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Sample records for alkane conversion chemistry

  1. Light alkane conversion

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1991-07-09

    This patent describes a process for the aromatization of an aliphatic feedstream. It comprises fluidizing finely divided solid particles in a combustion zone; charging oxygen-containing combustion gas and fuel to the combustion zone under combustion conditions; withdrawing a stream of finely divided particles from the combustion zone; flowing the withdrawn stream of finely divided particles above to a cracking/dehydrogenation zone; fluidizing the finely divided particles above in an aliphatic feedstream under conditions within the cracking/dehydrogenation zone controlled to at least partially crack and at least partially dehydrogenate the aliphatic feedstream to form an intermediate product stream containing a quantity of C{sub 4}-olefins such that the exothermic catalytic conversion of the C{sub 4}-olefins is sufficient to supply a portion of the endothermic heat of reaction for the endothermic catalytic conversion of paraffins contained in the intermediate feedstream to aromatics; contacting the intermediate product stream with an aromatization catalyst under aromatization conditions sufficient to evolve an aromatics-rich products stream.

  2. Catalytic conversion of light alkanes

    SciTech Connect

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  3. Alkanes and alkenes conversion to high octane gasoline

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1989-07-25

    This patent describes a process for the conversion of lower alkane and alkene hydrocarbons to high octane gasoline. It comprises: contacting a hydrocarbon feedstock comprising lower alkanes and alkenes with a fluidized bed of acidic, shape selective metallosiliate catalyst in a first conversion zone under high temperature alkane conversion conditions wherein the feedstock contains an amount of lower alkene sufficient to provide an exotherm sufficient to maintain near isothermal reaction conditions whereby an effluent stream is produced comprising higher aliphatic hydrocarbons rich in aromatics; contacting the effluent stream with a fluidized bed of acidic, medium pore metallosilicate catalyst in a second conversion zone at moderate temperature under oligonerization and alkylation conditions whereby a C/sub 5/ + gasoline boiling range product is produced rich in alkylated aromatics.

  4. Conversion of alkanes to linear alkylsilanes using an iridium-iron-catalysed tandem dehydrogenation-isomerization-hydrosilylation.

    PubMed

    Jia, Xiangqing; Huang, Zheng

    2016-02-01

    The conversion of inexpensive, saturated hydrocarbon feedstocks into value-added speciality chemicals using regiospecific, catalytic functionalization of alkanes is a major goal of organometallic chemistry. Linear alkylsilanes represent one such speciality chemical-they have a wide range of applications, including release coatings, silicone rubbers and moulding products. Direct, selective, functionalization of alkanes at primary C-H bonds is difficult and, to date, methods for catalytically converting alkanes into linear alkylsilanes are unknown. Here, we report a well-defined, dual-catalyst system for one-pot, two-step alkane silylations. The system comprises a pincer-ligated Ir catalyst for alkane dehydrogenation and an Fe catalyst that effects a subsequent tandem olefin isomerization-hydrosilylation. This method exhibits exclusive regioselectivity for the production of terminally functionalized alkylsilanes. This dual-catalyst strategy has also been applied to regioselective alkane borylations to form linear alkylboronate esters. PMID:26791899

  5. Conversion of alkanes to linear alkylsilanes using an iridium-iron-catalysed tandem dehydrogenation-isomerization-hydrosilylation

    NASA Astrophysics Data System (ADS)

    Jia, Xiangqing; Huang, Zheng

    2016-02-01

    The conversion of inexpensive, saturated hydrocarbon feedstocks into value-added speciality chemicals using regiospecific, catalytic functionalization of alkanes is a major goal of organometallic chemistry. Linear alkylsilanes represent one such speciality chemical—they have a wide range of applications, including release coatings, silicone rubbers and moulding products. Direct, selective, functionalization of alkanes at primary C-H bonds is difficult and, to date, methods for catalytically converting alkanes into linear alkylsilanes are unknown. Here, we report a well-defined, dual-catalyst system for one-pot, two-step alkane silylations. The system comprises a pincer-ligated Ir catalyst for alkane dehydrogenation and an Fe catalyst that effects a subsequent tandem olefin isomerization-hydrosilylation. This method exhibits exclusive regioselectivity for the production of terminally functionalized alkylsilanes. This dual-catalyst strategy has also been applied to regioselective alkane borylations to form linear alkylboronate esters.

  6. Alkane metathesis by tandem alkane-dehydrogenation-olefin-metathesis catalysis and related chemistry.

    PubMed

    Haibach, Michael C; Kundu, Sabuj; Brookhart, Maurice; Goldman, Alan S

    2012-06-19

    Methods for the conversion of both renewable and non-petroleum fossil carbon sources to transportation fuels that are both efficient and economically viable could greatly enhance global security and prosperity. Currently, the major route to convert natural gas and coal to liquids is Fischer-Tropsch catalysis, which is potentially applicable to any source of synthesis gas including biomass and nonconventional fossil carbon sources. The major desired products of Fischer-Tropsch catalysis are n-alkanes that contain 9-19 carbons; they comprise a clean-burning and high combustion quality diesel, jet, and marine fuel. However, Fischer-Tropsch catalysis also results in significant yields of the much less valuable C(3) to C(8)n-alkanes; these are also present in large quantities in oil and gas reserves (natural gas liquids) and can be produced from the direct reduction of carbohydrates. Therefore, methods that could disproportionate medium-weight (C(3)-C(8)) n-alkanes into heavy and light n-alkanes offer great potential value as global demand for fuel increases and petroleum reserves decrease. This Account describes systems that we have developed for alkane metathesis based on the tandem operation of catalysts for alkane dehydrogenation and olefin metathesis. As dehydrogenation catalysts, we used pincer-ligated iridium complexes, and we initially investigated Schrock-type Mo or W alkylidene complexes as olefin metathesis catalysts. The interoperability of the catalysts typically represents a major challenge in tandem catalysis. In our systems, the rate of alkane dehydrogenation generally limits the overall reaction rate, whereas the lifetime of the alkylidene complexes at the relatively high temperatures required to obtain practical dehydrogenation rates (ca. 125 -200 °C) limits the total turnover numbers. Accordingly, we have focused on the development and use of more active dehydrogenation catalysts and more stable olefin-metathesis catalysts. We have used thermally

  7. Two-stage process for conversion of alkanes to gasoline

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1989-08-22

    This patent describes an improvement in a two-stage process for upgrading hydrocarbons in at least four reaction zones cooperating to produce gasoline range hydrocarbons from lower alkanes. The reaction zones comprising first reaction zone to crack gas oil range hydrocarbons utilizing a large pore cracking catalyst, a second reaction zone in which the large pore catalyst is oxidatively regenerated, a third reaction zone in which an external catalyst cooler autogeneously cools regenerated catalyst by dehydrogenation of the lower alkane stream to produce an olefinic effluent, and a fourth reaction zone in which the olefinic effluent is oligomerized to the gasoline range hydrocarbons. The improvement comprising: a first stage, comprising utilizing excess heat from the second reaction zone: contacting the hot fluid catalytic cracking catalyst with C/sub 3//sup +/ alkanes in the third reaction zone to provide conversion of the alkanes to olefins which leave the third reaction zone as the olefinic effluent separated from catalyst; returning a specified amount of separate fluid catalytic cracking catalyst from the third reaction zone directly to the first or second reaction zone; a second state comprising passing the olefinic effluent from the third reaction zone to a fourth reaction zone for oligomerizing olefins to gasoline range hydrocarbons contacting the olefinic effluent with a medium pore zeolite catalyst effective; recovering a gasoline range hydrocarbon stream from the effluent of the fourth reaction zone.

  8. Environmental chemistry and toxicology of polychlorinated n-alkanes.

    PubMed

    Tomy, G T; Fisk, A T; Westmore, J B; Muir, D C

    1998-01-01

    Polychlorinated-n-alkanes (PCAs) or chlorinated paraffins consist of C10 to C30 n-alkanes with chlorine content from 30% to 70% by mass. PCAs are used as high-temperature lubricants, plasticizers, flame retardants, and additives in adhesives, paints, rubber, and sealants. This review presents the existing data on the environmental chemistry and toxicology of PCAs and a preliminary exposure and risk assessment. There is limited information on the levels, fate, or biological effects of PCAs in the environment. This results both from the difficulty associated with quantifying PCAs, because of the complexity inherent to commercial formulations, and from the limited knowledge of their physicochemical properties and biodegradation rates. There are indications that PCAs are widespread environmental contaminants at ng/L levels in surface waters and ng/g (wet wt) levels in biota. However, environmental measurements of PCAs are very limited in the U.S. and Canada, and are only slightly more detailed in western Europe. Assuming that reported water concentrations are mainly caused by the short chain (C10-C13) compounds, aquatic organisms may be at risk from exposure to PCAs. Fugacity level II modeling for two representative PCAs, using the best available physicochemical property data and estimated degradation rates, suggested that C16C24Cl10 would achieve higher concentrations in biota, sediment, and soil than C12H20Cl6 because of slower degradation rates and lower water solubility. Environmental residence time of C16H24Cl10 is estimated to be 520 d compared to 210 d for C12H20Cl6. Future studies will require better analytical methods and reference materials certified for PCA content. Additional data are needed to evaluate exposure of biota to PCAs in the environment, particularly in light of their continued production and usage around the globe. PMID:9751033

  9. Products of Chemistry: Alkanes: Abundant, Pervasive, Important, and Essential.

    ERIC Educational Resources Information Center

    Seymour, Raymond B.

    1989-01-01

    Discusses the history and commercialization of alkanes. Examines the nomenclature and uses of alkanes. Studies polymerization and several types of polyethylenes: low-density, high-density, low-molecular-weight, cross-linked, linear low-density, and ultrahigh-molecular-weight. Includes a glossary of hydrocarbon terms. (MVL)

  10. OXIDATION OF ALKANES WITH AIR USING IRON AND MANGANESE CATALYSTS. AN OVERALL GREEN CHEMISTRY APPROACH INCLUDING THE USE OF ALTERNATIVE SOLVENT SYSTEMS GENERATED BY PARIS II

    EPA Science Inventory

    The selective oxidation of alkanes is an industrially important process that is often plagued by low conversions and the formation of unwanted by-products. Research being conducted at the USEPA, implements a Green chemistry approach which is utilized to improve these difficult o...

  11. Multi-stage conversion of alkanes to gasoline

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1991-09-17

    This patent describes improvement in a facility for converting alkanes into gasoline, the facility including a fluid catalytic cracking system and an olefin oligomerization reactor. The improvement comprises: a first valved conduit means for withdrawing a controlled stream of the regenerated catalyst from the first regenerator means; a dehydrogenation reactor in valved communication with the first regenerator means, through the first valved conduit means the dehydrogenation reactor having a dehydrogenation zone at a temperature below those prevailing in the first regeneration zone, the dehydrogenation reactor being located externally relative to the fluid catalytic cracker reactor and first regenerator; means for introducing a lower alkane feedstream into the dehydrogenation zone in an amount sufficient to maintain hot withdrawn catalyst in a state of fluidization in the dehydrogenation reactor while the catalyst is being cooled therein; a second valved conduit means for transporting cooled catalyst from the dehydrogenation zone to the first regeneration zone.

  12. The chemistry of energy conversion and storage.

    PubMed

    Su, Dang Sheng

    2014-05-01

    What's in store: The sustainable development of our society requires the conversion and storage of renewable energy, and these should be scaled up to serve the global primary energy consumption. This special issue on "The Chemistry of Energy Conversion and Storage", assembled by guest editor Dangsheng Su, contains papers dealing with these aspects, and highlights important developments in the chemistry of energy conversion and storage during the last two years.

  13. Catalytic conversion of light alkanes. Quarterly progress report, April 1--June 30, 1992

    SciTech Connect

    Lyons, J.E.

    1992-06-30

    The second Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between April 1, 1992 and June 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products that can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon uwspomdon fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE I).

  14. Catalytic conversion of light alkanes: Quarterly report, January 1-March 31, 1992

    SciTech Connect

    Biscardi, J.; Bowden, P.T.; Durante, V.A.; Ellis, P.E. Jr.; Gray, H.B.; Gorbey, R.G.; Hayes, R.C.; Hodge, J.; Hughes, M.; Langdale, W.A.; Lyons, J.E.; Marcus, B.; Messick, D.; Merrill, R.A.; Moore, F.A.; Myers, H.K. Jr.; Seitzer, W.H.; Shaikh, S.N.; Tsao, W.H.; Wagner, R.W.; Warren, R.W.; Wijesekera, T.P.

    1997-05-01

    The first Quarterly Report of 1992 on the Catalytic Conversion of Light Alkanes reviews the work done between January 1. 1992 and March 31, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products which can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon transportation fuel. During the past quarter we have continued to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. We continue to investigate three molecular environments for the active catalytic species that we are trying to generate: electron-deficient porphryinic macrocycles (PHASE I), polyoxometallates (PHASE II), and regular oxidic lattices including zeolites and related structures as well as other molecular surface structures having metal oxo groups (PHASE III).

  15. Catalytic conversion of light alkanes phase II. Topical report, January 1990--January 1993

    SciTech Connect

    1998-12-31

    The Topical Report on Phase II of the project entitled, Catalytic Conversion of Light Alkanes reviews work done between January 1, 1990 and September 30, 1992 on the Cooperative Agreement. The mission of this work is to devise a new catalyst which can be used in a simple economic process to convert the light alkanes in natural gas to oxygenate products which can either be used as clean-burning, high octane liquid fuels, as fuel components or as precursors to liquid hydrocarbon transportation fuel. This Topical Report documents our efforts to design, prepare, characterize and test novel catalysts for the mild selective reaction of light hydrocarbons with air or oxygen to produce alcohols directly. These catalysts are designed to form active metal oxo (MO) species and to be uniquely active for the homolytic cleavage of the carbon-hydrogen bonds in light alkanes producing intermediates which can form alcohols. Research on the Cooperative Agreement is divided into three Phases relating to three molecular environments for the active catalytic species that we are trying to generate. In this report we present our work on catalysts which have oxidation-active metals in polyoxoanions (PHASE II).

  16. Catalytic conversion of light alkanes, Phase 1. Topical report, January 1990--January 1993

    SciTech Connect

    1993-12-31

    The authors have found a family of new catalytic materials which, if successfully developed, will be effective in the conversion of light alkanes to alcohols or other oxygenates. Catalysts of this type have the potential to convert natural gas to clean-burning high octane liquid fuels directly without requiring the energy-intensive steam reforming step. In addition they also have the potential to upgrade light hydrocarbons found in natural gas to a variety of high value fuel and chemical products. In order for commercially useful processes to be developed, increases in catalytic life, reaction rate and selectivity are required. Recent progress in the experimental program geared to the further improvement of these catalysts is outlined.

  17. Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates.

    SciTech Connect

    Lyons, J.E.

    1992-07-01

    The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

  18. Light alkane conversion processes - Suprabiotic catalyst systems for selective oxidation of light alkane gases to fuel oxygenates

    SciTech Connect

    Lyons, J.E.

    1992-01-01

    The objective of the work presented in this paper is to develop new, efficient catalysts for the selective transformation of the light alkanes in natural gas to alcohols for use as liquid transportation fuels, fuel precursors and chemical products. There currently exists no DIRECT one-step catalytic air-oxidation process to convert these substrates to alcohols. Such a one-step route would represent superior useful technology for the utilization of natural gas and similar refinery-derived light hydrocarbon streams. Processes for converting natural gas or its components (methane, ethane, propane, and the butanes) to alcohols for use as motor fuels, fuel additives or fuel precursors will not only add a valuable alternative to crude oil but will produce a clean-burning, high octane alternative to conventional gasoline.

  19. Chemistry of Energy Conversion and Storage.

    PubMed

    Su, Dang-Sheng; Schlögl, R

    2016-02-19

    Special Issue: Energy Conversion and Storage. Critical issues in current energy-based societies are its generation through methods utilizing alternatives to fossil fuels as well as its storage. Considering the scope, it is not surprising that the research becomes more and more multidisciplinary. Therefore, it is important to keep focused. The ChemEner symposia, the last one being highlighted in this Special Issue, achieve this by focusing on the state of the art and the newest development of the Chemistry of hydrogen generation, carbon dioxide reduction, and other related topics, exploring new concepts for clean future energy.

  20. Chemistry of Energy Conversion and Storage.

    PubMed

    Su, Dang-Sheng; Schlögl, R

    2016-02-19

    Special Issue: Energy Conversion and Storage. Critical issues in current energy-based societies are its generation through methods utilizing alternatives to fossil fuels as well as its storage. Considering the scope, it is not surprising that the research becomes more and more multidisciplinary. Therefore, it is important to keep focused. The ChemEner symposia, the last one being highlighted in this Special Issue, achieve this by focusing on the state of the art and the newest development of the Chemistry of hydrogen generation, carbon dioxide reduction, and other related topics, exploring new concepts for clean future energy. PMID:26914171

  1. Catalytic conversion of light alkanes, Phase 3. Topical report, January 1990--December 1992

    SciTech Connect

    1992-12-31

    The mission of this work is to devise a new catalyst which can be used in the first simple, economic process to convert the light alkanes in natural gas to an alcohol-rich oxygenated product which can either be used as an environmentally friendly, high-performance liquid fuel, or a precursor to a liquid hydrocarbon transportation fuel. The authors have entered the proof-of-concept stage for converting isobutane to tert butyl alcohol in a practical process and are preparing to enter proof-of-concept of a propane to isopropyl alcohol process in the near future. Methane and ethane are more refractory and thus more difficult to oxidize than the C{sub 3} and C{sub 4} hydrocarbons. Nonetheless, advances made in this area indicate that further research progress could achieve the goal of their direct conversion to alcohols. Progress in Phase 3 catalytic vapor phase methane and ethane oxidation over metals in regular oxidic lattices are the subject of this topical report.

  2. A Process for Microbial Hydrocarbon Synthesis: Overproduction of Fatty Acids in Escherichia coli and Catalytic Conversion to Alkanes

    PubMed Central

    Lennen, Rebecca M.; Braden, Drew J.; West, Ryan M.; Dumesic, James A.; Pfleger, Brian F.

    2013-01-01

    The development of renewable alternatives to diesel and jet fuels is highly desirable for the heavy transportation sector, and would offer benefits over the production and use of short-chain alcohols for personal transportation. Here, we report the development of a metabolically engineered strain of Escherichia coli that overproduces medium-chain length fatty acids via three basic modifications: elimination of β-oxidation, overexpression of the four subunits of acetyl-CoA carboxylase, and expression of a plant acyl–acyl carrier protein (ACP) thioesterase from Umbellularia californica (BTE). The expression level of BTE was optimized by comparing fatty acid production from strains harboring BTE on plasmids with four different copy numbers. Expression of BTE from low copy number plasmids resulted in the highest fatty acid production. Up to a seven-fold increase in total fatty acid production was observed in engineered strains over a negative control strain (lacking β-oxidation), with a composition dominated by C12 and C14 saturated and unsaturated fatty acids. Next, a strategy for producing undecane via a combination of biotechnology and heterogeneous catalysis is demonstrated. Fatty acids were extracted from a culture of an overproducing strain into an alkane phase and fed to a Pd/C plug flow reactor, where the extracted fatty acids were decarboxylated into saturated alkanes. The result is an enriched alkane stream that can be recycled for continuous extractions. Complete conversion of C12 fatty acids extracted from culture to alkanes has been demonstrated yielding a concentration of 0.44 g L−1 (culture volume) undecane. PMID:20073090

  3. Conversion of raw lignocellulosic biomass into branched long-chain alkanes through three tandem steps.

    PubMed

    Li, Chunrui; Ding, Daqian; Xia, Qineng; Liu, Xiaohui; Wang, Yanqin

    2016-07-01

    Synthesis of branched long-chain alkanes from renewable biomass has attracted intensive interest in recent years, but the feedstock for this synthesis is restricted to platform chemicals. Here, we develop an effective and energy-efficient process to convert raw lignocellulosic biomass (e.g., corncob) into branched diesel-range alkanes through three tandem steps for the first time. Furfural and isopropyl levulinate (LA ester) were prepared from hemicellulose and cellulose fractions of corncob in toluene/water biphasic system with added isopropanol, which was followed by double aldol condensation of furfural with LA ester into C15 oxygenates and the final hydrodeoxygenation of C15 oxygenates into branched long-chain alkanes. The core point of this tandem process is the addition of isopropanol in the first step, which enables the spontaneous transfer of levulinic acid (LA) into the toluene phase in the form of LA ester through esterification, resulting in LA ester co-existing with furfural in the same phase, which is the basis for double aldol condensation in the toluene phase. Moreover, the acidic aqueous phase and toluene can be reused and the residues, including lignin and humins in aqueous phase, can be separated and carbonized to porous carbon materials. PMID:27241180

  4. A new approach to the non-oxidative conversion of gaseous alkanes in a barrier discharge and features of the reaction mechanism

    NASA Astrophysics Data System (ADS)

    Kudryashov, S.; Ryabov, A.; Shchyogoleva, G.

    2016-01-01

    A new approach to the non-oxidative conversion of C1-C4 alkanes into gaseous and liquid products in a barrier discharge is proposed. It consists in inhibiting the formation of deposits on the reactor electrode surfaces due to the addition of distilled water into the flow of hydrocarbon gases. The energy consumption on hydrocarbon conversion decreases from methane to n-butane from ~46 to 35 eV molecule-1. The main gaseous products of the conversion of light alkanes are hydrogen and C2-C4 hydrocarbons. The liquid reaction products contain C5+ alkanes with a predominantly isomeric structure. The results of modeling the kinetics of chemical reactions show that an increase in the molecular weight of the reaction products is mainly due to processes involving CH2 radical and the recombination of alkyl radicals.

  5. Tracing natural gas transport into shallow groundwater using dissolved nitrogen and alkane chemistry in Parker County, Texas

    NASA Astrophysics Data System (ADS)

    Larson, T.; Nicot, J. P.; Mickler, P. J.; Darvari, R.

    2015-12-01

    Dissolved methane in shallow groundwater drives public concern about the safety of hydraulic fracturing. We report dissolved alkane and nitrogen gas concentrations and their stable isotope values (δ13C and δ15N, respectively) from 208 water wells in Parker county, Texas. These data are used to differentiate 'stray' natural gas and low temperature microbial methane, and (2) estimate the ratio of stray gas to groundwater. The ratio of (gas-phase) stray natural gas to groundwater is estimated by correlating dissolved methane and nitrogen concentrations and dissolved nitrogen δ15N values. Our hypothesis is groundwater exposed to high volumes of stray natural gas have high dissolved methane concentrations and low dissolved nitrogen concentrations and δ15N values. Alternatively, groundwater exposed to low volumes of stray gas-phase natural gas have elevated dissolved methane, but the concentration of dissolved nitrogen and its d15N value is atmospheric. A cluster of samples in Parker county have high concentrations of dissolved methane (>10mg/L) with d13Cmethane and alkane ratios (C1/C2+C3) typical of natural gas from the Barnett Shale and the Strawn Formation. Coupling dissolved nitrogen concentrations and δ15N values with these results, we suggest that few of the wells in this cluster preserve large gas to water ratios. Many samples with high dissolved methane concentrations have atmospheric dissolved nitrogen concentrations and δ15N values, providing evidence against high flux natural gas transport into shallow groundwater. These results demonstrate that dissolved nitrogen chemistry, in addition to dissolved alkane and noble gas measurements, may be useful to discern sources of dissolved methane and estimate ratios of stray natural gas-water ratios.

  6. An Acid-Base Chemistry Example: Conversion of Nicotine

    NASA Astrophysics Data System (ADS)

    Summerfield, John H.

    1999-10-01

    The current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry. In particular, the conversion by ammonia of the +1 form of nicotine to the easier-to-assimilate free-base form illustrates the effect of pH on acid-base equilibrium. The part played by ammonia in tobacco smoke is analogous to what takes place when cocaine is "free-based".

  7. Catalytic conversion of light alkanes. Final report, January 1, 1990--October 31, 1994

    SciTech Connect

    1998-12-31

    During the course of the first three years of the Cooperative Agreement (Phase I-III), we uncovered a family of metal perhaloporphyrin complexes which had unprecedented activity for the selective air-oxidation of fight alkanes to alcohols. The reactivity of fight hydrocarbon substrates with air or oxygen was in the order: isobutane>propane>ethane>methane, in accord with their homolytic bond dissociation energies. Isobutane was so reactive that the proof-of concept stage of a process for producing tert-butyl alcohol from isobutane was begun (Phase V). It was proposed that as more active catalytic systems were developed (Phases IV, VI), propane, then ethane and finally methane oxidations will move into this stage (Phases VII through IX). As of this writing, however, the program has been terminated during the later stages of Phases V and VI so that further work is not anticipated. We made excellent progress during 1994 in generating a class of less costly new materials which have the potential for high catalytic activity. New routes were developed for replacing costly perfluorophenyl groups in the meso-position of metalloporphyrin catalysts with far less expensive and lower molecular weight perfluoromethyl groups.

  8. The Chemistry of Energy Conversion and Storage.

    PubMed

    Cho, Jaephil; Dai, Liming; Guldi, Dirk

    2016-04-20

    Extra energy required: One of the most critical issues facing society today is energy - where do we get it from, how do we use it, how do we store it, how can we save it. Chemists play a decisive role in facing these challenges to secure a ready supply of energy for generations to come. To highlight the importance of this topic and the contributions that chemists around the world make, this special issue is dedicated to energy conversion and storage. Graphic designed by Freepik. http://www.freepik.com/free-vector/ batteries_800894.htm. PMID:27061944

  9. [Sources, Migration and Conversion of Dissolved Alkanes, Dissolved Fatty Acids in a Karst Underground River Water, in Chongqing Area].

    PubMed

    Liang, Zuo-bing; Sun, Yu-chuan; Wang, Zun-bo; Shi, Yang; Jiang, Ze-li; Zhang, Mei; Xie, Zheng-Lan; Liao, Yu

    2015-09-01

    Dissolved alkanes and dissolved fatty acids were collected from Qingmuguan underground river in July, October 2013. By gas chromatography-mass spectrometer (GC-MS), alkanes and fatty acids were quantitatively analyzed. The results showed that average contents of alkanes and fatty acids were 1 354 ng.L-1, 24203 ng.L-1 in July, and 667 ng.L-1, 2526 ng.L-1 in October respectively. With the increasing migration distance of dissolved alkanes and dissolved fatty acids in underground river, their contents decreased. Based on the molecular characteristic indices of alkanes, like CPI, OEP, Paq and R, dissolved alkanes were mainly originated from microorganisms in July, and aquatic plants in October. Saturated straight-chain fatty acid had the highest contents in all samples with the dominant peak in C16:0, combined with the characteristics of carbon peak, algae or bacteria might be the dominant source of dissolved fatty acids. PMID:26717680

  10. Thermodynamic analysis of syngas conversion chemistry

    SciTech Connect

    Vijayaraghavan, P.; Lee, S.

    1994-12-31

    The liquid phase catalytic conversion of syngas to methanol (LPMeOH{trademark}), and syngas to methanol and dimethyl ether (LPDME process) was investigated in a three-phase mini-pilot plant version of a mechanically agitated slurry reactor system. In this reactor system, the catalyst particles in powder form are slurried in the oil phase and this slurry is agitated by a mechanically driven impeller. Syngas reacts in the presence of the methanol synthesis catalyst (Cu/ZnO/Al{sub 2}O{sub 3})-oil slurry to form the product methanol in the LPMeOH process. The productivity of methanol in this process, is adversely affected by the chemical equilibrium limitation. Hence the dual catalytic approach (LPDME process), where the productivity of methanol is enhanced by the co-production of dimethyl ether with methanol, was developed to alleviate the chemical equilibrium limitation. In this LPDME process, syngas reacts in the presence of the methanol synthesis catalyst and the methanol dehydration catalyst ({gamma}-alumina), which are both slurried in the oil phase. The thermodynamics of the liquid phase methanol synthesis process and the liquid phase dimethyl ether process were investigated. The equilibrium conversions of H{sub 2}, CO, and syngas in both the processes are compared for nominally identical operating conditions. The effect of water and CO{sub 2} addition to the feed syngas, and the effect of temperature and pressure on the LPMeOH process and the LPDME process were also compared.

  11. Bringing an "old" biological buffer to coordination chemistry: new 1D and 3D coordination polymers with [Cu(4)(Hbes)(4)] cores for mild hydrocarboxylation of alkanes.

    PubMed

    Kirillov, Alexander M; Coelho, Jaime A S; Kirillova, Marina V; da Silva, M Fátima C Guedes; Nesterov, Dmytro S; Gruenwald, Katrin R; Haukka, Matti; Pombeiro, Armando J L

    2010-07-19

    New water-soluble 1D and 3D Cu(II)/Na coordination polymers 1-3 bearing unprecedented [Cu(4)(Hbes)(4)] cores have been easily generated by aqueous-medium self-assembly and fully characterized, thus opening up the use of the common biological buffer H(3)bes, (HO(3)SCH(2)CH(2))N(CH(2)CH(2)OH)(2), in synthetic coordination chemistry. Apart from representing the first isolated and structurally characterized coordination compounds derived from H(3)bes, 1-3 show a remarkable promoting effect in the mild aqueous-medium hydrocarboxylation, by CO and H(2)O, of gaseous alkanes (C(3)H(8) and n-C(4)H(10)) to the corresponding carboxylic acids, which are obtained in up to 95% yields based on the alkane.

  12. Direct Energy Conversion: Chemistry, Physics, Materials Science and Thermoelectrics.

    NASA Astrophysics Data System (ADS)

    Kanatzidis, Mercouri

    2006-03-01

    Interest in all-solid-state thermal to electrical conversion has been steadily increasing in recent years and this has been coinciding with an increasing recognition of rising energy demands in the future. Thus there is now renewed awareness of the need to find new energy sources and make conservation efforts more efficient. In this context thermoelectric materials seem poised to have an impact. Research is needed to understand at the fundamental level the scientific issues that are crucial in designing and discovering new highly efficient thermoelectrics. The progress in the field of thermoelectrics has been significant both at the concept level and at the materials discovery level thanks to a convergence of chemistry, physics and materials science efforts. I will describe how each of these disciplines impact each other to produce synergies that propel advances in this area. I will present recent progress in novel nanostructured chalcogenide materials that stimulate new experimentation and hold considerable promise for higher efficiencies in heat to electricity conversion.

  13. Chemistry of Furan Conversion into Aromatics and Olefins over HZSM-5: A Model Biomass Conversion Reaction

    SciTech Connect

    Cheng, Yu-Ting; Huber, George W.

    2011-06-03

    The conversion of furan (a model of cellulosic biomass) over HZSM-5 was investigated in a thermogravimetric analysis–mass spectrometry system, in situ Fourier transform infrared analysis, and in a continuous-flow fixed-bed reactor. Furan adsorbed as oligomers at room temperature with a 1.73 of adsorbed furan/Al ratio. These oligomers were polycyclic aromatic compounds that were converted to CO, CO₂, aromatics, and olefins at temperatures from 400 to 600 °C. Aromatics (e.g., benzene, toluene, and naphthalene), oligomer isomers (e.g., benzofuran, 2,2-methylenebisfuran, and benzodioxane), and heavy oxygenates (C₁₂{sub +} oligomers) were identified as intermediates formed inside HZSM-5 at different reaction temperatures. During furan conversion, graphite-type coke formed on the catalyst surface, which caused the aromatics and olefins formation to deactivate within the first 30 min of time on-stream. We have measured the effects of space velocity and temperature for furan conversion to help us understand the chemistry of biomass conversion inside zeolite catalysts. The major products for furan conversion included CO, CO₂, allene, C₂–C₆ olefins, benzene, toluene, styrene, benzofuran, indene, and naphthalene. The aromatics (benzene and toluene) and olefins (ethylene and propylene) selectivity decreased with increasing space velocity. Unsaturated hydrocarbons such as allene, cyclopentadiene, and aromatics selectivity increased with increasing space velocity. The product distribution was selective to olefins and CO at high temperatures (650 °C) but was selective to aromatics (benzene and toluene) at intermediate temperatures (450–600 °C). At low temperatures (450 °C), benzofuran and coke contributed 60% of the carbon selectivity. Several different reactions were occurring for furan conversion over zeolites. Some important reactions that we have identified in this study include Diels–Alder condensation (e.g., two furans form benzofuran and water

  14. Catalytic conversion of light alkanes-proof-of-concept stage -- Phase 6. Final report, February 1--October 31, 1994

    SciTech Connect

    1994-12-31

    During the course of the first three years of the Cooperative Agreement, the authors uncovered a family of metal perhaloporphyrin complexes which had unprecedented activity for the selective air-oxidation of light alkanes to alcohols. The reactivity of light hydrocarbon substrates with air or oxygen was in the order: isobutane > propane > ethane > methane, in accord with their homolytic bond dissociation energies. Isobutane was so reactive that the proof-of-concept stage of a process for producing tert-butyl alcohol from isobutane was begun (Phase 5). It was proposed that as more active catalytic systems were developed (Phases 4, 6), propane, then ethane and finally methane oxidations will move into this stage (Phases 7 through 9). As of this writing, however, the program has been terminated during the later stages of Phase 5 and 6 so that further work is not anticipated. 72 refs.

  15. Oxygen-free conversion of methane to higher alkanes through an isothermal two-step reaction on ruthenium

    SciTech Connect

    Belgued, M.; Amariglio, A.; Lefort, L.; Amariglio, H.

    1996-06-01

    Ruthenium dispersed on silica is able to chemisorb CH{sub 4} at temperatures significantly lower than EUROPT-1. At the temperatures used ({ge}80{degrees}C), H{sub 2} desorption parallels CH{sub 4} chemisorption but no C{sub 2}H{sub 6} is observed. During the following temperature programmed desorption under flowing argon, CH{sub 4} is removed through a wide range of temperature (from room temperature to 300{degrees}C) with a first contribution peaking at less than 100{degrees}C. Very small amounts of CH{sub 4} are desorbed after an adsorption carried out at T{ge} 180{degrees}C, due to strong dehydrogenation of the adspecies. Subsequent temperature programmed surface reaction of the remaining adspecies with hydrogen displays upto four CH{sub 4} peaks at well defined temperatures (ranging from {approx} 60 to {approx} 340{degrees}C), accompanied by a negligible formation of ethane. No C{sub {gamma}} was formed. The total amount of adsorbed CH{sub 4} and the average H/C ratio of the corresponding adspecies can be derived from these experiments. In a separate set of experiments, CH{sub 4} is switched to H{sub 2} at the end of the exposure step, the temperature being fixed. An immediate formation of alkanes ranging from C{sub 1} to C{sub 6} is then evidenced. A sizeable fraction of the chemisorbed layer can so be homologated to higher alkanes. The influences of the various operating factors are reported. In particular a neat maximum of the C{sub 2+} production versus temperature (at 160{degrees}C) is evidenced and is clearly due to the adverse hydrogenolysis reactions, efficiently catalyzed by Ru. All the results can be interpreted in complete similarity with the Pt case. 5 refs., 16 figs., 3 tabs.

  16. Catalytic conversion of light alkanes-proof-of-concept stage - Phase IV. Topical report, February 1, 1994--January 31, 1995

    SciTech Connect

    1998-12-31

    This report details the research performed on Phase IV of the extended Cooperative Agreement. This Phase, entitled C{sub 1}-C{sub 4} Research, provides the research support which accompanies the C{sub 4} Proof-of-Concept Phase (Phase V) as the two major activities of the Cooperative Agreement during calendar 1993. It is the objective of this phase to understand the nature of the catalysts and catalytic activity of perhaloporphyrin complexes uncovered during Phases I-III in order that superior catalytic materials can be made and tested which meet commercial criteria for the oxidation of the C{sub 1}-C{sub 4} light alkane gases found in natural gas and other available hydrocarbon streams. During Phase IV, we have examined the physical and electronic structures of the very active perhaloporphyrin catalysts which we have developed, and have gained an understanding of the properties which make them active. This has led us to design and synthesize materials which are cheaper, more active, more robust and, in general superior for carrying out practical catalysis. Our early generation perhaloporphyrin catalysts, while exhibiting unprecedented catalytic activity, were far too expensive for use in converting natural gas or its C{sub 1}-C{sub 4} components.

  17. Reducing the Degrees of Freedom in Chemistry Classroom Conversations

    ERIC Educational Resources Information Center

    Criswell, Brett A.

    2012-01-01

    Five high-school chemistry teachers were asked to enact a lesson in which they posed a problem for which students were likely to generate solutions based on reasoning that was not aligned with accepted principles of chemistry. Four teachers selected a problem related to the stoichiometry of a reaction; the fifth chose a problem associated with…

  18. Mimicking enzymatic active sites on surfaces for energy conversion chemistry.

    PubMed

    Gutzler, Rico; Stepanow, Sebastian; Grumelli, Doris; Lingenfelder, Magalí; Kern, Klaus

    2015-07-21

    Metal-organic supramolecular chemistry on surfaces has matured to a point where its underlying growth mechanisms are well understood and structures of defined coordination environments of metal atoms can be synthesized in a controlled and reproducible procedure. With surface-confined molecular self-assembly, scientists have a tool box at hand which can be used to prepare structures with desired properties, as for example a defined oxidation number and spin state of the transition metal atoms within the organic matrix. From a structural point of view, these coordination sites in the supramolecular structure resemble the catalytically active sites of metallo-enzymes, both characterized by metal centers coordinated to organic ligands. Several chemical reactions take place at these embedded metal ions in enzymes and the question arises whether these reactions also take place using metal-organic networks as catalysts. Mimicking the active site of metal atoms and organic ligands of enzymes in artificial systems is the key to understanding the selectivity and efficiency of enzymatic reactions. Their catalytic activity depends on various parameters including the charge and spin configuration in the metal ion, but also on the organic environment, which can stabilize intermediate reaction products, inhibits catalytic deactivation, and serves mostly as a transport channel for the reactants and products and therefore ensures the selectivity of the enzyme. Charge and spin on the transition metal in enzymes depend on the one hand on the specific metal element, and on the other hand on its organic coordination environment. These two parameters can carefully be adjusted in surface confined metal-organic networks, which can be synthesized by virtue of combinatorial mixing of building synthons. Different organic ligands with varying functional groups can be combined with several transition metals and spontaneously assemble into ordered networks. The catalytically active metal

  19. Dehydrogenation of n-alkanes catalyzed by iridium ``pincer`` complexes: Regioselective formation of {alpha}-olefins

    SciTech Connect

    Liu, F.; Singh, B.; Goldman, A.S.; Pak, E.B.; Jensen, C.M.

    1999-04-28

    The development of methods for the functionalization of alkanes is of cardinal importance in catalytic chemistry. A specific functionalization of particularly great potential value is the conversion of n-alkanes to the corresponding 1-alkenes ({alpha}-olefins) since these serve as precursors for a wide range of commodity-scale chemicals (>2 {times} 10{sup 9} kg/yr). Such a conversion is also an intriguing challenge as viewed from a fundamental perspective. n-Alkanes are the simplest organic molecules with the potential to undergo regioselective transformations; {alpha}-olefins are the thermodynamically least stable of the corresponding double-bond isomers and any mechanism for their formation must presumably involve activation of the strongest bond (primary C-{single_bond}H) in the molecule.

  20. Symposium on the Physical Chemistry of Solar Energy Conversion, Indianapolis American Chemical Society Meetings, Fall 2013

    SciTech Connect

    Lian, Tianquan

    2013-09-20

    The Symposium on the Physical Chemistry of Solar Energy Conversion at the Fall ACS Meeting in Indianapolis, IN (Sept. 8-12) featured the following sessions (approx. 6 speakers per session): (1) Quantum Dots and Nanorods for Solar Energy Conversion (2 half-day sessions); (2) Artificial Photosynthesis: Water Oxidation; (3) Artificial Photosynthesis: Solar Fuels (2 half-day sessions); (4) Organic Solar Cells; (5) Novel Concepts for Solar Energy Conversion (2 half-day sessions); (6) Emerging Techniques for Solar Energy Conversion; (7) Interfacial Electron Transfer

  1. Superacid catalysis of light hydrocarbon conversion. Eleventh quarterly report, April 1, 1996--June 30, 1996

    SciTech Connect

    Gates, B.C.

    1996-12-31

    The new catalyst Fe- and Mn-promoted sulfated zirconia is remarkably active for the low-temperature (even room temperature) isomerization of n-butane to give isobutane in the near absence of side products. Thus this catalyst offers excellent potential for practical application in this process. The catalyst is so active that it even converts smaller alkanes, including propane and ethane. The ethane conversion is orders of magnitude slower than the butane conversion, and the prospects for practical application with ethane are apparently negligible. However, the results for ethane conversion provide strong evidence that the alkane conversions proceed (at least under some conditions) by protonation of the alkane with the catalyst; thus the catalyst is comparable to superacids, and the chemistry is analogous to that occurring in superacid solutions. This insight will be useful in further improvement of the catalyst and the potential process for butane isomerization. The catalyst is active for alkane cracking at temperatures of typically 200-300{degrees}C, and evidence, summarized here, indicates that numerous reactions of alkanes begin as the catalyst protonates the alkane reactant. The kinetics data for this family of reactions fall on a linear compensation effect plot; such data for reactions that do not proceed via such a mechanism do not fall near the line representing the compensation effect. Thus the analysis of the kinetics data provides a good diagnostic tool for understanding the fundamental chemistry of the acid-catalyzed hydrocarbon conversions.

  2. EDITORIAL: Non-thermal plasma-assisted fuel conversion for green chemistry Non-thermal plasma-assisted fuel conversion for green chemistry

    NASA Astrophysics Data System (ADS)

    Nozaki, Tomohiro; Gutsol, Alexander

    2011-07-01

    This special issue is based on the symposium on Non-thermal Plasma Assisted Fuel Conversion for Green Chemistry, a part of the 240th ACS National Meeting & Exposition held in Boston, MA, USA, 22-26 August 2010. Historically, the Division of Fuel Chemistry of the American Chemical Society (ACS) has featured three plasma-related symposia since 2000, and has launched special issues in Catalysis Today on three occasions: 'Catalyst Preparation using Plasma Technologies', Fall Meeting, Washington DC, USA, 2000. Special issue in Catalysis Today 72 (3-4) with 12 peer-reviewed articles. 'Plasma Technology and Catalysis', Spring Meeting, New Orleans, LA, USA, 2003. Special issue in Catalysis Today 89 (1-2) with more than 30 peer-reviewed articles. 'Utilization of Greenhouse Gases II' (partly focused on plasma-related technologies), Spring Meeting, Anaheim, CA, USA, 2004. Special issue in Catalysis Today 98 (4) with 25 peer-reviewed articles. This time, selected presentations are published in this Journal of Physics D: Applied Physics special issue. An industrial material and energy conversion technology platform is established on thermochemical processes including various catalytic reactions. Existing industry-scale technology is already well established; nevertheless, further improvement in energy efficiency and material saving has been continuously demanded. Drastic reduction of CO2 emission is also drawing keen attention with increasing recognition of energy and environmental issues. Green chemistry is a rapidly growing research field, and frequently highlights renewable bioenergy, bioprocesses, solar photocatalysis of water splitting, and regeneration of CO2 into useful chemicals. We would also like to emphasize 'plasma catalysis' of hydrocarbon resources as an important part of the innovative next-generation green technologies. The peculiarity of non-thermal plasma is that it can generate reactive species almost independently of reaction temperature. Plasma

  3. Superacid Catalyzed Coal Conversion Chemistry. Final Technical Report, September 1, 1983-September 1, 1986

    DOE R&D Accomplishments Database

    Olah, G. A.

    1986-01-01

    This research project involved the study of a raw comparatively mild coal conversion process. The goal of the project was to study model systems to understand the basic chemistry involved and to provide a possible effective pretreatment of coal which significantly improves liquefaction-depolymerization under mild conditions. The conversion process operates at relatively low temperatures (170 degrees C) and pressures and uses an easily recyclable, stable superacid catalysts (HF-BF{sub 3}). It consequently offers an attractive alternative to currently available processes. From the present studies it appears that the modification of coal structure by electrophilic alkylation and subsequent reaction of alkylated coal with HF-BF{sub 3}-H{sub 2} system under mild conditions considerably improves the extractability of coal in pyridine and cyclohexane. On the other hand, nitration of coal and its subsequent reaction with HF-BF{sub 3}H{sub 2} decreases the pyridine and cyclohexane extractability. Study of model compounds under conditions identical with the superacidic HF/BF{sub 3}/H{sub 2} system provided significant information about the basic chemistry of the involved cleavage-hydrogenation reactions.

  4. Effect of gas composition on the NOx conversion chemistry in a plasma

    SciTech Connect

    McLarnon, C R; Penetrante, B M

    1998-08-24

    Much work has been done on the application of plasmas to the treatment of NOx from power plants. In power plant applications, the purpose of the plasma is to oxidize NO to NOx, and eventually to nitric acid. The desires products, in the form of ammonium salts, are then obtained by mixing ammonia with the formed acids. Some form of scrubbing is required to collect the final products. For applications to the treatment of exhausts from cars and trucks, it is very important to make a distinction between NO removal by chemical oxidation and NO removal by chemical reduction. To avoid the need for scrubbing of plasma processing products, the desired method of NO removal is by chemical reduction; i.e., the conversion of NO to benign gaseous products like N NO2. This paper will discuss the results of an extensive series of experiments aimed towards understanding the effect of gas composition on the NOx conversion chemistry in a plasma. The NOx conversion chemistry in the presence of the individual components, such as N2, O2, H2O, and CO2, as well as the mixture of these, will be presented. We will show that, in a lean-burn gasoline or diesel engine exhaust, the main effect of the gas-phase reactions in a plasma is the oxidation of NO to NOx and nitric acid. To implement the reduction of NOx to N2 in the highly oxidizing environment of a lean-burn engine exhaust, it will be necessary to prevent the formation of acid products and combine the plasma with another process that can chemically reduce NO2 to Nx.

  5. Gas-to-Particle Conversion in Surface Discharge Nonthermal Plasmas and Its Implications for Atmospheric Chemistry

    PubMed Central

    Kim, Hyun-Ha; Ogata, Atsushi

    2011-01-01

    This paper presents some experimental data on gas-to-particle conversion of benzene using nonthermal plasma (NTP) technology and discusses the possibility of its technical application in atmospheric chemistry. Aerosol measurement using a differential mobility analyzer (DMA) revealed that the parts of benzene molecules were converted into a nanometer-sized aerosol. Aerosol formation was found to be highly related with the missing part in carbon balance. Scanning electron microscopy analysis showed that the aerosols formed in synthetic humid air are the collection of nanoparticles. The carbonyl band (C=O) was found to be an important chemical constituent in the aerosol. The potential of the NTP as an accelerated test tool in studying secondary organic aerosol (SOA) formation from VOCs will be also addressed. PMID:22163781

  6. The hydrodeoxygenation of bioderived furans into alkanes

    NASA Astrophysics Data System (ADS)

    Sutton, Andrew D.; Waldie, Fraser D.; Wu, Ruilian; Schlaf, Marcel; ‘Pete' Silks, Louis A.; Gordon, John C.

    2013-05-01

    The conversion of biomass into fuels and chemical feedstocks is one part of a drive to reduce the world's dependence on crude oil. For transportation fuels in particular, wholesale replacement of a fuel is logistically problematic, not least because of the infrastructure that is already in place. Here, we describe the catalytic defunctionalization of a series of biomass-derived molecules to provide linear alkanes suitable for use as transportation fuels. These biomass-derived molecules contain a variety of functional groups, including olefins, furan rings and carbonyl groups. We describe the removal of these in either a stepwise process or a one-pot process using common reagents and catalysts under mild reaction conditions to provide n-alkanes in good yields and with high selectivities. Our general synthetic approach is applicable to a range of precursors with different carbon content (chain length). This allows the selective generation of linear alkanes with carbon chain lengths between eight and sixteen carbons.

  7. The hydrodeoxygenation of bioderived furans into alkanes.

    PubMed

    Sutton, Andrew D; Waldie, Fraser D; Wu, Ruilian; Schlaf, Marcel; Silks, Louis A Pete; Gordon, John C

    2013-05-01

    The conversion of biomass into fuels and chemical feedstocks is one part of a drive to reduce the world's dependence on crude oil. For transportation fuels in particular, wholesale replacement of a fuel is logistically problematic, not least because of the infrastructure that is already in place. Here, we describe the catalytic defunctionalization of a series of biomass-derived molecules to provide linear alkanes suitable for use as transportation fuels. These biomass-derived molecules contain a variety of functional groups, including olefins, furan rings and carbonyl groups. We describe the removal of these in either a stepwise process or a one-pot process using common reagents and catalysts under mild reaction conditions to provide n-alkanes in good yields and with high selectivities. Our general synthetic approach is applicable to a range of precursors with different carbon content (chain length). This allows the selective generation of linear alkanes with carbon chain lengths between eight and sixteen carbons. PMID:23609095

  8. Defect chemistry and defect engineering of TiO2-based semiconductors for solar energy conversion.

    PubMed

    Nowotny, Janusz; Alim, Mohammad Abdul; Bak, Tadeusz; Idris, Mohammad Asri; Ionescu, Mihail; Prince, Kathryn; Sahdan, Mohd Zainizan; Sopian, Kamaruzzaman; Mat Teridi, Mohd Asri; Sigmund, Wolfgang

    2015-12-01

    This tutorial review considers defect chemistry of TiO2 and its solid solutions as well as defect-related properties associated with solar-to-chemical energy conversion, such as Fermi level, bandgap, charge transport and surface active sites. Defect disorder is discussed in terms of defect reactions and the related charge compensation. Defect equilibria are used in derivation of defect diagrams showing the effect of oxygen activity and temperature on the concentration of both ionic and electronic defects. These defect diagrams may be used for imposition of desired semiconducting properties that are needed to maximize the performance of TiO2-based photoelectrodes for the generation of solar hydrogen fuel using photo electrochemical cells (PECs) and photocatalysts for water purification. The performance of the TiO2-based semiconductors is considered in terms of the key performance-related properties (KPPs) that are defect related. It is shown that defect engineering may be applied for optimization of the KPPs in order to achieve optimum performance. PMID:26446476

  9. Developing new synthetic methods for colloidal hybrid nanoparticles: Conversion chemistry and chemoselectivity

    NASA Astrophysics Data System (ADS)

    Bradley, Matthew

    Colloidal hybrid nanoparticles contain multiple domains, and through their solidsolid interfaces, can facilitate synergistic relationships between domains, resulting in the incorporation of multiple functionalities as well as modification of the intrinsic properties of each domain. Although there is a growing number of materials and applications associated with these unique types of particles, new synthetic methods must be investigated in order to realize the full potential of this new class of particles. To address this need, we demonstrate that the concepts used in total synthesis of complex organic molecules, can be applied to the synthesis of colloidal hybrid nanoparticles. Site selective growth, conversion chemistry, condensation chemistry, and protection/deprotection reactions are examined as ways to add complexity to colloidal hybrid nanoparticles. First, we will discuss the synthesis of PtPb-Fe3O4 and Pt3Sn-Fe3O4 heterodimer particles via a solution mediated conversion chemistry process. These types of reactions are known to be useful for nanoparticle systems but had not been explored as a method for adding complexity to colloidal heterodimers. Pt-Fe3O 4 heterodimers react with Pb(acac)2 and Sn(acac)2 at 180-200°C in a mixture of benzyl ether, oleylamine, oleic acid, and tert-butylamine borane to form PtPb-Fe3O4 and Pt3Sn-Fe3O4 heterodimers, respectively. This chemical transformation reaction introduces intermetallic and alloy components into the heterodimers, proceeds with morphological retention, and preserves the solid-solid interface that characterizes these hybrid nanoparticle systems. In addition, the PtPb-Fe3O4 heterodimers spontaneously aggregate to form colloidally stable (PtPb-Fe3O4) n nanoflowers via a process that is conceptually analogous to a molecular condensation reaction. Next, we will discuss the methanol oxidation activity of PtPb-Fe 3O4 and Pt3Sn- Fe3O4 heterodimers as well as examine the role of ligand exchange in this process. Before

  10. Drugs in the Chemistry Laboratory: The Conversion of Acetaminophen into Phenacetin.

    ERIC Educational Resources Information Center

    Volker, Eugene J.; And Others

    1979-01-01

    Describes an experiment in which acetaminophen is converted into phenacetin, that has been used at Shepherd College in an introductory chemistry course for nurses and in the organic chemistry laboratory. (BT)

  11. Organic Chemistry and the Native Plants of the Sonoran Desert: Conversion of Jojoba Oil to Biodiesel

    ERIC Educational Resources Information Center

    Daconta, Lisa V.; Minger, Timothy; Nedelkova, Valentina; Zikopoulos, John N.

    2015-01-01

    A new, general approach to the organic chemistry laboratory is introduced that is based on learning about organic chemistry techniques and research methods by exploring the natural products found in local native plants. As an example of this approach for the Sonoran desert region, the extraction of jojoba oil and its transesterification to…

  12. Mesoscale effects in electrochemical conversion: coupling of chemistry to atomic- and nanoscale structure in iron-based electrodes.

    PubMed

    Wiaderek, Kamila M; Borkiewicz, Olaf J; Pereira, Nathalie; Ilavsky, Jan; Amatucci, Glenn G; Chupas, Peter J; Chapman, Karena W

    2014-04-30

    The complex coupling of atomic, chemical, and electronic transformations across multiple length scales underlies the performance of electrochemical energy storage devices. Here, the coupling of chemistry with atomic- and nanoscale structure in iron conversion electrodes is resolved by combining pair distribution function (PDF) and small-angle X-ray scattering (SAXS) analysis for a series of Fe fluorides, oxyfluorides, and oxides. The data show that the anion chemistry of the initial electrode influences the abundance of atomic defects in the Fe atomic lattice. This, in turn, is linked to different atom mobilities and propensity for particle growth. Competitive nanoparticle growth in mixed anion systems contributes to a distinct nanostructure, without the interconnected metallic nanoparticles formed for single anion systems.

  13. Towards a practical development of light-driven acceptorless alkane dehydrogenation.

    PubMed

    Chowdhury, Abhishek Dutta; Weding, Nico; Julis, Jennifer; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2014-06-16

    The efficient catalytic dehydrogenation of alkanes to olefins is one of the most investigated reactions in organic synthesis. In the coming years, an increased supply of shorter-chain alkanes from natural and shale gas will offer new opportunities for inexpensive carbon feedstock through such dehydrogenation processes. Existing methods for alkane dehydrogenation using heterogeneous catalysts require harsh reaction conditions and have a lack of selectivity, whereas homogeneous catalysis methods result in significant waste generation. A strong need exists for atom-efficient alkane dehydrogenations on a useful scale. Herein, we have developed improved acceptorless catalytic systems under optimal light transmittance conditions using trans-[Rh(PMe3)2(CO)Cl] as the catalyst with different additives. Unprecedented catalyst turnover numbers are obtained for the dehydrogenation of cyclic and linear (from C4) alkanes and liquid organic hydrogen carriers. These reactions proceed with unique conversion, thereby providing a basis for practical alkane dehydrogenations. PMID:24829085

  14. More than a Conversation: Using Cogenerative Dialogues in the Professional Development of High School Chemistry Teachers

    ERIC Educational Resources Information Center

    Martin, Sonya N.; Scantlebury, Kathryn

    2009-01-01

    This paper focuses on content-based and pedagogical instructors' use of cogenerative dialogues to improve instructional practice and to evaluate program effectiveness in a professional development program for high school chemistry teachers. We share our research findings from using cogenerative dialogues as an evaluative tool for general…

  15. Potential and challenges of zeolite chemistry in the catalytic conversion of biomass.

    PubMed

    Ennaert, Thijs; Van Aelst, Joost; Dijkmans, Jan; De Clercq, Rik; Schutyser, Wouter; Dusselier, Michiel; Verboekend, Danny; Sels, Bert F

    2016-02-01

    Increasing demand for sustainable chemicals and fuels has pushed academia and industry to search for alternative feedstocks replacing crude oil in traditional refineries. As a result, an immense academic attention has focused on the valorisation of biomass (components) and derived intermediates to generate valuable platform chemicals and fuels. Zeolite catalysis plays a distinct role in many of these biomass conversion routes. This contribution emphasizes the progress and potential in zeolite catalysed biomass conversions and relates these to concepts established in existing petrochemical processes. The application of zeolites, equipped with a variety of active sites, in Brønsted acid, Lewis acid, or multifunctional catalysed reactions is discussed and generalised to provide a comprehensive overview. In addition, the feedstock shift from crude oil to biomass involves new challenges in developing fields, like mesoporosity and pore interconnectivity of zeolites and stability of zeolites in liquid phase. Finally, the future challenges and perspectives of zeolites in the processing of biomass conversion are discussed.

  16. Potential and challenges of zeolite chemistry in the catalytic conversion of biomass.

    PubMed

    Ennaert, Thijs; Van Aelst, Joost; Dijkmans, Jan; De Clercq, Rik; Schutyser, Wouter; Dusselier, Michiel; Verboekend, Danny; Sels, Bert F

    2016-02-01

    Increasing demand for sustainable chemicals and fuels has pushed academia and industry to search for alternative feedstocks replacing crude oil in traditional refineries. As a result, an immense academic attention has focused on the valorisation of biomass (components) and derived intermediates to generate valuable platform chemicals and fuels. Zeolite catalysis plays a distinct role in many of these biomass conversion routes. This contribution emphasizes the progress and potential in zeolite catalysed biomass conversions and relates these to concepts established in existing petrochemical processes. The application of zeolites, equipped with a variety of active sites, in Brønsted acid, Lewis acid, or multifunctional catalysed reactions is discussed and generalised to provide a comprehensive overview. In addition, the feedstock shift from crude oil to biomass involves new challenges in developing fields, like mesoporosity and pore interconnectivity of zeolites and stability of zeolites in liquid phase. Finally, the future challenges and perspectives of zeolites in the processing of biomass conversion are discussed. PMID:26691750

  17. Catalytic oxidation of light alkanes in presence of a base

    DOEpatents

    Bhinde, Manoj V.; Bierl, Thomas W.

    1998-01-01

    The presence of a base in the reaction mixture in a metal-ligand catalyzed partial oxidation of alkanes results in sustained catalyst activity, and in greater percent conversion as compared with oxidation in the absence of base, while maintaining satisfactory selectivity for the desired oxidation, for example the oxidation of isobutane to isobutanol.

  18. Catalytic oxidation of light alkanes in presence of a base

    DOEpatents

    Bhinde, M.V.; Bierl, T.W.

    1998-03-03

    The presence of a base in the reaction mixture in a metal-ligand catalyzed partial oxidation of alkanes results in sustained catalyst activity, and in greater percent conversion as compared with oxidation in the absence of base, while maintaining satisfactory selectivity for the desired oxidation, for example the oxidation of isobutane to isobutanol. 1 fig.

  19. Catalytic, mild, and selective oxyfunctionalization of linear alkanes: current challenges.

    PubMed

    Bordeaux, Mélanie; Galarneau, Anne; Drone, Jullien

    2012-10-22

    Selective catalysts for sustainable oxidation of alkanes are highly demanded because of the abundance of these molecules in the environment, the possibility to transform them into higher-value compounds, such as chemicals or synthetic fuels, and the fact that, kinetically speaking, this is a difficult reaction. Numerous chemical and biological catalysts have been developed in the lasts decades for this purpose, rendering the overview over this field of chemistry difficult. After giving a definition of the ideal catalyst for alkane oxyfunctionalization, this review aims to present the catalysts available today that are closest to ideal.

  20. High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes

    SciTech Connect

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M

    2011-03-01

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed high temperature chemical kinetic mechanism for n-octane and three lightly branched isomers octane (i.e., 2-methylheptane, 3-methylheptane, and 2,5-dimethylhexane). The model is validated against experimental data from a variety of fundamental combustion devices. This new model is used to show how the location and number of methyl branches affects fuel reactivity including laminar flame speed and species formation.

  1. Internal conversion and intersystem crossing pathways in UV excited, isolated uracils and their implications in prebiotic chemistry.

    PubMed

    Yu, Hui; Sanchez-Rodriguez, Jose A; Pollum, Marvin; Crespo-Hernández, Carlos E; Mai, Sebastian; Marquetand, Philipp; González, Leticia; Ullrich, Susanne

    2016-07-27

    The photodynamic properties of molecules determine their ability to survive in harsh radiation environments. As such, the photostability of heterocyclic aromatic compounds to electromagnetic radiation is expected to have been one of the selection pressures influencing the prebiotic chemistry on early Earth. In the present study, the gas-phase photodynamics of uracil, 5-methyluracil (thymine) and 2-thiouracil-three heterocyclic compounds thought to be present during this era-are assessed in the context of their recently proposed intersystem crossing pathways that compete with internal conversion to the ground state. Specifically, time-resolved photoelectron spectroscopy measurements evidence femtosecond to picosecond timescales for relaxation of the singlet (1)ππ* and (1)nπ* states as well as for intersystem crossing to the triplet manifold. Trapping in the excited triplet state and intersystem crossing back to the ground state are investigated as potential factors contributing to the susceptibility of these molecules to ultraviolet photodamage.

  2. Internal conversion and intersystem crossing pathways in UV excited, isolated uracils and their implications in prebiotic chemistry.

    PubMed

    Yu, Hui; Sanchez-Rodriguez, Jose A; Pollum, Marvin; Crespo-Hernández, Carlos E; Mai, Sebastian; Marquetand, Philipp; González, Leticia; Ullrich, Susanne

    2016-07-27

    The photodynamic properties of molecules determine their ability to survive in harsh radiation environments. As such, the photostability of heterocyclic aromatic compounds to electromagnetic radiation is expected to have been one of the selection pressures influencing the prebiotic chemistry on early Earth. In the present study, the gas-phase photodynamics of uracil, 5-methyluracil (thymine) and 2-thiouracil-three heterocyclic compounds thought to be present during this era-are assessed in the context of their recently proposed intersystem crossing pathways that compete with internal conversion to the ground state. Specifically, time-resolved photoelectron spectroscopy measurements evidence femtosecond to picosecond timescales for relaxation of the singlet (1)ππ* and (1)nπ* states as well as for intersystem crossing to the triplet manifold. Trapping in the excited triplet state and intersystem crossing back to the ground state are investigated as potential factors contributing to the susceptibility of these molecules to ultraviolet photodamage. PMID:27189184

  3. Superacid catalysis of light hydrocarbon conversion. Final report, August 26, 1993--August 26, 1996

    SciTech Connect

    Gates, B.C.

    1996-12-31

    Motivated by the goal of finding improved catalysts for low- temperature conversion of light alkanes into fuel components or precursors of fuel components, the researchers have investigated sulfated zirconia and promoted sulfated zirconia for conversion of butane, propane, and ethane. Catalyst performance data for sulfated zirconia promoted with iron and manganese show that it is the most active noncorrosive, nonhalide catalyst known for n-butane isomerization, and it is an excellent candidate catalyst for new low- temperature n-butane isomerization processes to make isobutane, which can be converted by established technology into methyl t-butyl ether (MTBE). Various transition metals have been found to work as promoters of sulfated zirconia for n-butane isomerization. The combination of iron and manganese is the best known combination of promoters yet discovered. The iron- and manganese-promoted sulfated zirconia is also a catalyst for conversion of propane and of ethane. Ethane is converted into ethylene and butanes in the presence of the iron- and manganese-promoted sulfated zirconia; propane is also converted into butane, among other products. However, the activities of the catalyst for these reactions are orders of magnitude less than the activity for n-butane conversion, and there is no evidence that the catalyst would be of practical value for conversion of alkanes lighter than butane. The product distribution data for ethane and propane conversion provide new insights into the nature of the catalyst and its acidity. These data suggest the involvement of Olah superacid chemistry, whereby the catalyst protonates the alkane itself, giving carbonium ions (as transition states). The mechanism of protonation of the alkane may also pertain to the conversion of butane, but there is good evidence that the butane conversion also proceeds via alkene intermediates by conventional mechanisms of carbenium ion formation and rearrangement.

  4. From Alkanes to Carboxylic Acids: Terminal Oxygenation by a Fungal Peroxygenase.

    PubMed

    Olmedo, Andrés; Aranda, Carmen; Del Río, José C; Kiebist, Jan; Scheibner, Katrin; Martínez, Angel T; Gutiérrez, Ana

    2016-09-26

    A new heme-thiolate peroxidase catalyzes the hydroxylation of n-alkanes at the terminal position-a challenging reaction in organic chemistry-with H2 O2 as the only cosubstrate. Besides the primary product, 1-dodecanol, the conversion of dodecane yielded dodecanoic, 12-hydroxydodecanoic, and 1,12-dodecanedioic acids, as identified by GC-MS. Dodecanal could be detected only in trace amounts, and 1,12-dodecanediol was not observed, thus suggesting that dodecanoic acid is the branch point between mono- and diterminal hydroxylation. Simultaneously, oxygenation was observed at other hydrocarbon chain positions (preferentially C2 and C11). Similar results were observed in reactions of tetradecane. The pattern of products formed, together with data on the incorporation of (18) O from the cosubstrate H2 (18) O2 , demonstrate that the enzyme acts as a peroxygenase that is able to catalyze a cascade of mono- and diterminal oxidation reactions of long-chain n-alkanes to give carboxylic acids.

  5. From Alkanes to Carboxylic Acids: Terminal Oxygenation by a Fungal Peroxygenase.

    PubMed

    Olmedo, Andrés; Aranda, Carmen; Del Río, José C; Kiebist, Jan; Scheibner, Katrin; Martínez, Angel T; Gutiérrez, Ana

    2016-09-26

    A new heme-thiolate peroxidase catalyzes the hydroxylation of n-alkanes at the terminal position-a challenging reaction in organic chemistry-with H2 O2 as the only cosubstrate. Besides the primary product, 1-dodecanol, the conversion of dodecane yielded dodecanoic, 12-hydroxydodecanoic, and 1,12-dodecanedioic acids, as identified by GC-MS. Dodecanal could be detected only in trace amounts, and 1,12-dodecanediol was not observed, thus suggesting that dodecanoic acid is the branch point between mono- and diterminal hydroxylation. Simultaneously, oxygenation was observed at other hydrocarbon chain positions (preferentially C2 and C11). Similar results were observed in reactions of tetradecane. The pattern of products formed, together with data on the incorporation of (18) O from the cosubstrate H2 (18) O2 , demonstrate that the enzyme acts as a peroxygenase that is able to catalyze a cascade of mono- and diterminal oxidation reactions of long-chain n-alkanes to give carboxylic acids. PMID:27573441

  6. Superacid Catalyzed Coal Conversion Chemistry. 1st and 2nd Quarterly Technical Progress Reports, September 1, 1983-March 30, 1984.

    DOE R&D Accomplishments Database

    Olah, G. A.

    1984-01-01

    In our laboratories we have previously developed a mild coal conversion process. This involves the use of a superacid system consisting of HF and BF{sub 3} in presence of hydrogen and/or a hydrogen donor solvent. In order to understand the chemistry involved in the process of depolymerization of coal by the HF:BF{sub 3}:H{sub 2} system we are carrying out a systematic study of a number of coal model compounds. The model compounds selected for present study have two benzene rings connected with various bridging units such as alkylidene, ether, sulfide etc. From studies so far carried out it appears that high pyridine extractibilities achieved by treating coal at temperature below 100 degrees C results from the cleavage of bridges such as present in bibenzyl, diphenyl methane, dibenzyl ether, dibenzyl sulfide etc. On the other hand the increased cyclohexane extractibility and distillability observed at relatively higher temperatures and hydrogen pressures reflects the hydrogenation and cleavage of the aromatic backbone in coal structure similar to what is seen in the conversion of model compounds such as biphenyl, diphenyl ether, diphenyl sulfide, anthracene, etc.

  7. Alkane desaturation by concerted double hydrogen atom transfer to benzyne.

    PubMed

    Niu, Dawen; Willoughby, Patrick H; Woods, Brian P; Baire, Beeraiah; Hoye, Thomas R

    2013-09-26

    The removal of two vicinal hydrogen atoms from an alkane to produce an alkene is a challenge for synthetic chemists. In nature, desaturases and acetylenases are adept at achieving this essential oxidative functionalization reaction, for example during the biosynthesis of unsaturated fatty acids, eicosanoids, gibberellins and carotenoids. Alkane-to-alkene conversion almost always involves one or more chemical intermediates in a multistep reaction pathway; these may be either isolable species (such as alcohols or alkyl halides) or reactive intermediates (such as carbocations, alkyl radicals, or σ-alkyl-metal species). Here we report a desaturation reaction of simple, unactivated alkanes that is mechanistically unique. We show that benzynes are capable of the concerted removal of two vicinal hydrogen atoms from a hydrocarbon. The discovery of this exothermic, net redox process was enabled by the simple thermal generation of reactive benzyne intermediates through the hexadehydro-Diels-Alder cycloisomerization reaction of triyne substrates. We are not aware of any single-step, bimolecular reaction in which two hydrogen atoms are simultaneously transferred from a saturated alkane. Computational studies indicate a preferred geometry with eclipsed vicinal C-H bonds in the alkane donor.

  8. Surface chemistry and corrosion behavior of aluminum-copper systems: Air-formed films to complex conversion coatings

    NASA Astrophysics Data System (ADS)

    Chidambaram, Devicharan

    Understanding the mechanism of corrosion inhibition by carcinogenic chromates is critical to the development of environmentally safe coatings containing benign chromate substitutes. An integrated approach to correlate the surface chemistry and corrosion behavior of a wide range of systems has been undertaken. Electrochemical behavior was studied by open circuit potential (OCP) measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). Surface chemistry was studied using variable-angle X-ray photoelectron spectroscopy (VAXPS), X-ray absorption near edge spectroscopy (XANES), secondary ion mass spectroscopy (SIMS), infrared spectroscopy and synchrotron infrared micro spectroscopy (SIRMS) and Raman spectroscopy. Using SIRMS, the ASTM recommended acetone degreasing was shown to initiate pitting of AA2024-T3 via photochemical formation of acetic acid. Due to the known tendency for photoreduction of Cr6+(3d0) following soft X-ray dosage during XPS, a novel method has been developed to prevent this reduction. This method yields, for the first time, an accurate determination of the Cr6+ content of a CCC. The pretreatment of the alloy prior to conversion coating has been shown to have significant influence on the surface intermetallic distribution, composition and corrosion resistance of the initial oxide film and subsequent conversion coating. AlconoxRTM pretreatment was found to result in a highly protective surface film that inhibits the subsequent formation of CCC. The study also shows that coupling of the alloy to platinum during the bromate pretreatment increases the corrosion resistance of the subsequently formed CCC by over an order of magnitude due to reduction in surface copper content. Adsorption of chromate ion on the passive oxide film formed on the metal surface was observed to induce fixed negative charges that inhibit chloride ingress on planar surfaces. While deprotonation of the aluminum hydroxide film by chromate was

  9. Liquid-liquid interfaces of semifluorinated alkane diblock copolymers with water, alkanes, and perfluorinated alkanes.

    SciTech Connect

    Perahia, Dvora, Dr.; Pierce, Flint; Tsige, Mesfin; Grest, Gary Stephen, Dr.

    2008-08-01

    The liquid-liquid interface between semifluorinated alkane diblock copolymers of the form F3C(CF2)n-1-(CH2)m-1CH3 and water, protonated alkanes, and perfluorinated alkanes are studied by fully atomistic molecular dynamics simulations. A modified version of the OPLS-AA (Optimized Parameter for Liquid Simulation All-Atom) force field of Jorgensen et al. has been used to study the interfacial behavior of semifluorinated diblocks. Aqueous interfaces are found to be sharp, with correspondingly large values of the interfacial tension. Due to the reduced hydrophobicity of the protonated block compared to the fluorinated block, hydrogen enhancement is observed at the interface. Water dipoles in the interfacial region are found to be oriented nearly parallel to the liquid-liquid interface. A number of protonated alkanes and perfluorinated alkanes are found to be mutually miscible with the semifluorinated diblocks. For these liquids, interdiffusion follows the expected Fickian behavior, and concentration-dependent diffusivities are determined.

  10. Integrated process for preparing a carboxylic acid from an alkane

    SciTech Connect

    Benderly, Abraham; Chadda, Nitin; Sevon, Douglass

    2011-12-20

    The present invention relates to an integrated process for producing unsaturated carboxylic acids from the corresponding C.sub.2-C.sub.4 alkane. The process begins with performance of thermally integrated dehydrogenation reactions which convert a C.sub.2-C.sub.4 alkane to its corresponding C.sub.2-C.sub.4 alkene, and which involve exothermically converting a portion of an alkane to its corresponding alkene by oxidative dehydrogenation in an exothermic reaction zone, in the presence of oxygen and a suitable catalyst, and then feeding the products of the exothermic reaction zone to an endothermic reaction zone wherein at least a portion of the remaining unconverted alkane is endothermically dehydrogenated to form an additional quantity of the same corresponding alkene, in the presence of carbon dioxide and an other suitable catalyst. The alkene products of the thermally integrated dehydrogenation reactions are then provided to a catalytic vapor phase partial oxidation process for conversion of the alkene to the corresponding unsaturated carboxylic acid or nitrile. Unreacted alkene and carbon dioxide are recovered from the oxidation product stream and recycled back to the thermally integrated dehydrogenation reactions.

  11. Modular and selective biosynthesis of gasoline-range alkanes.

    PubMed

    Sheppard, Micah J; Kunjapur, Aditya M; Prather, Kristala L J

    2016-01-01

    Typical renewable liquid fuel alternatives to gasoline are not entirely compatible with current infrastructure. We have engineered Escherichia coli to selectively produce alkanes found in gasoline (propane, butane, pentane, heptane, and nonane) from renewable substrates such as glucose or glycerol. Our modular pathway framework achieves carbon-chain extension by two different mechanisms. A fatty acid synthesis route is used to generate longer chains heptane and nonane, while a more energy efficient alternative, reverse-β-oxidation, is used for synthesis of propane, butane, and pentane. We demonstrate that both upstream (thiolase) and intermediate (thioesterase) reactions can act as control points for chain-length specificity. Specific free fatty acids are subsequently converted to alkanes using a broad-specificity carboxylic acid reductase and a cyanobacterial aldehyde decarbonylase (AD). The selectivity obtained by different module pairings provides a foundation for tuning alkane product distribution for desired fuel properties. Alternate ADs that have greater activity on shorter substrates improve observed alkane titer. However, even in an engineered host strain that significantly reduces endogenous conversion of aldehyde intermediates to alcohol byproducts, AD activity is observed to be limiting for all chain lengths. Given these insights, we discuss guiding principles for pathway selection and potential opportunities for pathway improvement.

  12. Modular and selective biosynthesis of gasoline-range alkanes.

    PubMed

    Sheppard, Micah J; Kunjapur, Aditya M; Prather, Kristala L J

    2016-01-01

    Typical renewable liquid fuel alternatives to gasoline are not entirely compatible with current infrastructure. We have engineered Escherichia coli to selectively produce alkanes found in gasoline (propane, butane, pentane, heptane, and nonane) from renewable substrates such as glucose or glycerol. Our modular pathway framework achieves carbon-chain extension by two different mechanisms. A fatty acid synthesis route is used to generate longer chains heptane and nonane, while a more energy efficient alternative, reverse-β-oxidation, is used for synthesis of propane, butane, and pentane. We demonstrate that both upstream (thiolase) and intermediate (thioesterase) reactions can act as control points for chain-length specificity. Specific free fatty acids are subsequently converted to alkanes using a broad-specificity carboxylic acid reductase and a cyanobacterial aldehyde decarbonylase (AD). The selectivity obtained by different module pairings provides a foundation for tuning alkane product distribution for desired fuel properties. Alternate ADs that have greater activity on shorter substrates improve observed alkane titer. However, even in an engineered host strain that significantly reduces endogenous conversion of aldehyde intermediates to alcohol byproducts, AD activity is observed to be limiting for all chain lengths. Given these insights, we discuss guiding principles for pathway selection and potential opportunities for pathway improvement. PMID:26556131

  13. Millisecond Oxidation of Alkanes

    SciTech Connect

    Scott Han

    2011-09-30

    This project was undertaken in response to the Department of Energy's call to research and develop technologies 'that will reduce energy consumption, enhance economic competitiveness, and reduce environmental impacts of the domestic chemical industry.' The current technology at the time for producing 140 billion pounds per year of propylene from naphtha and Liquified Petroleum Gas (LPG) relied on energy- and capital-intensive steam crackers and Fluidized Catalytic Cracking (FCC) units. The propylene is isolated from the product stream in a costly separation step and subsequently converted to acrylic acid and other derivatives in separate production facilities. This project proposed a Short Contact Time Reactor (SCTR)-based catalytic oxydehydrogenation process that could convert propane to propylene and acrylic acid in a cost-effective and energy-efficient fashion. Full implementation of this technology could lead to sizeable energy, economic and environmental benefits for the U. S. chemical industry by providing up to 45 trillion BTUs/year, cost savings of $1.8 billion/year and a combined 35 million pounds/year reduction in environmental pollutants such as COx, NOx, and SOx. Midway through the project term, the program directive changed, which approval from the DOE and its review panel, from direct propane oxidation to acrylic acid at millisecond contact times to a two-step process for making acrylic acid from propane. The first step was the primary focus, namely the conversion of propane to propylene in high yields assisted by the presence of CO2. The product stream from step one was then to be fed directly into a commercially practiced propylene-to-acrylic acid tandem reactor system.

  14. Photocatalytic acceptorless alkane dehydrogenation: scope, mechanism, and conquering deactivation with carbon dioxide.

    PubMed

    Chowdhury, Abhishek Dutta; Julis, Jennifer; Grabow, Kathleen; Hannebauer, Bernd; Bentrup, Ursula; Adam, Martin; Franke, Robert; Jackstell, Ralf; Beller, Matthias

    2015-01-01

    Alkane dehydrogenation is of special interest for basic science but also offers interesting opportunities for industry. The existing dehydrogenation methodologies make use of heterogeneous catalysts, which suffer from harsh reaction conditions and a lack of selectivity, whereas homogeneous methodologies rely mostly on unsolicited waste generation from hydrogen acceptors. Conversely, acceptorless photochemical alkane dehydrogenation in the presence of trans-Rh(PMe3 )2 (CO)Cl can be regarded as a more benign and atom efficient alternative. However, this methodology suffers from catalyst deactivation over time. Herein, we provide a detailed investigation of the trans-Rh(PMe3 )2 (CO)Cl-photocatalyzed alkane dehydrogenation using spectroscopic and theoretical investigations. These studies inspired us to utilize CO2 to prevent catalyst deactivation, which leads eventually to improved catalyst turnover numbers in the dehydrogenation of alkanes that include liquid organic hydrogen carriers. PMID:25346450

  15. Modeling SOA production from the oxidation of intermediate volatility alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

    2012-12-01

    Secondary Organic Aerosols (SOA) production and ageing is a multigenerational oxidation process involving the formation of successive organic compounds with higher oxidation degree and lower vapour pressure. This process was investigated using the explicit oxidation model GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere). Results for the C8-C24 n-alkane series show the expected trends, i.e. (i) SOA yield grows with the carbon backbone of the parent hydrocarbon, (ii) SOA yields decreases with the decreasing pre-existing organic aerosol concentration, (iii) the number of generations required to describe SOA production increases when the pre-existing organic aerosol concentration decreases. Most SOA contributors were found to be not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA). Branched alkanes are more prone to fragment in the early stage of the oxidation than their corresponding linear analogues. Fragmentation is expected to alter both the yield and the mean oxidation state of the SOA. Here, GECKO-A is applied to generate highly detailed oxidation schemes for various series of branched and cyclised alkanes. Branching and cyclisation effects on SOA yields and oxidation states will be examined.

  16. Superacid catalysis of light hydrocarbon conversion. Sixth quarterly report, January 1, 1995--March 31, 1995

    SciTech Connect

    Gates, B.C.

    1995-08-01

    Iron- and Manganese-promoted sulfated zirconia is a catalyst for the conversion of propane, but the rate of conversion of propane is much less than the rate of conversion of butane. Whereas this catalyst appears to be a good candidate for practical, industrial conversion of butane, it appears to lack sufficient activity for practical conversion of propane. Perhaps more active catalysts will be useful for propane conversion. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversions; they are consistent with the inference that the catalyst is a superacid and that the chemistry is analogous to. that determined in superacid solutions by G.A. Olah, who was awarded the most recent Nobel Prize in chemistry for his work. The catalyst was tested for conversion of propane at 1 bar, 200--300{degrees}C and propane partial pressures in the range of 0.01--0.05 bar. At 250{degrees}C, catalysis was demonstrated, as the number of propane molecules converted was at least 1 per sulfate group after 16 days of operation in a continues flow reactor. Propane was converted in high yield to butanes, but the conversions were low, for example being only a fraction of a percent at a space velocity of 9.1 {times} 10{sup {minus}7} mol(g of catalysis {center_dot} s) and 250{degrees}C. Coke formation was rapid. The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.

  17. Gas-phase reactions of the bare Th2+ and U2+ ions with small alkanes, CH4, C2H6, and C3H8: experimental and theoretical study of elementary organoactinide chemistry.

    PubMed

    Di Santo, Emanuela; Santos, Marta; Michelini, Maria C; Marçalo, Joaquim; Russo, Nino; Gibson, John K

    2011-02-16

    The gas-phase reactions of two dipositive actinide ions, Th(2+) and U(2+), with CH(4), C(2)H(6), and C(3)H(8) were studied by both experiment and theory. Fourier transform ion cyclotron resonance mass spectrometry was employed to study the bimolecular ion-molecule reactions; the potential energy profiles (PEPs) for the reactions, both observed and nonobserved, were computed by density functional theory (DFT). The experiments revealed that Th(2+) reacts with all three alkanes, including CH(4) to produce ThCH(2)(2+), whereas U(2+) reacts with C(2)H(6) and C(3)H(8), with different product distributions than for Th(2+). The comparative reactivities of Th(2+) and U(2+) toward CH(4) are well explained by the computed PEPs. The PEPs for the reactions with C(2)H(6) effectively rationalize the observed reaction products, ThC(2)H(2)(2+) and UC(2)H(4)(2+). For C(3)H(8) several reaction products were experimentally observed; these and additional potential reaction pathways were computed. The DFT results for the reactions with C(3)H(8) are consistent with the observed reactions and the different products observed for Th(2+) and U(2+); however, several exothermic products which emerge from energetically favorable PEPs were not experimentally observed. The comparison between experiment and theory reveals that DFT can effectively exclude unfavorable reaction pathways, due to energetic barriers and/or endothermic products, and can predict energetic differences in similar reaction pathways for different ions. However, and not surprisingly, a simple evaluation of the PEP features is insufficient to reliably exclude energetically favorable pathways. The computed PEPs, which all proceed by insertion, were used to evaluate the relationship between the energetics of the bare Th(2+) and U(2+) ions and the energies for C-H and C-C activation. It was found that the computed energetics for insertion are entirely consistent with the empirical model which relates insertion efficiency to the

  18. Alkane-Based Urethane Potting Compounds

    NASA Technical Reports Server (NTRS)

    Morris, D. E.

    1986-01-01

    New low viscosity urethanes easily mixed, molded, and outgassed. Alkane-based urethanes resist hydrolysis and oxidation and have excellent dielectric properties. Low-viscosity alkane-based urethane prepolymer prepared by one-step reaction of either isophorone diisocyanate or methyl-bis (4-cyclohexyl isocyanate) with hydrogenated, hydroxy-terminated polybutadiene (HTPBD).

  19. Solutions, Unit 2: Molarity, Molality, Concentration Conversions. A Computer-Enriched Module for Introductory Chemistry. Student's Guide and Teacher's Guide.

    ERIC Educational Resources Information Center

    Bader, Morris

    Presented are the teacher's guide and student manual for one of a series of self-instructional, computer-based learning modules for an introductory, undergraduate chemistry course. The student module for this solution concentration unit includes objectives, prerequisites, pretest, discussion, and 20 problem sets. Included in the teacher's guide…

  20. A Conversion of Methyl Ketones into Acetylenes: A Project for a Problem-Oriented or Microscale Organic Chemistry Course.

    ERIC Educational Resources Information Center

    Silveira, Augustine, Jr.; Orlando, Steven C.

    1988-01-01

    Describes a process for producing terminal or internal alkynes from ketones. Recommends using the experiment to aid in understanding acid-base strength, enolate anion chemistry, reaction at carbon versus oxygen, use of polar aprotic solvents, and elimination and nucleophilic substitution reactions. (ML)

  1. Low-temperature alkane C-H bond activation by zeolites: an in situ solid-state NMR H/D exchange study for a carbenium concerto.

    PubMed

    Haouas, Mohamed; Fink, Gerhard; Taulelle, Francis; Sommer, Jean

    2010-08-01

    Isotopic H/D exchange has been monitored by in situ MAS NMR spectroscopy of 2-[D(14)]methylpentane with H-USY to probe the controversy over the alkane conversion mechanism. The probe molecule has distinct exchangeable sites with different accessibility to the zeolite surface. In the early stages of the process, the regioselectivity of exchange demonstrates that the slow step of the mechanism is controlled by a carbenium ion intermediate. At a later stage of exchange, intramolecular hydride migrations, typical of carbenium chemistry, replace D by H also on other carbon atoms, resulting in a loss of regioselectivity. Therefore, the first and the subsequent steps of the H/D exchange proceed at this temperature through a carbenium intermediate species.

  2. Microsomal preparation from an animal tissue catalyzes release of carbon monoxide from a fatty aldehyde to generate an alkane.

    PubMed

    Cheesbrough, T M; Kolattukudy, P E

    1988-02-25

    Alkanes are widely distributed in nature and impaired alkane synthesis was implicated in certain neurological disorders. However, the mechanism of synthesis of alkanes in animals is unknown. Our search to find a convenient animal tissue to study alkane biosynthesis resulted in the finding that the uropygial gland (a modified sebaceous gland) of the eared grebe (Podiceps nigricollis) produces large amounts of alkanes. These alkanes, which constitute 35-41% of the total lipid produced, are mainly C21, C23, C25, and C27 n-alkanes. Cell free homogenates of this tissue synthesized alkanes from both fatty acid and aldehyde in the absence of O2. Differential centrifugation of the homogenates indicated that this activity was located in the microsomal fraction. With isolated microsomes conversion of fatty acid to alkane required CoA, ATP, and NADH whereas conversion of an aldehyde to alkane did not require the addition of cofactors. That the final step in alkane synthesis is a decarbonylation was shown by the stoichiometric production of heptadecane and CO from octadecanal. CO was identified by adsorption to RhCl [(C6H6)3P]3 and oxidation of the trapped CO to CO2 by watergas shift reaction. The enzyme preparation also catalyzed incorporation of 14C from 14CO into octadecanal showing the reversible nature of the decarbonylase. This decarbonylase had a sharp pH optimum at 7.0, a Kapp of 180 microM and a V1/2 of 90 rho mol/min/mg protein for octadecanal. The enzyme was inhibited by the metal chelators EDTA, O-phenanthroline, and 8-hydroxyquinoline, but not by KCN. It was stimulated nearly 3-fold by 5 microM 2-mercaptoethanol and inhibited by the presence of O2. During the conversion of [1-3H]octadecanal to heptadecane, 3H was lost to water and 3H from 3H2O was incorporated into the alkane generated from unlabeled octadecanal. The mechanism of the decarbonylation and the nature of the enzyme remain to be elucidated.

  3. Exploratory study of coal-conversion chemistry. Quarterly report No. 9, March 20, 1980-June 19, 1980. [Hydroxydiphenylmethane, diphenylether, diphenymethane

    SciTech Connect

    McMillen, Donald F.; Ogier, Walter C.

    1980-11-19

    This report describes work accomplished under two tasks: Task A, Mechanism of Cleavage of Key Bond Types Present in Coals, and Task B, Catalysis of Conversion in CO-H/sub 2/O Systems. Under Task A, the very effective catalysis of carbon-carbon bond cleavage by iron oxides in hydroxydiphenylmethane structures has been further characterized. An electron-transfer mechanism offers the most likely explanation of the observations that (1) alumina and silica-alumina surfaces are less active catalysts than Fe/sub 3/O/sub 4/, (2) meta-hydroxydiphenylmethane is almost as subject to catalysis as para-hydroxydiphenylmethane, (3) diphenyl ether is less subject to Fe/sub 3/O/sub 4/ catalysis than diphenylmethane, and (4) ortho-methoxydiphenylmethane exhibits the same susceptibility to Fe/sub 3/O/sub 4/ catalysis as ortho-hydroxydiphenylmethane. Under Task B, this quarter we have completed the survey of possible metal catalysts present in the Hastelloy C autoclave. We have found that coal conversion in CO-H/sub 2/O systems is effective when metal oxides such as MoO/sub 4//sup =/, Cr/sub 2/O/sub 7//sup =/, and MnO/sub 4//sup -/ are used as catalysts, but there is less or no coal conversion with FeCl/sub 3/ or Ni(CH/sub 3/COO)/sub 2/. While studying the fate of the catalyst after the reaction, we have isolated formate in the water-soluble fraction. This important information could help us in studying the role of formate in coal conversion. During this quarter, we have also studied the influence of reaction time and fresh CO on coal conversion in the presence of a catalyst. A striking result of 67% of benzene-soluble materials was obtained with an equivalent of 6000 ppM of Cr as sodium dichromate.

  4. The anaerobic degradation of gaseous, nonmethane alkanes — From in situ processes to microorganisms

    PubMed Central

    Musat, Florin

    2015-01-01

    The short chain, gaseous alkanes ethane, propane, n- and iso-butane are released in significant amounts into the atmosphere, where they contribute to tropospheric chemistry and ozone formation. Biodegradation of gaseous alkanes by aerobic microorganisms, mostly bacteria and fungi isolated from terrestrial environments, has been known for several decades. The first indications for short chain alkane anaerobic degradation were provided by geochemical studies of deep-sea environments around hydrocarbon seeps, and included the uncoupling of the sulfate-reduction and anaerobic oxidation of methane rates, the consumption of gaseous alkanes in anoxic sediments, or the enrichment in 13C of gases in interstitial water vs. the source gas. Microorganisms able to degrade gaseous alkanes were recently obtained from deep-sea and terrestrial sediments around hydrocarbon seeps. Up to date, only sulfate-reducing pure or enriched cultures with ethane, propane and n-butane have been reported. The only pure culture presently available, strain BuS5, is affiliated to the Desulfosarcina–Desulfococcus cluster of the Deltaproteobacteria. Other phylotypes involved in gaseous alkane degradation have been identified based on stable-isotope labeling and whole-cell hybridization. Under anoxic conditions, propane and n-butane are activated similar to the higher alkanes, by homolytic cleavage of the C—H bond of a subterminal carbon atom, and addition of the ensuing radical to fumarate, yielding methylalkylsuccinates. An additional mechanism of activation at the terminal carbon atoms was demonstrated for propane, which could in principle be employed also for the activation of ethane. PMID:25904994

  5. The anaerobic degradation of gaseous, nonmethane alkanes - From in situ processes to microorganisms.

    PubMed

    Musat, Florin

    2015-01-01

    The short chain, gaseous alkanes ethane, propane, n- and iso-butane are released in significant amounts into the atmosphere, where they contribute to tropospheric chemistry and ozone formation. Biodegradation of gaseous alkanes by aerobic microorganisms, mostly bacteria and fungi isolated from terrestrial environments, has been known for several decades. The first indications for short chain alkane anaerobic degradation were provided by geochemical studies of deep-sea environments around hydrocarbon seeps, and included the uncoupling of the sulfate-reduction and anaerobic oxidation of methane rates, the consumption of gaseous alkanes in anoxic sediments, or the enrichment in (13)C of gases in interstitial water vs. the source gas. Microorganisms able to degrade gaseous alkanes were recently obtained from deep-sea and terrestrial sediments around hydrocarbon seeps. Up to date, only sulfate-reducing pure or enriched cultures with ethane, propane and n-butane have been reported. The only pure culture presently available, strain BuS5, is affiliated to the Desulfosarcina-Desulfococcus cluster of the Deltaproteobacteria. Other phylotypes involved in gaseous alkane degradation have been identified based on stable-isotope labeling and whole-cell hybridization. Under anoxic conditions, propane and n-butane are activated similar to the higher alkanes, by homolytic cleavage of the C-H bond of a subterminal carbon atom, and addition of the ensuing radical to fumarate, yielding methylalkylsuccinates. An additional mechanism of activation at the terminal carbon atoms was demonstrated for propane, which could in principle be employed also for the activation of ethane. PMID:25904994

  6. Environmental green chemistry as defined by photocatalysis.

    PubMed

    Herrmann, J-M; Duchamp, C; Karkmaz, M; Hoai, Bui Thu; Lachheb, H; Puzenat, E; Guillard, C

    2007-07-31

    Photocatalysis is efficient in several fields. Firstly, in selective mild oxidation: oxidation of gas and liquid hydrocarbons (alkanes, alkenes, cyclo-alkanes, aromatics) into aldehydes and ketons. Primary and secondary alcohols are also oxidized into their corresponding aldehydes or ketones. The high selectivity was ascribed to a photoactive neutral, atomic oxygen species. Once platinized (only 0.5wt.% Pt) titania may catalyze reactions involving hydrogen (deuterium-alkane isotopic exchange and alcohol dehydrogenation). For fine chemicals, high initial selectivities enable titania to address most of the twelve principles of "green chemistry", such as the synthesis of 4-tert-butyl-benzaldehyde, an important intermediate in perfume industry by direct selective oxidation of 4-tert-butyl-toluene with air. A new field recently appeared: thio-photocatalysis. Oxygen was replaced by sulfur, using H(2)S as a convenient and reactive source. For instance, the conversion of propene in 1-propanthiol was successfully obtained. The reaction was performed using either CdS or TiO(2). The latter was much more active than CdS. In environmental photocatalysis, titania becomes a total oxidation catalyst once in presence of water because of the photogeneration of OH radicals by neutralization of OH(-) surface groups by positive holes. Many toxic inorganic ions are oxidized in their harmless upper oxidized state. The total degradation of organic pollutants (pesticides, herbicides, insecticides, fungicides, dyes, etc. ...) is the main field of water photocatalytic decontamination. The UVA solar spectrum can de advantageously used as demonstrated by many campaigns performed in the solar pilot plant at the "Plataforma Solar de Almeria" (Spain). PMID:17532130

  7. Environmental green chemistry as defined by photocatalysis.

    PubMed

    Herrmann, J-M; Duchamp, C; Karkmaz, M; Hoai, Bui Thu; Lachheb, H; Puzenat, E; Guillard, C

    2007-07-31

    Photocatalysis is efficient in several fields. Firstly, in selective mild oxidation: oxidation of gas and liquid hydrocarbons (alkanes, alkenes, cyclo-alkanes, aromatics) into aldehydes and ketons. Primary and secondary alcohols are also oxidized into their corresponding aldehydes or ketones. The high selectivity was ascribed to a photoactive neutral, atomic oxygen species. Once platinized (only 0.5wt.% Pt) titania may catalyze reactions involving hydrogen (deuterium-alkane isotopic exchange and alcohol dehydrogenation). For fine chemicals, high initial selectivities enable titania to address most of the twelve principles of "green chemistry", such as the synthesis of 4-tert-butyl-benzaldehyde, an important intermediate in perfume industry by direct selective oxidation of 4-tert-butyl-toluene with air. A new field recently appeared: thio-photocatalysis. Oxygen was replaced by sulfur, using H(2)S as a convenient and reactive source. For instance, the conversion of propene in 1-propanthiol was successfully obtained. The reaction was performed using either CdS or TiO(2). The latter was much more active than CdS. In environmental photocatalysis, titania becomes a total oxidation catalyst once in presence of water because of the photogeneration of OH radicals by neutralization of OH(-) surface groups by positive holes. Many toxic inorganic ions are oxidized in their harmless upper oxidized state. The total degradation of organic pollutants (pesticides, herbicides, insecticides, fungicides, dyes, etc. ...) is the main field of water photocatalytic decontamination. The UVA solar spectrum can de advantageously used as demonstrated by many campaigns performed in the solar pilot plant at the "Plataforma Solar de Almeria" (Spain).

  8. Direct hydrodeoxygenation of raw woody biomass into liquid alkanes.

    PubMed

    Xia, Qineng; Chen, Zongjia; Shao, Yi; Gong, Xueqing; Wang, Haifeng; Liu, Xiaohui; Parker, Stewart F; Han, Xue; Yang, Sihai; Wang, Yanqin

    2016-03-30

    Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with mass yields up to 28.1 wt% over a multifunctional Pt/NbOPO4 catalyst in cyclohexane. The superior performance of this catalyst allows simultaneous conversion of cellulose, hemicellulose and, more significantly, lignin fractions in the wood sawdust into hexane, pentane and alkylcyclohexanes, respectively. Investigation on the molecular mechanism reveals that a synergistic effect between Pt, NbOx species and acidic sites promotes this highly efficient hydrodeoxygenation of bulk lignocellulose. No chemical pretreatment of the raw woody biomass or separation is required for this one-pot process, which opens a general and energy-efficient route for converting raw lignocellulose into valuable alkanes.

  9. Direct hydrodeoxygenation of raw woody biomass into liquid alkanes.

    PubMed

    Xia, Qineng; Chen, Zongjia; Shao, Yi; Gong, Xueqing; Wang, Haifeng; Liu, Xiaohui; Parker, Stewart F; Han, Xue; Yang, Sihai; Wang, Yanqin

    2016-01-01

    Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with mass yields up to 28.1 wt% over a multifunctional Pt/NbOPO4 catalyst in cyclohexane. The superior performance of this catalyst allows simultaneous conversion of cellulose, hemicellulose and, more significantly, lignin fractions in the wood sawdust into hexane, pentane and alkylcyclohexanes, respectively. Investigation on the molecular mechanism reveals that a synergistic effect between Pt, NbOx species and acidic sites promotes this highly efficient hydrodeoxygenation of bulk lignocellulose. No chemical pretreatment of the raw woody biomass or separation is required for this one-pot process, which opens a general and energy-efficient route for converting raw lignocellulose into valuable alkanes. PMID:27025898

  10. Direct hydrodeoxygenation of raw woody biomass into liquid alkanes

    PubMed Central

    Xia, Qineng; Chen, Zongjia; Shao, Yi; Gong, Xueqing; Wang, Haifeng; Liu, Xiaohui; Parker, Stewart F.; Han, Xue; Yang, Sihai; Wang, Yanqin

    2016-01-01

    Being the only sustainable source of organic carbon, biomass is playing an ever-increasingly important role in our energy landscape. The conversion of renewable lignocellulosic biomass into liquid fuels is particularly attractive but extremely challenging due to the inertness and complexity of lignocellulose. Here we describe the direct hydrodeoxygenation of raw woods into liquid alkanes with mass yields up to 28.1 wt% over a multifunctional Pt/NbOPO4 catalyst in cyclohexane. The superior performance of this catalyst allows simultaneous conversion of cellulose, hemicellulose and, more significantly, lignin fractions in the wood sawdust into hexane, pentane and alkylcyclohexanes, respectively. Investigation on the molecular mechanism reveals that a synergistic effect between Pt, NbOx species and acidic sites promotes this highly efficient hydrodeoxygenation of bulk lignocellulose. No chemical pretreatment of the raw woody biomass or separation is required for this one-pot process, which opens a general and energy-efficient route for converting raw lignocellulose into valuable alkanes. PMID:27025898

  11. Supported organoiridium catalysts for alkane dehydrogenation

    SciTech Connect

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  12. Catalytic dehydroaromatization of n-alkanes by pincer-ligated iridium complexes

    NASA Astrophysics Data System (ADS)

    Ahuja, Ritu; Punji, Benudhar; Findlater, Michael; Supplee, Carolyn; Schinski, William; Brookhart, Maurice; Goldman, Alan S.

    2011-02-01

    Aromatic hydrocarbons are among the most important building blocks in the chemical industry. Benzene, toluene and xylenes are obtained from the high temperature thermolysis of alkanes. Higher alkylaromatics are generally derived from arene-olefin coupling, which gives branched products—that is, secondary alkyl arenes—with olefins higher than ethylene. The dehydrogenation of acyclic alkanes to give alkylaromatics can be achieved using heterogeneous catalysts at high temperatures, but with low yields and low selectivity. We present here the first catalytic conversion of n-alkanes to alkylaromatics using homogeneous or molecular catalysts—specifically ‘pincer’-ligated iridium complexes—and olefinic hydrogen acceptors. For example, the reaction of n-octane affords up to 86% yield of aromatic product, primarily o-xylene and secondarily ethylbenzene. In the case of n-decane and n-dodecane, the resulting alkylarenes are exclusively unbranched (that is, n-alkyl-substituted), with selectivity for the corresponding o-(n-alkyl)toluene.

  13. Exploratory study of coal-conversion chemistry. Quarterly report, June 20, 1980-September 19, 1980. [Diphenylmethane, diphenyl ether

    SciTech Connect

    Not Available

    1981-03-04

    This report describes work accomplished under two task: Task A, Mechanism of Cleavage of Key Bond types Present in Coals, and Task B, Catalysis of Conversion in CO-H/sub 2/O Systems. Under Task A, we have made additional measurements of catalytic carbon-carbon and carbon-oxygen bond cleavage in coal-related diphenylmethane and diphenyl ether structures. The results provide further support for, but do not definitely confirm, the tentative conclusion that the highly effective iron oxide catalysts involves oxidation to radical cation species. The homogeneous scission of carbon-oxygen bonds in diphenyl ether structure has also been studied. In the Task B studies of CO-H/sub 2/O systems, we typically obtain 50% benzene-soluble product material from 20 min. reaction of beneficiated Illinois No. 6 coal. This conversion level is obtained with aqueous solutions either at a starting pH above 12.6 or in neutral solutions with water-soluble catalysts present. We have studied a number of catalysts, including the potassium or sodium salts of molybdate, chromate, manganate, and tungstate; all are effective in the 3000 to 6000 ppM range. A striking result is that sodium nitrate at 6000 ppM is as effective as the metal salts. We found that the nitrate was converted to ammonium ion; also, formate was detected in the product aqueous phase. Finally, we find that catalytic quantities of sodium formate in CO/H/sub 2/O at pH 7 are effective in the conversion. However, in a control run in N/sub 2//H/sub 2/O, with a quantity of sodium formate equivalent to twice the molar quantity of hydrogen transferred to the coal in a successful run, the coal was converted to a product totally insoluble in benzene and with a lower hydrogen content than the starting coal.

  14. Solar photothermochemical alkane reverse combustion

    PubMed Central

    Chanmanee, Wilaiwan; Islam, Mohammad Fakrul; Dennis, Brian H.; MacDonnell, Frederick M.

    2016-01-01

    A one-step, gas-phase photothermocatalytic process for the synthesis of hydrocarbons, including liquid alkanes, aromatics, and oxygenates, with carbon numbers (Cn) up to C13, from CO2 and water is demonstrated in a flow photoreactor operating at elevated temperatures (180–200 °C) and pressures (1–6 bar) using a 5% cobalt on TiO2 catalyst and under UV irradiation. A parametric study of temperature, pressure, and partial pressure ratio revealed that temperatures in excess of 160 °C are needed to obtain the higher Cn products in quantity and that the product distribution shifts toward higher Cn products with increasing pressure. In the best run so far, over 13% by mass of the products were C5+ hydrocarbons and some of these, i.e., octane, are drop-in replacements for existing liquid hydrocarbons fuels. Dioxygen was detected in yields ranging between 64% and 150%. In principle, this tandem photochemical–thermochemical process, fitted with a photocatalyst better matched to the solar spectrum, could provide a cheap and direct method to produce liquid hydrocarbons from CO2 and water via a solar process which uses concentrated sunlight for both photochemical excitation to generate high-energy intermediates and heat to drive important thermochemical carbon-chain-forming reactions. PMID:26903631

  15. Solar photothermochemical alkane reverse combustion.

    PubMed

    Chanmanee, Wilaiwan; Islam, Mohammad Fakrul; Dennis, Brian H; MacDonnell, Frederick M

    2016-03-01

    A one-step, gas-phase photothermocatalytic process for the synthesis of hydrocarbons, including liquid alkanes, aromatics, and oxygenates, with carbon numbers (Cn) up to C13, from CO2 and water is demonstrated in a flow photoreactor operating at elevated temperatures (180-200 °C) and pressures (1-6 bar) using a 5% cobalt on TiO2 catalyst and under UV irradiation. A parametric study of temperature, pressure, and partial pressure ratio revealed that temperatures in excess of 160 °C are needed to obtain the higher Cn products in quantity and that the product distribution shifts toward higher Cn products with increasing pressure. In the best run so far, over 13% by mass of the products were C5+ hydrocarbons and some of these, i.e., octane, are drop-in replacements for existing liquid hydrocarbons fuels. Dioxygen was detected in yields ranging between 64% and 150%. In principle, this tandem photochemical-thermochemical process, fitted with a photocatalyst better matched to the solar spectrum, could provide a cheap and direct method to produce liquid hydrocarbons from CO2 and water via a solar process which uses concentrated sunlight for both photochemical excitation to generate high-energy intermediates and heat to drive important thermochemical carbon-chain-forming reactions.

  16. Gas-phase chemistry during the conversion of cyclohexane to carbon: Flow reactor studies at low and intermediate pressure

    SciTech Connect

    Osterheld, T.H.; Allendorf, M.D.; Larson, R.

    1995-07-01

    The gas-phase branching during the conversion of cyclohexane to solid carbon has been measured in a high-temperature-flow reactor. The experiments show that cyclohexane decomposes into a broad distribution of hydrocarbons that further decompose into the more kinetically stable products hydrogen, methane, acetylene, ethylene, benzene, and PAH. At 1363 K, the evolution to these species occurs quickly. We also observe the buildup of significant amounts of aromatic molecules at later stages in the decomposition, with as much as 15% of the total carbon in PAH and 25% in benzene. At later stages, the gas-phase molecules react slowly, even though the system is not at equilibrium, because of their kinetic stability and the smaller radical pool. The decomposition does not appear to depend sensitively on pressure in the regime of 25 to 250 torr. Thus, to a first approximation, these results can be extrapolated to atmospheric pressure.

  17. Structural insights into diversity and n-alkane biodegradation mechanisms of alkane hydroxylases

    PubMed Central

    Ji, Yurui; Mao, Guannan; Wang, Yingying; Bartlam, Mark

    2013-01-01

    Environmental microbes utilize four degradation pathways for the oxidation of n-alkanes. Although the enzymes degrading n-alkanes in different microbes may vary, enzymes functioning in the first step in the aerobic degradation of alkanes all belong to the alkane hydroxylases. Alkane hydroxylases are a class of enzymes that insert oxygen atoms derived from molecular oxygen into different sites of the alkane terminus (or termini) depending on the type of enzymes. In this review, we summarize the different types of alkane hydroxylases, their degrading steps, and compare typical enzymes from various classes with regard to their three-dimensional structures, in order to provide insights into how the enzymes mediate their different roles in the degradation of n-alkanes and what determines their different substrate ranges. Through the above analyzes, the degrading mechanisms of enzymes can be elucidated and molecular biological methods can be utilized to expand their catalytic roles in the petrochemical industry or in bioremediation of oil-contaminated environments. PMID:23519435

  18. Gas-phase study of Fe sup + -benzyne with alkanes

    SciTech Connect

    Yongqing Huang; Freiser, B.S. )

    1989-03-29

    The unimolecular chemistry of Fe{sup +}-benzyne and its reactivity with small alkanes in the gas phase are studied by Fourier transform mass spectrometry (FTMS). Collision-induced dissociation of Fe{sup +}-benzyne yields benzyne loss exclusively. In contrast, photodissociation of Fe{sup +}-benzyne yields not only cleavage of benzyne from Fe{sup +}, but competitive loss of C{sub 2}H{sub 2} and C{sub 4}H{sub 2} as well. The Fe{sup +}-benzyne is formed from chlorobenzene by loss of HCl. This dehydrochlorination of chlorobenzene also occurs in secondary reactions up to six times forming products of the type Fe{sup +}-polyphenylene. Fe{sup +}-benzyne reacts with alkanes larger than methane to form a wide variety of product ions by mechanisms including hydrogenation and methanation of the benzyne ligand. All of the product ions can be explained by mechanisms based on Fe{sup +} insertion into either C-C or C-H bonds as the reaction-initiating step, followed by either alkyl or H migration from Fe{sup +} onto the benzyne ligand or, alternatively, by the migratory insertion of benzyne into a metal-carbon or metal-hydrogen bond. Photodissociation and ion-molecule reaction studies yield a value for the metal-ligand bond energy of D{degree} (Fe{sup +}-benzyne) = 76 {plus minus} 10 kcal/mol.

  19. Role of precursor chemistry in the direct fluorination to form titanium based conversion anodes for lithium ion batteries

    SciTech Connect

    Adcock, Jamie; Dai, Sheng; Veith, Gabriel M.; Bridges, Craig A.; Powell, Jonathan M.

    2015-10-13

    In this study, a new synthetic route for the formation of titanium oxydifluoride (TiOF2) through the process of direct fluorination via a fluidized bed reactor system and the associated electrochemical properties of the powders formed from this approach are reported. The flexibility of this synthetic route was demonstrated using precursor powders of titanium dioxide (TiO2) nanoparticles, as well as a reduced TiOxNy. An advantage of this synthetic method is the ability to directly control the extent of fluorination as a function of reaction temperature and time. The reversible capacity of TiOF2 anodes was found to depend greatly upon the precursor employed. The TiOF2 synthesized from TiO2 and TiOxNy showed reversible capacities of 300 mAh g-1 and 440 mAh g-1, respectively, over 100 cycles. The higher reversible capacity of the TiOF2 powders derived from TiOxNy likely relate to the partial reduction of the Ti in the fluorinated electrode material, highlighting a route to optimize the properties of conversion electrode materials.

  20. Role of precursor chemistry in the direct fluorination to form titanium based conversion anodes for lithium ion batteries

    DOE PAGES

    Adcock, Jamie; Dai, Sheng; Veith, Gabriel M.; Bridges, Craig A.; Powell, Jonathan M.

    2015-10-13

    In this study, a new synthetic route for the formation of titanium oxydifluoride (TiOF2) through the process of direct fluorination via a fluidized bed reactor system and the associated electrochemical properties of the powders formed from this approach are reported. The flexibility of this synthetic route was demonstrated using precursor powders of titanium dioxide (TiO2) nanoparticles, as well as a reduced TiOxNy. An advantage of this synthetic method is the ability to directly control the extent of fluorination as a function of reaction temperature and time. The reversible capacity of TiOF2 anodes was found to depend greatly upon the precursormore » employed. The TiOF2 synthesized from TiO2 and TiOxNy showed reversible capacities of 300 mAh g-1 and 440 mAh g-1, respectively, over 100 cycles. The higher reversible capacity of the TiOF2 powders derived from TiOxNy likely relate to the partial reduction of the Ti in the fluorinated electrode material, highlighting a route to optimize the properties of conversion electrode materials.« less

  1. Microbial production of short-chain alkanes.

    PubMed

    Choi, Yong Jun; Lee, Sang Yup

    2013-10-24

    Increasing concerns about limited fossil fuels and global environmental problems have focused attention on the need to develop sustainable biofuels from renewable resources. Although microbial production of diesel has been reported, production of another much in demand transport fuel, petrol (gasoline), has not yet been demonstrated. Here we report the development of platform Escherichia coli strains that are capable of producing short-chain alkanes (SCAs; petrol), free fatty acids (FFAs), fatty esters and fatty alcohols through the fatty acyl (acyl carrier protein (ACP)) to fatty acid to fatty acyl-CoA pathway. First, the β-oxidation pathway was blocked by deleting the fadE gene to prevent the degradation of fatty acyl-CoAs generated in vivo. To increase the formation of short-chain fatty acids suitable for subsequent conversion to SCAs in vivo, the activity of 3-oxoacyl-ACP synthase (FabH), which is inhibited by unsaturated fatty acyl-ACPs, was enhanced to promote the initiation of fatty acid biosynthesis by deleting the fadR gene; deletion of the fadR gene prevents upregulation of the fabA and fabB genes responsible for unsaturated fatty acids biosynthesis. A modified thioesterase was used to convert short-chain fatty acyl-ACPs to the corresponding FFAs, which were then converted to SCAs by the sequential reactions of E. coli fatty acyl-CoA synthetase, Clostridium acetobutylicum fatty acyl-CoA reductase and Arabidopsis thaliana fatty aldehyde decarbonylase. The final engineered strain produced up to 580.8 mg l(-1) of SCAs consisting of nonane (327.8 mg l(-1)), dodecane (136.5 mg l(-1)), tridecane (64.8 mg l(-1)), 2-methyl-dodecane (42.8 mg l(-1)) and tetradecane (8.9 mg l(-1)), together with small amounts of other hydrocarbons. Furthermore, this platform strain could produce short-chain FFAs using a fadD-deleted strain, and short-chain fatty esters by introducing the Acinetobacter sp. ADP1 wax ester synthase (atfA) and the E. coli mutant

  2. Enzymes and genes involved in aerobic alkane degradation

    PubMed Central

    Wang, Wanpeng; Shao, Zongze

    2013-01-01

    Alkanes are major constituents of crude oil. They are also present at low concentrations in diverse non-contaminated because many living organisms produce them as chemo-attractants or as protecting agents against water loss. Alkane degradation is a widespread phenomenon in nature. The numerous microorganisms, both prokaryotic and eukaryotic, capable of utilizing alkanes as a carbon and energy source, have been isolated and characterized. This review summarizes the current knowledge of how bacteria metabolize alkanes aerobically, with a particular emphasis on the oxidation of long-chain alkanes, including factors that are responsible for chemotaxis to alkanes, transport across cell membrane of alkanes, the regulation of alkane degradation gene and initial oxidation. PMID:23755043

  3. The effect of environmental factors on stable isotopic composition of n-alkanes in Mediterranean olive oils

    NASA Astrophysics Data System (ADS)

    Pedentchouk, Nikolai; Mihailova, Alina; Abbado, Dimitri

    2014-05-01

    Traceability of the geographic origin of olive oils is an important issue from both commercial and health perspectives. This study evaluates the impact of environmental factors on stable C and H isotope compositions of n-alkanes in extra virgin olive oils from Croatia, France, Greece, Italy, Morocco, Portugal, Slovenia, and Spain. The data are used to investigate the applicability of stable isotope methodology for olive oil regional classification in the Mediterranean region. Analysis of stable C isotope composition of n-C29 alkane showed that extra virgin olive oils from Portugal and Spain have the most positive n-C29 alkane delta13C values. Conversely, olive oils from Slovenia, northern and central Italy are characterized by the most negative values. Overall, the n-C29 alkane delta13C values show a positive correlation with the mean air temperature during August-December and a negative correlation with the mean relative humidity during these months. Analysis of stable H isotope composition of n-C29 alkane revealed that the deltaD values are the most positive in olive oils from Greece and Morocco and the most negative in oils from northern Italy. The deltaD values of oils show significant correlation with all the analyses geographical parameters: the mean air temperature and relative humidity during August-December, the total amount of rainfall (the same months) and the annual deltaD values of precipitation. As predictor variables in the Categorical Data Analysis, the n-C29 alkane deltaD values show the most significant discriminative power, followed by the n-C29 alkane delta13C values. Overall, 93.4% of olive oil samples have been classified correctly into one of the production regions. Our findings suggest that an integrated analysis of C and H isotope compositions of n-alkanes extracted from extra virgin olive oil could become a useful tool for geographical provenancing of this highly popular food commodity.

  4. Cool-flame Extinction During N-Alkane Droplet Combustion in Microgravity

    NASA Technical Reports Server (NTRS)

    Nayagam, Vedha; Dietrich, Daniel L.; Hicks, Michael C.; Williams, Forman A.

    2014-01-01

    Recent droplet combustion experiments onboard the International Space Station (ISS) have revealed that large n-alkane droplets can continue to burn quasi-steadily following radiative extinction in a low-temperature regime, characterized by negative-temperaturecoefficient (NTC) chemistry. In this study we report experimental observations of n-heptane, n-octane, and n-decane droplets of varying initial sizes burning in oxygen/nitrogen/carbon dioxide and oxygen/helium/nitrogen environments at 1.0, 0.7, and 0.5 atmospheric pressures. The oxygen concentration in these tests varied in the range of 14% to 25% by volume. Large n-alkane droplets exhibited quasi-steady low-temperature burning and extinction following radiative extinction of the visible flame while smaller droplets burned to completion or disruptively extinguished. A vapor-cloud formed in most cases slightly prior to or following the "cool flame" extinction. Results for droplet burning rates in both the hot-flame and cool-flame regimes as well as droplet extinction diameters at the end of each stage are presented. Time histories of radiant emission from the droplet captured using broadband radiometers are also presented. Remarkably the "cool flame" extinction diameters for all the three n-alkanes follow a trend reminiscent of the ignition delay times observed in previous studies. The similarities and differences among the n-alkanes during "cool flame" combustion are discussed using simplified theoretical models of the phenomenon

  5. Improved Alkane Production in Nitrogen-Fixing and Halotolerant Cyanobacteria via Abiotic Stresses and Genetic Manipulation of Alkane Synthetic Genes.

    PubMed

    Kageyama, Hakuto; Waditee-Sirisattha, Rungaroon; Sirisattha, Sophon; Tanaka, Yoshito; Mahakhant, Aparat; Takabe, Teruhiro

    2015-07-01

    Cyanobacteria possess the unique capacity to produce alkane. In this study, effects of nitrogen deficiency and salt stress on biosynthesis of alkanes were investigated in three kinds of cyanobacteria. Intracellular alkane accumulation was increased in nitrogen-fixing cyanobacterium Anabaena sp. PCC7120, but decreased in non-diazotrophic cyanobacterium Synechococcus elongatus PCC7942 and constant in a halotolerant cyanobacterium Aphanothece halophytica under nitrogen-deficient condition. We also found that salt stress increased alkane accumulation in Anabaena sp. PCC7120 and A. halophytica. The expression levels of two alkane synthetic genes were not upregulated significantly under nitrogen deficiency or salt stress in Anabaena sp. PCC7120. The transformant Anabaena sp. PCC7120 cells with additional alkane synthetic gene set from A. halophytica increased intracellular alkane accumulation level compared to control cells. These results provide a prospect to improve bioproduction of alkanes in nitrogen-fixing halotolerant cyanobacteria via abiotic stresses and genetic engineering.

  6. Nitrated metalloporphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1994-01-18

    Compositions of matter comprising nitro-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has nitro groups attached thereto in meso and/or [beta]-pyrrolic positions.

  7. Reflectance spectroscopy of organic compounds: 1. Alkanes

    USGS Publications Warehouse

    Clark, R.N.; Curchin, J.M.; Hoefen, T.M.; Swayze, G.A.

    2009-01-01

    Reflectance spectra of the organic compounds comprising the alkane series are presented from the ultraviolet to midinfrared, 0.35 to 15.5 /??m. Alkanes are hydrocarbon molecules containing only single carbon-carbon bonds, and are found naturally on the Earth and in the atmospheres of the giant planets and Saturn's moon, Titan. This paper presents the spectral properties of the alkanes as the first in a series of papers to build a spectral database of organic compounds for use in remote sensing studies. Applications range from mapping the environment on the Earth, to the search for organic molecules and life in the solar system and throughout the. universe. We show that the spectral reflectance properties of organic compounds are rich, with major diagnostic spectral features throughout the spectral range studied. Little to no spectral change was observed as a function of temperature and only small shifts and changes in the width of absorption bands were observed between liquids and solids, making remote detection of spectral properties throughout the solar system simpler. Some high molecular weight organic compounds contain single-bonded carbon chains and have spectra similar to alkanes even ' when they fall into other families. Small spectral differences are often present allowing discrimination among some compounds, further illustrating the need to catalog spectral properties for accurate remote sensing identification with spectroscopy.

  8. Nitrated metalloporphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1992-01-01

    Alkanes are oxidized by contact with oxygen-containing gas in the presence as catalyst of a metalloporphyrin in which hydrogen atoms in the porphyrin ring have been replaced with one or more nitro groups. Hydrogen atoms in the porphyrin ring may also be substituted with halogen atoms.

  9. Nitrated metalloporphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1994-01-01

    Compositions of matter comprising nitro-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has nitro groups attached thereto in meso and/or .beta.-pyrrolic positions.

  10. Accelerated Molecular Dynamics Simulation of Alkane Desorption

    NASA Astrophysics Data System (ADS)

    McLaughlin, Kelly; Fichthorn, Kristen

    2006-03-01

    Thermal desorption has been the focus of much surface science research. Studies of alkanes on graphite^1 and gold^2 have shown prefactors that are constant with alkane chain length but vary by over six orders of magnitude. Other studies on magnesium oxide^3 and gold^4 show a prefactor that increases with increasing chain length. We have developed an all-atom model to study alkane desorption from graphite. Transition state theory is used to obtain rate constants from the simulation. Accelerated MD is used to extend the desorption simulation to experimentally relevant temperatures. Our results show a prefactor that increases with increasing chain length. We predict that it will become constant as internal conformational changes occur significantly. We examine the effect of desorption environment through varying the alkane surface coverage. 1. K.R. Paserba and A.J. Gellman, J. Chem. Phys. 115, 6737 (2001). 2. S.M. Wetterer et al., J. Phys. Chem. 102, 9266 (1998). 3. S.L. Tait et al., J. Chem. Phys. 122, 164707 (2005). 4. K.A. Fichthorn and R.A. Miron, Phys. Rev. Lett. 89, 196103 (2002).

  11. Interrogation of Chesapeake Bay sediment microbial communities for intrinsic alkane-utilizing potential under anaerobic conditions.

    PubMed

    Johnson, Jamie M; Wawrik, Boris; Isom, Catherine; Boling, Wilford B; Callaghan, Amy V

    2015-02-01

    Based on the transient exposure of Chesapeake Bay sediments to hydrocarbons and the metabolic versatility of known anaerobic alkane-degrading microorganisms, it was hypothesized that distinct Bay sediment communities, governed by geochemical gradients, would have intrinsic alkane-utilizing potential under sulfate-reducing and/or methanogenic conditions. Sediment cores were collected along a transect of the Bay. Community DNA was interrogated via pyrosequencing of 16S rRNA genes, PCR of anaerobic hydrocarbon activation genes, and qPCR of 16S rRNA genes and genes involved in sulfate reduction/methanogenesis. Site sediments were used to establish microcosms amended with n-hexadecane under sulfate-reducing and methanogenic conditions. Sequencing of 16S rRNA genes indicated that sediments associated with hypoxic water columns contained significantly greater proportions of Bacteria and Archaea consistent with syntrophic degradation of organic matter and methanogenesis compared to less reduced sediments. Microbial taxa frequently associated with hydrocarbon-degrading communities were found throughout the Bay, and the genetic potential for hydrocarbon metabolism was demonstrated via the detection of benzyl-(bssA) and alkylsuccinate synthase (assA) genes. Although microcosm studies did not indicate sulfidogenic alkane degradation, the data suggested that methanogenic conversion of alkanes was occurring. These findings highlight the potential role that anaerobic microorganisms could play in the bioremediation of hydrocarbons in the Bay. PMID:25764556

  12. Interrogation of Chesapeake Bay sediment microbial communities for intrinsic alkane-utilizing potential under anaerobic conditions.

    PubMed

    Johnson, Jamie M; Wawrik, Boris; Isom, Catherine; Boling, Wilford B; Callaghan, Amy V

    2015-02-01

    Based on the transient exposure of Chesapeake Bay sediments to hydrocarbons and the metabolic versatility of known anaerobic alkane-degrading microorganisms, it was hypothesized that distinct Bay sediment communities, governed by geochemical gradients, would have intrinsic alkane-utilizing potential under sulfate-reducing and/or methanogenic conditions. Sediment cores were collected along a transect of the Bay. Community DNA was interrogated via pyrosequencing of 16S rRNA genes, PCR of anaerobic hydrocarbon activation genes, and qPCR of 16S rRNA genes and genes involved in sulfate reduction/methanogenesis. Site sediments were used to establish microcosms amended with n-hexadecane under sulfate-reducing and methanogenic conditions. Sequencing of 16S rRNA genes indicated that sediments associated with hypoxic water columns contained significantly greater proportions of Bacteria and Archaea consistent with syntrophic degradation of organic matter and methanogenesis compared to less reduced sediments. Microbial taxa frequently associated with hydrocarbon-degrading communities were found throughout the Bay, and the genetic potential for hydrocarbon metabolism was demonstrated via the detection of benzyl-(bssA) and alkylsuccinate synthase (assA) genes. Although microcosm studies did not indicate sulfidogenic alkane degradation, the data suggested that methanogenic conversion of alkanes was occurring. These findings highlight the potential role that anaerobic microorganisms could play in the bioremediation of hydrocarbons in the Bay.

  13. The origin of alkanes found in human skin surface lipids

    SciTech Connect

    Bortz, J.T.; Wertz, P.W.; Downing, D.T. )

    1989-12-01

    Lipids extracted from human skin contain variable amounts of paraffin hydrocarbons. Although the composition of these alkanes strongly resembles petroleum waxes, it has been proposed that they are biosynthetic products of human skin. To investigate this question, skin surface lipids from 15 normal subjects were analyzed for the amount and composition of alkanes, using quantitative thin-layer chromatography and quartz capillary gas chromatography. The alkanes were found to constitute 0.5% to 1.7% of the skin lipids. Subjects differed greatly in the chain length distribution of their alkanes between 15 and 35 carbon atoms, and in the relative amounts of normal alkanes (like those in petroleum waxes) and branched chain alkanes (like those in petroleum lubricating oils). In 6 subjects, the alkane content of cerumen from each ear was examined to investigate whether alkanes arrive at the skin surface by a systemic route or by direct contact with environmental surfaces. No trace of alkanes was found in 11 of the 12 cerumen samples. Using a tandem accelerator mass spectrometer for carbon-14 dating, a combined sample of the skin surface alkanes was found to have a theoretical age of 30,950 years, similar to that of a sample of petrolatum. These analyses indicate that the alkanes found on the surface of human skin are mixtures of a variety of petroleum distillation fractions that are acquired by direct contamination from the environment.

  14. Comprehensive chemical kinetic modeling of the oxidation of C8 and larger n-alkanes and 2-methylalkanes

    SciTech Connect

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M; Togbe, C; Dagaut, P; Wang, H; Oehlschlaeger, M; NIemann, U; Seshadri, K; Veloo, P S; Ji, C; Egolfopoulos, F; Lu, T

    2011-03-16

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed and reduced chemical kinetic mechanism for singly methylated iso-alkanes (i.e., 2-methylalkanes) ranging from C{sub 8} to C{sub 20}. The mechanism also includes an updated version of our previously published C{sub 8} to C{sub 16} n-alkanes model. The complete detailed mechanism contains approximately 7,200 species 31,400 reactions. The proposed model is validated against new experimental data from a variety of fundamental combustion devices including premixed and nonpremixed flames, perfectly stirred reactors and shock tubes. This new model is used to show how the presence of a methyl branch affects important combustion properties such as laminar flame propagation, ignition, and species formation.

  15. Application of the homogeneous oxidation of alkanes: Synthesis and characterization of metal complexes of a linked aryloxide

    NASA Astrophysics Data System (ADS)

    Gordon, Benjamin Willis Franklin

    Methane is the main component of natural gas, largely left behind due to cost of transportation. There are vast stores of natural gas outweighing the known reserves of liquid petroleum. A chemical process by which methane can be transformed into a usable transportable product is very important. The selective transformation of methane into a transportable product, such as methanol or formaldehyde, would be a large step forward in utilizing a vast resource. Research on transforming methane selectively has been met with several obstacles based on poor conversion and selectivity. Several methods exist for transforming methane to methanol or formaldehyde through heterogeneous metal catalyzed oxidation. Currently, these metal catalyzed processes are energy intensive and result in low conversion and selectivity. Methanol, the desired product, tends to react preferentially. In many cases, methanol is transformed to another product at a fast rate before recovery. This work describes new techniques for preventing the over oxidation using a homogeneous catalyst system under mild temperature conditions and employing solvents that react with methanol. The solvent effectively removes methanol in a reversible process protecting it from further oxidation. The selective oxidation of higher weight alkanes, such as propane and butane, is also discussed where unusual primary carbon selectivity is observed. The transition metal atoms, tantalum and niobium, have received attention for the interesting chemical reactions, such as metathesis and living polymerization, that they are known to mediate. Aryloxide complexes of these metals undergo unusual chemical transformations especially in the presence of bulky ligand substituents. This work describes the synthesis and characterization of tantalum and niobium complexes of a linked aryloxide ligand. The metal complexes of this ligand are unusual and this dissertation provides the foundation for important future studies of the complexes of

  16. Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons

    DOEpatents

    Kung, Harold H.; Chaar, Mohamed A.

    1988-01-01

    Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons is carried out over metal vanadate catalysts under oxidizing conditions. The vanadate catalysts are represented by the formulas M.sub.3 (VO.sub.4).sub.2 and MV.sub.2 O.sub.6, M representing Mg, Zn, Ca, Pb, or Cd. The reaction is carried out in the presence of oxygen, but the formation of oxygenate by-products is suppressed.

  17. Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons

    DOEpatents

    Kung, H.H.; Chaar, M.A.

    1988-10-11

    Oxidative dehydrogenation of alkanes to unsaturated hydrocarbons is carried out over metal vanadate catalysts under oxidizing conditions. The vanadate catalysts are represented by the formulas M[sub 3](VO[sub 4])[sub 2] and MV[sub 2]O[sub 6], M representing Mg, Zn, Ca, Pb, or Cd. The reaction is carried out in the presence of oxygen, but the formation of oxygenate by-products is suppressed.

  18. Chemistry of secondary organic aerosol formation

    NASA Astrophysics Data System (ADS)

    Yee, Lindsay Diana

    The photooxidation of volatile organic compounds (VOCs) in the atmosphere can lead to the formation of secondary organic aerosol (SOA), a major component of fine particulate matter. Improvements to air quality require insight into the many reactive intermediates that lead to SOA formation, of which only a small fraction have been measured at the molecular level. This thesis describes the chemistry of secondary organic aerosol (SOA) formation from several atmospherically relevant hydrocarbon precursors. Photooxidation experiments of methoxyphenol and phenolic compounds and C12 alkanes were conducted in the Caltech Environmental Chamber. These experiments include the first photooxidation studies of these precursors run under sufficiently low NOx levels, such that RO2 + HO2 chemistry dominates, an important chemical regime in the atmosphere. Using online Chemical Ionization Mass Spectrometery (CIMS), key gas-phase intermediates that lead to SOA formation in these systems were identified. With complementary particle-phase analyses, chemical mechanisms elucidating the SOA formation from these compounds are proposed. Three methoxyphenol species (phenol, guaiacol, and syringol) were studied to model potential photooxidation schemes of biomass burning intermediates. SOA yields (ratio of mass of SOA formed to mass of primary organic reacted) exceeding 25% are observed. Aerosol growth is rapid and linear with the organic conversion, consistent with the formation of essentially non-volatile products. Gas and aerosol-phase oxidation products from the guaiacol system show that the chemical mechanism consists of highly oxidized aromatic species in the particle phase. Syringol SOA yields are lower than that of phenol and guaiacol, likely due to unique chemistry dependent on methoxy group position. The photooxidation of several C12 alkanes of varying structure n-dodecane, 2-methylundecane, cyclododecane, and hexylcyclohexane) were run under extended OH exposure to investigate the

  19. Alkane biosynthesis by decarbonylation of aldehyde catalyzed by a microsomal preparation from Botryococcus braunii.

    PubMed

    Dennis, M W; Kolattukudy, P E

    1991-06-01

    The final step in the synthesis of n-hydrocarbons in an animal and a higher plant involves enzymatic decarbonylation of aldehydes to the corresponding alkanes by loss of the carbonyl carbon. Whether such a novel reaction is involved in hydrocarbon synthesis in the colonial microalga, Botryococcus braunii, which is known to produce unusually high levels (up to 32% of dry weight) of n-C27, C29, and C31 alka-dienes and -trienes, was investigated. Dithioerythritol severely inhibited the incorporation of [1-14C]acetate into these hydrocarbons with accumulation of the label in the aldehyde fraction in the B. braunii cells. Microsomal preparations of the alga synthesized alkane from fatty acid and aldehyde in the absence of O2. Conversion of fatty acid to alkane required CoA, ATP, and NADH, whereas conversion of aldehyde to alkane did not require the addition of cofactors. That the alkane synthesis involves a decarbonylation was shown by the production of CO and heptadecane from octadecanal. CO was identified by adsorption to RhCl[(C6H6)3P]3. The decarbonylase had a pH optimum at 7.0, an apparent Km of 65 microM, a Vmax of 1.36 nmol/min/mg and was inhibited by the metal chelators EDTA, O-phenanthroline and 8-hydroxyquinoline. It was stimulated nearly threefold by 2 mM ascorbate and inhibited by the presence of O2. A partial (28%) retention of the aldehydic hydrogen of [1-3H]octadecanal in the heptadecane was observed; the remaining 3H was lost to H2O. The microsomal preparation also catalyzed the oxidation of 14CO to 14CO2, with a pH optimum of 7.0. This accounts for the nonstoichiometry of CO to heptadecane observed. In vivo studies with 14CO showed that the label was incorporated into metabolic products. This metabolic conversion of CO, not found in the previously examined hydrocarbon synthesizing systems, may be necessary for organisms that produce large amounts of hydrocarbons such as the present alga. The mechanism of the decarbonylation and the nature of the

  20. The Conversion of Starch and Sugars into Branched C10 and C11 Hydrocarbons.

    PubMed

    Sutton, Andrew D; Kim, Jin K; Wu, Ruilian; Hoyt, Caroline B; Kimball, David B; Silks, Louis A; Gordon, John C

    2016-09-01

    Oligosaccharides, such as starch, cellulose, and hemicelluloses, are abundant and easily obtainable bio-derived materials that can potentially be used as precursors for fuels and chemical feedstocks. To access the pertinent molecular building blocks (i.e., 5- or 6-carbon containing sugar units) located within these biopolymers and transform them into useful fuel precursors, oligosaccharide depolymerization followed by chain extension is required. This chain extension can readily be performed via a Garcia-Gonzalez-like approach using β-diketones under mild conditions to provide fuel precursors containing an increased carbon atom content that meets fuel requirements. In a subsequent step, ring opening and hydrodeoxygenation chemistry of these species allows for the preparation of branched alkanes under relatively mild conditions. This approach can be applied to monomeric sugars (glucose and xylose), oligosaccharides (starch), and potentially to hydrolyzed dedicated energy crops to allow the conversion of real biomass into fuel type molecules. PMID:27428812

  1. Structural and Kinetic Studies of Novel Cytochrome P450 Small-Alkane Hydroxylases

    SciTech Connect

    Arnold, Frances H.

    2012-02-27

    The goals of this project are to investigate (1) the kinetics and stabilities of engineered cytochrome P450 (P450) small alkane hydroxylases and their evolutionary intermediates, (2) the structural basis for catalytic proficiency on small alkanes of these engineered P450s, and (3) the changes in redox control resulting from protein engineering. To reach these goals, we have established new methods for determining the kinetics and stabilities of multicomponent P450s such as CYP153A6. Using these, we were able to determine that CYP153A6 is proficient for hydroxylation of alkanes as small as ethane, an activity that has never been observed previously in any natural P450. To elucidate the structures of the engineered P450s, we obtained x-ray diffraction data for two variants in the P450PMO (propane monooxygenase) lineage and a preliminary structure for the most evolved variant. This structure shows changes in the substrate binding regions of the enzyme and a reduction in active site volume that are consistent with the observed changes in substrate specificity from fatty acids in the native enzyme to small alkanes in P450PMO. We also constructed semi-rational designed libraries mutating only residues in the enzyme active site that in one round of mutagenesis and screening produced variants that achieved nearly half of the activity of the most evolved enzymes of the P450PMO lineage. Finally, we found that changes in redox properties of the laboratory-evolved P450 alkane hydroxylases did not reflect the improvement in their electron transfer efficiency. The heme redox potential remained constant throughout evolution, while activity increased and coupling efficiency improved from 10% to 90%. The lack of correlation between heme redox potential and enzyme activity and coupling efficiency led us to search for other enzyme properties that could be better predictors for activity towards small alkanes, specifically methane. We investigated the oxidation potential of the radical

  2. Release of alkanes from sedimentary organic matter via sequential degradation involving catalytic hydropyrolysis

    SciTech Connect

    Love, G.D.; McAulay, A.; Snape, C.E.

    1996-12-31

    Fixed-bed pyrolysis of petroleum source rocks (type I and II kerogens) and high-volatile coals (type III ketogens) at high hydrogen pressures (> 10 MN, hydropyrolysis) in the presence of a dispersed sulphided molydenum catalyst gives rise to extremely high oil (dichloromethane-soluble) yields (>60%) with overall conversions of the organic matter being greater than 90%. The yields and conformations of the hopanes and steranes released from a selection of petroleum source rocks and coals by sequential dichloromethane and pyridine extraction, catalytic hydrogenation and hydropyrolysis will be presented, together with the influence of hydrogen pressure and heating rate on alkane yields and sterochemistry. The aim of the hydrogenation step (conducted at 300{degrees}C cf. 520{degrees}C for hydropyrolysis) in this sequential degradation scheme is to cleave only the weaker covalent bonds. The findings have demonstrated the unique ability of hydropyrolysis to mainline the yields of covalently-bound alkanes while maintaining the biologically-inherited 17{beta}(H), 21{beta}(H) stereochemistries of the hopanes, largely intact, even for coals. The total alkane yields from hydropyrolysis represented ca 30% w/w of the organic matter remaining in immature type I kerogens with yields of the C{sub 29}-C{sub 35} 17{beta}(H), 21{beta}(H) hopanes being much higher than from both normal pyrolysis and the hydrogenation step.

  3. Thermal conductivity of liquid n-alkanes

    SciTech Connect

    Calado, J.C.G.; Fareleira, J.M.N.A.; Mardolcar, U.V.; Nieto de Castro, C.A.

    1988-05-01

    The thermal conductivity of liquids has been shown in the past to be difficult to predict with a reasonable accuracy, due to the lack of accurate experimental data and reliable prediction schemes. However, data of a high accuracy, and covering wide density ranges, obtained recently in laboratories in Boulder, Lisbon, and London with the transient hot-wire technique, can be used to revise an existing correlation scheme and to develop a new universal predictive technique for the thermal conductivity of liquid normal alkanes. The proposed correlation scheme is constructed on a theoretically based treatment of the van der Waals model of a liquid, which permits the prediction of the density dependence and the thermal conductivity of liquid n-alkanes, methane to tridecane, for temperatures between 110 and 370 K and pressures up to 0.6 MPa, i.e., for 0.3 less than or equal to T/T/sub c/ less than or equal to 0.7 and 2.4 less than or equal to rho/rho/sub c/ less than or equal to 3.7, with an accuracy of +/-1%, given a known value of the thermal conductivity of the fluid at the desired temperature. A generalization of the hard-core volumes obtained, as a function of the number of carbon atoms, showed that it was possible to predict the thermal conductivity of pentane to tetradecane +/- 2%, without the necessity of available experimental measurements.

  4. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated phenyl alkane. 721.536 Section 721.536 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.536 Halogenated phenyl alkane....

  5. 40 CFR 721.535 - Halogenated alkane (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated alkane (PMN P-01-433) is...

  6. 40 CFR 721.535 - Halogenated alkane (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.535 Halogenated alkane (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated alkane (PMN P-01-433) is...

  7. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.536 Halogenated phenyl alkane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated phenyl alkane (PMN P-89-867)...

  8. 40 CFR 721.536 - Halogenated phenyl alkane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.536 Halogenated phenyl alkane. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as halogenated phenyl alkane (PMN P-89-867)...

  9. Conversion of paraffins to gasoline

    SciTech Connect

    Harandi, M.N.

    1988-11-29

    This patent describes a continuous process for conversion of C/sub 2/-C/sub 4/ alkanes to aromatic rich hydrocarbons boiling in the gasoline range comprising: maintaining a dual vertical column reactor comprising a lower transport riser reaction zone and an upper turbulent fluidized bed reaction zone, both zones containing fluidized catalyst comprising acid medium pore metallosilicate zeolite; contacting a feedstock comprising at least one C/sub 2/-C/sub 4/ alkane with fluidized catalyst in the lower transport zone under high temperature dehydrogenation conditions to dehydrogenate the feedstock and substantially prevent cracking reactions to obtain an intermediate product comprising dehydrogenated hydrocarbons and aromatics; and contacting the intermediate hydrocarbon product with fluidized catalyst in the upper turbulent zone under lower temperature oligomerization conditions to obtain a final product comprising C/sub 5/+ gasoline boiling range hydrocarbons.

  10. Sophorolipids from Torulopsis bombicola: possible relation to alkane uptake.

    PubMed Central

    Ito, S; Inoue, S

    1982-01-01

    Torulopsis bombicola produces extracellular sophorolipids when it is grown on water-insoluble alkanes. Sophorolipids and related model compounds, which were not themselves used for growth, were found to stimulate markedly the growth of T. bombicola on alkanes. This stimulatory effect was restricted to growth on C10 to C20 alkanes, whereas no significantly influence was observed for growth on fatty alcohols, fatty acids, glucose, or glycerol. The nonionic methyl ester of the glycolipid supported the greatest cell yield. However, a number of synthetic nonionic surfactants were unable to replace the glycolipid. When organisms were grown on hexadecane, stimulation of growth by sophorolipids was observed almost exclusively with strains of Torulopsis yeasts. In contrast, the growth of other typical alkane-utilizing yeasts, such as candida and Pichia strains, was inhibited or not affected. It appears that sophorolipids are involved in alkane dissimilation by T. bombicola through an undetermined mechanism. PMID:7201782

  11. Alkanes in benthic organisms from the Buccaneer oil field

    SciTech Connect

    Middleditch, B.S.; Basile, B.

    1980-06-01

    About 200 g per day of alkanes are present in brine discharged from each of two production platforms in the Buccaneer oil field in the NW Gulf of Mexico. These alkanes disperse rapidly in the water column, so that seawater concentrations of petroleum alkanes in this region are generally very low. They can be taken up to some extent by plankton, fish, and barnacles, but the petroleum alkane concentrations in these organisms are also relatively low. The largest pool of petroleum alkanes is in the surficial sediments, where concentrations of up to 25 ppM are observed, with concentration gradients extending more than 20 m from the production platforms. Organisms are examined which are exposed to these sediments and, for comparison, other specimens from control sites around structures from which there are no discharges.

  12. Utilization of n-Alkanes by Cladosporium resinae

    PubMed Central

    Teh, J. S.; Lee, K. H.

    1973-01-01

    Four different isolates of Cladosporium resinae from Australian soils were tested for their ability to utilize liquid n-alkanes ranging from n-hexane to n-octadecane under standard conditions. The isolates were unable to make use of n-hexane, n-heptane, and n-octane for growth. In fact, these hydrocarbons, particularly n-hexane, exerted an inhibitory effect on spore germination and mycelial growth. All higher n-alkanes from n-nonane to n-octadecane were assimilated by the fungus, although only limited growth occurred on n-nonane and n-decane. The long chain n-alkanes (C14 to C18) supported good growth of all isolates, but there was no obvious correlation between cell yields and chain lengths of these n-alkanes. Variation in growth responses to individual n-alkane among the different isolates was also observed. The cause of this variation is unknown. PMID:4735447

  13. Spectroscopy of the tilde A state of NO-alkane complexes (alkane = methane, ethane, propane, and n-butane)

    NASA Astrophysics Data System (ADS)

    Tamé-Reyes, Victor M.; Gardner, Adrian M.; Harris, Joe P.; McDaniel, Jodie; Wright, Timothy G.

    2012-12-01

    We have recorded (1+1) resonance-enhanced multiphoton ionization spectra of complexes formed between NO and the alkanes: CH4, C2H6, C3H8, and n-C4H10. The spectra correspond to the tilde A ← tilde X transition, which is a NO-localized 3s ← 2pπ* transition. In line with previous work, the spectrum for NO-CH4 has well-defined structure, but this is only partially resolved for the other complexes. The spectra recorded in the NO+-alkane mass channels all show a slowly rising onset, followed by a sharp offset, which is associated with dissociation of NO-alkane, from which binding energies in the tilde X and tilde A states are deduced. Beyond this sharp offset, there is a further rise in signal, which is attributed to fragmentation of higher complexes, NO-(alkane)n. Analysis of these features allows binding energies for (NO-alkane) ... alkane to be estimated, and these suggest that in the NO-(alkane)2 complexes, the second alkane molecule is bound to the first, rather than to NO. Calculated structures for the 1:1 complexes are reported, as well as binding energies.

  14. High-order harmonic generation in alkanes

    SciTech Connect

    Altucci, C.; Velotta, R.; Heesel, E.; Springate, E.; Marangos, J. P.; Vozzi, C.; Benedetti, E.; Calegari, F.; Sansone, G.; Stagira, S.; Nisoli, M.; Tosa, V.

    2006-04-15

    We have investigated the process of high-order harmonic generation in light alkanes by using femtosecond laser pulses. We show the experimental results cannot be matched by a model that assumes a single active electron only in a hydrogenic s orbital. Clear evidences are shown of the important role played by the p-like character originating from the covalent C-H bond. By constructing a suitable mixture of s-type and p-type atomic wave functions, an excellent agreement between measurements in methane and simulations is found, thus confirming the validity of the developed method as a general tool for the analysis of high-order harmonic generation in complex molecules.

  15. Novel phase behavior in normal alkanes

    SciTech Connect

    Sirota, E.B.; King, H.E. Jr.; Hughes, G.J.; Wan, W.K. )

    1992-01-27

    X-ray scattering studies on aligned films of binary mixtures of the normal alkanes C{sub 23}H{sub 48} and C{sub 28}H{sub 58} reveal, for the first time in such materials, the existence of a new equilibrium phase having the symmetry of a smectic crystal, possibly a hexatic. This phase occurs between the hexagonally packed {ital R}{sub II} and the lower-temperature orthorhombic {ital R}{sub I}, plastic crystalline, layered, rotator phases. We argue that this loss of order is due to local distortion fluctuations in the hexagonal phase. Furthermore, we have identified an {ital ABC}-to-{ital ABAB} restacking transition within the ordered {ital R}{sub II} phase.

  16. The vapor-particle partitioning of n-alkanes

    SciTech Connect

    Doskey, P.V.

    1994-04-01

    A mixed-phase partitioning model has been proposed to predict the distribution of n-alkanes between the vapor and particle phases in the atmosphere. n-Alkanes having terrestrial plant wax and petroleum origins are assumed to be associated with atmospheric particles as microcrystalline solids and subcooled liquids, respectively. The fraction of n-alkanes on atmospheric particles having plant wax and petroleum origins is estimated with carbon preference indices. Hypothetical terrestrial plant wax and petroleum mixtures are used to estimate the mole fractions of the n-alkanes in each phase and the molecular weights of the phases. Solid and subcooled liquid phase n-alkane vapor pressures are used in the model to predict the fraction of n-alkanes associated with particles in the atmosphere. Trends in the prediction of vapor-particle partitioning using these assumptions agree well with field observations. However, the fraction of particle phase n-alkanes predicted by the model was significantly different from the field observations.

  17. Long-chain alkane production by the yeast Saccharomyces cerevisiae.

    PubMed

    Buijs, Nicolaas A; Zhou, Yongjin J; Siewers, Verena; Nielsen, Jens

    2015-06-01

    In the past decade industrial-scale production of renewable transportation biofuels has been developed as an alternative to fossil fuels, with ethanol as the most prominent biofuel and yeast as the production organism of choice. However, ethanol is a less efficient substitute fuel for heavy-duty and maritime transportation as well as aviation due to its low energy density. Therefore, new types of biofuels, such as alkanes, are being developed that can be used as drop-in fuels and can substitute gasoline, diesel, and kerosene. Here, we describe for the first time the heterologous biosynthesis of long-chain alkanes by the yeast Saccharomyces cerevisiae. We show that elimination of the hexadecenal dehydrogenase Hfd1 and expression of a redox system are essential for alkane biosynthesis in yeast. Deletion of HFD1 together with expression of an alkane biosynthesis pathway resulted in the production of the alkanes tridecane, pentadecane, and heptadecane. Our study provides a proof of principle for producing long-chain alkanes in the industrial workhorse S. cerevisiae, which was so far limited to bacteria. We anticipate that these findings will be a key factor for further yeast engineering to enable industrial production of alkane based drop-in biofuels, which can allow the biofuel industry to diversify beyond bioethanol.

  18. Long-chain alkane production by the yeast Saccharomyces cerevisiae.

    PubMed

    Buijs, Nicolaas A; Zhou, Yongjin J; Siewers, Verena; Nielsen, Jens

    2015-06-01

    In the past decade industrial-scale production of renewable transportation biofuels has been developed as an alternative to fossil fuels, with ethanol as the most prominent biofuel and yeast as the production organism of choice. However, ethanol is a less efficient substitute fuel for heavy-duty and maritime transportation as well as aviation due to its low energy density. Therefore, new types of biofuels, such as alkanes, are being developed that can be used as drop-in fuels and can substitute gasoline, diesel, and kerosene. Here, we describe for the first time the heterologous biosynthesis of long-chain alkanes by the yeast Saccharomyces cerevisiae. We show that elimination of the hexadecenal dehydrogenase Hfd1 and expression of a redox system are essential for alkane biosynthesis in yeast. Deletion of HFD1 together with expression of an alkane biosynthesis pathway resulted in the production of the alkanes tridecane, pentadecane, and heptadecane. Our study provides a proof of principle for producing long-chain alkanes in the industrial workhorse S. cerevisiae, which was so far limited to bacteria. We anticipate that these findings will be a key factor for further yeast engineering to enable industrial production of alkane based drop-in biofuels, which can allow the biofuel industry to diversify beyond bioethanol. PMID:25545362

  19. Expanding the product profile of a microbial alkane biosynthetic pathway.

    PubMed

    Harger, Matthew; Zheng, Lei; Moon, Austin; Ager, Casey; An, Ju Hye; Choe, Chris; Lai, Yi-Ling; Mo, Benjamin; Zong, David; Smith, Matthew D; Egbert, Robert G; Mills, Jeremy H; Baker, David; Pultz, Ingrid Swanson; Siegel, Justin B

    2013-01-18

    Microbially produced alkanes are a new class of biofuels that closely match the chemical composition of petroleum-based fuels. Alkanes can be generated from the fatty acid biosynthetic pathway by the reduction of acyl-ACPs followed by decarbonylation of the resulting aldehydes. A current limitation of this pathway is the restricted product profile, which consists of n-alkanes of 13, 15, and 17 carbons in length. To expand the product profile, we incorporated a new part, FabH2 from Bacillus subtilis , an enzyme known to have a broader specificity profile for fatty acid initiation than the native FabH of Escherichia coli . When provided with the appropriate substrate, the addition of FabH2 resulted in an altered alkane product profile in which significant levels of n-alkanes of 14 and 16 carbons in length are produced. The production of even chain length alkanes represents initial steps toward the expansion of this recently discovered microbial alkane production pathway to synthesize complex fuels. This work was conceived and performed as part of the 2011 University of Washington international Genetically Engineered Machines (iGEM) project.

  20. Heterogeneity of Alkane Chain Length in Freshwater and Marine Cyanobacteria

    PubMed Central

    Shakeel, Tabinda; Fatma, Zia; Fatma, Tasneem; Yazdani, Syed Shams

    2015-01-01

    The potential utilization of cyanobacteria for the biological production of alkanes represents an exceptional system for the next generation of biofuels. Here, we analyzed a diverse group of freshwater and marine cyanobacterial isolates from Indian culture collections for their ability to produce both alkanes and alkenes. Among the 50 cyanobacterial isolates screened, 32 isolates; 14 freshwater and 18 marine isolates; produced predominantly alkanes. The GC-MS/MS profiles revealed a higher percentage of pentadecane and heptadecane production for marine and freshwater strains, respectively. Oscillatoria species were found to be the highest producers of alkanes. Among the freshwater isolates, Oscillatoria CCC305 produced the maximum alkane level with 0.43 μg/mg dry cell weight, while Oscillatoria formosa BDU30603 was the highest producer among the marine isolates with 0.13 μg/mg dry cell weight. Culturing these strains under different media compositions showed that the alkane chain length was not influenced by the growth medium but was rather an inherent property of the strains. Analysis of the cellular fatty acid content indicated the presence of predominantly C16 chain length fatty acids in marine strains, while the proportion of C18 chain length fatty acids increased in the majority of freshwater strains. These results correlated with alkane chain length specificity of marine and freshwater isolates indicating that alkane chain lengths may be primarily determined by the fatty acid synthesis pathway. Moreover, the phylogenetic analysis showed clustering of pentadecane-producing marine strains that was distinct from heptadecane-producing freshwater strains strongly suggesting a close association between alkane chain length and the cyanobacteria habitat. PMID:25853127

  1. Alkanes-filled photonic crystal fibers as sensor transducers

    NASA Astrophysics Data System (ADS)

    Marć, P.; Przybysz, N.; Stasiewicz, K.; Jaroszewicz, L. R.

    2015-09-01

    In this paper we propose alkanes-filled PCFs as the new class of transducers for optical fiber sensors. We investigated experimentally thermo-optic properties of a commercially available LMA8 partially filled with different alkanes with a higher number of carbon atoms. A partially filled PCF spliced with standard SMFs constitutes one of the newest type transducer. We have selected a group of eight alkanes which have melting points in different temperatures. An analysis of temperature spectral characteristics of these samples will allow to design an optical fiber sensor with different temperature thresholds at specific wavelengths.

  2. Chemistry of tantalum clusters in solution and on SiO2 supports: analogies and contrasts.

    PubMed

    Nemana, Sailendra; Okamoto, Norihiko L; Browning, Nigel D; Gates, Bruce C

    2007-08-14

    Tantalum clusters have been synthesized from Ta(CH2Ph)5 on the surface of porous fumed SiO2. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO2 are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO2 catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored. PMID:17636989

  3. Chemistry of Tantalum Clusters in Solution And on SiO(2) Supports: Analogies And Contrasts

    SciTech Connect

    Nemana, S.; Okamoto, N.L.; Browning, N.D.; Gates, B.C.

    2009-06-03

    Tantalum clusters have been synthesized from Ta(CH{sub 2}Ph){sub 5} on the surface of porous fumed SiO{sub 2}. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO{sub 2} are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO{sub 2} catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored.

  4. Chemistry of Tantalum Clusters in Solution and on SiO2 Supports: Analogies and Contrasts

    SciTech Connect

    Nemana,S.; Okamoto, N.; Browning, N.; Gates, B.

    2007-01-01

    Tantalum clusters have been synthesized from Ta(CH{sub 2}Ph){sub 5} on the surface of porous fumed SiO{sub 2}. When these clusters are small, incorporating, on average, several Ta atoms, their chemistry is similar to that of molecular tantalum clusters (and other early transition-metal) clusters. For example, The Ta-Ta bonds in these small supported clusters have been characterized by extended X-ray absorption fine structure (EXAFS), IR, and UV-vis spectroscopy, being similar to those in molecular analogues. The redox reactions of the supported clusters, characterized by X-ray absorption near-edge structure, are analogous to those of early transition-metal clusters in solution. In contrast to the largest of these clusters in solution and in the solid state, those supported on SiO{sub 2} are raftlike, facilitating the substantial metal-support-oxygen bonding that is evident in the EXAFS spectra. Samples consisting of tantalum clusters on SiO{sub 2} catalyze alkane disproportionation and the conversion of methane with n-butane to give other alkanes, but catalytic properties of analogous clusters in solution have barely been explored.

  5. Process for converting light alkanes to higher hydrocarbons

    DOEpatents

    Noceti, Richard P.; Taylor, Charles E.

    1988-01-01

    A process is disclosed for the production of aromatic-rich, gasoline boiling range hydrocarbons from the lower alkanes, particularly from methane. The process is carried out in two stages. In the first, alkane is reacted with oxygen and hydrogen chloride over an oxyhydrochlorination catalyst such as copper chloride with minor proportions of potassium chloride and rare earth chloride. This produces an intermediate gaseous mixture containing water and chlorinated alkanes. The chlorinated alkanes are contacted with a crystalline aluminosilicate catalyst in the hydrogen or metal promoted form to produce gasoline range hydrocarbons with a high proportion of aromatics and a small percentage of light hydrocarbons (C.sub.2 -C.sub.4). The light hydrocarbons can be recycled for further processing over the oxyhydrochlorination catalyst.

  6. Pd/NbOPO₄ multifunctional catalyst for the direct production of liquid alkanes from aldol adducts of furans.

    PubMed

    Xia, Qi-Neng; Cuan, Qian; Liu, Xiao-Hui; Gong, Xue-Qing; Lu, Guan-Zhong; Wang, Yan-Qin

    2014-09-01

    Great efforts have been made to convert renewable biomass into transportation fuels. Herein, we report the novel properties of NbO(x)-based catalysts in the hydrodeoxygenation of furan-derived adducts to liquid alkanes. Excellent activity and stability were observed with almost no decrease in octane yield (>90% throughout) in a 256 h time-on-stream test. Experimental and theoretical studies showed that NbO(x) species play the key role in C-O bond cleavage. As a multifunctional catalyst, Pd/NbOPO4 plays three roles in the conversion of aldol adducts into alkanes: 1) The noble metal (in this case Pd) is the active center for hydrogenation; 2) NbO(x) species help to cleave the C-O bond, especially of the tetrahydrofuran ring; and 3) a niobium-based solid acid catalyzes the dehydration, thus enabling the quantitative conversion of furan-derived adducts into alkanes under mild conditions. PMID:25045056

  7. Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle.

    PubMed

    Lea-Smith, David J; Biller, Steven J; Davey, Matthew P; Cotton, Charles A R; Perez Sepulveda, Blanca M; Turchyn, Alexandra V; Scanlan, David J; Smith, Alison G; Chisholm, Sallie W; Howe, Christopher J

    2015-11-01

    Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria, Prochlorococcus and Synechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2-540 pg alkanes per mL per day, which translates into a global ocean yield of ∼ 308-771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities.

  8. Contribution of cyanobacterial alkane production to the ocean hydrocarbon cycle

    PubMed Central

    Lea-Smith, David J.; Biller, Steven J.; Davey, Matthew P.; Cotton, Charles A. R.; Perez Sepulveda, Blanca M.; Turchyn, Alexandra V.; Scanlan, David J.; Smith, Alison G.; Chisholm, Sallie W.; Howe, Christopher J.

    2015-01-01

    Hydrocarbons are ubiquitous in the ocean, where alkanes such as pentadecane and heptadecane can be found even in waters minimally polluted with crude oil. Populations of hydrocarbon-degrading bacteria, which are responsible for the turnover of these compounds, are also found throughout marine systems, including in unpolluted waters. These observations suggest the existence of an unknown and widespread source of hydrocarbons in the oceans. Here, we report that strains of the two most abundant marine cyanobacteria, Prochlorococcus and Synechococcus, produce and accumulate hydrocarbons, predominantly C15 and C17 alkanes, between 0.022 and 0.368% of dry cell weight. Based on global population sizes and turnover rates, we estimate that these species have the capacity to produce 2–540 pg alkanes per mL per day, which translates into a global ocean yield of ∼308–771 million tons of hydrocarbons annually. We also demonstrate that both obligate and facultative marine hydrocarbon-degrading bacteria can consume cyanobacterial alkanes, which likely prevents these hydrocarbons from accumulating in the environment. Our findings implicate cyanobacteria and hydrocarbon degraders as key players in a notable internal hydrocarbon cycle within the upper ocean, where alkanes are continually produced and subsequently consumed within days. Furthermore we show that cyanobacterial alkane production is likely sufficient to sustain populations of hydrocarbon-degrading bacteria, whose abundances can rapidly expand upon localized release of crude oil from natural seepage and human activities. PMID:26438854

  9. Reversible Interconversion between Alkanes, Alkenes, Alcohols and Ketones under Hydrothermal Conditions

    NASA Astrophysics Data System (ADS)

    Shipp, J.; Hartnett, H. E.; Gould, I. R.; Shock, E.; Williams, L. B.

    2011-12-01

    Many transformation reactions involving hydrocarbons that occur in deep sedimentary systems and determine petroleum compositions occur in the presence of H2O. Hydrothermal transformations of organic material are thought to provide carbon sources for microbes in deep ocean sediments. Hydrothermal conditions may also mimic the conditions where life developed on an early Earth. Nevertheless, much remains to be learned about the mechanisms of hydrothermal organic reactions, including ways in which various reactions are interrelated and how reactions compete with each other. It can be argued that metastable equilibrium states develop over geological timescales and at geochemically relevant temperatures, suggesting that reactions occur under thermodynamic rather than kinetic control. The extent to which reactions are reversible, and how product distributions are determined, are primary tests of the metastable equilibrium model. Seewald (2001, GCA 65, 1641-1664) showed that under hydrothermal conditions and in the presence of a redox buffer, simple alkanes and alkenes undergo oxidation, reduction, and hydration reactions. He proposed a reaction scheme where alkanes interconvert with alkenes, followed by stepwise hydration of alkenes to alcohols, oxidation to ketones, and finally conversion to carboxylic acids, which can undergo decarboxylation. Here we describe experiments that further develop the scope of these functional group interconversions, determine relative reaction kinetics, and provide insight into competing reactions. Hydrothermal experiments were performed at 300°C and 100 MPa in gold capsules for 12 to 144 hours. The reactant structures were based on cyclohexane with one and two methyl groups that served as regio- and stereochemical markers for the reactions. Starting with the alkanes, the observed products include the corresponding alkenes, alcohols, ketones and enones, in support of the Seewald reaction scheme. Our experiments add a branch to this scheme

  10. A Comparison of the Monolayer Dynamics of the Branched Alkane Squalane and the Normal Alkane Tetracosane Adsorbed on Graphite

    NASA Astrophysics Data System (ADS)

    Enevoldsen, A. D.; Hansen, F. Y.; Diama, A.; Taub, H.

    2004-03-01

    Squalane is a branched alkane (C_30H_62) with 24 carbon atoms in its backbone, like the normal alkane tetracosane ( n-C_24H_50), and six symmetrically placed methyl side groups. In general, branched alkanes such as squalane are better lubricants than n-alkanes. We have studied the dynamics of the squalane and tetracosane monolayers by quasielastic neutron scattering and molecular dynamics (MD) simulations on two different time scales. Both experiments and simulations showed that diffusion at 260 K is about 2.5 times faster in the squalane than in the tetracosane system. It is somewhat surprising that the diffusion in a system with a branched alkane is faster than with a normal alkane. A possible explanation is that the squalane molecule does not bind as strongly to the surface as tetracosane, because the MD simulations have shown that the adsorbed molecules have a distorted backbone. This may also explain why the slow intramolecular motions associated with conformational changes are seen at lower temperatures in the squalane than the tetracosane monolayer where they are only observed near melting.

  11. Selective hydroxylation of alkanes by an extracellular fungal peroxygenase.

    PubMed

    Peter, Sebastian; Kinne, Matthias; Wang, Xiaoshi; Ullrich, René; Kayser, Gernot; Groves, John T; Hofrichter, Martin

    2011-10-01

    Fungal peroxygenases are novel extracellular heme-thiolate biocatalysts that are capable of catalyzing the selective monooxygenation of diverse organic compounds, using only H(2)O(2) as a cosubstrate. Little is known about the physiological role or the catalytic mechanism of these enzymes. We have found that the peroxygenase secreted by Agrocybe aegerita catalyzes the H(2)O(2)-dependent hydroxylation of linear alkanes at the 2-position and 3-position with high efficiency, as well as the regioselective monooxygenation of branched and cyclic alkanes. Experiments with n-heptane and n-octane showed that the hydroxylation proceeded with complete stereoselectivity for the (R)-enantiomer of the corresponding 3-alcohol. Investigations with a number of model substrates provided information about the route of alkane hydroxylation: (a) the hydroxylation of cyclohexane mediated by H(2)(18)(2) resulted in complete incorporation of (18)O into the hydroxyl group of the product cyclohexanol; (b) the hydroxylation of n-hexane-1,1,1,2,2,3,3-D(7) showed a large intramolecular deuterium isotope effect [(k(H)/k(D))(obs)] of 16.0 ± 1.0 for 2-hexanol and 8.9 ± 0.9 for 3-hexanol; and (c) the hydroxylation of the radical clock norcarane led to an estimated radical lifetime of 9.4 ps and an oxygen rebound rate of 1.06 × 10(11) s(-1). These results point to a hydrogen abstraction and oxygen rebound mechanism for alkane hydroxylation. The peroxygenase appeared to lack activity on long-chain alkanes (> C(16)) and highly branched alkanes (e.g. tetramethylpentane), but otherwise exhibited a broad substrate range. It may accordingly have a role in the bioconversion of natural and anthropogenic alkane-containing structures (including alkyl chains of complex biomaterials) in soils, plant litter, and wood. PMID:21812933

  12. Variation in n-Alkane Distributions of Modern Plants: Questioning Applications of n-Alkanes in Chemotaxonomy and Paleoecology

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; McInerney, F. A.

    2010-12-01

    Long chain n-alkanes (n-C21 to n-C37) are synthesized as part of the epicuticular leaf wax of terrestrial plants and are among the most recognizable and widely used plant biomarkers. n-Alkane distributions have been utilized in previous studies on modern plant chemotaxonomy, testing whether taxa can be identified based on characteristic n-alkane profiles. Dominant n-alkanes (e.g. n-C27 or n-C31) have also been ascribed to major plant groups (e.g. trees or grasses respectively) and have been used in paleoecology studies to reconstruct fluctuations in plant functional types. However, many of these studies have been based on relatively few modern plant data; with the wealth of modern n-alkane studies, a more comprehensive analysis of n-alkanes in modern plants is now possible and can inform the usefulness of n-alkane distributions as paleoecological indicators. The work presented here is a combination of measurements made using plant leaves collected from the Chicago Botanic Garden and a compilation of published literature data from six continents. We categorized plants by type: angiosperms, gymnosperms, woody plants, forbs, grasses, ferns and pteridophytes, and mosses. We then quantified n-alkane distribution parameters such as carbon preference index (CPI), average chain length (ACL), and dispersion (a measure of the spread of the profile over multiple chain lengths) and used these to compare plant groups. Among all plants, one of the emergent correlations is a decrease in dispersion with increasing CPI. Within and among plant groups, n-alkane distributions show a very large range of variation, and the results show little or no correspondence between broad plant groups and a single dominant n-alkane or a ratio of n-alkanes. These findings are true both when data from six continents are combined and when plants from a given region are compared (North America). We also compared the n-alkane distributions of woody angiosperms, woody gymnosperms, and grasses with one

  13. Metabolism of Hydrocarbons in n-Alkane-Utilizing Anaerobic Bacteria.

    PubMed

    Wilkes, Heinz; Buckel, Wolfgang; Golding, Bernard T; Rabus, Ralf

    2016-01-01

    The glycyl radical enzyme-catalyzed addition of n-alkanes to fumarate creates a C-C-bond between two concomitantly formed stereogenic carbon centers. The configurations of the two diastereoisomers of the product resulting from n-hexane activation by the n-alkane-utilizing denitrifying bacterium strain HxN1, i.e. (1-methylpentyl)succinate, were assigned as (2S,1'R) and (2R,1'R). Experiments with stereospecifically deuterated n-(2,5-2H2)hexanes revealed that exclusively the pro-S hydrogen atom is abstracted from C2 of the n-alkane by the enzyme and later transferred back to C3 of the alkylsuccinate formed. These results indicate that the alkylsuccinate-forming reaction proceeds with an inversion of configuration at the carbon atom (C2) of the n-alkane forming the new C-C-bond, and thus stereochemically resembles a SN2-type reaction. Therefore, the reaction may occur in a concerted manner, which may avoid the highly energetic hex-2-yl radical as an intermediate. The reaction is associated with a significant primary kinetic isotope effect (kH/kD ≥3) for hydrogen, indicating that the homolytic C-H-bond cleavage is involved in the first irreversible step of the reaction mechanism. The (1-methylalkyl)succinate synthases of n-alkane-utilizing anaerobic bacteria apparently have very broad substrate ranges enabling them to activate not only aliphatic but also alkyl-aromatic hydrocarbons. Thus, two denitrifiers and one sulfate reducer were shown to convert the nongrowth substrate toluene to benzylsuccinate and further to the dead-end product benzoyl-CoA. For this purpose, however, the modified β-oxidation pathway known from alkylbenzene-utilizing bacteria was not employed, but rather the pathway used for n-alkane degradation involving CoA ligation, carbon skeleton rearrangement and decarboxylation. Furthermore, various n-alkane- and alkylbenzene-utilizing denitrifiers and sulfate reducers were found to be capable of forming benzyl alcohols from diverse alkylbenzenes

  14. Diffusion of Benzene and Alkylbenzenes in n-Alkanes.

    PubMed

    Kowert, Bruce A; Register, Paul M

    2015-10-01

    The translational diffusion constants, D, of benzene and a series of alkylbenzenes have been determined in four n-alkanes at room temperature using capillary flow techniques. The alkylbenzenes are toluene, ethylbenzene, 1-phenylpropane, 1-phenylpentane, 1-phenyloctane, 1-phenylundecane, 1-phenyltetradecane, and 1-phenylheptadecane. The n-alkanes are n-nonane, n-decane, n-dodecane, and n-pentadecane. Ratios of the solutes' D values are independent of solvent and in general agreement with the predictions of diffusion models for cylinders and lollipops. For the latter, an alkylbenzene's phenyl ring is the lollipop's candy; the alkyl chain is its handle. A model that considers the solutes to be spheres with volumes determined by the van der Waals increments of their constituent atoms is not in agreement with experiment. The diffusion constants of 1-alkene and n-alkane solutes in n-alkane solvents also are compared with the cylinder model; reasonably good agreement is found. The n-alkanes are relatively extended, and this appears to be the case for the alkyl chains of the 1-alkenes and alkylbenzenes as well. PMID:26417941

  15. Surface freezing in binary alkane-alcohol mixtures

    SciTech Connect

    Ofer, E.; Sloutskin, E.; Tamam, L.; Deutsch, M.; Ocko, B. M.

    2006-08-15

    Surface freezing was detected and studied in mixtures of alcohol and alkane molecules, using surface tensiometry and surface-specific x-ray scattering methods. Considering that surface freezing in pure alkanes forms an ordered monolayer and in alcohols it forms an ordered bilayer, the length mismatch repulsion was minimized by varying the carbon number of the alkane component around 2n, where n is the carbon number of the alcohol molecule. A solutionlike behavior was found for all mixtures, where the ideal liquid mixture phase-separates upon freezing both in the bulk and the surface. The solid exhibits a herringbone crystalline phase below an alkane mole fraction {phi}{sub t}{approx_equal}0.8 and a rotator phase above it. The surface frozen film below {phi}{sub t} is an alkane monolayer exhibiting a next-nearest neighbor molecular tilt of a composition-dependent magnitude. Above {phi}{sub t}, no diffraction peaks were observed. This could be explained by the intrinsically shorter-range order of the rotator phase and a possible proliferation of defects.

  16. Structure, Energetics, and Dynamics of Screw Dislocations in Even n-Alkane Crystals.

    PubMed

    Olson, Isabel A; Shtukenberg, Alexander G; Hakobyan, Gagik; Rohl, Andrew L; Raiteri, Paolo; Ward, Michael D; Kahr, Bart

    2016-08-18

    Spiral hillocks on n-alkane crystal surfaces were observed immediately after Frank recognized the importance of screw dislocations for crystal growth, yet their structures and energies in molecular crystals remain ill-defined. To illustrate the structural chemistry of screw dislocations that are responsible for plasticity in organic crystals and upon which the organic electronics and pharmaceutical industries depend, molecular dynamics was used to examine heterochiral dislocation pairs with Burgers vectors along [001] in n-hexane, n-octane, and n-decane crystals. The cores were anisotropic and elongated in the (110) slip plane, with significant local changes in molecular position, orientation, conformation, and energy. This detailed atomic level picture produced a distribution of strain consistent with linear elastic theory, giving confidence in the simulations. Dislocations with doubled Burgers vectors split into pairs with elementary displacements. These results suggest a pathway to understanding the mechanical properties and failure associated with elastic and plastic deformation in soft crystals. PMID:27478906

  17. One-step hydrotreatment of vegetable oil to produce high quality diesel-range alkanes.

    PubMed

    Wang, Congxin; Tian, Zhijian; Wang, Lei; Xu, Renshun; Liu, Qianhe; Qu, Wei; Ma, Huaijun; Wang, Bingchun

    2012-10-01

    A one-step hydrotreatment of vegetable oil combining deoxygenation and isomerization to directly produce low cloud point, high quality diesel is devised. The Pt/zeolite bifunctional catalysts prepared by using SAPO-11 and ZSM-22 zeolites as supports are used in this process. Catalytic reactions are conducted in a fixed-bed reactor under a hydrogen atmosphere. Over the bifunctional catalyst, 100 % conversion of soybean oil is obtained at 357 °C, 4 MPa, and 1 h(-1), and 80 % organic liquid yield is achieved, which is close to the maximum theoretical liquid yield. In the organic products, the alkanes selectivity is 100 % with an i-alkanes selectivity above 63 %. NH(3)-temperature programmed desorption (TPD), pyridine IR spectroscopy, and other characterization techniques are used to study the effect of the support acidity on the reaction pathway. Over the Pt/zeolite bifunctional catalyst with less strong Lewis acid sites, the reaction proceeds via the decarboxylation plus decarbonylation pathway. This one-step method provides a new strategy to produce low cloud point, high quality diesel from biomass feedstock in a more economic and attractive way. PMID:22764086

  18. Conversational Dominance.

    ERIC Educational Resources Information Center

    Esau, Helmut; Poth, Annette

    Details of conversational behavior can often not be interpreted until the social interaction, including the rights and obligations of the participants, their intent, the topic, etc., has been defined. This paper presents a model of conversation in which the conversational image a person presents in a given conversational situation is a function of…

  19. Alkanes in shrimp from the Buccaneer Oil Field

    SciTech Connect

    Middleditch, B.S.; Basile, B.; Chang, E.S.

    1982-07-01

    A total of 36 samples of shrimp were examined from the region of the Buccaneer oil field, eighteen of which were representatives of the commercial species Penaeus aztecus and the rest were various other species: Penaeus duorarum (pink shrimp), Trachypenaeus duorarum (sugar shrimp), Squilla empusa (mantis shrimp), and Sicyonia dorsalis (chevron shrimp). The alkanes and deuteriated alkanes were completely separated by GC, so a mass spectrometer was not required for their detection and quantitation. To confirm the identities of individual compounds, however, some samples were examined by combined gas chromatography-mass spectrometry. Results show that only thirteen of the forty shrimp collected from the region of the Buccaneer oil field contained petroleum alkanes, and the majority of these were obtained from trawls immediately adjacent to the production platforms. It appears that shrimp caught in the region of the Buccaneer oil field are not appreciably tainted with hydrocarbons discharged from the production platforms. (JMT)

  20. Infrared Spectroscopic Investigation on CH Bond Acidity in Cationic Alkanes

    NASA Astrophysics Data System (ADS)

    Matsuda, Yoshiyuki; Xie, Min; Fujii, Asuka

    2016-06-01

    We have demonstrated large enhancements of CH bond acidities in alcohol, ether, and amine cations through infrared predissociation spectroscopy based on the vacuum ultraviolet photoionization detection. In this study, we investigate for the cationic alkanes (pentane, hexane, and heptane) with different alkyl chain lengths. The σ electrons are ejected in the ionization of alkanes, while nonbonding electrons are ejected in ionization of alcohols, ethers, and amines. Nevertheless, the acidity enhancements of CH in these cationic alkanes have also been demonstrated by infrared spectroscopy. The correlations of their CH bond acidities with the alkyl chain lengths as well as the mechanisms of their acidity enhancements will be discussed by comparison of infrared spectra and theoretical calculations.

  1. Thermal decomposition of n-alkanes under supercritical conditions

    SciTech Connect

    Yu, J.; Eser, S.

    1996-10-01

    The future aircraft fuel system may be operating at temperatures above the critical points of fuels. Currently there is very limited information on the thermal stability of hydrocarbon fuels under supercritical conditions. In this work, the thermal stressing experiments of n-decane, n-dodecane, n-tetradecane, their mixtures, and an n-paraffin mixture, Norpar-13, was carried out under supercritical conditions. The experimental results indicated that the thermal decomposition of n-alkanes can be represented well by the first-order kinetics. Pressure has significant effects on the first-order rate constant and product distribution in the near-critical region. The major products are a series of n-alkanes and 1-alkenes. The relative yields of n-alkanes and 1-alkenes depend on the reaction conditions. The first-order rate constants for the thermal decomposition of individual compounds in a mixture are different from those obtained for the decomposition of pure compounds.

  2. Surface crystallization in normal-alkanes and alcohols

    SciTech Connect

    Deutsch, M.; Ocko, B.M.; Wu, X.Z. |; Sirota, E.B.; Sinha, S.K.

    1995-06-01

    A new, rare surface freezing, phenomenon is observed in molten normal-alkanes and their derivatives (alcohols, thiols, etc.). X-ray and surface tension measurements show the formation of a crystalline monolayer on the surface of the liquid alkane at temperatures up to 3 C above the bulk solidification temperature, T{sub f}. For alcohols, a single bilayer is formed. In both cases, the molecules in the layer are hexagonally packed and oriented normal to the surface for short chain lengths, and tilted for long ones. In both cases the single layer persists down to T{sub f}. In terms of wetting theory, this constitutes a very limited partial wetting of the liquid surface by the crystalline layer. The new surface phase is obtained only for chain lengths 14 < n {le} 50 in alkanes, and 16 < n < 30 in alcohols. The measurements are satisfactorily accounted for within a simple theory based on surface energy considerations.

  3. Nitrogen Oxide Atom-Transfer Redox Chemistry; Mechanism of NO(g) to Nitrite Conversion Utilizing μ-oxo Heme-Fe(III)-O-Cu(II)(L) Constructs.

    PubMed

    Hematian, Shabnam; Kenkel, Isabell; Shubina, Tatyana E; Dürr, Maximilian; Liu, Jeffrey J; Siegler, Maxime A; Ivanovic-Burmazovic, Ivana; Karlin, Kenneth D

    2015-05-27

    While nitric oxide (NO, nitrogen monoxide) is a critically important signaling agent, its cellular concentrations must be tightly controlled, generally through its oxidative conversion to nitrite (NO2(-)) where it is held in reserve to be reconverted as needed. In part, this reaction is mediated by the binuclear heme a3/CuB active site of cytochrome c oxidase. In this report, the oxidation of NO(g) to nitrite is shown to occur efficiently in new synthetic μ-oxo heme-Fe(III)-O-Cu(II)(L) constructs (L being a tridentate or tetradentate pyridyl/alkylamino ligand), and spectroscopic and kinetic investigations provide detailed mechanistic insights. Two new X-ray structures of μ-oxo complexes have been determined and compared to literature analogs. All μ-oxo complexes react with 2 mol equiv NO(g) to give 1:1 mixtures of discrete [(L)Cu(II)(NO2(-))](+) plus ferrous heme-nitrosyl compounds; when the first NO(g) equiv reduces the heme center and itself is oxidized to nitrite, the second equiv of NO(g) traps the ferrous heme thus formed. For one μ-oxo heme-Fe(III)-O-Cu(II)(L) compound, the reaction with NO(g) reveals an intermediate species ("intermediate"), formally a bis-NO adduct, [(NO)(porphyrinate)Fe(II)-(NO2(-))-Cu(II)(L)](+) (λmax = 433 nm), confirmed by cryo-spray ionization mass spectrometry and EPR spectroscopy, along with the observation that cooling a 1:1 mixture of [(L)Cu(II)(NO2(-))](+) and heme-Fe(II)(NO) to -125 °C leads to association and generation of the key 433 nm UV-vis feature. Kinetic-thermodynamic parameters obtained from low-temperature stopped-flow measurements are in excellent agreement with DFT calculations carried out which describe the sequential addition of NO(g) to the μ-oxo complex. PMID:25974136

  4. Oxaloacetate-to-malate conversion by mineral photoelectrochemistry: implications for the viability of the reductive tricarboxylic acid cycle in prebiotic chemistry

    NASA Astrophysics Data System (ADS)

    Guzman, Marcelo I.; Martin, Scot T.

    2008-10-01

    The carboxylic acids produced by the reductive tricarboxylic acid (rTCA) cycle are possibly a biosynthetic core of initial life, although several steps such as the reductive kinetics of oxaloacetate (OAA) to malate (MA) are problematic by conventional chemical routes. In this context, we studied the kinetics of this reaction as promoted by ZnS mineral photoelectrochemistry. The quantum efficiency φMA of MA production from the photoelectrochemical reduction of OAA followed φMA=0.13 [OAA] (2.1×10-3+[OAA])-1 and was independent of temperature (5 to 50°C). To evaluate the importance of this forward rate under a prebiotic scenario, we also studied the temperature-dependent rate of the backward thermal decarboxylation of OAA to pyruvate (PA), which followed an Arrhenius behavior as log (k-2)=11.74 4956/T, where k-2 is in units of s-1. These measured rates were employed in conjunction with the indirectly estimated carboxylation rate of PA to OAA to assess the possible importance of mineral photoelectrochemistry in the conversion of OAA to MA under several scenarios of prebiotic conditions on early Earth. As an example, our analysis shows that there is 90% efficiency with a forward velocity of 3 yr/cycle for the OAA→MA step of the rTCA cycle at 280 K. Efficiency and velocity both decrease for increasing temperature. These results suggest high viability for mineral photoelectrochemistry as an enzyme-free engine to drive the rTCA cycle through the early aeons of early Earth, at least for the investigated OAA→MA step.

  5. Assimilation of chlorinated alkanes by hydrocarbon-utilizing fungi

    SciTech Connect

    Murphy, G.L.; Perry, J.J.

    1984-12-01

    The fatty acid compositions of two filamentous fungi (Cunninghamella elegans and Penicillium zonatum) and a yeast (Candida lipolytica) were determined after the organisms were grown on 1-chlorohexadecane or 1-chlorooctadecane. These organisms utilized the chlorinated alkanes as sole sources of carbon and energy. Analyses of the fatty acids present after growth on the chlorinated alkanes indicated that 60 to 70% of the total fatty acids in C. elegans were chlorinated. Approximately 50% of the fatty acids in C. lipolytica were also chlorinated. P. zonatum contained 20% 1-chlorohexadecanoic acid after growth on either substrate but did not incorporate C/sub 18/ chlorinated fatty acids.

  6. Regioselective alkane hydroxylation with a mutant AlkB enzyme

    DOEpatents

    Koch, Daniel J.; Arnold, Frances H.

    2012-11-13

    AlkB from Pseudomonas putida was engineered using in-vivo directed evolution to hydroxylate small chain alkanes. Mutant AlkB-BMO1 hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. Mutant AlkB-BMO2 similarly hydroxylates propane and butane at the terminal carbon at a rate greater than the wild-type to form 1-propanol and 1-butanol, respectively. These biocatalysts are highly active for small chain alkane substrates and their regioselectivity is retained in whole-cell biotransformations.

  7. Modeling of alkane emissions from a wood stain

    SciTech Connect

    Chang, J.C.S.; Guo, Z.

    1993-01-01

    The article discusses full-scale residential house tests to evaluate the effects of organic emissions from a wood finishing product--wood stain--on indoor air quality (IAQ). The test house concentrations of three alkane species, nonane, decane, and undecane, were measured as a function of time after the application of the wood stain. It was found that the test house concentrations can be simulated by an integrated IAQ model which takes into consideration source, sink, and ventilation effects. The alkane emissions were controlled by an evaporation-like process.

  8. Nitrogen Oxide Atom-Transfer Redox Chemistry; Mechanism of NO(g) to Nitrite Conversion Utilizing µ-oxo Heme-FeIII−O−CuII(L) Constructs

    PubMed Central

    Hematian, Shabnam; Kenkel, Isabell; Shubina, Tatyana E.; Dürr, Maximilian; Liu, Jeffrey J.; Siegler, Maxime A.; Ivanovic-Burmazovic, Ivana; Karlin, Kenneth D.

    2015-01-01

    While nitric oxide (NO, nitrogen monoxide) is a critically important signaling agent, its cellular concentrations must be tightly controlled, generally through its oxidative conversion to nitrite (NO2−) where it is held in reserve to be reconverted as needed. In part, this reaction is mediated by the binuclear heme a3/CuB active site of cytochrome c oxidase. In this report, the oxidation of NO(g) to nitrite is shown to occur efficiently in new synthetic µ-oxo heme-FeIII−O−CuII(L) constructs (L being a tridentate or tetradentate pyridyl/alkylamino ligand), and spectroscopic and kinetic investigations provide detailed mechanistic insights. Two new X-ray structures of µ-oxo complexes have been determined and compared to literature analogs. All µ-oxo complexes react with 2 mol equiv NO(g) to give 1:1 mixtures of discrete [(L)CuII(NO2−)]+ plus ferrous heme-nitrosyl compounds; when the first NO(g) equiv reduces the heme center and itself is oxidized to nitrite, the second equiv of NO(g) traps the ferrous heme thus formed. For one µ-oxo heme-FeIII−O−CuII(L) compound, the reaction with NO(g) reveals an intermediate species (“intermediate”), formally a bis-NO adduct, [(NO)(porphyrinate)FeII-(NO2−)−CuII(L)]+ (λmax = 433 nm), confirmed by cryo-spray ionization mass spectrometry and EPR spectroscopy, along with the observation that cooling a 1:1 mixture of [(L)CuII(NO2−)]+ and heme-FeII(NO) to −125 °C leads to association and generation of the key 433 nm UV–vis feature. Kinetic-thermodynamic parameters obtained from low-temperature stopped-flow measurements are in excellent agreement with DFT calculations carried out which describe the sequential addition of NO(g) to the µ-oxo complex. PMID:25974136

  9. Session: Energy Conversion

    SciTech Connect

    Robertson, David; LaSala, Raymond J.; Kukacka, Lawrence E.; Bliem, Carl J.; Premuzic, Eugene T.; Weare, John H.

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hydrothermal Energy Conversion Technology'' by David Robertson and Raymond J. LaSala; ''Materials for Geothermal Production'' by Lawrence E. Kukacka; ''Supersaturated Turbine Expansions for Binary Geothermal Power Plants'' by Carl J. Bliem; ''Geothermal Waster Treatment Biotechnology: Progress and Advantages to the Utilities'' by Eugen T. Premuzic; and ''Geothermal Brine Chemistry Modeling Program'' by John H. Weare.

  10. Radiation-initiated conversion of paraffins to engine fuel: Direct and indirect initiation

    NASA Astrophysics Data System (ADS)

    Metreveli, A. K.; Ponomarev, A. V.

    2016-07-01

    Formation of gasoline and diesel fuel has been investigated using three various radiation-induced ways: (1) cracking of wax, (2) synthesis from methane, (3) high-temperature conversion of wax dilute solution in methane. The wax, synthesized by Fischer-Tropsch method, initially contained a mixture of C17-C120 linear paraffins. The yield of wax conversion to liquid mixture (C4-C27 alkenes and 61.5% alkanes) via mode (1) was 0.83±0.09 μmole/J, whereas yield of gas conversion to liquid mixture (C5-C13 alkanes) via mode (2) was 0.95±0.02 μmole/J. In the dilute solution wax underwent indirect action of radiation. In comparison with (1) the mode (3) produces similar amount of lighter fuel containing 80% of alkanes (C5-C15). At the same time degree of methane fixation is almost three times higher.

  11. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  12. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  13. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  14. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated alkane aromatic compound... Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical... as a halogenated alkane aromatic compound (PMN P-94-1747) is subject to reporting under this...

  15. 40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Mixture of hydrofluoro alkanes and... Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical... as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs P-96-945/946/947/948) are subject...

  16. 40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Mixture of hydrofluoro alkanes and... Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical... as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs P-96-945/946/947/948) are subject...

  17. 40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Mixture of hydrofluoro alkanes and... Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical... as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs P-96-945/946/947/948) are subject...

  18. 40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Mixture of hydrofluoro alkanes and... Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical... as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs P-96-945/946/947/948) are subject...

  19. 40 CFR 721.4464 - Mixture of hydrofluoro alkanes and hydrofluoro alkene.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixture of hydrofluoro alkanes and... Specific Chemical Substances § 721.4464 Mixture of hydrofluoro alkanes and hydrofluoro alkene. (a) Chemical... as a mixture of hydrofluoro alkanes and hydrofluoro alkene (PMNs P-96-945/946/947/948) are subject...

  20. Impacts of Conformational Geometries in Fluorinated Alkanes.

    PubMed

    Brandenburg, Tim; Golnak, Ronny; Nagasaka, Masanari; Atak, Kaan; Sreekantan Nair Lalithambika, Sreeju; Kosugi, Nobuhiro; Aziz, Emad F

    2016-01-01

    Research of blood substitute formulations and their base materials is of high scientific interest. Especially fluorinated microemulsions based on perfluorocarbons, with their interesting chemical properties, offer opportunities for applications in biomedicine and physical chemistry. In this work, carbon K-edge absorption spectra of liquid perfluoroalkanes and their parent hydrocarbons are presented and compared. Based on soft X-ray absorption, a comprehensive picture of the electronic structure is provided with the aid of time dependent density functional theory. We have observed that conformational geometries mainly influence the chemical and electronic interactions in the presented liquid materials, leading to a direct association of conformational geometries to the dissolving capacity of the presented perfluorocarbons with other solvents like water and possibly gases like oxygen. PMID:27527753

  1. Impacts of Conformational Geometries in Fluorinated Alkanes

    PubMed Central

    Brandenburg, Tim; Golnak, Ronny; Nagasaka, Masanari; Atak, Kaan; Sreekantan Nair Lalithambika, Sreeju; Kosugi, Nobuhiro; Aziz, Emad F.

    2016-01-01

    Research of blood substitute formulations and their base materials is of high scientific interest. Especially fluorinated microemulsions based on perfluorocarbons, with their interesting chemical properties, offer opportunities for applications in biomedicine and physical chemistry. In this work, carbon K-edge absorption spectra of liquid perfluoroalkanes and their parent hydrocarbons are presented and compared. Based on soft X-ray absorption, a comprehensive picture of the electronic structure is provided with the aid of time dependent density functional theory. We have observed that conformational geometries mainly influence the chemical and electronic interactions in the presented liquid materials, leading to a direct association of conformational geometries to the dissolving capacity of the presented perfluorocarbons with other solvents like water and possibly gases like oxygen. PMID:27527753

  2. Impacts of Conformational Geometries in Fluorinated Alkanes

    NASA Astrophysics Data System (ADS)

    Brandenburg, Tim; Golnak, Ronny; Nagasaka, Masanari; Atak, Kaan; Sreekantan Nair Lalithambika, Sreeju; Kosugi, Nobuhiro; Aziz, Emad F.

    2016-08-01

    Research of blood substitute formulations and their base materials is of high scientific interest. Especially fluorinated microemulsions based on perfluorocarbons, with their interesting chemical properties, offer opportunities for applications in biomedicine and physical chemistry. In this work, carbon K-edge absorption spectra of liquid perfluoroalkanes and their parent hydrocarbons are presented and compared. Based on soft X-ray absorption, a comprehensive picture of the electronic structure is provided with the aid of time dependent density functional theory. We have observed that conformational geometries mainly influence the chemical and electronic interactions in the presented liquid materials, leading to a direct association of conformational geometries to the dissolving capacity of the presented perfluorocarbons with other solvents like water and possibly gases like oxygen.

  3. Diffusion of squalene in n-alkanes and squalane.

    PubMed

    Kowert, Bruce A; Watson, Michael B; Dang, Nhan C

    2014-02-27

    Squalene, an intermediate in the biosynthesis of cholesterol, has a 24-carbon backbone with six methyl groups and six isolated double bonds. Capillary flow techniques have been used to determine its translational diffusion constant, D, at room temperature in squalane, n-C16, and three n-C8-squalane mixtures. The D values have a weaker dependence on viscosity, η, than predicted by the Stokes-Einstein relation, D = kBT/(6πηr). A fit to the modified relation, D/T = ASE/η(p), gives p = 0.820 ± 0.028; p = 1 for the Stokes-Einstein limit. The translational motion of squalene appears to be much like that of n-alkane solutes with comparable chain lengths; their D values show similar deviations from the Stokes-Einstein model. The n-alkane with the same carbon chain length as squalene, n-C24, has a near-equal p value of 0.844 ± 0.018 in n-alkane solvents. The values of the hydrodynamic radius, r, for n-C24, squalene, and other n-alkane solutes decrease as the viscosity increases and have a common dependence on the van der Waals volumes of the solute and solvent. The possibility of studying squalene in lipid droplets and membranes is discussed.

  4. Catalytic production of branched small alkanes from biohydrocarbons.

    PubMed

    Oya, Shin-ichi; Kanno, Daisuke; Watanabe, Hideo; Tamura, Masazumi; Nakagawa, Yoshinao; Tomishige, Keiichi

    2015-08-10

    Squalane, C30 algae-derived branched hydrocarbon, was successfully converted to smaller hydrocarbons without skeletal isomerization and aromatization over ruthenium on ceria (Ru/CeO2 ). The internal CH2 CH2 bonds located between branches are preferably dissociated to give branched alkanes with very simple distribution as compared with conventional methods using metal-acid bifunctional catalysts.

  5. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1993-05-18

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso- and/or [beta]-pyrrolic positions.

  6. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, P.E. Jr.; Lyons, J.E.

    1995-01-17

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or [beta]-pyrrolic positions.

  7. Diffusion of squalene in n-alkanes and squalane.

    PubMed

    Kowert, Bruce A; Watson, Michael B; Dang, Nhan C

    2014-02-27

    Squalene, an intermediate in the biosynthesis of cholesterol, has a 24-carbon backbone with six methyl groups and six isolated double bonds. Capillary flow techniques have been used to determine its translational diffusion constant, D, at room temperature in squalane, n-C16, and three n-C8-squalane mixtures. The D values have a weaker dependence on viscosity, η, than predicted by the Stokes-Einstein relation, D = kBT/(6πηr). A fit to the modified relation, D/T = ASE/η(p), gives p = 0.820 ± 0.028; p = 1 for the Stokes-Einstein limit. The translational motion of squalene appears to be much like that of n-alkane solutes with comparable chain lengths; their D values show similar deviations from the Stokes-Einstein model. The n-alkane with the same carbon chain length as squalene, n-C24, has a near-equal p value of 0.844 ± 0.018 in n-alkane solvents. The values of the hydrodynamic radius, r, for n-C24, squalene, and other n-alkane solutes decrease as the viscosity increases and have a common dependence on the van der Waals volumes of the solute and solvent. The possibility of studying squalene in lipid droplets and membranes is discussed. PMID:24528091

  8. Improving alkane synthesis in Escherichia coli via metabolic engineering.

    PubMed

    Song, Xuejiao; Yu, Haiying; Zhu, Kun

    2016-01-01

    Concerns about energy security and global petroleum supply have made the production of renewable biofuels an industrial imperative. The ideal biofuels are n-alkanes in that they are chemically and structurally identical to the fossil fuels and can "drop in" to the transportation infrastructure. In this work, an Escherichia coli strain that produces n-alkanes was constructed by heterologous expression of acyl-acyl carrier protein (ACP) reductase (AAR) and aldehyde deformylating oxygenase (ADO) from Synechococcus elongatus PCC7942. The accumulation of alkanes ranged from 3.1 to 24.0 mg/L using different expressing strategies. Deletion of yqhD, an inherent aldehyde reductase in E. coli, or overexpression of fadR, an activator for fatty acid biosynthesis, exhibited a nearly twofold increase in alkane titers, respectively. Combining yqhD deletion and fadR overexpression resulted in a production titer of 255.6 mg/L in E. coli, and heptadecene was the most abundant product. PMID:26476644

  9. 40 CFR 721.10704 - Aryl-substituted alkane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... reporting. (1) The chemical substance identified generically as an aryl-substituted alkane (PMN P-12-548) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this... communication program. Requirements as specified in § 721.72(a), (b), (c), (d), (e) (concentration set at...

  10. MODELING OF ALKANE EMISSIONS FROM A WOOD STAIN

    EPA Science Inventory

    The article discusses full-scale residential house tests to evaluate the effects of organic emissions from a wood finishing product--wood stain--on indoor air quality (IAQ). The test house concentrations of three alkane species, nonane, decane, and undecane, were measured as a fu...

  11. Diverse alkane hydroxylase genes in microorganisms and environments

    PubMed Central

    Nie, Yong; Chi, Chang-Qiao; Fang, Hui; Liang, Jie-Liang; Lu, She-Lian; Lai, Guo-Li; Tang, Yue-Qin; Wu, Xiao-Lei

    2014-01-01

    AlkB and CYP153 are important alkane hydroxylases responsible for aerobic alkane degradation in bioremediation of oil-polluted environments and microbial enhanced oil recovery. Since their distribution in nature is not clear, we made the investigation among thus-far sequenced 3,979 microbial genomes and 137 metagenomes from terrestrial, freshwater, and marine environments. Hundreds of diverse alkB and CYP153 genes including many novel ones were found in bacterial genomes, whereas none were found in archaeal genomes. Moreover, these genes were detected with different distributional patterns in the terrestrial, freshwater, and marine metagenomes. Hints for horizontal gene transfer, gene duplication, and gene fusion were found, which together are likely responsible for diversifying the alkB and CYP153 genes adapt to the ubiquitous distribution of different alkanes in nature. In addition, different distributions of these genes between bacterial genomes and metagenomes suggested the potentially important roles of unknown or less common alkane degraders in nature. PMID:24829093

  12. Cyano- and polycyanometalloporphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1992-01-01

    Alkanes are oxidized by contact with oxygen-containing gas in the presence as catalyst of a metalloporphyrin in which hydrogen atoms in the porphyrin ring have been substituted with one or more cyano groups. Hydrogen atoms in the porphyrin ring may also be substituted with halogen atoms.

  13. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1995-01-01

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or .beta.-pyrrolic positions.

  14. Cyano- and polycyanometallo-porphyrins as catalysts for alkane oxidation

    DOEpatents

    Ellis, Jr., Paul E.; Lyons, James E.

    1993-01-01

    New compositions of matter comprising cyano-substituted metal complexes of porphyrins are catalysts for the oxidation of alkanes. The metal is iron, chromium, manganese, ruthenium, copper or cobalt. The porphyrin ring has cyano groups attached thereto in meso and/or .beta.-pyrrolic positions.

  15. Improving alkane synthesis in Escherichia coli via metabolic engineering.

    PubMed

    Song, Xuejiao; Yu, Haiying; Zhu, Kun

    2016-01-01

    Concerns about energy security and global petroleum supply have made the production of renewable biofuels an industrial imperative. The ideal biofuels are n-alkanes in that they are chemically and structurally identical to the fossil fuels and can "drop in" to the transportation infrastructure. In this work, an Escherichia coli strain that produces n-alkanes was constructed by heterologous expression of acyl-acyl carrier protein (ACP) reductase (AAR) and aldehyde deformylating oxygenase (ADO) from Synechococcus elongatus PCC7942. The accumulation of alkanes ranged from 3.1 to 24.0 mg/L using different expressing strategies. Deletion of yqhD, an inherent aldehyde reductase in E. coli, or overexpression of fadR, an activator for fatty acid biosynthesis, exhibited a nearly twofold increase in alkane titers, respectively. Combining yqhD deletion and fadR overexpression resulted in a production titer of 255.6 mg/L in E. coli, and heptadecene was the most abundant product.

  16. Pathway of n-Alkane Oxidation in Cladosporium resinae

    PubMed Central

    Walker, J. D.; Cooney, J. J.

    1973-01-01

    Pathways of initial oxidation of n-alkanes were examined in two strains of Cladosporium resinae. Cells grow on dodecane and hexadecane and their primary alcohol and monoic acid derivatives. The homologous aldehydes do not support growth but are oxidized by intact cells and by cell-free preparations. Hexane and its derivatives support little or no growth, but cell extracts oxidize hexane, hexanol, and hexanal. Alkane oxidation by extracts is stimulated by reduced nicotinamide adenine dinucleotide (phosphate). Alcohol and aldehyde oxidation are stimulated by nicotinamide adenine dinucleotide (phosphate), and reduced coenzymes accumulate in the presence of cyanide or azide. Extracts supplied with 14C-hexadecane convert it to the alcohol, aldehyde, and acid. Therefore, the major pathway for initial oxidation of n-alkanes is via the primary alcohol, aldehyde, and monoic acid, and the system can act on short-, intermediate-, and long-chain substrates. Thus, filamentous fungi appear to oxidize n-alkanes by pathways similar to those used by bacteria and yeasts. PMID:4146874

  17. Crystallization features of normal alkanes in confined geometry.

    PubMed

    Su, Yunlan; Liu, Guoming; Xie, Baoquan; Fu, Dongsheng; Wang, Dujin

    2014-01-21

    How polymers crystallize can greatly affect their thermal and mechanical properties, which influence the practical applications of these materials. Polymeric materials, such as block copolymers, graft polymers, and polymer blends, have complex molecular structures. Due to the multiple hierarchical structures and different size domains in polymer systems, confined hard environments for polymer crystallization exist widely in these materials. The confined geometry is closely related to both the phase metastability and lifetime of polymer. This affects the phase miscibility, microphase separation, and crystallization behaviors and determines both the performance of polymer materials and how easily these materials can be processed. Furthermore, the size effect of metastable states needs to be clarified in polymers. However, scientists find it difficult to propose a quantitative formula to describe the transition dynamics of metastable states in these complex systems. Normal alkanes [CnH2n+2, n-alkanes], especially linear saturated hydrocarbons, can provide a well-defined model system for studying the complex crystallization behaviors of polymer materials, surfactants, and lipids. Therefore, a deeper investigation of normal alkane phase behavior in confinement will help scientists to understand the crystalline phase transition and ultimate properties of many polymeric materials, especially polyolefins. In this Account, we provide an in-depth look at the research concerning the confined crystallization behavior of n-alkanes and binary mixtures in microcapsules by our laboratory and others. Since 2006, our group has developed a technique for synthesizing nearly monodispersed n-alkane containing microcapsules with controllable size and surface porous morphology. We applied an in situ polymerization method, using melamine-formaldehyde resin as shell material and nonionic surfactants as emulsifiers. The solid shell of microcapsules can provide a stable three-dimensional (3-D

  18. Integrated two-liquid phase bioconversion and product-recovery processes for the oxidation of alkanes: Process design and economic evaluation

    SciTech Connect

    Mathys, R.G.; Schmid, A.; Witholt, B.

    1999-08-20

    Pseudomonas oleovorans and recombinant strains containing the alkane oxidation genes can product alkane oxidation genes can produce alkane oxidation products in two-liquid phase bioreactor systems. In these bioprocesses the cells, which grow in the aqueous phase, oxidize apolar, non-water soluble substrates. The apolar products typically accumulate in the emulsified apolar phase. The authors have studied both the bioconversion systems and several downstream processing systems to separate and purify alkanols from these two-liquid phase media. Based on the information generated in these studies, the authors have now designed bioconversion and downstream processing systems for the production of 1-alkanols from n-alkanes on a 10 kiloton/yr scale, taking the conversion of n-octane to 1-octanol as a model system. Here, the authors describe overall designs of fed-batch and continuous-fermentation processes for the oxidation of octane to 1-octanol by Pseudomonas oleovoran, and the authors discuss the economics of these processes. The overall performance of each of these two systems has been modeled with Aspen software. Although the continuous process is about 10% more expensive than the fed-batch process, improvements to reduce overall cost can be achieved more easily for continuous than for fed-batch fermentation by decreasing the dilution rate while maintaining near constant productivity. Improvements relevant to both processes can be achieved by increasing the biocatalyst performance, which results in improved overall efficiency, decreased capital investment, and hence, decreased production cost.

  19. Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions.

    PubMed

    Ballal, Deepti; Venkataraman, Pradeep; Fouad, Wael A; Cox, Kenneth R; Chapman, Walter G

    2014-08-14

    Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ε(W)/k = 220 K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E-ε(W)/k = 78.2 K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally. PMID:25134597

  20. Isolating the non-polar contributions to the intermolecular potential for water-alkane interactions.

    PubMed

    Ballal, Deepti; Venkataraman, Pradeep; Fouad, Wael A; Cox, Kenneth R; Chapman, Walter G

    2014-08-14

    Intermolecular potential models for water and alkanes describe pure component properties fairly well, but fail to reproduce properties of water-alkane mixtures. Understanding interactions between water and non-polar molecules like alkanes is important not only for the hydrocarbon industry but has implications to biological processes as well. Although non-polar solutes in water have been widely studied, much less work has focused on water in non-polar solvents. In this study we calculate the solubility of water in different alkanes (methane to dodecane) at ambient conditions where the water content in alkanes is very low so that the non-polar water-alkane interactions determine solubility. Only the alkane-rich phase is simulated since the fugacity of water in the water rich phase is calculated from an accurate equation of state. Using the SPC/E model for water and TraPPE model for alkanes along with Lorentz-Berthelot mixing rules for the cross parameters produces a water solubility that is an order of magnitude lower than the experimental value. It is found that an effective water Lennard-Jones energy ε(W)/k = 220 K is required to match the experimental water solubility in TraPPE alkanes. This number is much higher than used in most simulation water models (SPC/E-ε(W)/k = 78.2 K). It is surprising that the interaction energy obtained here is also higher than the water-alkane interaction energy predicted by studies on solubility of alkanes in water. The reason for this high water-alkane interaction energy is not completely understood. Some factors that might contribute to the large interaction energy, such as polarizability of alkanes, octupole moment of methane, and clustering of water at low concentrations in alkanes, are examined. It is found that, though important, these factors do not completely explain the anomalously strong attraction between alkanes and water observed experimentally.

  1. Numerical and experimental studies of ethanol flames and autoignition theory for higher alkanes

    NASA Astrophysics Data System (ADS)

    Saxena, Priyank

    In order to enhance the fuel efficiency of an engine and to control pollutant formation, an improved understanding of the combustion chemistry of the fuels at a fundamental level is paramount. This knowledge can be gained by developing detailed reaction mechanisms of the fuels for various combustion processes and by studying combustion analytically employing reduced-chemistry descriptions. There is a need for small detailed reaction mechanisms for alkane and alcohol fuels with reduced uncertainties in their combustion chemistry that are computationally cheaper in multidimensional CFD calculations. Detailed mechanisms are the starting points in identifying reduced-chemistry descriptions of combustion processes to study problems analytically. This research includes numerical, experimental and analytical studies. The first part of the dissertation consists of numerical and experimental studies of ethanol flames. Although ethanol has gained popularity as a possible low-pollution source of renewable energy, significant uncertainties remain in its combustion chemistry. To begin to address ethanol combustion, first a relatively small detailed reaction mechanism, commonly known as the San Diego Mech, is developed for the combustion of hydrogen, carbon monoxide, formaldehyde, methane, methanol, ethane, ethylene, and acetylene, in air or oxygen-inert mixtures. This mechanism is tested for autoignition, premixed-flame burning velocities, and structures and extinction of diffusion flames and of partially premixed flames of many of these fuels. The reduction in uncertainties in the combustion chemistry can best be achieved by consistently updating a reaction mechanism with reaction rate data for the elementary steps based on newer studies in literature and by testing it against as many experimental conditions as available. The results of such a testing for abovementioned fuels are reported here along with the modifications of reaction-rate parameters of the most important

  2. Recent Advances in Catalytic Conversion of Ethanol to Chemicals

    SciTech Connect

    Sun, Junming; Wang, Yong

    2014-04-30

    With increased availability and decreased cost, ethanol is potentially a promising platform molecule for the production of a variety of value-added chemicals. In this review, we provide a detailed summary of recent advances in catalytic conversion of ethanol to a wide range of chemicals and fuels. We particularly focus on catalyst advances and fundamental understanding of reaction mechanisms involved in ethanol steam reforming (ESR) to produce hydrogen, ethanol conversion to hydrocarbons ranging from light olefins to longer chain alkenes/alkanes and aromatics, and ethanol conversion to other oxygenates including 1-butanol, acetaldehyde, acetone, diethyl ether, and ethyl acetate.

  3. Hydrogen isotope composition of leaf wax n-alkanes in glaucous and non-glaucous varieties of wheat (Triticum spp.)

    NASA Astrophysics Data System (ADS)

    Pedentchouk, Nikolai; Eley, Yvette; Frizell-Armitage, Amelia; Uauy, Cristobal

    2015-04-01

    The use of the 2H/1H composition of terrestrial plants in climate and ecology studies depends on fundamental understanding of the processes within the plant that control fractionation of these two isotopes. Little is currently known about the extent of 2H/1H fractionation at different steps of biosynthesis, after the initial H uptake following leaf water photolysis. Knowing this effect is particularly important when seeking to interpret the 2H/1H composition of leaf wax biomarkers from plants that differ in the amount and type of individual compound classes in their leaf waxes. The purpose of this study was to investigate the link between the quantity and distribution of n-alkyl lipids in leaf waxes and their isotopic composition. We used a genetic approach to suppress glaucousness in 2 varieties of wheat (Alchemy and Malacca), which resulted in glaucous and non-glaucous phenotypes of both varieties. Both phenotypes were then grown outdoors under identical environmental conditions in central Norfolk, UK. At the end of the growing season, the plants were sampled for soil water, leaf water, and leaf wax isotopic measurements. Comparison of the leaf wax composition of the non-glaucous and glaucous phenotypes revealed that the non-glaucous varieties were characterised by the absence of diketones and a greater concentration of n-alkanes and primary alcohols.. Our results showed very small differences between glaucous and non-glaucous varieties with regard to soil (mean values, <2 per mil) and leaf (<1 per mil) water 2H/1H. Conversely, there was 15-20 and 10-15 per mil 2H-depletion in the C29 and C31 n-alkanes, respectively, from the non-glaucous phenotype. This 2H-depletion in the non-glaucous phenotype demonstrated that the suppression of diketone production and the increase in n-alkane and primary alcohol concentrations are linked with a shift in the 2H/1H composition of n-alkanes. The initial results of this work suggest that plants using the same environmental water

  4. Flash Points of Secondary Alcohol and n-Alkane Mixtures.

    PubMed

    Esina, Zoya N; Miroshnikov, Alexander M; Korchuganova, Margarita R

    2015-11-19

    The flash point is one of the most important characteristics used to assess the ignition hazard of mixtures of flammable liquids. To determine the flash points of mixtures of secondary alcohols with n-alkanes, it is necessary to calculate the activity coefficients. In this paper, we use a model that allows us to obtain enthalpy of fusion and enthalpy of vaporization data of the pure components to calculate the liquid-solid equilibrium (LSE) and vapor-liquid equilibrium (VLE). Enthalpy of fusion and enthalpy of vaporization data of secondary alcohols in the literature are limited; thus, the prediction of these characteristics was performed using the method of thermodynamic similarity. Additionally, the empirical models provided the critical temperatures and boiling temperatures of the secondary alcohols. The modeled melting enthalpy and enthalpy of vaporization as well as the calculated LSE and VLE flash points were determined for the secondary alcohol and n-alkane mixtures. PMID:26491811

  5. Influence of high biomass concentrations on alkane solubilities.

    PubMed

    Davison, B H; Barton, J W; Klasson, K T; Francisco, A B

    2000-05-01

    Alkane solubilities were measured experimentally for high-density biomass. The resulting Henry's law constants for propane were found to decrease significantly for both dense yeast suspensions and an actual propane-degrading biofilm consortium. At the biomass densities of a typical biofilm, propane solubility was about an order of magnitude greater than that in pure water. For example, a dense biofilm had a propane Henry's law constant of 0.09+/-0.04 atm m(3) mol(-1) compared to 0.6+/-0.1 atm m(3) mol(-1) measured in pure water. The results were modeled with mixing rules and compared with octanol-water mixtures. Hydrogels (agar) and salts decreased the alkane solubility. By considering a theoretical solubility of propane in dry biomass, estimates were made of intrinsic Henry's law constants for propane in pure yeast and biomass, which were 13+/-2 and 5+/-2 atm kg biomass mol(-1) for yeast and biofilm consortium, respectively.

  6. Site isolation in vanadium phosphorus oxide alkane oxidation

    SciTech Connect

    Thompson, M R; Ebner, J R

    1991-06-01

    Single crystal X-ray diffraction studies of vanadyl pyrophosphate indicate that at least two polytypical structures exists for this active and selective alkane oxidation catalyst. The crystal structures of these materials differ with respect to the symmetry and direction of columns of vanadyl groups within the unit cell. Single crystals of vanadyl pyrophosphate have been generated at extreme temperatures not often experienced by microcrystalline catalysts. The crystallography of the system suggests that other crystalline modifications or disordered phases might also exist. Zeroth-order models of crystal surface termination of vanadyl pyrophosphate have been constructed which conceptually illustrate the ability of vanadyl pyrophosphate to accommodate varying amounts of surface phosphorus parallel to (1,0,0), (0,1,0) and (0,2,4). Pyrophosphate termination of surfaces parallel to (1,0,0) likely results in the isolation of clusters of reactive centers and limits overoxidation of the alkane substrate. 23 refs., 6 figs.

  7. Surface crystallization and thin film melting in normal alkanes

    SciTech Connect

    Wu, X.Z. |; Shao, H.H. |; Ocko, B.M.; Deutsch, M.; Sinha, S.K.; Kim, M.W.; King, H.E. Jr.; Sirota, E.B.

    1994-12-31

    Normal alkanes of carbon number n > 14 exhibit surface crystallization at their liquid-vapor interface. This has been investigated with x-ray reflectivity, grazing incidence scattering and surface tension measurements. The structure and thermodynamics of the surface layer is consistent with a monolayer of the bulk rotator phase occurring at the surface above the bulk melting temperature. On the other hand, thin films of alkanes on SiO{sub 2}, exhibit a reduction of the melting temperature. The surface crystalline phase is observed for carbon number n > 14. The vanishing of surface phase for small n may be due to a transition from surface freezing to surface melting behavior. These measurements can yield the relative surface energies of the various phases. 41 refs.

  8. Glucose transport and its inhibition by short-chain n-alkanes in Cladosporium resinae.

    PubMed Central

    Teh, J S

    1975-01-01

    Glucose transport in Cladosporium resinae was studies with the aid of the non-metabolizable glucose analogue 3-O-methyl-D-glucose (3-O-MG). 3-O-MG, transported as a free sugar without phosphorylation, was found to inhibit glucose uptake competitively. Conversely, glucose was a competitive inhibitor of 3-O-MG uptake. Moreover, both glucose and 3-O-MG were able to bring about rapid counterflow intracellular 3-O-MG. Thus, glucose and 3-O-MG share the same entry and exit systems. The transport of 3-O-MG is carrier mediated and energy dependent as shown by saturation kinetics, strong temperature dependence, accumulation of unaltered 3-O-MG against a concentration gradient, and inhibition of uptake by NaN3, NaCN, and 2,4-dinitrophenol. The glucose transport system appeared to be constitutive for glucose transport in cells grown on fructose, galactose, mannose, xylose, or glucose. There was no derepressible low-Km glucose transport system in C. resinae. n-Hexane and n-heptane were found to inhibit 3-O-MG uptake rapidly at temperatures above 20 C. Over 50% inhibition of the uptake rate occurred after only 10 min of incubation with n-hexane at 30 C. The percentage of inhibition in the presence of n-hexane, compared to controls in the absence of n-hexane, was found to increase with increasing temperature. Longer-chain n-alkanes (C8 to C18) had no significant effect on uptake. The efflux of intracellular 3-O-MG, which appeared to occur by facilitated diffusion, was not affected by any of the n-alkanes tested including n-hexane. PMID:1171091

  9. At what chain length do unbranched alkanes prefer folded conformations?

    PubMed

    Byrd, Jason N; Bartlett, Rodney J; Montgomery, John A

    2014-03-01

    Short unbranched alkanes are known to prefer linear conformations, whereas long unbranched alkanes are folded. It is not known with certainty at what chain length the linear conformation is no longer the global minimum. To clarify this point, we use ab initio and density functional methods to compute the relative energies of the linear and hairpin alkane conformers for increasing chain lengths. Extensive electronic structure calculations are performed to obtain optimized geometries, harmonic frequencies, and accurate single point energies for the selected alkane conformers from octane through octadecane. Benchmark CCSD(T)/cc-pVTZ single point calculations are performed for chains through tetradecane, whereas approximate methods are required for the longer chains up to octadecane. Using frozen natural orbitals to unambiguously truncate the virtual orbital space, we are able to compute composite CCSD FNO(T) single point energies for all the chain lengths. This approximate composite method has significant computational savings compared to full CCSD(T) while retaining ∼0.15 kcal/mol accuracy compared to the benchmark results. More approximate dual-basis resolution-of-the-identity double-hybrid DFT calculations are also performed and shown to have reasonable 0.2-0.4 kcal/mol errors compared with our benchmark values. After including contributions from temperature dependent internal energy shifts, we find the preference for folded conformations to lie between hexadecane and octadecane, in excellent agreement with recent experiments [ Lüttschwager , N. O. ; Wassermann , T. N. ; Mata , R. A. ; Suhm , M. A. Angew. Chem. Int. Ed. 2013 , 52 , 463 ]. PMID:24524689

  10. Removal of alkanes from drinking water using membrane technologies

    SciTech Connect

    Fronk, C.A.

    1995-10-01

    Increasingly, the public is concerned about the quality of its drinking water. The chlorinated alkanes are saturated, aliphatic, synthetic organic compounds (SOC`s). When hydrocarbon feedstocks are chlorinated, a wide variety of chlorocarbons and chlorohydrocarbons are produced that are used as industrial solvents, degreasers and intermediaries. Because compounds such as Carbon Tetrachloride and 1,2-Dichloroethane are widely used, they often find their way into drinking water, particularly groundwaters. Surface waters are somewhat less affected bemuse of the high volatility of many chlorinated alkanes. The Drinking Water Research Division is responsible for evaluating various membrane technologies that may be feasible for meeting Maximum Contaminant Levels. Several membrane processes are under investigation to determine their effectiveness in removing SOC`s from drinking water. One study addressed the removal of a variety of alkanes from spiked groundwater by six reverse osmosis membranes: a cellulose acetate, a polyamide (hollow fiber), and four different types of thin-film composite membranes. Progressive chlorination of methanes, ethanes and propanes produces compounds that exhibit differing physicochemical properties. The differences in compound properties have an effect on the removal of these compounds by reverse osmosis membranes. For example only 25% of the methylene chloride (Dichloromethane) was removed by one thin-film composite versus 90% removal of the carbon tetrachloride. In addition, the various membranes are made of different polymeric materials and showed a wide range of removals. Generally, the thin-film composite membranes out performed the other membranes and the more highly chlorinated the compound the better the removal. Pervaporation is yet another membrane process that may prove effective in removal of alkanes and future studies will address its usefulness as a drinking water.

  11. Alkane production from biomass: chemo-, bio- and integrated catalytic approaches.

    PubMed

    Deneyer, Aron; Renders, Tom; Van Aelst, Joost; Van den Bosch, Sander; Gabriëls, Dries; Sels, Bert F

    2015-12-01

    Linear, branched and cyclic alkanes are important intermediates and end products of the chemical industry and are nowadays mainly obtained from fossil resources. In search for alternatives, biomass feedstocks are often presented as a renewable carbon source for the production of fuels, chemicals and materials. However, providing a complete market for all these applications seems unrealistic due to both financial and logistic issues. Despite the very large scale of current alkane-based fuel applications, biomass definitely has the potential to offer a partial solution to the fuel business. For the smaller market of chemicals and materials, a transition to biomass as main carbon source is more realistic and even probably unavoidable in the long term. The appropriate use and further development of integrated chemo- and biotechnological (catalytic) process strategies will be crucial to successfully accomplish this petro-to-bio feedstock transition. Furthermore, a selection of the most promising technologies from the available chemo- and biocatalytic tool box is presented. New opportunities will certainly arise when multidisciplinary approaches are further explored in the future. In an attempt to select the most appropriate biomass sources for each specific alkane-based application, a diagram inspired by van Krevelen is applied, taking into account both the C-number and the relative functionality of the product molecules.

  12. Alkane production from biomass: chemo-, bio- and integrated catalytic approaches.

    PubMed

    Deneyer, Aron; Renders, Tom; Van Aelst, Joost; Van den Bosch, Sander; Gabriëls, Dries; Sels, Bert F

    2015-12-01

    Linear, branched and cyclic alkanes are important intermediates and end products of the chemical industry and are nowadays mainly obtained from fossil resources. In search for alternatives, biomass feedstocks are often presented as a renewable carbon source for the production of fuels, chemicals and materials. However, providing a complete market for all these applications seems unrealistic due to both financial and logistic issues. Despite the very large scale of current alkane-based fuel applications, biomass definitely has the potential to offer a partial solution to the fuel business. For the smaller market of chemicals and materials, a transition to biomass as main carbon source is more realistic and even probably unavoidable in the long term. The appropriate use and further development of integrated chemo- and biotechnological (catalytic) process strategies will be crucial to successfully accomplish this petro-to-bio feedstock transition. Furthermore, a selection of the most promising technologies from the available chemo- and biocatalytic tool box is presented. New opportunities will certainly arise when multidisciplinary approaches are further explored in the future. In an attempt to select the most appropriate biomass sources for each specific alkane-based application, a diagram inspired by van Krevelen is applied, taking into account both the C-number and the relative functionality of the product molecules. PMID:26360875

  13. Dielectric constant of liquid alkanes and hydrocarbon mixtures

    NASA Technical Reports Server (NTRS)

    Sen, A. D.; Anicich, V. G.; Arakelian, T.

    1992-01-01

    The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

  14. Dielectric constant of liquid alkanes and hydrocarbon mixtures.

    PubMed

    Sen, A D; Anicich, V G; Arakelian, T

    1992-01-01

    The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

  15. Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

    DOE PAGES

    Wang, Zhandong; Zhang, Lidong; Moshammer, Kai; Popolan-Vaida, Denisia M.; Shankar, Vijai Shankar Bhavani; Lucassen, Arnas; Hemken, Christian; Taatjes, Craig A.; Leone, Stephen R.; Kohse-Hoinghaus, Katharina; et al

    2015-12-31

    Chain-branching reactions represent a general motif in chemistry, encountered in atmospheric chemistry, combustion, polymerization, and photochemistry; the nature and amount of radicals generated by chain-branching are decisive for the reaction progress, its energy signature, and the time towards its completion. In this study, experimental evidence for two new types of chain-branching reactions is presented, based upon detection of highly oxidized multifunctional molecules (HOM) formed during the gas-phase low-temperature oxidation of a branched alkane under conditions relevant to combustion. The oxidation of 2,5-dimethylhexane (DMH) in a jet-stirred reactor (JSR) was studied using synchrotron vacuum ultra-violet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS).more » Specifically, species with four and five oxygen atoms were probed, having molecular formulas of C8H14O4 (e.g., diketo-hydroperoxide/keto-hydroperoxy cyclic ether) and C8H16O5 (e.g., keto-dihydroperoxide/dihydroperoxy cyclic ether), respectively. The formation of C8H16O5 species involves alternative isomerization of OOQOOH radicals via intramolecular H-atom migration, followed by third O2 addition, intramolecular isomerization, and OH release; C8H14O4 species are proposed to result from subsequent reactions of C8H16O5 species. The mechanistic pathways involving these species are related to those proposed as a source of low-volatility highly oxygenated species in Earth's troposphere. At the higher temperatures relevant to auto-ignition, they can result in a net increase of hydroxyl radical production, so these are additional radical chain-branching pathways for ignition. Furthermore, the results presented herein extend the conceptual basis of reaction mechanisms used to predict the reaction behavior of ignition, and have implications on atmospheric gas-phase chemistry and the oxidative stability of organic substances.« less

  16. Contentious Conversations

    ERIC Educational Resources Information Center

    Zuidema, Leah A.

    2011-01-01

    The idea of joining a conversation through reading and writing is not new; in his 1941 book "The Philosophy of Literary Form: Studies in Symbolic Action," Kenneth Burke suggests that the acts of reading and writing are like entering a parlor where others are already conversing. The author explores the place of professional debate within NCTE and…

  17. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    Presents background information, laboratory procedures, classroom materials/activities, and chemistry experiments. Topics include sublimation, electronegativity, electrolysis, experimental aspects of strontianite, halide test, evaluation of present and future computer programs in chemistry, formula building, care of glass/saturated calomel…

  18. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Thirteen ideas are presented that may be of use to chemistry teachers. Topics covered include vitamin C, industrial chemistry, electrical conductivity, electrolysis, alkali metals, vibration modes infra-red, dynamic equilibrium, and some new demonstrations in gaseous combinations. (PS)

  19. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1978

    1978-01-01

    Describes experiments, demonstrations, activities and ideas relating to various fields of chemistry to be used in chemistry courses of secondary schools. Three experiments concerning differential thermal analysis are among these notes presented. (HM)

  20. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  1. Colour Chemistry

    ERIC Educational Resources Information Center

    Griffiths, J.; Rattee, I. D.

    1973-01-01

    Discusses the course offerings in pure color chemistry at two universities and the three main aspects of study: dyestuff chemistry, color measurement, and color application. Indicates that there exists a constant challenge to ingenuity in the subject discipline. (CC)

  2. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1982

    1982-01-01

    Presents background information, laboratory procedures, classroom materials/activities, and experiments for chemistry. Topics include superheavy elements, polarizing power and chemistry of alkali metals, particulate carbon from combustion, tips for the chemistry laboratory, interesting/colorful experiments, behavior of bismuth (III) iodine, and…

  3. Reactor system for conversion of alkanes to alkenes in a external fcc catalyst cooler

    SciTech Connect

    Harandi, M.N.; Owen, H.

    1991-05-28

    This patent describes a fluid catalytic cracking reactor system. It comprises: pressurized regenerator vessel means; first valved conduit means; dehydrogenation reactor means; fluid handling means; second valved conduit means; and third conduit means.

  4. Digital biology and chemistry.

    PubMed

    Witters, Daan; Sun, Bing; Begolo, Stefano; Rodriguez-Manzano, Jesus; Robles, Whitney; Ismagilov, Rustem F

    2014-09-01

    This account examines developments in "digital" biology and chemistry within the context of microfluidics, from a personal perspective. Using microfluidics as a frame of reference, we identify two areas of research within digital biology and chemistry that are of special interest: (i) the study of systems that switch between discrete states in response to changes in chemical concentration of signals, and (ii) the study of single biological entities such as molecules or cells. In particular, microfluidics accelerates analysis of switching systems (i.e., those that exhibit a sharp change in output over a narrow range of input) by enabling monitoring of multiple reactions in parallel over a range of concentrations of signals. Conversely, such switching systems can be used to create new kinds of microfluidic detection systems that provide "analog-to-digital" signal conversion and logic. Microfluidic compartmentalization technologies for studying and isolating single entities can be used to reconstruct and understand cellular processes, study interactions between single biological entities, and examine the intrinsic heterogeneity of populations of molecules, cells, or organisms. Furthermore, compartmentalization of single cells or molecules in "digital" microfluidic experiments can induce switching in a range of reaction systems to enable sensitive detection of cells or biomolecules, such as with digital ELISA or digital PCR. This "digitizing" offers advantages in terms of robustness, assay design, and simplicity because quantitative information can be obtained with qualitative measurements. While digital formats have been shown to improve the robustness of existing chemistries, we anticipate that in the future they will enable new chemistries to be used for quantitative measurements, and that digital biology and chemistry will continue to provide further opportunities for measuring biomolecules, understanding natural systems more deeply, and advancing molecular and

  5. Mononuclear Nonheme High-Spin Iron(III)-Acylperoxo Complexes in Olefin Epoxidation and Alkane Hydroxylation Reactions.

    PubMed

    Wang, Bin; Lee, Yong-Min; Clémancey, Martin; Seo, Mi Sook; Sarangi, Ritimukta; Latour, Jean-Marc; Nam, Wonwoo

    2016-02-24

    Mononuclear nonheme high-spin iron(III)-acylperoxo complexes bearing an N-methylated cyclam ligand were synthesized, spectroscopically characterized, and investigated in olefin epoxidation and alkane hydroxylation reactions. In the epoxidation of olefins, epoxides were yielded as the major products with high stereo-, chemo-, and enantioselectivities; cis- and trans-stilbenes were oxidized to cis- and trans-stilbene oxides, respectively. In the epoxidation of cyclohexene, cyclohexene oxide was formed as the major product with a kinetic isotope effect (KIE) value of 1.0, indicating that nonheme iron(III)-acylperoxo complexes prefer C═C epoxidation to allylic C-H bond activation. Olefin epoxidation by chiral iron(III)-acylperoxo complexes afforded epoxides with high enantioselectivity, suggesting that iron(III)-acylperoxo species, not high-valent iron-oxo species, are the epoxidizing agent. In alkane hydroxylation reactions, iron(III)-acylperoxo complexes hydroxylated C-H bonds as strong as those in cyclohexane at -40 °C, wherein (a) alcohols were yielded as the major products with high regio- and stereoselectivities, (b) activation of C-H bonds by the iron(III)-acylperoxo species was the rate-determining step with a large KIE value and good correlation between reaction rates and bond dissociation energies of alkanes, and (c) the oxygen atom in the alcohol product was from the iron(III)-acylperoxo species, not from molecular oxygen. In isotopically labeled water (H2(18)O) experiments, incorporation of (18)O from H2(18)O into oxygenated products was not observed in the epoxidation and hydroxylation reactions. On the basis of mechanistic studies, we conclude that mononuclear nonheme high-spin iron(III)-acylperoxo complexes are strong oxidants capable of oxygenating hydrocarbons prior to their conversion into iron-oxo species via O-O bond cleavage.

  6. Hydrogen-transferring pyrolysis of long-chain alkanes and thermal stability improvement of jet fuels by hydrogen donors

    SciTech Connect

    Song, C.; Lai, W.C.; Schobert, H.H. . Fuel Science Program)

    1994-03-01

    Hydrogen-transferring pyrolysis refers to the thermal decomposition of hydrocarbons in the presence of hydrogen donors. Relative to the pyrolysis of pure n-tetradecane (C[sub 14]H[sub 28]) at 450 C, adding 10 vol % of H-donor tetralin suppressed n-C[sub 14] conversion by 68 % after 12 min of residence time, by about 66% after 21 min, and by 37% after 30 min. The presence of tetralin not only inhibited the n-C[sub 14] decomposition, but also altered the product distribution. The decomposition and isomerization of primary radicals are strongly suppressed, leading to a much higher ratio of the 1-alkene to n-alkane with 12 carbon atoms and slightly higher alkene/alkane ratio for the other product groups. The overall reaction mechanism for the initial stage of hydrogen-transferring pyrolysis is characterized by a one-step [beta]-scission of secondary radical followed by H-abstraction of the resulting primary radical. Moreover, desirable effects of the H-donor are also observed even after 240 min at 450 C, especially for inhibiting solid deposition. The authors also examined the effect of tetralin addition on the deposit formation from a paraffinic jet fuel JP-8 which is rich in C[sub 9]-C[sub 16] long-chain alkanes, and an aromatic compound, n-butylbenzene. Adding 10 vol % tetralin to a JP-8 jet fuel, n-C[sub 14], and n-butylbenzene reduced the formation of deposits by 90% (from 3.1 to 0.3 wt %), 77 % (from 3.0 to 0.7 wt %), and 54 % (from 5.6 to 2.6 wt %), respectively. These results suggest that, by taking advantage of H-transferring pyrolysis, hydrocarbon jet fuels may be used at high operating temperatures with little or no solid deposition.

  7. Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes

    DOEpatents

    Crabtree, Robert H.; Brown, Stephen H.

    1988-01-01

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary alcohols and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  8. Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes

    DOEpatents

    Crabtree, R.H.; Brown, S.H.

    1988-02-16

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary alcohols and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  9. Draft Genome Sequence of Gordonia sihwensis Strain 9, a Branched Alkane-Degrading Bacterium

    PubMed Central

    Brown, Lisa M.; Gunasekera, Thusitha S.; Striebich, Richard C.

    2016-01-01

    Gordonia sihwensis strain 9 is a Gram-positive bacterium capable of efficient aerobic degradation of branched and normal alkanes. The draft genome of G. sihwensis S9 is 4.16 Mb in size, with 3,686 coding sequences and 68.1% G+C content. Alkane monooxygenase and P-450 cytochrome genes required for alkane degradation are predicted in G. sihwensis S9. PMID:27340079

  10. Fundamental Flame Velocities of Pure Hydrocarbons I : Alkanes, Alkenes, Alkynes Benzene, and Cyclohexane

    NASA Technical Reports Server (NTRS)

    Gerstein, Melvin; Levine, Oscar; Wong, Edgar L

    1950-01-01

    The flame velocities of 37 pure hydrocarbons including normal and branched alkanes, alkenes, and alkynes; as well as benzene and cyclohexane, together with the experimental technique employed are presented. The normal alkanes have about the same flame velocity from ethane through heptane with methane being about 16 percent lower. Unsaturation increases the flame velocity in the order of alkanes, alkenes, and alkynes. Branching reduces the flame velocity.

  11. CLUSTER CHEMISTRY

    SciTech Connect

    Muetterties, Earl L.

    1980-05-01

    Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.

  12. Forensic Chemistry

    NASA Astrophysics Data System (ADS)

    Bell, Suzanne

    2009-07-01

    Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

  13. Hydrocarbons. Independent Learning Project for Advanced Chemistry (ILPAC). Unit O1.

    ERIC Educational Resources Information Center

    Inner London Education Authority (England).

    This unit on hydrocarbons is one of 10 first year units produced by the Independent Learning Project for Advanced Chemistry (ILPAC). The unit is divided into sections dealing with alkanes, alkenes, alkynes, arenes, and several aspects of the petroleum industry. Two experiments, exercises (with answers), and pre- and post-tests are included.…

  14. Conversation Analysis.

    ERIC Educational Resources Information Center

    Schiffrin, Deborah

    1990-01-01

    Summarizes the current state of research in conversation analysis, referring primarily to six different perspectives that have developed from the philosophy, sociology, anthropology, and linguistics disciplines. These include pragmatics; speech act theory; interactional sociolinguistics; ethnomethodology; ethnography of communication; and…

  15. Molecular screening for alkane hydroxylase genes in Gram-negative and Gram-positive strains.

    PubMed

    Smits, T H; Röthlisberger, M; Witholt, B; van Beilen, J B

    1999-08-01

    We have developed highly degenerate oligonucleotides for polymerase chain reaction (PCR) amplification of genes related to the Pseudomonas oleovorans GPo1 and Acinetobacter sp. ADP1 alkane hydroxylases, based on a number of highly conserved sequence motifs. In all Gram-negative and in two out of three Gram-positive strains able to grow on medium- (C6-C11) or long-chain n-alkanes (C12-C16), PCR products of the expected size were obtained. The PCR fragments were cloned and sequenced and found to encode peptides with 43.2-93.8% sequence identity to the corresponding fragment of the P. oleovorans GPo1 alkane hydroxylase. Strains that were unable to grow on n-alkanes did not yield PCR products with homology to alkane hydroxylase genes. The alkane hydroxylase genes of Acinetobacter calcoaceticus EB104 and Pseudomonas putida P1 were cloned using the PCR products as probes. The two genes allow an alkane hydroxylase-negative mutant of Acinetobacter sp. ADP1 and an Escherichia coli recombinant containing all P. oleovorans alk genes except alkB, respectively, to grow on n-alkanes, showing that the cloned genes do indeed encode alkane hydroxylases. PMID:11207749

  16. Gas-Phase Reactions of Atomic Gold Cations with Linear Alkanes (C2-C9).

    PubMed

    Zhang, Ting; Li, Zi-Yu; Zhang, Mei-Qi; He, Sheng-Gui

    2016-06-30

    To develop proper ionization methods for alkanes, the reactivity of bare or ligated transition metal ions toward alkanes has attracted increasing interests. In this study, the reactions of the gold cations with linear alkanes from ethane up to nonane (CnH2n+2, n = 2-9) under mild conditions have been characterized by mass spectrometry and density functional theory calculations. When reacting with Au(+), small alkanes (n = 2-6) were confirmed to follow specific reaction channels of dehydrogenation for ethane and hydride transfer for others to generate product ions characteristic of the original alkanes, which indicates that Au(+) can act as a reagent ion to ionize alkanes from ethane to n-hexane. Strong dependence of the chain length of alkanes was observed for the rate constants and reaction efficiencies. Extensive fragmentation took place for larger alkanes (n > 6). Theoretical results show that the fragmentation induced by the hydride transfer occurs after the release of AuH. Moreover, the fragmentation of n-heptane was successfully avoided when the reaction took place in a high-pressure reactor. This implies that Au(+) is a potential reagent ion to ionize linear and even the branched alkanes. PMID:27266670

  17. Cloning and expression of three ladA-type alkane monooxygenase genes from an extremely thermophilic alkane-degrading bacterium Geobacillus thermoleovorans B23.

    PubMed

    Boonmak, Chanita; Takahashi, Yasunori; Morikawa, Masaaki

    2014-05-01

    An extremely thermophilic bacterium, Geobacillus thermoleovorans B23, is capable of degrading a broad range of alkanes (with carbon chain lengths ranging between C11 and C32) at 70 °C. Whole-genome sequence analysis revealed that unlike most alkane-degrading bacteria, strain B23 does not possess an alkB-type alkane monooxygenase gene. Instead, it possesses a cluster of three ladA-type genes, ladAαB23, ladAβB23, and ladB B23, on its chromosome, whose protein products share significant amino acid sequence identities, 49.8, 34.4, and 22.7 %, respectively, with that of ladA alkane monooxygenase gene found on a plasmid of Geobacillus thermodetrificans NG 80-2. Each of the three genes, ladAαB23, ladAβB23, and ladB B23, was heterologously expressed individually in an alkB1 deletion mutant strain, Pseudomonas fluorescens KOB2Δ1. It was found that all three genes were functional in P. fluorescens KOB2Δ1, and partially restored alkane degradation activity. In this study, we suggest that G. thermoleovorans B23 utilizes multiple LadA-type alkane monooxygenases for the degradation of a broad range of alkanes.

  18. Energy conversion & storage program. 1994 annual report

    SciTech Connect

    Cairns, E.J.

    1995-04-01

    The Energy Conversion and Storage Program investigates state-of-the-art electrochemistry, chemistry, and materials science technologies for: (1) development of high-performance rechargeable batteries and fuel cells; (2) development of high-efficiency thermochemical processes for energy conversion; (3) characterization of complex chemical processes and chemical species; (4) study and application of novel materials for energy conversion and transmission. Research projects focus on transport process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  19. Energy Conversion & Storage Program, 1993 annual report

    SciTech Connect

    Cairns, E.J.

    1994-06-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in: production of new synthetic fuels; development of high-performance rechargeable batteries and fuel cells; development of high-efficiency thermochemical processes for energy conversion; characterization of complex chemical processes and chemical species; and the study and application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis.

  20. Systematic study of aggregation structure and thermal behavior of a series of unique H-shape alkane molecules.

    PubMed

    Yamamoto, Hiroko; Tashiro, Kohji; Nemoto, Norio; Motoyama, Yukihiro; Takahashi, Yoshiaki

    2011-08-11

    The H-shape alkanes of various arm lengths have been synthesized successfully through the Grignard reaction. The detailed investigation of these novel compounds may allow us to widen the topological chemistry field furthermore. The molecular form and molecular packing structure in the crystal lattice have been revealed successfully on the basis of X-ray structure analysis as well as the analysis of Raman longitudinal acoustic modes (LAM) sensitive to the alkyl zigzag chain segments. The molecular conformation in the crystal lattice is deformed markedly from the originally imagined H-shape. In the cases of C3HOH to C6HOH, for example, the molecules are packed in a complicated manner and the OH···O hydrogen bonds govern the whole intermolecular interactions mainly. Since the alkyl segmental length is not very long, the conformational change is not very drastic, i.e., the small configurational entropy. Synergic effect of the hydrogen bonds and the small configurational entropy gives the higher melting point as known from the thermal data. On the other hand, in the cases of C10HOH and C12HOH, one of the long alkyl chain arms is found to be bent by 90° so that all of the alky chain segments of planar-zigzag conformation can be packed as closely as possible, and the intermolecular OH···O hydrogen bonds are also formed effectively without any mistake. As a result, the contribution of nonbonded intra- and intermolecular van der Waals interactions between the trans-zigzag alkyl chain segments become major, and the coupling of this enthalpy effect with the larger configurational entropy effect of the molecular shape results in the decrement of the melting point which approaches gradually that of longer n-alkane compound. In this way a sensitive balance between the nonbonded van der Waals interactions, the OH···O hydrogen bonds, as well as the configurational entropy effect gives the characteristic thermal behavior of the H-shape compounds. The thus

  1. Identification and use of an alkane transporter plug-in for applications in biocatalysis and whole-cell biosensing of alkanes

    NASA Astrophysics Data System (ADS)

    Grant, Chris; Deszcz, Dawid; Wei, Yu-Chia; Martínez-Torres, Rubéns Julio; Morris, Phattaraporn; Folliard, Thomas; Sreenivasan, Rakesh; Ward, John; Dalby, Paul; Woodley, John M.; Baganz, Frank

    2014-07-01

    Effective application of whole-cell devices in synthetic biology and biocatalysis will always require consideration of the uptake of molecules of interest into the cell. Here we demonstrate that the AlkL protein from Pseudomonas putida GPo1 is an alkane import protein capable of industrially relevant rates of uptake of C7-C16 n-alkanes. Without alkL expression, native E.coli n-alkane uptake was the rate-limiting step in both the whole-cell bioconversion of C7-C16 n-alkanes and in the activation of a whole-cell alkane biosensor by C10 and C11 alkanes. By coexpression of alkL as a transporter plug-in, specific yields improved by up to 100-fold for bioxidation of >C12 alkanes to fatty alcohols and acids. The alkL protein was shown to be toxic to the host when overexpressed but when expressed from a vector capable of controlled induction, yields of alkane oxidation were improved a further 10-fold (8 g/L and 1.7 g/g of total oxidized products). Further testing of activity on n-octane with the controlled expression vector revealed the highest reported rates of 120 μmol/min/g and 1 g/L/h total oxidized products. This is the first time AlkL has been shown to directly facilitate enhanced uptake of C10-C16 alkanes and represents the highest reported gain in product yields resulting from its use.

  2. Optimization of H3O+/O2+ Dual-mode Ionization in PTR-MS for Simultaneous Detection of Alkanes, Olefins and Aromatic Compounds

    NASA Astrophysics Data System (ADS)

    Amador-Muñoz, O.; Misztal, P. K.; Weber, R.; Drozd, G.; Worton, D. R.; Goldstein, A. H.

    2014-12-01

    Measurements of VOC composition from fossil fuels are analytically challenging because of the complex mixture of hydrocarbons (saturated, unsaturated, aromatics, etc). Speciated chemical measurements typically rely on relatively slow GC separation. Proton transfer reaction mass spectrometry (PTR-MS) is advantageous due to its fast response and high sensitivity. The most common ionization mechanism applied to VOC detection by PTR-MS is proton transfer from hydronium ion (H3O+). However, alkanes cannot be detected using H3O+ ionization chemistry because their proton affinities are too low. Ionization of alkanes is possible via electron transfer and/or hydride abstraction using O2+ or NO+. We used PTR-MS to analyze aromatic, alkene and alkane (linear, branched and cyclic) compounds simultaneously not by switching the ionization agents, but by adjusting the drift tube voltage and optimizing the ratio of H3O+/O2+ produced in the instrument's ion source. The highest detection sensitivity for aromatic and alkene compounds was produced by proton transfer from H3O+, while hydride abstraction by O2+ allowed detection of alkanes. For alkanes, sensitivities ranged from 1.1±0.01 cps/ppbv for n-decane to 74.7±0.25 cps/ppbv for decalin. Sensitivities in O2+ mode were from 6 (Adamantane) to 146 (4-Methyl nonane) times higher than those obtained in H3O+ mode under the same ion source and drift tube voltage conditions. Sensitivities for butyl benzene and 1-decene were 157±0.57 and 66.8±0.21 cps/ppbv, respectively. Sensitivity differences among C10 hydrocarbons are related to their structure, which affects their ionization energies (IE) and hence ease of hydride abstraction. Sensitivities at the parent ion mass were inversely correlated with IE (142 cps/ppbv/eV). This suggests higher electronic stability for cyclic non substituted compounds, followed by cyclic substituted, branch linear and linear C10 hydrocarbons. Although selectivity is a known shortcoming of quadrupole

  3. [Normal alkanes characteristic parameters of Jinzhou Bay surface sediments].

    PubMed

    Li, Ze-Li; Ma, Qi-Min; Cheng, Hai-Ou; Xu, Shao-Qing

    2011-11-01

    The concentration, composition and characteristic parameters of 18 surface sediment samples collected from Jinzhou Bay were studied. The samples were soxhlet-extracted with a mixture of 1: 1 (V/V) dichloromethane-hexane and analyzed by GC-MS after purification and concentration. Concentrations of n-alkanes vary from 1.9 to 4.2 microg x g(-1) with an average value of 2.6 microg x g(-1) dry weight. n-Alkanes distribution patterns of all positions were characterized by double peak-cluster, which means double sources from terrestrial and marine origin. The sum of nC25 to nC31 accounts for 20%-32% of the total n-alkanes, while the average value of L/H, C31/C19, TAR ratio are 0.67, 3.06, 2.02, respectively. All of these three indices suggest that the terrestrial contributions are higher than marine sources, especially for No. 2, 3 and 7 stations, which were influenced by riverinput nearby. Carbon Preference Index (CPI) ranges from 1.19 to 2.63 with an average value of 1.73, which is close to 1; the ratio of Pristane/Phytane (Pr/Ph) and unresolved/resolved compounds (U/R) range from 0.91 to 1.28, 2.2 to 4.3, respectively. All of these three parameters indicate that No. 13 and 15 stations are influenced by petroleum pollution. Comprehensive analysis of various parameters shows that Jinzhou Bay is threatened by both terrestrial inputs and petroleum hydrocarbons contaminations, which may relate to river discharging and port shipping in Jinzhou Bay. PMID:22295627

  4. Analysis of Pseudomonas putida alkane-degradation gene clusters and flanking insertion sequences: evolution and regulation of the alk genes.

    PubMed

    van Beilen, J B; Panke, S; Lucchini, S; Franchini, A G; Röthlisberger, M; Witholt, B

    2001-06-01

    The Pseudomonas putida GPo1 (commonly known as Pseudomonas oleovorans GPo1) alkBFGHJKL and alkST gene clusters, which encode proteins involved in the conversion of n-alkanes to fatty acids, are located end to end on the OCT plasmid, separated by 9.7 kb of DNA. This DNA segment encodes, amongst others, a methyl-accepting transducer protein (AlkN) that may be involved in chemotaxis to alkanes. In P. putida P1, the alkBFGHJKL and alkST gene clusters are flanked by almost identical copies of the insertion sequence ISPpu4, constituting a class 1 transposon. Other insertion sequences flank and interrupt the alk genes in both strains. Apart from the coding regions of the GPo1 and P1 alk genes (80-92% sequence identity), only the alkB and alkS promoter regions are conserved. Competition experiments suggest that highly conserved inverted repeats in the alkB and alkS promoter regions bind ALKS: PMID:11390693

  5. Preliminary assessment of halogenated alkanes as vapor-phase tracers

    SciTech Connect

    Adams, Michael C.; Moore, Joseph N.; Hirtz, Paul

    1991-01-01

    New tracers are needed to evaluate the efficiency of injection strategies in vapor-dominated environments. One group of compounds that seems to meet the requirements for vapor-phase tracing are the halogenated alkanes (HCFCs). HCFCs are generally nontoxic, and extrapolation of tabulated thermodynamic data indicate that they will be thermally stable and nonreactive in a geothermal environment. The solubilities and stabilities of these compounds, which form several homologous series, vary according to the substituent ratios of fluorine, chlorine, and hydrogen. Laboratory and field tests that will further define the suitability of HCFCs as vapor-phase tracers are under way.

  6. Modeling SOA formation from the oxidation of intermediate volatility n-alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

    2012-06-01

    The chemical mechanism leading to SOA formation and ageing is expected to be a multigenerational process, i.e. a successive formation of organic compounds with higher oxidation degree and lower vapor pressure. This process is here investigated with the explicit oxidation model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere). Gas phase oxidation schemes are generated for the C8-C24 series of n-alkanes. Simulations are conducted to explore the time evolution of organic compounds and the behavior of secondary organic aerosol (SOA) formation for various preexisting organic aerosol concentration (COA). As expected, simulation results show that (i) SOA yield increases with the carbon chain length of the parent hydrocarbon, (ii) SOA yield decreases with decreasing COA, (iii) SOA production rates increase with increasing COA and (iv) the number of oxidation steps (i.e. generations) needed to describe SOA formation and evolution grows when COA decreases. The simulated oxidative trajectories are examined in a two dimensional space defined by the mean carbon oxidation state and the volatility. Most SOA contributors are not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA), suggesting that OOA may underestimate SOA. Results show that the model is unable to produce highly oxygenated aerosols (OOA) with large yields. The limitations of the model are discussed.

  7. Modeling SOA formation from the oxidation of intermediate volatility n-alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J.; Madronich, S.

    2012-08-01

    The chemical mechanism leading to SOA formation and ageing is expected to be a multigenerational process, i.e. a successive formation of organic compounds with higher oxidation degree and lower vapor pressure. This process is here investigated with the explicit oxidation model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere). Gas phase oxidation schemes are generated for the C8-C24 series of n-alkanes. Simulations are conducted to explore the time evolution of organic compounds and the behavior of secondary organic aerosol (SOA) formation for various preexisting organic aerosol concentration (COA). As expected, simulation results show that (i) SOA yield increases with the carbon chain length of the parent hydrocarbon, (ii) SOA yield decreases with decreasing COA, (iii) SOA production rates increase with increasing COA and (iv) the number of oxidation steps (i.e. generations) needed to describe SOA formation and evolution grows when COA decreases. The simulated oxidative trajectories are examined in a two dimensional space defined by the mean carbon oxidation state and the volatility. Most SOA contributors are not oxidized enough to be categorized as highly oxygenated organic aerosols (OOA) but reduced enough to be categorized as hydrocarbon like organic aerosols (HOA), suggesting that OOA may underestimate SOA. Results show that the model is unable to produce highly oxygenated aerosols (OOA) with large yields. The limitations of the model are discussed.

  8. Assessment of the GECKO-A modeling tool using chamber observations for C12 alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; La, S.; Ouzebidour, F.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J. M.; Hodzic, A.; Madronich, S.; Yee, L. D.; Loza, C. L.; Craven, J. S.; Zhang, X.; Seinfeld, J.

    2013-12-01

    Secondary Organic Aerosol (SOA) production and ageing is the result of atmospheric oxidation processes leading to the progressive formation of organic species with higher oxidation state and lower volatility. Explicit chemical mechanisms reflect our understanding of these multigenerational oxidation steps. Major uncertainties remain concerning the processes leading to SOA formation and the development, assessment and improvement of such explicit schemes is therefore a key issue. The development of explicit mechanism to describe the oxidation of long chain hydrocarbons is however a challenge. Indeed, explicit oxidation schemes involve a large number of reactions and secondary organic species, far exceeding the size of chemical schemes that can be written manually. The chemical mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) is a computer program designed to overcome this difficulty. GECKO-A generates gas phase oxidation schemes according to a prescribed protocol assigning reaction pathways and kinetics data on the basis of experimental data and structure-activity relationships. In this study, we examine the ability of the generated schemes to explain SOA formation observed in the Caltech Environmental Chambers from various C12 alkane isomers and under high NOx and low NOx conditions. First results show that the model overestimates both the SOA yields and the O/C ratios. Various sensitivity tests are performed to explore processes that might be responsible for these disagreements.

  9. Influence of the hydrogenation step on selectivity during the nonoxidative oligomerization of methane to alkanes on Pt/SiO{sub 2} catalysts (EUROPt-1)

    SciTech Connect

    Marceau, E.; Tatiboueet, J.M.; Che, M.; Saint-Just, J.

    1999-04-25

    Methane oligomerization to alkanes can be accomplished on supported platinum via a two-step procedure: formation of carbonaceous species on the metallic surface by methane adsorption, followed by hydrogenation of these species. Temperature-programmed oxidation (TPO) experiments performed after hydrogenation steps of various durations show that the hydrogenation of a carbonaceous deposit obtained at 300 C on the reference Pt/SiO{sub 2} catalyst EUROPt-1 is not a fast process. Two groups of surface carbonaceous species have been characterized through their different reactivities toward oxygen, but at 300 C their reactivities toward hydrogen are similar. Among alkanes up to C{sub 5}, methane is the main product of hydrogenation, corresponding to one-half of the surface carbon reactive toward hydrogen; linear and branched alkanes are produced from the other half of the reactive carbonaceous species. On EUROPt-1, mainly ethane and n-pentane are produced during the first minutes of reaction, while on a sintered catalyst the initial production in n-pentane is negligible. The release of n-pentane during an intermediate purge with inert gas on EUROPt-1 shows that C-C bonds can form already during methane adsorption, leading to C{sub 5} precursors on specific active sites of this catalyst. A model of formation of C{sub 5} precursors is proposed by analogy with the organometallic chemistry of molecular hydrocarbon platinacycles. The subsequent production of alkanes (C{sub 2} > C{sub 3} > C{sub 4} > C{sub 5}) could be described through a statistical model of dynamic coupling between carbonaceous species involving hydrogen, rather than by hydrogenolysis of heavier carbonaceous species. However, this latter mechanism is likely to predominate for the production of C{sub 6}-C{sub 8} compounds.

  10. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Twelve new chemistry expermiments are described. Broad areas covered include atomic structure, solubility, gaseous diffusion, endothermic reactions, alcohols, equilibrium, atomic volumes, and some improvised apparatus. (PS)

  11. A novel method for the calibration of Kováts retention indices using n-alkanes with a thermionic nitrogen-phosphorus specific detector.

    PubMed

    Asselin, W M

    1986-10-01

    This paper describes a novel method for the detection of compounds that do not contain nitrogen or phosphorus by a thermionic nitrogen-phosphorus specific detector (NPD), which normally detects only nitrogen- or phosphorus-containing compounds. This method allows for the calibration of gas chromatographic columns with NPD detectors using n-alkanes instead of nitrogen-containing drug mixtures. This results in a more rapid and accurate calibration for the calculation of relative retention indices (RRI), such as Kováts indices, than was previously possible when employing an NPD detector. The proposed method describes the temporary conversion of the NPD detector into a detector with properties much like a flame ionization detector. After a deliberate increase in the hydrogen gas flow rate to the thermionic bead from 4 ml/min to 8 ml/min, the n-alkanes (containing no nitrogen) can be detected and used as RRI calibrators. Once the column has been calibrated, the hydrogen gas flow rate is lowered to the normal rate of 4 ml/min. The detector then behaves as a normal NPD, no longer detecting the n-alkanes.

  12. To Form a Favorable Idea of Chemistry

    ERIC Educational Resources Information Center

    Heikkinen, Henry W.

    2010-01-01

    "To confess the truth, Mrs. B., I am not disposed to form a very favorable idea of chemistry, nor do I expect to derive much entertainment from it." That 200-year-old statement by Caroline to Mrs. Bryan, her teacher, appeared on the first page of Jane Marcet's pioneering secondary school textbook, "Conversations on Chemistry". It was published 17…

  13. Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

    PubMed

    Tokiwa, Yuhei; Sakamoto, Hiroyasu; Takiue, Takanori; Aratono, Makoto; Matsubara, Hiroki

    2015-05-21

    Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion. PMID:25932500

  14. Multiple sources of alkanes in Quaternary oceanic sediment of Antarctica

    USGS Publications Warehouse

    Kvenvolden, K.A.; Rapp, J.B.; Golan-Bac, M.; Hostettler, F.D.

    1987-01-01

    Normal alkanes (n-C13n-C36), isoprenoid hydrocarbons (i-C15, i-C16, i-C18, i-C19, and i-C20) triterpanes (C27C32), and (C27C29) are present in low concentrations offshore Antarctica in near-surface, Quaternary sediment of the Wilkes Land continental margin and of the western Ross Sea. The distributions of these hydrocarbons are interpreted relative to possible sources and processes. The hydrocarbons appear to be mixtures of primary and recycled material from marine and terrigenous sources. The n-alkanes are most abundant and are characterized by two distinct populations, one of probable marine origin and the other likely from terrigenous, vascular plant sources. Because the continent of Antarctica today is devoid of higher plants, the plant-derived hydrocarbons in these offshore sediments probably came from wind-blown material and recycled Antarctic sediment that contains land-plant remains from an earlier period of time. Isoprenoid hydrocarbons are partially recycled and mainly of marine origin; the dominance of pristane over phytane suggests oxic paleoenvironmental conditions. Both modern and ancient triterpanes and steranes are present, and the distribution of these indicates a mixture of primary and recycled bacterial, algal, and possible higher-plant materials. Although the sampled sediments were deposited during the Quaternary, they apparently contain a significant component of hydrocarbons of pre-Quaternary age. ?? 1987.

  15. Geologic seepage of methane and light alkanes in Los Angeles

    NASA Astrophysics Data System (ADS)

    Doezema, L. A.; Chang, K.; Baril, R.; Nwachuku, I.; Contreras, P.; Marquez, A.; Howard, D.

    2013-12-01

    Natural geologic seepage of methane from underground oil and natural gas reservoirs has been suggested to be an underreported part of the global methane budget. Other light alkanes are also given off in combination with the methane seepage, making it possible that geologic seepage is also a potentially significant global source of these light alkanes. This study reports C1-C5 findings from geologic seepage made in the Los Angeles region. Microseepage, invisible escape of gases, was measured primarily at Kenneth Hahn Regional Park, while macroseepage, the visible release of gases, was measured at the La Brea Tar Pits. Samples were collected using stainless steel canisters and flux chambers and were analyzed using gas chromatography with flame ionization detectors (GC-FID). Average microseepage flux rates of 0.95 μg m-2 h-1 for ethane and 0.51 μg m-2 h-1 were found for propane, while average macroseepage rates for methane, ethane, and propane were 664, 19.8, and 18.1 mg m-2 h-1 respectively. Relationships between microseepage flux rate and location of underground oil and natural deposit and earthquake fault lines are presented. Additionally, the relative importance of findings in context with global budgets and local air quality is discussed.

  16. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting...

  17. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting...

  18. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting...

  19. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting...

  20. 40 CFR 721.2625 - Reaction product of alkane-diol and epichlorohydrin.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Reaction product of alkane-diol and... Specific Chemical Substances § 721.2625 Reaction product of alkane-diol and epichlorohydrin. (a) Chemical... as reaction product of alkanediol and epichlorohydrin (PMN P-89-760) is subject to reporting...

  1. Surfactant-induced phases in water-supported alkane monolayers: I. Thermodynamics.

    PubMed

    Yefet, Shai; Sloutskin, Eli; Tamam, Lilach; Sapir, Zvi; Cohen, Asaf; Deutsch, Moshe; Ocko, Benjamin M

    2014-07-15

    Alkanes longer than n = 6 carbons do not spread on the water surface, but condense in a macroscopic lens. However, adding trimethylammonium-based surfactants, C(m)TAB, in submillimolar concentrations causes the alkanes to spread and form a single Langmuir-Gibbs (LG) monolayer of mixed alkanes and surfactant tails, which coexists with the alkane lenses. Upon cooling, this LG film surface-freezes at a temperature T(s) above the bulk freezing temperature T(b). The thermodynamics of surface freezing (SF) of these LG films is studied by surface tension measurements for a range of alkanes (n = 12-21) and surfactant alkyl lengths (m = 14, 16, 18), at several concentrations c. The surface freezing range T(s)-T(b) observed is up to 25 °C, an order of magnitude larger than the temperature range of SF monolayers on the surface of pure alkane melts. The measured (n,T) surface phase diagram is accounted for well by a model based on mixtures' theory, which includes an interchange energy term ω. ω is found to be negative, implying attraction between unlike species, rather than the repulsion found for SF of binary alkane mixtures. Thus, the surfactant/alkane mixing is a necessary condition for the occurrence of SF in these LG films. The X-ray derived structure of the films is presented in an accompanying paper. PMID:24918482

  2. Identity and mechanisms of alkane-oxidizing metalloenzymes from deep-sea hydrothermal vents.

    PubMed

    Bertrand, Erin M; Keddis, Ramaydalis; Groves, John T; Vetriani, Costantino; Austin, Rachel Narehood

    2013-01-01

    Six aerobic alkanotrophs (organism that can metabolize alkanes as their sole carbon source) isolated from deep-sea hydrothermal vents were characterized using the radical clock substrate norcarane to determine the metalloenzyme and reaction mechanism used to oxidize alkanes. The organisms studied were Alcanivorax sp. strains EPR7 and MAR14, Marinobacter sp. strain EPR21, Nocardioides sp. strains EPR26w, EPR28w, and Parvibaculum hydrocarbonoclasticum strain EPR92. Each organism was able to grow on n-alkanes as the sole carbon source and therefore must express genes encoding an alkane-oxidizing enzyme. Results from the oxidation of the radical-clock diagnostic substrate norcarane demonstrated that five of the six organisms (EPR7, MAR14, EPR21, EPR26w, and EPR28w) used an alkane hydroxylase functionally similar to AlkB to catalyze the oxidation of medium-chain alkanes, while the sixth organism (EPR92) used an alkane-oxidizing cytochrome P450 (CYP)-like protein to catalyze the oxidation. DNA sequencing indicated that EPR7 and EPR21 possess genes encoding AlkB proteins, while sequencing results from EPR92 confirmed the presence of a gene encoding CYP-like alkane hydroxylase, consistent with the results from the norcarane experiments.

  3. Geomicrobiological linkages between short-chain alkane consumption and sulfate reduction rates in seep sediments

    PubMed Central

    Bose, Arpita; Rogers, Daniel R.; Adams, Melissa M.; Joye, Samantha B.; Girguis, Peter R.

    2013-01-01

    Marine hydrocarbon seeps are ecosystems that are rich in methane, and, in some cases, short-chain (C2–C5) and longer alkanes. C2–C4 alkanes such as ethane, propane, and butane can be significant components of seeping fluids. Some sulfate-reducing microbes oxidize short-chain alkanes anaerobically, and may play an important role in both the competition for sulfate and the local carbon budget. To better understand the anaerobic oxidation of short-chain n-alkanes coupled with sulfate-reduction, hydrocarbon-rich sediments from the Gulf of Mexico (GoM) were amended with artificial, sulfate-replete seawater and one of four n-alkanes (C1–C4) then incubated under strict anaerobic conditions. Measured rates of alkane oxidation and sulfate reduction closely follow stoichiometric predictions that assume the complete oxidation of alkanes to CO2 (though other sinks for alkane carbon likely exist). Changes in the δ13C of all the alkanes in the reactors show enrichment over the course of the incubation, with the C3 and C4 incubations showing the greatest enrichment (4.4 and 4.5‰, respectively). The concurrent depletion in the δ13C of dissolved inorganic carbon (DIC) implies a transfer of carbon from the alkane to the DIC pool (−3.5 and −6.7‰ for C3 and C4 incubations, respectively). Microbial community analyses reveal that certain members of the class Deltaproteobacteria are selectively enriched as the incubations degrade C1–C4 alkanes. Phylogenetic analyses indicate that distinct phylotypes are enriched in the ethane reactors, while phylotypes in the propane and butane reactors align with previously identified C3–C4 alkane-oxidizing sulfate-reducers. These data further constrain the potential influence of alkane oxidation on sulfate reduction rates (SRRs) in cold hydrocarbon-rich sediments, provide insight into their contribution to local carbon cycling, and illustrate the extent to which short-chain alkanes can serve as electron donors and govern microbial

  4. Incorporation of chlorinated alkanes into fatty acids of hydrocarbon-utilizing mycobacteria.

    PubMed

    Murphy, G L; Perry, J J

    1983-12-01

    The cellular fatty acid composition of Mycobacterium vaccae JOB5 and Mycobacterium convolutum R22 was examined after growth on n-alkanes and compared with the fatty acids of the organisms after growth on 1-chlorohexadecane and 1-chlorooctadecane. Growth on n-alkanes resulted in normal fatty acid profiles. Mass spectral analyses indicated that, after growth on the terminally chlorinated n-alkanes, 75 to 86% of the fatty acids in M. convolutum and ca. 55% of the fatty acids in M. vaccae contained chlorine. Neither organism could utilize chloroacetate or 3-chloropropionate as sole source of carbon and energy. When these compounds were added to a growth medium with n-hexadecane as substrate, there was no evidence that chlorinated fatty acids were produced. Terminally chlorinated n-alkanes can be added to the list of n-alkanes, alkenes, and cyclohexylalkane derivatives that can be directly incorporated into cellular fatty acids of hydrocarbon-utilizing organisms.

  5. Possible origin of n -alkanes with a remarkable even-to-odd predominance in recent marine sediments

    NASA Astrophysics Data System (ADS)

    Nishimura, Mitsugu; Baker, Earl W.

    1986-02-01

    N- alkane distributions with a remarkable even-to-odd predominance (C 16-C 24) were found in marine surface sediments. The previously proposed diagenetic reduction of the corresponding n- fatty acids could not be considered as a source for these N- alkane. Based on a comparison of compositional features of n- alkane, n- fatty acid and n- alcohol distributions, carbon isotope analyses, and other geochemical parameters, the data indicate that the even-predominant n- alkanes were derived directly from marine bacteria.

  6. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1981

    1981-01-01

    Outlines laboratory procedures, demonstrations, teaching suggestions, and content information related to chemistry. Topics include polarizing power; calorimetry and momentum; microcomputers in school chemistry; a constant-volume dispenser for liquids, floating magnets, and crystal lattices; preparation of chromium; and solvent polarity and…

  7. Adsorption of proteins at the aqueous solution/alkane interface: Co-adsorption of protein and alkane.

    PubMed

    Miller, R; Aksenenko, E V; Zinkovych, I I; Fainerman, V B

    2015-08-01

    The equations of state, adsorption isotherms and functions of the distribution of protein molecules in liquid interfacial layers with respect to molar area and the equations for their viscoelastic behavior are presented. This theory was used to determine the adsorption characteristics of β-casein and β-lactoglobulin at water/oil interfaces. The experimental results are shown to be describable quite adequately by the proposed theory with consistent model parameters. The data analysis demonstrated that the β-casein molecule adsorbed at equilibrium conditions is more unfolded as compared with dynamic conditions, and this fact causes the significant increase of the adsorption equilibrium constant. The theory assumes the adsorption of protein molecules from the aqueous solution and a competitive adsorption of alkane molecules from the alkane phase. The comparison of the experimental equilibrium interfacial tension isotherms for β-lactoglobulin at the solution/hexane interface with data calculated using the proposed theoretical model demonstrates that the assumption of a competitive adsorption is essential, and the influence of the hexane molecules on the shape of the adsorption isotherm does in fact exist.

  8. 40 CFR 721.10625 - Distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... benzene by-product, brominated and bromo diphenyl alkane (generic). 721.10625 Section 721.10625 Protection... Distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane (generic). (a... generically as distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane...

  9. 40 CFR 721.10625 - Distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... benzene by-product, brominated and bromo diphenyl alkane (generic). 721.10625 Section 721.10625 Protection... Distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane (generic). (a... generically as distillation bottoms, alkylated benzene by-product, brominated and bromo diphenyl alkane...

  10. 40 CFR 721.10178 - Distillates (Fischer-Tropsch), hydroisomerized middle, C10-13-branched alkane fraction.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...), hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721.10178 Protection of Environment...), hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance and significant new uses subject... middle, C10-13-branched alkane fraction (PMN P-04-319; CAS No. 642928-30-1) is subject to reporting...

  11. 40 CFR 721.10178 - Distillates (Fischer-Tropsch), hydroisomerized middle, C10-13-branched alkane fraction.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...), hydroisomerized middle, C10-13-branched alkane fraction. 721.10178 Section 721.10178 Protection of Environment...), hydroisomerized middle, C10-13-branched alkane fraction. (a) Chemical substance and significant new uses subject... middle, C10-13-branched alkane fraction (PMN P-04-319; CAS No. 642928-30-1) is subject to reporting...

  12. Copper-Catalyzed Intermolecular Amidation and Imidation of Unactivated Alkanes

    PubMed Central

    2015-01-01

    We report a set of rare copper-catalyzed reactions of alkanes with simple amides, sulfonamides, and imides (i.e., benzamides, tosylamides, carbamates, and phthalimide) to form the corresponding N-alkyl products. The reactions lead to functionalization at secondary C–H bonds over tertiary C–H bonds and even occur at primary C–H bonds. [(phen)Cu(phth)] (1-phth) and [(phen)Cu(phth)2] (1-phth2), which are potential intermediates in the reaction, have been isolated and fully characterized. The stoichiometric reactions of 1-phth and 1-phth2 with alkanes, alkyl radicals, and radical probes were investigated to elucidate the mechanism of the amidation. The catalytic and stoichiometric reactions require both copper and tBuOOtBu for the generation of N-alkyl product. Neither 1-phth nor 1-phth2 reacted with excess cyclohexane at 100 °C without tBuOOtBu. However, the reactions of 1-phth and 1-phth2 with tBuOOtBu afforded N-cyclohexylphthalimide (Cy-phth), N-methylphthalimide, and tert-butoxycyclohexane (Cy-OtBu) in approximate ratios of 70:20:30, respectively. Reactions with radical traps support the intermediacy of a tert-butoxy radical, which forms an alkyl radical intermediate. The intermediacy of an alkyl radical was evidenced by the catalytic reaction of cyclohexane with benzamide in the presence of CBr4, which formed exclusively bromocyclohexane. Furthermore, stoichiometric reactions of [(phen)Cu(phth)2] with tBuOOtBu and (Ph(Me)2CO)2 at 100 °C without cyclohexane afforded N-methylphthalimide (Me-phth) from β-Me scission of the alkoxy radicals to form a methyl radical. Separate reactions of cyclohexane and d12-cyclohexane with benzamide showed that the turnover-limiting step in the catalytic reaction is the C–H cleavage of cyclohexane by a tert-butoxy radical. These mechanistic data imply that the tert-butoxy radical reacts with the C–H bonds of alkanes, and the subsequent alkyl radical combines with 1-phth2 to form the corresponding N-alkyl imide product

  13. Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

    SciTech Connect

    Wang, Zhandong; Zhang, Lidong; Moshammer, Kai; Popolan-Vaida, Denisia M.; Shankar, Vijai Shankar Bhavani; Lucassen, Arnas; Hemken, Christian; Taatjes, Craig A.; Leone, Stephen R.; Kohse-Hoinghaus, Katharina; Hansen, Nils; Dagaut, Philippe; Sarathy, S. Mani

    2015-12-31

    Chain-branching reactions represent a general motif in chemistry, encountered in atmospheric chemistry, combustion, polymerization, and photochemistry; the nature and amount of radicals generated by chain-branching are decisive for the reaction progress, its energy signature, and the time towards its completion. In this study, experimental evidence for two new types of chain-branching reactions is presented, based upon detection of highly oxidized multifunctional molecules (HOM) formed during the gas-phase low-temperature oxidation of a branched alkane under conditions relevant to combustion. The oxidation of 2,5-dimethylhexane (DMH) in a jet-stirred reactor (JSR) was studied using synchrotron vacuum ultra-violet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS). Specifically, species with four and five oxygen atoms were probed, having molecular formulas of C8H14O4 (e.g., diketo-hydroperoxide/keto-hydroperoxy cyclic ether) and C8H16O5 (e.g., keto-dihydroperoxide/dihydroperoxy cyclic ether), respectively. The formation of C8H16O5 species involves alternative isomerization of OOQOOH radicals via intramolecular H-atom migration, followed by third O2 addition, intramolecular isomerization, and OH release; C8H14O4 species are proposed to result from subsequent reactions of C8H16O5 species. The mechanistic pathways involving these species are related to those proposed as a source of low-volatility highly oxygenated species in Earth's troposphere. At the higher temperatures relevant to auto-ignition, they can result in a net increase of hydroxyl radical production, so these are additional radical chain-branching pathways for ignition. Furthermore, the results presented herein extend the conceptual basis of reaction mechanisms used to predict the reaction behavior of ignition, and have

  14. Conversational sensemaking

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Webberley, Will; Braines, Dave

    2015-05-01

    Recent advances in natural language question-answering systems and context-aware mobile apps create opportunities for improved sensemaking in a tactical setting. Users equipped with mobile devices act as both sensors (able to acquire information) and effectors (able to act in situ), operating alone or in collectives. The currently- dominant technical approaches follow either a pull model (e.g. Apple's Siri or IBM's Watson which respond to users' natural language queries) or a push model (e.g. Google's Now which sends notifications to a user based on their context). There is growing recognition that users need more flexible styles of conversational interaction, where they are able to freely ask or tell, be asked or told, seek explanations and clarifications. Ideally such conversations should involve a mix of human and machine agents, able to collaborate in collective sensemaking activities with as few barriers as possible. Desirable capabilities include adding new knowledge, collaboratively building models, invoking specific services, and drawing inferences. As a step towards this goal, we collect evidence from a number of recent pilot studies including natural experiments (e.g. situation awareness in the context of organised protests) and synthetic experiments (e.g. human and machine agents collaborating in information seeking and spot reporting). We identify some principles and areas of future research for "conversational sensemaking".

  15. Conversational sensing

    NASA Astrophysics Data System (ADS)

    Preece, Alun; Gwilliams, Chris; Parizas, Christos; Pizzocaro, Diego; Bakdash, Jonathan Z.; Braines, Dave

    2014-05-01

    Recent developments in sensing technologies, mobile devices and context-aware user interfaces have made it pos- sible to represent information fusion and situational awareness for Intelligence, Surveillance and Reconnaissance (ISR) activities as a conversational process among actors at or near the tactical edges of a network. Motivated by use cases in the domain of Company Intelligence Support Team (CoIST) tasks, this paper presents an approach to information collection, fusion and sense-making based on the use of natural language (NL) and controlled nat- ural language (CNL) to support richer forms of human-machine interaction. The approach uses a conversational protocol to facilitate a ow of collaborative messages from NL to CNL and back again in support of interactions such as: turning eyewitness reports from human observers into actionable information (from both soldier and civilian sources); fusing information from humans and physical sensors (with associated quality metadata); and assisting human analysts to make the best use of available sensing assets in an area of interest (governed by man- agement and security policies). CNL is used as a common formal knowledge representation for both machine and human agents to support reasoning, semantic information fusion and generation of rationale for inferences, in ways that remain transparent to human users. Examples are provided of various alternative styles for user feedback, including NL, CNL and graphical feedback. A pilot experiment with human subjects shows that a prototype conversational agent is able to gather usable CNL information from untrained human subjects.

  16. Circumstellar chemistry

    NASA Technical Reports Server (NTRS)

    Glassgold, Alfred E.; Huggins, Patrick J.

    1987-01-01

    The study of the outer envelopes of cool evolved stars has become an active area of research. The physical properties of CS envelopes are presented. Observations of many wavelengths bands are relevant. A summary of observations and a discussion of theoretical considerations concerning the chemistry are summarized. Recent theoretical considerations show that the thermal equilibrium model is of limited use for understanding the chemistry of the outer CS envelopes. The theoretical modeling of the chemistry of CS envelopes provides a quantitive test of chemical concepts which have a broader interest than the envelopes themselves.

  17. Measurements of homogeneous nucleation in normal-alkanes

    NASA Astrophysics Data System (ADS)

    Kraack, H.; Sirota, E. B.; Deutsch, M.

    2000-04-01

    The homogeneous nucleation of normal-alkanes with carbon numbers 15⩽n⩽60 is studied by scanning calorimetry, using the droplet technique. Pure, nonemulsified samples show near-zero undercoolings below the melting point, Tm, except for both ends of the n-range, where undercoolings ΔT of up to 2 °C are observed. The emulsions have much larger undercoolings. The relative undercoolings show three regimes: A fast decreasing one, up to n=17, an anomalously low constant one, ΔT/Tm≈0.04, for 17⩽n⩽30, and a gradually increasing one for 32⩽n⩽60. A value of ΔT/Tm≈0.086 is reached at n=60. The connections of these results with the bulk rotator phases and the recently discovered surface freezing effect are discussed. Strong intrinsic interrelations among these are indicated.

  18. Morphological Transformations in Solid Domains of Alkanes on Surfactant Solutions.

    PubMed

    Matsubara, Hiroki; Takaichi, Tetsumasa; Takiue, Takanori; Aratono, Makoto; Toyoda, Aya; Iimura, Kenichi; Ash, Philip A; Bain, Colin D

    2013-03-21

    Alkanes on surfactant solutions can form three distinct phases at the air-solution interface, a liquid phase (L), a solid monolayer phase (S1), and a hybrid bilayer phase (S2). Phase coexistence between any two, or all three, of these phases has been observed by Brewster angle microscopy of tetradecane, hexadecane, and their mixtures on solutions of tetradecyltrimethylammonium bromide. The morphologies of the domains depend on the competition between line tension and electrostatic interactions, which are essentially different depending on the pair of phases in contact. Domains of S1 in the L phase are long and thin; however, long, thin domains of L in an S1 phase are not stable but break up into a string of small circular domains. The bilayer S2 domains are always circular, owing to the dominance of line tension on the morphology. PMID:26291344

  19. Thermal analysis of n-alkane phase change material mixtures

    SciTech Connect

    Chio, Y.I.; Choi, E.; Lorsch, H.G.

    1991-03-31

    Tests were performed to characterize the thermal behavior of it number of n-alkanes to be used as phase change materials (PCMs) in district cooling applications. Hexadecane and tetradecane were mixed in different fractions, and their thermal behavior was experimentally evaluated. Test results for melting temperature and fusion energy for laboratory grade hexadecane and tetradecane showed good agreement with datain the literature. However, values for commercial grade hexadecane were found to be considerably lower. In the range of temperatures of interest for district cooling, mixtures of tetradecane and hexadecane can be treated as homogeneous substances. However, their heats of fusion are slightly lower than those of the pure substances. Their melting temperatures are also lower by an amount that can be predicted.

  20. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1973

    1973-01-01

    Several ideas are proposed for chemistry teachers to try in their classrooms. Subjects included are polymerization of acrylate, polymerization of styrene, conductivity, pollution, preparation of chlorine, redox equations, chemiluminescence, and molecular sieves. (PS)

  1. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1981

    1981-01-01

    Describes 13 activities, experiments and demonstrations, including the preparation of iron (III) chloride, simple alpha-helix model, investigating camping gas, redox reactions of some organic compounds, a liquid crystal thermometer, and the oxidation number concept in organic chemistry. (JN)

  2. Nuclear Chemistry.

    ERIC Educational Resources Information Center

    Chemical and Engineering News, 1979

    1979-01-01

    Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)

  3. Precolumbian Chemistry.

    ERIC Educational Resources Information Center

    Robinson, Janet Bond

    1995-01-01

    Describes the content and development of a curriculum that provides an approach to descriptive chemistry and the history of technology through consideration of the pottery, metallurgy, pigments, dyes, agriculture, and medicine of pre-Columbian people. (DDR)

  4. Catalytic Chemistry.

    ERIC Educational Resources Information Center

    Borer, Londa; And Others

    1996-01-01

    Describes an approach for making chemistry relevant to everyday life. Involves the study of kinetics using the decomposition of hydrogen peroxide by vegetable juices. Allows students to design and carry out experiments and then draw conclusions from their results. (JRH)

  5. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1980

    1980-01-01

    Describes equipment, activities, and experiments useful in chemistry instruction, including among others, a rapid method to determine available chlorine in bleach, simple flame testing apparatus, and a simple apparatus demonstrating the technique of flash photolysis. (SK)

  6. Measuring long chain alkanes in diesel engine exhaust by thermal desorption PTR-MS

    NASA Astrophysics Data System (ADS)

    Erickson, M. H.; Gueneron, M.; Jobson, B. T.

    2013-07-01

    A method using thermal desorption sampling and analysis by PTR-MS to measure long chain alkanes (C12-C18) and other larger organics associated with diesel engine exhaust emissions is described. Long chain alkanes undergo dissociative proton transfer reactions forming a series of fragment ions with formula CnH2n+1. The PTR-MS is insensitive to n-alkanes less than C8 but displays an increasing sensitivity for larger alkanes. Fragment ion distribution and sensitivity is a function of drift conditions. At 80 Td the most abundant ion fragments from C10 to C16 n-alkanes were m/z 57, 71 and 85. The mass spectrum of gasoline and diesel fuel at 80 Td displayed ion group patterns that can be related to known fuel constituents, such as alkanes, alkylbenzenes and cycloalkanes, and other compound groups that are inferred from molecular weight distributions such as dihydronapthalenes and naphthenic monoaromatics. It is shown that thermal desorption sampling of gasoline and diesel engine exhausts at 80 Td allows for discrimination against light alkanes and alkenes which are a major constituent of both exhausts, allowing for quantification of higher molecular weight alkanes from the abundance of CnH2n+1 fragment ions. Using this approach, the molar abundance of C12-C18 alkanes in diesel engine exhaust was found to be 75% that of the total C1-C4 alkylbenzene abundance. While the PTR-MS mass spectra of gasoline and diesel exhaust looked similar, the abundance of higher molecular weight compounds relative to that of C4-alkylbenzenes was much greater in diesel engine exhaust. The abundance patterns of compounds determined by thermal desorption sampling may allow for emission profiles to be developed to better quantify the relative contributions of diesel and gasoline exhaust emissions of larger organic compounds to urban air concentrations.

  7. Stratospheric chemistry

    SciTech Connect

    Brune, W.H. )

    1991-01-01

    Advances in stratospheric chemistry made by investigators in the United States from 1987 to 1990 are reviewed. Subject areas under consideration include photochemistry of the polar stratosphere, photochemistry of the global stratosphere, and assessments of inadvertent modification of the stratosphere by anthropogenic activity. Particular attention is given to early observations and theories, gas phase chemistry, Antarctic observations, Arctic observations, odd-oxygen, odd-hydrogen, odd-nitrogen, halogens, aerosols, modeling of stratospheric ozone, and reactive nitrogen effects.

  8. Energy Conversion and Storage Program

    SciTech Connect

    Cairns, E.J.

    1992-03-01

    The Energy Conversion and Storage Program applies chemistry and materials science principles to solve problems in (1) production of new synthetic fuels, (2) development of high-performance rechargeable batteries and fuel cells, (3) development of advanced thermochemical processes for energy conversion, (4) characterization of complex chemical processes, and (5) application of novel materials for energy conversion and transmission. Projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials, and advanced methods of analysis. Electrochemistry research aims to develop advanced power systems for electric vehicle and stationary energy storage applications. Topics include identification of new electrochemical couples for advanced rechargeable batteries, improvements in battery and fuel-cell materials, and the establishment of engineering principles applicable to electrochemical energy storage and conversion. Chemical Applications research includes topics such as separations, catalysis, fuels, and chemical analyses. Included in this program area are projects to develop improved, energy-efficient methods for processing waste streams from synfuel plants and coal gasifiers. Other research projects seek to identify and characterize the constituents of liquid fuel-system streams and to devise energy-efficient means for their separation. Materials Applications research includes the evaluation of the properties of advanced materials, as well as the development of novel preparation techniques. For example, the use of advanced techniques, such as sputtering and laser ablation, are being used to produce high-temperature superconducting films.

  9. Prototheca zopfii Kruger strain UMK-13 growth on acetate or n-alkanes

    SciTech Connect

    Koenig, D.W.; Ward, H.B.

    1983-01-01

    A new strain of Prototheca zopfii Kruger was grown on acetate or on pure n-alkanes. A maximum acetate-supported exponential growth of 12 divisions day/sup -1/ occurred at pH 5 and 30/sup 0/C. At 25/sup 0/C, growth on n-alkanes was almost as fast, but no growth occurred at 30/sup 0/C. After 3 days at 25/sup 0/C, 34 to 45% of the n-alkanes had been removed, whereas at 21/sup 0/C and slower growth, utilization was twofold greater after 15 days. Rates of growth and utilization increased markedly after a point of sudden emulsification.

  10. Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes

    DOEpatents

    Crabtree, Robert H.; Brown, Stephen H.

    1989-01-01

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  11. Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes

    DOEpatents

    Crabtree, R.H.; Brown, S.H.

    1989-10-17

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  12. Adsorption and dissociation kinetics of alkanes on CaO(100)

    NASA Astrophysics Data System (ADS)

    Chakradhar, A.; Liu, Y.; Schmidt, J.; Kadossov, E.; Burghaus, U.

    2011-08-01

    The adsorption kinetics of ethane, butane, pentane, and hexane on CaO(100) have been studied by multi-mass thermal desorption (TDS) spectroscopy. The sample cleanliness was checked by Auger electron spectroscopy. A molecular and dissociative adsorption pathway was evident for the alkanes, except for ethane, which does not undergo bond activation. Two TDS peaks appeared when recording the parent mass, which are assigned to different adsorption sites/configurations of the molecularly adsorbed alkanes. Bond activation leads to desorption of hydrogen and several alkane fragments assigned to methane and ethylene formation. Only one TDS feature is seen in this case. Formation of carbon residuals was absent.

  13. Characterization of the Medium- and Long-Chain n-Alkanes Degrading Pseudomonas aeruginosa Strain SJTD-1 and Its Alkane Hydroxylase Genes

    PubMed Central

    Liu, Huan; Xu, Jing; Liang, Rubing; Liu, Jianhua

    2014-01-01

    A gram-negative aliphatic hydrocarbon-degrading bacterium SJTD-1 isolated from oil-contaminated soil was identified as Pseudomonas aeruginosa by comparative analyses of the 16S rRNA sequence, phenotype, and physiological features. SJTD-1 could efficiently mineralize medium- and long-chain n-alkanes (C12-C30) as its sole carbon source within seven days, showing the most optimal growth on n-hexadecane, followed by n-octadecane, and n-eicosane. In 36 h, 500 mg/L of tetradecane, hexadecane, and octadecane were transformed completely; and 2 g/L n-hexadecane was degraded to undetectable levels within 72 h. Two putative alkane-degrading genes (gene 3623 and gene 4712) were characterized and our results indicated that their gene products were rate-limiting enzymes involved in the synergetic catabolism of C12–C16 alkanes. On the basis of bioinformatics and transcriptional analysis, two P450 monooxygenases, along with a putative AlmA-like oxygenase, were examined. Genetically defective mutants lacking the characteristic alkane hydroxylase failed to degrade n-octadecane, thereby suggesting a different catalytic mechanism for the microbial transformation of alkanes with chain lengths over C18. PMID:25165808

  14. Characterization of the medium- and long-chain n-alkanes degrading Pseudomonas aeruginosa strain SJTD-1 and its alkane hydroxylase genes.

    PubMed

    Liu, Huan; Xu, Jing; Liang, Rubing; Liu, Jianhua

    2014-01-01

    A gram-negative aliphatic hydrocarbon-degrading bacterium SJTD-1 isolated from oil-contaminated soil was identified as Pseudomonas aeruginosa by comparative analyses of the 16S rRNA sequence, phenotype, and physiological features. SJTD-1 could efficiently mineralize medium- and long-chain n-alkanes (C12-C30) as its sole carbon source within seven days, showing the most optimal growth on n-hexadecane, followed by n-octadecane, and n-eicosane. In 36 h, 500 mg/L of tetradecane, hexadecane, and octadecane were transformed completely; and 2 g/L n-hexadecane was degraded to undetectable levels within 72 h. Two putative alkane-degrading genes (gene 3623 and gene 4712) were characterized and our results indicated that their gene products were rate-limiting enzymes involved in the synergetic catabolism of C12-C16 alkanes. On the basis of bioinformatics and transcriptional analysis, two P450 monooxygenases, along with a putative AlmA-like oxygenase, were examined. Genetically defective mutants lacking the characteristic alkane hydroxylase failed to degrade n-octadecane, thereby suggesting a different catalytic mechanism for the microbial transformation of alkanes with chain lengths over C18. PMID:25165808

  15. Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.

    PubMed

    Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A

    2015-08-13

    The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems. PMID:26170423

  16. Flow reactor studies of non-equilibrium plasma-assisted oxidation of n-alkanes.

    PubMed

    Tsolas, Nicholas; Lee, Jong Guen; Yetter, Richard A

    2015-08-13

    The oxidation of n-alkanes (C1-C7) has been studied with and without the effects of a nanosecond, non-equilibrium plasma discharge at 1 atm pressure from 420 to 1250 K. Experiments have been performed under nearly isothermal conditions in a flow reactor, where reactive mixtures are diluted in Ar to minimize temperature changes from chemical reactions. Sample extraction performed at the exit of the reactor captures product and intermediate species and stores them in a multi-position valve for subsequent identification and quantification using gas chromatography. By fixing the flow rate in the reactor and varying the temperature, reactivity maps for the oxidation of fuels are achieved. Considering all the fuels studied, fuel consumption under the effects of the plasma is shown to have been enhanced significantly, particularly for the low-temperature regime (T<800 K). In fact, multiple transitions in the rates of fuel consumption are observed depending on fuel with the emergence of a negative-temperature-coefficient regime. For all fuels, the temperature for the transition into the high-temperature chemistry is lowered as a consequence of the plasma being able to increase the rate of fuel consumption. Using a phenomenological interpretation of the intermediate species formed, it can be shown that the active particles produced from the plasma enhance alkyl radical formation at all temperatures and enable low-temperature chain branching for fuels C3 and greater. The significance of this result demonstrates that the plasma provides an opportunity for low-temperature chain branching to occur at reduced pressures, which is typically observed at elevated pressures in thermal induced systems.

  17. Second NASA Conference on Laser Energy Conversion

    NASA Technical Reports Server (NTRS)

    Billman, K. W. (Editor)

    1976-01-01

    The possible transmission of high power laser beams over long distances and their conversion to thrust, electricity, or other useful forms of energy is considered. Specific topics discussed include: laser induced chemistry; developments in photovoltaics, including modification of the Schottky barrier devices and generation of high voltage emf'sby laser radiation of piezoelectric ceramics; the thermo electronic laser energy converter and the laser plasmadynamics converters; harmonic conversion of infrared laser radiation in molecular gases; and photon engines.

  18. A Discovery-Based Experiment Involving Rearrangement in the Conversion of Alcohols to Alkyl Halides: Permanent Magnet [to the thirteenth power]C NMR in the First-Semester Organic Chemistry Lab

    ERIC Educational Resources Information Center

    Kjonaas, Richard A.; Tucker, Ryand J. F.

    2008-01-01

    The use of permanent magnet [to the thirteenth power]C NMR in large-section first-semester organic chemistry lab courses is limited by the availability of experiments that not only hinge on first-semester lecture topics, but which also produce at least 0.5 mL of neat liquid sample. This article reports a discovery-based experiment that meets both…

  19. Radiation Chemistry

    NASA Astrophysics Data System (ADS)

    Wojnárovits, L.

    Ionizing radiation causes chemical changes in the molecules of the interacting medium. The initial molecules change to new molecules, resulting in changes of the physical, chemical, and eventually biological properties of the material. For instance, water decomposes to its elements H2 and O2. In polymers, degradation and crosslinking take place. In biopolymers, e.g., DNS strand breaks and other alterations occur. Such changes are to be avoided in some cases (radiation protection), however, in other cases they are used for technological purposes (radiation processing). This chapter introduces radiation chemistry by discussing the sources of ionizing radiation (radionuclide sources, machine sources), absorption of radiation energy, techniques used in radiation chemistry research, and methods of absorbed energy (absorbed dose) measurements. Radiation chemistry of different classes of inorganic (water and aqueous solutions, inorganic solids, ionic liquids (ILs)) and organic substances (hydrocarbons, halogenated compounds, polymers, and biomolecules) is discussed in concise form together with theoretical and experimental backgrounds. An essential part of the chapter is the introduction of radiation processing technologies in the fields of polymer chemistry, food processing, and sterilization. The application of radiation chemistry to nuclear technology and to protection of environment (flue gas treatment, wastewater treatment) is also discussed.

  20. Liquid alkanes with targeted molecular weights from biomass-derived carbohydrates.

    PubMed

    West, Ryan M; Liu, Zhen Y; Peter, Maximilian; Dumesic, James A

    2008-01-01

    Liquid transportation fuels must burn cleanly and have high energy densities, criteria that are currently fulfilled by petroleum, a non-renewable resource, the combustion of which leads to increasing levels of atmospheric CO(2). An attractive approach for the production of transportation fuels from renewable biomass resources is to convert carbohydrates into alkanes with targeted molecular weights, such as C(8)-C(15) for jet-fuel applications. Targeted n-alkanes can be produced directly from fructose by an integrated process involving first the dehydration of this C(6) sugar to form 5-hydroxymethylfurfural, followed by controlled formation of C-C bonds with acetone to form C(9) and C(15) compounds, and completed by hydrogenation and hydrodeoxygenation reactions to form the corresponding n-alkanes. Analogous reactions are demonstrated starting with 5-methylfurfural or 2-furaldehyde, with the latter leading to C(8) and C(13) n-alkanes. PMID:18702136

  1. Draft Genome Sequence of the Versatile Alkane-Degrading Bacterium Aquabacterium sp. Strain NJ1

    PubMed Central

    Shiwa, Yuh; Yoshikawa, Hirofumi; Zylstra, Gerben J.

    2014-01-01

    The draft genome sequence of a soil bacterium, Aquabacterium sp. strain NJ1, capable of utilizing both liquid and solid alkanes, was deciphered. This is the first report of an Aquabacterium genome sequence. PMID:25477416

  2. Alkane oxidation with porphyrins and metal complexes thereof having haloalkyl side chains

    DOEpatents

    Wijesekera, Tilak; Lyons, James E.; Ellis, Jr., Paul E.; Bhinde, Manoj V.

    1998-01-01

    Transition metal complexes of meso-haloalkylporphyrins, wherein the haloalkyl groups contain 2 to 8 carbon atoms have been found to be highly effective catalysts for oxidation of alkanes and for the decomposition of hydroperoxides.

  3. Alkane oxidation with porphyrins and metal complexes thereof having haloalkyl side chains

    DOEpatents

    Wijesekera, T.; Lyons, J.E.; Ellis, P.E. Jr.; Bhinde, M.V.

    1998-06-23

    Transition metal complexes of meso-haloalkylporphyrins are disclosed, wherein the haloalkyl groups contain 2 to 8 carbon atoms have been found to be highly effective catalysts for oxidation of alkanes and for the decomposition of hydroperoxides. 7 figs.

  4. Modeling the Role of Alkanes, Polycyclic Aromatic Hydrocarbons, and Their Oligomers in Secondary Organic Aerosol Formation

    EPA Science Inventory

    A computationally efficient method to treat secondary organic aerosol (SOA) from various length and structure alkanes as well as SOA from polycyclic aromatic hydrocarbons (PAHs) is implemented in the Community Multiscale Air Quality (CMAQ) model to predict aerosol concentrations ...

  5. Conformational problem of alkanes in liquid crystals by NMR spectroscopy: a mini-review.

    PubMed

    Weber, Adrian C J; Chen, Daniel H J

    2014-10-01

    Recent discoveries of the role of alkane flexibility in determining liquid-crystal behaviour are surveyed. With the impetus for understanding the alkane conformational problem established, recent model dependent (1)H NMR work on the topic will be reviewed where progress is made but the need to circumvent models eventually becomes evident. A closer look at the rigid basic units of alkanes will provide the way forward where it is shown that the orientational ordering and anisotropic potentials of these molecules dissolved in liquid crystals scale with each other. Once this relationship is established, a series of works using anisotropic and isotropic (1)H NMR spectroscopy to study alkane conformational statistics will be covered, wherein the influence of the gas, isotropic condensed and anisotropic condensed phases will be described. PMID:25142124

  6. Regulation of the Alkane Hydroxylase CYP153 Gene in a Gram-Positive Alkane-Degrading Bacterium, Dietzia sp. Strain DQ12-45-1b

    PubMed Central

    Liang, Jie-Liang; JiangYang, Jing-Hong

    2015-01-01

    CYP153, one of the most common medium-chain n-alkane hydroxylases belonging to the cytochrome P450 superfamily, is widely expressed in n-alkane-degrading bacteria. CYP153 is also thought to cooperate with AlkB in degrading various n-alkanes. However, the mechanisms regulating the expression of the protein remain largely unknown. In this paper, we studied CYP153 gene transcription regulation by the potential AraC family regulator (CypR) located upstream of the CYP153 gene cluster in a broad-spectrum n-alkane-degrading Gram-positive bacterium, Dietzia sp. strain DQ12-45-1b. We first identified the transcriptional start site and the promoter of the CYP153 gene cluster. Sequence alignment of upstream regions of CYP153 gene clusters revealed high conservation in the −10 and −35 regions in Actinobacteria. Further analysis of the β-galactosidase activity in the CYP153 gene promoter-lacZ fusion cell indicated that the CYP153 gene promoter was induced by n-alkanes comprised of 8 to 14 carbon atoms, but not by derived decanol and decanic acid. Moreover, we constructed a cypR mutant strain and found that the CYP153 gene promoter activities and CYP153 gene transcriptional levels in the mutant strain were depressed compared with those in the wild-type strain in the presence of n-alkanes, suggesting that CypR served as an activator for the CYP153 gene promoter. By comparing CYP153 gene arrangements in Actinobacteria and Proteobacteria, we found that the AraC family regulator is ubiquitously located upstream of the CYP153 gene, suggesting its universal regulatory role in CYP153 gene transcription. We further hypothesize that the observed mode of CYP153 gene regulation is shared by many Actinobacteria. PMID:26567302

  7. Biodegradation of variable-chain-length n-alkanes in Rhodococcus opacus R7 and the involvement of an alkane hydroxylase system in the metabolism

    PubMed Central

    2014-01-01

    Rhodococcus opacus R7 is a Gram-positive bacterium isolated from a polycyclic aromatic hydrocarbon contaminated soil for its versatile metabolism; indeed the strain is able to grow on naphthalene, o-xylene, and several long- and medium-chain n-alkanes. In this work we determined the degradation of n-alkanes in Rhodococcus opacus R7 in presence of n-dodecane (C12), n-hexadecane (C16), n-eicosane (C20), n-tetracosane (C24) and the metabolic pathway in presence of C12. The consumption rate of C12 was 88%, of C16 was 69%, of C20 was 51% and of C24 it was 78%. The decrement of the degradation rate seems to be correlated to the length of the aliphatic chain of these hydrocarbons. On the basis of the metabolic intermediates determined by the R7 growth on C12, our data indicated that R. opacus R7 metabolizes medium-chain n-alkanes by the primary alcohol formation. This represents a difference in comparison with other Rhodococcus strains, in which a mixture of the two alcohols was observed. By GC-MSD analysis we also identified the monocarboxylic acid, confirming the terminal oxidation. Moreover, the alkB gene cluster from R. opacus R7 was isolated and its involvement in the n-alkane degradation system was investigated by the cloning of this genomic region into a shuttle-vector E. coli-Rhodococcus to evaluate the alkane hydroxylase activity. Our results showed an increased biodegradation of C12 in the recombinant strain R. erythropolis AP (pTipQT1-alkR7) in comparison with the wild type strain R. erythropolis AP. These data supported the involvement of the alkB gene cluster in the n-alkane degradation in the R7 strain. PMID:25401074

  8. The Number of High-Energy Bands in the Photoelectron Spectrum of Alkanes

    NASA Astrophysics Data System (ADS)

    Merris, Russell; Gutman, Ivan

    2000-12-01

    It was observed that within the Bieri-Dill-Heilbronner-Schmelzer model for the calculation of the ion-ization energies of alkanes CnH2n+2, there are exactly n C2s -electron energy levels lying below the degenerate α-ß manifold. We now show that, indeed, this regularity is obeyed by practically all alkane species. Exceptions do exist, but they must possess a (chemically infeasible) group of more than six mutually connected quaternary carbon atoms.

  9. Measuring long chain alkanes in diesel engine exhaust by thermal desorption PTR-MS

    NASA Astrophysics Data System (ADS)

    Erickson, M. H.; Gueneron, M.; Jobson, B. T.

    2014-01-01

    A method using thermal desorption sampling and analysis by proton transfer reaction mass spectrometry (PTR-MS) to measure long chain alkanes (C12-C18) and other larger organics associated with diesel engine exhaust emissions is described. Long chain alkanes undergo dissociative proton transfer reactions forming a series of fragment ions with formula CnH2n+1. The PTR-MS is insensitive to n-alkanes less than C8 but displays an increasing sensitivity for larger alkanes. Fragment ion distribution and sensitivity is a function of drift conditions. At 80 Td the most abundant ion fragments from C10 to C16 n-alkanes were m/z 57, 71 and 85. The mass spectrum of gasoline and diesel fuel at 80 Td displayed ion group patterns that can be related to known fuel constituents, such as alkanes, alkylbenzenes and cycloalkanes, and other compound groups that are inferred from molecular weight distributions such as dihydronapthalenes and naphthenic monoaromatics. It is shown that thermal desorption sampling of gasoline and diesel engine exhausts at 80 Td allows for discrimination against volatile organic compounds, allowing for quantification of long chain alkanes from the abundance of CnH2n+1 fragment ions. The total abundance of long chain alkanes in diesel engine exhaust was measured to be similar to the total abundance of C1-C4 alkylbenzene compounds. The abundance patterns of compounds determined by thermal desorption sampling may allow for emission profiles to be developed to better quantify the relative contributions of diesel and gasoline exhaust emissions on organic compounds concentrations in urban air.

  10. Polymer Chemistry

    NASA Technical Reports Server (NTRS)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  11. Chemistry Experiments

    NASA Technical Reports Server (NTRS)

    Brasseur, Guy; Remsberg, Ellis; Purcell, Patrick; Bhatt, Praful; Sage, Karen H.; Brown, Donald E.; Scott, Courtney J.; Ko, Malcolm K. W.; Tie, Xue-Xi; Huang, Theresa

    1999-01-01

    The purpose of the chemistry component of the model comparison is to assess to what extent differences in the formulation of chemical processes explain the variance between model results. Observed concentrations of chemical compounds are used to estimate to what degree the various models represent realistic situations. For readability, the materials for the chemistry experiment are reported in three separate sections. This section discussed the data used to evaluate the models in their simulation of the source gases and the Nitrogen compounds (NO(y)) and Chlorine compounds (Cl(y)) species.

  12. Two distinct monooxygenases for alkane oxidation in Nocardioides sp. strain CF8.

    PubMed

    Hamamura, N; Yeager, C M; Arp, D J

    2001-11-01

    Alkane monooxygenases in Nocardioides sp. strain CF8 were examined at the physiological and genetic levels. Strain CF8 can utilize alkanes ranging in chain length from C(2) to C(16). Butane degradation by butane-grown cells was strongly inhibited by allylthiourea, a copper-selective chelator, while hexane-, octane-, and decane-grown cells showed detectable butane degradation activity in the presence of allylthiourea. Growth on butane and hexane was strongly inhibited by 1-hexyne, while 1-hexyne did not affect growth on octane or decane. A specific 30-kDa acetylene-binding polypeptide was observed for butane-, hexane-, octane-, and decane-grown cells but was absent from cells grown with octane or decane in the presence of 1-hexyne. These results suggest the presence of two monooxygenases in strain CF8. Degenerate primers designed for PCR amplification of genes related to the binuclear-iron-containing alkane hydroxylase from Pseudomonas oleovorans were used to clone a related gene from strain CF8. Reverse transcription-PCR and Northern blot analysis showed that this gene encoding a binuclear-iron-containing alkane hydroxylase was expressed in cells grown on alkanes above C(6). These results indicate the presence of two distinct monooxygenases for alkane oxidation in Nocardioides sp. strain CF8. PMID:11679317

  13. Marine hydrocarbonoclastic bacteria as whole-cell biosensors for n-alkanes.

    PubMed

    Sevilla, Emma; Yuste, Luis; Rojo, Fernando

    2015-07-01

    Whole-cell biosensors offer potentially useful, cost-effective systems for the in-situ monitoring of seawater for hydrocarbons derived from accidental spills. The present work compares the performance of a biosensor system for the detection of alkanes in seawater, hosted in either Escherichia coli (commonly employed in whole-cell biosensors but not optimized for alkane assimilation) or different marine bacteria specialized in assimilating alkanes. The sensor system was based on the Pseudomonas putida AlkS regulatory protein and the PalkB promoter fused to a gene encoding the green fluorescent protein. While the E. coli sensor provided the fastest response to pure alkanes (25-fold induction after 2 h under the conditions used), a sensor based on Alcanivorax borkumensis was slower, requiring 3-4 h to reach similar induction values. However, the A. borkumensis sensor showed a fourfold lower detection threshold for octane (0.5 μM), and was also better at sensing the alkanes present in petrol. At petrol concentrations of 0.0125%, the A. borkumensis sensor rendered a sevenfold induction, while E. coli sensor showed no response. We discuss possible explanations to this behaviour in terms of the cellular adaptations to alkane uptake and the basal fluorescence produced by each bacterial strain, which was lowest for A. borkumensis. PMID:25874658

  14. Alkanes in flower surface waxes of Momordica cochinchinensis influence attraction to Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae).

    PubMed

    Mukherjee, A; Sarkar, N; Barik, A

    2013-08-01

    Extraction, thin-layer chromatography, and gas chromatography-mass spectrophotometry analyses revealed 15 alkanes representing 97.14% of the total alkanes in the surface waxes of Momordica cochinchinensis Spreng flowers. Nonacosane was the prevailing alkane followed by hexatriacontane, nonadecane, heptacosane, and hentriacontane, accounting for 39.08%, 24.24%, 13.52%, 6.32%, and 5.12%, respectively. The alkanes from flower surface waxes followed by a synthetic mixture of alkanes mimicking alkanes of flower surface waxes elicited attraction of the female insect, Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) between 2 and 10-μg/mL concentrations in a Y-shaped glass tube olfactometer bioassay under laboratory conditions. Synthetic nonadecane from 178.28-891.37 ng, heptacosane from 118.14-590.72 ng, and nonacosane at 784.73 ng showed attraction of the insect. A synthetic mixture of 534.82 ng nonadecane, 354.43 ng heptacosane, and 2,354.18 ng nonacosane elicited highest attraction of A. foveicollis. PMID:23949856

  15. Alkanes in flower surface waxes of Momordica cochinchinensis influence attraction to Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae).

    PubMed

    Mukherjee, A; Sarkar, N; Barik, A

    2013-08-01

    Extraction, thin-layer chromatography, and gas chromatography-mass spectrophotometry analyses revealed 15 alkanes representing 97.14% of the total alkanes in the surface waxes of Momordica cochinchinensis Spreng flowers. Nonacosane was the prevailing alkane followed by hexatriacontane, nonadecane, heptacosane, and hentriacontane, accounting for 39.08%, 24.24%, 13.52%, 6.32%, and 5.12%, respectively. The alkanes from flower surface waxes followed by a synthetic mixture of alkanes mimicking alkanes of flower surface waxes elicited attraction of the female insect, Aulacophora foveicollis Lucas (Coleoptera: Chrysomelidae) between 2 and 10-μg/mL concentrations in a Y-shaped glass tube olfactometer bioassay under laboratory conditions. Synthetic nonadecane from 178.28-891.37 ng, heptacosane from 118.14-590.72 ng, and nonacosane at 784.73 ng showed attraction of the insect. A synthetic mixture of 534.82 ng nonadecane, 354.43 ng heptacosane, and 2,354.18 ng nonacosane elicited highest attraction of A. foveicollis.

  16. Marine hydrocarbonoclastic bacteria as whole-cell biosensors for n-alkanes

    PubMed Central

    Sevilla, Emma; Yuste, Luis; Rojo, Fernando

    2015-01-01

    Whole-cell biosensors offer potentially useful, cost-effective systems for the in-situ monitoring of seawater for hydrocarbons derived from accidental spills. The present work compares the performance of a biosensor system for the detection of alkanes in seawater, hosted in either Escherichia coli (commonly employed in whole-cell biosensors but not optimized for alkane assimilation) or different marine bacteria specialized in assimilating alkanes. The sensor system was based on the Pseudomonas putida AlkS regulatory protein and the PalkB promoter fused to a gene encoding the green fluorescent protein. While the E. coli sensor provided the fastest response to pure alkanes (25-fold induction after 2 h under the conditions used), a sensor based on Alcanivorax borkumensis was slower, requiring 3–4 h to reach similar induction values. However, the A. borkumensis sensor showed a fourfold lower detection threshold for octane (0.5 μM), and was also better at sensing the alkanes present in petrol. At petrol concentrations of 0.0125%, the A. borkumensis sensor rendered a sevenfold induction, while E. coli sensor showed no response. We discuss possible explanations to this behaviour in terms of the cellular adaptations to alkane uptake and the basal fluorescence produced by each bacterial strain, which was lowest for A. borkumensis. PMID:25874658

  17. Marine hydrocarbonoclastic bacteria as whole-cell biosensors for n-alkanes.

    PubMed

    Sevilla, Emma; Yuste, Luis; Rojo, Fernando

    2015-07-01

    Whole-cell biosensors offer potentially useful, cost-effective systems for the in-situ monitoring of seawater for hydrocarbons derived from accidental spills. The present work compares the performance of a biosensor system for the detection of alkanes in seawater, hosted in either Escherichia coli (commonly employed in whole-cell biosensors but not optimized for alkane assimilation) or different marine bacteria specialized in assimilating alkanes. The sensor system was based on the Pseudomonas putida AlkS regulatory protein and the PalkB promoter fused to a gene encoding the green fluorescent protein. While the E. coli sensor provided the fastest response to pure alkanes (25-fold induction after 2 h under the conditions used), a sensor based on Alcanivorax borkumensis was slower, requiring 3-4 h to reach similar induction values. However, the A. borkumensis sensor showed a fourfold lower detection threshold for octane (0.5 μM), and was also better at sensing the alkanes present in petrol. At petrol concentrations of 0.0125%, the A. borkumensis sensor rendered a sevenfold induction, while E. coli sensor showed no response. We discuss possible explanations to this behaviour in terms of the cellular adaptations to alkane uptake and the basal fluorescence produced by each bacterial strain, which was lowest for A. borkumensis.

  18. Characterization of phospholipid+semifluorinated alkane vesicle system.

    PubMed

    Sabín, Juan; Ruso, Juan M; González-Pérez, Alfredo; Prieto, Gerardo; Sarmiento, Félix

    2006-01-15

    The aim of this study is to characterize vesicles obtained by the incorporation of the semifluorinated alkane, (perfluoro-n-hexyl)ethane (diblock F6H2) to a standard lipid, egg yolk phosphatidylcholine (PC). Large unilamellar vesicles (LUVs), prepared by extrusion, were characterized by fluorescence spectroscopy, zeta potential (zeta-potential) and light scattering. By using the fluorescence spectroscopy technique, the anisotropy of l,6-diphenyl-l,3,5-hexatriene (DPH) probe at different temperatures was determined. It was demonstrated that F6H2 is placed inside of the lipid bilayer and that the hydrocarbon acyl chain in the bilayers has higher viscosity in the presence of fluoroalkane. The zeta-potential of the PC-F6H2 system is negative and increases (in absolute value) from -10 to -19 mV when the temperature rises from 10 to 25 degrees C, this last value keeping practically constant with a further increase of temperature. The adsorption of K+ ions on the liposome surface was measured by zeta-potential. This adsorption originates a sudden increase of the initial zeta-potential followed by a slight decrease with K+ concentration. The application of the DLVO theory of colloidal stability showed a growing dependence of the DLVO potential with K+ concentration and consequently a increasing stability.

  19. Alkane functionalization at ([mu]-Oxo)diiron(III) centers

    SciTech Connect

    Leising, R.A.; Kim, J.; Perez, M.A.; Que, L. Jr. )

    1993-10-20

    The reactivity of ([mu]-oxo)diferric complexes with [sup t]BuOOH (TBHP) for the functionalization of alkanes in CH[sub 3]CN has been investigated as part of our efforts to model dinuclear sites in nonheme iron enzymes. [Fe[sub 2](TPA)[sub 2]O(OAc)](CIO[sub 4])[sub 3] (1) (TPA = tris(2-pyridylmethyl)amine, OAc = acetate) is an efficient catalyst for cyclohexane oxidation, affording cyclohexanol (A, 9 equiv), cyclohexanone (K, 11 equiv), and (tert-butylperoxy)cyclohexane (P, 16 equiv) in 0.25 h at ambient temperature and pressure under an argon atmosphere. The catalyst is remarkably robust, as indicated by the [sup 1]H NMR and UV-vis spectra of the reaction mixture during the catalytic reaction and by its ability to maintain its turnover efficiency with subsequent additions of oxidant. The catalytic mechanism for TBHP utilization was explored by observing the effects of varying the tripodal ligands on the ([mu]-oxo)([mu]-carboxylato)diferric catalysts and varying the bridge on Fe[sub 2]O(TPA)[sub 2] catalysts. The (A + K)/P ratio increased as the ligands became more electron donating. Solvent also played an important role in determining the partitioning of products between A + K and P, with benzonitrile favoring hydroxylated products at the expense of P and pyridine having the opposite effect. 49 refs., 2 figs., 3 tabs.

  20. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1982

    1982-01-01

    Presents procedures, experiments, demonstrations, teaching suggestions, and information on a variety of chemistry topics including, for example, inert gases, light-induced reactions, calculators, identification of substituted acetophenones, the elements, analysis of copper minerals, extraction of metallic strontium, equilibrium, halogens, and…

  1. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    Presents chemistry experiments, laboratory procedures, demonstrations, teaching suggestions, and classroom materials/activities. These include: game for teaching ionic formulas; method for balancing equations; description of useful redox series; computer programs (with listings) for water electrolysis simulation and for determining chemical…

  2. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Short articles on the kinetics of the hydrogen peroxide-iodide ion reaction, simulation of fluidization catalysis, the use of Newman projection diagrams to represent steric relationships in organic chemistry, the use of synthetic substrates for proteolytic enzyme reactions, and two simple clock reactions"--hydrolysis of halogenoalkanes and…

  3. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1972

    1972-01-01

    Short articles on the alkylation of aniline, the preparation and properties of perbromate, using scrap copper in chemistry instruction, a safe method of burning hydrogen, and the use of an ion-charge model as an alternative to the mole concept in secondary school instruction. (AL)

  4. Confectionary Chemistry.

    ERIC Educational Resources Information Center

    Levine, Elise Hilf

    1996-01-01

    Presents activities and demonstrations that enable teachers to use various types of confections as tactile experiences to spark chemistry students' interest and generate enthusiasm for learning. Presents uses of candy in teaching about atomic structure, spontaneous nuclear decay, chemical formulas, fractoluminescence, the effect of a molecular…

  5. Chemistry Notes

    ERIC Educational Resources Information Center

    School Science Review, 1976

    1976-01-01

    Describes several chemistry projects, including solubility, formula for magnesium oxide, dissociation of dinitrogen tetroxide, use of 1-chloro-2, 4-dinitrobenzene, migration of ions, heats of neutralizations, use of pocket calculators, sonic cleaning, oxidation states of manganese, and cell potentials. Includes an extract from Chemical Age on…

  6. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1983

    1983-01-01

    Presents chemistry experiments, laboratory procedures, demonstrations, and classroom materials/activities. These include: experiments on colloids, processing of uranium ore, action of heat on carbonates; color test for phenols and aromatic amines; solvent properties of non-electrolytes; stereoscopic applications/methods; a valency balance;…

  7. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1978

    1978-01-01

    Describes some laboratory apparatus, chemistry experiments and demonstrations, such as a Kofler block melting point apparatus, chromatographic investigation of the phosphoric acid, x-ray diffraction, the fountain experiment, endothermic sherbet, the measurement of viscosity, ionization energies and electronic configurations. (GA)

  8. Chemistry Notes.

    ERIC Educational Resources Information Center

    School Science Review, 1980

    1980-01-01

    Presents 12 chemistry notes for British secondary school teachers. Some of these notes are: (1) a simple device for testing pH-meters; (2) portable fume cupboard safety screen; and (3) Mass spectroscopy-analysis of a mass peak. (HM)

  9. Carboxylic acid reductase is a versatile enzyme for the conversion of fatty acids into fuels and chemical commodities.

    PubMed

    Akhtar, M Kalim; Turner, Nicholas J; Jones, Patrik R

    2013-01-01

    Aliphatic hydrocarbons such as fatty alcohols and petroleum-derived alkanes have numerous applications in the chemical industry. In recent years, the renewable synthesis of aliphatic hydrocarbons has been made possible by engineering microbes to overaccumulate fatty acids. However, to generate end products with the desired physicochemical properties (e.g., fatty aldehydes, alkanes, and alcohols), further conversion of the fatty acid is necessary. A carboxylic acid reductase (CAR) from Mycobacterium marinum was found to convert a wide range of aliphatic fatty acids (C(6)-C(18)) into corresponding aldehydes. Together with the broad-substrate specificity of an aldehyde reductase or an aldehyde decarbonylase, the catalytic conversion of fatty acids to fatty alcohols (C(8)-C(16)) or fatty alkanes (C(7)-C(15)) was reconstituted in vitro. This concept was applied in vivo, in combination with a chain-length-specific thioesterase, to engineer Escherichia coli BL21(DE3) strains that were capable of synthesizing fatty alcohols and alkanes. A fatty alcohol titer exceeding 350 mg·L(-1) was obtained in minimal media supplemented with glucose. Moreover, by combining the CAR-dependent pathway with an exogenous fatty acid-generating lipase, natural oils (coconut oil, palm oil, and algal oil bodies) were enzymatically converted into fatty alcohols across a broad chain-length range (C(8)-C(18)). Together with complementing enzymes, the broad substrate specificity and kinetic characteristics of CAR opens the road for direct and tailored enzyme-catalyzed conversion of lipids into user-ready chemical commodities.

  10. Surveys of research in the Chemistry Division, Argonne National Laboratory

    SciTech Connect

    Grazis, B.M.

    1992-11-01

    Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

  11. Surveys of research in the Chemistry Division, Argonne National Laboratory

    SciTech Connect

    Grazis, B.M.

    1992-01-01

    Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

  12. Impact of chamber wall loss of gaseous organic compounds on secondary organic aerosol formation: explicit modeling of SOA formation from alkane and alkene oxidation

    NASA Astrophysics Data System (ADS)

    La, Y. S.; Camredon, M.; Ziemann, P. J.; Valorso, R.; Matsunaga, A.; Lannuque, V.; Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.

    2016-02-01

    Recent studies have shown that low volatility gas-phase species can be lost onto the smog chamber wall surfaces. Although this loss of organic vapors to walls could be substantial during experiments, its effect on secondary organic aerosol (SOA) formation has not been well characterized and quantified yet. Here the potential impact of chamber walls on the loss of gaseous organic species and SOA formation has been explored using the Generator for Explicit Chemistry and Kinetics of the Organics in the Atmosphere (GECKO-A) modeling tool, which explicitly represents SOA formation and gas-wall partitioning. The model was compared with 41 smog chamber experiments of SOA formation under OH oxidation of alkane and alkene series (linear, cyclic and C12-branched alkanes and terminal, internal and 2-methyl alkenes with 7 to 17 carbon atoms) under high NOx conditions. Simulated trends match observed trends within and between homologous series. The loss of organic vapors to the chamber walls is found to affect SOA yields as well as the composition of the gas and the particle phases. Simulated distributions of the species in various phases suggest that nitrates, hydroxynitrates and carbonylesters could substantially be lost onto walls. The extent of this process depends on the rate of gas-wall mass transfer, the vapor pressure of the species and the duration of the experiments. This work suggests that SOA yields inferred from chamber experiments could be underestimated up a factor of 2 due to the loss of organic vapors to chamber walls.

  13. Impact of chamber wall loss of gaseous organic compounds on secondary organic aerosol formation: explicit modeling of SOA formation from alkane and alkene oxidation

    NASA Astrophysics Data System (ADS)

    La, Y. S.; Camredon, M.; Ziemann, P. J.; Valorso, R.; Matsunaga, A.; Lannuque, V.; Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.

    2015-09-01

    Recent studies have shown that low volatility gas-phase species can be lost onto the smog chamber wall surfaces. Although this loss of organic vapors to walls could be substantial during experiments, its effect on secondary organic aerosol (SOA) formation has not been well characterized and quantified yet. Here the potential impact of chamber walls on the loss of gaseous organic species and SOA formation has been explored using the Generator for Explicit Chemistry and Kinetics of the Organics in the Atmosphere (GECKO-A) modeling tool which explicitly represents SOA formation and gas/wall partitioning. The model was compared with 41 smog chamber experiments of SOA formation under OH oxidation of alkane and alkene series (linear, cyclic and C12-branched alkanes and terminal, internal and 2-methyl alkenes with 7 to 17 carbon atoms) under high NOx conditions. Simulated trends match observed trends within and between homologous series. The loss of organic vapors to the chamber walls is found to affect SOA yields as well as the composition of the gas and the particle phases. Simulated distributions of the species in various phases suggest that nitrates, hydroxynitrates and carbonylesters could substantially be lost onto walls. The extent of this process depends on the rate of gas/wall mass transfer, the vapor pressure of the species and the duration of the experiments. This work suggests that SOA yields inferred from chamber experiments could be underestimated up to 0.35 yield unit due to the loss of organic vapors to chamber walls.

  14. Berberine cation: A fluorescent chemosensor for alkanes and other low-polarity compounds. An explanation of this phenomenon

    PubMed

    Cossio; Arrieta; Cebolla; Membrado; Vela; Garriga; Domingo

    2000-07-27

    Alkanes in the presence of berberine sulfate provide an enhancement of fluorescent signal, which depends on alkane concentration and structure, when the system is irradiated with monochromatic UV light. Computational analysis suggests that an ion-induced dipole between alkanes and berberine sulfate is responsible for this phenomenon. This interaction can properly model the experimentally obtained fluorescent response. The proposed explanation allows other interacting systems to be designed, which have been experimentally confirmed. PMID:10930271

  15. Berberine cation: A fluorescent chemosensor for alkanes and other low-polarity compounds. An explanation of this phenomenon

    PubMed

    Cossio; Arrieta; Cebolla; Membrado; Vela; Garriga; Domingo

    2000-07-27

    Alkanes in the presence of berberine sulfate provide an enhancement of fluorescent signal, which depends on alkane concentration and structure, when the system is irradiated with monochromatic UV light. Computational analysis suggests that an ion-induced dipole between alkanes and berberine sulfate is responsible for this phenomenon. This interaction can properly model the experimentally obtained fluorescent response. The proposed explanation allows other interacting systems to be designed, which have been experimentally confirmed.

  16. Photochemical properties of some Cl-containing halogenated alkanes.

    PubMed

    Orkin, V L; Khamaganov, V G; Kasimovskaya, E E; Guschin, A G

    2013-07-01

    Rate constants for the gas-phase reactions of OH radicals with three partially halogenated alkanes, CH3Cl (kMC), CHFClCFCl2 (k122a), and CH2FCFCl2 (k132c), were measured using a discharge flow-electron paramagnetic resonance technique over the temperature range from 298 to 460 K. The temperature dependences of the rate constants can be represented by the expressions kMC(298-460 K) = (3.09 ± 0.94) × 10(-12) exp[-(1411 ± 85)/T] cm(3) molecule(-1) s(-1), k122a(298-460 K) = (1.26 ± 0.24) × 10(-12) exp[-(1298 ± 66)/T] cm(3) molecule(-1) s(-1), and k132c(298-370 K) = (8.1 ± 2.2) × 10(-13) exp[-(1247 ± 89)/T] cm(3) molecule(-1) s(-1). The atmospheric lifetimes of CH3Cl, CHFClCFCl2, and CH2FCFCl2 due to their reaction with OH were estimated to be 1.6, 3.5, and 4.5 years, respectively. The UV absorption cross sections of halogenated ethanes, CHFClCFCl2, and CH2FCFCl2, were measured at T = 295 K between 190 and 240 nm, as were those for CHCl2CF2Cl (HCFC-122), CHCl2CF3 (HCFC-123), CHFClCF2Cl (HCFC-123a), and CH3CFCl2 (HCFC-141b). The atmospheric lifetimes due to stratospheric photolysis were also estimated. PMID:23725515

  17. Cyclooctane metathesis catalyzed by silica-supported tungsten pentamethyl [(≡SiO)W(Me)5]: distribution of macrocyclic alkanes.

    PubMed

    Riache, Nassima; Callens, Emmanuel; Samantaray, Manoja K; Kharbatia, Najeh M; Atiqullah, Muhammad; Basset, Jean-Marie

    2014-11-10

    Metathesis of cyclic alkanes catalyzed by the new surface complex [(≡SiO)W(Me)5] affords a wide distribution of cyclic and macrocyclic alkanes. The major products with the formula C(n)H(2n) are the result of either a ring contraction or ring expansion of cyclooctane leading to lower unsubstituted cyclic alkanes (5≤n≤7) and to an unprecedented distribution of unsubstituted macrocyclic alkanes (12≤n≤40), respectively, identified by GC/MS and by NMR spectroscopies.

  18. [Distribution Characteristics and Source Apportionment of n-Alkanes in Water from Yellow River in Henan Section].

    PubMed

    Feng, Jing-lan; Xi, Nan-nan; Zhang, Fei; Liu, Shu-hui; Sun, Jian-hui

    2016-03-15

    To investigate the distributions and possible sources of n-alkanes in water and suspended particulate matter from Yellow River in Henan section, 26 water and suspended particulate matter samples were collected in August 2010 and 22 n-alkanes (C₁₄-C₃₆) were quantitatively determined by gas chromatography-mass spectrometer (GC-MS). Potential sources of n-alkanes were analyzed using different characteristic parameters. The results indicated that total concentrations of 22 n-alkanes were 521-5,843 ng · L⁻¹ with a mean concentration of 1,409 ng · L⁻¹, while the total amounts of n-alkanes in the suspended particulate matter were 463-11,142 ng · L⁻¹ with a mean value of 1,951 ng · L⁻¹. The composition profiles of n-alkanes in water showed unimodal distribution with a peak at C₂₅ in water. However, the composition characteristics of n-alkanes in SPM were of bimodal type, but still with the advantage of high carbon hydrocarbons peak at C₂₅. Results of characteristic parameters including CPI, TAR, OEP and % WaxCn showed that n-alkanes in the studied area were derived mainly from combustion of fossil fuel, while terrestrial higher plant played a role in the existence of n-alkanes in water and suspended particulate matter from Yellow River in Henan section. PMID:27337879

  19. Circumstellar chemistry

    NASA Technical Reports Server (NTRS)

    Glassgold, A. E.; Mamon, G. A.

    1991-01-01

    Recent theoretical studies of circumstellar chemistry are discussed for both red-giant and protostellar winds. The generalized photochemical model is able to account for the recently discovered silicon-bearing molecules in the prototypical, C-rich, AGB star IRC + 10216. The surprising occurrence of CO in protostellar winds that are largely atomic is interpreted to be the result of the high density and the rapid decrease of the temperature with distance that is expected for such winds.

  20. Computational chemistry

    NASA Technical Reports Server (NTRS)

    Arnold, J. O.

    1987-01-01

    With the advent of supercomputers, modern computational chemistry algorithms and codes, a powerful tool was created to help fill NASA's continuing need for information on the properties of matter in hostile or unusual environments. Computational resources provided under the National Aerodynamics Simulator (NAS) program were a cornerstone for recent advancements in this field. Properties of gases, materials, and their interactions can be determined from solutions of the governing equations. In the case of gases, for example, radiative transition probabilites per particle, bond-dissociation energies, and rates of simple chemical reactions can be determined computationally as reliably as from experiment. The data are proving to be quite valuable in providing inputs to real-gas flow simulation codes used to compute aerothermodynamic loads on NASA's aeroassist orbital transfer vehicles and a host of problems related to the National Aerospace Plane Program. Although more approximate, similar solutions can be obtained for ensembles of atoms simulating small particles of materials with and without the presence of gases. Computational chemistry has application in studying catalysis, properties of polymers, all of interest to various NASA missions, including those previously mentioned. In addition to discussing these applications of computational chemistry within NASA, the governing equations and the need for supercomputers for their solution is outlined.

  1. Leaf wax n-alkane distributions in and across modern plants: Implications for paleoecology and chemotaxonomy

    NASA Astrophysics Data System (ADS)

    Bush, Rosemary T.; McInerney, Francesca A.

    2013-09-01

    Long chain (C21 to C37) n-alkanes are among the most long-lived and widely utilized terrestrial plant biomarkers. Dozens of studies have examined the range and variation of n-alkane chain-length abundances in modern plants from around the world, and n-alkane distributions have been used for a variety of purposes in paleoclimatology and paleoecology as well as chemotaxonomy. However, most of the paleoecological applications of n-alkane distributions have been based on a narrow set of modern data that cannot address intra- and inter-plant variability. Here, we present the results of a study using trees from near Chicago, IL, USA, as well as a meta-analysis of published data on modern plant n-alkane distributions. First, we test the conformity of n-alkane distributions in mature leaves across the canopy of 38 individual plants from 24 species as well as across a single growing season and find no significant differences for either canopy position or time of leaf collection. Second, we compile 2093 observations from 86 sources, including the new data here, to examine the generalities of n-alkane parameters such as carbon preference index (CPI), average chain length (ACL), and chain-length ratios for different plant groups. We show that angiosperms generally produce more n-alkanes than do gymnosperms, supporting previous observations, and furthermore that CPI values show such variation in modern plants that it is prudent to discard the use of CPI as a quantitative indicator of n-alkane degradation in sediments. We also test the hypotheses that certain n-alkane chain lengths predominate in and therefore can be representative of particular plant groups, namely, C23 and C25 in Sphagnum mosses, C27 and C29 in woody plants, and C31 in graminoids (grasses). We find that chain-length distributions are highly variable within plant groups, such that chemotaxonomic distinctions between grasses and woody plants are difficult to make based on n-alkane abundances. In contrast

  2. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments

    PubMed Central

    Gittel, Antje; Donhauser, Johanna; Røy, Hans; Girguis, Peter R.; Jørgensen, Bo B.; Kjeldsen, Kasper U.

    2015-01-01

    Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e

  3. Ubiquitous Presence and Novel Diversity of Anaerobic Alkane Degraders in Cold Marine Sediments.

    PubMed

    Gittel, Antje; Donhauser, Johanna; Røy, Hans; Girguis, Peter R; Jørgensen, Bo B; Kjeldsen, Kasper U

    2015-01-01

    Alkanes are major constituents of crude oil and are released to the marine environment by natural seepage and from anthropogenic sources. Due to their chemical inertness, their removal from anoxic marine sediments is primarily controlled by the activity of anaerobic alkane-degrading microorganisms. To facilitate comprehensive cultivation-independent surveys of the diversity and distribution of anaerobic alkane degraders, we designed novel PCR primers that cover all known diversity of the 1-methylalkyl succinate synthase gene (masD/assA), which catalyzes the initial activation of alkanes. We studied masD/assA gene diversity in pristine and seepage-impacted Danish coastal sediments, as well as in sediments and alkane-degrading enrichment cultures from the Middle Valley (MV) hydrothermal vent system in the Pacific Northwest. MasD/assA genes were ubiquitously present, and the primers captured the diversity of both known and previously undiscovered masD/assA gene diversity. Seepage sediments were dominated by a single masD/assA gene cluster, which is presumably indicative of a substrate-adapted community, while pristine sediments harbored a diverse range of masD/assA phylotypes including those present in seepage sediments. This rare biosphere of anaerobic alkane degraders will likely increase in abundance in the event of seepage or accidental oil spillage. Nanomolar concentrations of short-chain alkanes (SCA) were detected in pristine and seepage sediments. Interestingly, anaerobic alkane degraders closely related to strain BuS5, the only SCA degrader in pure culture, were found in mesophilic MV enrichments, but not in cold sediments from Danish waters. We propose that the new masD/assA gene lineages in these sediments represent novel phylotypes that are either fueled by naturally occurring low levels of SCA or that metabolize medium- to long-chain alkanes. Our study highlights that masD/assA genes are a relevant diagnostic marker to identify seepage and microseepage, e

  4. Biogeographic variation of foliar n-alkanes of Juniperus communis var. saxatilis Pallas from the Balkans.

    PubMed

    Rajčević, Nemanja; Janaćković, Pedja; Dodoš, Tanja; Tešević, Vele; Marin, Petar D

    2014-12-01

    The composition of the epicuticular n-alkanes isolated from the leaves of ten populations of Juniperus communis L. var. saxatilis Pallas from central (continental) and western (coastal) areas of the Balkan Peninsula was characterized by GC-FID and GC/MS analyses. In the leaf waxes, 14 n-alkane homologues with chain-lengths ranging from C22 to C35 were identified. All samples were dominated by n-tritriacontane (C33 ), but differences in two other dominant n-alkanes allowed separating the coastal from the continental populations. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses as well as the Mantel test) were deployed to analyze the diversity and variability of the epicuticular-leaf-n-alkane patterns of the ten natural populations of J. communis var. saxatilis and their relation to different geographic and bioclimatic parameters. Cluster analysis showed a high correlation of the leaf-n-alkane patterns with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon. Several bioclimatic parameters related to aridity were highly correlated with this differentiation.

  5. Toward aldehyde and alkane production by removing aldehyde reductase activity in Escherichia coli

    PubMed Central

    Rodriguez, Gabriel M.; Atsumi, Shota

    2015-01-01

    Advances in synthetic biology and metabolic engineering have enabled the construction of novel biological routes to valuable chemicals using suitable microbial hosts. Aldehydes serve as chemical feedstocks in the synthesis of rubbers, plastics, and other larger molecules. Microbial production of alkanes is dependent on the formation of a fatty aldehyde intermediate which is converted to an alkane by an aldehyde deformylating oxygenase (ADO). However, microbial hosts such as Escherichia coli are plagued by many highly active endogenous aldehyde reductases (ALRs) that convert aldehydes to alcohols, which greatly complicates strain engineering for aldehyde and alkane production. It has been shown that the endogenous ALR activity outcompetes the ADO enzyme for fatty aldehyde substrate. The large degree of ALR redundancy coupled with an incomplete database of ALRs represents a significant obstacle in engineering E. coli for either aldehyde or alkane production. In this study, we identified 44 ALR candidates encoded in the E. coli genome using bioinformatics tools, and undertook a comprehensive screening by measuring the ability of these enzymes to produce isobutanol. From the pool of 44 candidates, we found five new ALRs using this screening method (YahK, DkgA, GldA, YbbO, and YghA). Combined deletions of all 13 known ALRs resulted in a 90–99% reduction in endogenous ALR activity for a wide range of aldehyde substrates (C2–C12). Elucidation of the ALRs found in E. coli could guide one in reducing competing alcohol formation during alkane or aldehyde production. PMID:25108218

  6. Second virial coefficients, critical temperatures, and the molecular shapes of long n-alkanes

    NASA Astrophysics Data System (ADS)

    Vega, Carlos; López Rodríguez, Antonio

    1996-09-01

    The second virial coefficient for a molecular model of n-alkanes with up to 200 carbon atoms has been computed for temperatures in the range of 1000 Kalkanes. The Boyle temperature of n-alkanes is not much affected by the length of the chain for n-alkanes with more than 100 carbon atoms. According to the Flory theory, for infinitely long chains the Boyle temperature and the critical temperature, denoted as the θ temperature are the same. On this basis using the present model we find θ=1620 K as the critical temperature of polymethylene. Scaling laws for the square of the end-to-end distance and for the radius of gyration at several temperatures are analyzed. For high temperatures, the scaling laws correspond to good solvent conditions whereas at the θ temperature the scaling laws are those of an ideal chain. The shape of long n-alkanes at several temperatures is also analyzed. We find that the polymethylene chains present an anisotropy similar to that of a parallelepiped with a ratio of sizes of 1:1.7:3.6.

  7. Whole-cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills.

    PubMed

    Zhang, Dayi; He, Yi; Wang, Yun; Wang, Hui; Wu, Lin; Aries, Eric; Huang, Wei E

    2012-01-01

    Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oil-water interface of 10-80 µm emulsified mineral and crude oil droplets. These properties make ADP1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. Acinetobacter baylyi bioreporter ADPWH_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. Bioreporter ADPWH_alk was able to detect a broad range of alkanes and alkenes with carbon chain length from C7 to C36. So far, ADPWH_alk is the only bioreporter that is able to detect alkane with carbon chain length greater than C18. This bioreporter responded to the alkanes in about 30 min and it was independent to the cell growth phase because of two point mutations in alkM promoter recognized by alkane regulatory protein ALKR. ADPWH_alk was applied to detect mineral oil, Brent, Chestnut and Sirri crude oils in water and seawater in the range 0.1-100 mg l(-1), showing that the bioreporter oil detection was semi-quantitative. This study demonstrates that ADPWH_alk is a rapid, sensitive and semi-quantitative bioreporter that can be useful for environmental monitoring and assessment of oil spills in seawater and soils.

  8. ClogP(alk): a method for predicting alkane/water partition coefficient.

    PubMed

    Kenny, Peter W; Montanari, Carlos A; Prokopczyk, Igor M

    2013-05-01

    Alkane/water partition coefficients (P(alk)) are less familiar to the molecular design community than their 1-octanol/water equivalents and access to both data and prediction tools is much more limited. A method for predicting alkane/water partition coefficient from molecular structure is introduced. The basis for the ClogP(alk) model is the strong (R² = 0.987) relationship between alkane/water partition coefficient and molecular surface area (MSA) that was observed for saturated hydrocarbons. The model treats a molecule as a perturbation of a saturated hydrocarbon molecule with the same MSA and uses increments defined for functional groups to quantify the extent to which logP(alk) is perturbed by the introduction each functional group. Interactions between functional groups, such as intramolecular hydrogen bonds are also parameterized within a perturbation framework. The functional groups and interactions between them are specified substructurally in a transparent and reproducible manner using SMARTS notation. The ClogP(alk) model was parameterized using data measured for structurally prototypical compounds that dominate the literature on alkane/water partition coefficients and then validated using an external test set of 100 alkane/water logP measurements, the majority of which were for drugs.

  9. n-Alkane distributions as indicators of novel ecosystem development in western boreal forest soils

    NASA Astrophysics Data System (ADS)

    Norris, Charlotte; Dungait, Jennifer; Quideau, Sylvie

    2013-04-01

    Novel ecosystem development is occurring within the western boreal forest of Canada due to land reclamation following surface mining in the Athabasca Oil Sands Region. Sphagnum peat is the primary organic matter amendment used to reconstruct soils in the novel ecosystems. We hypothesised that ecosystem recovery would be indicated by an increasing similarity in the biomolecular characteristics of novel reconstructed soil organic matter (SOM) derived from peat to those of natural boreal ecosystems. In this study, we evaluated the use of the homologous series of very long chain (>C20) n-alkanes with odd-over-even predominance as biomarker signatures to monitor the re-establishment of boreal forests on reconstructed soils. The lipids were extracted from dominant vegetation inputs and SOM from a series of natural and novel ecosystem reference plots. We observed unique very long n-alkane signatures of the source vegetation, e.g. Sphagnum sp. was dominated by C31 and aspen (Populus tremuloides Michx.) leaves by C25. Greater concentrations of very long chain n-alkanes were extracted from natural than novel ecosystem SOM (p<0.01), and their distribution differed between the two systems (p<0.001) and reflected the dominant vegetation input. Our results indicate that further research is required to clarify the influence of vegetation or disturbance on the signature of very long chain n-alkanes in SOM; however, the use of n-alkanes as biomarkers of ecosystem development is a promising method.

  10. Effects of fuel properties on the burning characteristics of collision-merged alkane/water droplets

    SciTech Connect

    Wang, C.H.; Pan, K.L.; Huang, W.C.; Wen, H.C.; Yang, J.Y.; Law, C.K.

    2008-04-15

    The combustion characteristics of freely falling droplets, individually generated by the merging of colliding alkane and water droplets, were experimentally investigated. The outcome of the collision droplets was first studied and then the subsequent burning processes such as the flame appearance, ignition and burning behaviors were recorded, through either visual observation or microphotography with the aid of stroboscopic lighting. If the merged droplets were exhibited in an insertive manner, while the water droplet inserted into the alkane droplet, these yield the burning behaviors prior to the end of flame were very much similar to that of pure alkane. The burning was ended with droplet extinction for lower-C alkane, and with either droplet ''flash vaporization'' or extinction for hexadecane. And if the merged droplets were in adhesive manner, for hexadecane with large water content, they either could not be ignited for the large merged droplets, or be ignited with a much prolonged ignition delay, followed by a soot-reducing flame and an ending of droplet extinction for the small merged droplets. ''Homogeneous'' explosion was not observed in any of the tests, and ''heterogeneous'' explosion, induced by trapped air bubbles, occasionally occurred for merged droplets with C-atom in alkane is higher than dodecane. And the sudden disappearance of droplet definitely decreased the burning time and thus enhanced the burning intensity. Besides, the fuel mass consumption rates were increased, even in the cases that having droplet extinction, because of the enlargement of the surface area due to the stuffing of water droplet. (author)

  11. Anaerobic oxidation of short-chain alkanes in hydrothermal sediments: potential influences on sulfur cycling and microbial diversity

    SciTech Connect

    Adams, MM; Hoarfrost, AL; Bose, A; Joye, SB; Girguis, PR

    2013-05-14

    Short-chain alkanes play a substantial role in carbon and sulfur cycling at hydrocarbon-rich environments globally, yet few studies have examined the metabolism of ethane (C-2), propane (C-3), and butane (C-4) in anoxic sediments in contrast to methane (C-1). In hydrothermal vent systems, short-chain alkanes are formed over relatively short geological time scales via thermogenic processes and often exist at high concentrations. The sediment-covered hydrothermal vent systems at Middle Valley (MV Juan de Fuca Ridge) are an ideal site for investigating the anaerobic oxidation of C-1-C-4 alkanes, given the elevated temperatures and dissolved hydrocarbon species characteristic of these metalliferous sediments. We examined whether MV microbial communities oxidized C-1-C-4 alkanes under mesophilic to thermophilic sulfate-reducing conditions. Here we present data from discrete temperature (25, 55, and 75 degrees C) anaerobic batch reactor incubations of MV sediments supplemented with individual alkanes. Co-registered alkane consumption and sulfate reduction (SR) measurements provide clear evidence for C-1-C-4 alkane oxidation linked to SR over time and across temperatures. In these anaerobic batch reactor sediments, 16S ribosomal RNA pyrosequencing revealed that Deltaproteobacteria, particularly a novel sulfate-reducing lineage, were the likely phylotypes mediating the oxidation of C-2-C-4 alkanes. Maximum C-1-C-4 alkane oxidation rates occurred at 55 degrees C, which reflects the mid-core sediment temperature profile and corroborates previous studies of rate maxima for the anaerobic oxidation of methane (AOM). Of the alkanes investigated, C-3 was oxidized at the highest rate over time, then C-4, C-2, and C-1, respectively. The implications of these results are discussed with respect to the potential competition between the anaerobic oxidation of C-2-C(4)alkanes with AOM for available oxidants and the influence on the fate of C-1 derived from these hydrothermal systems.

  12. Modeling SOA formation from alkanes and alkenes in chamber experiments: effect of gas/wall partitioning of organic vapors.

    NASA Astrophysics Data System (ADS)

    Stéphanie La, Yuyi; Camredon, Marie; Ziemann, Paul; Ouzebidour, Farida; Valorso, Richard; Madronich, Sasha; Lee-Taylor, Julia; Hodzic, Alma; Aumont, Bernard

    2014-05-01

    Oxidation products of Intermediate Volatility Organic Compounds (IVOC) are expected to be the major precursors of secondary organic aerosols (SOA). Laboratory experiments were conducted this last decade in the Riverside APRC chamber to study IVOC oxidative mechanisms and SOA formation processes for a large set of linear, branched and cyclic aliphatic hydrocarbons (Ziemann, 2011). This dataset are used here to assess the explicit oxidation model GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) (Aumont et al., 2005). The simulated SOA yields agree with the general trends observed in the chamber experiments. They are (i) increasing with the increasing carbon number; (ii) decreasing with increasing methyl branch number; and (iii) increasing for cyclic compounds compared to their corresponding linear analogues. However, simulated SOA yields are systematically overestimated regardless of the precursors, suggesting missing processes in the model. In this study, we assess whether gas-to-wall partitioning of organic vapors can explain these model/observation mismatches (Matsunaga and Ziemann, 2010). First results show that GECKO-A outputs better match the observations when wall uptake of organic vapors is taken into account. Effects of gas/wall partitioning on SOA yields and composition will be presented. Preliminary results suggest that wall uptake is a major process influencing SOA production in the Teflon chambers. References Aumont, B., Szopa, S., Madronich, S.: Modelling the evolution of organic carbon during its gas-phase tropospheric oxidation: development of an explicit model based on a self generating approach. Atmos.Chem.Phys., 5, 2497-2517 (2005). P. J. Ziemann: Effects of molecular structure on the chemistry of aerosol formation from the OH-radical-initiated oxidation of alkanes and alkenes, Int. Rev.Phys.Chem., 30:2, 161-195 (2011). Matsunaga, A., Ziemann, P. J.: Gas-wall partitioning of organic compounds in a Teflon film

  13. (Pesticide chemistry)

    SciTech Connect

    Barnthouse, L.W.

    1990-09-04

    This report summarizes a trip by L. W. Barnthouse of the Environmental Sciences Division (ESD), Oak Ridge National Laboratory (ORNL), to Hamburg, Federal Republic of Germany (FRG), where he participated in the 7th International Congress of Pesticide Chemistry. He chaired a workshop on experimental systems for determining effects of pesticides on nontarget organisms and gave an oral presentation at a symposium on pesticide risk assessment. Before returning to the United States, Dr. Barnthouse visited the Netherlands Institute for Sea Research in Texel, the Netherlands.

  14. n-Alkanes in surficial sediments of Visakhapatnam harbour, east coast of India

    NASA Astrophysics Data System (ADS)

    Punyu, V. R.; Harji, R. R.; Bhosle, N. B.; Sawant, S. S.; Venkat, K.

    2013-04-01

    Surface sediments collected from 19 stations along Visakhapatnam harbour were analysed for organic carbon (OC), δ 13Coc, total lipids (TL), total hydrocarbon (THC), n-alkane concentration and composition. OC, δ 13Coc, TL and THC ranged from 0.6% to 7.6%, -29.3 to -23.8‰, 300 to 14,948 \\upmu g g - 1 dw, and 0.2 to 2,277 \\upmu g g - 1 dw, respectively. Predominance of even carbon numbers n-alkanes C12-C21 with carbon preference index (CPI) of <1 suggests major microbial influence. Fair abundance of odd carbon number n-alkanes in the range of C15-C22 and C23-C33 indicates some input from phytoplankton and terrestrial sources, respectively. Petrogenic input was evident from the presence of hopanes and steranes. The data suggest that organic matter (OM) sources varied spatially and were mostly derived from mixed source.

  15. The synergetic effect of starch and alpha amylase on the biodegradation of n-alkanes.

    PubMed

    Karimi, M; Biria, D

    2016-06-01

    The impact of adding soluble starch on biodegradation of n-alkanes (C10-C14) by Bacillus subtilis TB1 was investigated. Gas chromatography was employed to measure the residual hydrocarbons in the system. It was observed that the efficiency of biodegradation improved with the presence of starch and the obtained residual hydrocarbons in the system were 53% less than the samples without starch. The produced bacterial enzymes were studied through electrophoresis and reverse zymography for explaining the observations. The results indicated that the produced amylase by the bacteria can degrade hydrocarbons and the same was obtained by the application of a commercial alpha amylase sample. In addition, in silico docking of alpha-amylase with n-alkanes with different molecular weights was studied by Molegro virtual docker which showed high negative binding energies and further substantiated the experimental observations. Overall, the findings confirmed the catalytic effect of alpha amylase on n-alkanes degradation.

  16. Distribution, activity and function of short-chain alkane degrading phylotypes in hydrothermal vent sediments

    NASA Astrophysics Data System (ADS)

    Adams, M. M.; Joye, S. B.; Hoarfrost, A.; Girguis, P. R.

    2012-12-01

    Global geochemical analyses suggest that C2-C4 short chain alkanes are a common component of the utilizable carbon pool in deep-sea sediments worldwide and have been found in diverse ecosystems. From a thermodynamic standpoint, the anaerobic microbial oxidation of these aliphatic hydrocarbons is more energetically yielding than the anaerobic oxidation of methane (AOM). Therefore, the preferential degradation of these hydrocarbons may compete with AOM for the use of oxidants such as sulfate, or other potential oxidants. Such processes could influence the fate of methane in the deep-sea. Sulfate-reducing bacteria (SRB) from hydrocarbon seep sediments of the Gulf of Mexico and Guaymas Basin have previously been enriched that anaerobically oxidize short chain alkanes to generate CO2 with the preferential utilization of 12C-enriched alkanes (Kniemeyer et al. 2007). Different temperature regimens along with multiple substrates were tested and a pure culture (deemed BuS5) was isolated from mesophilic enrichments with propane or n-butane as the sole carbon source. Through comparative sequence analysis, strain BuS5 was determined to cluster with the metabolically diverse Desulfosarcina / Desulfococcus cluster, which also contains the SRB found in consortia with anaerobic, methane-oxidizing archaea in seep sediments. Enrichments from a terrestrial, low temperature sulfidic hydrocarbon seep also corroborated that propane degradation occurred with most bacterial phylotypes surveyed belonging to the Deltaproteobacteria, particularly Desulfobacteraceae (Savage et al. 2011). To date, no microbes capable of ethane oxidation or anaerobic C2-C4 alkane oxidation at thermophilic temperature have been isolated. The sediment-covered, hydrothermal vent systems found at Middle Valley (Juan de Fuca Ridge, eastern Pacific Ocean) are a prime environment for investigating mesophilic to thermophilic anaerobic oxidation of short-chain alkanes, given the elevated temperatures and dissolved

  17. The synergetic effect of starch and alpha amylase on the biodegradation of n-alkanes.

    PubMed

    Karimi, M; Biria, D

    2016-06-01

    The impact of adding soluble starch on biodegradation of n-alkanes (C10-C14) by Bacillus subtilis TB1 was investigated. Gas chromatography was employed to measure the residual hydrocarbons in the system. It was observed that the efficiency of biodegradation improved with the presence of starch and the obtained residual hydrocarbons in the system were 53% less than the samples without starch. The produced bacterial enzymes were studied through electrophoresis and reverse zymography for explaining the observations. The results indicated that the produced amylase by the bacteria can degrade hydrocarbons and the same was obtained by the application of a commercial alpha amylase sample. In addition, in silico docking of alpha-amylase with n-alkanes with different molecular weights was studied by Molegro virtual docker which showed high negative binding energies and further substantiated the experimental observations. Overall, the findings confirmed the catalytic effect of alpha amylase on n-alkanes degradation. PMID:26971168

  18. Mie potentials for phase equilibria calculations: application to alkanes and perfluoroalkanes.

    PubMed

    Potoff, Jeffrey J; Bernard-Brunel, Damien A

    2009-11-01

    Transferable united-atom force fields, based on n - 6 Lennard-Jones potentials, are presented for normal alkanes and perfluorocarbons. It is shown that by varying the repulsive exponent the range of the potential can be altered, leading to improved predictions of vapor pressures while also reproducing saturated liquid densities to high accuracy. Histogram-reweighting Monte Carlo simulations in the grand canonical ensemble are used to determine the vapor liquid coexistence curves, vapor pressures, heats of vaporization, and critical points for normal alkanes methane through tetradecane, and perfluorocarbons perfluoromethane through perfluorooctane. For all molecules studied, saturated liquid densities are reproduced to within 1% of experiment. Vapor pressures for normal alkanes and perfluorocarbons were predicted to within 3% and 6% of experiment, respectively. Calculations performed for binary mixture vapor-liquid equilibria for propane + pentane show excellent agreement with experiment, while slight deviations are observed for the ethane + perfluoroethane mixture.

  19. Diffusion Coefficients of n-Alkanes and Polyethylenes Filled with Zinc Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ozisik, Rahmi; Mattice, Wayne L.; von Meerwall, Ernst

    2003-03-01

    The diffusion coefficients of various n-alkane and polyethylene samples filled with zinc oxide nanoparticles were measured with pulsed-gradient spin-echo (PGSE) NMR technique. The n-alkanes used in this study had carbon numbers ranging between 12 and 60. The number average molecular weights of the two polyethylene samples were 6200 and 13900 g/mol. The different size of zinc oxide used with spherical geometry. The experiments were performed with three different zinc oxide nanoparticles that had differing sizes. This study investigates the effects of the nanoparticle size and the molecular weight on the diffusion coefficient of the polymer chains. The results account for the restriction to diffusion due to detour and tortuosity effects, which differ for n-alkanes and polyethylene. Because the effective diffusion distance in the PGSE NMR experiments is larger than the size of the nanoparticles, the observed diffusivities represent asymptotic averages over multiple encounters between the diffusing molecules and the nanoparticles.

  20. Pulse radiolysis of alkanes: A time-resolved electron paramagnetic resonance study

    SciTech Connect

    Shkrob, I.A.; Trifunac, A.D.

    1994-02-14

    Time-resolved spin-echo-detected electron paramagnetic resonance (EPR) was applied to examine short-lived alkyl radicals formed in pulse radiolysis of liquid alkanes. It was found that the ratio of yields of penultimate and interior radicals in n-alkanes at the instant of their generation is temperature-independent and is ca. 1.25 times greater than the statistical quantity. This higher-than-statistical production of penultimate radicals indicates that the fast ion molecule reactions involving radical cations are a significant route of radical generation. The analysis of spin-echo kinetics in n-alkanes suggests that the alkyl radicals are emissively polarized in spur reactions. this initial polarization rapidly increases with shortening of the aliphatic chain. Another finding is that a long-chain structure of these radicals results in much higher rate of Heisenberg spin exchange relative to the recombination rate. The relative yields of hydrogen abstraction and fragmentation for various branched alkanes are estimated. It is concluded that the fragmentation occurs prior to the formation of radicals in an excited precursor species. Effects of phenolic and alkene additives in radiolysis of n-alkanes are examined. It is demonstrated that phenoxy radicals are produced in dissociative capture of electrons and alkane holes. Another route is a reaction of phenols with free hydrogen atoms. A rapid transfer of singlet correlation from the geminate radical ion pairs is responsible for unusual polarization patterns in the phenoxy and cyclohexadienyl radicals. The significance of these results in the context of cross-linking in polyethylene and higher paraffins is discussed. 56 refs.

  1. Structure and Mass Transport Characteristics at the Intrinsic Liquid-Vapor Interfaces of Alkanes.

    PubMed

    Chilukoti, Hari Krishna; Kikugawa, Gota; Ohara, Taku

    2016-07-28

    In this paper, an instantaneous interface definition has been used to study the intrinsic structure and self-diffusion coefficient in the vicinity of the liquid-vapor interfaces of decane and tetracosane at three different temperatures using molecular dynamics simulations, and the results have been compared with those obtained on the basis of the conventional Gibbs dividing surface (time- and space-averaged interface). The alkane molecules were modeled using the united atom NERD force field. Partial layered structures of alkane molecules at the liquid-vapor interface are observed as a pinned structure of alkane liquids based on the intrinsic interface. This kind of characteristic has not been observed in the density profiles obtained based on the Gibbs dividing surface. By examining the orientation order parameter and radius of gyration of the alkane molecules, it was observed that the alkane molecules were preferentially oriented to be more parallel to the intrinsic interface than to the Gibbs dividing surface, and the shape of the alkane molecules is slightly changed in the vicinity of the liquid-vapor interfaces. The self-diffusion coefficient parallel to the intrinsic interface was examined using the Green-Kubo relation, where the projection of the velocity in the parallel direction to the local intrinsic interface is used in the velocity correlation function. It was found that the self-diffusion coefficient in the direction parallel to the intrinsic interface changes as the position approaches the interface in a more obvious manner as compared with the self-diffusion coefficient obtained with respect to the Gibbs dividing surface. These results suggest that the use of an instantaneous interface definition allowed us to capture sharp variations in transport properties which are originating due to steeper structure at the liquid-vapor interfaces.

  2. Structure and Mass Transport Characteristics at the Intrinsic Liquid-Vapor Interfaces of Alkanes.

    PubMed

    Chilukoti, Hari Krishna; Kikugawa, Gota; Ohara, Taku

    2016-07-28

    In this paper, an instantaneous interface definition has been used to study the intrinsic structure and self-diffusion coefficient in the vicinity of the liquid-vapor interfaces of decane and tetracosane at three different temperatures using molecular dynamics simulations, and the results have been compared with those obtained on the basis of the conventional Gibbs dividing surface (time- and space-averaged interface). The alkane molecules were modeled using the united atom NERD force field. Partial layered structures of alkane molecules at the liquid-vapor interface are observed as a pinned structure of alkane liquids based on the intrinsic interface. This kind of characteristic has not been observed in the density profiles obtained based on the Gibbs dividing surface. By examining the orientation order parameter and radius of gyration of the alkane molecules, it was observed that the alkane molecules were preferentially oriented to be more parallel to the intrinsic interface than to the Gibbs dividing surface, and the shape of the alkane molecules is slightly changed in the vicinity of the liquid-vapor interfaces. The self-diffusion coefficient parallel to the intrinsic interface was examined using the Green-Kubo relation, where the projection of the velocity in the parallel direction to the local intrinsic interface is used in the velocity correlation function. It was found that the self-diffusion coefficient in the direction parallel to the intrinsic interface changes as the position approaches the interface in a more obvious manner as compared with the self-diffusion coefficient obtained with respect to the Gibbs dividing surface. These results suggest that the use of an instantaneous interface definition allowed us to capture sharp variations in transport properties which are originating due to steeper structure at the liquid-vapor interfaces. PMID:27387788

  3. Self-assembly of long chain alkanes and their derivatives on graphite

    NASA Astrophysics Data System (ADS)

    Yang, Teng; Berber, Savas; Tománek, David; Liu, Jun-Fu; Miller, Glen P.

    2008-03-01

    We combine scanning tunneling microscopy (STM) measurements with ab initio calculations to study the self-assembly of long chain alkanes and related alcohol and carboxylic acid molecules on graphite. For each system, we identify the optimum adsorption geometry and explain the energetic origin of the domain formation observed in the STM images. Our results for the hierarchy of adsorbate-adsorbate and adsorbate-substrate interactions provide a quantitative basis to understand the ordering of long chain alkanes in self-assembled monolayers and ways to modify it using alcohol and acid functional groups.

  4. Monocarboxylic acids from oxidation of acyclic isoprenoid alkanes by Mycobacterium fortuitum

    NASA Technical Reports Server (NTRS)

    Cox, R. E.; Maxwell, J. R.; Myers, R. N.

    1976-01-01

    Mycobacterium fortuitum utilizes certain stereoisomeric mixtures of individual multimethyl branched alkanes as sole carbon source, including 2,6(R), 10(S), 14(RS)-tetramethylhexadecane; 2,6(R), 10(S), 14(RS)-tetramethylheptadecane; 2,6(RS), 10(RS)-trimethyltetradecane, and 2,6(R), 10(S)-trimethylpentadecane. Products of oxidation isolated from the bacterial lipids were acids derived predominantly from oxidation of the isopropyl terminus of each alkane, except in the case of 2,6(RS), 10(RS)-trimethyltetradecane. With the latter, acids from oxidation at either terminus were detected in comparable proportions.

  5. Self-assembly of long chain alkanes and their derivatives on graphite.

    PubMed

    Yang, Teng; Berber, Savas; Liu, Jun-Fu; Miller, Glen P; Tománek, David

    2008-03-28

    We combine scanning tunneling microscopy (STM) measurements with ab initio calculations to study the self-assembly of long chain alkanes and related alcohol and carboxylic acid molecules on graphite. For each system, we identify the optimum adsorption geometry and explain the energetic origin of the domain formation observed in the STM images. Our results for the hierarchy of adsorbate-adsorbate and adsorbate-substrate interactions provide a quantitative basis to understand the ordering of long chain alkanes in self-assembled monolayers and ways to modify it using alcohol and acid functional groups.

  6. Benzylic Phosphates in Friedel-Crafts Reactions with Activated and Unactivated Arenes: Access to Polyarylated Alkanes.

    PubMed

    Pallikonda, Gangaram; Chakravartya, Manab

    2016-03-01

    Easily reachable electron-poor/rich primary and secondary benzylic phosphates are suitably used as substrates for Friedel-Crafts benzylation reactions with only 1.2 equiv activated/deactivated arenes (no additional solvent) to access structurally and electronically diverse polyarylated alkanes with excellent yields and selectivities at room temperature. Specifically, diversely substituted di/triarylmethanes are generated within 2-30 min using this approach. A wide number of electron-poor polyarylated alkanes are easily accomplished through this route by just tuning the phosphates. PMID:26835977

  7. Mass effect on the Soret coefficient in n-alkane mixtures.

    PubMed

    Alonso de Mezquia, David; Bou-Ali, M Mounir; Madariaga, J Antonio; Santamaría, Carlos

    2014-02-28

    We have determined the Soret coefficient of different equimolar and non equimolar n-alkane mixtures from measurements of the molecular diffusion and thermal diffusion coefficients. It is shown that equimolar mixtures behave as isotopic-like mixtures in which only the mass effect contributes to the Soret effect. In non equimolar mixtures, a small linear dependence with the molar fraction is observed. Finally, we have obtained a new correlation, which allows the determination of the Soret coefficient of n-alkane mixtures using the data of viscosity, the thermal expansion coefficient of the pure components, and the density of the equimolar mixture. PMID:24588181

  8. Regioselective alkane hydroxylation with a mutant CYP153A6 enzyme

    DOEpatents

    Koch, Daniel J.; Arnold, Frances H.

    2013-01-29

    Cytochrome P450 CYP153A6 from Myobacterium sp. strain HXN1500 was engineered using in-vivo directed evolution to hydroxylate small-chain alkanes regioselectively. Mutant CYP153A6-BMO1 selectively hydroxylates butane and pentane at the terminal carbon to form 1-butanol and 1-pentanol, respectively, at rates greater than wild-type CYP153A6 enzymes. This biocatalyst is highly active for small-chain alkane substrates and the regioselectivity is retained in whole-cell biotransformations.

  9. Mass effect on the Soret coefficient in n-alkane mixtures

    SciTech Connect

    Alonso de Mezquia, David; Mounir Bou-Ali, M.; Madariaga, J. Antonio; Santamaría, Carlos

    2014-02-28

    We have determined the Soret coefficient of different equimolar and non equimolar n-alkane mixtures from measurements of the molecular diffusion and thermal diffusion coefficients. It is shown that equimolar mixtures behave as isotopic-like mixtures in which only the mass effect contributes to the Soret effect. In non equimolar mixtures, a small linear dependence with the molar fraction is observed. Finally, we have obtained a new correlation, which allows the determination of the Soret coefficient of n-alkane mixtures using the data of viscosity, the thermal expansion coefficient of the pure components, and the density of the equimolar mixture.

  10. Photolytic formation of free radicals and their effect on hydrocarbon pyrolysis chemistry in a concentrated solar environment: Final report

    SciTech Connect

    Hunjan, M.; Mok, W.S.; Antal, M.J. Jr.

    1987-01-01

    The objective of this research was two-fold: (1) to determine whether uv photons available in a concentrated solar environment can be used as a photolytic source to dissociate vapor phase acetone; and (2) to explore the effects of photolysis on rate and selectivity of free radical reactions. The experiments were conducted in a 1 kW arc image furnace/tubular flow reactor system. The results obtained conclusively showed that acetone readily photodissociates in a 1000 sun environment, leading to the formation of free radicals. It was further observed that Beer-Lambert law can be used to predict the rate of photolysis of acetone. Furthermore, acetone, when used as source of methyl radicals, sensitized the reaction chemistry of alkanes and alkenes at a temperature of 350/sup 0/C. The methyl radicals from photolysis of acetone enhanced the cracking reactions of the alkanes yielding smaller alkanes and alkenes. When the initial hydrocarbon reactant was an alkene, a sensitization of the addition reaction was observed leading to formation of next higher alkene. To gain a theoretical insight into the reaction chemistry of alkanes, a numerical simulation model was developed to study the photosensitized decomposition of n-butane and the simulation results thus obtained were found to be in close agreement with experimental results. 64 refs., 10 figs., 22 tabs.

  11. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane,...

  12. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane,...

  13. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane,...

  14. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane,...

  15. 40 CFR 721.10145 - Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Modified reaction products of alkyl... Modified reaction products of alkyl alcohol, halogenated alkane, substituted epoxide, and amino compound... identified generically as modified reaction products of alkyl alcohol, halogenated alkane,...

  16. 40 CFR 721.10103 - Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Naphtha (Fischer-Tropsch), C4-11... Significant New Uses for Specific Chemical Substances § 721.10103 Naphtha (Fischer-Tropsch), C4-11-alkane... substance identified as naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN P-04-235; CAS...

  17. 40 CFR 721.10103 - Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Naphtha (Fischer-Tropsch), C4-11... Significant New Uses for Specific Chemical Substances § 721.10103 Naphtha (Fischer-Tropsch), C4-11-alkane... substance identified as naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN P-04-235; CAS...

  18. 40 CFR 721.10103 - Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Naphtha (Fischer-Tropsch), C4-11... Significant New Uses for Specific Chemical Substances § 721.10103 Naphtha (Fischer-Tropsch), C4-11-alkane... substance identified as naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN P-04-235; CAS...

  19. 40 CFR 721.10103 - Naphtha (Fischer-Tropsch), C4-11-alkane, branched and linear.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Naphtha (Fischer-Tropsch), C4-11... Significant New Uses for Specific Chemical Substances § 721.10103 Naphtha (Fischer-Tropsch), C4-11-alkane... substance identified as naphtha (fischer-tropsch), C4-11-alkane, branched and linear (PMN P-04-235; CAS...

  20. Detailed chemical kinetic models for large n-alkanes and iso-alkanes found in conventional and F-T diesel fuels

    SciTech Connect

    Westbrook, C K; Pitz, W J; Mehl, M; Curran, H J

    2009-03-09

    n-Hexadecane and 2,2,4,4,6,8,8-heptamethylnonane represent the primary reference fuels for diesel that are used to determine cetane number, a measure of the ignition property of diesel fuel. With the development of chemical kinetics models for both primary reference fuels, a new capability is now available to model diesel fuel ignition. Additionally, we have developed chemical kinetic models for a whole series of large n-alkanes and a large iso-alkane to represent these chemical classes in fuel surrogates for conventional and future fuels. These chemical kinetic models are used to predict the effect of the aforementioned fuel components on ignition characteristics under conditions found in internal combustion engines.

  1. Provocative Opinion: Descriptive Chemistry.

    ERIC Educational Resources Information Center

    Bent, Henry A.; Bent, Brian E.

    1987-01-01

    Discusses many of the distinctions that chemists draw between theoretical chemistry and descriptive chemistry, along with the tendency for chemical educators to adopt the type of chemistry they feel is most important to teach. Uses examples to argue that theoretical chemistry and descriptive chemistry are, at the bottom line, the same. (TW)

  2. Enhanced Translocation and Growth of Rhodococcus erythropolis PR4 in the Alkane Phase of Aqueous-Alkane Two Phase Cultures Were Mediated by GroEL2 Overexpression

    PubMed Central

    Takihara, Hayato; Ogihara, Jun; Yoshida, Takao; Okuda, Shujiro; Nakajima, Mutsuyasu; Iwabuchi, Noriyuki; Sunairi, Michio

    2014-01-01

    We previously reported that R. erythropolis PR4 translocated from the aqueous to the alkane phase, and then grew in two phase cultures to which long-chain alkanes had been added. This was considered to be beneficial for bioremediation. In the present study, we investigated the proteins involved in the translocation of R. erythropolis PR4. The results of our proteogenomic analysis suggested that GroEL2 was upregulated more in cells that translocated inside of the pristane (C19) phase than in those located at the aqueous-alkane interface attached to the n-dodecane (C12) surface. PR4 (pK4-EL2-1) and PR4 (pK4-ΔEL2-1) strains were constructed to confirm the effects of the upregulation of GroEL2 in translocated cells. The expression of GroEL2 in PR4 (pK4-EL2-1) was 15.5-fold higher than that in PR4 (pK4-ΔEL2-1) in two phase cultures containing C12. The growth and cell surface lipophilicity of PR4 were enhanced by the introduction of pK4-EL2-1. These results suggested that the plasmid overexpression of groEL2 in PR4 (pK4-EL2-1) led to changes in cell localization, enhanced growth, and increased cell surface lipophilicity. Thus, we concluded that the overexpression of GroEL2 may play an important role in increasing the organic solvent tolerance of R. erythropolis PR4 in aqueous-alkane two phase cultures. PMID:25311591

  3. Alkane dehydrogenation catalyzed by rhodium(I) phosphine complexes. Observation of the stoichiometric alkane-to-rhodium hydrogen-transfer step

    SciTech Connect

    Shih, K.C.; Goldman, A.S. )

    1993-09-01

    RhL[sub 2]Cl (L = P[sup t]Pr[sub 3]) is found to dehydrogenate cyclooctane to give H[sub 2]RhL[sub 2]Cl and cyclooctene; this represents the first observation of the key hydrogen-transfer step proposed for related, catalytic alkane transfer-dehydrogenation systems. Using norbornene as a hydrogen acceptor, transfer-dehydrogenation is catalyzed but turnover numbers are low. 18 refs., 1 tab.

  4. Evaluation of NO+ reagent ion chemistry for online measurements of atmospheric volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Koss, Abigail R.; Warneke, Carsten; Yuan, Bin; Coggon, Matthew M.; Veres, Patrick R.; de Gouw, Joost A.

    2016-07-01

    NO+ chemical ionization mass spectrometry (NO+ CIMS) can achieve fast (1 Hz and faster) online measurement of trace atmospheric volatile organic compounds (VOCs) that cannot be ionized with H3O+ ions (e.g., in a PTR-MS or H3O+ CIMS instrument). Here we describe the adaptation of a high-resolution time-of-flight H3O+ CIMS instrument to use NO+ primary ion chemistry. We evaluate the NO+ technique with respect to compound specificity, sensitivity, and VOC species measured compared to H3O+. The evaluation is established by a series of experiments including laboratory investigation using a gas-chromatography (GC) interface, in situ measurement of urban air using a GC interface, and direct in situ measurement of urban air. The main findings are that (1) NO+ is useful for isomerically resolved measurements of carbonyl species; (2) NO+ can achieve sensitive detection of small (C4-C8) branched alkanes but is not unambiguous for most; and (3) compound-specific measurement of some alkanes, especially isopentane, methylpentane, and high-mass (C12-C15) n-alkanes, is possible with NO+. We also demonstrate fast in situ chemically specific measurements of C12 to C15 alkanes in ambient air.

  5. Adiabatic Coupling Constant of Nitrobenzene- n-Alkane Critical Mixtures. Evidence from Ultrasonic Spectra and Thermodynamic Data

    NASA Astrophysics Data System (ADS)

    Mirzaev, Sirojiddin Z.; Kaatze, Udo

    2016-09-01

    Ultrasonic spectra of mixtures of nitrobenzene with n-alkanes, from n-hexane to n-nonane, are analyzed. They feature up to two Debye-type relaxation terms with discrete relaxation times and, near the critical point, an additional relaxation term due to the fluctuations in the local concentration. The latter can be well represented by the dynamic scaling theory. Its amplitude parameter reveals the adiabatic coupling constant of the mixtures of critical composition. The dependence of this thermodynamic parameter upon the length of the n-alkanes corresponds to that of the slope in the pressure dependence of the critical temperature and is thus taken another confirmation of the dynamic scaling model. The change in the variation of the coupling constant and of several other mixture parameters with alkane length probably reflects a structural change in the nitrobenzene- n-alkane mixtures when the number of carbon atoms per alkane exceeds eight.

  6. Classification of vegetable oils according to their botanical origin using n-alkane profiles established by GC-MS.

    PubMed

    Troya, F; Lerma-García, M J; Herrero-Martínez, J M; Simó-Alfonso, E F

    2015-01-15

    n-Alkane profiles established by gas chromatography-mass spectrometry (GC-MS) were used to classify vegetable oils according to their botanical origin. The n-alkanes present in corn, grapeseed, hazelnut, olive, peanut and sunflower oils were isolated by means of alkaline hydrolysis followed by silica gel column chromatography of the unsaponifiable fractions. The n-alkane fraction was constituted mainly of n-alkanes in the range C8-C35, although only those most abundant (15 n-alkanes, from 21 to 35 carbon No.) were used as original variables to construct linear discriminant analysis (LDA) models. Ratios of the peak areas selected by pairs were used as predictors. All the oils were correctly classified according to their botanical origin, with assignment probabilities higher than 95%, using an LDA model.

  7. Combustion chemistry

    SciTech Connect

    Brown, N.J.

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  8. Ab initio simulations reveal that reaction dynamics strongly affect product selectivity for the cracking of alkanes over H-MFI.

    PubMed

    Zimmerman, Paul M; Tranca, Diana C; Gomes, Joseph; Lambrecht, Daniel S; Head-Gordon, Martin; Bell, Alexis T

    2012-11-28

    Product selectivity of alkane cracking catalysis in the H-MFI zeolite is investigated using both static and dynamic first-principles quantum mechanics/molecular mechanics simulations. These simulations account for the electrostatic- and shape-selective interactions in the zeolite and provide enthalpic barriers that are closely comparable to experiment. Cracking transition states for n-pentane lead to a metastable intermediate (a local minimum with relatively small barriers to escape to deeper minima) where the proton is shared between two hydrocarbon fragments. The zeolite strongly stabilizes these carbocations compared to the gas phase, and the conversion of this intermediate to more stable species determines the product selectivity. Static reaction pathways on the potential energy surface starting from the metastable intermediate include a variety of possible conversions into more stable products. One-picosecond quasiclassical trajectory simulations performed at 773 K indicate that dynamic paths are substantially more diverse than the potential energy paths. Vibrational motion that is dynamically sampled after the cracking transition state causes spilling of the metastable intermediate into a variety of different products. A nearly 10-fold change in the branching ratio between C2/C3 cracking channels is found upon inclusion of post-transition-state dynamics, relative to static electronic structure calculations. Agreement with experiment is improved by the same factor. Because dynamical effects occur soon after passing through the rate-limiting transition state, it is the dynamics, and not only the potential energy barriers, that determine the catalytic selectivity. This study suggests that selectivity in zeolite catalysis is determined by high temperature pathways that differ significantly from 0 K potential surfaces.

  9. Why Teach Environmental Chemistry?

    ERIC Educational Resources Information Center

    Gardner, Marjorie H.

    1974-01-01

    Discusses the importance of teaching environmental chemistry in secondary school science classes, and outlines five examples of environmental chemistry problems that focus on major concepts of chemistry and have critical implications for human survival and well-being. (JR)

  10. Science Update: Inorganic Chemistry

    ERIC Educational Resources Information Center

    Rawls, Rebecca

    1978-01-01

    This first in a series of articles describing the state of the art of various branches of chemistry reviews inorganic chemistry, including bioinorganic, photochemistry, organometallic, and solid state chemistries. (SL)

  11. Science Update: Inorganic Chemistry.

    ERIC Educational Resources Information Center

    Rawls, Rebecca

    1981-01-01

    Describes areas of inorganic chemistry which have changed dramatically in the past year or two, including photochemistry, electrochemistry, organometallic complexes, inorganic reaction theory, and solid state chemistry. (DS)

  12. 40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... with mixed metal oxides (generic). 721.10148 Section 721.10148 Protection of Environment ENVIRONMENTAL... mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acryloxy alkanoic alkane derivative with mixed...

  13. 40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with mixed metal oxides (generic). 721.10148 Section 721.10148 Protection of Environment ENVIRONMENTAL... mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acryloxy alkanoic alkane derivative with mixed...

  14. Improved GC/MS method for quantitation of n-Alkanes in plant and fecal material

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A gas chromatography-mass spectrometry (GC/MS) method for the quantitation of n-alkanes (carbon backbones ranging from 21 to 36 carbon atoms) in forage and fecal samples has been developed. Automated solid-liquid extraction using elevated temperature and pressure minimized extraction time to 30 min...

  15. Anaerobic biodegradation of long-chain n-alkanes under sulfate-reducing conditions

    SciTech Connect

    Caldwell, M.E.; Suflita, J.M.; Garrett, R.M.; Prince, R.C.

    1998-07-15

    The ability of anaerobic microorganisms to degrade a wide variety of crude oil components was investigated using chronically hydrocarbon-contaminated marine sediments as the source of inoculum. When sulfate reduction was the predominant electron-accepting process, gas chromatographic analysis revealed almost complete n-alkane removal (C{sub 15}-C{sub 34}) from a weathered oil within 201 d of incubation. No alteration of the oil was detected in sterile control incubations or when nitrate served as an alternate electron acceptor. The amount of sulfate reduced in the oil-amended nonsterile incubations was more than enough to account for the complete mineralization of the n-alkane fraction of the oil; no loss of this anion was observed in sterile control incubations. The mineralization of the alkanes was confirmed using {sup 14}C-14,15-octacosane (C{sub 28}H{sub 58}), with 97% of the radioactivity recovered as {sup 14}CO{sub 2}. These findings extend the range of hydrocarbons known to be amenable to anaerobic biodegradation. Moreover, the rapid and extensive alteration in the n-alkanes can no longer be considered a defining characteristic of aerobic oil biodegradation processes alone.

  16. Microstructure of High Pressure Polyolefin/n-Alkane & Dimethyl Ether Solutions

    NASA Astrophysics Data System (ADS)

    van Zanten, John; McHugh, Mark; Li, Dan; Guney-Altay, Ozge; Dinoia, Todd; Kermis, Thomas; Park, Il-Hyun

    2003-03-01

    A series of dilute and semi-dilute poly(ethylene-co-1-butene)/n-alkane and dimethyl ether (DME) solutions have been investigated with high pressure small angle neutron scattering and dynamic light scattering. The n-alkane solvents considered in these investigations were ethane, propane, butane and pentane. The solutions have been examined at 110-150 °C and at pressures up to ˜2500 bar. In the semi-dilute concentration range, the classic high concentration isotopic labeling technique is used in conjunction with small angle neutron scattering to determine both the solution correlation length and coil dimensions for poly(ethylene-co-1-butene) dissolved in either ethane, pentane or DME. Chain collapse is observed upon approach to the phase boundary in n-alkane solutions but is absent in DME solutions. For the dilute solution regime, solutions of varying concentration in all of the n-alkanes and DME are considered in order to determine both the polymer diffusion coefficient at infinite dilution as well as the dynamic second viral coefficient which is primarily dominated by the second osmotic virial coefficient. The polymer coil hydrodynamic radii behavior in dilute solutions is essentially the same as that observed for the semi-dilute solutions. Coil behavior in the dilute and semi-dilute concentration regimes is compared and contrasted.

  17. 40 CFR 721.10148 - Acryloxy alkanoic alkane derivative with mixed metal oxides (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... with mixed metal oxides (generic). 721.10148 Section 721.10148 Protection of Environment ENVIRONMENTAL... mixed metal oxides (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as acryloxy alkanoic alkane derivative with mixed...

  18. Iridium complexes of new NCP pincer ligands: catalytic alkane dehydrogenation and alkene isomerization.

    PubMed

    Jia, Xiangqing; Zhang, Lei; Qin, Chuan; Leng, Xuebing; Huang, Zheng

    2014-09-28

    Iridium complexes of novel NCP pincer ligands containing pyridine and phosphinite arms have been synthesized. One Ir complex shows good catalytic activity for alkane dehydrogenation, and all complexes are highly active for olefin isomerization. A combination of the Ir complex and a (PNN)Fe pincer complex catalyzes the formation of linear alkylboronates selectively from internal olefins via sequential olefin isomerization-hydroboration.

  19. Biosurfactant-mediated biodegradation of straight and methyl-branched alkanes by Pseudomonas aeruginosa ATCC 55925

    PubMed Central

    2011-01-01

    Accidental oil spills and waste disposal are important sources for environmental pollution. We investigated the biodegradation of alkanes by Pseudomonas aeruginosa ATCC 55925 in relation to a rhamnolipid surfactant produced by the same bacterial strain. Results showed that the linear C11-C21 compounds in a heating oil sample degraded from 6% to 100%, whereas the iso-alkanes tended to be recalcitrant unless they were exposed to the biosurfactant; under such condition total biodegradation was achieved. Only the biodegradation of the commercial C12-C19 alkanes could be demonstrated, ranging from 23% to 100%, depending on the experimental conditions. Pristane (a C19 branched alkane) only biodegraded when present alone with the biosurfactant and when included in an artificial mixture even without the biosurfactant. In all cases the biosurfactant significantly enhanced biodegradation. The electron scanning microscopy showed that cells depicted several adaptations to growth on hydrocarbons, such as biopolymeric spheres with embedded cells distributed over different layers on the spherical surfaces and cells linked to each other by extracellular appendages. Electron transmission microscopy revealed transparent inclusions, which were associated with hydrocarbon based-culture cells. These patterns of hydrocarbon biodegradation and cell adaptations depended on the substrate bioavailability, type and length of hydrocarbon. PMID:21906343

  20. 40 CFR 721.785 - Halogenated alkane aromatic compound (generic name).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.785 Halogenated alkane aromatic compound (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified...

  1. Immunogenecity of Modified Alkane Polymers Is Mediated through TLR1/2 Activation

    PubMed Central

    Crisi, Giovanna M.; Cobelli, Neil; Santambrogio, Laura

    2008-01-01

    Background With the advancement of biomedical technology, artificial materials have been developed to replace diseased, damaged or nonfunctional body parts. Among such materials, ultra high molecular weight alkane or modified alkyl polymers have been extensively used in heart valves, stents, pacemakers, ear implants, as well as total joint replacement devices. Although much research has been undertaken to design the most non-reactive biologically inert polyethylene derivatives, strong inflammatory responses followed by rejection and failure of the implant have been noted. Methodology/Principal Findings Purification of the alkane polymers from the site of inflammation revealed extensive “in vivo” oxidation as detected by fourier transformed infra-red spectroscopy. Herein, we report the novel observation that oxidized alkane polymers induced activation of TLR1/2 pathway as determined by ligand dependent changes in intrinsic tyrosine fluorescence intensity and NF-κΒ luciferase gene assays. Oxidized polymers were very effective in activating dendritic cells and inducing secretion of pro-inflammatory cytokines. Molecular docking of the oxidized alkanes designated ligand specificity and polymeric conformations fitting into the TLR1/2 binding grooves. Conclusion/Significance This is the first report of a synthetic polymer activating immune responses through TLR binding. PMID:18560588

  2. Macroseepage of Methane and Light Alkanes at the La Brea Tar Pits in Los Angeles

    NASA Astrophysics Data System (ADS)

    Doezema, L. A.; Weber, D.; Schuffels, S.; Marquez, A.; Taylor, C.; Raya, P.; Howard, D.; Contreras, P.; Fusco, K.; Morales, F.; Nwachuku, I.

    2015-12-01

    Natural seepage of methane has been theorized to be an underreported source of global methane. Recent studies have also suggested that light alkane flux that is given off in combination with the methane also is underreported in local and global budgets. This study investigated macroseepage, visible seepage, at the La Brea Tar Pits in Los Angeles, CA. More than 100 samples were collected from individual seeps using stainless steel flux chambers and canisters and were analyzed for methane and C2-C5 alkanes using gas chromatography equipped with flame ionization detectors (GC-FID). Maximum hourly fluxes from individual seeps were over 70 g of methane and over 720 mg, 670 mg, 200 mg, 20 mg, 14 mg, and 0.2 mg for ethane, propane, i-butane, n-butane, i-pentane, and n-pentane respectively. In addition to the active seepage sites, a significant amount of methane and light alkanes was also found to come from outgassing from standing tar deposits. Using gas ratios found in this study along with overall methane emission estimates from another recent study, the La Brea Tar Pits were found to be a significant source of light alkanes in the South Coast Air Basin, contributing approximately 2% towards the overall budget.

  3. Technical Note: n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary?

    NASA Astrophysics Data System (ADS)

    Zech, M.; Kreutzer, S.; Goslar, T.; Meszner, S.; Krause, T.; Faust, D.; Fuchs, M.

    2012-07-01

    There is an ongoing discussion whether n-alkane biomarkers - and organic matter (OM) from loess in general - reflect a syn-sedimentary paleoenvironmental and paleoclimate signal or whether they are significantly a post-sedimentary feature contaminated by root-derived OM. We present first radiocarbon data for the n-alkane fraction of lipid extracts and for the first time luminescence ages for the Middle to Late Weichselian loess-paleosol sequence of Gleina in Saxony, Germany. Comparison of these biomarker ages with sedimentation ages as assessed by optically stimulated luminescence (OSL) dating shows that one n-alkane sample features a syn-sedimentary age (14C: 29.2 ± 1.4 kyr cal BP versus OSL: 27.3 ± 3.0 kyr). By contrast, the 14C ages derived from the other n-alkane samples are clearly younger (20.3 ± 0.7 kyr cal BP, 22.1 ± 0.7 kyr cal BP and 29.8 ± 1.4 kyr cal BP) than the corresponding OSL ages (26.6 ± 3.1 kyr, 32.0 ± 3.5 kyr and 45.6 ± 5.3 kyr). This finding suggests that a post-sedimentary n-alkane contamination presumably by roots has occurred. In order to estimate the post-sedimentary n-alkane contamination more quantitatively, we applied a 14C mass balance calculation based on the measured pMC (percent modern carbon) values, the calculated syn-sedimentary pMC values and pMC values suspected to reflect likely time points of post-sedimentary contamination (current, modern, 3 kyr, 6 kyr and 9 kyr). Accordingly, current and modern root-contamination would account for up to 7%, a 3 kyr old root-contamination for up to 10%, and an Early and Middle Holocene root-contamination for up to 20% of the total sedimentary n-alkane pool. We acknowledge and encourage that these first radiocarbon results need further confirmation both from other loess-paleosol sequences and for different biomarkers, e.g. carboxylic acids or alcohols as further lipid biomarkers.

  4. Investigating C4 Grass Contributions to N-alkane Based Paleoclimate Reconstructions

    NASA Astrophysics Data System (ADS)

    Doman, C. E.; Enders, S. K.; Chadwick, O.; Freeman, K. H.

    2014-12-01

    Plant wax n-alkanes are long-chain, saturated hydrocarbons contained within the protective waxy cuticle on leaves. These lipids are pervasive and persistent in soils and sediments and thus are ideal biomarkers of ancient terrestrial organic matter. In ecosystems dominated by C3 plants, the relationship between the carbon isotopic value of whole leaves and lipids is fairly well documented, but this relationship has not been fully investigated for plants that use C4 photosynthesis. In both cases, it is unclear if the isotopic relationships are sensitive to environmental conditions, or reflect inherited characteristics. This study used a natural climate gradient on the Kohala peninsula of Hawaii to investigate relationships between climate and the δ13C and δ2H values of n-alkanes in C3 and C4 plants. δ13C of C3 leaves and lipids decreased 5 ‰ from the driest to the wettest sites, consistent with published data. Carbon isotope values of C4 plants showed no relationship to moisture up to 1000 mm mean annual precipitation (MAP). Above this threshold, δ 13C values were around 10‰ more depleted, likely due to a combination of canopy effects and C4 grasses growing in an uncharacteristically wet and cold environment. In C3 plants, the fractionation between leaf and lipid carbon isotopes did not vary with MAP, which allows estimations of δ13C leaf to be made from alkanes preserved in ancient sediments. Along this transect, C3 plants produce around twice the quantity of n-alkanes as C4 grasses. C4 grasses produce longer carbon chains. As a result, n-alkanes in the geologic record will be biased towards C3 plants, but the presence of alkanes C33 and C35 indicate the contributions of C4 grasses. In both C3 and C4 plants, average chain length increased with mean annual precipitation, but the taxonomic differences in chain length were greater than environmental differences. Hydrogen isotopes of n-alkanes show no trends with MAP, but do show clear differences between plant

  5. n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary?

    NASA Astrophysics Data System (ADS)

    Zech, Michael; Kreutzer, Sebastian; Goslar, Tomasz; Meszner, Sascha; Krause, Tobias; Faust, Dominik; Fuchs, Markus

    2013-04-01

    There is an ongoing discussion whether n-alkane biomarkers - and organic matter (OM) from loess in general - reflect a syn-sedimentary paleoenvironmental and paleoclimate signal or whether they are significantly a post-sedimentary feature contaminated by root-derived OM (Zech et al., 2012, 2013; Wiesenberg and Gocke, 2013). We present first radiocarbon data for the n-alkane fraction of lipid extracts and for the first time luminescence ages for the Middle to Late Weichselian loess-paleosol sequence of Gleina in Saxony, Germany. Comparison of these biomarker ages with sedimentation ages as assessed by optically stimulated luminescence (OSL) dating shows that one n-alkane sample features a syn-sedimentary age (14C: 29.2 ± 1.4 kyr calBP versus OSL: 27.3 ± 3.0 kyr). By contrast, the 14C ages derived from the other n-alkane samples are clearly younger (20.3 ± 0.7 kyr calBP, 22.1 ± 0.7 kyr calBP and 29.8 ± 1.4 kyr calBP) than the corresponding OSL ages (26.6 ± 3.1 kyr, 32.0 ± 3.5 kyr and 45.6 ± 5.3 kyr). This finding suggests that a post-sedimentary n-alkane contamination presumably by roots has occurred. In order to estimate the post-sedimentary n-alkane contamination more quantitatively, we applied a 14C mass balance calculation based on the measured pMC (percent modern carbon) values, the calculated syn-sedimentary pMC values and pMC values suspected to reflect likely time points of post-sedimentary contamination (modern, last decades, 3 kyr, 6 kyr and 9 kyr). Accordingly, modern and last decadal root-contamination would account for up to 7%, a 3 kyr old root-contamination for up to 10%, and an Early and Middle Holocene root-contamination for up to 20% of the total sedimentary n-alkane pool. We acknowledge and encourage that these first radiocarbon results need further confirmation both from other loess-paleosol sequences and for different biomarkers, e.g. carboxylic acids or alcohols as further lipid biomarkers. Zech, M., Kreutzer, S., Goslar, T., Meszner, S

  6. QSAR models for predicting in vivo aquatic toxicity of chlorinated alkanes to fish.

    PubMed

    Zvinavashe, Elton; van den Berg, Hans; Soffers, Ans E M F; Vervoort, Jacques; Freidig, Andreas; Murk, Albertinka J; Rietjens, Ivonne M C M

    2008-03-01

    Quantitative structure-activity relationship (QSAR) models are expected to play a crucial role in reducing the number of animals to be used for toxicity testing resulting from the adoption of the new European Union chemical control system called Registration, Evaluation, and Authorization of Chemicals (REACH). The objective of the present study was to generate in vitro acute toxicity data that could be used to develop a QSAR model to describe acute in vivo toxicity of chlorinated alkanes. Cytotoxicity of a series of chlorinated alkanes to Chinese hamster ovary (CHO) cells was observed at concentrations similar to those that have been shown previously to be toxic to fish. Strong correlations exist between the acute in vitro toxicity of the chlorinated alkanes and (i) hydrophobicity [modeled by the calculated log K ow (octanol-water partition coefficient); r (2) = 0.883 and r int (2) = 0.854] and (ii) in vivo acute toxicity to fish ( r (2) = 0.758). A QSAR model has been developed to predict in vivo acute toxicity to fish, based on the in vitro data and even on in silico log K ow data only. The developed QSAR model is applicable to chlorinated alkanes with up to 10 carbon atoms, up to eight chlorine atoms, and log K ow values lying within the range from 1.71 to 5.70. Out of the 100204 compounds on the European Inventory of Existing Chemicals (EINECS), our QSAR model covers 77 (0.1%) of them. Our findings demonstrate that in vitro experiments and even in silico calculations can replace animal experiments in the prediction of the acute toxicity of chlorinated alkanes.

  7. Enhanced biodegradation of alkane hydrocarbons and crude oil by mixed strains and bacterial community analysis.

    PubMed

    Chen, Yu; Li, Chen; Zhou, Zhengxi; Wen, Jianping; You, Xueyi; Mao, Youzhi; Lu, Chunzhe; Huo, Guangxin; Jia, Xiaoqiang

    2014-04-01

    In this study, two strains, Acinetobacter sp. XM-02 and Pseudomonas sp. XM-01, were isolated from soil samples polluted by crude oil at Bohai offshore. The former one could degrade alkane hydrocarbons (crude oil and diesel, 1:4 (v/v)) and crude oil efficiently; the latter one failed to grow on alkane hydrocarbons but could produce rhamnolipid (a biosurfactant) with glycerol as sole carbon source. Compared with pure culture, mixed culture of the two strains showed higher capability in degrading alkane hydrocarbons and crude oil of which degradation rate were increased from 89.35 and 74.32 ± 4.09 to 97.41 and 87.29 ± 2.41 %, respectively. In the mixed culture, Acinetobacter sp. XM-02 grew fast with sufficient carbon source and produced intermediates which were subsequently utilized for the growth of Pseudomonas sp. XM-01 and then, rhamnolipid was produced by Pseudomonas sp. XM-01. Till the end of the process, Acinetobacter sp. XM-02 was inhibited by the rapid growth of Pseudomonas sp. XM-01. In addition, alkane hydrocarbon degradation rate of the mixed culture increased by 8.06 to 97.41 % compared with 87.29 % of the pure culture. The surface tension of medium dropping from 73.2 × 10(-3) to 28.6 × 10(-3) N/m. Based on newly found cooperation between the degrader and the coworking strain, rational investigations and optimal strategies to alkane hydrocarbons biodegradation were utilized for enhancing crude oil biodegradation. PMID:24532465

  8. Enhanced biodegradation of alkane hydrocarbons and crude oil by mixed strains and bacterial community analysis.

    PubMed

    Chen, Yu; Li, Chen; Zhou, Zhengxi; Wen, Jianping; You, Xueyi; Mao, Youzhi; Lu, Chunzhe; Huo, Guangxin; Jia, Xiaoqiang

    2014-04-01

    In this study, two strains, Acinetobacter sp. XM-02 and Pseudomonas sp. XM-01, were isolated from soil samples polluted by crude oil at Bohai offshore. The former one could degrade alkane hydrocarbons (crude oil and diesel, 1:4 (v/v)) and crude oil efficiently; the latter one failed to grow on alkane hydrocarbons but could produce rhamnolipid (a biosurfactant) with glycerol as sole carbon source. Compared with pure culture, mixed culture of the two strains showed higher capability in degrading alkane hydrocarbons and crude oil of which degradation rate were increased from 89.35 and 74.32 ± 4.09 to 97.41 and 87.29 ± 2.41 %, respectively. In the mixed culture, Acinetobacter sp. XM-02 grew fast with sufficient carbon source and produced intermediates which were subsequently utilized for the growth of Pseudomonas sp. XM-01 and then, rhamnolipid was produced by Pseudomonas sp. XM-01. Till the end of the process, Acinetobacter sp. XM-02 was inhibited by the rapid growth of Pseudomonas sp. XM-01. In addition, alkane hydrocarbon degradation rate of the mixed culture increased by 8.06 to 97.41 % compared with 87.29 % of the pure culture. The surface tension of medium dropping from 73.2 × 10(-3) to 28.6 × 10(-3) N/m. Based on newly found cooperation between the degrader and the coworking strain, rational investigations and optimal strategies to alkane hydrocarbons biodegradation were utilized for enhancing crude oil biodegradation.

  9. Microbial Communities in Methane- and Short Chain Alkane-Rich Hydrothermal Sediments of Guaymas Basin.

    PubMed

    Dowell, Frederick; Cardman, Zena; Dasarathy, Srishti; Kellermann, Matthias Y; Lipp, Julius S; Ruff, S Emil; Biddle, Jennifer F; McKay, Luke J; MacGregor, Barbara J; Lloyd, Karen G; Albert, Daniel B; Mendlovitz, Howard; Hinrichs, Kai-Uwe; Teske, Andreas

    2016-01-01

    The hydrothermal sediments of Guaymas Basin, an active spreading center in the Gulf of California (Mexico), are rich in porewater methane, short-chain alkanes, sulfate and sulfide, and provide a model system to explore habitat preferences of microorganisms, including sulfate-dependent, methane- and short chain alkane-oxidizing microbial communities. In this study, hot sediments (above 60°C) covered with sulfur-oxidizing microbial mats surrounding a hydrothermal mound (termed "Mat Mound") were characterized by porewater geochemistry of methane, C2-C6 short-chain alkanes, sulfate, sulfide, sulfate reduction rate measurements, in situ temperature gradients, bacterial and archaeal 16S rRNA gene clone libraries and V6 tag pyrosequencing. The most abundantly detected groups in the Mat mound sediments include anaerobic methane-oxidizing archaea of the ANME-1 lineage and its sister clade ANME-1Guaymas, the uncultured bacterial groups SEEP-SRB2 within the Deltaproteobacteria and the separately branching HotSeep-1 Group; these uncultured bacteria are candidates for sulfate-reducing alkane oxidation and for sulfate-reducing syntrophy with ANME archaea. The archaeal dataset indicates distinct habitat preferences for ANME-1, ANME-1-Guaymas, and ANME-2 archaea in Guaymas Basin hydrothermal sediments. The bacterial groups SEEP-SRB2 and HotSeep-1 co-occur with ANME-1 and ANME-1Guaymas in hydrothermally active sediments underneath microbial mats in Guaymas Basin. We propose the working hypothesis that this mixed bacterial and archaeal community catalyzes the oxidation of both methane and short-chain alkanes, and constitutes a microbial community signature that is characteristic for hydrothermal and/or cold seep sediments containing both substrates. PMID:26858698

  10. Microbial Communities in Methane- and Short Chain Alkane-Rich Hydrothermal Sediments of Guaymas Basin.

    PubMed

    Dowell, Frederick; Cardman, Zena; Dasarathy, Srishti; Kellermann, Matthias Y; Lipp, Julius S; Ruff, S Emil; Biddle, Jennifer F; McKay, Luke J; MacGregor, Barbara J; Lloyd, Karen G; Albert, Daniel B; Mendlovitz, Howard; Hinrichs, Kai-Uwe; Teske, Andreas

    2016-01-01

    The hydrothermal sediments of Guaymas Basin, an active spreading center in the Gulf of California (Mexico), are rich in porewater methane, short-chain alkanes, sulfate and sulfide, and provide a model system to explore habitat preferences of microorganisms, including sulfate-dependent, methane- and short chain alkane-oxidizing microbial communities. In this study, hot sediments (above 60°C) covered with sulfur-oxidizing microbial mats surrounding a hydrothermal mound (termed "Mat Mound") were characterized by porewater geochemistry of methane, C2-C6 short-chain alkanes, sulfate, sulfide, sulfate reduction rate measurements, in situ temperature gradients, bacterial and archaeal 16S rRNA gene clone libraries and V6 tag pyrosequencing. The most abundantly detected groups in the Mat mound sediments include anaerobic methane-oxidizing archaea of the ANME-1 lineage and its sister clade ANME-1Guaymas, the uncultured bacterial groups SEEP-SRB2 within the Deltaproteobacteria and the separately branching HotSeep-1 Group; these uncultured bacteria are candidates for sulfate-reducing alkane oxidation and for sulfate-reducing syntrophy with ANME archaea. The archaeal dataset indicates distinct habitat preferences for ANME-1, ANME-1-Guaymas, and ANME-2 archaea in Guaymas Basin hydrothermal sediments. The bacterial groups SEEP-SRB2 and HotSeep-1 co-occur with ANME-1 and ANME-1Guaymas in hydrothermally active sediments underneath microbial mats in Guaymas Basin. We propose the working hypothesis that this mixed bacterial and archaeal community catalyzes the oxidation of both methane and short-chain alkanes, and constitutes a microbial community signature that is characteristic for hydrothermal and/or cold seep sediments containing both substrates.

  11. Diverse Bacterial Groups Contribute to the Alkane Degradation Potential of Chronically Polluted Subantarctic Coastal Sediments.

    PubMed

    Guibert, Lilian M; Loviso, Claudia L; Borglin, Sharon; Jansson, Janet K; Dionisi, Hebe M; Lozada, Mariana

    2016-01-01

    We aimed to gain insight into the alkane degradation potential of microbial communities from chronically polluted sediments of a subantarctic coastal environment using a combination of metagenomic approaches. A total of 6178 sequences annotated as alkane-1-monooxygenases (EC 1.14.15.3) were retrieved from a shotgun metagenomic dataset that included two sites analyzed in triplicate. The majority of the sequences binned with AlkB described in Bacteroidetes (32 ± 13 %) or Proteobacteria (29 ± 7 %), although a large proportion remained unclassified at the phylum level. Operational taxonomic unit (OTU)-based analyses showed small differences in AlkB distribution among samples that could be correlated with alkane concentrations, as well as with site-specific variations in pH and salinity. A number of low-abundance OTUs, mostly affiliated with Actinobacterial sequences, were found to be only present in the most contaminated samples. On the other hand, the molecular screening of a large-insert metagenomic library of intertidal sediments from one of the sampling sites identified two genomic fragments containing novel alkB gene sequences, as well as various contiguous genes related to lipid metabolism. Both genomic fragments were affiliated with the phylum Planctomycetes, and one could be further assigned to the genus Rhodopirellula due to the presence of a partial sequence of the 23S ribosomal RNA (rRNA) gene. This work highlights the diversity of bacterial groups contributing to the alkane degradation potential and reveals patterns of functional diversity in relation with environmental stressors in a chronically polluted, high-latitude coastal environment. In addition, alkane biodegradation genes are described for the first time in members of Planctomycetes.

  12. Microbial Communities in Methane- and Short Chain Alkane-Rich Hydrothermal Sediments of Guaymas Basin

    PubMed Central

    Dowell, Frederick; Cardman, Zena; Dasarathy, Srishti; Kellermann, Matthias Y.; Lipp, Julius S.; Ruff, S. Emil; Biddle, Jennifer F.; McKay, Luke J.; MacGregor, Barbara J.; Lloyd, Karen G.; Albert, Daniel B.; Mendlovitz, Howard; Hinrichs, Kai-Uwe; Teske, Andreas

    2016-01-01

    The hydrothermal sediments of Guaymas Basin, an active spreading center in the Gulf of California (Mexico), are rich in porewater methane, short-chain alkanes, sulfate and sulfide, and provide a model system to explore habitat preferences of microorganisms, including sulfate-dependent, methane- and short chain alkane-oxidizing microbial communities. In this study, hot sediments (above 60°C) covered with sulfur-oxidizing microbial mats surrounding a hydrothermal mound (termed “Mat Mound”) were characterized by porewater geochemistry of methane, C2–C6 short-chain alkanes, sulfate, sulfide, sulfate reduction rate measurements, in situ temperature gradients, bacterial and archaeal 16S rRNA gene clone libraries and V6 tag pyrosequencing. The most abundantly detected groups in the Mat mound sediments include anaerobic methane-oxidizing archaea of the ANME-1 lineage and its sister clade ANME-1Guaymas, the uncultured bacterial groups SEEP-SRB2 within the Deltaproteobacteria and the separately branching HotSeep-1 Group; these uncultured bacteria are candidates for sulfate-reducing alkane oxidation and for sulfate-reducing syntrophy with ANME archaea. The archaeal dataset indicates distinct habitat preferences for ANME-1, ANME-1-Guaymas, and ANME-2 archaea in Guaymas Basin hydrothermal sediments. The bacterial groups SEEP-SRB2 and HotSeep-1 co-occur with ANME-1 and ANME-1Guaymas in hydrothermally active sediments underneath microbial mats in Guaymas Basin. We propose the working hypothesis that this mixed bacterial and archaeal community catalyzes the oxidation of both methane and short-chain alkanes, and constitutes a microbial community signature that is characteristic for hydrothermal and/or cold seep sediments containing both substrates. PMID:26858698

  13. Chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.

    1992-01-01

    Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

  14. Trace Chemistry

    NASA Technical Reports Server (NTRS)

    Radhakrishnan, Krishnan; Whitefield, Philip

    1999-01-01

    The goals of the trace chemistry group were to identify the processes relevant to aerosol and aerosol precursor formation occurring within aircraft gas turbine engines; that is, within the combustor, turbine, and nozzle. The topics of discussion focused on whether the chemistry of aerosol formation is homogeneous or heterogeneous; what species are important for aerosol and aerosol precursor formation; what modeling/theoretical activities to pursue; what experiments to carry out that both support modeling activities and elucidate fundamental processes; and the role of particulates in aerosol and aerosol precursor formation. The consensus of the group was that attention should be focused on SO2, SO3, and aerosols. Of immediate concern is the measurement of the concentration of the species SO3, SO2, H2SO4 OH, HO2, H2O2, O, NO, NO2, HONO, HNO3, CO, and CO2 and particulates in various engines, both those currently in use and those in development. The recommendation was that concentration measurements should be made at both the combustor exit and the engine exit. At each location the above species were classified into one of four categories of decreasing importance, Priority I through IV, as follows: Combustor exit: Priority I species - SO3:SO2 ratio, SO3, SO2, and particulates; Priority II species: OH and O; Priority III species - NO and NO2; and Priority IV species - CO and CO2. For the Engine exit: Priority I species - SO3:SO2 ratio, SO3, SO2,H2SO4, and particulates; Priority II species: OH,HO2, H2O2, and O; Priority III species - NO, NO2, HONO, and HNO3; and Priority IV species - CO and CO2. Table I summarizes the anticipated concentration range of each of these species. For particulate matter, the quantities of interest are the number density, size distribution, and composition. In order to provide data for validating multidimensional reacting flow models, it would be desirable to make 2-D, time-resolved measurements of the concentrations of the above species and

  15. Involvement of an Alkane Hydroxylase System of Gordonia sp. Strain SoCg in Degradation of Solid n-Alkanes▿

    PubMed Central

    Lo Piccolo, Luca; De Pasquale, Claudio; Fodale, Roberta; Puglia, Anna Maria; Quatrini, Paola

    2011-01-01

    Enzymes involved in oxidation of long-chain n-alkanes are still not well known, especially those in Gram-positive bacteria. This work describes the alkane degradation system of the n-alkane degrader actinobacterium Gordonia sp. strain SoCg, which is able to grow on n-alkanes from dodecane (C12) to hexatriacontane (C36) as the sole C source. SoCg harbors in its chromosome a single alk locus carrying six open reading frames (ORFs), which shows 78 to 79% identity with the alkane hydroxylase (AH)-encoding systems of other alkane-degrading actinobacteria. Quantitative reverse transcription-PCR showed that the genes encoding AlkB (alkane 1-monooxygenase), RubA3 (rubredoxin), RubA4 (rubredoxin), and RubB (rubredoxin reductase) were induced by both n-hexadecane and n-triacontane, which were chosen as representative long-chain liquid and solid n-alkane molecules, respectively. Biotransformation of n-hexadecane into the corresponding 1-hexadecanol was detected by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME/GC-MS) analysis. The Gordonia SoCg alkB was heterologously expressed in Escherichia coli BL21 and in Streptomyces coelicolor M145, and both hosts acquired the ability to transform n-hexadecane into 1-hexadecanol, but the corresponding long-chain alcohol was never detected on n-triacontane. However, the recombinant S. coelicolor M145-AH, expressing the Gordonia alkB gene, was able to grow on n-triacontane as the sole C source. A SoCg alkB disruption mutant that is completely unable to grow on n-triacontane was obtained, demonstrating the role of an AlkB-type AH system in degradation of solid n-alkanes. PMID:21183636

  16. Biotechnology of biomass conversion

    SciTech Connect

    Wayman, M.; Parekh, S.R.

    1990-01-01

    This book covers: An introduction to biomass crops; The microbiology of fermentation processes; The production of ethanol from biomass crops, such as sugar cane and rubbers; The energy of biomass conversion; and The economics of biomass conversion.

  17. PEROXYNITRITE CHEMISTRY

    SciTech Connect

    Lymar, S.V.

    2000-11-29

    This century old area of research has been experiencing a renaissance during the last decade, with the annual number of publications on the subject increasing from only one in 1990 to nearly 200 in the late-1990s. This renewed interest is stimulated by the discovery of biological roles of nitric oxide, distinguished by the 1998 Nobel prize, and the recognition that the conversion of nitric oxide into peroxynitrite may play major roles in human diseases associated with oxidative stress and in cellular defense against invading pathogens. Peroxynitrite (ONOO{sup {minus}})is a structural isomer of nitrate (NO{sub 3}{sup {minus}}) that contains a peroxo bond. The physiological route to ONOO{sup {minus}} is provided by the combination of nitric oxide ({center_dot}NO) with superoxide ({center_dot}O{sub 2}{sup {minus}}), an extremely rapid reaction occurring upon every encounter of these radicals (the upper dot denotes radical species). Both {center_dot}NO and {center_dot}O{sub 2}{sup {minus}} are the oxygen metabolic products simultaneously generated in a number of cell types within a human body. Compared to its precursors, peroxynitrite is a much stronger oxidant capable of oxidizing proteins, nucleic acids, and lipids.

  18. Synthetic studies in nitrogen chemistry

    SciTech Connect

    Wu, J.

    1992-01-01

    N,N-Bis(benzotriazolylmethyl)arylamines were obtained quantitatively from mixtures of benzotriazole, formaldehyde and the corresponding arylamine in refluxing toluene with azeotropic removal of water. Treatment of these adducts with Grignard reagents or sodium borohydride afforded symmetrically substituted N,N-dialkylarylamines in high yields. Unsymmetrically substituted N,N-dialkylarylamines could also be obtained by similar stepwise procedures. Sterically hindered N,N-bis(sec-butyl)arylamines were prepared by alkylations of the anions of the corresponding arylamines with 2-iodobutane. Chlorosulfonation of 2-nitroanisole gave 4-methoxy-3-nitrobenzene-sulfon-yl chloride, which was converted with N-butyl-(3-phenylpropyl)-amine into the corresponding benzenesulfonamide. Hydrolysis of the methoxy group and reduction of the nitro substituent of this benzene-sulfonamide, followed by diazotization and coupling with 2-naphthol, afforded N-butyl-N-(3-phenylpropyl)-4-hydroxy-3-(2-hydroxy-1-naphthyl)azobenzenesulfonamide. Medium-sized (7 and 8) benzosultams were synthesized by Friedel-Crafts cyclizations of w-phenylaklanesulfamoyl chlorides. New (benzotriazol-1-y)methyl derivatives of type Bt(1)CH[sub 2] X [Bt(1) = benzotriazol-1-yl] were prepared. [alpha]-(Benzotriazol-1-yl)acetophenone was converted to a number of interesting derivatives. Lithiation of 1-methylbenzotriazole followed by treatments with electrophiles gave various [alpha]-substituted 1-methylbenzotriazoles. Simple treatments of 2-alkylbenzotriazoles by LDA gave symmetrical [alpha],[beta]-bis-(benzotriazol-2-yl)alkanes sterospecifically as the [alpha],[alpha]-coupled products in high yields. A molecule [Bt(2)CH(CH[sub 3])CH(CH[sub 3])CH(CH[sub 3])CH(CH[sub 3])Bt(2)] [Bt(2) = benzotriazole-2-yl] with four asymmetric centers derived from four molecules of 2-ethylbenzotriazole was obtained as a single isomer. A new radical mechanism was first proposed to account for the chemistry of 2-alkylbenzotriazoles.

  19. Multimetallic catalysed radical oxidative C(sp3)–H/C(sp)–H cross-coupling between unactivated alkanes and terminal alkynes

    PubMed Central

    Tang, Shan; Wang, Pan; Li, Haoran; Lei, Aiwen

    2016-01-01

    Radical involved transformations are now considered as extremely important processes in modern organic synthetic chemistry. According to the demand by atom-economic and sustainable chemistry, direct C(sp3)–H functionalization through radical oxidative coupling represents an appealing strategy for C–C bond formations. However, the selectivity control of reactive radical intermediates is still a great challenge in these transformations. Here we show a selective radical oxidative C(sp3)–H/C(sp)–H cross-coupling of unactivated alkanes with terminal alkynes by using a combined Cu/Ni/Ag catalytic system. It provides a new way to access substituted alkynes from readily available materials. Preliminary mechanistic studies suggest that this reaction proceeds through a radical process and the C(sp3)–H bond cleavage is the rate-limiting step. This study may have significant implications for controlling selective C–C bond formation of reactive radical intermediates by using multimetallic catalytic systems. PMID:27339161

  20. Direct Conversion of Energy.

    ERIC Educational Resources Information Center

    Corliss, William R.

    This publication is one of a series of information booklets for the general public published by the United States Atomic Energy Commission. Direct energy conversion involves energy transformation without moving parts. The concepts of direct and dynamic energy conversion plus the laws governing energy conversion are investigated. Among the topics…

  1. Impact of chamber wall loss of gaseous organic compounds on secondary organic aerosol formation: Explicit modeling of SOA formation from alkane and alkene oxidation

    DOE PAGES

    La, Y. S.; Camredon, M.; Ziemann, P. J.; Valorso, R.; Matsunaga, A.; Lannuque, V.; Lee-Taylor, J.; Hodzic, A.; Madronich, S.; Aumont, B.

    2016-02-08

    Recent studies have shown that low volatility gas-phase species can be lost onto the smog chamber wall surfaces. Although this loss of organic vapors to walls could be substantial during experiments, its effect on secondary organic aerosol (SOA) formation has not been well characterized and quantified yet. Here the potential impact of chamber walls on the loss of gaseous organic species and SOA formation has been explored using the Generator for Explicit Chemistry and Kinetics of the Organics in the Atmosphere (GECKO-A) modeling tool, which explicitly represents SOA formation and gas–wall partitioning. The model was compared with 41 smog chambermore » experiments of SOA formation under OH oxidation of alkane and alkene series (linear, cyclic and C12-branched alkanes and terminal, internal and 2-methyl alkenes with 7 to 17 carbon atoms) under high NOx conditions. Simulated trends match observed trends within and between homologous series. The loss of organic vapors to the chamber walls is found to affect SOA yields as well as the composition of the gas and the particle phases. Simulated distributions of the species in various phases suggest that nitrates, hydroxynitrates and carbonylesters could substantially be lost onto walls. The extent of this process depends on the rate of gas–wall mass transfer, the vapor pressure of the species and the duration of the experiments. Furthermore, this work suggests that SOA yields inferred from chamber experiments could be underestimated up a factor of 2 due to the loss of organic vapors to chamber walls.« less

  2. The Role of Water Chemistry in Marine Aquarium Design: A Model System for a General Chemistry Class

    NASA Astrophysics Data System (ADS)

    Keaffaber, Jeffrey J.; Palma, Ramiro; Williams, Kathryn R.

    2008-02-01

    Water chemistry is central to aquarium design, and it provides many potential applications for discussion in undergraduate chemistry and engineering courses. Marine aquaria and their life support systems feature many chemical processes. A life support system consists of the entire recirculation system, as well as the habitat tank and all ancillary water treatment processes. Many fundamental concepts learned in general chemistry, for example, unit conversion, solution concentrations, stoichiometry, redox reactions, and acid-base chemistry are all key to understanding the life support system. This article uses a hypothetical tank to house ocean sunfish as a model to show students the calculations and other considerations that are needed when designing a marine aquarium.

  3. Energy conversion & storage program. 1995 annual report

    SciTech Connect

    Cairns, E.J.

    1996-06-01

    The 1995 annual report discusses laboratory activities in the Energy Conversion and Storage (EC&S) Program. The report is divided into three categories: electrochemistry, chemical applications, and material applications. Research performed in each category during 1995 is described. Specific research topics relate to the development of high-performance rechargeable batteries and fuel cells, the development of high-efficiency thermochemical processes for energy conversion, the characterization of new chemical processes and complex chemical species, and the study and application of novel materials related to energy conversion and transmission. Research projects focus on transport-process principles, chemical kinetics, thermodynamics, separation processes, organic and physical chemistry, novel materials and deposition technologies, and advanced methods of analysis.

  4. Static conversion systems

    NASA Astrophysics Data System (ADS)

    Ewell, R.; Mondt, J.

    Historically, all space power systems that have actually flown in space have relied on static energy conversion technology. Thus, static conversion is being considered for space nuclear power systems as well. There are four potential static conversion technologies which should be considered. These include: the alkali metal thermoelectric converter (AMTEC), the thermionic converter, the thermoelectric converter, and the thermophotovoltaic converter (TPV). These four conversion technologies will be described in brief detail along with their current status and development needs. In addition, the systems implications of using each of these conversion technologies with a space nuclear reactor power system will be evaluated and some comparisons made.

  5. Changes in the concentration and relative abundance of alkanes and PAHs from the Deepwater Horizon oiling of coastal marshes.

    PubMed

    Turner, R E; Overton, E B; Meyer, B M; Miles, M S; Hooper-Bui, L

    2014-09-15

    We determined changes of 28 alkanes and 43 different PAHs in 418 wetland soil samples collected on ten sampling trips to three Louisiana estuaries before and after they were oiled from the 2010 Deepwater Horizon disaster. There was a significant decline in 22 of the 28 alkane analytes (0.42% day(-1)), no change in 6, over 2.5 years. The concentration of five aromatic petroleum hydrocarbons (PAHs) increased (range 0.25-0.70% day(-1)), whereas the total PAH pool did not change. Of these five, naphthalene and C-1-naphthalenes are suggested to be of higher toxicity than the other three because of their relatively higher volatility or solubility. The relative proportions of alkane analytes, but not PAHs, does not yet resemble that in the pre-oiled marshes after 3 years, The trajectories of nine indicators for degradation/weathering were either inconclusive or misleading (alkanes) or confirmed the relatively meager degradation of PAHs. PMID:25127500

  6. Particle size distribution of n-alkanes nda Pb-210 in aerosols off the coast of Peru

    NASA Astrophysics Data System (ADS)

    Schneider, J. K.; Gagosian, R. B.; Cochran, J. K.; Trull, T. W.

    1983-08-01

    The results of particle size distributions measurements of aliphatic hydrocarbons and Pb-210 in aerosols in the upwelling zone off the Peruvian coast are reported. The data were taken as part of the Sea/Air Exchange Program (Searex) using cascade impactor samples on ships cruising 10-100 km off the coast. The samplers were situated on masts on the bow of the ship, which was steered into the wind, with samples taken only when the wind speeds exceeded 5 m/sec. The dominant aliphatic hydrocarbon fraction was n-alkanes above C20, and n-alkane concentrations were calculated as a function of the carbon number. Increasing Pb-210 concentrations were observed with decreasing particle size, a similar situation to that of the n-alkanes. It is suggested that the particle size distribution characteristics are due to fossil fuel combustion and gas-particle partitioning of the n-alkanes.

  7. Chemistry Rocks: Redox Chemistry as a Geologic Tool.

    ERIC Educational Resources Information Center

    Burns, Mary Sue

    2001-01-01

    Applies chemistry to earth science, uses rocks in chemistry laboratories, and teaches about transition metal chemistry, oxidation states, and oxidation-reduction reactions from firsthand experiences. (YDS)

  8. Revisiting Mt. Kilimanjaro: Do n-alkane biomarkers in soils reflect the δ2H isotopic composition of precipitation?

    NASA Astrophysics Data System (ADS)

    Zech, M.; Zech, R.; Rozanski, K.; Hemp, A.; Gleixner, G.; Zech, W.

    2014-06-01

    During the last decade compound-specific deuterium (δ2H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect δ2H of precipitation (δ2Hprec). Recently, several authors suggested that δ2H of n-alkanes (δ2H,sub>n-alkanes) can also be used as proxy in paleoaltimetry studies. Here we present results from a δ2H transect study (~1500 to 4000 m a.s.l.) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in δ2Hprec is present above ~2000 m a.s.l., i.e. δ2Hprec values become more negative with increasing altitude. The compound-specific δ2H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our δ2Hn-alkane results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro (Peterse et al., 2009, BG, 6, 2799-2807), a major re-interpretation is required given that the δ2Hn-alkane results do not reflect the δ2Hprec results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% at ~ 2000 m a.s.l. to 51% at 4000 m a.s.l.), strongly controls δ2Hleaf water. The modelled δ2H leaf water enrichment along the altitudinal transect matches well the measured 2H leaf water enrichment as assessed by using the δ2Hprec and δ2Hn-alkane results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect δ2Hprec but rather δ2

  9. Anaerobic oxidation of short-chain alkanes in hydrothermal sediments: potential influences on sulfur cycling and microbial diversity

    PubMed Central

    Adams, Melissa M.; Hoarfrost, Adrienne L.; Bose, Arpita; Joye, Samantha B.; Girguis, Peter R.

    2013-01-01

    Short-chain alkanes play a substantial role in carbon and sulfur cycling at hydrocarbon-rich environments globally, yet few studies have examined the metabolism of ethane (C2), propane (C3), and butane (C4) in anoxic sediments in contrast to methane (C1). In hydrothermal vent systems, short-chain alkanes are formed over relatively short geological time scales via thermogenic processes and often exist at high concentrations. The sediment-covered hydrothermal vent systems at Middle Valley (MV, Juan de Fuca Ridge) are an ideal site for investigating the anaerobic oxidation of C1–C4 alkanes, given the elevated temperatures and dissolved hydrocarbon species characteristic of these metalliferous sediments. We examined whether MV microbial communities oxidized C1–C4 alkanes under mesophilic to thermophilic sulfate-reducing conditions. Here we present data from discrete temperature (25, 55, and 75°C) anaerobic batch reactor incubations of MV sediments supplemented with individual alkanes. Co-registered alkane consumption and sulfate reduction (SR) measurements provide clear evidence for C1–C4 alkane oxidation linked to SR over time and across temperatures. In these anaerobic batch reactor sediments, 16S ribosomal RNA pyrosequencing revealed that Deltaproteobacteria, particularly a novel sulfate-reducing lineage, were the likely phylotypes mediating the oxidation of C2–C4 alkanes. Maximum C1–C4 alkane oxidation rates occurred at 55°C, which reflects the mid-core sediment temperature profile and corroborates previous studies of rate maxima for the anaerobic oxidation of methane (AOM). Of the alkanes investigated, C3 was oxidized at the highest rate over time, then C4, C2, and C1, respectively. The implications of these results are discussed with respect to the potential competition between the anaerobic oxidation of C2–C4alkanes with AOM for available oxidants and the influence on the fate of C1 derived from these hydrothermal systems. PMID:23717305

  10. Molecular mobility depending on chain length and thermally induced molecular motion of n-alkane/urea inclusion compounds

    NASA Astrophysics Data System (ADS)

    Nakaoki, Takahiko; Nagano, Hiromasa; Yanagida, Toshinori

    2004-08-01

    Solid-state high resolution 13C NMR was used to analyze the end group conformation and molecular mobility of n-alkanes in a urea host as a function of the carbon number of the n-alkane. It was shown that the chemical shift of the inner methylenes could be interpreted by the γ- gauche effect. Of further interest is our finding that the chemical shift of 3-methylene is independent of both chain length and temperature, a result indicating that the torsional rotation of the bond ω 3 between the 4-methylene and 5-methylene carbons is so inhibited that there is little gauche conformation. The chemical shift of the inner methylenes indicated a different tendency between the even- and the odd-numbered n-alkanes. The fact that the signals of the even-numbered n-alkanes were observed at a comparatively more upfield location than those of the odd-numbered ones indicated that the even-numbered n-alkane had a higher molecular mobility and tended to adopt a more gauche conformation. The decomposition temperature obtained by thermal analysis also suggested a difference between the even- and odd-numbered n-alkanes. The decomposition temperature of the even-numbered n-alkane/urea inclusion compounds was a little lower than that of the odd-numbered ones, a disparity corresponding to the higher molecular mobility of the n-alkane in the urea host. The spin-lattice relaxation time ( T1C) increased with increasing chain length for chains with less than the 14 carbon atoms but reached a constant value for all longer chains. This result is completely different from that for the n-alkane crystal, which gave a longer T1C depending on the chain length, and can be explained by a reduced intermolecular interaction between the n-alkane and the urea host. Clearly, T1C measurements can be applied to confirm the formation of inclusion compounds. However, the different T1C values between the methyl, 2-, 3-, and inner methylene carbons indicates that the n-alkane molecule does not rotate so fast

  11. n-Alkane biosynthetic hydrogen isotope fractionation is not constant throughout the growing season in the riparian tree Salix viminalis

    NASA Astrophysics Data System (ADS)

    Newberry, Sarah L.; Kahmen, Ansgar; Dennis, Paul; Grant, Alastair

    2015-09-01

    Compound-specific δ2H values of leaf wax n-alkanes have emerged as a potentially powerful paleohydrological proxy. Research suggests terrestrial plant n-alkane δ2H values are strongly correlated with meteoric water δ2H values, and may provide information on temperature, relative humidity, evaporation, and precipitation. This is based upon several assumptions, including that biosynthetic fractionation of n-alkanes during synthesis is constant within a single species. Here we present a multi-isotope study of the n-alkanes of riparian Salix viminalis growing in Norwich, UK. We measured n-alkane δ2H, leaf water δ2H, xylem water δ2H, and bulk foliar δ13C and evaluated the variability of n-alkane δ2H values and net biosynthetic fractionation (εlw-wax) over a whole growing season. S. viminalis n-alkane δ2H values decreased by 40‰ between the start of the growing season in April and the time when they stabilized in July. Variation in leaf and xylem water δ2H did not explain this variability. εlw-wax varied from -116‰ during leaf expansion in April to -156‰ during the stable phase. This suggests that differential biosynthetic fractionation was responsible for the strong seasonal trends in S. viminalis n-alkane δ2H values. We suggest that variability in εlw-wax is driven by seasonal differences in the carbohydrate source and thus the NADPH used in n-alkane biosynthesis, with stored carbohydrates utilized during spring and recent occurring growing season assimilates used later in the season. This is further supported by bulk foliar δ13C values, which are 13C-enriched during the period of leaf flush, relative to the end of the growing season. Our results challenge the assumption that biosynthetic fractionation is constant for a given species, and suggest that 2H-enriched stored assimilates are an important source for n-alkane biosynthesis early in the growing season. These findings have implications for the interpretation of sedimentary n-alkanes and call

  12. Liquid-vapor equilibria and interfacial properties of n-alkanes and perfluoroalkanes by molecular simulation.

    PubMed

    Amat, Miguel A; Rutledge, Gregory C

    2010-03-21

    A molecular dynamics study is presented to assess the performance of a united-atom model in the prediction of liquid-vapor interfacial properties for short-chain perfluoroalkanes and their alkane counterparts. In particular, the ability of this model to discriminate between the surface-energy values of these two types of compounds was investigated over a wide temperature range corresponding to the liquid-vapor region. Comparisons with available experimental data and surface-tension predictions given by other force-field parameterizations, including those based on the more computationally demanding all-atom method, were performed to gauge the viability of this model. It was found that the model used in this study captures qualitatively the expected behavior of surface energy between alkanes and perfluoroalkanes and yields values that are in excellent agreement with experimental data, especially in the high-temperature limit as the critical temperature is approached. PMID:20331313

  13. Liquid-vapor equilibria and interfacial properties of n-alkanes and perfluoroalkanes by molecular simulation

    NASA Astrophysics Data System (ADS)

    Amat, Miguel A.; Rutledge, Gregory C.

    2010-03-01

    A molecular dynamics study is presented to assess the performance of a united-atom model in the prediction of liquid-vapor interfacial properties for short-chain perfluoroalkanes and their alkane counterparts. In particular, the ability of this model to discriminate between the surface-energy values of these two types of compounds was investigated over a wide temperature range corresponding to the liquid-vapor region. Comparisons with available experimental data and surface-tension predictions given by other force-field parameterizations, including those based on the more computationally demanding all-atom method, were performed to gauge the viability of this model. It was found that the model used in this study captures qualitatively the expected behavior of surface energy between alkanes and perfluoroalkanes and yields values that are in excellent agreement with experimental data, especially in the high-temperature limit as the critical temperature is approached.

  14. Structural transformations of even-numbered n-alkanes confined in mesopores

    SciTech Connect

    Huber, P.; Soprunyuk, V. P.; Knorr, K.

    2006-09-15

    The n-alkanes C{sub 12}H{sub 26}, C{sub 14}H{sub 30}, and C{sub 16}H{sub 34} have been imbibed and solidified in mesoporous Vycor glass with a mean pore diameter of 10 nm. The samples have been investigated by x-ray diffractometry and calorimetric measurements. The structures and phase sequences have been determined. Apart from a reduction and the hysteresis of the melting-freezing transition, pore-confined C12 reproduces the liquid-triclinic phase sequence of the bulk material, but for C16 an orthorhombic rotator mesophase appears that in the bulk state is absent for C16 but well known from odd-numbered alkanes of similar length. In pore-confined C14 this phase shows up on cooling but not on heating.

  15. An ESR and NMR study of the radiolysis of n-alkanes: Crystal structure dependence

    NASA Astrophysics Data System (ADS)

    Toriyama, K.; Okazaki, M.; Nunome, K.; Matsuura, K.

    The process of radiation damage for long-chain n-alkanes was investigated to elucidate that for polyethylene. Chain-end alkyl radicals were preferentially formed not only through primary C-H scission but also through a hydrogen atom reaction in odd- n-alkane, as was shown by analysis of the ESR spectra for isotopic mixtures of tridecane- h28/tridecane- d28 and nonadecane- h40/nonadecane- d40. To elucidate the mode of alkyl radical migration in solids through intermolecular hydrogen atom abstraction, D/H exchange was detected in mixed crystals of eicosane- d42/eicosane- h42. The chain-end region was found to be more reactive than the inner region for radical site migration. In addition, formation of a microscopic amorphous island by destruction of the crystal lattice was also detected. The influences of molecular packing were large in all cases.

  16. Fossil Leaves and Fossil Leaf n-Alkanes: Reconstructing the First Closed Canopied Rainforests

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2013-12-01

    Although the age and location is disputed, the rise of the first closed-canopy forest is likely linked with the expansion of angiosperms in the late Cretacous or early Cenozoic. The carbon isotope 'canopy effect' reflects the extent of canopy closure, and is well documented in δ13C values of the leaves and leaf lipids in modern forests. To test the extent of canopy closure among the oldest documented angiosperm tropical forests, we analyzed isotopic characteristics of leaf fossils and leaf waxes from the Guaduas and Cerrejón Formations. The Guaduas Fm. (Maastrichtian) contains some of the earliest angiosperm fossils in the Neotropics, and both leaf morphology and pollen records at this site suggest an open-canopy structure. The Cerrejón Fm. (Paleocene) contains what are believed to be the first recorded fossil leaves from a closed-canopy forest. We analyzed the bulk carbon isotope content (δ13Cleaf) of 199 fossil leaves, as well as the n-alkane concentration and chain-length distribution, and δ13C of alkanes (δ13Clipid) of 73 fossil leaves and adjacent sediment samples. Fossil leaves are dominated by eudicots and include ten modern plant families (Apocynaceae, Bombaceae, Euphorbaceae, Fabaceae, Lauraceae, Malvaceae, Meliaceae, Menispermaceae, Moraceae, Sapotaceae). We interpreted extent of canopy coverage based on the range of δ13Cleaf values. The narrow range of δ13C values in leaves from the Guaduas Fm (2.7‰) is consistent with an open canopy. A significantly wider range in values (6.3‰) suggests a closed-canopy signature for site 0315 of the Cerrejón Fm,. In contrast, at Site 0318, a lacustrine deposit, leaves had a narrow range (3.3‰) in δ13C values, and this is not consistent with a closed-canopy, but is consistent with leaf assemblages from a forest edge. Leaves that accumulate in lake sediments tend to be biased toward plants living at the lake edge, which do not experience closed-canopy conditions, and do not express the isotopic

  17. Microwave synthesis of CdSe and CdTe nanocrystals in nonabsorbing alkanes.

    PubMed

    Washington, Aaron L; Strouse, Geoffrey F

    2008-07-16

    Controlling nanomaterial growth via the "specific microwave effect" can be achieved by selective heating of the chalcogenide precursor. The high polarizability of the precursor allows instantaneous activation and subsequent nucleation leading to the synthesis of CdSe and CdTe in nonmicrowave absorbing alkane solvents. Regardless of the desired size, narrow dispersity nanocrystals can be isolated in less than 3 min with high quantum efficiencies and elliptical morphologies. The reaction does not require a high temperature injection step, and the alkane solvent can be easily removed. In addition, batch-to-batch variance in size is 4.2 +/- 0.14 nm for 10 repeat experimental runs. The use of a stopped-flow reactor allows near continuous automation of the process leading to potential industrial benefits.

  18. Condensation of a supersaturated vapor. XII. The homogeneous nucleation of the n-alkanes

    NASA Astrophysics Data System (ADS)

    Rudek, Markus M.; Fisk, Jeffery A.; Chakarov, Vasil M.; Katz, Joseph L.

    1996-09-01

    Homogeneous nucleation rates as functions of both supersaturation and temperature were measured in an upward thermal diffusion cloud chamber for four n-alkanes: n-heptane, n-octane, n-nonane, and n-decane. Nucleation rates from about 10-4 to 5×100 drops cm-3 s-1 were obtained in the temperature range, 241 to 330 K. Their dependences on supersaturation and temperature were compared to predictions of several nucleation theories: the internally consistent Classical theory, two versions of the Kalikmanov-van Dongen theory, and the Delale-Meier theory. Each theory predicted the dependence of the nucleation rate on supersaturation reasonably well. However, large temperature dependent correction factors were needed for quantitative agreement between measured and predicted nucleation rates. A plot of the ratio of measured to predicted nucleation rates vs reduced temperature shows that all n-alkanes investigated can be represented to within a factor of ten by a single, best fit line.

  19. Crossed-beam DC slice imaging of fluorine atom reactions with linear alkanes

    SciTech Connect

    Shi, Yuanyuan; Kamasah, Alexander; Joalland, Baptiste; Suits, Arthur G.

    2015-05-14

    We report the reaction dynamics of F atom with selected alkanes studied by crossed beam scattering with DC slice ion imaging. The target alkanes are propane, n-butane, and n-pentane. The product alkyl radicals are probed by 157 nm single photon ionization following reaction at a collision energy of ∼10 kcal mol{sup −1}. The analyzed data are compared with the corresponding theoretical studies. Reduced translational energy distributions for each system show similar trends with little of the reaction exoergicity appearing in translation. However, the pentane reaction shows a somewhat smaller fraction of available energy in translation than the other two, suggesting greater energy channeled into pentyl internal degrees of freedom. The center-of-mass angular distributions all show backscattering as well as sharp forward scattering that decreases in relative intensity with the size of the molecule. Possible reasons for these trends are discussed.

  20. Comparison of bulk and n-alkane PETM carbon isotope trends from the Bighorn Basin, Wyoming

    NASA Astrophysics Data System (ADS)

    Baczynski, A. A.; McInerney, F. A.; Kraus, M. J.; Wing, S.

    2010-12-01

    The Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt, short-term, and large-scale global warming fueled by a large release of isotopically light carbon, is recorded in terrestrial and marine carbonates and organic carbon as a prominent negative carbon isotope excursion (CIE). Here we present a composite stable carbon isotope record from n-alkanes and four bulk organic carbon records from individual sections spanning the PETM interval in the Cabin Fork area of the southeastern Bighorn Basin, Wyoming. The n-alkane curve shows an abrupt, negative shift in δ13C values, an extended CIE body, and a rapid recovery to pre-PETM δ13C values. While the bulk organic carbon records show similarly abrupt negative shifts in δ13C values, the CIE appears to be compressed as well as smaller in magnitude, and the return to more positive δ13C values is often more gradual. Furthermore, the stratigraphic thickness of the most negative CIE values and the pattern of the recovery phase are not consistent among the four bulk organic carbon records. The discrepancy between the bulk organic matter and n-alkane CIE may arise because of changes in soil organic matter cycling during the PETM. Bulk soil organic matter δ13C values are influenced by degradation and selective preservation whereas n-alkanes are resistant to diagenesis. Variations in sediment accumulation rates across the basin may be responsible for the differences between the four bulk organic carbon δ13C records. Sites with extended CIE bodies likely present more complete isotope records with greater time resolution and less time averaging than those with reduced CIEs. The shape of the high-resolution n-alkane curve presented here is similar to the newest 3He-based timescale for the PETM using data from Walvis Ridge, IODP site 1266 (Murphy et al., 2010). The most significant difference between this revised PETM timescale and previously published age models is the allocation of time within the PETM event. Murphy et

  1. Adsorption layer properties of alkyltrimethylammonium bromides at interfaces between water and different alkanes.

    PubMed

    Mucic, N; Kovalchuk, N M; Aksenenko, E V; Fainerman, V B; Miller, R

    2013-11-15

    We measured the interfacial tensions of aqueous solutions against different oil phases using drop profile analysis tensiometry (PAT-1, Sinterface Technologies, Germany) for decyl- and dodecyltrimethylammonium bromide (C10TAB and C12TAB) in phosphate buffer (10 mM, pH7). The following alkanes were used as oil phases: hexane, heptane, octane, nonane, decane, dodecane and tetradecane. The obtained equilibrium interfacial tension isotherms were fitted by the Frumkin Ionic Compressibility model (FIC). The surfactants adsorb at the water/oil interface in competition with the oil molecules. At high surfactant surface coverage this competitive adsorption is manifested in two ways. First, for short chain surfactants, the oil molecules are embedded into the adsorption layer. Second, for long chain surfactants, the short alkane chains of the oil molecules are squeezed out from the adsorption layer due to strong mutual interaction between surfactants' chains. PMID:24011787

  2. Microwave synthesis of CdSe and CdTe nanocrystals in nonabsorbing alkanes.

    PubMed

    Washington, Aaron L; Strouse, Geoffrey F

    2008-07-16

    Controlling nanomaterial growth via the "specific microwave effect" can be achieved by selective heating of the chalcogenide precursor. The high polarizability of the precursor allows instantaneous activation and subsequent nucleation leading to the synthesis of CdSe and CdTe in nonmicrowave absorbing alkane solvents. Regardless of the desired size, narrow dispersity nanocrystals can be isolated in less than 3 min with high quantum efficiencies and elliptical morphologies. The reaction does not require a high temperature injection step, and the alkane solvent can be easily removed. In addition, batch-to-batch variance in size is 4.2 +/- 0.14 nm for 10 repeat experimental runs. The use of a stopped-flow reactor allows near continuous automation of the process leading to potential industrial benefits. PMID:18576624

  3. Liquid-vapor equilibria and interfacial properties of n-alkanes and perfluoroalkanes by molecular simulation.

    PubMed

    Amat, Miguel A; Rutledge, Gregory C

    2010-03-21

    A molecular dynamics study is presented to assess the performance of a united-atom model in the prediction of liquid-vapor interfacial properties for short-chain perfluoroalkanes and their alkane counterparts. In particular, the ability of this model to discriminate between the surface-energy values of these two types of compounds was investigated over a wide temperature range corresponding to the liquid-vapor region. Comparisons with available experimental data and surface-tension predictions given by other force-field parameterizations, including those based on the more computationally demanding all-atom method, were performed to gauge the viability of this model. It was found that the model used in this study captures qualitatively the expected behavior of surface energy between alkanes and perfluoroalkanes and yields values that are in excellent agreement with experimental data, especially in the high-temperature limit as the critical temperature is approached.

  4. Stable Isotope Labeled n-Alkanes to Assess Digesta Passage Kinetics through the Digestive Tract of Ruminants

    PubMed Central

    Warner, Daniel; Ferreira, Luis M. M.; Breuer, Michel J. H.; Dijkstra, Jan; Pellikaan, Wilbert F.

    2013-01-01

    We describe the use of carbon stable isotope (13C) labeled n-alkanes as a potential internal tracer to assess passage kinetics of ingested nutrients in ruminants. Plant cuticular n-alkanes originating from intrinsically 13C labeled ryegrass plants were pulse dosed intraruminally in four rumen-cannulated lactating dairy cows receiving four contrasting ryegrass silage treatments that differed in nitrogen fertilization level (45 or 90 kg nitrogen ha−1) and maturity (early or late). Passage kinetics through the gastrointestinal tract were derived from the δ13C (i.e. the ratio 13C:12C) in apparently undigested fecal material. Isotopic enrichment was observed in a wide range of long-chain n-alkanes (C27–C36) and passage kinetics were determined for the most abundant C29, C31 and C33 n-alkanes, for which a sufficiently high response signal was detected by combustion isotope ratio mass spectrometry. Basal diet treatment and carbon chain length of n-alkanes did not affect fractional passage rates from the rumen (K1) among individual n-alkanes (3.71–3.95%/h). Peak concentration time and transit time showed a quantitatively small, significant (p≤0.002) increase with carbon chain length. K1 estimates were comparable to those of the 13C labeled digestible dry matter fraction (3.38%/h; r = 0.61 to 0.71; p≤0.012). A literature review has shown that n-alkanes are not fermented by microorganisms in the rumen and affirms no preferential depletion of 13C versus 12C. Our results suggest that 13C labeled n-alkanes can be used as nutrient passage tracers and support the reliability of the δ13C signature of digestible feed nutrients as a tool to measure nutrient-specific passage kinetics. PMID:24124493

  5. A hexanuclear mixed-valence oxovanadium(IV,V) complex as a highly efficient alkane oxidation catalyst.

    PubMed

    Sutradhar, Manas; Kirillova, Marina V; Guedes da Silva, M Fátima C; Martins, Luísa M D R S; Pombeiro, Armando J L

    2012-11-01

    The new hexanuclear mixed-valence vanadium complex [V(3)O(3)(OEt)(ashz)(2)(μ-OEt)](2) (1) with an N,O-donor ligand is reported. It acts as a highly efficient catalyst toward alkane oxidations by aqueous H(2)O(2). Remarkably, high turnover numbers up to 25000 with product yields of up to 27% (based on alkane) stand for one of the most active systems for such reactions.

  6. Alkane distribution and carbon isotope composition in fossil leaves: An interpretation of plant physiology in the geologic past

    NASA Astrophysics Data System (ADS)

    Graham, H. V.; Freeman, K. H.

    2014-12-01

    The relative chain-length distribution and carbon-isotope composition of n-alkanes extracted from sedimentary rocks are important geochemical tools for investigating past terrestrial ecosystems. Alkanes preserved in ancient sediments are assumed to be contemporaneous, derived from the same ecosystem, and integrated from the biomass present on the landscape at the time of deposition. Further, there is an underlying assumption that ancient plants exhibited the same metabolic and physiological responses to climate conditions that are observed for modern plants. Interpretations of alkane abundances and isotopic signatures are complicated by the strong influence of phylogenetic affiliation and ecological factors, such as canopy structure. A better understanding of how ecosystem and taxa influence alkane properties, including homologue abundance patterns and leaf-lipid carbon isotope fractionation would help strengthen paleoecological interpretations based on these widely employed plant biomarkers. In this study, we analyze the alkane chain-length distribution and carbon-isotope composition of phytoleim and alkanes (d13Cleaf and d13Clipid) extracted from a selection of Cretaceous and Paleocene fossil leaves from the Guaduas and Cerrejon Formations of Colombia. These data were compared with data for the same families in a modern analogue biome. Photosynthetic and biosynthetic fractionation (∆leaf and elipid) values determined from the fossil material indicate carbon metabolism patterns were similar to modern plants. Fossil data were incorporated in a biomass-weighted mixing model to represent the expected lipid complement of sediment arising from this ecosystem and compared with alkane measurements from the rock matrix. Modeled and observed isotopic and abundance patterns match well for alkane homologs most abundant in plants (i.e., n-C27 to n-C33). The model illustrates the importance of understanding biases in litter flux and taphonomic pressures inherent in the

  7. A unified single-event microkinetic model for alkane hydroconversion in different aggregation states on Pt/H-USY-zeolites.

    PubMed

    Laxmi Narasimhan, C S; Thybaut, Joris W; Martens, Johan A; Jacobs, Pierre A; Denayer, Joeri F; Marin, Guy B

    2006-04-01

    A single-event microkinetic model for the catalytic hydroconversion of hydrocarbons on Pt/H-US-Y bifunctional zeolite catalysts developed for low-pressure vapor phase conditions was extended to cover high-pressure vapor phase and liquid phase conditions. The effect of the density of the bulk hydrocarbon phase on the physisorption as well as on the protonation steps of the reaction network was accounted for explicitly and can be interpreted in terms of "compression" of the hydrocarbon sorbate inside the zeolite pores and "solvation" of the catalyst framework by the dense bulk hydrocarbon phase. The bulk phase density effect on the physisorbed state is described via a single excess free enthalpy of physisorption. A dense bulk hydrocarbon phase destabilizes the sorbate molecules inside the catalyst pores. An expression of the excess free enthalpy of physisorption involving the fugacity coefficient and a zeolite dependent factor allows description of physisorption data. Typical excess free enthalpy values are in the range 1.5-5.1 kJ mol(-1) increasing with carbon number in the series of C5-C16 alkanes. At high-pressure vapor phase and liquid phase conditions, the excess standard protonation enthalpy is estimated at -7.8 kJ mol(-1) leading to relatively more stable carbenium ions at dense bulk phase conditions. As a result of the excess physisorption and protonation properties, the lightest hydrocarbons in mixtures are more competitive at dense phase conditions and their conversion is enhanced compared to low-density conditions. PMID:16570981

  8. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    DOEpatents

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-09-29

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase is dispersed.

  9. Iridium complexes of new NCP pincer ligands: catalytic alkane dehydrogenation and alkene isomerization.

    PubMed

    Jia, Xiangqing; Zhang, Lei; Qin, Chuan; Leng, Xuebing; Huang, Zheng

    2014-09-28

    Iridium complexes of novel NCP pincer ligands containing pyridine and phosphinite arms have been synthesized. One Ir complex shows good catalytic activity for alkane dehydrogenation, and all complexes are highly active for olefin isomerization. A combination of the Ir complex and a (PNN)Fe pincer complex catalyzes the formation of linear alkylboronates selectively from internal olefins via sequential olefin isomerization-hydroboration. PMID:25101950

  10. Angiosperm n-alkane distribution patterns and the geologic record of C4 grassland evolution

    NASA Astrophysics Data System (ADS)

    Henderson, A.; Graham, H. V.; Patzkowsky, M.; Fox, D. L.; Freeman, K. H.

    2012-12-01

    n-Alkane average chain-length (ACL) patterns vary regionally with community composition and climate. To clarify the influence of phylogenetic and community patterns, we compiled and analyzed a global database of published n-alkane abundance for n-C27 to C35 homologs in modern plant specimens (n=205). ACL for waxes in C4 non-woody plants are longer than for woody plants, suggesting ACL can serve as an indicator of the three-dimensional structure of local vegetation. Further, these findings suggest compound-specific isotopic data for longer alkane homologs (C31, C33, C35) will proportionately represent non-woody vegetation and isotope measurements of C29 are more representative of woody vegetation. Thus, the combination of ACL and carbon isotope compositions should allow us to disentangle C3 woody, C3 non-woody, and C4 non-woody signals in terrestrial paleorecords. Application of this approach to the geologic record of Miocene C4 grassland expansion in the US Great Plains and the Siwaliks in Pakistan illustrate two very different transition scenarios. Alkane-specific isotopic data indicate C4 grasslands appeared 2.5 Ma in the Great Plains and 6.5 Ma in the Siwaliks, and ACL analysis indicates that this transition involved the replacement of woody vegetation in the US and the replacement of C3 grasses in Pakistan. Our analysis illustrates that, consistent with differences in the timing of C4 grassland, the drivers of change were likely not the same in these regions. Oxygen isotope records suggest that the more recent transition in the Great Plains was associated with climate cooling and possibly changes in disturbance regimes and that the transition in the Siwaliks was likely associated with warming and drying.

  11. Using n-alkanes to estimate diet composition of herbivores: a novel mathematical approach.

    PubMed

    Barcia, P; Bugalho, M N; Campagnolo, M L; Cerdeira, J O

    2007-02-01

    N-alkanes are long-chain saturated hydrocarbons occurring in plant cuticles that can be used as chemical markers for estimating the diet composition of herbivores. An important constraint of using n-alkanes to estimate diet composition with currently employed mathematical procedures is that the number of markers must be equal or larger than the number of diet components. This is a considerable limitation when dealing with free-ranging herbivores feeding on complex plant communities. We present a novel approach for the estimation of diet composition using n-alkanes which applies equally to cases where the number of markers is lower, equal or greater than the number of plant species in the diet. The model uses linear programming to estimate the minimum and maximum proportions of each plant in the diet, and avoids the need for grouping species in order to reduce the number of estimated dietary components. We illustrate the model with two data sets of n-alkane content of plants and faeces obtained from a sheep grazing experiment conducted in Australia and a red deer study in Portugal. Our results are consistent with previous studies on those data sets and provide additional information on the proportions of individual species in the diet. Results show that sheep included in the diet high proportions of white clover (from 0.25 to 0.37), and relatively high proportions of grasses (e.g. brome from 0.14 to 0.26) but tended to avoid Lotus spp. (always less than 0.04 of the diet). For red deer we found high proportions of legumes (e.g. Trifolium angustifolium and Vicia sativa reaching maximum proportions of 0.42 and 0.30 of the diet, respectively) with grasses being less important and Cistus ladanifer, a browse, also having relevance (from 0.21 to 0.42 of the diet).

  12. Genome Sequence of Rhodococcus sp. Strain BCP1, a Biodegrader of Alkanes and Chlorinated Compounds

    PubMed Central

    Cappelletti, M.; Di Gennaro, P.; D’Ursi, P.; Orro, A.; Mezzelani, A.; Landini, M.; Fedi, S.; Frascari, D.; Presentato, A.; Milanesi, L.

    2013-01-01

    Rhodococcus sp. strain BCP1 cometabolizes chlorinated compounds and mineralizes a broad range of alkanes, as it is highly tolerant to them. The high-quality draft genome sequence of Rhodococcus sp. strain BCP1, consisting of 6,231,823 bp, with a G+C content of 70.4%, 5,902 protein-coding genes, and 58 RNA genes, is presented here. PMID:24158549

  13. Long-chain n-alkanes occurring during microbial degradation of petroleum.

    PubMed

    Walker, J D; Colwell, R R

    1976-06-01

    Five axenic cultures and a mixed culture were examined for ability to degrade South Louisiana, Brass River Nigerian, Anaco Venezuelan, and Altamont crude oils. A wax was observed during microbial degradation of Altamont crude oil, but not during weathering of the oil. The high-boiling n-alkanes in the wax were associated with microbial degradation of the oil and appeared to be similar to components of tarballs found in the open ocean. PMID:1277009

  14. Gas phase heterogeneous catalytic oxidation of alkanes to aliphatic ketones and/or other oxygenates

    SciTech Connect

    Lin, Manhua; Wang, Xiang; Yeom, Younghoon

    2015-03-17

    A catalyst, its method of preparation and its use for producing aliphatic ketones by subjecting alkanes C.sub.3 to C.sub.9 to a gas phase catalytic oxidation in the presence of air or oxygen, and, optionally, steam and/or one or more diluting gases. The catalyst comprises a catalytically active mixed metal oxide phase and a suitable support material onto and/or into which the active catalytic phase id dispersed.

  15. Enthalpies of dissolution of n-alkanes in a mixture of methanol-formamide

    NASA Astrophysics Data System (ADS)

    Batov, D. V.; Kustov, A. V.; Antonova, O. A.; Smirnova, N. L.

    2015-06-01

    The enthalpies of dissolution of n-hexane, n-octane, and n-decane are determined thermochemically under standard conditions to describe nonspecific solvation in a mixed solvent of methanol-formamide. Experimental data are matched with the values obtained using model calculations. It is found that the differences between the experimental and calculated enthalpies of dissolution in the region with a high content of formamide could be due to the preferable solvation of n-alkanes by methanol.

  16. Leaf n-alkanes as characters differentiating coastal and continental Juniperus deltoides populations from the Balkan Peninsula.

    PubMed

    Rajčević, Nemanja; Janaćković, Pedja; Dodoš, Tanja; Tešević, Vele; Bojović, Srdjan; Marin, Petar D

    2014-07-01

    The composition of the cuticular n-alkanes isolated from the leaves of nine populations of Juniperus deltoides R.P.Adams from continental and coastal areas of the Balkan Peninsula was characterized by GC-FID and GC/MS analyses. In the leaf waxes, 14 n-alkane homologues with chain-lengths ranging from C22 to C35 were identified. n-Tritriacontane (C33 ) was dominant in the waxes of all populations, but variations between the populations in the contents of all n-alkanes were observed. Several statistical methods (ANOVA, principal component, discriminant, and cluster analyses) were used to investigate the diversity and variability of the cuticular-leaf-n-alkane patterns of the nine J. deltoides populations. This is the first report on the n-alkane composition for this species. The multivariate statistical analyses evidenced a high correlation of the leaf-n-alkane pattern with the geographical distribution of the investigated samples, differentiating the coastal from the continental populations of this taxon.

  17. Water solubility of selected C9-C18 alkanes using a slow-stir technique: Comparison to structure - property models.

    PubMed

    Letinski, Daniel J; Parkerton, Thomas F; Redman, Aaron D; Connelly, Martin J; Peterson, Brian

    2016-05-01

    Aqueous solubility is a fundamental physical-chemical substance property that strongly influences the distribution, fate and effects of chemicals upon release into the environment. Experimental water solubility was determined for 18 selected C9-C18 normal, branched and cyclic alkanes. A slow-stir technique was applied to obviate emulsion formation, which historically has resulted in significant overestimation of the aqueous solubility of such hydrophobic liquid compounds. Sensitive GC-MS based methods coupled with contemporary sample extraction techniques were employed to enable reproducible analysis of low parts-per billion aqueous concentrations. Water solubility measurements for most of the compounds investigated, are reported for the first time expanding available data for branched and cyclic alkanes. Measured water solubilities spanned four orders of magnitude ranging from 0.3 μg/L to 250 μg/L. Good agreement was observed for selected alkanes tested in this work and reported in earlier literature demonstrating the robustness of the slow-stir water solubility technique. Comparisons of measured alkane water solubilities were also made with those predicted by commonly used quantitative structure-property relationship models (e.g. SPARC, EPIWIN, ACD/Labs). Correlations are also presented between alkane measured water solubilities and molecular size parameters (e.g. molar volume, solvent accessible molar volume) affirming a mechanistic description of empirical aqueous solubility results and prediction previously reported for a more limited set of alkanes. PMID:26924078

  18. Transcriptional response of Desulfatibacillum alkenivorans AK-01 to growth on alkanes: insights from RT-qPCR and microarray analyses.

    PubMed

    Herath, Anjumala; Wawrik, Boris; Qin, Yujia; Zhou, Jizhong; Callaghan, Amy V

    2016-05-01

    Microbial transformation of n-alkanes in anaerobic ecosystems plays a pivotal role in biogeochemical carbon cycling and bioremediation, but the requisite genetic machinery is not well elucidated.Desulfatibacillum alkenivorans AK-01 utilizes n-alkanes (C13 to C18) and contains two genomic loci encoding alkylsuccinate synthase (ASS) gene clusters. ASS catalyzes alkane addition to fumarate to form methylalkylsuccinic acids. We hypothesized that the genes in the two clusters would be differentially expressed depending on the alkane substrate utilized for growth. RT-qPCR was used to investigate ass-gene expression across AK-01's known substrate range, and microarray-based transcriptomic analysis served to investigate whole-cell responses to growth on n-hexadecane versus hexadecanoate. RT-qPCR revealed induction of ass gene cluster 1 during growth on all tested alkane substrates, and the transcriptional start sites in cluster 1 were determined via 5'RACE. Induction of ass gene cluster 2 was not observed under the tested conditions. Transcriptomic analysis indicated that the upregulation of genes potentially involved in methylalkylsuccinate metabolism, including methylmalonyl-CoA mutase and a putative carboxyl transferase. These findings provide new directions for studying the transcriptional regulation of genes involved in alkane addition to fumarate, fumarate recycling and the processing of methylalkylsuccinates with regard to isolates, enrichment cultures and ecological datasets.

  19. Transcriptional response of Desulfatibacillum alkenivorans AK-01 to growth on alkanes: insights from RT-qPCR and microarray analyses.

    PubMed

    Herath, Anjumala; Wawrik, Boris; Qin, Yujia; Zhou, Jizhong; Callaghan, Amy V

    2016-05-01

    Microbial transformation of n-alkanes in anaerobic ecosystems plays a pivotal role in biogeochemical carbon cycling and bioremediation, but the requisite genetic machinery is not well elucidated.Desulfatibacillum alkenivorans AK-01 utilizes n-alkanes (C13 to C18) and contains two genomic loci encoding alkylsuccinate synthase (ASS) gene clusters. ASS catalyzes alkane addition to fumarate to form methylalkylsuccinic acids. We hypothesized that the genes in the two clusters would be differentially expressed depending on the alkane substrate utilized for growth. RT-qPCR was used to investigate ass-gene expression across AK-01's known substrate range, and microarray-based transcriptomic analysis served to investigate whole-cell responses to growth on n-hexadecane versus hexadecanoate. RT-qPCR revealed induction of ass gene cluster 1 during growth on all tested alkane substrates, and the transcriptional start sites in cluster 1 were determined via 5'RACE. Induction of ass gene cluster 2 was not observed under the tested conditions. Transcriptomic analysis indicated that the upregulation of genes potentially involved in methylalkylsuccinate metabolism, including methylmalonyl-CoA mutase and a putative carboxyl transferase. These findings provide new directions for studying the transcriptional regulation of genes involved in alkane addition to fumarate, fumarate recycling and the processing of methylalkylsuccinates with regard to isolates, enrichment cultures and ecological datasets. PMID:27009900

  20. A new mechanism for regional atmospheric chemistry modeling

    NASA Astrophysics Data System (ADS)

    Stockwell, William R.; Kirchner, Frank; Kuhn, Michael; Seefeld, Stephan

    1997-11-01

    A new gas-phase chemical mechanism for the modeling of regional atmospheric chemistry, the "Regional Atmospheric Chemistry Mechanism" (RACM) is presented. The mechanism is intended to be valid for remote to polluted conditions and from the Earth's surface through the upper troposphere. The RACM mechanism is based upon the earlier Regional Acid Deposition Model, version 2 (RADM2) mechanism [Stockwell et al., 1990] and the more detailed Euro-RADM mechanism [Stockwell and Kley, 1994]. The RACM mechanism includes rate constants and product yields from the most recent laboratory measurements, and it has been tested against environmental chamber data. A new condensed reaction mechanism is included for biogenic compounds: isoprene, α-pinene, and d-limonene. The branching ratios for alkane decay were reevaluated, and in the revised mechanism the aldehyde to ketone ratios were significantly reduced. The relatively large amounts of nitrates resulting from the reactions of unbranched alkenes with NO3 are now included, and the production of HO from the ozonolysis of alkenes has a much greater yield. The aromatic chemistry has been revised through the use of new laboratory data. The yield of cresol production from aromatics was reduced, while the reactions of HO, NO3, and O3 with unsaturated dicarbonyl species and unsaturated peroxynitrate are now included in the RACM mechanism. The peroxyacetyl nitrate chemistry and the organic peroxy radical-peroxy radical reactions were revised, and organic peroxy radical +NO3 reactions were added.

  1. Diffusion of methane and other alkanes in metal-organic frameworks for natural gas storage

    SciTech Connect

    Borah, B; Zhang, HD; Snurr, RQ

    2015-03-03

    Diffusion of methane, ethane, propane and n-butane was studied within the micropores of several metal organic frameworks (MOFs) of varying topologies, including the MOFs PCN-14, NU-125, NU-1100 and DUT-49. Diffusion coefficients of the pure components, as well as methane/ethane, methane/ propane and methane/butane binary mixtures, were calculated using molecular dynamics simulations to understand the effect of the longer alkanes on uptake of natural gas in MOB. The calculated self diffusion coefficients of all four components are on the order of 10(-8) m(2)/s. The diffusion coefficients of the pure components decrease as a function of chain length in all of the MOFs studied and show different behaviour as a function of loading in different MOB. The self-diffusivities follow the trend DPCN-14 < DNU-125 approximate to DNU-1100 < DDUT-49, which is exactly the reverse order of the densities of the MOFs: PCN-14 > NU-125 approximate to NU-1100 > DUT-49. By comparing the diffusion of pure methane and methane mixtures vvith the higher alkancs, it is observed that the diffusivity of methane is unaffected by the presence of the higher alkanes in the MOFs considered, indicating that the diffusion path of methane is not blocked by the higher alkanes present in natural gas. (C) 2014 Elsevier Ltd. All rights reserved.

  2. Molecular dynamics simulations of layers of linear and branched alkanes under shear

    NASA Astrophysics Data System (ADS)

    Soza, P.; Hansen, F. Y.; Taub, H.; Volkmann, U. G.

    2008-03-01

    We have previously studied the equilibrium structure and dynamical excitations in films of the linear alkane tetracosane (n-C24H50) and the branched alkane squalane (C30H62) in great detail^2. Here we report the results of nonequilibrium molecular dynamics simulations of these systems in order to compare the rheological properties of alkanes of the same length but with different architecture. The simulations were done in the NVT ensemble using the reverse nonequilibrium algorithm proposed by F. Müller-Plathe et al.^3. The viscosity was calculated for different shear rates and compared with experimental values. Different structural parameters such as the mean end-to-end distance, the radius of gyration, and the angle of alignment of the molecules with the flow were studied as a function of the shear rate. ^2A.D. Enevoldsen et al., J. Chem. Phys. 126, 104703-10 (2007); 126, 104704-17 (2007). ^3F. Müller-Plathe et al., Phys. Rev. E, 59, 4894 (1998)

  3. Environmental hazards and health risk of common liquid perfluoro-n-alkanes, potent greenhouse gases.

    PubMed

    Tsai, Wen-Tien

    2009-02-01

    This article aimed at introducing the main physical properties and commercial/industrial uses of common liquid perfluoro-n-alkanes (including perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, and perfluorononane) and the environment and health hazards posed by their toxic decomposition products (especially in hydrogen fluoride and perfluoroisobutylene) because these perfluorocompounds are potent greenhouse gases, which have been blanketed into the Kyoto Protocol, but was rarely described in the National Inventory Reports by Annex I Parties. The environmental properties (including octanol-water partition coefficient, water solubility and Henry's law constant) of liquid perfluoro-n-alkanes were evaluated, and further discussed were its atmospheric implications according to the predicted properties and possible proposal for the formation of trifluoroacetic acid (CF(3)COOH) in the atmosphere by the ionized photolysis. These predicted values revealed that liquid perfluoro-n-alkanes tend to be hydrophobic and partitioned into organic matter, and they have exceptionally low solubility in water and extremely high vaporization from the water bodies, suggesting that it will sink into the atmosphere if it is released into the environment.

  4. Raman analysis of bond conformations in the rotator state and premelting of normal alkanes.

    PubMed

    Kotula, Anthony P; Walker, Angela R Hight; Migler, Kalman B

    2016-06-14

    We perform Raman spectroscopic measurements on normal alkanes (CnH2n+2) to quantify the n dependence of the conformational disorder that occurs below the melt temperature. We employ a three-state spectral analysis method originally developed for semi-crystalline polyethylene that posits crystalline, amorphous, and non-crystalline consecutive trans (NCCT) conformations to extract their respective mass fractions. For the alkanes studied that melt via a rotator phase (21 ≤n≤ 37), we find that conformational disorder can be quantified by the loss of NCCT mass fraction, which systematically decreases with increasing chain length. For those that melt directly via the crystal phase (n≥ 40), we observe NCCT conformational mass fractions that are independent of chain length but whose disordered mass fraction increases with length. These complement prior IR measurements which measure disorder via gauche conformations, but have not been able to measure the mass fraction of this disorder as a function of n. An interesting feature of the three-state analysis when applied to alkanes is that the measured fraction of disordered chain conformations in the rotator phase of (10 to 30)% greatly exceeds the mass fraction of gauche bonds (1 to 7)% as measured from IR; we reconcile this difference through DFT calculations. PMID:27174157

  5. Line tension of alkane lenses on aqueous surfactant solutions at phase transitions of coexisting interfaces.

    PubMed

    Matsubara, Hiroki; Ushijima, Baku; Law, Bruce M; Takiue, Takanori; Aratono, Makoto

    2014-04-01

    Alkane droplets on aqueous solutions of surfactants exhibit a first-order wetting transition as the concentration of surfactant is increased. The low-concentration or "partial wetting" state corresponds to an oil lens in equilibrium with a two-dimensional dilute gas of oil and surfactant molecules. The high-concentration or "pseudo-partial wetting" state consists of an oil lens in equilibrium with a mixed monolayer of surfactant and oil. Depending on the combination of surfactant and oil, these mixed monolayers undergo a thermal phase transition upon cooling, either to a frozen mixed monolayer or to an unusual bilayer structure in which the upper leaflet is a solid layer of pure alkane with hexagonal packing and upright chains while the lower leaflet remains a disordered liquid-like mixed monolayer. Additionally, certain long-chain alkanes exhibit a surface freezing transition at the air-oil interface where the top monolayer of oil freezes above its melting point. In this review, we summarize our previous studies and discuss how these wetting and surface freezing transitions influence the line tension of oil lenses from both an experimental and theoretical perspective.

  6. Diffusion of Trace Alkanes in Polyethylene: Spin-Echo Measurements and Monte-Carlo Simulations

    NASA Astrophysics Data System (ADS)

    von Meerwall, E.; Lin, H.; Mattice, W. L.

    2006-03-01

    We have performed pulsed-gradient NMR diffusion (D) measurements on five n-alkanes (24, 28, 36, 44, and 60 carbons) in a polyethylene (PE) host (M = 33 kDa) as function of concentration c (2-10 wt.%) at 180 deg. C. Monte-Carlo simulations on the second-nearest-neighbor diamond lattice (38, 46, 62, and 78 carbons) at c between 2 and 15 wt.% in a host of PE (M = 4.5 kDa) explored static and dynamic properties. The bridging method uses beads combining adjacent moieties and incorporates two-bead moves; it permits detailed reconstruction of the chain molecules at any stage. It uses discretized short-range rotational isomeric state and long-range intra- and interchain Lennard-Jones potentials. For both experiment and simulation, trace D was obtained by extrapolating D(c) to c = 0 using the Fujita-Doolittle equation with known chain-end free-volume parameters. A ratio of 330 Monte-Carlo steps per picosecond brings simulation into congruence with experiment; this factor is identical to that required for PE melts. The applicability of the Rouse model is approached only for the largest alkanes, but the M(alkane)-dependence of trace D is seen to be in transition from the Rouse-like 1/M-scaling to a steeper value characteristic of reptation with constraint release.

  7. Fully atomistic molecular-mechanical model of liquid alkane oils: Computational validation.

    PubMed

    Zahariev, Tsvetan K; Slavchov, Radomir I; Tadjer, Alia V; Ivanova, Anela N

    2014-04-15

    Fully atomistic molecular dynamics simulations were performed on liquid n-pentane, n-hexane, and n-heptane to derive an atomistic model for middle-chain-length alkanes. All simulations were based on existing molecular-mechanical parameters for alkanes. The computational protocol was optimized, for example, in terms of thermo- and barostat, to reproduce properly the properties of the liquids. The model was validated by comparison of thermal, structural, and dynamic properties of the normal alkane liquids to experimental data. Two different combinations of temperature and pressure coupling algorithms were tested. A simple differential approach was applied to evaluate fluctuation-related properties with sufficient accuracy. Analysis of the data reveals a satisfactory representation of the hydrophobic systems behavior. Thermodynamic parameters are close to the experimental values and exhibit correct temperature dependence. The observed intramolecular geometry corresponds to extended conformations domination, whereas the intermolecular structure demonstrates all characteristics of liquid systems. Cavity size distribution function was calculated from coordinates analysis and was applied to study the solubility of gases in hexane and heptane oils. This study provides a platform for further in-depth research on hydrophobic solutions and multicomponent systems.

  8. Fully atomistic molecular-mechanical model of liquid alkane oils: Computational validation.

    PubMed

    Zahariev, Tsvetan K; Slavchov, Radomir I; Tadjer, Alia V; Ivanova, Anela N

    2014-04-15

    Fully atomistic molecular dynamics simulations were performed on liquid n-pentane, n-hexane, and n-heptane to derive an atomistic model for middle-chain-length alkanes. All simulations were based on existing molecular-mechanical parameters for alkanes. The computational protocol was optimized, for example, in terms of thermo- and barostat, to reproduce properly the properties of the liquids. The model was validated by comparison of thermal, structural, and dynamic properties of the normal alkane liquids to experimental data. Two different combinations of temperature and pressure coupling algorithms were tested. A simple differential approach was applied to evaluate fluctuation-related properties with sufficient accuracy. Analysis of the data reveals a satisfactory representation of the hydrophobic systems behavior. Thermodynamic parameters are close to the experimental values and exhibit correct temperature dependence. The observed intramolecular geometry corresponds to extended conformations domination, whereas the intermolecular structure demonstrates all characteristics of liquid systems. Cavity size distribution function was calculated from coordinates analysis and was applied to study the solubility of gases in hexane and heptane oils. This study provides a platform for further in-depth research on hydrophobic solutions and multicomponent systems. PMID:24554590

  9. The air-water exchange of C{sub 15}-C{sub 31} n-alkanes in a precipitation-dominated seepage lake.

    SciTech Connect

    Doskey, P. V.; Environmental Research

    2000-01-01

    The air-water exchange of semivolatile n-alkanes in Crystal Lake, a small precipitation-dominated seepage lake in northern Wisconsin, was investigated with modeling and mass balance approaches. The results suggest that atmospheric deposition contributes approximately 80% of the allochthonous input of n-alkanes to Crystal Lake. Atmospheric deposition accounts for about 50% of the total annual input of n-alkanes to Crystal Lake, and an additional 30% is contributed by in situ production of planktonic n-alkanes ({Sigma}C{sub 15}, C{sub 17}, C{sub 19}). Contributions to the particle dry flux of terrestrial n-alkanes ({Sigma}C{sub 25}, C{sub 27}, C{sub 29}, C{sub 31}) by pine pollen dispersal and by dry deposition of particles containing leaf waxes are similar in magnitude and constitute about 60% of the atmospheric input, with particle wet deposition being responsible for the remainder. Approximately 30% of the atmospheric input of the n-alkanes occurs during a two-week episode of pine pollen dispersal in spring. Concentration gradients between gaseous n-alkanes in the atmosphere and dissolved n-alkanes in the water column of Crystal Lake favor volatilization of n-alkanes from the lake surface; however, distributions of dissolved n-alkanes are characteristic of bacteria, and therefore are contained in organic matter and not available for air-water exchange. The estimated net atmospheric input of terrestrial n-alkanes is about 20% less than the settling sediment flux. Additional allochthonous sources of the terrestrial n-alkanes might include diffuse surface runoff or episodes of coarse-particle deposition. The discrepancies in the results from the modeling and mass balance approaches indicate that direct measurements of air-water exchange rates and measurements of the seasonal variations of particle size distributions in air and rain would greatly improve our ability to quantify air-water exchange rates of n-alkanes.

  10. Constitutional dynamic chemistry: bridge from supramolecular chemistry to adaptive chemistry.

    PubMed

    Lehn, Jean-Marie

    2012-01-01

    Supramolecular chemistry aims at implementing highly complex chemical systems from molecular components held together by non-covalent intermolecular forces and effecting molecular recognition, catalysis and transport processes. A further step consists in the investigation of chemical systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, thus behaving as programmed chemical systems. Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when the molecular entity contains covalent bonds that may form and break reversibility, so as to allow a continuous change in constitution by reorganization and exchange of building blocks. These features define a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels.CDC introduces a paradigm shift with respect to constitutionally static chemistry. The latter relies on design for the generation of a target entity, whereas CDC takes advantage of dynamic diversity to allow variation and selection. The implementation of selection in chemistry introduces a fundamental change in outlook. Whereas self-organization by design strives to achieve full control over the output molecular or supramolecular entity by explicit programming, self-organization with selection operates on dynamic constitutional diversity in response to either internal or external factors to achieve adaptation.The merging of the features: -information and programmability, -dynamics and reversibility, -constitution and structural diversity, points to the emergence of adaptive and evolutive chemistry, towards a chemistry of complex matter.

  11. Carboxylic acid reductase is a versatile enzyme for the conversion of fatty acids into fuels and chemical commodities

    PubMed Central

    Akhtar, M. Kalim; Turner, Nicholas J.; Jones, Patrik R.

    2013-01-01

    Aliphatic hydrocarbons such as fatty alcohols and petroleum-derived alkanes have numerous applications in the chemical industry. In recent years, the renewable synthesis of aliphatic hydrocarbons has been made possible by engineering microbes to overaccumulate fatty acids. However, to generate end products with the desired physicochemical properties (e.g., fatty aldehydes, alkanes, and alcohols), further conversion of the fatty acid is necessary. A carboxylic acid reductase (CAR) from Mycobacterium marinum was found to convert a wide range of aliphatic fatty acids (C6–C18) into corresponding aldehydes. Together with the broad-substrate specificity of an aldehyde reductase or an aldehyde decarbonylase, the catalytic conversion of fatty acids to fatty alcohols (C8–C16) or fatty alkanes (C7–C15) was reconstituted in vitro. This concept was applied in vivo, in combination with a chain-length-specific thioesterase, to engineer Escherichia coli BL21(DE3) strains that were capable of synthesizing fatty alcohols and alkanes. A fatty alcohol titer exceeding 350 mg·L−1 was obtained in minimal media supplemented with glucose. Moreover, by combining the CAR-dependent pathway with an exogenous fatty acid-generating lipase, natural oils (coconut oil, palm oil, and algal oil bodies) were enzymatically converted into fatty alcohols across a broad chain-length range (C8–C18). Together with complementing enzymes, the broad substrate specificity and kinetic characteristics of CAR opens the road for direct and tailored enzyme-catalyzed conversion of lipids into user-ready chemical commodities. PMID:23248280

  12. Carboxylic acid reductase is a versatile enzyme for the conversion of fatty acids into fuels and chemical commodities.

    PubMed

    Akhtar, M Kalim; Turner, Nicholas J; Jones, Patrik R

    2013-01-01

    Aliphatic hydrocarbons such as fatty alcohols and petroleum-derived alkanes have numerous applications in the chemical industry. In recent years, the renewable synthesis of aliphatic hydrocarbons has been made possible by engineering microbes to overaccumulate fatty acids. However, to generate end products with the desired physicochemical properties (e.g., fatty aldehydes, alkanes, and alcohols), further conversion of the fatty acid is necessary. A carboxylic acid reductase (CAR) from Mycobacterium marinum was found to convert a wide range of aliphatic fatty acids (C(6)-C(18)) into corresponding aldehydes. Together with the broad-substrate specificity of an aldehyde reductase or an aldehyde decarbonylase, the catalytic conversion of fatty acids to fatty alcohols (C(8)-C(16)) or fatty alkanes (C(7)-C(15)) was reconstituted in vitro. This concept was applied in vivo, in combination with a chain-length-specific thioesterase, to engineer Escherichia coli BL21(DE3) strains that were capable of synthesizing fatty alcohols and alkanes. A fatty alcohol titer exceeding 350 mg·L(-1) was obtained in minimal media supplemented with glucose. Moreover, by combining the CAR-dependent pathway with an exogenous fatty acid-generating lipase, natural oils (coconut oil, palm oil, and algal oil bodies) were enzymatically converted into fatty alcohols across a broad chain-length range (C(8)-C(18)). Together with complementing enzymes, the broad substrate specificity and kinetic characteristics of CAR opens the road for direct and tailored enzyme-catalyzed conversion of lipids into user-ready chemical commodities. PMID:23248280

  13. CHEMISTRY IN EVAPORATING ICES-UNEXPLORED TERRITORY

    SciTech Connect

    Cecchi-Pestellini, Cesare; Rawlings, Jonathan M. C.; Viti, Serena; Williams, David A. E-mail: jcr@star.ucl.ac.u E-mail: daw@star.ucl.ac.u

    2010-12-20

    We suggest that three-body chemistry may occur in warm high-density gas evaporating in transient co-desorption events on interstellar ices. Using a highly idealized computational model we explore the chemical conversion from simple species of the ice to more complex species containing several heavy atoms, as a function of density and of adopted three-body rate coefficients. We predict that there is a wide range of densities and rate coefficients in which a significant chemical conversion may occur. We discuss the implications of this idea for the astrochemistry of hot cores.

  14. Fidelity of fossil n-alkanes from leaf to paleosol and applications to the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Bush, R. T.; McInerney, F. A.; Baczynski, A. A.; Wing, S. L.

    2011-12-01

    Long chain n-alkanes (C21-C35) are well-known as biomarkers of terrestrial plants. They can be preserved across a wide range of terrestrial and marine environments, survive in the sedimentary record for millions of years, and can serve as proxies for ancient environments. Most n-alkane records are derived from sediments rather than directly from fossil leaves. However, little is known about the fidelity of the n-alkane record: how and where leaf preservation relates to n-alkane preservation and how patterns of n-alkane carbon isotope ratios (δ13C) compare to living relatives. To examine these questions, we analyzed n-alkanes from fluvial sediments and individual leaf fossils collected in the Bighorn Basin, Wyoming, across the Paleocene-Eocene Thermal Maximum (PETM) carbon isotope excursion. We assessed the fidelity of the n-alkane signature from individual fossil leaves via three separate means. 1) Spatial variations were assessed by comparing n-alkane concentrations on a fossil leaf and in sediments both directly adjacent to the leaf and farther away. Absolute concentrations were greater within the compression fossil than in the directly adjacent sediment, which were in turn greater than in more distant sediment. 2) n-Alkane abundances and distributions were examined in fossil leaves having a range of preservational quality, from fossils with intact cuticle to carbonized fossils lacking cuticle and higher-order venation. The best preserved fossils preserved a higher concentration of n-alkanes and showed the most similar n-alkane distribution to living relatives. However, a strong odd over even predominance suggests a relatively unmodified plant source occurred in all samples regardless of preservation state. 3) n-Alkane δ13C values were measured for both fossil leaves and their living relatives. Both the saw-tooth pattern of δ13C values between odd and even chain lengths and the general decrease in δ13C values with increasing chain length are consistent with

  15. Conversing with Computers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    I/NET, Inc., is making the dream of natural human-computer conversation a practical reality. Through a combination of advanced artificial intelligence research and practical software design, I/NET has taken the complexity out of developing advanced, natural language interfaces. Conversational capabilities like pronoun resolution, anaphora and ellipsis processing, and dialog management that were once available only in the laboratory can now be brought to any application with any speech recognition system using I/NET s conversational engine middleware.

  16. Special Report: Brain Chemistry.

    ERIC Educational Resources Information Center

    Krassner, Michael B.

    1983-01-01

    Chemical actions in the brain result in cognitive, emotional, neuroendocrine, neuromuscular, and/or neurocirculatory effects. Developments in understanding brain chemistry are discussed, considering among others, neurotransmitter chemistry, neuropeptides, drugs and the brain, antidepressants, and actions of minor tranquilizers. (JN)

  17. Organometallic Chemistry of Molybdenum.

    ERIC Educational Resources Information Center

    Lucas, C. Robert; Walsh, Kelly A.

    1987-01-01

    Suggests ways to avoid some of the problems students have learning the principles of organometallic chemistry. Provides a description of an experiment used in a third-year college chemistry laboratory on molybdenum. (TW)

  18. Chemistry for Potters.

    ERIC Educational Resources Information Center

    Denio, Allen A.

    1980-01-01

    Relates pottery making to chemistry by providing chemical information about clay, its origin, composition, properties, and changes that occur during firing; also describes glaze compositions, examples of redox chemistry, salt glazing, crystalline glazes, and problems in toxicity. (CS)

  19. Environmental chemistry: Volume A

    SciTech Connect

    Yen, T.F.

    1999-08-01

    This is an extensive introduction to environmental chemistry for engineering and chemical professionals. The contents of Volume A include a brief review of basic chemistry prior to coverage of litho, atmo, hydro, pedo, and biospheres.

  20. Environmental swap energy and role of configurational entropy in transfer of small molecules from water into alkanes

    NASA Astrophysics Data System (ADS)

    Smejtek, Pavel; Word, Robert C.

    2004-01-01

    We studied the effect of segmented solvent molecules on the free energy of transfer of small molecules from water into alkanes (hexane, heptane, octane, decane, dodecane, tetradecane, and hexadecane). For these alkanes we measured partition coefficients of benzene, 3-methylindole (3MI), 2,3,4,6-tetrachlorophenol (TeCP), and 2,4,6-tribromophenol (TriBP) at 3, 11, 20, 3, and 47 °C. For 3MI, TeCP, and TriBP the dependence of free energy of transfer on length of alkane chains was found to be very different from that for benzene. In contrast to benzene, the energy of transfer for 3MI, TeCP, and TriBP was independent of the number of carbons in alkanes. To interpret data, we used the classic Flory-Huggins (FH) theory of concentrated polymer solutions for the alkane phase. For benzene, the measured dependence of energy of transfer on the number of carbons in alkanes agreed well with predictions based on FH model in which the size of alkane segments was obtained from the ratio of molar volumes of alkanes and the solute. We show that for benzene, the energy of transfer can be divided into two components, one called environmental swap energy (ESE), and one representing the contribution of configurational entropy of alkane chains. For 3MI, TeCP, and TriBP the contribution of configurational entropy was not measurable even though the magnitude of the effect predicted from the FH model for short chain alkanes was as much as 20 times greater than experimental uncertainties. From the temperature dependence of ESE we obtained enthalpy and entropy of transfer for benzene, 3MI, TeCP, and TriBP. Experimental results are discussed in terms of a thermodynamic cycle considering creation of cavity, insertion of solute, and activation of solute-medium attractive interactions. Our results suggest that correcting experimental free energy of transfer by Flory-Huggins configurational entropy term is not generally appropriate and cannot be applied indiscriminately.

  1. Conversion of biomass to selected chemical products.

    PubMed

    Gallezot, Pierre

    2012-02-21

    This critical review provides a survey illustrated by recent references of different strategies to achieve a sustainable conversion of biomass to bioproducts. Because of the huge number of chemical products that can be potentially manufactured, a selection of starting materials and targeted chemicals has been done. Also, thermochemical conversion processes such as biomass pyrolysis or gasification as well as the synthesis of biofuels were not considered. The synthesis of chemicals by conversion of platform molecules obtained by depolymerisation and fermentation of biopolymers is presently the most widely envisioned approach. Successful catalytic conversion of these building blocks into intermediates, specialties and fine chemicals will be examined. However, the platform molecule value chain is in competition with well-optimised, cost-effective synthesis routes from fossil resources to produce chemicals that have already a market. The literature covering alternative value chains whereby biopolymers are converted in one or few steps to functional materials will be analysed. This approach which does not require the use of isolated, pure chemicals is well adapted to produce high tonnage products, such as paper additives, paints, resins, foams, surfactants, lubricants, and plasticisers. Another objective of the review was to examine critically the green character of conversion processes because using renewables as raw materials does not exempt from abiding by green chemistry principles (368 references). PMID:21909591

  2. Allochthonous carbon hypothesis for bulk OM and n-alkane PETM carbon isotope discrepancies

    NASA Astrophysics Data System (ADS)

    Baczynski, A. A.; McInerney, F. A.; Wing, S. L.; Kraus, M. J.; Fricke, H. C.

    2011-12-01

    The Paleocene-Eocene Thermal Maximum (PETM), a period of abrupt, transient, and large-scale global warming fueled by a large release of isotopically light carbon, is a relevant analogue for episodes of rapid global warming and recovery. The PETM is recorded in pedogenic carbonate, bulk organic matter, and n-alkanes as a prominent negative carbon isotope excursion (CIE) in paleosols exposed in the Bighorn Basin, WY. Here we present a composite stable carbon isotope record from n-alkanes and dispersed soil organic δ13C records from five individual sections that span the PETM in the southeastern Bighorn Basin. Four sections are from a 10km transect in the Cabin Fork area and one section was collected at Sand Creek Divide. These five new dispersed organic carbon (DOC) isotope records are compared to the previously published Polecat Bench (Magioncalda et al. 2004) and Honeycombs (Yans et al. 2006) isotope records. The high-resolution n-alkane curve shows an abrupt, negative shift in δ13C values, an extended CIE body, and a rapid recovery to more positive δ13C values. Although the five DOC records show similarly abrupt negative shifts in δ13C values, the DOC CIEs are compressed, smaller in magnitude, and return to more positive δ13C values more gradually relative to the n-alkane record. Moreover, the stratigraphic thickness of the body of the excursion and the pattern of the recovery phase are not consistent among the five DOC records. We modeled predicted DOC δ13C values from the n-alkane record by applying enrichment factors based on modern plants to the n-alkane δ13C values. The anomaly, difference between the expected and observed DOC δ13C values, was calculated for the PETM records and compared to weight percent carbon and grain size. There is no correlation between pre- and post-PETM anomaly values and grain size or weight percent carbon. PETM anomaly values, however, do trend with both grain size and weight percent carbon. The largest PETM anomaly values

  3. Chemistry as General Education

    ERIC Educational Resources Information Center

    Tro, Nivaldo J.

    2004-01-01

    The efficacy of different science and chemistry courses for science-major and non-major students, and the question of chemistry's contribution to general education are evaluated. Chemistry and science curriculum are too profession- and consumer-oriented, and to overcome this problem, it is advised that all disciplines must incorporate the major…

  4. History of Chemistry.

    ERIC Educational Resources Information Center

    Servos, John W.

    1985-01-01

    Discusses the development of chemistry in the United States by considering: (1) chemistry as an evolving body of ideas/techniques, and as a set of conceptual resources affecting and affected by the development of other sciences; and (2) chemistry related to the history of American social and economic institutions and practices. (JN)

  5. Chemistry and Art.

    ERIC Educational Resources Information Center

    Berry, Martyn

    1999-01-01

    Describes a Chemistry and Art project developed for secondary students and teachers sponsored by the National Gallery and The Royal Society of Chemistry in the United Kingdom. Discusses aspects of the techniques used in creating five paintings as well as the chemistry involved in their making, deterioration, conservation, and restoration.…

  6. Environmental Chemistry Activities.

    ERIC Educational Resources Information Center

    Jackland, Thomas; And Others

    The authors of this curriculum supplement believe in a laboratory approach to chemistry and express the feeling that environmental chemistry provides the students an opportunity to apply theoretical chemistry to important practical problems. There are eighteen activities presented, each accompanied with behavioral objectives, one or more suggested…

  7. Chemistry on Stamps.

    ERIC Educational Resources Information Center

    Schreck, James O.

    1986-01-01

    Suggests how postage stamps can be incorporated into chemistry teaching. Categories considered include emergence of chemistry as a science, metric system, atoms (and molecules and ions), stoichiometry, energy relationships in chemical systems, chemical bonding, nuclear chemistry, biochemistry, geochemistry, matter (gases, liquids, and solids),…

  8. Green Chemistry and Education.

    ERIC Educational Resources Information Center

    Hjeresen, Dennis L.; Schutt, David L.; Boese, Janet M.

    2000-01-01

    Many students today are profoundly interested in the sustainability of their world. Introduces Green Chemistry and its principles with teaching materials. Green Chemistry is the use of chemistry for pollution prevention and the design of chemical products and processes that are environmentally benign. (ASK)

  9. Mechanisms in Photographic Chemistry

    ERIC Educational Resources Information Center

    Sahyun, M. R. V.

    1974-01-01

    Reviews current research interests in photographic chemistry, involving two proposed models for spectral sensitization of crystal defects and impurities in the photolysis reactivity and the mechanisms of development and complexation. Establishment of photographic chemistry in a chemistry curriculum is recommended. (CC)

  10. School Chemistry vs. Chemistry in Research: An Exploratory Experiment.

    ERIC Educational Resources Information Center

    Habraken, Clarisse L.; Buijs, Wim; Borkent, Hens; Ligeon, Willy; Wender, Harry; Meijer, Marijn

    2001-01-01

    Reports on a study exploring why students are not studying chemistry. Three groups of graduating high school students and their chemistry teachers stayed at a research institute working on molecular modeling and wrote essays on school chemistry versus chemistry in research. Concludes that school chemistry does not convey today's chemistry in…

  11. Light-emitting diodes for analytical chemistry.

    PubMed

    Macka, Mirek; Piasecki, Tomasz; Dasgupta, Purnendu K

    2014-01-01

    Light-emitting diodes (LEDs) are playing increasingly important roles in analytical chemistry, from the final analysis stage to photoreactors for analyte conversion to actual fabrication of and incorporation in microdevices for analytical use. The extremely fast turn-on/off rates of LEDs have made possible simple approaches to fluorescence lifetime measurement. Although they are increasingly being used as detectors, their wavelength selectivity as detectors has rarely been exploited. From their first proposed use for absorbance measurement in 1970, LEDs have been used in analytical chemistry in too many ways to make a comprehensive review possible. Hence, we critically review here the more recent literature on their use in optical detection and measurement systems. Cloudy as our crystal ball may be, we express our views on the future applications of LEDs in analytical chemistry: The horizon will certainly become wider as LEDs in the deep UV with sufficient intensity become available.

  12. Gene structure and regulation of alkane monooxygenases in propane-utilizing Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7.

    PubMed

    Kotani, Tetsuya; Kawashima, Yui; Yurimoto, Hiroya; Kato, Nobuo; Sakai, Yasuyoshi

    2006-09-01

    Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7 were isolated from soil samples as propane-utilizing bacteria and were found to be able to utilize various gaseous and liquid n-alkanes as carbon and energy sources. One gene cluster, M-prmABCD, and two gene clusters, P-prm1ABCD and P-prm2ABCD, were cloned from the genomes of Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7, respectively. These gene clusters are homologous to the gene cluster encoding the multicomponent propane monooxygenase (prmABCD) of Gordonia sp. TY-5. The expression of prm gene clusters in Mycobacterium sp. TY-6 and Pseudonocardia sp. TY-7 was shown to be induced by gaseous n-alkanes (C2-C4) except methane, suggesting that the products of these genes are involved in gaseous n-alkane oxidation. Homologous genes for an alkane hydroxylase system (alk system) involved in liquid n-alkane oxidation were also cloned from the genomic DNA of Mycobacterium sp. TY-6. The alk gene cluster was transcribed in response to liquid n-alkanes (C11-C15). These results indicate that Mycobacterium sp. TY-6 has two distinct gene clusters for multicomponent monooxygenases involved in alkane oxidation. Whole-cell reactions revealed that propane is oxidized to 1-propanol through terminal oxidation in Mycobacterium sp. TY-6 and that propane is oxidized to 1-propanol and 2-propanol through both terminal and subterminal oxidations in Pseudonocardia sp. TY-7. This study reveals the diversity of propane metabolism present in microorganisms. PMID:17046531

  13. Evaluating the potential of long chain n-alkanes and n-carboxylic acids as biomarkers for past vegetation

    NASA Astrophysics Data System (ADS)

    Lanny, Verena; Zech, Roland; Eglinton, Timothy

    2014-05-01

    Leaf waxes, such as long chain n-alkanes and n-carboxylic acids, may have a great potential for the reconstruction of past environmental and climate conditions (e.g. (Zech R. et al., 2013). While n-C27 and n-C29 alkanes often predominantly occur in trees and shrubs, n-C31 and n-C33 are more abundant in grasses and herbs. However, little is known about chain-length distributions of n-carboxylic acids, and very few studies have systematically investigated leaf waxes in top soils. We analyzed n-alkanes and n-carboxylic acids in ~100 litter and topsoil samples from Southern Germany to Sweden. Our results show that sites under deciduous trees often contain a lot of C27 n-alkanes and C28 n-carboxylic acids. Coniferous sites are characterized by dominance in n-alkanes C29 and C31 and have relatively high concentrations of n-carboxylic acids C22 and C24. Grass sites show a Cmax at C31 for n-alkanes and at C24 or C26 for n-carboxylic acids. Differences in homologue patterns are most pronounced in the litter samples, but are well preserved also in the topsoils (0-3 cm depth, a little less in the lower topsoils from 3-10 cm). Our results illustrate the potential of combining n-alkane and n-carboxylic acid analyses for paleo-vegetation reconstructions, yet indicate that the degree of degradation may have to be taken into consideration (Zech M. et al., 2013). References: Zech, M. et al. (2013) Quat. Int. 296, 108-116. Zech, R. et al. (2013) Palaeo3, 387, 165-175.

  14. The Conversation Class

    ERIC Educational Resources Information Center

    Jackson, Acy L.

    2012-01-01

    The conversation class occupies a unique place in the process of learning English as a second or foreign language. From the author's own experience in conducting special conversation classes with Persian-speaking adults, he has drawn up a number of simple but important guidelines, some of which he hopes may provide helpful suggestions for the…

  15. NUCLEAR CONVERSION APPARATUS

    DOEpatents

    Seaborg, G.T.

    1960-09-13

    A nuclear conversion apparatus is described which comprises a body of neutron moderator, tubes extending therethrough, uranium in the tubes, a fluid- circulating system associated with the tubes, a thorium-containing fluid coolant in the system and tubes, and means for withdrawing the fluid from the system and replacing it in the system whereby thorium conversion products may be recovered.

  16. Energy conversion alternatives study

    NASA Technical Reports Server (NTRS)

    Shure, L. T.

    1979-01-01

    Comparison of coal based energy systems is given. Study identifies and compares various advanced energy conversion systems using coal or coal derived fuels for baselaoad electric power generation. Energy Conversion Alternatives Study (ECAS) reports provede government, industry, and general public with technically consistent basis for comparison of system's options of interest for fossilfired electric-utility application.

  17. Common conversion factors.

    PubMed

    2001-05-01

    This appendix presents tables of some of the more common conversion factors for units of measure used throughout Current Protocols manuals, as well as prefixes indicating powers of ten for SI units. Another table gives conversions between temperatures on the Celsius (Centigrade) and Fahrenheit scales. PMID:18770653

  18. Assessment through Conversation.

    ERIC Educational Resources Information Center

    Fu, Danling; Lamme, Linda L.

    2002-01-01

    Presents conversations with parents, teachers, and children around portfolios that provide a better picture of a child's growth and understanding than standardized test scores ever can. Concludes that the involvement of students, teachers, and parents in conversation about children's literacy development brings the potential of a common vision and…

  19. Conversion of methane to higher hydrocarbons in ac nonequilibrium plasmas

    SciTech Connect

    Thanyachotpaiboon, K.; Chavadej; Caldwell, T.A.; Lobban, L.L.; Mallinson, R.G.

    1998-10-01

    The effects of plasma chemistry on the conversion of methane were studied using a dielectric barrier discharge reactor at ambient temperatures. A dielectric barrier discharge reactor generates a nonequilibrium plasma when a sufficiently high voltage is applied across the reactor`s electrodes. Methane molecules are activated at this temperature and coupled to form C{sub 2} hydrocarbons, higher hydrocarbons, and hydrogen. The study on the effect of voltage, residence time and third bodies on methane conversion and product selectivity shows that methane conversion initially increases with increasing voltage and residence time above the breakdown voltage, and product selectivities are essentially independent of the voltage. Production of hydrogen during the reaction limits olefin production. Methane conversion also increases when helium and ethane are in the feed stream. Helium and ethane both appear to be more easily activated than methane and enhance methane activation and conversion.

  20. HOCO radical chemistry.

    PubMed

    Francisco, Joseph S; Muckerman, James T; Yu, Hua-Gen

    2010-12-21

    Free radicals are important species in atmospheric chemistry, combustion, plasma environments, interstellar clouds, and biochemistry. Therefore, researchers would like to understand the formation mechanism, structure, stability, reactivity, spectroscopy, and dynamics of these chemical species. However, due to the presence of one or more unpaired electrons, radicals are often very reactive and have short lifetimes, which makes it difficult to conduct experiments. The HOCO radical appears in the atmosphere as well as in combustion environments and plays an important role in the conversion of CO to CO(2). Through the interplay between theoretical and experimental investigations, researchers have only recently understood the chemical role of the HOCO radical. In this Account, we systematically describe the current state of knowledge of the HOCO radical based on recent theoretical and experimental studies. This radical's two stable conformers, trans- and cis-HOCO, have been identified by high-level ab initio calculations and experimental spectroscopy. trans-HOCO is more stable by approximately 1.8 kcal/mol. The heat of formation of HOCO (298 K) was determined to be -43.0 ± 0.5 kcal/mol, giving a potential well depth of 30.1 ± 0.5 kcal/mol relative to the asymptote of the reactants OH + CO. The HOCO radical is very reactive. In most reactions between the HOCO radical and atoms, the HOCO radical acts as a hydrogen donor to reaction partners. Generally, the hydrogen is transferred through the formation of an association intermediate, which then proceeds through a molecular elimination step to produce the reaction products. The reaction rates of HOCO with some small radicals fall in the range of 10(-11)-10(-10) cm(3) molecule(-1) s(-1). These results clearly illustrate important features in the reactivity of the HOCO radical with other molecules.