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...

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...

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...

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...

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

EPA Science Inventory

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

Treatment Of Groundwater Contaminated With PAHs, Gasoline Hydrocarbons, And Methyl Tert-Butyl Ether In A Laboratory Biomass-Retaining Bioreactor

EPA Science Inventory

In this study, we investigated the treatability of co-mingled groundwater contaminated with polycyclic aromatic hydrocarbons (PAHs), gasoline hydrocarbons, and methyl tert-butyl ether (MtBE) using an ex-situ aerobic biotreatment system. The PAHs of interest were nap...

Overview of technologies for removal of methyl tert-butyl ether (MTBE) from water.

PubMed

Levchuk, Irina; Bhatnagar, Amit; Sillanpää, Mika

2014-04-01

Wide use of methyl tert-butyl ether (MTBE) as fuel oxygenates leads to worldwide environment contamination with this compound basically due to fuel leaks from storage or pipelines. Presence of MTBE in drinking water is of high environmental and social concern. Existing methods for MTBE removal from water have a number of limitations which can be possibly overcome in the future with use of emerging technologies. This work aims to provide an updated overview of recent developments in technologies for MTBE removal from water. Copyright © 2014. Published by Elsevier B.V.

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

USGS Publications Warehouse

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

1995-01-01

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

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...

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

USGS Publications Warehouse

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

1999-01-01

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

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...

Lung toxicity and tumor promotion by hydroxylated derivatives of 2,6-di-tert-butyl-4-methylphenol (BHT) and 2-tert-butyl-4-methyl-6-iso-propylphenol: correlation with quinone methide reactivity.

PubMed

Kupfer, Rene; Dwyer-Nield, Lori D; Malkinson, Alvin M; Thompson, John A

2002-08-01

Acute pulmonary toxicity and tumor promotion by the food additive 2,6-di-tert-butyl-4-methylphenol (BHT) in mice are well documented. These effects have been attributed to either of two quinone methides, 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone (BHT-QM) formed through direct oxidation of BHT by pulmonary cytochrome P450 or a quinone methide formed by hydroxylation of a tert-butyl group of BHT (to form BHTOH) followed by oxidation of this metabolite to BHTOH-QM. BHTOH-QM is a more reactive electrophile compared to BHT-QM due to intramolecular interactions of the side-chain hydroxyl with the carbonyl oxygen. To further examine this bioactivation pathway, an analogue of BHTOH was prepared, 2-tert-butyl-6-(1'-hydroxy-1'-methyl)ethyl-4-methylphenol (BPPOH), that is structurally very similar to BHTOH but forms a quinone methide (BPPOH-QM) capable of more efficient intramolecular hydrogen bonding and, therefore, higher electrophilicity than BHTOH-QM. BPPOH-QM was synthesized and its reactivity with water, methanol, and glutathione determined to be >10-fold higher than that of BHTOH-QM. The conversions of BPPOH and BHTOH to quinone methides in lung microsomes from male BALB/cByJ mice were quantitatively similar, but in vivo the former was pneumotoxic at one-half of the dose required for the latter and one-eighth of the dose required for BHT, as determined by increased lung weight:body weight ratios following a single i.p. injection. Similar differences were found in the doses of BHT, BHTOH, or BPPOH required for tumor promotion after a single initiating dose of 3-methylcholanthrene followed by three weekly injections of the phenol. The downregulaton of calpain II, previously shown to accompany lung tumor promotion by BHT and BHTOH, also occurred with BPPOH. The correlation between biologic activities of these phenols and the reactivities of their corresponding quinone methides provides additional support for the role of BHTOH-QM as the principal metabolite

27 CFR 21.101 - tert-Butyl alcohol.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false tert-Butyl alcohol. 21.101....101 tert-Butyl alcohol. (a) Acidity (as acetic acid). 0.003 percent by weight maximum. (b) Color. Colorless. (c) Distillation range. When 100 ml of tertiary butyl alcohol are distilled, none should distill...

27 CFR 21.101 - tert-Butyl alcohol.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false tert-Butyl alcohol. 21.101....101 tert-Butyl alcohol. (a) Acidity (as acetic acid). 0.003 percent by weight maximum. (b) Color. Colorless. (c) Distillation range. When 100 ml of tertiary butyl alcohol are distilled, none should distill...

Reaction of alkylphenols with acetals. II. Reaction of 4methyl-2-tert-butylphenol with dimethoxymethane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Starikova, O.F.; Gurvich, Y.A.; Kumok, S.T.

1985-12-20

The authors explain how di(hydroxydialkylaryl) derivatives of methane play an important role in the inhibition of oxidation processes in polymers, oils, fuels, and other organic materials. They investigate the reaction of 4-methyl-2-tert-butylphenol with dimethoxymethane, and established that the reaction mass contained 2-methoxymethyl-4-6-tert-butylphenol. The formation and the transformations of 2-methoxymethyl-4-methyl-6-tert-butylphenol do not have a significant effect on the synthesis of di(2-hydroxy-5-methyl-3-tert-butylphenyl) methane from 4-methyl-2-tert-butyl-phenol and dimethoxymethane.

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

USGS Publications Warehouse

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

1996-01-01

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

Methyl tert-butyl ether (MTBE) in finished drinking water in Germany.

PubMed

Kolb, Axel; Püttmann, Wilhelm

2006-03-01

In the present study 83 finished drinking water samples from 50 cities in Germany were analyzed for methyl tert-butyl ether (MTBE) content with a detection limit of 10 ng/L. The detection frequency was 46% and the concentrations ranged between 17 and 712 ng/L. Highest concentrations were found in the community water systems (CWSs) of Leuna and Spergau in Saxony-Anhalt. These CWSs are supplied with water possibly affected by MTBE contaminated groundwater. MTBE was detected at concentrations lower than 100 ng/L in drinking water supplied by CWSs using bank filtered water from Rhine and Main Rivers. The results from Leuna and Spergau show that large groundwater contaminations in the vicinity of CWSs pose the highest risk for MTBE contamination in drinking water. CWSs using bank filtered water from Rhine and Main Rivers are susceptible to low MTBE contaminations in finished drinking water. All measured MTBE concentrations were below proposed limit values for drinking water.

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

PubMed

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

2017-11-01

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

IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) ...

EPA Pesticide Factsheets

The IRIS Toxicological Review of tert-Butyl Alcohol (tert-Butanol) was released for external peer review in June 2017. EPA’s Science Advisory Board’s (SAB) Chemical Assessment Advisory Committee (CAAC) will conduct a peer review of the scientific basis supporting the tert-butanol assessment and release a final report of their review. Information regarding the peer review can be found on the SAB website. EPA is conducting an Integrated Risk Information System (IRIS) health assessment for tert-butanol. The outcome of this project is a Toxicological Review and IRIS Summary for tert-butanol that will be entered into the IRIS database.

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

PubMed

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

2015-04-01

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

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

PubMed

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

2007-09-19

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

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

PubMed

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

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.

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

EPA Science Inventory

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

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

PubMed Central

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

2007-01-01

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

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

PubMed

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

2004-02-01

Microbial consortia obtained from soil samples of gasoline-polluted sites were individually enriched with pentane, hexane, isooctane and toluene. Cometabolism with methyl tert-butyl ether, (MTBE), gave maximum degradation rates of 49, 12, 32 and 0 mg g(-1)protein h(-1), respectively. MTBE was fully degraded even when pentane was completely depleted with a cometabolic coefficient of 1 mgMTBE mg(-1)pentane. The analysis of 16S rDNA from isolated microorganisms in the pentane-adapted consortia showed that microorganisms could be assigned to Pseudomonas. This is the first work reporting the cometabolic mineralization of MTBE by consortium of this genus.

Enhanced cometabolic degradation of methyl tert-butyl ether by a Pseudomonas sp. strain grown on n-pentane

NASA Astrophysics Data System (ADS)

Li, S. S.; Wang, S.; Yan, W.

2016-08-01

When methyl tert-butyl ether (MTBE) is added as oxygenates it increases the octane number and decreases the release of nitric oxide from the incomplete combustion of reformulated gasoline. The extensive use of MTBE allowed it to be detectable as a pollutant in both ground-level and underground water worldwide. The present study focuses on the isolation and characterization of MTB-degrading microorganisms by cometabolism based on the results of growth on different carbon sources. It also focuses on the kinetic analysis and the continuous degradation of MTBE. A bacterial strain WL1 that can grow on both n-alkanes (C5-C8) and aromatics was isolated and named Pseudomonas sp. WL1 according to the 16S rDNA sequencing analysis. Strain WL1 could cometabolically degrade MTBE in the presence of n-alkanes with a desirable degradation rate. Diverse n-alkanes with different lengths of carbon chains showed significant influence on the degradation rate of MTBE and accumulation of tert-butyl alcohol (TBA). When strain WL1 cometabolically degraded MTBE in the presence of n-pentane, higher MTBE-degrading rate and lower TBA-accumulation were observed (Vmax = 38.1 nmol/min/mgprotei, Ks = 6.8 mmol/L). In the continuous degrading experiment, the removal efficiency of MTBE by Pseudomonas sp. WL1 did not show any obvious decrease after five subsequent additions.

IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) ...

EPA Pesticide Factsheets

On April 29, 2016, the Toxicological Review of tert-Butyl Alcohol (tert-Butanol) (Public Comment Draft) was released for public comment. The draft Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and the Executive Office of the President during Step 3 (Interagency Science Consultation) before public release. As part of the IRIS process, all written interagency comments on IRIS assessments will be made publicly available. Accordingly, interagency comments with EPA's response and the interagency science consultation drafts of the IRIS Toxicological Review of tert-Butanol and charge to external peer reviewers are posted on this site. EPA is undertaking a new health assessment for t-butyl alcohol (tert-butanol) for the Integrated Risk Information System (IRIS). The outcome of this project will be a Toxicological Review and IRIS and IRIS Summary of TBA that will be entered on the IRIS database. IRIS is an EPA database containing Agency scientific positions on potential adverse human health effects that may result from chronic (or lifetime) exposure to chemicals in the environment. IRIS contains chemical-specific summaries of qualitative and quantitative health information to evaluate potential public health risks associated with environmental contaminants. The IRIS database is relied on for the development of risk assessments, site-specific environmental decisions, and rule making.

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

EPA Science Inventory

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

IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) (External Review Draft)

EPA Science Inventory

The IRIS Toxicological Review of tert-Butyl Alcohol (tert-Butanol) was released for external peer review in June 2017. EPA’s Science Advisory Board’s (SAB) Chemical Assessment Advisory Committee (CAAC) will conduct a peer review of the scientific basis supporting ...

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

PubMed

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

2003-01-01

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

Effect of benzene, toluene, ethylbenzene, and p-xylene (BTEX) mixture on biodegradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) by pure culture UC1.

PubMed

Pruden, Amy; Suidan, Makram

2004-08-01

The effect of a BTEX mixture on the biodegradation of methyl tert-butyl ether (MTBE) and its degradation intermediate, tert-butyl alcohol (TBA) was investigated in the pure bacterial culture UC1, which has been identified to be a strain of the known MTBE-degrader PM1 based on greater than 99% 16S rDNA similarity. Several degradation studies were carried out on UC1 at three initial concentration levels of MTBE or TBA: 6-7; 15-17; and 40-45 mg/l, both with and without BTEX present cumulatively at about half of the MTBE or TBA molar mass in the system. The BTEX mixture was observed not to affect either the rate or the degradation lag period of MTBE or TBA degradation, except that the TBA degradation rate actually increased when BTEX was present initially in the highest concentration studies. When serving as the sole substrate, the MTBE degradation rate ranged from 48 +/- 1.2 to 200 +/- 7.0 mg(MTBE)/g(dw) h, and the TBA degradation rate from 140 +/- 18 to 530 +/- 70 mg(TBA)/g(dw) h. When present with BTEX, MTBE and TBA rates ranged from 46 +/- 2.2 to 210 +/- 14 and 170 +/- 28 to 780 +/- 43 mg(TBA)/g(dw) h, respectively. In studies where varying concentrations of TBA were present with 5 mg/l MTBE, both compounds were degraded simultaneously with no obvious preference for either substrate. In the highest concentration study of TBA with 5 mg/l MTBE, BTEX was also observed to increase the ultimate rate of TBA degradation. In addition to exploring the affect of BTEX, this study also provides general insight into the metabolism of MTBE and TBA by pure culture UC1.

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

EPA Science Inventory

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

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

NASA Astrophysics Data System (ADS)

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

2010-01-01

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

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

USGS Publications Warehouse

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

1956-01-01

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

tert-Butyl 6-amino-5-cyano-2-(2-meth­oxy­eth­yl)nicotinate

PubMed Central

Chen, Yi-Ning; Zhao, Xing-Dong; Deng, Jie; Li, Qin-Geng

2012-01-01

The title compound, C14H19N3O3, was synthesized by the reaction of 3-meth­oxy­propionitrile, tert-butyl bromo­acetate and eth­oxy­methyl­enemalononitrile. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into chains propagating along the b axis. PMID:22737103

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

PubMed

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

2015-04-01

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

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1.

PubMed

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

2016-09-01

Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA. Investigations of interactions between BTEX and MTBE degradation have not yielded consistent trends, and the molecular mechanisms of BTEX compounds' impact on MTBE degradation are not well understood. We investigated trends in transcription of biodegradation genes in the MTBE-degrading bacterium, Methylibium petroleiphilum PM1 upon exposure to MTBE, TBA, ethylbenzene and benzene as individual compounds or in mixtures. We designed real-time quantitative PCR assays to target functional genes of strain PM1 and provide evidence for induction of genes mdpA (MTBE monooxygenase), mdpJ (TBA hydroxylase) and bmoA (benzene monooxygenase) in response to MTBE, TBA and benzene, respectively. Delayed induction of mdpA and mdpJ transcription occurred with mixtures of benzene and MTBE or TBA, respectively. bmoA transcription was similar in the presence of MTBE or TBA with benzene as in their absence. Our results also indicate that ethylbenzene, previously proposed as an inhibitor of MTBE degradation in some bacteria, inhibits transcription of mdpA, mdpJ and bmoAgenes in strain PM1.

Effect of benzene and ethylbenzene on the transcription of methyl-tert-butyl ether degradation genes of Methylibium petroleiphilum PM1

PubMed Central

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

2016-01-01

Methyl-tert-butyl ether (MTBE) and its degradation by-product, tert-butyl alcohol (TBA), are widespread contaminants detected frequently in groundwater in California. Since MTBE was used as a fuel oxygenate for almost two decades, leaking underground fuel storage tanks are an important source of contamination. Gasoline components such as BTEX (benzene, toluene, ethylbenzene and xylenes) are often present in mixtures with MTBE and TBA. Investigations of interactions between BTEX and MTBE degradation have not yielded consistent trends, and the molecular mechanisms of BTEX compounds’ impact on MTBE degradation are not well understood. We investigated trends in transcription of biodegradation genes in the MTBE-degrading bacterium, Methylibium petroleiphilum PM1 upon exposure to MTBE, TBA, ethylbenzene and benzene as individual compounds or in mixtures. We designed real-time quantitative PCR assays to target functional genes of strain PM1 and provide evidence for induction of genes mdpA (MTBE monooxygenase), mdpJ (TBA hydroxylase) and bmoA (benzene monooxygenase) in response to MTBE, TBA and benzene, respectively. Delayed induction of mdpA and mdpJ transcription occurred with mixtures of benzene and MTBE or TBA, respectively. bmoA transcription was similar in the presence of MTBE or TBA with benzene as in their absence. Our results also indicate that ethylbenzene, previously proposed as an inhibitor of MTBE degradation in some bacteria, inhibits transcription of mdpA, mdpJ and bmoAgenes in strain PM1. PMID:27450417

N-tert-Butyl-N'-(5,7-dimethyl-1,8-naphthyridin-2-yl)urea.

PubMed

Lüning, U; Kühl, C; Bolte, M

2001-08-01

The title compound, C(15)H(20)N(4)O, has been synthesized as an AADD recognition unit for quadruple hydrogen bonds. All non-H atoms of the molecule apart from two methyl groups of the tert-butyl group lie in a common plane. An intramolecular hydrogen bond is formed connecting two N atoms. In the solid state, the title compound crystallizes as a centrosymmetric dimer connected by N-H...O=C interactions with an N...O distance of 2.824 (2) A.

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

PubMed

Farobie, Obie; Matsumura, Yukihiko

2015-09-01

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

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

PubMed

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

2007-06-01

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

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

PubMed

Roslev, Peter; Lentz, Trine; Hesselsoe, Martin

2015-02-01

The inhibitory effects of the fuel additive methyl tert-butyl ether (MTBE) and potential degradation products tert-butanol (TBA) and formaldehyde was examined using mixed microbial biomass, and six strains of bioluminescent bacteria and yeast. The purpose was to assess microbial toxicity with quantitative bioluminescent and fluorescent endpoints, and to identify sensitive proxies suitable for monitoring MTBE contamination. Bioluminescent Aliivibrio fischeri DSM 7151 (formerly Vibrio fischeri) appeared highly sensitive to MTBE exposure, and was a superior test organisms compared to lux-tagged Escherichia coli DH5α, Pseudomonas fluorescens DF57-40E7 and Saccharomyces cerevisiae BLYR. EC10 and EC50 for acute MTBE toxicity in A. fischeri were 1.1 and 10.9 mg L(-1), respectively. Long term (24h) MTBE exposure resulted in EC10 values of 0.01 mg L(-1). TBA was significantly less toxic with EC10 and EC50 for acute and chronic toxicity >1000 mg L(-1). Inhibition of bioluminescence was generally a more sensitive endpoint for MTBE toxicity than measuring intracellular ATP levels and heterotrophic CO2 assimilation. A weak estrogenic response was detected for MTBE at concentrations ⩾ 3.7 g L(-1) using an estrogen inducible bioluminescent yeast strain (S. cerevisiae BLYES). Microbial hydrolytic enzyme activity in groundwater was affected by MTBE with EC10 values of 0.5-787 mg L(-1), and EC50 values of 59-3073 for alkaline phosphatase, arylsulfatase, beta-1,4-glucanase, N-acetyl-beta-d-glucosaminidase, and leucine-aminopeptidase. Microbial alkaline phosphatase and beta-1,4-glucanase activity were most sensitive to MTBE exposure with EC50 ⩽ 64.8 mg L(-1). The study suggests that bioassays with luminescent A. fischeri, and fluorescent assays targeting hydrolytic enzyme activity are good candidates for monitoring microbial MTBE toxicity in contaminated water. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2014-06-01

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

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

PubMed Central

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

2012-01-01

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

Reactivities of Substituted α-Phenyl-N-tert-butyl Nitrones

PubMed Central

2015-01-01

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

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

PubMed Central

Fester, Thomas

2013-01-01

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

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

EPA Science Inventory

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

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

NASA Astrophysics Data System (ADS)

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

2014-01-01

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

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

PubMed

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

2009-06-15

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

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

USGS Publications Warehouse

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

1959-01-01

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

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

PubMed

Vatani, Hossein; Yazdi, Ali Sarafraz

2014-01-01

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

IRIS Toxicological Review of Tert-Butyl Alcohol (Tert-Butanol) ...

EPA Pesticide Factsheets

EPA is developing an Integrated Risk Information System (IRIS) assessment of tert-butyl Alcohol (tert-butanol) and has released the public comment draft assessment for public comment and external peer review. When final, the assessment will appear on the IRIS database. This draft report is being released for public viewing and comment prior to a public meeting, providing an opportunity for the IRIS Program to engage in early discussions with stakeholders and the public on data that may be used to identify adverse health effects and characterize exposure-response relationships. EPA welcomes all comments on the draft literature search, preliminary evidence tables, and preliminary exposure-response arrays, such as remarks on the following: • the clarity and transparency of the materials; • the approach for identifying pertinent studies; • the selection of studies for data extraction to preliminary evidence tables and exposure-response arrays; • any methodological considerations that could affect the interpretation of or confidence in study results; and • any additional studies published or nearing publication that may provide data for the evaluation of human health hazard or dose-response relationships.

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

PubMed

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

2017-05-01

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

Separation and determination of methyl tert-butyl ether and its degradation products by a laboratory-constructed micro-cryogenic chromatographic oven.

PubMed

Liu, Jiemin; Jiang, Guibin; Zhou, Qunfang; Liu, Jingfu; Wen, Meijuan

2003-10-01

A laboratory-made micro-cryogenic chromatographic oven was mainly improved in size, which was controlled at 6 x 6 x 2.5 cm. A thermoelectric system was used to cool the capillary column instead of the traditional liquid cryogen. A cold block connected to the cryogenic module was directly solidified at room temperature with thermally conductive adhesive so that the uniformity of transferring heat was greatly improved, and the size of the system was reduced. Moreover, this system was inexpensive and convenient for both operation and control. The newly developed device coupled with headspace solid-phase microextraction (SPME) was successfully applied to the determination of methyl tert-butyl ether (MTBE) and its degradation products. During the analysis procedure, a 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used to extract MTBE and its degradation products. The extraction was controlled at 50 degrees C for 30 min and the NaCl content in the sample was maintained at 35%. The limits of detection (LODs) ranged from 0.006 microg mL(-1) (for MTBE) to 0.206 microg mL(-1) (for methyl acetate) and the relative standard deviations (RSD%) were below 4%. The spiked recoveries for the developed method were evaluated using various water samples as a matrix.

Synthesis, structural characterization and theoretical studies of a new Schiff base 4-(((3-(tert-Butyl)-(1-phenyl)pyrazol-5-yl) imino)methyl)phenol

NASA Astrophysics Data System (ADS)

Cuenú, Fernando; Londoño-Salazar, Jennifer; Torres, John Eduard; Abonia, Rodrigo; D'Vries, Richard F.

2018-01-01

4-(((3-(tert-Butyl)-(1-phenyl)pyrazol-5-yl)imino)methyl)phenol (4-OHFPz) was synthesized and characterized by FT-IR, MS, NMR, and single-crystal X-ray diffraction. Optimization of molecular geometry, vibrational frequencies, and chemical shifts were calculated by using the methods of density functional theory (DFT) with B3LYP and B3PW91 as functionals and Hartree-Fock with 6-311G++(d,p) as basis set using the GAUSSIAN 09 program package. With the VEDA 4 software, the vibrational frequencies were assigned in terms of the potential energy distribution (PED). The equilibrium geometries calculated by all methods were compared with X-ray diffraction results, indicating that the theoretical results matches well with the experimental ones. The data obtained from the vibrational analysis and the calculated NMR are consistent with the experimental spectra.

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

ERIC Educational Resources Information Center

Hairfield, E. M.; And Others

1985-01-01

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

40 CFR 721.4925 - Methyl n-butyl ketone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Methyl n-butyl ketone. 721.4925... Substances § 721.4925 Methyl n-butyl ketone. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance methyl n-butyl ketone, CAS Number 591-78-6, is subject to reporting...

40 CFR 721.4925 - Methyl n-butyl ketone.

Code of Federal Regulations, 2010 CFR

2010-07-01

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

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

PubMed Central

Hartle, R

1993-01-01

Concerns for atmospheric pollution from auto exhaust have led to the blending of "oxygenates" with motor fuels. The most common oxygenate, methyl tert-butyl ether (MTBE) is currently required within several metropolitan areas (Denver and Phoenix) in the range of 12% of the motor fuel. Amendments to the Clean Air Act may expand this requirement to as many as 44 other areas of the United States in the near future. In consideration of the magnitude of potential uncontrolled exposures from its extensive use and a related concern involving the potential influence of MTBE blending on exposures to other constituents of gasoline (particularly benzene), an evaluation of exposures among service station attendants and operators was undertaken at the request, and in cooperation with, the American Petroleum Institute during the latter part of 1990. For application of the survey results to a broad audience, three categories or types of service stations were identified with regard to MTBE use and exposure potential: a) service stations that do not use MTBE or use it only as an octane enhancer, b) service stations with seasonal requirements to use 12-15% MTBE (the Denver, Colorado, and Phoenix, Arizona, metropolitan areas), and c) service stations equipped with stage II (active) vapor recovery systems (several coastal areas, most notably Southern California). At the two sampled service stations that use only minimal amounts of MTBE (less than 1%), only 1 of 32 personal breathing zone (PBZ) samples from attendants was above the analytical limit of detection, reported at 0.16 ppm. The geometric mean concentration of benzene among this same population (n = 32) was 0.04 ppm.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8020445

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

PubMed

Hartle, R

1993-12-01

Concerns for atmospheric pollution from auto exhaust have led to the blending of "oxygenates" with motor fuels. The most common oxygenate, methyl tert-butyl ether (MTBE) is currently required within several metropolitan areas (Denver and Phoenix) in the range of 12% of the motor fuel. Amendments to the Clean Air Act may expand this requirement to as many as 44 other areas of the United States in the near future. In consideration of the magnitude of potential uncontrolled exposures from its extensive use and a related concern involving the potential influence of MTBE blending on exposures to other constituents of gasoline (particularly benzene), an evaluation of exposures among service station attendants and operators was undertaken at the request, and in cooperation with, the American Petroleum Institute during the latter part of 1990. For application of the survey results to a broad audience, three categories or types of service stations were identified with regard to MTBE use and exposure potential: a) service stations that do not use MTBE or use it only as an octane enhancer, b) service stations with seasonal requirements to use 12-15% MTBE (the Denver, Colorado, and Phoenix, Arizona, metropolitan areas), and c) service stations equipped with stage II (active) vapor recovery systems (several coastal areas, most notably Southern California). At the two sampled service stations that use only minimal amounts of MTBE (less than 1%), only 1 of 32 personal breathing zone (PBZ) samples from attendants was above the analytical limit of detection, reported at 0.16 ppm. The geometric mean concentration of benzene among this same population (n = 32) was 0.04 ppm.(ABSTRACT TRUNCATED AT 250 WORDS)

Microbial community composition during anaerobic mineralization of tert-butyl alcohol (TBA) in fuel-contaminated aquifer material.

PubMed

Wei, Na; Finneran, Kevin T

2011-04-01

Anaerobic mineralization of tert-butyl alcohol (TBA) and methyl tert-butyl ether (MTBE) were studied in sediment incubations prepared with fuel-contaminated aquifer material. Microbial community compositions in all incubations were characterized by amplified ribosomal DNA restriction analysis (ARDRA). The aquifer material mineralized 42.3±9.9% of [U-(14)C]-TBA to 14CO2 without electron acceptor amendment. Fe(III), sulfate, and Fe(III) plus anthraquinone-2,6-disulfonate addition also promoted U-[14C]-TBA mineralization at levels similar to those of the unamended controls. Nitrate actually inhibited TBA mineralization relative to unamended controls. In contrast to TBA, [U-(14)C]-MTBE was not significantly mineralized in 400 days regardless of electron acceptor amendment. Microbial community analysis indicated that the abundance of one dominant clone group correlated closely with anaerobic TBA mineralization. The clone was phylogenetically distinct from known aerobic TBA-degrading microorganisms, Fe(III)- or sulfate-reducing bacteria. It was most closely associated with organisms belonging to the alphaproteobacteria. Microbial communities were different in MTBE and TBA amended incubations. Shannon indices and Simpson indices (statistical community comparison tools) both demonstrated that microbial community diversity decreased in incubations actively mineralizing TBA, with distinct "dominant" clones developing. These data contribute to our understanding of anaerobic microbial transformation of fuel oxygenates in contaminated aquifer material and the organisms that may catalyze the reactions.

Stable carbon and hydrogen isotope analysis of methyl tert-butyl ether and tert-amyl methyl ether by purge and trap-gas chromatography-isotope ratio mass spectrometry: method evaluation and application.

PubMed

Kujawinski, Dorothea M; Stephan, Manuel; Jochmann, Maik A; Krajenke, Karen; Haas, Joe; Schmidt, Torsten C

2010-01-01

In order to monitor the behaviour of contaminants in the aqueous environment effective enrichment techniques often have to be employed due to their low concentrations. In this work a robust and sensitive purge and trap-gas chromatography-isotope ratio mass spectrometry method for carbon and hydrogen isotope analysis of fuel oxygenates in water is presented. The method evaluation included the determination of method detection limits, accuracy and reproducibility of deltaD and delta(13)C values. Lowest concentrations at which reliable delta(13)C values could be determined were 5 microg L(-1) and 28 microg L(-1) for TAME and MTBE, respectively. Stable deltaD values for MTBE and TAME could be achieved for concentrations as low as 25 and 50 microg L(-1). Good long-term reproducibility of delta(13)C and deltaD values was obtained for all target compounds. But deltaD values varying more than 5 per thousand were observed using different thermal conversion tubes. Thus, a correction of deltaD values in the analysis of groundwater samples was necessary to guarantee comparability of the results. The applicability of this method was shown by the analysis of groundwater samples from a gasoline contaminated site. By two dimensional isotope analysis two locations within this site were identified at which anaerobic and aerobic degradation of methyl tert-butyl ether occurred.

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

PubMed

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

2015-07-20

Experimental evidence for the presence of tert-butyl cations, which are important intermediates in acid-catalyzed heterogeneous reactions, on solid acids has still not been provided to date. By combining density functional theory (DFT) calculations with (1)H/(13)C magic-angle-spinning NMR spectroscopy, the tert-butyl cation was successfully identified on zeolite H-ZSM-5 upon conversion of isobutene by capturing this intermediate with ammonia. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed Central

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

2017-01-01

Methyl tert-butyl ether (MTBE) has been used as a common gasoline additive worldwide since the late twentieth century, and it has become the most frequently detected groundwater pollutant in many countries. This study aimed to synthesize a novel microbial carrier to improve its adsorptive capacity for MTBE and biofilm formation, compared to the traditional granular activated carbon (GAC). A polypyrrole (PPy)-modified GAC composite (PPy/GAC) was synthesized, and characterized by Fourier transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) surface area analysis. The adsorption behaviors of MTBE were well described by the pseudo-second-order and Langmuir isotherm models. Furthermore, three biofilm reactors were established with PPy/GAC, PPy, and GAC as the carriers, respectively, and the degradation of MTBE under continuous flow was investigated. Compared to the biofilm reactors with PPy or GAC (which both broke after a period of operation), the PPy/GAC biofilm column produced stable effluents under variable treatment conditions with a long-term effluent MTBE concentration <20 μg/L. Pseudomonas aeruginosa and Acinetobacter pittii may be the predominant bacteria responsible for MTBE degradation in these biofilm reactors. PMID:28125030

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

USGS Publications Warehouse

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

2001-01-01

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

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

USGS Publications Warehouse

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

2008-01-01

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

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

PubMed

Ayotte, Joseph D; Argue, Denise M; McGarry, Frederick J

2005-01-01

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

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

PubMed Central

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

2009-01-01

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

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

PubMed Central

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

2012-01-01

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

Vibrational and reorientationl relaxation in liquid tert-butyl bromide and tert-butyl bromide- d9

NASA Astrophysics Data System (ADS)

Szostak, R.; Hawranek, J. P.

1992-12-01

The vibrational and reorientational correlation functions of the ν s(CBr) mode in liquid tert-butyl bromide (TBBr) and in its deuterated analogue (TBBr- d9) were determined from Raman bandshapes. The Kubo product δτ m obtained by fitting the Rothschild equation to experimental data amounts to 0.36-0.45 for the studied bands, which indicates a fairly fast modulation regime in these systems. The approximation of experimental rotational correlation functions with the help of the J-diffusion model yields values of 0.11-0.12ps for the angular momentum correlation time. The second-order rotational correlation times (1.7-2.0ps) agree well with the NMR results of D.W. Aksnes, K. Ramstad and O.P. Björlykke, Magn. Reson. Chem., 25 (1987) 1063. Selected bandshape parameters for δ(CCC) in both compounds, ϱ(CH 3) in TBBr and ν s(CC) in TBBR- d9 were also quoted.

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

Code of Federal Regulations, 2010 CFR

2010-07-01

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

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane...

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Butyl acrylate, polymer with... acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane. (a... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane...

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

PubMed

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

2006-05-01

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

Emulsion Polymerization of Butyl Acrylate: Spin Trapping and EPR Study

NASA Technical Reports Server (NTRS)

Kim, S.; Westmoreland, D.

1994-01-01

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

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

PubMed

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

2017-02-07

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

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

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Butyl acrylate, polymer with... NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.6920 Butyl... butyl acrylate, polymer with substituted methyl styrene, methyl methacrylate, and substituted silane...

27 CFR 21.118 - Methyl n-butyl ketone.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Methyl n-butyl ketone. 21.118 Section 21.118 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....118 Methyl n-butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color...

27 CFR 21.118 - Methyl n-butyl ketone.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Methyl n-butyl ketone. 21.118 Section 21.118 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....118 Methyl n-butyl ketone. (a) Acidity (as acetic acid). 0.02 percent by weight, maximum. (b) Color...

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

PubMed Central

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

2007-01-01

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

Trends in methyl tert-butyl ether concentrations in private wells in southeast New Hampshire: 2005 to 2015

USGS Publications Warehouse

Flanagan, Sarah; Levitt, Joseph; Ayotte, Joseph

2017-01-01

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

Di-tert-butyl-chlorido(N,N-dibenzyl-dithio-carbamato)tin(IV).

PubMed

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R T

2011-02-26

The Sn(IV) atom in the title diorganotin dithio-carbamate, [Sn(C(4)H(9))(2)(C(15)H(14)NS(2))Cl], is penta-coordinated by an asymmetrically coordinating dithio-carbamate ligand, a Cl atom and two C atoms of the Sn-bound tert-butyl groups. The resulting C(2)ClS(2) donor set defines a coordination geometry inter-mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former.

Allele-specific DNA methylation and its interplay with repressive histone marks at promoter-mutant TERT genes

PubMed Central

Stern, Josh Lewis; Paucek, Richard D.; Huang, Franklin W.; Ghandi, Mahmoud; Nwumeh, Ronald; Costello, James C.; Cech, Thomas R.

2017-01-01

SUMMARY A mutation in the promoter of the Telomerase Reverse Transcriptase (TERT) gene is the most frequent noncoding mutation in cancer. The mutation drives unusual monoallelic expression of TERT, allowing immortalization. Here we find that DNA methylation of the TERT CpG Island (CGI) is also allele-specific in multiple cancers. The expressed allele is hypomethylated, which is opposite to cancers without TERT promoter mutations. The continued presence of Polycomb repressive complex 2 (PRC2) on the inactive allele suggests that histone marks of repressed chromatin may be causally linked to high DNA methylation. Consistent with this hypothesis, TERT promoter DNA containing 5-methyl-CpG has much increased affinity for PRC2 in vitro. Thus, CpG methylation and histone marks appear to collaborate to maintain the two TERT alleles in different epigenetic states in TERT promoter-mutant cancers. Finally, in several cancers DNA methylation levels at the TERT CGI correlate with altered patient survival. PMID:29281820

Optimization of headspace solid-phase microextraction by means of an experimental design for the determination of methyl tert.-butyl ether in water by gas chromatography-flame ionization detection.

PubMed

Dron, Julien; Garcia, Rosa; Millán, Esmeralda

2002-07-19

A procedure for determination of methyl tert.-butyl ether (MTBE) in water by headspace solid-phase microextraction (HS-SPME) has been developed. The analysis was carried out by gas chromatography with flame ionization detection. The extraction procedure, using a 65-microm poly(dimethylsiloxane)-divinylbenzene SPME fiber, was optimized following experimental design. A fractional factorial design for screening and a central composite design for optimizing the significant variables were applied. Extraction temperature and sodium chloride concentration were significant variables, and 20 degrees C and 300 g/l were, respectively chosen for the best extraction response. With these conditions, an extraction time of 5 min was sufficient to extract MTBE. The calibration linear range for MTBE was 5-500 microg/l and the detection limit 0.45 microg/l. The relative standard deviation, for seven replicates of 250 microg/l MTBE in water, was 6.3%.

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

PubMed

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

2013-09-01

Two deep frozen persons, a female and a male, were found dead in a car. There had been an explosive fire inside the car which had extinguished itself. On the floor inside the car were large pools of liquid which smelled of gasoline. The autopsy findings and routine toxicological analyses could not explain the cause of death. Carboxyhemoglobin levels in the blood samples were <10%. Analysis with a headspace gas chromatography revealed methyl tert-butyl ether (MTBE) concentrations of 185 mg/L (female victim) and 115 mg/L (male victim) in peripheral blood. The urine MTBE concentrations were 150 mg/L and 256 mg/L, respectively. MTBE is a synthetic chemical which is added to gasoline as a fuel oxygenate. Gasoline poisoning is likely to be the cause of the death in these two cases, and MTBE can be a suitable marker of gasoline exposure, when other volatile components have vaporized. © 2013 American Academy of Forensic Sciences.

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

PubMed

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

2008-04-01

Tert-butyl alcohol (TBA) is a metabolite of methyl tert-butyl ether and is itself possibly a fuel oxygenate. The goals of this study were to enrich and characterize TBA-degrading micro-organism(s) from a granular activated carbon (GAC) unit currently treating TBA. The results reported herein describe the first aerobic, TBA-degrading cultures derived from GAC. Strains KR1 and YZ1 were enriched from a GAC sample in a bicarbonate-buffered freshwater medium. TBA was degraded to 10% of the initial concentration (2-5 mM) within 5 days after initial inoculation and was continuously degraded within 1 day of each re-amendment. Resting cell suspensions mineralized 70 and 60% of the TBA within 24 h for KR1 and YZ1, respectively. Performance optimization with resting cells was conducted to investigate kinetics and the extent of TBA degradation as influenced by oxygen, pH and temperature. The most favorable temperature was 37 degrees C; however, TBA was degraded from 4 to 60 degrees C, indicating that the culture will sufficiently treat groundwater without heating. This is also the first report of psychrotolerant or thermotolerant TBA biodegradation. The pH range for TBA degradation ran from 5.0 to 9.0. Phylogenetic data using a partial 16S rRNA gene sequence (570 bases) suggest that the primary members of KR1 and YZ1 include uncharacterized organisms within the genera Hydrogenophaga, Caulobacter, and Pannonibacter.

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

PubMed

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

2013-10-01

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

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

PubMed

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

2017-06-28

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

Allele-Specific DNA Methylation and Its Interplay with Repressive Histone Marks at Promoter-Mutant TERT Genes.

PubMed

Stern, Josh Lewis; Paucek, Richard D; Huang, Franklin W; Ghandi, Mahmoud; Nwumeh, Ronald; Costello, James C; Cech, Thomas R

2017-12-26

A mutation in the promoter of the Telomerase Reverse Transcriptase (TERT) gene is the most frequent noncoding mutation in cancer. The mutation drives unusual monoallelic expression of TERT, allowing immortalization. Here, we find that DNA methylation of the TERT CpG island (CGI) is also allele-specific in multiple cancers. The expressed allele is hypomethylated, which is opposite to cancers without TERT promoter mutations. The continued presence of Polycomb repressive complex 2 (PRC2) on the inactive allele suggests that histone marks of repressed chromatin may be causally linked to high DNA methylation. Consistent with this hypothesis, TERT promoter DNA containing 5-methyl-CpG has much increased affinity for PRC2 in vitro. Thus, CpG methylation and histone marks appear to collaborate to maintain the two TERT alleles in different epigenetic states in TERT promoter mutant cancers. Finally, in several cancers, DNA methylation levels at the TERT CGI correlate with altered patient survival. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Synthesis and dynamic NMR study of ketenimines derived from tert-butyl isocyanide, alkyl 2-arylamino-2-oxo-acetates, and dialkyl acetylenedicarboxylates.

PubMed

Yavari, Issa; Nasiri, Farough; Djahaniani, Horieh

2004-01-01

The adduct produced in the reaction between tert-butyl isocyanide and dialkyl acetylenedicarboxylates was trapped by alkyl 2-arylamino-2-oxo-acetates. When the aryl group is 2-methyl-6-nitrophenyl or 2,6-di-isopropylphenyl, the product exists as two stable rotamers at room temperature as a result of restricted rotation around the Ar-N single bond. When the aryl group is 1-naphthyl or 8-quinolinyl, dynamic NMR effects are observed in the 1H NMR spectra. The calculated free-energy of activation for interconversion of the rotational isomers in 1-naphthyl and 8-quinolinyl derivatives amounts to about 99+/-2 and 68.5+/-2 kJ mol(-1), respectively.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karsanov, I.V.; Ivakhnenko, E.P.; Khandkarova, V.S.

1987-07-10

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-saltmore » (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.« less

Synchrotron Photoionization Investigation of the Oxidation of Ethyl tert-Butyl Ether.

PubMed

Winfough, Matthew; Yao, Rong; Ng, Martin; Catani, Katherine; Meloni, Giovanni

2017-02-23

The oxidation of ethyl tert-butyl ether (ETBE), a widely used fuel oxygenated additive, is investigated using Cl atoms as initiators in the presence of oxygen. The reaction is carried out at 293, 550, and 700 K. Reaction products are probed by a multiplexed chemical kinetics photoionization mass spectrometer coupled with the synchrotron radiation produced at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory. Products are identified on the basis of mass-to-charge ratio, ionization energies, and shape of photoionization spectra. Reaction pathways are proposed together with detected primary products.

(N-Benzyl-N-ethyl-dithio-carbamato)di-tert-butyl-chloridotin(IV).

PubMed

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R T

2011-02-26

The Sn(IV) atom in the title diorganotin dithio-carbamate, [Sn(C(4)H(9))(2)Cl(C(10)H(12)NS(2))], is penta-coordinated by an asymmetrically coordinating dithio-carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C(2)ClS(2) donor set defines a coordination geometry inter-mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C-H⋯π contacts link centrosymmetrically related mol-ecules into dimeric aggregates.

A series of (E)-5-(arylideneamino)-1-tert-butyl-1H-pyrrole-3-carbonitriles and their reduction products to secondary amines: syntheses and X-ray structural studies.

PubMed

Macías, Mario A; Castillo, Juan Carlos; Portilla, Jaime

2018-01-01

An efficent access to a series of N-(pyrrol-2-yl)amines, namely (E)-1-tert-butyl-5-[(4-chlorobenzylidene)amino]-1H-pyrrole-3-carbonitrile, C 16 H 16 ClN 3 , (7a), (E)-1-tert-butyl-5-[(2,4-dichlorobenzylidene)amino]-1H-pyrrole-3-carbonitrile, C 16 H 15 Cl 2 N 3 , (7b), (E)-1-tert-butyl-5-[(pyridin-4-ylmethylene)amino]-1H-pyrrole-3-carbonitrile, C 15 H 16 N 4 , (7c), 1-tert-butyl-5-[(4-chlorobenzyl)amino]-1H-pyrrole-3-carbonitrile, C 16 H 18 ClN 3 , (8a), and 1-tert-butyl-5-[(2,4-dichlorobenzyl)amino]-1H-pyrrole-3-carbonitrile, C 16 H 17 Cl 2 N 3 , (8b), by a two-step synthesis sequence (solvent-free condensation and reduction) starting from 5-amino-1-tert-butyl-1H-pyrrole-3-carbonitrile is described. The syntheses proceed via isolated N-(pyrrol-2-yl)imines, which are also key synthetic intermediates of other valuable compounds. The crystal structures of the reduced compounds showed a reduction in the symmetry compared with the corresponding precursors, viz. Pbcm to P-1 from compound (7a) to (8a) and P2 1 /c to P-1 from compound (7b) to (8b), probably due to a severe change in the molecular conformations, resulting in the loss of planarity observed in the nonreduced compounds. In all of the crystals, the supramolecular assembly is controlled mainly by strong (N,C)-H...N hydrogen bonds. However, in the case of (7a)-(7c), C-H...Cl interactions are strong enough to help in the three-dimensional architecture, as observed in Hirshfeld surface maps.

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

PubMed

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

2016-09-01

Among the strategies developed for contaminated groundwater bioremediation, those based on the use of bacteria adhering to inert supports and establishing biofilms have gained great importance in this field. Extractive membrane biofilm reactor (EMBFR) technology offers productive solutions for the removal of volatile and semi-volatile compounds. EMBFR technology is based on the use of extractive semipermeable membranes through which contaminants migrate to the biological compartment in which microorganisms with pollutant biotransformation and/or mineralization capacities can grow, forming an active biofilm on the membrane surface. The objective of this study was to assess the use of three bacterial strains (Paenibacillus sp. SH7 CECT 8558, Agrobacterium sp. MS2 CECT 8557, and Rhodococcus ruber EE6 CECT 8612), as inoculum in a lab-scale EMBFR running for 28 days under aerobic conditions to eliminate methyl tert-butyl ether (MTBE) from water samples. Three different hydraulic retention times (1, 6, and 12 h) were employed. MTBE degradation values were determined daily by a gas GC-MS technique, as well as suspended bacterial growth. The biofilm established by the bacterial strains on the semipermeable membrane was detected by Field-Emission Scanning Electron Microscopy (FESEM) at the end of each experiment. The acute toxicity of the treated effluents and biomedium was determined by Microtox © assay (EC 50 ).The results achieved from the MTBE degradation, biofilm formation, and toxicity analysis indicated that bacterial strains MS2 and EE6 were the best options as selective inoculum, although further research is needed, particularly with regard to their possible use as a mixed culture. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1238-1245, 2016. © 2016 American Institute of Chemical Engineers.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Tingshun, E-mail: tshjiang@mail.ujs.edu.cn; Cheng, Jinlian; Liu, Wangping

2014-10-15

Several zirconium (or aluminum) incorporated mesoporous MCM-48 solid acid catalysts (SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48) were prepared by the impregnation method and their physicochemical properties were characterized by means of XRD, FT-IR, TEM, NH{sub 3}-TPD and N{sub 2} physical adsorption. Also, the catalytic activities of these solid acid catalysts were evaluated by the alkylation of phenol with tert-butyl alcohol. The effect of weight hour space velocity (WHSV), reaction time and reaction temperature on catalytic properties was also studied. The results show that the SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 still have good mesoporous structure and long rangemore » ordering. Compared with the Zr (or Al)–MCM-48 samples, SO{sub 4}{sup 2−}/Zr-MCM-48 and SO{sub 4}{sup 2−}/Al-MCM-48 solid acid catalysts have strong acidity and exhibit high activities in alkylation reaction of phenol with tert-butyl alcohol. The SO{sub 4}{sup 2−}/Zr-MCM-48-25 (molar ratio of Si/Zr=0.04) catalyst was found to be the most promising and gave the highest phenol conversion among all catalysts. A maximum phenol conversion of 91.6% with 4-tert-butyl phenol (4-TBP) selectivity of 81.8% was achieved when the molar ratio of tert-butyl alcohol:phenol is 2:1, reaction time is 2 h, the WHSV is 2 h{sup −1} and the reaction temperature is 140 °C. - Highlights: • Sulfuric acid functional mesoporous solid acid catalysts were prepared via impregnation method. • The alkylation of phenol with tert-butyl alcohol was carried out over these solid acid catalysts. • The catalytic activity of SO{sub 4}{sup 2−}/Zr-MCM-48-25 catalyst is much higher than that of the others. • A maximum phenol conversion of 91.6% was achieved under optimum reaction conditions for SO{sub 4}{sup 2−}/Zr-MCM-48-25.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, C.; Ong, H.Y.; Kok, P.W.

1996-12-31

The primary aim of this study was to determine the extent and levels of exposure to volatile organic compounds (VOCs) from automobile emissions in a group of immigration officers at a busy cross-border checkpoint. A majority (80%) of the workers monitored were exposed to benzene at levels between 0.01 and 0.5 ppm, with only 1.2% exceeding the current Occupational Safety and Health Administration occupational exposure limit of 1 ppm. The geometric mean (GM) concentrations of 8-hr time-weighted average exposure were 0.03 ppm, 0.9 ppm, and 2.46 ppm for methyl-tert-butyl ether (MTBE), benzene, and total hydrocarbons (THC), respectively. The highest time-weightedmore » 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.« less

Di-tert-butyl­chlorido(N,N-dibenzyl­dithio­carbamato)tin(IV)

PubMed Central

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R. T.

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2(C15H14NS2)Cl], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl atom and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. PMID:21522304

Isolation and Characterization of 4-tert-Butylphenol-Utilizing Sphingobium fuliginis Strains from Phragmites australis Rhizosphere Sediment▿ †

PubMed Central

Toyama, Tadashi; Momotani, Naonori; Ogata, Yuka; Miyamori, Yuji; Inoue, Daisuke; Sei, Kazunari; Mori, Kazuhiro; Kikuchi, Shintaro; Ike, Michihiko

2010-01-01

We isolated three Sphingobium fuliginis strains from Phragmites australis rhizosphere sediment that were capable of utilizing 4-tert-butylphenol as a sole carbon and energy source. These strains are the first 4-tert-butylphenol-utilizing bacteria. The strain designated TIK-1 completely degraded 1.0 mM 4-tert-butylphenol in basal salts medium within 12 h, with concomitant cell growth. We identified 4-tert-butylcatechol and 3,3-dimethyl-2-butanone as internal metabolites by gas chromatography-mass spectrometry. When 3-fluorocatechol was used as an inactivator of meta-cleavage enzymes, strain TIK-1 could not degrade 4-tert-butylcatechol and 3,3-dimethyl-2-butanone was not detected. We concluded that metabolism of 4-tert-butylphenol by strain TIK-1 is initiated by hydroxylation to 4-tert-butylcatechol, followed by a meta-cleavage pathway. Growth experiments with 20 other alkylphenols showed that 4-isopropylphenol, 4-sec-butylphenol, and 4-tert-pentylphenol, which have alkyl side chains of three to five carbon atoms with α-quaternary or α-tertiary carbons, supported cell growth but that 4-n-alkylphenols, 4-tert-octylphenol, technical nonylphenol, 2-alkylphenols, and 3-alkylphenols did not. The rate of growth on 4-tert-butylphenol was much higher than that of growth on the other alkylphenols. Degradation experiments with various alkylphenols showed that strain TIK-1 cells grown on 4-tert-butylphenol could degrade 4-alkylphenols with variously sized and branched side chains (ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-heptyl, n-octyl, tert-octyl, n-nonyl, and branched nonyl) via a meta-cleavage pathway but not 2- or 3-alkylphenols. Along with the degradation of these alkylphenols, we detected methyl alkyl ketones that retained the structure of the original alkyl side chains. Strain TIK-1 may be useful in the bioremediation of environments polluted by 4-tert-butylphenol and various other 4-alkylphenols. PMID:20802076

5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetra­methoxy­calix[4]arene dichloro­methane hemisolvate

PubMed Central

Fischer, Conrad; Gruber, Tobias; Seichter, Wilhelm; Schindler, Diana; Weber, Edwin

2008-01-01

In the title compound, C48H64O4·0.5CH2Cl2, both crystallographically independent calixarene mol­ecules display a partial cone conformation. Their crystal packing is stabilized by C—H⋯π contacts involving the meth­oxy groups. The solvent mol­ecule is located inter­stitially between two calixarene units with C—H⋯Cl contacts to meth­oxy and tert-butyl groups. One tert-butyl residue of each calixarene mol­ecule is disordered over two positions (occupancies 0.60/0.40 and 0.63/0.37), resulting in bond distances that deviate from ideal values. The tetra­mer calixarene mol­ecules present models with approximate non-crystallographic Cs symmetry. PMID:21202066

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

PubMed Central

Vlad, Elena; Bozga, Grigore

2012-01-01

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

Unexpected complexes from meta-phenylene bis(tert-butyl nitroxides) and gadolinium(III) 1,1,1,5,5,5-hexafluoropentane-2,4-dionate

NASA Astrophysics Data System (ADS)

Sekine, Hiroyasu; Ishida, Takayuki

2018-01-01

Coordination reaction of the stable ground triplet biradical biphenyl-3,5-diyl bis(tert-butyl nitroxide) and [Gd(hfac)3(H2O)2] unexpectedly gave complexes containing a dimerized diamagnetic ligand via a [3+3] cycloaddition of the benzene rings (hfac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate). To avoid such dimerization, we introduced a bulkier substituent into the ligand; namely, a new ground triplet biradical 5-mesityl-1,3-phenylene bis(tert-butyl nitroxide) was applied to this complexation scheme. However, an unexpected complex was again obtained in a different way, and the magnetic study revealed that the novel ligand involved was diamagnetic. The crystallographic analysis of the product clarified isomerization from the paramagnetic ligand to a diamagnetic N-tert-butylaminoquinone imine N-oxide ligand as a result of disproportionation from two open-shell nitroxide groups to closed-shell groups, an amine and a nitrone. The present paper reports the first structural evidence for a diamagnetic isomer of m-phenylene-bridged bisnitroxde compounds.

Aquatic Life Criteria - Methyl Tertiary-Butyl Ether (MTBE)

EPA Pesticide Factsheets

Information pertaining to the 1999 Acute and Chronic Ambient Aquatic Life Water Quality Criteria for Methyl Tertiary-Butyl Ether (MTBE) for freshwater and salt water. Information includes the safe levels of MTBE that should protect the majority of species.

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

USGS Publications Warehouse

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

2017-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1987-04-23

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

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

PubMed

Kozlosky, John; Bonventre, Josephine; Cooper, Keith

2013-08-01

Methyl-tertiary butyl ether (MTBE), a well known gasoline oxygenate, and US Food and Drug Administration approved gallstone treatment, has been previously shown to specifically target teleost embryonic angiogenesis. The studies reported here were to determine whether similar vascular disrupting effects occur in higher vertebrate models. Rat brain endothelial cells were isolated and allowed to form microcapillary-like tubes on Matrigel. MTBE (0.34-34.0 mm) exposure resulted in a dose-dependent reduction of tube formation, with the LOAEL at 0.34 mm, while MTBE's primary metabolite, tertiary butyl alcohol had no effect on tube formation. HUVECs, a primary cell line representing macrovascular cells, were able to form tubes on Matrigel in the presence of MTBE (1.25-80 mm), but the tubes were narrower than those formed in the absence of MTBE. In a mouse Matrigel plug implantation assay, 34.0 mm MTBE completely inhibited vessel invasion into plugs containing endothelial cell growth supplement (ECGS) compared with control plugs with ECGS alone. When timed-pregnant Fisher 344 rats were gavaged with MTBE (500-1500 mg kg(-1) ) from day 6 of organogenesis through 10 days post-parturition, no organ toxicity or histological changes in pup vasculature were observed. Results of the in vitro cell culture studies show that MTBE is anti-angiogenic at mm concentrations and has potential use as an anti-angiogenic treatment for solid tumors with minimal toxicity. Copyright © 2012 John Wiley & Sons, Ltd.

(N-Benzyl-N-ethyl­dithio­carbamato)di-tert-butyl­chloridotin(IV)

PubMed Central

Abdul Muthalib, Amirah Faizah; Baba, Ibrahim; Mohamed Tahir, Mohamed Ibrahim; Tiekink, Edward R. T.

2011-01-01

The SnIV atom in the title diorganotin dithio­carbamate, [Sn(C4H9)2Cl(C10H12NS2)], is penta­coordinated by an asymmetrically coordinating dithio­carbamate ligand, a Cl and two C atoms of the Sn-bound tert-butyl groups. The resulting C2ClS2 donor set defines a coordination geometry inter­mediate between square pyramidal and trigonal bipyramidal with a slight tendency towards the former. In the crystal structure, C—H⋯π contacts link centrosymmetrically related mol­ecules into dimeric aggregates. PMID:21522295

Synthetic phenolic antioxidants, including butylated hydroxytoluene (BHT), in resin-based dental sealants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei; Kannan, Pranav; Xue, Jingchuan

Resin-based dental sealants (also referred to as pit-and-fissure sealants) have been studied for their contribution to bisphenol A (BPA) exposure in children. Nevertheless, little attention has been paid to the occurrence of other potentially toxic chemicals in dental sealants. In this study, the occurrence of six synthetic phenolic antioxidants (SPAs), including 2,6-di-tert-butyl-4-hydroxytoluene (BHT), 2,6-di-tert-butyl-4-(hydroxyethyl)phenol (BHT-OH), 3,5-di-tert-butyl-4-hydroxy-benzaldehyde (BHT-CHO), 2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzoic acid (BHT-COOH) and 2-tert-butyl-4-methoxyphenol (BHA), was examined in 63 dental sealant products purchased from the U.S. market. BHT was found in all dental sealants at median and maximum concentrations of 56.8 and 1020 µg/g, respectively. The metabolites of BHT andmore » BHA were detected in 39–67% of samples, at concentration ranges of« less

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

PubMed Central

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

2011-01-01

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

Bromine catalyzed conversion of S-tert-butyl groups into versatile and, for self-assembly processes accessible, acetyl-protected thiols.

PubMed

Blaszczyk, Alfred; Elbing, Mark; Mayor, Marcel

2004-10-07

The facile and efficient conversion of a tert-butyl protecting group to an acetyl protecting group for thiols by catalytic amounts of bromine in acetyl chloride and the presence of acetic acid has been developed. The fairly mild reaction conditions are of particular interest for new protecting group strategies for sulfur functionalised target structures. Copyright 2004 The Royal Society of Chemistry

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

PubMed

McNellis, Erik R; Bronner, Christopher; Meyer, Jörg; Weinelt, Martin; Tegeder, Petra; Reuter, Karsten

2010-06-28

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

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...

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

USGS Publications Warehouse

Delzer, Gregory C.; Ivahnenko, Tamara

2003-01-01

The large-scale use of the gasoline oxygenate methyl tert-butyl ether (MTBE), and its high solubility, low soil adsorption, and low biodegradability, has resulted in its detection in ground water and surface water in many places throughout the United States. Studies by numerous researchers, as well as many State and local environmental agencies, have discovered high levels of MTBE in soils and ground water at leaking underground gasoline-storage-tank sites and frequent occurrence of low to intermediate levels of MTBE in reservoirs used for both public water supply and recreational boating.In response to these findings, the American Water Works Association Research Foundation sponsored an investigation of MTBE and other volatile organic compounds (VOCs) in the Nation?s sources of drinking water. The goal of the investigation was to provide additional information on the frequency of occurrence, concentration, and temporal variability of MTBE and other VOCs in source water used by community water systems (CWSs). The investigation was completed in two stages: (1) reviews of available literature and (2) the collection of new data. Two surveys were associated with the collection of new data. The first, termed the Random Survey, employed a statistically stratified design for sampling source water from 954 randomly selected CWSs. The second, which is the focus of this report, is termed the Focused Survey, which included samples collected from 134 CWS source waters, including ground water, reservoirs, lakes, rivers, and streams, that were suspected or known to contain MTBE. The general intent of the Focused Survey was to compare results with the Random Survey and provide an improved understanding of the occurrence, concentration, temporal variability, and anthropogenic factors associated with frequently detected VOCs. Each sample collected was analyzed for 66 VOCs, including MTBE and three other ether gasoline oxygenates (hereafter termed gasoline oxygenates). As part of

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

PubMed

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

2013-07-01

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

Analytical results from ground-water sampling using a direct-push technique at the Dover National Test Site, Dover Air Force Base, Delaware, June-July 2001

USGS Publications Warehouse

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

2004-01-01

A joint study by the Dover National Test Site and the U.S. Geological Survey was conducted from June 27 through July 18, 2001 to determine the spatial distribution of the gasoline oxygenate additive methyl tert-butyl ether and selected water-quality constituents in the surficial aquifer underlying the Dover National Test Site at Dover Air Force Base, Delaware. The study was conducted to support a planned enhanced bio-remediation demonstration and to assist the Dover National Test Site in identifying possible locations for future methyl tert-butyl ether remediation demonstrations. This report presents the analytical results from ground-water samples collected during the direct-push ground-water sampling study. A direct-push drill rig was used to quickly collect 115 ground-water samples over a large area at varying depths. The ground-water samples and associated quality-control samples were analyzed for volatile organic compounds and methyl tert-butyl ether by the Dover National Test Site analytical laboratory. Volatile organic compounds were above the method reporting limits in 59 of the 115 ground-water samples. The concentrations ranged from below detection limits to maximum values of 12.4 micrograms per liter of cis-1,2-dichloroethene, 1.14 micrograms per liter of trichloroethene, 2.65 micrograms per liter of tetrachloroethene, 1,070 micrograms per liter of methyl tert-butyl ether, 4.36 micrograms per liter of benzene, and 1.8 micrograms per liter of toluene. Vinyl chloride, ethylbenzene, p,m-xylene, and o-xylene were not detected in any of the samples collected during this investigation. Methyl tert-butyl ether was detected in 47 of the 115 ground-water samples. The highest methyl tert-butyl ether concentrations were found in the surficial aquifer from -4.6 to 6.4 feet mean sea level, however, methyl tert-butyl ether was detected as deep as -9.5 feet mean sea level. Increased methane concentrations and decreased dissolved oxygen concentrations were found in

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

PubMed

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

2012-01-01

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

The rapid detection of methyl tert-butyl ether (MtBE) in water using a prototype gas sensor system.

PubMed

de Lacy Costello, B P J; Sivanand, P S; Ratcliffe, N M; Reynolds, D M

2005-01-01

The gasoline additive Methyl-tertiary-Butyl Ether (MtBE) is the second most common contaminant of groundwater in the USA and represents an important soil contaminant. This compound has been detected in the groundwater in at least 27 states as a result of leaking underground storage facilities (gasoline storage tanks and pipelines). Since the health effects of MtBE are unclear the potential threat to drinking water supplies is serious. Therefore, the ability to detect MtBE at low levels (ppb) and on-line at high-risk groundwater sites would be highly desirable. This paper reports the use of 'commercial' and metal oxide sensor arrays for the detection of MtBE in drinking and surface waters at low ppb level (microg.L(-1) range). The output responses from some of the sensors were found to correlate well with MtBE concentrations under laboratory conditions.

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

NASA Astrophysics Data System (ADS)

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

2012-06-01

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

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...

A practical and improved synthesis of (3S,5S)-3-[(tert-butyloxycarbonyl)methyl]- 5-[(methanesulfonyloxy)methyl]-2- pyrrolidinone.

PubMed

Yee, Nathan K; Dong, Yong; Kapadia, Suresh R; Song, Jinhua J

2002-11-29

A practical and improved synthesis of (3S,5S)-3-[(tert-butyloxycarbonyl)methyl]-5-[(methanesulfonyloxy)methyl]-2-pyrrolidinone (1) is described. The key transformations involve a highly efficient reaction sequence consisting of ethoxycarbonylation, alkylation, hydrolysis, and decarboxylation to produce compound 10. The process described herein is practical, robust, and cost-effective, and it has been successfully implemented in a pilot plant to produce a multikilogram quantity of mesylate 1.

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

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2'-(1,2-diazenediyl)bis[2-methylbutanenitrile]- and 2,2'-(1,2-diazenediyl)bis[2-methylpropanenitrile]-initiated. 721.10326...

46 CFR 30.25-1 - Cargoes carried in vessels certificated under the rules of this subchapter.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-Amyl methyl ether (Methyl tert-pentyl ether) C Amyl methyl ketone, see Methyl amyl ketone D Animal and... heptyl ketone [C] Butyl methyl ketone, see Methyl butyl ketone n-Butyl propionate C Butyl stearate III... alcohol (all isomers) C Diisobutylene B Diisobutyl ketone D Diisobutyl phthalate B Diisodecyl phthalate...

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

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

USGS Publications Warehouse

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

2001-01-01

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

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

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2â²-(1,2-diazenediyl)bis[2-methylbutanenitrile]- and 2,2â²-(1,2-diazenediyl)bis[2-methylpropanenitrile]-initiated. 721.10326...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate, zinc 2-methyl-2-propenoate (1:2) and zinc 2-propenoate (1:2), 2,2â²-(1,2-diazenediyl)bis[2-methylbutanenitrile]- and 2,2â²-(1,2-diazenediyl)bis[2-methylpropanenitrile]-initiated. 721.10326...

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...

Biodegradation of methyl t-butyl ether by aerobic granules under a cosubstrate condition.

PubMed

Zhang, L L; Chen, J M; Fang, F

2008-03-01

Aerobic granules efficient at degrading methyl tert-butyl ether (MTBE) with ethanol as a cosubstrate were successfully developed in a well-mixed sequencing batch reactor (SBR). Aerobic granules were first observed about 100 days after reactor startup. Treatment efficiency of MTBE in the reactor during stable operation exceeded 99.9%, and effluent MTBE was in the range of 15-50 microg/L. The specific MTBE degradation rate was observed to increase with increasing MTBE initial concentration from 25 to 500 mg/L, which peaked at 22.7 mg MTBE/g (volatile suspended solids).h and declined with further increases in MTBE concentration as substrate inhibition effects became significant. Microbial-community deoxyribonucleic acid profiling was carried out using denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal ribonucleic acid. The reactor was found to be inhabited by several diverse bacterial species, most notably microorganisms related to the genera Sphingomonas, Methylobacterium, and Hyphomicrobium vulgare. These organisms were previously reported to be associated with MTBE biodegradation. A majority of the bands in the reactor represented a group of organisms belonging to the Flavobacteria-Proteobacteria-Actinobacteridae class of bacteria. This study demonstrates that MTBE can be effectively degraded by aerobic granules under a cosubstrate condition and gives insight into the microorganisms potentially involved in the process.

Adduction of DNA with MTBE and TBA in mice studied by accelerator mass spectrometry.

PubMed

Yuan, Y; Wang, H F; Sun, H F; Du, H F; Xu, L H; Liu, Y F; Ding, X F; Fu, D P; Liu, K X

2007-12-01

Methyl tert-butyl ether (MTBE) is a currently worldwide used octane enhancer substituting for lead alkyls and gasoline oxygenate. Our previous study using doubly (14)C-labeled MTBE [(CH(3))(3) (14)CO(14)CH(3)] has shown that MTBE binds DNA to form DNA adducts at low dose levels in mice. To elucidate the mechanism of the binding reaction, in this study, the DNA adducts with singly (14)C-labeled MTBE, which was synthesized from (14)C-methanol and tert-butyl alcohol (TBA), or (14)C-labeled TBA in mice have been measured by ultra sensitive accelerator mass spectrometry. The results show that the methyl group of MTBE and tert-butyl alcohol definitely form adducts with DNA in mouse liver, lung, and kidney. The methyl group of MTBE is the predominant binding part in liver, while the methyl group and the tert-butyl group give comparable contributions to the adduct formation in lung and kidney.

Methyl tertiary-butyl ether: studies for potential human health hazards.

PubMed

McGregor, Douglas

2006-04-01

When methyl tertiary-butyl ether (MTBE) in gasoline was first introduced to reduce vehicle exhaust emissions and comply with the Clean Air Act, in the United States, a pattern of complaints emerged characterised by seven "key symptoms." Later, carefully controlled volunteer studies did not confirm the existence of the specific key symptoms, although one study of self-reported sensitive (SRS) people did suggest that a threshold at about 11-15% MTBE in gasoline may exist for SRSs in total symptom scores. Neurobehavioral and psychophysiological studies on volunteers, including SRSs, found no adverse responses associated with MTBE at likely exposure levels. MTBE is well and rapidly absorbed following oral and inhalation exposures. Cmax values for MTBE are achieved almost immediately after oral dosing and within 2 h of continuous inhalation. It is rapidly eliminated, either by exhalation as unchanged MTBE or by urinary excretion of its less volatile metabolites. Metabolism is more rapid humans than in rats, for both MTBE and tert-butyl alcohol (TBA), its more persistent primary metabolite. The other primary metabolite, formaldehyde, is detoxified at a rate very much greater than its formation from MTBE. MTBE has no specific effects on reproduction or development, or on genetic material. Neurological effects were observed only at very high concentrations. In carcinogenicity studies of MTBE, TBA, and methanol (included as an endogenous precursor of formaldehyde, without the presence of TBA), some increases in tumor incidence have been observed, but consistency of outcome was lacking and even some degree of replication was observed in only three cases, none of which had human relevance: alpha(2u)-globulin nephropathy-related renal tubule cell adenoma in male rats; Leydig-cell adenoma in male rats, but not in mice, which provide the better model of the human disease; and B-cell-derived lymphoma/leukemia of doubtful pathogenesis that arose mainly in lungs of orally dosed

Phenyl 3,5-di-tert-butyl-2-hy­droxy­benzoate

PubMed Central

Carreño, Alexander; Preite, Marcelo; Manriquez, Juan Manuel; Vega, Andrés; Chavez, Ivonne

2010-01-01

The title mol­ecule, C21H26O3, has a six-membered planar carbon ring as the central core, substituted at position 1 with phen­oxy­carbonyl, at position 2 with hy­droxy and at positions 3 and 5 with tert-butyl groups. The structure shows two independent but very similar mol­ecules within the asymmetric unit. For both independent mol­ecules, the ester carboxyl­ate group is coplanar with the central core, as reflected by the small C—C—O—C torsion angles [179.95 (17) and 173.70 (17)°]. In contrast, the phenyl substituent is almost perpendicular to the carboxyl­ate –CO2 fragment, as reflected by C—O—C—C torsion angles, ranging from 74 to 80°. The coplanarity between the central aromatic ring and the ester carboxyl­ate –CO2– group allows the formation of an intra­molecular hydrogen bond, with O⋯O distances of 2.563 (2) and 2.604 (2) Å. PMID:21589569

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...

Methylation of the TERT promoter and risk stratification of childhood brain tumours: an integrative genomic and molecular study.

PubMed

Castelo-Branco, Pedro; Choufani, Sanaa; Mack, Stephen; Gallagher, Denis; Zhang, Cindy; Lipman, Tatiana; Zhukova, Nataliya; Walker, Erin J; Martin, Dianna; Merino, Diana; Wasserman, Jonathan D; Elizabeth, Cynthia; Alon, Noa; Zhang, Libo; Hovestadt, Volker; Kool, Marcel; Jones, David T W; Zadeh, Gelareh; Croul, Sidney; Hawkins, Cynthia; Hitzler, Johann; Wang, Jean C Y; Baruchel, Sylvain; Dirks, Peter B; Malkin, David; Pfister, Stefan; Taylor, Michael D; Weksberg, Rosanna; Tabori, Uri

2013-05-01

Identification of robust biomarkers of malignancy and methods to establish disease progression is a major goal in paediatric neuro-oncology. We investigated whether methylation of the TERT promoter can be a biomarker for malignancy and patient outcome in paediatric brain tumours. For the discovery cohort, we used samples obtained from patients with paediatric brain tumours and individuals with normal brain tissues stored at the German Cancer Research Center (Heidelberg, Germany). We used methylation arrays for genome-wide assessment of DNA. For the validation cohort, we used samples obtained from several tissues for which full clinical and follow-up data were available from two hospitals in Toronto (ON, Canada). We did methylation analysis using quantitative Sequenom and pyrosequencing of an identified region of the TERT promoter. We assessed TERT expression by real-time PCR. To establish whether the biomarker could be used to assess and predict progression, we analysed methylation in paired samples of tumours that transformed from low to high grade and from localised to metastatic, and in choroid plexus tumours of different grades. Finally, we investigated overall survival in patients with posterior fossa ependymomas in which the identified region was hypermethylated or not. All individuals responsible for assays were masked to the outcome of the patients. Analysis of 280 samples in the discovery cohort identified one CpG site (cg11625005) in which 78 (99%) of 79 samples from normal brain tissues and low-grade tumours were not hypermethylated, but 145 (72%) of 201 samples from malignant tumours were hypermethylated (>15% methylated; p<0.0001). Analysis of 68 samples in the validation cohort identified a subset of five CpG sites (henceforth, upstream of the transcription start site [UTSS]) that was hypermethylated in all malignant paediatric brain tumours that expressed TERT but not in normal tissues that did not express TERT (p<0.0001). UTSS had a positive

Human TERT promoter mutation enables survival advantage from MGMT promoter methylation in IDH1 wild-type primary glioblastoma treated by standard chemoradiotherapy.

PubMed

Nguyen, HuyTram N; Lie, Amy; Li, Tie; Chowdhury, Reshmi; Liu, Fei; Ozer, Byram; Wei, Bowen; Green, Richard M; Ellingson, Benjamin M; Wang, He-Jing; Elashoff, Robert; Liau, Linda M; Yong, William H; Nghiemphu, Phioanh L; Cloughesy, Timothy; Lai, Albert

2017-03-01

Promoter mutation in the human telomerase reverse transcriptase gene (hTERT) occurs in ~75% of primary glioblastoma (GBM). Although the mutation appears to upregulate telomerase expression and contributes to the maintenance of telomere length, its clinical significance remains unclear. We performed hTERT promoter genotyping on 303 isocitrate dehydrogenase 1 wild-type GBM tumors treated with standard chemoradiotherapy. We also stratified 190 GBM patients from the database of The Cancer Genome Atlas (TCGA) by hTERT gene expression. We analyzed overall and progression-free survival by Kaplan-Meier and Cox regression. We detected hTERT promoter mutation in 75% of the patients. When included as the only biomarker, hTERT mutation was not prognostic in our patient cohort by Cox regression analysis. However, when hTERT and O6-DNA methylguanine-methyltransferase (MGMT) were included together, we observed an interaction between these 2 factors. To further investigate this interaction, we performed pairwise comparison of the 4 patient subcohorts grouped by hTERT-MGMT status (MUT-M, WT-M, MUT-U, and WT-U). MGMT methylated patients showed improved survival only in the presence of hTERT promoter mutation: MUT-M versus MUT-U (overall survival of 28.3 vs 15.9 mos, log-rank P < .0001 and progression-free survival of 15.4 vs 7.86 mo, log-rank P < .0001). These results were confirmed by Cox analyses. Analogously, the cohort from TCGA demonstrated survival benefit of MGMT promoter methylation only in patients with high hTERT expression. In addition, hTERT mutation was negatively prognostic in our MGMT unmethylated patients, while the analogous association with high expression was not observed in the cohort from TCGA. The prognostic influence of MGMT promoter methylation depends on hTERT promoter mutation. This interaction warrants further mechanistic investigation. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights

Two related lithium calixarene complexes, [p-tert-butylcalix[4]arene(OMe)(OH)2(OLi)](2).4MeCN and {p-tert-butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}(2).8MeCN, determined using synchrotron radiation.

PubMed

Lee, Darren S; Elsegood, Mark R J; Redshaw, Carl; Zhan, Shuzhong

2009-08-01

The crystal structures of acetonitrile solvates of two related lithium calixarene complexes have been determined by low-temperature single-crystal X-ray diffraction using synchrotron radiation. Bis(mu-5,11,17,23-tetra-tert-butyl-26,28-dihydroxy-25-methoxy-27-oxidocalix[4]arene)dilithium(I) acetonitrile tetrasolvate, [Li2(C45H57O4)2].4C2H3N or [p-tert-butylcalix[4]arene(OMe)(OH)2(OLi)](2).4MeCN, (I), crystallizes with the complex across a centre of symmetry and with four molecules of unbound acetonitrile of crystallization per complex. Tetraacetonitrilebis(mu-5,11,17,23-tetra-tert-butyl-26,28-dihydroxy-25,27-dioxidocalix[4]arene)tetralithium(I) acetonitrile octasolvate, [Li4(C44H54O4)2(C2H3N)4].8C2H3N or {p-tert-butylcalix[4]arene(OH)2(OLi)[OLi(NCMe)2]}(2).8MeCN, (II), also crystallizes with the complex lying across a centre of symmetry and contains eight molecules of unbound acetonitrile per complex plus four more directly bound to two of the lithium ions, two on each ion. The cores of both complexes are partially supported by O-H...O hydrogen bonds. The methoxy methyl groups in (I) prevent the binding of any more than two Li+ ions, while the corresponding two O-atom sites in (II) bind an extra Li(+) ion each, making four in total. The calixarene cone adopts an undistorted cone conformation in (I), but an elliptical one in (II).

On the competition between weak O-H···F and C-H···F hydrogen bonds, in cooperation with C-H···O contacts, in the difluoromethane – tert-butyl alcohol cluster

PubMed Central

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

2017-01-01

The 1:1 complex of tert-butyl alcohol with difluoromethane has been characterized by means of a joint experimental-computational investigation. Its rotational spectrum has been recorded by using a pulsed-jet Fourier-Transform microwave spectrometer. The experimental work has been guided and supported by accurate quantum-chemical calculations. In particular, the computed potential energy landscape pointed out the formation of three stable isomers. However, the very low interconversion barriers explain why only one isomer, showing one O-H···F and two C-H···O weak hydrogen bonds, has been experimentally characterized. The effect of the H → tert-butyl- group substitution has been analyzed from the comparison to the difluoromethane-water adduct. PMID:28919646

Enhanced diisobutene production in the presence of methyl tertiary butyl ether

DOEpatents

Smith, Jr., Lawrence A.

1983-01-01

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

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

NASA Astrophysics Data System (ADS)

Watanabe, Hiroshi

2011-03-01

Viscoelastic and dielectric behavior was examined for well entangled, miscible blends of high- M cis-polyisoprene (PI) and poly(p-tert-butyl styrene) (PtBS). The dielectric data of the blends, reflecting the global motion of the PI chains having the type-A dipoles, indicated that PI and PtBS were the fast and slow components therein. At high temperatures T , the blends exhibited two-step entanglement plateau. The high frequency (ω) plateau height was well described by a simple mixing rule of the entanglement length based on the number fraction of the Kuhn segments. At low T , the blend exhibited the Rouse-like power-law behavior of storage and loss moduli, G ' = G ~ω0.5 , in the range of ω where the high- ω plateau was supposed to emerge. This lack of the high- ω plateau was attributed to retardation of the Rouse equilibration of the PI chain over the entanglement length due to the hindrance from the slow PtBS chains: The PI and PtBS chains were equilibrated cooperatively, and the retardation due to PtBS shortened the plateau for PI to a width not resolved experimentally. A simple model for this cooperative equilibration formulated on the basis of the dielectric data described the viscoelastic data surprisingly well.

Electrical properties of binary mixtures of amino silicone oil and methyl iso butyl ketone

NASA Astrophysics Data System (ADS)

Shah, K. N.; Rana, V. A.; Vankar, H. P.

2018-05-01

The real and imaginary parts of the dielectric function of the binary mixtures of the methyl iso butyl ketone and amino silicone oil in the frequency range 100 Hz to 2 MHz were measured using precision LCR meter at 305.15 K. The electrical properties such as electrical modulus M*(ω), electrical conductivity σ*(ω) and complex impedance Z*(ω) were calculated using the dielectric function ɛ*(ω). The ionic polarization relaxation time (Τσ) and D.C. conductivity (σdc) were also calculated using electrical properties. The ionic behavior of methyl iso butyl ketone and non-ionic behavior of amino silicone oil are also explained. The electrical parameters are used to gain information about the effect of concentration variation of components of the mixtures on the electrical properties.

Enhanced diisobutene production in the presence of methyl tertiary butyl ether

DOEpatents

Smith, L.A. Jr.

1983-03-01

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

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

PubMed

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

2018-02-01

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

The correlations between DNA methylation and polymorphisms in the promoter region of the human telomerase reverse transcriptase (hTERT) gene with postoperative recurrence in patients with thyroid carcinoma (TC).

PubMed

Li, Jian-Jun; Zheng, Ping Chen Jue-Ru; Wang, Yao-Zong

2017-06-06

This study aims at exploring the correlations between DNA methylation and polymorphisms in the promoter region of the human telomerase reverse transcriptase (hTERT) gene and postoperative recurrence in patients with thyroid carcinoma (TC). A total of 312 patients diagnosed with TC were chosen for the study and categorized into recurrence (n = 75) and non-recurrence (n = 237) groups. The hTERT rs2736100 and rs2736098 polymorphisms were detected by performing polymerase chain reaction-restriction fragment length polymorphism. DNA methylation in the promoter region of hTERT gene was evaluated by pyrosequencing. A telephonic and/or outpatient follow-up was conducted for all patients. The correlations of DNA methylation and polymorphisms in the promoter region of hTERT with postoperative recurrence of TC patients underwent analysis. The patient in the recurrence group showed evidently different pathological types and tumor stages in comparison to the non-recurrence group. The GG genotype of hTERT rs2736100 might increase the recurrence risk of TC patients. No correlations between hTERT rs2736098 polymorphisms and recurrence risk were observed. Compared to the TT + TG genotype frequency, the rs2736100 GG genotype frequency increased in patients without multicentricity, patients with extrathyroidal invasion, patients with lymph node metastasis, patients with undifferentiated carcinoma, and patients in the III + IV stage. The recurrence group showed significantly higher DNA methylation level compared to the non-recurrence group. The DNA methylation level was closely associated to tumor stage and lymph node metastasis of TC patients in the recurrence group. The DNA methylation and rs2736100 polymorphisms in the promoter region of hTERT gene might be in correlation to postoperative recurrence of TC patients.

Protective effect of vanilloids against tert-butyl hydroperoxide-induced oxidative stress in vero cells culture.

PubMed

Rosa, Antonella; Atzeri, Angela; Deiana, Monica; Melis, M Paola; Incani, Alessandra; Corona, Giulia; Loru, Debora; Appendino, Giovanni; Dessì, M Assunta

2008-05-28

This study investigated the effect of synthetic capsiate, a simplified analogue of capsiate, and vanillyl alcohol on the oxidative stress induced by tert-butyl hydroperoxide (TBH) in a line of fibroblasts derived from monkey kidney (Vero cells). In response to the TBH-mediated oxidative stress, a reduction of the levels of total unsaturated fatty acids and cholesterol was observed, and a rise in the concentrations of conjugated dienes fatty acids hydroperoxides and 7-ketocholesterol. Pretreatment with both synthetic capsiate and vanillyl alcohol preserved Vero cells from oxidative damage and showed a remarkable protective effect on the reduction of the levels of total unsaturated fatty acids and cholesterol, inhibiting the increase of MDA, conjugated dienes fatty acids hydroperoxides, and 7-ketocholesterol. Both compounds were effective against peroxidation of cell membrane lipids induced by TBH, with synthetic capsiate essentially acting as a pro-drug of vanillyl alcohol, its hydrophilic hydrolytic derivative.

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

PubMed

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

2017-05-10

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

Telomerase activity, telomere length and hTERT DNA methylation in peripheral blood mononuclear cells from monozygotic twins with discordant smoking habits.

PubMed

Marcon, Francesca; Siniscalchi, Ester; Andreoli, Cristina; Allione, Alessandra; Fiorito, Giovanni; Medda, Emanuela; Guarrera, Simonetta; Matullo, Giuseppe; Crebelli, Riccardo

2017-10-01

Increased telomerase expression has been implicated in the pathogenesis of lung cancer and, since the primary cause of lung cancer is smoking, an association between telomerase reactivation and tobacco smoke has been proposed. In this work an investigation has been performed to assess the relationship between tobacco smoke exposure and telomerase activity (TA) in peripheral blood mononuclear cells of healthy smokers. The methylation status of the catalytic subunit of telomerase hTERT was concurrently investigated to assess the possible association between epigenetic modifications of hTERT and TA. Besides, the association between smoke and telomere length (TL) has been evaluated. Healthy monozygotic twins with discordant smoking habits were selected as study population to minimize inter-individual differences because of demographic characteristics and genetic heterogeneity. Statistically significant higher values of TA and TL were observed in smokers compared to nonsmoker co-twins. The multivariate analysis of data showed, besides smoking habits (P = 0.02), an influence of gender (P = 0.006) and BMI (P = 0.001) on TA and a borderline effect of gender (P = 0.05) on TL. DNA methylation analysis, focused on 100 CpG sites mapping in hTERT, highlighted nine CpG sites differentially methylated in smokers. When co-twins were contrasted, selecting as variables the intra-twin difference in TA and hTERT DNA methylation, a statistically significant inverse correlation (P = 0.003) was observed between TA and DNA methylation at the cg05521538 site. In conclusion, these results indicate an association of tobacco smoke with TA and TL and suggest a possible association between smoke-induced epigenetic effects and TA in healthy smokers. Environ. Mol. Mutagen. 58:551-559, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

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

Code of Federal Regulations, 2012 CFR

2012-07-01

..., Calcium Salt Maleic Anhydride Methacrylic Acid *Methacrylic Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n... Acid Nylon Salt Oxalic Acid *Oxo Aldehydes—Alcohols Pentaerythritol Pentane *Pentenes *Petroleum...

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

Code of Federal Regulations, 2014 CFR

2014-07-01

..., Calcium Salt Maleic Anhydride Methacrylic Acid *Methacrylic Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n... Acid Nylon Salt Oxalic Acid *Oxo Aldehydes—Alcohols Pentaerythritol Pentane *Pentenes *Petroleum...

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

Code of Federal Regulations, 2011 CFR

2011-07-01

..., Calcium Salt Maleic Anhydride Methacrylic Acid *Methacrylic Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n... Acid Nylon Salt Oxalic Acid *Oxo Aldehydes—Alcohols Pentaerythritol Pentane *Pentenes *Petroleum...

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

Code of Federal Regulations, 2013 CFR

2013-07-01

..., Calcium Salt Maleic Anhydride Methacrylic Acid *Methacrylic Acid Esters Methane Methyl Ethyl Ketone Methyl Methacrylate Methyl Tert-Butyl Ether Methylisobutyl Ketone *n-Alkanes n-Butyl Alcohol n-Butylacetate n... Acid Nylon Salt Oxalic Acid *Oxo Aldehydes—Alcohols Pentaerythritol Pentane *Pentenes *Petroleum...

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...

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

EPA Science Inventory

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

21 CFR 176.200 - Defoaming agents used in coatings.

Code of Federal Regulations, 2014 CFR

2014-04-01

... are provided: List of substances Limitations n-Butyl alcohol tert-Butyl alcohol Butyl stearate Castor... Glyceryl monostearate Hexane Hexylene glycol (2-methyl-2,4-pentanediol) Isobutyl alcohol Isopropyl alcohol...

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

PubMed

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

2013-03-01

New salen type ligands, N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-ethylenedianiline [(X=H (1), 5-tert-butyl (2)] and N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-amidedianiline [X=H (3), 5-tert (4)] and their copper(II) complexes 5-8, have been synthesized. Their spectroscopic (IR, (1)H NMR, UV/vis, ESR) properties, as well as magnetic and redox-reactivity behavior are reported. IR spectra of 7 and 8 indicate the coordination of amide oxygen atoms of 3 and 4 ligands to Cu(II). The solid state ESR spectra of 5-8 exhibits less informative exchange narrowed isotropic or anisotropic signals with weak unresolved low field patterns. The magnetic moments of 5 (2.92 μ(B) per Cu(II)) and 6 (2.79 μ(B) per Cu(II)) are unusual for copper(II) complexes and considerably higher than those for complexes 7 and 8. Cryogenic measurements (300-10 K) show weak antiferromagnetic exchange interactions between the copper(II) centers in complexes 6 and 8. The results of electrochemical and chemical redox-reactivity studies are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

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...

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...

2-(4-Bromo­benz­yl)-5,11,17,23-tetra-tert-butyl-25,26,27,28-tetra­methoxy­calix[4]arene

PubMed Central

Fischer, Conrad; Lin, Guisheng; Seichter, Wilhelm; Weber, Edwin

2009-01-01

In the title compound, C55H69BrO4, the calixarene mol­ecule displays a ‘partial cone’ conformation bearing the lateral substituent in a sterically favorable equatorial arrangement between two syn-orientated arene units. The crystal packing is stabilized by weak C—H⋯π contacts, involving one tert-butyl group, and π–stacking inter­actions of the lateral bromo­benzene units [centroid–centroid distance = 3.706 (1) Å]. PMID:21582956

Catalytic performance of strong acid catalyst: Methyl modified SBA-15 loaded perfluorinated sulfonic acid obtained by the waste perfluorinated sulfonic acid ion exchange membrane

NASA Astrophysics Data System (ADS)

Jiang, Tingshun; Huang, Qiuyan; Li, Yingying; Fang, Minglan; Zhao, Qian

2018-02-01

Mesoporous molecular sieve (SBA-15) was modified using the trimethylchlorosilane as functional agent and the silylation SBA-15 mesoporous material was prepared in this work. The alcohol solution of perfluorinated sulfonic acid dissolved from the waste perfluorinated sulfonic acid ion exchange membrane (PFSIEM) was loaded onto the resulting mesoporous material by the impregnation method and their physicochemical properties were characterized by FT-IR, N2-physisorption, XRD, TG-DSC and TEM. The catalytic activities of these synthesized solid acid catalysts were evaluated by alkylation of phenol with tert-butyl alcohol. The influence of reaction temperature, weight hour space velocity (WHSV) and reaction time on the phenol conversion and product selectivity were assessed by means of a series of experiments. The results showed that with the increase of the active component of the catalyst, these catalysts still remained good mesoporous structure, but the mesoporous ordering decreased to some extent. These catalysts exhibited good catalytic performance for the alkylation of phenol with tert-butanol. The maximum phenol conversion of 89.3% with 70.9% selectivity to 4-t-butyl phenol (4-TBP) was achieved at 120 °C and the WHSV is 4 h-1. The methyl group was loaded on the surface of the catalyst by trimethylchlorosilane. This is beneficial to retard the deactivation of the catalyst. In this work, the alkylation of phenol with tert-butyl alcohol were carried out using the methyl modified SBA-15 mesoporous materials loaded perfluorinated sulfonic acid as catalysts. The results show that the resulting catalyst exhibited high catalytic activity.

Microwave-assisted synthesis and crystal structure of oxo(diperoxo)(4,4'-di-tert-butyl-2,2'-bipyridine)-molybdenum(VI).

PubMed

Amarante, Tatiana R; Almeida Paz, Filipe A; Gago, Sandra; Gonçalves, Isabel S; Pillinger, Martyn; Rodrigues, Alírio E; Abrantes, Marta

2009-09-16

The oxodiperoxo complex MoO(O2)(2)(tbbpy) (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine) was isolated from the reaction of MoO2Cl(2)(tbbpy) in water under microwaveassisted heating at 120 masculineC for 4 h. The structure of the oxodiperoxo complex was determined by single crystal X-ray diffraction. The Mo(VI) centre is seven-coordinated with a geometry which strongly resembles a highly distorted bipyramid. Individual MoO(O2)(2)(tbbpy) complexes are interdigitated along the [010] direction to form a column. The crystal structure is formed by the close packing of the columnar-stacked complexes. Interactions between neighbouring columns are essentially of van der Waals type mediated by the need to effectively fill the available space.

SIRT1 exhibits antioxidative effects in HT22 cells induced by tert-butyl alcohol.

PubMed

Ma, Junxiang; Song, Dongmei; Zhang, Yuanyuan; Chen, Li; Zhang, Shixuan; Jia, Jiaxin; Chen, Tian; Guo, Caixia; Tian, Lin; Gao, Ai; Niu, Piye

2018-02-01

Tertiary butyl alcohol (TBA) is a principal metabolite of methyl tertiary-butyl ether (MTBE), a common pollutant worldwide in the ground or underground water, which is found to produce nervous system damage. Nevertheless, few data regarding the effects of TBA has been reported. Studies indicated that oxidative stress plays a pivotal role in MTBE neurotoxic mechanism. Sirtuin 1 (SIRT1) has been reported to exert a neuroprotective effect on various neurologic diseases via resistance to oxidative stress by deacetylating its substrates. In this study, we examined levels of oxidative stress after exposure to TBA for 6 h in HT22 cells and HT22 cells with SIRT1 silencing (transfected with SIRT1 siRNA) or high expression (preconditioned with agonists SRT1720). We found that TBA activated oxidative stress by increasing generation of intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and Oxidized glutathione (GSSG), and decreasing contents of superoxide dismutase (SOD) and glutathione reductase (GSH). In additional, levels of TBA-induced oxidative stress were aggravated when SIRT1 silenced but alleviated when SIRT1 enhanced. Our study indicated that SIRT1 mitigated oxidative stress induced by TBA. © 2017 Wiley Periodicals, Inc.

Phenyl-alpha-tert-butyl nitrone reverses mitochondrial decay in acute Chagas' disease.

PubMed

Wen, Jian-Jun; Bhatia, Vandanajay; Popov, Vsevolod L; Garg, Nisha Jain

2006-12-01

In this study, we investigated the mechanism(s) of mitochondrial functional decline in acute Chagas' disease. Our data show a substantial decline in respiratory complex activities (39 to 58%) and ATP (38%) content in Trypanosoma cruzi-infected murine hearts compared with normal controls. These metabolic alterations were associated with an approximately fivefold increase in mitochondrial reactive oxygen species production rate, substantial oxidative insult of mitochondrial membranes and respiratory complex subunits, and >60% inhibition of mtDNA-encoded transcripts for respiratory complex subunits in infected myocardium. The antioxidant phenyl-alpha-tert-butyl nitrone (PBN) arrested the oxidative damage-mediated loss in mitochondrial membrane integrity, preserved redox potential-coupled mitochondrial gene expression, and improved respiratory complex activities (47 to 95% increase) and cardiac ATP level (>or=40% increase) in infected myocardium. Importantly, PBN resulted twofold decline in mitochondrial reactive oxygen species production rate in infected myocardium. Taken together, our data demonstrate the pathological significance of oxidative stress in metabolic decay and energy homeostasis in acute chagasic myocarditis and further suggest that oxidative injuries affecting mitochondrial integrity-dependent expression and activity of the respiratory complexes initiate a feedback cycle of electron transport chain inefficiency, increased reactive oxygen species production, and energy homeostasis in acute chagasic hearts. PBN and other mitochondria-targeted antioxidants may be useful in altering mitochondrial decay and oxidative pathology in Chagas' disease.

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

PubMed

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

2011-02-01

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

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

NASA Astrophysics Data System (ADS)

Jamróz, Małgorzata E.; Jarosz, Małgorzata; Witowska-Jarosz, Janina; Bednarek, Elżbieta; Tęcza, Witold; Jamróz, Michał H.; Dobrowolski, Jan Cz.; Kijeński, Jacek

2007-07-01

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

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

PubMed Central

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

2011-01-01

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

Interactions of poly(tert-butyl acrylate)-poly(styrene) diblock copolymers with lipids at the air-water interface.

PubMed

Mudgil, Poonam; Dennis, Gary R; Millar, Thomas J

2006-08-29

Diblock copolymers with hydrophilic poly(tert-butyl acrylate) (PtBA) and hydrophobic poly(styrene) (PS) blocks were synthesized with a view to use them as a surfactant in tear film for increasing the ocular comfort in dry eye syndrome. Interactions of six PtBA-PS copolymers with four important lipids found in the tear film, namely cholesterol, cholesteryl palmitate, dipalmitoyl phosphatidylcholine, and phosphatidylinositol, were studied at the air-water interface using a Langmuir trough. Thermodynamics of mixing of the copolymers and the lipids in the mixed monolayers was determined by calculating excess free energy of mixing. The diblock copolymers showed repulsive interactions with cholesteol and cholesteryl palmitate, near neutral interactions with dipalmitoyl phosphatidylcholine, and attractive interactions with phosphatidylinositol. The lipids interacted with the PS component of the copolymer. The results indicate that a copolymer with a small hydrophilic group and a big hydrophobic group can be a likely candidate for forming stable interactions with the lipids present in the tear film and hence increase the ocular comfort.

Development and application of a rat PBPK model to elucidate kidney and liver effects induced by ETBE and tert-butanol.

PubMed

Salazar, Keith D; Brinkerhoff, Christopher J; Lee, Janice S; Chiu, Weihsueh A

2015-11-01

Subchronic and chronic studies in rats of the gasoline oxygenates ethyl tert-butyl ether (ETBE) and tert-butanol (TBA) report similar noncancer kidney and liver effects but differing results with respect to kidney and liver tumors. Because TBA is a major metabolite of ETBE, it is possible that TBA is the active toxic moiety in all these studies, with reported differences due simply to differences in the internal dose. To test this hypothesis, a physiologically-based pharmacokinetic (PBPK) model was developed for ETBE and TBA to calculate internal dosimetrics of TBA following either TBA or ETBE exposure. This model, based on earlier PBPK models of methyl tert-butyl ether (MTBE), was used to evaluate whether kidney and liver effects are consistent across routes of exposure, as well as between ETBE and TBA studies, on the basis of estimated internal dose. The results demonstrate that noncancer kidney effects, including kidney weight changes, urothelial hyperplasia, and chronic progressive nephropathy (CPN), yielded consistent dose-response relationships across routes of exposure and across ETBE and TBA studies using TBA blood concentration as the dose metric. Relative liver weights were also consistent across studies on the basis of TBA metabolism, which is proportional to TBA liver concentrations. However, kidney and liver tumors were not consistent using any dose metric. These results support the hypothesis that TBA mediates the noncancer kidney and liver effects following ETBE administration; however, additional factors besides internal dose are necessary to explain the induction of liver and kidney tumors. Published by Elsevier Inc.

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

EPA Science Inventory

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

Highly efficient enzymatic synthesis of tert-butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate with a mutant alcohol dehydrogenase of Lactobacillus kefir.

PubMed

He, Xiu-Juan; Chen, Shao-Yun; Wu, Jian-Ping; Yang, Li-Rong; Xu, Gang

2015-11-01

tert-Butyl (S)-6-chloro-5-hydroxy-3-oxohexanoate ((S)-CHOH) is a valuable chiral synthon, which is used for the synthesis of the cholesterol-lowering drugs atorvastatin and rosuvastatin. To date, only the alcohol dehydrogenases from Lactobacillus brevis (LbADH) and Lactobacillus kefir (LkADH) have demonstrated catalytic activity toward the asymmetric reduction of tert-butyl 6-chloro-3,5-dioxohexanoate (CDOH) to (S)-CHOH. Herein, a tetrad mutant of LkADH (LkTADH), A94T/F147L/L199H/A202L, was screened to be more efficient in this bioreduction process, exhibiting a 3.7- and 42-fold improvement in specific activity toward CDOH (1.27 U/mg) over LbADH (0.34 U/mg) and wild-type LkADH (0.03 U/mg), respectively. The molecular basis for the improved catalytic activity of LkTADH toward CDOH was investigated using homology modeling and docking analysis. Two major issues had a significant impact on the biocatalytic efficiency of this process, including (i) the poor aqueous stability of the substrate and (ii) partial substrate inhibition. A fed-batch strategy was successfully developed to address these issues and maintain a suitably low substrate concentration throughout the entire process. Several other parameters were also optimized, including the pH, temperature, NADP(+) concentration and cell loading. A final CDOH concentration of 427 mM (100 g/L) gave (S)-CHOH in 94 % yield and 99.5 % e.e. after a reaction time of 38 h with whole cells expressing LkTADH. The space-time yield and turnover number of NADP(+) in this process were 10.6 mmol/L/h and 16,060 mol/mol, respectively, which were the highest values ever reported. This new approach therefore represents a promising alternative for the efficient synthesis of (S)-CHOH.

Protective effects of hesperidin against oxidative stress of tert-butyl hydroperoxide in human hepatocytes.

PubMed

Chen, Mingcang; Gu, Honggang; Ye, Yiyi; Lin, Bing; Sun, Lijuan; Deng, Weiping; Zhang, Jingzhe; Liu, Jianwen

2010-10-01

Increasing evidence regarding free radical generating agents and the inflammatory process suggest that accumulation of reactive oxygen species (ROS) could involve hepatotoxicity. Hesperidin, a naturally occurring flavonoid presents in fruits and vegetables, has been reported to exert a wide range of pharmacological effects that include antioxidant, anti-inflammatory, antihypercholesterolemic, and anticarcinogenic actions. However, the cytoprotection and mechanism of hesperidin to neutralize oxidative stress in human hepatic L02 cells remain unclear. In this work, we assessed the capability of hesperidin to prevent tert-butyl hydroperoxide (t-BuOOH)-induced cell damage by augmenting cellular antioxidant defense. Hesperidin significantly protected hepatocytes against t-BuOOH-induced cell cytotoxicity, such as mitochondrial membrane potential (MMP) deplete and lactate dehydrogenase (LDH) release. Hesperidin also remarkably prevented indicators of oxidative stress, such as the ROS and lipid peroxidation level in a dose-dependent manner. Western blot showed that hesperidin facilitated ERK/MAPK phosphorylation which appeared to be responsible for nuclear translocation of Nrf2, thereby inducing cytoprotective heme oxygenase-1 (HO-1) expression. Based on the results described above, it suggested that hesperidin has potential as a therapeutic agent in the treatment of oxidative stress-related hepatocytes injury and liver dysfunctions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Dynamics of an excess hole in the 1-methyl-1-butyl-pyrrolidinium dicyanamide ionic-liquid

NASA Astrophysics Data System (ADS)

Wu, Fei; Xu, Changhui; Margulis, Claudio J.

2018-05-01

In a set of recent publications [C. J. Margulis et al., J. Am. Chem. Soc. 133, 20186 (2011); C. H. Xu et al., J. Am. Chem. Soc. 135, 17528 (2013); C. H. Xu and C. J. Margulis, J. Phys. Chem. B 119, 532 (2015); and K. B. Dhungana et al., J. Phys. Chem. B 121, 8809 (2017)], we explored for selected ionic liquids the early stages of excess charge localization and reactivity relevant both to electrochemical and radiation chemistry processes. In particular, Xu and Margulis [J. Phys. Chem. B 119, 532 (2015)] explored the dynamics of an excess electron in 1-methyl-1-butyl-pyrrolidinium dicyanamide. When electrons are produced from an ionic liquid, the more elusive hole species are also generated. Depending on the nature of cations and anions and the relative alignment of their electronic states in the condensed phase, the very early hole species can nominally be neutral radicals—if the electron is generated from anions—or doubly charged radical cations if their origin is from cations. However, in reality early excess charge localization is more complex and often involves more than one ion. The dynamics and the transient spectroscopy of the hole are the main objects of this study. We find that in the case of 1-methyl-1-butyl-pyrrolidinium dicyanamide, it is the anions that can most easily lose an electron becoming radical species, and that hole localization is mostly on anionic nitrogen. We also find that the driving force for localization of an excess hole appears to be smaller than that for an excess electron in 1-methyl-1-butyl-pyrrolidinium dicyanamide. The early transient hole species can absorb light in the visible, ultraviolet, and near infrared regions, and we are able to identify the type of states being connected by these transitions.

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

PubMed

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

2016-09-02

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

LASERS IN MEDICINE: Quantum efficiency of the laser-excited singlet-oxygen-sensitised delayed fluorescence of the zinc complex of tetra(4-tert-butyl)phthalocyanine

NASA Astrophysics Data System (ADS)

Bashtanov, M. E.; Drozdova, N. N.; Krasnovskii, A. A.

1999-12-01

An investigation was made of the ratios of the intensity Idf of the singlet-oxygen(1O2)-sensitised delayed fluorescence of the zinc complex of tetra(4-tert-butyl)phthalocyanine (ZnTBPc), with the maximum at λ = 685 nm, to the intensity I1270 of the photosensitised phosphorescence of 1O2 with the maximum at λ = 1270 nm in deuterated benzene when excited with λ = 337 nm nitrogen-laser pulses. Depending on the energy density of the laser radiation (0.25 — 0.7 mJ cm-2) and on the concentration of ZnTBPc (0.06 — 3.4 μM), the ratio of the zero-time intensities of the delayed fluorescence of ZnTBPc and of the singlet-oxygen phosphorescence Idf0/I12700 varied from 0.01 to 0.2 in air-saturated solutions of ZnTBPc. The intensity Idf0 decreased fivefold as a result of saturation with oxygen of air-saturated solutions. The quantum efficiency of the delayed fluorescence was represented by the coefficient α =(Idf0/I12700)kr/(γf[1O2]0[ZnTBPc]), where [1O2]0 is the zero-time concentration of 1O2 after a laser shot; kr is the rate constant of radiative deactivation of 1O2 in the investigated solvent; γf is the quantum yield of the ZnTBPc fluorescence. It was established that in the case of air-saturated solutions of ZnTBPc this coefficient was approximately 200 times less than for metal-free tetra(4-tert-butyl)phthalocyanine and its absolute value was ~2 × 1011 M-2 s-1.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

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

PubMed

Wang, C J; Wang, J M; Lin, W L; Chu, C Y; Chou, F P; Tseng, T H

2000-05-01

Hibiscus anthocyanins (HAs), a group of natural pigments occurring in the dried flowers of Hibiscus sabdariffa L., which is a local soft drink material and medical herb, were studied for antioxidant bioactivity. The preliminary study showed that HAs were able to quench the free radicals of 1,1-diphenyl-2-picrylhydrazyl. This antioxidant bioactivitiy was further evaluated using the model of tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity in rat primary hepatocytes and hepatotoxicity in rats. The results demonstrated that HAs, at the concentrations of 0.10 and 0.20 mg/ml, significantly decreased the leakage of lactate dehydrogenase and the formation of malondialdehyde induced by a 30-min treatment of t-BHP (1.5 mM). The in vivo investigation showed that the oral pretreatment of HAs (100 and 200 mg/kg) for 5 days before a single dose of t-BHP (0.2 mmol/kg, ip) significantly lowered the serum levels of hepatic enzyme markers (alanine and aspartate aminotransferase) and reduced oxidative liver damage. The histopathological evaluation of the liver revealed that Hibiscus pigments reduced the incidence of liver lesions including inflammatory, leucocyte infiltration, and necrosis induced by t-BHP in rats. Based on the results described above, we speculate that Hibiscus pigments may play a role in the prevention of oxidative damage in living systems.

Structural, energetic, and UV-Vis spectral analysis of UVA filter 4-tert-butyl-4'-methoxydibenzoylmethane.

PubMed

Pinto da Silva, Luís; Ferreira, Paulo J O; Duarte, Darío J R; Miranda, Margarida S; Esteves da Silva, Joaquim C G

2014-02-27

The growing awareness of the harmful effects of ultraviolet (UV) solar radiation has increased the production and consumption of sunscreen products, which contain organic and inorganic molecules named UV filters that absorb, reflect, or scatter UV radiation, thus minimizing negative human health effects. 4-tert-Butyl-4'-methoxydibenzoylmethane (BMDBM) is one of the few organic UVA filters and the most commonly used. BMDBM exists in sunscreens in the enol form which absorbs strongly in the UVA range. However, under sunlight irradiation tautomerization occurs to the keto form, resulting in the loss of UV protection. In this study we have performed quantum chemical calculations to study the excited-state molecular structure and excitation spectra of the enol and keto tautomers of BMDBM. This knowledge is of the utmost importance as the starting point for studies aiming at the understanding of its activity when applied on human skin and also its fate once released into the aquatic environment. The efficiency of excitation transitions was rationalized based on the concept of molecular orbital superposition. The loss of UV protection was attributed to the enol → keto phototautomerism and subsequent photodegradation. Although this process is not energetically favorable in the singlet bright state, photodegradation is possible because of intersystem crossing to the first two triplet states.

Role of 6-shogaol in tert -butyl hydroperoxide-induced apoptosis of HepG2 cells.

PubMed

Kim, Sang Chan; Lee, Jong Rok; Park, Sook Jahr

2014-01-01

The aim of this study was to investigate the protective effects of 6-shogaol on tert-butyl hydroperoxide (tBHP)-induced oxidative stress leading to apoptosis in human hepatoma cell line HepG2. The cells were exposed to tBHP (100 μmol/l) after pretreatment with 6-shogaol (2.5 and 5 μmol/l), and then cell viability was measured. 6-Shogaol fully prevented HepG2 cell death caused by tBHP. Treatment of tBHP resulted in apoptotic cell death as assessed by TUNEL assay and the expression of apoptosis regulator proteins, Bcl-2 family, caspases and cytochrome c. Cells treated with 6-shogaol showed rapid reduction of apoptosis by restoring these markers of apoptotic cells. In addition, 6-shogaol significantly recovered disruption of mitochondrial membrane potential as a start sign of hepatic apoptosis induced by oxidative stress. In line with this observation, antioxidative 6-shogaol inhibited generation of reactive oxygen species and depletion of reduced glutathione in tBHP-stimulated HepG2 cells. Taken together, these results for the first time showed antioxidative and antiapoptotic activities of 6-shogaol in tBHP-treated hepatoma HepG2 cells, suggesting that 6-shogaol could be beneficial in hepatic disorders caused by oxidative stress. © 2014 S. Karger AG, Basel.

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...

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

ERIC Educational Resources Information Center

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

2004-01-01

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

Epigenetic Alteration by DNA Methylation of ESR1, MYOD1 and hTERT Gene Promoters is Useful for Prediction of Response in Patients of Locally Advanced Invasive Cervical Carcinoma Treated by Chemoradiation.

PubMed

Sood, S; Patel, F D; Ghosh, S; Arora, A; Dhaliwal, L K; Srinivasan, R

2015-12-01

Locally advanced invasive cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) IIB/III] is treated by chemoradiation. The response to treatment is variable within a given FIGO stage. Therefore, the aim of the present study was to evaluate the gene promoter methylation profile and corresponding transcript expression of a panel of six genes to identify genes which could predict the response of patients treated by chemoradiation. In total, 100 patients with invasive cervical cancer in FIGO stage IIB/III who underwent chemoradiation treatment were evaluated. Ten patients developed systemic metastases during therapy and were excluded. On the basis of patient follow-up, 69 patients were chemoradiation-sensitive, whereas 21 were chemoradiation-resistant. Gene promoter methylation and gene expression was determined by TaqMan assay and quantitative real-time PCR, respectively, in tissue samples. The methylation frequency of ESR1, BRCA1, RASSF1A, MLH1, MYOD1 and hTERT genes ranged from 40 to 70%. Univariate and hierarchical cluster analysis revealed that gene promoter methylation of MYOD1, ESR1 and hTERT could predict for chemoradiation response. A pattern of unmethylated MYOD1, unmethylated ESR1 and methylated hTERT promoter as well as lower ESR1 transcript levels predicted for chemoradiation resistance. Methylation profiling of a panel of three genes that includes MYOD1, ESR1 and hTERT may be useful to predict the response of invasive cervical carcinoma patients treated with standard chemoradiation therapy. Copyright © 2015 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

(E)-2′-[(3,5-Di-tert-butyl-2-hy­droxy­benzyl­idene)amino]-1,1′-binaphthalen-2-ol methanol monosolvate

PubMed Central

He, Dian; Li, Chong; Wang, Xiaohong

2011-01-01

The title compound, C35H35NO2·CH4O, was obtained by the reaction of rac-2-amino-2-hy­droxy-1,1-binaphthyl and 3,5-di-tert-butyl-2-hy­droxy­benzaldehyde in absolute methanol. In the Schiff base mol­ecule, the two naphthyl bicycles are twisted by 71.15 (5)°. One hy­droxy group is involved in intra­molecular O—H⋯N hydrogen bond, while the methanol solvent mol­ecule is linked to another hy­droxy group via an inter­molecular O—H⋯O hydrogen bond. PMID:22219946

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

PubMed Central

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

2014-01-01

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

Some features of the oxidative conversion of Mo(CO)/sub 6/ in a medium of hydroperoxide or tert-butyl hydroperoxide and an aromatic hydrocarbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fomin, V.M.; Lunin, A.V.; Aleksandrov, Yu.A.

1988-03-10

Occurrence of the reaction under study was followed from the decrease in hydroperoxide or of Mo(CO)/sub 6/. The Mo(CO)/sub 6/ content of the reaction was found by determining either the concentration of this compound directly or by determining the concentration of the gaseous products from its transformations (CO + CO/sub 2/). Hydroperoxides (I) and (II) were determined iodometrically. Metal-containing products of the oxidation of Mo(CO)/sub 6/, molybdenum oxides and peroxides, were analyzed by IR and ESR spectroscopy, elemental analysis, and iodometry. Analysis of transformation products of the hydroperoxides (phenol, acetone, dimethylphenylcarbinol, acetophenone, tert-butyl alcohol, water, and oxygen) was performed usingmore » gas chromatography. Results are presented.« less

Synthesis of methyl 3-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside and methyl 3-O-alpha-D-talopyranosyl-alpha-D-talopyranoside.

PubMed

Dubey, R; Jain, R K; Abbas, S A; Matta, K L

1987-08-01

Methyl 2-O-benzyl-3-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha- D-mannopyranoside (4) and methyl 2-O-benzyl-3-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside (6) were prepared from a common intermediate, namely, methyl 2-O-benzyl-4,6-O-benzylidene-3-O-(2,3,4,6-tetra-O-acetyl-alpha-D- mannopyranosyl)-alpha-D-mannopyranoside. On treatment with tert-butylchlorodiphenylsilane, in N,N-dimethylformamide in the presence of imidazole, 4 and 6 afforded methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-mannopyranoside (7), and methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(6-O-tert- butyldiphenylsilyl-alpha-D-mannopyranosyl)-alpha-D-mannopyranoside (8), respectively. Compound 8 was converted into its 2,3-O-isopropylidene derivative (9), and oxidation of 7 and 9 with pyridinium chlorochromate, and reduction of the resulting carbonyl intermediates gave methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-talopyranoside and methyl 2-O-benzyl-6-O-tert-butyldiphenylsilyl-3-O-(6-O-tert-butyldiphe nylsilyl- 2,3-O-isopropylidene-alpha-D-talopyranosyl)-alpha-D-talopyranoside , respectively. Removal of the protecting groups furnished the title disaccharides.

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...

Depigmentation with tert-butyl hydroquinone using black guinea pigs.

PubMed

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

1999-01-01

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

Radiochemical study of reactions of alkyl cations with amines. I. Reactions of methyl and sec-butyl cations with diethylamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ignat`ev, I.S.; Kochina, T.A.; Nefedov, V.D.

1995-08-10

Ion-molecular gas-phase reactions of free methyl and sec-butyl cations with diethylamine were studied. These reactions proceed via two competing pathways involving formation of a condensation complex or a proton-transfer complex, the latter process predominating. 32 refs., 1 tab.

Equilibrium Polymerization of Butyl Methacrylate in Bulk and in Nanopore Confinement

NASA Astrophysics Data System (ADS)

Tian, Qian; Simon, Sindee

The equilibrium between monomer and polymer in free radical polymerization can be shifted towards monomer under nanoconfinement. This decrease in ceiling temperature is due to a decrease in the entropy associated with the constrained polymer chains, resulting in a larger negative change in entropy of reaction. Here, we investigate the equilibrium polymerization of butyl methacrylate (BMA) in bulk and in nanopore confinement with differential scanning calorimetry (DSC) using di-tert-butyl peroxide (DTBP) as initiator. This system has several advantages compare to the previously studied system of methyl methacrylate (MMA) initiated with 2,2'-azo-bis-isobutyronitrile (AIBN), namely, a reduced rate of reaction, higher boiling point of monomer, and higher initiator utilization temperature range, all of which facilitate the study of the reaction at high temperatures near the ceiling temperature. Interestingly, for BMA, there is no change in limiting conversion between material reacted in bulk and that in controlled pore glass having pore diameters of 7.5 and 50 nm. This unexpected result may be due to the greater flexibility of the PBMA chains compared to PMMA, suggesting that in the BMA/PBMA system, the degree of confinement is relatively low. Future studies will continue to investigate how the entropy change on reaction is affected by confinement.

IRIS Toxicological Review of tert-Butyl Alcohol (tert-Butanol) ...

EPA Pesticide Factsheets

In August 2013, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for TBA to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in comments on the following: Draft literature search strategies The approach for identifying studies The screening process for selecting pertinent studies The resulting list of pertinent studies Preliminary evidence tables The process for selecting studies to include in evidence tables The quality of the studies in the evidence tables The literature search strategy, which describes the processes for identifying scientific literature, contains the studies that EPA considered and selected to include in the evidence tables. The preliminary evidence tables and exposure-response arrays present the key study data in a standardized format. The evidence tables summarize the available critical scientific literature. The exposure-response figures provide a graphical representation of the responses at different levels of exposure for each study in the evidence table. EPA is undertaking a new health assessment for t-butyl alcohol (TBA) for the Integrated Risk Information System (IRIS). The outcome of this project will be a Toxicological Review and IRIS and IRIS Summary of TBA that will be entered on the IRIS database. IRIS is an EPA da

Cyclic cooperative intramolecular hydrogen bond in p-tert-butylcalix[6]arene according to FTIR spectroscopy and DFT studies

NASA Astrophysics Data System (ADS)

Furer, V. L.; Potapova, L. I.; Kovalenko, V. I.

2017-06-01

This article describes a comparative research of IR spectra and H-bonds in the p-tert-butylcalix[6]arene (TB6) and calix[6]arene (C6). IR spectra were computed for compressed cone conformation by DFT method. The assignment of the bands in the IR spectra of the TB6 and C6 was made. The effect of the bulky tert-butyl substituents on the structure and H-bonding in TB6 was established. Our research has shown that in TB6 and C6 the cyclic H-bond is realized, which ensures the existence of a compressed cone conformation. Introduction of tert-butyl substituents in TB6 leads to hardening of H-bonds. Examination of IR spectra showed that when heated TB6 remains in a compressed cone conformation. In a molecule of TB6 and C6 oxygen atoms are in a ;boat; conformation.

Solution processable 2-(trityloxy)ethyl and tert-butyl group containing amorphous molecular glasses of pyranylidene derivatives with light-emitting and amplified spontaneous emission properties

NASA Astrophysics Data System (ADS)

Zarins, Elmars; Vembris, Aivars; Misina, Elina; Narels, Martins; Grzibovskis, Raitis; Kokars, Valdis

2015-11-01

Small organic molecules with incorporated 4H-pyran-4-ylidene (pyranylidene) fragment as the π-conjugation system which bonds the electron acceptor fragment (A) with electron donor part (D) in the molecule - also well known as derivatives of 4-(dicyano-methylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran (DCM) laser dye-have attracted considerable attention of scientists as potential new generation materials for organic photonics and molecular electronics due to their low-cost fabrication possibility, flexibility and low-weight. Six glassy derivatives of 4H-pyran-4-ylidene (pyranylidene) with attached bulky 2-(trityloxy)ethyl and tert-butyl groups are described in this report. Almost all of the synthesized compounds form good optical quality transparent amorphous films from volatile organic solvents and could be obtained in good yields up to 75%. Their light emission in solution and thin solid films is in the range of 600-700 nm, they are thermally stable and show glass transition in the range of 108-158 °C. The amplified spontaneous emission threshold values of the neat films of the glassy pyranylidene derivatives vary from 155 to 450 μJ/cm2 and their HOMO and LUMO energy levels are between of those of tris(8-hydroxy quinolinato) aluminum (Alq3). The photoluminescence quantum yields of the glassy compounds are in the range from 1% to about 7.7% and their electroluminescence properties have been investigated. Therefore, glassy pyranylidene derivatives could be a very potential low-cost solution processable materials for Alq3 hosted light-amplification and light-emitting application studies.

Crystal structure of 1-iodo-3-{[4-(tert-butyl­sulfan­yl)phen­yl]ethyn­yl}azulene

PubMed Central

Förster, Sebastian; Seichter, Wilhelm; Weber, Edwin

2015-01-01

The title compound, C20H19IS, features a 1,3-disubstituted azulene involving an ethynylene elongated 4-(tert-butyl­sulfanyl)­phenyl sidearm and an iodine atom as the substituents. The azulene ring system is almost planar (r.m.s. deviation = 0.012 Å) and subtends a dihedral angle of 35.7 (1)° with the benzene ring. As a result of the inherent dipole character of the azulene core, a supra­molecular π–π dimer [separation between the centroids of the five- and seven-membered rings = 3.7632 (10) Å] with anti­parallel orientated mol­ecules can be observed in the crystal. The packing is consolidated by an unusual I⋯π(acetyl­ene) contact [I⋯Cg = 3.34 Å, C—I⋯Cg = 173.3°], and a very weak C—H⋯π inter­action is also found in the structure, with the azulene five-membered ring as the acceptor. PMID:26396788

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene IV. 3,3-Dimethyl-1,2-bis(trimethylgermyl)cyclopropene

NASA Astrophysics Data System (ADS)

Panchenko, Yu. N.; De Maré, G. R.; Abramenkov, A. V.; Baird, M. S.; Tverezovsky, V. V.; Nizovtsev, A. V.; Bolesov, I. G.

2003-06-01

The infrared (IR) and Raman spectra of 3,3-dimethyl-1,2-bis(trimethylgermyl)cyclopropene (I) were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level. The HF/6-31G*//HF6-31G* quantum mechanical force field (QMFF) was calculated and used to determine the theoretical fundamental vibrational frequencies, their predicted IR intensities, Raman activities, and Raman depolarisation ratios. Using Pulay's scaling method and the theoretical molecular geometry, the QMFF of I was scaled by a set of scaling factors comprised of elements transferred from the sets used to correct the QMFF's of 3,3-dimethylbutene-1, and 1-methyl-, 1,2-dimethyl-, and 3,3-dimethylcyclopropene (17 scale factors for a 105-dimensional problem). This set of scale factors was used previously to correct the QMFF of 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene and 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene. The scaled QMFF obtained was used to solve the vibrational problem. Differential Raman cross-sections were calculated using the quantum mechanical values of the Raman activities. The appropriate theoretical spectrograms for the Raman and IR spectra of I were constructed. Assignments of the experimental vibrational spectra of I are given. They take into account the calculated potential energy distributions and the correlation between the estimations of the experimental IR and Raman intensities and Raman depolarisation ratios and the corresponding theoretical values calculated using the unscaled QMFF.

Improving the Safety of Lithium-Ion Battery via a Redox Shuttle Additive 2,5-Di- tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB).

PubMed

Leonet, Olatz; Colmenares, Luis C; Kvasha, Andriy; Oyarbide, Mikel; Mainar, Aroa R; Glossmann, Tobias; Blázquez, J Alberto; Zhang, Zhengcheng

2018-03-21

2,5-Di- tert-butyl-1,4-bis(2-methoxyethoxy)benzene (DBBB) is studied as a redox shuttle additive for overcharge protection for a 1.5 Ah graphite/C-LFP lithium-ion pouch cell for the first time. The electrochemical performance demonstrated that the protecting additive remains inert during the extended standard cycling for 4000 cycles. When a 100% overcharge is introduced in the charging protocol, the baseline cell fails rapidly during the first abusive event, whereas the cell containing DBBB additive withstands 700 overcharge cycles with 87% capacity retention and no gas evolution or cell swelling was observed. It is the first time the effectiveness of the DBBB as overcharge protection additive in a large pouch cell format is demonstrated.

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

PubMed

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

2013-03-01

Ganodermanondiol, a biologically active compound, was isolated from the Lingzhi mushroom (Ganoderma lucidum). The present study examined the protective effects of ganodermanondiol against tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity. Ganodermanondiol protected human liver-derived HepG2 cells through nuclear factor-E2-related factor 2 (Nrf2) pathway-dependent heme oxygenase-1 expressions. Moreover, ganodermanondiol increased cellular glutathione levels and the expression of the glutamine-cysteine ligase gene in a dose-dependent manner. Furthermore, ganodermanondiol exposure enhanced the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and its upstream kinase activators, LKB1 and Ca(2+)/calmodulin-dependent protein kinase-II (CaMKII). This study indicates that ganodermanondiol exhibits potent cytoprotective effects on t-BHP-induced hepatotoxicity in human liver-derived HepG2 cells, presumably through Nrf2-mediated antioxidant enzymes and AMPK. Copyright © 2012 Elsevier Ltd. All rights reserved.

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...

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...

Catalytic Activity of μ-Carbido-Dimeric Iron(IV) Octapropylporphyrazinate in the 3,5,7,2',4'-Pentahydroxyflavone Oxidation Reaction with tert-Butyl Hydroperoxide

NASA Astrophysics Data System (ADS)

Tyurin, D. V.; Zaitseva, S. V.; Kudrik, E. V.

2018-05-01

It is found for the first time that μ-carbido-dimeric iron(IV) octapropylporphyrazinate displays catalytic activity in the oxidation reaction of natural flavonol morin with tert-butyl hydroperoxide, with the catalyst being stable under conditions of the reaction. The kinetics of this reaction are studied. It is shown the reaction proceeds via tentative formation of a complex between the catalyst and the oxidant, followed by O‒O bond homolytic cleavage. The kinetics of the reaction is described in the coordinates of the Michaelis-Menten equation. A linear dependence of the apparent reaction rate constant on the concentration of the catalyst is observed, testifying to its participation in the limiting reaction step. The equilibrium constants and rates of interaction are found. A mechanism is proposed for the reaction on the basis of the experimental data.

A National survey of methyl tert-butyl ether and other volatile organic compounds in drinking-water sources: Results of the random source-water survey

USGS Publications Warehouse

Grady, Stephen J.

2002-01-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Steele, W.V.

2002-07-01

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

Congested ferrocenyl polyphosphanes bearing electron-donating or electron-withdrawing phosphanyl groups: assessment of metallocene conformation from NMR spin couplings and use in palladium-catalyzed chloroarenes activation.

PubMed

Mom, Sophal; Beaupérin, Matthieu; Roy, David; Royer, Sylviane; Amardeil, Régine; Cattey, Hélène; Doucet, Henri; Hierso, J-C

2011-11-21

The synthesis of novel substituted cyclopentadienyl salts that incorporate both a congested branched alkyl group (tert-butyl, (triphenyl)methyl, or tri(4-tert-butyl)phenylmethyl) and a phosphanyl group is reported. The introduction of either electron-withdrawing or electron-donating substituents (furyl, i-propyl, cyclohexyl, tert-butyl) on P atoms was generally achieved in high yield. The modular synthesis of ferrocenyl polyphosphanes from an assembly of these cyclopentadienyl salts was investigated, leading to the formation of new triphosphanes (denoted as 9-12) and diphosphanes (denoted as 14-16). The resulting phosphanes are not sensitive to air or moisture, even when electron-rich substituents are present. This set of polyphosphanes displays varied conformational features, which are discussed in the light of their multinuclear NMR characterization in solution and of the X-ray solid state structure of the representative triphosphane 1,2-bis(diphenylphosphanyl)-1'-(diisopropylphosphanyl)-3'-(triphenyl)methyl-4-tert-butyl ferrocene, 11. In particular, the existence of a range of significantly different nonbonded ("through-space", TS) spin-spin coupling constants between heteroannular P atoms, for the triphosphanes of this class, allowed their preferred conformation in solution to be appraised. The study evidences an unanticipated flexibility of the ferrocene platform, despite the presence of very congested tert-butyl and trityl groups. Herein, we show that, contrary to our first belief, the preferred conformation for the backbone of ferrocenyl polyphosphanes can not only depend on the hindrance of the groups decorating the cyclopentadienyl rings but is also a function of the substituents of the phosphanyl groups. The interest of these robust phosphanes as ligands was illustrated in palladium catalysis for the arylation of n-butyl furan with chloroarenes, using direct C-H activation of the heteroaromatic in the presence of low metal/ligand loadings (0.5-1.0 mol�

Flash Pyrolysis of t-Butyl Hydroperoxide and Di-t-butyl Peroxide: Evidence of Roaming in the Decomposition of Organic Hydroperoxides.

PubMed

Jones, Paul J; Riser, Blake; Zhang, Jingsong

2017-10-19

Thermal decomposition of t-butyl hydroperoxide and di-t-butyl peroxide was investigated using flash pyrolysis (in a short reaction time of <100 μs) and vacuum-ultraviolet (λ = 118.2 nm) single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS) at temperatures up to 1120 K and quantum computational methods. Acetone and methyl radical were detected as the predominant products in the initial decomposition of di-t-butyl peroxide via O-O bond fission. In the initial dissociation of t-butyl hydroperoxide, acetone, methyl radical, isobutylene, and isobutylene oxide products were identified. The novel detection of the unimolecular formation of isobutylene oxide, as supported by the computational study, was found to proceed via a roaming hydroxyl radical facilitated by a hydrogen-bonded intermediate. This new pathway could provide a new class of reactions to consider in the modeling of the low temperature oxidation of alkanes.

Difunctionalization of alkenes with iodine and tert-butyl hydroperoxide (TBHP) at room temperature for the synthesis of 1-(tert-butylperoxy)-2-iodoethanes.

PubMed

Wang, Hao; Chen, Cui; Liu, Weibing; Zhu, Zhibo

2017-01-01

We developed a direct vicinal difunctionalization of alkenes with iodine and TBHP at room temperature. This iodination and peroxidation in a one-pot synthesis produces 1-( tert -butylperoxy)-2-iodoethanes, which are inaccessible through conventional synthetic methods. This method generates multiple radical intermediates in situ and has excellent regioselectivity, a broad substrate scope and mild conditions. The iodine and peroxide groups of 1-( tert -butylperoxy)-2-iodoethanes have several potential applications and allow further chemical modifications, enabling the preparation of synthetically valuable molecules.

Synthesis of methyl 2-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside and methyl 2-O-alpha-D-talopyranosyl-alpha-D-talopyranoside.

PubMed

Jain, R K; Dubey, R; Abbas, S A; Matta, K L

1987-03-15

Treatment of methyl 3-O-benzyl-2-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha-D- mannopyranoside (1) with tert-butyldiphenylsilyl chloride in N,N-dimethylformamide afforded methyl 3-O-benzyl-6-O-tert-butyldiphenylsilyl-2-O-(2,3,4,6-tetra-O-acetyl -alpha-D- mannopyranosyl)-alpha-D-mannopyranoside (2). Oxidation of 2 with pyridinium chlorochromate, followed by reduction of the carbonyl group, and subsequent O-deacetylation afforded methyl 3-O-benzyl-6-O-tert-butyldiphenylsilyl-2-O-alpha-D-mannopyranosyl- alpha-D- talopyranoside (5). Cleavage of the tert-butyldiphenylsilyl group of 5 with tetrabutylammonium fluoride in oxolane, followed by hydrogenolysis, gave methyl 2-O-alpha-D-mannopyranosyl-alpha-D-talopyranoside (7). O-Deacetylation of 1 gave methyl 3-O-benzyl-2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside (8). Treatment of 8 with tert-butyldiphenylsilyl chloride afforded a 6,6'-disilyl derivative, which was converted into a 2',3'-O-isopropylidene derivative, and then further oxidized with pyridinium chlorochromate. The resulting diketone was reduced and removal of the protecting groups gave methyl 2-O-alpha-D-talopyranosyl-alpha-D-talopyranoside (15). The structures of both 7 and 15 were established by 13C-n.m.r. spectroscopy.

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

NASA Astrophysics Data System (ADS)

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

2016-06-01

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

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

NASA Astrophysics Data System (ADS)

Sert, Yusuf; Singer, L. M.; Findlater, M.; Doğan, Hatice; Çırak, Ç.

2014-07-01

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.

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

PubMed Central

Rwei, Syang-Peng; Chen, Yu-Ming; Chiang, Whe-Yi; Ting, Yi-Tien

2017-01-01

A UV-curable, flame-retardant monomer, DAPP (bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl-phosphate), was synthesized based on BPDCP (4-tert-butylphenyl-dichloro phosphate) and HEA (2-hydroxy ethyl acrylate). DAPP was blended with regular bisphenol A epoxy acrylate (BAEA) in various ratios to yield various phosphorus contents. The TGA-IR (thermogravimetric analyzer interface with an infrared spectrometer) results demonstrate that compounding 30 mol % DAPP with BAEA significantly reduced the amount of released CO gas. In contrast, the peak intensity of CO2 is independent of phosphorus content. The limiting oxygen index (LOI), reaching the saturated value of 26, and the heat release rate (HRR) measured using a cone-calorimeter, 156.43 KW/m2, confirm the saturation point when 30 mol % DAPP was compounded into BAEA. A study of the kinetics of pyrolysis reveals that Ea decreases as the phosphorus content increases. Both the TGA-IR and pyrolysis results reveal that the phosphorus compound DAPP is easily decomposed during the initial stage of burning to form an insulating layer, which inhibits further burning of the resin and the consequent release of other flammable gases. PMID:28772562

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

PubMed

Munjal, Bhushan; Bansal, Arvind K

2015-01-01

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

Development and application of a rat PBPK model to elucidate kidney and liver effects induced by ETBE and tert-butanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salazar, Keith D., E-mail: Salazar.keith@epa.gov; Brinkerhoff, Christopher J., E-mail: Brinkerhoff.Chris@epa.gov; Lee, Janice S., E-mail: Lee.JaniceS@epa.gov

Subchronic and chronic studies in rats of the gasoline oxygenates ethyl tert-butyl ether (ETBE) and tert-butanol (TBA) report similar noncancer kidney and liver effects but differing results with respect to kidney and liver tumors. Because TBA is a major metabolite of ETBE, it is possible that TBA is the active toxic moiety in all these studies, with reported differences due simply to differences in the internal dose. To test this hypothesis, a physiologically-based pharmacokinetic (PBPK) model was developed for ETBE and TBA to calculate internal dosimetrics of TBA following either TBA or ETBE exposure. This model, based on earlier PBPKmore » models of methyl tert-butyl ether (MTBE), was used to evaluate whether kidney and liver effects are consistent across routes of exposure, as well as between ETBE and TBA studies, on the basis of estimated internal dose. The results demonstrate that noncancer kidney effects, including kidney weight changes, urothelial hyperplasia, and chronic progressive nephropathy (CPN), yielded consistent dose–response relationships across routes of exposure and across ETBE and TBA studies using TBA blood concentration as the dose metric. Relative liver weights were also consistent across studies on the basis of TBA metabolism, which is proportional to TBA liver concentrations. However, kidney and liver tumors were not consistent using any dose metric. These results support the hypothesis that TBA mediates the noncancer kidney and liver effects following ETBE administration; however, additional factors besides internal dose are necessary to explain the induction of liver and kidney tumors. - Highlights: • We model two metabolically-related fuel oxygenates to address toxicity data gaps. • Kidney and liver effects are compared on an internal dose basis. • Noncancer kidney effects are consistent using TBA blood concentration. • Liver weight changes are consistent using TBA metabolic rate. • Kidney and liver tumors are not

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

NASA Astrophysics Data System (ADS)

Banerjee, Saikat; Bagchi, Biman

2013-10-01

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

Intriguing Morphology Evolution from Noncrosslinked Poly(tert-butyl acrylate) Seeds with Polar Functional Groups in Soap-Free Emulsion Polymerization of Styrene.

PubMed

Wang, Lu; Pan, Mingwang; Song, Shaofeng; Zhu, Lei; Yuan, Jinfeng; Liu, Gang

2016-08-09

Herein, we demonstrate a facile approach to prepare anisotropic poly(tert-butyl acrylate)/polystyrene (PtBA/PS) composite particles with controllable morphologies by soap-free seeded emulsion polymerization (SSEP). In the first step, noncrosslinked PtBA seeds with self-stabilizing polar functional groups (e.g., ester groups and radicals) are synthesized by soap-free emulsion polymerization. During the subsequent SSEP of styrene (St), PS bulges are nucleated on the PtBA seeds due to the microphase separation confined in the latex particles. The morphology evolution of PtBA/PS composite particles is tailored by varying the monomer/seed feed ratio, polymerization time, and polymerization temperature. Many intriguing morphologies, including hamburger-like, litchi-like, mushroom-like, strawberry-like, bowl-like, and snowman-like, have been acquired for PtBA/PS composite particles. The polar groups on the PtBA seed surface greatly influence the formation and further merging of PS/St bulges during the polymerization. A possible formation mechanism is proposed on the basis of experimental results. These complex composite particles are promising for applications in superhydrophobic coatings.

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).

TSA-induced DNMT1 down-regulation represses hTERT expression via recruiting CTCF into demethylated core promoter region of hTERT in HCT116.

PubMed

Choi, Jee-Hye; Min, Na Young; Park, Jina; Kim, Jin Hong; Park, Soo Hyun; Ko, Young Jong; Kang, Yoonsung; Moon, Young Joon; Rhee, Sangmyung; Ham, Seung Wook; Park, Ae Ja; Lee, Kwang-Ho

2010-01-01

Trichostatin A (TSA), an inhibitor of histone deacetylase, is a well-known antitumor agent that effectively and selectively induces tumor growth arrest and apoptosis. Recently, it was reported that hTERT is one of the primary targets for TSA-induced apoptosis in cancer cells but the mechanism of which has not yet been elucidated. In the present study, to better understand the epigenetic regulation mechanism responsible for the repression of hTERT by TSA, we examined expression of hTERT in the HCT116 colon cancer cell line after treatment with TSA and performed site-specific CpG methylation analysis of the hTERT promoter. We found that TSA-induced the demethylation of site-specific CpGs on the promoter of hTERT, which was caused by down-regulation of DNA methyltransferase 1 (DNMT1). Among the demethylated region, the 31st-33rd CpGs contained a binding site for CTCF, an inhibitor of hTERT transcription. ChIP analysis revealed that TSA-induced demethylation of the 31st-33rd CpGs promoted CTCF binding on hTERT promoter, leading to repression of hTERT. Taken together, down-regulation of DNMT1 by TSA caused demethylation of a CTCF binding site on the hTERT promoter, the result of which was repression of hTERT via recruitment of CTCF to the promoter. Copyright 2009 Elsevier Inc. All rights reserved.

Enantioselective Reduction of Ketones Catalyzed by Rare-Earth Metals Complexed with Phenoxy Modified Chiral Prolinols.

PubMed

Song, Peng; Lu, Chengrong; Fei, Zenghui; Zhao, Bei; Yao, Yingming

2018-06-01

Enantioselective reduction of ketones and α,β-unsaturated ketones by pinacolborane (HBpin) has been well-established by using chiral rare-earth metal catalysts with phenoxy modified prolinols. A number of highly optically active alcohols were obtained from reduction of simple ketones catalyzed by ytterbium complex 1 [L 4 Yb(L 4 H)] (H 2 L 4 = ( S)-2- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol). Moreover, α,β-unsaturated ketones were selectively reduced to a wide range of chiral allylic alcohols with excellent yields, high enantioselectivity, and complete chemoselectivity, catalyzed by a single component chiral ytterbium complex 2 [L 1 Yb(L 1 H)] (H 2 L 1 = ( S)-2,4-di- tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol).

Ab initio/DFT/GIAO-CCSD(T) calculational study of the t-butyl cation: comparison of experimental data with structures, energetics, IR vibrational frequencies, and 13C NMR chemical shifts indicating preferred C(s) conformation.

PubMed

Rasul, Golam; Chen, Jonathan L; Prakash, G K Surya; Olah, George A

2009-06-18

The C(s) conformation of the tert-butyl cation 3 was established to be the preferred global energy minimum using a combination of ab initio, DFT, and CCSD(T) methodology with correlation-consistent basis sets. The potential energy surface of methyl rotation involving the C(3v), C(s), and C(3h) forms, however, in accord with previous studies, is quite flat. The computed IR absorptions of 3 indicate that it has the greatest degree of electron donation from C-H bonds into the C(+)-C bonds. The experimental (13)C NMR chemical shifts also agree very well with the experimental data.

FT-IR, FT-Raman spectra, density functional computations of the vibrational spectra and molecular conformational analysis of 2,5-di-tert-butyl-hydroquinone

NASA Astrophysics Data System (ADS)

Subramanian, N.; Sundaraganesan, N.; Dereli, Ö.; Türkkan, E.

2011-12-01

The purpose of finding conformer among six different possible conformers of 2,5-di-tert-butyl-hydroquinone (DTBHQ), its equilibrium geometry and harmonic wavenumbers were calculated by the B3LYP/6-31G(d,p) method. The infrared and Raman spectra of DTBHQ were recorded in the region 400-4000 cm -1 and 50-3500 cm -1, respectively. In addition, the IR spectra in CCl 4 at various concentrations of DTBHQ are also recorded. The computed vibrational wavenumbers were compared with the IR and Raman experimental data. Computational calculations at B3LYP level with two different basis sets 6-31G(d,p) and 6-311++G(d,p) are also employed in the study of the possible conformer of DTBHQ. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA 4 program. The general agreement between the observed and calculated frequencies was established.

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

USGS Publications Warehouse

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

2004-01-01

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

Biotic and abiotic transformations of methyl tertiary butyl ether (MTBE).

PubMed

Fischer, Axel; Oehm, Claudia; Selle, Michael; Werner, Peter

2005-11-01

Methyl tertiary butyl ether (MTBE) is a fuel additive which is used all over the world. In recent years it has often been found in groundwater, mainly in the USA, but also in Europe. Although MTBE seems to be a minor toxic, it affects the taste and odour of water at concentrations of < 30 microg/L. Although MTBE is often a recalcitrant compound, it is known that many ethers can be degraded by abiotic means. The aim of this study was to examine biotic and abiotic transformations of MTBE with respect to the particular conditions of a contaminated site (former refinery) in Leuna, Germany. Groundwater samples from wells of a contaminated site were used for aerobic and anaerobic degradation experiments. The abiotic degradation experiment (hydrolysis) was conducted employing an ion-exchange resin and MTBE solutions in distilled water. MTBE, tertiary butyl formate (TBF) and tertiary butyl alcohol (TBA) were measured by a gas chromatograph with flame ionisation detector (FID). Aldehydes and organic acids were respectively analysed by a gas chromatograph with electron capture detector (ECD) and high-performance ion chromatography (HPIC). Under aerobic conditions, MTBE was degraded in laboratory experiments. Only 4 of a total of 30 anaerobic experiments exhibited degradation, and the process was very slow. In no cases were metabolites detected, but a few degradation products (TBF, TBA and formic acid) were found on the site, possibly due to the lower temperatures in groundwater. The abiotic degradation of MTBE with an ion-exchange resin as a catalyst at pH 3.5 was much faster than hydrolysis in diluted hydrochloric acid (pH 1.0). Although the aerobic degradation of MTBE in the environment seems to be possible, the specific conditions responsible are widely unknown. Successful aerobic degradation only seems to take place if there is a lack of other utilisable compounds. However, MTBE is often accompanied by other fuel compounds on contaminated sites and anaerobic conditions

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

PubMed

Sert, Yusuf; Singer, L M; Findlater, M; Doğan, Hatice; Çırak, Ç

2014-07-15

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. Copyright © 2014 Elsevier B.V. All rights reserved.

Draft genome sequence of Methylibium sp. strain T29, a novel fuel oxygenate-degrading bacterial isolate from Hungary.

PubMed

Szabó, Zsolt; Gyula, Péter; Robotka, Hermina; Bató, Emese; Gálik, Bence; Pach, Péter; Pekker, Péter; Papp, Ildikó; Bihari, Zoltán

2015-01-01

Methylibium sp. strain T29 was isolated from a gasoline-contaminated aquifer and proved to have excellent capabilities in degrading some common fuel oxygenates like methyl tert-butyl ether, tert-amyl methyl ether and tert-butyl alcohol along with other organic compounds. Here, we report the draft genome sequence of M. sp. strain T29 together with the description of the genome properties and its annotation. The draft genome consists of 608 contigs with a total size of 4,449,424 bp and an average coverage of 150×. The genome exhibits an average G + C content of 68.7 %, and contains 4754 protein coding and 52 RNA genes, including 48 tRNA genes. 71 % of the protein coding genes could be assigned to COG (Clusters of Orthologous Groups) categories. A formerly unknown circular plasmid designated as pT29A was isolated and sequenced separately and found to be 86,856 bp long.

Toxicokinetics of ethers used as fuel oxygenates.

PubMed

Dekant, W; Bernauer, U; Rosner, E; Amberg, A

2001-10-15

The toxicokinetics and biotransformation of methyl-tert.butyl ether (MTBE), ethyl-tert.butyl ether (ETBE) and tert.amyl-methyl ether (TAME) in rats and humans are summarized. These ethers are used as gasoline additives in large amounts, and thus, a considerable potential for human exposure exists. After inhalation exposure MTBE, ETBE and TAME are rapidly taken up by both rats and humans; after termination of exposure, clearance by exhalation and biotransformation to urinary metabolites is rapid in rats. In humans, clearance by exhalation is slower in comparison to rats. Biotransformation of MTBE and ETBE is both qualitatively and quantitatively similar in humans and rats after inhalation exposure under identical conditions. The extent of biotransformation of TAME is also quantitatively similar in rats and humans; the metabolic pathways, however, are different. The results suggest that reactive and potentially toxic metabolites are not formed during biotransformation of these ethers and that toxic effects of these compounds initiated by covalent binding to cellular macromolecules are unlikely.

APMP.QM-S8: determination of mass fraction of benzoic acid, methyl paraben and n-butyl paraben in soy sauce

NASA Astrophysics Data System (ADS)

Teo, Tang Lin; Gui, Ee Mei; Lu, Ting; Sze Cheow, Pui; Giannikopoulou, Panagiota; Kakoulides, Elias; Lampi, Evgenia; Choi, Sik-man; Yip, Yiu-chung; Chan, Pui-kwan; Hui, Sin-kam; Wollinger, Wagner; Carvalho, Lucas J.; Garrido, Bruno C.; Rego, Eliane C. P.; Ahn, Seonghee; Kim, Byungjoo; Li, Xiuqin; Guo, Zhen; Styarini, Dyah; Aristiawan, Yosi; Putri Ramadhaningtyas, Dillani; Aryana, Nurhani; Ebarvia, Benilda S.; Dacuaya, Aaron; Tongson, Alleni; Aganda, Kim Christopher; Junvee Fortune, Thippaya; Tangtrirat, Pradthana; Mungmeechai, Thanarak; Ceyhan Gören, Ahmet; Gündüz, Simay; Yilmaz, Hasibe

2017-01-01

The supplementary comparison APMP.QM-S8: determination of mass fraction of benzoic acid, methyl paraben and n-butyl paraben in soy sauce was coordinated by the Health Sciences Authority, Singapore under the auspices of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM). Ten national metrology institutes (NMIs) or designated institutes (DIs) participated in the comparison. All the institutes participated in the comparison for benzoic acid, while six NMIs/DIs participated in the comparison for methyl paraben and n-butyl paraben. The comparison was designed to enable participating institutes to demonstrate their measurement capabilities in the determination of common preservatives in soy sauce, using procedure(s) that required simple sample preparation and selective detection in the mass fraction range of 50 to 1000 mg/kg. The demonstrated capabilities can be extended to include other polar food preservatives (e.g. sorbic acid, propionic acid and other alkyl benzoates) in water, aqueous-based beverages (e.g. fruit juices, tea extracts, sodas, sports drinks, etc) and aqueous-based condiments (e.g. vinegar, fish sauce, etc). Liquid--liquid extraction and/or dilution were applied, followed by instrumental analyses using LC-MS/MS, LC-MS, GC-MS (with or without derivatisation) or HPLC-DAD. Isotope dilution mass spectrometry was used for quantification, except in the case of a participating institute, where external calibration method was used for quantification of all three measurands. The assigned Supplementary Comparison Reference Values (SCRVs) were the medians of ten results for benzoic acid, six results for methyl paraben and six results for n-butyl paraben. Benzoic acid was assigned a SCRV of 154.55 mg/kg with a combined standard uncertainty of 0.94 mg/kg, methyl paraben was assigned a SCRV of 100.95 mg/kg with a combined standard uncertainty of 0.40 mg/kg, and n-butyl paraben was assigned a SCRV of 99.05 mg

40 CFR 721.10072 - Benzene, 1,1′-methylenebis[4-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl...

Code of Federal Regulations, 2010 CFR

2010-07-01

...-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl ester, poly[oxy(methyl-1,2-ethanediyl)], .alpha.-hydro-.omega.-hydroxy-, oxirane, alkyl-, polymer with oxirane, ether with propanepolyol and...-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl ester, poly[oxy(methyl-1,2-ethanediyl...

The relationship between crystal structure and methyl and t-butyl group dynamics in van der Waals organic solids

NASA Astrophysics Data System (ADS)

Beckmann, Peter A.; Paty, Carol; Allocco, Elizabeth; Herd, Maria; Kuranz, Carolyn; Rheingold, Arnold L.

2004-03-01

We report x-ray diffractometry in a single crystal of 2-t-butyl-4-methylphenol (TMP) and low-frequency solid state nuclear magnetic resonance (NMR) proton relaxometry in a polycrystalline sample of TMP. The x-ray data show TMP to have a monoclinic, P21/c, structure with eight molecules per unit cell and two crystallographically inequivalent t-butyl group (C(CH3)3) sites. The proton spin-lattice relaxation rates were measured between 90 and 310 K at NMR frequencies of 8.50, 22.5, and 53.0 MHz. The relaxometry data is fitted with two models characterizing the dynamics of the t-butyl groups and their constituent methyl groups, both of which are consistent with the determined x-ray structure. In addition to presenting results for TMP, we review previously reported x-ray diffractometry and low-frequency NMR relaxometry in two other van der Waals solids which have a simpler structure. In both cases, a unique model for the reorientational dynamics was found. Finally, we review a similar previously reported analysis in a van der Waals solid with a very complex structure in which case fitting the NMR relaxometry requires very many parameters and serves mainly as a flag for a careful x-ray diffraction study.

40 CFR 799.5000 - Testing consent orders for substances and mixtures with Chemical Abstract Service Registry Numbers.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Environmental Releases Report November 18, 1994. 112-35-6 Triethylene glycol monomethyl ether Health effects... Health effects November 23, 1993. 994-05-8 Tertiary-amyl methyl ether Health effects March 21, 1995. 1634-04-4 Methyl tert-butyl ether Health effects March 31, 1988. 2461-18-9 Lauryl glycidyl ether 1 Health...

Application of a source apportionment model in consideration of volatile organic compounds in an urban stream

USGS Publications Warehouse

Asher, W.E.; Luo, W.; Campo, K.W.; Bender, D.A.; Robinson, K.W.; Zogorski, J.S.; Pankow, J.F.

2007-01-01

Position-dependent concentrations of trichloroethylene and methyl-tert-butyl ether are considered for a 2.81-km section of the Aberjona River in Massachusetts, USA. This river flows through Woburn and Winchester (Massachusetts, USA), an area that is highly urbanized, has a long history of industrial activities dating to the early 1800s, and has gained national attention because of contamination from chlorinated solvent compounds in Woburn wells G and H. The river study section is in Winchester and begins approximately five stream kilometers downstream from the Woburn wells superfund site. Approximately 300 toxic release sites are documented in the watershed upstream from the terminus of the study section. The inflow to the river study section is considered one source of contamination. Other sources are the atmosphere, a tributary flow, and groundwater flows entering the river; the latter are categorized according to stream zone (1, 2, 3, etc.). Loss processes considered include outflows to groundwater and water-to-atmosphere transfer of volatile compounds. For both trichloroethylene and methyl-rerf-butyl ether, degradation is neglected over the timescale of interest. Source apportionment fractions with assigned values ??inflow, ??1, ??2, ??3, etc. are tracked by a source apportionment model. The strengths of the groundwater and tributary sources serve as fitting parameters when minimizing a reduced least squares statistic between water concentrations measured during a synoptic study in July 2001 versus predictions from the model. The model fits provide strong evidence of substantial unknown groundwater sources of trichloroethylene and methyl-tert-butyl ether amounting to tens of grams per day of trichloroethylene and methyl-tert-butyl ether in the river along the study section. Modeling in a source apportionment manner can be useful to water quality managers allocating limited resources for remediation and source control. ?? 2007 SETAC.

Dielectric properties of binary mixtures of methyl iso butyl ketone and amino silicone oil

NASA Astrophysics Data System (ADS)

Shah, K. N.; Rana, V. A.; Trivedi, C. M.; Vankar, H. P.

2017-05-01

Dielectric permittivity ɛ*(ω) = ɛ' - jɛ″ of the binary mixtures of the methyl iso butyl ketone and amino silicone oil in the frequency range 100 Hz to 2 MHz were measured using precision LCR meter at 305.15 K. Relative complex permittivity spectra in the frequency range 100 Hz to 2 MHz, of the mixture solutions of varying concentrations is reported. Determined values of the permittivity at optical frequency of all the samples are also reported. The dielectric parameters are used to gain information about the effect of concentration variation of components of the mixtures on the dielectric properties. It also provides the information about electrode polarization phenomena taking place under the low frequency A.C. electric field.

Sensitive multiresidue method by HS-SPME/GC-MS for 10 volatile organic compounds in urine matrix: a new tool for biomonitoring studies on children.

PubMed

Antonucci, Arianna; Vitali, Matteo; Avino, Pasquale; Manigrasso, Maurizio; Protano, Carmela

2016-08-01

A HS-SPME method coupled with GC-MS analysis has been developed for simultaneously measuring the concentration of 10 volatile organic compounds (VOCs) (benzene, toluene, ethylbenzene, o-, m-, and p-xylene, methyl tert-butyl ether, ethyl tert-butyl ether, 2-methyl-2-butyl methyl ether, and diisopropyl ether) in urine matrix as a biomonitoring tool for populations at low levels of exposure to such VOCs. These compounds, potentially toxic for human health, are common contaminants of both outdoor and indoor air, as they are released by autovehicular traffic; some of them are also present in environmental tobacco smoke (ETS). Thus, the exposure to these pollutants cannot be neglected and should be assessed. The low limits of detection and quantification (LODs and LOQs <6.5 and 7.5 ng L(-1), respectively) and the high reproducibility (CVs <4 %) make the developed method suited for biomonitoring populations exposed at low levels such as children. Further, the method is cost-effective and low in time-consumption; therefore, it is useful for investigating large populations. It has been applied to children exposed to traffic pollution and/or ETS; the relevant results are reported, and the relevant implications are discussed.

Organophosphazenes. 15. Reactions of Hexafluorocyclotriphosphazene with Tert- and n-Butyl Lithium Reagents

DTIC Science & Technology

1981-12-04

H ECU’ITY CLASSIFICATION OF THIS PAGE (When frl,* IFnfered) REPORT DOCUMENTATION PAGE - RE INSTRUCTIONSBEFORE COMPLETING FORM 1. REPORT NUMBER 2...GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER 10 _ _ _ _V11 * 4. TITLE (and Subtitle) S. TYPE OF REPORT I PERIOD COVERED Organoohosphazenes. 15...Reactions of Hexafluro- Technical Report cvclotriphosDhazene with Tert- and n-Butvl Lithium Reagents . PERFORMING ORG. REPORT NUMSER 7. AUTHOR•,) S

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

NASA Astrophysics Data System (ADS)

Richaud, Emmanuel

2014-10-01

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

Crystal structure of (2,2′-bi­pyridine-κ2 N,N′)bis­(3,5-di-tert-butyl-o-benzo­quinonato-κ2 O,O′)ruthenium(II)

PubMed Central

Ali, Akram; Potaskalov, Vadim A.

2017-01-01

In the title mononuclear complex, [Ru(C14H20O2)2(C10H8N2)], the RuII ion has a distorted octa­hedral coordination environment defined by two N atoms of the chelating 2,2′-bi­pyridine ligand and four O atoms from two 3,5-di-tert-butyl-o-benzo­quinone ligands. In the crystal, the complex mol­ecules are linked by inter­molecular C—H⋯O hydrogen bonds and π–π stacking inter­actions between the 2,2′-bi­pyridine ligands [centroid–centroid distance = 3.538 (3) Å], resulting in a layer structure extending parallel to the ab plane. PMID:28316832

Salvianic acid A sodium protects HUVEC cells against tert-butyl hydroperoxide induced oxidative injury via mitochondria-dependent pathway.

PubMed

Jia, Dan; Li, Tian; Chen, Xiaofei; Ding, Xuan; Chai, Yifeng; Chen, Alex F; Zhu, Zhenyu; Zhang, Chuan

2018-01-05

Salvianic acid A (Danshensu) is a major water-soluble component extracted from Salvia miltiorrhiza (Danshen), which has been widely used in clinic in China for treatment of cardiovascular diseases (CVDs). This study aimed to investigate the protective effects of salvianic acid A sodium (SAAS) against tert-butyl hydroperoxide (t-BHP) induced human umbilical vein endothelial cell (HUVEC) oxidative injury and the underlying molecular mechanisms. In the antioxidant activity-assessing model, SAAS pretreatment significantly ameliorated the cell growth inhibition and apoptosis induced by t-BHP. An ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) based-metabolic profiling was developed to investigate the metabolic changes of HUVEC cells in response to t-BHP and SAAS. The results revealed that t-BHP injury upregulated 13 metabolites mainly involved in tryptophan metabolism and phenylalanine metabolism which were highly correlated with mitochondrial function and oxidative stress, and 50 μM SAAS pretreatment effectively reversed these metabolic changes. Further biomedical research indicated that SAAS pretreatment reduced the t-BHP induced increase of lactate dehydrogenase (LDH), intracellular reactive oxygen species (ROS), malondialdehyde (MDA) and mitochondrial membrane potential (MMP), and the decrease of key antioxidant enzymes through mitochondria antioxidative pathways via JAK2/STAT3 and PI3K/Akt/GSK-3β signalings. Taken together, our results suggested that SAAS may protect HUVEC cells against t-BHP induced oxidative injury via mitochondrial antioxidative defense system. Copyright © 2017 Elsevier B.V. All rights reserved.

FENTON-DRIVEN CHEMICAL REGENERATION OF MTBE-SPENT GAC

EPA Science Inventory

Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was chemically regenerated utilizing the Fenton mechanism. Two successive GAC regeneration cycles were performed involving iterative adsorption and oxidation processes: MTBE was adsorbed to the GAC, oxidized, r...

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

PubMed Central

Senge, Mathias O.; Dahms, Katja

2014-01-01

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

Fenton-Driven Regeneration of MTBE-spent Granular Activated Carbon

EPA Science Inventory

Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto activated carbon and Fenton-driven oxidation regeneration of the spent-GAC...

The TERT promoter SNP rs2853669 decreases E2F1 transcription factor binding and increases mortality and recurrence risks in liver cancer.

PubMed

Ko, Eunkyong; Seo, Hyun-Wook; Jung, Eun Sun; Kim, Baek-hui; Jung, Guhung

2016-01-05

A common single-nucleotide polymorphism in the telomerase reverse transcriptase (TERT) promoter, rs2853669 influences patient survival rates and the risk of developing cancer. Recently, several lines of evidence suggest that the rs2853669 suppresses TERT promoter mutation-mediated TERT expression levels and cancer mortality as well as recurrence rates. However, no reports are available on the impact of rs2853669 on TERT expression in hepatocellular carcinoma (HCC) and its association with patient survival. Here, we found that HCC-related overall and recurrence-free survival rates were not associated with TERT promoter mutation individually, but rs2853669 and the TERT promoter mutation in combination were associated with poor survival rates. TERT mRNA expression and telomere fluorescence levels were greater in patients with HCC who had both the combination. The combination caused TERT promoter methylation through regulating the binding of DNA methyltransferase 1 and histone deacetylase 1 to the TERT promoter in HCC cell lines. The TERT expression level was significantly higher in HCC tumor with a methylated promoter than in that with an unmethylated promoter. In conclusion, we demonstrate a substantial role for the rs2853669 in HCC with TERT promoter mutation, which suggests that the combination of the rs2853669 and the mutation indicate poor prognoses in liver cancer.

PRODUCTS OF THE GAS-PHASE REACTIONS OF THE OH RADICAL WITH N-BUTYL METHYL ETHER AND 2-ISOPROPOXYETHANOL: REACTIONS OF ROC(O)< RADICALS. (R825252)

EPA Science Inventory

The products of the gas-phase reactions of the OH radical with n-butyl methyl ether and 2-isopropoxyethanol in the presence of NO have been investigated at 298 ? 2 K and 740 Torr total pressure of air by gas chromatography and in situ atmospheric pressure ionization...

Anaerobic biodegradability of alkylphenols and fuel oxygenates in the presence of alternative electron acceptors.

PubMed

Puig-Grajales, L; Tan, N G; van der Zee, F; Razo-Flores, E; Field, J A

2000-11-01

Alkylphenols and fuel oxygenates are important environmental pollutants produced by the petrochemical industry. A batch biodegradability test was conducted with selected ortho-substituted alkylphenols (2-cresol, 2,6-dimethylphenol and 2-ethylphenol), fuel oxygenates (methyl tert-butyl ether, ethyl tert-butyl ether and tert-amylmethyl ether) and tert-butyl alcohol (TBA) as model compounds. The ortho-substituted alkylphenols were not biodegraded after 100 days of incubation under methanogenic, sulfate-, or nitrate-reducing conditions. However, biodegradation of 2-cresol and 2-ethylphenol (150 mg l(-1)) was observed in the presence of Mn (IV) as electron acceptor. The biodegradation of these two compounds took place in less than 15 days and more than 90% removal was observed for both compounds. Mineralization was indicated since no UV-absorbing metabolites accumulated after 23 days of incubation. These alkylphenols were also slowly chemically oxidized by Mn (IV). No biodegradation of fuel oxygenates or TBA (1 g l(-1)) was observed after 80 or more days of incubation under methanogenic, Fe (III)-, or Mn (IV)-reducing conditions, suggesting that these compounds are recalcitrant under anaerobic conditions. The fuel oxygenates caused no toxicity towards acetoclastic methanogens activity in anaerobic granular sludge.

Mutant IDH1 expression drives TERT promoter reactivation as part of the cellular transformation process

PubMed Central

Ohba, Shigeo; Mukherjee, Joydeep; Johannessen, Tor-Christian; Mancini, Andrew; Chow, Tracy T.; Wood, Matthew; Jones, Lindsey; Mazor, Tali; Marshall, Roxanne E.; Viswanath, Pavithra; Walsh, Kyle M.; Perry, Arie; Bell, Robert J. A.; Phillips, Joanna J.; Costello, Joseph F.; Ronen, Sabrina M.; Pieper, Russell O.

2016-01-01

Mutations in the isocitrate dehydrogenase gene IDH1 are common in lower-grade glioma where they result in the production of 2-hydroxyglutarate (2HG), disrupted patterns of histone methylation and gliomagenesis. IDH1 mutations also co-segregate with mutations in the ATRX gene and the TERT promoter, suggesting that IDH mutation may drive the creation or selection of telomere-stabilizing events as part of immortalization/transformation process. To determine if and how this may occur, we investigated the phenotype of pRb/p53-deficient human astrocytes engineered with IDH1 wild-type (WT) or R132H mutant (IDH1mut) genes as they progressed through their lifespan. IDH1mut expression promoted 2HG production and altered histone methylation within 20 population doublings (PD), but had no effect on telomerase expression or telomere length. Accordingly, cells expressing either IDH1 WT or IDH1mut entered a telomere-induced crisis at PD 70. In contrast, only IDH1mut cells emerged from crisis, grew indefinitely in culture and formed colonies in soft agar and tumors in vivo. Clonal populations of post-crisis IDH1mut cells displayed shared genetic alterations, but no mutations in ATRX or the TERT promoter were detected. Instead, these cells reactivated telomerase and stabilized their telomeres in association with increased histone lysine methylation (H3K4me3) and c-Myc/Max binding at the TERT promoter. Overall, these results show that while IDH1mut does not create or select for ATRX or TERT promoter mutations, it can indirectly reactivate TERT, and in doing so contribute to astrocytic immortalization and transformation. PMID:27758882

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

PubMed

Bombach, Petra; Nägele, Norbert; Rosell, Mònica; Richnow, Hans H; Fischer, Anko

2015-04-09

Ethyl tert-butyl ether (ETBE) is an upcoming groundwater pollutant in Europe whose environmental fate has been less investigated, thus far. In the present study, we investigated the in situ biodegradation of ETBE in a fuel-contaminated aquifer using compound-specific stable isotope analysis (CSIA), and in situ microcosms in combination with total lipid fatty acid (TLFA)-stable isotope probing (SIP). In a first field investigation, CSIA revealed insignificant carbon isotope fractionation, but low hydrogen isotope fractionation of up to +14‰ along the prevailing anoxic ETBE plume suggesting biodegradation of ETBE. Ten months later, oxygen injection was conducted to enhance the biodegradation of petroleum hydrocarbons (PH) at the field site. Within the framework of this remediation measure, in situ microcosms loaded with [(13)C6]-ETBE (BACTRAP(®)s) were exposed for 119 days in selected groundwater wells to assess the biodegradation of ETBE by TLFA-SIP under the following conditions: (i) ETBE as main contaminant; (ii) ETBE as main contaminant subjected to oxygen injection; (iii) ETBE plus other PH; (iv) ETBE plus other PH subjected to oxygen injection. Under all conditions investigated, significant (13)C-incorporation into microbial total lipid fatty acids extracted from the in situ microcosms was found, providing clear evidence of ETBE biodegradation. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects on temperature and acidic pre-treatment on Fenton-driven oxidation of MTBE-spent granular activated carbon

EPA Science Inventory

Temperature-dependent mechanisms in the Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was investigated. Prior to iron (Fe) amendment to the GAC, acid-treatment altered the surface chemistry of the GAC and lowered the p...

ANAEROBIC BIODEGRADATION OF MTBE AT A GASOLINE SPILL SITE

EPA Science Inventory

To manage risk or to implement natural attenuation as a remedy, regulatory agencies must understand the processes that attenuate methyl-tert-butyl ether (MTBE) in ground water. Most case studies and laboratory studies in the literature indicate that natural biodegradation is not ...

USE OF MEMBRANE BIOREACTOR FOR BIODEGRADATION OF MTBE IN CONTAMINATED WATER1

EPA Science Inventory

An ultrafiltration membrane bioreactor was evaluated for biodegradation of methyl tert-butyl ether (MTBE) in contaminated water. The system was fed 5 mg/L MTBE in granular activated carbon (GAC) treated Cincinnati tap water containing ample buffer and nutrients. Within 120...

Quantifying residues from postharvest fumigation of almonds and walnuts with propylene oxide

USDA-ARS?s Scientific Manuscript database

A novel analytical approach, involving solvent extraction with methyl tert-butyl ether (MTBE) followed by gas chromatography (GC), was developed to quantify residues that result from the postharvest fumigation of almonds and walnuts with propylene oxide (PPO). Verification and quantification of PPO,...

CHEMICAL DESTRUCTION OF MTBE USING FENTON'S REAGENT: EFFECT OF FERROUS IRON/HYDROGEN PEROXIDE RATIO

EPA Science Inventory

In previous laboratory experiments Fenton's Reagent (FR) was successfully used as the source of hydroxyl radicals (OH*) for chemical treatment of low concentrations of methyl tert-butyl ether (MTBE) in water. Although under certain conditions MTBE degradation levels as high as 99...

SUMMARY OF WORKSHOP ON BIODEGRADATION OF MTBE FEBRUARY 1-3, 2000

EPA Science Inventory

A workshop on biodegradation of methyl tert butyl ether (MTBE) contaminated soils and groundwater was held in Cincinnati, Ohio, February 1-2, 2000, and was sponsored by the USEPA's NRMRL and the American Petroleum Institute. Researchers in academia, industry, and government were ...

Disposition of 2,6-di-tert-butyl-4-nitrophenol (DBNP), a submarine atmosphere contaminant, in male Sprague-Dawley rats.

PubMed

Still, Kenneth R; Jung, Anne E; Ritchie, Glenn D; Jederberg, Warren W; Wilfong, Erin R; Briggs, G Bruce; Arfsten, Darryl P

2005-07-01

The phenol 2,6-di-tert-butyl-4-nitrophenol (DBNP) is a contaminant found onboard submarines and is formed by the nitration of an antioxidant present in turbine lubricating oil TEP 2190. DBNP has been found on submarine interior surfaces, on eating utensils and dishes, and on the skin of submariners. DBNP exposure is a potential health concern because it is an uncoupler of mitochondrial oxidative phosphorylation. Adult male rats were dosed once by oral gavage with 15 or 40 mg/kg DBNP mixed with 14C-DBNP in kanola oil and 0.8% v/v DMSO (n = 16/group). The distribution of 14C in major tissues was measured over time for up to 240 h post-dose. Unexpectedly, 6/16 (40%) of the rats gavaged with 40 mg/kg DBNP died within 24 h of dosing. Prostration, no auditory startle response, reduced locomotor activity, and muscular rigidity persisted in survivors for up to 8 days after dosing. For animals dosed with 15 mg/kg DBNP, radioactivity levels were significantly elevated in the following tissues 24h after dosing: fat>liver>kidneys>heart>lungs>brain>striated muscle>spleen. Radioactivity levels were elevated for fat, liver, kidney, heart, and lungs of animals euthanized 144 h post-dosing and in the liver of animals euthanized 240 h post-dosing. These findings suggest that DBNP may accumulate in the body as a result of continuous or repeat exposures of short interval to DBNP.

Bacopa monnieri protects SH-SY5Y cells against tert-Butyl hydroperoxide-induced cell death via the ERK and PI3K pathways

PubMed Central

Petcharat, Kanoktip; Singh, Meharvan; Ingkaninan, Kornkanok; Attarat, Jongrak; Yasothornsrikul, Sukkid

2017-01-01

Objective Oxidative stress plays an important role in the pathological processes of various neurodegenerative diseases. Bacopa monnieri (BM) has a potent antioxidant property. Therefore, the purpose of this study was to evaluate the neuroprotective potential of BM against SH-SY5Y neuroblastoma cell death induced by the pro-oxidant insult, tert-Butyl hydroperoxide (TBHP), and to identify possible mechanisms related to its neuroprotective action. Methods The neuroprotective effect of BM was evaluated by the degree of protection against TBHP-induced cell death in human SH-SY5Y cells that was measured by calcein-AM assay. ERK1/2 and Akt phosphorylation was evaluated by immunoblotting. Results We found that BM exhibited protection against TBHP-mediated cytotoxicity. The neuroprotective effect of BM was abolished in the presence of either ERK1/2 or PI3K inhibitors. In addition, western blotting with anti-phospho-ERK1/2 and anti-phospho-Akt antibodies showed that BM increased both ERK1/2 and Akt phosphorylation. Conclusion These results suggest that BM by activation of ERK/MAPK and PI3K/Akt signaling pathways protects SH-SY5Y cells from TBHP-induced cell death. PMID:29152617

Bacopa monnieri protects SH-SY5Y cells against tert-Butyl hydroperoxide-induced cell death via the ERK and PI3K pathways.

PubMed

Petcharat, Kanoktip; Singh, Meharvan; Ingkaninan, Kornkanok; Attarat, Jongrak; Yasothornsrikul, Sukkid

2015-01-01

Oxidative stress plays an important role in the pathological processes of various neurodegenerative diseases. Bacopa monnieri (BM) has a potent antioxidant property. Therefore, the purpose of this study was to evaluate the neuroprotective potential of BM against SH-SY5Y neuroblastoma cell death induced by the pro-oxidant insult, tert -Butyl hydroperoxide (TBHP), and to identify possible mechanisms related to its neuroprotective action. The neuroprotective effect of BM was evaluated by the degree of protection against TBHP-induced cell death in human SH-SY5Y cells that was measured by calcein-AM assay. ERK1/2 and Akt phosphorylation was evaluated by immunoblotting. We found that BM exhibited protection against TBHP-mediated cytotoxicity. The neuroprotective effect of BM was abolished in the presence of either ERK1/2 or PI3K inhibitors. In addition, western blotting with anti-phospho-ERK1/2 and anti-phospho-Akt antibodies showed that BM increased both ERK1/2 and Akt phosphorylation. These results suggest that BM by activation of ERK/MAPK and PI3K/Akt signaling pathways protects SH-SY5Y cells from TBHP-induced cell death.

[Effects of methyl tertiary butyl ether on cell cycle and cell apoptosis].

PubMed

Zhou, W; Huang, G; Zhang, H; Ye, S

2000-07-01

To explore the effects of the new gasoline additive, methyl tertiary butyl ether (MTBE) on cell cycle and cell apoptosis. Flow cytometry was used to evaluate the effect of MTBE (1, 2, 4 microl/ml, 24 h) on NIH/3T3 cell cycles; and the effect of MTBE on Hela cell apoptosis was evaluated by detecting cell survival using crystal violet staining. Flow cytometry showed that MTBE could change NIH/3T3 cell cycles, decrease the number of cells in S stage, and arrest cells at G(2) + M stage. The results suggested that MTBE could affect NIH/3T3 cell cycles and induce cell proliferation. This situation existed 48 hours after the treatment, and cell cycles came back normal 96 hours after the treatment. By detecting cell survival using crystal violet staining, we found that MTBE could inhibit the apoptosis of Hela cells which was induced by tumor necrosis factor (TNF)alpha and cycloheximide. MTBE's carcinogenicity to animals may relate to induction of cell proliferation and inhibition of cell apoptosis.

Three isomers detected for the whisky lactone: 5-butyl-4-methyl tetrahydrofuran-2-one by Fourier transform microwave spectroscopy and quantum chemical calculations

NASA Astrophysics Data System (ADS)

Kawashima, Yoshiyuki; Katsuragi, Ryusuke; Hirota, Eizi

2017-05-01

The ground-state rotational spectra of the whisky lactone (WL) : 5-butyl-4-methyl tetrahydrofuran-2-one were observed and analyzed by molecular beam Fourier transform microwave spectroscopy combined with quantum chemical calculations. We have detected three stereo-isomers: the trans-TTT form with a methyl CH3 group attached to C(4) in an equatorial position (eq) and a butyl C4H9 group to C(5) in an eq position, for which 110 b-type and 113 a-type transitions were assigned, the cis-TTT form with a CH3 to C(4) in an axial position (ax) and a C4H9 to C(5) in eq, for which 96 a-type, 101 b-type, and 45 c-type transitions were observed, and the cis-GTT form with a CH3 to C(4) in ax and a C4H9 to C(5) in eq, for which 158 a-type, 52 b-type, and 17 c-type transitions were observed, where TTT and GTT denote the conformations about the C(6)sbnd C(5), C(7)sbnd C(6), and C(8)sbnd C(7) bonds, with T and G designating trans and gauche, respectively. The rotational constants thus derived agree with the predictions made by quantum chemical calculations, MP2/6-311++G(d, p) within 1.2%. The trans-TTT form was calculated to be the most stable. The splittings due to internal rotation of the terminal methyl in the butyl group were observed for all the three stereo-isomers and were analyzed by the XIAM program to determine the threefold potential barrier V3 to be 966.4 (25), 978.8 (11), and 1098.7 (48) in cm-1 for the trans-TTT (eq, eq), the cis-TTT (ax, eq), and the cis-GTT (ax, eq) forms, respectively, to be compared with quantum chemically calculated values: 1055, 1055, and 1053 in cm-1.

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

USGS Publications Warehouse

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

2001-01-01

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

Entropy driven chain effects on ligation chemistry† †Electronic supplementary information (ESI) available: Synthetic details, applied MHKS parameters, SEC chromatograms of all samples, (HT) NMR data, experimental debonding values, SANS measurements, computational data (energy contributions and geometries in the form of Gaussian archive entries). See DOI: 10.1039/c4sc02908a Click here for additional data file.

PubMed Central

Pahnke, Kai; Brandt, Josef; Gryn'ova, Ganna; Lindner, Peter; Schweins, Ralf; Schmidt, Friedrich Georg

2015-01-01

We report the investigation of fundamental entropic chain effects that enable the tuning of modular ligation chemistry – for example dynamic Diels–Alder (DA) reactions in materials applications – not only classically via the chemistry of the applied reaction sites, but also via the physical and steric properties of the molecules that are being joined. Having a substantial impact on the reaction equilibrium of the reversible ligation chemistry, these effects are important when transferring reactions from small molecule studies to larger or other entropically very dissimilar systems. The effects on the DA equilibrium and thus the temperature dependent degree of debonding (%debond) of different cyclopentadienyl (di-)functional poly(meth-)acrylate backbones (poly(methyl methacrylate), poly(iso-butyl methacrylate), poly(tert-butyl methacrylate), poly(iso-butyl acrylate), poly(n-butyl acrylate), poly(tert-butyl acrylate), poly(methyl acrylate) and poly(isobornyl acrylate)), linked via a difunctional cyanodithioester (CDTE) were examined via high temperature (HT) NMR spectroscopy as well as temperature dependent (TD) SEC measurements. A significant impact of not only chain mass and length with a difference in the degree of debonding of up to 30% for different lengths of macromonomers of the same polymer type but – remarkably – as well the chain stiffness with a difference in bonding degrees of nearly 20% for isomeric poly(butyl acrylates) is found. The results were predicted, reproduced and interpreted via quantum chemical calculations, leading to a better understanding of the underlying entropic principles. PMID:29560194

MTBE OXIDATION BYPRODUCTS FROM THE TREATMENT OF SURFACE WATERS BY OZONATION AND UV-OZONATION

EPA Science Inventory

In recent years, there has been considerable concern over the release of methyl tert-butyl ether (MTBE), as gasoline additive, into the aquifers used as potable water sources. MTBE readily dissolves in water and has entered the environment via gasoline spills and leaking...

Effects of Temperature and Acidic Pre-Treatment on Fenton-Driven Oxidation of MTBE-Spent Granular Activated Carbon

EPA Science Inventory

Temperature-dependent mechanisms in the Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was investigated. Prior to iron (Fe) amendment to the GAC, acid-treatment altered the surface chemistry of the GAC and lowered the pH ...

Particle Size Effects on Fenton Regeneration of MTBE-spent Activated Carbon

EPA Science Inventory

Fenton-driven regeneration of spent granular activated carbon (GAC) is a developing technology that may reduce water treatment costs. In this study, the effect of GAC particle size on Fenton-driven oxidation of methyl tert-butyl ether (MTBE)-spent GAC was evaluated. The GAC was...

Abiotic Reductive Dechlorination of Tetrachloroethylene and Trichloroethylene in Anaerobic Environments

DTIC Science & Technology

2009-01-15

Measurement of Henry’s Law Constant for methyl tert-butyl ether Using Solid-phase Microextraction. Environmental Toxicology and Chemistry 2001, 20, 1625...and Environmental Microbiology 2005, 71, 3413-3419. Nirmalakhandan, N. N., R. E. Speece. QSAR Model for Predicting Henry’s Constant. Environmental

NOVEL EMBEDDED CERAMIC ELECTRODE SYSTEM TO ACTIVATE NANOSTRUCTURED TITANIUM DIOXIDE FOR DEGRADATION OF MTBE

EPA Science Inventory

A novel reactor combining a flame-deposited nanostructured titanium dioxide film and a set of embedded ceramic electrodes was designed, developed and tested for degradation of methyl tert-butyl ether (MTBE) in water. On applying a voltage to the ceramic electrodes, a surface coro...

OBSERVATIONS FROM CONTAMINANT PLUMES ON LONG ISLAND

EPA Science Inventory

The aquifers of Long Island serve as a sole source drinking water supply for the entire
local population of about three million people. Where the shallow Upper Glacial Aquifer has been contaminated with petroleum hydrocarbons and methyl tert-butyl ether (MTBE), intensive site ...

COSTS TO REMEDIATE MTBE-CONTAMINATED SITES

EPA Science Inventory

The extensive contamination of methyl tert-butyl ether (MTBE) in ground water has introduced concerns about the increased cost of remediation of MTBE releases compared to sites with BTEX only contamination. In an attempt to evaluate these costs, cost information for 311 sites wa...

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

PubMed Central

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

2014-01-01

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

LOCALIZED RECHARGE INFLUENCES ON MTBE TRANSPORT AND WELL PLACEMENT CONSIDERATIONS

EPA Science Inventory

Vertical characterization of a gasoline release site at East Patchogue, New York showed that methyl tert-butyl ether (MTBE) and aromatic plumes "dived" as they passed beneath a sand pit. That this behavior was caused by aquifer recharge was shown by two pieces of evidence. Fir...

Fenton-driven regeneration of MTBE-spent granular activated carbon - Effects of particle size and Iron Amendment Procedures

EPA Science Inventory

Fenton-driven regeneration of spent granular activated carbon (GAC) is a technology being developed to regenerate organic contaminant-spent GAC. Here, the effect of GAC particle size (>2 mm to <0.35 mm) on Fenton-driven oxidation of methyl tert-butyl ether (MTBE)-spent GAC was ev...

Iron Amendment and Fenton Oxidation of MTBE-Spent Granular Activated Carbon

EPA Science Inventory

Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves Fe amendment to the GAC to catalyze H2O2 reactions and to enhance the rate of MTBE oxidation and GAC regeneration. Four forms of iron (ferric sulfate, ferric chloride, fer...

BTEX MTBE BIOREMEDIATION: BIONETS CONTAINING ISOLITE, PM1, SOLID OXYGEN SOURCE

EPA Science Inventory

Methyl tert-Butyl Ether (MTBE), a gasoline additive, is a persistent and foul tasting contaminate that is more mobile in ground water than BTEX . It, along with BTEX, is turning up at many American crossroads. This study's objective was to determine if biologically active in sit...

MTBE BIOREMEDIATION WITH BIONETS CONTAINING ISOLITE, PMI, SOS ON AIR

EPA Science Inventory

Methyl tert-Butyl Ether (MTBE), a gasoline additive, is a persistent and foul tasting contaminant that is more mobile in ground water than BTEX. It is turning up at many American crossroads. This study's objective was to determine if biologically active in situ Bionets could bior...

COST OF MTBE REMEDIATION

EPA Science Inventory

Widespread contamination of methyl tert-butyl ether (MTBE) in ground water has raised concerns about the increased cost of remediation of MTBE releases compared to BTEX-only sites. To evaluate these cost, cost information for 311 sites was furnished by U.S. EPA Office of Undergr...

REMEDIAL COSTS FOR MTBE IN SOIL AND GROUND WATER

EPA Science Inventory

Widespread contamination of methyl tert-butyl ether (MTBE) in ground water has raised concerns about the increased cost of remediation of MTBE releases compared to BTEX-only sites. To evaluate these costs, cost information for 311 sites was furnished by U.S. EPA Office of Underg...

CONTROLLED, SHORT-TERM DERMAL AND INHALATION EXPOSURE TO MTBE AND DIBROMOCHLOROMETHANE

EPA Science Inventory

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

NIOSH Manual of Analytical Methods (third edition). Fourth supplement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-08-15

The NIOSH Manual of Analytical Methods, 3rd edition, was updated for the following chemicals: allyl-glycidyl-ether, 2-aminopyridine, aspartame, bromine, chlorine, n-butylamine, n-butyl-glycidyl-ether, carbon-dioxide, carbon-monoxide, chlorinated-camphene, chloroacetaldehyde, p-chlorophenol, crotonaldehyde, 1,1-dimethylhydrazine, dinitro-o-cresol, ethyl-acetate, ethyl-formate, ethylenimine, sodium-fluoride, hydrogen-fluoride, cryolite, sodium-hexafluoroaluminate, formic-acid, hexachlorobutadiene, hydrogen-cyanide, hydrogen-sulfide, isopropyl-acetate, isopropyl-ether, isopropyl-glycidyl-ether, lead, lead-oxide, maleic-anhydride, methyl-acetate, methyl-acrylate, methyl-tert-butyl ether, methyl-cellosolve-acetate, methylcyclohexanol, 4,4'-methylenedianiline, monomethylaniline, monomethylhydrazine, nitric-oxide, p-nitroaniline, phenyl-ether, phenyl-ether-biphenyl mixture, phenyl-glycidyl-ether, phenylhydrazine, phosphine, ronnel, sulfuryl-fluoride, talc, tributyl-phosphate, 1,1,2-trichloro-1,2,2-trifluoroethane, trimellitic-anhydride, triorthocresyl-phosphate, triphenyl-phosphate, and vinyl-acetate.

Persulfate Oxidation of MTBE- and Chloroform-Spent Granular Activated Carbon

EPA Science Inventory

Activated persulfate (Na2S2O8) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H2O2–persulfate binary mixtur...

DECISION-MAKING, SCIENCE AND GASOLINE ADDITIVES

EPA Science Inventory

Methyl-tert butyl ether (MTBE) has been used as a gasoline additive to serve two major purposes. The first use was as an octane-enhancer to replace organic lead, beginning in 1979. The second use, which began about 1992, was as an oxygenated additive to meet requirements ...

THE TRANSPORT AND FATE OF ETHANOL AND BTEX IN GROUNDWATER CONTAMINATED BY GASOHOL. (R821114)

EPA Science Inventory

Ethanol is used a component in all gasoline in Brazil, and its use could increase significantly in the U.S. to meet the requirements of the Clean Air Act Amendments. Recent problems with ground water contamination by methyl tert-butyl ether (MTBE) have made policymakers more c...

MTBE BIODEGRADATION IN A GRAVITY FLOW, HIGH-BIOMASS RETAINING BIOREACTOR

EPA Science Inventory

The aerobic biodegradation of methyl tert-butyl ether (MtBE), a widely used fuel oxygenate, was investigated using a pilot-scale biomass-retaining bioreactor called a Biomass Concentrator Reactor (BCR). The reactor was operated for a year at a flow rate of 2500 L/d on Ci...

Metabolism and elimination of methyl, iso- and n-butyl paraben in human urine after single oral dosage.

PubMed

Moos, Rebecca K; Angerer, Jürgen; Dierkes, Georg; Brüning, Thomas; Koch, Holger M

2016-11-01

Parabens are used as preservatives in personal care and consumer products, food and pharmaceuticals. Their use is controversial because of possible endocrine disrupting properties. In this study, we investigated metabolism and urinary excretion of methyl paraben (MeP), iso-butyl paraben (iso-BuP) and n-butyl paraben (n-BuP) after oral dosage of deuterium-labeled analogs (10 mg). Each volunteer received one dosage per investigated paraben separately and at least 2 weeks apart. Consecutive urine samples were collected over 48 h. In addition to the parent parabens (free and conjugated) which are already used as biomarkers of internal exposure and the known but non-specific metabolites, p-hydroxybenzoic acid (PHBA) and p-hydroxyhippuric acid (PHHA), we identified new, oxidized metabolites with hydroxy groups on the alkyl side chain (3OH-n-BuP and 2OH-iso-BuP) and species with oxidative modifications on the aromatic ring. MeP represented 17.4 % of the dose excreted in urine, while iso-BuP represented only 6.8 % and n-BuP 5.6 %. Additionally, for iso-BuP, about 16 % was excreted as 2OH-iso-BuP and for n-BuP about 6 % as 3OH-n-BuP. Less than 1 % was excreted as ring-hydroxylated metabolites. In all cases, PHHA was identified as the major but non-specific metabolite (57.2-63.8 %). PHBA represented 3.0-7.2 %. For all parabens, the majority of the oral dose captured by the above metabolites was excreted in the first 24 h (80.5-85.3 %). Complementary to the parent parabens excreted in urine, alkyl-chain-oxidized metabolites of the butyl parabens are introduced as valuable and contamination-free biomarkers of exposure.

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

NASA Astrophysics Data System (ADS)

Phillippi, Ben

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

Composition and Behavior of Fuel Ethanol

EPA Science Inventory

Ethanol usage in the United States has increased due in part to the elimination of methyl tert-butyl ether from the fuel supply and to the mandates of Congress. Two samples, one each from a wet mill and a dry mill ethanol plant, were obtained before denaturing. Each of these ...

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

USGS Publications Warehouse

Delzer, Gregory C.; Ivahnenko, Tamara

2003-01-01

The large-scale use of the gasoline oxygenate methyl tert-butyl ether (MTBE), and its high solubility, low soil adsorption, and low biodegradability, has resulted in its detection in ground water and surface water in many places throughout the United States. Studies by numerous researchers, as well as many State and local environmental agencies, have discovered high levels of MTBE in soils and ground water at leaking underground gasoline-storage-tank sites and frequent occurrence of low to intermediate levels of MTBE in reservoirs used for both public water supply and recreational boating.In response to these findings, the American Water Works Association Research Foundation sponsored an investigation of MTBE and other volatile organic compounds (VOCs) in the Nation's sources of drinking water. The goal of the investigation was to provide additional information on the frequency of occurrence, concentration, and temporal variability of MTBE and other VOCs in source water used by community water systems (CWSs). The investigation was completed in two stages: (1) reviews of available literature and (2) the collection of new data. Two surveys were associated with the collection of new data. The first, termed the Random Survey, employed a statistically stratified design for sampling source water from 954 randomly selected CWSs. The second, which is the focus of this report, is termed the Focused Survey, which included samples collected from 134 CWS source waters, including ground water, reservoirs, lakes, rivers, and streams, that were suspected or known to contain MTBE. The general intent of the Focused Survey was to compare results with the Random Survey and provide an improved understanding of the occurrence, concentration, temporal variability, and anthropogenic factors associated with frequently detected VOCs. Each sample collected was analyzed for 66 VOCs, including MTBE and three other ether gasoline oxygenates (hereafter termed gasoline oxygenates). As part of

Carcinogenicity of methyl-tertiary butyl ether in gasoline.

PubMed

Mehlman, Myron A

2002-12-01

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

[Effect of methyl tertiary butyl ether on the expression of proto-oncogenes and function genes].

PubMed

Zhou, W; Huang, G; Zhang, H

1999-05-30

Methyl tertiary butyl ether (MTBE) is a new gasoline additive, which is used to increase the combustion of gasoline and to reduce the emission of harmful exhaust from automobile. The mechanism for the carcinogenesis of MTBE in animals is not clear. Immunohistochemistry method was used to detect the effect of MTBE on the expression of c-myc and p21 proteins in NIH3T3 cells. Dot hybridization method was used to explore the expression of c-myc gene and GST-P(glutathione S-transferase-P) gene in the of MTBE treated rats. The results showed that MTBE could enhance the expression of c-myc protein, but had no effect on p21 protein. MTBE could induce high expression of c-myc gene, and had no effect on the expression of GST-P gene. These results suggest that the high expression of c-myc gene induced by MTBE might be one of the mechanisms of its carcinogenicity in animal.

Fenton-like Degradation of MTBE: Effects of Iron Counter Anion and Radical Scavengers

EPA Science Inventory

Fenton-driven oxidation of Methyl tert-butyl ether (MTBE) (0.11-0.16 mM) in batch reactors containing ferric iron (5 mM), hydrogen peroxide (H2O2) (6 mM) (pH=3) was performed to investigate MTBE transformation mechanisms. Independent variables included the form of iron (Fe) (Fe2(...

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

NASA Astrophysics Data System (ADS)

Sert, Yusuf; Puttaraju, K. B.; Keskinoğlu, Sema; Shivashankar, K.; Ucun, Fatih

2015-01-01

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

Crystal structure of (2-{[(8-aminona-phthalen-1-yl)imino]-meth-yl}-4,6-di-tert-butyl-phenolato-κ3N,N',O)bromido-nickel(II).

PubMed

O'Brien, Patrick; Zeller, Matthias; Lee, Wei-Tsung

2018-04-01

The title compound, [NiBr(C 25 H 29 N 2 O)], contains an Ni II atom with a slightly distorted square-planar coordination environment defined by one O and two N atoms from the 2-{[(8-aminona-phthalen-1-yl)imino]-meth-yl}-4,6-di- tert -butyl-phenolate ligand and a bromide anion. The Ni-O and Ni-N bond lengths are slightly longer than those observed in the phenyl backbone counterpart, which can be attributed to the larger steric hindrance of the naphthyl group in the structure of the title compound. The mol-ecule as a whole is substanti-ally distorted, with both the planar naphthalene-1,8-di-amine and imino-meth-yl-phenolate substitutents rotated against the NiN 2 OBr plane by 38.92 (7) and 37.22 (8)°, respectively, giving the mol-ecule a twisted appearance. N-H⋯Br hydrogen bonds and N-H⋯C(π) contacts connect the mol-ecules into dimers, and additional C-H⋯Br contacts, C-H⋯π inter-actions, and an offset stacking inter-action between naphthyl units inter-connect these dimers into a three-dimensional network.

Synthesis of methyl 2-O- and 3-O-alpha-D-talopyranosyl-alpha-D-mannopyranoside.

PubMed

Rana, S S; Matta, K L

1986-09-01

Methyl 3,4,6-tri-O-benzyl-2-O-[6-O-(tert-butyldiphenylsilyl)-alpha-D- mannopyranosyl]-alpha-D-mannopyranoside (2) was synthesized by treatment of methyl 3,4,6-tri-O-benzyl-2-O-alpha-D-mannopyranosyl-alpha-D-mannopyranoside with tert-butylchlorodiphenylsilane in the presence of imidazole. Isopropylidenation, followed by oxidation with pyridinium chlorochromate, and stereoselective reduction with sodium borohydride, converted 2 into methyl 3,4,6-tri-O-benzyl-2-O-[6-O-(tert-butyldiphenylsilyl)-2,3-O-isopro pylidene- alpha-D-talopyranosyl]-alpha-D-mannopyranoside (5). Treatment of 5 with a molar solution of tetrabutylammonium fluoride in dry oxolane produced a diol which, on O-de-isopropylidenation followed by catalytic hydrogenolysis, afforded the disaccharide glycoside methyl 2-O-alpha-D-talopyranosyl-alpha-D-mannopyranoside. Synthesis of methyl 3-O-alpha-D-talopyranosyl-alpha-D-mannopyranoside was accomplished by a similar reaction-sequence. The structures of the final disaccharides, and of various other intermediates, were established by 1H- and 13C-n.m.r. spectroscopy.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, Jon; Grum-Tokars, Valerie; Zhou, Ya

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

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

USGS Publications Warehouse

Baehr, Arthur L.; Reilly, Timothy J.

2001-01-01

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

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

PubMed Central

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

2010-01-01

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

Telomerase reverse transcriptase (TERT) is a therapeutic target of oleanane triterpenoid CDDO-Me in prostate cancer.

PubMed

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

2012-12-11

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.

Antioxidant capacity of BO-653, 2,3-dihydro-5-hydroxy-4,6-di-tert-butyl-2,2-dipentylbenzofuran, and uric acid as evaluated by ORAC method and inhibition of lipid peroxidation.

PubMed

Niki, Etsuo; Fukuhara, Akiko; Omata, Yo; Saito, Yoshiro; Yoshida, Yasukazu

2008-04-01

The role of radical-scavenging antioxidant against oxidative stress has received much attention. The antioxidant capacity has been assessed by various methods. Above all, oxygen radical absorbance capacity (ORAC) has been frequently employed [Prior et.al., J. Agric. Food Chem.2005, 53, 4290]. In the present study, the antioxidant capacity of 2,3-dihydro-5-hydroxy-4,6-di-tert-butyl-2,2-dipentylbenzofuran (BO-653) and uric acid was assessed by ORAC method using pyranine as a reference probe and compared with that against lipid peroxidation of human plasma. It was found that BO-653 was assessed to be much less potent than uric acid by ORAC method, whereas BO-653 exerted much higher antioxidant activity than uric acid against plasma lipid peroxidation. The reason for such discrepancy is discussed. The results suggest that ORAC method is suitable for the assessment of free radical scavenging capacity, but not for the assessment of antioxidant capacity against lipid peroxidation in plasma.

Enantiodifferentiation of whisky and cognac lactones using gas chromatography with different cyclodextrin chiral stationary phases.

PubMed

Schmarr, Hans-Georg; Mathes, Maximilian; Wall, Kristina; Metzner, Frank; Fraefel, Marius

2017-09-22

The chiral lactone 5-butyl-4-methyloxolan-2-one or 5-butyl-4-methyldihydro-2(3H)-furanone, often named whisky lactone, is found in oak wood, then contributing to the appreciated flavor of beverages stored in such wooden barrels. Its next higher homologue is named cognac lactone (5-pentyl-4-methyloxolan-2-one or 5-pentyl-4-methyldihydro-2(3H)-furanone), however is much less known, probably due to its minor concentration level. In order to study the direct enantioseparation of both lactones by gas chromatography on chiral stationary phases, individual enantiomers, particularly for cognac lactone were made available. This was achieved by baker's yeast reduction of synthesized ethyl 3-methyl-4-oxononanoate or, after hydrolysis, of the corresponding 4-ketoacid, that gave access to individual enantiomers of cognac lactone. Good enantioseparation was achieved for both whisky and cognac lactone with high values for the chiral resolution with 6-O-tert. butyl dimethylsilyl-2,3-dialkylated or 6-O-tert. butyl dimethylsilyl-2,3-diacylated cyclodextrin derivatives as chiral selectors. The influence of the nature and position of derivatization of the cyclodextrin moiety revealed a strong impact on the chiral recognition mechanism, as the investigated alkylated derivatives heptakis-(2,6-di-O-iso-pentyl-3-O-allyl)-β-cyclodextrin and octakis-(2,3-di-O-pentyl-6-O-methyl)-γ-cyclodextrin did not provide any or only minor chiral selectivity for the two lactones. Copyright © 2017 Elsevier B.V. All rights reserved.

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

NASA Astrophysics Data System (ADS)

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-01

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 xTBA ≈ 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 xTBA ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak nonlinearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ≈ 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.

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

PubMed

Banerjee, Saikat; Furtado, Jonathan; Bagchi, Biman

2014-05-21

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

Protective effect of black garlic extracts on tert-Butyl hydroperoxide-induced injury in hepatocytes via a c-Jun N-terminal kinase-dependent mechanism

PubMed Central

Lee, Ko-Chao; Teng, Chih-Chuan; Shen, Chien-Heng; Huang, Wen-Shih; Lu, Chien-Chang; Kuo, Hsing-Chun; Tung, Shui-Yi

2018-01-01

Black garlic has been reported to show multiple bioactivities against the development of different diseases. In the present study, the hepatoprotective effect of black garlic on injured liver cells was investigated. Rat clone-9 hepatocytes were used for all experiments; tert-Butyl hydroperoxide (tBHP) was used to induce injury of rat clone-9 hepatocytes. The contents of malondialdehyde (MDA) and glutathione (GSH); anti-oxidative enzyme activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx); and mRNA expression levels of interleukin (IL)-6 and IL-8 in rat clone-9 hepatocytes were determined to evaluate the level of cell damage. Black garlic extracts were demonstrated to significantly attenuate tBHP-induced cell death of rat clone-9 hepatocytes (P<0.05). Pretreatment with black garlic extracts antagonized GSH depletion, tBHP-increased MDA accumulation and the mRNA expression level of IL-6/IL-8, and tBHP-decreased antioxidative enzyme activities (all P<0.05). Moreover, the present study revealed that c-Jun N-terminal kinase signaling regulated black garlic-inhibited tBHP effects in rat clone-9 hepatocytes. Our findings demonstrate that black garlic has the hepatoprotective potential to block tBHP-damaged effects on cell death, lipid peroxidation, oxidative stress, and inflammation in rat clone-9 hepatocytes. Thus, the present study indicates that black garlic may be an excellent natural candidate in the development of adjuvant therapy and healthy foods for liver protection. PMID:29456651

Vibrational spectra and ab initio analysis of tert-butyl, trimethylsilyl, and trimethylgermyl derivatives of 3,3-dimethylcyclopropene II. 3,3-Dimethyl-1,2-bis(trimethylsilyl)cyclopropene

NASA Astrophysics Data System (ADS)

Panchenko, Yu. N.; De Maré, G. R.; Abramenkov, A. V.; Baird, M. S.; Tverezovsky, V. V.; Nizovtsev, A. V.; Bolesov, I. G.

2003-07-01

The IR and Raman spectra of 3,3-dimethyl-1,2-bis(trimethylsilyl)cyclopropene (I) (synthesised using standard procedures) were measured in the liquid phase. Total geometry optimisation was performed at the HF/6-31G* level. The HF/6-31G*//HF/6-31G* quantum mechanical force field (QMFF) was calculated and used to determine the theoretical fundamental vibrational frequencies, their predicted IR intensities, Raman activities, and Raman depolarisation ratios. Using Pulay's scaling method and the theoretical molecular geometry, the QMFF of I was scaled by a set of scaling factors used previously for 3,3-dimethyl-1,2-bis(tert-butyl)cyclopropene (17 scale factors for a 105-dimensional problem). The scaled QMFF obtained was used to solve the vibrational problem. The quantum mechanical values of the Raman activities were converted to differential Raman cross sections. The figures for the experimental and theoretical Raman and IR spectra are presented. Assignments of the experimental vibrational spectra of I are given. They take into account the calculated potential energy distribution and the correlation between the estimations of the experimental IR and Raman intensities and Raman depolarisation ratios and the corresponding theoretical values (including Raman cross sections) calculated using the unscaled QMFF.

Protein dynamics in organic media at varying water activity studied by molecular dynamics simulation.

PubMed

Wedberg, Rasmus; Abildskov, Jens; Peters, Günther H

2012-03-01

In nonaqueous enzymology, control of enzyme hydration is commonly approached by fixing the thermodynamic water activity of the medium. In this work, we present a strategy for evaluating the water activity in molecular dynamics simulations of proteins in water/organic solvent mixtures. The method relies on determining the water content of the bulk phase and uses a combination of Kirkwood-Buff theory and free energy calculations to determine corresponding activity coefficients. We apply the method in a molecular dynamics study of Candida antarctica lipase B in pure water and the organic solvents methanol, tert-butyl alcohol, methyl tert-butyl ether, and hexane, each mixture at five different water activities. It is shown that similar water activity yields similar enzyme hydration in the different solvents. However, both solvent and water activity are shown to have profound effects on enzyme structure and flexibility.

Disposition, metabolism, and toxicity of methyl tertiary butyl ether, an oxygenate for reformulated gasoline.

PubMed

Hutcheon, D E; Arnold, J D; ten Hove, W; Boyle, J

1996-04-05

Studies of the toxicology of methyl tertiary butyl ether (MTBE) were reviewed as a possible information base for evaluating the health effects of evaporative emissions from reformulated gasoline (RFG). The major metabolites of the oxidative demethylation of MTBE in vivo were methanol and tertiary butyl alcohol (TBA), whereas formaldehyde and TBA were the principal products of hepatic microsomal oxidation by cytochrome P-450. Pharmacokinetic studies in rats treated with intragastric MTBE in corn oil gave an initial disposition T1/2 for MTBE of 0.32 h. The decline in the serum drug versus time curve for MTBE in rats was accompanied by a progressive increase in serum methanol concentrations to levels more than 50-200 times those of the parent compound. Repeated exposure of MTBE vapor by inhalation in rats resulted in dose-dependent increases in MTBE in the blood, brain, and adipose tissue compartments. Blood concentrations of TBA were also dose dependent and provided an estimate of the total amount of MTBE distributed to peripheral drug metabolizing compartments. Perirenal fat/blood MTBE concentration ratios ranged from 9.7 to 11.6 after 15 wk of intermittent exposure. During an oxyfuels program in Fairbanks, AK, blood levels of occupationally exposed workers were 0.2-31.5 microgram/L MTBE and 1.6 to 72.2 microgram/L TBA with a mean TBA:MTBE blood concentration ratio of 4.2. In patients who received MTBE by percutaneous, transhepatic puncture for the dissolution of cholesterol gallstones, concentrations of MTBE in fat tissue reached 60 and 300 microgram/g at a treatment time when mean blood MTBE was less than 20 microgram/ml. The results of laboratory and clinical studies indicate that metabolites of MTBE may contribute to the nephropathy, neoplasms, and other pathological changes associated with repeated exposure to MTBE in experimental animals. It is concluded that such studies can provide a well-defined database for quantitative safety comparisons and health risk

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

PubMed

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

2004-02-01

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

3,3-Dimethyl-1-[5-(1H-1,2,4-triazol-1-yl­meth­yl)-1,3,4-thia­diazol-2-ylsulfan­yl]butan-2-one

PubMed Central

Wei, Qing-Li; He, Fu-Jin; Li, Fang; Bi, Sai

2008-01-01

In the mol­ecule of the title compound, C11H15N5OS2, the thia­diazole and triazole rings are not coplanar, the dihedral angle formed by their mean planes being 59.9 (2)°. The exocyclic S atom, and the methyl­ene, carbonyl, tert-butyl and one methyl carbon form an approximately planar zigzag chain, which makes a dihedral angle of 74.6 (1)° with the thia­diazole ring. PMID:21201440

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

PubMed Central

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

2012-01-01

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

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

PubMed Central

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

2008-01-01

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

Unique orientations and rotational dynamics of a 1-butyl-3-methyl-imidazolium hexafluorophosphate ionic liquid at the gas-liquid interface: the effects of the hydrogen bond and hydrophobic interactions.

PubMed

Yang, Deshuai; Fu, Fangjia; Li, Li; Yang, Zhen; Wan, Zheng; Luo, Yi; Hu, Na; Chen, Xiangshu; Zeng, Guixiang

2018-05-07

Here we report a series of molecular dynamics simulations for the orientations and rotational dynamics of the 1-butyl-3-methyl-imidazoliumhexafluorophosphate ([BMIM][PF 6 ]) ionic liquid (IL) at the gas-liquid interface. Compared to the bulk phase, the [BMIM] + cations at the interface prefer to orientate themselves with their imidazolium rings perpendicular to the gas-IL interface plane and their butyl chains pointing toward the vacuum phase. Such a preferential orientation can be attributed to the combined effect of the hydrophobic interactions and the optimum loss of hydrogen bonds (HBs). More interestingly, our simulation results demonstrate that the butyl chains of cations exhibit a two-stage rotational behavior at the interface, where the butyl chains are always in the vacuum phase at the first stage and the second stage corresponds to the butyl chains migrating from the vacuum phase into the liquid phase. A further detailed analysis reveals that their rotational motions at the first stage are mainly determined by the weakened HB strength at the interface while those at the second stage are dominated by their hydrophobic interactions. Such a unique rotational behavior of the butyl chains is significantly different from those of the anions and the imidazolium rings of cations at the interface due to the lack of existence of hydrophobic interaction in the cases of the latter two. In addition, a new and simple time correlation function (TCF) was constructed here for the first time to quantitatively identify the relevant hydrophobic interaction of alkyl chains. Therefore, our simulation results provide a molecular-level understanding of the effects of HB and hydrophobic interactions on the unique properties of imidazolium-based ILs at the gas-liquid interface.

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

USGS Publications Warehouse

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

2001-01-01

Data on volatile organic compounds (VOCs) in drinking water supplied by 2,110 randomly selected community water systems (CWSs) in 12 Northeast and Mid-Atlantic States indicate 64 VOC analytes were detected at least once during 1993-98. Selection of the 2,110 CWSs inventoried for this study targeted 20 percent of the 10,479 active CWSs in the region and represented a random subset of the total distribution by State, source of water, and size of system. The data include 21,635 analyses of drinking water collected for compliance monitoring under the Safe Drinking Water Act; the data mostly represent finished drinking water collected at the pointof- entry to, or at more distal locations within, each CWS?s distribution system following any watertreatment processes. VOC detections were more common in drinking water supplied by large systems (serving more than 3,300 people) that tap surface-water sources or both surface- and groundwater sources than in small systems supplied exclusively by ground-water sources. Trihalomethane (THM) compounds, which are potentially formed during the process of disinfecting drinking water with chlorine, were detected in 45 percent of the randomly selected CWSs. Chloroform was the most frequently detected THM, reported in 39 percent of the CWSs. The gasoline additive methyl tert-butyl ether (MTBE) was the most frequently detected VOC in drinking water after the THMs. MTBE was detected in 8.9 percent of the 1,194 randomly selected CWSs that analyzed samples for MTBE at any reporting level, and it was detected in 7.8 percent of the 1,074 CWSs that provided MTBE data at the 1.0-?g/L (microgram per liter) reporting level. As with other VOCs reported in drinking water, most MTBE concentrations were less than 5.0 ?g/L, and less than 1 percent of CWSs reported MTBE concentrations at or above the 20.0-?g/L lower limit recommended by the U.S. Environmental Protection Agency?s Drinking-Water Advisory. The frequency of MTBE detections in drinking water

Modified extraction procedure for gas-liquid chromatography applied to the identification of anaerobic bacteria.

PubMed Central

Thomann, W R; Hill, G B

1986-01-01

Chloroform and ether commonly are used as solvents to extract metabolic organic acids for analysis by gas-liquid chromatography in the identification of anaerobic bacteria. Because these solvents are potentially hazardous to personnel, modified extraction procedures involving the use of a safer solvent, methyl tert-butyl ether were developed which remained both simple to perform and effective for organism identification. PMID:3700623

Bidentate urea derivatives of p-tert-butyldihomooxacalix[4]arene: neutral receptors for anion complexation.

PubMed

Marcos, Paula M; Teixeira, Filipa A; Segurado, Manuel A P; Ascenso, José R; Bernardino, Raul J; Michel, Sylvia; Hubscher-Bruder, Véronique

2014-01-17

Three new bidentate ureidodihomooxacalix[4]arene derivatives (phenyl 5a, n-propyl 5b, and tert-butyl 5c) were synthesized in four steps from the parent compound p-tert-butyldihomooxacalix[4]arene and obtained in the cone conformation, as shown by NMR studies. The binding ability of these neutral receptors toward spherical, linear, trigonal planar, and tetrahedrical anions was assessed by (1)H NMR and UV-vis titrations. The structures and complexation energies of some complexes were also studied by DFT methods. The data showed that the association constants are strongly dependent on the nature of the substituent (aryl/alkyl) at the urea moiety. In general, for all the receptors, the association constants decrease with decrease of anion basicity. Ph-urea 5a is the best anion receptor, showing the strongest complexation for F(-) (log K(assoc) = 3.10 in CDCl3) and also high binding affinity for the carboxylates AcO(-) and BzO(-). Similar results were obtained by UV-vis studies and were also corroborated by DFT calculations.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Shanju; Liu, Zhan; Bucknall, David G.

2011-01-01

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

Phenylthiazoles with tert-Butyl side chain: Metabolically stable with anti-biofilm activity.

PubMed

Kotb, Ahmed; Abutaleb, Nader S; Seleem, Mohamed A; Hagras, Mohamed; Mohammad, Haroon; Bayoumi, Ashraf; Ghiaty, Adel; Seleem, Mohamed N; Mayhoub, Abdelrahman S

2018-05-10

A new series of phenylthiazoles with t-butyl lipophilic component was synthesized and their antibacterial activity against a panel of multidrug-resistant bacterial pathogens was evaluated. Five compounds demonstrated promising antibacterial activity against methicillin-resistant staphylococcal strains and several vancomycin-resistant staphylococcal and enterococcal species. Additionally, three derivatives 19, 23 and 26 exhibited rapid bactericidal activity, and remarkable ability to disrupt mature biofilm produced by MRSA USA300. More importantly, a resistant mutant to 19 couldn't be isolated after subjecting MRSA to sub-lethal doses for 14 days. Lastly, this new series of phenylthiazoles possesses an advantageous attribute over the first-generation compounds in their stability to hepatic metabolism, with a biological half-life of more than 9 h. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Method for producing redox shuttles

DOEpatents

Pupek, Krzysztof Z.; Dzwiniel, Trevor L.; Krumdick, Gregory K.

2015-03-03

A single step method for producing a redox shuttle having the formula 2,5-di-tert-butyl-1,4-phenylene tetraethyl bis(phosphate) is provided, the method comprising phosphorylating tert butyl hydroquinone with a phosphate-containing reagent. Also provided is method for producing 2,5-di-tert-butyl-1,4-phenylene tetraethyl bis(phosphate), the method comprising solubilizing tert-butyl hydroquinone and tetrabutylammonium bromide with methyltetrahydrofuran to create a mixture; heating the mixture while adding base to the mixture in an amount to turn the mixture orange; and adding diethyl chlorophosphate to the orange mixture in an amount to phosphorylate the hydroquinone.

Selective liquid phase oxidation of benzyl alcohol to benzaldehyde by tert-butyl hydroperoxide over γ-Al2O3 supported copper and gold nanoparticles

NASA Astrophysics Data System (ADS)

Ndolomingo, Matumuene Joe; Meijboom, Reinout

2017-03-01

Benzyl alcohol oxidation to benzaldehyde was performed by tert-butyl hydroperoxide (TBHP) in the absence of any solvent using γ-Al2O3 supported copper and gold nanoparticles. Li2O and ionic liquids were used as additive and stabilizers for the synthesis of the catalysts. The physico-chemical properties of the catalysts were characterized by atomic absorption spectroscopy (AAS), X-ray diffraction spectroscopy (XRD), N2 absorption/desorption (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and temperature programmed reduction (TPR), whereas, the oxidation reaction was followed by gas chromatography with a flame ionization detector (GC-FID). The as prepared catalysts exhibited good catalytic performance in terms of conversion and selectivity towards benzaldehyde. The performance of the Au-based catalysts is significantly higher than that of the Cu-based catalysts. For both Cu and Au catalysts, the conversion of benzyl alcohol increased as the reaction proceeds, while the selectivity for benzaldehyde decreased. Moreover, the catalysts can be easily recycled and reused with neither significant loss of activity nor selectivity. A kinetic study for the Cu and Au-catalyzed oxidation of benzyl alcohol to benzyldehyde is reported. The rate at which the oxidation of benzyl alcohol is occurring as a function of catalyst and oxidant amounts was investigated, with the apparent rate constant, kapp being proportional to the amount of nano catalyst and oxygen present in the system.

Production of o-diphenols by immobilized mushroom tyrosinase.

PubMed

Marín-Zamora, María Elisa; Rojas-Melgarejo, Francisco; García-Cánovas, Francisco; García-Ruiz, Pedro Antonio

2009-01-15

The o-diphenols 4-tert-butyl-catechol, 4-methyl-catechol, 4-methoxy-catechol, 3,4-dihydroxyphenylpropionic acid and 3,4-dihydroxyphenylacetic acid were produced from the corresponding monophenols (4-tert-butyl-phenol, 4-methyl-phenol, 4-methoxy-phenol, p-hydroxyphenylpropionic acid and p-hydroxyphenylacetic acid) using immobilized mushroom tyrosinase from Agaricus bisporus. In all cases the yield was R(diphenol)> or =88-96%, which, according to the literature, is the highest yield so far, obtained using tyrosinase. The reaction was carried out in 0.5M borate buffer pH 9.0 which was used to minimize the diphenolase activity of tyrosinase by complexing the o-diphenols generated. Hydroxylamine and ascorbic acid were also present in the reaction medium, the former being used to reduce mettyrosinase to deoxytyrosinase, closing the catalytic cycle, and the latter to reduce the o-quinone produced to o-diphenol. Inactivation of the tyrosinase by ascorbic acid was also minimized due to the formation of an ascorbic acid-borate complex. Concentrations of the o-diphenolic compounds obtained at several reaction times were determined by gas chromatography-mass spectrometry (GC-MS) and UV-vis spectroscopy. The experimental results are discussed.

An efficient synthesis of the constrained peptidomimetic 2-oxo-3-(N-9-fluorenyloxycarbonylamino)-1-azabicyclo[4.3.0]nonane-9-carboxylic acid from pyroglutamic acid.

PubMed

Mandal, Pijus Kumar; Kaluarachchi, Kumar K; Ogrin, Douglas; Bott, Simon G; McMurray, John S

2005-11-25

[reaction: see text] Azabicyclo[X.Y.0]alkane amino acids are rigid dipeptide mimetics that are useful tools for structure-activity studies in peptide-based drug discovery. Herein, we report an efficient synthesis of three diastereomers of 9-tert-butoxycarbonyl-2-oxo-3-(N-tert-butoxycarbonylamino)-1-azabicyclo[4.3.0]nonane (3S,6S,9S, 3S,6R,9R, and 3S,6R,9S). Methyl N-Boc-pyroglutamate is cleaved with vinylmagnesium bromide to produce an acyclic gamma-vinyl ketone. Michael addition of N-diphenylmethyleneglycine tert-butyl ester produces the N-Boc-delta-oxo-alpha,omega-diaminoazelate intermediate, which, on hydrogenloysis, gives the fused ring system. Acidolytic deprotection followed by Fmoc-protection provided building blocks suitable for solid-phase synthesis.

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

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

Acetylcholinesterase and Acetylcholine Receptor

DTIC Science & Technology

1989-01-30

trimethyl analogue, neopentyl alcohol, (CH 3 ) 3 CCH20H, Ki(comi - 29 mM, Ki(nonc)’ = 74 mM, and to the ether isomer of the latter, =-butyl methyl ether, (CH...Trietrylene glycol di-tert-butylether is being prepared from the glycol via the di-p-toluenesulfonate, mp 80-81"C from methanol, lit. 80-810C (60). 2-N,N

[18F]Fluorophenylazocarboxylates: Design and Synthesis of Potential Radioligands for Dopamine D3 and μ-Opioid Receptor

PubMed Central

2017-01-01

18F-Labeled building blocks from the type of [18F]fluorophenylazocarboxylic-tert-butyl esters offer a rapid, mild, and reliable method for the 18F-fluoroarylation of biomolecules. Two series of azocarboxamides were synthesized as potential radioligands for dopamine D3 and the μ-opioid receptor, revealing compounds 3d and 3e with single-digit and sub-nanomolar affinity for the D3 receptor and compound 4c with only micromolar affinity for the μ-opioid receptor, but enhanced selectivity for the μ-subtype in comparison to the lead compound AH-7921. A “minimalist procedure” without the use of a cryptand and base for the preparation of 4-[18F]fluorophenylazocarboxylic-tert-butyl ester [18F]2a was established, together with the radiosynthesis of methyl-, methoxy-, and phenyl-substituted derivatives ([18F]2b–f). With the substituted [18F]fluorophenylazocarbylates in hand, two prototype azocarboxylates radioligands were synthesized by 18F-fluoroarylation, namely the methoxy azocarboxamide [18F]3d as the D3 receptor radioligand and [18F]4a as a prototype structure of the μ-opioid receptor radioligand. By introducing the new series of [18F]fluorophenylazocarboxylic-tert-butyl esters, the method of 18F-fluoroarylation was significantly expanded, thereby demonstrating the versatility of 18F-labeled phenylazocarboxylates for the design of potential radiotracers for positron emission tomography . PMID:29479577

Freeze-drying of tert-butyl alcohol/water cosolvent systems: effects of formulation and process variables on residual solvents.

PubMed

Wittaya-Areekul, S; Nail, S L

1998-04-01

The objective of this study was to identify significant formulation and processing variables affecting levels of tert-butyl alcohol (TBA) and isopropyl alcohol (IPA) in freeze-dried solids prepared from TBA/water cosolvent systems. The variables examined were the physical state of the solute (crystalline vs amorphous), initial TBA concentration, freezing rate, cake thickness, and the temperature and duration of secondary drying. Sucrose and glycine were used as models for noncrystallizing and crystallizing solutes, respectively. The TBA concentration above which eutectic crystallization takes place was determined by differential scanning calorimetry. Model formulations were subjected to extremes of freezing rate by either dipping in liquid nitrogen or by slowly freezing on the shelf of a freeze-dryer. Dynamics of solvent loss during secondary drying was determined by withdrawing samples as a function of time at different shelf temperatures using a thief system. On the basis of these studies, the most important determinant of residual TBA level is the physical state of the solute. Freeze-dried glycine contained very low levels of residual TBA (0.01-0.03%) regardless of freezing rate or initial TBA concentration. For freeze-dried sucrose, residual TBA levels were approximately 2 orders of magnitude higher and were significantly affected by initial TBA concentration and freezing rate. For the sucrose/TBA/water system, relatively low residual TBA levels were obtained when the initial TBA level was above the threshold concentration for eutectic crystallization of TBA, whereas samples freeze-dried from solutions containing TBA concentrations below this threshold contained significantly higher levels of TBA. Residual IPA levels increased continuously with initial concentration of TBA in the sucrose/TBA/water system. Formulations of sucrose/TBA/water which were frozen rapidly contained residual TBA levels which were approximately twice those measured in the same

Using DNA-Stable Isotope Probing to Identify MTBE- and TBA-Degrading Microorganisms in Contaminated Groundwater.

PubMed

Key, Katherine C; Sublette, Kerry L; Duncan, Kathleen; Mackay, Douglas M; Scow, Kate M; Ogles, Dora

2013-01-01

Although the anaerobic biodegradation of methyl tert -butyl ether (MTBE) and tert -butyl alcohol (TBA) has been documented in the laboratory and the field, knowledge of the microorganisms and mechanisms involved is still lacking. In this study, DNA-stable isotope probing (SIP) was used to identify microorganisms involved in anaerobic fuel oxygenate biodegradation in a sulfate-reducing MTBE and TBA plume. Microorganisms were collected in the field using Bio-Sep® beads amended with 13 C 5 -MTBE, 13 C 1 -MTBE (only methoxy carbon labeled), or 13 C 4 -TBA. 13 C-DNA and 12 C-DNA extracted from the Bio-Sep beads were cloned and 16S rRNA gene sequences were used to identify the indigenous microorganisms involved in degrading the methoxy group of MTBE and the tert -butyl group of MTBE and TBA. Results indicated that microorganisms were actively degrading 13 C-labeled MTBE and TBA in situ and the 13 C was incorporated into their DNA. Several sequences related to known MTBE- and TBA-degraders in the Burkholderiales and the Sphingomonadales orders were detected in all three 13 C clone libraries and were likely to be primary degraders at the site. Sequences related to sulfate-reducing bacteria and iron-reducers, such as Geobacter and Geothrix , were only detected in the clone libraries where MTBE and TBA were fully labeled with 13 C, suggesting that they were involved in processing carbon from the tert -butyl group. Sequences similar to the Pseudomonas genus predominated in the clone library where only the methoxy carbon of MTBE was labeled with 13 C. It is likely that members of this genus were secondary degraders cross-feeding on 13 C-labeled metabolites such as acetate.

Using DNA-Stable Isotope Probing to Identify MTBE- and TBA-Degrading Microorganisms in Contaminated Groundwater

PubMed Central

Key, Katherine C.; Sublette, Kerry L.; Duncan, Kathleen; Mackay, Douglas M.; Scow, Kate M.; Ogles, Dora

2014-01-01

Although the anaerobic biodegradation of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) has been documented in the laboratory and the field, knowledge of the microorganisms and mechanisms involved is still lacking. In this study, DNA-stable isotope probing (SIP) was used to identify microorganisms involved in anaerobic fuel oxygenate biodegradation in a sulfate-reducing MTBE and TBA plume. Microorganisms were collected in the field using Bio-Sep® beads amended with 13C5-MTBE, 13C1-MTBE (only methoxy carbon labeled), or13C4-TBA. 13C-DNA and 12C-DNA extracted from the Bio-Sep beads were cloned and 16S rRNA gene sequences were used to identify the indigenous microorganisms involved in degrading the methoxy group of MTBE and the tert-butyl group of MTBE and TBA. Results indicated that microorganisms were actively degrading 13C-labeled MTBE and TBA in situ and the 13C was incorporated into their DNA. Several sequences related to known MTBE- and TBA-degraders in the Burkholderiales and the Sphingomonadales orders were detected in all three13C clone libraries and were likely to be primary degraders at the site. Sequences related to sulfate-reducing bacteria and iron-reducers, such as Geobacter and Geothrix, were only detected in the clone libraries where MTBE and TBA were fully labeled with 13C, suggesting that they were involved in processing carbon from the tert-butyl group. Sequences similar to the Pseudomonas genus predominated in the clone library where only the methoxy carbon of MTBE was labeled with 13C. It is likely that members of this genus were secondary degraders cross-feeding on 13C-labeled metabolites such as acetate. PMID:25525320

Hydrolysis of the quinone methide of butylated hydroxytoluene in aqueous solutions.

PubMed

Willcockson, Maren Gulsrud; Toteva, Maria M; Stella, Valentino J

2013-10-01

Butylated hydroxytoluene or BHT is an antioxidant commonly used in pharmaceutical formulations. BHT upon oxidation forms a quinone methide (QM). QM is a highly reactive electrophilic species that can undergo nucleophilic addition. Here, the kinetic reactivity of QM with water at various apparent pH values in a 50% (v/v) water-acetonitrile solution at constant ionic strength of I = 0.5 (NaCl)4 , was studied. The hydrolysis of QM in the presence of added acid, base, sodium chloride, and phosphate buffer resulted in the formation of only one product--the corresponding 3,5-di-tert-butyl-4-hydroxybenzyl alcohol (BA). The rate of BA formation was catalyzed by the addition of acid and base, but not chloride and phosphate species. Nucleophilic excipients, used in the pharmaceutical formulation, or nucleophilic groups on active pharmaceutical ingredient molecule may form adducts with QM, the immediate oxidative product of BHT degradation, thus having implications for drug product impurity profiles. Because of these considerations, BHT should be used with caution in formulations containing drugs or excipients capable of acting as nucleophiles. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

(CH3)3COOH (tert-butyl hydroperoxide): OH reaction rate coefficients between 206 and 375 K and the OH photolysis quantum yield at 248 nm.

PubMed

Baasandorj, Munkhbayar; Papanastasiou, Dimitrios K; Talukdar, Ranajit K; Hasson, Alam S; Burkholder, James B

2010-10-14

Rate coefficients, k, for the gas-phase reaction of the OH radical with (CH(3))(3)COOH (tert-butyl hydroperoxide) were measured as a function of temperature (206-375 K) and pressure (25-200 Torr (He, N(2))). Rate coefficients were measured under pseudo-first-order conditions using pulsed laser photolysis to produce OH and laser induced fluorescence (PLP-LIF) to measure the OH temporal profile. Two independent methods were used to determine the gas-phase infrared cross sections of (CH(3))(3)COOH, absolute pressure and chemical titration, that were used to determine the (CH(3))(3)COOH concentration in the LIF reactor. The temperature dependence of the rate coefficients is described, within the measurement precision, by the Arrhenius expression k(1)(T) = (7.0 ± 1.0) × 10(-13) exp[(485 ± 20)/T] cm(3) molecule(-1) s(-1) where k(1)(296 K) was measured to be (3.58 ± 0.54) × 10(-12) cm(3) molecule(-1) s(-1). The uncertainties are 2σ (95% confidence level) and include estimated systematic errors. UV absorption cross sections of (CH(3))(3)COOH were determined at 185, 214, 228, and 254 nm and over the wavelength range 210-300 nm. The OH quantum yield following the 248 nm pulsed laser photolysis of (CH(3))(3)COOH was measured relative to the OH quantum yields of H(2)O(2) and HNO(3) using PLP-LIF and found to be near unity.

Combined use of l-alanine tert butyl ester lactate and trimethyl-β-cyclodextrin for the enantiomeric separations of 2-arylpropionic acids nonsteroidal anti-inflammatory drugs.

PubMed

Mavroudi, Maria C; Kapnissi-Christodoulou, Constantina P

2015-10-01

In this study, a new CE method, employing a binary system of trimethyl-β-CD (TM-β-CD) and a chiral amino acid ester-based ionic liquid (AAIL), was developed for the chiral separation of seven 2-arylpropionic acid nonsteroidal anti-inflammatory drugs (NSAIDs). In particular, the enantioseparation of ibuprofen, ketoprofen, carprofen, indoprofen, flurbiprofen, naproxen, and fenoprofen was improved significantly by supporting the BGE with the chiral AAIL l-alanine tert butyl ester lactate (l-AlaC4 Lac). Parameters, such as concentrations of TM-β-CD and l-AlaC4 Lac, and buffer pH, were systematically examined in order to optimize the chiral separation of each NSAID. It was observed that the addition of the AAIL into the BGE improved both resolution and efficiency significantly. After optimization of separation conditions, baseline separation (Rs >1.5) of five of the analytes was achieved in less than 11 min, while the resolution of ibuprofen and flurbiprofen was approximately 1.2. The optimized enantioseparation conditions for all analytes involve a BGE of 5 mM sodium acetate/acetic acid (pH 5.0), an applied voltage of 30 kV, and a temperature of 20°C. In addition, the results obtained by computing the %-RSD values of the EOF and the two enantiomer peaks, demonstrated excellent run-to-run, batch-to-batch, and day-to-day reproducibilities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents

PubMed Central

Gau, Michael R.; Zdilla, Michael J.

2016-01-01

Organolithium reagents are powerful tools in the synthetic chemist's toolbox. However, the extreme pyrophoric nature of the most reactive reagents warrants proper technique, thorough training, and proper personal protective equipment. To aid in the training of researchers using organolithium reagents, a thorough, step-by-step protocol for the safe and effective use of tert-butyllithium on an inert gas line or within a glovebox is described. As a model reaction, preparation of lithium tert-butyl amide by the reaction of tert-butyl amine with one equivalent of tert-butyl lithium is presented. PMID:27911386

Electrochemical preparation of tris(tert-butyldimethylsilyl)cyclopropene and its hydride abstraction to tris(tert-butyldimethylsilyl)cyclopropenium tetrafluoroborate

PubMed Central

Buchholz, Herwig A.; Prakash, G. K. Surya; Deffieux, Denis; Olah, George A.

1999-01-01

Electrochemical reductive tert-butyldimethylsilylation of tetrachlorocyclopropene to 1,2,3-tris(tert-butyldimethylsilyl)cyclopropene, a potential strained precursor for Diels–Alder and related cycloaddition reactions, is described. By hydride abstraction with nitrosonium tetrafluoroborate, 1,2,3-tris(tert-butyldimethylsilyl)cyclopropene is ionized quantitatively to Hückeloid 2π aromatic tris(tert-butyldimethylsilyl)cyclopropenium tetrafluoroborate. PMID:10468551

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

PubMed

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

2011-04-01

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

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

USGS Publications Warehouse

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

2003-01-01

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

Health assessment of gasoline and fuel oxygenate vapors: micronucleus and sister chromatid exchange evaluations.

PubMed

Schreiner, Ceinwen A; Hoffman, Gary M; Gudi, Ramadevi; Clark, Charles R

2014-11-01

Micronucleus and sister chromatid exchange (SCE) tests were performed for vapor condensate of baseline gasoline (BGVC), or gasoline with oxygenates, methyl tert-butyl ether (G/MTBE), ethyl tert butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), t-butyl alcohol (TBA), or ethanol (G/EtOH). Sprague Dawley rats (the same 5/sex/group for both endpoints) were exposed to 0, 2000, 10,000, or 20,000mg/m(3) of each condensate, 6h/day, 5days/week over 4weeks. Positive controls (5/sex/test) were given cyclophosphamide IP, 24h prior to sacrifice at 5mg/kg (SCE test) and 40mg/kg (micronucleus test). Blood was collected from the abdominal aorta for the SCE test and femurs removed for the micronucleus test. Blood cell cultures were treated with 5μg/ml bromodeoxyuridine (BrdU) for SCE evaluation. No significant increases in micronucleated immature erythrocytes were observed for any test material. Statistically significant increases in SCE were observed in rats given BGVC alone or in female rats given G/MTBE. G/TAME induced increased SCE in both sexes at the highest dose only. Although DNA perturbation was observed for several samples, DNA damage was not expressed as increased micronuclei in bone marrow cells. Inclusion of oxygenates in gasoline did not increase the effects of gasoline alone or produce a cytogenetic hazard. Copyright © 2014 Elsevier Inc. All rights reserved.

Constitutive expression of tert in thymocytes leads to increased incidence and dissemination of T-cell lymphoma in Lck-Tert mice.

PubMed

Canela, Andrés; Martín-Caballero, Juan; Flores, Juana M; Blasco, María A

2004-05-01

Here we describe a new mouse model with constitutive expression of the catalytic subunit of telomerase (Tert) targeted to thymocytes and peripheral T cells (Lck-Tert mice). Two independent Lck-Tert mouse lines showed higher incidences of spontaneous T-cell lymphoma than the corresponding age-matched wild-type controls, indicating that constitutive expression of Tert promotes lymphoma. Interestingly, T-cell lymphomas in Lck-Tert mice were more disseminated than those in wild-type controls and affected both lymphoid and nonlymphoid tissues, while nonlymphoid tissues were never affected with lymphoma in age-matched wild-type controls. Importantly, these roles of Tert constitutive expression in promoting tumor progression and dissemination were independent of the role of telomerase in telomere length maintenance, since telomere length distributions on a single-cell basis were identical in Lck-Tert and wild-type thymocytes. Finally, Tert constitutive expression did not interfere with telomere capping in Lck-Tert primary thymocytes, although it resulted in greater chromosomal instability upon gamma irradiation in Lck-Tert primary lymphocytes than in controls, suggesting that Tert overexpression may interfere with the cellular response to DNA damage.

Improved Understanding of In Situ Chemical Oxidation. Technical Objective I: Contaminant Oxidation Kinetics Contaminant Oxidation Kinetics

DTIC Science & Technology

2009-05-01

methyl tert butyl ether NAPL non-aqueous phase liquid NOD natural oxidant demand •OH hydroxide radical Ox oxidant O3 ozone PCE...and persulfate; and Technical Objective 2, assess how soil properties (e.g., soil mineralogy , natural carbon content) affect oxidant mobility and...to develop a general description of kobs vs. T because there are many reactions that can contribute to the concentration of the reactive intermediate

Microbial biosafety of pilot-scale bioreactor treating MTBE and TBA-contaminated drinking water supply.

PubMed

Schmidt, Radomir; Klemme, David A; Scow, Kate; Hristova, Krassimira

2012-03-30

A pilot-scale sand-based fluidized bed bioreactor (FBBR) was utilized to treat both methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) from a contaminated aquifer. To evaluate the potential for re-use of the treated water, we tested for a panel of water quality indicator microorganisms and potential waterborne pathogens including total coliforms, Escherichia coli, Salmonella and Shigella spp., Campylobacter jejuni, Aeromonas hydrophila, Legionella pneumophila, Vibrio cholerae, Yersinia enterocolytica and Mycobacterium avium in both influent and treated waters from the bioreactor. Total bacteria decreased during FBBR treatment. E. coli, Salmonella and Shigella spp., C. jejuni, V. cholerae, Y. enterocolytica and M. avium were not detected in aquifer water or bioreactor treated water samples. For those pathogens detected, including total coliforms, L. pneumophila and A. hydrophila, numbers were usually lower in treated water than influent samples, suggesting removal during treatment. The detection of particular bacterial species reflected their presence or absence in the influent waters. Copyright © 2012 Elsevier B.V. All rights reserved.

Effect of antioxidants on the performance and emission characteristics of a diesel engine fuelled by waste cooking sunflower methyl ester

NASA Astrophysics Data System (ADS)

Reddy, V. Puneeth Kumar; Senthil Kumar, D.; Thirumalini, S.

2018-02-01

Biodiesel is a renewable, biodegradable fuel produced from vegetable oils and animal fats. Nonetheless, its extensive utilization is impeded by the auto-oxidation resulting in degradation of the fuel. Adding antioxidants to the biodiesel is a potential solution, but it might have an effect on the clean-burning characteristics of the fuel. This paper investigates the effect of antioxidants on the performance and emission characteristics of a diesel engine fuelled by the waste cooking sunflower methyl ester. The fuel samples tested include B10, B20, B30 and B40, among which B20 produced the best possible results. Antioxidants 2, 6-ditert-butyl-4-methylphenol (BHA) and 2(3)-tert-butyl-4-methoxy phenol (BHT) of two concentrations 1000 ppm, 2000 ppm were added to B20 to evaluate the effectiveness. B20BHA1000 had the best effect with an average decrease of 5.035%, 2.02% in brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT) compared to B20. Regarding the emission characteristics it was observed that B20BHA1000 had produced an increase of 7.21%, 27.79% in NOx and smoke emissions and a decrease of 33.33% in HC emissions when compared to B20. On the whole, without any requirement of alteration in the diesel engines, B20 blends with antioxidant can be utilized as fuel.

μ-Carbonato-κ(4) O,O':O',O''-bis-{[2'-(di-tert-butyl-phosphan-yl)biphenyl-2-yl-κ(2) P,C (1)]palladium(II)} dichloro-methane monosolvate.

PubMed

Muller, Alfred; Holzapfel, Cedric W

2012-12-01

The title compound, [(μ2-CO3){Pd(P(t-C4H9)2(C12H8)}2]·CH2Cl2, the first CO3-bridged palladium dimer complex reported to date, was obtained while preparing the Pd(0) complex with (2-biphen-yl)P( (t) Bu)2. In the crystal, each palladium dimer is accompanied by a dichloro-methane solvent mol-ecule. Coordination of the carbonate and chelated phosphane ligands gives distorted square-planar environments at the Pd atoms. Important geometrical parameters include Pd-P(av.) = 2.2135 (4) Å, Pd-C(av.) = 1.9648 (16) Å and P-Pd-C = 84.05 (5) and 87.98 (5)°, and O-Pd-O' = 60.56 (4) and 61.13 (4)°. Bonding with the carbonate O atoms shows values of 2.1616 (11) and 2.1452 (11) Å for the Pd-O-Pd bridge, whereas other Pd-O distances are slightly longer at 2.2136 (11) and 2.1946 (11) Å. One of the tert-butyl groups is disordered over two set of sites with an occupancy ratio of 0.723 (6):0.277 (6). Weak C-H⋯O interactions are observed propagating the molecules along the [100] direction.

A new piperazine derivative: 1-(4-(3,5-di-tert-butyl-4-hydroxybenzyl) piperazin-1-yl)-2-methoxyethan-1-one with antioxidant and central activity.

PubMed

Brito, Adriane F; Braga, Patrícia C C S; Moreira, Lorrane K S; Silva, Dayane M; Silva, Daiany P B; Sanz, Germán; Vaz, Boniek G; de Carvalho, Flávio S; Lião, Luciano M; Silva, Rafaela R; Noël, François; Neri, Hiasmin F S; Ghedini, Paulo C; de Carvalho, Murilo F; de S Gil, Eric; Costa, Elson A; Menegatti, Ricardo

2018-03-01

In the scope of a research program aimed at developing new drugs for the treatment of central nervous system diseases, we describe herein the synthesis and pharmacological evaluation of 1-(4-(3,5-di-tert-butyl-4-hydroxybenzyl) piperazin-1-yl)-2-methoxyethan-1-one (LQFM180). This compound showed antioxidant activity in two models, electroanalytical assays, and DPPH activity. Moreover, in behavioral tests as the open field test LQFM180 (9.4, 18.8, and 37.6 mg/kg, per oral (p.o.)), we detected anxiolytic-like activity. In the sodium pentobarbital-induced sleep test, LQFM180, in all doses, decreased the latency to sleep and increased sleep duration, indicating central depressant activity; moreover, in the chimney test, LQFM180 did not alter motor activity. LQFM180 (18.8 mg/kg, p.o.) increased the time and number of entries on open arms in the elevated plus maze test, suggesting anxiolytic-like activity, which was reversed by NAN-190 and p-chlorophenylalanine, indicating a role of the serotonergic pathway on this effect. In the forced swimming test, LFQM180 (18.8 mg/kg, p.o.) decreased immobility time, suggesting antidepressant-like activity, which was reversed by monoaminergic antagonists, indicating a role for the serotonergic, noradrenergic, and dopaminergic pathways. Competition binding assays showed that LQFM180 was able to bind to the α 1B , 5-HT 1A , and D 2 receptors, however, within the low micromolar range. We conclude that LQFM180 should be considered as a scaffold for drug candidate development.

Azilsartan, an angiotensin II type 1 receptor blocker, attenuates tert-butyl hydroperoxide-induced endothelial cell injury through inhibition of mitochondrial dysfunction and anti-inflammatory activity.

PubMed

Liu, Hao; Mao, Ping; Wang, Jia; Wang, Tuo; Xie, Chang-Hou

2016-03-01

Angiotensin II type 1 receptor (AT1-R) blockers protect against brain ischemia by mechanisms dependent on and independent of arterial blood pressure. However, the effects of AT1-R blockers on brain endothelial cell injury and detailed mechanisms remain unclear. The goal of this study is to investigate whether azilsartan, an AT1-R blocker, could attenuate oxidative injury in endothelial cells via regulating mitochondrial function and inflammatory responses. We found that treatment with azilsartan suppressed tert-butyl hydroperoxide (t-BHP)-induced oxidative damage in murine brain endothelial cells (mBECs) by increasing cell viability, decreasing lactate dehydrogenase (LDH) release and inhibiting cell apoptosis. Azilsartan significantly inhibited reactive oxygen species (ROS) generation and lipid peroxidation, but had no effect on antioxidant system. We also detected preserved mitochondrial function after azilsartan treatment, as evidenced by increased mitochondrial membrane potential (MMP), reduced cytochrome c release, preserved ATP synthesis and inhibited mitochondrial swelling. In addition, azilsartan differently regulated expression of inflammatory cytokines and increased the activation of endothelial nitric oxide synthase (eNOS). Pretreatment with eNOS inhibitor L-NIO partially prevented the azilsartan-induced regulation of cytokines and protection. Furthermore, azilsartan-induced protection in our in vitro model was shown to be associated with protein stability of peroxisome proliferator-activated receptor-γ (PPAR-γ). Overall, our data suggest that the AT1-R blocker azilsartan may have therapeutic values in treating endothelial dysfunction associated neurological disorders through anti-oxidative and anti-inflammatory properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Activation of C-H bonds by rare-earth metallocene-butyl complexes.

PubMed

Grindell, Richard; Day, Benjamin M; Guo, Fu-Sheng; Pugh, Thomas; Layfield, Richard A

2017-09-05

The stable metallocene-butyl complexes [(Cp Me ) 2 M( n Bu)] 2 (M = Y, Dy) were synthesized and their reactivity towards to ferrocene and bulky N-heterocyclic carbenes investigated. Selective mono-deprotonation of ferrocene and a benzylic methyl group of IMes were observed, whereas a control reaction of (Cp Me ) 3 M with IMes resulted in a normal-to-abnormal NHC rearrangement.

Semi-industrial isolation of salicin and amygdalin from plant extracts using slow rotary counter-current chromatography.

PubMed

Du, Qizhen; Jerz, Gerold; Ha, Yangchun; Li, Lei; Xu, Yuanjin; Zhang, Qi; Zheng, Qunxiong; Winterhalter, Peterb; Ito, Yoichiro

2005-05-13

Salicin in the bark extract of Salix alba and amygdalin in the fruit extract of Semen armeniacae were each separated by slow rotary counter-current chromatography (SRCCC). The apparatus was equipped with a 40-L column made of 17 mm i.d. convoluted Teflon tubing. A 500g amount of crude extract containing salicin at 13.5% was separated yielding 63.5 g of salicin at 95.3% purity in 20h using methyl tert-butyl ether-l-butanol (1:3) saturated by methanol-water (1:5) as a stationary phase and methanol-water (1:5) saturated by methyl tert-butyl ether-1-butanol (1:3) as a mobile phase. A 400g amount of crude extract containing amygdalin at 55.3% was isolated to yield 221.2g of amygdalin at 94.1% purity in 19h using ethyl acetate-1-butanol (1:2) saturated by water as a stationary phase and water saturated by ethyl acetate-1-butanol (1:2) as a mobile phase. The flow rate of the mobile phase was 50 ml/min. The results show that industrial SRCCC separation of salicin and amygdalin is feasible using a larger column at a higher flow rate of the mobile phase.

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

EPA Science Inventory

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

Anaerobic degradation of a mixture of MtBE, EtBE, TBA, and benzene under different redox conditions.

PubMed

van der Waals, Marcelle J; Pijls, Charles; Sinke, Anja J C; Langenhoff, Alette A M; Smidt, Hauke; Gerritse, Jan

2018-04-01

The increasing use of biobased fuels and fuel additives can potentially change the typical fuel-related contamination in soil and groundwater. Anaerobic biotransformation of the biofuel additive ethyl tert-butyl ether (EtBE), as well as of methyl tert-butyl ether (MtBE), benzene, and tert-butyl alcohol (TBA, a possible oxygenate metabolite), was studied at an industrially contaminated site and in the laboratory. Analysis of groundwater samples indicated that in the field MtBE was degraded, yielding TBA as major product. In batch microcosms, MtBE was degraded under different conditions: unamended control, with medium without added electron acceptors, or with ferrihydrite or sulfate (with or without medium) as electron acceptor, respectively. Degradation of EtBE was not observed under any of these conditions tested. TBA was partially depleted in parallel with MtBE. Results of microcosm experiments with MtBE substrate analogues, i.e., syringate, vanillate, or ferulate, were in line with the hypothesis that the observed TBA degradation is a cometabolic process. Microcosms with ferulate, syringate, isopropanol, or diethyl ether showed EtBE depletion up to 86.5% of the initial concentration after 83 days. Benzene was degraded in the unamended controls, with medium without added electron acceptors and with ferrihydrite, sulfate, or chlorate as electron acceptor, respectively. In the presence of nitrate, benzene was only degraded after addition of an anaerobic benzene-degrading community. Nitrate and chlorate hindered MtBE, EtBE, and TBA degradation.

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

PubMed

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

2015-06-18

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

Exposure to MTBE, TAME and aromatic hydrocarbons during gasoline pump maintenance, repair and inspection.

PubMed

Vainiotalo, Sinikka; Kuusimäki, Leea; Pekari, Kaija

2006-09-01

The exposure of gasoline pump repairers and inspectors to gasoline was studied at service stations and repair shops in Finland in April-June 2004. The average air temperature ranged from 7 degrees C to 16 degrees C and wind speed from 2.5 to 7 m/s. The gasoline blends contained mixtures of methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME), the total content of oxygenates being 11-12%. The content of benzene was <1%. Breathing zone air was collected during the work task using passive monitors. The mean sampling period was 4.5 h. The mean TWA-8 h concentrations for MTBE, TAME, hexane, benzene, toluene, ethylbenzene and xylene were 4.5, 1.3, 0.55, 0.23, 2.2, 0.26 and 1.1 mg/m3, respectively. None of the individual benzene concentrations exceeded the binding limit value for benzene (3.25 mg/m3). The sum concentration of MTBE and TAME in urine was between 8.9 and 530 nmol/l in individual post-shift samples. The individual sum concentrations of the metabolites tert-butyl alcohol and tert-amyl alcohol collected the following morning after the exposure ranged from 81 to 916 nmol/l. All individual results were below corresponding biological action levels. Exposure to aromatic hydrocarbons was estimated from post-shift urine samples, with benzene showing the highest concentration (range 4.4 and 35 nmol/l in non-smokers). The exposure levels were similar to those measured in previous studies during unloading of tanker lorries and railway wagons. The results indicated a slightly higher exposure for inspectors, who calibrated fuel pump gauges at the service stations, than for pump repairers. No significant skin exposure occurred during the study.

Synthesis and characterization of phosphonates from methyl linoleate and vegetable oils

USDA-ARS?s Scientific Manuscript database

Phosphonates were synthesized on a medium scale (~200 g) from three lipids: methyl linoleate (MeLin), high-oleic sunflower oil (HOSO), and soybean oil (SBO), and three dialkyl phosphites: methyl, ethyl, and n-butyl, using radical initiator. A staged addition of the lipid and the initiator was needed...

Risk characterization of methyl tertiary butyl ether (MTBE) in tap water.

PubMed

Stern, B R; Tardiff, R G

1997-12-01

Methyl tertiary butyl ether (MTBE) can enter surface water and groundwater through wet atmospheric deposition or as a result of fuel leaks and spills. About 30% of the U.S. population lives in areas where MTBE is in regular use. Ninety-five percent of this population is unlikely to be exposed to MTBE in tap water at concentrations exceeding 2 ppb, and most will be exposed to concentrations that are much lower and may be zero. About 5% of this population may be exposed to higher levels of MTBE in tap water, resulting from fuel tank leaks and spills into surface or groundwater used for potable water supplies. This paper describes the concentration ranges found and anticipated in surface and groundwater, and estimates the distribution of doses experienced by humans using water containing MTBE to drink, prepare food, and shower/bathe. The toxic properties (including potency) of MTBE when ingested, inhaled, and in contact with the skin are summarized. Using a range of human toxic potency values derived from animal studies, margins of exposure (MOE) associated with alternative chronic exposure scenarios are estimated to range from 1700 to 140,000. Maximum concentrations of MTBE in tap water anticipated not to cause adverse health effects are determined to range from 700 to 14,000 ppb. The results of this analysis demonstrate that no health risks are likely to be associated with chronic and subchronic human exposures to MTBE in tap water. Although some individuals may be exposed to very high concentrations of MTBE in tap water immediately following a localized spill, these exposures are likely to be brief in duration due to large-scale dilution and rapid volatilization of MTBE, the institution of emergency response and remediation measures to minimize human exposures, and the low taste and odor thresholds of MTBE which ensure that its presence in tap water is readily detected at concentrations well below the threshold for human injury.

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

EPA Science Inventory

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

Synthesis and characterization of phosphonates from methyl linoleate and vegetable oils

USDA-ARS?s Scientific Manuscript database

Phosphonates were synthesized on a medium scale (~200 g) from three lipids: methyl linoleate (MeLin), high-oleic sunflower oil (HOSO) and soybean oil (SBO), and three dialkyl phosphites: methyl, ethyl and n-butyl, using a radical initiator. A staged addition of the lipid and the initiator to the dia...

Synthesis and characterization of phosphonates from methyl linoleate and vegetable oils

USDA-ARS?s Scientific Manuscript database

Phosphonates were synthesized on a medium scale (~200 g) from three lipids–methyl linoleate (MeLin), high-oleic sunflower oil (HOSO) and soybean oil (SBO), and three dialkyl phosphites–methyl, ethyl and n-butyl, using a radical initiator. A staged addition of the lipid and the initiator was used to ...

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

PubMed Central

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

2003-01-01

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

Monitoring of BHT-quinone and BHT-CHO in the gas of capsules of Asclepias physocarpa.

PubMed

Ma, Bing-Ji; Peng, Hua; Liu, Ji-Kai

2006-01-01

Three volatile components, namely benzoic acid ethyl ester (1), 2,6-di-tert-butyl-p-benzoquinone (BHT-quinone) (2), and 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHT-CHO) (3), were detected from the gas in the capsules of Asclepias physocarpa by means of GC/MS analysis. BHT-quinone and BHT-CHO as organic pollutants are the degradation products of the antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). Ground water, lake water and/or rain water are a source of BHT metabolites in the plant Asclepias physocarpa.

Phenoxide and alkoxide complexes of Mg, Al and Zn, and their use for the ring-opening polymerization of ℇ-caprolactone with initiators of different natures.

PubMed

Minyaev, Mikhail E; Nifant'ev, Ilya E; Shlyakhtin, Andrey V; Ivchenko, Pavel V; Lyssenko, Konstantin A

2018-05-01

A new packing polymorph of bis(2,6-di-tert-butyl-4-methylphenolato-κO)bis(tetrahydrofuran-κO)magnesium, [Mg(C 15 H 23 O) 2 (C 4 H 8 O) 2 ] or Mg(BHT) 2 (THF) 2 , (BHT is the 2,6-di-tert-butyl-4-methylphenoxide anion and THF is tetrahydrofuran), (1), has the same space group (P2 1 ) as the previously reported modification [Nifant'ev et al. (2017d). Dalton Trans. 46, 12132-12146], but contains three crystallographically independent molecules instead of one. The structure of (1) exhibits rotational disorder of the tert-butyl groups and positional disorder of a THF ligand. The complex of bis(2,6-di-tert-butyl-4-methylphenolato-κO)bis(μ 2 -ethyl glycolato-κ 2 O,O':κO)dimethyldialuminium, [Al 2 (CH 3 ) 2 (C 4 H 7 O 3 ) 2 (C 15 H 23 O) 2 ] or [(BHT)AlMe(OCH 2 COOEt)] 2 , (2), is a dimer located on an inversion centre and has an Al 2 O 2 rhomboid core. The 2-ethoxy-2-oxoethanolate ligand (OCH 2 COOEt) displays a μ 2 -κ 2 O,O':κO semi-bridging coordination mode, forming a five-membered heteronuclear Al-O-C-C-O ring. The same ligand exhibits positional disorder of the terminal methyl group. The redetermined structure of the heptanuclear complex octakis(μ 3 -benzyloxo-κO:κO:κO)hexaethylheptazinc, [Zn 7 (C 2 H 5 ) 6 (C 7 H 7 O) 8 ] or [Zn 7 (OCH 2 Ph) 8 Et 6 ], (3), possesses a bicubic Zn 7 O 8 core located at an inversion centre and demonstrates positional disorder of one crystallographically independent phenyl group. Cambridge Structural Database surveys are given for complexes structurally analogous to (2) and (3). Complexes (2) and (3), as well as derivatives of (1), are of interest as catalysts for the ring-opening polymerization of ℇ-caprolactone, and polymerization results are reported.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deeb, Dorrah; Gao, Xiaohua; Liu, Yongbo

2012-06-15

Highlights: Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT gene expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT protein expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT telomerase activity. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT regulatory proteins. -- Abstract: Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a multifunctional oleanane synthetic triterpenoid with potent anti-inflammatory and antitumorigenic properties. The mechanisms of the antisurvival and apoptosis-inducing activities of CDDO-Me and related derivatives of oleanolic acid have been defined; however, to date, no study has been carried out on the effect of CDDOs on human telomerase reverse transcriptase (hTERT) gene or telomerase activity. Here we report for the first time that inhibition of cell proliferation and induction of apoptosismore » 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.« less

Steric/π-electronic insulation of the carbo-benzene ring: dramatic effects of tert-butyl vs phenyl crowns on geometric, chromophoric, redox and magnetic properties.

PubMed

Listunov, Dymytrii; Duhayon, Carine; Poater, Albert; Mazères, Serge; Saquet, Alix; Maraval, Valérie; Chauvin, Remi

2018-04-13

Hexa-tert-butyl-carbo-benzene C18tBu6 and three phenylated counterparts C18tBumPh6-m (m = 4, 2) have been synthesized. The peralkylated version (m = 6) provides experimental access to intrinsic features of the insulated C18 core independently from the influence of π-conjugated substituent. Over the series, structural, spectroscopical and electrochemical properties are compared with those of the hexaphenylated reference (m = 0). Anchoring tBu substituents at the C18 macrocycle is shown to enhance stability and solubility, and to dramatically modify UV-vis absorption and redox properties. Whereas all the carbo-benzenes reported hitherto were obtained as dark-reddish/greenish solids, crystals and solutions of C18tBu6 happen to be yellow (max = 379 nm vs 472 nm for C18Ph6). By comparison to C18Ph6, reduction of C18tBu6 remains reversible but occurs at a twice higher absolute potential (E1/2 = -1.36 V vs -0.72 V). Systematic X-ray diffraction analyses and DFT calculations show that the C18 ring symmetry is the nearest to D6h for m = 6, indicating a maximum geometrical aromaticity. According to calculated nucleus independent chemical shifts, the macrocyclic magnetic aromaticity is also found to be maximum for C18tBu6: NICS(0)=-17.2 ppm, vs -18.0±0.1 ppm for the theoretical references C18H6 and C18F6, and -13.5 ppm for C18Ph6. Accurate correlations of NICS(0) with experimental or calculated maximum UV-vis absorption wavelength max and chemical hardness =ELUMO-EHOMO are evidenced. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low coordinated mononuclear erbium(iii) single-molecule magnets with C3v symmetry: a method for altering single-molecule magnet properties by incorporating hard and soft donors.

PubMed

Zhang, Haitao; Nakanishi, Ryo; Katoh, Keiichi; Breedlove, Brian K; Kitagawa, Yasutaka; Yamashita, Masahiro

2018-01-02

Structures and magnetic characteristics of two three-coordinate erbium(iii) compounds with C 3v geometry, tris(2,6-di-tert-butyl-p-cresolate)erbium, Er(dbpc) 3 (1) and tris(bis(trimethylsilyl)methyl)erbium, Er(btmsm) 3 (2), were determined. Both underwent temperature-dependent slow magnetic relaxation processes in the absence of an external magnetic field. As a result of the differences in the coordination environment, they exhibit different energy barriers and quantum tunneling of magnetization (QTM) constants.

Effect of H2 and redox condition on biotic and abiotic MTBE transformation

USGS Publications Warehouse

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

2006-01-01

Laboratory studies conducted with surface water sediment from a methyl tert-butyl ether (MTBE)-contaminated site in South Carolina demonstrated that, under methanogenic conditions, [U-14C] MTBE was transformed to 14C tert-butyl alcohol (TBA) with no measurable production of 14CO2. Production of TBA was not attributed to the activity of methanogenic microorganisms, however, because comparable transformation of [U-14C] MTBE to 14C-TBA also was observed in heat-sterilized controls with dissolved H2 concentrations > 5 nM. The results suggest that the transformation of MTBE to TBA may be an abiotic process that is driven by biologically produced H2 under in situ conditions. In contrast, mineralization of [U-14C] MTBE to 14CO2 was completely inhibited by heat sterilization and only observed in treatments characterized by dissolved H2 concentrations < 2 nM. These results suggest that the pathway of MTBE transformation is influenced by in situ H2 concentrations and that in situ H2 concentrations may be an useful indicator of MTBE transformation pathways in ground water systems.

Effect of redox conditions on MTBE biodegradation in surface water Sediments

USGS Publications Warehouse

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

2001-01-01

Microbial degradation of methyl tert-butyl ether (MTBE) was observed in surface water-sediment microcosms under anaerobic conditions. The efficiency and products of anaerobic MTBE biodegradation were dependent on the predominant terminal electron-accepting conditions. In the presence of substantial methanogenic activity, MTBE biodegradation was nominal and involved reduction of MTBE to the toxic product, tert-butyl alcohol (TBA). In the absence of significant methanogenic activity, accumulation of [14C]TBA generally decreased, and mineralization of [U-14C]MTBE to 14CO2 generally increased as the oxidative potential of the predominant terminal electron acceptor increased in the order of SO4, Fe(III), Mn(IV) < NO3 < O2. Microbial mineralization of MTBE to CO2 under Mn(IV)or SO4-reducing conditions has not been reported previously. The results of this study indicate that microorganisms inhabiting the sediments of streams and lakes can degrade MTBE effectively under a range of anaerobic terminal electron-accepting conditions. Thus, anaerobic bed sediment microbial processes may provide a significant environmental sink for MTBE in surface water systems throughout the United States.

Calculated volatilization rates of fuel oxygenate compounds and other gasoline-related compounds from rivers and streams

USGS Publications Warehouse

Pankow, J.F.; Rathbun, R.E.; Zogorski, J.S.

1996-01-01

Large amounts of the 'fuel-oxygenate' compound methyl-tert-butyl ether (MTBE) are currently being used in gasoline to reduce carbon monoxide and ozone in urban air and to boost fuel octane. Because MTBE can be transported to surface waters in various ways, established theory was used to calculate half-lives for MTBE volatilizing from flowing surface waters. Similar calculations were made for benzene as a representative of the 'BTEX' group of compounds (benzene, toluene, ethyl benzene, and the xylenes), and for tert-butyl alcohol (TBA). The calculations were made as a function of the mean flow velocity u (m/day), the mean flow depth h (m), the ambient temperature, and the wind speed. In deep, slow-moving flows, MTBE volatilizes at rates which are similar to those for the BTEX compounds. In shallow, fast-moving flows, MTBE volatilizes more slowly than benzene, though in such flows both MTBE and benzene volatilize quickly enough that these differences may often not have much practical significance. TBA was found to be essentially nonvolatile from water.

Cancer-associated TERT promoter mutations abrogate telomerase silencing

PubMed Central

Chiba, Kunitoshi; Johnson, Joshua Z; Vogan, Jacob M; Wagner, Tina; Boyle, John M; Hockemeyer, Dirk

2015-01-01

Mutations in the human telomerase reverse transcriptase (TERT) promoter are the most frequent non-coding mutations in cancer, but their molecular mechanism in tumorigenesis has not been established. We used genome editing of human pluripotent stem cells with physiological telomerase expression to elucidate the mechanism by which these mutations contribute to human disease. Surprisingly, telomerase-expressing embryonic stem cells engineered to carry any of the three most frequent TERT promoter mutations showed only a modest increase in TERT transcription with no impact on telomerase activity. However, upon differentiation into somatic cells, which normally silence telomerase, cells with TERT promoter mutations failed to silence TERT expression, resulting in increased telomerase activity and aberrantly long telomeres. Thus, TERT promoter mutations are sufficient to overcome the proliferative barrier imposed by telomere shortening without additional tumor-selected mutations. These data establish that TERT promoter mutations can promote immortalization and tumorigenesis of incipient cancer cells. DOI: http://dx.doi.org/10.7554/eLife.07918.001 PMID:26194807

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

PubMed

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

1999-02-01

We studied customer exposure during refueling by collecting air samples from customers' breathing zone. The measurements were carried out during 4 days in summer 1996 at two Finnish self-service gasoline stations with "stage I" vapor recovery systems. The 95-RON (research octane number) gasoline contained approximately 2.7% methyl tert-butyl ether (MTBE), approximately 8.5% tert-amyl methyl ether (TAME), approximately 3.2% C6 alkyl methyl ethers (C6 AMEs), and 0.75% benzene. The individual exposure concentrations showed a wide log-normal distribution, with low exposures being the most frequent. In over 90% of the samples, the concentration of MTBE was higher (range <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

The uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether inhaled alone and in combination with gasoline vapor.

PubMed

Benson, Janet M; Tibbetts, Brad M; Barr, Edward B

2003-06-13

The purpose of these studies was to evaluate the tissue uptake, distribution, metabolism, and excretion of methyl tertiary-butyl ether (MTBE) in rats and to determine the effects of coinhalation of the volatile fraction of unleaded gasoline on these parameters. Male F344 rats were exposed nose-only once for 4 h to 4, 40, or 400 ppm 14C-MTBE and to 20 and 200 ppm of the light fraction of unleaded gasoline (LFG) containing 4 and 40 ppm 14C-MTBE, respectively. To evaluate the effects of repeated inhalation of LFG on the fate of inhaled MTBE, rats were exposed for 7 consecutive days to 20 and 200 ppm LFG followed on d 8 by exposure to LFG containing 14C-MTBE. Three subgroups of rats were included for evaluation of respiratory parameters, rates and routes of excretion, and tissue distribution and elimination. MTBE and its chief metabolite, tertiary-butyl alcohol, were quantitated in blood and kidney (immediately after exposure), and the major urinary metabolites, 2-hydroxyisobutyric acid and 2-methyl-1,2- propanediol, were identified and quantified in urine. Inhalation of MTBE alone or as a component of LFG had no concentration-dependent effect on respiratory minute volume. The initial body burdens (IBBs) of MTBE equivalents achieved after 4 h of exposure to MTBE did not increase linearly with exposure concentration. MTBE equivalents rapidly distributed to all tissues examined, with the largest percentages distributed to liver. Between 40 and 400 ppm, there was a significant reduction in percentage of the IBB present in the major organs examined, both immediately and 72 h after exposure. At 400 ppm, the elimination rates of MTBE equivalents from tissues changed significantly. Furthermore, at 400 ppm there was a significant decrease in the elimination half-time of volatile organic compounds (VOCs) in breath and a significant increase in the percentage of the IBB of MTBE equivalents eliminated as VOCs in breath. LFG coexposure significantly decreased the percentage of the

[Determination of migration of 25 primary aromatic amines from food contact plastic materials by gas chromatography-mass spectrometry].

PubMed

Li, Ying; Li, Chengfa; Xiao, Daoqing; Liang, Feng; Chen, Zhinan; Schen, Xuhui; Sun, Xiaoying; Li, Yongtao

2013-01-01

A solid phase extraction (SPE) combination with gas chromatography-mass spectrometry (GC-MS) was developed for the determination of the migration of 25 primary aromatic amines (PAAs) from food contact plastic materials and articles. The samples were extracted by deionized water and 30 g/L acetic acid, and the pH value of the solution was adjusted to 8 - 10 with ammonia. The extracts were cleaned up and concentrated on an SPE column, then eluted by equal volume of methyl-tert-butyl ether and ethanol. The analysis of the target compounds was performed by GC-MS. The results indicated that the limits of detection were in the range of 0.4 -2.0 microg/kg for different PAAs. The recoveries and relative standard deviations (n = 7) of 10 microg/kg PAAs ranged from 51.6% -118.4% and 0.5% -9.8%, respectively, except the 2,4-diaminoanisole in the acid simulant. The effects of different experimental conditions such as the pH value and volume ratio of methyl-tert-butyl ether and ethanol were studied. The results showed that the method is accurate and stable, and could meet the requirement of the European Commission Regulation (EU) No 10/2011 for the determination of primary aromatic amines. It can be applied in the analysis of the primary aromatic amines in real food contact plastic material and article samples.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arıcı, Mürsel, E-mail: marici@ogu.edu.tr; Zafer Yeşilel, Okan; Büyükgüngör, Orhan

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

CUDR promotes liver cancer stem cell growth through upregulating TERT and C-Myc

PubMed Central

Pu, Hu; Zheng, Qidi; Li, Haiyan; Wu, Mengying; An, Jiahui; Gui, Xin; Li, Tianming; Lu, Dongdong

2015-01-01

Cancer up-regulated drug resistant (CUDR) is a novel non-coding RNA gene. Herein, we demonstrate excessive CUDR cooperates with excessive CyclinD1 or PTEN depletion to accelerate liver cancer stem cells growth and liver stem cell malignant transformation in vitro and in vivo. Mechanistically, we reveal the decrease of PTEN in cells may lead to increase binding capacity of CUDR to CyclinD1. Therefore, CUDR-CyclinD1 complex loads onto the long noncoding RNA H19 promoter region that may lead to reduce the DNA methylation on H19 promoter region and then to enhance the H19 expression. Strikingly, the overexpression of H19 increases the binding of TERT to TERC and reduces the interplay between TERT with TERRA, thus enhancing the cell telomerase activity and extending the telomere length. On the other hand, insulator CTCF recruits the CUDR-CyclinD1 complx to form the composite CUDR-CyclinD1-insulator CTCF complex which occupancied on the C-myc gene promoter region, increasing the outcome of oncogene C-myc. Ultimately, excessive TERT and C-myc lead to liver cancer stem cell and hepatocyte-like stem cell malignant proliferation. To understand the novel functions of long noncoding RNA CUDR will help in the development of new liver cancer therapeutic and diagnostic approaches. PMID:26513297

New evidence for primordial action site of Fluazifop-P-butyl on Acanthospermum hispidum seedlings: From the effects on chlorophyll fluorescence characteristics and histological observation.

PubMed

Shang, Yuhong; Yang, Congjun; Liu, Zhihang; Song, Jiqing; Li, Pingliang; Li, Lingxu; Zhou, Fei; Xin, Hua; Wan, Fanghao; Matsumoto, Hiroshi; Luo, Xiaoyong

2017-10-01

Acanthospermum hispidum DC, an Asteraceae weed species, was very susceptible to fluazifop-P-butyl, but tolerant to other aryloxyphenoxypropionate herbicides, such as haloxyfop-P-methyl. However, other Asteraceae weeds including Bidens pilosa were all tolerant to fluazifop-P-butyl. Membrane lipid peroxidation by increasing the levels of reactive oxygen species (ROS) was proposed as an action mechanism of fluazifop-P-butyl in A. hispidum. To further clarify the primordial action site of fluazifop-P-butyl in this species, the effects on chlorophyll fluorescence characteristics and cytohistology of apical meristems were studied. Chlorophyll fluorescence characteristics (CFC) in sensitive A. hispidum seedlings were markedly affected by 10μM fluazifop-P-butyl, with the dark fluorescence yield (Fo), maximal fluorescence yield (Fm), maximal PS II quantum yield (Fv/Fm), effective photosystem II (PS II) quantum yield [Y(II)], and quantum yield of regulated energy dissipation [Y(NPQ)] declining, quantum yield of nonregulated energy dissipation [Y(NO)] rising, but these measures were not affected in Bidens pilosa. The effects of fluazifop-P-butyl on chlorophyll fluorescence properties were observed on the growing point before the mature leaves by about 4-6h. Haloxyfop-P-methyl, a control herbicide, had no effects on CFC of either A. hispidum or B. pilosa. In addition, damage to apical meristem cells of A. hispidum was observed at 6 HAT prior to changes in chlorophyll fluorescence parameters suggesting that the primary action site of fluazifop-P-butyl in this species is in the apical meristem and the effects on CFC may be the results of secondary action. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis and evaluation of new antimalarial analogues of quinoline alkaloids derived from Cinchona ledgeriana Moens ex Trimen.

PubMed

Park, Byeoung-Soo; Kim, Dae-Young; Rosenthal, Philip J; Huh, Sun-Chul; Lee, Belinda J; Park, Eun -u; Kim, Sung-Min; Kim, Jang-Eok; Kim, Mi-Hee; Huh, Tae-Lin; Choi, Young-Jae; Suh, Ki-Hyung; Choi, Won-Sik; Lee, Sung-Eun

2002-05-20

In the course of attempts to develop antimalarial drugs, we have designed and synthesized a series of quinoline alkaloide derivatives. Three of them, N-(4-methoxy-3,5-di-tert-butylbenzyl)cinchonidinium bromide (OSL-5), O-benzyl-N-(3,5-di-tert-butyl-4-methoxybenzyl)cinchonidinium bromide (OSL-7), and N-(3,5-di-tert-butyl-4-methoxybenzyl)quininium bromide (OSL-14) show potent activity against Plasmodium falciparum.

MTBE, TBA, and TAME attenuation in diverse hyporheic zones.

PubMed

Landmeyer, James E; Bradley, Paul M; Trego, Donald A; Hale, Kevin G; Haas, Joseph E

2010-01-01

Groundwater contamination by fuel-related compounds such as the fuel oxygenates methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA), and tert-amyl methyl ether (TAME) presents a significant issue to managers and consumers of groundwater and surface water that receives groundwater discharge. Four sites were investigated on Long Island, New York, characterized by groundwater contaminated with gasoline and fuel oxygenates that ultimately discharge to fresh, brackish, or saline surface water. For each site, contaminated groundwater discharge zones were delineated using pore water geochemistry data from 15 feet (4.5 m) beneath the bottom of the surface water body in the hyporheic zone and seepage-meter tests were conducted to measure discharge rates. These data when combined indicate that MTBE, TBA, and TAME concentrations in groundwater discharge in a 5-foot (1.5-m) thick section of the hyporheic zone were attenuated between 34% and 95%, in contrast to immeasurable attenuation in the shallow aquifer during contaminant transport between 0.1 and 1.5 miles (0.1 to 2.4 km). The attenuation observed in the hyporheic zone occurred primarily by physical processes such as mixing of groundwater and surface water. Biodegradation also occurred as confirmed in laboratory microcosms by the mineralization of U- (14)C-MTBE and U-(14)C-TBA to (14)CO(2) and the novel biodegradation of U- (14)C-TAME to (14)CO(2) under oxic and anoxic conditions. The implication of fuel oxygenate attenuation observed in diverse hyporheic zones suggests an assessment of the hyporheic zone attenuation potential (HZAP) merits inclusion as part of site assessment strategies associated with monitored or engineered attenuation.

MTBE, TBA, and TAME attenuation in diverse hyporheic zones

USGS Publications Warehouse

Landmeyer, J.E.; Bradley, P.M.; Trego, D.A.; Hale, K.G.; Haas, J.E.

2010-01-01

Groundwater contamination by fuel-related compounds such as the fuel oxygenates methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA), and tert-amyl methyl ether (TAME) presents a significant issue to managers and consumers of groundwater and surface water that receives groundwater discharge. Four sites were investigated on Long Island, New York, characterized by groundwater contaminated with gasoline and fuel oxygenates that ultimately discharge to fresh, brackish, or saline surface water. For each site, contaminated groundwater discharge zones were delineated using pore water geochemistry data from 15 feet (4.5 m) beneath the bottom of the surface water body in the hyporheic zone and seepage-meter tests were conducted to measure discharge rates. These data when combined indicate that MTBE, TBA, and TAME concentrations in groundwater discharge in a 5-foot (1.5-m) thick section of the hyporheic zone were attenuated between 34% and 95%, in contrast to immeasurable attenuation in the shallow aquifer during contaminant transport between 0.1 and 1.5 miles (0.1 to 2.4 km). The attenuation observed in the hyporheic zone occurred primarily by physical processes such as mixing of groundwater and surface water. Biodegradation also occurred as confirmed in laboratory microcosms by the mineralization of U- 14C-MTBE and U- 14C-TBA to 14CO2 and the novel biodegradation of U- 14C-TAME to 14CO2 under oxic and anoxic conditions. The implication of fuel oxygenate attenuation observed in diverse hyporheic zones suggests an assessment of the hyporheic zone attenuation potential (HZAP) merits inclusion as part of site assessment strategies associated with monitored or engineered attenuation. ?? 2009 National Ground Water Association.

Brucine diol-copper-catalyzed asymmetric synthesis of endo-pyrrolidines: the mechanistic dichotomy of imino esters.

PubMed

Li, Jian-Yuan; Kim, Hun Young; Oh, Kyungsoo

2015-03-06

Enantio- and diastereodivergent approaches to pyrrolidines are described by using catalyst- and substrate-controlled reaction pathways. A concerted endo-selective [3 + 2]-cycloaddition pathway is developed for the reaction of methyl imino ester, whereas endo-pyrrolidines with an opposite absolute stereochemical outcome are prepared by using the stepwise reaction pathway of tert-butyl imino ester. The development of catalyst- and substrate-controlled stereodivergent approaches highlights the inherent substrate-catalyst interactions in the [3 + 2]-cycloaddition reactions of metalated azomethine ylides.

Enterovirus inhibitory activity of C-8-tert-butyl substituted 4-aryl-6,7,8,9-tetrahydrobenzo[4,5]thieno[3,2-e][1,2,4]triazolo[4,3-a]pyrimidin-5(4H)-ones.

PubMed

Kumar Biswas, Bishyajit; Malpani, Yashwardhan R; Ha, Neul; Kwon, Do-Hyun; Soo Shin, Jin; Kim, Hae-Soo; Kim, Chonsaeng; Bong Han, Soo; Lee, Chong-Kyo; Jung, Young-Sik

2017-08-01

Members of a series of 4-aryl-6,7,8,9-tetrahydrobenzo[4,5]thieno[3,2-e][1,2,4]triazolo[4,3-a]pyrimidin-5(4H)-ones (1, Fig. 2) were prepared and tested against representative enteroviruses including Human Coxsackievirus B1 (Cox B1), Human Coxsackievirus B3 (Cox B3), human Poliovirus 3 (PV3), human Rhinovirus 14 (HRV14), human Rhinovirus 21 (HRV 21) and human Rhinovirus 71 (HRV 71). The C-8-tert-butyl group on the tetrahydrobenzene ring in these substances was found to be crucial for their enterovirus activity. One member of this group, 1e, showed single digit micromolar activities (1.6-8.85μM) against a spectrum of viruses screened, and the highest selectivity index (SI) values for Cox B1 (>11.2), for Cox B3 (>11.5), and for PV3 (>51.2), respectively. In contrast, 1p, was the most active analog against the selected HRVs (1.8-2.6μM), and showed the highest selectivity indices among the group of compounds tested. The SI values for 1p were 11.5 for HRV14, 8.4 for HRV21, and 12.1 for HRV71, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Efficacy of Myricetin as an Antioxidant in Methyl Esters of Soybean Oil

USDA-ARS?s Scientific Manuscript database

The antioxidant activity of myricetin, a natural flavonol found in fruits and vegetables, was determined in soybean oil methyl esters (SME) and compared with alpha-tocopherol and tert-butylhydroquinone (TBHQ) over a 90 day period employing EN 14112, acid value, and kinematic viscosity methods. Myri...

Optical and electrochemical characteristics of Ir(III) complexes with metalated 4-(4-bromophenyl)-2-methyl-1,3-thiazole and isocyanide, ethylenediamine, and diethyldithiocarbamate ligands

NASA Astrophysics Data System (ADS)

Katlenok, E. A.; Kinzhalov, M. A.; Eremina, A. A.; Balashev, K. P.

2017-05-01

The influence of donor-acceptor properties of tert-butyl-, 2.6-dimethylphenyl-, and 4-bromophenyl-isocyanides (BuNC, XylNC, BpNC), ethylenediamine (En), and diethyldithiocarbamate ions (Dtc-) on the 1H and 13C NMR, IR, optical, and electrochemical characteristics of Ir(III) complexes with metalated 4-(4-bromophenyl)-2-methyl-1,3-thiazole is studied. Enhancement of the donor properties of BpNC, XylNC, BuNC, En, and Dtc- ligands leads to a bathochromic shift of metal-to-ligand charge transfer (MLCT) bands and to a decrease in the difference between the one-electron oxidation and reduction potentials of complexes. The bathochromic shift of the low-temperature phosphorescence of complexes in frozen (77 K) solutions with increasing donor properties of BpNC, XylNC, BuNC, En, and Dtc-ligands is caused by a decrease in the admixture of MLCT to the intraligand excited state of {Ir(bptz)2}. Quenching of the phosphorescence of complexes in liquid solutions is attributed to the thermally-induced population of excited d- d* states with subsequent nonradiative deactivation.

Hydroalumination of a chlorotrialkynylsilane: spontaneous stepwise 1,3-dyotropic rearrangement via an intermediate silyl cation.

PubMed

Uhl, Werner; Bohnemann, Jörg; Layh, Marcus; Würthwein, Ernst-Ulrich

2014-07-07

A new functionalised alkynylsilane, Cl-Si(CC-CMe3 )3 (3), was obtained by a facile multistep synthesis. Treatment of 3 with equimolar quantities of the hydrides H-M(CMe3 )2 (M=Al, Ga) gave the mixed alkenyl-di(alkynyl)silanes, in which the chlorine atom adopts a bridging position between the aluminium and silicon atoms. Dual hydrogallation of 3 resulted in the formation of a di(alkenyl)-alkynylsilane containing two gallium atoms, one of which is coordinated to the chlorine atom, and the second is bonded to the α-carbon atom of the remaining alkynyl group. A tert-butylsilane was unexpectedly formed by a unique 1,3-dyotropic chlorine-tert-butyl exchange for the corresponding dialuminium compound. One aluminium atom is bonded to a tert-butyl group, a terminal chlorine atom and the α-carbon atom of the ethynyl moiety; the second is coordinatively unsaturated, with two terminal tert-butyl substituents. High-level quantum-chemical calculations favour a stepwise dyotropic rearrangement with an intermediate cationic silicon species over a simultaneous tert-butyl-chlorine migration via a five-coordinate silicon atom in the transition state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of thermocleavable functionality on organic field-effect transistor performance of small molecules

NASA Astrophysics Data System (ADS)

Mahale, Rajashree Y.; Dharmapurikar, Satej S.; Chini, Mrinmoy Kumar; Venugopalan, Vijay

2017-06-01

Diketopyrrolopyrrole based donor-acceptor-donor conjugated small molecules using ethylene dioxythiophene as a donor was synthesized. Electron deficient diketopyrrolopyrrole unit was substituted with thermocleavable (tert-butyl acetate) side chains. The thermal treatment of the molecules at 160 °C eliminated the tert-butyl ester group results in the formation of corresponding acid. Optical and theoretical studies revealed that the molecules adopted a change in molecular arrangement after thermolysis. The conjugated small molecules possessed p-channel charge transport characteristics in organic field effect transistors. The charge carrier mobility was increased after thermolysis of tert-butyl ester group to 5.07 × 10-5 cm2/V s.

Recurrent TERT promoter mutations identified in a large-scale study of multiple tumor types are associated with increased TERT expression and telomerase activation

PubMed Central

Huang, Dong-Sheng; Wang, Zhaohui; He, Xu-Jun; Diplas, Bill H.; Yang, Rui; Killela, Patrick J.; Liang, Junbo; Meng, Qun; Ye, Zai-Yuan; Wang, Wei; Jiang, Xiao-Ting; Xu, Li; He, Xiang-Lei; Zhao, Zhong-Sheng; Xu, Wen-Juan; Wang, Hui-Ju; Ma, Ying-Yu; Xia, Ying-Jie; Li, Li; Zhang, Ru-Xuan; Jin, Tao; Zhao, Zhong-Kuo; Xu, Ji; Yu, Sheng; Wu, Fang; Wang, Si-Zhen; Jiao, Yu-Chen; Yan, Hai; Tao, Hou-Quan

2015-01-01

Background Several somatic mutation hotspots were recently identified in the TERT promoter region in human cancers. Large scale studies of these mutations in multiple tumor types are limited, in particular in Asian populations. This study aimed to: analyze TERT promoter mutations in multiple tumor types in a large Chinese patient cohort, investigate novel tumor types and assess the functional significance of the mutations. Methods TERT promoter mutation status was assessed by Sanger sequencing for 13 different tumor types and 799 tumor tissues from Chinese cancer patients. Thymic epithelial tumors, gastrointestinal leiomyoma, and gastric schwannoma were included, for which the TERT promoter has not been previously sequenced. Functional studies included TERT expression by RT-qPCR, telomerase activity by the TRAP assay, and promoter activity by the luciferase reporter assay. Results TERT promoter mutations were highly frequent in glioblastoma (83.9%), urothelial carcinoma (64.5%), oligodendroglioma (70.0%), medulloblastoma (33.3%), and hepatocellular carcinoma (31.4%). C228T and C250T were the most common mutations. In urothelial carcinoma, several novel rare mutations were identified. TERT promoter mutations were absent in GIST, thymic epithelial tumors, gastrointestinal leiomyoma, gastric schwannoma, cholangiocarcinoma, gastric and pancreatic cancer. TERT promoter mutations highly correlated with upregulated TERT mRNA expression and telomerase activity in adult gliomas. These mutations differentially enhanced the transcriptional activity of the TERT core promoter. Conclusions TERT promoter mutations are frequent in multiple tumor types and have similar distributions in Chinese cancer patients. The functional significance of these mutations reflect the importance to telomere maintenance and hence tumorigenesis, making them potential therapeutic targets. PMID:25843513

In vitro and in vivo effect of 2,6-Di-tert-butyl-4-methylphenol as an antibiofilm agent against quorum sensing mediated biofilm formation of Vibrio spp.

PubMed

Santhakumari, Sivasubramanian; Jayakumar, Rengarajan; Logalakshmi, Ravichandran; Prabhu, Narayanan Marimuthu; Abdul Nazar, Abdul Kuthus; Karutha Pandian, Shunmugiah; Veera Ravi, Arumugam

2018-05-25

This study unveils the in vitro and in vivo antibiofilm potential of 2,6-Di-tert-butyl-4-methylphenol (DTBMP) from Chroococcus turgidus against Vibrio spp. In the preliminary study, cell free culture supernatant (CFCS) of C. turgidus inhibited the violacein production in biomarker strain Chromobacterium violaceum and its mutant strain CV026 in a dose dependent manner. The effective biofilm inhibitory concentration (BIC) of pure compound DTBMP from C. turgidus was identified as 250 μg/ml concentration in tested Vibrio species. Furthermore, DTBMP proved to effectively inhibit the bioluminescence production in V. harveyi and other biofilm related virulence traits such as exopolysaccharides (EPS) production, hydrophobicity index, swimming and swarming motility at its BIC concentration in three major pathogenic vibrios: V. harveyi, V. parahaemolyticus and V. vulnificus. The antibiofilm potential of DTBMP was validated through light, confocal laser scanning and scanning electron microscopic analyses. In addition, the non-bactericidal effect of DTBMP was determined through growth curve and 2,3-bis (2-methyloxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. Real-time PCR studies revealed the down-regulation of master quorum sensing (QS) regulator genes of V. harveyi such as luxR, luxS, luxP, luxQ and luxO on treatment with DTBMP. In vivo results confirmed that DTBMP augmented the survival rate of Litopenaeus vannamei larvae up to 75, 88 and 66% upon infection with V. harveyi, V. parahaemolyticus and V. vulnificus, respectively. The results of this study ascertain the promising effects of DTBMP as an antibiofilm agent, which could be positively explored to treat biofilm-associated vibrios infections in aquaculture. Copyright © 2018 Elsevier B.V. All rights reserved.

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

Toxicity of methyl tertiary-butyl ether (MTBE) following exposure of Wistar Rats for 13 weeks or one year via drinking water.

PubMed

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

2012-09-01

Thirteen-week and one-year toxicity studies of methyl tertiary-butyl ether (MTBE) administered in drinking water to Wistar rats were conducted. Male and female rats were exposed to MTBE in drinking water at 0.5, 3, 7.5 and 15 mg ml(-1) for 13 weeks and at 0.5, 3 and 7.5 (males) or 0.5, 3 and 15 mg ml(-1) (females) for 1 year. Body weights were reduced only in males following 13 weeks of exposure. Reduced water consumption and urine output were observed in males and females exposed to MTBE. Kidney cell replication and α(2u)-globulin levels in males were increased at 1 and 4 weeks of MTBE exposure and tubular cell regeneration was increased in male kidneys exposed to MTBE concentrations of 7.5 mg ml(-1) or greater for 13 weeks. Wet weights of male kidneys were increased following 13 weeks, 6 months and 1 year of exposure to MTBE concentrations of 7.5 mg ml(-1) or greater. Kidney wet weights were increased in females at MTBE concentrations of 15 mg ml(-1) for 13 weeks. Tertiary-butyl alcohol blood levels increased linearly with dose in males and females following 1 year of exposure. Chronic progressive nephropathy (CPN), of minimal to mild severity, increased in males, but not females, with 1 year of MTBE exposure. In summary, exposure of Wistar rats to MTBE in the drinking water resulted in minimal exposure-related effects including limited renal changes in male rats suggestive of α(2u)-globulin nephropathy following 13 weeks of exposure and an exacerbation of CPN in males at the end of 1 year of exposure. Copyright © 2011 John Wiley & Sons, Ltd.

Recurrent TERT promoter mutations identified in a large-scale study of multiple tumour types are associated with increased TERT expression and telomerase activation.

PubMed

Huang, Dong-Sheng; Wang, Zhaohui; He, Xu-Jun; Diplas, Bill H; Yang, Rui; Killela, Patrick J; Meng, Qun; Ye, Zai-Yuan; Wang, Wei; Jiang, Xiao-Ting; Xu, Li; He, Xiang-Lei; Zhao, Zhong-Sheng; Xu, Wen-Juan; Wang, Hui-Ju; Ma, Ying-Yu; Xia, Ying-Jie; Li, Li; Zhang, Ru-Xuan; Jin, Tao; Zhao, Zhong-Kuo; Xu, Ji; Yu, Sheng; Wu, Fang; Liang, Junbo; Wang, Sizhen; Jiao, Yuchen; Yan, Hai; Tao, Hou-Quan

2015-05-01

Several somatic mutation hotspots were recently identified in the telomerase reverse transcriptase (TERT) promoter region in human cancers. Large scale studies of these mutations in multiple tumour types are limited, in particular in Asian populations. This study aimed to: analyse TERT promoter mutations in multiple tumour types in a large Chinese patient cohort, investigate novel tumour types and assess the functional significance of the mutations. TERT promoter mutation status was assessed by Sanger sequencing for 13 different tumour types and 799 tumour tissues from Chinese cancer patients. Thymic epithelial tumours, gastrointestinal leiomyoma, and gastric schwannoma were included, for which the TERT promoter has not been previously sequenced. Functional studies included TERT expression by reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR), telomerase activity by the telomeric repeat amplification protocol (TRAP) assay and promoter activity by the luciferase reporter assay. TERT promoter mutations were highly frequent in glioblastoma (83.9%), urothelial carcinoma (64.5%), oligodendroglioma (70.0%), medulloblastoma (33.3%) and hepatocellular carcinoma (31.4%). C228T and C250T were the most common mutations. In urothelial carcinoma, several novel rare mutations were identified. TERT promoter mutations were absent in gastrointestinal stromal tumour (GIST), thymic epithelial tumours, gastrointestinal leiomyoma, gastric schwannoma, cholangiocarcinoma, gastric and pancreatic cancer. TERT promoter mutations highly correlated with upregulated TERT mRNA expression and telomerase activity in adult gliomas. These mutations differentially enhanced the transcriptional activity of the TERT core promoter. TERT promoter mutations are frequent in multiple tumour types and have similar distributions in Chinese cancer patients. The functional significance of these mutations reflect the importance to telomere maintenance and hence tumourigenesis, making them

Synthesis of polymer hybrid latex poly(methyl methacrylate-co-butyl acrylate) with organo montmorillonite via miniemulsion polymerization method for barrier paper

NASA Astrophysics Data System (ADS)

Chanra, J.; Budianto, E.; Soegijono, B.

2018-03-01

Hybrid polymer latex based on combination of organic-inorganic materials, poly(methyl methacrylate-co-butyl acrylate) (PMMBA) and organo-montmorillonite (OMMT) were synthesized via miniemulsion polymerization technique. Modification of montmorillonite (MMT) through the incorporation of myristyltrimethylammonium bromide (MTAB) into the clay’s interlayer spaces were investigated by Small-Angle X-ray Scattering (SAXS), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). Barrier property and thermal stability of polymer latex film sample were investigated through its Water Vapor Transmission Rate (WVTR) and Thermogravimetric Analysis (TGA). The results indicated that addition of OMMT as filler in PMMBA increased the barrier property and thermal stability of the latex film. Addition of 8.0% (wt) OMMT increased the barrier property and thermal stability. Miniemusion polymerization process with higher addition (>8.0 wt%) of OMMT resulting in high latex viscosity, particle size, and high amount of coagulum. The utilization of this hybrid polymer could benefits paper and board industries to produce high quality barrier paper for food packaging.

Impact of anisotropy on the structure and dynamics of ionic liquids: A computational study of 1-butyl-3-methyl-imidazolium trifluoroacetate

NASA Astrophysics Data System (ADS)

Schröder, C.; Rudas, T.; Neumayr, G.; Gansterer, W.; Steinhauser, O.

2007-07-01

The complex ionic network of 1-butyl-3-methyl-imidazolium trifluoroacetate was simulated by means of the molecular dynamics methods over a time period of 100ns. The influence of the anisotropy of the shape and charge distribution of both the cations and the anions on the local (molecular) and global (collective) structure and dynamics is analyzed. The distance-dependent g coefficients of the orientational probability function g(r,Ω) were found to be an excellent way to interpret local structure. Thereby, the combination and interrelation of individual g coefficients elucidate the mutual orientation. Dynamics at the molecular level is characterized by the time correlation function of the center-of-mass corrected molecular dipole moment μcm. Upon uniting the set of molecular dipoles to a single collective rotational dipole moment, MD, dynamics on a global level is studied. Decomposing into subsets of cations and anions respective self terms as well as the prominent cross term can be extracted. This decomposition also enables a detailed peak assignment in dielectric spectra.

Impact of anisotropy on the structure and dynamics of ionic liquids: a computational study of 1-butyl-3-methyl-imidazolium trifluoroacetate.

PubMed

Schröder, C; Rudas, T; Neumayr, G; Gansterer, W; Steinhauser, O

2007-07-28

The complex ionic network of 1-butyl-3-methyl-imidazolium trifluoroacetate was simulated by means of the molecular dynamics methods over a time period of 100 ns. The influence of the anisotropy of the shape and charge distribution of both the cations and the anions on the local (molecular) and global (collective) structure and dynamics is analyzed. The distance-dependent g coefficients of the orientational probability function g(r,Omega) were found to be an excellent way to interpret local structure. Thereby, the combination and interrelation of individual g coefficients elucidate the mutual orientation. Dynamics at the molecular level is characterized by the time correlation function of the center-of-mass corrected molecular dipole moment mucm. Upon uniting the set of molecular dipoles to a single collective rotational dipole moment, MD, dynamics on a global level is studied. Decomposing into subsets of cations and anions respective self terms as well as the prominent cross term can be extracted. This decomposition also enables a detailed peak assignment in dielectric spectra.

Synthesis and Crystal Structure of Dibromido{2-[(4-tert-butylmethylphenyl) iminomethyl]pyridine-κ2 N, N'}Zinc

NASA Astrophysics Data System (ADS)

Khalaj, M.; Ghazanfarpour-Darjani, M.; Seftejani, F. B.; Lalegani, A.

2017-12-01

The title compound [Zn( dip)Br2] was synthesized using the Schiff base bidentate ligand (E)-4- tert-butyl- N-(pyridine-2-ylmethylene)benzeneamine ( dip) and zinc(II) bromide salts. It has been characterized by elemental analysis, X-ray diffraction, and optical spectroscopy. The X-ray diffraction analysis demonstrates that in this structure, the zinc(II) ion is located on an inversion center and exhibits a ZnN2Br2 tetrahedral geometry. In this structure the dip ligand is coordinated with zinc(II) ion in a cyclic-bidentate fashion forming a five-membered metallocyclic ring. The compound crystallizes in the monoclinic sp. gr. P21/ m with a = 9.2700(13) Å, b = 7.6128(11) Å, c = 12.3880(17) Å, and β = 97.021(3)°.

Isotope effects and the temperature dependences of the hyperfine coupling constants of muoniated sec-butyl radicals in condensed phases.

PubMed

Fleming, Donald G; Bridges, Michael D; Arseneau, Donald J; Chen, Ya Kun; Wang, Yan Alexander

2011-04-07

Reported here is the first μSR study of the muon (A(μ)) and proton (A(p)) β-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(μ)′(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(μ)′(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(μ)′(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

[Mechanisms of (2-methyl-n-butyl) shikonin induced apoptosis of gastric cancer SGC-7901 cells].

PubMed

Wang, Hai-Bing; Ma, Xiao-Qiong

2012-06-01

This study is to investigate the effect of (2-methyl-n-butyl) shikonin (MBS) on inducing apoptosis of human gastric cancer cell line SGC-7901 and the role of ERK1/2 signal pathway in the apoptosis. MTT assay was used to detect SGC-7901 cell proliferation. DNA condensation was measured by DAPI stain. Cell apoptosis was analyzed by flow cytometry. Mitochondrial membrane potential (MMP) was analyzed by JC-1 staining. The protein expressions of Bcl-2, Bax, Survivin, cleaved caspase-9, cleaved caspase-3, cleaved PARP, p-ERK1/2, ERK1/2, p-JNK, JNK, p-p38 and p38 were detected by Western blotting. The results showed that MBS reduced the cell viability of SGC-7901 cells in a dose- and time-dependent manner. The IC50 at 24 h and 48 h for SGC-7901 cells was 10.113 and 4.196 micromolL(-1), respectively. After being treated with MBS, the typical nuclear condensation was observed in SGC-7901 cells by DAPI stain. Apoptosis in SGC-7901 cells was induced by MBS in a dose dependent manner. The protein expression of Bcl-2 was down-regulated, while the protein expressions of cleaved caspase-9, cleaved caspase-3, cleaved PARP, p-ERK1/2 and p-JNK were up-regulated after MBS treatment. U0126, a specific MAP kinase (MEK1/2) inhibitor, blocked the ERK1/2 activation by MBS. MMP was decreased by MBS treatment. It can be concluded that MBS could inhibit SGC-7901 cell proliferation and induce apoptosis. Mitochondrial apoptosis pathway, ERK1/2 signal pathway and JNK signal pathway might be involved in this process.

Composition changes in the cuticular surface lipids of the helophytes Phragmites australis and Juncus effusus as result of pollutant exposure.

PubMed

Macherius, André; Kuschk, Peter; Haertig, Claus; Moeder, Monika; Shtemenko, Natalia I; Bayona, Antonio Heredia; Guerrero, José A Heredia; Gey, Manfred

2011-06-01

Helophytes like rush and reed are increasingly used for phytoremediation of contaminated water. This study characterises the response of rush and reed plants to chemical stressors such as chlorobenzene, benzene and methyl-tert-butyl ether. The extractable wax layer of the cuticle was chosen for detailed investigations due to its multiple, particularly, protective functions for plants and its easy availability for analysis. The chemical composition of the cuticle wax layer of reed and rush was studied in dependence on chemical stress caused by contaminated water under wetland cultivation conditions. The lipid layer of leaves was extracted, derivatised and investigated by GC-MS using retention time locking and a plant-specific data base. In case of rush, a remarkable increase of the total lipid layer and a prolongation of the mean chain length resulted as response on a chlorobenzene exposure. The significant difference in the substance profiles of exposed plants and controls could be confirmed by multivariate data analysis. The lipid layer of reed was not changed significantly when the plants were exposed to water polluted with benzene and methyl-tert-butyl ether. However, scanning electron microscopic images of the exposed reed leaves indicated alterations in the crystal structure of their wax surface. The composition and morphology of cuticular waxes indicated the plants' response to chemical stress very sensitively thus, changes in the wax layer could be used as an indication for growing in a contaminated area.

The fate of MtBE during Fenton-like treatments through laboratory scale column tests.

PubMed

Piscitelli, Daniela; Zingaretti, Daniela; Verginelli, Iason; Gavasci, Renato; Baciocchi, Renato

2015-12-01

In Situ Chemical Oxidation (ISCO) based on the Fenton's process is a proven technology for the treatment of groundwater contaminated by organic compounds. Nevertheless, the application of this treatment process to methyl tert-butyl ether (MtBE) is questioned, as there are concerns about its capacity to achieve complete mineralization. Many existing studies have focused on water contaminated by MtBE and are thus not representative of in situ treatments since they do not consider the presence of soil. In this work, the effectiveness of a Fenton-like process for MtBE treatment was proven in soil column tests performed at operating conditions (i.e., oxidant and contaminant concentration and flow rates) resembling those typically used for in situ applications. No MtBE by-products were detected in any of the tested conditions, thus suggesting that the tert-butyl group of MtBE was completely degraded. A mass balance based on the CO2 produced was used as evidence that most of the MtBE removed was actually mineralized. Finally, the obtained results show that preconditioning of soil with a chelating agent (EDTA) significantly enhanced MtBE oxidation. Copyright © 2015 Elsevier B.V. All rights reserved.

The lightest organic radical cation for charge storage in redox flow batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jinhua; Pan, Baofei; Duan, Wentao

2016-08-25

Electrochemically reversible fluids of high energy density are promising materials for capturing the electrical energy generated from intermittent sources like solar and wind. To meet this technological challenge there is a need to understand the fundamental limits and interplay of electrochemical potential, stability and solubility in “lean” derivatives of redox-active molecules. Here we describe the process of molecular pruning, illustrated for 2,5-di-tert-butyl-1,4-bis(2-methoxyethoxy)benzene, a molecule known to produce a persistently stable, high-potential radical cation. By systematically shedding molecular fragments considered important for radical cation steric stabilization, we discovered a minimalistic structure that retains long-term stability in its oxidized form. Interestingly, wemore » find the tert-butyl groups are unnecessary; high stability of the radical cation and high solubility are both realized in derivatives having appropriately positioned arene methyl groups. These stability trends are rationalized by mechanistic considerations of the postulated decomposition pathways. We suggest that the molecular pruning approach will uncover lean redox active derivatives for electrochemical energy storage leading to materials with long-term stability and high intrinsic capacity.« less

Reaction of singlet-excited 2,3-diazabicyclo[2.2.2]oct-2-ene and tert-butoxyl radicals with aryl-substituted benzofuranones.

PubMed

Lundgren, Cecilia Vannesjö; Koner, Apurba L; Tinkl, Michael; Pischel, Uwe; Nau, Werner M

2006-03-03

5,7-Di-tert-butyl-3-aryl-3H-benzofuran-2-ones are lactones with potential antioxidant activity, owing to their abstractable benzylic C-H hydrogens. The fluorescence quenching of the azoalkane 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO), an established probe for the hydrogen-donor propensity of chain-breaking antioxidants, was investigated for 16 aryl-substituted benzofuranone derivatives [m,m-(CF3)2, p-CN, m-CN, p-CF3, p-COOCH3, m-CF3, p-Cl, p-F, H, m-CH3, p-CH3, m,p-(CH3)2, p-OCH3, o-CH3, o-CF3, o,m-(CH3)2]. Analysis of the rate data in terms of a linear free energy relationship yielded a reaction constant of rho = +0.35. This implies that n,pi*-excited DBO acts as nucleophilic species. In contrast, hydrogen abstraction of tert-butoxyl radicals from the benzofuranones was accelerated by electron-donating substituents (rho = -0.23), in conformity with the electrophilic character of oxygen-centered alkoxyl radicals. Possible implications for the optimization of the hydrogen-donor propensity of antioxidants through structural variation are discussed.

Biodegradation of Methyl Tertiary Butyl Ether (MTBE) by a Microbial Consortium in a Continuous Up-Flow Packed-Bed Biofilm Reactor: Kinetic Study, Metabolite Identification and Toxicity Bioassays

PubMed Central

Alfonso-Gordillo, Guadalupe; Flores-Ortiz, César Mateo; Morales-Barrera, Liliana

2016-01-01

This study investigated the aerobic biodegradation of methyl tertiary-butyl ether (MTBE) by a microbial consortium in a continuous up-flow packed-bed biofilm reactor using tezontle stone particles as a supporting material for the biofilm. Although MTBE is toxic for microbial communities, the microbial consortium used here was able to resist MTBE loading rates up to 128.3 mg L-1 h-1, with removal efficiencies of MTBE and chemical oxygen demand (COD) higher than 90%. A linear relationship was observed between the MTBE loading rate and the MTBE removal rate, as well as between the COD loading rate and the COD removal rate, within the interval of MTBE loading rates from 11.98 to 183.71 mg L-1 h-1. The metabolic intermediate tertiary butyl alcohol (TBA) was not detected in the effluent during all reactor runs, and the intermediate 2-hydroxy butyric acid (2-HIBA) was only detected at MTBE loading rates higher than 128.3 mg L-1 h-1. The results of toxicity bioassays with organisms from two different trophic levels revealed that the toxicity of the influent was significantly reduced after treatment in the packed-bed reactor. The packed-bed reactor system used in this study was highly effective for the continuous biodegradation of MTBE and is therefore a promising alternative for detoxifying MTBE-laden wastewater and groundwater. PMID:27907122

Biodegradation of Methyl Tertiary Butyl Ether (MTBE) by a Microbial Consortium in a Continuous Up-Flow Packed-Bed Biofilm Reactor: Kinetic Study, Metabolite Identification and Toxicity Bioassays.

PubMed

Alfonso-Gordillo, Guadalupe; Flores-Ortiz, César Mateo; Morales-Barrera, Liliana; Cristiani-Urbina, Eliseo

2016-01-01

This study investigated the aerobic biodegradation of methyl tertiary-butyl ether (MTBE) by a microbial consortium in a continuous up-flow packed-bed biofilm reactor using tezontle stone particles as a supporting material for the biofilm. Although MTBE is toxic for microbial communities, the microbial consortium used here was able to resist MTBE loading rates up to 128.3 mg L-1 h-1, with removal efficiencies of MTBE and chemical oxygen demand (COD) higher than 90%. A linear relationship was observed between the MTBE loading rate and the MTBE removal rate, as well as between the COD loading rate and the COD removal rate, within the interval of MTBE loading rates from 11.98 to 183.71 mg L-1 h-1. The metabolic intermediate tertiary butyl alcohol (TBA) was not detected in the effluent during all reactor runs, and the intermediate 2-hydroxy butyric acid (2-HIBA) was only detected at MTBE loading rates higher than 128.3 mg L-1 h-1. The results of toxicity bioassays with organisms from two different trophic levels revealed that the toxicity of the influent was significantly reduced after treatment in the packed-bed reactor. The packed-bed reactor system used in this study was highly effective for the continuous biodegradation of MTBE and is therefore a promising alternative for detoxifying MTBE-laden wastewater and groundwater.

Bis(1,3-di-tert-butylimidazolin-2-iminato) titanium complexes as effective catalysts for the monodisperse polymerization of propylene.

PubMed

Sharma, Manab; Yameen, Haneen Simaan; Tumanskii, Boris; Filimon, Sabina-Alexandra; Tamm, Matthias; Eisen, Moris S

2012-10-17

The use of bis(1,3-di-tert-butylimidazolin-2-iminato) titanium dichloride (1) and dimethyl (2) complexes in the polymerization of propylene is presented. The complexes were activated using different amounts of methylalumoxane (MAO), giving in each case a very active catalytic mixture and producing polymers with a narrow molecular weight distribution (polydispersity = 1.10). The use of the cocatalyst triphenylcarbenium (trityl) tetra(pentafluorophenyl)borate totally inhibits the reaction, producing the corresponding bis(1,3-di-tert-butylimidazolin-2-iminato) titanium(III) methyl complex, the trityl radical ((•)CPh(3)), the anionic MeB(C(6)F(5))(4)(-), B(C(6)F(5))(3), and the bis(1,3-di-tert-butylimidazolin-2-iminato) titanium(IV) dimethyl·B(C(6)F(5))(3) complex. The use of a combination of physical methods such as NMR, ESR-C(60), and MALDI-TOF analyses enabled us to propose a plausible mechanism for the polymerization of propylene, presenting that the polymerization is mainly carried out in a living fashion. In addition, we present a slow equilibrium toward a small amount of a dormant species responsible for 2,1-misinsertions and chain transfer processes.

Gold(I) Complexes of Ferrocenyl Polyphosphines: Aurophilic Gold Chloride Formation and Phosphine-Concerted Shuttling of a Dinuclear [ClAu···AuCl] Fragment.

PubMed

Rampazzi, Vincent; Roger, Julien; Amardeil, Régine; Penouilh, Marie-José; Richard, Philippe; Fleurat-Lessard, Paul; Hierso, Jean-Cyrille

2016-11-07

A smart steric control of the metallocene backbone in bis- and poly(phosphino)ferrocene ligands favors intramolecular aurophilic interactions between [AuCl] fragments in polynuclear gold(I) complexes. We synthesized and characterized by multinuclear NMR and X-ray diffraction analysis mono-, di-, and polynuclear gold complexes of constrained ferrocenyl diphosphines, which bear either bulky tert-butyl groups or more flexible siloxane substituents at the cyclopentadienyl rings. The complexes meso-1,1'-bis(diphenylphosphino)-3,3'-di-tert-butylferrocene (4-m), rac-1,1'-bis[bis(5-methyl-2-furyl)phosphino]-3,3'-di-tert-butylferrocene (5-r), and rac-1,1'-bis(diphenylphosphino)-3,3'-bis[(tri-iso-propylsilyl)oxy]ferrocene (6-r) were used to form dinuclear gold complexes. Coordination of tert-butylated ferrocenyl phosphines generated aurophilic interactions in the corresponding dinuclear gold complexes, contrary to gold(I) complexes reported with 1,1'-bis(diphenylphosphino)ferrocene. The structurally related tetraphosphine 1,1',2,2'-tetrakis(diphenylphosphino)-4,4'-di-tert-butylferrocene (11) also gave access to mononuclear, dinuclear, and the original trinuclear gold chloride aurophilic complexes in which 14e - to 16e - gold centers coexist. In such complexes, nonbonded ("through-space") 31 P- 31 P' nuclear spin couplings were evidenced by high-resolution NMR. In these interactions nuclear spin information is transferred between the lone-pair electron of an uncoordinated phosphorus P and a phosphorus P' that is involved in a σ covalent bond Au-P'. The dinuclear aurophilic complex displayed a concerted shuttling of its [ClAu···AuCl] fragment between the four phosphorus donors of the tetraphosphine ligand. Thus, an aurophilic Au···Au bond, which is assumed to be a weak energy interaction, can be conserved within a dynamic shuttling process at high temperature involving an intramolecular coordination-decoordination process of digold(I) at phosphorus atoms.

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

PubMed Central

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

1999-01-01

We studied customer exposure during refueling by collecting air samples from customers' breathing zone. The measurements were carried out during 4 days in summer 1996 at two Finnish self-service gasoline stations with "stage I" vapor recovery systems. The 95-RON (research octane number) gasoline contained approximately 2.7% methyl tert-butyl ether (MTBE), approximately 8.5% tert-amyl methyl ether (TAME), approximately 3.2% C6 alkyl methyl ethers (C6 AMEs), and 0.75% benzene. The individual exposure concentrations showed a wide log-normal distribution, with low exposures being the most frequent. In over 90% of the samples, the concentration of MTBE was higher (range <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

P. berghei Telomerase Subunit TERT is Essential for Parasite Survival

PubMed Central

Religa, Agnieszka A.; Ramesar, Jai; Janse, Chris J.; Scherf, Artur; Waters, Andrew P.

2014-01-01

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

Methanex considers methanol, MTBE in Qatar

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

CW has learned that Methanex Corp. is considering entering one of two methanol and methyl tert-butyl ether (MTBE) projects in Qatar. Executive v.p. Michael Wilson says that part of the company`s New Zealand plant could be moved to a site in Qatar, which would lower capital costs for the possible project by $75 million-$100 million. Both Qatar General Petroleum Corp. and Qatar Fuel Additives are developing methanol and MTBE projects at Umm Said, Qatar. Methanex says its goal is to ensure low-cost feedstocks.

Health Risk Assessment for Inhalation Exposure to Methyl Tertiary Butyl Ether at Petrol Stations in Southern China

PubMed Central

Hu, Dalin; Yang, Jianping; Liu, Yungang; Zhang, Wenjuan; Peng, Xiaowu; Wei, Qinzhi; Yuan, Jianhui; Zhu, Zhiliang

2016-01-01

Methyl tertiary butyl ether (MTBE), a well known gasoline additive, is used in China nationwide to enhance the octane number of gasoline and reduce harmful exhaust emissions, yet  little is known regarding the potential health risk associated with occupational exposure to MTBE in petrol stations. In this study, 97 petrol station attendants (PSAs) in southern China were recruited for an assessment of the health risk associated with inhalation exposure to MTBE. The personal exposure levels of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS, and the demographic characteristics of the PSAs were investigated. Cancer and non-cancer risks were calculated with the methods recommended by the United States Environmental Protection Agency. The results showed that the exposure levels of MTBE in operating workers were much higher than among support staff (p < 0.01) and both were lower than 50 ppm (an occupational threshold limit value). The calculated cancer risks (CRs) at the investigated petrol stations was 0.170 to 0.240 per 106 for operating workers, and 0.026 to 0.049 per 106 for support staff, which are below the typical target range for risk management of 1 × 10−6 to 1 × 10−4; The hazard quotients (HQs) for all subjects were <1. In conclusion, our study indicates that the MTBE exposure of PSAs in southern China is in a low range which does not seem to be a significant health risk. PMID:26861375

Health Risk Assessment for Inhalation Exposure to Methyl Tertiary Butyl Ether at Petrol Stations in Southern China.

PubMed

Hu, Dalin; Yang, Jianping; Liu, Yungang; Zhang, Wenjuan; Peng, Xiaowu; Wei, Qinzhi; Yuan, Jianhui; Zhu, Zhiliang

2016-02-06

Methyl tertiary butyl ether (MTBE), a well known gasoline additive, is used in China nationwide to enhance the octane number of gasoline and reduce harmful exhaust emissions, yet little is known regarding the potential health risk associated with occupational exposure to MTBE in petrol stations. In this study, 97 petrol station attendants (PSAs) in southern China were recruited for an assessment of the health risk associated with inhalation exposure to MTBE. The personal exposure levels of MTBE were analyzed by Head Space Solid Phase Microextraction GC/MS, and the demographic characteristics of the PSAs were investigated. Cancer and non-cancer risks were calculated with the methods recommended by the United States Environmental Protection Agency. The results showed that the exposure levels of MTBE in operating workers were much higher than among support staff (p < 0.01) and both were lower than 50 ppm (an occupational threshold limit value). The calculated cancer risks (CRs) at the investigated petrol stations was 0.170 to 0.240 per 10⁶ for operating workers, and 0.026 to 0.049 per 10⁶ for support staff, which are below the typical target range for risk management of 1 × 10(-6) to 1 × 10(-4); The hazard quotients (HQs) for all subjects were <1. In conclusion, our study indicates that the MTBE exposure of PSAs in southern China is in a low range which does not seem to be a significant health risk.

Identification and characterization of N-tert-butoxycarbonyl-MDMA: a new MDMA precursor.

PubMed

Collins, Michael; Donnelly, Christopher; Cameron, Shane; Tahtouh, Mark; Salouros, Helen

2017-03-01

In September 2015, 80 litres of a viscous, light-red liquid, described as hair product, was seized by the Australian Border Force (ABF). Initial testing by ABF indicated that the liquid was the 3,4-methylenedioxymethamphetamine (MDMA) precursor chemical safrole and custody of the material was transferred to the Australian Federal Police (AFP) who coordinated all subsequent investigations. Initial gas chromatography-mass spectrometry (GC-MS) analysis by the AFP indicated that the material was not safrole and samples of the liquid were transferred to the National Measurement Institute Australia (NMIA) for identification. Using a combination of nuclear magnetic resonance spectroscopy (NMR), GC-MS, infrared spectroscopy, and synthesis, the unknown substance was identified as N-tert.-butoxycarbonyl-MDMA (t-BOC-MDMA). The substance was also converted in high yield to MDMA (aqueous HCl, 80 °C, 30 min). The possibility that the t-BOC-MDMA may act as a pro-drug following ingestion was explored by exposure to simulated gastric juice (pH 1.5) and monitored by NMR (37 °C) at various intervals. The majority of t-BOC-MDMA was converted to MDMA after 305 min, which suggested that this derivatized form might serve as a pro-drug in vivo. An investigation into the chemistry of potential pro-drugs showed that t-BOC derivatives of methamphetamine, pseudoephedrine and 4-methylmethcahtinone (mephedrone) could also be prepared using di-tert.-butyl dicarbonate. The appearance of t-BOC-derivatives on the drug market requires further monitoring. © 2016 Commonwealth of Australia. Drug Testing and Analysis © 2016 John Wiley & Sons, Ltd. © 2016 Commonwealth of Australia. Drug Testing and Analysis © 2016 John Wiley & Sons, Ltd.

TERT promoter mutation in adult granulosa cell tumor of the ovary.

PubMed

Pilsworth, Jessica A; Cochrane, Dawn R; Xia, Zhouchunyang; Aubert, Geraldine; Färkkilä, Anniina E M; Horlings, Hugo M; Yanagida, Satoshi; Yang, Winnie; Lim, Jamie L P; Wang, Yi Kan; Bashashati, Ali; Keul, Jacqueline; Wong, Adele; Norris, Kevin; Brucker, Sara Y; Taran, Florin-Andrei; Krämer, Bernhard; Staebler, Annette; Oliva, Esther; Shah, Sohrab P; Kommoss, Stefan; Kommoss, Friedrich; Gilks, C Blake; Baird, Duncan M; Huntsman, David G

2018-02-15

The telomerase reverse transcriptase (TERT) gene is highly expressed in stem cells and silenced upon differentiation. Cancer cells can attain immortality by activating TERT to maintain telomere length and telomerase activity, which is a crucial step of tumorigenesis. Two somatic mutations in the TERT promoter (C228T; C250T) have been identified as gain-of-function mutations that promote transcriptional activation of TERT in multiple cancers, such as melanoma and glioblastoma. A recent study investigating TERT promoter mutations in ovarian carcinomas found C228T and C250T mutations in 15.9% of clear cell carcinomas. However, it is unknown whether these mutations are frequent in other ovarian cancer subtypes, in particular, sex cord-stromal tumors including adult granulosa cell tumors. We performed whole-genome sequencing on ten adult granulosa cell tumors with matched normal blood and identified a TERT C228T promoter mutation in 50% of tumors. We found that adult granulosa cell tumors with mutated TERT promoter have increased expression of TERT mRNA and exhibited significantly longer telomeres compared to those with wild-type TERT promoter. Extension cohort analysis using allelic discrimination revealed the TERT C228T mutation in 51 of 229 primary adult granulosa cell tumors (22%), 24 of 58 recurrent adult granulosa cell tumors (41%), and 1 of 22 other sex cord-stromal tumors (5%). There was a significant difference in overall survival between patients with TERT C228T promoter mutation in the primary tumors and those without it (p = 0.00253, log-rank test). In seven adult granulosa cell tumors, we found the TERT C228T mutation present in recurrent tumors and absent in the corresponding primary tumor. Our data suggest that TERT C228T promoter mutations may have an important role in progression of adult granulosa cell tumors.

μ-Carbonato-κ4 O,O′:O′,O′′-bis­{[2′-(di-tert-butyl­phosphan­yl)biphenyl-2-yl-κ2 P,C 1]palladium(II)} dichloro­methane monosolvate

PubMed Central

Muller, Alfred; Holzapfel, Cedric W.

2012-01-01

The title compound, [(μ2-CO3){Pd(P(t-C4H9)2(C12H8)}2]·CH2Cl2, the first CO3-bridged palladium dimer complex reported to date, was obtained while preparing the Pd0 complex with (2-biphen­yl)P(tBu)2. In the crystal, each palladium dimer is accompanied by a dichloro­methane solvent mol­ecule. Coordination of the carbonate and chelated phosphane ligands gives distorted square-planar environments at the Pd atoms. Important geometrical parameters include Pd—P(av.) = 2.2135 (4) Å, Pd—C(av.) = 1.9648 (16) Å and P—Pd—C = 84.05 (5) and 87.98 (5)°, and O—Pd—O′ = 60.56 (4) and 61.13 (4)°. Bonding with the carbonate O atoms shows values of 2.1616 (11) and 2.1452 (11) Å for the Pd—O—Pd bridge, whereas other Pd—O distances are slightly longer at 2.2136 (11) and 2.1946 (11) Å. One of the tert-butyl groups is disordered over two set of sites with an occupancy ratio of 0.723 (6):0.277 (6). Weak C—H⋯O interactions are observed propagating the molecules along the [100] direction. PMID:23468771

Peripheral substitution of pheophorbides and bacteriopheophorbides to promote inclusion into inert carrier systems for PDT

NASA Astrophysics Data System (ADS)

Roehrs, Susanne; Ruebner-Heuermann, Anja; Hartwich, G.; Scheer, H.; Moser, Joerg G.

1996-01-01

Pheophorbide a ethyl ester, pyropheophorbide a ethyl ester, and bacteriopheophorbide ethyl ester were substituted in 31-position with tert.butyl phenoxy or tert.butyl benzoic acid ester groups resp. in order to enhance affinity to (beta) -cyclodextrin dimers which form inclusion complexes with these photosensitizing drugs. This is a first step to construct inert transport complexes in order to photosensitize specifically cancer cells.

Frequency of TERT promoter mutations in primary tumors of the liver.

PubMed

Quaas, Alexander; Oldopp, Theresa; Tharun, Lars; Klingenfeld, Catina; Krech, Till; Sauter, Guido; Grob, Tobias J

2014-12-01

Transcriptional regulation of the TERT gene is a major cause of the cancer-specific increase in telomerase activity. Recently, frequent somatic mutations in the TERT promoter have been described in several tumor entities such as melanoma, glioblastoma, bladder cancer, and hepatocellular carcinoma. By generating a putative consensus binding site for ETS transcription factors within the TERT promoter, these mutations are predicted to increase promoter activity and TERT transcription. In order to improve the understanding of the role of TERT promoter mutation in liver tumorigenesis, the mutational status of the TERT promoter was analyzed in 78 hepatocellular carcinomas, 15 hepatocellular adenomas, and 52 intrahepatic cholangiocarciomas. The promoter region of TERT was screened for the two hotspot mutations using PCR and restriction fragment length analysis, utilizing the introduction of novel restriction sites by the somatic mutations. TERT promoter mutation was found in 37 of 78 hepatocellular carcinomas (47 %) and was restricted to the -124C>T mutation. Frequency of mutations was associated with grade of differentiation ranging from 39 % in well-differentiated tumors to 73 % in high-grade hepatocellular carcinomas. TERT promoter mutations were not found in 15 hepatocellular adenomas and 52 intrahepatic cholangiocarcinomas. These data show that TERT promoter mutation is the most frequent genetic alteration in hepatocellular carcinoma known at this time. The striking predominance of the -124C>T mutation compared with other tumor entities suggest a biological difference of the two hotspot mutations. Analysis of TERT promoter mutation might become a diagnostic tool distinguishing hepatocellular adenoma from well-differentiated hepatocellular carcinoma.

Facile Synthesis of Thick Films of Poly(methyl methacrylate), Poly(styrene), and Poly(vinyl pyridine) from Au Surfaces

PubMed Central

Saha, Sampa

2011-01-01

Atom transfer radical polymerization (ATRP) is commonly used to grow polymer brushes from Au surfaces, but the resulting film thicknesses are usually significantly less than with ATRP from SiO2 substrates. On Au, growth of poly(methyl methacrylate) (PMMA) blocks from poly(tert-butyl acrylate) brushes occurs more rapidly than growth of PMMA from initiator monolayers, suggesting that the disparity between growth rates from Au and SiO2 stems from the Au surface. Radical quenching by electron transfer from Au is probably not the termination mechanism because polymerization from thin, cross-linked initiators gives film thicknesses that are essentially the same as the thicknesses of films grown from SiO2 under the same polymerization conditions. However, this result is consistent with termination through desorption of thiols from non-cross-linked films, and reaction of these thiols with growing polymer chains. The enhanced stability of cross-linked initiators allows ATRP at temperatures up to ~100 °C and enables the growth of thick films of PMMA (350 nm), polystyrene (120 nm) and poly(vinyl pyridine) (200 nm) from Au surfaces in 1 hour. At temperatures >100 °C, the polymer brush layers delaminate as large area films. PMID:21728374

Theoretical and Kinetic Tools for Selecting Effective Antioxidants: Application to the Protection of Omega-3 Oils with Natural and Synthetic Phenols

PubMed Central

Guitard, Romain; Nardello-Rataj, Véronique; Aubry, Jean-Marie

2016-01-01

Radical-scavenging antioxidants play crucial roles in the protection of unsaturated oils against autoxidation and, especially, edible oils rich in omega-3 because of their high sensitivity to oxygen. Two complementary tools are employed to select, among a large set of natural and synthetic phenols, the most promising antioxidants. On the one hand, density functional theory (DFT) calculations provide bond dissociation enthalpies (BDEs) of 70 natural (i.e., tocopherols, hydroxybenzoic and cinnamic acids, flavonoids, stilbenes, lignans, and coumarins) and synthetic (i.e., 2,6-di-tert-butyl-4-methylphenol (BHT), 3-tert-butyl-4-hydroxyanisol (BHA), and tert-butylhydroquinone (TBHQ)) phenols. These BDEs are discussed on the basis of structure–activity relationships with regard to their potential antioxidant activities. On the other hand, the kinetic rate constants and number of hydrogen atoms released per phenol molecule are measured by monitoring the reaction of phenols with 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical. The comparison of the results obtained with these two complementary methods allows highlighting the most promising antioxidants. Finally, the antioxidant effectiveness of the best candidates is assessed by following the absorption of oxygen by methyl esters of linseed oil containing 0.5 mmol L−1 of antioxidant and warmed at 90 °C under oxygen atmosphere. Under these conditions, some natural phenols namely epigallocatechin gallate, myricetin, rosmarinic and carnosic acids were found to be more effective antioxidants than α-tocopherol. PMID:27483242

Theoretical and Kinetic Tools for Selecting Effective Antioxidants: Application to the Protection of Omega-3 Oils with Natural and Synthetic Phenols.

PubMed

Guitard, Romain; Nardello-Rataj, Véronique; Aubry, Jean-Marie

2016-07-29

Radical-scavenging antioxidants play crucial roles in the protection of unsaturated oils against autoxidation and, especially, edible oils rich in omega-3 because of their high sensitivity to oxygen. Two complementary tools are employed to select, among a large set of natural and synthetic phenols, the most promising antioxidants. On the one hand, density functional theory (DFT) calculations provide bond dissociation enthalpies (BDEs) of 70 natural (i.e., tocopherols, hydroxybenzoic and cinnamic acids, flavonoids, stilbenes, lignans, and coumarins) and synthetic (i.e., 2,6-di-tert-butyl-4-methylphenol (BHT), 3-tert-butyl-4-hydroxyanisol (BHA), and tert-butylhydroquinone (TBHQ)) phenols. These BDEs are discussed on the basis of structure-activity relationships with regard to their potential antioxidant activities. On the other hand, the kinetic rate constants and number of hydrogen atoms released per phenol molecule are measured by monitoring the reaction of phenols with 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) radical. The comparison of the results obtained with these two complementary methods allows highlighting the most promising antioxidants. Finally, the antioxidant effectiveness of the best candidates is assessed by following the absorption of oxygen by methyl esters of linseed oil containing 0.5 mmol L(-1) of antioxidant and warmed at 90 °C under oxygen atmosphere. Under these conditions, some natural phenols namely epigallocatechin gallate, myricetin, rosmarinic and carnosic acids were found to be more effective antioxidants than α-tocopherol.

Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties.

PubMed

Bwambok, David K; Marwani, Hadi M; Fernand, Vivian E; Fakayode, Sayo O; Lowry, Mark; Negulescu, Ioan; Strongin, Robert M; Warner, Isiah M

2008-02-01

We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L- and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L- and D-alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L- and D-alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263 degrees C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state (19)F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L- and D-alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion.

2-tert-Butyl-5-(2-pyridyl)-2H-tetrazole as a chelating ligand in the direct synthesis of novel Cu(II) and heterobimetallic Cu(II)/Mn(II) complexes.

PubMed

Mosalkova, Anastasiya P; Voitekhovich, Sergei V; Lyakhov, Alexander S; Ivashkevich, Ludmila S; Lach, Jochen; Kersting, Berthold; Gaponik, Pavel N; Ivashkevich, Oleg A

2013-02-28

For the first time, a representative of the 2,5-disubstituted tetrazoles, namely, 2-tert-butyl-5-(2-pyridyl)-2H-tetrazole (L), has been found to participate in oxidative dissolution of copper powder in homometalic systems Cu0–L–NH4X–DMSO (X = Cl, SCN, ClO4) and heterobimetallic ones Cu0–Mn(OAc)2–L–NH4OAc–Solv (Solv = DMSO, DMF), providing the formation of molecular homometallic complexes [CuL2Cl2] (1), [CuL2(SCN)2] (2), and [CuL2(H2O)](ClO4)2 (3), heterobimetallic complex [Cu2MnL2(OAc)6] (4) from DMF solution and its mixture with complex [Cu2MnL2(OAc)6]·2DMSO (5) from DMSO solution. Free ligand L and complexes 1–4 were characterized by elemental analysis, IR spectroscopy, thermal and X-ray single crystal analyses, whereas complex 5 was characterized by X-ray analysis only. Compounds 1–3 are mononuclear complexes, with chelating coordination mode of L via the tetrazole ring N4 and pyridine ring N7 atoms. Heterobimetallic complexes 4 and 5 possess trinuclear structures, with a linear Cu–Mn–Cu arrangement of the metal atoms, linked by the acetate anions; each copper(II) atom is decorated by a chelating unit of L via the tetrazole ring N1 and pyridine ring N7 atoms in complex 4, and via the N4, N7 atoms in complex 5. Temperature-dependent magnetic susceptibility measurements of complex 4 revealed a weak antiferromagnetic coupling between the paramagnetic copper(II) and manganese(II) ions (J = −2.5 cm(−1), g(Cu) = 2.25 and g(Mn) = 2.01), with magnetic exchange through the acetato bridges.

The associations of TERT-CLPTM1L variants and TERT mRNA expression with the prognosis of early stage non-small cell lung cancer.

PubMed

Chen, Z; Wang, J; Bai, Y; Wang, S; Yin, X; Xiang, J; Li, X; He, M; Zhang, X; Wu, T; Xu, P; Guo, H

2017-01-01

Lung cancer is the leading cause of cancer-related death in the world. Several genome-wide association studies (GWAS) have identified TERT-CLPTM1L as plausible causative locus for lung cancer development. This study aimed to investigate the associations of genetic variations in TERT-CLPTM1L and the expression level of TERT with the survival of early stage non-small cell lung cancer (NSCLC) patients. We selected three single-nucleotide polymorphisms of TERT-CLPTM1L (rs2853669, rs2736108 and rs31490) and genotyped in 140 early stage NSCLC patients by TaqMan assay. Associations between these variations and survival outcome of early stage NSCLC patients were further investigated. We also used TCGA data to evaluate the associations of TERT messenger RNA (mRNA) expression and survival outcome of early stage NSCLC patients. Survival analysis showed that, compared with early NSCLC patients carrying TERT rs2853669 TT+TC genotypes, patients with rs2853669 CC genotype had significantly longer median survival time (MST=102.2 vs 52.4 months; log-rank P=0.028) and lower death risk [hazard ratio (HR) with 95% confidence interval (CI))=0.38(0.17-0.82), P=0.014]. Early NSCLC patients carrying TERT rs2736108 AA genotype had significantly shorter MST (MST=29.0 vs 63.3 months; log-rank P=0.020) and increased death risk [HR (95% CI)=2.22(1.01-5.80), P=0.046], when compared with patients carrying rs2736108 GG genotypes. TCGA data revealed that early NSCLC patients with higher expression level of TERT mRNA in lung tumor tissues had a longer MST and decreased death risk than those with low expression level of TERT mRNA [MST=54.4 vs 49.0 months; log-rank P=0.041; adjusted HR (95% CI)=0.68(0.50-0.94)]. These findings may add potential evidence to understand the prognostic value of TERT and provide a new prospect of individualized prevention and treatment for early stage NSCLC.

``Living polymers'' in organic solvents : stress relaxation in bicopper tetracarboxylate/tert-butyl cyclohexane solutions

NASA Astrophysics Data System (ADS)

Terech, P.; Maldivi, P.; Dammer, C.

1994-10-01

Viscoelastic solutions of a bicopper tetracarboxylate complex in tert-butylcyclohexane have been studied by dynamic rheology in a wide range of concentrations (0.5-1.5 % volume fraction). The zero shear viscosity, the elastic modulus, the terminal stress relaxation time and the height of the high-frequency dip, in a Cole-Cole representation of the complex elastic modulus, follow scaling laws. The related exponents are discussed in the context of the physics of “living polymers” : a term used to describe worm-like species undergoing scission/recombination reactions competing mainly with the reptation motions of the chains. The current system, made up of molecular threads (17.5 Å diameter) of Cu2(O2C-CH(C2H5)C4H9)4 in the apolar solvent, is representative of a “living polymer” where, instead of mechanisms involving transient star polymeric crosslinks, a reversible scission mechanism prevails. The dynamics in the high-frequency range evolves from a regime where reptation is the dominant relaxation mechanism to a cross-over regime where “breathing” fluctuations and Rouse motions become important. Large modifications of the stress relaxation function occur for more concentrated systems. The binary system is the first example of a “living polymer” in an organic solvent and exhibits elastic moduli (G ≈ ca. 120 Pa à φ = 1 %) which are at least 20 times larger than those found for the aqueous “living polymer” systems. Les solutions viscoélastiques d'un tétracarboxylate binucléaire de cuivre dans le tert-butylcyclohexane sont étudiées par rhéologie en mode dynamique dans une gamme étendue de concentrations (0,5 %-15,5 %). La viscosité à gradient nul, le module élastique, le temps terminal de relaxation et la hauteur du puits à haute fréquence, dans une représentation Cole-Cole du module élastique complexe, suivent des lois d'échelles. Les exposants correspondants sont discutés dans le contexte de la physique des “polymères vivants

Experimental and theoretical studies on the OH-initiated degradation of tert-butylamine

NASA Astrophysics Data System (ADS)

Tan, Wen; D'Anna, Barbara; Eichler, Philipp; Mikoviny, Tomas; Müller, Markus; Jørgen Nielsen, Claus; Wisthaler, Armin; Zhu, Liang

2017-04-01

Amine-based carbon dioxide (CO2) capture facilities release small amounts of amines into the atmosphere. Once airborne, the amines are photochemically transformed into imines, amides, nitrosamines, nitramines and other breakdown products. As some of these products pose a risk to human health and the environment, we have elucidated photochemical decomposition mechanisms of various types of amines in previous work. Our studies did, however, not include amines in which the primary amino group is attached to a tertiary carbon atom, with 2-amino-2-methyl-1-propanol (AMP, (CH3)2C(NH2)CH2OH) being a prominent candidate used in CO2 capture. Our initial step in elucidating the degradation mechanism of AMP was to study tert-butylamine (tBA, (CH3)3C(NH2)), which is a similar molecule but lacks the OH group. OH-initiated degradation of tBA was studied in chamber experiments at the European Photoreactor (EUPHORE) in Valencia (Spain) using state-of-the-art analytical instrumentation. A Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) was used to measure tBA and tBA degradation products in the gas phase. Propan-2-imine (PI, (CH3)2C(=NH)) and tert-butylnitramine (tBNA, (CH3)3C(NHNO2)) were observed as the two major gas-phase products. An Aerosol Mass Spectrometer (AMS) made quantitative measurements of tert-butylaminium nitrate in the particle phase. A PTR-ToF-MS instrument equipped with a "chemical analysis of aerosol online" (CHARON) inlet detected the two major tBA degradation products (PI, tBNA) in the particle phase. Experimental work was supplemented by quantum chemistry calculations. We will present measured product yields and a complete degradation scheme of tBA. This work was supported by the Norwegian Research Council CLIMIT program under contract 244055.

Soluble, High Molecular Weight Polysilsesquioxanes with Carboxylate Functionalities

DOE Office of Scientific and Technical Information (OSTI.GOV)

RAHIMIAN,KAMYAR; LOY,DOUGLAS A.; WHEELER,DAVID R.

2000-07-14

Trialkoxysilyl-containing monomers of the type (RO){sub 3}Si(CH{sub 2}){sub 3}C(O)OtBu (R = Me, Et) were prepared by hydrosilation of the corresponding vinylic tert-butyl esters CH{sub 3}CHCH{sub 2}C(O)OtBu. Acid- or base-catalyzed polymerization of the monomers leads to very high molecular weight polymers with relatively narrow polydispersities. The polymerization results in complete condensation of the alkoxy groups while the tert-butyl ester functionality remains fully intact. Partial or full deprotection of the tert-butyl group can easily be achieved to yield the corresponding carboxylic acid polymers. The ester and carboxylic acid functionalities of these new materials allow for their potential use in a variety ofmore » applications such as scavenging of heavy metals.« less

Rearrangement of Upstream Sequences of the hTERT Gene During Cellular Immortalization

PubMed Central

Zhao, Yuanjun; Wang, Shuwen; Popova, Evgenya Y.; Grigoryev, Sergei A.; Zhu, Jiyue

2010-01-01

Telomerase expression, resulting from transcriptional activation of the hTERT gene, allows cells to acquire indefinite proliferative potential during cellular immortalization and tumorigenesis. However, mechanisms of hTERT gene activation in many immortal cell lines and cancer cells are poorly understood. Here, we report our studies on hTERT activation using genetically related pairs of telomerase-negative (Tel−) and -positive (Tel+) fibroblast lines. First, whereas transiently transfected plasmid reporters did not recapitulate the endogenous hTERT promoter, the promoter in chromosomally integrated bacterial artificial chromosome (BAC) reporters was activated in a subset of Tel+ cells, indicating that activation of the hTERT promoter required native chromatin context and/or distal regulatory elements. Second, the hTERT gene, located near the telomere of chromosome 5p, was translocated in all three Tel+ cell lines but not in their parental pre-crisis cells and Tel− immortal siblings. The breakage points were mapped to regions upstream of the hTERT promoter, indicating that the hTERT gene was the target of these chromosomal rearrangements. In two Tel+ cell lines, translocation of the endogenous hTERT gene appeared to be the major mechanism of its activation as the activity of hTERT promoter in many chromosomally integrated BAC reporters, with intact upstream and downstream neighboring loci, remained relatively low. Therefore, our results suggest that rearrangement of upstream sequences is an important new mechanism of hTERT promoter activation during cellular immortalization. The chromosomal rearrangements likely occurred during cellular crisis and facilitated by telomere dysfunction. Such translocations allowed the hTERT promoter to escape from the native condensed chromatin environment. PMID:19672873

Investigation of steric influences on hydrogen-bonding motifs in cyclic ureas by using X-ray, neutron, and computational methods.

PubMed

McCormick, Laura J; McDonnell-Worth, Ciaran; Platts, James A; Edwards, Alison J; Turner, David R

2013-11-01

A series of urea-derived heterocycles, 5N-substituted hexahydro-1,3,5-triazin-2-ones, has been prepared and their structures have been determined for the first time. This family of compounds only differ in their substituent at the 5-position (which is derived from the corresponding primary amine), that is, methyl (1), ethyl (2), isopropyl (3), tert-butyl (4), benzyl (5), N,N-(diethyl)ethylamine (6), and 2-hydroxyethyl (7). The common heterocyclic core of these molecules is a cyclic urea, which has the potential to form a hydrogen-bonding tape motif that consists of self-associative R₂²(8) dimers. The results from X-ray crystallography and, where possible, Laue neutron crystallography show that the hydrogen-bonding motifs that are observed and the planarity of the hydrogen bonds appear to depend on the steric hindrance at the α-carbon atom of the N substituent. With the less-hindered substituents, methyl and ethyl, the anticipated tape motif is observed. When additional methyl groups are added onto the α-carbon atom, as in the isopropyl and tert-butyl derivatives, a different 2D hydrogen-bonding motif is observed. Despite the bulkiness of the substituents, the benzyl and N,N-(diethyl)ethylamine derivatives have methylene units at the α-carbon atom and, therefore, display the tape motif. The introduction of a competing hydrogen-bond donor/acceptor in the 2-hydroxyethyl derivative disrupts the tape motif, with a hydroxy group interrupting the N-H···O=C interactions. The geometry around the hydrogen-bearing nitrogen atoms, whether planar or non-planar, has been confirmed for compounds 2 and 5 by using Laue neutron diffraction and rationalized by using computational methods, thus demonstrating that distortion of O-C-N-H torsion angles occurs to maintain almost-linear hydrogen-bonding interactions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Frequent somatic TERT promoter mutations and CTNNB1 mutations in hepatocellular carcinoma.

PubMed

Lee, Seung Eun; Chang, Seong-Hwan; Kim, Wook Youn; Lim, So Dug; Kim, Wan Seop; Hwang, Tea Sook; Han, Hye Seung

2016-10-25

Genetic alterations of TERT and CTNNB1 have been documented in hepatocellular carcinoma. TERT promoter mutations are the earliest genetic events in the multistep process of hepatocarcinogenesis related to cirrhosis. However, analyses of TERT promoter and CTNNB1 mutations in hepatocellular carcinoma tumor samples have not been performed in the Korean population, where hepatitis B virus-related hepatocellular carcinoma is prevalent. In order to identify the role of TERT promoter and CTNNB1 mutations in the hepatocarcinogenesis and pathogenesis of recurrent hepatocellular carcinoma, we performed the sequence analyses in 140 hepatocellular nodules (including 107 hepatocellular carcinomas), and 8 pairs of matched primary and relapsed hepatocellular carcinomas. TERT promoter and CTNNB1 mutations were only observed in hepatocellular carcinomas but not in precursor lesions. Of 109 patients with hepatocellular carcinoma, 41 (39.0%) and 15 (14.6%) harbored TERT and CTNNB1 mutations, respectively. TERT promotermutations were significantly more frequent in hepatocellular carcinomas related to hepatitis C virus infection (5/6; 83.3%) compared to tumors of other etiologies (P = 0.001). In two cases, discordance in TERT promoter mutation status was observed between the primary and the corresponding recurrent hepatocellular carcinoma. The two patients with discordant cases had early relapses. In conclusion, we identified TERT promoter and CTNNB1 mutations as the most frequent somatic genetic alterations observed in hepatocellular carcinoma, indicating its pivotal role in hepatocarcinogenesis. Furthermore, we suggest the possibility of intratumoral genetic heterogeneity of TERT promoter mutations in hepatocellular carcinoma as indicated by the discordance in TERT promoter mutations between primary and corresponding recurrent hepatocellular carcinoma.

Separation of chlorogenic acid and concentration of trace caffeic acid from natural products by pH-zone-refining countercurrent chromatography.

PubMed

Lu, Yuanyuan; Dong, Genlai; Gu, Yanxiang; Ito, Yoichiro; Wei, Yun

2013-07-01

Chlorogenic acid and caffeic acid were selected as test samples for separation by the pH-zone-refining countercurrent chromatography (CCC). The separation of these test samples was performed with a two-phase solvent system composed of methyl-tert-butyl-ether/acetonitrile/water at a volume ratio of 4:1:5 v/v/v where trifluoroacetic acid (TFA; 8 mM) was added to the organic stationary phase as a retainer and NH4 OH (10 mM) to the aqueous mobile phase as an eluter. Chlorogenic acid was successfully separated from Flaveria bidentis (L.) Kuntze (F. bidentis) and Lonicerae Flos by pH-zone-refining CCC, a slightly polar two-phase solvent system composed of methyl-tert-butyl-ether/acetonitrile/n-butanol/water at a volume ratio of 4:1:1:5 v/v/v/v was selected where TFA (3 mM) was added to the organic stationary phase as a retainer and NH4 OH (3 mM) to the aqueous mobile phase as an eluter. A 16.2 mg amount of chlorogenic acid with the purity of 92% from 1.4 g of F. bidentis, and 134 mg of chlorogenic acid at the purity of 99% from 1.3 g of crude extract of Lonicerae Flos have been obtained. These results suggest that pH-zone-refining CCC is suitable for the isolation of the chlorogenic acid from the crude extracts of F. bidentis and Lonicerae Flos. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lipase-catalyzed kinetic resolution of novel antitubercular benzoxazole derivatives.

PubMed

Łukowska-Chojnacka, Edyta; Kowalkowska, Anna; Napiórkowska, Agnieszka

2018-04-01

Novel benzoxazole derivatives were synthesized, and their antitubercular activity against sensitive and drug-resistant Mycobacterium tuberculosis strains (M. tuberculosis H 37 Rv, M. tuberculosis sp. 210, M. tuberculosis sp. 192, Mycobacterium scrofulaceum, Mycobacterium intracellulare, Mycobacterium fortuitum, Mycobacterium avium, and Mycobacterium kansasii) was evaluated. The chemical step included preparation of ketones, alcohols, and esters bearing benzoxazole moiety. All racemic mixtures of alcohols and esters were separated in Novozyme SP 435-catalyzed transesterification and hydrolysis, respectively. The transesterification reactions were carried out in various organic solvents (tert-butyl methyl ether, toluene, diethyl ether, and diisopropyl ether), and depending on the solvent, the enantioselectivity of the reactions ranged from 4 to >100. The enzymatic hydrolysis of esters was performed in 2 phase tert-butyl methyl ether/phosphate buffer (pH = 7.2) system and provided also enantiomerically enriched products (ee 88-99%). The antitubercular activity assay has shown that synthesized compounds exhibit an interesting antitubercular activity. Racemic mixtures of alcohols, (±)-4-(1,3-benzoxazol-2-ylsulfanyl)butan-2-ol ((±)-3a), (±)-4-[(5-bromo-1,3-benzoxazol-2-yl)sulfanyl]butan-2-ol ((±)-3b), and (±)-4-[(5,7-dibromo-1,3-benzoxazol-2-yl)sulfanyl]butan-2-ol ((±)-3c), displayed as high activity against M. scrofulaceum, M. intracellulare, M. fortuitum, and M. kansasii as commercially available antituberculosis drug-Isoniazid. Moreover, these compounds exhibited twice higher activity toward M. avium (MIC 12.5) compared with Isoniazid (MIC 50). © 2017 Wiley Periodicals, Inc.

Gas chromatographic-mass spectrometric determination of alkylphosphonic acids from aqueous samples by ion-pair solid-phase extraction on activated charcoal and methylation.

PubMed

Vijaya Saradhi, U V R; Prabhakar, S; Jagadeshwar Reddy, T; Murty, M R V S

2007-07-20

In the present paper, we report an improved ion-pair solid-phase extraction (IP-SPE) method for the analysis of alkylphosphonic acids, namely, methyl, ethyl and propylphosphonic acids, present in the aqueous sample. The aqueous sample was mixed with an ion-pair reagent, phenyltrimethylammonium hydroxide (PTMAH) and passed through activated charcoal SPE cartridge. The retained chemicals in the cartridge were extracted with methanol and analysed by gas chromatography-mass spectrometry (GC-MS) under the electron impact ionization (EI) mode. The analytes were converted to their methyl esters by pyrolytic methylation in the hot GC injection port. The recoveries of alkylphosphonic acids were above 95% and the minimum detection limits were as low as 10 ng/mL. The recovery of the test chemicals was tested with solvents, dichloromethane, n-hexane, ethyl acetate, acetone, acetonitrile and methanol. The chemicals could be efficiently extracted by the hydrophilic solvents. The method did not work at the highly acidic pH (when acidified with dilute HCl) but worked well from pH 4.0 to 14.0. The present method was also tested with other tetra-(methyl, ethyl, propyl and n-butyl)ammonium hydroxides. The test chemicals were not converted to their methyl and ethyl esters with tetramethyl and tetraethylammonium hydroxides, whereas they were converted to their corresponding propyl and n-butyl esters with tetrapropyl and tetra(n-butyl)ammonium hydroxides. The method was also applied to two highly cross-linked polymeric sorbents DSC-6S and Oasis HLB. The recovery of the chemicals on these sorbents was observed to be poor. Methylation using phenyltrimethylammonium hydroxide is non-hazardous and advantageous over methylation using diazomethane. The method was applied to the analysis of aqueous samples given in one of the official proficiency tests conducted by the Organization for the Prohibition of Chemical Weapons and all the spiked chemicals were identified as methyl esters.

21 CFR 181.27 - Plasticizers.

Code of Federal Regulations, 2010 CFR

2010-04-01

...: Acetyl tributyl citrate. Acetyl triethyl citrate. p-tert-Butylphenyl salicylate. Butyl stearate. Butylphthalyl butyl glycolate. Dibutyl sebacate. Di-(2-ethylhexyl) phthalate (for foods of high water content...

21 CFR 181.27 - Plasticizers.

Code of Federal Regulations, 2011 CFR

2011-04-01

...: Acetyl tributyl citrate. Acetyl triethyl citrate. p-tert-Butylphenyl salicylate. Butyl stearate. Butylphthalyl butyl glycolate. Dibutyl sebacate. Di-(2-ethylhexyl) phthalate (for foods of high water content...

Steric control of the asymmetric synthesis of N-substituted 2-methyl-4-piperidones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grishina, G.V.; Potapov, V.M.; Abdulganeeva, S.A.

Transmission of the iodomethylate of 1,2-dimethyl-4-piperidone by (S)-sec-butylamine gives 1-(S-sec-butyl)-2S-methyl-4-piperidone in 33% optical yield while transamination by (S)-1-methyl-2-phenylethylamine gives a 1:1 diastereomeric mixture of 1-(1-methyl-2-phenylethyl)-2-methyl-4-piperidone. The decrease in the optical yield is related to the facile opening of the piperidone ring at the C-N bond with subsequent recyclization. The /sup 13/C NMR data indicate that all the diastereomers of the 4-piperidones obtained are in the chain conformation with predominantly equatorial orientation of the methyl group at C/sub (2)/. The chiral optical properties were studied and the absolution configurations of the 4-piperidones obtained were established.

Chromatin Redistribution of the DEK Oncoprotein Represses hTERT Transcription in Leukemias12

PubMed Central

Karam, Maroun; Thenoz, Morgan; Capraro, Valérie; Robin, Jean-Philippe; Pinatel, Christiane; Lancon, Agnès; Galia, Perrine; Sibon, David; Thomas, Xavier; Ducastelle-Lepretre, Sophie; Nicolini, Franck; El-Hamri, Mohamed; Chelghoun, Youcef; Wattel, Eric; Mortreux, Franck

2014-01-01

Although numerous factors have been found to modulate hTERT transcription, the mechanism of its repression in certain leukemias remains unknown. We show here that DEK represses hTERT transcription through its enrichment on the hTERT promoter in cells from chronic and acute myeloid leukemias, chronic lymphocytic leukemia, but not acute lymphocytic leukemias where hTERT is overexpressed. We isolated DEK from the hTERT promoter incubated with nuclear extracts derived from fresh acute myelogenous leukemia (AML) cells and from cells expressing Tax, an hTERT repressor encoded by the human T cell leukemia virus type 1. In addition to the recruitment of DEK, the displacement of two potent known hTERT transactivators from the hTERT promoter characterized both AML cells and Tax-expressing cells. Reporter and chromatin immunoprecipitation assays permitted to map the region that supports the repressive effect of DEK on hTERT transcription, which was proportionate to the level of DEK-promoter association but not with the level of DEK expression. Besides hTERT repression, this context of chromatin redistribution of DEK was found to govern about 40% of overall transcriptional modifications, including those of cancer-prone genes. In conclusion, DEK emerges as an hTERT repressor shared by various leukemia subtypes and seems involved in the deregulation of numerous genes associated with leukemogenesis. PMID:24563617

LC-MS-Based Lipidomics and Automated Identification of Lipids Using the LipidBlast In-Silico MS/MS Library.

PubMed

Cajka, Tomas; Fiehn, Oliver

2017-01-01

This protocol describes the analysis, specifically the identification, of blood plasma lipids. Plasma lipids are extracted using methyl tert-butyl ether (MTBE), methanol, and water followed by separation and data acquisition of isolated lipids using reversed-phase liquid chromatography coupled to quadrupole/time-of-flight mass spectrometry (RPLC-QTOFMS) operated in MS/MS mode. For lipid identification, acquired MS/MS spectra are converted to the mascot generic format (MGF) followed by library search using the in-silico MS/MS library LipidBlast. Using this approach, lipid classes, carbon-chain lengths, and degree of unsaturation of fatty-acid components are annotated.

Total to withdraw from Qatar methanol - MTBE?

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Total is rumored to be withdrawing from the $700-million methanol and methyl tert-butyl ether (MTBE) Qatar Fuel Additives Co., (Qafac) project. The French company has a 12.5% stake in the project. Similar equity is held by three other foreign investors: Canada`s International Octane, Taiwan`s Chinese Petroleum Corp., and Lee Change Yung Chemical Industrial Corp. Total is said to want Qafac to concentrate on methanol only. The project involves plant unit sizes of 610,000 m.t./year of MTBE and 825,000 m.t./year of methanol. Total declines to comment.

Long-term study of migration of volatile organic compounds from cross-linked polyethylene (PEX) pipes and effects on drinking water quality.

PubMed

Lund, Vidar; Anderson-Glenna, Mary; Skjevrak, Ingun; Steffensen, Inger-Lise

2011-09-01

The objectives of this study were to investigate migration of volatile organic compounds (VOCs) from cross-linked polyethylene (PEX) pipes used for drinking water produced by different production methods, and to evaluate their potential risk for human health and/or influence on aesthetic drinking water quality. The migration tests were carried out in accordance with EN-1420-1, and VOCs were analysed by gas chromatography-mass spectrometry. The levels of VOC migrating from new PEX pipes were generally low, and decreasing with time of pipe use. No association was found between production method of PEX pipes and concentration of migration products. 2,4-di-tert-butyl phenol and methyl tert-butyl ether (MTBE) were two of the major individual components detected. In three new PEX pipes, MTBE was detected in concentrations above the recommended US EPA taste and odour value for drinking water, but decreased below this value after 5 months in service. However, the threshold odour number (TON) values for two pipes were similar to new pipes even after 1 year in use. For seven chemicals for which conclusions on potential health risk could be drawn, this was considered of no or very low concern. However, odour from some of these pipes could negatively affect drinking water for up to 1 year.

Degradation of MTBE and TBA by a new isolate from MTBE-contaminated soil.

PubMed

Zhang, Rui-Ling; Huang, Guo-Qiang; Lian, Jing-Yan; Li, Xin-Gang

2007-01-01

Methyl tert-butyl ether (MTBE), a gasoline additive, possesses serious problems to the environmental health. In the present study, a bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil. The isolate was identified as Chryseobacterium sp., a new species capable of degrading MTBE. In order to enhance its degradation ability, selected environment factors were investigated. The results showed that the optimal temperature was in the range of 25-30 degrees C, the pH was 7.0, the inoculum size was 2 x 10(8) CFU/ml and the optimal concentration of MTBE was from 50 to 100 mg/L. The maximum MTBE utilization rate (upsilon(max)) was 102 nmol MTBE/(mg cell protein x h). Furthermore, it was found that the isolate could also degrade tert-butyl alcohol (TBA). The degradation rates of TBA were much faster than those of MTBE. The additional TBA would lead to the decrease of the initial MTBE degradation rate and the inhibitory effect of TBA increased with the increase of TBA concentration. Similar protein profiles at least seven peptides were demonstrated after SDS-PAGE analysis of crude extracts obtained from the cells growing in MTBE and TBA culture.

Field Confirmation and Monitoring Tools for Aerobic Bioremediation of TBA and MTBE

NASA Astrophysics Data System (ADS)

North, K.; Rasa, E.; Mackay, D. M.; Scow, K. M.; Hristova, K. R.

2009-12-01

We have been investigating in situ biotreatment of an existing tert-butyl alcohol (TBA) plume at Vandenberg AFB by recirculation/oxygenation and evaluating monitoring tools for microbial community composition and activity inside and outside of the treatment zone. Results indicate that recirculation/oxygenation by two pairs of recirculation wells is effective at adding oxygen and decreasing methyl tert-butyl ether (MTBE) and TBA concentrations to detection limits along the flowpaths predicted. Compound-specific isotope analyses (CSIA) of groundwater and microbial community analyses (extraction and analysis of DNA) of groundwater and sediments are underway for sampling locations along flowpaths inside and outside of the treatment zone to seek confirmation of in situ biodegradation. We are also evaluating a novel approach to compare the performance of microbial “traps” in characterizing microbial communities: groundwater from the aerobic treatment zone is extracted, separated and directed to multiple chambers located in an air-conditioned ex situ experimental setup. The “traps” under evaluation are in separate chambers; influent and effluent are monitored. The traps being evaluated include Bio-Trap® housings containing Bio-Sep® beads baited with MTBE or TBA labeled with 13C and various unbaited materials. Insights from the various monitoring approaches will be discussed and compared.

Butylate

Integrated Risk Information System (IRIS)

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

Sequestering ability of butylated hydroxytoluene, propyl gallate, resveratrol, and vitamins C and E against ABTS, DPPH, and hydroxyl free radicals in chemical and biological systems.

PubMed

Soares, Daniele G; Andreazza, Ana C; Salvador, Mirian

2003-02-12

The antioxidant capacity of butylated hydroxytoluene (BHT; 2,6-di-tert-butyl-p-cresol), propyl gallate (3,4,5-trihydroxybenzoic acid n-propyl ester), resveratrol (trans-3,4',5-trihydroxystilbene), and vitamins C (l-ascorbic acid) and E [(+)-alpha-tocopherol] was studied in chemical and biological systems. The chemical assays evaluated the capacity of these antioxidants to sequester 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS.) and 1,1 diphenyl-2-picrylhydrazyl (DPPH.). A new colorimetric method to determine hydroxyl radical scavenging is also described. The biological tests use the eucaryotic cells of Saccharomyces cerevisiae treated with the antioxidants in the presence of the stressing agents apomorphine, hydrogen peroxide, and paraquat dichloride (methylviologen; 1,1'-dimethyl-4,4'-bipyridinium dichloride). The results in chemical systems showed that all of the antioxidants were able to significantly inhibit the oxidation of beta-carotene by hydroxyl free radicals. The assays in yeast showed that the antioxidant activity of the tested compounds depended on the stressing agent used and the mechanism of action of the antioxidant.

Effects of Ammonium Dinitramide in Human Liver Slices: An EPR/Spin Trapping Study.

DTIC Science & Technology

1995-09-01

environmentally safe than AP. EPR/spin trapping studies with the spin trap N-tert-butyl-a-phenyl nitrone (PBN lOmM) for 5 min in the presence of ADN yielded...N-tert-butyl-a-phenyl nitrone PBN 17. SECURITY CLASSIFICATION OF REPORT UNCLASSIFIED 18. SECURITY CLASSIFICATION OF THIS PAGE UNCLASSIFIED... nitrone s second SCN- thiocyanate SD standard deviation Vll INTRODUCTION This is a study of the reactions of free radicals formed when ammonium

The First Seven-Coordinated Triiodo Complex of Rhenium(III)

NASA Astrophysics Data System (ADS)

Schoultz, X.; Gerber, T. I. A.; Betz, R.; Hosten, E. C.

2017-12-01

The reaction of cis-[ReO2I(P Ph 3)2] with tert-butyl isocyanide in benzene led to the isolation of the complex [ReI3(CN- t-Bu)3(P Ph 3)] ( 1). The complex is unusual since it contains bulky ligands with large cone angles, i.e. three iodides, three isocyanides with tert-butyl groups and a triphenylphosphine as ligands in a seven-coordinate geometry around the rhenium(III) metal ion.

Synthesis and solution self-assembly of side-chain cobaltocenium-containing block copolymers.

PubMed

Ren, Lixia; Hardy, Christopher G; Tang, Chuanbing

2010-07-07

The synthesis of side-chain cobaltocenium-containing block copolymers and their self-assembly in solution was studied. Highly pure monocarboxycobaltocenium was prepared and subsequently attached to side chains of poly(tert-butyl acrylate)-block-poly(2-hydroxyethyl acrylate), yielding poly(tert-butyl acrylate)-block-poly(2-acryloyloxyethyl cobaltoceniumcarboxylate). The cobaltocenium block copolymers exhibited vesicle morphology in the mixture of acetone and water, while micelles of nanotubes were formed in the mixture of acetone and chloroform.

Isotope-dilution gas chromatography-mass spectrometry coupled with injection-port butylation for the determination of 4-t-octylphenol, 4-nonylphenols and bisphenol A in human urine.

PubMed

Chung, Shuang-Hung; Ding, Wang-Hsien

2018-02-05

An analytical method that utilizes isotope-dilution gas chromatography-mass spectrometry (ID-GC-MS) coupled with injection-port butylation was developed. The method was validated, and confirmed to be able to determine the presence of three commonly detected endocrine-disrupting chemicals (EDCs: 4-tert-octylphenol (4-t-OP), 4-nonylphenols (4-NPs) and bisphenol A (BPA)) in human urine with high precision and accuracy. After sample preparation by solid-phase extraction, the extract was introduced into GC-MS via injection-port butylation. The butylated target analytes were identified and quantified by using ion-trap mass spectrometry operating in the selected-ion-storage mode, and employing the measurement of peak area ratios of the butylated target analytes and labeled-analogues in the samples and calibration standards. The labeled-analogues were also used to correct the variations associated with the analysis and matrix effect. The limits of quantitation (LOQs) ranged from 0.1 to 0.3ng/mL. High precisions for both intra- and inter-day analysis ranged from 1 to 6%, and excellent accuracy (mean recovery) ranged from 92 to 105% on two concentration levels. In human urine, the total concentrations of three selected EDCs varied from 1.28 to 7.14ng/mL. 4-NPs were detected within all collected samples. The developed method allows accurate analysis of trace-level of EDCs in urine, and these target EDCs could act as useful biomarkers to assess exposure in biomonitoring studies and programs. Copyright © 2017 Elsevier B.V. All rights reserved.

Clinicopathological characteristics of TERT promoter mutation and telomere length in hepatocellular carcinoma.

PubMed

Lee, Hye Won; Park, Tae In; Jang, Se Young; Park, Soo Young; Park, Won-Jin; Jung, Soo-Jung; Lee, Jae-Ho

2017-02-01

Promoter mutations in telomerase reverse transcriptase (TERT) and telomere length have been studied in various tumors. In the present study, the frequency and clinical characteristics of TERT promoter mutation and telomere length were studied in hepatocellular carcinoma (HCC). TERT promoter mutation and telomere length were analyzed in 162 tumor samples of the patients with HCC by sequencing and real-time PCR, respectively. The TERT promoter mutation rate was 28.8% (46/160) in HCC and was associated with males (P = 0.027). The telomere length was not significantly different in the presence of a TERT promoter mutation but was shorter in high-grade tumor stages (P = 0.048). Survival analyses showed that poor overall survival was associated with longer telomere length (P = 0.013). However, the TERT promoter mutation did not have a prognostic value for HCC. Multivariate survival analyses demonstrated that the telomere length was an independent prognostic marker for poor overall survival (hazard ratio = 1.75, 95% confidence interval: 1.046-2.913, P = 0.033). These data demonstrated that TERT promoter mutation is a frequent event in HCC; however, telomere length, but not the presence of a TERT promoter mutation, might have potential value as a prognostic indicator of HCC.

40 CFR 721.644 - Amines, C12-14-tert-alkyl, sulfonates.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Amines, C12-14-tert-alkyl, sulfonates... Substances § 721.644 Amines, C12-14-tert-alkyl, sulfonates. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as amines, C12-14-tert-alkyl, sulfonates (PMN...

40 CFR 721.644 - Amines, C12-14-tert-alkyl, sulfonates.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Amines, C12-14-tert-alkyl, sulfonates... Substances § 721.644 Amines, C12-14-tert-alkyl, sulfonates. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as amines, C12-14-tert-alkyl, sulfonates (PMN...

Release of drinking water contaminants and odor impacts caused by green building cross-linked polyethylene (PEX) plumbing systems.

PubMed

Kelley, Keven M; Stenson, Alexandra C; Dey, Rajarashi; Whelton, Andrew J

2014-12-15

Green buildings are increasingly being plumbed with crosslinked polyethylene (PEX) potable water pipe. Tap water quality was investigated at a six month old plumbing system and chemical and odor quality impacts of six PEX pipe brands were examined. Eleven PEX related contaminants were found in the plumbing system; one regulated (toluene) and several unregulated: Antioxidant degradation products, resin solvents, initiator degradation products, or manufacturing aides. Water chemical and odor quality was monitored for new PEX-a, -b and -c pipes with (2 mg/L free chlorine) and without disinfectant over 30 days. Odor and total organic carbon (TOC) levels decreased for all pipes, but odor remained greater than the USA's Environmental Protection Agency's (USEPA) secondary maximum contaminant level. Odors were not attributed to known odorants ethyl-tert-butyl ether (ETBE) or methyl-tert-butyl ether (MTBE). Free chlorine caused odor levels for PEX-a1 pipe to increase from 26 to 75 threshold odor number (TON) on day 3 and affected the rate at which TOC changed for each brand over 30 days. As TOC decreased, the ultraviolet absorbance at 254 nm increased. Pipes consumed as much as 0.5 mg/L as Cl2 during each 3 day stagnation period. Sixteen organic chemicals were identified, including toluene, pyridine, methylene trichloroacetate and 2,4-di-tert-butylphenol. Some were also detected during the plumbing system field investigation. Six brands of PEX pipes sold in the USA and a PEX-a green building plumbing system impacted chemical and drinking water odor quality. Copyright © 2014 Elsevier Ltd. All rights reserved.

40 CFR 60.707 - Chemicals affected by subpart RRR.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-7 Brometone 76-08-4 1,3-Butadiene 106-99-0 Butadiene and butene fractions n-Butane 106-97-8 1,4-Butanediol 110-63-4 Butanes, mixed 1-Butene 106-98-9 2-Butene 25167-67-3 Butenes, mixed n-Butyl acetate 123-86-4 Butyl acrylate 141-32-2 n-Butyl alcohol 71-36-3 sec-Butyl alcohol 78-92-2 tert-Butyl alcohol 75...

40 CFR 60.707 - Chemicals affected by subpart RRR.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-7 Brometone 76-08-4 1,3-Butadiene 106-99-0 Butadiene and butene fractions n-Butane 106-97-8 1,4-Butanediol 110-63-4 Butanes, mixed 1-Butene 106-98-9 2-Butene 25167-67-3 Butenes, mixed n-Butyl acetate 123-86-4 Butyl acrylate 141-32-2 n-Butyl alcohol 71-36-3 sec-Butyl alcohol 78-92-2 tert-Butyl alcohol 75...

40 CFR 60.707 - Chemicals affected by subpart RRR.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-7 Brometone 76-08-4 1,3-Butadiene 106-99-0 Butadiene and butene fractions n-Butane 106-97-8 1,4-Butanediol 110-63-4 Butanes, mixed 1-Butene 106-98-9 2-Butene 25167-67-3 Butenes, mixed n-Butyl acetate 123-86-4 Butyl acrylate 141-32-2 n-Butyl alcohol 71-36-3 sec-Butyl alcohol 78-92-2 tert-Butyl alcohol 75...

(1-Butyl-4-methyl-pyridinium)[Cu(SCN)2]: a coordination polymer and ionic liquid.

PubMed

Spielberg, Eike T; Edengeiser, Eugen; Mallick, Bert; Havenith, Martina; Mudring, Anja-Verena

2014-04-25

The compound (C4C1py)[Cu(SCN)2], (C4C1py = 1-Butyl-4-methyl-pyridinium), which can be obtained from CuSCN and the ionic liquid (C4C1py)(SCN), turns out to be a new organic-inorganic hybrid material as it qualifies both, as a coordination polymer and an ionic liquid. It features linked [Cu(SCN)2](-) units, in which the thiocyanates bridge the copper ions in a μ1,3-fashion. The resulting one-dimensional chains run along the a axis, separated by the C4C1py counterions. Powder X-ray diffraction not only confirms the single-crystal X-ray structure solution but proves the reformation of the coordination polymer from an isotropic melt. However, the materials shows a complex thermal behavior often encountered for ionic liquids such as a strong tendency to form a supercooled melt. At a relatively high cooling rate, glass formation is observed. When heating this melt in differential scanning calorimetry (DSC) and temperature-dependent polarizing optical microscopy (POM), investigations reveal the existence of a less thermodynamically stable crystalline polymorph. Raman measurements conducted at 10 and 100 °C point towards the formation of polyanionic chain fragments in the melt. Solid-state UV/Vis spectroscopy shows a broad absorption band around 18,870 cm(-1) (530 nm) and another strong one below 20,000 cm(-1) (<500 nm). The latter is attributed to the d(Cu(I))→π*(SCN)-MLCT (metal-to-ligand charge transfer) transition within the coordination polymer yielding an energy gap of 2.4 eV. At room temperature and upon irradiation with UV light, the material shows a weak fluorescence band at 15,870 cm(-1) (630 nm) with a quantum efficiency of 0.90(2) % and a lifetime of 131(2) ns. Upon lowering the temperature, the luminescence intensity strongly increases. Simultaneously, the band around 450 nm in the excitation spectrum decreases. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Millimeterwave Spectrum of n-BUTYL Cyanide

NASA Astrophysics Data System (ADS)

Ordu, Matthias H.; Müller, Holger S. P.; Lewen, Frank; Schlemmer, Stephan; Nez, Marc Nu; Walters, Adam

2011-06-01

The rotational spectrum of n-butyl cyanide (C_4H_9CN) was measured between 75 and 130 GHz using a novel all-solid-state spectrometer with a total absorption path of 44 m. In the course of the analysis of the spectrum, about 3000 transitions were assigned and a full set of quartic centrifugal distortion parameters with some sextic and octic terms could be determined for each of the three known conformers (anti-anti, anti-gauche(methyl end) and gauche(CN end)-anti). The work was motivated by the fact that n-butyl cyanide is likely to be found in interstellar hot core environments. This is indicated by the discovery of n-propyl cyanide (C_3H_7CN), the next smaller alkyl cyanide, in the ISM. The increased accuracy of the model, which will be additionally extended by future laboratory measurements around 200 GHz, may now be employed for a prediction of the spectrum up to 300 GHz with a feasible uncertainty for astronomic line surveys. Furthermore, there are two less abundant conformers, cis-gauche-gauche and trans-gauche-gauche, which have not yet been detected in the rotational spectrum. Due to the increased sensitivity of the new spectrometer, it seems possible now for the first time to identify their sectroscopic fingerprints in the recorded data. A. Belloche, R. T. Garrod, H. S. P.Müller, K. M. Menten, C. Comito, and P. Schilke, Astronomy & Astrophysics 499, 215 (2009) R. K. Bohn, J. L. Pardus, J. August, T. Brupbacher, W. Jäger, J. Mol. Struct. 413-414, 293 (1997)

Transgenic rat model of childhood-onset dermatitis by overexpressing telomerase reverse transcriptase (TERT).

PubMed

Kaneko, Ryosuke; Sato, Atsuko; Hamada, Shun; Yagi, Takeshi; Ohsawa, Ichiro; Ohtsuki, Mamitaro; Kobayashi, Eiji; Hirabayashi, Masumi; Murakami, Takashi

2016-08-01

Childhood-onset dermatitis is one of the most common skin disorders in children. Although various mouse models that mirror aspects of dermatitis have become available, there is still a need for an animal model that develops dermatitis in childhood and is more suitable for performing tissue transplantation experiments. There is emerging evidence that peripheral blood T lymphocytes from patients with dermatitis have significantly increased telomerase activity. Here, we developed telomerase reverse transcriptase (TERT)-expressing transgenic (Tg) rats that spontaneously developed eczematous skin inflammation in childhood. Newborn TERT-Tg rats developed visible dermatitis in 56 % of cases, and the skin lesions microscopically showed spongiosis and acanthosis with infiltration of lymphocytes, eosinophils and mast cells. TERT-Tg rats with dermatitis exhibited increased CD4 (2.5-fold) and CD8 (fivefold) T cell numbers compared with dermatitis-free TERT-Tg rats. Stronger TERT activity was observed in the peripheral lymphocytes of dermatitis-positive TERT-Tg rats than those of dermatitis-free TERT-Tg rats. RT-PCR analysis revealed that IL-4 was markedly elevated in the spleen of dermatitis-positive TERT-Tg rats, and that interferon-gamma was increased in the dermatitis lesions. Moreover, skin grafting of TERT-Tg rats with dermatitis onto T cell-deficient nude rats demonstrated that the inflamed skin lesions could not be maintained. Taken together, the results suggest that TERT activation in T lymphocytes is one of the potential predisposing factors for dermatitis. Moreover, our results demonstrated that the TERT-Tg rats mirror aspects of human childhood-onset dermatitis and that these animals represent a potential animal model system for studying childhood-onset dermatitis.

Tetra­kis(2,3,5,5-tetra­methyl­hexen-2-yl)silane

PubMed Central

Meyer-Wegner, Frank; Bolte, Michael; Lerner, Hans-Wolfram

2014-01-01

In the title compound, C40H76Si, the Si atom is located on a special position of site symmetry -4. Thus, there is just a quarter of a mol­ecule in the asymmetric unit. The C=C double bonds exhibit a trans configuration. The Si atom and the tert-butyl group are located on the same side of the plane formed by the C=C double bond and its four substituents. The crystal packing shows no short contacts between the mol­ecules and despite the low crystal density (0.980 Mg m−3), there are no significant voids in the structure. PMID:24765057

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

PubMed

Saravanan, S; Balachandran, V

2014-09-15

This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) 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. Copyright © 2014 Elsevier B.V. All rights reserved.

Proteome alteration induced by hTERT transfection of human fibroblast cells.

PubMed

Mazzucchelli, Gabriel D; Gabelica, Valérie; Smargiasso, Nicolas; Fléron, Maximilien; Ashimwe, Wilson; Rosu, Frédéric; De Pauw-Gillet, Marie-Claire; Riou, Jean-François; De Pauw, Edwin

2008-04-17

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 to that purpose. The effect of the transfection has been studied on the proteome of human fibroblast (WI38). Cytosolic and nuclear fractions of WI38 cells, empty vector transfected WI38 (WI38-HPV) and hTERT WI38 cells were submitted to a 2D-DIGE (Two-Dimensional Differential In-Gel Electrophoresis) analysis. Only spots that had a similar abundance in WI38 and WI38-HPV, but were differentially expressed in WI38 hTERT were selected for MS identification. This method directly points to the proteins linked with the hTERT expression. Number of false positive differentially expressed proteins has been excluded by using control WI38-HPV cells. The proteome alteration induced by hTERT WI38 transfection should be taken into account in subsequent use of the cell line for anti-telomerase drugs evaluation. 2D-DIGE experiment shows that 57 spots out of 2246 are significantly differentially expressed in the cytosolic fraction due to hTERT transfection, and 38 were confidently identified. In the nuclear fraction, 44 spots out of 2172 were selected in the differential proteome analysis, and 14 were identified. The results show that, in addition to elongating telomeres, hTERT gene transfection has other physiological roles, among which an enhanced ER capacity and a potent cell protection against apoptosis. We show that the methodology reduces the complexity of the proteome analysis and highlights proteins implicated in other processes than telomere elongation. hTERT induced proteome changes suggest that telomerase expression enhances natural cell repair

Use B-spline interpolation fitting baseline for low concentration 2, 6-di-tertbutyl p-cresol determination in jet fuels by differential pulse voltammetry

NASA Astrophysics Data System (ADS)

Wen, D. S.; Wen, H.; Shi, Y. G.; Su, B.; Li, Z. C.; Fan, G. Z.

2018-01-01

The B-spline interpolation fitting baseline in electrochemical analysis by differential pulse voltammetry was established for determining the lower concentration 2,6-di-tert-butyl p-cresol(BHT) in Jet Fuel that was less than 5.0 mg/L in the condition of the presence of the 6-tert-butyl-2,4-xylenol.The experimental results has shown that the relative errors are less than 2.22%, the sum of standard deviations less than 0.134mg/L, the correlation coefficient more than 0.9851. If the 2,6-ditert-butyl p-cresol concentration is higher than 5.0mg/L, linear fitting baseline method would be more applicable and simpler.

[Total analysis of organic rubber additives].

PubMed

He, Wen-Xuan; Robert, Shanks; You, Ye-Ming

2010-03-01

In the present paper, after middle pressure chromatograph separation using both positive phase and reversed-phase conditions, the organic additives in ethylene-propylene rubber were identified by infrared spectrometer. At the same time, by using solid phase extraction column to maintain the main component-fuel oil in organic additves to avoid its interfering with minor compounds, other organic additves were separated and analysed by GC/Ms. In addition, the remaining active compound such as benzoyl peroxide was identified by CC/Ms, through analyzing acetone extract directly. Using the above mentioned techniques, soften agents (fuel oil, plant oil and phthalte), curing agent (benzoylperoxide), vulcanizing accelerators (2-mercaptobenzothiazole, ethyl thiuram and butyl thiuram), and antiagers (2, 6-Di-tert-butyl-4-methyl phenol and styrenated phenol) in ethylene-propylene rubber were identified. Although the technique was established in ethylene-propylene rubber system, it can be used in other rubber system.

PREPARATIVE ISOLATION AND PURIFICATION OF CHEMICAL CONSTITUENTS OF BELAMCANDA BY MPLC, HSCCC AND PREP-HPLC

PubMed Central

Wang, Xiaohong; Liang, Yong; Peng, Cuilin; Xie, Huichun; Pan, Man; Zhang, Tianyou; Ito, Yoichiro

2010-01-01

Combined with medium-pressure liquid chromatography (MPLC) and preparative high-pressure liquid chromatography (Prep-HPLC), high-speed countercurrent chromatography (HSCCC) was successfully applied for separation and purification of isoflavonoids from the extract of belamcanda. HSCCC separation was performed on a two-phase solvent system composed of methyl tert-butyl ether -ethyl acetate - n-butyl alcohol – acetonitrile −0.1% aqueous trifluoroacetic acid at a volume radio of 1:2:1:1:5. Semi-purified peak fractions from HSCCC separation were further purified by Prep-HPLC. Nine well-separated fractions were analyzed by HPLC-UV absorption spectrometry to determine their purities and characterized with ESI-MSn. Except for peaksland VII (unknown) seven compounds were identified as apocynin (peak II), mangiferin (peak III), 7-O-methylmangiferin (peak IV), hispidulin (peak V), 3′-hydroxyltectoridin (peak VI), iristectorin B (peak VII), isoiridin (peak IX). PMID:21552369

miR-128 inhibits telomerase activity by targeting TERT mRNA

PubMed Central

Guzman, Herlinda; Sanders, Katie; Idica, Adam; Bochnakian, Aurore; Jury, Douglas; Daugaard, Iben; Zisoulis, Dimitrios G; Pedersen, Irene Munk

2018-01-01

Telomerase is a unique cellular reverse transcriptase (RT) essential for maintaining telomere stability and required for the unlimited proliferation of cancer cells. The limiting determinant of telomerase activity is the catalytic component TERT, and TERT expression is closely correlated with telomerase activity and cancer initiation and disease progression. For this reason the regulation of TERT levels in the cell is of great importance. microRNAs (miRs) function as an additional regulatory level in cells, crucial for defining expression boundaries, proper cell fate decisions, cell cycle control, genome integrity, cell death and metastasis. We performed an anti-miR library screen to identity novel miRs, which participate in the control of telomerase. We identified the tumor suppressor miR (miR-128) as a novel endogenous telomerase inhibitor and determined that miR-128 significantly reduces the mRNA and protein levels of Tert in a panel of cancer cell lines. We further evaluated the mechanism by which miR-128 regulates TERT and demonstrated that miR-128 interacts directly with the coding sequence of TERT mRNA in both HeLa cells and teratoma cells. Interestingly, the functional miR-128 binding site in TERT mRNA, is conserved between TERT and the other cellular reverse transcriptase encoded by Long Interspersed Elements-1 (LINE-1 or L1), which can also contribute to the oncogenic phenotype of cancer. This finding supports the novel idea that miRs may function in parallel pathways to inhibit tumorigenesis, by regulating a group of enzymes (such as RT) by targeting conserved binding sites in the coding region of both enzymes. PMID:29568354

TERT promoter mutation status as an independent prognostic factor in cutaneous melanoma.

PubMed

Griewank, Klaus G; Murali, Rajmohan; Puig-Butille, Joan Anton; Schilling, Bastian; Livingstone, Elisabeth; Potrony, Miriam; Carrera, Cristina; Schimming, Tobias; Möller, Inga; Schwamborn, Marion; Sucker, Antje; Hillen, Uwe; Badenas, Celia; Malvehy, Josep; Zimmer, Lisa; Scherag, André; Puig, Susana; Schadendorf, Dirk

2014-09-01

Recently, TERT promoter mutations were identified at high frequencies in cutaneous melanoma tumor samples and cell lines. The mutations were found to have a UV-signature and to lead to increased TERT gene expression. We analyzed a large cohort of melanoma patients for the presence and distribution of TERT promoter mutations and their association with clinico-pathological characteristics. 410 melanoma tumor samples were analyzed by Sanger sequencing for the presence of TERT promoter mutations. An analysis of associations between mutation status and various clinical and pathologic variables was performed. TERT promoter mutations were identified in 154 (43%) of 362 successfully sequenced melanomas. Mutation frequencies varied between melanoma subtype, being most frequent in melanomas arising in nonacral skin (48%) and melanomas with occult primary (50%), and less frequent in mucosal (23%), and acral (19%) melanomas. Mutations carried a UV signature (C>T or CC>TT). The presence of TERT promoter mutations was associated with factors such as BRAF or NRAS mutation (P < .001), histologic type (P = .002), and Breslow thickness (P < .001). TERT promoter mutation was independently associated with poorer overall survival in patients with nonacral cutaneous melanomas (median survival 80 months vs 291 months for wild-type; hazard ratio corrected for other covariates 2.47; 95% confidence interval [CI] = 1.29 to 4.74; P = .006). UV-induced TERT promoter mutations are one of the most frequent genetic alterations in melanoma, with frequencies varying depending on melanoma subtype. In nonacral cutaneous melanomas, presence of TERT promoter mutations is independently associated with poor prognosis. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

The study of DNA adduct 8-hydroxy-2‧deoxyguanosine (8-OHdG) formation of butylated hydroxyanisole (BHA) and its metabolite ter-butyl hydroquinone (TBHQ) through in vitro reaction with Calf Thymus DNA and 2‧deoxyguanosine

NASA Astrophysics Data System (ADS)

Budiawan; Purwaningsih, S. S.; Cahaya, D. I.

2017-04-01

Butylated Hydroxyanisole (BHA) and its metabolite Tert-Butyl Hydroquinone (TBHQ) are synthetic antioxidants, commonly used as food and beverage preservatives. Although WHO declared their safety, the use of these preservatives are still controversial because some studies showed that BHA induced proliferative effects in animal testing and TBHQ is considered as carcinogenic and causes DNA cleavage. This study is aimed to analyze the interaction between Calf Thymus DNA with BHA and TBHQ which are mediated with Copper (II) Chloride. The result of the study in spectrophotometric showed there was bathochromic shift as much as 2-3 nm in DNA treated with TBHQ. The next analysis used HPLC method in stationary phase of ODS, mobile phase of 10mM Natrium Hydrogen Phosphate Buffer and Methanol (85 : 15) for DNA adduct formation, 8-Hydroxy-2-Deoxyguanosine (8-OHDG) as biomarker of risk cancer. The resultof the study showed the formation of DNA adduct 8-OHDG in the interaction between DNA and 20-500 ppm of TBHQ. The 8-OHdG formation was greatly increased by the higher concentration of TBHQ. The relative amount of 8 OHDG which formed was reached 946/105 deoxyguanosine in DNA bases. Confirmation test by LCMS/MS was characterized with the detection of mother ion peak (m/z 284); fragment ion peaks at m/z 167.9, and 139.9; at retention time 3.52 min. Meanwhile the interaction between DNA and 50-250 ppm BHA did not induce 8-OHDG.

40 CFR 180.576 - Cyhalofop-butyl; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Cyhalofop-butyl; tolerances for... § 180.576 Cyhalofop-butyl; tolerances for residues. (a) General. Time-limited tolerances are established for combined residues of cyhalofop (cyhalofop-butyl, R-(+)-n-butyl-2-(4(4-cyano-2-fluorophenoxy...

40 CFR 180.576 - Cyhalofop-butyl; tolerances for residues.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Cyhalofop-butyl; tolerances for... § 180.576 Cyhalofop-butyl; tolerances for residues. (a) General. Time-limited tolerances are established for combined residues of cyhalofop (cyhalofop-butyl, R-(+)-n-butyl-2-(4(4-cyano-2-fluorophenoxy...

TERT promoter mutation and its interaction with IDH mutations in glioma: Combined TERT promoter and IDH mutations stratifies lower-grade glioma into distinct survival subgroups-A meta-analysis of aggregate data.

PubMed

Vuong, Huy Gia; Altibi, Ahmed M A; Duong, Uyen N P; Ngo, Hanh T T; Pham, Thong Quang; Chan, Aden Ka-Yin; Park, Chul-Kee; Fung, Kar-Ming; Hassell, Lewis

2017-12-01

The clinical significance of telomerase reverse transcriptase (TERT) promoter mutation in glioma remains unclear. The aim of our meta-analysis is to investigate the prognostic impact TERT promoter mutation in glioma patients and its interaction with other molecular markers, particularly Isocitrate Dehydrogenase (IDH) mutation from aggregate level data. Relevant articles were searched in four electronic databases including PubMed, Scopus, Web of Science and Virtual Health Library. Pooled HRs were calculated using random effect model weighted by inverse variance method. From 1010 studies, we finally included 28 studies with 11519 patients for meta-analyses. TERT mutation is significantly associated with compromised overall survival (OS) (HR=1.38; 95% CI=1.15-1.67) and progression-free survival (PFS) (HR=1.31; 95% CI=1.06-1.63) in glioma patients. In studying its reaction with IDH, TERT promoter mutation was associated with reduced OS in both IDH-mutant (IDH-mut) and IDH-wild type (IDH-wt) glioblastomas but shown to have inverse effects on IDH-mut and IDH-wt grade II/III tumors. Our analysis categorized WHO grade II/III glioma patients into four distinct survival subgroups with descending survival as follow: TERT-mut/IDH-mut≫TERT-wt/IDH-mut≫TERT-wt/IDH-wt≫TERT-mut/IDH-wt. Prognostic value of TERT promoter mutations in gliomas is dependent on tumor grade and the IDH mutational status. With the same tumor grade in WHO grade II and III tumors and the same IDH mutation status, TERT-mut is a prognostic factor. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

Suffet, I H

2007-01-01

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.

Modulation of RBC volume distributions by oxidants (phenazine methosulfate and tert-butyl hydroperoxide): role of Gardos channel activation.

PubMed

Lisovskaya, Irina L; Shcherbachenko, Irina M; Volkova, Rimma I; Tikhonov, Vladimir P

2008-06-01

A study was made comparing the effects of two oxidants--phenazine methosulfate (50-1500 microM)+10 mM ascorbate and t-butyl hydroperoxide (1-3 mM)--on the volume-related parameters of normal human red blood cells. Incubation with either oxidative system for 20-30 min resulted in red blood cell density and osmotic resistance distribution shifts. Treatment with the phenazine methosulfate+ascorbate system in the presence of Ca(2+) led to cell shrinking, with the maximum effect being more than 20%. In contrast, under the same conditions, t-BHP caused cell swelling by up to 15%. Modification of the suspending medium (Ca(2+) removing, clotrimazole addition, or enrichment with K(+)) modulated the redistribution effects, suggesting that they were mediated to some extent by Gardos channel activation. These findings are important for understanding how oxidants modulate RBC cation channels.

Round robin test for odour testing of migration waters.

PubMed

Rapp, Thomas; Günther, Herbert

2015-04-15

For a round robin test for EN 1420-1 (Odour assessment for organic materials in contact with drinking water) with 14 contributing laboratories from 10 European countries segments of a plastic pipe were sent to the laboratories which performed a migration test and an odour analysis of the migration waters (water that had contact with the organic material) according to the procedure described in the standard from 1999. In addition reference substances (Methyl tert-butyl ether, 1-butanol and hexanal) were investigated for their suitability to qualify the panels and the individual panellists. Methyl tert-butyl ether (MtBE) and 1-butanol proved to be suitable for this purpose, whereas hexanal showed a wide distribution of the individual odour threshold concentrations. Both possible testing options (unforced and forced choice) were performed and gave similar results. However, with respect to the qualification of the panellists and the data analysis the unforced choice procedure showed advantages. As human olfactory perception is used for the analysis, the reproducibility and the comparability between laboratories is of particular concern. For the pipe material the TON results of the different laboratories were in a range of ±1.5 dilutions based on a dilution factor of 2. This might be improved by taking the individual sensitivities of the panellists into account more strongly. Appropriate measures for the improvement of the test method appear to be the use of the proposed reference substances for the training of the panellists as well as the auditing and the selection of the panellists. The results of this round robin test are used in the revision process of the standard. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analogues of methotrexate and aminopterin with gamma-methylene and gamma-cyano substitution of the glutamate side chain: synthesis and in vitro biological activity.

PubMed

Rosowsky, A; Bader, H; Freisheim, J H

1991-01-01

Analogues of methotrexate (MTX) and aminopterin (AMT) modified at the gamma-position of the glutamate side chain were synthesized and evaluated as dihydrofolate reductase (DHFR) inhibitors and tumor cell growth inhibitors. Condesations of 4-amino-4-deoxy-N10-methylpteroic acid (mAPA) with dimethyl DL-4-methyleneglutamate in the presence of diethyl phosphorocyanidate (DEPC) followed by alkaline hydrolysis yielded N-(4-amino-4-deoxy-N10-methylpteroyl)-DL-4-methyleneglutamic acid (gamma-methyleneMTX). Condensation of 4-amino-4-deoxy-N10-formylpteroic acid (fAPA) with dimethyl-DL-4-methyleneglutamate by the mixed carboxylic-carbonic anhydride method yielded N-4-amino-4-deoxypteroyl)-DL-4-methyleneglutamic acid (gamma-methyleneAMT). Also prepared via DEPC coupling was a mixture of the four possible diastereomers of N-(4-amino-4-deoxy-N10-methylpteroyl)-4-cyanoglutamic acid (gamma-cyanoMTX). The requisite intermediate gamma-tert-butyl alpha-methyl 4-cyanoglutamate, as a DL-threo/DL-erythro mixture, was prepared from methyl N alpha-Boc-O-tosyl-L-serinate by reaction with sodium tert-butyl cyanoacetate followed by mild trifluoroacetic treatment to selectively remove the Boc group. The gamma-methylene derivatives of MTX and AMT are attractive because of their potential to act as Michael acceptors within the DHFR active site. gamma-CyanoMTX may be viewed as a congener of the nonpolyglutamated MTX analogue gamma-fluoroMTX. In vitro bioassay data for the gamma-methylene and gamma-cyano compounds support the idea that the active site of DHFR, already known for its ability to tolerate modification of the gamma-carboxyl group of MTX and AMT, can likewise accommodate substitution on the gamma-carbon itself.

Unusual Internal Rotation Coupling in the Microwave Spectrum of Pinacolone

NASA Astrophysics Data System (ADS)

Zhao, YueYue; Nguyen, Ha Vinh Lam; Stahl, Wolfgang; Hougen, Jon T.

2015-06-01

The molecular-beam Fourier-transform microwave spectrum of pinacolone (methyl tert-butyl ketone) has been measured in several regions between 2 and 40 GHz. Assignments of a large number of A and E transitions were confirmed by combination differences, but fits of the assigned spectrum using several torsion-rotation computer programs based on different models led to the unexpected conclusion that no existing program correctly captures the internal dynamics of this molecule. A second puzzle arose when it became clear that roughly half of the spectrum remained unassigned even after all predicted transitions were added to the assignment list. Quantum chemical calculations carried out at the MP2/6-311++G(d,p) level indicate that this molecule does not have a plane of symmetry at equilibrium, and that internal rotation of the light methyl group induces a large oscillatory motion of the heavy tert-butyl group from one side of the C_s saddle point to the other. The effect of this non-C_s equilibrium structure was modeled for J = 0 levels by a simple two-top torsional Hamiltonian, where magnitudes of the strong top-top coupling terms were determined directly from the ab initio two-dimensional potential surface. A plot of the resultant torsional levels on the same scale as a one-dimensional potential curve along the zig-zag path connecting the six (unequally spaced) minima bears a striking resemblance to the 1:2:1 splitting pattern of levels in an internal rotation problem with a six-fold barrier. A plot of the six minima closely resembles the potential surface for methylamine. This talk will focus on implications of these resemblances for future work.

Photochemistry and photooxidation of tetraphenyl-p-dioxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

George, M.V.; Kumar, C.V.; Scaiano, J.C.

1979-09-20

Laser flash photolysis studies of tetraphenyl-p-dioxin have led to the characterization of its triplet state. The T-T absorption spectra shows maxima at 350 and 545 nm; the triplet has a lifetime of 535 ns in methanol and can be quenched by di-tert-butyl nitroxide, paraquat dications, oxygen, and di-tert-butyl selenoketone. The interaction of the triplet with oxygen leads to the formation of singlet oxygen which in turn reacts with the title compound to yield benzil.

Di-tert-butyl-bis(N-isopropyl-N-methyl-dithio-carbamato-κS,S')tin(IV).

PubMed

Muthalib, Amirah Faizah; Baba, Ibrahim; Samsudin, Mohd Wahid; Ng, Seik Weng

2010-03-03

The dithio-carbamate anions in the title compound, [Sn(C(4)H(9))(2)(C(5)H(10)NS(2))(2)], chelate to the Sn(IV) atom, which is six-coordinated in a skew-trapezoidal-bipyramidal geometry. The mol-ecule lies across a twofold rotation axis. The crystal studied was a non-merohedral twin, the ratio of the twin components being 0.82 (1):0.18 (1).

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

PubMed Central

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

2011-01-01

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

Chronic carcinogenicity study of gasoline vapor condensate (GVC) and GVC containing methyl tertiary-butyl ether in F344 rats.

PubMed

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

2011-01-01

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

Synthesis of backbone P-functionalized imidazol-2-ylidene complexes: en route to novel functional ionic liquids.

PubMed

Majhi, Paresh Kumar; Sauerbrey, Susanne; Schnakenburg, Gregor; Arduengo, Anthony J; Streubel, Rainer

2012-10-01

1-Alkyl-3-methyl-4-diphenylphosphoryl-imidazolium hydrogensulfate (4a,b) (a: R(1) = R(2) = Me; b: R(1) = (i)Pr, R(2) = Me) and 1-alkyl-3-methyl-4,5-bis(diphenylphosphoryl)imidazolium hydrogensulfate (6a,c) (c: R(1) = (n)Bu, R(2) = Me) were obtained selectively and in good yields by oxidative desulfurization of 1-alkyl-3-methyl-4-diphenylphosphino-imidazole-2-thiones (2a,b) and 1-n-butyl-3-methyl-4,5-bis(diphenylphosphoryl)imidazole-2-thione (3c) or 1,3-dimethyl-4-diphenylthiophosphoryl-5-diphenylphosphino-imidazole-2-thione (5a), respectively, with hydrogen peroxide. Synthesis of phosphoryl functionalized imidazol-2-ylidene complexes of group VI metal pentacarbonyls (7a-9a) and (10b-12b) and bis(phosphoryl) functionalized imidazol-2-ylidene complexes of group VI metal pentacarbonyls (13c-15c) and (16a) with low steric demand (methyl, isopropyl, n-butyl) at both N-centers was achieved through deprotonation of imidazolium salts (4a,b) and (6a,c), respectively,-having HSO(4)(-) as a counterion-with potassium tert-butoxide followed by rapid addition of metal pentacarbonyl acetonitrile complexes [M(CO)(5)(CH(3)CN)] (M = Cr, Mo, W). The products were unambiguously characterized by elemental analyses, spectroscopic and spectrometric methods, and in addition, by single-crystal X-ray structure studies in the cases of 4b, 8a, 15c, and 16a; the latter two reveal imidazole ring bond distance alternation in contrast to 8a.

The reactivity of phosphagermaallene Tip(t-Bu)Ge=C=PMes* with doubly and triply bonded nitrogen compounds.

PubMed

Ghereg, Dumitru; Gornitzka, Heinz; Escudié, Jean; Ladeira, Sonia

2010-11-15

Phosphagermaallene Tip(t-Bu)Ge=C=PMes* (1; Mes* = 2,4,6-tri-tert-butylphenyl, Tip = 2,4,6-triisopropylphenyl) gives, with N-benzylidenemethylamine and pivalonitrile, [2+2] cycloadditions between the Ge=C double bond and the C=N and C≡N unsaturations, leading to the formation of the corresponding four-membered heterocycles 2 and 9. With N-tert-butyl-α-phenylnitrone and benzonitrile oxide, [2+3] cycloadditions occur to form the five-membered ring derivatives 6 and 7. By treatment of 1 with derivatives which possess weak acidic hydrogens in α of the C=N or C≡N multiple bond, two types of reactions were observed: an ene reaction with methyl(benzylideneamino)acetate and a 1,2 addition with acetonitrile to afford azadienyl(germyl)ether (4) and 3-germa-1-phosphapropene (8), respectively. In the case of benzonitrile, phosphagermaallene 1 behaves as a 1,3-dipole, to give, via a cyclic phosphagermacarbene intermediate, the tricyclic derivative 10.

40 CFR 180.411 - Fluazifop-P-butyl; tolerances for residues.

Code of Federal Regulations, 2010 CFR

2010-07-01

... residues of the herbicide, fluazifop-P-butyl, butyl(R)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy... of the herbicide, fluazifop-P-butyl, butyl(R)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy...

Continuous production of biodiesel under supercritical methyl acetate conditions: Experimental investigation and kinetic model.

PubMed

Farobie, Obie; Matsumura, Yukihiko

2017-10-01

In this study, biodiesel production by using supercritical methyl acetate in a continuous flow reactor was investigated for the first time. The aim of this study was to elucidate the reaction kinetics of biodiesel production by using supercritical methyl. Experiments were conducted at various reaction temperatures (300-400°C), residence times (5-30min), oil-to-methyl acetate molar ratio of 1:40, and a fixed pressure of 20MPa. Reaction kinetics of biodiesel production with supercritical methyl acetate was determined. Finally, biodiesel yield obtained from this method was compared to that obtained with supercritical methanol, ethanol, and MTBE (methyl tertiary-butyl ether). The results showed that biodiesel yield with supercritical methyl acetate increased with temperature and time. The developed kinetic model was found to fit the experimental data well. The reactivity of supercritical methyl acetate was the lowest, followed by that of supercritical MTBE, ethanol, and methanol, under the same conditions. Copyright © 2017. Published by Elsevier Ltd.

Mobil cuts the alcohol out of oxygenate production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, A.

1992-04-15

Mobil Corp. has unveiled a new etherification technology that can produce fuel oxygenated based only on olefinic refinery streams and water. The process has the potential to allow refiners to produce oxygenates without having to rely on an external supply of alcohols such as methanol or ethanol. Mobil has developed the technology around a new oxygenate, disopropyl ether (DIPE), based on propylene. However, the process has also been tested using mixed propylene/C{sub 4} and straight C{sub 4} streams, says Michael J. McNally, manager of Mobil`s Motor Gasoline Group (Paulsboro, NJ), producing ethers analogous to methyl tert-butyl ether (MTBE).

Determination of erythromycin in human plasma, using column liquid chromatography with a polymeric packing material, alkaline mobile phase and amperometric detection.

PubMed

Nilsson, L G; Walldorf, B; Paulsen, O

1987-12-25

A method based on column liquid chromatography was developed for determination of plasma concentrations of erythromycin. PRP-1, a polymeric type of packing material suitable for chromatography and amperometric detection at high pH, was used. The effect of pH on the column performance and on the electrochemical response was studied. A pH of ca. 10 was found to be optimal. After extraction with tert.-butyl methyl ether, plasma concentrations down to 0.2 mumol/l could be measured, using automated sample injection. Oleandomycin was used as internal standard. The method was used for determination of plasma concentrations in a pharmacokinetic study under steady-state conditions.

Removal of some organic pollutants in water employing ceramic membranes impregnated with cross-linked silylated dendritic and cyclodextrin polymers.

PubMed

Allabashi, Roza; Arkas, Michael; Hörmann, Gerold; Tsiourvas, Dimitris

2007-01-01

Triethoxysilylated derivatives of poly(propylene imine) dendrimer, polyethylene imine and polyglycerol hyperbranched polymers and beta-cyclodextrin have been synthesized and characterized. These compounds impregnated ceramic membranes made from Al(2)O(3), SiC and TiO(2) and subsequently sol-gel reaction led to their polymerization and chemical bond formation with the ceramic substrates. The resulting organic-inorganic filters were tested for the removal of a variety of organic pollutants from water. They were found to remove of polycyclic aromatic hydrocarbons (up to 99%), of monocyclic aromatic hydrocarbons (up to 93%), trihalogen methanes (up to 81%), pesticides (up to 43%) and methyl-tert-butyl ether (up to 46%).

Asymmetric epoxidation of unsaturated ketones catalyzed by heterobimetallic rare earth-lithium complexes bearing phenoxy-functionalized chiral diphenylprolinolate ligand.

PubMed

Qian, Qinqin; Tan, Yufang; Zhao, Bei; Feng, Tao; Shen, Qi; Yao, Yingming

2014-09-05

Four novel heterobimetallic complexes [REL2]{[(THF)3Li]2(μ-Cl)} stabilized by chiral phenoxy-functionalized prolinolate (RE = Yb (1), Y (2), Sm (3), Nd (4), H2L = (S)-2,4-di-tert-butyl-6-[[2-(hydroxydiphenylmethyl)pyrrolidin-1-yl]methyl]phenol have been synthesized and characterized. These readily available complexes are highly active in catalyzing the epoxidation of α,β-unsaturated ketones, while the enantioselectivity varies according to the ionic radii of the rare earth center. A series of chalcone derivatives were converted to chiral epoxides in 80 → 99% ee at 0 °C using TBHP as the oxidant in the presence of 10 mol % of 1.

40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Chlorohydroxyalkyl butyl ether... Specific Chemical Substances § 721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance... chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to reporting under this section for the significant new use...

40 CFR 721.3438 - Chlorohydroxyalkyl butyl ether (generic).

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Chlorohydroxyalkyl butyl ether... Specific Chemical Substances § 721.3438 Chlorohydroxyalkyl butyl ether (generic). (a) Chemical substance... chlorohydroxyalkyl butyl ether (PMN P-99-1295) is subject to reporting under this section for the significant new use...

Quantitative assessment of hTERT mRNA expression in dysplastic nodules of HBV-related hepatocarcinogenesis.

PubMed

Oh, Bong-Kyeong; Kim, Young-Joo; Park, Young Nyun; Choi, Jinsub; Kim, Kyung Sik; Park, Chanil

2006-04-01

Telomerase reverse transcriptase (hTERT) is the rate-limiting determinant of telomerase, which is critical for carcinogenesis. Dysplastic nodules (DNs) appear to be preneoplastic lesions of hepatocellular carcinomas (HCCs). In this study, in order to characterize DNs, hTERT mRNA, hTERT gene dosage, and mRNA for c-myc, a transcriptional activator of hTERT were studied in human multi-step hepatocarcinogenesis. Fifty four hepatic nodules including 5 large regenerative nodules, 14 low-grade DNs, 7 high-grade DNs, 11 DNs with HCC foci and 17 HCCs, 23 livers with chronic hepatitis/cirrhosis, and 6 normal livers were examined. Transcript levels were measured by real-time quantitative RT-PCR and gene dosages by real-time PCR and Southern blotting. The hTERT mRNA levels increased with the progression of hepatocarcinogenesis, and a significant induction in the transition between low- and high-grade DNs was seen. Most high-grade DNs strongly expressed hTERT mRNA at levels similar to those of HCCs. Twenty-one percent of low-grade DNs had high levels of hTERT mRNA, up to those of high-grade DNs and there was no difference in the pathological features between low-grade DNs with and without increased hTERT mRNA levels. No correlation was found between hTERT mRNA levels, hTERT gene dosage, and c-myc mRNA levels. These results suggest that the induction of hTERT mRNA is an important early event and that its measurement by real-time quantitative RT-PCR is a useful tool to detect premalignant/malignant tendencies in hepatic nodules. However, hTERT gene dosage and c-myc expression are not the main mechanisms regulating hTERT expression in hepatocarcinogenesis.

46 CFR 30.25-1 - Cargoes carried in vessels certificated under the rules of this subchapter.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Amyl methyl ketone, see Methyl amyl ketone D Animal and Fish oils, n.o.s. D (see also Oil, edible, or...-Butyl formate D n-Butyl formate @D Butyl heptyl ketone [C] Butyl methyl ketone, see Methyl butyl ketone... Diisobutyl ketone D Diisobutyl phthalate B Diisodecyl phthalate, see Dialkyl(C7-C13) phthalates Diisononyl...

46 CFR 30.25-1 - Cargoes carried in vessels certificated under the rules of this subchapter.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Amyl methyl ketone, see Methyl amyl ketone D Animal and Fish oils, n.o.s. D (see also Oil, edible, or...-Butyl formate D n-Butyl formate @D Butyl heptyl ketone [C] Butyl methyl ketone, see Methyl butyl ketone... Diisobutyl ketone D Diisobutyl phthalate B Diisodecyl phthalate, see Dialkyl(C7-C13) phthalates Diisononyl...

46 CFR 30.25-1 - Cargoes carried in vessels certificated under the rules of this subchapter.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Amyl methyl ketone, see Methyl amyl ketone D Animal and Fish oils, n.o.s. D (see also Oil, edible, or...-Butyl formate D n-Butyl formate @D Butyl heptyl ketone [C] Butyl methyl ketone, see Methyl butyl ketone... Diisobutyl ketone D Diisobutyl phthalate B Diisodecyl phthalate, see Dialkyl(C7-C13) phthalates Diisononyl...

46 CFR 30.25-1 - Cargoes carried in vessels certificated under the rules of this subchapter.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Amyl methyl ketone, see Methyl amyl ketone D Animal and Fish oils, n.o.s. D (see also Oil, edible, or...-Butyl formate D n-Butyl formate @D Butyl heptyl ketone [C] Butyl methyl ketone, see Methyl butyl ketone... Diisobutyl ketone D Diisobutyl phthalate B Diisodecyl phthalate, see Dialkyl(C7-C13) phthalates Diisononyl...

Isolation of tert-alkylphenols from the products of alkylation of phenols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nesterova, T.N.; Verevkin, S.P.; Rempel', R.D.

1987-08-10

The authors studied the conditions of isolation of tert-amyl-, hexyl-, heptyl-, octyl-, decyl-, and dodecylphenols, and tert-alkylcresols, alkylpyrocatechols, and alkylhydroquinones from alkylation products. The compounds were isolated in all cases from reaction mixtures obtained in presence of cation-exchange resins of the KU-2 type. A preliminary stage, flash evaporation of the reaction mass at 4-13 Pa for 5-15 min, is needed to prevent decomposition of tert-alkylphenols during their isolation from acid reaction mixtures by fractionation. Flash distillation of high-boiling tert-alkylphenols should be conducted in presence of a component lowering the boiling point of the mixture, added in 1:(0.5-1.0) weight ratio ofmore » original mixture to the component.« less

Novel types of tetra-, hexa-, octa-, and dodecanuclear silver clusters containing (2,7-Di-tert-butylfluoren-9-ylidene)methanedithiolate.

PubMed

Vicente, José; González-Herrero, Pablo; García-Sánchez, Yolanda; Jones, Peter G

2009-03-02

The reaction of AgClO(4) with piperidinium 2,7-di-tert-butyl-9H-fluorene-9-carbodithioate (pipH)[S(2)C(t-Bu-Hfy)] (1) (t-Bu-Hfy = 2,7-di-tert-butylfluoren-9-yl) afforded [Ag(n){S(2)C(t-Bu-Hfy)}(n)] (2), which reacted with phosphines to give [Ag{S(2)C(t-Bu-Hfy)}L(2)] [L = PPh(3) (3a); L(2) = bis(diphenylphosphino)ethane (dppe, 3b), 1,1'-bis(diphenylphosphino)ferrocene (dppf, 3c). By reacting complex 2 with AgClO(4) and piperidine in a 1:1:1 molar ratio, the dodecanuclear cluster [Ag(12){S(2)C(t-Bu-fy)}(6)] (4) (t-Bu-fy = 2,7-di-tert-butylfluoren-9-ylidene) was obtained. Compound 4 can also be directly prepared from the reaction of 1 with AgClO(4) and piperidine in a 1:2:1 molar ratio. The reactions of 1 with AgClO(4), phosphines, and piperidine afforded the compounds [Ag(6){S(2)C(t-Bu-fy)}(3)L(5)] [1:2:2:1 molar ratio; L = PPh(3) (5a), P(p-To)(3) (5b)], [Ag(4){S(2)C(t-Bu-fy)}(2)(dppf)(2)] (6) (1:2:1:1 molar ratio), [Ag(n){S(2)C(t-Bu-fy)}(n/2){P(i-Pr)(3)}(n)] (7) (1:2:2:1 molar ratio), or [Ag(8){S(2)C(t-Bu-fy)}(4){P(i-Pr)(3)}(4)] (8) (1:2:1:1 molar ratio). Complexes 5a,b, 6, 7, and 8 can be also obtained by reacting 4 with the corresponding phosphine in the appropriate molar ratio. The crystal structures of 4, 5b, and 8 have been determined by X-ray diffraction studies. The nuclearity of complex 6 was established from its (31)P{(1)H} NMR data, which reveal a very fast dynamic process leading to an average coupling of each of the P atoms of the dppf ligands with four Ag atoms.

Biomimetic Oxidation Studies. 11. Alkane Functionalization in Aqueous Solution Utilizing in Situ Formed [Fe(2)O(eta(1)-H(2)O)(eta(1)-OAc)(TPA)(2)](3+), as an MMO Model Precatalyst, Embedded in Surface-Derivatized Silica and Contained in Micelles.

PubMed

Neimann, Karine; Neumann, Ronny; Rabion, Alain; Buchanan, Robert M.; Fish, Richard H.

1999-07-26

The biomimetic, methane monooxygenase enzyme (MMO) precatalyst, [Fe(2)O(eta(1)-H(2)O)(eta(1)-OAc)(TPA)(2)](3+) (TPA = tris[(2-pyridyl)methyl]amine), 1, formed in situ at pH 4.2 from [Fe(2)O(&mgr;-OAc)(TPA)(2)](3+), 2, was embedded in an amorphous silicate surface modified by a combination of hydrophilic poly(ethylene oxide) and hydrophobic poly(propylene oxide). The resulting catalytic assembly was found to be a biomimetic model for the MMO active site within a hydrophobic macroenvironment, allowing alkane functionalization with tert-butyl hydroperoxide (TBHP)/O(2) in an aqueous reaction medium (pH 4.2). For example, cyclohexane was oxidized to a mixture of cyclohexanone, cyclohexanol, and cyclohexyl-tert-butyl peroxide, in a ratio of approximately 3:1:2. The balance between poly(ethylene oxide) and poly(propylene oxide), tethered on the silica surface, was crucial for maximizing the catalytic activity. The silica-based catalytic assembly showed reactivity somewhat higher in comparison to an aqueous micelle system utilizing the surfactant, cetyltrimethylammonium hydrogen sulfate at its critical micelle concentration, in which functionalization of cyclohexane with TBHP/O(2) in the presence of 1 was also studied at pH 4.2 and was found to provide similar products: cyclohexanol, cyclohexanone, and cyclohexyl-tert-butyl peroxide, in a ratio of approximately 2:3:1. Moreover, the mechanism for both the silica-based catalytic assembly and the aqueous micelle system was found to occur via the Haber-Weiss process, in which redox chemistry between 1 and TBHP provides both the t-BuO(*)() and t-BuOO(*)()( )()radicals. The t-BuO(*)()( )()radical initiates the C-H functionalization reaction to form the carbon radical, followed by O(2) trapping, to provide cyclohexyl hydroperoxide, which produces the cyclohexanol and cyclohexanone in the presence of 1, whereas the coupling product emanates from t-BuOO(*)() and cyclohexyl radicals. A discussion concerning both approaches for

Excitotoxic and Radiation Stress Increase TERT Levels in the Mitochondria and Cytosol of Cerebellar Purkinje Neurons.

PubMed

Eitan, Erez; Braverman, Carmel; Tichon, Ailone; Gitler, Daniel; Hutchison, Emmette R; Mattson, Mark P; Priel, Esther

2016-08-01

Telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase, an enzyme that elongates telomeres at the ends of chromosomes during DNA replication. Recently, it was shown that TERT has additional roles in cell survival, mitochondrial function, DNA repair, and Wnt signaling, all of which are unrelated to telomeres. Here, we demonstrate that TERT is enriched in Purkinje neurons, but not in the granule cells of the adult mouse cerebellum. TERT immunoreactivity in Purkinje neurons is present in the nucleus, mitochondria, and cytoplasm. Furthermore, TERT co-localizes with mitochondrial markers, and immunoblot analysis of protein extracts from isolated mitochondria and synaptosomes confirmed TERT localization in mitochondria. TERT expression in Purkinje neurons increased significantly in response to two stressors: a sub-lethal dose of X-ray radiation and exposure to a high glutamate concentration. While X-ray radiation increased TERT levels in the nucleus, glutamate exposure elevated TERT levels in mitochondria. Our findings suggest that in mature Purkinje neurons, TERT is present both in the nucleus and in mitochondria, where it may participate in adaptive responses of the neurons to excitotoxic and radiation stress.

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

PubMed

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

2007-10-01

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

Laboratory evidence of MTBE biodegradation in Borden aquifer material

NASA Astrophysics Data System (ADS)

Schirmer, Mario; Butler, Barbara J.; Church, Clinton D.; Barker, James F.; Nadarajah, Nalina

2003-02-01

Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.

21 CFR 520.260 - n-Butyl chloride capsules.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false n-Butyl chloride capsules. 520.260 Section 520.260... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.260 n-Butyl chloride capsules. (a)(1) Specifications. n-Butyl chloride capsules, veterinary contain 272 milligrams or 816 milligrams...

Absence of TERT promoter mutations in colorectal precursor lesions and cancer

PubMed Central

Cruvinel-Carloni, Adriana; Yamane, Letícia; Scapulatempo-Neto, Cristovam; Guimarães, Denise; Reis, Rui Manuel

2018-01-01

Abstract Hotspot mutations (c.-124bp G > A and c.-146bp G > A) in the promoter region of the TERT gene have been recently described in several types of solid tumors, including glioma, bladder, thyroid, liver and skin neoplasms. However, knowledge with respect to colorectal precursor lesions and cancer is scarce. In the present study we aimed to determine the frequency of hotspot TERT promoter mutations in 145 Brazilian patients, including 103 subjects with precursor lesions and 42 with colorectal carcinomas, and we associated the presence of such mutations with the patients clinical-pathological features. The mutation analysis was conclusive in 123 cases, and none of the precursor and colorectal carcinoma cases showed TERT promoter mutations. We conclude that TERT mutations are not a driving factor in colorectal carcinogenesis. PMID:29473934

An X-ray crystallographic and density functional theory study of (3Z)-4-(5-ethylsulfonyl-2-hydroxyanilino)pent-3-en-2-one and (3Z)-4-(5-tert-butyl-2-hydroxyanilino)pent-3-en-2-one.

PubMed

Akerman, Kate J; Munro, Orde Q

2013-03-01

The Schiff base enaminones (3Z)-4-(5-ethylsulfonyl-2-hydroxyanilino)pent-3-en-2-one, C13H17NO4S, (I), and (3Z)-4-(5-tert-butyl-2-hydroxyanilino)pent-3-en-2-one, C15H21NO2, (II), were studied by X-ray crystallography and density functional theory (DFT). Although the keto tautomer of these compounds is dominant, the O=C-C=C-N bond lengths are consistent with some electron delocalization and partial enol character. Both (I) and (II) are nonplanar, with the amino-phenol group canted relative to the rest of the molecule; the twist about the N(enamine)-C(aryl) bond leads to dihedral angles of 40.5 (2) and -116.7 (1)° for (I) and (II), respectively. Compound (I) has a bifurcated intramolecular hydrogen bond between the N-H group and the flanking carbonyl and hydroxy O atoms, as well as an intermolecular hydrogen bond, leading to an infinite one-dimensional hydrogen-bonded chain. Compound (II) has one intramolecular hydrogen bond and one intermolecular C=O...H-O hydrogen bond, and consequently also forms a one-dimensional hydrogen-bonded chain. The DFT-calculated structures [in vacuo, B3LYP/6-311G(d,p) level] for the keto tautomers compare favourably with the X-ray crystal structures of (I) and (II), confirming the dominance of the keto tautomer. The simulations indicate that the keto tautomers are 20.55 and 18.86 kJ mol(-1) lower in energy than the enol tautomers for (I) and (II), respectively.