15 results on '"chloromethane"'
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2. The biogeochemical cycling of chlorine.
- Author
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Barnum TP and Coates JD
- Subjects
- Atmosphere chemistry, Earth, Planet, Geology, Chlorides, Chlorine
- Abstract
Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from -1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth., (© 2022 John Wiley & Sons Ltd.)
- Published
- 2022
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3. Highly Selective Carbonylation of CH 3 Cl to Acetic Acid Catalyzed by Pyridine-Treated MOR Zeolite.
- Author
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Fang X, Wen F, Ding X, Liu H, Chen Z, Liu Z, Liu H, Zhu W, and Liu Z
- Abstract
The selective conversion of methane to high value-added chemicals under mild conditions is of great significance for the commercially viable and sustainable utilization of methane but remains a formidable challenge. Herein, we report a strategy for efficiently converting methane to acetic acid via CH
3 Cl as an intermediate. Up to 99.3 % acetic acid and methyl acetate (AA+MA) selectivity was achieved over pyridine-pretreated MOR (MOR-8) under moderate conditions of 523 K and 2.0 MPa. Water, conventionally detrimental to carbonylation reaction over zeolite catalysts, was conducive to the production of AA in the current reaction system. In the 100 h continuous test with the MOR-8 catalyst, the average AA+MA selectivity remained over 98 %. AA was formed by carbonylation of methoxy groups within 8-membered rings of MOR followed by hydrolysis. This strategy provided an approach for highly efficient utilization of methane to oxygenates under mild reaction conditions., (© 2022 Wiley-VCH GmbH.)- Published
- 2022
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4. A putatively new family of alphaproteobacterial chloromethane degraders from a deciduous forest soil revealed by stable isotope probing and metagenomics.
- Author
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Kröber E, Kanukollu S, Wende S, Bringel F, and Kolb S
- Abstract
Background: Chloromethane (CH
3 Cl) is the most abundant halogenated organic compound in the atmosphere and substantially responsible for the destruction of the stratospheric ozone layer. Since anthropogenic CH3 Cl sources have become negligible with the application of the Montreal Protocol (1987), natural sources, such as vegetation and soils, have increased proportionally in the global budget. CH3 Cl-degrading methylotrophs occurring in soils might be an important and overlooked sink., Results and Conclusions: The objective of our study was to link the biotic CH3 Cl sink with the identity of active microorganisms and their biochemical pathways for CH3 Cl degradation in a deciduous forest soil. When tested in laboratory microcosms, biological CH3 Cl consumption occurred in leaf litter, senescent leaves, and organic and mineral soil horizons. Highest consumption rates, around 2 mmol CH3 Cl g-1 dry weight h-1 , were measured in organic soil and senescent leaves, suggesting that top soil layers are active (micro-)biological CH3 Cl degradation compartments of forest ecosystems. The DNA of these [13 C]-CH3 Cl-degrading microbial communities was labelled using stable isotope probing (SIP), and the corresponding taxa and their metabolic pathways studied using high-throughput metagenomics sequencing analysis. [13 C]-labelled Metagenome-Assembled Genome closely related to the family Beijerinckiaceae may represent a new methylotroph family of Alphaproteobacteria, which is found in metagenome databases of forest soils samples worldwide. Gene markers of the only known pathway for aerobic CH3 Cl degradation, via the methyltransferase system encoded by the CH3 Cl utilisation genes (cmu), were undetected in the DNA-SIP metagenome data, suggesting that biological CH3 Cl sink in this deciduous forest soil operates by a cmu-independent metabolism., (© 2022. The Author(s).)- Published
- 2022
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5. Highly Enhanced Aromatics Selectivity by Coupling of Chloromethane and Carbon Monoxide over H-ZSM-5.
- Author
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Fang X, Liu H, Chen Z, Liu Z, Ding X, Ni Y, Zhu W, and Liu Z
- Abstract
The transformation of methane into high value-added chemicals such as aromatics provides a more desired approach towards sustainable chemistry but remains a critical challenge due to the low selectivity of aromatics and poor stability. Herein, we first report a coupling reaction of CH
3 Cl and CO (CCTA) based on methane conversion, which achieves extremely high aromatics selectivity (82.2 %) with the selectivity of BTX up to ca. 60 % over HZSM-5. The promoting effects have been demonstrated on other zeolites especially 10-membered rings (10 MR) zeolites. Multiple characterizations show that 2,3-dimethyl-2-cyclopentene-1-one (DMCPO) is generated from acetyl groups and olefins. Furthermore, isotopic labeling analysis confirms that CO is inserted into the DMCPO and aromatics rings. A new aromatization mechanism is proposed, including the formation of the above intermediates, which conspicuously weakens the hydrogen transfer reaction, leading to a considerable increase of aromatics selectivity and a dramatic drop in alkanes., (© 2022 Wiley-VCH GmbH.)- Published
- 2022
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6. Evaluation of developmental toxicity of Methyl Chloride (Chloromethane) in rats, mice, and rabbits.
- Author
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Arts J, Kellert M, Pottenger L, and Theuns-van Vliet J
- Subjects
- Animals, Mice, Rabbits, Rats, Toxicity Tests, Heart drug effects, Methyl Chloride toxicity
- Abstract
Methyl Chloride (MeCl; Chloromethane) is a high production volume chemical (>1000 t/a) and is used as an industrial solvent. Based on cardiac lesions reported in developmental toxicity studies in mice, but not in rats, manufacturers decided to classify MeCl as a developmental toxicant, cat. 2. Recently, the European Chemical Agency required a developmental toxicity study in a non-rodent species. No developmental toxicity was observed in rabbits in the recently completed, GLP, OECD 414 guideline study. In view of the absence of cardiac effects in rats and rabbits, the purpose of this review is to consider whether the cardiac effects reported in mice should be considered real effects and, if so, their potential for relevance to humans. This paper provides substantive new evidence with data from a third species and shows that an evaluation of the integrated scientific evidence indicates the reported developmental cardiac effects in mice, if not an artifact, are unlikely to be relevant to humans. As such the classification of MeCl for developmental toxicity was reconsidered., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2019
- Full Text
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7. Chloromethane formation and degradation in the fern phyllosphere.
- Author
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Jaeger N, Besaury L, Röhling AN, Koch F, Delort AM, Gasc C, Greule M, Kolb S, Nadalig T, Peyret P, Vuilleumier S, Amato P, Bringel F, and Keppler F
- Abstract
Chloromethane (CH
3 Cl) is the most abundant halogenated trace gas in the atmosphere. It plays an important role in natural stratospheric ozone destruction. Current estimates of the global CH3 Cl budget are approximate. The strength of the CH3 Cl global sink by microbial degradation in soils and plants is under discussion. Some plants, particularly ferns, have been identified as substantial emitters of CH3 Cl. Their ability to degrade CH3 Cl remains uncertain. In this study, we investigated the potential of leaves from 3 abundant ferns (Osmunda regalis, Cyathea cooperi, Dryopteris filix-mas) to produce and degrade CH3 Cl by measuring their production and consumption rates and their stable carbon and hydrogen isotope signatures. Investigated ferns are able to degrade CH3 Cl at rates from 2.1 to 17 and 0.3 to 0.9μggdw -1 day- 1 for C. cooperi and D. filix-mas respectively, depending on CH3 Cl supplementation and temperature. The stable carbon isotope enrichment factor of remaining CH3 Cl was -39±13‰, whereas negligible isotope fractionation was observed for hydrogen (-8±19‰). In contrast, O. regalis did not consume CH3 , with stable isotope values of -97±8‰ for carbon and -202±10‰ for hydrogen, respectively. Even though the 3 ferns showed clearly different formation and consumption patterns, their leaf-associated bacterial diversity was not notably different. Moreover, we did not detect genes associated with the only known chloromethane utilization pathway "cmu" in the microbial phyllosphere of the investigated ferns. Our study suggests that still unknown CHdw -1 day- 1 , with stable isotope values of -97±8‰ for carbon and -202±10‰ for hydrogen, respectively. Even though the 3 ferns showed clearly different formation and consumption patterns, their leaf-associated bacterial diversity was not notably different. Moreover, we did not detect genes associated with the only known chloromethane utilization pathway "cmu" in the microbial phyllosphere of the investigated ferns. Our study suggests that still unknown CH3 Cl biodegradation processes on plants play an important role in global cycling of atmospheric CH3 Cl., (Copyright © 2018 Elsevier B.V. All rights reserved.)- Published
- 2018
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8. Empirical data in support of a skin notation for methyl chloride.
- Author
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Gaskin S, Thredgold L, Heath L, Pisaniello D, Logan M, and Baxter C
- Subjects
- Hazardous Substances pharmacokinetics, Humans, In Vitro Techniques, Risk Assessment, Methyl Chloride pharmacokinetics, Skin Absorption physiology
- Abstract
This article presents the first empirical experimental data on the skin absorption of methyl chloride gas using an in vitro technique and human skin. Methyl chloride is a commonly used industrial agent that is known to be an inhalational hazard but is also reported to be absorbed through human skin in amounts that contribute substantially to systemic intoxication. As a result, is has been assigned a skin notation by the ACGIH. Other than predictive models, there is a general paucity of experimental data on the skin absorption of methyl chloride and therefore a distinct lack of empirical evidence in the open literature to support the assignment of a skin notation for this chemical. This study found that methyl chloride permeates through human epidermis when exposed at high atmospheric concentrations within relatively short timeframes. Therefore, providing important initial empirical evidence in support of the assignment of a skin notation.
- Published
- 2018
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9. Genomic and Transcriptomic Analysis of Growth-Supporting Dehalogenation of Chlorinated Methanes in Methylobacterium .
- Author
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Chaignaud P, Maucourt B, Weiman M, Alberti A, Kolb S, Cruveiller S, Vuilleumier S, and Bringel F
- Abstract
Bacterial adaptation to growth with toxic halogenated chemicals was explored in the context of methylotrophic metabolism of Methylobacterium extorquens , by comparing strains CM4 and DM4, which show robust growth with chloromethane and dichloromethane, respectively. Dehalogenation of chlorinated methanes initiates growth-supporting degradation, with intracellular release of protons and chloride ions in both cases. The core, variable and strain-specific genomes of strains CM4 and DM4 were defined by comparison with genomes of non-dechlorinating strains. In terms of gene content, adaptation toward dehalogenation appears limited, strains CM4 and DM4 sharing between 75 and 85% of their genome with other strains of M. extorquens . Transcript abundance in cultures of strain CM4 grown with chloromethane and of strain DM4 grown with dichloromethane was compared to growth with methanol as a reference C
1 growth substrate. Previously identified strain-specific dehalogenase-encoding genes were the most transcribed with chlorinated methanes, alongside other genes encoded by genomic islands (GEIs) and plasmids involved in growth with chlorinated compounds as carbon and energy source. None of the 163 genes shared by strains CM4 and DM4 but not by other strains of M. extorquens showed higher transcript abundance in cells grown with chlorinated methanes. Among the several thousand genes of the M. extorquens core genome, 12 genes were only differentially abundant in either strain CM4 or strain DM4. Of these, 2 genes of known function were detected, for the membrane-bound proton translocating pyrophosphatase HppA and the housekeeping molecular chaperone protein DegP. This indicates that the adaptive response common to chloromethane and dichloromethane is limited at the transcriptional level, and involves aspects of the general stress response as well as of a dehalogenation-specific response to intracellular hydrochloric acid production. Core genes only differentially abundant in either strain CM4 or strain DM4 total 13 and 58 CDS, respectively. Taken together, the obtained results suggest different transcriptional responses of chloromethane- and dichloromethane-degrading M. extorquens strains to dehalogenative metabolism, and substrate- and pathway-specific modes of growth optimization with chlorinated methanes.- Published
- 2017
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10. Transfer of a Catabolic Pathway for Chloromethane in Methylobacterium Strains Highlights Different Limitations for Growth with Chloromethane or with Dichloromethane.
- Author
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Michener JK, Vuilleumier S, Bringel F, and Marx CJ
- Abstract
Chloromethane (CM) is an ozone-depleting gas, produced predominantly from natural sources, that provides an important carbon source for microbes capable of consuming it. CM catabolism has been difficult to study owing to the challenging genetics of its native microbial hosts. Since the pathways for CM catabolism show evidence of horizontal gene transfer, we reproduced this transfer process in the laboratory to generate new CM-catabolizing strains in tractable hosts. We demonstrate that six putative accessory genes improve CM catabolism, though heterologous expression of only one of the six is strictly necessary for growth on CM. In contrast to growth of Methylobacterium strains with the closely related compound dichloromethane (DCM), we find that chloride export does not limit growth on CM and, in general that the ability of a strain to grow on DCM is uncorrelated with its ability to grow on CM. This heterologous expression system allows us to investigate the components required for effective CM catabolism and the factors that limit effective catabolism after horizontal transfer.
- Published
- 2016
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11. Methyl chloride and methyl bromide emissions from baking: an unrecognized anthropogenic source.
- Author
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Thornton BF, Horst A, Carrizo D, and Holmstrand H
- Abstract
Methyl chloride and methyl bromide (CH3Cl and CH3Br) are the largest natural sources of chlorine and bromine, respectively, to the stratosphere, where they contribute to ozone depletion. We report the anthropogenic production of CH3Cl and CH3Br during breadbaking, and suggest this production is an abiotic process involving the methyl ester functional groups in pectin and lignin structural polymers of plant cells. Wide variations in baking styles allow only rough estimates of this flux of methyl halides on a global basis. A simple model suggests that CH3Br emissions from breadbaking likely peaked circa 1990 at approximately 200tonnes per year (about 0.3% of industrial production), prior to restrictions on the dough conditioner potassium bromate. In contrast, CH3Cl emissions from breadbaking may be of similar magnitude as acknowledged present-day CH3Cl industrial emissions. Because the mechanisms involve functional groups and compounds widely found in plant materials, this type of methyl halide production may occur in other cooking techniques as well., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2016
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12. Probing the diversity of chloromethane-degrading bacteria by comparative genomics and isotopic fractionation.
- Author
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Nadalig T, Greule M, Bringel F, Keppler F, and Vuilleumier S
- Abstract
Chloromethane (CH3Cl) is produced on earth by a variety of abiotic and biological processes. It is the most important halogenated trace gas in the atmosphere, where it contributes to ozone destruction. Current estimates of the global CH3Cl budget are uncertain and suggest that microorganisms might play a more important role in degrading atmospheric CH3Cl than previously thought. Its degradation by bacteria has been demonstrated in marine, terrestrial, and phyllospheric environments. Improving our knowledge of these degradation processes and their magnitude is thus highly relevant for a better understanding of the global budget of CH3Cl. The cmu pathway, for chloromethane utilisation, is the only microbial pathway for CH3Cl degradation elucidated so far, and was characterized in detail in aerobic methylotrophic Alphaproteobacteria. Here, we reveal the potential of using a two-pronged approach involving a combination of comparative genomics and isotopic fractionation during CH3Cl degradation to newly address the question of the diversity of chloromethane-degrading bacteria in the environment. Analysis of available bacterial genome sequences reveals that several bacteria not yet known to degrade CH3Cl contain part or all of the complement of cmu genes required for CH3Cl degradation. These organisms, unlike bacteria shown to grow with CH3Cl using the cmu pathway, are obligate anaerobes. On the other hand, analysis of the complete genome of the chloromethane-degrading bacterium Leisingera methylohalidivorans MB2 showed that this bacterium does not contain cmu genes. Isotope fractionation experiments with L. methylohalidivorans MB2 suggest that the unknown pathway used by this bacterium for growth with CH3Cl can be differentiated from the cmu pathway. This result opens the prospect that contributions from bacteria with the cmu and Leisingera-type pathways to the atmospheric CH3Cl budget may be teased apart in the future.
- Published
- 2014
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13. Mechanistic aspects of the nucleophilic substitution of pectin. On the formation of chloromethane.
- Author
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Sailaukhanuly Y, Sárossy Z, Carlsen L, and Egsgaard H
- Subjects
- Biomass, Chlorine chemistry, Ions chemistry, Temperature, Chlorides chemistry, Methyl Chloride chemistry, Pectins chemistry
- Abstract
Chloromethane, accounting for approximately 16% of the tropospheric chlorine, is mainly coming from natural sources. However anthropogenic activities, such as combustion of biomass may contribute significantly as well. The present study focuses on the thermal solid state reaction between pectin, an important constituent of biomass, and chloride ions as found in alkali metal chlorides. The formation of chloromethane is evident with the amount formed being linear with respect to chloride if pectin is in great excess. Thus the reaction is explained as a pseudo first order SN2 reaction between the chloride ion and the methyl ester moiety in pectin. It is suggested that the polymeric nature of pectin plays an active role by an enhanced transport of halides along the carbohydrate chain. Optimal reaction temperature is around 210°C. At higher temperatures the yield of chloromethane decreases due to a thermal decomposition of the pectin. The possible influence of the type of cation is discussed., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2014
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14. Adjustment factors for toluene, styrene and methyl chloride by population modeling of toxicokinetic variability.
- Author
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Mörk AK, Jonsson F, and Johanson G
- Subjects
- Adolescent, Adult, Child, Child, Preschool, Dose-Response Relationship, Drug, Female, Humans, Infant, Male, Monte Carlo Method, Occupational Exposure analysis, Risk Assessment, Solvents toxicity, Toxicokinetics, Ventilation, Workplace, Methyl Chloride toxicity, Styrene toxicity, Toluene toxicity
- Abstract
The availability of experimental data suitable as a basis to quantify human variability in response to chemical exposure has increased in recent years. It has enabled scientifically based, data driven adjustment factors (AF) to be deployed in the risk assessment process. As part of this development, we derive AF for human toxicokinetic variability (HK) for three lipophilic organic solvents; toluene, styrene and methyl chloride using physiologically based pharmacokinetic (PBPK) models in a population framework. The Monte Carlo simulations cover the influence of age and gender on toxicokinetic variability in the general population, as well as workplace ventilation rates and fluctuations in exposure level and workload in adult male and female workers. The derived AFHK are below 2.2 (95th percentile) for all subpopulations, exposure scenarios and chemicals, except for markers of acute effects in workers, where the factors are up to 5.0., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
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15. Comparative studies of the toxicity and pharmacodynamic action of chlorinated methanes with special reference to their physical and chemical characteristics.
- Author
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VON OETTINGEN WF and POWELL CC
- Subjects
- Halogenation, Methane, Methyl Chloride, Physical Examination
- Published
- 1950
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