 90 days); however, when operated at a ?50-day cell waste rate, loss of MTBE-degrading activity was observed. The following three noteworthy experimental data show that MTBE is biodegraded extensively by BC-1: (i) the continuous (oxygen-sparged) culture was able to sustain a population of autotrophic ammonia-oxidizing bacteria which could nitrify influent NH4+ concentrations at high rates and obtain CO2 (sole carbon source for growth) from the metabolism of the alkyl ether, (ii) BC-1 metabolized radiolabeled either (14CH3O-MTBE) to 14CO2 (40%) and 14C-labeled cells (40%), and (iii) cell suspensions of the culture were capable of degrading (substrate depletion experiments) MTBE to t-butyl alcohol, a primary metabolite of MTBE. BC-1 is a mixed culture containing several bacterial species and is the first culture of its kind which can completely degrade an alkyl ether. PMID:16349335

Salanitro, J. P.; Diaz, L. A.; Williams, M. P.; Wisniewski, H. L.

1994-01-01

230

Determination of endocrine disruptors in water after derivatization with N-methyl- N-( tert.-butyldimethyltrifluoroacetamide) using gas chromatography with mass spectrometric detection  

Microsoft Academic Search

The combined gas chromatographic determination of a number of hydroxyl-group containing endocrine disruptors, including 4-octylphenol, 4-nonylphenol, 2,4-dichlorophenol, pentachlorophenol, 4-tert.-butylbenzoic acid, bisphenol-A, 17?-estradiol and 17?-ethynylestradiol, was investigated. Derivatization, required for sensitive determination of these compounds, was carried out using N-methyl-N-(tert.-butyldimethyltrifluoroacetamide). A number of parameters affecting the derivatization reaction, like temperature, time, matrix, solvent, and amount of reagent were studied in detail.

Hans G. J Mol; Suryati Sunarto; Odile M Steijger

2000-01-01

231

Induction of Heme Oxygenase1 (HO1) and NAD[P]H: Quinone Oxidoreductase 1 (NQO1) by a Phenolic Antioxidant, Butylated Hydroxyanisole (BHA) and Its Metabolite, tert -Butylhydroquinone (tBHQ) in Primary-Cultured Human and Rat Hepatocytes  

Microsoft Academic Search

Purpose  This study was aimed to investigate the effects of a phenolic antioxidant, butylated hydroxyanisole (BHA) and its metabolite, tert-butylhydroquinone (tBHQ) on the induction of HO-1, NQO1 and Nrf2 proteins and their regulatory mechanisms in primary-cultured hepatocytes.Methods  After exposure of BHA and tBHQ to primary-cultured rat and human hepatocytes and mouse neonatal fibroblasts (MFs), Western blot, semi-quantitative RT-PCR and microarray analysis were

Young-Sam Keum; Yong-Hae Han; Celine Liew; Jung-Hwan Kim; Changjiang Xu; Xiaoling Yuan; Michael P. Shakarjian; Saeho Chong; Ah-Ng Kong

2006-01-01

232

Dinuclear and polynuclear transition metal complexes with macrocyclic ligands. 6. New dinuclear copper(ii) complexes with macrocyclic Schiff bases derived from 4- tert -butyl-2,6-diformylphenol  

Microsoft Academic Search

New dinuclear complexes containing CuII atoms in the cavity of a macrocyclic Schiff base were prepared by template condensation of 4-tert-butyl-2,6-diformylphenol with 1,3-diaminopropane in the presence of CuII trimethylacetate and chloride as well as by extra-ligand exchange. The mononuclear CuII complex with two 1,3-diaminopropane molecules can serve as an intermediate in this template synthesis. The reaction of CuII trimethylacetate with

V. V. Roznyatovsky; N. E. Borisova; M. D. Reshetova; Yu. A. Ustynyuk; G. G. Aleksandrov; I. L. Eremenko; I. I. Moiseev

2004-01-01

233

One-Pot Synthesis of TBMPS (bis [tertButyl)-1 Pyrenylmethyl-Silyl) Chloride as a Novel Fluorescent Silicon-Based Protecting Group for Protection of 5?OH Nucleosides and Its Use as Purification Handle in Oligonucleotide Synthesis  

Microsoft Academic Search

An efficient and novel synthesis of bis(tert-butyl)-1-pyrenylmethyl-silyl group (TBMPS) has been reported having fluorescent properties conferred by the pyrenyl group. This silyl group being base labile is efficiently used for one-pot protection of the 5?-OH of the nucleosides. While incorporated terminally at the 5?-OH of long sequences viz. AA TGG AGC CAG T and GC TAT GTC AGT TCC CCT

Snehlata Tripathi; Krishna Misra; Yogesh S. Sanghvi

2005-01-01

234

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

235

Effects of consumption of rooibos (Aspalathus linearis) and a rooibos-derived commercial supplement on hepatic tissue injury by tert-butyl hydroperoxide in Wistar rats.  

PubMed

This study investigated the antioxidative effect of rooibos herbal tea and a rooibos-derived commercial supplement on tert-butyl hydroperoxide- (t-BHP-) induced oxidative stress in the liver. Forty male Wistar rats consumed fermented rooibos, unfermented rooibos, a rooibos-derived commercial supplement, or water for 10 weeks, while oxidative stress was induced during the last 2 weeks via intraperitoneal injection of 30 µmole of t-BHP per 100 g body weight. None of the beverages impaired the body weight gain of the respective animals. Rats consuming the rooibos-derived commercial supplement had the highest (P < 0.05) daily total polyphenol intake (169 mg/day) followed by rats consuming the unfermented rooibos (93.4 mg/day) and fermented rooibos (73.1 mg/day). Intake of both the derived supplement and unfermented rooibos restored the t-BHP-induced reduction and increased (P < 0.05) the antioxidant capacity status of the liver, while not impacting on lipid peroxidation. The rooibos herbal tea did not affect the hepatic antioxidant enzymes, except fermented rooibos that caused a decrease (P < 0.05) in superoxide dismutase activity. This study confirms rooibos herbal tea as good dietary antioxidant sources and, in conjunction with its many other components, offers a significantly enhanced antioxidant status of the liver in an induced oxidative stress situation. PMID:24738022

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

2014-01-01

236

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

NASA Astrophysics Data System (ADS)

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

Banerjee, Saikat; Bagchi, Biman

2013-10-01

237

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

PubMed

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

238

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

239

Solvent extraction of technetium from alkaline waste media using bis-4,4{prime}(5{prime})[(tert-butyl)cyclohexano]-18-crown-6  

SciTech Connect

The crown ether bis-4,4`(5`)[(tert-butyl)cyclohexano]-18-crown-6 can be utilized in a solvent-extraction process for the removal of technetium as pertechnetate ion, TcO{sub 4}{sup {minus}} from solutions simulating highly radioactive alkaline defense wastes (``tank wastes``) stored at several sites in the United States. The process employs non-halogenated and non-volatile diluents and modifiers and includes an efficient stripping procedure using only water. More than 95% of the pertechnetate present at 6 {times} 10{sup {minus}5} M in Melton Valley (Oak Ridge, TN) and Hanford (Washington) tank-waste simulants was removed following two cross-current extraction contacts using 0.02 M bis-4,4`(5`)[(tertbutyl)cyclohexano]- 18-crown-6 in 2:1 vol/vol TBP/Isopar{reg_sign} M diluent at 25 C. Similarly, for both simulants, more than 98% of the pertechnetate contained in the solvent was back-extracted following two cross-current stripping contacts using deionized water.

Bonnesen, P.V.; Presley, D.J.; Moyer, B.A.

1995-07-01

240

Bis[O,O?-bis-(4-tert-butyl-phen-yl) di-thio-phosphato-?2 S,S?]bis-(pyridine-?N)lead(II)  

PubMed Central

In the title compound, [Pb(C20H26O2PS2)2(C5H5N)2], the PbII ion is coordinated by two S,S?-bidentate anions and two pyridine mol­ecules. The PbN2S4 coordination geometry approximates to a penta­gonal bipyramid with one equatorial site vacant. The N atoms occupy the axial sites. One of the pyridine mol­ecules is disordered over two sets of sites in a 0.907?(7):0.093?(7) ratio and one of the tert-butyl groups is disordered over two sets of sites in a 0.534?(6):0.466?(6) ratio. An intra­molecular C—H?O inter­action occurs in one of the ligands. In the crystal, pairs of short Pb?S contacts [3.4018?(11)?Å] generate a centrosymmetric dimeric assembly with the distant S atom lying in the region of the vacant coordination site of the metal atom. No directional packing inter­actions occur. PMID:24427011

Zhang, Xiulan; Xie, Bin; He, Linxin; Lu, Lu; Chen, Neng

2013-01-01

241

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

242

tert-Butyl hydroperoxide-induced differing plasma membrane and oxidative stress processes in yeast strains BY4741 and erg5?.  

PubMed

The molecular mechanism of tert-butyl hydroperoxide (t-BuOOH) elicited cytotoxicity and the background of t-BuOOH sensitivity were studied in the Saccharomyces cerevisiae ergosterol-less gene deletion mutant erg5? and its parental strain BY4741. In comparison to BY4741, untreated erg5? cells exhibited alterations in sterol and fatty acid compositions of the plasma membrane, as reflected by the inherent amphotericin B resistance, an elevated level (31%) of plasma membrane rigidity and a decreased uptake of glycerol. Surprisingly, the untreated erg5? cells exhibited an unbalanced intracellular redox state, accompanied by the continuous upregulation of the antioxidant enzymes Mn superoxide dismutase, catalase, and glutathione S-transferase, which resulted in decreased specific concentrations of superoxide and peroxides and elevated levels of the hydroxyl radical and thiols. The 2.5-fold sensitivity of erg5? to t-BuOOH suggested that the oxidative stress adaptation processes of the mutant could not restore the redox homeostasis of the cells and there is an overlap between sterol and redox homeostases. t-BuOOH treatment of both strains induced adaptive modification of the sterol and fatty acid compositions, increased the plasma membrane fluidity and elevated the specific activities of most antioxidant enzymes through specific regulation processes in a strain-dependent manner. PMID:24687861

Gazdag, Zoltán; Máté, Gábor; Certik, Milan; Türmer, Katalin; Virág, Eszter; Pócsi, István; Pesti, Miklós

2014-07-01

243

Solvent injection-lyophilization of tert-butyl alcohol/water cosolvent systems for the preparation of drug-loaded solid lipid nanoparticles.  

PubMed

A simple procedure involving solvent injection-lyophilization (SIL) was used to prepare solid lipid nanoparticles (SLNs). A tert-butyl alcohol (t-BA) solution containing lipids was injected into a stirred aqueous solution containing lyoprotectants to form SLNs dispersed in a t-BA/water cosolvent system. The t-BA/water cosolvent SLN dispersion was subsequently lyophilized to obtain a dry product which, upon rehydration, formed an aqueous dispersion of spherical SLNs with a size under 200 nm. A lipophilic drug, cinnarizine, was dissolved in t-BA at a drug-to-lipid mass ratio of 1:20 and almost 100% of the drug was entrapped in the formed SLNs following the SIL process. Likewise, hydrophilic 5-fluorouracil, after being solubilized in t-BA through forming anhydrous reverse micelles, could be entrapped in SLNs with an encapsulation efficiency up to 15.6%. Differential scanning calorimetry and small angle X-ray scattering analysis proved that the lipids in the formed SLNs were in a stable beta-form, and there was no recrystallization expulsion of drugs during storage. In contrast to the conventional solvent injection method, the SIL procedure was not time-consuming and no relatively high-temperature evaporation was needed to remove organic solvents. Moreover, the efficiency of the lyophilization was markedly enhanced due to use of the t-BA/water cosolvent system. Thus, the SIL procedure was found to be an efficient method for preparing stable drug-loaded SLNs. PMID:20447810

Wang, Ting; Wang, Ning; Zhang, Yingying; Shen, Wancui; Gao, Xingmei; Li, Tiefu

2010-08-01

244

Photothermal tautomerization of a UV sunscreen (4-tert-butyl-4'-methoxydibenzoylmethane) in acetonitrile studied by steady-state and laser flash photolysis.  

PubMed

The photothermal tautomerization processes between enol and keto forms of 4-tert-butyl-4'-methoxydibenzoylmethane (trade name, Avobenzone) in acetonitrile have been studied by steady-state and laser flash photolysis. The keto form is produced upon photolysis of the enol in only acetonitrile with a quantum yield of 0.014. The molar absorptivity of the keto form was determined. Phototautomerization from the keto to the enol form was not seen. Laser flash photolysis of the keto form recognized the formation of the triplet state. In the dark, the keto form underwent thermal tautomerization to the enol with a lifetime of 5.1 h at 295 K. The enolization rate in acetonitrile was not accelerated by the presence of alcohols and/or water but increased with increasing temperature and followed the Arrhenius expression. The activation energy and the frequency factor were determined for the enolization process from the keto to the enol form. On the basis of the energy states of the tautomers and isomers as estimated by DFT calculations, a schematic energy diagram was determined for the photothermal tautomerization processes in acetonitrile. PMID:23410191

Yamaji, Minoru; Kida, Mayumi

2013-03-01

245

Adaptation to tert-butyl hydroperoxide at a plasma membrane level in the fission yeast Schizosaccharomyces pombe parental strain and its t-BuOOH-resistant mutant.  

PubMed

The one-gene mutant hyd1-190 of the fission yeast Schizosaccharomyces pombe displayed four-fold resistance to tert-butyl hydroperoxide (t-BuOOH) in comparison with its parental strain hyd(+). The cells of hyd1-190 exhibited a quantitative alteration in the sterol content and hence in the fatty acid composition of the plasma membrane, reflected in a two-fold amphotericin B sensitivity, increased rigidity of the plasma membrane, revealed by an elevated (?7.9?°C) phase-transition temperature, measured by means of electron paramagnetic resonance spectroscopy, and a significantly decreased uptake of glycerol. Treatment of the strains with a subinhibitory concentration (0.2?mM) of t-BuOOH induced adaptation via modification of the sterol and fatty acid compositions, resulting in increased (?3.95?°C) and decreased (?6.83?°C) phase-transition temperatures of the hyd(+) and hyd1-190 strains, respectively, in order to defend the cells against the consequences of t-BuOOH-induced external oxidative stress. However, in contrast with hyd(+), hyd1-190 lacks the ability to adapt to t-BuOOH at a cell level. PMID:23712692

Kálmán, Nikoletta; Gazdag, Zoltán; ?ertík, Milan; Belágyi, József; Selim, Samy A; Pócsi, István; Pesti, Miklós

2014-03-01

246

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

E-print Network

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 $x_{\\text{TBA}} \\approx 0.03 - 0.07$. 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 $x_{\\text{TBA}} \\approx 0.05$. 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 non-linearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, $x_{\\text{TBA}} \\approx 0.45$, 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.

Saikat Banerjee; Jonathan Furtado; Biman Bagchi

2014-02-20

247

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

E-print Network

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 $x_{\\text{TBA}} \\approx 0.03 - 0.07$. 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 $x_{\\text{TBA}} \\approx 0.05$. 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 non-linearity. Interestingly, water mol...

Banerjee, Saikat; Bagchi, Biman

2014-01-01

248

Spectroscopic and electrochemical characterization of di- tert-butylated sterically hindered Schiff bases and their phenoxyl radicals  

NASA Astrophysics Data System (ADS)

A series of sterically hindered N-arylsalicylaldimines (SAs) previously prepared from substituted salicylaldehydes (X-Sal, where X = H, Cl, Br, NO 2, OH, OCH 3) and 2,6-di- t-butyl-1-hydroxyaniline (L xH) and 2,5-di- t-butylaniline (L x'H) were characterized by 1H and 13C NMR, UV-Vis and electrochemical methods. The electronic spectra (ES) (X = OH, OCH 3) in alcoholic solvents (MeOH, EtOH, PrOH, iso-PrOH) unlike other solvents exhibit a new absorption band in the region 630-675 nm ( ?=19-242 M -1 cm -1), which are not characteristic for other SA known in literature. The ESR studies of primary phenoxyl radicals generated from L xH by their oxidation with PbO 2 reveal that some of them with the time are converted to more stable secondary Coppinger's radical. The cyclic voltammograms of L xH and L x'H except NO 2-substituted ones in CH 3CN are similar and along with two or three irreversible anodic waves at the potentials ranging from 0.0 to +1.9 V versus Ag/AgCl, also display one or two irreversible reduction waves at potentials -0.6 to +0.5 V. A series of a new SA prepared from 3,5-di- t-butylsalicylaldehyde and mono-substituted anilines (X = H, o-, p-F, Cl, Br, OCH 3, p- t-butyl, 5,6-benzo) were characterized by analytical, spectroscopic (IR, UV-Vis, 1H and 13C NMR), and electrochemical techniques. The ES spectra of o-, p-Cl, p-Br, o-CH 3 and 5,6-benzo-substituted SA did not exhibit expected absorptions at 400-500 nm in alcoholic solutions.

Kasumov, V. T.; Medjidov, A. A.; Yayli, N.; Zeren, Y.

2004-11-01

249

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

250

Synthesis of 3-(1Methyl1H-imidazol-2-ylthio)propanoic Acid and (E)-3-(1Methyl1H-imidazol-2-ylthio)acrylic Acid  

Microsoft Academic Search

The syntheses of 3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid and 3-(1-methyl-1H-imidazol-2-ylthio)propanoic acid, mitochondria-targeted prodrugs of the antioxidant methimazole, are described. The method of Fan et al. (Fan et al., Synthesis2006, 2286) for the reaction of phenols with propiolic acid and propiolate esters was modified to synthesize (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylic acid. The intermediate tert-butyl (E)-3-(1-methyl-1H-imidazol-2-ylthio)acrylate was prepared by the reaction of tert-butyl propiolate with methimazole; the use

Christopher M. Hattan; Jalil Shojaie; Serrine S. Lau; M. W. Anders

2012-01-01

251

Perfluoro-tert-butyl-homoserine as a sensitive 19F NMR reporter for peptide-membrane interactions in solution.  

PubMed

Fluorine ((19)F) NMR is a valuable tool for studying dynamic biological processes. However, increasing the sensitivity of fluorinated reporter molecules is a key to reducing acquisition times and accessing transient biological interactions. Here, we evaluate the utility a novel amino acid, L-O-(perfluoro-t-butyl)-homoserine (pFtBSer), that can easily be synthesized and incorporated into peptides and provides greatly enhanced sensitivity over currently used (19)F biomolecular NMR probes. Incorporation of pFtBSer into the potent antimicrobial peptide MSI-78 results in a sharp (19)F NMR singlet that can be readily detected at concentrations of 5 µm and lower. We demonstrate that pFtBSer incorporation into MSI-78 provides a sensitive tool to study binding through (19)F NMR chemical shift and nuclear relaxation changes. These results establish future potential for pFtBSer to be incorporated into various proteins where NMR signal sensitivity is paramount, such as in-cell investigations. PMID:23509011

Buer, Benjamin C; Levin, Benjamin J; Marsh, E Neil G

2013-05-01

252

Synthesis of highly methanol selective membranes for separation of methyl tertiary butyl ether (MTBE)–methanol mixtures by pervaporation  

Microsoft Academic Search

Methyl tertiary butyl ether (MTBE) is now being extensively used as a lead-free octane enhancer for green fuel. Pervaporative separation process is used for separation of methanol–MTBE mixtures encountered during manufacturing of MTBE. Three different copolymers of acrylamide with increasing amount of 2-hydroxyethyl methacrylate (HEMA), i.e. PAMHEMA-1, -2 and -3 were synthesized and the cross-linked (gelled) copolymer membranes made from

S. Ray

2006-01-01

253

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

254

Poly[tetra-butyl-ammonium [chlorido-hexa-methyl-?3-sulfato-distannate(IV)  

PubMed

In the structure of the title coordination polymer, {(C16H36N)[Sn2(CH3)6Cl(SO4)]} n , the two independent Sn(IV) atoms are coordinated in a trigonal-bipyramidal manner by three methyl groups in the equatorial plane and in the axial positions by either two O atoms of bridging SO4 (2-) anions or by a Cl atom and one O atom of a bridging SO4 (2-) anion, respectively. The [Sn2(CH3)6Cl(SO4)](-) anion forms an infinite zigzag chain parallel to the c axis. The cations are situated between these chains. Two of the four butyl groups of the cation are partially disordered over two sets of sites with site occupancies of 0.79?(2):0.21?(2) and 0.75?(2):0.25?(2), respectively. Weak C-H?O hydrogen-bonding inter-actions help to consolidate the crystal packing. PMID:24046577

Diop, Tidiane; van der Lee, Arie; Sidibé, Mamadou

2013-01-01

255

?-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

256

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

257

Electronic structure and electron dynamics at an organic molecule/metal interface: interface states of tetra-tert-butyl-imine/Au(111)  

NASA Astrophysics Data System (ADS)

Time- and angle-resolved two-photon photoemission (2PPE) spectroscopies have been used to investigated the electronic structure, electron dynamics and localization at the interface between tetra-tert-butyl imine (TBI) and Au(111). At a TBI coverage of one monolayer (ML), the two highest occupied molecular orbitals, HOMO and HOMO-1, are observed at an energy of -1.9 and -2.6 eV below the Fermi level (EF), respectively, and coincide with the d-band features of the Au substrate. In the unoccupied electronic structure, the lowest unoccupied molecular orbital (LUMO) has been observed at 1.6 eV with respect to EF. In addition, two delocalized states that arise from the modified image potential at the TBI/metal interface have been identified. Their binding energies depend strongly on the adsorption structure of the TBI adlayer, which is coverage dependent in the submonolayer (<=1 ML) regime. Thus the binding energy of the lower interface state (IS) shifts from 3.5 eV at 1.0 ML to 4.0 eV at 0.5 ML, which is accompanied by a pronounced decrease in its lifetime from 100 fs to below 10 fs. This is a result of differences in the wave function overlap with electronic states of the Au(111) substrate at different binding energies. This study shows that in order to fully understand the electronic structure of organic adsorbates at metal surfaces, not only adsorbate- and substrate-induced electronic states have to be considered but also ISs, which are the result of a potential formed by the interaction between the adsorbate and the substrate.

Hagen, Sebastian; Luo, Ying; Haag, Rainer; Wolf, Martin; Tegeder, Petra

2010-12-01

258

Affinity probes for the GABA-gated chloride channel: 5 e- tertButyl2 e-[4-(substituted-ethynyl)phenyl]-1,3-dithianes with photoactivatable, fluorescent, biotin, agarose and protein substituents  

Microsoft Academic Search

Affinity probes for the noncompetitive blocker or picrotoxinin site of the ?-aminobutyric acid (GABA)-gated chloride channel were designed for four types of applications: photoaffinity reagents to covalently label the binding site; fluorescent probes for receptor analysis; biotinylated compounds and agarose\\/sepharose conjugates for affinity chromatography; ligand-protein\\/enzyme conjugates for immunoassay. These 5e-tert-butyl-2e-[4-(substituted-ethynyl)phenyl]-1,3-dithianes were optimized by structure-activity studies for potency as inhibitors of

Qing X. Li; John E. Casida

1995-01-01

259

Lower rim substituted tert-butylcalix[4]arenes (II). Complexing ability of 5,11,17,23-tetra- tert-butyl-25,26,27,28-tetrakis- O-(piperidinylcarbonyl)methylenecalix[4]arene. The crystal structures of the ligand and its sodium complex  

Microsoft Academic Search

The sodium(I) chloride and yttrium(III), lanthanum(III), samarium(III) and gadolinium(III) nitrate complexes of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis(piperidinylcarbonyl)methylene)calix[4]arene were prepared in direct reaction of the ligand and appriopriate metal salts and characterized by spectral data (IR, UV–Vis, 1H NMR, FAB MS), and elemental analysis. The transmetallation reactions of the sodium complex by the lanthanide ions was also achieved. The crystal structures of the ligand and

Maria Boche?ska; Anna Zieli?ska; Victor Ch Kravtsov; Maria Gdaniec; Emilia Luks; Wanda Radecka-Paryzek

2002-01-01

260

MEASUREMENT OF EXHALED BREATH AND VENOUS BLOOD TO DEVELOP A PHYSIOLOGICALLY BASED PHARMACOKINETIC MODEL FOR HUMAN EXPOSURE TO METHYL TERTIARY-BUTYL ETHER AND THE PRODUCTION OF THE BIOMARKER TERTIARY-BUTYL ALCOHOL  

EPA Science Inventory

Methyl tertiary-butyl ether (MTBE) is a common fuel additive used to increase the availability of oxygen in gasoline to reduce winter-time carbon monoxide emissions from automobiles. Also, MTBE boosts gasoline "octane" rating and, as such, allows reduction of benzene...

261

Synthesis and Thermo-Oxidative Aging Resistance of Hydroxyl Terminated Polybutadiene Bound 2,2-Thiobis(4-methyl-6-tert-butylphenol)  

Microsoft Academic Search

A novel polymeric antioxidant HTPB-IPDI-TPH was synthesized by the reaction between 2,2-thiobis (4-methyl-6-tert-butylphenol) (TPH) and an adduct (HTPB-IPDI) from hydroxyl terminated polybutadiene (HTPB) and isophorone diisocyanate (IPDI). The effects of raw materials ratio and the reaction condition were investigated by measuring the content of the residual –NCO groups of the reactants during the reaction. The structure of HTPB-IPDI-TPH was characterized

Yonghong Wang; Xingrong Zeng; Hongqiang Li; Jianhua Guo

2012-01-01

262

2-Bromo-5-tert-butyl-N-methyl-N-[2-(methyl-amino)-phen-yl]-3-(1-methyl-1H-benzimidazol-2-yl)benzamide  

PubMed Central

In the title compound, C27H29BrN4O, benzimidazole ring system and the amide moiety are planar [r.m.s. deviations = 0.016?(2) and 0.017?(1)?Å, respectively]. The mol­ecule adopts a conformation in which the amide linkage is almost perpendicular to the central ring [dihedral angle = 85.79?(8)°], while the benzimidazole ring system makes a dihedral angle of 70.26?(11)° with the central ring. In the crystal, the mol­ecules form dimers through N—H?O hydrogen bonds and C—H?O interactions. These dimers are further linked into zigzag ribbons along [201] by weak C—H?Br inter­actions. As a result of the bulky nature of the mol­ecule, as evidenced by the large dihedral angles between rings, there is little evidence for any ?–? inter­actions. PMID:25161598

Prasad, Poonam Rajesh; Das, Shikha; Singh, Harkesh B.; Butcher, Ray J.

2014-01-01

263

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...

264

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

PubMed

A series of binary oxide catalysts (ceria-ZnO) were prepared and doped with different amounts of palladium in the range of 0.5%-1.5%. The prepared catalysts were characterized by SEM, TEM, XRD and XPS, as well as by N2 sorptiometry study. The XPS results confirmed the structure of the Pd CeO2-x-ZnO. The photocatalytic activity of these catalysts was evaluated for degradation of MTBE in water. These photocatalyst efficiently degrade a 100ppm aqueous solution of MTBE upon UV irradiation for 5h in the presence of 100mg of each of these photocatalysts. The removal of 99.6% of the MTBE was achieved with the ceria-ZnO catalyst doped with 1% Pd. In addition to the Pd loading, the N2 sorptiometry study introduced other factors that might affect the catalytic efficiency is the catalyst average pore sizes. The photoreaction was determined to be a first order reaction. PMID:24275473

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

2014-01-15

265

Reaction of carboranyl boron-centered radicals with phosphites and the addition of carborane-containing and some other phosphoranyl radicals to 3,6-di-tert-butyl-ortho-benzoquinone  

SciTech Connect

The preparative photolysis of bis(m-carboran-9-yl)mercury and bis(p-carboran-2-yl)-mercury with trimethyl phosphite leads to the dimethyl esters of m- and p-B-carboranylphosphonic acids. The reaction of carboranyl boron-centered radicals with phosphites occurs through the formation of a phosphoranyl radical. The addition of the phosphoranyl radicals derived from 2,6,7-tris(trichloromethyl)-3,5,8-trioxo-1,4-diphosphabicyclo(2.2.2)octane to 3,6-di-tert-butyl-ortho-benzoquinone was detected. ESR spectroscopy was used to observe the tautomeric transfers of the phosphoranyl group between the ortho-benzoquinone oxygen atoms.

Tumanskii, B.L.; Kampel', V.Ts.; Bregadze, VI.; Bubnov, N.N.; Solodovnikov, S.P.; Prokof'ev, A.I.; Kozlov, E.S.; Godovikov, N.N.; Kabachnik, M.I.

1986-08-20

266

Solution and solid-state study of the structure of azo-coupling products from isomeric enaminones possessing tert-butyl group: An unprecedented observation of pure hydrazo form in azo coupled N-alkyl ?-enaminones  

NASA Astrophysics Data System (ADS)

The structure of the azo-coupling products from enaminones derived from 4,4-dimethyl-1-phenylpentane-1,3-dione has been studied by means of solution-state 1H, 13C and 15N NMR spectroscopy and X-ray diffractometry. The presence of bulky tert-butyl group hinders or even prevents from the formation of planar conjugated heterodiene system Hsbnd Nsbnd Cdbnd Csbnd Ndbnd N with an intramolecular hydrogen bond Nsbnd H⋯Ndbnd which is the prerequisite for fast tautomeric exchange imino-hydrazo - enamino-azo. The minor amount of azo compounds is formed by a proton exchange through a hydrogen bond Nsbnd H⋯N, which is either intramolecular (in solution) or intermolecular (solid state). The intermolecular exchange proceeds via the dimers of the azo coupling products. This is unprecedented result among the similar molecules hitherto studied.

Šim?nek, Petr; Pad?lková, Zde?ka; Machá?ek, Vladimír

2014-10-01

267

Physiologically based pharmacokinetic rat model for methyl tertiary-butyl ether; comparison of selected dose metrics following various MTBE exposure scenarios used for toxicity and carcinogenicity evaluation  

Microsoft Academic Search

There are a number of cancer and toxicity studies that have been carried out to assess hazard from methyl tertiary-butyl ether (MTBE) exposure via inhalation and oral administration. MTBE has been detected in surface as well as ground water supplies which emphasized the need to assess the risk from exposure via drinking water contamination. This model can now be used

Susan J. Borghoff; Horace Parkinson; Teresa L. Leavens

2010-01-01

268

1-sec-Butyl-3-[hy-droxy(1-methyl-1H-indol-3-yl)methyl-idene]pyrrolidine-2,4-dione  

PubMed Central

In the title compound, C18H20N2O3, the dihedral angle between the indole ring system (r.m.s. deviation = 0.018?Å) and the hy­droxy­methyl­enepyrrolidine-2,4-dione plane (r.m.s. deviation = 0.036?Å) is 9.87?(7)°. The keto and enol groups are involved in an intra­molecular O—H?O hydrogen bond. An intra­molecular C—H?O inter­action also occurs. The sec-butyl group is disordered over two orientations corresponding to an approximate 180° rotation about the N—C bond, with occupancies of 0.670?(6) and 0.330?(6). In the crystal, mol­ecules are linked into chains along the c axis by C—H?O hydrogen bonds. PMID:21588613

Xu, Hai-zhen; Zhu, You-Quan

2010-01-01

269

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

Microsoft Academic Search

The solid phase microextraction (SPME) technique with on-fiber derivatization was evaluated for the analysis of alkylphenols (APs), including 4-tert-octylphenol (4-t-OP), technical nonylphenol isomers (t-NPs) and 4-nonylphenol (4-NP), in water. The 85?m polyacrylate (PA) fiber was used and a two-step sample preparation procedure was established. In the first step, water sample of 2mL was placed in a 4mL PTFE-capped glass vial.

Yi-Ping Pan; Shih-Wei Tsai

2008-01-01

270

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

271

Mechanistic basis for inflammation and tumor promotion in lungs of 2,6-di-tert-butyl-4-methylphenol-treated mice: electrophilic metabolites alkylate and inactivate antioxidant enzymes.  

PubMed

An established model for mechanistic analysis of lung carcinogenesis involves administration of 3-methylcholanthrene to mice followed by several weekly injections of the tumor promoter 2,6-di-tert-butyl-4-methylphenol (BHT). BHT is metabolized to quinone methides (QMs) responsible for promoting tumor formation. QMs are strongly electrophilic and readily form adducts with proteins. The goal of the present study was to identify adducted proteins in the lungs of mice injected with BHT and to assess the potential impact of these modifications on tumorigenesis. Cytosolic proteins from treated mouse lungs were separated by two-dimensional electrophoresis, adducts detected by immunoblotting, and proteins identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Eight adducts were detected in the lungs of most, or all, of six experimental groups of BALB mice. Of these adducts, several were structural proteins, but others, namely, peroxiredoxin 6 (Prx6), Cu,Zn-superoxide dismutase (SOD1), carbonyl reductase, and selenium-binding protein 1, have direct or indirect antioxidant functions. When the 9000g supernatant fraction of mouse lung was treated with BHT-QM (2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone), substantial lipid peroxidation and increases in hydrogen peroxide and superoxide formation were observed. Studies with human Prx6 and bovine SOD1 demonstrated inhibition of enzyme activity concomitant with adduct formation. LC-MS/MS analysis of digests of adducted Prx6 demonstrated adduction of both Cys 91 and Cys 47; the latter residue is essential for peroxidatic activity. Analysis of QM-treated bovine SOD1 by matrix-assisted laser desorption/ionization time-of-flight MS demonstrated the predominance of a monoadduct at His 78. This study provides evidence that indicates Prx6, SOD1, and possibly other antioxidant enzymes in mouse lung are inhibited by BHT-derived QMs leading to enhanced levels of reactive oxygen species and inflammation and providing a mechanistic basis for the effects of BHT on lung tumorigenesis. PMID:17305404

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

2007-02-01

272

Final Report On the Safety Assessment of Glycolic Acid, Ammonium, Calcium, Potassium, and Sodium Glycolates, Methyl, Ethyl, Propyl, and Butyl Glycolates, and Lactic Acid, Ammonium, Calcium, Potassium, Sodium, and Tea-Lactates, Methyl, Ethyl, Isopropyl, and Butyl Lactates, and Lauryl, Myristyl, and Cetyl Lactates  

Microsoft Academic Search

This report provides a review of the safety of Glycolic Acid, Ammonium, Calcium, Potassium, and Sodium Glycolates, Methyl, Ethyl, Propyl, and Butyl Glycolates, Lactic Acid, Ammonium, Calcium, Potassium, Sodium, and TEA-Lactates, and Lauryl, Myristyl, and Cetyl Lactates. These ingredients belong to a group known as alpha-hydroxy acids (AHAs). Products containing these ingredients may be for consumer use, salon use, or

F. A. Andersen

1998-01-01

273

Actual commuter exposure to methyl-tertiary butyl ether, benzene and toluene while traveling in Korean urban areas.  

PubMed

This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, and toluene on actual commuting routes, not hypothetical routes as used in many previous in-vehicle exposure studies of volatile organic compounds (VOCs). It focuses on four potentially influencing factors (transportation mode, passenger-car type, time of day, and season). A total of 40 passenger car commuters and 20 public bus commuters were recruited. The same commuters participated in both the summer and winter studies. The transportation mode, passenger-car type and commute season were all found to affect the in-vehicle levels of the target VOCs. Conversely, the commute time of day had little effect on the in-car and in-bus levels of the target compounds. The present study also confirmed that under Korean commuting conditions, passenger car and public bus interiors are important microenvironments for exposure to MTBE, benzene and toluene. This is supported by a previous finding that both in-car and in-bus air levels of the target VOCs tend to be much higher than ambient air levels of the compounds. Meanwhile, some spurious gasoline sold during the experimental periods appears to have elevated the in-car and in-bus exposures to toluene compared with those reported by some previous studies conducted in the same study area. PMID:12150439

Lee, Jin-Woo; Jo, Wan-Kuen

2002-05-27

274

Construction of wettability gradient surface on copper substrate by controlled hydrolysis of poly(methyl methacrylate-butyl acrylate) films  

NASA Astrophysics Data System (ADS)

We report a gradient wettability surface on copper slide prepared by a simple controlled ester group hydrolysis procedure of poly(methyl methacrylate-butyl acrylate) [P (MMA-BA)] films coated on the copper substrate. In the method, sodium hydroxide solutions are selected to prepare surface gradient wettability on P (MMA-BA) films. The P (MMA-BA) copolymers with different MMA contents are first synthesized by a conventional free atom radical solution polymerization method. The transfer of surface chemical composition from the ester group to acid salt is achieved by hydrolysis in NaOH solution. The effects of different concentrations of NaOH solution and reaction times on the physicochemical properties of the resulting surfaces are studied. The field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) results show that the varying concentration along the substrate length is only attributed to the hydrolysis reaction of ester groups. The hydrolysis causes insignificant change on the morphology of the original film on the copper substrate. In addition, it is found that the MMA copolymer content has a significant influence on the concentration of ester groups on the outermost surface and thus important for forming the slope gradients.

Zhang, Yong; Cheng, Jiang; Yang, Zhuo-ru

2014-10-01

275

The impact of groundwater quality on the removal of methyl tertiary-butyl ether (MTBE) using advanced oxidation technology.  

PubMed

In this study, the removal of methyl tertiary-butyl ether (MTBE) from contaminated groundwater using advanced oxidation technology was investigated. The UV/H(2)O(2) treatment process was applied to remove MTBE from two Saudi groundwater sources that have different quality characteristics with regard to their contents of inorganic species such as chloride, bromide, sulfates and alkalinity. MTBE was spiked into water samples collected from the two sources to a concentration level of about 250 microg/L. A 500 mL bench-scale forced-liquid circulation photoreactor was used to conduct the experiments. Two different UV lamps were utilized: 15 Watt low pressure (LP) and 150 Watt medium pressure (MP). Results of the study showed that the UV/H(2)O(2) process removed more than 90% of MTBE in 20 minutes when the MP lamp was used at an MTBE/H(2)O(2) molar ratio of 1:200. The results also showed that groundwater sources with higher levels of radical scavengers such as alkalinity, bromide, nitrate and sulfate showed lower rate of MTBE removal. PMID:19844063

Tawabini, B; Fayad, N; Morsy, M

2009-01-01

276

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

277

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

PubMed

Methyl t-butyl ether (MTBE) and ethyl t-butyl ether (ETBE) are commonly used in unleaded gasoline to increase the oxygen content of fuel and to reduce carbon monoxide emissions from motor vehicles. This study was undertaken to investigate: (1) the effect of administration to rats of ETBE and its metabolite, t-butanol, on the induction and/or inhibition of hepatic P450 isoenzymes; (2) the oxidative metabolism of MTBE and ETBE by liver microsomes from rats pretreated with selected P450 inducers and purified rat P450(s), (2B1, 2E1, 2C11, 1A1). ETBE administration by gavage at a dose of 2 ml/kg for 2 days induced hepatic microsomal P4502E1-linked p-nitrophenol hydroxylase and the P4502B1/2-associated PROD and 16beta-testosterone hydroxylase, verified by immunoblot experiments. t-Butanol treatments at doses of 200 and 400 mg/kg i.p. for 4 days did not alter any liver microsomal monoxygenases. Both MTBE and ETBE were substrates for rat liver microsomes and were oxidatively dealkylated to yield formaldehyde and acetaldehyde, respectively. The dealkylation rates of both MTBE and ETBE were increased c. fourfold in phenobarbital (PB)-treated rats. In rats pretreated with pyrazole, an inducer of 2E1, only the demethylation of MTBE was increased (c. twofold). When the oxidations of MTBE and ETBE were investigated with purified P450(s) in a reconstituted system, it was found that P4502B1 had the highest activities towards both solvents, whereas 1A1 and 2C1 were only slightly active; P4502E1 had an appreciable activity on MTBE but not against ETBE. Metyrapone, a potent inhibitor of P450 2B, consistently inhibited both the MTBE and ETBE dealkylations in microsomes from PB-treated rats. Furthermore, 4-methylpyrazole (a probe inhibitor of 2E1) and anti-P4502E1 IgG showed inhibition, though modest, only on MTBE demethylation, but not on ETBE deethylation. Inhibition experiments have also suggested that rat 2A1 may exert an important role in MTBE and ETBE oxidation. Taken together, these results indicate that 2B1, when expressed, is the major enzyme involved in the oxidation of these two solvents and that 2E1 may have a role, although minor, in MTBE demethylation. The implications of these data for MTBE and ETBE toxicity remain to be established. PMID:9587015

Turini, A; Amato, G; Longo, V; Gervasi, P G

1998-03-01

278

Formation of alkenes via degradation of tert-alkyl ethers and alcohols by Aquincola tertiaricarbonis L108 and Methylibium spp.  

PubMed

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

2011-09-01

279

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

280

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

PubMed

2,6-Di-tert-butyl-p-cresol (DBPC), dibenzyl disulfide (DBDS), and 1,2,3-benzotriazole (BTA) are additives that may be found concomitantly in the oil matrix of power transformer. DBPC and DBDS act as antioxidants while, BTA is a corrosion inhibitor that protects copper conductors inside the transformer unit from corrosion. A powerful analytical method is, therefore, required to determine these additives at trace levels in the transformer oil. This work describes a unique single liquid-liquid extraction pretreatment step prior to the determination of the components by gas chromatography (GC) and high-performance liquid chromatography (HPLC) techniques. The optimum volume ratio used in the pretreatment step was determined as 5:2:5 for mineral oil/n-hexane/acetonitrile, respectively. Relatively, the method is simple and quick with a minimal use of solvents. Analytical results indicate that the method is relatively sensitive, accurate, and precise for each of the three components in fresh and used mineral oil. The calibration curves for the three components demonstrate a significant increase in sensitivities. Detection limits found were, 100 mg L(-1) (0.01% w/v), 0.80 mg L(-1) , and 2.04 mg L(-1) for DBPC, DBDS, and BTA, respectively. The Student's t values determined at 95% confidence level indicate that there is no significant difference between the experimental means obtained by this method and the standard method for each component. PMID:22311820

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

2012-03-01

281

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

282

Exchange pathways in tris-mu-thiolato-bridged [Cr(2)L(3)](ClO(4)2Cl*H2O*MeOH (L=2,6-bis(aminomethyl)-4-tert-butyl-thiophenolate).  

PubMed

From polarized optical absorption and emission spectra of the tris-mu-thiolato bridged [Cr(2)L(3)](ClO(4))(2)Cl.H(2)O.MeOH (L = 2,6-bis(aminomethyl)-4-tert-butyl-thiophenolate) 1 in the visible and near UV, the exchange splittings of the (4)A(2) ground and the (2)E and (2)T(1) excited states are determined. In view of the large Cr-Cr distance of 3.01 A, the antiferromagnetic ground state splitting with J = 78 cm(-1) (H = J(S(A).S(B))) is large compared to other triply bridged Cr(3+) dimers. This can be rationalized using a model based on a valence bond approach, in which the exchange splittings are derived from configuration interactions between the ground electron configuration and ligand-to-metal (LMCT) as well as metal-to-metal (MMCT) charge-transfer configurations. It allows us to distinguish the interactions via ligand orbitals from the direct interactions between the metal-centered orbitals. We compare our results with those obtained for the tri-mu-hydroxo-bridged [Cr(2)(OH)(3)(tmtame)(2)](NO(3))(3) (tmtame = N,N',N' '-trimethyl-1,1,1-tris(aminomethyl)ethane) 2. In the latter the interactions via the ligands are negligible, whereas they play an important role in 1, due to the softness of the sulfur ligand atoms. PMID:11421680

Schenker, R; Weihe, H; Güdel, H U; Kersting, B

2001-07-01

283

Phenyl-?-tert-butyl-nitrone and Benzonidazole Treatment Controlled the Mitochondrial Oxidative Stress and Evolution of Cardiomyopathy in Chronic Chagasic Rats  

PubMed Central

Objectives Determine the pathological importance of oxidative stress-induced injurious processes in chagasic heart dysfunction. Background Trypanosoma cruzi-induced inflammatory pathology and a feedback cycle of mitochondrial dysfunction and oxidative stress may contribute to Chagas disease. Methods Sprague Dawley rats were infected with T. cruzi, and treated with phenyl-?-tert-butylnitrone (PBN/antioxidant) and/or benzonidazole (BZ/anti-parasite). We monitored myocardial parasite burden, oxidative adducts, mitochondrial complex activities, respiration and ATP synthesis rates, and inflammatory and cardiac remodeling responses during disease development. Cardiac hemodynamics was determined for all rats. Results BZ (not PBN) decreased the parasite persistence and immune adverse events (proinflammatory cytokine expression, NADPH (?-Nicotinamide Adenine Dinucleotide Phosphate, reduced) oxidase and myeloperoxidase activities, and inflammatory infiltrate) in chronic hearts. PBN±BZ (not BZ alone) decreased the mtROS level, oxidative adducts (malonyldialdehyde, 4-hydroxynonenal, carbonyls), hypertrophic gene expression (ANP, BNP, ?sk-Actin), and collagen deposition, and preserved the respiratory chain efficiency and energy status in chronic hearts. Subsequently, left ventricular dysfunction was prevented in PBN±BZ-treated chagasic rats. Conclusions BZ treatment after acute stage decreased the parasite persistence and inflammatory pathology. Yet, oxidative adducts, mitochondrial dysfunction and remodeling responses persisted and contributed to declining cardiac function in chagasic rats. Combinatorial treatment (PBN+BZ) was beneficial in arresting the T. cruzi-induced inflammatory and oxidative pathology and chronic heart failure in chagasic rats. PMID:20510218

Wen, Jian-Jun; Gupta, Shivali; Guan, Zhangjun; Dhiman, Monisha; Condon, David; Lui, Charles; Garg, Nisha Jain

2010-01-01

284

A re-evaluation of the taste and odour of methyl tertiary butyl ether (MTBE) in drinking water.  

PubMed

Methyl tertiary butyl ether (MTBE) is a gasoline additive that has been found in groundwater when an underground gasoline storage tank leaks. Although dependent on the clean-up standards that are applied, clean-up costs have been estimated in the US alone to be in the billions of dollars. MTBE is considered primarily a taste and odour concern and not a toxicity issue at concentrations found in drinking water. Thus, the clean-up of MTBE problems is controlled by the MTBE odour threshold concentration (OTC). The level of clean-up and associated differential of millions of dollars is a matter of concern for water purveyors and well owners. A 1993 study of nine OTC studies showed the OTC of MTBE in water to be between 0.04 and 0.06 microg/L, a level over two orders of magnitude less than eight other studies. This 1993 study was repeated at the original laboratory in 2004 and is reported in this paper. The laboratory's quality control programme and ability to repeat one of the eight other studies indicated the laboratory was qualified to repeat its original OTC study. The flavour and odour detection threshold range in the 1993 study, however, could not be confirmed by trained assessors repeating the original study in 2004. The inconsistencies in the data and the high detection on water blanks indicate that the dilution series of the test solutions for the 1993 study were mainly at subthreshold levels. Therefore, the original study of 1993 is not a valid OTC study for MTBE and should not be used to develop drinking water and clean-up standards. The OTC of MTBE is over 15 microg/L for the eight valid studies. PMID:17489419

Suffet, I H

2007-01-01

285

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

PubMed

We report ab initio density functional theory electronic structure calculations of rotational barriers for t-butyl groups and their constituent methyl groups both in the isolated molecules and in central molecules in clusters built from the X-ray structure in four t-butyl aromatic compounds. The X-ray structures have been reported previously. We also report and interpret the temperature dependence of the solid state (1)H nuclear magnetic resonance spin-lattice relaxation rate at 8.50, 22.5, and 53.0 MHz in one of the four compounds. Such experiments for the other three have been reported previously. We compare the computed barriers for methyl group and t-butyl group rotation in a central target molecule in the cluster with the activation energies determined from fitting the (1)H NMR spin-lattice relaxation data. We formulate a dynamical model for the superposition of t-butyl group rotation and the rotation of the t-butyl group's constituent methyl groups. The four compounds are 2,7-di-t-butylpyrene, 1,4-di-t-butylbenzene, 2,6-di-t-butylnaphthalene, and 3-t-butylchrysene. We comment on the unusual ground state orientation of the t-butyl groups in the crystal of the pyrene and we comment on the unusually high rotational barrier of these t-butyl groups. PMID:24852535

Wang, Xianlong; Mallory, Frank B; Mallory, Clelia W; Odhner, Hosanna R; Beckmann, Peter A

2014-05-21

286

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

NASA Astrophysics Data System (ADS)

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 1H 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 1H 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; Mallory, Frank B.; Mallory, Clelia W.; Odhner, Hosanna R.; Beckmann, Peter A.

2014-05-01

287

The influence of phosphotungstic acid acidity on Al-MCM-41 in t-butylation of phenol with t-butyl alcohol  

Microsoft Academic Search

Al-MCM-41 (Si\\/Al=20) molecular sieve was synthesized hydrothermally and phosphotungstic acid (PW) of 10, 20 and 40wt% was supported on it. Their catalytic performance was examined in the vapour phase alkylation of phenol with tert-butyl alcohol (TBA) in the temperature range 190–275°C. The major products were 2-tert-butyl phenol (2-TBP), 4-tert-butyl phenol (4-TBP), 2,4-di-tert-butyl phenol (2,4-DTBP) and small amounts of undesired products.

K. Usha Nandhini; J. Herbert Mabel; Banumathi Arabindoo; M. Palanichamy; V. Murugesan

2006-01-01

288

Aqueous extract of Terminalia arjuna attenuates tert-butyl hydroperoxide-induced oxidative stress in HepG2 cell model.  

PubMed

Arjuna (Terminalia arjuna) is a medicinal plant used in many polyherbal hepatoprotective formulations. Although widely claimed to be antioxidant, data supporting such actions of Arjuna are limited. In the present study, we have investigated the efficacy of the aqueous extract of T. arjuna (AETA) using a standard pro-oxidant [tertiary butyl hydroperoxide (TBHP)] in HepG2 cells. Cells were incubated with AETA (5-100 µg/ml) for a range of time points (4-24 h) with or without TBHP (500 ?M), and biochemical markers of oxidative stress (OS) were determined. Cells incubated with TBHP showed the significant induction of OS response in cytosol manifested as lipid hydroperoxide (76%-198%) and the generation of reactive oxygen species (60%-127%). Diminished levels of reduced glutathione (35%-60%) and total antioxidant capacity (20%-61%) suggested an altered redox state. Significant perturbations in the activities of antioxidant enzymes such as catalase (30%-56%), superoxide dismutase (25%-68%), glutathione S-transferase (29%-67%), glutathione peroxidase (24%-68%) and glutathione reductase (38%-49%) were discernible suggesting the ongoing OS in the cells. However, cells treated with AETA (100 µg/ml) along with TBHP offered significant protection by reducing levels of lipid hydroperoxide (33%-62%) and ROS (69%) and by increasing antioxidant capacity (54%-81%) and levels of reduced glutathione (49%-82%). Further, it also enhanced the activities of endogenous antioxidant enzymes (superoxide dismutase, 60%; catalase, 35%-82%; glutathione peroxidase, 42-65 %; glutathione reductase, 48%-62%; and glutathione S-transferase, 22%-100%). Taken together, these data suggest that Arjuna can protect against the oxidative damage induced by TBHP and may be effectively used as a hepatoprotective adjuvant to abrogate OS in vivo. PMID:22961563

Shivananjappa, Mahesh Mysore; Mhasavade, Deepak; Joshi, Manoj Kumar

2013-03-01

289

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

290

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

291

Metabolism of (+/-)-trans-7,8-dihydroxy-7,8-dihydro-benzo[a]pyrene in mouse liver microsomes and the effect of 2(3)-tert-butyl-4-hydroxy-anisole.  

PubMed

The metabolism of (+/-)-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (BP-7,8-diol) was examined using liver microsomes from mice maintained either on a standard laboratory food diet or on a mixture of ground food pellets and 2(3)-tert-butyl-4-hydroxyanisole (BHA, 7.5 g/kg food). Dietary BHA had a statistically significant inhibitory effect both on the formation of polar metabolites of BP-7,8-diol and on the covalent binding of reactive products to calf thymus DNA. When BHA (20 micro M) was added in vitro to the microsomal incubation system, both the metabolism of BP-7,8-diol and the covalent binding of BP-7,8-diol metabolites to DNA, was reduced by approximately 50% using either type of microsomes. The binding of [14C]7 beta, 8 alpha-dihydroxy-9 alpha, 10 alpha-epoxy-7,8,0,10-tetrahydrobenzo[a]pyrene to calf thymus DNA was not affected by the presence of BHA. The reduced metabolism of BP-7,8-diol in microsomes from BHA-treated mice compared to control was not due to the effect or residual BHA in the microsomal preparation. These results show that BHA acts as a potent inhibitor of the activation of the proximate carcinogen BP-7,8-diol to reactive, DNA-binding products both when administered as a dietary constituent and as an additive to microsomal incubation systems. Both of these properties may be of relevance to the inhibitory effect of BHA on benzo[a]pyrene carcinogenesis. PMID:6889472

Dock, L; Rahimtula, A; Jernström, B; Moldéus, P

1982-01-01

292

Ethers from ethanol. 2: Reaction equilibria of simultaneous tert-amyl ethyl ether synthesis and isoamylene isomerization  

SciTech Connect

The recent requirements for blending oxygenates with gasoline for pollution abatement and octane improvement have opened up huge markets for ethers, synthesized by catalytically reacting an isoolefin with an alcohol. Consequently, alternatives to isobutylene-derived methyl tert-butyl ether (MTBE) obtained from methanol and ethyl tert-butyl ether (ETBE) obtained from ethanol are being explored. This paper provides a thermodynamic analysis of the liquid phase etherification of ethanol with 2-methyl-1-butene (2M1B) and 2-methyl-2-butene (2M2B), the two reactive isoamylene isomers. Both these isomers produce tert-amyl ethyl ether (TAEE) but also undergo isomerization. Theoretical and experimental results are provided here for the simultaneous TAEE synthesis and isoamylene isomerization. Expressions for the three thermodynamic equilibrium constants as a function of temperature are developed. Gibbs free energy and the enthalpy of formation of TAEE are also obtained. The equilibrium constants` correlations are utilized to compute the effect of the feed mole ratio of the isoamylenes and the inert solvent to ethanol as well as the reaction temperature on the equilibrium conversions and selectivities. Conditions that maximize etherification conversion and selectivity are explored.

Kitchaiya, P.; Datta, R. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemical and Biochemical Engineering

1995-04-01

293

Investigating the Micro-Channel Flow Reactor Configuration on the Liquid Phase Synthesis of tert-amyl Methyl Ether Catalyzed by Sulfuric Acid  

NASA Astrophysics Data System (ADS)

This study aims to investigate the effect of reactants and catalyst flow rates; the effect of the catalyst concentration and the position inlet to the reactor location of the catalyst on the synthesis of tert-amyl methyl ether (TAME), have investigated. The results reveal that the micro channel reactor shows high selectivity for homogeneous syntheses of TAME compared to heterogeneous ones. The experimental results show that no other di-ether products were noticed in this study. The selected flow rates for the reactants and the catalyst give a stable flow pattern inside the reactor and no turbulent flow was noticed in any conducted runs. The mole fraction for methanol (MeOH) and tert-amyl alcohol (TAA) are 22 and 37% respectively, (this was considered the standard condition). Experimental results show that, keeping H2SO4 flows in the top lane of the reactor gives good mixing from the middle and bottom lanes. At the same time this will give the chance to the reactant to be pulled toward the middle lane to promote the reaction. Therefore, the middle lane can be considered as the core of the reaction zone phase, while the other lanes as separation zones. On the other hand, when H2SO4 introduced from the middle inlet the chance of reactants mixing from the top and bottom lanes will be less. It was also noticed that during the reaction and when the H2SO4 introduced at the top lane of the micro-channel, the catalyst distributes itself within the TAA lane and forms a micelle to react with MeOH in the bottom lane. When the flow rates of the reactants was reduced to half of its standard condition the yield was noticed to be higher. This may be attributed to the fact that lower flow rate, will lengthen the residence time inside the reactor and more reaction will develop.

Matouq, Mohammed; Al-Anber, Zaid; Tagawa, Tomohiko; Aljbour, Salah; Yamada, Hiroshi

294

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

295

Efficacy of disodium 4-[( tert-butylimino)methyl]benzene-1,3-disulfonate N-oxide (NXY-059), a free radical trapping agent, in a rat model of hemorrhagic stroke  

Microsoft Academic Search

Because free radical mechanisms may contribute to brain injury in hemorrhagic stroke, the effect of the free radical trapping agent disodium 4-[(tert-butylimino)methyl]benzene-1,3-disulfonate N-oxide (NXY-059) was investigated on outcome following intracerebral hemorrhage (ICH) in rat. ICH was induced in 20 adult rats by infusion of collagenase into the caudate-putamen. Thirty minutes later rats were treated with NXY-059 (50 mg\\/kg subcutaneous plus

James Peeling; Marc R Del Bigio; Dale Corbett; A. Richard Green; David M Jackson

2001-01-01

296

Impact of Ethanol on Benzene Plume Lengths: Microbial and Modeling Studies  

E-print Network

Air Act. Fuel oxygen- ates include methyl tert-butyl ether MTBE , ethyl tert-butyl ether ETBE , tert-amyl methyl ether TAME , dissopropyl ether DIPE , tert-butyl alcohol TBA , methanol, and ethanol. The addition

Alvarez, Pedro J.

297

Thermally Switchable Thin Films of an ABC Triblock Copolymer of Poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate)  

SciTech Connect

The thermo-responsive behavior of polymer films consisting of novel linear triblock copolymers of poly(n-butyl methacrylate)-poly(methyl methacrylate)-poly(2-fluoroethyl methacrylate) (PnBuMA-PMMA-P2FEMA) are reported using differential scanning calorimetry (DSC), atomic forcing microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contacting angle (CA) measurements. The surface morphology, wettability and chemical structure of thin films of these triblock copolymers on silicon wafers as a function of temperature have been investigated. It has been shown that the wettability of the films is thermally switchable. Detailed structural analysis shows that thermo-responsive surface composition changes are produced. The underlying mechanism of the thermoresponsive behavior is discussed.

Zhang, Shanju [Georgia Institute of Technology; Liu, Zhan [Georgia Institute of Technology; Bucknall, David G. [Georgia Institute of Technology; He, Lihong [ORNL; Hong, Kunlun [ORNL; Mays, Jimmy [ORNL; Allen, Mark [Georgia Institute of Technology

2011-01-01

298

Preparation of p-tert[(dimethylamino)methyl]-calix[4]arene functionalized aminopropylpolysiloxane resin for selective solid-phase extraction and preconcentration of metal ions.  

PubMed

A new p-tert-[(dimethylamino)methyl]-1,3-bisglyciyl-calix[4]arene functionalized aminopropylpolysiloxane resin (APPS-CA) has been prepared and investigated for selective solid-phase extraction (SPE) of trace Cr (III), Cu (II), Ni (II), Co (II) and Zn (II) prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The characterization of the surface modification was performed on the basis of FT-IR spectroscopy, elemental analysis and thermal gravimetric analysis. The separation/preconcentration conditions of analytes were investigated, including effect of pH, the shaking time, the sample flow rate and volume, the elution condition, the interfering ions and stability test. At pH 4.0, the maximum adsorption capacity of Cr (III), Cu (II), Ni (II), Co (II) and Zn (II) were 47.2, 34.3, 52.8, 29.8 and 36.4 mg g(-1), respectively. The adsorbed metal ions were quantitatively eluted by 2.0 mL of 0.5 mol L(-1) HCl. Common coexisting ions did not interfere with the separation. According to the definition of International Union of Pure and Applied Chemistry, the detection limits (3 sigma) of this method were found to be 0.58, 0.33, 0.47, 0.61 and 0.14 ng mL(-1) for Cr (III), Cu (II), Ni (II), Co (II) and Zn (II), respectively. The relative standard deviation under optimum conditions is less than 4.0%. The application of this new adsorbent to preconcentration trace Cr (III), Cu (II), Ni (II), Co (II) and Zn (II) of two water samples gave high accurate and precise results. PMID:19398269

Nie, Rong; Chang, Xijun; He, Qun; Hu, Zheng; Li, Zhenhua

2009-09-30

299

Four-center oxidation state combinations and near-infrared absorption in [Ru(pap)(Q)2]n (Q = 3,5-di-tert-butyl-N-aryl-1,2-benzoquinonemonoimine, pap = 2-phenylazopyridine).  

PubMed

The complex series [Ru(pap)(Q)2](n) ([1](n)-[4](n); n = +2, +1, 0, -1, -2) contains four redox non-innocent entities: one ruthenium ion, 2-phenylazopyridine (pap), and two o-iminoquinone moieties, Q = 3,5-di-tert-butyl-N-aryl-1,2-benzoquinonemonoimine (aryl = C6H5 (1(+)); m-(Cl)2C6H3 (2(+)); m-(OCH3)2C6H3 (3(+)); m-(tBu)2C6H3 (4(+))). A crystal structure determination of the representative compound, [1]ClO4, established the crystallization of the ctt-isomeric form, that is, cis and trans with respect to the mutual orientations of O and N donors of two Q ligands, and the coordinating azo N atom trans to the O donor of Q. The sensitive C-O (average: 1.299(3)?Å), C-N (average: 1.346(4)?Å) and intra-ring C-C (meta; average: 1.373(4)?Å) bond lengths of the coordinated iminoquinone moieties in corroboration with the N-N length (1.292(3)?Å) of pap in 1(+) establish [Ru(III)(pap(0))(Q(·-))2 ](+) as the most appropriate electronic structural form. The coupling of three spins from one low-spin ruthenium(III) (t2g(5)) and two Q(·-) radicals in 1(+)-4(+) gives a ground state with one unpaired electron on Q(·-), as evident from g = 1.995 radical-type EPR signals for 1(+)-4(+). Accordingly, the DFT-calculated Mulliken spin densities of 1(+) (1.152 for two Q, Ru: -0.179, pap: 0.031) confirm Q-based spin. Complex ions 1(+)-4(+) exhibit two near-IR absorption bands at about ? = 2000 and 920?nm in addition to intense multiple transitions covering the visible to UV regions; compounds [1]ClO4-[4]ClO4 undergo one oxidation and three separate reduction processes within ±2.0?V versus SCE. The crystal structure of the neutral (one-electron reduced) state (2) was determined to show metal-based reduction and an EPR signal at g = 1.996. The electronic transitions of the complexes 1(n)-4(n) (n = +2, +1, 0, -1, -2) in the UV, visible, and NIR regions, as determined by using spectroelectrochemistry, have been analyzed by TD-DFT calculations and reveal significant low-energy absorbance (?max >1000?nm) for cations, anions, and neutral forms. The experimental studies in combination with DFT calculations suggest the dominant valence configurations of 1(n)-4(n) in the accessible redox states to be [Ru(III)(pap(0))(Q(·-))(Q(0))](2+) (1(2+)-4(2+))?[Ru(III)(pap(0))(Q(·-))2](+) (1(+)-4(+))?[Ru(II)(pap(0))(Q(·-))2] (1-4)?[Ru(II)(pap(·-))(Q(·-))2](-) (1(-)-4(-))?[Ru(III)(pap(·-))(Q(2-))2](2-) (1(2-)-4(2-)). PMID:23576220

Das, Dipanwita; Agarwala, Hemlata; Chowdhury, Abhishek Dutta; Patra, Tuhin; Mobin, Shaikh M; Sarkar, Biprajit; Kaim, Wolfgang; Lahiri, Goutam Kumar

2013-06-01

300

3-tert-Butyl 5-methyl (2R,4S,5R)-2-(4-methoxyphenyl)-4-(3-nitrophenyl)-1,3-oxazolidine-3,5-dicarboxylate  

PubMed Central

The title mol­ecule, C23H26N2O8, was synthesized in three steps starting from m-nitro­cinnamic acid. The central oxazolidine ring adopts an almost perfect envelope conformation with the O atom as the flap [puckering parameter ? = 0.3?(6)°]. The dihedral angle formed by the benzene rings is 61.81?(9)°. In the crystal, mol­ecules are connected into double chains parallel to [010] by C—H?O hydrogen bonds. The absolute configuration was assigned from the synthetic procedure. PMID:23284466

Montiel-Smith, Sara; Bernes, Sylvain; Sandoval-Ramirez, Jesus; Meza-Reyes, Socorro; Dubois, Joelle

2012-01-01

301

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...

302

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...

303

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

E-print Network

as a result of the enactment of the Clean Air Act (CAA) Amendments of 1990. The CAA Amendments mandate in the United States as an octane enhancer and oxygenate in gasoline. Octane enhancement began in the late 1970 that oxygen must be added to gasoline in areas that do not meet National Ambient Air Quality Standards (NAAQS

304

Methyl tert-butyl ether (MTBE) is a volatile organic com-pound (VOC) derived from natural gas that is added to gas-  

E-print Network

ranked second among all organic chemicals manufactured in the United States. Currently, the U.S; Missoula, Montana; Milwaukee, Wisconsin; and New Jersey. As part of the U.S. Geological Survey's National decreases the need for foreign oil. Why is MTBE of interest? About 109 million Americans live in counties

305

Thermodynamic and transport properties of binary mixtures of dimethyl sulfoxide with t -butyl alcohol, butyl acetate, 2-butanone and butyl amine at different temperatures  

Microsoft Academic Search

Densities and viscosities of binary mixtures of dimethyl sulfoxide (DMSO) with tert-butyl alcohol, butyl acetate, butanone, and butyl amine were determined over the entire range of mole fractions at temperatures\\u000a of 298.15, 308.15, and 318.15 K. At each temperature, the excess molar volume (V\\u000a \\u000a E\\u000a ), viscosity deviations (??), and Gibbs excess free energy of activation for viscous flow (?G

M. N. Roy; M. Das

2006-01-01

306

New reactions of N-tert-butylimines; formation of N-heterocycles by methyl radical elimination on flash vacuum thermolysis of N-benzylidene- and N-(2-pyridylmethylidene)-tert-butylamines.  

PubMed

Thermal reactions of N-benzylidene- and N-(2-pyridylmethylidene)-tert-butylamines (5 and 13) under FVT conditions have been investigated. Unexpectedly, at 800?°C, compound 5 yields 1,2-dimethylindole and 3-methylisoquinoline. In the reaction of 13 at 800?°C, 3-methylimidazo[1,5-a]pyridine was obtained as the major product. Mechanisms of these reactions have been proposed on the basis of DFT calculations. Furthermore, UV-photoelectron spectroscopy combined with FVT has been applied for direct monitoring and characterization of the thermolysis products in situ. PMID:24108670

Vu, Thien Y; Chrostowska, Anna; Huynh, Thi Kieu Xuan; Khayar, Saïd; Dargelos, Alain; Justyna, Katarzyna; Pasternak, Beata; Le?niak, Stanis?aw; Wentrup, Curt

2013-10-25

307

Cell death induced by the phenolic antioxidant tert-butylhydroquinone and its metabolite tert-butylquinone in human monocytic leukemia U937 cells  

Microsoft Academic Search

2-tert-Butyl-4-hydroquinone (TBHQ), a phenolic antioxidant used as a food additive, and its metabolite 2-tert-butyl-1,4-benzoquinone (TBQ) were both cytotoxic in human monocytic leukemia U937 cells, TBQ being the more strongly cytotoxic. Both compounds induced caspase activity towards DEVD-MCA as a substrate and the cleavage of poly(ADP-ribose) polymerase in cells. Enzyme activities of caspase-3,-7,-6 and -9 seemed to be induced, and procaspases-3

T Okubo; Y Yokoyama; K Kano; I Kano

2003-01-01

308

Pattern of neurotoxicity of n?hexane, methyl n?butyl ketone, 2,5?hexanediol, and 2,5?hexanedione alone and in combination with O?ethyl O?4?nitrophenyl phenylphosphonothioate in hens  

Microsoft Academic Search

This investigation was designed to study the neurotoxicity produced in hens by the aliphatic hexacarbons n?hexane, methyl n?butyl ketone (MnBK), 2,5?hexanediol (2,5?HDOH), and 2,5?hexanedione (2,5?HD) following daily dermal application of each chemical alone and in combination with O?ethyl O?4?nitrophenyl phenylphosphonothioote (EPN). Dermal application was carried out on the unprotected back of the neck. To assess whether the joint neurotoxic action

H. M. Makkawy; Gerald M. Campbell

1985-01-01

309

Poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers: preparation and aqueous solution properties.  

PubMed

A series of water-soluble, amphiphilic graft copolymers has been prepared by free-radical copolymerization of methoxypoly(ethylene glycol) macromonomers, with either methyl methacrylate or butyl methacrylate as the comonomers, in water/ethanol solvent mixtures. Lower molecular weight copolymers were obtained by increasing the concentration of the initiator, azobisisobutyronitrile (AIBN), used in the polymerization reaction. However, the route used also led to the formation of significant quantities of tetramethylsuccinodinitrile, a toxic byproduct resulting from the cage reaction of AIBN. Static fluorescence measurements using pyrene as a probe, along with 1H NMR experiments, showed that the graft copolymers form aggregates in water at very low concentrations (approximately 0.01 g l(-1)) with the pendant hydrophilic graft chains forming a stabilizing shell around the hydrophobic backbone. An increase in the hydrophile-lipophile balance of the graft copolymers was found to lead to smaller aggregates with lower aggregation numbers and highly swollen hydrophilic shells, as revealed by small angle neutron scattering (SANS). PMID:16256637

Horgan, Adrian; Saunders, Brian; Vincent, Brian; Heenan, Richard K

2003-06-15

310

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

311

Reversal in enantioselectivity of tert-butyl versus phenyl-substituted bis(oxazoline) copper(II) catalyzed hetero Diels-Alder and ene reactions. Crystallographic and mechanistic studies  

Microsoft Academic Search

X-Ray crystal structures of the Cu[(S,S)-tert-Bu-bis(oxazoline)](H2O)2(SbF6)2 (6), Cu[(S,S)-Ph-bis(oxazoline)](H2O)2(SbF6)2 (7), and Cu[(S,S)-iso-Pr-bis(oxazoline)](H2O)2(SbF6)2 (8) complexes are presented. Implications of the structural details are considered in the context of the opposite enantiofacial biases conferred by complexes Cu[(S,S)-tert-Bu-bis(oxazoline)](X)2 (1, X = OTf or SbF6) and Cu[(S,S)-Ph-bis(oxazoline)](X)2 (2) in hetero Diels-Alder and glyoxylate ene reactions. Structural and mechanistic studies suggest that a change in geometry

David A. Evans; Jeffrey S. Johnson; Christopher S. Burgey; Kevin R. Campos

1999-01-01

312

(?)-(4aR,5R,8S,8aR)-8-(tert-Butyl-dimethyl-sil-yloxy)-2,5,8a-trimethyl-4a,5,8,8a-tetra-hydro-naphthalene-1,4-dione  

PubMed Central

In the title compound, C19H30O3Si, both rings adopt a half-boat conformation. Overall, the mol­ecule approximates a U-shape as the cyclo-2-ene-1,4-dione and butyl­dimethyl­sil­yloxy substituents lie to the same side of the central cyclo­hexene ring; the methyl substituent lies to the other side of the mol­ecule. In the crystal, linear supra­molecular chains along the b axis are sustained by C—H?O inter­actions. PMID:23476523

Delling, Felix N.; Zukerman-Schpector, Julio; Brocksom, Timothy J.; Brocksom, Ursula; Finelli, Fernanda G.; Tiekink, Edward R. T.

2013-01-01

313

Synthesis, antimalarial activity, and preclinical pharmacology of a novel series of 4'-fluoro and 4'-chloro analogues of amodiaquine. Identification of a suitable "back-up" compound for N-tert-butyl isoquine.  

PubMed

On the basis of a mechanistic understanding of the toxicity of the 4-aminoquinoline amodiaquine (1b), three series of amodiaquine analogues have been prepared where the 4-aminophenol "metabolic alert" has been modified by replacement of the 4'-hydroxy group with a hydrogen, fluorine, or chlorine atom. Following antimalarial assessment and studies on mechanism of action, two candidates were selected for detailed ADME studies and in vitro and in vivo toxicological assessment. 4'-Fluoro-N-tert-butylamodiaquine (2k) was subsequently identified as a candidate for further development studies based on potent activity versus chloroquine-sensitive and resistant parasites, moderate to excellent oral bioavailability, low toxicity in in vitro studies, and an acceptable safety profile. PMID:19284751

O'Neill, Paul M; Shone, Alison E; Stanford, Deborah; Nixon, Gemma; Asadollahy, Eghbaleh; Park, B Kevin; Maggs, James L; Roberts, Phil; Stocks, Paul A; Biagini, Giancarlo; Bray, Patrick G; Davies, Jill; Berry, Neil; Hall, Charlotte; Rimmer, Karen; Winstanley, Peter A; Hindley, Stephen; Bambal, Ramesh B; Davis, Charles B; Bates, Martin; Gresham, Stephanie L; Brigandi, Richard A; Gomez-de-Las-Heras, Federico M; Gargallo, Domingo V; Parapini, Silvia; Vivas, Livia; Lander, Hollie; Taramelli, Donatella; Ward, Stephen A

2009-04-01

314

Solubility of CO2 in 1-butyl-3-methyl-imidazolium-trifluoro acetate ionic liquid studied by Raman spectroscopy and DFT investigations.  

PubMed

The polarized and depolarized Raman spectra of 1-butyl-3-methyl-imidazolium-trifluoro acetate (Bmim TFA) ionic liquid and of the dense phase obtained after introduction of supercritical carbon dioxide (313K) under pressure (from 0.1 MPa up to 9 MPa) in the ionic liquid have been recorded. The spectrum of the pure ionic liquid has been assigned by comparison with the spectra of ionic liquids sharing the same cation and using literature data concerning the vibrational modes of the TFA anion. It was found that the spectra of the ionic liquid is almost unaffected by the CO(2) dilution. The only noticeable perturbation concerns a weak enhancement of the mode assigned here to the symmetric stretch vibration of the COO group of the TFA anion. The band shape analysis of the ?(CC) band in pure Bmim TFA shows that the carboxylate groups probe a variety of environments which are almost not affected by the dilution in carbon dioxide. The analysis of the Fermi dyad of carbon dioxide shows that this molecule is perturbed upon dilution in the ionic liquid. The spectra suggest the presence of carbon dioxide in two different environments. In the first one, carbon dioxide molecules interact with themselves, whereas in the second environment, this molecule interacts with the COO group of the TFA anion. This is supported by B3LYP-DFT calculations aimed at assessing the interaction between an ion pair dimer and a carbon dioxide molecule. It is shown that dissolved CO(2) molecules preferentially interact with the TFA anion through a weak charge transfer interaction taking place between the carbon atom of CO(2) (acting as a Lewis acid) and a oxygen atom of the COO group of TFA (as a Lewis base). The results show that Bmim TFA is able to accommodate a large amount of carbon dioxide without having its short-range local structure significantly perturbed. Most CO(2) is hosted in the voids existing among the ion pairs, while some also weakly interact with the anion. It is finally argued that the evolution of the local organization of the IL upon carbon dioxide dilution presents similarities with the microsegregation phenomena reported for IL upon increasing the alkyl chains lengths. PMID:21410211

Cabaço, M Isabel; Besnard, M; Danten, Y; Coutinho, J A P

2011-04-01

315

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

... 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...

2014-07-01

316

(4,4?,6,6?-Tetra-tert-butyl-2,2?-{[2-(di-methyl-amino)-ethyl]-nitrilo-bis-(methyl-ene)}diphenolato)dioxidomolyb-denum(VI) chloro-form monosolvate  

PubMed Central

In the title compound, [Mo(C34H54N2O2)O2]·CHCl3, the molybdenum(VI) ion exhibits a cis-dioxide distorted octa­hedral geometry. Two anionic phenolate O-atom donors and two neutral N-atom donors of the ligand are trans and cis, respectively. The Mo=O bond lengths and the O=Mo=O bond angle are typical for six-coordinated dioxomolyb­denum(VI) complexes. The Mo—N bond lengths are longer than 2.30?Å, as expected for a trans O=Mo—N structure. PMID:22219760

Lei, Xiangyang; Chelamalla, Nagasree

2011-01-01

317

Depigmentation with t ert Butyl Hydroquinone using Black Guinea Pigs  

Microsoft Academic Search

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)

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

1999-01-01

318

Analysis of the antioxidant butylated hydroxytoluene (BHT) in water by means of solid phase extraction combined with GC\\/MS  

Microsoft Academic Search

The antioxidant 3,5-di-tert-butyl-4-hydroxy-toluene (BHT) is widely used as an additive to increase the tenability of food and plastics. BHT is degraded to 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) in mammals, as well as in the natural environment such as in water and soils. BHT-CHO has been studied extensively in terms of their potential toxicities. The present investigation was carried out to quantify BHT and

Elke Fries; Wilhelm Püttmann

2002-01-01

319

Contribution of oxygen radicals to DNA cleavage by quinone compounds derived from phenolic antioxidants, tert-butylhydroquinone and 2,5-di-tert-butylhydroquinone  

Microsoft Academic Search

The effects of synthetic phenolic antioxidants, tert-butylhydroquinone (TBHQ), 2,5-di-tert-butylhydroquinone (DTBHQ) and 3-tert-butyl-4-hydroxyanisole (BHA), on DNA cleavage were examined with supercoiled plasmid DNA, pUC18, in vitro. Extensive single and double strand breaks of DNA by TBHQ were observed and almost all the DNA was converted to the linear form at 10?2 M. The cleavage was stimulated by both CuCl2 and FeCl2,

Tomoko Okubo; Fumiko Nagai; Keiko Ushiyama; Itsu Kano

1997-01-01

320

N-(tert-butoxycarbonyl)-O-allyl-L-seryl-?-aminoisobutyryl-L-valine methyl ester: a protected tripeptide with an allylated serine residue.  

PubMed

The title compound [systematic name (6S,12S)-methyl 6-(allyloxymethyl)-12-isopropyl-2,2,9,9-tetramethyl-4,7,10-trioxo-3-oxa-5,8,11-triazatridecan-13-oate], C(21)H(37)N(3)O(7), containing the little studied O-allyl-L-serine residue [Ser(All)], crystallizes in the monoclinic space group C2 with one molecule in the asymmetric unit. The compound is an analogue of the Ser140-Val142 segment of the water channel aquaporin-4 (AQP4). It forms a distorted type-II ?-turn with a P(II)-3(10L)-P(II) backbone conformation (P(II) is polyproline II). The overall backbone conformation is markedly different from that of the CO(Pro139)-Val142 stretch of rat AQP4, but is quite similar to the corresponding segment of human AQP4, despite significant differences at the level of the individual residues. The side chain of the Ser(All) residue adopts a gauche conformation relative to the backbone CO-C(?) and C(?)-N bonds. The H atoms of the two CH(2) groups in the Ser(All) side chain are almost eclipsed. The crystal packing of the title compound is divided into one-molecule-thick layers, each layer having a hydrophilic core and distinct hydrophobic interfaces on either side. PMID:21881187

Gebreslasie, Hadgu Girmay; Jacobsen, Øyvind; Görbitz, Carl Henrik

2011-09-01

321

Formation of poly(methyl methacrylate) thin films onto wool fiber surfaces by vapor deposition polymerization.  

PubMed

Chemical vapor deposition (CVD) polymerization is a useful technique because of the possibility of forming very thin film of pure polymers on substrates with any geometric shape. In this work, thin films of poly(methyl methacrylate) or PMMA were formed on the surfaces of wool fabrics by a CVD polymerization process. Various polymerization initiators including dicumyl peroxide, tert-butyl peroxide, and potassium peroxydisulfate have been investigated to polymerize methyl methacrylate onto the surfaces of wool by the CVD polymerization. The wool fabrics were impregnated with initiators and were then exposed to MMA monomer vapor under vacuum at the boiling temperature of the monomer. Wool fabrics with vapor-deposited PMMA surfaces were characterized by elemental analysis, TGA, FTIR, disperse dye absorption, contact angles measurement, AFM, and SEM. PMMA-coated wool fabrics showed higher contact angle and absorbed more dyes than that of the control wool. It was evident from the results obtained by various characterization techniques that MMA was successfully polymerized and formed thin films on the surfaces of wool fabrics by all initiators investigated but the best results were achieved with tert-butyl peroxide. PMID:23406279

Hassan, M Mahbubul; McLaughlin, J Robert

2013-03-13

322

Ethers from ethanol. 3: Equilibrium conversion and selectivity limitations in the liquid-phase synthesis of two tert-hexyl ethyl ethers  

SciTech Connect

Alternatives to the conventional isobutylene-derived ethers, namely methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE), are being explored, e.g., those produced from a combination of the branched C{sub 5} and C{sub 6} olefins with methanol or biomass-based ethanol. The conversion and selectivity of these ethers are thermodynamically limited. This paper, thus, describes the determination and analysis of the equilibrium limitations in the liquid-phase synthesis of two of the three possible isomers of tert-hexyl ethyl ether (THEE) from reactive C{sub 6} olefins and ethanol in the temperature range 298--353 K. The coupled reaction network for either of these two ethers involves two simultaneous esterification and one isomerization reactions, all being reversible. The equilibrium constants for these reactions, experimentally determined from equilibrium composition and the corresponding activity coefficients estimated by the UNIFAC method, decrease in the following order of tertiary olefins: 2M1P > isobutylene < 2,3DM1B {approx} 2M1B > 2M2P > 2M2B > 2,3DM2B for etherification reactions with ethanol, and (2,3DM1B {r_reversible} 2,3DM2B) > (2M1B {r_reversible} 2M2B) > (2M1P {r_reversible} 2M2P) for the isomerization reactions. This is explained on the basis of the relative stability of these olefins. The developed correlations are used to study the influence of process variables on the equilibrium conversion and selectivity of THEE formation.

Zhang, T.; Datta, R. [Univ. of Iowa, Iowa City, IA (United States). Dept. of Chemical and Biochemical Engineering

1995-07-01

323

5-Lipoxygenase-activating protein inhibitors. Part 3: 3-{3- tert-Butylsulfanyl-1-[4-(5-methoxy-pyrimidin-2-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1 H-indol-2-yl]-2,2-dimethyl-propionic acid (AM643)—A potent FLAP inhibitor suitable for topical administration  

Microsoft Academic Search

AM643 (compound 6, 3-{3-tert-butylsulfanyl-1-[4-(5-methoxy-pyrimidin-2-yl)-benzyl]-5-(5-methyl-pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid) was identified as a potential candidate for formulation as a topical agent for the treatment of skin disorders involving leukotriene production. Dermal application of 6 using a prototypical vehicle in a murine ear arachidonic acid model showed significant reduction in the concentrations of leukotrienes in mouse skin with concomitant reduction in ear swelling.

Nicholas Stock; Christopher Baccei; Gretchen Bain; Charles Chapman; Lucia Correa; Janice Darlington; Christopher King; Catherine Lee; Daniel S. Lorrain; Pat Prodanovich; Angelina Santini; Kevin Schaab; Jilly F. Evans; John H. Hutchinson; Peppi Prasit

2010-01-01

324

Dynamic mechanical properties of chlorinated butyl rubber blends  

Microsoft Academic Search

The binary blends are prepared by chlorinated butyl rubber (CIIR) and 3,9-bis[1,1-dimethyl-2{?-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2, 4, 8,10-tetraoxaspiro[5,5]-undecane (AO-80), which are investigated by dynamic mechanical analysis and thermal analysis. It is shown that CIIR\\/AO-80 blends clearly exhibit two kinds of relaxations, which are attributed to the relaxation of CIIR-rich matrix and AO-80-rich domains, respectively, and attenuated total reflection (ATR)-FTIR spectrum indicates that the existence

Cong Li; Shi-Ai Xu; Fang-Yi Xiao; Chi-Fei Wu

2006-01-01

325

Butylated hydroxyanisole and lung tumor development in A/J mice  

SciTech Connect

A diet containing 0.75% butylated hydroxyanisole (BHA) did not enhance the development of lung tumors in A/J mice if fed for 8 weeks after administration of urethane, benzo(a)pyrene (B(a)P), or dimethylnitrosamine (DMN). Prefeeding animals with BHA partially protected animals against the tumorigenic effect of urethane and B(a)P. Partial protection was also seen in animals given B(a)P and then exposed to BHA in the diet. The two isomers of BHA 3-tert.-butyl-4-hydroxyanisole and 2-tert.-butyl-4-hydroxyanisole) were synthesized and injected ip. They failed to enhance lung tumor development. It is concluded that BHA is not a promoting agent as is butylated hydroxytoluene (BHT) for lung tumors in mice. One possible explanation is that BHA in the diet does not produce the extensive cell proliferation seen in the lungs of mice fed BHT. 19 references, 5 tables.

Witschi, H.R.; Doherty, D.G.

1984-01-01

326

Methyl, ethyl, propyl, butyl: futile but not for water, as the correlation of structure and thermodynamic signature shows in a congeneric series of thermolysin inhibitors.  

PubMed

Water is ubiquitously present in any biological system and has therefore to be regarded as an additional binding partner in the protein-ligand binding process. Upon complex formation, a new solvent-exposed surface is generated and water molecules from the first solvation layer will arrange around this newly formed surface. So far, the influence of such water arrangements on the ligand binding properties is unknown. In this study, the binding modes of nine congeneric phosphonamidate-type inhibitors with systematically varied, size-increasing hydrophobic P2 ' substituents (from methyl to phenylethyl) addressing the hydrophobic, solvent-exposed S2 ' pocket of thermolysin were analyzed by high-resolution crystal structures and correlated with their thermodynamic binding profiles as measured by isothermal titration calorimetry. Overall, ??G spreads over 7.0 kJ mol(-1) , ??H varies by 15.8 kJ mol(-1) , and -T??S by 12.1 kJ mol(-1) . Throughout the series, these changes correlate remarkably well with the geometric differences of water molecules arranged adjacent to the P2 ' substituents. Ligands with medium-sized P2 ' substituents exhibit highest affinities, presumably because of their optimal solvation patterns around these complexes. The addition, removal, or rearrangement of even a single methyl group can result in a strong modulation of the adjacent water network pattern shifting from enthalpy to entropy-driven binding. In conclusion, the quality of a water network assembled around a protein-ligand complex influences the enthalpy/entropy signature and can even modulate affinity to a surprising extent. PMID:24623396

Krimmer, Stefan G; Betz, Michael; Heine, Andreas; Klebe, Gerhard

2014-04-01

327

Crystal structure of (2,4-di-tert-butyl-6-{[(6,6?-dimethyl-2?-oxido-1,1?-biphenyl-2-yl)imino]methyl}phenolato-?3 O,N,O?)bis(propan-2-olato-?O)titanium(IV)  

PubMed Central

In the mononuclear TiIV title complex, [Ti(C29H33NO2)(C3H6O)2], the TiNO4 coordination polyhedron comprises an N-atom and two O-atom donors from the dianionic Schiff base ligand and two O-atom donors from monodentate isopropoxide anions. The stereochemistry is distorted trigonal–bipyramidal with the N-donor in an elongated axial site [Ti—N = 2.2540?(17)?Å], the O-donors having normal Ti—O bond lengths [1.7937?(14)?Å (axial)–1.8690?(14)?Å]. In the crystal, C—H?? inter­actions link mol­ecules into centrosymmetric dimers. PMID:25309186

Chen, Liang; Wang, Huiran; Deng, Xuebin

2014-01-01

328

Biotreatment of groundwater contaminated with MTBE: interaction of common environmental co-contaminants  

E-print Network

, a laboratory-scale biotrickling filter for groundwater treatment inoculated with a microbial consortium filter. Tert-butyl alcohol (TBA), a frequent co-contaminant of MTBE had no inhibitory effect on MTBE tert-butyl ether; TBA ­ tert-butyl alcohol Introduction Methyl tert-butyl ether (MTBE) and its biodeg

329

Pattern of neurotoxicity of n-hexane, methyl n-butyl ketone, 2,5-hexanediol, and 2,5-hexanedione alone and in combination with O-ethyl O-4-nitrophenyl phenylphosphonothioate in hens  

SciTech Connect

This investigation was designed to study the neurotoxicity produced in hens by the aliphatic hexacarbons n-hexane, methyl n-butyl ketone (MnBK), 2,5-hexanediol (2,5-HDOH), and 2,5-hexanedione (2,5-HD) following daily dermal application of each chemical alone and in combination with O-ethyl O-4-nitrophenyl phenylphosphonothioate (EPN). Dermal application was carried out on the unprotected back of the neck. To assess whether the joint neurotoxic action of various chemicals is caused by the enhancement of absorption through the skin or by interaction at the molecular level, two additional experiments were performed. Dermal application was carried out for 90 d followed by a 30-d observation period. The results show that (1) hens treated with EPN developed severe ataxia followed by improvement during the observation period; (2) n-hexane produced leg weakness with subsequent recovery, whereas the same dose of MnBK, 2,5-HDOH, or 2,5-HD produced clinical signs of neurotoxicity characterized by gross ataxia; (3) concurrent dermal application of EPN with n-hexane of 2,5-HDOH at the same site or at different sites produced an additive neurotoxic action; (4) simultaneous dermal application of EPN and MnBK at different sites resulted in an additive effect, whereas it caused potentiation when applied at the same site; and (5) concurrent topical application of EPN and 2,5-HD produced a potentiating neurotoxic effect. While no histopathologic lesion was produced at the end of the observation period when any test chemical was applied alone, binary treatments of EPN and aliphatic hexacarbons resulted in histopathologic changes in some hens, with morphology and distribution characteristic of EPN neurotoxicity. The mechanism of this joint action seems to be related both to enhancing skin absorption of EPN and/or to its metabolic activation by n-hexane and its related chemicals.

Abou-Donia, M.B.; Makkawy, H.M.; Campbell, G.M.

1985-01-01

330

Depletion of sirtuin 1 (SIRT1) leads to epigenetic modifications of telomerase (TERT) gene in hepatocellular carcinoma cells.  

PubMed

Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase that is implicated in plethora of biological processes, including metabolism, aging, stress response, and tumorigenesis. Telomerase (TERT) is essential for telomere maintenance. Activation of TERT is considered a crucial step in tumorigenesis, and therefore it is a potential therapeutic target against cancer. We have recently found that SIRT1 expression is highly elevated in hepatocellular carcinoma, and the depletion of SIRT1 leads to substantial reduction in TERT mRNA and protein expression. However, the underlying molecular mechanism of SIRT1-dependent TERT expression remains uncharacterized. Here, we elucidated if SIRT1 regulates TERT expression via transcriptional, epigenetic and post-transcriptional mechanisms. We report that depletion of SIRT1 does not lead to significant change in transcriptional activity and CpG methylation patterns of the TERT promoter, nor does it affect mRNA stability or 3'-UTR regulation of TERT. Intriguingly, depletion of SIRT1 is associated with substantial induction of acetylated histone H3-K9 and reduction of trimethyl H3-K9 at the TERT gene, which are known to be associated with gene activation. Our data revealed that SIRT1 regulates histone acetylation and methylation at the TERT promoter. We postulated that SIRT1 may regulate TERT expression via long-range interaction, or via yet unidentified histone modifications. PMID:24416313

Zhang, Bin; Chen, Juan; Cheng, Alfred S L; Ko, Ben C B

2014-01-01

331

Tert -butylhydroquinone induces mitochondrial oxidative stress causing Nrf2 activation  

Microsoft Academic Search

Tert-butylhydroquinone (tBHQ), the major metabolite of butylated hydroxyanisole, induces an antioxidant response through the redox-sensitive\\u000a transcription factor, nuclear factor-E2-related factor-2 (Nrf2). However, the mechanism by which tBHQ induces Nrf2 activity\\u000a is not entirely understood. Here, we show that tBHQ preferentially alters the redox status in the mitochondrial compartment\\u000a in HeLa cells. HeLa cells treated with tBHQ showed a preferential oxidation

Barry R. Imhoff; Jason M. Hansen

2010-01-01

332

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

333

Expression level of hTERT is regulated by somatic mutation and common single nucleotide polymorphism at promoter region in glioblastoma  

PubMed Central

We investigated the role of somatic mutations and a common single nucleotide polymorphism (SNP) in the hTERT promoter region on hTERT expression and clinical outcomes. The hTERT promoter region was sequenced from 48 glioblastomas. hTERT expression was analyzed by quantitative real time-PCR. The association between hTERT promoter genetic changes and other genomic events and clinical variables common in gliomas were examined. C228T and C250T somatic mutations were found in 60.4% of glioblastomas, and a common SNP (T349C) was found in 66.6%. Somatic mutations and the SNP likely have opposing effects on hTERT expression. hTERT expression was significantly higher in the C228T or C250T mutated tumors. Tumors with the T349C genotype showed lower hTERT expression when C228T or C250T mutations were present. However, no significant survival differences were observed among the groups with or without hTERT promoter mutations and SNP. There was a significant association between genetic changes in the hTERT promoter and patient age as well as MGMT promoter methylation and EGFR amplification. hTERT expression is modulated by somatic mutations in the hTERT promoter as well as a common polymorphism. However, hTERT related genomic changes have limited value as an independent prognostic factor for clinical outcomes in glioblastomas. PMID:24930669

Park, Chul-Kee; Lee, Se-Hoon; Kim, Ji Young; Kim, Ja Eun; Kim, Tae Min; Lee, Soon-Tae; Choi, Seung Hong; Park, Sung-Hye; Kim, Il Han

2014-01-01

334

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

335

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

336

27 CFR 20.113 - Proprietary solvents general-use formula.  

Code of Federal Regulations, 2011 CFR

...combination of the following: ethyl acetate (equivalent to 85% ester content...21.106 of this chapter), methyl isobutyl ketone, methyl n -butyl ketone, tert -butyl...contains more than 4% by weight of methyl alcohol, the label shall...

2011-04-01

337

Comparison of stabilization by Vitamin E and 2,6-di-tert-butylphenols during polyethylene radio-thermal-oxidation  

NASA Astrophysics Data System (ADS)

This paper reports a compilation of data for PE+Vitamin E and 2,6-di-tert-butylphenols oxidation in radio-thermal ageing. Data unambiguously show that Vitamin E reacts with Prad and POOrad whereas 2,6-di-tert-butyl phenols only react with POOrad . Kinetic parameters of the stabilization reactions for both kinds of antioxidants were tentatively extracted from phenol depletion curves, and discussed regarding the structure of the stabilizer. They were also used for completing an existing kinetic model used for predicting the stabilization by antioxidants. This one permits to compare the efficiency of stabilizer with dose rate or sample thickness.

Richaud, Emmanuel

2014-10-01

338

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

339

Resolution of 1-n-butyl-3-methyl-3-phospholene 1-oxide with TADDOL derivatives and calcium salts of O,O'-Dibenzoyl-(2R,3R)- or O,O'-di-p-toluoyl-(2R,3R)-tartaric acid.  

PubMed

The resolution methods applying (-)-(4R,5R)-4,5-bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane ("TADDOL"), (-)-(2R,3R)-?,?,?',?'-tetraphenyl-1,4-dioxaspiro[4.5]decan-2,3-dimethanol ("spiro-TADDOL"), as well as the acidic and neutral Ca(2+) salts of (-)-O,O'-dibenzoyl- and (-)-O,O'-di-p-toluoyl-(2R,3R)-tartaric acid were extended for the preparation of 1-n-butyl-3-methyl-3-phospholene 1-oxide in optically active form. In one case, the intermediate diastereomeric complex could be identified by single-crystal X-ray analysis. The absolute P-configuration of the enantiomers of the phospholene oxide was also determined by comparing the experimentally obtained and calculated CD spectra. PMID:24510520

Bagi, Péter; Fekete, András; Kállay, Mihály; Hessz, Dóra; Kubinyi, Miklós; Holczbauer, Tamás; Czugler, Mátyás; Fogassy, Elemér; Keglevich, György

2014-03-01

340

Synthesis and biological evaluation of metabolites of 2-n-butyl-9-methyl-8-[1,2,3]triazol-2-yl-9H-purin-6-ylamine (ST1535), a potent antagonist of the A2A adenosine receptor for the treatment of Parkinson's disease.  

PubMed

The synthesis and preliminary in vitro evaluation of five metabolites of the A2A antagonist ST1535 (1) are reported. The metabolites, originating in vivo from enzymatic oxidation of the 2-butyl group of the parent compound, were synthesized from 6-chloro-2-iodo-9-methyl-9H-purine (2) by selective C-C bond formation via halogen/magnesium exchange reaction and/or palladium-catalyzed reactions. The metabolites behaved in vitro as antagonist ligands of cloned human A2A receptor with affinities (Ki 7.5-53 nM) comparable to that of compound 1 (Ki 10.7 nM), thus showing that the long duration of action of 1 could be in part due to its metabolites. General behavior after oral administration in mice was also analyzed. PMID:23789814

Piersanti, Giovanni; Bartoccini, Francesca; Lucarini, Simone; Cabri, Walter; Stasi, Maria Antonietta; Riccioni, Teresa; Borsini, Franco; Tarzia, Giorgio; Minetti, Patrizia

2013-07-11

341

Use of tert-butylbenzoylated tartardiamide chiral stationary phase for the enantiomeric resolution of acidic compounds by nano-liquid chromatography.  

PubMed

Several racemic acidic compounds of pharmaceutical and environmental interest have been separated into their enantiomers by nano-liquid chromatography (nano-LC) employing a tert-butylbenzoylated tartardiamide chiral stationary phase (CHI-TBB). CHI-TBB was packed into a fused silica capillary of 100 microm id and retained by two frits made with a heated wire; detection was on-column at a window (about 0.5 cm) prepared by removing the polyimide layer. The normal phase mode was selected for eluting the studied acidic compounds and therefore n-hexane/2-propanol/acetic acid (89/10/1, v/v/v) was used as mobile phase. Working at a flow rate of 220 nL/min a good resolution was obtained for mecoprop, dichlorprop, diclofop, fenoxaprop (herbicides) and for DF 1738Y, DF 1770Y, DF 2008Y (drugs under evaluation). In order to optimize the chiral resolution we modified the polarity of the mobile phase by adding several polar additives such as ethyl acetate, dichloromethane, tert-butyl methyl ether. Better results were obtained for some herbicides on working with 2-propanol/CH2Cl2/n-hexane/acetic acid (8/4/87/1, v/v/v/v). The influence of the capillary temperature on chiral resolution was studied for two herbicides with different chemical structures, namely mecoprop and haloxyfop in the temperature range between 10 and 40 degrees C and with n-hexane/2-propanol/1% acetic acid (89/10/1, v/v/v) as the mobile phase. Linear correlation of ln k vs 1/T and In alpha vs 1/ T was observed; deltaH degrees values were negative, demonstrating that retention of analytes was an exothermic process. A decrease in resolution was observed with rising temperature, showing that enantioresolution was mainly influenced by selectivity factors. PMID:16894787

Fanali, Salvatore; D'Orazio, Giovanni; Rocco, Anna

2006-07-01

342

Nucleophilic Participation in the Solvolyses of (Arylthio)methyl Chlorides and Derivatives: Application of Simple and Extended Forms of the Grunwald-Winstein Equations  

PubMed Central

The specific rates of solvolysis of chloromethyl phenyl sulfide [(phenylthio)methyl chloride] and its p-chloro-derivative have been determined at 0.0 °C in a wide range of hydroxylic solvents, including several containing a fluroalcohol. Treatment in terms of a two-term Grunwald-Winstein equation, incorporating terms based on solvent ionizing power (YCl) and solvent nucleophilicity (NT) suggest a mechanism similar to that for the solvolyses of tert-butyl chloride, involving in the rate-determining step a nucleophilic solvation of the incipient carbocation in an ionization process. A previous suggestion, that a third-term governed by the aromatic ring parameter (I) is required, is shown both for the new and for the previously studied related substrates to be an artifact, resulting from an appreciable degree of multicollinearity between I values and a linear combination of NT and YCl values. PMID:22711999

Kevill, Dennis N.; Park, Young Hoon; Park, Byoung-Chun; D’Souza, Malcolm J.

2012-01-01

343

Thermochemistry, reaction paths, and kinetics on the tert-isooctane radical reaction with O2.  

PubMed

Thermochemical properties of tert-isooctane hydroperoxide and its radicals are determined by computational chemistry. Enthalpies are determined using isodesmic reactions with B3LYP density function and CBS QB3 methods. Application of group additivity with comparison to calculated values is illustrated. Entropy and heat capacities are determined using geometric parameters and frequencies from the B3LYP/6-31G(d,p) calculations for the lowest energy conformer. Internal rotor potentials are determined for the tert-isooctane hydroperoxide and its radicals in order to identify isomer energies. Recommended values derived from the most stable conformers of tert-isooctane hydroperoxide of are -77.85 ± 0.44 kcal mol(-1). Isooctane is a highly branched molecule, and its structure has a significant effect on its thermochemistry and reaction barriers. Intramolecular interactions are shown to have a significant effect on the enthalpy of the isooctane parent and its radicals on peroxy/peroxide systems, the R• + O2 well depths and unimolecular reaction barriers. Bond dissociation energies and well depths, for tert-isooctane hydroperoxide ? R• + O2 are 33.5 kcal mol(-1) compared to values of ?38 to 40 kcal mol(-1) for the smaller tert-butyl-O2 ? R• + O2. Transition states and kinetic parameters for intramolecular hydrogen atom transfer and molecular elimination channels are characterized to evaluate reaction paths and kinetics. Kinetic parameters are determined versus pressure and temperature for the chemically activated formation and unimolecular dissociation of the peroxide adducts. Multifrequency quantum RRK (QRRK) analysis is used for k(E) with master equation analysis for falloff. The major reaction paths at 1000 K are formation of isooctane plus HO2 followed by cyclic ether plus OH. Stabilization of the tert-isooctane hydroperoxy radical becomes important at lower temperatures. PMID:24894154

Snitsiriwat, Suarwee; Bozzelli, Joseph W

2014-07-01

344

Review of the biological response to a novel bone cement containing poly(ethyl methacrylate) and n-butyl methacrylate  

Microsoft Academic Search

This review describes work published independently elsewhere in which the biological reactions to poly(ethyl methacrylate) n-butyl methacrylate (PEMBMA) have been studied. This material has been compared throughout with conventional poly(methyl methacrylate) (PMMA). Butyl methacrylate monomer used in PEMBMA was slightly less toxic than methyl methacrylate monomer used in PMMA when injected intraperitoneally in mice. No differences in cardiorespiratory effects were

P. A. Revell; M. Braden; M. A. R. Freeman

1998-01-01

345

Coated wire lead(II) selective potentiometric sensor based on 4- tert-butylcalix[6]arene  

Microsoft Academic Search

A coated-wire lead ion-selective electrode (ISE) has been constructed using 5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexahydroxycalix[6]arene as neutral carrier in a poly(vinyl chloride) matrix. The sensor exhibited a linear Nernstian response over the range 1×10?6 to 1×10?1M with a slope of 30±1mV per decade change and a detection limit of 6×10?7M. The working pH range of the sensor is 1.5–6.0 and it shows good selectivity

Vaishali S. Bhat; Vijaykumar S. Ijeri; Ashwini K. Srivastava

2004-01-01

346

Telomerase Reverse Transcriptase (TERT) is a Therapeutic Target of Oleanane Triterpenoid CDDO-Me in Prostate Cancer  

PubMed Central

Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is an synthetic oleanane triterpenoid with strong antiprolifertive and proapoptotic activities in cancer cells. However, the effect of CDDO-Me on human telomerase reverse transcriptase (hTERT) and its telomerase activity in prostate cancer cells has not been studied. We investigated the role of hTERT in mediating the anticancer activity of CDDO-Me in prostate cancer cells in vitro and in vivo. The inhibition of cell proliferation and induction of apoptosis by CDDO-Me in LNCaP and PC-3 prostate cancer cell lines was associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT transcriptionally and post-translationally. Furthermore, ablation of hTERT protein increased the sensitivity of cancer cells to CDDO-Me, whereas its overexpression rendered them resistant to CDDO-Me. In addition, inhibition of progression of preneoplastic lesions (i.e., low and high-grade prostate intraepithelial neoplasms, PINs) to adenocarcinoma of the prostate by CDDO-Me in TRAMP mice was associated with significant decrease in TERT and its regulatory proteins in the prostate gland. These data provide evidence that telomerase is a potential target of CDDO-Me for the prevention and treatment of prostate cancer. PMID:23519253

Liu, Yongbo; Gao, Xiaohua; Deeb, Dorrah; Arbab, Ali S.; Gautam, Subhash C.

2013-01-01

347

The stereochemistry of excited state atom reorganization processes; the di-pi-methane rearrangement  

E-print Network

, 24 mol) of potassium tert-bu- toxide in 1/0 ml of tert-butyl alcohol was added 33. 9 g E (0, 18 mol) of 3-phenylcyclohexene-1-carboxaldehyde. To this was added 52. 09 g (0. 37 mol) of methyl iodide in 65 ml of tert-butyl alcohol at 50..., 24 mol) of potassium tert-bu- toxide in 1/0 ml of tert-butyl alcohol was added 33. 9 g E (0, 18 mol) of 3-phenylcyclohexene-1-carboxaldehyde. To this was added 52. 09 g (0. 37 mol) of methyl iodide in 65 ml of tert-butyl alcohol at 50...

Ko, Jan Kwei

2012-06-07

348

Di-n-butyl-ammonium 2-(3,5-di-tert-butyl-4-hydroxy-benzyl-sulfan-yl)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

349

Microbial metabolism of fluazifop-butyl.  

PubMed

A microbial mixed culture able to grow on fluazifop-butyl and fluazifop was isolated. Fluazifop degradation by this microbial population was studied either when the herbicide was applied as the sole carbon source or in the presence of a second carbon source (sodium acetate or sodium propionate). The degradation rate was enhanced by sodium propionate. The degradation was found to be stereoselective. The S-enantiomer of fluazifop was degraded at a much higher rate than the R-enantiomer. Fluazifop disappearance was accompanied by formation of three metabolites which were identified by UV, IR, MS and NMR analyses. The metabolites were shown to be: 4-(5-trifluoromethyl-2-pyridyl)oxyphenol, 5-trifluoromethyl-2- hydroxypyridine and 2-(5-trifluoro-methyl pyridyl)hydroxy acetate. PMID:8409232

Nègre, M; Gennari, M; Andreoni, V; Ambrosoli, R; Celi, L

1993-10-01

350

In situ electrochemical SFG/DFG study of CN- and nitrile adsorption at Au from 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ionic liquid([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]diazenyl} benzonitrile (CTDB) and K[Au(CN)?].  

PubMed

In this paper we report an in situ electrochemical Sum-/Difference Frequency Generation (SFG/DFG) spectroscopy investigation of the adsorption of nitrile and CN? from the ionic liquid 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) containing 4-{2-[1-(2-cyanoethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-diazenyl}benzonitrile (CTDB) at Au electrodes in the absence and in the presence of the Au-electrodeposition process from K[Au(CN)?]. The adsorption of nitrile and its coadsorption with CN? resulting either from the cathodic decomposition of the dye or from ligand release from the Au(I) cyanocomplex yield potential-dependent single or double SFG bands in the range 2,125-2,140 cm?¹, exhibiting Stark tuning values of ca. 3 and 1 cm?¹ V?¹ in the absence and presence of electrodeposition, respectively. The low Stark tuning found during electrodeposition correlates with the cathodic inhibiting effect of CTDB, giving rise to its levelling properties. The essential insensitivity of the other DFG parameters to the electrodeposition process is due to the growth of smooth Au. PMID:22732885

Bozzini, Benedetto; Busson, Bertrand; Gayral, Audrey; Humbert, Christophe; Mele, Claudio; Six, Catherine; Tadjeddine, Abderrahmane

2012-01-01

351

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

PubMed

The 5-HT1AR partial agonist PET radiotracer, [(11)C]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=0.1nM; Emax=77%; EC50=0.65nM) 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 [(18)F]fluoroethyltosylate in DMSO in the presence of 1.6equiv of K2CO3 in 45±5% yield (EOS). PET shows [(18)F]FECUMI-101 binds specifically to 5-HT1AR enriched brain regions of baboon. The specificity of [(18)F]FECUMI-101 binding to 5-HT1AR was confirmed by challenge studies with the known 5-HT1AR ligand WAY100635. These findings indicate that [(18)F]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; Kumar, J S Dileep

2013-09-01

352

Anhydrous tert-pentanol as a novel media for the efficient enzymatic synthesis of amoxicillin  

Microsoft Academic Search

The efficient enzymatic synthesis of amoxicillin using anhydrous tert-pentanol as a novel media has been demonstrated for the first time. p-OH-Phenylglycine methyl ester (HPGM) was selected as the activated acyl donor due to its good solubility in organic solvents. The screening results of 21 organic solvents showed that solvents with either strong polarity or poor substrate solubility were unfavorable. Remarkable

Chun-Xiu Chen; Qi Wu; Bo-Kai Liu; De-Shui Lv; Xian-Fu Lin

2008-01-01

353

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

354

Tetra-butyl-ammonium butyl-tetra-chlorido-stannate(IV).  

PubMed

In the title compound, [N(C4H9)4][Sn(C4H9)Cl4], the Sn(IV) atom of the stannate anion has a trigonal-bipyramidal coordination sphere by two Cl atoms and one butyl chain in the equatorial plane and by two Cl atoms in the apical positions. Two of the four butyl chains of the tetra-butyl-ammonium cation are partially disordered, each with refined site occupancies of 0.691?(6):0.309?(6). Weak C-H?Cl hydrogen-bonding inter-actions help to consolidate the crystal packing, as well as a short Cl?Cl inter-action of 3.295?(2)?Å. PMID:24098187

Diop, Tidiane; van der Lee, Arie; Diop, Libasse

2013-01-01

355

Tetra-butyl-ammonium butyl-tetra-chlorido-stannate(IV)  

PubMed Central

In the title compound, [N(C4H9)4][Sn(C4H9)Cl4], the SnIV atom of the stannate anion has a trigonal-bipyramidal coordination sphere by two Cl atoms and one butyl chain in the equatorial plane and by two Cl atoms in the apical positions. Two of the four butyl chains of the tetra­butyl­ammonium cation are partially disordered, each with refined site occupancies of 0.691?(6):0.309?(6). Weak C—H?Cl hydrogen-bonding inter­actions help to consolidate the crystal packing, as well as a short Cl?Cl inter­action of 3.295?(2)?Å. PMID:24098187

Diop, Tidiane; van der Lee, Arie; Diop, Libasse

2013-01-01

356

Reduction of cytotoxic p-quinone metabolites of tert-butylhydroquinone by human aldo-keto reductase (AKR) 1B10.  

PubMed

2-tert-Butylhydroquinone (BHQ), an antioxidant used as a food additive, exhibits an anticancer effect, whereas it is carcinogenic in rodents at high doses. BHQ is metabolized into cytotoxic tert-butylquinone (BQ), which is further converted to 6-tert-butyl-2,3-epoxy-4-hydroxy-5-cyclohexen-1-one (TBEH) through 6-tert-butyl-2,3-epoxy-4-benzoquinone (TBE), which induces chromosomal aberration. The reductases for BQ and TBE may be protective against the toxicity of the two p-quinones, but the responsible human enzymes remain unidentified. In this study, we compared the ability of 12 human recombinant enzymes in the aldo-keto reductase (AKR) and short-chain dehydrogenase/reductase superfamilies to reduce BQ and TBE. Among them, AKR1B10 was the most efficient catalyst of the stoichiometric two-electron reduction of BQ and TBE into BHQ and TBEH, respectively. BQ and TBE are more cytotoxic towards endothelial cells than BHQ and TBEH, and their cytotoxicity was decreased by the overexpression of AKR1B10 in the cells. Additionally, AKR1B10 gene expression in human HCT116 cells was up-regulated by treatments with BHQ, BQ and TBE. These results suggest a role for the enzyme in protection at least against the toxicity of the two p-quinone metabolites of BHQ. PMID:22498646

Matsunaga, Toshiyuki; Endo, Satoshi; Takemura, Mayuko; Soda, Midori; Yamamura, Keiko; Tajima, Kazuo; Miura, Takeshi; Terada, Tomoyuki; El-Kabbani, Ossama; Hara, Akira

2012-01-01

357

Preparation of tert-butyl-capped polyenes containing up to 15 double bonds  

SciTech Connect

7,8-Bis(trifluoromethyl)tricyclo(4.2.2.0{sup 2.5})deca-3,7,9-triene (TCDT) can be ring-opened in a controlled manner by W(CH-t-Bu)(NAr)(O-t-Bu){sub 2} (Ar = 2,6-C{sub 6}H{sub 3}-i-Pr{sub 2}) to give living oligomers from which the metal can be removed in a Wittig-like reaction with pivaldehyde or 4,4-dimethyl-trans-2-pentenal. Mixtures of odd and even polyenes have been analyzed by reversed-phase HPLC methods, and those having as many as 13 double bonds have been isolated by column chromatography on silica gel under dinitrogen at {minus}40{degree}C and characterized by {sup 1}H and {sup 13}C NMR and UV-vis studies. The 17-ene has been observed by HPLC. Polyenes containing more than 17 double bonds are relatively unstable under the reaction and subsequent isolation conditions; those containing between 11 and 15 double bonds decompose thermally progressively more readily. UV-vis and {sup 13}C and {sup 1}H NMR data have been collected and analyzed in detail for the trans(cis,trans){sub x} isomers for x = 1-5 (up to 11 double bonds) and for the odd and even all-trans forms containing up to nine double bonds.

Knoll, K.; Schrock, R.R. (Massachusetts Institute of Technology, Cambridge (USA))

1989-11-27

358

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.

359

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

360

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...

361

Induction of oxidative DNA damage and early lesions in rat gastro-intestinal epithelium in relation to prostaglandin H synthase-mediated metabolism of butylated hydroxyanisole  

Microsoft Academic Search

The effect of metabolic activation of the food additive 3-tert-butyl-4-hydroxyanisole (BHA) by prostaglandin H synthase on the gastro-intestinal cell proliferation was determined by studies of the nature and the time dependency of early lesions in the forestomach, glandular stomach and colon\\/rectum of rats given BHA with and without co-administration of acetylsalicyclic acid (ASA; an inhibitor of prostaglandin H synthase), in

P. A. E. L. Schilderman; F. J. ten Vaarwerk; J. T. Lutgerink; A. Van Der Wurff; F. ten Hoor; J. C. S. Kleinjans

1995-01-01

362

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; Pfaffli, P

1999-01-01

363

Organoruthenium chalcogen complexes: synthesis of tert-butyl-cyclopentadienyl dicarbonyl ruthenium thio- and seleno-carboxylate complexes and crystal structure determination of ( tBu?C 5H 4)Ru(CO) 2SCO(3NO 2?C 6H4) and ( tBu?C 5A 4)Ru(CO) 2SeCO(3,5-(NO 2) 2?C 6H 3)  

Microsoft Academic Search

The substituted cyclopentadienyl organoruthenium dimers [(tBu?C5H4)Ru(CO)2]2(I) and [(1,3-Bu2-C5H3)Ru(CO)2]2(II) were prepared from the reaction of Ru3(CO)12 with t-butyl cyclopentadiene or 1,3-di-t-butylcyclopentadiene. The thermal reaction of dimer I with elemental sulfur or selenium afforded mixtures of organoruthenium polysulfides and polyselenides from which the binuclear pentasulfur and pentaselenium bridged complexes [(tBu?C5H4)Ru(CO)2]2(?-S5)(III) and [(tBu?C5H4)Ru(CO)2]2(?-Se5)(IV) were isolated and characterized. The organoruthenium sulfides and selenides readily

Ibrahim Jibril; Fatima T. Esmadi; Harbi Al-Masri; Laslo Zsolnai; Gottfried Huttner

1996-01-01

364

HUMAN EXPOSURE OF METHYL TERTIARY BUTYL ETHER (MTBE)  

EPA Science Inventory

Data on ambient air quality and microenvironmental exposures (e.g., during refueling, inside cards, in personal garages) are too limited for a quantitative estimate of population exposures to MTBE. t best, they can be used to estimate broad ranges of potential exposures. ecause o...

365

Di-tert-butylhydroxylated flavonoids protect endothelial cells against oxidized LDL-induced cytotoxicity.  

PubMed

The protective effect of di-tert-butylhydroxylated flavonoids (chalcones and arylidenes) against minimally oxidized LDL (mO-LDL)-induced cytotoxicity was studied in cultured bovine aortic endothelial cells. Most of the tested compounds decreased aldehydes formation in medium containing mO-LDL, but their capacity to inhibit LDL oxidation in the cellular medium was not sufficient to totally reduce the cellular toxicity of mO-LDL. Most of the tested flavonoids improved the integrity of cells exposed to mO-LDL, whereas butylated hydroxytoluene was ineffective and quercetin worsened the toxicity of mO-LDL. Moreover these flavonoids induced an increase in GSH cellular levels and their protective effects might be because of their inability to reduce metal ion. Arylidene 6 substituted at position 7 by a hydroxyl group was the most potent compound. PMID:11835624

Furman, C; Lebeau, J; Fruchart, J; Bernier, J; Duriez, P; Cotelle, N; Teissier, E

2001-01-01

366

Catalytic Activity of Polymer Anchored Cu-tren Complex in the Oxidation of 2,6-Di-t-butyl Phenol  

Microsoft Academic Search

Poly(styrene-co-dimethylaminoethyl methacrylate) and poly(methyl methacrylate-co- dimethylaminoethyl methacrylate) were prepared by solution polymerization. These polymers were quaternized by methyl iodide and n-hexyl bromide. The produced polymers were used as support in the aqueous oxidation of 2,6-di-tert-butylphenol (DBP) using hydrogen peroxide catalyzed by tris(2-aminoethyl)amine copper(II) complex “Cu(II)-tren complex” anchored on the prepared polymers. The products obtained from the reactions were 3,3?-5,5?-tetra-tert-butyldiphenoquinine (DPQ)

Hany El-Hamshary; Samia Al-Sigeny; Mohamed M. Ibrahim

2010-01-01

367

Determination of acidic drugs in sewage water by gas chromatography–mass spectrometry as tert.-butyldimethylsilyl derivatives  

Microsoft Academic Search

A procedure is described for the determination of five acidic non-steroidal anti-inflammatory pharmaceuticals (ibuprofen, naproxen, ketoprofen, tolfenamic acid and diclofenac) in sewage water. The analytical method involves the concentration of water samples using a solid-phase extraction polymeric sorbent, functionalized with N-vinylpyrrolidone. Analytes were eluted with ethyl acetate, derivatized using N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and analyzed by GC–MS. Influence of time, temperature and

I Rodr??guez; J. B Quintana; J Carpinteiro; A. M Carro; R. A Lorenzo; R Cela

2003-01-01

368

Altered histone mark deposition and DNA methylation at homeobox genes in human oral squamous cell carcinoma.  

PubMed

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, Exp Cell Res) 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

2014-10-01

369

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

370

The metabolism of the isomeric tert.-butylcyclohexanones  

PubMed Central

1. (±)-2-, (±)-3- and 4-tert.-Butylcyclohexanone are reduced in the rabbit to secondary alcohols, which are excreted extensively conjugated with glucuronic acid. 2. The major metabolite of (±)-2-tert.-butylcyclohexanone is (+)-cis-2-tert.-butylcyclohexanol, which has been isolated from the urine as [(+)-cis-2-tert.-butylcyclohexyl ?-d-glucosid]uronic acid. The minor metabolite is (+)-trans-2-tert.-butylcyclohexanol. 3. (±)-3-tert.-Butylcyclohexanone is reduced mainly to (±)-cis-3-tert.-butylcyclohexanol, and to a smaller extent to (±)-trans-3-tert.-butylcyclohexanol. 4. 4-tert.-Butylcyclohexanone yields mainly the trans-alcohol, which is excreted in conjugated form and has been recovered from the urine as (trans-4-tert.-butylcyclohexyl ?-d-glucosid)uronic acid. The cis-alcohol is formed to a minor extent and excreted in conjugated form. 5. The ratios of the amounts of cis- to trans-alcohols produced by the three ketones differed from the relative amounts of cis- and trans-alcohols produced by the corresponding methylcyclohexanones. 6. From these findings the suggestion is made that two orientations of ketone relative to coenzyme occur: alcohols with an equatorially orientated hydroxyl group are thought to be produced as a result of a `face-to-face' interaction with NADH, and alcohols with axially orientated hydroxyl groups as a result of a `perpendicular' interaction. Which will predominate is thought to depend on steric factors, particularly the size and position of alkyl substituents in the substrate. PMID:4291995

Cheo, K. L.; Elliott, T. H.; Tao, R. C. C.

1967-01-01

371

Assessment on radiochemical recycling of butyl rubber  

Microsoft Academic Search

The behavior of butyl rubber samples subjected to accelerated electron beams or ?-rays was studied in order to characterize its availability to radiation processing. Changes in some main properties such as average weight, molecular weight, gel content, Mooney viscosity, unsaturation level and degradation index were determined at various doses. Vulcanized butyl rubber starts significant radiodegradation at about 45 kGy. An

T. Zaharescu; C. Cazac; S. Jipa; R. Setnescu

2001-01-01

372

1-butyl-3-methylimidazolium 3,5-dinitro-1,2,4-triazolate: a novel ionic liquid containing a rigid, planar energetic anion.  

PubMed

The novel ionic liquid, 1-butyl-3-methylimidazolium 3,5-dinitro-1,2,4-triazolate has been synthesized and exhibits an unexpectedly low melting point (35 degrees C) considering the size and shape of the rigid, planar anion; analogous tetraalkylammonium salts (methyl, ethyl and n-butyl) have also been prepared and the tetraethylammonium example was characterized by single crystal X-ray diffraction. PMID:15700064

Katritzky, Alan R; Singh, Shailendra; Kirichenko, Kostyantyn; Holbrey, John D; Smiglak, Marcin; Reichert, W Matthew; Rogers, Robin D

2005-02-21

373

Hydrogen Bonded Rings, Chains and Lassos: The Case of T-butyl Alcohol Clusters  

SciTech Connect

Infrared OH stretching spectra of hydrogen bonded 2-methyl-propan-2-ol (t-butyl alcohol) clusters are investigated by ragout-jet FTIR spectroscopy. A spectral difference technique is used to discriminate approximately between neighbouring cluster sizes. Dimers, trimers and cyclic tetramers can be detected along with larger clusters, which exhibit a surprisingly structured vibrational fingerprint. Comparison is made to the spectra of related alcohols and to energetic and harmonic vibrational predictions from electronic structure calculations.

Zimmermann, D; Haber, Th; Schaal, H; Suhm, M A.

2001-03-10

374

Hydrogen bonded rings, chains and lassos: the case of t-butyl alcohol clusters  

Microsoft Academic Search

Infrared OH stretching spectra of hydrogen bonded 2-methyl-propan-2-01 (t-butyl alcohol) clusters are investigated by ragout-jet FTIR spectroscopy. A spectral difference technique is used to discriminate approximately between neighbouring cluster sizes. Dimers, trimers and cyclic tetramers can be detected along with larger clusters, which exhibit a surprisingly structured vibrational fingerprint. Comparison is made to the spectra of related alcohols and to

D. ZIMMERMANN; T. H. HÄBER; H. SCHAAL; M. A. SUHM

2001-01-01

375

Hydrogen bonded rings, chains and lassos: the case of t-butyl alcohol clusters  

Microsoft Academic Search

Infrared OH stretching spectra of hydrogen bonded 2-methyl-propan-2-ol (t-butyl alcohol) clusters are investigated by ragout-jet FTIR spectroscopy. A spectral difference technique is used to discriminate approximately between neighbouring cluster sizes. Dimers, trimers and cyclic tetramers can be detected along with larger clusters, which exhibit a surprisingly structured vibrational fingerprint. Comparison is made to the spectra of related alcohols and to

D. Zimmermann; Th. Häber; H. Schaal; M. A. Suhm

2001-01-01

376

Rigid P-chiral phosphine ligands with tert-butylmethylphosphino groups for rhodium-catalyzed asymmetric hydrogenation of functionalized alkenes.  

PubMed

Both enantiomers of 2,3-bis(tert-butylmethylphosphino)quinoxaline (QuinoxP*), 1,2-bis(tert-butylmethylphosphino)benzene (BenzP*), and 1,2-bis(tert-butylmethylphosphino)-4,5-(methylenedioxy)benzene (DioxyBenzP*) were prepared in short steps from enantiopure (S)- and (R)-tert-butylmethylphosphine-boranes as the key intermediates. All of these ligands were crystalline solids and were not readily oxidized on exposure to air. Their rhodium complexes exhibited excellent enantioselectivities and high catalytic activities in the asymmetric hydrogenation of functionalized alkenes, such as dehydroamino acid derivatives and enamides. The practical utility of these catalysts was demonstrated by the efficient preparation of several chiral pharmaceutical ingredients having an amino acid or a secondary amine component. A rhodium complex of the structurally simple ligand BenzP* was used for the mechanistic study of asymmetric hydrogenation. Low-temperature NMR studies together with DFT calculations using methyl ?-acetamidocinnamate as the standard model substrate revealed new aspects of the reaction pathways and the enantioselection mechanism. PMID:22192064

Imamoto, Tsuneo; Tamura, Ken; Zhang, Zhenfeng; Horiuchi, Yumi; Sugiya, Masashi; Yoshida, Kazuhiro; Yanagisawa, Akira; Gridnev, Ilya D

2012-01-25

377

hTERT and TP53 deregulation in intestinal-type gastric carcinogenesis in non-human primates.  

PubMed

Despite the high incidence, the molecular events involved in intestinal-type gastric carcinogenesis remains unclear. We previously established an intestinal-type gastric carcinogenesis model in Cebus apella, a New World monkey. In the present study, we evaluated hTERT and TP53 mRNA expression, as well as their protein immunoreactivity, in normal mucosa, non-atrophic gastritis, atrophic gastritis, intestinal metaplasia, and intestinal-type gastric cancer samples of non-human primates treated with N-methyl-nitrosourea. In addition, we evaluated the number of TP53 copies in these samples. Although hTERT immunoreactivity was only detected in gastric cancer, a continuous increase of hTERT mRNA expression was observed from non-atrophic gastritis to gastric tumors. No sample presented p53 immunoreactivity. However, we also observed a continuous decrease of TP53 mRNA expression during the sequential steps of gastric carcinogenesis. Moreover, loss of TP53 copies was observed in intestinal metaplasia and gastric cancer samples. Our study highlights that hTERT and TP53 have a key role in intestinal-type gastric cancer initiation. PMID:22707033

Leal, Mariana Ferreira; Calcagno, Danielle Queiroz; Khayat, André Salim; Silva, Tanielly Cristina Raiol; Muniz, José Augusto Pereira Carneiro; Assumpção, Paulo Pimentel; de Arruda Cardoso Smith, Marília; Burbano, Rommel Rodríguez

2013-08-01

378

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

379

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

380

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

381

Unscheduled DNA synthesis induced in human lymphocytes by butyl glycidyl ethers.  

PubMed

Unscheduled DNA synthesis (UDS) was examined in normal human peripheral blood lymphocytes (HPBL) exposed to n- and tert.-butyl glycidyl ethers (BGE). n-BGE, which is currently used as a major reactive diluent for industrial epoxy resin systems, has been implicated as a bacterial mutagen. t-BGE, a potential replacement for n-BGE, is less cytotoxic to HPBL. Both these BGEs have demonstrated genetic activity in human cells. Here, slide autoradiography and liquid scintillation counting techniques have been used to show that both n-BGE and t-BGE induce repair-DNA synthesis in normal HPBL. These agents demonstrate similar dose-response relationships over the range of concentrations up to 333 micrograms/ml. Cultures were examined for repair-DNA synthesis after a continuous 5-h exposure to varying concentration of n-BGE or t-BGE. PMID:7144779

Frost, A F; Legator, M S

1982-09-01

382

Telomere Lengths, Pulmonary Fibrosis and Telomerase (TERT) Mutations  

Microsoft Academic Search

BackgroundTelomerase 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

Alberto Diaz de Leon; Jennifer T. Cronkhite; Anna-Luise A. Katzenstein; J. David Godwin; Ganesh Raghu; Craig S. Glazer; Randall L. Rosenblatt; Carlos E. Girod; Edward R. Garrity; Chao Xing; Christine Kim Garcia; Rory Edward Morty

2010-01-01

383

Palladium-Catalyzed Synthesis of N-tert-Prenylindoles  

PubMed Central

Palladium-catalyzed N-tert-prenylation of indoles, tricarbonylchromium-activated indoles, and indolines that occur in high yields (up to 94%) with high tert-prenyl-to-n-prenyl selectivity (up to 12:1) are reported. PMID:23714013

Johnson, Kirsten F.; Van Zeeland, Ryan

2013-01-01

384

Methylation matters  

PubMed Central

DNA methylation is not just for basic scientists any more. There is a growing awareness in the medical field that having the correct pattern of genomic methylation is essential for healthy cells and organs. If methylation patterns are not properly established or maintained, disorders as diverse as mental retardation, immune deficiency, and sporadic or inherited cancers may follow. Through inappropriate silencing of growth regulating genes and simultaneous destabilisation of whole chromosomes, methylation defects help create a chaotic state from which cancer cells evolve. Methylation defects are present in cells before the onset of obvious malignancy and therefore cannot be explained simply as a consequence of a deregulated cancer cell. Researchers are now able to detect with exquisite sensitivity the cells harbouring methylation defects, sometimes months or years before the time when cancer is clinically detectable. Furthermore, aberrant methylation of specific genes has been directly linked with the tumour response to chemotherapy and patient survival. Advances in our ability to observe the methylation status of the entire cancer cell genome have led us to the unmistakable conclusion that methylation abnormalities are far more prevalent than expected. This methylomics approach permits the integration of an ever growing repertoire of methylation defects with the genetic alterations catalogued from tumours over the past two decades. Here we discuss the current knowledge of DNA methylation in normal cells and disease states, and how this relates directly to our current understanding of the mechanisms by which tumours arise.???Keywords: methylation; cancer PMID:11333864

Costello, J.; Plass, C.

2001-01-01

385

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

386

Safety Assessment of Butylated Hydroxyanisole and Butylated Hydroxytoluene as Antioxidant Food Additives  

Microsoft Academic Search

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are widely used antioxidant food additives. They have been extensively studied for potential toxicities. This review details experimental studies of genotoxicity and carcinogenicity which bear on cancer hazard assessment of exposure to humans. We conclude that BHA and BHT pose no cancer hazard and, to the contrary, may be anticarcinogenic at current levels

G. M Williams; M. J Iatropoulos; J Whysner

1999-01-01

387

STABLE ISOTOPE ANALYSIS OF MTBE TO EVALUATE THE SOURCE OF TBA IN GROUND WATER  

EPA Science Inventory

Although tert-butyl alcohol (TBA) has not been used as a fuel oxygenate in Orange County, California, the concentrations of TBA in ground water at gasoline spill sites are high compared those of the conventional fuel oxygenate methyl tert-butyl ether (MTBE). In the year 2002, th...

388

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

389

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...

390

Biodegradation of tert-butylphenyl diphenyl phosphate.  

PubMed Central

The biodegradation of tert-butylphenyl diphenyl phosphate (BPDP) was examined in microcosms containing sediment and water from five different ecosystems as part of our studies to elucidate the environmental fate of phosphate ester flame retardants. Biodegradation of [14C]BPDP was monitored in the environmental microcosms by measuring the evolution of 14CO2. Over 37% of BPDP was mineralized after 8 weeks in microcosms from an ecosystem which had chronic exposure to agricultural chemicals. In contrast, only 1.7% of BPDP was degraded to 14CO2 in samples collected from a noncontaminated site. The exposure concentration of BPDP affected the percentage which was degraded to 14CO2 in microcosms from the two most active ecosystems. Mineralization was highest at a concentration of 0.1 mg of BPDP and was inhibited with 10- and 100-fold higher concentrations of BPDP in these microcosms. Indigenous heterotrophic and BPDP-utilizing microbial populations and phosphoesterase enzyme activities were highest in sediments which had the highest biodegradation of BPDP. We observed adaptive increases in both microbial populations and phosphoesterase enzymes in some sediments acclimated to BPDP. Chemical analyses of the residues in the microcosms indicated undegraded BPDP and minor amounts of phenol, tert-butylphenol, diphenyl phosphate, and triphenyl phosphate as biodegradation products. These data suggest that the microbial degradation of BPDP results from at least three catabolic processes and is highest when low concentrations of BPDP are exposed to sediment microorganisms of eutrophic ecosystems which have high phosphotri- and diesterase activities and previous exposure to anthropogenic chemicals. PMID:3082280

Heitkamp, M A; Freeman, J P; Cerniglia, C E

1986-01-01

391

I. Kinetic and mechanistic study of the (4+4) dimerization of 2,3-dimethylene-2,3-dihydrofuran. II. Preparation of 2,3-dimethylene-2,3-dihydrogenzo(b)furan by the flash vacuum pyrolysis of 2-methyl-3-benzo(b)furylmethyl benzoate. III. Reaction of 2,3-dimethylene-2,3-dihydrofuran with triplet oxygen  

SciTech Connect

A kinetic and mechanistic study of the (4+4) dimerization of 2,3-dimethylene-2,3-dihydrofuran (A) has been carried out based on the secondary deuterium kinetic isotope effects (2/sup 0/ D KIE), substituent effects and solvent effects. The 2/sup 0/ D KIE was studied by measuring the rate constants, k/sub 1/, k/sub 2/, k/sub 3/ and k/sub 4/, respectively, for the (4+4) dimerization of A, 2-methylene-3-dideuteriomethylene-2,3-dihydrofuran (B), 2-dideuteriomethylene-3-methylene-2,3-dihydrofuran (C) and 2,3-bis-(dideuteriomethylene)-2,3-dihydrofuran (D). 2-3-Dimethylene-2,3-dihydrobenzo(b)furan (E) was synthesized by the flash vacuum pyrolysis of 2-methyl-3-benzo(b)furylmethyl benzoate. The chemical reactions of E, which were investigated in this study, include thermal dimerization reactions and Diels-Alder reactions. The dimerization reaction of E gave both (4+2) and (4+4) dimers. The formation of cyclic peroxides from the reactions of A and its 5-methyl and 5-tert-butyl derivatives with triplet oxygen was investigated. Thermolysis of a cyclic peroxide gave dialdehyde, hydroxy aldehyde and diol as the products. 150 references, 28 figures, 70 tables.

Chou, C.H.

1985-03-01

392

Assessment on radiochemical recycling of butyl rubber  

NASA Astrophysics Data System (ADS)

The behavior of butyl rubber samples subjected to accelerated electron beams or ?-rays was studied in order to characterize its availability to radiation processing. Changes in some main properties such as average weight, molecular weight, gel content, Mooney viscosity, unsaturation level and degradation index were determined at various doses. Vulcanized butyl rubber starts significant radiodegradation at about 45 kGy. An advanced irradiation of IIR will decrease sharply the molecular weight of vulcanizates providing suitable plasticization matter for other kinds of synthetic rubbers.

Zaharescu, T.; Cazac, C.; Jipa, S.; Setnescu, R.

2001-12-01

393

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

394

21 CFR 172.270 - Sulfated butyl oleate.  

Code of Federal Regulations, 2011 CFR

...FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

2011-04-01

395

21 CFR 172.270 - Sulfated butyl oleate.  

Code of Federal Regulations, 2012 CFR

...FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

2012-04-01

396

21 CFR 172.270 - Sulfated butyl oleate.  

...HEALTH AND HUMAN SERVICES (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

2014-04-01

397

21 CFR 172.270 - Sulfated butyl oleate.  

Code of Federal Regulations, 2013 CFR

...FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate. Sulfate butyl oleate may be safely used in food,...

2013-04-01

398

21 CFR 172.270 - Sulfated butyl oleate.  

Code of Federal Regulations, 2010 CFR

...FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Coatings, Films and Related Substances § 172.270 Sulfated butyl oleate...mixture of butyl esters produced by transesterification of an edible vegetable oil using 1-butanol. Following sulfation,...

2010-04-01

399

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular geometry of butylated hydroxy toluene  

NASA Astrophysics Data System (ADS)

The FT-IR spectrum of 2,6-di-tert-butyl-4-methylphenol [butylated hydroxy toluene] was recorded in the region 4000-400 cm -1. The FT-Raman spectrum of butylated hydroxy toluene was also recorded in the region 3500-50 cm -1. The molecular structure and vibrational frequencies of butylated hydroxy toluene (BHT) have been investigated with combined experimental and theoretical study. Two stable conformers of the title compound were obtained from the result of geometry optimizations of these possible conformers. The conformer 1 is (approximately 2.6 kcal/mol) more stable than conformer 2. Geometry optimizations and vibrational frequency calculations were performed by BLYP and B3LYP methods using 6-31G(d), 6-31G(d,p) and 6-31+G(d,p) as basis sets. The scaled frequencies were compared with experimental spectrum and on the basis of this comparison; assignments of fundamental vibrational modes were examined. Comparison of the experimental spectra with harmonic vibrational wavenumbers indicates that B3LYP/6-31G(d) results are more accurate. Predicted electronic absorption spectra of BHT from TD-DFT calculation have been analyzed and compared with the experimental UV-vis spectrum. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule.

Chinna Babu, P.; Sundaraganesan, N.; Dereli, Ö.; Türkkan, E.

2011-08-01

400

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

401

Electrical conductivity enhancement of a polymer using butyl glycidyl ether (BGE)–lithium hexafluorophosphate (LiPF 6 ) complex  

Microsoft Academic Search

In this study, we investigated the improvement in electrical conductivity of a polymer with the addition of dissolved lithium\\u000a hexafluorophosphate (LiPF6) in an ether based solvent, butyl glycidyl ether (BGE). Thin film samples were fabricated by adding LiPF6 (up to 1 wt%) to poly (methyl-methacrylate) (PMMA). Film with 0.75% LiPF6 showed the highest improvement of electrical conductivity by three orders of

Soumen Jana; Wei-Hong Zhong

2008-01-01

402

A 10-watt CW photodissociation laser with IODO perfluoro-tert-butane  

NASA Technical Reports Server (NTRS)

NASA has been investigating the feasibility of direct solar-pumped laser systems for power beaming in space. Among the various gas, liquid, and solid laser systems being proposed as candidates for solar-pumped lasers, the iodine photodissociation gas laser has demonstrated its potential for space application. Of immediate attention is the determination of system requirements and the choice of lasants to improve the system efficiency. The development of an efficient iodine laser depends on the availability of a suitable iodide which has favorable laser kinetics, chemically reversibility, and solar energy utilization. Among the various alkyliodide lasants comparatively tested in a long-pulse system, perfluoro- tert-butyl iodide, T-C4F9I, was found to be the best. However, the operating conditions for the laser medium in a continuously pumped and continuous-flow iodine laser differ considerably from those in the pulsed regime. The results of the continuous wave (CW)) laser performance from t-C4F9I are reported. Perfluoro- n-propyl iodide, n-C3F7I is used for comparison because of its universal use in photodissociation iodine lasers.

Tabibi, Bagher; Venable, Demetrius D.

1989-01-01

403

Epigenetic mechanisms regulate placental c-myc and hTERT in normal and pathological pregnancies; c-myc as a novel fetal DNA epigenetic marker for pre-eclampsia.  

PubMed

Placental development is known for its resemblance with tumor development, such as in the expression of oncogenes (c-myc) and telomerase (hTERT). The expression of c-myc and hTERT is up-regulated during early pregnancy and gestational trophoblastic diseases (GTDs). To determine the role of DNA methylation [via methylation-sensitive high resolution melting (MS-HRM)] and histone modifications [via chromatin immunoprecipitation (ChIP assay)] in regulating the differential expression of c-myc and hTERT during normal gestation and their dysregulation during placental disorders, we obtained placental samples from 135 pregnant women, in five groups: normal first, second and third trimester (n = 30 each), pre-eclamptic pregnancy (n = 30) and molar pregnancy (n = 15). Two placental cell lines (JEG-3 and HTR-8/SVneo) and isolated first-trimester cytotrophoblasts were also studied. Quantitative RT-PCR revealed decreased mRNA expression levels of c-myc and hTERT, which were associated with a higher level of H3K9me3 (1.5-fold, P < 0.05) and H3K27me3 (1.9-fold, P < 0.05), respectively, in third-trimester placental villi versus first-trimester villi. A significantly lower level of H3K27me3 in molar placenta was associated with a higher mRNA expression of c-myc and hTERT. The development of pre-eclampsia (PE) was associated with increased methylation (P < 0.001) and H3K27me3 (P < 0.01) at the c-myc promoter and reduced H3K9me3 (P < 0.01) and H3K27me3 (P < 0.05) at the hTERT promoter. Further, mRNA expression of c-myc and hTERT was strongly correlated in molar villi (r = 0.88, P < 0.01) and JEG-3 cells (r = 0.99, P < 0.02). Moreover, on the basis of methylation data, we demonstrate the potential of c-myc as a fetal DNA epigenetic marker for pre-eclamptic pregnancies. Thus we suggest a role for epigenetic mechanisms in regulating differential expression of c-myc and hTERT during placental development and use of the c-myc promoter region as a potential fetal DNA marker in the case of PE. PMID:25024139

Rahat, Beenish; Hamid, Abid; Ahmad Najar, Rauf; Bagga, Rashmi; Kaur, Jyotdeep

2014-10-01

404

78 FR 48674 - Announcement of the IRIS Public Meeting Schedule for Calendar Years 2013 and 2014; Announcement...  

Federal Register 2010, 2011, 2012, 2013

...Preliminary Materials for tert-Butyl Alcohol, Ethyl tert-Butyl Ether, and Hexahydro-1...materials for three chemicals, tert-butyl alcohol (tert-butanol), ethyl-tert- butyl...October 23-24, 2013 Topics tert-Butyl alcohol (tert-Butanol) Ethyl...

2013-08-09

405

Mesoporous FeAlMCM-41: an improved catalyst for the vapor phase tert-butylation of phenol  

Microsoft Academic Search

A range of iron and aluminum-containing mesoporous molecular sieves FeAlMCM-41 with different nSi\\/(nFe+nAl) ratios have been synthesized hydrothermally and characterized in detail by physicochemical methods, viz. X-ray diffraction (XRD), N2 adsorption, elementary analysis, UV-Vis, ESR and 27Al MAS NMR spectroscopy. UV-Vis and ESR spectroscopy suggest that iron is present in tetrahedral coordination and imparts Brønsted acidity. The catalyst FeAlMCM-41 (nSi\\/nAl=40;

A. Vinu; K. Usha Nandhini; V. Murugesan; Winfried Böhlmann; V. Umamaheswari; Andreas Pöppl; Martin Hartmann

2004-01-01

406

Preparation of N- t Boc l-glutathione dimethyl and di- tert-butyl esters: Versatile synthetic building blocks  

Microsoft Academic Search

The title l-glutathione derivatives, containing acid- and base-labile esters, respectively, were obtained in good overall yields. N-tBoc l-glutathione dimethyl ester was prepared via Fischer esterification of l-glutathione disulfide (GSSG) using HCl in dry methanol, protection of the amine with tBoc2O, and tributylphosphine cleavage of the disulfide in wet isopropanol. Alternatively, Fischer esterification and tBoc-protection of l-glutathione (GSH) also furnished N-tBoc

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

2007-01-01

407

(Z)-tert-Butyl 2-(4-amino-9H-fluoren-9-yl-idene)acetate.  

PubMed

The title compound, C(19)H(19)NO(2), obtained as an almost equimolar mixture (as shown by (1)H NMR) with the E isomer through a Wittig reaction between 4-amino-9H-fluoren-9-one and the stabilized ylide Ph(3)P=CHCO(2)C(CH(3))(3), was obtained pure in the Z configuration following crystallization from toluene. The mol-ecule shows a planar arrangement of the ring system and the new double bond, whereas the carbonyl O atom forms a 45.1?(3)° dihedral angle with it. The mol-ecules are linked by N-H?O hydrogen bonds, forming cyclic structures with R(4) (4)(24) graph-set motifs. These motifs are connected to each other, giving rise to a sheet structure parallel to the ab plane. The linkage within the sheets is further enhanced by ?-? stacking inter-actions between the fluorene units [centroid-centroid distance = 3.583?(2)?Å]. PMID:21201178

Krokidis, Marios; Papaioannou, Dionissios; Nastopoulos, Vassilios

2008-01-01

408

(Z)-tert-Butyl 2-(4-amino-9H-fluoren-9-yl-idene)acetate  

PubMed Central

The title compound, C19H19NO2, obtained as an almost equimolar mixture (as shown by 1H NMR) with the E isomer through a Wittig reaction between 4-amino-9H-fluoren-9-one and the stabilized ylide Ph3P=CHCO2C(CH3)3, was obtained pure in the Z configuration following crystallization from toluene. The mol­ecule shows a planar arrangement of the ring system and the new double bond, whereas the carbonyl O atom forms a 45.1?(3)° dihedral angle with it. The mol­ecules are linked by N—H?O hydrogen bonds, forming cyclic structures with R 4 4(24) graph-set motifs. These motifs are connected to each other, giving rise to a sheet structure parallel to the ab plane. The linkage within the sheets is further enhanced by ?–? stacking inter­actions between the fluorene units [centroid–centroid distance = 3.583?(2)?Å]. PMID:21201178

Krokidis, Marios; Papaioannou, Dionissios; Nastopoulos, Vassilios

2008-01-01

409

Resveratrol in vitro ameliorates tert-butyl hydroperoxide-induced alterations in erythrocyte membranes from young and older humans.  

PubMed

Implication of reactive oxygen species/oxidative stress has been readily reported in etiology of aging and related manifestations. Plasma membrane as a regulator of numerous aspects of cell physiology including cell-cell interaction, solute transport, and signal transduction, provides structural integrity to the cells. The aim of the present study was to determine the effect of resveratrol administration in vitro, to evaluate the biological effect of this phytoalexin in oxidatively injured erythrocytes during aging. This study, carried out on 91 normal healthy subjects, provides experimental evidence that erythrocytes have increased oxidative damage with age. In vitro administration of resveratrol significantly attenuated deleterious effects of oxidative injury in erythrocytes from humans of all ages. PMID:24914573

Pandey, Kanti Bhooshan; Rizvi, Syed Ibrahim

2014-10-01

410

The Mechanism of Hyperoside Protection of ECV-304 Cells against tertButyl Hydroperoxide-Induced Injury  

Microsoft Academic Search

The aim of the present study was to investigate the mechanism of hyperoside protecting ECV-304 cells against tertbutyl hydroperoxide (TBHP)-induced injury. ECV-304 cell viability was measured by MTT assay. Cellular morphologic changes were observed using phase contrast microscopy. The genotoxic effects of TBHP and the protective ability of hyperoside were assessed by the Comet test. Lipid peroxidation was measured by

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

2008-01-01

411

Reactivity ratios and sequence determination of methacrylonitrile/butyl acrylate copolymers by NMR spectroscopy  

NASA Astrophysics Data System (ADS)

Methacrylonitrile/butyl acrylate (M/B) copolymers were prepared by bulk polymerization using benzoyl peroxide as an initiator. The Distortionless Enhancement by Polarization Transfer spectra were used to differentiate between the carbon resonance signals of methyl, methine, methylene and oxymethylene groups in the 13C{ 1H} NMR spectrum of the copolymer (M/B). Comonomer reactivity ratios were determined using Kelen-Tudos and non-linear error in variable methods. Two-dimensional Heteronuclear Single Quantum Coherence and Total Correlated Spectroscopy were used to resolve the complex 1H NMR spectrum and to determine the compositional and configurational sequences of M/B copolymers.

Brar, A. S.; Pradhan, D. R.; Hooda, Sunita

2004-08-01

412

TERT promoter mutations and BRAF mutations are rare in sporadic, and TERT promoter mutations are absent in NF1-related malignant peripheral nerve sheath tumors.  

PubMed

Hot spot mutations in the promoter region of telomerase reverse transcriptase (TERT promoter mutations) occur frequently in tumors of neuroectodermal origin such as melanoma and glioma. Many of these tumors are of neuroectodermal or ectomesenchymal origin which is suggestive of TERT promoter mutations playing a role in the development of malignant peripheral nerve sheath tumors (MPNSTs). In melanoma a correlation has been suggested between the occurrence of TERT promoter mutations and v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) mutations. We investigated TERT promoter and BRAF mutation frequency in respectively 94 and 86 consecutive MPNST cases from our institute. TERT promoter mutation analysis on DNA from formalin-fixed, paraffin-embedded specimens was performed by SNaPshot analysis. Sequence analysis of BRAF was performed by bidirectional DNA sequencing. We identified TERT C228T or C250T promoter mutations in 10 % (9/94) and BRAF V600E mutations in 3 % (3/86) of MPNSTs. All TERT promoter- and BRAF mutations occurred in NF1 unrelated tumors. One co-occurrence of a TERT promoter- and a BRAF mutation was observed. In comparison with other neuroectodermal derived malignant neoplasms, TERT promoter mutations occur at relatively low frequency in MPNSTs. The observation of TERT promotor and BRAF mutations in sporadic MPNSTs and the absence of TERT promotor and rarity of BRAF mutations in NF1 related tumors may imply an alternative genetic route of tumor progression in both patient groups. PMID:25035100

Dubbink, Hendrikus J; Bakels, Hannah; Post, Edward; Zwarthoff, Ellen C; Verdijk, Robert M

2014-11-01

413

The chicken telomerase reverse transcriptase (chTERT): molecular and cytogenetic characterization with a comparative analysis  

E-print Network

of TERT regulation and function in vertebrates utilizing the telomere clock mechanism to different degrees; SSC, sodium salt citrate; TERC or TR, telomerase RNA; TERT, telomerase reverse transcriptase; TNB

Delany, Mary E.

414

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)....

415

Kinetics of 1,4-Dioxane Biodegradation by  

E-print Network

, tetrahydrofuran, or toluene including Methylosinus trichosporium OB3b, Mycobacterium vaccae JOB5, Pseudonocardia K, 10). Several ethers, such as tetrahydrofuran and methyl tert- butyl ether, have also been shown

Alvarez-Cohen, Lisa

416

Synthesis of 2-cyanoacrylates via 2-cyanoacryloyl chloride  

Microsoft Academic Search

Monomers that are difficult to obtain, such as tert-butyl 2-cyanoacrylate, trimethylsilyl-methyl 2-cyanoacrylate, 2,2,3,3-tetrafluoropropyl 2-cyanoacrylate, and the previously unknown adamantyl 2-cyanoacrylate were prepared starting from 2-cyanoacryloyl chloride.

N. G. Senchenya; K. A. Mager; T. I. Guseva; Yu. G. Gololobov

1994-01-01

417

Antioxidant properties of di- tert-butylhydroxylated flavonoids  

Microsoft Academic Search

Epidemiological evidence suggests an inverse relationship between dietary intake of flavonoids and cardiovascular risk. The biological activities of flavonoids are related to their antioxidative effects, but they also can be mutagenic, due to the prooxidant activity of the catechol pattern. To prevent these problems, we synthesized new flavonoids where one or two di-tert-butylhydroxyphenyl (DBHP) groups replaced catechol moiety at position

Jonathan Lebeau; Christophe Furman; Jean-Luc Bernier; Patrick Duriez; Elisabeth Teissier; Nicole Cotelle

2000-01-01

418

Radioprotecting effect of propylgalate and butylated hydroxyanisol.  

PubMed

It has been reported that a great part of the deleterious effect caused by ionizing radiations is due to oxidative phenomena. The purpose of this work was to investigate if some antioxidants commonly used in the food industry might have a radioprotecting effect. N propyl-galate (NPG), hydroxyanisol-butylated (HAB) and hydroxytoluene-butylated (HTB) were utilized. Forty BALB/C mice that received 600 rads of gamma irradiation from a 60Co emitter died 17.12 +/- 7.82 days after. Thirteen mice that were injected 5 mg of NPG 24 hours and 30 minutes before radiation survived for more than 90 days. This same effect was observed in 13 mice that were also injected with 10 mg NPC and in other 13 that received 10 mg of HAB in the same way. Doses of 5 mg HAB or 5 and 10 mg HTB did not have a radioprotecting effect. When the radiation dose was increased to 800 rads, the radioprotecting effect was absent with any of the NPG, HAB or HTB doses. In protected mice, preservation of higher numbers of hematopoietic cells were observed in the bone marrow together with slight reduction of chromosomal fractures. There results show that antioxidants used in the food industry have a radioprotecting effect that had not been investigated. PMID:7294944

Ramos-Damián, M; Acosta-Ruiz, R; Hernández-Delgado, J; Vázquez-Valls, E; Gomez-Estrada, H

1981-01-01

419

Application of ionic liquids as plasticizers for poly(methyl methacrylate).  

PubMed

The room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, [C4mim][PF6] was found to be an efficient plasticizer for poly(methyl methacrylate), prepared by in situ radical polymerization in the ionic liquid medium; the polymers have physical characteristics comparable with those containing traditional plasticizers and retain greater thermal stability. PMID:12125560

Scott, Mark P; Brazel, Christopher S; Benton, Michael G; Mays, Jimmy W; Holbrey, John D; Rogers, Robin D

2002-07-01

420

Intake of butylated hydroxyanisole and butylated hydroxytoluene and stomach cancer risk: results from analyses in the Netherlands Cohort Study  

Microsoft Academic Search

Both carcinogenic and anticarcinogenic properties have been reported for the synthetic antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The association between dietary intake of BHA and BHT and stomach cancer risk was investigated in the Netherlands Cohort Study (NLCS) that started in 1986 among 120,852 men and women aged 55 to 69 years. A semi-quantitative food frequency questionnaire was

A. A. M. Botterweck; H. Verhagen; R. A. Goldbohm; J. Kleinjans; P. A. van den Brandt

2000-01-01

421

Global and gene specific DNA methylation changes during zebrafish development  

PubMed Central

DNA methylation is dynamic through the life of an organism. Previous studies have primarily focused on DNA methylation changes during very early embryogenesis. In this study, global and gene specific DNA methylation in zebrafish (Danio rerio) embryos, larvae and adult liver were compared. The percent methylation of cytosines was low in 2 to 4.3 hours post fertilization (hpf) zebrafish embryos and was consistently higher in zebrafish older than 6 hpf. Furthermore, quantitative real-time PCR (qPCR) results showed relatively high DNA methyltransferase 1 (dnmt1) and low glycine N-methyltransferase (gnmt) mRNA expression in early embryogenesis. By studying methylation patterns and gene expression of five developmentally important genes, namely vasa, Ras-association domain family member 1 (rassf1), telomerase reverse transcriptase (tert), c-jun and c-myca, we found that the timing of changes in DNA methylation patterns was gene specific, and changes in gene expression were not necessarily correlated with the DNA methylation patterns. PMID:23876386

Fang, Xiefan; Corrales, Jone; Thornton, Cammi; Scheffler, Brian E.; Willett, Kristine L.

2013-01-01

422

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

E-print Network

/L, and EPA has set its advisory level for taste and odor at 20­40 µg/L (3). In California, concern regarding con- struction at gas stations, spillage from vehicle acci- dents, and homeowner releases. In Maine

423

Novel di-tertiary-butyl phenylhydrazones as dual cyclooxygenase-2/5-lipoxygenase inhibitors: synthesis, COX/LOX inhibition, molecular modeling, and insights into their cytotoxicities.  

PubMed

Although dual inhibition of Cyclooxygenase-2 (COX-2) and 5-Lipoxygenase (5-LOX) enzymes is highly effective than targeting COX or LOX alone, there are only a few reports of examining such compounds in case of colorectal cancers (CRC). In the present work we report that the novel di-tert-butyl phenol-based dual inhibitors DTPSAL, DTPBHZ, DTPINH, and DTPNHZ exhibit significant cytotoxicity against human CRC cell lines. Molecular docking studies revealed a good fit of these compounds in the COX-2 and 5-LOX protein cavities. The inhibitors show significant inhibition of COX-2 and 5-LOX activities and are effective against a panel of human colon cancer cell lines including HCA-7, HT-29, SW480 and intestinal Apc10.1 cells as well as the hyaluronan synthase-2 (Has2) enzyme over-expressing colon cancer cells, through inhibition of the Hyaluronan/CD44v6 cell survival pathway. Western blot analysis and qRT-PCR analyses indicated that the di-tert-butyl phenol-based dual inhibitors reduce the expression of COX-2, 5-LOX, and CD44v6 in human colon cancer HCA-7 cells, while the combination of CD44v6shRNA and DTPSAL has an additional inhibitory effect on CD44v6 mRNA expression. The synergistic inhibitory effect of Celecoxib and Licofelone on CD44v6 mRNA expression suggests that the present dual inhibitors down-regulate cyclooxygenase and lipoxygenase enzymes through CD44v6. The compounds also exhibited enhanced antiproliferative potency compared to standard dual COX/LOX inhibitor, viz. Licofelone. Importantly, the HA/CD44v6 antagonist CD44v6shRNA in combination with synthetic compounds had a sensitizing effect on the cancer cells which enhanced their antiproliferative potency, a finding which is crucial for the anti-proliferative potency of the novel synthetic di-tert-butyl phenol based dual COX-LOX inhibitors in colon cancer cells. PMID:24295787

Ghatak, Shibnath; Vyas, Alok; Misra, Suniti; O'Brien, Paul; Zambre, Ajit; Fresco, Victor M; Markwald, Roger R; Swamy, K Venkateshwara; Afrasiabi, Zahra; Choudhury, Amitava; Khetmalas, Madhukar; Padhye, Subhash

2014-01-01

424

Toxicokinetics of p-tert-octylphenol in male Wistar rats  

Microsoft Academic Search

Only weak oestrogenic activity has been reported for p-alkylphenols compared with the physiological hormone 17?-estradiol. Despite the low potency, there is concern that due to\\u000a bioaccumulation oestrogenically efficient blood levels could be reached in humans exposed to trace levels of p-alkylphenols. To address these concerns, toxicokinetic studies with p-tert-octylphenol [OP; p-(1,1,3,3-tetramethylbutyl)-phenol] as a model compound have been conducted in male

H. Certa; N. Fedtke; H.-J. Wiegand; A. M. F. Müller; H. M. Bolt

1996-01-01

425

Direct amperometric determination of tert-butylhydroquinone in biodiesel  

Microsoft Academic Search

The direct amperometric determination of tert-butylhydroquinone (TBHQ) in biodiesel at an unmodified glassy carbon electrode is reported. A biodiesel aliquot was added into an electrochemical cell containing a 75% (v\\/v) ethanol–water solution under stirring (with final concentration of 50mmolL?1 HClO4). The amperometric method involved the continuous application of three sequential potential pulses to the working electrode (700mV for 300ms, 0mV

Thiago F. Tormin; Denise T. Gimenes; Leandro G. Silva; Reinaldo Ruggiero; Eduardo M. Richter; Valdir S. Ferreira; Rodrigo A. A. Muñoz

2010-01-01

426

Blood DNA methylation, nevi number, and the risk of melanoma.  

PubMed

Germline mutations determining increased cutaneous malignant melanoma (CMM) risk have been identified in familial and sporadic CMM cases, but they account only for a small proportion of CMM cases. Recent evidence suggests that germline epimutations (e.g. DNA methylation alterations), which can be inherited similarly to genomic mutations and can be detected in normal body cells (including blood), might increase susceptibility to cancer. The aim of the study was to identify germline epimutations of genes that were found to be mutated in familial CMM (p16, p14, CDK4, MC1R, hTERT), immune and inflammatory genes (ICAM-1, TNF?), DNA mismatch repair gene (MLH1), and repetitive elements (ALU, LINE-1, HERV-w). We measured DNA methylation using bisulfite pyrosequencing in peripheral blood mononuclear cells from 167 CMM cases and 164 sex-matched and age-matched controls. We used multivariable logistic regression models to evaluate the association between methylation levels and CMM status or presence of dysplastic nevi. We found an association between the risk of CMM and peripheral blood mononuclear cell methylation levels of TNF? [odds ratio (OR)=1.11, 95% confidence interval (CI)=1.03-1.18], CDK4 (OR=0.76, 95% CI=0.64-0.91), and MLH1 (OR=1.12, 95% CI=1.02-1.22). In control participants, the risk of developing dysplastic nevi was associated with methylation levels of TNF? (OR=0.81, 95% CI=0.69-0.95), hTERT (OR=0.90, 95% CI=0.82-0.99), and ALU (OR=1.56, 95% CI=1.02-2.39). Epimutations in CMM susceptibility genes and in genes involved in response to oxidative damage are associated with the risk of developing CMM or dysplastic nevi. Further studies measuring methylation levels of these genes in prospectively collected samples are warranted to further elucidate their role in the development and progression of CMM. PMID:25026000

Pergoli, Laura; Favero, Chiara; Pfeiffer, Ruth M; Tarantini, Letizia; Calista, Donato; Cavalleri, Tommaso; Angelici, Laura; Consonni, Dario; Bertazzi, Pier A; Pesatori, Angela C; Landi, Maria T; Bollati, Valentina

2014-10-01

427

Toxic effects of butyl elastomers on aerobic methane oxidation  

NASA Astrophysics Data System (ADS)

Large quantities of the potent greenhouse gas methane are liberated into the water column of marine and lacustrine environments where it may be consumed by aerobic methane oxidising bacteria before reaching the atmosphere.The reliable quantification of aerobic methane oxidation (MOx) rates is consequently of paramount importance for estimating methane budgets and to understand the controls on water column methane cycling. A widely used set of methods for measuring MOx rates is based on the incubation of water samples during which the consumption of methane is monitored, for instance with radio-tracer assays. Typically, incubation vessels are sealed with butyl rubber stoppers because these elastomers are essentially impermeable for gases at the relevant time scales. We tested the effect of different stopper materials (unmodified- and halogenated butyl rubber) on MOx activity in environmental samples and in cultures of methane oxidising bacteria. MOx rates in samples sealed with unmodified butyl rubber were > 75% lower compared to parallel incubations with halogenated butyl rubber seals, suggesting inhibiting/toxic effects associated with the use of unmodified butyl elastomers. To further explore the cause of these effects, we analysed aqueous extracts of the different stoppers. Halogenated butyl rubber stoppers appeared to bleed off comparably little amounts of organics. In stark contrast, extracts of unmodified butyl rubber were contaminated with various organic compounds including potential bactericides such as benzyltoluenes, phenylalkanes and benzuothiazoles. We also found tetramethylthiourea, a scavenger of active oxygen species, which may inhibit the MOx pathway.

Niemann, Helge; Steinle, Lea I.; Blees, Jan H.; Krause, Stefan; Bussmann, Ingeborg; Lehmann, Moritz F.; Treude, Tina

2013-04-01

428

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

429

The participation of hydrogen peroxide in methyl jasmonate-induced NH(4)(+) accumulation in rice leaves.  

PubMed

Ammonium is a central intermediate in the nitrogen metabolism of plants. We have previously shown that methyl jasmonate (MJ) not only increases the content of H(2)O(2), but also causes NH(4)(+) accumulation in rice leaves. More recently, H(2)O(2) is thought to constitute a general signal molecule participating in the recognition of and the response to stress factors. In this study, we examined the role of H(2)O(2) as a link between MJ and subsequent NH(4)(+) accumulation in detached rice leaves. MJ treatment resulted in an accumulation of NH(4)(+) in detached rice leaves, which was preceded by a decrease in the activity of glutamine synthetase (GS) and an increase in the specific activities of protease and phenylalanine ammonia-lyase (PAL). GS, PAL, and protease appear to be the enzymes responsible for the accumulation of NH(4)(+) in MJ-treated detached rice leaves. Dimethylthiourea (DMTU), a chemical trap for H(2)O(2), was observed to be effective in inhibiting MJ-induced NH(4)(+) accumulation in detached rice leaves. Scavengers of free radicals (sodium benzoate, SB, and glutathione, GSH), nitric oxide donor (N-tert-butyl-alpha-phenylnitrone, PBN), the inhibitors of NADPH oxidase (diphenyleneiodonium chloride, DPI, and imidazole, IMD), and inhibitors of phosphatidylinositol 3-kinase (wortmannin, WM, and LY 294002, LY), which have previously been shown to prevent MJ-induced H(2)O(2) production in detached rice leaves, inhibited MJ-induced NH(4)(+) accumulation. Similarly, changes in enzymes responsible for NH(4)(+) accumulation induced by MJ were observed to be inhibited by DMTU, SB, GSH, PBN DPI, IMD, WM, or LY. Seedlings of rice cultivar Taichung Native 1 (TN1) are jasmonic acid (JA)-sensitive and those of cultivar Tainung 67 (TNG67) are JA-insensitive. On treatment with JA, H(2)O(2) accumulated in the leaves of TN1 seedlings but not in the leaves of TNG67. Ethylene action inhibitor, silver thiosulfate, was observed to inhibit MJ- and abscisic acid-induced accumulation of NH(4)(+) and changes in enzymes responsible for NH(4)(+) accumulation in detached rice leaves, suggesting that the action of MJ and ABA is ethylene dependent. PMID:17215059

Hung, Kuo Tung; Kao, Ching Huei

2007-11-01

430

Proteome alteration induced by hTERT transfection of human fibroblast cells  

Microsoft Academic Search

BACKGROUND: Telomerase confers cellular immortality by elongating telomeres, thereby circumventing the Hayflick limit. Extended-life-span cells have been generated by transfection with the human telomerase reverse transcriptase (hTERT) gene. hTERT transfected cell lines may be of outstanding interest to monitor the effect of drugs targeting the telomerase activity. The incidence of hTERT gene transfection at the proteome level is a prerequisite

Gabriel D Mazzucchelli; Valérie Gabelica; Nicolas Smargiasso; Maximilien Fléron; Wilson Ashimwe; Frédéric Rosu; Marie-Claire De Pauw-Gillet; Jean-François Riou; Edwin De Pauw

2008-01-01

431

hTERT antagonizes p53-induced apoptosis independently of telomerase activity  

Microsoft Academic Search

The p53 tumor suppressor controls cell growth and survival through transcriptional regulation of gene expression. Previously, we found that the human telomerase reverse transcriptase (hTERT) gene is downregulated by p53. To investigate if hTERT downregulation has a role in p53-dependent apoptosis, we tested if constitutive expression of telomerase could inhibit p53-induced apoptosis. Here we show that constitutive hTERT expression results

Rubaiyat Rahman; Leena Latonen; Klas G Wiman

2005-01-01

432

hTERT promotes the invasion of telomerase-negative tumor cells in vitro.  

PubMed

Telomerase activation is a common feature of most types of human cancers. Although several studies have shown that activation of telomerase might participate in the progression of tumors, the mechanism by which telomerase activation causes the invasion and metastasis of tumors remains unclear. In this study, we transfected a vector containing the full-length cDNA of hTERT into a telomerase-negative osteosarcoma cell line U2OS (hTERT/U2OS). Vacant vector-transfected U2OS cells served as a control (EGFP/U2OS). We then compared the biological and vitodynamic changes in these transfected and untransfected U2OS cells. The hTERT protein was detected in hTERT/U2OS cells by Western blot analysis and immunochemistry assay. The telomere length in hTERT/U2OS cells was longer than that in EGFP/U2OS and untransfected U2OS cells. We also found using vacuum micropipette aspiration that hTERT transfection did not only promote the proliferation of hTERT-transfected U2OS cells but also increased the cellular adhesion capacity to the extracellular matrix. Transwell matrigel assay confirmed an increased invasion ability in hTERT/U2OS cells. These results strongly suggest that hTERT transfection promotes the invasion of telomerase-negative cells. Telomerase-mediated telomere maintenance enables these cells to achieve a fully malignant endpoint, including invasion and metastasis. PMID:19578747

Yu, Song-Tao; Chen, Ling; Wang, Hong-Jin; Tang, Xu-Dong; Fang, Dian-Chun; Yang, Shi-Ming

2009-08-01

433

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

434

76 FR 5696 - Fluazifop-P-butyl; Pesticide Tolerances  

Federal Register 2010, 2011, 2012, 2013

...FRL-8861-1] Fluazifop-P-butyl; Pesticide Tolerances AGENCY: Environmental Protection...Registration Division (7505P), Office of Pesticide Programs, Environmental Protection Agency...agricultural producer, food manufacturer, or pesticide manufacturer. Potentially affected...

2011-02-02

435

Spectrophotometric determination of the dissociation constants of methyl yellow in mixed protic solvents  

Microsoft Academic Search

The concentration dissociation constants (pKa) of methyl yellow, MY (H+In) in mixed aqueous solvents of methanol, ethanol, iso-propanol, tert-butanol have been accurately determined from spectrophotometric measurements at 25°C and a constant ionic strength of 0.1 mol l?1. It has been shown that in these solvents, the pKa values decrease with increasing composition of the organic co-solvent. A linear relationship between

Jing Fan; Xuejing Shen; Jianji Wang

1999-01-01

436

Room Temperature Aging Study of Butyl O-rings  

Microsoft Academic Search

During testing under the Enhanced Surveillance Campaign in 2001, preliminary data detected a previously unknown and potentially serious concern with recently procured butyl o-rings. All butyl o-rings molded from a proprietary formulation throughout the period circa 1999 through 2001 had less than a full cure. Tests showed that sealing force values for these suspect o-rings were much lower than expected

Mark Wilson

2009-01-01

437

OXIDATION OF PHENOLIC ANTIOXIDANTS IN A RIVER SYSTEM  

EPA Science Inventory

The phenolic antioxidants are important commercial organic chemicals. Their environmental fate is of significance because of their abundance and usage patterns. This paper reports on the fates of 2,6-di-tert-butylphenol and the methyl and octadecyl esters of 3-(3,5-di-tert-butyl-...

438

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...

439

The hTERT protein as a marker for malignancy in meningiomas.  

PubMed

The meningioma evolution remains problematic as 6 to 19% relapse after total resection. We have no criterion or marker to predict with certainty the tumour behaviour, and the WHO grading system is to a certain degree controversial. Telomerase expression seems to play an active role in conferring to the tumour cell indefinite life span. Telomerase activity has been documented via TRAP protocol and telomerase messenger expression (hTERT mRNA). In meningiomas the protein hTERT itself has not been studied directly. Thirty tumour samples of meningiomas operated in our Neurosurgical Department are reviewed with a mean follow-up of 4 years. Specifically hTERT protein, resection type, proliferation markers (Ki-67), and recurrences are evaluated. MRI is used for recurrence controls. Seven samples appeared to be hTERT-positive and all seven showed recurrence. Four patients had undergone a subtotal resection (STR). Among them two were hTERT-positive; only these showed recurrence and malignancy. Of the five macroscopically total resections (MTR), two were initially histologically benign and progressed to malignancy. A strong correlation was found between hTERT and recurrences (coefficient=0.989; p=0,01) with the Spearman's rho test, and weaker one between the Ki-67 and hTER (coefficient=0.672; p<0.0001). The hTERT staining revealed the presence of the hTERT protein not only in their nucleoli but sometime outside as nuclear speckles. The presence of nucleolar or subnuclear hTERT is directly correlated to recurrence and progression towards malignancy. Relocalisation of this protein was confirmed. A distinction is proposed between regrowth, based on normal proliferation (Ki-67) which can accompany subtotal resection and recurrence. Recurrence appears to be pathologic proliferation linked to hTERT presence. The hTERT presence predicts a sombre clinical outcome at mid-term for the individual patient. PMID:15643510

Kalala, J P O; Maes, L; Vandenbroecke, C; de Ridder, L

2005-02-01

440

Effects of butylated hydroxyanisole, butylated hydroxytoluene and tertiary butylhydroquinone on growth and luteoskyrin production by Penicillium islandicum  

Microsoft Academic Search

Butylated hydroxyanisole (BHA), Butylated hydroxytoluene (BHT) and tertiary butylhydroquinone (TBHQ) alone in cultural media\\u000a were tested for the inhibition of growth and luteoskyrin production by two toxigenic strains ofPenicillium islandicum UST-11 andP. islandicum HLT-6. In potato dextrose agar, the concentrations of BHA and TBHQ from 0.2 mg\\/disc, BHT from 5.0 mg\\/disc did affect the\\u000a growth of both tested strains, but

Hshinn-Hshiung Tseng; Tsung-Che Tseng

1995-01-01

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