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Sample records for 1-butene 2-methylpropene trans-2-butene

  1. Metabolism of 2-Methylpropene (Isobutylene) by the Aerobic Bacterium Mycobacterium sp. Strain ELW1

    PubMed Central

    Kottegoda, Samanthi; Waligora, Elizabeth

    2015-01-01

    An aerobic bacterium (Mycobacterium sp. strain ELW1) that utilizes 2-methylpropene (isobutylene) as a sole source of carbon and energy was isolated and characterized. Strain ELW1 grew on 2-methylpropene (growth rate = 0.05 h−1) with a yield of 0.38 mg (dry weight) mg 2-methylpropene−1. Strain ELW1 also grew more slowly on both cis- and trans-2-butene but did not grow on any other C2 to C5 straight-chain, branched, or chlorinated alkenes tested. Resting 2-methylpropene-grown cells consumed ethene, propene, and 1-butene without a lag phase. Epoxyethane accumulated as the only detected product of ethene oxidation. Both alkene consumption and epoxyethane production were fully inhibited in cells exposed to 1-octyne, suggesting that alkene oxidation is initiated by an alkyne-sensitive, epoxide-generating monooxygenase. Kinetic analyses indicated that 1,2-epoxy-2-methylpropane is rapidly consumed during 2-methylpropene degradation, while 2-methyl-2-propen-1-ol is not a significant metabolite of 2-methylpropene catabolism. Degradation of 1,2-epoxy-2-methylpropane by 2-methylpropene-grown cells led to the accumulation and further degradation of 2-methyl-1,2-propanediol and 2-hydroxyisobutyrate, two sequential metabolites previously identified in the aerobic microbial metabolism of methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA). Growth of strain ELW1 on 2-methylpropene, 1,2-epoxy-2-methylpropane, 2-methyl-1,2-propanediol, and 2-hydroxyisobutyrate was fully inhibited when cobalt ions were omitted from the growth medium, while growth on 3-hydroxybutyrate and other substrates was unaffected by the absence of added cobalt ions. Our results suggest that, like aerobic MTBE- and TBA-metabolizing bacteria, strain ELW1 utilizes a cobalt/cobalamin-dependent mutase to transform 2-hydroxyisobutyrate. Our results have been interpreted in terms of their impact on our understanding of the microbial metabolism of alkenes and ether oxygenates. PMID:25576605

  2. Interactions of Molecules with cis and trans Double Bonds: A Theoretical Study of cis- and trans-2-Butene.

    PubMed

    Zarić, Milana M; Bugarski, Branko; Kijevčanin, Mirjana Lj

    2016-01-18

    Noncovalent interactions of cis- and trans-2-butene, as the smallest model systems of molecules with cis and trans double bonds, were studied to find potential differences in interactions of these molecules. The study was performed using quantum chemical methods including very accurate CCSD(T)/CBS method. We studied parallel and displaced parallel interactions in 2-butene dimers, in butane dimers, and between 2-butene and saturated butane. The results show the trend that interactions of 2-butene with butane are the strongest, followed by interactions in butane dimers, whereas the interaction in 2-butene dimers are the weakest. The strongest calculated interaction energy is between trans-2-butene and butane, with a CCSD(T)/CBS energy of -2.80 kcal mol(-1) . Interactions in cis-2-butene dimers are stronger than interactions in trans-2-butene dimers. Interestingly, some of the interactions involving 2-butene are as strong as interactions in a benzene dimer. These insights into interactions of cis- and trans-2-butene can improve understanding of the properties and processes that involve molecules with cis and trans double bonds, such as fatty acids and polymers.

  3. Production of stabilized Criegee intermediates and peroxides in the gas phase ozonolysis of alkenes: 1. Ethene, trans-2-butene, and 2,3-dimethyl-2-butene

    NASA Astrophysics Data System (ADS)

    Hasson, Alam S.; Orzechowska, Grazyna; Paulson, Suzanne E.

    2001-12-01

    Ozone-alkene reactions generate stabilized Criegee intermediates (of the form R1R2COO), which are believed to react with water molecules to form organic hydroperoxides, hydrogen peroxide and carboxylic acids. These reactions are thought to be significant sources of these environmentally important compounds, yet both the yields of stabilized Criegee intermediates and the branching ratios from their reaction with water are not well known. The formation of hydrogen peroxide and organic hydroperoxides was investigated in the gas phase ozonolysis of ethene, trans-2-butene, and 2,3-dimethyl-2-butene for relative humidities (RH) from 0 and 80% by gas chromatography with flame ionization detection and high-performance liquid chromatography with fluorescence detection. Additionally, yields of acetaldehyde and acetic acid from trans-2-butene and acetone from 2,3-dimethyl-2-butene were measured. The reactions of stabilized Criegee intermediates with water were found to proceed almost entirely via organic hydroperoxide or hydrogen peroxide formation with little acid formation. Stabilized Criegee intermediate yields of 0.39, 0.24, and 0.10 were obtained for ethene, trans-2-butene, and 2,3-dimethyl-2-butene, respectively.

  4. The Bond Dissociation Energies of 1-Butene

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R. (Technical Monitor)

    1994-01-01

    The bond dissociation energies of 1-butene and several calibration systems are computed using the G2(MP2) approach. The agreement between the calibration systems and experiment is very good. The computed values for 1-butene are compared with calibration systems and the agreement between the computed results for 1-butene and the "rule of thumb" values from the smaller systems is remarkably good.

  5. Isolation of 3-methyl-1-butene from a hydrocarbon stream

    SciTech Connect

    Drake, C.A.

    1986-08-19

    A process is described for recovering 3-methyl-1-butene from a hydrocarbon stream containing 3-methyl-1-butene and 2-butyne which forms an azeotrope with 3-methyl-1-butene the process comprising contacting the stream with sulfuric acid having a concentration ranging from 70 to 85 weight percent to form a soluble fraction containing the 2-butyne and the sulfuric acid and an insoluble fraction which contains the 3-methyl-1-butene and recovering the 3-methyl-1-butene through conventional separation techniques.

  6. Adsorption of oxygen and 1-butene on magnesium ferrite

    SciTech Connect

    Samuilova, O.K.; Kozlova, M.M.; Yagodovskii, V.D.

    1986-08-01

    The kinetics of the adsorption of oxygen and 1-butene on magnesium ferrite was studied. Conductometry and thermal desorption methods were used to investigate the adsorption of oxygen on magnesium ferrite. Two forms of adsorbed oxygen were found. The formation of these forms affects the kinetics of the adsorption of 1-butene.

  7. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... of 1-butene liquid monomer. Butene/ethylene copolymers are produced by the catalytic polymerization of 1-butene liquid monomer in the presence of small amounts of ethylene monomer so as to yield no..._regulations/ibr_locations.html. (iii) Density. Poly-1-butene resins have a density of 0.904 to 0.920...

  8. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Poly-1-butene resins and butene/ethylene...-butene resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers... contact with food subject to the provisions of this section. (a) Identity. Poly-1-butene resins...

  9. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly-1-butene resins and butene/ethylene copolymers... resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers identified... with food subject to the provisions of this section. (a) Identity. Poly-1-butene resins are produced...

  10. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Poly-1-butene resins and butene/ethylene...-butene resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers... produced by the catalytic polymerization of 1-butene liquid monomer. Butene/ethylene copolymers...

  11. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Poly-1-butene resins and butene/ethylene...-butene resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers... produced by the catalytic polymerization of 1-butene liquid monomer. Butene/ethylene copolymers...

  12. Kinetic Partitioning of 1-Butene Defect in Random Propylene 1-Butene Copolymers by Time-Resolved FTIR

    NASA Astrophysics Data System (ADS)

    Ruiz-Orta, Carolina; Alamo, Rufina G.

    2011-03-01

    Two different types of regularity bands are identified in a time-resolved FTIR crystallization of a series of random isotactic propylene 1-butene copolymers with a concentration of 1-butene from 2 to 19 mol%. The first type are bands associated with 31 helices of isotactic sequences of different n length (n, number of monomer units). The second are regularity bands at 830, 920, 1010 and 1240 cm-1 associated with continuous sequences of the chain that include the 1-butene comonomer. Conformational changes during the isothermal crystallization process were monitored with these regularity bands. The variation of the intensity of regularity band at 920 cm-1 with crystallinity content and a shift of the 841 cm-1 (n = 12) at lower frequencies correlate with the content of comonomer included in the crystal. Changes in frequency of the n = 12 band with varying crystallization temperature (Tc), and with crystallization time at a fixed Tc are associated with the kinetic partitioning of the comonomer units, that was quantified with data obtained from 13C NMR. The frequency shift is absent in copolymers with co-units that are excluded from the crystalline regions, such as the 1-octene comonomer.

  13. Catalytic cracking process utilizing an iso-olefin enhancer catalyst additive

    SciTech Connect

    Haag, W.O.; Harandi, M.N.; Owen, H.

    1993-08-10

    A fluid catalytic cracking process is described for upgrading C[sub 9] + aromatic containing feeds to produce gasoline, distillate, and C[sub 4] olefins, including 1-butene, cis-2-butene, trans-2-butene, in a fluid catalytic cracking unit which includes a riser, a stripping unit and a regenerator, wherein the process comprises: (a) cracking a C[sub 9] + containing feed, selected from the group consisting of gas oil, resid and admixtures thereof, in a riser in the presence of a first catalyst component, under fluid catalytic cracking conditions, wherein the first catalyst component comprises an amorphous cracking catalyst, a large pore crystalline cracking catalyst or admixtures thereof, to provide gasoline boiling range components, and an amount of C[sub 4] olefins in a first product mixture; wherein the fluid catalytic cracking conditions include a riser top temperature within the range of from 950-1,150 F, a catalyst to feed ratio from 3:1-10:1, and a catalyst contact time from 0.5-10 seconds; (b) contacting said first product mixture with a second catalyst component which comprises ZSM-23, under conditions effective to increase isomerization, with no significant oligomerization to heavier molecules, of at least one of C[sub 4] olefins to 2-methylpropene, with no significant oligomerization to heavier molecules, and recovering a second product mixture which contains amounts of 2-methylpropene greater than that in the first effluent, wherein the conditions of the vapor phase catalytic isomerization of the 1-butene, cis-2-butene, and trans-2-butene to the isobutylene include a temperature within the range of from 950-1,150 F, a catalyst to feed ratio of from 3:1-10:1, and a catalyst contact time from 0.5-10 seconds.

  14. Radical product yields from the ozonolysis of short chain alkenes under atmospheric boundary layer conditions.

    PubMed

    Alam, Mohammed S; Rickard, Andrew R; Camredon, Marie; Wyche, Kevin P; Carr, Timo; Hornsby, Karen E; Monks, Paul S; Bloss, William J

    2013-11-27

    The gas-phase reaction of ozone with unsaturated volatile organic compounds (VOCs), alkenes, is an important source of the critical atmospheric oxidant OH, especially at night when other photolytic radical initiation routes cannot occur. Alkene ozonolysis is also known to directly form HO2 radicals, which may be readily converted to OH through reaction with NO, but whose formation is poorly understood. We report a study of the radical (OH, HO2, and RO2) production from a series of small alkenes (propene, 1-butene, cis-2-butene, trans-2-butene, 2-methylpropene, 2,3-dimethyl-2-butene (tetramethyl ethene, TME), and isoprene). Experiments were performed in the European Photoreactor (EUPHORE) atmospheric simulation chamber, with OH and HO2 levels directly measured by laser-induced fluorescence (LIF) and HO2 + ΣRO2 levels measured by peroxy-radical chemical amplification (PERCA). OH yields were found to be in good agreement with the majority of previous studies performed under comparable conditions (atmospheric pressure, long time scales) using tracer and scavenger approaches. HO2 yields ranged from 4% (trans-2-butene) to 34% (2-methylpropene), lower than previous experimental determinations. Increasing humidity further reduced the HO2 yields obtained, by typically 50% for an RH increase from 0.5 to 30%, suggesting that HOx production from alkene ozonolysis may be lower than current models suggest under (humid) ambient atmospheric boundary layer conditions. The mechanistic origin of the OH and HO2 production observed is discussed in the context of previous experimental and theoretical studies.

  15. Selective Dimerization of Ethylene to 1-Butene with a Porous Catalyst.

    PubMed

    Metzger, Eric D; Brozek, Carl K; Comito, Robert J; Dincă, Mircea

    2016-03-23

    Current heterogeneous catalysts lack the fine steric and electronic tuning required for catalyzing the selective dimerization of ethylene to 1-butene, which remains one of the largest industrial processes still catalyzed by homogeneous catalysts. Here, we report that a metal-organic framework catalyzes ethylene dimerization with a combination of activity and selectivity for 1-butene that is premier among heterogeneous catalysts. The capacity for mild cation exchange in the material MFU-4l (MFU-4l = Zn5Cl4(BTDD)3, H2BTDD = bis(1H-1,2,3-triazolo[4,5-b],[4',5'-i])dibenzo[1,4]dioxin) was leveraged to create a well-defined and site-isolated Ni(II) active site bearing close structural homology to molecular tris-pyrazolylborate complexes. In the presence of ethylene and methylaluminoxane, the material consumes ethylene at a rate of 41,500 mol per mole of Ni per hour with a selectivity for 1-butene of up to 96.2%, exceeding the selectivity reported for the current industrial dimerization process.

  16. Selective Dimerization of Ethylene to 1-Butene with a Porous Catalyst

    PubMed Central

    2016-01-01

    Current heterogeneous catalysts lack the fine steric and electronic tuning required for catalyzing the selective dimerization of ethylene to 1-butene, which remains one of the largest industrial processes still catalyzed by homogeneous catalysts. Here, we report that a metal–organic framework catalyzes ethylene dimerization with a combination of activity and selectivity for 1-butene that is premier among heterogeneous catalysts. The capacity for mild cation exchange in the material MFU-4l (MFU-4l = Zn5Cl4(BTDD)3, H2BTDD = bis(1H-1,2,3-triazolo[4,5-b],[4′,5′-i])dibenzo[1,4]dioxin) was leveraged to create a well-defined and site-isolated Ni(II) active site bearing close structural homology to molecular tris-pyrazolylborate complexes. In the presence of ethylene and methylaluminoxane, the material consumes ethylene at a rate of 41,500 mol per mole of Ni per hour with a selectivity for 1-butene of up to 96.2%, exceeding the selectivity reported for the current industrial dimerization process. PMID:27163041

  17. The infrared spectra of spiropentane methylenecyclobutane and 2-methyl-1-butene

    NASA Technical Reports Server (NTRS)

    Cleaves, Alden P; Sherrick, Mildred E

    1946-01-01

    The infrared spectra of spiropentane, methylenecyclobutane, and 2-methyl-1-butene were measured in the region from 3 to 14 microns with a rock salt prism spectrometer of medium dispersion. The pure samples were prepared at the NACA Cleveland Laboratory. The vapors of these three C5 hydrocarbons were investigated at room temperature and at pressures in the range from 80 to 300 millimeters of mercury absolute in a 10-centimeter cell. The spectra were compared with each other and with Ramon spectra for the same compounds.

  18. SAXS/WAXS studies of flow-induced crystallization of poly(1-butene) in shear flow

    NASA Astrophysics Data System (ADS)

    Luo, Binbin; Burghardt, Wesley

    2013-03-01

    Flow-induced crystallization of poly(1-butene) was studied in shear flow. Flow was produced using a Linkam shear cell that has been modified to allow x-ray access for in situ studies of polymer structure using synchrotron x-ray scattering techniques. After loading in the the shear cell, samples were first heated well into the melt, and then cooled to a crystallization temperature selected such that negligible quiescent crystallization would occur on reasonable time scales. A short burst of shear flow was then applied at various rates, after which simultaneous wide- and small-angle x-ray scattering (SAXS and WAXS) data were collected to study the resulting accelerated crystallization kinetics, as well as the morphology of the resulting crystallites (e.g. degree of crystallite orientation). The impact of both deformation rate and total applied strain on the crystallization process were examined.

  19. Photoelectron and electron momentum spectroscopy of 1-butene at benchmark theoretical levels

    NASA Astrophysics Data System (ADS)

    Shojaei, S. H. Reza; Morini, Filippo; Hajgató, Bálazs; Deleuze, Michael S.

    2011-12-01

    The results of experimental studies of the valence electronic structure of 1-butene employing photoelectron spectroscopy as well as electron momentum spectroscopy are interpreted on the ground of quantitative calculations of one-electron and shake-up ionization energies and of the related Dyson orbitals, using one-particle Green's function theory in conjunction with the third-order algebraic diagrammatic construction scheme (ADC(3)). Comparison is made with simulations of (e, 2e) electron momentum distributions obtained from standard (B3LYP) Kohn-Sham orbitals. Our analysis is based on highly quantitative determinations of the energy difference between the cis and gauche (C1) conformers, within ~0.02 kcal mol-1 accuracy, and a thermostatistical evaluation thereby of conformer weights beyond the level of the rigid rotor harmonic oscillator approximation. Relative entropies are found to be particularly sensitive to hindered rotations. The shake-up onset is located at 15.9 eV, and the orbital picture of ionization breaks down completely at electron binding energies above 19 eV. If the available experimental momentum profiles demonstrate the dominance of the C1 conformer, they are in this case clearly not sensitive enough to the molecular conformation for evaluating conformer abundances with accuracies better than 10% due to the limited energy and momentum resolutions and likely physical complications.

  20. SAXS/WAXS studies of shear-induced crystallization of poly(1-butene)

    NASA Astrophysics Data System (ADS)

    Kweon, Mu Sung; Luo, Binbin; Burghardt, Wesley

    Flow-induced crystallization of poly(1-butene) was studied in shear flow. Flow was produced using a Linkam shear cell that has been modified to allow x-ray access for in situ studies of polymer structure using synchrotron x-ray scattering techniques. After loading in the shear cell, samples were first heated well into the melt, and then cooled to a crystallization temperature selected such that negligible quiescent crystallization would occur on reasonable time scales. A short burst of shear flow was then applied at various rates, after which simultaneous wide- and small-angle x-ray scattering (WAXS and SAXS, respectively) data were collected to study the impact of both deformation rate and total applied strain on accelerated crystallization kinetics as well as the morphology of the resulting crystallites (e.g. degree of crystallite orientation). SAXS and WAXS data generally showed qualitative agreement in measures of the extent of crystallization and the degree of crystallite orientation. Average crystallite orientation was found to decrease over the course of crystallization. The crystalline volume fraction in the sample was calculated from the (i) SAXS invariant and (ii) integrated WAXS intensity profile to quantify the extent to which the sample crystallized at various flow c

  1. Early Stages in Polymer Crystal Growth for Isotactic Poly-1-Butene: From Nucleation to Network Percolation

    NASA Astrophysics Data System (ADS)

    Arora, Deepak; Winter, Horst

    2010-03-01

    Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. An attempt is made to connect the crystal fraction inside spherulites with the average crystallinity of the entire sample. The crystal fraction inside spherulites is very small initially but increases with time and catches up with the sample crystallinity later on. Experiments include optical microscopy, DSC, SALS, and rheology. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by rheology, is not caused by packing/jamming of spherulites but by the formation of a percolating structure. Impingement of pairs of spherulites occurs already much before percolation. This makes it difficult to predict crystal growth and define spherulitic impingement for the whole sample. At percolation, the absolute crystallinity is about 7-8 vol%. This shows that spherulites are mostly amorphous before impingement.

  2. Direct fabrication of porous isotactic poly-1-butene with form I from the melt using CO2.

    PubMed

    Li, Lei; Liu, Tao; Zhao, Ling

    2011-11-15

    The deformation of isotactic poly-1-butene (iPB-1) matrix, during the CO(2) -assisted foaming process, makes the iPB-1 melt crystallize into form I rather than form I', which crystallizes after annealing under high-pressure CO(2) without foaming. The result provides a new strategy to directly obtain porous iPB-1 with stable form I from iPB-1 melt.

  3. Influence of vibration of a catalyst bed on the adsorption of 1-butene on a bismuth-molybdenum catalyst

    SciTech Connect

    Barannik, G.B.; Valkov, V.; Ven'yaminov, S.A.; Schnabel, K.H.

    1982-04-01

    In a study of the thermodesorption of 1-butene on bismuth molybdates (..cap alpha..- and ..gamma..-phases), it was discovered that vibration of the catalyst bed during the adsorption of 1-butene at 30/sup 0/C results in the formation of divinyl, which is not observed in the absence of vibration. A vibrationally fluidized catalyst bed has been used to eliminate the temperature gradient over the bed, and the details of the procedure were described previously. The conclusion that divinyl forms was drawn on the basis of thermodesorption data and comfirmed by chromatographic analysis of the gaseous phase during adsorption. The thermodesorption spectrum obtained with vibration of the catalyst during adsorption differs from the spectrum for the case of adsorption without vibration and is similar to the spectrum obtained following the adsorption of divinyl. By varying the vibration time, it is possible to obtain spectra occupying intermediate positions. This phenomenon is due to the readsorption of divinyl formed during the adsorption of 1-butene and is observed only in cases in which the vibration of the catalyst was carried out in the adsorption step.

  4. Butene concentration prediction in ethylene/propylene/1-butene terpolymers by FT-IR spectroscopy through multivariate statistical analysis and artificial neural networks.

    PubMed

    Marengo, Emilio; Longo, Valentina; Bobba, Marco; Robotti, Elisa; Zerbinati, Orfeo; Di Martino, Silvana

    2009-01-15

    This paper reports the development of calibration models for quality control in the production of ethylene/propylene/1-butene terpolymers by the use of multivariate tools and FT-IR spectroscopy. 1-Butene concentration prediction is achieved in terpolymers by coupling FT-IR spectroscopy to multivariate regression tools. A dataset of 26 terpolymers (14 coming from a constrained experimental design for mixtures, plus 12 terpolymers used for external validation) was analysed by FT-IR spectroscopy. An internal method of "Polimeri Europa" plant, based on (13)C NMR spectroscopy is used to determine the percentage of 1-butene in the samples. Then, different multivariate tools are used for 1-butene concentration prediction based on the FT-IR spectra recorded. Different multivariate calibration methods were explored: principal component regression (PCR), partial least squares (PLS), stepwise OLS regression (SWR) and artificial neural networks (ANNs). The model obtained by back-propagation neural networks turned out to be the best one. The performances of the BP-ANN model were further improved by variable selection procedures based on the calculation of the first derivative of the network. The proposed approach allows the monitoring in real time of the polymer synthesis and the estimation of the characteristics of the product attainable from the concentration of 1-butene.

  5. SAXS/WAXS studies of flow-induced crystallization of poly(1-butene) in uniaxial extensional flow

    NASA Astrophysics Data System (ADS)

    McCready, Erica; Burghardt, Wesley

    2013-03-01

    We report studies of flow-induced crystallization of poly(1-butene) in uniaxial extensional flow. Flow was produced using an SER extensional flow fixture housed in a custom built convection oven designed to provide x-ray access for in situ studies of polymer structure using synchrotron x-ray scattering techniques. Samples were loaded into the SER fixture, heated well into the melt, and then cooled to a temperature at which quiescent crystallization would be prohibitively slow. A short interval of uniaxial extensional flow was then applied, after which simultaneous wide- and small-angle x-ray scattering (SAXS and WAXS) patterns were collected to study the phase transformation kinetics and morphology of the subsequent accelerated crystallization. The impact of both deformation rate and total applied strain on the crystallization process were examined.

  6. ZSM-5 with controllable acidity as an efficient catalyst for a highly adjustable propene/ethene ratio in the 1-butene cracking.

    PubMed

    Zhao, Shufang; Yang, Di; Zhang, Xiaowei; Yao, Xuting; Liu, Yueming; He, Mingyuan

    2016-09-28

    A facile strategy was proposed to realize the precise control of zeolitic acidity by selective cracking of a silane with an acid site. Modified ZSM-5 with controllable acidity brought about a highly adjustable propene/ethene (P/E) ratio in the 1-butene cracking. PMID:27506458

  7. Synthesis of Lipid Based Polyols from 1-butene Metathesized Palm Oil for Use in Polyurethane Foam Applications

    NASA Astrophysics Data System (ADS)

    Sasidharan Pillai, Prasanth Kumar

    This thesis explores the use of 1-butene cross metathesized palm oil (PMTAG) as a feedstock for preparation of polyols which can be used to prepare rigid and flexible polyurethane foams. PMTAG is advantageous over its precursor feedstock, palm oil, for synthesizing polyols, especially for the preparation of rigid foams, because of the reduction of dangling chain effects associated with the omega unsaturated fatty acids. 1-butene cross metathesis results in shortening of the unsaturated fatty acid moieties, with approximately half of the unsaturated fatty acids assuming terminal double bonds. It was shown that the associated terminal OH groups introduced through epoxidation and hydroxylation result in rigid foams with a compressive strength approximately 2.5 times higher than that of rigid foams from palm and soybean oil polyols. Up to 1.5 times improvement in the compressive strength value of the rigid foams from the PMTAG polyol was further obtained following dry and/or solvent assisted fractionation of PMTAG in order to reduce the dangling chain effects associated with the saturated components of the PMTAG. Flexible foams with excellent recovery was achieved from the polyols of PMTAG and the high olein fraction of PMTAG indicating that these bio-derived polyurethane foams may be suitable for flexible foam applications. PMTAG polyols with controlled OH values prepared via an optimized green solvent free synthetic strategy provided flexible foams with lower compressive strength and higher recovery; i.e., better flexible foam potential compared to the PMTAG derived foams with non-controlled OH values. Overall, this study has revealed that the dangling chain issues of vegetable oils can be addressed in part using appropriate chemical and physical modification techniques such as cross metathesis and fractionation, respectively. In fact, the rigidity and the compressive strength of the polyurethane foams were in very close agreement with the percentage of terminal

  8. SAXS/WAXS studies of flow-induced crystallization of poly(1-butene) in uniaxial extensional flow

    NASA Astrophysics Data System (ADS)

    McCready, Erica; Burghardt, Wesley

    2014-03-01

    We report studies of flow-induced crystallization of poly(1-butene) in uniaxial extensional flow. Flow was produced using an SER extensional flow fixture housed in a custom built convection oven designed to provide x-ray access for in situ studies of polymer structure using synchrotron x-ray scattering techniques. Samples were loaded into the SER fixture, heated well into the melt, and then cooled to a temperature at which quiescent crystallization would be prohibitively slow. A short interval of uniaxial extensional flow was then applied, after which simultaneous wide- and small-angle x-ray scattering (SAXS and WAXS) patterns were collected to study the phase transformation kinetics and morphology of the subsequent accelerated crystallization. The degree of crystallite orientation was generally found to decrease over the course of the crystallization. WAXS measurements yielded systematically higher degrees of crystallite orientation than SAXS. Both SAXS and WAXS gave generally consistent results for the extent of crystallization, although the SAXS invariant showed a decrease at long times that is not mirrored in the WAXS data. The impact of both deformation rate and total applied strain on the crystallization process were examined.

  9. Electrical conductivity and equation of state of liquid nitrogen, oxygen, benzene, and 1-butene shocked to 60 GPa

    SciTech Connect

    Hamilton, D.C.

    1986-10-08

    Measurements are reported for the electrical conductivity of liquid nitrogen (N/sub 2/), oxygen (O/sub 2/) and benzene (C/sub 6/H/sub 6/), and Hugoniot equation of state of liquid 1-butene (C/sub 4/H/sub 8/) under shock compressed conditions. The conductivity data span 7 x 10/sup -4/ to 7 x 10/sup 1/ ..cap omega../sup -1/cm/sup -1/ over a dynamic pressure range 18.1 to 61.5 GPa and are discussed in terms of amorphous semiconduction models which include such transport phenomena as hopping, percolation, pseudogaps, and metallization. Excellent agreement is found between the equation-of-state measurements, which span a dynamic pressure range 12.3 to 53.8 GPa, and Ree's calculated values which assume a 2-phase mixture consisting of molecular hydrogen and carbon in a dense diamond-like phase. There is a 2-1/2 fold increase in the thermal pressure contribution over a less dense, stoichiometrically equivalent liquid. 90 refs., 48 figs., 8 tabs.

  10. Evaluated kinetics of terminal and non-terminal addition of hydrogen atoms to 1-alkenes: a shock tube study of H + 1-butene.

    PubMed

    Manion, Jeffrey A; Awan, Iftikhar A

    2015-01-22

    Single-pulse shock tube methods have been used to thermally generate hydrogen atoms and investigate the kinetics of their addition reactions with 1-butene at temperatures of 880 to 1120 K and pressures of 145 to 245 kPa. Rate parameters for the unimolecular decomposition of 1-butene are also reported. Addition of H atoms to the π bond of 1-butene results in displacement of either methyl or ethyl depending on whether addition occurs at the terminal or nonterminal position. Postshock monitoring of the initial alkene products has been used to determine the relative and absolute reaction rates. Absolute rate constants have been derived relative to the reference reaction of displacement of methyl from 1,3,5-trimethylbenzene (135TMB). With k(H + 135TMB → m-xylene + CH3) = 6.7 × 10(13) exp(-3255/T) cm(3) mol(-1) s(-1), we find the following: k(H + 1-butene → propene + CH3) = k10 = 3.93 × 10(13) exp(-1152 K/T) cm(3) mol(-1) s(-1), [880-1120 K; 145-245 kPa]; k(H + 1-butene → ethene + C2H5) = k11 = 3.44 × 10(13) exp(-1971 K/T) cm(3) mol(-1) s(-1), [971-1120 K; 145-245 kPa]; k10/k11 = 10((0.058±0.059)) exp [(818 ± 141) K/T), 971-1120 K. Uncertainties (2σ) in the absolute rate constants are about a factor of 1.5, while the relative rate constants should be accurate to within ±15%. The displacement rate constants are shown to be very close to the high pressure limiting rate constants for addition of H, and the present measurements are the first direct determination of the branching ratio for 1-olefins at high temperatures. At 1000 K, addition to the terminal site is favored over the nonterminal position by a factor of 2.59 ± 0.39, where the uncertainty is 2σ and includes possible systematic errors. Combining the present results with evaluated data from the literature pertaining to temperatures of <440 K leads us to recommend the following: k∞(H + 1-butene → 2-butyl) = 1.05 × 10(9)T(1.40) exp(-366/T) cm(3) mol(-1) s(-1), [220-2000 K]; k∞(H + 1-butene → 1

  11. Comparison of two-body and three-body decomposition of ethanedial, propanal, propenal, n-butane, 1-butene, and 1,3-butadiene

    NASA Astrophysics Data System (ADS)

    Chin, Chih-Hao; Lee, Shih-Huang

    2012-01-01

    We investigated two-body (binary) and three-body (triple) dissociations of ethanedial, propanal, propenal, n-butane, 1-butene, and 1,3-butadiene on the ground potential-energy surfaces using quantum-chemical and Rice-Ramsperger-Kassel-Marcus calculations; most attention is paid on the triple dissociation mechanisms. The triple dissociation includes elimination of a hydrogen molecule from a combination of two separate terminal hydrogen atoms; meanwhile, the rest part simultaneously decomposes to two stable fragments, e.g., C2H4, C2H2, or CO. Transition structures corresponding to the concerted triple dissociation were identified using the B3LYP/6-311G(d,p) level of theory and total energies were computed using the method CCSD(T)/6-311+G(3df, 2p). The forward barrier height of triple dissociation has a trend of ethanedial < propanal < propenal < n-butane < 1-butene < 1,3-butadiene, pertaining to the reaction enthalpy. Ratios of translational energies of three separate fragments could be estimated from the transition structure of triple dissociation. The synchronous concerted dissociation of propanal, propenal, and 1-butene leading to three different types of molecular fragments by breaking nonequivalent chemical bonds is rare. The triple dissociation of propanal, n-butane, 1-butene, and 1,3-butadiene were investigated for the first time. To outline a whole picture of dissociation mechanisms, some significant two-body dissociation channels were investigated for the calculations of product branching ratios. The triple dissociation plays an important role in the three carbonyl compounds, but plays a minor or negligible role in the three hydrocarbons.

  12. Theoretical investigation of ethylene/1-butene copolymerization process using constrained geometry catalyst (CpSiH 2NH)-Ti-Cl 2

    NASA Astrophysics Data System (ADS)

    Malani, Hema; Hayashi, Shigekazu; Zhong, Huifeng; Sahnoun, Riadh; Tsuboi, Hideyuki; Koyama, Michihisa; Hatakeyama, Nozomu; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Del Carpio, Carlos A.; Miyamoto, Akira

    2008-09-01

    The ethylene/1-butene copolymerization using constrained geometry catalyst CpSiH 2-NH-TiCl 2 (CGC) was investigated by the density functional theory and molecular dynamics. Structures and energetics of reactants, π-complexes, transition states, and products during insertion of ethylene and 1-butene monomers into the catalytic reactive site of the CGC were investigated by the density functional theory (DFT) using the software Dmol 3, while dynamics of atoms during copolymerization process was investigated by classical molecular dynamics (MD) using the New-Ryudo-CR program. The calculated results were compared with the available experimental and theoretical ones. It was found that the ethylene insertion into Ti-Me active species is energetically more favorable than the butene one and the 2,1-butene insertion is more favorable than 1,2-butene one. Once the initial ethylene insertion has taken place, the further ethylene insertion occurring with a less energy barrier, in good agreement with experimental findings.

  13. Comparative dimerization of 1-butene with a variety of metal catalysts, and the investigation of a new catalyst for C=H bond activation.

    PubMed

    Small, Brooke L; Schmidt, Roland

    2004-02-20

    Catalytic dimerization of 1-butene by a variety of catalysts is carried out, and the products are analyzed by gas chromatography and mass spectrometry. Catalysts based on cobalt and iron can produce highly linear dimers, with the cobalt-based dimers exceeding 97 % linearity. Catalysts based on vanadium and aluminum prefer to make branched dimers, which are most often methyl-heptenes in the case of vanadium and almost exclusively 2-ethyl-1-butene in the case of aluminum. The vanadium catalyst also produces substantial amounts of dienes and alkanes, suggesting a competing hydrogenation/dehydrogenation pathway that appears to involve vinyl Cbond;H bond activation. Nickel catalysts are generally less selective than those based on iron or cobalt for making linear dimers, but they can make dimers with 60 % linearity. The major by-products for the nickel systems are trisubstituted internal olefins. An important side reaction that must be considered for dimerization reactions is 1-butene isomerization to 2-butene, which makes recycling the butene difficult for a linear dimerization process. Aluminum, iron, and vanadium systems promote very little isomerization, but nickel and cobalt systems tend to isomerize the undimerized substrate heavily. PMID:14978828

  14. Determination of thermodynamic properties of isotactic poly(1-butene) at infinite dilution using density and inverse gas chromatography.

    PubMed

    Kozłowska, Marta Karolina; Domańska, Urszula; Lempert, Małgorzata; Rogalski, Marek

    2005-03-18

    The partial molar volumes, V1(M), and the molar volume of isotactic crystalline low-molecular-weight poly(1-butene), iPBu-1, V1, have been calculated from the measured density of {iPBu-1 + solvent (n-hexane, n-heptane, n-nonane, n-decane, p-xylene, cyclohexane and chloroform)} systems. Some of the thermodynamic quantities were also obtained for the iPBu-1 with eight hydrocarbons (n-octane, n-decane, n-undecane, n-dodecane, n-tridecane, o-xylene, m-xylene, p-xylene) by the method of inverse gas chromatography at various temperatures. The weight fraction activity coefficients of the solvent at infinite dilution, omega2(infinity) and the Flory-Huggins thermodynamic interaction parameters, chi21(infinity), between polymer and solvents were determined. The partial molar free energy, deltaG2(infinity), the partial molar heat of mixing, deltaH2(infinity), at infinite dilution and the polymer solubility parameter, delta1, were calculated. Additionally, the (solid + liquid) binary mixtures equilibria, SLE, of iPBu-1 with three hydrocarbons (n-octane, n-decane and m-xylene) were studied by a dynamic method. By performing these experiments over a large concentration range, the T-x phase diagrams of the polymer-solvent systems were constructed. The excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase. The omega2(infinity) were determined from the solubility measurements and were predicted by using the UNIFAC FV model.

  15. In situ FTIR spectroscopy of 1-butene and 1,3-butadiene selective oxidation to maleic anhydride on V-P-O catalysts

    SciTech Connect

    Wenig, R.W.; Schrader, G.L.

    1987-03-26

    The selective oxidation of 1-butene and 1,3-butadiene was studied by transmission infrared spectroscopy. Vanadium-phosphorus-oxygen catalysts prepared by the reaction of V/sub 2/O/sub 5/ with H/sub 3/PO/sub 4/ in alcohol solution were used. Infrared spectra were collected in situ during the flow of 75 cm/sup 3/ of 1.5% hydrocarbon-in-air mixtures over catalysts having P-to-V ratios of 0.9, 1.0, and 1.1. Reaction temperatures from 300 to 400 /sup 0/C were investigated with 1-butene feeds, whereas the highly reactive 1,3-butadiene was studied only at 300 /sup 0/C. An adsorbed butadiene species, maleic acid, and maleic anhydride were observed during both olefin partial oxidation studies. Evidence was obtained for a second olefin species which had been previously observed for in situ n-butane selective oxidation studies. Concentrations of adsorbed species were found to vary with catalyst phosphorus loading, reaction temperature, and time of exposure to reaction conditions.

  16. Chirality Effect on Flory-Huggins Interaction Parameters in Polylactide-b-Poly(ethylene-co-1-butene)-b-Polylactide Triblock Copolymers

    NASA Astrophysics Data System (ADS)

    Cao, Weiqiang; Zhu, Lei; Rong, Lixia; Hsiao, Benjamin S.

    2009-03-01

    In this work, a set of well-defined polylactide-b-poly(ethylene-co-1-butene)-b-polylactide (PLA-PEB-PLA) triblock copolymers were synthesized by controlled ring-opening polymerization of corresponding lactide monomers (L-lactide and racemic mixture of D- and L-lactides) using Sn(Oct)2 as the catalyst. The volume fractions of PLA in the triblock copolymers were adjusted by tuning its molecular weight. The mesophase morphology and phase transitions in these triblock copolymers were studied by temperature-dependent small-angle X-ray scattering (SAXS). The Flory-Huggins interaction parameter χ between EB and lactide as a function of temperature were estimated from the order-disorder transition temperature (TODT) using the mean-field critical (χN)c values. The effects of PLA chirality on both Flory-Huggins interaction parameter and segmental lengths were investigated.

  17. The structure factor of poly(1-butene) and poly(4-methyl-1-pentene) from wide angle X-ray scattering, molecular dynamics and PRISM.

    NASA Astrophysics Data System (ADS)

    Habenschuss, Anton; Kim, Man-Ho; Curro, John G.; Heine, David R.

    2003-03-01

    The melt structures of the isotactic vinyl polymers poly(1-butene) and poly(4-methyl-1-pentene), with corresponding ethyl and isobutyl side chains, were recently studied with wide-angle X-ray diffraction. For these polymers, a "pre-peak" appears below the main diffraction peak in the carbon-carbon structure factor. The pre-peak becomes stronger and shifts to lower scattering vectors with increasing bulkiness of the side chain. These features are predicted on the basis of molecular dynamics simulations and Polymer Reference Interaction Site Model (PRISM) calculations. Good agreement is found for the structure factor determined with simulation and theory and the X-ray scattering experiments. The origin of the pre-peak for vinyl polymers based on experiment and theory will be discussed.

  18. Effects of Deposition Plasma Power on Properties of Low Dielectric-Constant Plasma Polymer Films Deposited Using Hexamethyldisiloxane and 3,3-Dimethyl-1-butene Precursors

    NASA Astrophysics Data System (ADS)

    Lee, Sungwoo; Woo, Jihyung; Nam, Eunkyoung; Jung, Donggeun; Yang, Jaeyoung; Chae, Heeyeop; Kim, Hyoungsub

    2009-10-01

    We investigated the effects of deposition plasma power on the properties of plasma polymer films deposited by plasma-enhanced chemical vapor deposition using a mixture of hexamethyldisiloxane and 3,3-dimethyl-1-butene as the precursor, which are referred to as plasma polymerized hexamethyldisiloxane:3,3-dimethyl-1-butene (PPHMDSO:DMB) films. As the deposition plasma power was increased from 15 to 60 W, the relative dielectric constants k of PPHMDSO:DMB films, increased from 2.67 to 3.19. After annealing at 450 °C, the films deposited at a deposition plasma power of 15-60 W showed k values of 2.27-2.64. With increased deposition plasma power, the as-deposited and annealed films showed increased values of hardness and Young's modulus. For as-deposited films, deposited at a plasma power of 15-60 W, the films showed a hardness of 0.13-2.0 GPa, and a modulus of 2.25-17.27 GPa. Annealed films, deposited at a plasma power of 15-60 W, showed a hardness of 0.05-2.07 GPa and a modulus of 1.66-14.4 GPa. The change in the k value and hardness of plasma polymer films as a function of deposition plasma power was correlated with fourier transform infrared (FT-IR) absorption peaks of C-Hx, Si-CH3, and Si-O related groups. The as-deposited and annealed PPHMDSO:DMB films showed decreased intensities of C-Hx and Si-CH3 peaks as the deposition plasma power increased. The reduction in the dielectric constant after annealing is mainly due to hydrocarbon removal in the film. Deconvolution of Si-CH3 bending peaks of PPHMDSO:DMB films was performed to relate mechanical properties to chemical structures. The relative oxygen content in the O-Si-(CH3)x structure is analyzed in detail. Improvements in hardness and modulus of our films are attributed to an increased amount of O3Si-(CH3) in the Si-CH3 structure.

  19. Conformationally disordered crystals and their influence on material properties: The cases of isotactic polypropylene, isotactic poly(1-butene), and poly(L-lactic acid)

    NASA Astrophysics Data System (ADS)

    Cocca, Mariacristina; Androsch, René; Righetti, Maria Cristina; Malinconico, Mario; Di Lorenzo, Maria Laura

    2014-12-01

    This article provides a comprehensive review of the physical properties of the conformationally disordered (condis) structures of isotactic polypropylene (iPP), isotactic poly(1-butene) (iPB-1) and poly(L-lactic acid) (PLLA), in comparison with the respective more stable crystalline forms. The aim of this review is to define the influence of the condis modifications on the thermal and mechanical properties of these materials. The condis structures of the three polymers are metastable and spontaneously transform into the more stable crystalline structures upon annealing above a critical temperature. The transition from the mesophase to the more stable crystalline structure becomes possible when the chains have sufficient mobility to allow rearrangements of chain conformations. A rigid amorphous fraction develops during solidification of iPP, iPB-1 and PLLA. Crystallization of iPB-1 and PLLA into the more stable forms leads to a larger coupling of the amorphous and crystalline chain segments, compared to the conformationally disordered arrangements, which results in a higher fraction of rigid amorphous chain segments. The difference in chain packing, together with the varied mobility of the coupled amorphous chain portions, affects both the initial resistance to the tensile strain and the large strain properties. All the three stable crystalline forms have a higher Young's modulus compared to the condis mesophases, and can sustain lower deformation under mechanical stimuli.

  20. Modeling chemical growth processes in Titan's atmosphere 2. Theoretical study of reactions between C 2H and ethene, propene, 1-butene, 2-butene, isobutene, trimethylethene, and tetramethylethene

    NASA Astrophysics Data System (ADS)

    Woon, David E.; Park, Jin-Young

    2009-08-01

    Barrierless reactions between unsaturated hydrocarbons and the ethynyl radical (C 2H) can contribute to the growth of organic particulates in the haze-forming regions of Titan's atmosphere as well as in the gas giants and in the interstellar medium. We employed a combination of quantum chemistry and statistical rate theories to characterize reactions between ground state C 2H and seven alkenes of the general structure RRCdbnd CRR containing up to six carbons. The alkenes included ethene (C 2H 4); propene (C 3H 6); 1-butene, 2-butene, and isobutene (C 4H 8); trimethylethene (C 5H 10); and tetramethylethene (C 6H 12). Density functional theory calculations at the B3LYP/6-31 + G ∗∗ level were used to characterize the adducts, isomers, products, and the intervening transition states for the addition-elimination reactions of all seven species. A multiple-well treatment was then employed to determine the outcome distributions for the range of temperatures and pressures relevant to Titan's atmosphere, the interstellar medium, and the outer atmospheres of the gas giants. Finally, trajectory calculations using an ROMP2 potential energy surface were used to calculate kinetic rates for the ethene + C 2H reaction, where the agreement between the computed and measured values is very good. At low pressure and temperature, vinyl acetylene is a dominant product of several of the reactions, and all of the reactions yield at least one dominant product with both a double and a triple C sbnd C bond.

  1. MoO sub 3 catalysts promoted by MnMoO sub 4 I. Synthesis, characterization, and selectivity in oxidation of 1-butene and 1,3-butadiene to maleic anhydride

    SciTech Connect

    Ozkan, U.; Gill, R.C.; Smith, M.R. )

    1989-03-01

    MoO{sub 3} catalysts impregnated with MnMoO{sub 4} are active for the selective oxidation of C{sub 4} hydrocarbons to maleic anhydride. Presence of MnMoO{sub 4} creates a significant promoter effect in catalytic behavior of MoO{sub 3}. The pure phases and the impregnated catalysts have been characterized during various stages of their life history using characterization techniques such as X-ray diffraction, laser Raman spectroscopy, scanning electron microscopy, and BET surface area measurements, and their catalytic activity and selectivity in selective oxidation of 1-butene and 1,3-butadiene to maleic anhydride have been studied.

  2. MoO sub 3 catalysts promoted by MnMoO sub 4. II. Effect of O sub 2 concentration and temperature in selective oxidation of 1-butene to maleic anhydride

    SciTech Connect

    Gill, R.C.; Ozkan, U.S. )

    1990-04-01

    In a previous paper, the authors have reported the results of a study where they focused their attention on catalytic activity and selectivity of pure MoO{sub 3} and attempted to modify its catalytic behavior by bringing its surfaces into close contact with MnMoO{sub 4}. While their characterization experiments revealed the two-phase nature of the MnMoO{sub 4}/MoO{sub 3} catalyst, the activity studies showed a pronounced promoter effect in selective oxidation of both 1-butene and 1,3-butadiene to maleic anhydride, suggesting a possible synergy between the two phases. This note presents the results of their selective oxidation studies where the effect of temperature and oxygen partial pressure on catalytic behavior of the pure phases (MoO{sub 3} and MnMoO{sub 4}) as well as the two phase catalyst (MnMoO{sub 4}/MoO{sub 3}) has been investigated in conversion of 1-butene to maleic anhydride. All catalysts were characterized in detail using BET surface area measurement, x-ray diffraction, scanning electron microscopy, energy dispersive x-ray analysis, laser Raman spectroscopy and Raman microprobe techniques.

  3. Flow cytometric analysis of micronucleus induction in rat bone marrow polychromatic erythrocytes by 1,2;3,4-diepoxybutane, 3,4-epoxy-1-butene, and 1,2-epoxybutane-3,4-diol.

    PubMed

    Lähdetie, J; Grawé, J

    1997-07-01

    Automation of the analysis of micronucleus induction with flow cytometry was developed by using mouse bone marrow or peripheral blood. In the present study, we report the use of flow cytometry for the identification and quantification of micronuclei (MN) induced in rat bone marrow polychromatic erythrocytes. Three metabolites of the industrial chemical 1,3-butadiene, namely 1,2;3,4-diepoxybutane (DEB), 3,4-epoxy-1-butene (EB) and 1,2-epoxybutane-3,4-diol (diol-EB), were studied in addition to mitomycin C and cyclophosphamide, which served as positive controls. DEB showed a dose-dependent increase in the frequency of MN, whereas EB was completely negative and diol-EB only weakly positive at one dose level. The effect of the positive control compounds was observed 48 h after a single injection in a dose-dependent manner. Flow cytometry was an effective method to quantitate bone marrow MN induction in the rat when density gradient separation of polychromatic erythrocytes is used. The results are compatible with the theory that oxidation of EB to the mutagenic metabolite DEB occurs at a low rate in rat bone marrow and that EB is detoxified by epoxide hydrolase and by conjugation with glutathione by glutathione transferase yielding nonmutagenic metabolites. Thus, the reported lack of MN induction by 1,3-butadiene inhalation in rat bone marrow is explained.

  4. Selective oxidation of n-butane and butenes over vanadium-containing catalysts

    SciTech Connect

    Nieto, J.M.L.; Concepcion, P.; Dejoz, A.; Knoezinger, H.; Melo, F.; Vazquez, M.I.

    2000-01-01

    The oxidative dehydrogenation (OXDH) of n-butane, 1-butene, and trans-2-butene on different vanadia catalysts has been compared. MgO, alumina, and Mg-Al mixed oxides with Mg/(Al + Mg) ratios of 0.25 and 0.75 were used as supports. The catalytic data indicate that the higher the acid character of catalysts the lower is both the selectivity to C{sub 4}-olefins from n-butane and the selectivity to butadiene from both 1-butene or trans-2-butene. Thus, OXDH reactions are mainly observed from n-butane and butenes on basic catalysts. The different catalytic performance of both types of catalysts is a consequence of the isomerization of olefins on acid sites, which appears to be a competitive reaction with the selective way, i.e., the oxydehydrogenation process by a redox mechanism. Infrared spectroscopy data of 1-butene adsorbed on supported vanadium oxide catalysts suggest the presence of different adsorbed species. O-containing species (carbonyl and alkoxide species) are observed on catalysts with acid sites while adsorbed butadiene species are observed on catalysts with basic sites. According to these results a reaction network for the oxydehydrogenation of n-butane is proposed with parallel and consecutive reactions.

  5. Solubility parameter of poly(1-butene), isotactic

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  6. Partial specific volume of poly(1-butene)

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  7. Second virial coefficient of poly(1-butene)

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  8. Processing-structure-property studies of: (I) submicron polymeric fibers produced by electrospinning and (II) films of linear low density polyethylenes as influenced by the short chain branch length in copolymers of ethylene/1-butene, ethylene/1-hexene and ethylene/1-octene synthesized by a single site metallocene catalyst

    NASA Astrophysics Data System (ADS)

    Gupta, Pankaj

    The overall theme of the research discussed in this dissertation has been to explore processing-structure-property relationships for submicron polymeric fibers produced by electrospinning (Part I) and to ascertain whether or not the length of the short chain branch has any effect on the physical properties of films of linear low-density polyethylenes (LLDPEs) (Part II). The research efforts discussed in Part I of this dissertation relate to some fundamental as well as more applied investigations involving electrospinning. These include investigating the effects of solution rheology on fiber formation and developing novel methodologies to fabricate polymeric mats comprising of high specific surface submicron fibers of more than one polymer, high chemical resistant substrates produced by in situ photo crosslinking during electrospinning, superparamagnetic flexible substrates by electrospinning a solution of an elastomeric polymer containing ferrite nanoparticles of Mn-Zn-Ni and substrates for filtration applications. Bicomponent electrospinning of poly(vinyl chloride)-polyurethane and poly(vinylidiene fluoride)-polyurethane was successfully performed. In addition, filtration properties of single and bicomponent electrospun mats of polyacrylonitrile and polystyrene were investigated. Results indicated lower aerosol penetration or higher filtration efficiencies of the filters based on submicron electrospun fibers in comparison to the conventional filter materials. In addition, Part II of this dissertation explores whether or not the length of the short chain branch affects the physical properties of blown and compression molded films of LLDPEs that were synthesized by a single site metallocene catalyst. Here, three resins based on copolymers of ethylene/1-butene, ethylene/1-hexene, and ethylene/1-octene were utilized that were very similar in terms of their molecular weight and distribution, melt rheology, density, crystallinity and short chain branching content and

  9. Reactions of OH with Butene Isomers. Measurements of the Overall Rates and a Theoretical Study

    SciTech Connect

    Vasu, Subith; Huynh, Lam; Davidson, David F.; Hanson, Ronald K.; Golden, David

    2011-03-09

    Reactions of hydroxyl (OH) radicals with 1-butene (k1), trans-2-butene (k2), and cis-2-butene (k3) were studied behind reflected shock waves over the temperature range 880-1341 K and at pressures near 2.2 atm. OH radicals were produced by shock-heating tert-butyl hydroperoxide, (CH3)3-CO-OH, and monitored by narrow-line width ring dye laser absorption of the well-characterized R1(5) line of the OH A-X (0, 0) band near 306.7 nm. OH time histories were modeled using a comprehensive C5 oxidation mechanism, and rate constants for the reaction of OH with butene isomers were extracted by matching modeled and measured OH concentration time histories. We present the first high-temperature measurement of OH + cis-2-butene and extend the temperature range of the only previous high-temperature study for both 1-butene and trans-2-butene. With the potential energy surface calculated using CCSD(T)/6-311++G(d,p)//QCISD/6-31G(d), the rate constants and branching fractions for the H-abstraction channels of the reaction of OH with 1-butene were calculated in the temperature range 300-1500 K. Corrections for variational and tunneling effects as well as hindered-rotation treatments were included. The calculations are in good agreement with current and previous experimental data and with a recent theoretical study.

  10. Mesophases in polyethylene, polypropylene, and poly(1-butene)

    SciTech Connect

    Androsch, Rene J; Di Lorenzo, Maria; Schick, Christoph; Wunderlich, Bernhard {nmn}

    2010-01-01

    This paper contains new views about the amorphous and partially ordered phases of the three polymers listed in the title. The discussion is based on information on structure, thermodynamic stability, and large-amplitude molecular motion. Polyethylene is the basic backbone of all alkene polymers, and the other two are the first members of the vinyl polymers which have stereospecifically placed alkyl side chains. Their multiphase structures consist of metastable crystals, mesophases, and surrounding rigid and mobile amorphous fractions. All these phases have sizes ranging from micrometer dimensions down to nanometers. Besides the phase structures, information about the molecular coupling between the phases must be considered. Depending on temperature, the polymer phases can vary from solid (rigid) to liquid (mobile). New knowledge is also gained by cross-comparison of the title polymers. The experimental information was gained from (a) various forms of slow, fast, and temperature-modulated thermal analysis to identify equilibrium and non-equilibrium states, (b) measurement of structure and morphology at various length scales, and (c) tracing of the large-amplitude molecular motion, the kinetics of order/disorder changes, and the liquid/solid transitions (glass transitions). It is shown that much more needs to be known about the various phases and their coupling to characterize a given polymer and to fine-tune its properties for a given application.

  11. Second virial coefficient of poly(ethylene-alt-1-butene)

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  12. Second virial coefficient of poly(ethylene-co-1-butene)

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  13. Second virial coefficient of poly(1-butene), isotactic

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  14. Marine tropospheric hydrocarbons: An intercomparison exercise

    NASA Astrophysics Data System (ADS)

    Carsey, Thomas P.

    1991-07-01

    Results from an multilaboratory intercomparison exercise for the determination of non-methane hydrocarbons in the North Pacific troposphere are presented. Each of the ten participating labs analyzed marine air obtained on the NOAA ship R/V RESEARCHER and from a single large tank of Oregon coastal air for some or all of the following: ethane, ethylene, 1-butene, isobutene (2-methyl 1-propene), cis-2-butene, trans-2-butene, iso-pentene, n-pentane, isopentene (2-methyl 1-butene), 1-pentene, benzene, toluene, methane, carbon dioxide, and methyl chloroform. The following parameters were computed where data was sufficient for each lab and each analyte: mean mixing ratios, total precision, analytical precision, and sampling precision. Means were compared using a nonparametric procedure. Mixing ratios vs time data for the various compounds indicated that diurnal changes were minimal or absent; however, slight decreases in mixing ratios were observed for C2H6, C2H2, CH3CCl3, CO and CH4.

  15. Kinetic studies of olefin binding to sulfido sites in dinuclear molybdenum complexes

    SciTech Connect

    Koval, C.R.; Lopez, L.L.; Kaul, B.B.; Renshaw, S.; Green, K.; DuBois, M.R.

    1995-07-01

    The reactions of olefins with a series of molybdenum complexes of the formula (R-CpMo-({mu}-S)){sub 2}S{sub 2}CHX, where R = H, CH{sub 3}, CO{sub 2}Na, and X = H, CN, CMe{sub 3}, have been studied. Olefin reagents have included propene, 1-butene, cis- and trans-2-butene, and isomers of hexene. Olefin additions to the sulfido ligands in the dimers result in alkanedithiolate complexes. The rates of these reactions have been monitored by visible spectroscopy, and rate constants, k{sub on}, have been compared as dimer substituent and olefin structure have been varied. The rate constants for olefin dissociation from the alkanedithiolate complexes, k{sub off}, have also been determined by NMR spectroscopy. The studies have permitted us to probe the relative contributions of k{sub on} and k{sub off} to the equilibrium constants for reversible olefin binding as inductive and steric effects are varied. The potential for using these systems in olefin separation schemes is discussed. 20 refs., 3 figs., 6 tabs.

  16. Pressure-dependent OH yields in alkene + HO2 reactions: a theoretical study.

    PubMed

    Zádor, Judit; Klippenstein, Stephen J; Miller, James A

    2011-09-15

    The major bimolecular product of alkyl + O(2) reactions is alkene + hydroperoxyl radical (HO(2)), but in the reverse direction, the reactants are reformed to a very limited extent only. The most important products of the alkene + HO(2) reactions are alkylperoxy radical (ROO(•)), hydroxyl radical (OH) + cyclic ether, and the corresponding hydroperoxyalkyl ((•)QOOH) species. Moreover, abstraction of allylic hydrogens can compete with the addition, further complicating the possible outcome of this reaction type and its effect on low-temperature combustion chemistry. In this paper, six alkene + HO(2) reactions and the reaction between an unsaturated oxygenate and HO(2) are studied based on previously established potential energy surfaces. The studied unsaturated compounds are ethene, propene, 1-butene, trans-2-butene, isobutene, cyclohexene, and vinyl alcohol. Using multiwell master equations, temperature- (300-1200 K) and pressure-dependent rate coefficients and branching fractions are calculated for these reactions. The importance of this reaction type for the combustion of unsaturated compounds is also assessed, and we show that, to get reliable results, it is important to include the pressure-dependence of the rate coefficients in the calculations. PMID:21819062

  17. Laboratory spectroscopic analyses of electron irradiated alkanes and alkenes in solar system ices

    NASA Astrophysics Data System (ADS)

    Hand, K. P.; Carlson, R. W.

    2012-03-01

    We report results from laboratory experiments of 10 keV electron irradiation of thin ice films of water and short-chain hydrocarbons at ˜10-8 Torr and temperatures ranging from 70-100 K. Hydrocarbon mixtures include water with C3H8, C3H6, C4H10 (butane and isobutane), and C4H8, (1-butene and cis/trans-2-butene). The double bonds of the alkenes in our initial mixtures were rapidly destroyed or converted to single carbon bonds, covalent bonds with hydrogen, bonds with -OH (hydroxyl), bonds with oxygen (C-O), or double bonds with oxygen (carbonyl). Spectra resulting from irradiation of alkane and alkene ices are largely indistinguishable; the initial differences in film composition are destroyed and the resulting mixture includes long-chain, branched aliphatics, aldehydes, ketones, esters, and alcohols. Methane was observed as a product during radiolysis but CO was largely absent. We find that while some of the carbon is oxidized and lost to CO2 formation, some carbon is sequestered into highly refractory, long-chain aliphatic compounds that remain as a thin residue even after the ice film has been raised to standard temperature and pressure. We conclude that the high availability of hydrogen in our experiments leads to the formation of the formyl radical which then serves as the precursor for formaldehyde and polymerization of longer hydrocarbon chains.

  18. pVT data of poly(ethylene-co-1-butene) in dimethyl ether

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  19. pVT data of poly(ethylene-co-1-butene) in n-pentane

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  20. Solubility parameter of poly[styrene-b-(1-butene-co-ethylene)-b-styrene

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  1. Isotope effects and the temperature dependences of the hyperfine coupling constants of muoniated sec-butyl radicals in condensed phases.

    PubMed

    Fleming, Donald G; Bridges, Michael D; Arseneau, Donald J; Chen, Ya Kun; Wang, Yan Alexander

    2011-04-01

    Reported here is the first μSR study of the muon (A(μ)) and proton (A(p)) β-hyperfine coupling constants (Hfcc) of muoniated sec-butyl radicals, formed by muonium (Mu) addition to 1-butene and to cis- and trans-2-butene. The data are compared with in vacuo spin-unrestricted MP2 and hybrid DFT/B3YLP calculations reported in the previous paper (I), which played an important part in the interpretation of the data. The T-dependences of both the (reduced) muon, A(μ)′(T), and proton, A(p)(T), Hfcc are surprisingly well explained by a simple model, in which the calculated Hfcc from paper I at energy minima of 0 and near ±120° are thermally averaged, assuming an energy dependence given by a basic 2-fold torsional potential. Fitted torsional barriers to A(μ)′(T) from this model are similar (~3 kJ/mol) for all muoniated butyl radicals, suggesting that these are dominated by ZPE effects arising from the C−Mu bond, but for A(p)(T) exhibit wide variations depending on environment. For the cis- and trans-2-butyl radicals formed from 2-butene, A(μ)′(T) exhibits clear discontinuities at bulk butene melting points, evidence for molecular interactions enhancing these muon Hfcc in the environment of the solid state, similar to that found in earlier reports for muoniated tert-butyl. In contrast, for Mu−sec-butyl formed from 1-butene, there is no such discontinuity. The muon hfcc for the trans-2-butyl radical are seemingly very well predicted by B3LYP calculations in the solid phase, but for sec-butyl from 1-butene, showing the absence of further interactions, much better agreement is found with the MP2 calculations across the whole temperature range. Examples of large proton Hfcc near 0 K are also reported, due to eclipsed C−H bonds, in like manner to C−Mu, which then also exhibit clear discontinuities in A(p)(T) at bulk melting points. The data suggest that the good agreement found between theory and experiment from the B3LYP calculations for eclipsed bonds in

  2. Sources of C₂-C₄ alkenes, the most important ozone nonmethane hydrocarbon precursors in the Pearl River Delta region.

    PubMed

    Zhang, Yanli; Wang, Xinming; Zhang, Zhou; Lü, Sujun; Huang, Zhonghui; Li, Longfeng

    2015-01-01

    Surface ozone is becoming an increasing concern in China's megacities such as the urban centers located in the highly industrialized and densely populated Pearl River Delta (PRD) region, where previous studies suggested that ozone production is sensitive to VOC emissions with alkenes being important precursors. However, little was known about sources of alkenes. Here we present our monitoring of ambient volatile organic compounds at four representative urban, suburban and rural sites in the PRD region during November-December 2009, which experienced frequent ozone episodes. C2-C4 alkenes, whose total mixing ratios were 11-20% of non-methane hydrocarbons (NMHCs) quantified, accounted for 38-64% of ozone formation potentials (OFPs) and 30-50% of the total hydroxyl radical (OH) reactivity by NMHCs. Ethylene was the most abundant alkene, accounting for 8-15% in total mixing ratios of NMHCs and contributed 25-46% of OFPs. Correlations between C2-C4 alkenes and typical source tracers suggested that ethylene might be largely related to vehicle exhausts and industry activities, while propene and butenes were much more LPG-related. Positive Matrix Factorization (PMF) confirmed that vehicle exhaust and liquefied petroleum gas (LPG) were two major sources that altogether accounted for 52-62%, 58-77%, 73-83%, 68-79% and 73-84% for ethylene, propene, 1-butene, trans-2-butene and cis-2-butene, respectively. Vehicle exhausts alone contributed 32-49% ethylene and 35-41% propene. Industry activities contributed 13-23% ethylene and 7-20% propene. LPG instead contributed the most to butenes (38-65%) and substantially to propene (23-36%). Extensive tests confirmed high fractions of propene and butenes in LPG then used in Guangzhou and in LPG combustion plumes; therefore, limiting alkene contents in LPG would benefit regional ozone control.

  3. Degradation of chlorinated butenes and butadienes in granular iron columns.

    PubMed

    Hughes, Rodney; Gui, Lai; Gillham, Robert W

    2009-10-01

    Manufacturing facilities for production of chlorobutyl rubber have the potential to release a mixture of at least 5 chlorinated butenes and butadienes including trans-1,4-dichlorobutene-2 (1,4-DCB-2), 3,4-dichlorobutene-1 (3,4-DCB-1), 2,3,4-trichlorobutene-1 (TCB), 2-chlorobutadiene-1,3 (chloroprene) and 2,3-dichlorobutadiene-1,3 (DCBD) into groundwater environment. To evaluate the potential of using granular iron in the remediation of the above contaminants, a series of column experiments were conducted. Degradation of all 5 compounds followed pseudo-first-order kinetics. The three chlorinated butenes degraded much faster (surface area normalized half-lives, t(1/2)', ranged from 1.6 to 5.2 min m2/mL) than the 2 chlorinated butadienes (t(1/2)' ranged from 102 to 197 min m2/mL). All contaminants fully dechlorinated by granular iron to 1,3-butadiene as a common reaction intermediate that then degraded to a mixture of relatively non-harmful end products consisting of 1-butene, cis-2-butene, trans-2-butene and n-butane. Based on the kinetic data, product distributions, and chlorine mass balances, reaction pathways for these compounds are proposed. For the chlorinated butenes, 3,4-DCB-1 and TCB, undergo reductive beta-elimination reactions resulting in 1,3-butadiene and chloroprene intermediates. Dechlorination of 1,4-DCB-2 to 1,3-butadiene occurs through a reductive elimination similar to reductive beta-elimination. For dechlorination of the two chlorinated butadienes, chloroprene and DCBD, dechlorination occurs through a hydrogenolysis pathway. The common non-chlorinated intermediate, 1,3-butadiene, undergoes catalytic hydrogenation resulting in a mixture of butane isomers and n-butane. The results suggest that granular iron is an effective material for treatment of groundwater contaminated with these compounds.

  4. pVT data of poly(ethylene-co-1-butene) in n-pentane-d12

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  5. pVT data of poly(ethylene-co-1-butene) in dimethyl ether-d6

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  6. Reactions of volatile organic compounds in the atmosphere: Ozone-alkene reactions

    NASA Astrophysics Data System (ADS)

    Fenske, Jill Denise

    2000-08-01

    Photochemical smog cannot form without sunlight, nitrogen oxides, and volatile organic compounds (VOC). This dissertation addresses several different aspects of VOC chemistry in the atmosphere. Aside from ambient levels of VOC outdoors, VOC are also present at moderate concentrations indoors. Many studies have measured indoor air concentrations of VOC, but only one considered the effects of human breath. The major VOC in the breath of healthy individuals are isoprene (12-580 ppb), acetone (1.2-1800 ppb), ethanol (13-1000 ppb), methanol (160-2000 ppb), and other alcohols. Human emissions of VOC are negligible on a regional (less than 4%) and global scale (less than 0.3%). However, in indoor air, under fairly crowded situations, human emissions of VOC may dominate other sources of VOC. An important class of VOC in the atmosphere is alkenes, due to their high reactivity. The ozone reaction with alkenes forms OH radicals, a powerful oxidizing agent in the troposphere. OH radical formation yields from the ozonolysis of several cycloalkenes were measured using small amounts of fast-reacting aromatics and aliphatic ethers to trace OH formation. The values are 0.62 +/- 0.15, 0.54 +/- 0.13, 0.36 +/- 0.08, and 0.91 +/- 0.20 for cyclopentene, cyclohexene, cycloheptene and 1-methylcyclohexene, respectively. Density functional theory calculations at the B3LYP/6-31 G(d,p) level are presented to aid in understanding the trends observed. The pressure dependence of OH radical yields may lend insight into the formation mechanism. We have made the first study of the pressure dependence of the OH radical yield for ethene, propene, 1-butene, trans-2-butene, and 2,3-dimethyl-2- butene over the range 20-760 Torr, and trans -3-hexene, and cyclopentene over the range 200-760 Torr. The OH yields from ozonolysis of ethene and propene were pressure dependent, while the other compounds had OH yields that were independent of pressure. Ozone-alkene reactions form vibrationally excited carbonyl

  7. Laboratory Analysis Of Water, Hydrocarbon And Ammonia Ice Mixtures Exposed To High-energy Electron Irradiation

    NASA Astrophysics Data System (ADS)

    Hand, Kevin P.; Carlson, R. W.; Tsapin, A. I.

    2006-09-01

    Irradiation of low temperature ices in the laboratory provides insight into processes that may be occurring on icy bodies in the solar system. Here we report on results from high-energy (10keV) electron irradiation of thin ice films at 1e-8 torr and 70-120K. Mixtures include water with CO2, C3H8, C3H6, C4H10 (butane and isobutane), C4H8,(1-butene and cis/trans-2-butene), and NH3. During irradiation of H2O + alkane films at 80K, CO2 and CH4 production is observed and both species are retained in the ice, possibly trapped in clathrates. The -CH3 infrared bands initially present are seen to decrease with increasing dose. Bands associated with -CH2- persist, indicating polymerization of the initial short-chain hydrocarbons. In alkenes a similar evolution toward polymerization is observed, however the first step appears to be the destruction of the C=C bond. Upon warming of the film, mass spectra data compliment the mid-infrared data and indicate the production of H2CO, however glycolic acid is not explicitly seen in the mass spectra. When warmed to 300K, residues remained for all irradiated films except that of the H2O + CO2 mixtures. Residues were analyzed with Matrix Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI). Results show the production of large aliphatic, very refractory, hydrocarbons (with m/z up to 2500). Mid-infrared spectra of the residues indicate carbonyls and alcohols, likely due to polymerized aldehydes and carboxylic acids. Films of H2O + C3H8 + NH3 at 70K show the production of OCN- (cyanate ion), formamide, along with other possible amides and hydrocarbons. HPLC results indicate the production of racemic alanine. Finally, results of abiotic experiments are compared to results from the irradiation of bacterial spores in ice. The application to Europa and Enceladus is discussed.

  8. EXTENDED ALKYLATE PRODUCTION ACTIVITY DURING FIXED-BED SUPERCRITICAL 1-BUTENE/ISOBUTANE ALKYLATION ON SOLID ACID CATALYSTS USING CARBON DIOXIDE AS DILUENT. (R824729)

    EPA Science Inventory

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

  9. Biogenic Emissions of Light Alkenes from a Coniferous Forest

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Turnipseed, A. A.; Martinez, L.; Shen, S.; De Gouw, J. A.; Warneke, C.; Koss, A.; Lerner, B. M.; Miller, B. R.; Smith, J. N.; Guenther, A. B.

    2014-12-01

    Alkenes are reactive hydrocarbons that play important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. The light alkenes (C2-C4) originate from both biogenic and anthropogenic sources and include C2H4 (ethene), C3H6 (propene) and C4H8 (1-butene, 2-butene, 2-methylpropene). Light alkenes are used widely as chemical feedstocks because their double bond makes them versatile for industrial reactions. Their biogenic sources are poorly characterized, with most global emissions estimates relying on laboratory-based studies; net ecosystem emissions have been measured at only one site thus far. Here we report net ecosystem fluxes of light alkenes and isoprene from a semi-arid ponderosa pine forest in the Rocky Mountains of Colorado, USA. Canopy scale fluxes were measured using relaxed eddy accumulation (REA) techniques on the 28-meter NCAR tower in the Manitou Experimental Forest Observatory. Updrafts and downdrafts were determined by sonic anemometry and segregated into 'up' and 'down' reservoirs over the course of an hour. Samples were then measured on two separate automated gas chromatographs (GCs). The first GC measured light hydrocarbons (C2-C6 alkanes and C2-C5 alkenes) by flame ionization detection (FID). The second GC measured halocarbons (methyl chloride, CFC-12, and HCFC-22) by electron capture detection (ECD). Additional air measurements from the top of the tower included hydrocarbons and their oxidation products by Proton Transfer Reaction Mass Spectrometry (PTR-MS). Three field intensives were conducted during the summer of 2014. The REA flux measurements showed that ethene, propene and the butene emissions have significant diurnal cycles, with maximum emissions at midday. The light alkenes contribute significantly to the overall biogenic source of reactive hydrocarbons and have a temporal variability that may be associated with physical and biological parameters. These ecosystem scale measurements

  10. Production of hydrogen peroxide and organic peroxides in the gas phase reactions of ozone with natural alkenes

    SciTech Connect

    Simonaitis, R.; Olszyna, K.J.; Meagher, J.F.

    1991-01-01

    The formation of H{sub 2}O{sub 2} and organic peroxides in the reaction of O{sub 3} with trans-2-butene and naturally occurring alkenes has been studied using a 31 m{sup 3} reaction chamber. H{sub 2}O{sub 2} and organic peroxides were found to be products of the O{sub 3} reaction with trans-2-butene, isoprene, {alpha} and {beta}-pinene, and limonene. Water is necessary for the formation of H{sub 2}O{sub 2} and most of the H{sub 2}O{sub 2} is formed via a route that does not involve HO{sub 2} radicals. These results indicate that the reaction of O{sub 3} with natural alkenes may be a significant source of atmospheric H{sub 2}O{sub 2}, particularly in forest and rural areas.

  11. Low temperature rate coefficients for reactions of the butadiynyl radical, C4H, with various hydrocarbons. Part II: reactions with alkenes (ethylene, propene, 1-butene), dienes (allene, 1,3-butadiene) and alkynes (acetylene, propyne and 1-butyne).

    PubMed

    Berteloite, Coralie; Le Picard, Sébastien D; Balucani, Nadia; Canosa, André; Sims, Ian R

    2010-04-21

    The kinetics of the reactions of the linear butadiynyl radical, C4H (CCCCH), with a variety of unsaturated hydrocarbons have been studied over the temperature range of 39-300 K using a CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, or reaction kinetics in uniform supersonic flow) apparatus combined with the pulsed laser photolysis-laser induced fluorescence technique. The rate coefficients for all the reactions studied are found to all be in excess of 10(-10) cm(3) molecule(-1) s(-1) over the entire temperature range. They can be fitted with the following expressions (valid from 39 K to 300 K, with RMS deviations of the experimental points from the predicted values shown, to which should be added 10% possible systematic error) for reaction of C4H with alkenes: k(C2H4) = (1.95 +/- 0.17) x 10(-10) (T/298 K)(-0.40) exp(9.4 K/T) cm3 molecule(-1) s(-1); k(C3H6) = (3.25 +/- 0.12) x 10(-10) (T/298 K)(-0.84) exp(-48.9 K/T) cm3 molecule(-1) s(-1); k(1-C4H8) = (6.30 +/- 0.35) x 10(-10) (T/298 K)(-0.61) exp(-65.0 K/T) cm3 molecule(-1) s(-1), for reaction of C4H with dienes: k(C3H4) = (3.70 +/- 0.34) x 10(-10) (T/298 K)(-1.18) exp(-91.1 K/T) cm3 molecule(-1) s(-1); k(1,3-C4H6) = (5.37 +/- 0.30) x 10(-10) (T/298 K)(-1.25) exp(-116.8 K/T) cm3 molecule(-1) s(-1), and for reaction of C4H with alkynes: k(C2H2) = (1.82 +/- 0.19) x 10(-10) (T/298 K)(-1.06) exp(-65.9 K/T) cm3 molecule(-1) s(-1); k(C3H4) = (3.20 +/- 0.08) x 10(-10) (T/298 K)(-0.82) exp(-47.5 K/T) cm3 molecule(-1) s(-1); k(1-C4H6) = (3.48 +/- 0.14) x 10(-10) (T/298 K)(-0.65) exp(-58.4 K/T) cm3 molecule(-1) s(-1). Possible reaction mechanisms and product channels are discussed in detail for each of these reactions. Potential implications of these results for models of low temperature chemical environments, in particular cold interstellar clouds and star-forming regions, are considered.

  12. Bactericidal effects of photochemical smog constituents produced by a flow reactor. III. Communication: determination of mutagenic effects of photochemical smog on E. coli K 12 343/113.

    PubMed

    Nover, H; Botzenhart, K

    1985-06-01

    The multipurpose strain E. coli K12 343/113 allows the simultaneous detection of different DNA alterations such as base-pair changes, frameshifts and deletions. The investigations show the detection of mutagenic potency in the mixture which is called photochemical smog, produced by a flow reactor. Responsible for these effects were ozone and hydrocarbon-radicals, but not NOx, hydrocarbons (propene, isobutene, trans-2-butene) and peroxiacetylnitrate (PAN). In the given conditions these mutagenic substances are involved in DNA alterations like base-pair changes and deletions due to the amounts of colonies in the gal+-, MTR-, and arg+-system. No frameshifts could be detected in the nad+-system.

  13. Photo-oxidation of Polymers Synthesized by Plasma and Initiated CVD

    DOE PAGESBeta

    Baxamusa, Salmaan H.; Suresh, Aravind; Ehrmann, Paul; Laurence, Ted; Hanania, Jiries; Hayes, Jeff; Harley, Stephen; Burkey, Daniel D.

    2015-11-09

    Plasma polymers are often limited by their susceptibility to spontaneous and photo-oxidation. We show that the unusual photoluminescence (PL) behavior of a plasma polymer of trans-2-butene is correlated with its photoluminescence strength. These photo-processes occur under blue light illumination (λ=405 nm), distinguishing them from traditional ultraviolet degradation of polymers. These photo-active defects are likely formed during the plasma deposition process and we show that a polymer synthesized using initiated (i)CVD, non-plasma method, has 1000× lower PL signal and enhanced photo-stability. In conclusion, non-plasma methods such as iCVD may therefore be a route to overcoming material aging issues that limit themore » adoption of plasma polymers.« less

  14. [Effects of photochemical smog from a flow reactor on bacteria. I. Determination of the effects of photochemical smog on bacteria].

    PubMed

    Nover, H; Botzenhart, K

    1983-04-01

    To measure the damage to bacteria from photochemical smog Serratia marcescens, Staphylococcus epidermidis, Micrococcus luteus and spores of Bacillus cereus have been exposed to defined gas-mixtures. A smog-simulation-chamber has been used which allowed adjustment of reproducible and longterm constant smog formations due to the flow system. Two methods have been applied to examine the bactericidal effects of the photo-chemical smog: adsorption of bacteria to membrane filters and spraying on silk threads. Smog mixtures formed by olefines (propene 4200 ppb, isobutene 3000 ppb, trans-2-butene 1600 ppb) and nitrogene oxides (500-700 ppb) showed bactericidal effects at ozone levels of 500 ppb. The survival of exposed bacteria is influenced less by gasing with 500 ppb ozone than with the smog mixture.

  15. Photo-oxidation of Polymers Synthesized by Plasma and Initiated CVD

    SciTech Connect

    Baxamusa, Salmaan H.; Suresh, Aravind; Ehrmann, Paul; Laurence, Ted; Hanania, Jiries; Hayes, Jeff; Harley, Stephen; Burkey, Daniel D.

    2015-11-09

    Plasma polymers are often limited by their susceptibility to spontaneous and photo-oxidation. We show that the unusual photoluminescence (PL) behavior of a plasma polymer of trans-2-butene is correlated with its photoluminescence strength. These photo-processes occur under blue light illumination (λ=405 nm), distinguishing them from traditional ultraviolet degradation of polymers. These photo-active defects are likely formed during the plasma deposition process and we show that a polymer synthesized using initiated (i)CVD, non-plasma method, has 1000× lower PL signal and enhanced photo-stability. In conclusion, non-plasma methods such as iCVD may therefore be a route to overcoming material aging issues that limit the adoption of plasma polymers.

  16. Use of propane as a quench gas in argon-filled proportional counters and comparison with other quench gases

    NASA Technical Reports Server (NTRS)

    Agrawal, P. C.; Ramsey, B. D.

    1988-01-01

    An experimental investigation of propane and six other quench gases was carried out in argon-filled proportional counters. The objective of the study was to find the best gas mixture for optimizing the gas gain and the energy resolution as well as to understand the role of the ionization potential of quench gases in determining these parameters. It was found that the best gas gains and energy resolutions are obtained with propane, ethane, and isobutane in that order. The ionization potentials of these three lie below the argon metastable potentials and have the lowest value of resonance defect compared to the other quench gases. The better results obtained with these mixtures can be explained by an increased ionization yield resulting from the Penning effect. Propylene and trans-2-butene give inferior performance compared to the above three gases. Methane and carbon dioxide, the most commonly used quench gases in the argon-filled detectors, provide the worst results.

  17. Metal-containing plasma-polymerized coatings for laser-fusion targets

    SciTech Connect

    Letts, S.A.; Jordan, C.W.

    1981-09-14

    Addition of metal to plastic layers in some direct drive laser fusion targets is needed to reduce electron induced fuel preheat. A plasma polymerization coating system was constructed to produce a metal seeded polymer by adding an organometallic gas to the usual trans-2-butene and hydrogen feedstocks. Since organometallic gases are highly reactive and toxic, safety is a major concern in the design of a coating system. Our coating apparatus was designed with three levels of containment to assure protection of the operator. The gas handling system has redundant valves and was designed to fail safe. Several sensor controlled interlocks assure safe operating conditions. Waste materials are collected on a specially designed cold trap. Waste disposal is accomplished by heating the traps and purging volatile products through a reactor vessel. The design, operating procedure, and safety interlocks of this novel coating system are described.

  18. Pulmonary function in normal and elastase-treated hamsters exposed to a complex mixture of olefin-ozone-sulfur dioxide reaction products

    SciTech Connect

    Raub, J.A.; Miller, F.J.; Graham, J.A.; Gardner, D.E.; O'Neil, J.J.

    1983-01-01

    An elastase-induced emphysema model was utilized to determine if hamsters with preexisting lung disease were more susceptible to lung damage from air-pollutant exposure. Male golden hamsters, divided into two treatment groups, were given a single intratracheal injection of either 6 units of porcine pancreatic elastase (EMP) or buffer (CNT). After a 4-week recovery period, equal numbers of each group were exposed 23 hr/day x 28 day to filtered air (AIR) or to the complex by-products from a dark-phase-reaction mixture of trans-2-butene, ozone, and sulfur dioxide (MIX). Lung-function measurements on the elastase-treated groups showed changes consistent with mild emphysema. There were no significant differences in lung volumes or lung compliance between the AIR- and MIX-exposed animals. However, the nitrogen washout slope decreased and the diffusing capacity for carbon monoxide increased in both the CNT and EMP hamsters exposed to the MIX. The change in diffusing capacity was greater in normal hamsters than in hamsters with emphysema, and it is hypothesized that animals with impaired lung function had a decreased ability to respond to a pulmonary insult from the mix.

  19. Combined effects of organic reactivity and NMHC/NOx ratio on photochemical-oxidant formation - a modeling study

    SciTech Connect

    Dodge, M.C.

    1984-01-01

    A modeling study was undertaken to assess the effect of organic reactivity on photochemical-oxidant formation. A six-component hydrocarbon model was developed and tested against data collected in a smog chamber study of irradiated auto exhaust and oxides of nitrogen NOx mixtures. The model was then adjusted to conditions that closely approximated those of the urban environment and used to assess the relative reactivity of various organic constituents present in an urban-like air mass. Twelve organics were investigated in the study: ethane, propane, n-butane, ethylene, propylene, trans-2-butene, toluene, m-xylene, methanol, ethanol, formalehyde, and acetaldehyde. The findings of this study indicate that the reactivity of organics depends strongly on the hydrocarbon-to-NOx ratio of the mix in which they are reacting. At low hydrocarbon-to-NOx ratios, the organics investigated in this study displayed significantly different O/sub 3/-forming potentials. At high hydrocarbon-to-NOx ratios, however, all organics exhibited comparable O to 3-forming potential.

  20. Evaluation of Fluidized Beds for Mass Production of IFE Targets

    SciTech Connect

    Huang, H.; Vermillion, B.A.; Brown, L.C.; Besenbruch, G.E.; Goodin, D.T.; Stemke, R.W.; Stephens, R.B.

    2005-01-15

    Of the building blocks of an inertial fusion energy (IFE) plant, target fabrication remains a significant credibility issue. For this reason, an extensive parametric study has been conducted on mass production of glow discharge polymer (GDP) shells in a vertical fluidized bed. Trans-2-butene was used as a reactant gas with hydrogen as a diluting and etching agent. Coating rates in the range of 1 to 2 {mu}m/h were demonstrated on batches of 30 shells where National Ignition Facility-quality surfaces were obtained for 3- to 5-{mu}m-thick coatings. Thick coatings up to 325 {mu}m were also demonstrated that are visually transparent, without void and stress fracture. A phenomenological understanding of the GDP growth mechanisms to guide future experiments was further established. Specifically, gas-phase precipitation and high-impact collisions were identified as the main surface-roughening mechanisms. The former produces dense cauliflower-like surface patterns that can be eliminated by adjusting the gas flow rates and the flow ratio. The latter produces isolated domelike surface defects that can be reduced by introducing concerted motion between the shells. By converting from a vertical to a horizontal configuration, fully transparent coatings were obtained on 350 shells. Collisions in a fluidized bed have been identified as the limiting factor in meeting IFE specifications, and a related-rotary kiln technique is recommended for scale-up.

  1. Moessbauer spectra of ferrite catalysts used in oxidative dehydrogenation

    NASA Technical Reports Server (NTRS)

    Cares, W. R.; Hightower, J. W.

    1971-01-01

    Room temperature Mossbauer spectroscopy was used to examine bulk changes which occur in low surface area CoFe2O4 and CuFe2O4 catalysts as a result of contact with various mixtures of trans-2-butene and O2 during oxidative dehydrogenation reactions at about 420 C. So long as there was at least some O2 in the gas phase, the CoFe2O4 spectrum was essentially unchanged. However, the spectrum changed from a random spinel in the oxidized state to an inverse spinel as it was reduced by oxide ion removal. The steady state catalyst lies very near the fully oxidized state. More dramatic solid state changes occurred as the CuFe2O4 underwent reduction. Under severe reduction, the ferrite was transformed into Cu and Fe3O4, but it could be reversibly recovered by oxidation. An intense doublet located near zero velocity persisted in all spectra of CuFe2O4 regardless of the state of reduction.

  2. The use of design-of-experiments methodology to optimize polymer capsule fabrication. 1998 summer research program for high school juniors at the University of Rochester`s Laboratory for Laser Energetics: Student research reports

    SciTech Connect

    Lai, L.

    1999-03-01

    Future inertial-fusion experiments on Omega will utilize {approximately} 1 mm-diameter cryogenic targets that have a {approximately} 100-{micro}m-thick, uniformly-frozen fuel layer on their interior. It is desired that they have a stress-free wall thickness < 1 {micro}m and an rms surface roughness < 20 nm. A design-of-experiments (DOE) approach was used to characterize a glow-discharge-polymerization coater built at LLE to fabricate smooth, stress-free capsules with submicron wall thicknesses. The DOE approach was selected because several parameters can be changed simultaneously in a manner which allows the minimum number of runs to be performed to obtain statistically-relevant data. Planar, silicon substrates were coated with {approximately} 3--5 {micro}m of polymer and profilometry was used to determine the coating rate, the film stress, and the surface roughness. The coating rate was found to depend on the trans-2-butene/hydrogen ratio, the total gas-flow rate, the total chamber pressure, and the RF power. In addition, a two-parameter interaction between the total pressure and the RF power also affects the coating rate. The film stress depends on the total chamber pressure and the total mass-flow rate. The surface roughness is independent of the parameters studied. Preliminary results indicate that capsules can be produced rapidly without affecting the smoothness of their outside surface and without residual stress in their walls.

  3. Effects of rf power on chemical composition and surface roughness of glow discharge polymer films

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; He, Xiaoshan; Chen, Guo; Wang, Tao; Tang, Yongjian; He, Zhibing

    2016-03-01

    The glow discharge polymer (GDP) films for laser fusion targets were successfully fabricated by plasma enhanced chemical vapor deposition (PECVD) at different radio frequency (rf) powers. The films were deposited using trans-2-butene (T2B) mixed with hydrogen as gas sources. The composition and state of plasma were diagnosed by quadrupole mass spectrometer (QMS) and Langmuir probe during the deposition process. The composition, surface morphology and roughness were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and white-light interferometer (WLI), respectively. Based on these observation and analyses, the growth mechanism of defects in GDP films were studied. The results show that, at low rf power, there is a larger probability for secondary polymerization and formation of multi-carbon C-H species in the plasma. In this case, the surface of GDP film turns to be cauliflower-like. With the increase of rf power, the degree of ionization is high, the relative concentration of smaller-mass hydrocarbon species increases, while the relative concentration of larger-mass hydrocarbon species decreases. At higher rf power, the energy of smaller-mass species are high and the etching effects are strong correspondingly. The GDP film's surface roughness shows a trend of decrease firstly and then increase with the increasing rf power. At rf power of 30 W, the surface root-mean-square roughness (Rq) drops to the lowest value of 12.8 nm, and no "void" defect was observed.

  4. Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes. Final report

    SciTech Connect

    Norton, J.R.

    1994-04-25

    Assignment of the vibrational modes Of Os{sub 2}(CO){sub 8}(CHCH{sub 3}) and Os(CO){sub 4}(C{sub 2}H{sub 4)} has given fingerprint vibrational spectra for the following species when chemisorbed on metal catalyst surfaces: ethylidene and ethylene bound in a metallacyclopropane mode. The formation and fragmentation of diosmacyclobutanes have been shown to involve slippage of the outgoing olefin onto a single osmium, and associative exchange of the olefin from that site. The incorporation of vinylcyclopropane without rearrangement has confirmed the absence of a diradical intermediate. The anomalous stability of the diosmacyclobutane derived from trans-2-butene has proven due to greater destabilization (by the substituent methyls) of the slipped intermediate than of the ground state. Reaction of an osmacyclobutane with 1,3- or 1,2-dienes (allenes) gives 1,2 rather than 1,4 addition to the diosmium unit. Treatment of Os(CO){sub 4}(C{sub 2}H{sub 4}) with triflic acid results in the formation of Os(CO){sub 4}(C{sub 2}H{sub 5})OTf. The authors have found that the reaction of an aryl iodine(III) reagent with propargyl stannanes or silanes results in o-iodo propargyl arenes.

  5. Permselective, metal chelate containing, plasma polymers

    SciTech Connect

    Morosoff, N.C.; Clymer, S.D.; Stannett, V.T.; Skelly, J.M.; Crumbliss, A.L.

    1993-12-31

    Metal chelates, including cobalt Schiff bases and a cobalt porphyrin complex, have been codeposited with hydrocarbon plasma polymers to form thin films. The hydrocarbon monomers used were trans-2-butene and cyclooctene. The sorption of O{sub 2} by such membranes before and after reaction with pyridine (Pyr) or 1-methylimidazole (1-MeIm) was measured and the association FTIR and uv/visible absorption spectra were obtained. In addition permeability to O{sub 2} and N{sub 2} was determined. It was found that the structure of the metal chelates, which were sublimed into the plasma, was preserved. When bound to an axial base (Pyr or 1-MeIm), the plasma polymer occluded chelates bound O{sub 2} reversibly. O{sub 2} diffusion coefficients varied with the nature of the plasma polymer matrix. The ideal separation factor (O{sub 2}/N{sub 2}) increased for metal chelate containing plasma polymers vis-a-vis that for the plasma polymer matrix (without metal chelate). The ideal separation factor was at a maximum for low metal chelate loading and at a {open_quotes}mass thickness{close_quotes} of {approximately} 10 {mu}g/(cm{sup 2}min).

  6. A sputtering derived atomic oxygen source for studying fast atom reactions

    NASA Technical Reports Server (NTRS)

    Ferrieri, Richard A.; Yung, Y. Chu; Wolf, Alfred P.

    1987-01-01

    A technique for the generation of fast atomic oxygen was developed. These atoms are created by ion beam sputtering from metal oxide surfaces. Mass resolved ion beams at energies up to 60 KeV are produced for this purpose using a 150 cm isotope separator. Studies have shown that particles sputtered with 40 KeV Ar(+) on Ta2O5 were dominantly neutral and exclusively atomic. The atomic oxygen also resided exclusively in its 3P ground state. The translational energy distribution for these atoms peaked at ca 7 eV (the metal-oxygen bond energy). Additional measurements on V2O5 yielded a bimodal distribution with the lower energy peak at ca 5 eV coinciding reasonably well with the metal-oxygen bond energy. The 7 eV source was used to investigate fast oxygen atom reactions with the 2-butene stereoisomers. Relative excitation functions for H-abstraction and pi-bond reaction were measured with trans-2-butene. The abstraction channel, although of minor relative importance at thermal energy, becomes comparable to the addition channel at 0.9 eV and dominates the high-energy regime. Structural effects on the specific channels were also found to be important at high energy.

  7. Synthesis of the E and Z isomers of the antiestrogen tamoxifen and its metabolite, hydroxytamoxifen, in tritium-labeled form

    SciTech Connect

    Robertson, D.W.; Katzenellenbogen, J.A.

    1982-06-04

    Both isomers of the potent antiestrogen tamoxifen (1,2-diphenyl-1-(4-(2-(dimethylamino)ethoxy)phenyl)-1-butene: E isomer = ICI-47699; Z isomer = ICI-46474, Nolvadex) and its metabolite, hydroxytamoxifen (1-(4-(2-(dimethylamino)ethoxy)phenyl)-1-(4-hydroxyphenyl)-2-phenyl-1-butene), have been synthesized in a high specific activity, tritium-labeled form by catalytic tritium-halogen exchange performed on brominated precursors. The synthesis of another precursor to labeled tamoxifen which would enable the incorporation of three tritium atoms into the molecule by tritium-halogen exchange is reported.

  8. Roughness Optimization at High Modes for GDP CHx Microshells

    SciTech Connect

    Theobald, M.; Dumay, B.; Chicanne, C.; Barnouin, J.; Legaie, O.; Baclet, P.

    2004-03-15

    For the ''Megajoule'' Laser (LMJ) facility of the CEA, amorphous hydrogenated carbon (a-C:H) is the nominal ablator to be used for inertial confinement fusion (ICF) experiments. These capsules contain the fusible deuterium-tritium mixture to achieve ignition. Coatings are prepared by glow discharge polymerization (GDP) with trans-2-butene and hydrogen. The films properties have been investigated. Laser fusion targets must have optimized characteristics: a diameter of about 2.4 mm for LMJ targets, a thickness up to 175 {mu}m, a sphericity and a thickness concentricity better than 99% and an outer and an inner roughness lower than 20 nm at high modes. The surface finish of these laser fusion targets must be extremely smooth to minimize hydrodynamic instabilities.Movchan and Demchishin, and later Thornton introduced a structure zone model (SZM) based on both evaporated and sputtered metals. They investigated the influence of base temperature and the sputtering gas pressure on structure and properties of thick polycrystalline coatings of nickel, titanium, tungsten, aluminum oxide. An original cross-sectional analysis by atomic force microscopy (AFM) allows amorphous materials characterization and permits to make an analogy between the amorphous GDP material and the existing model (SZM). The purpose of this work is to understand the relationship between the deposition parameters, the growing structures and the surface roughness.The coating structure as a function of deposition parameters was first studied on plane silicon substrates and then optimized on PAMS shells. By adjusting the coating parameters, the structures are modified, and in some case, the high modes roughness decreases dramatically.

  9. Kinetics of the gas-phase reactions of NO/sub 3/ radicals with a series of dialkenes, cycloalkenes, and monoterpenes at 295 +/- 1 K

    SciTech Connect

    Atkinson, R.; Aschmann, S.M.; Winer, A.M.; Pitts, J.N. Jr.

    1984-05-01

    Rate constants for the gas-phase reactions of the NO/sub 3/ radical, an important reactive constituent of nighttime ambient atmospheres, have been determined for the first time for a series of dialkenes, cycloalkenes, and monoterpenes by using a relative rate technique. By use of a rate constant for the reaction of NO/sub 3/ radicals with trans-2-butene of (2.11 +/- 0.24) x 10 /sup -13/ cm/sup 3/ molecule /sup -1/s/sup -1/, the rate constants obtained at 295 +/- 1 K were the following (in cm/sup 3/ molecule/sup -1/s/sup -1/ units): 1,3-butadiene, (5.34 +/- 0.62) x 10/sup -14/; isoprene, (3.23 +/- 0.38) x 10/sup -13/; cyclohexene, (2.87 +/- 0.34) x 10/sup -13/; 1,3-cyclohexadiene, (7.2 +/- 1.7) x 10/sup -12/; 1,4-cyclohexadiene, (2.89 +/- 0.35) x 10/sup -13/; 1,3-cycloheptadiene, (3.8 +/- 0.9) x 10/sup -12/; ..cap alpha..-pinene, (3.4 +/- 0.8) x 10/sup -12/; ..beta..-pinene, (1.4 +/- 0.3) x 10/sup -12/; ..delta../sup 3/-carene, (5.9 +/- 1.3) x 10/sup -12/; d-limonene, (7.7 +/- 1.7) x 10/sup -12/. These NO/sub 3/ radical rate constants for the naturally emitted hydrocarbons isoprene and the monoterpenes, in conjunction with measured ambient NO/sub 3/ radical concentrations, show that nighttime reaction with the NO/sub 3/ radical can be an important, if not dominant, loss process for these organics. Similarly, these reactions can also be an important loss process for NO/sub 3/ radicals, and hence for NO/sub x/, during nighttime hours. 43 references.

  10. Sources of Volatile Organic Compounds (VOCs) in the UAE

    NASA Astrophysics Data System (ADS)

    Abbasi, Naveed; Majeed, Tariq; Iqbal, Mazhar; Riemer, Daniel; Apel, Eric; Lootah, Nadia

    The gas chromatography-flame ionization detection/mass spectrometry system has been used to identify major volatile organic compounds (VOCs) sources in the UAE (latitude 24.45N; longitude 54.22E). VOCs are emitted from an extensive number of sources in urban environments including fuel production, distribution, and consumption. Transport sources contribute a substantial portion of the VOC burden to the urban atmosphere in developed regions. UAE is located at the edge of the Persian Gulf and is highly affected by emissions from petrochemical industries in neighbouring Saudi Arabia, Qatar, and Iran. VOCs emerging from these industries can be transported to the UAE with jet streams. The analysis of the collected air samples at three locations in Sharjah, UAE during the autumn and winter seasons indicates the presence of more than 100 VOC species. The concentrations of these species vary in magnitudes but the most prominent are: acetylene, ethane, propane, butane, pentane, benzene, and toluene. The possible tracers for various emission sources have also been identified such as 2-methylpentane, 1, 3-butadiene and 2, 2-dimethlybutane for vehicle exhaust, the light hydrocarbons, namely n-butane, trans-2-butene, and n-pentane for gasoline vapor, and n-nonane, n-decane, and n-undecane for diesel vapor and asphalt application processes. As various emission sources are characterized by overlapping VOC species, the ratio of possible VOC tracers are used to quantify the contribution of different sources. Our aim in this paper is to explore and discuss possible impacts of transported emissions on the local VOC emission inventory from various sources for the UAE. This work is partially supported by Office of Development and Alumni Affairs at the American University of Sharjah, U.A.E.

  11. Systematic preparation of selective heterogeneous catalysts. Final report, September 1, 1984--August 31, 1991

    SciTech Connect

    Augustine, R.L.

    1991-11-07

    The Single Turnover (STO) procedure, involving pulses of hydrogen and 1-butene, was developed for studying the types of active sites present on supported metal catalysts. The STO procedure was used to study direct saturated sites and other topics. Frontier molecular orbital studies were also made.

  12. Systematic preparation of selective heterogeneous catalysts

    SciTech Connect

    Augustine, R.L.

    1991-11-07

    The Single Turnover (STO) procedure, involving pulses of hydrogen and 1-butene, was developed for studying the types of active sites present on supported metal catalysts. The STO procedure was used to study direct saturated sites and other topics. Frontier molecular orbital studies were also made.

  13. Cut C/sub 4/ recovery costs

    SciTech Connect

    Strigle, R.F.; Fukuyo, K.

    1986-06-01

    A system to recover 1-butene, consisting of a four column distillation train, has been installed in Nippon Petrochemical Co., Ltd's. plant. The first two columns were operated in series and removed iso-butane overhead as distillate from the other C/sub 4/ hydrocarbons in the feed. The last two columns also were operated in series and recovered high purity 1-butene (99+ percent) as distillate using the bottoms from the first pair of columns as feed. The bottoms from this second pair of columns contained all the n-butane present in the feed to the system plus the 2-butene isomers. The distillate from the first pair of columns was combined with the bottoms from the second pair of columns, and this mixture was sold as butane fuel. Each of the first pair of columns contained 70 actual trays on 400-mm spacing. These single-pass trays developed an overall efficiency of only 59 percent. Table 1 shows the operation of the first pair of the trayed columns separating isobutane from 1-butene. The relative volatility between isobutane and 1-butene is very low-only 1.10. In fact, this separation has such a low relative volatility that the temperature rise is only 1/sup 0/C per theoretical stage.

  14. Characterization of oxygenated derivatives of isoprene related to 2-methyltetrols in Amazonian aerosols using trimethylsilylation and gas chromatography/ion trap mass spectrometry.

    PubMed

    Wang, Wu; Kourtchev, Ivan; Graham, Bim; Cafmeyer, Jan; Maenhaut, Willy; Claeys, Magda

    2005-01-01

    In the present study, we have tentatively identified the structures of three oxygenated derivatives of isoprene in Amazonian rain forest aerosols as the C(5) alkene triols, 2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene. The formation of these oxygenated derivatives of isoprene can be explained by acid-catalyzed ring opening of epoxydiol derivatives of isoprene, namely, 1,2-epoxy-2-methyl-3,4-dihydroxybutane and 1,2-dihydroxy-2-methyl-3,4-epoxybutane. The structural proposals of the C(5) alkene triols were based on chemical derivatization reactions and detailed interpretation of electron and chemical ionization mass spectral data, including data obtained from first-order mass spectra, deuterium labeling of the trimethylsilyl methyl groups, and MS(2) ion trap experiments. The characterization of 2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene in forest aerosols is important from an atmospheric chemistry viewpoint in that these compounds hint at the formation of intermediate isomeric epoxydiol derivatives of isoprene and as such provide mechanistic insights into the formation of the previously reported 2-methyltetrols through photooxidation of isoprene.

  15. Determination of Tamoxifen and its Major Metabolites in Exposed Fish

    EPA Science Inventory

    Tamoxifen (TAM), (Z)-1-(p-dimethylaminoethoxyphenyl)-1, 2-diphenyl-1-butene, is a nonsteroidal agent that has been used in breast cancer treatment for decades. Its major metabolites are 4-hydroxytamoxifen (4-OHT), N-desmethyltamoxifen (DMT), and endoxifen. While TAM and metabolit...

  16. Non-methane hydrocarbons (NMHCs) and their contribution to ozone formation potential in a petrochemical industrialized city, Northwest China

    NASA Astrophysics Data System (ADS)

    Jia, Chenhui; Mao, Xiaoxuan; Huang, Tao; Liang, Xiaoxue; Wang, Yanan; Shen, Yanjie; Jiang, Wanyanhan; Wang, Huiqin; Bai, Zhilin; Ma, Minquan; Yu, Zhousuo; Ma, Jianmin; Gao, Hong

    2016-03-01

    Hourly air concentrations of fifty-three non-methane hydrocarbons (NMHCs) were measured at downtown and suburb of Lanzhou, a petrochemical industrialized city, Northwest China in 2013. The measured data were used to investigate the seasonal characteristics of NMHCs air pollution and their contributions to the ozone formation in Lanzhou. Annually averaged NMHCs concentration was 38.29 ppbv in downtown Lanzhou. Among 53 NMHCs, alkanes, alkenes, and aromatics accounted for 57%, 23% and 20% of the total NMHCs air concentration, respectively. The atmospheric levels of toluene and propane with mean values of 4.62 and 4.56 ppbv were higher than other NMHCs, respectively. The ambient levels of NMHCs in downtown Lanzhou were compared with measured NMHCs data collected at a suburban site of Lanzhou, located near a large-scale petrochemical industry. Results show that the levels of alkanes, alkenes, and aromatics in downtown Lanzhou were lower by factors of 3-11 than that in west suburb of the city. O3-isopleth plots show that ozone was formed in VOCs control area in downtown Lanzhou and NOx control area at the west suburban site during the summertime. Propylene-equivalent (Prop-Equiv) concentration and the maximum incremental reactivity (MIR) in downtown Lanzhou indicate that cis-2-butene, propylene, and m/p-xylene were the first three compounds contributing to ozone formation potentials whereas in the petrochemical industrialized west suburb, ethane, propene, and trans-2-Butene played more important role in the summertime ozone formation. Principal component analysis (PCA) and multiple linear regression (MLR) were further applied to identify the dominant emission sources and examine their fractions in total NMHCs. Results suggest that vehicle emission, solvent usage, and industrial activities were major sources of NMHCs in the city, accounting for 58.34%, 22.19%, and 19.47% of the total monitored NMHCs in downtown Lanzhou, respectively. In the west suburb of the city

  17. The Effect of Cavitating Ultrasound on the Aqueous Phase Hydrogenation of Cis-2-buten-1-ol and Cis-2-penten-1-ol on Pd-black

    SciTech Connect

    Disselkamp, Robert S.; Denslow, Kayte M.; Hart, Todd R.; White, James F.; Peden, Charles HF.

    2005-07-15

    We have studied the effect of cavitating ultrasound on the heterogeneous aqueous hydrogenation of cis-2-buten-1-ol (C4 olefin) and cis-2-penten-1-ol (C5 olefin) on Pd-black to form the trans-olefins (trans-2-buten-1-ol and trans-2-penten-1-ol) and saturated alcohols (1-butanol and 1-pentanol, respectively). Silent (and magnetically stirred) experiments served as control experiments. As described in an earlier publication by our group, we have added an inert dopant, 1-propanol, in the reaction mixture to ensure the rapid onset of cavitation in the ultrasound-assisted reactions that can lead to altered selectivity compared to silent reaction systems [Disselkamp et al., J. Catal., 227 (2004) 552]. The motivation for this study is to examine whether cavitating ultrasound can reduce the [trans-olefin/saturated alcohol] molar ratio during the course of the reaction. This could have practical application in that it may offer an alternative processing methodology of synthesizing healthier edible seed oils by reducing trans-fat content. We have observed that cavitating ultrasound results in a [(trans-olefin/saturated alcohol)ultrasound/(trans-olefin/saturated alcohol)silent] ratio quantity less than 0.5 at the reaction mid-point for both the C4 and C5 olefin systems. This indicates that ultrasound reduces trans-olefin production compared to the silent control experiment. Furthermore, there is an added 30% reduction for the C5 versus C4 olefin compounds again at reaction mid-point. We attribute differences in the ratio quantity as a moment of inertia effect. In principle, the C4 versus C5 olefins has a {approx}52% increase in moment of inertia about C2=C3 double bond slowing isomerization. Since seed oils are C18 multiple cis olefins and have an moment of inertia even greater than our C5 olefin here, our study suggests that even a greater reduction in trans-olefin content may occur for partial hydrogenation of C18 seed oils.

  18. The effect of cavitating ultrasound on the aqueous phase hydrogenation of cis-2-buten-1-ol and cis-2-penten-1-ol on Pd-black

    SciTech Connect

    Disselkamp, Robert S.; Denslow, Kayte M.; Hart, Todd R.; White, James F.; Peden, Charles HF.

    2005-07-15

    We have studied the effect of cavitating ultrasound on the heterogeneous aqueous hydrogenation of cis-2-buten-1-ol (C4 olefin) and cis-2-penten-1-ol (C5 olefin) on Pd-black to form the trans-olefins (trans-2-buten-1-ol and trans-2-penten-1-ol) and saturated alcohols (1-butanol and 1-pentanol, respectively). Silent (and magnetically stirred) experiments served as control experiments. As described in an earlier publication by our group, we have added an inert dopant, 1-propanol, in the reaction mixture to ensure the rapid onset of cavitation in the ultrasound-assisted reactions that can lead to altered selectivity compared to silent reaction systems [R.S. Disselkamp, Ya-Huei Chin, C.H.F. Peden, J. Catal. 227 (2004) 552]. The motivation for this study is to examine whether cavitating ultrasound can reduce the [trans-olefin/saturated alcohol] molar ratio during the course of the reaction. This could have practical application in that it may offer an alternative processing methodology of synthesizing healthier edible seed oils by reducing trans-fat content.We have observed that cavitating ultrasound results in a [(trans-olefin/saturated alcohol)ultrasound/(trans-olefin/saturated alcohol)silent] ratio quantity less than 0.5 at the reaction mid-point for both the C4 and C5 olefin systems. This indicates that ultrasound reduces trans-olefin production compared to the silent control experiment. Furthermore, there is an added 30% reduction for the C5 versus C4 olefin compounds again at reaction mid-point. We attribute differences in the ratio quantity as a moment of inertia effect. In principle, the C4 versus C5 olefins has a {approx}52% increase in moment of inertia about C2 C3 double bond slowing isomerization. Since seed oils are C18 multiple cis-olefins and have a moment of inertia even greater than our C5 olefin here, our study suggests that even a greater reduction in trans-olefin content may occur for partial hydrogenation of C18 seed oils.

  19. Theoretical kinetics studies of two model reactions in biodiesel and diesel combustion

    NASA Astrophysics Data System (ADS)

    Sha, Yuan

    We use 1-methylallyl radical (CH3CH=CH-CH2· ↔ CH3C·H-CH=CH2·) as a model of allylic radicals generated during combustion of unsaturated diesel fuel molecules. The chemically activated isomerization of 1-methylallyl generated in the highly exothermic (˜35 kcal/mol) OH + trans-2-butene reaction was considered by using RRKM/Master Equation calculations from 0.01 to 100 atm and from 300 to 700 K. Density functional theory (DFT) with the M05-2X, M06-2X and B3LYP functionals are used for structures, energies, vibrational frequencies, anharmonic constants, and the torsional potentials of methyl rotations. The cis:trans ratio formed upon quenching the radicals were, as might be expected, dependent on the functional, but, were even more sensitive when an vibrations were treated as anharmonic. The fraction of cis- 1-methylallyl is significant, if not dominant at 300 -700 K and 0.01 -10 atm. Sensitivity studies were carried out to determine the dependence of the cis:trans ratio on the extent of chemical activation, treatment of the K-rotor as active or inactive, and the rate of collisional energy transfer. All these parameters significantly influence the cis:trans ratio. The 1,5 H-migration reaction of 3-hydroperoxy-1-propylperoxy radical (HOOCH2CH2CH2OO·) is a important as a model of a critical propagation step in diesel autoignition from alkanes or molecules with long alkyl tails. Its product may be the meta-stable alpha,gamma-dihydroperoxypropyl radical or, if unstable, OH + 3-hydroperoxypropanal. To study the possibly different tunneling effects of the two possible products, the quantum mechanical rate constants, including tunneling, are directly determined using semi-classical transition state theory (SCTST) at 200 K to 1700 K. Small-curvature tunneling (SCT) is to compute tunneling corrections to classical rate constants. The two reactions do not have obvious tunneling differences at above 700 K. Below 700 K, SCTST tunneling corrections are significantly higher

  20. The Origin of Regioselectivity in 2-butanol Dehydration on Solid Acid Catalysts

    SciTech Connect

    Kwak, Ja Hun; Rousseau, Roger J.; Mei, Donghai; Peden, Charles HF; Szanyi, Janos

    2011-10-17

    The origin in the variations of trans-/cis-2-butene product selectivity ratios in 2-butanol dehydration over solid acid catalysts were investigated using a combined experimental-theory approach. Reactivity measurements over γ-Al2O3, AlOx/SBA-15, and H-form zeolites with widely varying Si/Al ratios and pore structures showed over two orders of magnitude change in the trans-/cis-2-butene product ratio. Activation energy barriers calculated for the concerted C-O and β-C-H bond breakings of adsorbed butoxy intermediates by dispersion-corrected DFT calculations correctly predicted the trans-/cis-2-butene product ratio observed on γ-Al2O3. The very low trans-2-butene selectivity on γ-Al2O3 can now be understood by the formation of a late transition state with high energy barrier caused by the strong van der Waals interaction between the γ-H atoms and the flat catalyst surface. Decreasing the dispersive attractive force between the adsorbed butoxide and the surface (e.g., by moving it further away from the support surface in AlOx/SBA-15) leads to almost equimolar formation of the trans- and cis-2-butene isomers. Trans-/cis-2-butene selectivity ratios much higher than that dictated by thermodynamic equilibrium can be achieved by introducing additional geometric constraints around the active catalytic site (e.g., varying the 3D environment around the active center in zeolites). We propose a model to explain the widely varying trans-/cis-2-butene selectivity in 2-butanol dehydration over solid acid catalysts that is consistent with the experimental results in this study. A key outcome of the study is the realization that van der Waals interactions between the reactant and the active catalyst surface must be included in the theoretic models in order to be able to accurately predict product selectivities. This information, in turn, significantly advances our ability to develop catalyst materials with designed active centers in order to achieve desired regioselectivities.

  1. [Pollution characteristics and health risk assessment of atmospheric VOCs in the downtown area of Guangzhou, China].

    PubMed

    Li, Lei; Li, Hong; Wang, Xue-Zhong; Zhang, Xin-Min; Wen, Chong

    2013-12-01

    The measurements of 31 kinds of VOCs in the ambient air of a site were carried out in the downtown of Guangzhou by online method from November 5, 2009 to November 9, 2009. The ambient level and composition characteristics, temporal variation characteristics, sources identification, and chemical reactivity of VOCs were studied, and the health risk of VOCs in the ambient air in the study area was assessed by using the international recognized health risk assessment method. Results showed that the mean and the range of the mass concentrations of 31 VOCs were 114.51 microg x m(-3) and 29.42-546.06 microg x m(-3), respectively. The mass concentrations of 31 VOCs, and those of alkanes, alkenes, and aromatics all showed a changing trend of higher in the morning and in the evening, and lower at noontime. Vehicular exhaust, gasoline and liquefied petroleum gas evaporates were the main sources of VOCs with the volatilization of paints and solvents being important emission sources. Toluene, trans-2-butene, m/p-xylene, i-butane, and 1,3,5-trimethylbenzene were the key reactive species among the 31 VOCs. Vehicular exhaust and gasoline evaporation were the main sources of VOCs leading to the formation of ozone. Health risk assessment showed that n-hexane, 1,3-butadiene, benzene, toluene, ethylbenzene, m/p-xylene and o-xylene had no appreciable risk of adverse non-cancer health effect on the exposed population, but 1, 3-butadiene and benzene had potential cancer risk. By comparing the corresponding data about health risk assessment of benzene compounds in some cities in China, it is concluded that benzene can impose relatively high cancer risk to the exposed populations in the ambient air of some cities in China. Therefore, strict countermeasures should be taken to further control the pollution of benzene in the ambient air of cities, and it is imperative to start the related studies and develop the atmospheric environmental health criteria and national ambient air quality

  2. Synthesis of amphiphilic diblock copolymer for surface modification of Ethylene-Norbornene Copolymers

    NASA Astrophysics Data System (ADS)

    Levinsen, Simon; Svendsen, Winnie Edith; Horsewell, Andy; Almdal, Kristoffer

    2014-03-01

    The aim of this work is to produce polymer modifiers in order to develop hydrophilic polymeric surfaces for use in microfluidics. The use of hydrophilic polymers in microfluidics will have many advantages e.g. preventing protein absorbance. Here we present an amphiphilic diblock copolymer consisting of a bulk material compatible block and a hydrophilic block. To utilize the possibility of incorporating diblock copolymers into ethylene-norbornene copolymers, we have in this work developed a model poly(ethylene-1-butene) polymer compatible with the commercial available ethylene-norbornene copolymer TOPAS. Through matching of the radius of gyration for the model polymer and TOPAS the miscibility was achieved. The poly(ethylene-1-butene) polymer was synthesized from a hydrogenated anionic polymerized polybutadiene polymer. As hydrophilic block poly(ethylene oxide) was subsequently added also with anionic polymerization. Recent miscibility results between the model polymer and TOPAS will be presented, as well ongoing efforts to study the hydrophilic surface.

  3. Effects of metal and acidic sites on the reaction by-products of butyl acetate oxidation over palladium-based catalysts.

    PubMed

    Yue, Lin; He, Chi; Hao, Zhengping; Wang, Shunbing; Wang, Hailin

    2014-03-01

    Catalytic oxidation is widely used in pollution control technology to remove volatile organic compounds. In this study, Pd/ZSM-5 catalysts with different Pd contents and acidic sites were prepared via the impregnation method. All the catalysts were characterized by means of N2 adsorption-desorption, X-ray fluorescence (XRF), H2 temperature programmed reduction (H2-TPR), and NH3 temperature programmed desorption (NH3-TPD). Their catalytic performance was investigated in the oxidation of butyl acetate experiments. The by-products of the reaction were collected in thermal desorption tubes and identified by gas chromatography/mass spectrometry. It was found that the increase of Pd content slightly changed the catalytic activity of butyl acetate oxidation according to the yield of CO2 achieved at 90%, but decreased the cracking by-products, whereas the enhancement of strong acidity over Pd-based catalysts enriched the by-product species. The butyl acetate oxidation process involves a series of reaction steps including protolysis, dehydrogenation, dehydration, cracking, and isomerization. Generally, butyl acetate was cracked to acetic acid and 2-methylpropene and the latter was an intermediate of the other by-products, and the oxidation routes of typical by-products were proposed. Trace amounts of 3-methylpentane, hexane, 2-methylpentane, pentane, and 2-methylbutane originated from isomerization and protolysis reactions. PMID:25079284

  4. Effects of metal and acidic sites on the reaction by-products of butyl acetate oxidation over palladium-based catalysts.

    PubMed

    Yue, Lin; He, Chi; Hao, Zhengping; Wang, Shunbing; Wang, Hailin

    2014-03-01

    Catalytic oxidation is widely used in pollution control technology to remove volatile organic compounds. In this study, Pd/ZSM-5 catalysts with different Pd contents and acidic sites were prepared via the impregnation method. All the catalysts were characterized by means of N2 adsorption-desorption, X-ray fluorescence (XRF), H2 temperature programmed reduction (H2-TPR), and NH3 temperature programmed desorption (NH3-TPD). Their catalytic performance was investigated in the oxidation of butyl acetate experiments. The by-products of the reaction were collected in thermal desorption tubes and identified by gas chromatography/mass spectrometry. It was found that the increase of Pd content slightly changed the catalytic activity of butyl acetate oxidation according to the yield of CO2 achieved at 90%, but decreased the cracking by-products, whereas the enhancement of strong acidity over Pd-based catalysts enriched the by-product species. The butyl acetate oxidation process involves a series of reaction steps including protolysis, dehydrogenation, dehydration, cracking, and isomerization. Generally, butyl acetate was cracked to acetic acid and 2-methylpropene and the latter was an intermediate of the other by-products, and the oxidation routes of typical by-products were proposed. Trace amounts of 3-methylpentane, hexane, 2-methylpentane, pentane, and 2-methylbutane originated from isomerization and protolysis reactions.

  5. The Thermodynamic Conjugation Stabilization of 1,3-Butadiyne Is Zero

    ERIC Educational Resources Information Center

    Rogers, Donald W.; Zavitsas, Andreas A.; Matsunaga, Nikita

    2010-01-01

    Many textbooks point out that the thermodynamic stabilization enthalpy of 1 mol of 1,3-butadiene relative to 2 mol of 1-butene or to 1 mol of 1,4-pentadiene is slightly less than 4 kcal mol[superscript -1], owing to conjugation between the double bonds in the 1,3 configuration. It is reasonable to suppose that the analogous thermochemical…

  6. Replacing precious metals with carbide catalysts for hydrogenation reactions

    DOE PAGESBeta

    Ruijun, Hou; Chen, Jingguang G.; Chang, Kuan; Wang, Tiefeng

    2015-03-03

    Molybdenum carbide (Mo₂C and Ni/Mo₂C) catalysts were compared with Pd/SiO₂ for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO₂, Mo₂C showed similar hydrogenation rate for 1,3-butadiene and 1,3-CHD and even higher rate for 1,4-CHD, but with significant deactivation rate for 1,3-CHD hydrogenation. However, the hydrogenation activity of Mo₂C could be completely regenerated by H₂ treatment at 723 K for the three molecules. The Ni modified Mo₂C catalysts retained similar activity for 1,3-butadiene hydrogenation with significantly enhanced selectivity for 1-butene production. The 1-butene selectivity increased with increasing Ni loading below 15%. Among the Nimore » modified Mo₂C catalysts, 8.6%Ni/Mo₂C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO₂. Compared to Pd/SiO₂, both Mo₂C and Ni/Mo₂C showed combined advantages in hydrogenation activity and catalyst cost reduction, demonstrating the potential to use less expensive carbide catalysts to replace precious metals for hydrogenation reactions.« less

  7. Replacing precious metals with carbide catalysts for hydrogenation reactions

    SciTech Connect

    Ruijun, Hou; Chen, Jingguang G.; Chang, Kuan; Wang, Tiefeng

    2015-03-03

    Molybdenum carbide (Mo₂C and Ni/Mo₂C) catalysts were compared with Pd/SiO₂ for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO₂, Mo₂C showed similar hydrogenation rate for 1,3-butadiene and 1,3-CHD and even higher rate for 1,4-CHD, but with significant deactivation rate for 1,3-CHD hydrogenation. However, the hydrogenation activity of Mo₂C could be completely regenerated by H₂ treatment at 723 K for the three molecules. The Ni modified Mo₂C catalysts retained similar activity for 1,3-butadiene hydrogenation with significantly enhanced selectivity for 1-butene production. The 1-butene selectivity increased with increasing Ni loading below 15%. Among the Ni modified Mo₂C catalysts, 8.6%Ni/Mo₂C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO₂. Compared to Pd/SiO₂, both Mo₂C and Ni/Mo₂C showed combined advantages in hydrogenation activity and catalyst cost reduction, demonstrating the potential to use less expensive carbide catalysts to replace precious metals for hydrogenation reactions.

  8. A Glutathione S-Transferase with Activity towards cis-1,2-Dichloroepoxyethane Is Involved in Isoprene Utilization by Rhodococcus sp. Strain AD45

    PubMed Central

    van Hylckama Vlieg, Johan E. T.; Kingma, Jaap; van den Wijngaard, Arjan J.; Janssen, Dick B.

    1998-01-01

    Rhodococcus sp. strain AD45 was isolated from an enrichment culture on isoprene (2-methyl-1,3-butadiene). Isoprene-grown cells of strain AD45 oxidized isoprene to 3,4-epoxy-3-methyl-1-butene, cis-1,2-dichloroethene to cis-1,2-dichloroepoxyethane, and trans-1,2-dichloroethene to trans-1,2-dichloroepoxyethane. Isoprene-grown cells also degraded cis-1,2-dichloroepoxyethane and trans-1,2-dichloroepoxyethane. All organic chlorine was liberated as chloride during degradation of cis-1,2-dichloroepoxyethane. A glutathione (GSH)-dependent activity towards 3,4-epoxy-3-methyl-1-butene, epoxypropane, cis-1,2-dichloroepoxyethane, and trans-1,2-dichloroepoxyethane was detected in cell extracts of cultures grown on isoprene and 3,4-epoxy-3-methyl-1-butene. The epoxide-degrading activity of strain AD45 was irreversibly lost upon incubation of cells with 1,2-epoxyhexane. A conjugate of GSH and 1,2-epoxyhexane was detected in cell extracts of cells exposed to 1,2-epoxyhexane, indicating that GSH is the physiological cofactor of the epoxide-transforming activity. The results indicate that a GSH S-transferase is involved in the metabolism of isoprene and that the enzyme can detoxify reactive epoxides produced by monooxygenation of chlorinated ethenes. PMID:9687433

  9. Electron collisions with methyl-substituted ethylenes: Cross section measurements and calculations for 2-methyl–2-butene and 2,3-dimethyl–2-butene

    SciTech Connect

    Szmytkowski, Czesław Stefanowska, Sylwia; Zawadzki, Mateusz; Ptasińska-Denga, Elżbieta; Możejko, Paweł

    2015-08-14

    We report electron-scattering cross sections determined for 2-methyl–2-butene [(H{sub 3}C)HC = C(CH{sub 3}){sub 2}] and 2,3-dimethyl–2-butene [(H{sub 3}C){sub 2}C = C(CH{sub 3}){sub 2}] molecules. Absolute grand-total cross sections (TCSs) were measured for incident electron energies in the 0.5–300 eV range, using a linear electron-transmission technique. The experimental TCS energy dependences for the both targets appear to be very similar with respect to the shape. In each TCS curve, three features are discernible: the resonant-like structure located around 2.6–2.7 eV, the broad distinct enhancement peaking near 8.5 eV, and a weak hump in the vicinity of 24 eV. Theoretical integral elastic (ECS) and ionization (ICS) cross sections were computed up to 3 keV by means of the additivity rule (AR) approximation and the binary-encounter-Bethe method, respectively. Their sums, (ECS+ICS), are in a reasonable agreement with the respective measured TCSs. To examine the effect of methylation of hydrogen sides in the ethylene [H{sub 2}C = CH{sub 2}] molecule on the TCS, we compared the TCS energy curves for the sequence of methylated ethylenes: propene [H{sub 2}C = CH(CH{sub 3})], 2-methylpropene [H{sub 2}C = C(CH{sub 3}){sub 2}], 2-methyl–2-butene [(H{sub 3}C)HC = C(CH{sub 3}){sub 2}], and 2,3-dimethyl–2-butene [(H{sub 3}C){sub 2}C = C(CH{sub 3}){sub 2}], measured in the same laboratory. Moreover, the isomeric effect is also discussed for the C{sub 5}H{sub 10} and C{sub 6}H{sub 12} compounds.

  10. Ice core records of monoterpene- and isoprene-SOA tracers from Aurora Peak in Alaska since 1660s: Implication for climate change variability in the North Pacific Rim

    NASA Astrophysics Data System (ADS)

    Pokhrel, Ambarish; Kawamura, Kimitaka; Ono, Kaori; Seki, Osamu; Fu, Pingqing; Matoba, Sumio; Shiraiwa, Takayuki

    2016-04-01

    Monoterpene and isoprene secondary organic aerosol (SOA) tracers are reported for the first time in an Alaskan ice core to better understand the biological source strength before and after the industrial revolution in the Northern Hemisphere. We found significantly high concentrations of monoterpene- and isoprene-SOA tracers (e.g., pinic, pinonic, and 2-methylglyceric acids, 2-methylthreitol and 2-methylerythritol) in the ice core, which show historical trends with good correlation to each other since 1660s. They show positive correlations with sugar compounds (e.g., mannitol, fructose, glucose, inositol and sucrose), and anti-correlations with α-dicarbonyls (glyoxal and methylglyoxal) and fatty acids (e.g., C18:1) in the same ice core. These results suggest similar sources and transport pathways for monoterpene- and isoprene-SOA tracers. In addition, we found that concentrations of C5-alkene triols (e.g., 3-methyl-2,3,4-trihydroxy-1-butene, cis-2-methyl 1,3,4-trihydroxy-1-butene and trans-2-methyl-1,3,4-trihydroxy-1-butene) in the ice core have increased after the Great Pacific Climate Shift (late 1970s). They show positive correlations with α-dicarbonyls and fatty acids (e.g., C18:1) in the ice core, suggesting that enhanced oceanic emissions of biogenic organic compounds through the marine boundary layer are recorded in the ice core from Alaska. Photochemical oxidation process for these monoterpene- and isoprene-/sesquiterpene-SOA tracers are suggested to be linked with the periodicity of multi-decadal climate oscillations and retreat of sea ice in the Northern Hemisphere.

  11. Development of a pulsed uniform supersonic gas expansion system based on an aerodynamic chopper for gas phase reaction kinetic studies at ultra-low temperatures.

    PubMed

    Jiménez, E; Ballesteros, B; Canosa, A; Townsend, T M; Maigler, F J; Napal, V; Rowe, B R; Albaladejo, J

    2015-04-01

    A detailed description of a new pulsed supersonic uniform gas expansion system is presented together with the experimental validation of the setup by applying the CRESU (French acronym for Cinétique de Réaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in a Uniform Supersonic Flow) technique to the gas-phase reaction of OH radicals with 1-butene at ca. 23 K and 0.63 millibars of helium (carrier gas). The carrier gas flow, containing negligible mixing ratios of OH-precursor and 1-butene, is expanded from a high pressure reservoir (337 millibars) to a low pressure region (0.63 millibars) through a convergent-divergent nozzle (Laval type). The novelty of this experimental setup is that the uniform supersonic flow is pulsed by means of a Teflon-coated aerodynamic chopper provided with two symmetrical apertures. Under these operational conditions, the designed Laval nozzle achieves a temperature of (22.4 ± 1.4) K in the gas jet. The spatial characterization of the temperature and the total gas density within the pulsed uniform supersonic flow has also been performed by both aerodynamical and spectroscopic methods. The gas consumption with this technique is considerably reduced with respect to a continuous CRESU system. The kinetics of the OH+1-butene reaction was investigated by the pulsed laser photolysis/laser induced fluorescence technique. The rotation speed of the disk is temporally synchronized with the exit of the photolysis and the probe lasers. The rate coefficient (k(OH)) for the reaction under investigation was then obtained and compared with the only available data at this temperature.

  12. Difference-NMR techniques for selection of components on the basis of relaxation times

    NASA Astrophysics Data System (ADS)

    Harris, Douglas J.; de Azevedo, Eduardo R.; Bonagamba, Tito J.

    2003-05-01

    This work describes a numerical methodology to obtain more efficient relaxation filters to selectively retain or remove components based on relaxation times. The procedure uses linear combinations of spectra with various recycle or filter delays to obtain components that are both quantitative and pure. Modulation profiles are calculated assuming exponential relaxation behavior. The method is general and can be applied to a wide range of solution or solid-state NMR experiments including direct-polarization (DP), or filtered cross-polarization (CP) spectra. 13C NMR experiments on isotactic poly(1-butene) and dimethyl sulfone showed the utility of the technique for selectively suppressing peaks.

  13. Abscission: The Role of Ethylene, Ethylene Analogues, Carbon Dioxide, and Oxygen

    PubMed Central

    Abeles, F. B.; Gahagan, H. E.

    1968-01-01

    Ethylene was the most effective abscission accelerant examined, with decreasing activity shown by propene, carbon monoxide, acetylene, vinyl fluoride, 1-butene, and 1,3-butadiene. Carbon dioxide inhibited abscission, but its effect was overcome by ethylene. Oxygen was required for abscission as an electron acceptor for respiration and not as a potentiator or activator of the ethylene attachment site. The molecular requirements for abscission were similar to those shown by other workers for other biological processes under the influence of ethylene. PMID:16656908

  14. Preparation and characterization of active niobium, tantalum, and tungsten metathesis catalysts

    SciTech Connect

    Schrock, R.; Rocklage, S.; Wengrovius, J.; Rupprecht, G.; Fellmann, J.

    1980-03-01

    Complexes of the types M(CHCR/sub 3/)L/sub 2/X/sub 3/, M(CHCR/sub 3/)(OCR/sub 3/)/sub 2/LX, and WO(CHCR/sub 3/)L/sub 2/Cl/sub 2/, where M is Nb or Ta, R is methyl, L is a tertiary phosphine, and X is Cl or Br, showed good activities in metathesis of terminal olefins, including ethylene, propylene, styrene, 1-butene, and cis-2-pentene, at 25/sup 0/C in the presence of traces of AlCl/sub 3/.

  15. 40 CFR Appendix Xvii to Part 86 - Procedure for Determining Vehicle Emission Control Technology Category/Fuel Reactivity Adjustment...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... percent Total Aromatics 32 ±3.0 Multi-substituted alkyl aromatics 21 ±3.0 Olefins 12 ±3.0 Saturates...-04-8 trans-2-pentene 8.80 00558-37-2 3,3-dimethyl-1-butene 4.42 00627-20-3 cis-2-pentene 8.80 00689... 1.32 07385-78-6 3,4-dimethyl-1-pentene 3.48 00693-89-0 1-methylcyclopentene 7.66 00071-43-2...

  16. 40 CFR Appendix Xvii to Part 86 - Procedure for Determining Vehicle Emission Control Technology Category/Fuel Reactivity Adjustment...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... percent Total Aromatics 32 ±3.0 Multi-substituted alkyl aromatics 21 ±3.0 Olefins 12 ±3.0 Saturates...-04-8 trans-2-pentene 8.80 00558-37-2 3,3-dimethyl-1-butene 4.42 00627-20-3 cis-2-pentene 8.80 00689... 1.32 07385-78-6 3,4-dimethyl-1-pentene 3.48 00693-89-0 1-methylcyclopentene 7.66 00071-43-2...

  17. 40 CFR Appendix Xvii to Part 86 - Procedure for Determining Vehicle Emission Control Technology Category/Fuel Reactivity Adjustment...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... percent Total Aromatics 32 ±3.0 Multi-substituted alkyl aromatics 21 ±3.0 Olefins 12 ±3.0 Saturates...-04-8 trans-2-pentene 8.80 00558-37-2 3,3-dimethyl-1-butene 4.42 00627-20-3 cis-2-pentene 8.80 00689... 1.32 07385-78-6 3,4-dimethyl-1-pentene 3.48 00693-89-0 1-methylcyclopentene 7.66 00071-43-2...

  18. 40 CFR Appendix Xvii to Part 86 - Procedure for Determining Vehicle Emission Control Technology Category/Fuel Reactivity Adjustment...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... percent Total Aromatics 32 ±3.0 Multi-substituted alkyl aromatics 21 ±3.0 Olefins 12 ±3.0 Saturates...-04-8 trans-2-pentene 8.80 00558-37-2 3,3-dimethyl-1-butene 4.42 00627-20-3 cis-2-pentene 8.80 00689... 1.32 07385-78-6 3,4-dimethyl-1-pentene 3.48 00693-89-0 1-methylcyclopentene 7.66 00071-43-2...

  19. XAFS Study of the Photo-Active Site of Mo/MCM-41

    NASA Astrophysics Data System (ADS)

    Miyamoto, Daisuke; Ichikuni, Nobuyuki; Shimazu, Shogo

    2007-02-01

    An Mo/MCM-41 catalyst was prepared and used for study of propene and 1-butene photo-metathesis reactions. XAFS analysis revealed that hydrogen reduction leads to a decreased role for the Mo=O site. The Mo-O site plays an important role for the olefin photo-metathesis reaction on the H2 reduced Mo/MCM-41. From EXAFS analysis, the active site of photo-metathesis reaction is the Mo=O part for oxidized Mo/MCM-41, whereas it is the Mo-O site for reduced Mo/MCM-41.

  20. Density Fluctuations in Crystallizing Polymers: Fact or Fiction?

    NASA Astrophysics Data System (ADS)

    Baert, Jimmy; Van Puyvelde, Peter

    2008-07-01

    The fact that, in polymer crystallization, nucleation might be accompanied by large scale density fluctuations has been investigated for the flow-induced crystallization of isotactic poly-1-butene (PB-1). Small Angle Light Scattering (SALS) was applied to measure density and orientation fluctuations, whereas complementary results were obtained from optical microscopy. The observations seem to indicate that the detected density fluctuations result from the presence of weakly anisotropic structures, rather than being an indication of densification before the onset of crystallization. In addition, the present work provides a critical review of polymer crystallization studies using SALS.

  1. How Do Orientation Fluctuations Evolve to Crystals?

    NASA Astrophysics Data System (ADS)

    Xiao, Zhicheng; Ilavsky, Jan; Long, Gabrielle G.; Akpalu, Yvonne A.

    Light and synchrotron X-ray scattering are used to probe structure formation during isothermal crystallization of an ethylene-1-hexene copolymer (EH064, M w = 70,000 g/mol, ρ = 0.900 g/cm3, M w /M n ~ 2, 6.4 mole percent hexene) andan ethylene-1-butene copolymer (EB059, M w = 70,000 g/mol, ρ = 0.905 g/cm3, M w /M n ~ 2, 5.9 mole percent butene).

  2. Tungsten imido catalysts for selective ethylene dimerisation.

    PubMed

    Wright, Christopher M R; Turner, Zoë R; Buffet, Jean-Charles; O'Hare, Dermot

    2016-02-14

    A tungsten imido complex W(NDipp)Me3Cl (Dipp = 2,6-(i)Pr-C6H3) is active for the selective dimerisation of ethylene to yield 1-butene under mild conditions. Immobilisation and activation of W(NDipp)Cl4(THF) on layered double hydroxides, silica or polymethylaluminoxane yields active solid state catalysts for the selective dimerisation of ethylene. The polymethylaluminoxane-based catalyst displays a turnover frequency (4.0 molC2H4 molW(-1) h(-1)) almost 7 times that of the homogeneous catalyst.

  3. Study of the Thermodynamics (Thermal and Cl Catalyzed) and Kinetics of the Cis and Trans Isomerizations of CF3CF═CHF, CF3CH═CHCF3, and CH3CH═CHCH3 in 100-950 Torr of N2 Diluent at 296-875 K: Effect of F and CF3 Substitution on the Isomerization Process Including the Fluorine "Cis Effect".

    PubMed

    Kaiser, E W; Pierce, David S

    2015-08-27

    The equilibrium constants for the Z to E isomerizations of CF3CF═CHF (K1) and CF3CH═CHCF3 (K2) have been measured using GC/FID analysis over the temperature ranges 360–850 and 297–850 K, respectively. At lower temperature, K was determined using Cl atom catalysis. At higher temperature, K was measured without a catalyst. The temperature-dependent expressions are K1 (Z to E) = 1.45(±0.15)e(–[2845(±100)/RT]) and K2 (Z to E) = 1.9(±0.22)e(+[4330(±120)/RT]) (where the gas constant R ≡ 1.986 cal mol(–1) K(–1)). For isomerization 1, the Z (fluorine cis) isomer is 2.85 kcal mol(–1) lower in energy than the E (fluorine trans) isomer, providing another example of the fluorine "cis effect" in olefins. For isomerization 2, the E(trans) isomer is 4.3 kcal mol(–1) lower in energy than the corresponding Z(cis) isomer as is normal for olefins. The isomerization rate constant in a single direction was also measured for each fluorinated compound: k–1(E to Z) = 10(13.87±0.24)e(–59530(±887)/RT) s(–1); and k2(Z to E) = 10(13.89±0.23)e(–58845(±675)/RT) s(–1). To verify the experimental method, cis to trans (k3) and trans to cis (k–3) isomerization rate constants were also measured for cis- and trans-2-butene for comparison to several previous studies. The rate constants determined herein are k3 (cis to trans) = 10(13.95±0.23)e(–63245(±815)/RT) s(–1); and k–3 (trans to cis) = 10(14.32±0.28)e(–64993(±1132)/RT) s(–1). k3 agrees well with four previous measurements and represents the best available rate constant for 2-butene. All errors quoted here are 2σ. The typical total pressure for these experiments was 760 ± 100 Torr. Limited experiments performed at 100 Torr showed no pressure dependence for any of the compounds above 100 Torr. Thus, all isomerization rate constants represent high-pressure limits. The rates of the addition reactions of Cl to the double bonds of CF3CF═CHF (k4) and CF3CH═CHCF3 (k7) (used in Cl catalysis) were

  4. Study of the Thermodynamics (Thermal and Cl Catalyzed) and Kinetics of the Cis and Trans Isomerizations of CF3CF═CHF, CF3CH═CHCF3, and CH3CH═CHCH3 in 100-950 Torr of N2 Diluent at 296-875 K: Effect of F and CF3 Substitution on the Isomerization Process Including the Fluorine "Cis Effect".

    PubMed

    Kaiser, E W; Pierce, David S

    2015-08-27

    The equilibrium constants for the Z to E isomerizations of CF3CF═CHF (K1) and CF3CH═CHCF3 (K2) have been measured using GC/FID analysis over the temperature ranges 360–850 and 297–850 K, respectively. At lower temperature, K was determined using Cl atom catalysis. At higher temperature, K was measured without a catalyst. The temperature-dependent expressions are K1 (Z to E) = 1.45(±0.15)e(–[2845(±100)/RT]) and K2 (Z to E) = 1.9(±0.22)e(+[4330(±120)/RT]) (where the gas constant R ≡ 1.986 cal mol(–1) K(–1)). For isomerization 1, the Z (fluorine cis) isomer is 2.85 kcal mol(–1) lower in energy than the E (fluorine trans) isomer, providing another example of the fluorine "cis effect" in olefins. For isomerization 2, the E(trans) isomer is 4.3 kcal mol(–1) lower in energy than the corresponding Z(cis) isomer as is normal for olefins. The isomerization rate constant in a single direction was also measured for each fluorinated compound: k–1(E to Z) = 10(13.87±0.24)e(–59530(±887)/RT) s(–1); and k2(Z to E) = 10(13.89±0.23)e(–58845(±675)/RT) s(–1). To verify the experimental method, cis to trans (k3) and trans to cis (k–3) isomerization rate constants were also measured for cis- and trans-2-butene for comparison to several previous studies. The rate constants determined herein are k3 (cis to trans) = 10(13.95±0.23)e(–63245(±815)/RT) s(–1); and k–3 (trans to cis) = 10(14.32±0.28)e(–64993(±1132)/RT) s(–1). k3 agrees well with four previous measurements and represents the best available rate constant for 2-butene. All errors quoted here are 2σ. The typical total pressure for these experiments was 760 ± 100 Torr. Limited experiments performed at 100 Torr showed no pressure dependence for any of the compounds above 100 Torr. Thus, all isomerization rate constants represent high-pressure limits. The rates of the addition reactions of Cl to the double bonds of CF3CF═CHF (k4) and CF3CH═CHCF3 (k7) (used in Cl catalysis) were

  5. A simplified chemistry module for atmospheric transport and dispersion models: Proof-of-concept using SCIPUFF

    NASA Astrophysics Data System (ADS)

    Burns, Douglas S.; Rottmann, Shawn D.; Plitz, Angela B. L.; Wiseman, Floyd L.; Moore, William; Chynwat, Veeradej

    2012-09-01

    An atmospheric chemistry module was developed to predict the fate of environmentally hazardous compounds discharged into the atmosphere. The computationally efficient model captures the diurnal variation within the environment and in the degradation rates of the released compounds, follows the formation of toxic degradation products, runs rapidly, and in principle can be integrated with any atmospheric transport and dispersion model. To accomplish this, a detailed atmospheric chemistry mechanism for a target toxic industrial compound (TIC) was reduced to a simple empirical effective degradation rate term (keff). Empirically derived decay functions for keff were developed as a function of important meteorological parameters such as solar flux, temperature, humidity, and cloud cover for various land uses and locations by statistically analyzing data generated from a detailed chemistry mechanism run over a wide range of (typical) atmospheric conditions. 1-Butene and two degradation products (propanal and nitrooxybutanone) were used as representative chemicals in the algorithm development for this proof-of-concept demonstration of the capability of the model. The quality of the developed model was evaluated via comparison with experimental chamber data and the results (decay rates) compared favorably for ethene, propene, and 1-butene (within a factor of two 75% or more of the time).

  6. Spectroscopic Identification of Y(C4H6) Isomers Formed by Yttrium-Mediated C-H Bond Activation of Butenes

    NASA Astrophysics Data System (ADS)

    Kim, Jong Hyun; Yang, Dong-Sheng

    2016-06-01

    Y(C4H6) was observed from the reactions of laser-vaporized Y atom with 1-butene (CH2=CHCH2CH3) and iso-butene (CH2=C(CH3)2) in a pulsed molecular beam source, and its structural isomers were investigated with mass-analyzed threshold ionization spectroscopy combined with electronic structure calculations and spectral simulations. Y(C4H6) was identified as a five-membered metallacycle [Y(CH2-CH=CH-CH2)] from the Y + 1-butene reaction and a tetrahedral structure [YC(CH2)3] from the Y + iso-butene reaction. The metallacycle has a Cs structure with Y binding to the two terminal carbon atoms, whereas the tetrahedron has C3v symmetry with Y binding to the tertiary carbon atom of trimethylenemethane. Both isomers have a doublet ground state with the highest molecular orbital being largely a Y 5s character. Ionization removes the metal based electron, and the resultant singlet ion has a similar structure to the neutral complex. However, the adiabatic ionization energy [46309(5) cm-1] of the tetrahedron is considerably higher than that [43473(5) cm-1] of the cyclic structure.

  7. 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.

  8. Lamellar Morphology of Metallocene Random Propylene Copolymers studied by Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Hosier, Ian; Alamo, Rufina

    2003-03-01

    Four sets of propylene based random copolymers with co-units of ethylene, 1-butene, 1-hexene and 1-octene, in a wide range of co-monomer contents up to 10 mol percent (including co-unit and other defects), were studied after both rapid and isothermal crystallization from the melt. Etched film surfaces were imaged so as to minimize catalyst and co-catalyst residues. As the concentration of the gamma polymorph increases with increasing comonomer content or increasing crystallization temperature, the thickness and lateral extension of the observed lamellae decreases rapidly. Spherulites are formed in copolymers with non-crystallizable units (1-hexene and 1-octene) up to 3 mol percent total defect content, and were observed right up to 7 mol percent total defect content in those with partially crystallizable co-monomers (ethylene and 1-butene). However, lamellae were observed in the surfaces of all copolymers analyzed, even in the most defective ones, highlighting the importance of the gamma polymorph in propagating lamellar crystallites in polypropylenes with a high concentration of defects. The morphology of equivalent microtomed bulk specimens will be comparatively discussed.

  9. Vanadium-phosphorus-oxygen industrial catalysts for C/sub 4/ hydrocarbon selective oxidation to maleic anhydride

    SciTech Connect

    Wenig, R.W.

    1987-06-01

    The selective oxidation of n-butane to maleic anhydride by vanadium-phosphorus-oxygen (V-P-O) industrial catalysts varying in P-to-V ratio has been studied in a fixed bed integral reactor system. Catalyst characterization studies including x-ray diffraction, laser Raman spectroscopy, infrared spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy, x-ray energy dispersive spectroscopy, and BET surface area measurements were used. A strong effect of P-to-V synthesis ratio on catalyst structure, catalyst morphology, vanadium oxidation state, and reactivity in n-butane selective oxidation was observed. A slight ''excess'' of catalyst phosphorus (P/V = 1.1 catalyst) was found to stabilize an active and selective (VO)/sub 2/P/sub 2/O/sub 7/ phase. The mechanism of n-butane selective oxidation to maleic anhydride was studied by in situ infrared spectroscopy using n-butane, 1-butene, 1,3-butadiene, crotyl alcohol, maleic acid, crotonic acid, and maleic anhydride feeds. During paraffin selective oxidation, highly reactive olefin species and maleic acid were observed on the surfaces of V-P-O catalysts. Further evidence in support of conjugated or possibly strained olefin and maleic acid reaction intermediates in n-butane and 1-butene partial oxidation to maleic anhydride was gathered.

  10. Cathodic hydrogenation of unsaturated hydrocarbons in a polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Salazar-Villalpando, Maria Dolores

    2000-10-01

    With the cathodic hydrogenation and isomerization of unsaturated hydrocarbons in a Polymer Electrolyte Fuel Cell, we wanted to investigate an alternative heterogeneous cathodic process to perform acid catalyzed reactions. In this process, the catalytic activity and selectivity of the catalyst/solid electrolyte interface could be tuned by controlling the proton spillover via an electrical potential. Acidic metal supports, such as zeolites or clays, function through their ability to release and accept protons. Similarly, the use of proton solid electrolyte membranes, such as Nafion allows the electromigration of protons from the fuel cell anode to the corresponding cathode. Of various fuel cell systems considered, the polymer electrolyte fuel cells using Nafion as the solid electrolyte seemed to be the most suitable system because the acidic properties of the Nafion. The products from the hydrogenation and isomerization reactions of 2,3Dimethyl-1-butene (2,3DM1BE) were 2,3Dimethylbutane (2,3DMBA) and 2,3Dimethyl-2-Butene (2,3DM2BE) respectively. The Non-Faradaic Modification of Catalytic activity (NEMCA) or the electrochemical activation of the catalyst/Nafion interface enhanced the catalytic rate of the isomerization reaction. The isomerization of 3,3Dimethyl-1-butene formed 2,3Dimethylbutane as the product from the skeleton rearrangement reaction. These reactions represent examples of the use of fuel cells in the Cogeneration of chemical compounds and electrical power.

  11. Synthesis of hydride and alkyl compounds containing the Cp*Os([eta][sup 3]-allyl) fragment. Crystal structures of Cp*Os([eta][sup 3]-C[sub 8]H[sub 13])Br[sub 2] and [Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Me(H[sub 2]O)][BF[sub 4

    SciTech Connect

    Mui, H.D.; Brumaghim, J.L.; Gross, C.L.; Girolami, G.S. . School of Chemical Sciences)

    1999-08-16

    Treatment of Cp*[sub 2]Os[sub 2]Br[sub 4] with 3-bromo-2-methylpropene or 1,3-cyclooctadiene affords the 2-methylpropenyl and cyclooctenyl products Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Br[sub 2] and Cp*Os([eta][sup 3]-C[sub 8]H[sub 13])Br[sub 2], respectively. The monoalkyl complexes Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])MeBr and Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])(CH[sub 2]SiMe[sub 3])-Br can be generated by treating Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Br[sub 2] with MgMe[sub 2] or LiCH[sub 2]SiMe[sub 3]. The dimethyl complex Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Me[sub 2] can be synthesized from Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Br[sub 2] by addition of methyllithium. In contrast, addition of ethyllithium to Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Br[sub 2] yields the ethylene complex Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])([eta][sup 2]-C[sub 2]H[sub 4]) and a small amount of Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])H[sub 2]. The latter dihydride can be synthesized in better yield by treating Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Br[sub 2] with LiAlH[sub 4]. When the dimethyl complex Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Me[sub 2] is protonated with HBF[sub 4] in the presence of H[sub 2]O the aqua complex [Cp*Os([eta][sup 3]-C[sub 4]H[sub 7])Me(H[sub 2]O)][BF[sub 4

  12. Synthesis of hydride and alkyl compounds containing the Cp*Os({eta}{sup 3}-allyl) fragment. Crystal structures of Cp*Os({eta}{sup 3}-C{sub 8}H{sub 13})Br{sub 2} and [Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Me(H{sub 2}O)][BF{sub 4}

    SciTech Connect

    Mui, H.D.; Brumaghim, J.L.; Gross, C.L.; Girolami, G.S.

    1999-08-16

    Treatment of Cp*{sub 2}Os{sub 2}Br{sub 4} with 3-bromo-2-methylpropene or 1,3-cyclooctadiene affords the 2-methylpropenyl and cyclooctenyl products Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Br{sub 2} and Cp*Os({eta}{sup 3}-C{sub 8}H{sub 13})Br{sub 2}, respectively. The monoalkyl complexes Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})MeBr and Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})(CH{sub 2}SiMe{sub 3})-Br can be generated by treating Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Br{sub 2} with MgMe{sub 2} or LiCH{sub 2}SiMe{sub 3}. The dimethyl complex Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Me{sub 2} can be synthesized from Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Br{sub 2} by addition of methyllithium. In contrast, addition of ethyllithium to Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Br{sub 2} yields the ethylene complex Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})({eta}{sup 2}-C{sub 2}H{sub 4}) and a small amount of Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})H{sub 2}. The latter dihydride can be synthesized in better yield by treating Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Br{sub 2} with LiAlH{sub 4}. When the dimethyl complex Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Me{sub 2} is protonated with HBF{sub 4} in the presence of H{sub 2}O the aqua complex [Cp*Os({eta}{sup 3}-C{sub 4}H{sub 7})Me(H{sub 2}O)][BF{sub 4}] is formed.

  13. Ice core records of monoterpene- and isoprene-SOA tracers from Aurora Peak in Alaska since 1660s: Implication for climate variability in the North Pacific Rim

    NASA Astrophysics Data System (ADS)

    Pokhrel, A.; Kawamura, K.; Seki, O.; Ono, K.; Matoba, S.; Shiraiwa, T.

    2015-12-01

    180 m long ice core (ca. 343 years old) was drilled in the saddle of the Aurora Peak of Alaska, which is located southeast of Fairbanks (63.52°N; 146.54°W, elevation: 2,825 m). Samples were directly transported to the Institute of Low Temperature Science, Hokkaido University and have been analyzed for monoterpene- and isoprene-SOA tracers using gas chromatograph (GC; HP 6890) and mass spectrometry system (GC/MS; Agilent). Ice core collected from mountain glacier has not been explored for SOA yet. We found significantly high concentrations of these tracers (e.g., pinic, pinonic, and 2-methylglyceric acids, 2-methylthreitol and 2-methylrythritol), which show historical trends with good correlation with each other since 1665-2008. They show positive correlations with sugar compounds (e.g., mannitol, glucose, fructose, inositol, and sucrose), and anti-correlations with diacids (e.g., C9), w-oxocarboxylic (wC4-wC9), a-dicarbonyls and low molecular weight fatty acids (LFAs) (e.g., C18:1). LFAs show strong correlations with MSA- and nss-SO42- in the same ice core. These results suggest source regions of SOA tracers and ice core chemistry of Alaska. Concentrations of C5-alkene triols (e.g., 3-methyl-2,3,4-trihydroxy-1-butene, cis-2-methyl 1,3,4-trihydroxy-1-butene and trans-2-methyl-1,3,4-trihydroxy-1-butene) have increased in the ice core after the Great Pacific Climate Shift (late 1970's). They show positive correlations with a-dicarbonyls and LFAs (e.g., C18:1) in the ice core, suggesting that enhanced oceanic emissions of biogenic organic compounds through the surface microlayer are recorded in the ice core. Photochemical oxidation processes for these monoterpene- and isoprene-/sesquiterpene-SOA tracers are suggested to be linked with the periodicity of multi-decadal climate oscillations (e.g., North Pacific Index) and we can look at a whole range of environmental parameters in parallel with the robust reconstructed temperature changes in the Northern Hemisphere.

  14. Synthesis of substrates for periodate-coupled assay of phospholipases C and sphingomyelinases.

    PubMed

    Larsen, Kira Løw; Andersen, Rokhsana J; Brask, Jesper

    2016-09-01

    A series of 4-nitrophenyl (pNP) and 4-methylumbelliferyl (4MU) substrate analogues of phosphatidyl choline (PC) and phosphatidic acid (PA) were synthesized from 4-bromo-1-butene by ether formation, olefin epoxidation and ring opening with the phosphate head group. The pNP PC analogue, 4-(4-nitrophenoxy)-2-hydroxy-butyl-1-phosphoryl choline (1) was evaluated in assays of fungal sphingomyelinases, also displaying phospholipase C activity. Reactions were terminated with a periodate-containing stop solution, leading to liberation of pNP, quantified spectrophotometrically in an end-point measurement. A kinetic evaluation of sphingomyelinases from Kionochaeta sp. and Penicillium emersonii showed relatively high KM and low kcat values for this substrate, limiting its practical applicability in assays with low sphingomyelinase concentrations. PMID:27444331

  15. Polymer Optical Constants from Long-Range Corrected DFT Calculations.

    PubMed

    Maekawa, Shintaro; Moorthi, Krzysztof

    2016-03-10

    A methodology to calculate refractive indices of plastics based on the Lorentz-Lorenz equation has been proposed. The polarizability of the nonconjugated polymer repeat units is predicted using the long-range corrected functionals. The end effect corrections in repeat unit models are essential to achieve accuracy similar to that observed for molecular liquids (ca. 1% in mean absolute deviation). The functionals with 100% Hartree-Fock (HF) exchange in the long-range limit perform best for aromatic and other hydrogen-deficient compounds; the Coulomb-attenuated hybrid exchange-correlation functional (CAM-B3LYP) performs very well for hydrogen-rich (usually, fully saturated) compounds. Exceptionally good agreement is observed for the sets of wavelength-dependent refractive index data for polystyrene, poly(methyl methacrylate), and for poly(perfluoro-4-vinyloxy-1-butene) (CYTOP), for which the root-mean-square deviations are 0.004, 0.002, and 0.004, respectively.

  16. Synthesis of an un-supported, high-flow ZSM-22 zeolite membrane

    DOEpatents

    Thoma, Steven G.; Nenoff, Tina M.

    2006-10-10

    Novel methods for synthesizing wholly un-supported, high-flow catalytic membranes consisting of 100% crystalline ZSM-22 crystals with no binder phase, having sufficient porosity to allow high Weight Hourly Space Velocities of feedstock to pass through without generating back pressure. The ZSM-22 membranes perform favorably to existing bulk ZSM-22 catalysts (e.g., via 1-butene conversion and selectivity). The method of membrane synthesis, based on Vapor Phase Transport, allows free-standing, binder-less membranes to be fabricated in varied geometries and sizes so that membranes can be tailor-made for particular geometries applications. The ZSM-22 precursor gel may be consolidated into a semi-cohesive body prior to vapor phase crystallization, for example, by uniaxial pressing. These crystalline membranes may be modified by ion exchange, pore ion exchange, framework exchange, synthesis modification techniques to incorporate other elements into the framework, such as K, H, Mg, Zn, V, Ga, and Pt.

  17. Hydrogenation of carbon monoxide over ruthenium: detection of surface species by reactive scavenging

    SciTech Connect

    Baker, J.A.; Bell, A.T.

    1982-11-01

    Hydrocarbon species produced on the surface of a Ru/SiO/sub 2/ catalyst during CO hydrogenation have been detected by analysis of the products formed when these species react with cyclohexene, benzene, cyclopentene, or cis-2-butene, added in low concentration to the synthesis gas mixture. The presence of adsorbed methylene groups is strongly supported by the formation of norcarane and 1,2-dimethylcyclopropane from cyclohexene and cis-2-butene, respectively, and by the formation of ethylcyclopropane from 1-butene produced by the isomerization of cis-2-butene. Methyl and higher-molecular-weight alkyl groups are detected through the observation of alkyl derivatives of cyclohexene and benzene when cyclohexene or benzene is used as the scavenger. The addition of a scavenger to the synthesis gas is found to decrease the formation of higher-molecular-weight hydrocarbons produced by CO hydrogenation. This suggests that the species removed by the scavenger are intermediates in the process of hydrocarbon chain growth.

  18. Gaseous Species Measurements of Alternative Jet Fuels in Sooting Laminar Coflow Diffusion Flames

    NASA Astrophysics Data System (ADS)

    Zabeti, Parham

    The gaseous species concentration of Jet A-1, GTL, CTL and a blend of 80 vol.% GTL and 20 vol.% hexanol jet fuels in laminar coflow diffusion flames have been measured and studied. These species are carbon monoxide, carbon dioxide, oxygen, methane, ethane, ethylene, propylene, and acetylene. Benzene and propyne concentrations were also detected in CTL flames. 1-Butene has been quantified for the blend of GTL and hexanol flame. The detailed experimental setup has been described and results from different flames are compared. The CO is produced in a same amount in all the flames. The CTL flame had the largest and GTL/hexanol flame had lowest CO2 concentrations. The results indicate that GTL and GTL hexanol blend flames produce similar concentrations for all the measured hydrocarbon species and have the highest concentration among all the jet fuels. The experimental results from Jet A-1 fuel are also compared with numerical studies by Saffaripour et al .

  19. Reaction mechanism studies of unsaturated molecules using photofragment translational spectroscopy

    SciTech Connect

    Longfellow, C.A. |

    1996-05-01

    A number of molecules have been studied using the technique of photofragment translational spectroscopy. In Chapter One a brief introduction to the experimental technique is given. In Chapter Two the infrared multiphoton dissociation (IRMPD) of acetic acid is discussed. Carbon dioxide and methane were observed for the first time as products from dissociation under collisionless conditions. Chapter Three relates an IRMPD experiment of hexafluoropropene. The predominant channel produces CFCF{sub 3} or C{sub 2}F{sub 4} and CF{sub 2}, with the heavier species undergoing further dissociation to two CF{sub 2} fragments. In Chapter Four the ultraviolet (UV) dissociation of hexafluoropropene is investigated. Chapter Five explores the IRMPD of octafluoro-1-butene and octafluoro-2-butene.

  20. Fuel structure and pressure effects on the formation of soot particles in diffusion flames. Annual technical report, 15 January 1988-15 January 1989

    SciTech Connect

    Santoro, R.J.

    1989-02-15

    Studies emphasizing the effects of fuel molecular structure on soot formation processes in laminar-diffusion flames were investigated. Particular attention was given to the particle inception and surface growth processes for a series of fuels. Studies of butane, 1-butene, and 1,3 butadiene have revealed that fuel structure strongly affects the soot-particle-inception process. However, subsequent surface-growth processes are largely determined by the available surface area. Thus, the surface growth process is independent of the fuel molecular structure following the initial particle-inception stage. Studies of the particle-inception region indicate that increased soot formation is strongly correlated with visible-fluorescence measurements attributed to large polynuclear aromatic hydrocarbon species in the flame.

  1. Partial oxidation of {alpha}-olefins over iron antimony oxide - influence of carbon number

    SciTech Connect

    Steen, E. van; Schnobel, M.; O`Connor, C.T.

    1996-10-01

    Iron antimony oxide is a well known catalyst for the partial oxidation of propane and 1-butene. Kinetic studies of the partial oxidation of {alpha}-olefins (C{sub 2}-C{sub 9}) revealed that the activity showed a maximum at C{sub 4}. The main products of the partial oxidation of {alpha}-olefins (larger than C{sub 2}) are the conjugated alkenal (acrolein) and dienes. The selectivity to these desired products decreases with increasing chain length probably caused by both the decrease in number of allylic hydrogen atoms and the shielding of them. Ethene could only be oxidized at relatively high temperatures (over 450{degrees}C) and the only observed products were CO and CO{sub 2} indicating the need for the presence of allylic hydrogen for low temperature selective partial oxidation. Increasing the carbon number increases the yield of CO and CO{sub 2} due to shielding of the allylic hydrogen.

  2. Catalytic conversion of cellulose to liquid hydrocarbon fuels by progressive removal of oxygen to facilitate separation processes and achieve high selectivities

    DOEpatents

    Dumesic, James A [Verona, WI; Ruiz, Juan Carlos Serrano [Madison, WI; West, Ryan M [Madison, WI

    2014-01-07

    Described is a method to make liquid chemicals. The method includes deconstructing cellulose to yield a product mixture comprising levulinic acid and formic acid, converting the levulinic acid to .gamma.-valerolactone, and converting the .gamma.-valerolactone to pentanoic acid. Alternatively, the .gamma.-valerolactone can be conveted to a mixture of n-butenes. The pentanoic acid can be decarboxylated yield 1-butene or ketonized to yield 5-nonanone. The 5-nonanone can be hydrodeoxygenated to yield nonane, or 5-nonanone can be reduced to yield 5-nonanol. The 5-nonanol can be dehydrated to yield nonene, which can be dimerized to yield a mixture of C.sub.9 and C.sub.18 olefins, which can be hydrogenated to yield a mixture of alkanes.

  3. Catalytic conversion of cellulose to liquid hydrocarbon fuels by progressive removal of oxygen to facilitate separation processes and achieve high selectivities

    DOEpatents

    Dumesic, James A.; Ruiz, Juan Carlos Serrano; West, Ryan M.

    2015-06-30

    Described is a method to make liquid chemicals. The method includes deconstructing cellulose to yield a product mixture comprising levulinic acid and formic acid, converting the levulinic acid to .gamma.-valerolactone, and converting the .gamma.-valerolactone to pentanoic acid. Alternatively, the .gamma.-valerolactone can be converted to a mixture of n-butenes. The pentanoic acid can be decarboxylated yield 1-butene or ketonized to yield 5-nonanone. The 5-nonanone can be hydrodeoxygenated to yield nonane, or 5-nonanone can be reduced to yield 5-nonanol. The 5-nonanol can be dehydrated to yield nonene, which can be dimerized to yield a mixture of C.sub.9 and C.sub.18 olefins, which can be hydrogenated to yield a mixture of alkanes.

  4. Reaction of diethylcalcium and diethylstrontium with alkylthiovinylacetylenes and their analogs

    SciTech Connect

    Cherkasov, L.N.; Radchenko, S.I. |

    1994-08-20

    Alkylthiovinylacetylenes (4-alkylthio-1-buten-3-ynes) do not add previously prepared Grignard reagents and dialkylmagnesiums at the terminal carbon-carbon bonds. Diethylbarium (the complex with diethylzinc) adds to alkylthiovinylacetylenes with the formation of intermediates, the protolysis of which with water gives allenyl thioethers with normal structure. The alkylseleno- and alkyltellurovinylacetylenes are cleaved by diethylbarium and by organomagnesium compounds at the carbon-heteroatom bond. There are published data on the reaction of alkylthiovinylacetylenes and their analogs with dialkylcalciums and dialkylstrontiums. In the present work the authors established that diethylcalcium and diethylstrontium (the complexes with diethylzinc) add with high regioselectivity to methylthio- and ethylthiovinylacetylenes in a ratio of 1:1 with the formation of normal allenyl thioethers with yields of 30-35% (on the alkylthiovinylacetylene) after decomposition of the organometallic adducts with water.

  5. Crosslinking and degradation of polypropylene by electron beam irradiation in the presence of trifunctional monomers

    NASA Astrophysics Data System (ADS)

    Han, Do Hung; Shin, Seung-Ho; Petrov, Serguei

    2004-02-01

    Homo-polypropylene (HPP) and random terpolymer of propylene with 2% ethylene and 1% 1-butene by weight (RTPP) can be crosslinked with relatively high gel contents even at doses less than 20 kGy, when using trimethylpropanetriacrylate (TMPTA) and triallylcyanuate (TAC) as crosslinking agents. At high doses, HPP with TMPTA degrades more compared to HPP with TAC or RTPP with TMPTA, resulting in a significant increase of the melt index. Heat of fusion of the irradiated polypropylenes (PPs) indicates that the crosslinking and degradation are likely to have little effect on the crystallinity of the PP. Larger amounts of TMPTA in HPP gave rise to more degradation than crosslinking, since excesses of monomer prohibit crosslinking through homo-polymerization.

  6. Three-Dimensional Conformation of Folded Polymers in Single Crystals

    NASA Astrophysics Data System (ADS)

    Hong, You-lee; Yuan, Shichen; Li, Zhen; Ke, Yutian; Nozaki, Koji; Miyoshi, Toshikazu

    2015-10-01

    The chain-folding mechanism and structure of semicrystalline polymers have long been controversial. Solid-state NMR was applied to determine the chain trajectory of 13C CH3 -labeled isotactic poly(1-butene) (i PB 1 ) in form III chiral single crystals blended with nonlabeled i PB 1 crystallized in dilute solutions under low supercooling. An advanced 13C - 13C double-quantum NMR technique probing the spatial proximity pattern of labeled 13C nuclei revealed that the chains adopt a three-dimensional (3D) conformation in single crystals. The determined results indicate a two-step crystallization process of (i) cluster formation via self-folding in the precrystallization stage and (ii) deposition of the nanoclusters as a building block at the growth front in single crystals.

  7. Light emission from an ambipolar semiconducting polymer field-effect transistor

    NASA Astrophysics Data System (ADS)

    Swensen, James S.; Soci, Cesare; Heeger, Alan J.

    2006-02-01

    Ambipolar light-emitting field-effect transistors are fabricated with two different metals for the top-contact source and drain electrodes; a low-work-function metal defining the channel for the source electrode and a high-work-function metal defining the channel for the drain electrode. A thin film of polypropylene-co-1-butene on SiN x is used as the gate dielectric on an n ++-Si wafer, which functioned as the substrate and the gate electrode. Transport data show ambipolar behavior. Recombination of electrons and holes results in a narrow zone of light emission within the channel. The location of the emission zone is controlled by the gate bias.

  8. A solution processable fluorene-benzothiadiazole small molecule for n-type organic field-effect transistors

    NASA Astrophysics Data System (ADS)

    Mutkins, Karyn; Gui, Ke; Aljada, Muhsen; Schwenn, Paul E.; Namdas, Ebinazar B.; Burn, Paul L.; Meredith, Paul

    2011-04-01

    We report an n-type organic semiconductor [2-({7-(9,9-di-n-propyl-9H-fluoren-2-yl}benzo[c][1,2,5]thiadiazol-4-yl)methylene]malononitrile (herein referred to as K12) for use in organic field-effect transistors (OFETs). K12 can be processed by spin-coating from solution or by vacuum deposition, organizing into highly orientated microcrystalline structures at modest (75 °C) annealing temperatures. OFETs with n-octyltrichlorosilane or hexamethyldisilazane monolayers, or poly(propylene-co-1-butene) (PPCB) modified dielectric surfaces were prepared. The mobility, ON/OFF ratio, threshold voltage, and current hysteresis were found to be dependent on the thermal history of the film and surface onto which it was deposited. The highest OFET mobility achieved was 2.4×10-3 cm2/V s, for spin-coated films with a PPCB modified silicon dioxide dielectric.

  9. Light emission from an ambipolar semiconducting polymer field-effect transistor

    NASA Astrophysics Data System (ADS)

    Swensen, James S.; Soci, Cesare; Heeger, Alan J.

    2005-12-01

    Ambipolar light-emitting field-effect transistors are fabricated with two different metals for the top-contact source and drain electrodes; a low-work-function metal defining the channel for the source electrode and a high-work-function metal defining the channel for the drain electrode. A thin film of polypropylene-co-1-butene on SiNx is used as the gate dielectric on an n++-Si wafer, which functioned as the substrate and the gate electrode. Transport data show ambipolar behavior. Recombination of electrons and holes results in a narrow zone of light emission within the channel. The location of the emission zone is controlled by the gate bias.

  10. Crystalline Morphology of Propylene 1-Octene Random Copolymers

    NASA Astrophysics Data System (ADS)

    Jeon, Keesu; Alamo, Rufina G.

    2008-03-01

    The morphology of isotactic propylene 1-octene random copolymers has been studied by AFM, DSC, WAXS, and FTIR in an octene range of 10-20 mol %. Different morphologies were observed below and above 15 mol %. The morphological components in the higher counit copolymers are not of the lamellae-type, thicker than lamellae observed below 15 mol %, connected and isotropic in their orientation. Their global morphology is developed via nucleation and growth (NG) of spherulitic aggregates. The evolution of heat of fusion with time is also sigmoidal shape, typical of NG-type crystallization mechanism. WAXS diffractograms for the higher counit copolymers are devoid of crystalline reflections, except for small and broad peaks suggesting mesomorphic-like structures, which by FTIR show small contents of the 840 cm-1, 12 and higher units regularity bands, and hence formed of short helical sequences. The PO morphology is additionally compared with copolymers with ethylene, 1-butene and 1-hexene counits at matched contents.

  11. Polarized Raman study of random copolymers of propylene with olefins

    NASA Astrophysics Data System (ADS)

    Gen, D. E.; Chernyshov, K. B.; Prokhorov, K. A.; Nikolaeva, G. Yu.; Sagitova, E. A.; Pashinin, P. P.; Kovalchuk, A. A.; Klyamkina, A. N.; Nedorezova, P. M.; Optov, V. A.; Shklyaruk, B. F.

    2010-06-01

    The polarized Raman spectroscopy is employed in the study of structural modifications in the films of isotactic polypropylene (PP) whose chain contains ethylene, 1-butene, 1-hexene, 1-octene, and 4-metyl-pentene-1, which represents an isomer of 1-hexene. It is demonstrated that the phase and conformational compositions of copolymer molecules depend on the comonomer content and the side-chain length of the second monomer. The content of the PP molecules in the helical conformation in the crystalline and amorphous phases of the copolymers monotonically decreases with increasing content of the second monomer. The decrease in the content of helical macromolecules in the crystalline phase is faster than the decrease in the amorphous phase. At a certain content of comonomers, the total content of the helical fragments decreases with increasing length of the side chain of the second monomer. The structures and Raman spectra of the copolymers of propylene with 1-hexene and 4-methyl-1-pentene are similar.

  12. Precision Polyolefin Structure: Modeling Polyethylene Containing Methyl and Ethyl Branches

    NASA Astrophysics Data System (ADS)

    Rojas, Giovanni; Wagener, Kenneth B.

    Sequenced copolymers of ethylene and diverse species have been created using acyclic diene metathesis (ADMET) polymerization, a step growth, condensation- type polymerization driven to high conversion by the removal of ethylene. ADMET permits control over branch content and branch length, which can be predetermined during the monomer synthesis, allowing sequence control in the resultant unsaturated polymer. Monomers are symmetrical α,ωdienes with a pendant functionality. Diverse functional groups are compatible with ADMET polymerization when Schrock’s or first-generation Grubb’s catalysts are used. Saturation with hydrogen after ADMET polymerization affords a polyethylene (PE) backbone bearing specific functionalities in precise places. Varying both the pendant functional group and the spacing between functionalities alters the physical and chemical properties of the polymer. Incorporation of alkyl chains into the PE backbone via ADMET leads to the study of perfect structures modeling the copolymerization of ethylene with α-olefins such as 1-propene, 1-butene, 1-hexene, and 1-octene.

  13. Structure and entanglements in short chain branched polyolefin melts

    NASA Astrophysics Data System (ADS)

    Moorthi, K.; Kamio, K.; Ramos, J.; Theodorou, D. N.

    2013-02-01

    Atomistic models of short chain branched (SCB) polyethylene melts containing up to 20-40 mol% of comonomer (1-butene, 1-hexene, 1-octene or 1-decene) have been equilibrated at 450 K using a connectivity altering Monte Carlo method, and analyzed for topological constraints using Z1 and CReTA codes. The calculated tube diameters, , of SCB melts are found to scale with the backbone weight fraction, φ, as ˜φ-0.46, close to the scaling predicted by the binary contact model, ˜φ-0.5 and in disagreement with the packing model prediction ˜φ-1.27. Similar scaling relationships are observed experimentally for polymer solutions, and reproduced by the present methods.

  14. Phase Transitions and Honeycomb Morphology in an Incompatible Blend of Enantiomeric Polylactide Block Copolymers

    NASA Astrophysics Data System (ADS)

    Sun, Lu; Ginorio, Jorge; Zhu, Lei; Rong, Lixia; Sics, Igor; Hsiao, Benjamin

    2007-03-01

    Enantiomeric PLAs, poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), are known to form stereocomplexes. In this work, by using controlled ring-opening polymerization of L- and D-lactides from monohydroxyl-terminated hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(ethylene-co-1-butene) (PEB) oligomers, respectively, well-defined PEO-b-PLLA (2k-5.4k) and PEB-b-PDLA (4.2-5.4k) block copolymers were synthesized. Quantitative stereocomplex formation was achieved by casting an equimolar mixture of incompatible PEO-b-PLLA and PEB-b-PDLA from chloroform at room temperature. Depending on different thermal histories, either lamellar or inverted cylindrical morphology was observed in the molten state. Intriguingly, novel honeycomb morphology with the minor PEB component forming the matrix was observed in the inverted cylindrical phase.

  15. In situ fourier transform infrared study of crotyl alcohol, maleic acid, crotonic acid, and maleic anhydride oxidation on a V-P-O industrial catalyst

    SciTech Connect

    Wenig, R.W.; Schrader, G.L.

    1987-10-22

    Crotyl alcohol, maleic acid, crotonic (2-butenoic) acid, and maleic anhydride were fed to an in situ infrared cell at 300/sup 0/C containing a P/V = 1.1 vanadium-phosphorous-oxide (V-P-O) catalyst used for the selective oxidation of n-butane. Crotyl alcohol was used as a mechanistic probe for the formation of reactive olefin species observed during previous n-butane and 1-butene studies. Crotonic acid, maleic acid, and maleic anhydride were fed as probes for the existence of other possible adsorbed intermediates. Olefin species and maleic acid are proposed as possible reaction intermediates in n-butane selective oxidation to maleic anhydride. The involvement of peroxide species in the oxidation of butadiene to maleic acid is also discussed.

  16. Catalytic oxidation of furan on a Mo-Ti-O catalyst. Infrared and thermodesorption study

    SciTech Connect

    Rivasseau, J.; Canesson, P.; Blanchard, M.

    1980-10-16

    The adsorption and oxidation of furan, an intermediate in the conversion of 1-butene to maleic anhydride, were studied on a catalyst containing 15.6% molybdenum as trioxide on titanium dioxide that yielded 53% maleic anhydride at 63% conversion. The results showed at furan adsorbed in two distinct modes, of which one was observed only on oxidized surface and the other was always present but depended on the degree of reduction. The adsorbed furan was oxidized in the presence of oxygen at temperatures above 235/sup 0/C, but it desorbed only above 320/sup 0/C. The Mo=O species did not seem to be important in the oxidation of furan to maleic anhydride.

  17. Shock tube study of the fuel structure effects on the chemical kinetic mechanisms responsible for soot formation, part 2

    NASA Technical Reports Server (NTRS)

    Frenklach, M.; Clary, D. W.; Ramachandra, M. K.

    1985-01-01

    Soot formation in oxidation of allene, 1,3-butadiene, vinylacetylene and chlorobenzene and in pyrolysis of ethylene, vinylacetylene, 1-butene, chlorobenzene, acetylen-hydrogen, benzene-acetylene, benzene-butadiene and chlorobenzene-acetylene argon-diluted mixtures was studied behind reflected shock waves. The results are rationalized within the framework of the conceptual models. It is shown that vinylacetylene is much less sooty than allene, which indicates that conjugation by itself is not a sufficient factor for determining the sooting tendency of a molecule. Structural reactivity in the context of the chemical kinetics is the dominant factor in soot formation. Detailed chemical kinetic modeling of soot formation in pyrolysis of acetylene is reported. The main mass growth was found to proceed through a single dominant route composed of conventional radical reactions. The practically irreversible formation reactions of the fused polycyclic aromatics and the overshoot by hydrogen atom over its equilibrium concentration are the g-driving kinetic forces for soot formation.

  18. Observation of 2-methyltetrols and related photo-oxidation products of isoprene in boreal forest aerosols from Hyytiälä, Finland

    NASA Astrophysics Data System (ADS)

    Kourtchev, I.; Ruuskanen, T.; Maenhaut, W.; Kulmala, M.; Claeys, M.

    2005-05-01

    Oxidation products of isoprene including 2-methyltetrols (2-methylthreitol and 2-methylerythritol), 2-methylglyceric acid and triol derivatives of isoprene (2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene) have been detected in boreal forest PM1 aerosols collected at Hyytiälä, southern Finland, during a 2004 summer period, at significant atmospheric concentrations (in total 51 ng m-3 in summer versus 0.46 ng m-3 in fall). On the basis of these results, it can be concluded that photo-oxidation of isoprene is an important atmospheric chemistry process that contributes to secondary organic aerosol formation during summer in this conifer forest ecosystem. In addition to isoprene oxidation products, malic acid, which can be regarded as an end-oxidation product of unsaturated fatty acids, was also detected at high concentrations during the summer period (46 ng m-3 in summer versus 5.2 ng m-3 in fall), while levoglucosan, originating from biomass burning, became relatively more important during the fall period (29 ng m-3 in fall versus 10 ng m-3 in summer). Pinic acid, a major photo-oxidation product of α-pinene in laboratory experiments, could only be detected at trace levels in the summer PM1 aerosol samples from Hyytiälä, suggesting that further oxidation of pinic acid occurs and/or that different oxidation pathways are followed. We hypothesize that photo-oxidation of isoprene may participate in the early stages of new particle formation, a phenomenon which has been well documented in the boreal forest environment.

  19. Observation of 2-methyltetrols and related photo-oxidation products of isoprene in boreal forest aerosols from Hyytiälä, Finland

    NASA Astrophysics Data System (ADS)

    Kourtchev, I.; Ruuskanen, T.; Maenhaut, W.; Kulmala, M.; Claeys, M.

    2005-10-01

    Oxidation products of isoprene including 2-methyltetrols (2-methylthreitol and 2-methylerythritol), 2-methylglyceric acid and triol derivatives of isoprene (2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene) have been detected in boreal forest PM1 aerosols collected at Hyytiälä, southern Finland, during a 2004 summer period, at significant atmospheric concentrations (in total 51 ng m-3 in summer versus 0.46 ng m-3 in fall). On the basis of these results, it can be concluded that photo-oxidation of isoprene is an important atmospheric chemistry process that contributes to secondary organic aerosol formation during summer in this conifer forest ecosystem. In addition to isoprene oxidation products, malic acid, which can be regarded as an intermediate in the oxidation of unsaturated fatty acids, was also detected at high concentrations during the summer period (46 ng m-3 in summer versus 5.2 ng m-3 in fall), while levoglucosan, originating from biomass burning, became relatively more important during the fall period (29 ng m-3 in fall versus 10 ng m-3 in summer). Pinic acid, a major photo-oxidation product of α-pinene in laboratory experiments, could only be detected at trace levels in the summer samples, suggesting that further oxidation of pinic acid occurs and/or that different oxidation pathways are followed. We hypothesize that photo-oxidation of isoprene may participate in the early stages of new particle formation, a phenomenon which has been well documented in the boreal forest environment.

  20. Inhibitory Potency of 4-Carbon Alkanes and Alkenes toward CYP2E1 Activity

    PubMed Central

    Hartman, Jessica H.; Miller, Grover P.; Boysen, Gunnar

    2016-01-01

    CYP2E1 has been implicated in the bioactivation of many small molecules into reactive metabolites which form adducts with proteins and DNA, and thus a better understanding of the molecular determinants of its selectivity are critical for accurate toxicological predictions. In this study, we determined the potency of inhibition of human CYP2E1 for various 4-carbon alkanes, alkenes and alcohols. In addition, known CYP2E1 substrates and inhibitors including 4-methylpyrazole, aniline, and dimethylnitrosamine were included to determine their relative potencies. Of the 1,3-butadiene-derived metabolites studied, 3,4-epoxy-1-butene was the strongest inhibitor with an IC50 of 110 μM compared to 1700 μM and 6600 μM for 1,2-butenediol and 1,2:3,4-diepoxybutane, respectively. Compared to known inhibitors, inhibitory potency of 3,4-epoxy-1-butene is between 4-methylpyrazole (IC50 = 1.8 μM) and dimethylnitrosamine (IC50 = 230 μM). All three butadiene metabolites inhibit CYP2E1 activity through a simple competitive mechanism. Among the 4-carbon compounds studied, the presence and location of polar groups seems to influence inhibitory potency. To further examine this notion, the investigation was extended to include structurally and chemically similar analogs, including propylene oxide and various butane alcohols. Those results demonstrated preferential recognition of CYP2E1 toward the type and location of polar and hydrophobic structural elements. Taken together, CYP2E1 metabolism may be modified in vivo by exposure to 4-carbon compounds, such as drugs, and nutritional constituents, a finding that highlights the complexity of exposure to mixtures. PMID:24561005

  1. Structure-property evolution during polymer crystallization

    NASA Astrophysics Data System (ADS)

    Arora, Deepak

    The main theme of this research is to understand the structure-property evolution during crystallization of a semicrystalline thermoplastic polymer. A combination of techniques including rheology, small angle light scattering, differential scanning calorimetry and optical microscopy are applied to follow the mechanical and optical properties along with crystallinity and the morphology. Isothermal crystallization experiments on isotactic poly-1-butene at early stages of spherulite growth provide quantitative information about nucleation density, volume fraction of spherulites and their crystallinity, and the mechanism of connecting into a sample spanning structure. Optical microscopy near the fluid-to-solid transition suggests that the transition, as determined by time-resolved mechanical spectroscopy, is not caused by packing/jamming of spherulites but by the formation of a percolating network structure. The effect of strain, Weissenberg number (We ) and specific mechanical work (w) on rate of crystallization (nucleation followed by growth) and on growth of anisotropy was studied for shear-induced crystallization of isotactic poly-1-butene. The samples were sheared for a finite strain at the beginning of the experiment and then crystallized without further flow (Janeschitz-Kriegl protocol). Strain requirements to attain steady state/leveling off of the rate of crystallization were found to be much larger than the strain needed to achieve steady state of flow. The large strain and We>1 criteria were also observed for morphological transition from spherulitic growth to oriented growth. An apparatus for small angle light scattering (SALS) and light transmission measurements under shear was built and tested at the University of Massachusetts Amherst. As a new development, the polarization direction can be rotated by a liquid crystal polarization rotator (LCPR) with a short response time of 20 ms. The experiments were controlled and analyzed with a LabVIEW(TM) based

  2. CAChe Molecular Modeling: A Visualization Tool Early in the Undergraduate Chemistry Curriculum

    NASA Astrophysics Data System (ADS)

    Crouch, R. David; Holden, Michael S.; Samet, Cindy

    1996-10-01

    In Dickinson's chemistry curriculum, "Synthesis & Reactivity" replaces the traditional organic chemistry sequence and begins in the second semester of the freshman year. A key aspect of our sequence is the correlation of laboratory experiments with lecture topics and the extension of laboratory exercises beyond the usual 4-hour period. With this goal in mind, a number of "Synthesis & Reactivity" experiments have been developed that include an out-of-class computational chemistry exercise using CAChe (1), a versatile molecular modeling software package. Because the first semester of "Synthesis & Reactivity" has a large number of freshmen, emphasis is placed on developing an insight for where nucleophiles and electrophiles might attack a molecule. The Visualizer+ routine in CAChe generates striking graphical images of these sites and the reaction of NBS/H2O with 3-sulfolene (2) presents an excellent opportunity to introduce CAChe into an experiment. Before the laboratory, students are introduced to CAChe to determine how NBS might interact with a nucleophile such as an alkene. Students then return to the laboratory to perform the bromohydrin synthesis but are asked to consider what the regiochemistry would be were the alkene not symmetric. Specifically, students are instructed to visit the computer laboratory during the week and perform calculations on the bromonium ion formed from 2-methylpropene to determine where a nucleophilic H2O molecule might attack. The MOPAC routine in CAChe provides data that are converted to a graphical depiction of the frontier density of the intermediate, indicating potential reactive sites based on electron distribution of orbitals near the HOMO and LUMO. When these data are manipulated by Visualizer+, the obvious conclusion is that the nucleophilic water molecule should attack the more highly substituted carbon of the bromonium ion (Fig. 1) and generate one regioisomer. Figure 1. Relative nucleophilic susceptibilities ofr the

  3. VOCs Speciation From Steam Boiler Stacks of Industries Located in Naucalpan

    NASA Astrophysics Data System (ADS)

    Mejia, G. M.; Tejeda, D. D.; Bremauntz, M. P.; Valdez, A.; Montufar, P. C.; Martinez, M. A.; Sierra, M. J.; Gonzalez, C. A.

    2007-05-01

    Results of VOCs speciation from industrial steam boiler stacks located in Naucalpan are presented and discussed. This municipality is located north of the Metropolitan Zone of the Valley of Mexico (MZVM). Speciation of VOCs is important to generate information about sources of pollution, to update emission inventories, to study the dynamics of pollutants in the atmosphere, and to estimate possible risks of population exposure. This information is valuable for decision making on air pollution control strategies. Samples from 35 steam boilers form industries burning Diesel, LPG, or CNG were taken using the US-EPA Method 18. Selected samples from the use of different fuels were analyzed using gas chromatography and flame ionization detection (GC-FID) according to US-EPA protocol TO-14. The VOCs analyzed included alkanes of 9 carbons or less, alkenes of 7 carbons or less and aromatics (families of benzene). The results show consistency on the VOCs detected on Diesel samples. The main compounds found were 1- Butene+iButylene, m/p-Xylene, Ethane, Propene, Propane, Acetylene, 2Me-1Butene, and Toluene. The average concentrations of these compounds were in the range of 130 to 385 ppbC. The results of LPG samples did not show a definite pattern of VOCs, although light components predominate and, in some samples, Toluene and Xylene. These last components were not expected for industries reporting the use of LPG, perhaps due to the use of a combination of fuels and mistakes in the reports of fuel used at the time of sampling. The analysis of CNG samples show predominance of light VOCs, in the range of 90 to 300 ppbC. As in the case of LPG, some aromatics showed high concentrations in some samples analyzed perhaps due to the use of different fuels in the boiler. The results of this study are the first results of VOCs speciation obtained form exhaust gases from stacks of Mexican industries. The data reported are valuable to analyze emission inventories of VOCs and to better

  4. (Phenoxyimidazolyl-salicylaldimine)iron complexes: synthesis, properties and iron catalysed ethylene reactions.

    PubMed

    Yankey, Margaret; Obuah, Collins; Guzei, Ilia A; Osei-Twum, Emmanuel; Hearne, Giovanni; Darkwa, James

    2014-10-01

    The reaction of 2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L1), 2,4-di-tert-butyl-6-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L2) or 4-tert-butyl-2-{[2-(1H-imidazol-4-yl)-ethylimino]-methyl}-phenol (L3) with iron(ii) precursors produced either iron(ii) or iron(iii) complexes, depending on the nature of the anions in the iron(ii) precursor and the ligand. When the anion is chloride and the ligand L1, the product is [(L1)2Fe][FeCl4] (1), but when the anion is triflate (OTf(-)) and the ligand is L2, the product is [(L2)2Fe][OTf]2 (2). With iron(ii) halides and tert-butyl groups on the phenoxy ligands L2 and L3, the iron(iii) complexes [(L2)FeX2] {where X = Cl (3), Br (4) and I = (5)} and [(L3)FeCl2] (6) were formed. Complexes 1-6 were characterised by a combination of elemental analyses, IR spectroscopy and mass spectrometry; and in selected cases (3 and 4) by single crystal X-ray crystallography. The crystal structures of 3 and 4 indicated that the iron(ii) precursors oxidised to iron(iii) in forming complexes 3-6; an observation that was corroborated by the magnetic properties and the (57)Fe Mössbauer spectra of 3 and 4. The iron(iii) complexes 3-6 were used as pre-catalysts for the oligomerisation and polymerisation of ethylene. Products of these ethylene reactions depended on the solvent used. In toluene ethylene oligomerised mainly to 1-butene and was followed by the 1-butene alkylating the solvent to form butyl-toluenes via a Friedel-Crafts alkylation reaction. In chlorobenzene, ethylene oligomerised mainly to a mixture of C4-C12 alkenes. Interestingly small amounts of butyl-chlorobenzenes and hexyl-chlorobenzenes were also formed via a Friedel-Crafts alkylation with butenes and hexenes from the oligomerisation of ethylene. PMID:25111396

  5. Model vanadium-phosphorus-oxygen catalysts for the selective oxidation of C/sub 4/ hydrocarbons to maleic anhydride

    SciTech Connect

    Moser, T.P.

    1987-06-01

    Two model vanadium-phosphorus-oxygen catalysts, ..beta..-VOPO/sub 4/ and (VO)/sub 2/P/sub 2/O/sub 7/, were investigated for the selective oxidation of C/sub 4/ hydrocarbons to maleic anhydride. In situ laser Raman spectroscopy was used. Complementary techniques including x-ray powder diffraction and x-ray photoelectron spectroscopy were used for characterization of the fresh and used catalytic materials. The direct observation of phase stability and the participation of lattice oxygen during catalysis was possible using the in situ Raman technique. In particular, ..beta..-VOPO/sub 4/ and (VO)/sub 2/P/sub 2/O/sub 7/ demonstrated bulk structural integrity during n-butane oxidation. The relatively greater reducing capacity of 1-butene induced the ..beta..-VOPO/sub 4/ to (VO)/sub 2/P/sub 2/O/sub 7/ phase transformation. Direct structural identification of catalytically active centers for paraffin and olefin oxidation were investigated using an /sup 18/O-enriched ..beta..-VOPO/sub 4/ phase catalyst. Active sites responsible for complete combustion (Site I) and selective oxidation (Site II) were identified. The selective route for 1-butene oxidation involved predominantly Site II centers, while Site I centers were associated with complete combustion. In contrast, n-butane oxidation required the highly active Site I centers for initial activation and for the formation of an intermediate containing two oxygen atoms. Raman band assignments indicated these oxygen sites were associated with PO/sub 4/ units in the ..beta..-VOPO/sub 4/ lattice. Maleic anhydride conversion was particularly sensitive to the catalytic phase present. Significant combustion activity was observed when maleic anhydride was fed directly to an integral flow reactor charged with model catalysts. The combustion activity was least for (VO)/sub 2/P/sub 2/O/sub 7/, nominally a V(IV) phase. The ..beta..-VOPO/sub 4/ catalyst, nominally a V(V) phase, resulted in increased conversions of maleic anhydride.

  6. [Emission Characteristics of VOCs from Typical Restaurants in Beijing].

    PubMed

    Cui, Tong; Cheng, Jing-chen; He, Wan-qing; Ren, Pei-fang; Nie, Lei; Xu, Dong-yao; Pan, Tao

    2015-05-01

    Using the EPA method, emission of volatile organic compounds (VOCs) , sampled from barbecue, Chinese and Western fast-food, Sichuan cuisine and Zhejiang cuisine restaurants in Beijing was investigated. VOCs concentrations and components from different cuisines were studied. The results indicated that based on the calibrated baseline ventilation volume, the VOCs emission level from barbecue was the highest, reaching 12.22 mg · m(-3), while those from fast-food of either Chinese or Western, Sichuan cuisine and Zhejiang cuisine were about 4 mg · m(-3). The components of VOCs from barbecue were different from those in the other cuisines, which were mainly propylene, 1-butene, n-butane, etc. The non-barbecue cuisines consisted of high concentration of alcohols, and Western fast-food contained relatively high proportion of aldehydes and ketones organic compounds. According to emission concentration of baseline ventilation volume, barbecue released more pollutants than the non-barbecue cuisines at the same scale. So, barbecue should be supervised and controlled with the top priority. PMID:26314095

  7. Modifications of surface properties of a H{sub 2}-treated RuS{sub 2}/SiO{sub 2} catalyst: A parallel between low-temperature CO FTIR spectroscopy and model reactions

    SciTech Connect

    Berhault, G.; Mauge, F.; Lavalley, J.C.; Lacroix, M.; Breysse, M.

    2000-01-25

    A silica-supported ruthenium sulfide catalyst was progressively reduced by hydrogen at increasing temperatures (423--673 K). The resulting modification of the surface properties was characterized by low-temperature CO adsorption FTIR spectroscopy and by test reactions such as CH{sub 3}SH condensation and 1-butene hydrogenation. On the nonreduced catalyst, CO adsorption spectra showed the presence of bands, indicating various CO forms on Ru sites in a sulfur-rich environment. When sulfur was progressively removed from the ruthenium sulfide phase, the number of coordinatively unsaturated Ru sites increased with the simultaneous formation of metallic Ru microdomains. A comparison of measurements of adsorption and catalytic activity showed that a rich sulfur environment was needed for the condensation of CH{sub 3}SH to CH{sub 3}SCH{sub 3}, a reaction that required acidic sites, while butene hydrogenation required highly depleted Ru sites. These results show that, upon reduction, RuS{sub 2} became less acidic and increasingly more metallic.

  8. Effect of pretreatment with dehulling and microwaving on the flavor characteristics of cold-pressed rapeseed oil by GC-MS-PCA and electronic nose discrimination.

    PubMed

    Zhou, Qi; Yang, Mei; Huang, Fenghong; Zheng, Chang; Deng, Qianchun

    2013-07-01

    Raw and dehulled rapeseeds were treated with microwave energy (800 W) from 1 to 8 min with 1-min intervals at a frequency of 2450 MHz to investigate the influence of microwaving and dehulling pretreatment on the flavor characteristics of rapeseed oil extracted by pressing. Headspace solid phase microextraction was used to isolate the volatile compounds of rapeseed oil, which were then identified by gas chromatography-mass spectrometry analysis. The results indicated that microwave and dehulling pretreatment of rapeseed can significantly influence the kinds and content of volatile compounds. The key flavor compounds in rapeseed oil were oxidized volatiles, heterocyclic compounds, and degradation products of glucosinolates. A pungent compound, 4-isothiocyanato-1-butene, was reduced by 97% in rapeseed treated for 3 min with microwaves energy when compared to the rapeseed oil without any treatment. The pyrazine compounds in the oil appeared after 6 min of microwave pretreatment and give a pleasant roasting flavor when compared to crude oils. Principal component analysis was able to differentiate between oils obtained using 4 pretreatment processes based on volatile compounds and electronic nose. The results showed that dehulling pretreatment could improve the flavor, yet microwaving had a greater effect on the flavor of rapeseed oils.

  9. Temperature-programmed sulfiding of precursor cobalt oxide genesis of highly active sites on sulfided cobalt catalyst for hydrogenation and isomerization

    SciTech Connect

    Inamura, Kazuhiro; Takyu, Toshiyuki ); Okamoto, Yasuaki; Nagata, Kozo; Imanaka, Toshinobu )

    1992-02-01

    It was found that the method of sulfidation of cobalt oxide strongly affects the catalytic activities and selectivities of the resultant cobalt sulfide catalyst, as well as the calcination temperature of the cobalt oxide. When cobalt oxide was sulfided at 673 K by a temperature-programmed sulfiding method (a heating rate of 6 K/min), catalytic activities for the hydrogenation of butadiene and the isomerization of 1-butene were considerably enhanced compared with those for cobalt sulfide prepared by isothermal sulfidation at 673 K. Results of temperature-programmed sulfiding (TPS), temperature-programmed reduction (TPR), and X-ray diffraction (XRD) suggest that the catalysts showing high catalytic activities after sulfidation are partially sulfided at 673 K and consist of the unsulfided cobalt core phases (CoO or metallic Co). The sulfidation property of precursor cobalt oxides has been studied using TPS, simulating the sulfidation process of the cobalt sulfide catalysts. Two distinctly different kinds of sulfidation process are estimated by TPS measurements of the cobalt oxides. The calcination temperature of the precursor cobalt oxides strongly affects the sulfidation paths. They are differentiated in terms of the presence of a metallic Co intermediate. The relationship of the mechanism of sulfidation of the cobalt oxides to the generation of highly active sites is discussed.

  10. ( l brace (. eta. sup 5 -C sub 5 Me sub 4 )Me sub 2 Si(. eta. sup 1 -NCMe sub 3 ) r brace (PMe sub 3 )ScH) sub 2 : A unique example of a single-component. alpha. -olefin polymerization catalyst

    SciTech Connect

    Shapiro, P.J.; Bunel, E.; Schaefer, W.P.; Bercaw, J.E. )

    1990-03-01

    The synthesis and structure of the title compound are described. ({l brace}({eta}{sup 5}-C{sub 5}Me{sub 4})Me{sub 2}Si({eta}{sup 1}-NCMe{sub 3}){r brace}Sc(PMe{sub 3})){sub 2}({mu}-H){sub 2} (3) crystallizes with a molecule of toluene per scandium in the monoclinic system, space group C2/c, with a = 21.238 (3) {angstrom}, b = 11.470 (2) {angstrom}, c = 22.253 (3) {angstrom}, {beta} = 113.16 (1){degree}, V = 4984.0 (14) {angstrom}{sup 3}, Z = 8 (four dimers), and d = 1.24 g{center dot}cm{sup {minus}3}. Propene, 1-butene, and 1-pentene are cleanly, albeit slowly, polymerized with >99% head-to-tail coupling to produce linear, atactic polymers with M{sub n} = 3,000-4,000 and PDI's of 1.7-2.1. Chain transfer is relatively slow and appears to occur by {beta}-H elimination. All evidence points to a one-component catalyst system with all scandium centers functioning alike.

  11. Ruta montana L. leaf essential oil and extracts: characterization of bioactive compounds and suppression of crown gall disease.

    PubMed

    Hammami, Inés; Smaoui, Slim; Hsouna, Anis Ben; Hamdi, Naceur; Triki, Mohamed Ali

    2015-01-01

    The aims of this study were to assess the antimicrobial efficacy of the leaf essential oil and the leaf extracts of R. montana against Botrytis cinerea, Fusarium oxysporum, Verticillium dahliae, Aspergillus oryzae and Fusarium solani. The oil (1.000 µg/disk) and the extracts (1.500 µg/disk) revealed a remarkable antifungal effect against the tested plant pathogenic fungi with a radial growth inhibition percentage of 40.0-80.0 % and 5.0-58.0 %, respectively along with their respective MIC values ranging from 100 to 1100 µg/mL and 250 to 3000 µg/mL. The oil had a strong detrimental effect on spore germination of all the tested plant pathogens along with the concentration as well as time-dependent kinetic inhibition of Fusarium oxysporum. Also, the oil exhibited a potent in vivo antifungal effect against Botrytis cinerea on tomato plants. Experiments carried out in plant revealed that the essential oil was slightly effective in suppression of gall formation induced by Agrobacterium tumefaciens on bitter almond. The results of this study indicate that the oil and extracts of R. montana leaves could become natural alternatives to synthetic fungicides to control certain important plant microbial diseases. The GC-MS analysis determined that 28 compounds, which represented 89.03 % of total oil, were present in the oil containing mainly 1-butene, methylcyclopropane, 2-butene and caryophyllene oxide. PMID:26417353

  12. [Aluminum coordination and active sites on aluminas, Y-zeolites and pillared layered silicates]. Progress report

    SciTech Connect

    Fripiat, J.J.

    1994-02-01

    This report is organized in four sections. In the first the authors will outline structural features which are common to all fine grained alumina, as well as to non-framework alumina in zeolites. This section will be followed by a study of the surface vs. bulk coordination of aluminum. The third section will deal with measurement of the number of acid sites and the scaling of their strength. The fourth and last section will describe three model reactions: the isomerization of 1-butene and of 2 cis-butene; the isomerization and disproportionation of oxtho-xylene; and the transformation of trichloroethane into vinyl chloride followed by the polymerization of the vinyl chloride. The relationship between chemical activity and selectivity and what is known of the local structure of the active catalytic sites will be underlined. Other kinds of zeolites besides Y zeolite have been studied. Instead of the aluminum pillared silicates they found it more interesting to study the substitution of silicon by aluminum in a layered structure containing a permanent porosity (aluminated sepiolite).

  13. Development and characterization of ZnO, Au/ZnO and Pd/ZnO thin films through their adsorptive and catalytic properties.

    PubMed

    Giannoudakos, A; Agelakopoulou, T; Asteriadis, I; Kompitsas, M; Roubani-Kalantzopoulou, F

    2008-04-11

    In this paper, we report (a) the development of ZnO thin films prepared by pulsed laser deposition and partially covered with nano-particles Pd or Au and (b) their physicochemical study, in order to investigate their catalytic and/or adsorptive properties. It is the first time where two different and popular methods, namely pulsed laser deposition and reversed flow-inverse gas chromatography, are combined. The inverse gas chromatographic technique with the corresponding time-resolved analysis is used for the first time in order to characterise compounds in the nano-scale domain. We focus on the determination of physicochemical quantities mainly concerning the adsorption in thin films, with (Pd/ZnO) or without (Au/ZnO) catalytic behaviour. Thus, entropy and other important physicochemical quantities are calculated which reveal the mechanism of adsorption as well as of isomerization-hydrogenation of 1-butene and contribute to the study of heterogeneity of thin film surfaces. The programs used have been written in Fortran. An important achievement is also the determination of the standard deviations of the kinetic constants. PMID:18313683

  14. New analytical method for the determination of styrene oligomers formed from polystyrene decomposition and its application at the coastlines of the North-West Pacific ocean.

    PubMed

    Saido, Katsuhiko; Koizumi, Koshiro; Sato, Hideto; Ogawa, Naoto; Kwon, Bum Gun; Chung, Seon-Yong; Kusui, Takashi; Nishimura, Masahiko; Kodera, Yoichi

    2014-03-01

    The pollution caused by plastic debris is an environmental problem with increasing concern in the oceans. Among the plastic polymers, polystyrene (PS) is one of the most problematic plastics due to the direct public health risk associated with their dispersion, as well as the numerous adverse environmental impacts which arise both directly from the plastics and from their degradation products. Little is known about their potential distribution characteristics throughout the oceans. For the first time, we report here on the regional distribution of styrene monomer (SM), styrene dimers (SD; 2,4-diphenyl-1-butene, SD1; 1,3-diphenyl propane, SD2), and styrene trimer (2,4,6-triphenyl-1-hexene: ST1), as products of PS decomposition determined from samples of sand and seawater from the shorelines of the North-West Pacific ocean. In order to quantitatively determine SM, SD (=SD1+SD2), and ST1, a new analytical method was developed. The detection limit was 3.3 μg L(-1), based on a signal-to-noise ratio of three, which was well-suited to quantify levels of SM, SD, and ST1 in samples. Surprisingly, the concentrations of SM, SD, and ST1 in sand samples from the shorelines were consistently greater than those in seawater samples from the same location. The results of this study suggest that SM, SD, and ST1 can be widely dispersed throughout the North-West Pacific oceans. PMID:24394362

  15. Synthesis of novel acid electrolytes for phosphoric acid fuel cells

    NASA Astrophysics Data System (ADS)

    Adcock, James L.

    1988-11-01

    A 40 millimole per hour scale aerosol direct fluorination reactor was constructed. F-Methyl F-4-methoxybutanoate and F-4-methoxybutanoyl fluoride were synthesized by aerosol direct fluorination of methyl 4-methoxybutanoate. Basic hydrolysis of the perfluorinated derivatives produce sodium F-4 methoxybutanoate which was pyrolyzed to F-3-methoxy-1-propene. Purification and shipment of 33 grams of F-3-methoxy-1-propene followed. Syntheses by analogous methods allowed production and shipment of 5 grams of F-3-ethoxy 1-propene, 18 grams of F-3-(2-methoxy.ethoxy) 1-propene, and 37 grams of F-3,3-dimethyl 1-butene. Eighteen grams of F-2,2-dimethyl 1-chloropropane was produced directly and shipped. As suggested by other contractors, 5 grams of F-3-methoxy 1-iodopropane, and 5 grams of F-3-(2-methoxy.ethoxy) 1-iodopropane were produced by converting the respective precursor acid sodium salts produced for olefin synthesis to the silver salts and pyrolyzing them with iodine. Each of these compounds was prepared for the first time by the aerosol fluorination process during the course of the contract. These samples were provided to other Gas Research Institute (GRI) contractors for synthesis of perfluorinated sulfur (VI) and phosphorous (V) acids.

  16. An extended hindered-rotor model with incorporation of Coriolis and vibrational-rotational coupling for calculating partition functions and derived quantities

    NASA Astrophysics Data System (ADS)

    Vansteenkiste, P.; Van Neck, D.; Van Speybroeck, V.; Waroquier, M.

    2006-01-01

    Large-amplitude motions, particularly internal rotations, are known to affect substantially thermodynamic functions and rate constants of reactions in which flexible molecules are involved. Up to now all methods for computing the partition functions of these motions rely on the Pitzer approximation of more than 50 years ago, in which the large-amplitude motion is treated in complete independence of the other (vibrational) degrees of freedom. In this paper an extended hindered-rotor model (EHR) is developed in which the vibrational modes, treated harmonically, are correctly separated from the large-amplitude motion and in which relaxation effects (the changes in the kinetic-energy matrix and potential curvature) are taken into account as one moves along the large-amplitude path. The model also relies on a specific coordinate system in which the Coriolis terms vanish at all times in the Hamiltonian. In this way an increased level of consistency between the various internal modes is achieved, as compared with the more usual hindered-rotor (HR) description. The method is illustrated by calculating the entropies and heat capacities on 1,3-butadiene and 1-butene (with, respectively, one and two internal rotors) and the rate constant for the addition reaction of a vinyl radical to ethene. We also discuss various variants of the one-dimensional hindered-rotor scheme existing in the literature and its relation with the EHR model. It is argued why in most cases the HR approach is already quite successful.

  17. Emission characteristics of volatile organic compounds from coal-, coal gangue-, and biomass-fired power plants in China

    NASA Astrophysics Data System (ADS)

    Yan, Yulong; Yang, Chao; Peng, Lin; Li, Rumei; Bai, Huiling

    2016-10-01

    Face the large electricity demand, thermal power generation still derives the main way of electricity supply in China, account for 78.19% of total electricity production in 2013. Three types of thermal power plants, including coal-fired power plant, coal gangue-fired power plant and biomass-fired power plant, were chosen to survey the source profile, chemical reactivity and emission factor of VOCs during the thermal power generation. The most abundant compounds generated during coal- and coal gangue-fired power generation were 1-Butene, Styrene, n-Hexane and Ethylene, while biomass-fired power generation were Propene, 1-Butenen, Ethyne and Ethylene. The ratios of B/T during thermal power generation in this study was 0.8-2.6, which could be consider as the characteristics of coal and biomass burning. The field tested VOCs emission factor from coal-, coal gangue- and biomass-fired power plant was determined to be 0.88, 0.38 and 3.49 g/GJ, or showed as 0.023, 0.005 and 0.057 g/kg, with the amount of VOCs emission was 44.07, 0.08, 0.45 Gg in 2013, respectively. The statistical results of previous emission inventory, which calculated the VOCs emission used previous emission factor, may overestimate the emission amount of VOCs from thermal power generation in China.

  18. Hydrocarbon Source Signatures in Houston, Texas: Influence of the Petrochemical Industry

    SciTech Connect

    Jobson, B Tom T; Berkowitz, Carl M; Kuster, W C; Goldan, P D; Williams, E J; Fesenfeld, F; Apel, Eric; Karl, Thomas G; Lonneman, William A; Riemer, D

    2004-12-22

    Observations of C1-C10 hydrocarbon mixing ratios measured by in-situ instrumentation at the La Porte super site during the TexAQS 2000 field experiment are reported. The La Porte data were compared to a roadway vehicle exhaust signature obtained from canister samples collected in the Houston Washburn tunnel during the same summer to better understand the impact of petrochemical emissions of hydrocarbons at the site. It is shown that the abundance of ethene, propene, 1-butene, C2-C4 alkanes, hexane, cyclohexane, methylcyclohexane, isopropylbenzene, and styrene at La Porte were systematically impacted by petrochemical industry emissions. Coherent power law relationships between frequency distribution widths of hydrocarbon mixing ratios and their local lifetimes clearly identify two major source groups, roadway vehicle emissions and industrial emissions. Distributions of most aromatics and long chain alkanes were consistent with roadway vehicle emissions as the dominant source. Airmass reactivity was generally dominated by C1-C3 aldehydes. Propene and ethene sometimes dominated air mass reactivity with HO loss frequencies often greater than 10 s-1. Ozone mixing ratios near 200 ppbv were observed on two separate occasions and these air masses appear to have been impacted by industrial emissions of alkenes from the Houston Ship Channel. The La Porte data provide evidence of the importance of industrial emissions of ethene and propene on air masses reactivity and ozone formation in Houston.

  19. CYP 17 and CYP 19 inhibitors. Evaluation of fluorine effects on the inhibiting activity of regioselectively fluorinated 1-(Naphthalen-2-ylmethyl)imidazoles.

    PubMed

    Hartmann, Rolf W; Palusczak, Anja; Lacan, Fabrice; Ricci, Giacomo; Ruzziconi, Renzo

    2004-04-01

    Regioselectively fluorinated 1-(naphth-2-ylmethyl)imidazoles 1a-h have been synthesized starting from the corresponding (naphth-2-yl)methanols (2). 2a-d have been obtained by LiAlH4-promoted reduction of fluorinated 1-methyl-2-naphthaldehydes. The latter were easily prepared in fairly good overall yields by ceric ammonium nitrate (CAN)-promoted oxidative addition of the suitable 3-(fluoroaryl)-1-trimethylsilyloxy-1-butenes to ethyl vinyl ether in methanol followed by cyclization of the resulting acetals in strongly acidic medium in the presence of DDQ. 2e-h were prepared by LiAlH4-promoted reduction of the corresponding fluorinated methyl 2-naphthoates. The latter were more profitably obtained by reacting the suitable benzyl bromide with the sodium salt of dimethyl 2-(2,2-dimethoxyethyl)malonate in DMF followed by demethoxycarbonylation and acid catalysed cyclization of the resulting acetals. Compared with the nonfluorinated parent compounds 1i-1, fluorinated 1-(naphth-2-yl)methylimidazoles 1a-h turned out to be potent inhibitors of CYP17 and CYP19 enzymes. The most active inhibitor of CYP17 is 1c, whereas CYP19 is strongly inhibited by 1b, 1e, and 1g. Interestingly, 1g is a potent dual inhibitor also being very active towards CYP19.

  20. Monobenzofused 1,4-azaborines: synthesis, characterization, and discovery of a unique coordination mode.

    PubMed

    Xu, Senmiao; Haeffner, Fredrik; Li, Bo; Zakharov, Lev N; Liu, Shih-Yuan

    2014-06-23

    We report the first general synthesis of boron-substituted monobenzofused 1,4-azaborines using ring-closing metathesis of an enamine-containing diene as a key synthetic strategy. As part of our investigations, we discovered that the B-C3 moiety in a 1,4-azaborine can serve uniquely as a η(2)-L-type ligand. This functionality is exemplified by two κ(2)-N-η(2)-BC Pt complexes of a boron-pyridyl-substituted monobenzofused-1,4-azaborine. Single-crystal X-ray diffraction analysis of the Pt complexes shows a strong structural contribution from the iminium resonance form of the monobenzofused-1,4-azaborine ligand. We also demonstrate that a palladium(0) complex supported by a 1,4-azaborine-based phosphine ligand can catalyze hydroboration of 1-buten-3-yne with unique selectivity. In view of the importance of arene-metal π-interactions in catalytic applications, this work should open new opportunities for ligand design involving the 1,4-azaborine motif as an arene substitute.

  1. Gas-phase reactions of doubly charged actinide cations with alkanes and alkenes--probing the chemical activity of 5f electrons from Th to Cm.

    PubMed

    Marçalo, Joaquim; Santos, Marta; Gibson, John K

    2011-11-01

    Small alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) were used to probe the gas-phase reactivity of doubly charged actinide cations, An(2+) (An = Th, Pa, U, Np, Pu, Am, Cm), by means of Fourier transform ion cyclotron resonance mass spectrometry. Different combinations of doubly and singly charged ions were observed as reaction products, comprising species formed via metal-ion induced eliminations of small molecules, simple adducts and ions resulting from electron, hydride or methide transfer channels. Th(2+), Pa(2+), U(2+) and Np(2+) preferentially yielded doubly charged products of hydrocarbon activation, while Pu(2+), Am(2+) and Cm(2+) reacted mainly through transfer channels. Cm(2+) was also capable of forming doubly charged products with some of the hydrocarbons whereas Pu(2+) and Am(2+) were not, these latter two ions conversely being the only for which adduct formation was observed. The product distributions and the reaction efficiencies are discussed in relation to the electronic configurations of the metal ions, the energetics of the reactions and similar studies previously performed with doubly charged lanthanide and transition metal cations. The conditions for hydrocarbon activation to occur as related to the accessibility of electronic configurations with one or two 5f and/or 6d unpaired electrons are examined and the possible chemical activity of the 5f electrons in these early actinide ions, particularly Pa(2+), is considered.

  2. Kinetic and mechanistic study of the atmospheric reaction of MBO331 with Cl atoms

    NASA Astrophysics Data System (ADS)

    Rodríguez, Diana; Rodríguez, Ana; Garzón, Andrés; Granadino-Roldán, José M.; Soto, Amparo; Aranda, Alfonso; Notario, Alberto

    2012-12-01

    The present work deals with the reaction of 3-methyl-3-buten-1-ol (MBO331) with Cl atoms, which has been investigated by gas chromatography with flame ionization detection (GC-FID) at atmospheric pressure in N2 or air, using the relative rate technique. The rate constant reaction at 298 ± 1 K was found to be (5.01 ± 0.70) × 10-10 cm3 molecule-1 s-1, using cyclohexane, octane and 1-butene as a reference compounds. The temperature dependence for the reaction was studied within the 298-333 K range. Additionally, a product identification under atmospheric conditions has been performed for the first time by GC-MS, with 3-methyl-3-butenal, methacrolein and chloroacetone being observed as degradation products. A theoretical study on the reaction at the QCISD(T)/6-311G**//MP2/6-311G** level was also carried out to obtain more information on the mechanism. From the theoretical study it can be predicted that Cl addition to the double bond proceeds through lower energy barriers than H-abstraction pathways and therefore is energetically favoured. Finally, atmospheric implications of the results obtained are discussed.

  3. Photochemistry of 1 and 2-(2-methylphenyl)-1,6-heptadiene. [4a-methyl-1,2,3,4,4a,9,10,10a-octahydrophenanthrene

    SciTech Connect

    Barrows, R.D.; Hornback, J.M.

    1982-01-01

    In an attempt to synthesize partially saturated phenanthrene derivatives by an intramolecular Diels-Alder reaction between a photochemically produced o-xylylene (diene) and a tethered dienophile, it was found that 1 and 2 underwent a photochemically allowed (2 + 2) cycloaddition. Irradiation of 1 gave 6-(2-methylphenyl)bicyclo(3.2.0)heptane in 86% yield. Upon irradiation of 2, a benzvalene rearrangement of 2 first took place, producing the meta isomer 2-(3-methylphenyl)-1,6-heptadiene, followed by a (2 + 2) photocycloaddition giving 1-(3-methylphenyl)bicyclo(3.2.0)heptane in 15% yield. Direct irradiation of 2-(3-methylphenyl)-1,6-heptadiene gave the same bicyclo derivative as 2 in 34% yield. Examination of the fluorescence spectra of 1 and 2 in comparison with 1-(2-methylphenyl)propene and 2-(2-methylphenyl)-1-butene, respectively, has shown that 1 may be biased toward (2 + 2) cycloaddition where 2 is not biased toward (2 + 2) photocycloization. Attempts to produce 4a-methyl-1,2,3,4,4a,9,10,10a-octahydrophenanthrene by an intramolecular Diels-Alder reaction of the o-xylylene produced by irradiation of 3 will also be described.

  4. A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol.

    PubMed

    Pavarelli, Giulia; Velasquez Ochoa, Juliana; Caldarelli, Aurora; Puzzo, Francesco; Cavani, Fabrizio; Dubois, Jean-Luc

    2015-07-01

    We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.

  5. New analytical method for the determination of styrene oligomers formed from polystyrene decomposition and its application at the coastlines of the North-West Pacific ocean.

    PubMed

    Saido, Katsuhiko; Koizumi, Koshiro; Sato, Hideto; Ogawa, Naoto; Kwon, Bum Gun; Chung, Seon-Yong; Kusui, Takashi; Nishimura, Masahiko; Kodera, Yoichi

    2014-03-01

    The pollution caused by plastic debris is an environmental problem with increasing concern in the oceans. Among the plastic polymers, polystyrene (PS) is one of the most problematic plastics due to the direct public health risk associated with their dispersion, as well as the numerous adverse environmental impacts which arise both directly from the plastics and from their degradation products. Little is known about their potential distribution characteristics throughout the oceans. For the first time, we report here on the regional distribution of styrene monomer (SM), styrene dimers (SD; 2,4-diphenyl-1-butene, SD1; 1,3-diphenyl propane, SD2), and styrene trimer (2,4,6-triphenyl-1-hexene: ST1), as products of PS decomposition determined from samples of sand and seawater from the shorelines of the North-West Pacific ocean. In order to quantitatively determine SM, SD (=SD1+SD2), and ST1, a new analytical method was developed. The detection limit was 3.3 μg L(-1), based on a signal-to-noise ratio of three, which was well-suited to quantify levels of SM, SD, and ST1 in samples. Surprisingly, the concentrations of SM, SD, and ST1 in sand samples from the shorelines were consistently greater than those in seawater samples from the same location. The results of this study suggest that SM, SD, and ST1 can be widely dispersed throughout the North-West Pacific oceans.

  6. Exploring Molecular Dimension and Trajectory of Polymer Chains Embedded in Single Crystals

    NASA Astrophysics Data System (ADS)

    Hong, Youlee; Miyoshi, Toshikazu

    2015-03-01

    Semicrystalline polymers are crystallized as folded chains in thin lamellae of ca. 5-20 nm from random coils in the melt and solution states.. Even though there are continuous efforts on understanding of crystallization mechanisms at molecular levels for understanding of crystallization mechanism of polymers at molecular levels, the fundamental questions - when, where, and how do semicrystalline polymers fold during crystallization?- have not been clarified due to experimental limitations. Recently, we developed a novel strategy to access chain trajectory of semi-crystalline polymers using 13C -13C double Quantum (DQ) NMR. In this work, we recently investigated determined molecular dimension as well as chain-trajectory of 13C CH3-labeled isotactic poly(1-butene) (iPB1) in form III chiral single crystals blended with nonlabeled iPB1 crystallized under low supercooling, using solid-state NMR. Comparisons of 13C -13C double quantum (DQ) NMR results at multiple sites with spin dynamics simulation revealed individual chains form the three dimensional nanoclusters via folding. This result supports proves two step process of i) cluster formation by chain-folding the prestage of crystallization. and ii) depositions of the cluster on the growth front of single crystal. National Science Foundation.

  7. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    NASA Astrophysics Data System (ADS)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  8. Mixed interactions in random copolymers

    NASA Astrophysics Data System (ADS)

    Marinov, Toma; Luettmer-Strathmann, Jutta

    2002-03-01

    The description of thermodynamic properties of copolymers in terms of simple lattice models requires a value for the mixed interaction strength (ɛ_12) between unlike chain segments, in addition to parameters that can be derived from the properties of the corresponding homopolymers. If the monomers are chemically similar, Berthelot's geometric-mean combining rule provides a good first approximation for ɛ_12. In earlier work on blends of polyolefins [1], we found that the small-scale architecture of the chains leads to corrections to the geometric-mean approximation that are important for the prediction of phase diagrams. In this work, we focus on the additional effects due to sequencing of the monomeric units. In order to estimate the mixed interaction ɛ_12 for random copolymers, the small-scale simulation approach developed in [1] is extended to allow for random sequencing of the monomeric units. The approach is applied here to random copolymers of ethylene and 1-butene. [1] J. Luettmer-Strathmann and J.E.G. Lipson. Phys. Rev. E 59, 2039 (1999) and Macromolecules 32, 1093 (1999).

  9. Interactions in random copolymers

    NASA Astrophysics Data System (ADS)

    Marinov, Toma; Luettmer-Strathmann, Jutta

    2002-04-01

    The description of thermodynamic properties of copolymers in terms of simple lattice models requires a value for the effective interaction strength between chain segments, in addition to parameters that can be derived from the properties of the corresponding homopolymers. If the monomers are chemically similar, Berthelot's geometric-mean combining rule provides a good first approximation for interactions between unlike segments. In earlier work on blends of polyolefins [1], we found that the small-scale architecture of the chains leads to corrections to the geometric-mean approximation that are important for the prediction of phase diagrams. In this work, we focus on the additional effects due to sequencing of the monomeric units. In order to estimate the effective interaction for random copolymers, the small-scale simulation approach developed in [1] is extended to allow for random sequencing of the monomeric units. The approach is applied here to random copolymers of ethylene and 1-butene. [1] J. Luettmer-Strathmann and J.E.G. Lipson. Phys. Rev. E 59, 2039 (1999) and Macromolecules 32, 1093 (1999).

  10. Determining the melt miscibility of commercial polyolefin blends by Small-Angle Light Scattering

    NASA Astrophysics Data System (ADS)

    Peng, Ping

    2005-03-01

    The melt miscibility of high-density polyethylene (HDPE) (Mw = 52 kg/mol, PDI = 2.9) and linear low-density polyethylenes (LLDPEs) based on homogeneous ethylene-1-butene copolymers (EB0187: 18.7 mol% butene branches, Mw = 58.1 kg/mol and EB0059: 5.9 mol% butene branches, Mw = 70 kg/mol) is determined by Small-Angle Light Scattering (SALS) under parallel-polarized optical alignment. Blends with branching density differences (δy) ranging from 5.9 to 18.7 mol% were studied. For the HDPE/EB0187 blend, (δy = 18.7%), cooling and isothermal measurements (2 h) in the melt can be used to determine the miscibility and the phase boundary. When this blend is rapidly cooled room temperature, the resulting SALS patterns show that the size of phase separated domain (˜ 1 μm) is much smaller than the average spherulite size (68 μm). These results consist with our microscopic observations and the transmitted light measured simultaneously with the VV scattering in the melt. From the compositions studied, we can conclude that this blend exhibits UCST behavior. For blends with lower δy, isothermal measurements provide a sensitive means for determining the melt miscibility. Based on the above observations, we can conclude that SALS can be used to determine the melt miscibility of polyolefin blends.

  11. Chain-Folding Structures of a Semi-crystalline Polymer in Bulk and Single Crystals Elucidated by 13C-13C Double Quantum NMR

    NASA Astrophysics Data System (ADS)

    Hong, You-Lee; Miyoshi, Toshikazu

    2014-03-01

    Semi-crystalline polymers are crystallized as folded chains in thin lamellae of ca. 5-20 nm from random coils in the melt and solution states. However, understanding of detailed chain-folding structure and crystallization mechanism are still challenging issue due to various experimental limitations. We recently developed a new strategy using 13C-13C double-quantum (DQ) NMR with selectively 13C isotope labeled isotactic poly(1-butene) form I to investigate chain-trajectory in solution and melt grown crystals at various Tcs. This new method can determine the re-entrance sites, the successive folding number (n) , and the fractions (F) of chain-folding in a wide Tc range. In melt grown crystals at Tc = 95 °C, a comparison of experimental and simulated DQ efficiency determined that the polymer chains alternatively change chain-folding directions and the stems tightly pack via intramolecular interactions, and the fraction (F) of adjacent re-entry structure ranges from 70% at n = 4 to 100% at mixed structures of n = 1 and 2. Furthermore, DQ efficiency is independent of Tc in bulk crystals. This means chain-folding do not change in a wide Tcs. DMR-1105829.

  12. When Do Semi-crystalline Polymer Fold during Crystallization?

    NASA Astrophysics Data System (ADS)

    Miyoshi, Toshikazu; Hong, You-Lee

    2014-03-01

    Semi-crystalline polymers are crystallized as folded chains in thin lamellae of ca. 5-20 nm from random coils in the melt and solution states. Lauritzen-Hoffman theory implied the crystallization process is dominated by sequential stem deposition on the growth front. Conversely, Allegra proposed a bundle model in which aggregates of 10-20 stems are produced by folding in the pre-stage of crystallization. The pre-folded chains are kinetically deposited on the growth front and thus determine the morphology at different crystallization temperatures. The folded chains preserve their own chain-folding directions, numbers, and fractions as a function of concentrations and supercooling, which would provide detailed chain-folding mechanism. We recently developed a new strategy using 13C-13C double-quantum NMR to investigate chain-trajectory of 13C selectively labeled polymer in bulk crystals. Here, we report how re-entrance sites, fraction, and number of folded chains of isotactic poly(1-butene) in form III single crystals depends on supercooling conditions and solvent effects. On the basis of molecular level structures, we will discuss about chain-folding process of iPB1 in dilute solutions. DMR-1105829.

  13. Characterization and acidic properties of Al-SBA-15 materials prepared by post-synthesis alumination of a low-cost ordered mesoporous silica

    NASA Astrophysics Data System (ADS)

    Gómez-Cazalilla, M.; Mérida-Robles, J. M.; Gurbani, A.; Rodríguez-Castellón, E.; Jiménez-López, A.

    2007-03-01

    A series of Al-containing SBA-15 type materials with different Si/Al ratio, were prepared by post-synthesis modification of a pure highly ordered mesoporous silica SBA-15 obtained by using sodium silicate as silica source, and amphiphilic block copolymer as structure-directing agent. A high level of aluminum incorporation was achieved, reaching an Si/Al ratio of up to 5.5, without any significant loss in the textural properties of SBA-15. These materials were fully characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), 27Al NMR spectroscopy, and N 2 adsorption at 77 K. The acid properties of these materials have been evaluated by NH 3-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FTIR spectroscopy. The effective acidity of these materials was evaluated using two catalytic reactions: 2-propanol dehydrogenation and 1-butene isomerization. The adsorption of basic probe molecules and the catalytic behavior revealed an evolution of the acid properties with the Al content. These studies have shown that the Al-SBA-15 materials contain Brønsted and Lewis acid sites with medium acidity which makes them appropriate to be used as acid catalysts in heterogeneous catalysis, catalytic supports, and adsorbents.

  14. Orientation Control of Molecular Chains in Polymers Using Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Kimura, Kuniko; Kobayashi, Kei; Yamada, Hirofumi; Horiuchi, Toshihisa; Ishida, Kenji; Matsushige, Kazumi

    2004-07-01

    We successfully controlled the molecular orientation of flat-on lamellar crystals of the ferroelectric copolymer, vinylidenefluoride and trifluoroethylene (P(VDF-TrFE)), on Pt and Au surfaces utilizing atomic force microscopy (AFM). The orientation was controlled by scanning a cantilever tip in contact with the film surface whose temperature was kept at just below its melting point (Tm). The molecules were stretched in the scan direction and new edge-on crystals were subsequently formed, whose lamellar planes were perpendicular to the scan direction. We also attempted to modify an isotactic poly-1-butene (IPB) thin film and a polyaniline emeraldine base (PANI-EB) thin film utilizing AFM. In the case of IPB film, structures similar to edge-on crystals of P(VDF-TrFE) were obtained when modified with the film temperature kept at just below its Tm. The result strongly suggests that this orientation control technique is also applicable to IPB. On the other hand, in the case of PANI-EB film, we could obtain many ellipsoidal grains in the scanned area. One possible mechanism is that PANI-EB molecular chains were stretched parallel to the modification scan to form fibrils or bundles.

  15. Gas-Phase Reactions of Doubly Charged Lanthanide Cations with Alkanes and Alkenes. Trends in Metal(2+) Reactivity

    SciTech Connect

    Gibson, John K.; Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio; Haire, Richard G.

    2008-12-08

    The gas-phase reactivity of doubly-charged lanthanide cations, Ln2+ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), with alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) was studied by Fourier transform ion cyclotron resonance mass spectrometry. The reaction products consisted of different combinations of doubly-charged organometallic ions?adducts or species formed via metal-ion-induced hydrogen, dihydrogen, alkyl, or alkane eliminations from the hydrocarbons?and singly-charged ions that resulted from electron, hydride, or methide transfers from the hydrocarbons to the metal ions. The only lanthanide cations capable of activating the hydrocarbons to form doubly-charged organometallic ions were La2+, Ce2+, Gd2+, and Tb2+, which have ground-state or low-lying d1 electronic configurations. Lu2+, with an accessible d1 electronic configuration but a rather high electron affinity, reacted only through transfer channels. The remaining Ln2+ reacted via transfer channels or adduct formation. The different accessibilities of d1 electronic configurations and the range of electron affinities of the Ln2+ cations allowed for a detailed analysis of the trends for metal(2+) reactivity and the conditions for occurrence of bond activation, adduct formation, and electron, hydride, and methide transfers.

  16. Textural and structural properties and surface acidity characterization of mesoporous silica-zirconia molecular sieves

    NASA Astrophysics Data System (ADS)

    Rodríguez-Castellón, E.; Jiménez-López, A.; Maireles-Torres, P.; Jones, D. J.; Rozière, J.; Trombetta, M.; Busca, G.; Lenarda, M.; Storaro, L.

    2003-11-01

    Homogeneous mesoporous zirconium-containing MCM-41 type silica were prepared by supramolecular templating and their textural and structural properties were studied using powder X-ray diffraction, N 2 porosimetry, atomic force microscopy, EXAFS, XPS, and UV-VIS-NIR diffuse reflectance spectroscopy. Their acid properties were also studied by using IR spectroscopy and by the use of catalytic tests such as the decomposition of isopropanol and the isomerization of 1-butene. The materials prepared show a good degree of crystallinity with a regular ordering of the pores into a hexagonal arrangement and high thermal stability. The specific surface area of the prepared materials decreases as the zirconium content rises. Zirconium atoms are in coordination 7 to 8 and located at the surface of the pores such that a high proportion of the oxygen atoms bonded to zirconium corresponds to surface non-condensed oxygen atoms. Both facts are responsible for the acid properties of the solids that show weak Brønsted and medium strong Lewis acidity.

  17. On the Radiolysis of Ethylene Ices by Energetic Electrons and Implications to the Extraterrestrial Hydrocarbon Chemistry

    NASA Astrophysics Data System (ADS)

    Zhou, Li; Maity, Surajit; Abplanalp, Matt; Turner, Andrew; Kaiser, Ralf I.

    2014-07-01

    The chemical processing of ethylene ices (C2H4) by energetic electrons was investigated at 11 K to simulate the energy transfer processes and synthesis of new molecules induced by secondary electrons generated in the track of galactic cosmic ray particles. A combination of Fourier transform infrared spectrometry (solid state) and quadrupole mass spectrometry (gas phase) resulted in the identification of six hydrocarbon molecules: methane (CH4), the C2 species acetylene (C2H2), ethane (C2H6), the ethyl radical (C2H5), and—for the very first time in ethylene irradiation experiments—the C4 hydrocarbons 1-butene (C4H8) and n-butane (C4H10). By tracing the temporal evolution of the newly formed molecules spectroscopically online and in situ, we were also able to fit the kinetic profiles with a system of coupled differential equations, eventually providing mechanistic information, reaction pathways, and rate constants on the radiolysis of ethylene ices and the inherent formation of smaller (C1) and more complex (C2, C4) hydrocarbons involving carbon-hydrogen bond ruptures, atomic hydrogen addition processes, and radical-radical recombination pathways. We also discuss the implications of these results on the hydrocarbon chemistry on Titan's surface and on ice-coated, methane-bearing interstellar grains as present in cold molecular clouds such as TMC-1.

  18. Initial manufacturing performance of an actively controlled PBS resist development process

    NASA Astrophysics Data System (ADS)

    Novembre, Anthony E.; Tarascon, Regine G.; Thompson, Larry F.; Tang, Wallace T.; Tange, C. O.; Bostic, R. A.; Ahn, D. H.

    1993-03-01

    An improvement in the method used to fabricate 5 X 5 in2 -1 and 5x biased and unbiased optical masks is achieved by actively controlling the resist development step of the mask fabrication process. This method has been initially applied to a photomask process which utilizes poly(1-butene-co-sulfur dioxide)(PBS) resist as the pattern delineation material. Real-time targeting of resist feature dimensions is performed using a Laserlith Resist Thickness and Endpoint Controller which has been adapted to an Applied Process TechnologyR/Convac Model 915 resist processor. The controller monitors in real-time the one-step resist development process for a time period based on the measured development rate of the resist, the geometry and size of the targeted feature. After the resist is developed, the controller instructs the resist processor to continue onto the remaining steps in the processing cycle. The targeted resist features of initial product produced using this system have an average variation from targeted size of 0.04 micrometers and an average resist linewidth uniformity (3(sigma) ) of 0.04 micrometers . These results indicate that active control of this critical development step enables the resist feature dimensions to be within +/- 0.05 micrometers of their targeted size after completion of the post-development bake step.

  19. Catalytic conversion of cellulose to liquid hydrocarbon fuels by progressive removal of oxygen to facilitate separation processes and achieve high selectivities

    DOEpatents

    Dumesic, James A.; Ruiz, Juan Carlos Serrano; West, Ryan M.

    2012-04-03

    Described is a method to make liquid chemicals, such as functional intermediates, solvents, and liquid fuels from biomass-derived cellulose. The method is cascading; the product stream from an upstream reaction can be used as the feedstock in the next downstream reaction. The method includes the steps of deconstructing cellulose to yield a product mixture comprising levulinic acid and formic acid, converting the levulinic acid to .gamma.-valerolactone, and converting the .gamma.-valerolactone to pentanoic acid. Alternatively, the .gamma.-valerolactone can be converted to a mixture of n-butenes. The pentanoic acid so formed can be further reacted to yield a host of valuable products. For example, the pentanoic acid can be decarboxylated yield 1-butene or ketonized to yield 5-nonanone. The 5-nonanone can be hydrodeoxygenated to yield nonane, or 5-nonanone can be reduced to yield 5-nonanol. The 5-nonanol can be dehydrated to yield nonene, which can be dimerized to yield a mixture of C.sub.9 and C.sub.18 olefins, which can be hydrogenated to yield a mixture of alkanes. Alternatively, the nonene may be isomerized to yield a mixture of branched olefins, which can be hydrogenated to yield a mixture of branched alkanes. The mixture of n-butenes formed from .gamma.-valerolactone can also be subjected to isomerization and oligomerization to yield olefins in the gasoline, jet and Diesel fuel ranges.

  20. An extended hindered-rotor model with incorporation of Coriolis and vibrational-rotational coupling for calculating partition functions and derived quantities.

    PubMed

    Vansteenkiste, P; Van Neck, D; Van Speybroeck, V; Waroquier, M

    2006-01-28

    Large-amplitude motions, particularly internal rotations, are known to affect substantially thermodynamic functions and rate constants of reactions in which flexible molecules are involved. Up to now all methods for computing the partition functions of these motions rely on the Pitzer approximation of more than 50 years ago, in which the large-amplitude motion is treated in complete independence of the other (vibrational) degrees of freedom. In this paper an extended hindered-rotor model (EHR) is developed in which the vibrational modes, treated harmonically, are correctly separated from the large-amplitude motion and in which relaxation effects (the changes in the kinetic-energy matrix and potential curvature) are taken into account as one moves along the large-amplitude path. The model also relies on a specific coordinate system in which the Coriolis terms vanish at all times in the Hamiltonian. In this way an increased level of consistency between the various internal modes is achieved, as compared with the more usual hindered-rotor (HR) description. The method is illustrated by calculating the entropies and heat capacities on 1,3-butadiene and 1-butene (with, respectively, one and two internal rotors) and the rate constant for the addition reaction of a vinyl radical to ethene. We also discuss various variants of the one-dimensional hindered-rotor scheme existing in the literature and its relation with the EHR model. It is argued why in most cases the HR approach is already quite successful.

  1. Ruta montana L. leaf essential oil and extracts: characterization of bioactive compounds and suppression of crown gall disease

    PubMed Central

    Hammami, Inés; Smaoui, Slim; Hsouna, Anis Ben; Hamdi, Naceur; Triki, Mohamed Ali

    2015-01-01

    The aims of this study were to assess the antimicrobial efficacy of the leaf essential oil and the leaf extracts of R. montana against Botrytis cinerea, Fusarium oxysporum, Verticillium dahliae, Aspergillus oryzae and Fusarium solani. The oil (1.000 µg/disk) and the extracts (1.500 µg/disk) revealed a remarkable antifungal effect against the tested plant pathogenic fungi with a radial growth inhibition percentage of 40.0-80.0 % and 5.0-58.0 %, respectively along with their respective MIC values ranging from 100 to 1100 µg/mL and 250 to 3000 µg/mL. The oil had a strong detrimental effect on spore germination of all the tested plant pathogens along with the concentration as well as time-dependent kinetic inhibition of Fusarium oxysporum. Also, the oil exhibited a potent in vivo antifungal effect against Botrytis cinerea on tomato plants. Experiments carried out in plant revealed that the essential oil was slightly effective in suppression of gall formation induced by Agrobacterium tumefaciens on bitter almond. The results of this study indicate that the oil and extracts of R. montana leaves could become natural alternatives to synthetic fungicides to control certain important plant microbial diseases. The GC-MS analysis determined that 28 compounds, which represented 89.03 % of total oil, were present in the oil containing mainly 1-butene, methylcyclopropane, 2-butene and caryophyllene oxide. PMID:26417353

  2. Characteristics of volatile organic compounds from motorcycle exhaust emission during real-world driving

    NASA Astrophysics Data System (ADS)

    Tsai, Jiun-Horng; Huang, Pei-Hsiu; Chiang, Hung-Lung

    2014-12-01

    The number of motorcycles has increased significantly in Asia, Africa, Latin American and Europe in recent years due to their reasonable price, high mobility and low fuel consumption. However, motorcycles can emit significant amounts of air pollutants; therefore, the emission characteristics of motorcycles are an important consideration for the implementation of control measures for motorcycles in urban areas. Results of this study indicate that most volatile organic compound (VOC) emission factors were in the range of several decades mg/km during on-road driving. Toluene, isopentane, 1,2,4-trimethylbenzene, m,p-xylene, and o-xylene were the most abundant VOCs in motorcycle exhaust, with emission factors of hundreds mg/km. Motorcycle exhaust was 15.4 mg/km for 15 carbonyl species. Acetaldehyde, acetone, formaldehyde and benzaldehyde were the major carbonyl species, and their emission factors ranged from 1.4 to 3.5 mg/km 1,2,4-trimethylbenzene, m,p-xylene, 1-butene, toluene, o-xylene, 1,2,3-trimethylbenzene, propene, 1,3,5-trimethylbenzene, isoprene, m-diethylbenzene, and m-ethyltoluene were the main ozone formation potential (OFP) species, and their OFP was 200 mg-O3/km or higher.

  3. Reactive lattice oxygen sites for C sub 4 -hydrocarbon selective oxidation over. beta. -VOPO sub 4

    SciTech Connect

    Lashier, M.E.; Schrader, G.L. )

    1991-03-01

    The role of lattice oxygen species in the catalytic oxidation of n-butene to maleic anhydride has been investigated using {beta}-VOPO{sub 4} labeled with {sup 18}O. The catalyst was prepared by stoichiometric reaction of (VO){sub 2}P{sub 2}O{sub 7} with {sup 18}O{sub 2} using solid state preparation techniques. The {beta}-VOPO{sub 7/2} {sup 18}O{sub 1/2} was characterized using laser Raman and Fourier transform infrared spectroscopies: preferential incorporation at P-O-V sites was observed. A pulse reactor was used to react n-butane, 1-butene, 1,3-butadiene, furan, {gamma}-butyrolactone, and maleic anhydride with the catalyst in the absence of gas-phase O{sub 2}. Incorporation of {sup 18}O into the products was monitored by mass spectrometry. Specific lattice oxygen sites could be associated with the reaction pathways for selective or nonselective oxidation. The results of this study also indicate that the initial interaction of n-butane with {beta}-VOPO{sub 4} is fundamentally different from the initial interaction of olefins or oxygenated species. The approach used in this research-referred to as Isotopic Reactive-Site Mapping-is a potentially powerful method for probing the reactive lattice sites of other selective oxidation catalysts.

  4. Kinetics and characterization of bismuth molybdate catalysts. 1. A gradientless partial oxidation reactor

    SciTech Connect

    Burban, P.M.; Schuit, G.C.A.; Bicschoff, K.B. ); Koch, T.A. Du Pont Experimental Station, Wilmington, DE )

    1990-12-01

    A gradientless laboratory fixed bed reactor was designed for studying the partial oxidation of 1-butene to 1,3-butadiene over bismuth-molybdate catalysts. By dilution of the catalyst bed with inert silicon carbide, axial catalyst bed temperature gradients were routinely reduced to 2 K or less over the temperature range 650-740 K for the exothermic model reaction. A systematic experimental procedure was developed and used to show that potential transport 'disguises' did not significantly influence the intrinsic rate of butadiene formation measured under both integral and differential conditions. For one Bi{sub 2}MoO{sub 6} catalyst system, rate of butadiene formation data over the temperature range 700-740 K were fit to pseudo first-order (in butene) kinetics. Analytical solutions of the governing equations describing fixed bed reactor transport disguises for first-order catalytic reactions were used to confirm that the reactor operated in a near gradientless fashion, in agreement with experiment.

  5. The effect of rhenium, sulfur and alumina on the conversion of hydrocarbons over platinum single crystals: Surface science and catalytic studies

    SciTech Connect

    Kim, C.

    1992-04-01

    Conversion reactions of hydrocarbons over Pt-Re model catalyst surfaces modified by sulfur and alumina have been studied. A plasma deposition source has been developed to deposit Pt, Re, and Al on metal substrates variable coverage in ultrahigh vacuum without excessive heating. Conversion of n-hexane was performed over the Re-covered Pt and Pt-covered Re surfaces. The presence of the second metal increased hydrogenolysis activity of both Pt-Re surfaces. Addition of sulfur on the model Catalyst surfaces suppressed hydrogenolysis activity and increased the cyclization rate of n-hexane to methylcyclopentane over Pt-Re surfaces. Sulfiding also increased the dehydrogenation rate of cyclohexane to benzene Over Pt-Re surfaces. It has been proposed that the PtRe bimetallic catalysts show unique properties when combined with sulfur, and electronic interactions exist between platinum, rhenium and sulfur. Decomposition of hydrocarbons on the sulfur-covered Pt-Re surfaces supported that argument. For the conversion of 1-butene over the planar Pt/AlO{sub x}, the addition of Pt increased the selectivity of hydrogenation over isomerization.

  6. The effect of rhenium, sulfur and alumina on the conversion of hydrocarbons over platinum single crystals: Surface science and catalytic studies

    SciTech Connect

    Kim, C.

    1992-04-01

    Conversion reactions of hydrocarbons over Pt-Re model catalyst surfaces modified by sulfur and alumina have been studied. A plasma deposition source has been developed to deposit Pt, Re, and Al on metal substrates variable coverage in ultrahigh vacuum without excessive heating. Conversion of n-hexane was performed over the Re-covered Pt and Pt-covered Re surfaces. The presence of the second metal increased hydrogenolysis activity of both Pt-Re surfaces. Addition of sulfur on the model Catalyst surfaces suppressed hydrogenolysis activity and increased the cyclization rate of n-hexane to methylcyclopentane over Pt-Re surfaces. Sulfiding also increased the dehydrogenation rate of cyclohexane to benzene Over Pt-Re surfaces. It has been proposed that the PtRe bimetallic catalysts show unique properties when combined with sulfur, and electronic interactions exist between platinum, rhenium and sulfur. Decomposition of hydrocarbons on the sulfur-covered Pt-Re surfaces supported that argument. For the conversion of 1-butene over the planar Pt/AlO[sub x], the addition of Pt increased the selectivity of hydrogenation over isomerization.

  7. Evaluation of the acid properties of porous zirconium-doped and undoped silica materials

    SciTech Connect

    Fuentes-Perujo, D.; Santamaria-Gonzalez, J.; Merida-Robles, J.; Rodriguez-Castellon, E.; Jimenez-Lopez, A.; Maireles-Torres, P. . E-mail: maireles@uma.es; Moreno-Tost, R.

    2006-07-15

    A series of porous silica and Zr-doped silica molecular sieves, belonging to the MCM-41 and MSU families, were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N{sub 2} adsorption at 77 K. Their acid properties have been evaluated by NH{sub 3}-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FT-IR spectroscopy and the catalytic tests of isopropanol decomposition and isomerization of 1-butene. The acidity of purely siliceous solids were, in all cases, very low, while the incorporation of Zr(IV) into the siliceous framework produced an enhancement of the acidity. The adsorption of basic probe molecules and the catalytic behaviour revealed that Zr-doped MSU-type silica was more acidic than the analogous Zr-MCM-41 solid, with a similar Zr content. This high acidity observed in the case of Zr-doped silica samples is due to the presence of surface zirconium atoms with a low coordination, mainly creating Lewis acid sites. - Graphical abstract: The adsorption of basic probe molecules and the catalytic behaviour have revealed that MSU-type materials are more acidic than the analogous MCM-41 solids, mainly after the incorporation of zirconium into the silica framework.

  8. β-Hydride Elimination at Low-Coordinate Gold(III) Centers.

    PubMed

    Rekhroukh, Feriel; Estevez, Laura; Mallet-Ladeira, Sonia; Miqueu, Karinne; Amgoune, Abderrahmane; Bourissou, Didier

    2016-09-14

    This Article reports the first comprehensive study of β-hydride elimination at gold(III). The stability/fate of gold(III) alkyl species have been investigated experimentally and computationally. A series of well-defined cationic cyclometalated gold(III) alkyl complexes [(P,C)gold(III)(R)][NTf2] [(P,C) = 8-diisopropylphosphino-naphthyl; R = Me, nPr, nBu] have been synthesized and spectroscopically characterized. While the cationic gold(III) methyl derivative 3c is stable for days at room temperature, the gold(III) n-propyl and n-butyl complexes 3a,b readily undergo β-hydride elimination at low temperature to generate propylene and 2-butenes, respectively. The formation of internal olefins from the gold(III) n-butyl complex 3b shows that olefin isomerization takes place after β-hydride elimination. Computational studies indicate that this isomerization proceeds through a chain-walking mechanism involving a highly reactive gold(III) hydride intermediate and a sequence of β-hydride elimination/reinsertion into the Au-H bond. The reaction of the cationic gold(III) methyl complex 3c with ethylene was also explored. According to (1)H and (13)C NMR spectroscopy, a mixture of propylene, 1-butene, and 2-butenes is formed. DFT calculations provide detailed mechanistic insights and support the occurrence of migratory insertion of ethylene, β-hydride elimination, and olefin exchange at gold(III). PMID:27533923

  9. Combustion modeling and kinetic rate calculations for a stoichiometric cyclohexane flame. 1. Major reaction pathways.

    PubMed

    Zhang, Hongzhi R; Huynh, Lam K; Kungwan, Nawee; Yang, Zhiwei; Zhang, Shaowen

    2007-05-17

    The Utah Surrogate Mechanism was extended in order to model a stoichiometric premixed cyclohexane flame (P = 30 Torr). Generic rates were assigned to reaction classes of hydrogen abstraction, beta scission, and isomerization, and the resulting mechanism was found to be adequate in describing the combustion chemistry of cyclohexane. Satisfactory results were obtained in comparison with the experimental data of oxygen, major products and important intermediates, which include major soot precursors of C2-C5 unsaturated species. Measured concentrations of immediate products of fuel decomposition were also successfully reproduced. For example, the maximum concentrations of benzene and 1,3-butadiene, two major fuel decomposition products via competing pathways, were predicted within 10% of the measured values. Ring-opening reactions compete with those of cascading dehydrogenation for the decomposition of the conjugate cyclohexyl radical. The major ring-opening pathways produce 1-buten-4-yl radical, molecular ethylene, and 1,3-butadiene. The butadiene species is formed via beta scission after a 1-4 internal hydrogen migration of 1-hexen-6-yl radical. Cascading dehydrogenation also makes an important contribution to the fuel decomposition and provides the exclusive formation pathway of benzene. Benzene formation routes via combination of C2-C4 hydrocarbon fragments were found to be insignificant under current flame conditions, inferred by the later concentration peak of fulvene, in comparison with benzene, because the analogous species series for benzene formation via dehydrogenation was found to be precursors with regard to parent species of fulvene. PMID:17388269

  10. Measurement of proton transfer reaction rates in a microwave cavity discharge flowing afterglow

    NASA Astrophysics Data System (ADS)

    Brooke, George M., IV

    The reaction rate coefficients between the hydronium ion and the molecules ethene (C2H4), propene (C 3H6), 1-butene (C4H8) and hydrogen sulfide (H2S) were measured at 296 K. The measured reaction rates were compared to collision rates calculated using average dipole orientation (ADO) theory. Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is spatially separated from the flow tube, eliminating many of the problems inherent with the original FA devices. In addition to measuring reaction rate coefficients, the MCD-FA was shown to be an effective tool for measuring trace compounds in atmospheric air. This method has many advantages over current detection techniques since compounds can be detected in almost real time, large mass ranges can be scanned quickly, and repeated calibration is not required. Preliminary measurements were made of car exhaust and exhaled alveolar air. Car exhaust showed the presence of numerous hydrocarbons, such as butene, benzene and toluene while the exhaled alveolar air showed the presence of various volatile organic compounds such as methanol and acetone.

  11. A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol.

    PubMed

    Pavarelli, Giulia; Velasquez Ochoa, Juliana; Caldarelli, Aurora; Puzzo, Francesco; Cavani, Fabrizio; Dubois, Jean-Luc

    2015-07-01

    We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride. PMID:26073302

  12. Calculational and Experimental Investigations of the Pressure Effects on Radical - Radical Cross Combinations Reactions: C2H5 + C2H3

    NASA Technical Reports Server (NTRS)

    Fahr, Askar; Halpern, Joshua B.; Tardy, Dwight C.

    2007-01-01

    Pressure-dependent product yields have been experimentally determined for the cross-radical reaction C2H5 + C2H3. These results have been extended by calculations. It is shown that the chemically activated combination adduct, 1-C4H8*, is either stabilized by bimolecular collisions or subject to a variety of unimolecular reactions including cyclizations and decompositions. Therefore the "apparent" combination/disproportionation ratio exhibits a complex pressure dependence. The experimental studies were performed at 298 K and at selected pressures between about 4 Torr (0.5 kPa) and 760 Torr (101 kPa). Ethyl and vinyl radicals were simultaneously produced by 193 nm excimer laser photolysis of C2H5COC2H3 or photolysis of C2H3Br and C2H5COC2H5. Gas chromatograph/mass spectrometry/flame ionization detection (GC/MS/FID) were used to identify and quantify the final reaction products. The major combination reactions at pressures between 500 (66.5 kPa) and 760 Torr are (1c) C2H5 + C2H3 yields 1-butene, (2c) C2H5 + C2H5 yields n-butane, and (3c) C2H3 + C2H3 yields 1,3-butadiene. The major products of the disproportionation reactions are ethane, ethylene, and acetylene. At moderate and lower pressures, secondary products, including propene, propane, isobutene, 2-butene (cis and trans), 1-pentene, 1,4-pentadiene, and 1,5-hexadiene are also observed. Two isomers of C4H6, cyclobutene and/or 1,2-butadiene, were also among the likely products. The pressure-dependent yield of the cross-combination product, 1-butene, was compared to the yield of n-butane, the combination product of reaction (2c), which was found to be independent of pressure over the range of this study. The [ 1-C4H8]/[C4H10] ratio was reduced from approx.1.2 at 760 Torr (101 kPa) to approx.0.5 at 100 Torr (13.3 kPa) and approx.0.1 at pressures lower than about 5 Torr (approx.0.7 kPa). Electronic structure and RRKM calculations were used to simulate both unimolecular and bimolecular processes. The relative importance

  13. Polar organic marker compounds in atmospheric aerosols during the LBA-SMOCC 2002 biomass burning experiment in Rondônia, Brazil: sources and source processes, time series, diel variations and size distributions

    NASA Astrophysics Data System (ADS)

    Claeys, M.; Kourtchev, I.; Pashynska, V.; Vas, G.; Vermeylen, R.; Wang, W.; Cafmeyer, J.; Chi, X.; Artaxo, P.; Andreae, M. O.; Maenhaut, W.

    2010-04-01

    Measurements of polar organic marker compounds were performed on aerosols that were collected at a pasture site in the Amazon basin (Rondônia, Brazil) using a High-Volume dichotomous sampler (HVDS) and a Micro-Orifice Uniform Deposit Impactor (MOUDI). The samplings were conducted within the framework of the LBA-SMOCC (Large-Scale Biosphere Atmosphere Experiment in Amazônia - Smoke Aerosols, Clouds, Rainfall, and Climate: Aerosols From Biomass Burning Perturb Global and Regional Climate) campaign, which took place from 9 September till 14 November 2002, spanning the late dry season (biomass burning), the transition period, and the onset of the wet season (clean conditions). In the present study a more detailed discussion is presented compared to previous reports on the behavior of selected polar marker compounds, including: (a) levoglucosan, a tracer for biomass burning, (b) malic acid, a tracer for the oxidation of semivolatile carboxylic acids, (c) tracers for secondary organic aerosol (SOA) from isoprene, i.e., the 2-methyltetrols (2-methylthreitol and 2-methylerythritol) and the C5-alkene triols [2-methyl-1,3,4-trihydroxy-1-butene (cis and trans) and 3-methyl-2,3,4-trihydroxy-1-butene], and (d) sugar alcohols (arabitol, mannitol, and erythritol), tracers for fungal spores. The results obtained for levoglucosan are covered first with the aim to address its contrasting behavior with that of malic acid, the isoprene SOA tracers, and the fungal spore tracers. The tracer data are discussed taking into account new insights that recently became available into their stability and/or aerosol formation processes. During all three periods, levoglucosan was the most dominant identified organic species in the PM2.5 size fraction of the HVDS samples. In the dry period levoglucosan reached concentrations of up to 7.5 μg m-3 and exhibited diel variations with a nighttime prevalence. It was closely associated with the PM mass in the size-segregated samples and was mainly

  14. Competitive Low Pressure Oxygen Plasma Interactions with Different= Carbon-Carbon Double Bonds

    NASA Astrophysics Data System (ADS)

    Patiño, P.; Sifontes, A.; Gambús, G.

    1999-10-01

    Recently we have shown advances from reactions of O(^3P) with both, l ong-chain hydrocarbons and refinery residuum. The oxidation products of t he process, a mixture of alcohols, epoxides and carbonyl compounds, might have potential properties as additives in formulating fuels. This work s hows the results of the interactions of an oxygen plasma with double bond s, both olefin and aromatic, in the same compound. The reactions have bee n carried out by making the plasma, created by a high voltage glow discha rge, reach the low vapor pressure surface of liquid 4-phenyl-1-butene. Th is (3 mL) was cooled down to -45 ^oC in a glass reactor, applied power was 24 W, at an oxygen pressure of 20 Pa. Products were analyzed by IR, N MR and mass spectroscopies. Conversions were studied as a function of the reaction time, this ranging from 5 to 120 minutes. At short times the O( ^3P) atoms produced in the discharge only reacted with the alkene fra ction of the hydrocarbon, 4-phenyl-1,2-epoxibutane (52%) and 4-phenyl-bu tanal (48%) being the products. Reactions on the benzene ring were obser ved from about 30 minutes on, the corresponding phenols having being prod uced at ratios ortho:para:meta :: 4:1:0.7. At 120 minutes, the ol efin have been completely oxidized and a low fraction of the non-equivale nt two methylene groups have reacted to produce alcohols and ketones.

  15. On-board measurements of gaseous pollutant emission characteristics under real driving conditions from light-duty diesel vehicles in Chinese cities.

    PubMed

    Wang, Gang; Cheng, Shuiyuan; Lang, Jianlei; Li, Song; Tian, Liang

    2016-08-01

    A total of 15 light-duty diesel vehicles (LDDVs) were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hydrocarbons (HC) and nitrogen oxides (NOx) at different speeds, chemical species profiles and ozone formation potential (OFP) of volatile organic compounds (VOCs) emitted from diesel vehicles with different emission standards were analyzed. The results demonstrated that emission reductions of HC and NOx had been achieved as the control technology became more rigorous from Stage I to Stage IV. It was also found that the HC and NOx emissions and percentage of O2 dropped with the increase of speed, while the percentage of CO2 increased. The abundance of alkanes was significantly higher in diesel vehicle emissions, approximately accounting for 41.1%-45.2%, followed by aromatics and alkenes. The most abundant species were propene, ethane, n-decane, n-undecane, and n-dodecane. The maximum incremental reactivity (MIR) method was adopted to evaluate the contributions of individual VOCs to OFP. The results indicated that the largest contributors to O3 production were alkenes and aromatics, which accounted for 87.7%-91.5%. Propene, ethene, 1,2,4-trimethylbenzene, 1-butene, and 1,2,3-trimethylbenzene were the top five VOC species based on their OFP, and accounted for 54.0%-64.8% of the total OFP. The threshold dilution factor was applied to analyze the possibility of VOC stench pollution. The majority of stench components emitted from vehicle exhaust were aromatics, especially p-diethylbenzene, propylbenzene, m-ethyltoluene, and p-ethyltoluene.

  16. High throughput HPLC-ESI(-)-MS/MS methodology for mercapturic acid metabolites of 1,3-butadiene: Biomarkers of exposure and bioactivation.

    PubMed

    Kotapati, Srikanth; Esades, Amanda; Matter, Brock; Le, Chap; Tretyakova, Natalia

    2015-11-01

    1,3-Butadiene (BD) is an important industrial and environmental carcinogen present in cigarette smoke, automobile exhaust, and urban air. The major urinary metabolites of BD in humans are 2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene/1-(N-acetyl-L-cystein-S-yl)-2-hydroxybut-3-ene (MHBMA), 4-(N-acetyl-L-cystein-S-yl)-1,2-dihydroxybutane (DHBMA), and 4-(N-acetyl-L-cystein-S-yl)-1,2,3-trihydroxybutyl mercapturic acid (THBMA), which are formed from the electrophilic metabolites of BD, 3,4-epoxy-1-butene (EB), hydroxymethyl vinyl ketone (HMVK), and 3,4-epoxy-1,2-diol (EBD), respectively. In the present work, a sensitive high-throughput HPLC-ESI(-)-MS/MS method was developed for simultaneous quantification of MHBMA and DHBMA in small volumes of human urine (200 μl). The method employs a 96 well Oasis HLB SPE enrichment step, followed by isotope dilution HPLC-ESI(-)-MS/MS analysis on a triple quadrupole mass spectrometer. The validated method was used to quantify MHBMA and DHBMA in urine of workers from a BD monomer and styrene-butadiene rubber production facility (40 controls and 32 occupationally exposed to BD). Urinary THBMA concentrations were also determined in the same samples. The concentrations of all three BD-mercapturic acids and the metabolic ratio (MHBMA/(MHBMA+DHBMA+THBMA)) were significantly higher in the occupationally exposed group as compared to controls and correlated with BD exposure, with each other, and with BD-hemoglobin biomarkers. This improved high throughput methodology for MHBMA and DHBMA will be useful for future epidemiological studies in smokers and occupationally exposed workers.

  17. Characterizations of volatile organic compounds during high ozone episodes in Beijing, China.

    PubMed

    An, Jun-lin; Wang, Yue-si; Wu, Fang-kun; Zhu, Bin

    2012-04-01

    Air samples were collected in Beijing from June through August 2008, and concentrations of volatile organic compounds (VOCs) in those samples are here discussed. This sampling was performed to increase understanding of the distributions of their compositions, illustrate the overall characteristics of different classes of VOCs, assess the ages of air masses, and apportion sources of VOCs using principal compound analysis/absolute principal component scores (PCA/APCS). During the sampling periods, the relative abundance of the four classes of VOCs as determined by the concentration-based method was different from that determined by the reactivity approach. Alkanes were found to be most abundant (44.3-50.1%) by the concentration-based method, but aromatic compounds were most abundant (38.2-44.5%) by the reactivity approach. Aromatics and alkenes contributed most (73-84%) to the ozone formation potential. Toluene was the most abundant compound (11.8-12.7%) during every sampling period. When the maximum incremental reactivity approach was used, propene, toluene, m,p-xylene, 1-butene, and 1,2,4-trimethylbenzene were the five most abundant compounds during two sampling periods. X/B, T/B, and E/B ratios in this study were lower than those found in other cities, possibly due to the aging of the air mass at this site. Four components were extracted from application of PCA to the data. It was found that the contribution of vehicle exhaust to total VOCs accounted for 53% of VOCs, while emissions due to the solvent use contributed 33% of the total VOCs. Industrial sources contributed 3% and biogenic sources contributed 11%. The results showed that vehicle exhausts (i.e., unburned vehicle emissions + vehicle internal engine combustion) were dominant in VOC emissions during the experimental period. The solvent use made the second most significant contribution to ambient VOCs. PMID:21552987

  18. Gas-phase chemistry of bare and oxo-ligated protactinium ions: a contribution to a systematic understanding of actinide chemistry.

    PubMed

    Gibson, John K; Haire, Richard G

    2002-11-01

    Gas-phase chemistry of bare and oxo-ligated protactinium ions has been studied for the first time. Comparisons were made with thorium, uranium, and neptunium ion chemistry to further the systematic understanding of 5f elements. The rates of oxidation of Pa(+) and PaO(+) by ethylene oxide compared with those of the homologous uranium ions indicate that the first and second bond dissociation energies, BDE[Pa(+)-O] and BDE[OPa(+)-O], are approximately 800 kJ mol(-1). The relatively facile fluorination of Pa(+) to PaF(4)(+) by SF(6) is consistent with the high stability of the pentavalent oxidation state of Pa. Reactions with ethene, propene, 1-butene, and iso-butene revealed that Pa(+) is a very reactive metal ion. In analogy with U(+) chemistry, ethene was trimerized by Pa(+) to give PaC(6)H(6)(+). Reactions of Pa(+) with larger alkenes resulted in secondary and tertiary products not observed for U(+) or Np(+). The bare protactinium ion is significantly more reactive with organic substrates than are heavier actinide ions. The greatest difference between Pa and heavier actinide congeners was the exceptional dehydrogenation activity of PaO(+) with alkenes; UO(+) and NpO(+) were comparatively inert. The striking reactivity of PaO(+) is attributed to the distinctive electronic structure at the metal center in this oxide, which is considered to reflect the greater availability of the 5f electrons for participation in bonding, either directly or by promotion/hybridization with higher-energy valence orbitals.

  19. Gas-phase chemistry of bare and oxo-ligated protactinium ions: a contribution to a systematic understanding of actinide chemistry.

    PubMed

    Gibson, John K; Haire, Richard G

    2002-11-01

    Gas-phase chemistry of bare and oxo-ligated protactinium ions has been studied for the first time. Comparisons were made with thorium, uranium, and neptunium ion chemistry to further the systematic understanding of 5f elements. The rates of oxidation of Pa(+) and PaO(+) by ethylene oxide compared with those of the homologous uranium ions indicate that the first and second bond dissociation energies, BDE[Pa(+)-O] and BDE[OPa(+)-O], are approximately 800 kJ mol(-1). The relatively facile fluorination of Pa(+) to PaF(4)(+) by SF(6) is consistent with the high stability of the pentavalent oxidation state of Pa. Reactions with ethene, propene, 1-butene, and iso-butene revealed that Pa(+) is a very reactive metal ion. In analogy with U(+) chemistry, ethene was trimerized by Pa(+) to give PaC(6)H(6)(+). Reactions of Pa(+) with larger alkenes resulted in secondary and tertiary products not observed for U(+) or Np(+). The bare protactinium ion is significantly more reactive with organic substrates than are heavier actinide ions. The greatest difference between Pa and heavier actinide congeners was the exceptional dehydrogenation activity of PaO(+) with alkenes; UO(+) and NpO(+) were comparatively inert. The striking reactivity of PaO(+) is attributed to the distinctive electronic structure at the metal center in this oxide, which is considered to reflect the greater availability of the 5f electrons for participation in bonding, either directly or by promotion/hybridization with higher-energy valence orbitals. PMID:12401099

  20. Regioselectivity of the photochemical addition of phosphine to unsaturated hydrocarbons in the atmospheres of Jupiter and Saturn.

    PubMed

    Guillemin, J C; Le Serre, S; Lassalle, L

    1997-01-01

    Phosphine (PH3) has been observed in the atmospheres of Jupiter and Saturn. We have studied the regioselectivity in the gaseous phase of the photochemical addition of PH3 to propene 1, propadiene 2, propyne 3, 1,3-butadiene 4 and 1,3-butadiyne 5. The photolysis were performed at 185 and 254 nm. The volatile products formed in these reactions were characterized by 1H and 31P NMR. The n-propylphosphine 6 and the isopropylphosphine 7 were the major products observed in the photolysis of PH3 with propene. The allylphosphine 8 was obtained when most of the light was absorbed by propene. This allylphosphine was the main product formed in the photolysis of PH3 in the presence of propadiene; the methylvinylphosphine 10 being not detected in these experiments, the reaction presents a very high regioselectivity. When most of the light was absorbed by propadiene, the propargylphosphine 9 was also observed. The photolysis of PH3 in the presence of propyne led to the E- and Z-1-propenylphosphines 12a,b and small amounts of methylvinylphosphine 10. Even when most of the light was absorbed by propyne, the propargylphosphine 9 was not observed. The Z-1-butene-3-ynylphosphine 13a and a mixture of primary phosphines containing the E-and Z-2-butenylphosphines 14a,b were obtained as major products when 1,3-butadiyne and 1,3-butadiene respectively where photolyzed with PH3. A high regioselectivity was thus observed in the photolysis of PH3 with an alkyne or an allene but alkenes led to mixtures of products.

  1. Triarylphosphine Ligands with Hemilabile Alkoxy Groups. Ligands for Nickel(II)-Catalyzed Olefin Dimerization Reactions. Hydrovinylation of Vi-nylarenes, 1,3-Dienes, and Cycloisomerization of 1,6-Dienes

    PubMed Central

    Biswas, Souvagya; Zhang, Aibin; Raya, Balaram

    2014-01-01

    Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-, 2-benzyloxymethyl- or 2-benzyloxyethyl-phenyl moiety results in a set of simple ligands, which exhibit strikingly different behaviour in various nickel(II)-catalyzed olefin dimerization reactions. Complexes of ligands with 2-benzyloxyphenyl-, 2-benzyloxymethylphenyl-diphenylphosphine (L5 and L6 respectively) are most active for hydrovinylation (HV) of vinylarenes, with the former leading to extensive isomerization of the primary 3-aryl-1-butenes into the conjugated 2-aryl-2-butenes even at −55 °C. However, 2-benzyloxymethyl-substituted ligand L6 is slightly less active, leading up to quantitative yields of the primary products of HV at ambient temperature with no trace of isomerization, thus providing the best option for a practical synthesis of these compounds. In sharp contrast, hydrovinylation of a variety of 1,3-dienes is best catalyzed by nickel(II)-complexes of 2-benzyloxyphenyldiphenylphosphine, L5. The other two ligands, 2-benzyloxymethyl-(L6) and 2-benzyloxyethyl-diphenylphosphine (L7) are much less effective in the HV of 1,3-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other hydrovinylation reactions, is also uniquely effected by nickel(II)-complexes of L5, but not of L6 or L7. In an attempt to prepare authentic samples of the methylencyclohexane products, nickel(II)-complexes of N-heterocyclic carbene-ligands were examined. In sharp contrast to the phosphines, which give the methylenecyclopentanes, methylenecyclohexanes are the major products in the (N-heterocyclic carbene)nickel(II)-mediated reactions. PMID:25395919

  2. On the radiolysis of ethylene ices by energetic electrons and implications to the extraterrestrial hydrocarbon chemistry

    SciTech Connect

    Zhou, Li; Maity, Surajit; Abplanalp, Matt; Turner, Andrew; Kaiser, Ralf I.

    2014-07-20

    The chemical processing of ethylene ices (C{sub 2}H{sub 4}) by energetic electrons was investigated at 11 K to simulate the energy transfer processes and synthesis of new molecules induced by secondary electrons generated in the track of galactic cosmic ray particles. A combination of Fourier transform infrared spectrometry (solid state) and quadrupole mass spectrometry (gas phase) resulted in the identification of six hydrocarbon molecules: methane (CH{sub 4}), the C2 species acetylene (C{sub 2}H{sub 2}), ethane (C{sub 2}H{sub 6}), the ethyl radical (C{sub 2}H{sub 5}), and—for the very first time in ethylene irradiation experiments—the C4 hydrocarbons 1-butene (C{sub 4}H{sub 8}) and n-butane (C{sub 4}H{sub 10}). By tracing the temporal evolution of the newly formed molecules spectroscopically online and in situ, we were also able to fit the kinetic profiles with a system of coupled differential equations, eventually providing mechanistic information, reaction pathways, and rate constants on the radiolysis of ethylene ices and the inherent formation of smaller (C1) and more complex (C2, C4) hydrocarbons involving carbon-hydrogen bond ruptures, atomic hydrogen addition processes, and radical-radical recombination pathways. We also discuss the implications of these results on the hydrocarbon chemistry on Titan's surface and on ice-coated, methane-bearing interstellar grains as present in cold molecular clouds such as TMC-1.

  3. Mechanistic Analysis and Thermochemical Kinetic Simulation of the Pathways for Volatile Product Formation from Pyrolysis of Polystyrene, Especially of the Dimer

    SciTech Connect

    Poutsma, Marvin L

    2006-01-01

    Simulations of the initial distribution of volatiles from pyrolysis of polystyrene were based on propagation rate constants estimated by thermochemical kinetic procedures. The voluminous database exhibits a disturbing lack of consistency with respect to effects of conversion level, temperature, and reactor type. It therefore remains difficult to assign the true primary distribution of the major products, styrene, 2,4-diphenyl-1-butene (''dimer''), 2,4,6-triphenyl-1-hexene (''trimer''), 1,3-diphenylpropane, and toluene, and its dependence on conditions. Probable perturbations by secondary reactions and selective evaporation are considered. The rate constant for 1,3-hydrogen shift appears much too small to accommodate the commonly proposed ''back-biting'' mechanism for dimer formation. Dimer more likely arises by addition of benzyl radical to olefinic chain-ends, followed by {beta}-scission, although ambiguities remain in assigning rate constants for the addition and {beta}-scission steps. With this modification, the major products can be successfully associated with decay of the sec-benzylic chain-end radical. In contrast, the minimal formation of allylbenzene, 2,4-diphenyl-1-pentene, and 2,4,6-triphenyl-1-heptene suggests a minimal chain-propagating role for the prim chain-end radical. Compared with polyethylene, the much enhanced ''unzipping'' to form monomer from polystyrene and the more limited depth of ''back-biting'' into the chain arise from an enthalpy-driven acceleration of {beta}-scission coupled with a kinetically driven deceleration of intramolecular hydrogen transfer. In contrast, the greater ''unzipping'' of poly(isobutylene) compared with polyethylene is proposed to result from relief of steric strain.

  4. Yttrium-Assisted C-H and C-C Bond Activation of Ethylene Probed by Mass-Analyzed Threshold Ionization Spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Jong Hyun; Yang, Dong-Sheng

    2016-06-01

    The reaction between Y atom and ethylene (CH2=CH2) was performed in a laser-ablation supersonic molecular beam source. Y(C2H2), Y(C2H4), and Y(C4H6) were observed by time-of-flight mass spectrometry and investigated with mass-analyzed threshold ionization (MATI) spectroscopy and theoretical calculations. Y(C2H2) is formed by hydrogen elimination, Y(C2H4) by simple association, and La(C4H6) by C-C bond coupling and dehydrogenation. Both Y(C2H2) and Y(C2H4) have a C2v triangular structure with a C=C double bond in Y(C2H2) and a C-C single bond in Y(C2H4). Y(C4H6) has a five-membered metallacyclic structure (Cs) with Y binding to the two terminal carbon atoms of butene, which is the exactly same as that of Y(C4H6) formed in the Y + 1-butene reaction. For all three complexes, ionization has a small effect on the metal-carbon bond lengths because the rejected electron has basically a Y 5s character. The adiabatic ionization energies are measured to be 45679(5) wn for Y(C2H2), 45603(5) wn for Y(C2H4) and 43475(5) wn for Y(C4H6). The metal-ligand stretching frequencies of the three complexes are also measured from the MATI spectra.

  5. Insights into the Mechanism of Tandem Alkene Hydroformylation over a Nanostructured Catalyst with Multiple Interfaces.

    PubMed

    Su, Ji; Xie, Chenlu; Chen, Chen; Yu, Yi; Kennedy, Griffin; Somorjai, Gabor A; Yang, Peidong

    2016-09-14

    The concept of tandem catalysis, where sequential reactions catalyzed by different interfaces in single nanostructure give desirable product selectively, has previously been applied effectively in the production of propanal from methanol (via carbon monoxide and hydrogen) and ethylene via tandem hydroformylation. However, the underlying mechanism leading to enhanced product selectivity has remained elusive due to the lack of stable, well-defined catalyst suitable for in-depth comprehensive study. Accordingly, we present the design and synthesis of a three-dimensional (3D) catalyst CeO2-Pt@mSiO2 with well-defined metal-oxide interfaces and stable architecture and investigate the selective conversion of ethylene to propanal via tandem hydroformylation. The effective production of aldehyde through the tandem hydroformylation was also observed on propylene and 1-butene. A thorough study of the CeO2-Pt@mSiO2 under different reaction and control conditions reveals that the ethylene present for the hydroformylation step slows down initial methanol decomposition, preventing the accumulation of hydrogen (H2) and favoring propanal formation to achieve up to 80% selectivity. The selectivity is also promoted by the fact that the reaction intermediates produced from methanol decomposition are poised to directly undergo hydroformylation upon migration from one catalytic interface to another. This synergistic effect between the two sequential reactions and the corresponding altered reaction pathway, compared to the single-step reaction, constitute the key advantages of this tandem catalysis. Ultimately, this in-depth study unravels the principles of tandem catalysis related to hydroformylation and represents a key step toward the rational design of new heterogeneous catalysts. PMID:27585650

  6. Final report on EURAMET.QM-S6/1195: Bilateral comparison of liquefied hydrocarbon mixtures in constant pressure (piston) cylinders

    NASA Astrophysics Data System (ADS)

    Brown, Andrew S.; Downey, Michael L.; Milton, Martin J. T.; van der Veen, Adriaan M. H.; Zalewska, Ewelina T.; Li, Jianrong

    2013-01-01

    Traceable liquid hydrocarbon mixtures are required in order to underpin measurements of the composition and other physical properties of LPG (liquefied petroleum gas) and LNG (liquefied natural gas), thus meeting the needs of an increasingly large European industrial market. The development of traceable liquid hydrocarbon standards by National Measurement Institutes (NMIs) was still at a relatively early stage at the time this comparison was proposed in 2011. NPL and VSL, who were the only NMIs active in this area, had developed methods for the preparation and analysis of such standards in constant pressure (piston) cylinders, but neither laboratory had Calibration and Measurement Capabilities (CMCs) for these mixtures. This report presents the results of EURAMET 1195, the first comparison of liquid hydrocarbon mixtures between NMIs, which assessed the preparation and analytical capabilities of NPL and VSL for these mixtures. The comparison operated between August 2011 and January 2012. Each laboratory prepared a liquid hydrocarbon standard with nominally the same composition and these standards were exchanged for analysis. The results of the comparison show a good agreement between the laboratories' results and the comparison reference values for the six components with amount fractions greater than 1.0 cmol/mol (propane, propene, iso-butene, n-butane, iso-butane and 1-butene). Measurement of the three components with lower amount fractions (1,3-butadiene, iso-pentane and n-pentane) proved more challenging. In all but one case, the differences from the comparison reference values for these three components were greater than the expanded measurement uncertainty. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by EURAMET, according to the provisions of the CIPM Mutual

  7. Rich premixed laminar methane flames doped by light unsaturated hydrocarbons. II. 1,3-Butadiene

    SciTech Connect

    Gueniche, H.A.; Glaude, P.A.; Fournet, R.; Battin-Leclerc, F.

    2007-10-15

    In line with the study presented in Part I of this paper, the structure of a rich premixed laminar methane flame doped with 1,3-butadiene has been investigated. The flame contains 20.7% (molar) of methane, 31.4% of oxygen, and 3.3% of 1,3-butadiene, corresponding to an equivalence ratio of 1.8, and a C{sub 4}H{sub 6}/CH{sub 4} ratio of 16%. The flame has been stabilized on a burner at a pressure of 6.7 kPa using argon as dilutant, with a gas velocity at the burner of 36 cm/s at 333 K. The temperature ranged from 600 K close to the burner up to 2150 K. Quantified species included the usual methane C{sub 0}-C{sub 2} combustion products and 1,3-butadiene, but also propyne, allene, propene, propane, 1,2-butadiene, butynes, vinylacetylene, diacetylene, 1,3-pentadiene, 2-methyl-1,3-butadiene (isoprene), 1-pentene, 3-methyl-1-butene, benzene, and toluene. To model these new results, some improvements have been made to a mechanism previously developed in our laboratory for the reactions of C{sub 3}-C{sub 4} unsaturated hydrocarbons. The main reaction pathways of consumption of 1,3-butadiene and of formation of C{sub 6} aromatic species have been derived from flow rate analyses. In this case, the C{sub 4} route to benzene formation plays an important role in comparison to the C{sub 3} pathway. (author)

  8. Chemical dynamics in time and energy space

    SciTech Connect

    Myers, J.D.

    1993-04-01

    The development of a versatile picosecond ultraviolet/vacuum ultraviolet temporal spectrometer and its potential use for measuring internal energy redistribution in isolated molecules are described in detail. A detailed description of the double-pass Nd:YAG amplifier and the dye amplifiers is given with the pulse energies achieved in the visible, ultraviolet, and vacuum ultraviolet. The amplified visible pulses are shown to be of sub-picosecond duration and near transform limited. The instrument`s temporal response ({le}10 ps) is derived from an instrument limited measurement of the dissociation lifetime of methyl iodide at 266 nm. The methyl iodide experiment is used to discuss the various sources of noise and background signals that are intrinsic to this type of experiment. Non-time-resolved experiments measuring the branching ratio and kinetic energy distributions of products from the 193 nm photodissociation of cyclopentadiene and thiophene are presented. These studies were done using the molecular beam Photofragment Translational Spectroscopy (PTS) technique. The results from the cyclopentadiene experiment confirm that H atom elimination to yield the cyclopentadienyl radical is the dominant dissociation channel. A barrier of {ge}5 kcal/mol can be understood in terms of the delocalization of the radical electron of the cyclopentadienyl fragment. A concerted elimination yielding cyclopropene and acetylene was also observed and is proposed to occur via a bicyclo-[2.1.0]pent-2-ene intermediate. Two other channels, yielding acetylene plus the CH{sub 2}CHCH triplet carbene, and CH{sub 2} plus 1-buten-3-yne, are postulated to occur via ring opening. The implications of the experimental results for bulk thermal oxidation and pyrolysis models are discussed. The thiophene experiment shows six competing dissociation channels. The postulated intermediates for the various thiophene dissociation channels include bicyclo, ring opened, and possibly ring contracted forms.

  9. The chemistry of tributyl phosphate at elevated temperatures in the Plutonium Finishing Plant Process Vessels

    SciTech Connect

    Barney, G.S.; Cooper, T.D.

    1994-06-01

    Potentially violent chemical reactions of the tributyl phosphate solvent used by the Plutonium Finishing Plant at the Hanford Site were investigated. There is a small probability that a significant quantity of this solvent could be accidental transferred to heated process vessels and react there with nitric acid or plutonium nitrate also present in the solvent extraction process. The results of laboratory studies of the reactions show that exothermic oxidation of tributyl phosphate by either nitric acid or actinide nitrates is slow at temperatures expected in the heated vessels. Less than four percent of the tributyl phosphate will be oxidized in these vented vessels at temperatures between 125{degrees}C and 250{degrees}C because the oxidant will be lost from the vessels by vaporization or decomposition before the tributyl phosphate can be extensively oxidized. The net amounts of heat generated by oxidation with concentrated nitric acid and with thorium nitrate (a stand-in for plutonium nitrate) were determined to be about -150 and -220 joules per gram of tributyl phosphate initially present, respectively. This is not enough heat to cause violent reactions in the vessels. Pyrolysis of the tributyl phosphate occurred in these mixtures at temperatures of 110{degrees}C to 270{degrees}C and produced mainly 1-butene gas, water, and pyrophosphoric acid. Butene gas generation is slow at expected process vessel temperatures, but the rate is faster at higher temperatures. At 252{degrees}C the rate of butene gas generated was 0.33 g butene/min/g of tributyl phosphate present. The measured heat absorbed by the pyrolysis reaction was 228 J/g of tributyl phosphate initially present (or 14.5 kcal/mole of tributyl phosphate). Release of flammable butene gas into process areas where it could ignite appears to be the most serious safety consideration for the Plutonium Finishing Plant.

  10. Polar organic marker compounds in atmospheric aerosols: Determination, time series, size distributions and sources

    NASA Astrophysics Data System (ADS)

    Kourtchev, Ivan

    Terrestrial vegetation releases substantial amounts of reactive volatile organic compounds (VOCs; e.g., isoprene, monoterpenes) into the atmosphere. The VOCs can be rapidly photooxidized under conditions of high solar radiation, yielding products that can participate in new particle formation and growth processes above forests. This thesis focuses on the characterization, identification and quantification of oxidation products of biogenic VOC (BVOCs) as well as other species (tracer compounds) that provide information on aerosol sources and source processes. Atmospheric aerosols from various forested sites (i.e., Hyytiala, southern Finland; Rondonia, Brazil; K-Puszta, Hungary and Julich, Germany) were analyzed with Gas Chromotography/Mass Spectrometry (GC/MS) using analytical procedure that targets polar organic compounds. The study demonstrated that isoprene (i.e., 2-methyerythritol, 2-methylthreitol, 2-methylglyceric acid and C5-alkene triols (2-methyl-1,3,4-trihydroxy-l-butene (cis and trans) and 3 methyl-2,3,4-trihydroxy-1-butene)) and monoterpene (pinic acid, norpinic acid, 3-hydroxyglutaric acid and 3-methyl-1,2,3-butanetricarboxylic acid) oxidation products were present in substantial concentrations in atmospheric aerosols suggesting that oxidation of BVOC from the vegetation is an important process in all studied sites. On the other hand, presence of levoglucosan, biomass burning marker, especially in Amazonian rain forest site at Rondonia, Brazil, pointed that all sites were affected by anthropogenic activities, namely biomass burning. Other identified compounds included plyols, arabitol, mannitol and erythritol, which are marker compounds for fungal spores and monosacharides, glucose and fructose, markers for plant polens. Temporal variations as well as mass size distributions of the detected species confirmed the possible formation mechanisms of marker compounds.

  11. Cytotoxic evaluation of volatile oil from Descurainia sophia seeds on MCF-7 and HeLa cell lines

    PubMed Central

    Khodarahmi, E.; Asghari, G.H.; Hassanzadeh, F.; Mirian, M.; Khodarahmi, G.A.

    2015-01-01

    Descurainia sophia is a plant widely distributed and used as folk medicine throughout the world. Different extracts of aerial parts and seeds of this plant have been shown to inhibit the growth of different cancer cell lines in vitro. In this study, cytotoxic activity of D. sophia seed volatile oil was evaluated. D. sophia seed powder was mixed with distilled water and left at 25 °C for 17 h (E1), 23 h (E2) and 28 h (E3) to autolyse. Then, the volatile fractions of E1, E2, and E3 were collected after steam distillation for 3 h. Cytotoxic effects of the volatile oils alone or in combination with doxorubicin (mixture of E1 or E2 at 50 μg/ml or E1 at 100 μg/ml with doxorubicin at 0.1, 1, 10 μM) against MCF-7 cell line were determined using MTT assay. Cytotoxic effect of E1 volatile oil was also determined on HeLa cell line. The results indicated that 1-buten-4-isothiocyanate was the major isothiocyanate found in the volatile oils. The results of cytotoxic evaluations showed that volatile constituents were more toxic on MCF-7 cells with IC50< 100 μg/ml than HeLa cells with IC50> 100 μg/ml. No significant differences were observed between cytotoxic activities of E1, E2 and E3 on MCF-7 cell line. Concomitant use of E1 and E2 (50 μg/ml) with doxurubicin (1 μM) significantly reduced the viability of MCF-7 cells compared to the negative control, doxorubicin alone, or each volatile fraction. The same result was obtained on HeLa cells, when E1 (100 μg/ml) was concurrently used with doxorubicin (1 μM). PMID:26487894

  12. Observation and Analysis of Polymer Crystal Structures at the Stem Level. Implications Regarding Polymer Crystallization Processes.

    NASA Astrophysics Data System (ADS)

    Lotz, Bernard

    2003-03-01

    The building element of chain folded polymer crystals is the individual stem that spans the lamellar thickness. For chiral but racemic helical polymers such as polyolefins (e.g. isotactic and syndiotactic polypropylene and poly(1-butene)), stems can be right- or left-handed helices. These polymers can exist in various crystal polymorphs that are either "racemic" or "chiral" (made of both, or of only one helical hand). Upon crystallization, each stem has a conformational "choice", but must adapt to the crystal structure and, once crystallized, is characterized by a "conformational tag" (right or left hand). Various means exist to determine or observe helical hands in polyolefin lamellae: Atomic Force Microscopy on epitaxially crystallized samples, or, for the alpha phase of isotactic polypropylene, analysis of its specific lamellar branching. These observations and analyses indicate that the helical hand of stems is tightly determined by the substrate or growth face topography, i.e. indicate that the depositing stem probes and adapts to the surface structure prior to successful attachment. This "post-mortem" analysis of the crystal structure and stem chirality emphasizes the "sequential" nature of the growth process (successive attachment of individual stems). It is in line with early views on polymer crystallization. It is at variance with recently introduced models or scenarios that assume either some pre-ordering of the polymer melt as a result of spinodal decomposition and/or accretion of polymer chains in pseudo-crystalline bundles followed by (solid state) reorganization of the bundles to generate fully grown lamellae.

  13. Use of ferric sulfate: acid media for the desulfurization of model compounds of coal. [Dibenzothiophene, diphenyl sulfide, di-n-butyl sulfide

    SciTech Connect

    Clary, L.R.; Vermeulen, T.; Lynn, S.

    1980-12-01

    The objective of this work has been to investigate the ability of ferric sulfate-acid leach systems to oxidize the sulfur in model compounds of coal. Ferric iron-acid leach systems have been shown to be quite effective at removal of inorganic sulfur in coal. In this study, the oxidative effect of ferric iron in acid-leach systems was studied using dibenzothiophene, diphenyl sulfide, and di-n-butyl sulfide as models of organic sulfur groups in coal. Nitrogen and oxygen, as well as various transition metal catalysts and oxidants, were utilized in this investigation. Dibenzothiophene was found to be quite refractory to oxidation, except in the case where metavanadate was added, where it appears that 40% oxidation to sulfone could have occurred per hour at 150/sup 0/C and mild oxygen pressure. Diphenyl sulfide was selectively oxidized to sulfoxide and sulfone in an iron and oxygen system. Approximately 15% conversion to sulfone occurred per hour under these conditions. Some of the di-n-butyl sulfide was cracked to 1-butene and 1-butanethiol under similar conditions. Zinc chloride and ferric iron were used at 200/sup 0/C in an attempt to desulfonate dibenzothiophene sulfone, diphenyl sulfone, and di-n-butyl sulfone. Di-n-butyl sulfone was completely desulfurized on one hour and fragmented to oxidized parafins, while dibenzothiophene sulfone and diphenyl sulfone were unaffected. These results suggest that an iron-acid leach process could only selectively oxidize aryl sulfides under mild conditions, representing only 20% of the organic sulfur in coal (8% of the total sulfur). Removal through desulfonation once selective sulfur oxidation had occurred was only demonstrated for alkyl sulfones, with severe oxidation of the fragmented paraffins also occurring in one hour.

  14. On-board measurements of gaseous pollutant emission characteristics under real driving conditions from light-duty diesel vehicles in Chinese cities.

    PubMed

    Wang, Gang; Cheng, Shuiyuan; Lang, Jianlei; Li, Song; Tian, Liang

    2016-08-01

    A total of 15 light-duty diesel vehicles (LDDVs) were tested with the goal of understanding the emission factors of real-world vehicles by conducting on-board emission measurements. The emission characteristics of hydrocarbons (HC) and nitrogen oxides (NOx) at different speeds, chemical species profiles and ozone formation potential (OFP) of volatile organic compounds (VOCs) emitted from diesel vehicles with different emission standards were analyzed. The results demonstrated that emission reductions of HC and NOx had been achieved as the control technology became more rigorous from Stage I to Stage IV. It was also found that the HC and NOx emissions and percentage of O2 dropped with the increase of speed, while the percentage of CO2 increased. The abundance of alkanes was significantly higher in diesel vehicle emissions, approximately accounting for 41.1%-45.2%, followed by aromatics and alkenes. The most abundant species were propene, ethane, n-decane, n-undecane, and n-dodecane. The maximum incremental reactivity (MIR) method was adopted to evaluate the contributions of individual VOCs to OFP. The results indicated that the largest contributors to O3 production were alkenes and aromatics, which accounted for 87.7%-91.5%. Propene, ethene, 1,2,4-trimethylbenzene, 1-butene, and 1,2,3-trimethylbenzene were the top five VOC species based on their OFP, and accounted for 54.0%-64.8% of the total OFP. The threshold dilution factor was applied to analyze the possibility of VOC stench pollution. The majority of stench components emitted from vehicle exhaust were aromatics, especially p-diethylbenzene, propylbenzene, m-ethyltoluene, and p-ethyltoluene. PMID:27521933

  15. Characteristics of volatile organic compounds (VOCs) emitted from a petroleum refinery in Beijing, China

    NASA Astrophysics Data System (ADS)

    Wei, Wei; Cheng, Shuiyuan; Li, Guohao; Wang, Gang; Wang, Haiyan

    2014-06-01

    This study made a field VOCs (volatile organic compounds) measurement for a petroleum refinery in Beijing by determining 56 PAMS VOCs, which are demanded for photochemical assessment in US, and obtained the characteristics of VOCs emitted from the whole refinery and from its inner main devices. During the monitoring period, this refinery brought about an average increase of 61 ppbv in the ambient TVOCs (sum of the PAMS VOCs) at the refinery surrounding area, while the background of TVOCs there was only 10-30 ppbv. In chemical profile, the VOCs emitted from the whole refinery was characteristic by isobutane (8.7%), n-butane (7.9%), isopentane (6.3%), n-pentane (4.9%%), n-hexane (7.6%), C6 branched alkanes (6.0%), propene (12.7%), 1-butene (4.1%), benzene (7.8%), and toluene (5.9%). On the other hand, the measurement for the inner 5 devices, catalytic cracking units (CCU2 and CCU3), catalytic reforming unit (CRU), tank farm (TF), and wastewater treatment(WT), revealed the higher level of VOCs pollutions (about several hundred ppbv of TVOCs), and the individual differences in VOCs chemical profiles. Based on the measured speciated VOCs data at the surrounding downwind area, PMF receptor model was applied to identify the VOCs sources in the refinery. Then, coupling with the VOCs chemical profiles measured at the device areas, we concluded that CCU1/3 contributes to 25.9% of the TVOCs at the surrounding downwind area by volume, followed by CCU2 (24.7%), CRU (18.9%), TF (18.3%) and WT (12.0%), which was accordant with the research of US EPA (2008). Finally, ozone formation potentials of the 5 devices were also calculated by MIR technique, which showed that catalytic cracking units, accounting for about 55.6% to photochemical ozone formation, should be given the consideration of VOCs control firstly.

  16. SmoXYB1C1Z of Mycobacterium sp. Strain NBB4: a Soluble Methane Monooxygenase (sMMO)-Like Enzyme, Active on C2 to C4 Alkanes and Alkenes

    PubMed Central

    Martin, Kiri E.; Ozsvar, Jazmin

    2014-01-01

    Monooxygenase (MO) enzymes initiate the aerobic oxidation of alkanes and alkenes in bacteria. A cluster of MO genes (smoXYB1C1Z) of thus-far-unknown function was found previously in the genomes of two Mycobacterium strains (NBB3 and NBB4) which grow on hydrocarbons. The predicted Smo enzymes have only moderate amino acid identity (30 to 60%) to their closest homologs, the soluble methane and butane MOs (sMMO and sBMO), and the smo gene cluster has a different organization from those of sMMO and sBMO. The smoXYB1C1Z genes of NBB4 were cloned into pMycoFos to make pSmo, which was transformed into Mycobacterium smegmatis mc2-155. Cells of mc2-155(pSmo) metabolized C2 to C4 alkanes, alkenes, and chlorinated hydrocarbons. The activities of mc2-155(pSmo) cells were 0.94, 0.57, 0.12, and 0.04 nmol/min/mg of protein with ethene, ethane, propane, and butane as substrates, respectively. The mc2-155(pSmo) cells made epoxides from ethene, propene, and 1-butene, confirming that Smo was an oxygenase. Epoxides were not produced from larger alkenes (1-octene and styrene). Vinyl chloride and 1,2-dichloroethane were biodegraded by cells expressing Smo, with production of inorganic chloride. This study shows that Smo is a functional oxygenase which is active against small hydrocarbons. M. smegmatis mc2-155(pSmo) provides a new model for studying sMMO-like monooxygenases. PMID:25015887

  17. Cl atom initiated oxidation of 1-alkenes under atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Walavalkar, M.; Sharma, A.; Alwe, H. D.; Pushpa, K. K.; Dhanya, S.; Naik, P. D.; Bajaj, P. N.

    2013-03-01

    In view of the importance of the oxidation pathways of alkenes in the troposphere, and the significance of Cl atom as an oxidant in marine boundary layer (MBL) and polluted industrial atmosphere, the reactions of four 1-alkenes (C6-C9) with Cl atoms are investigated. The rate coefficients at 298 K are measured to be (4.0 ± 0.5), (4.4 ± 0.7), (5.5 ± 0.9) and (5.9 ± 1.7) × 10-10 cm3 molecule-1 s-1 for 1-hexene, 1-heptene, 1-octene and 1-nonene, respectively. The quoted errors include the experimental 2σ, along with the error in the reference rate coefficients. From the systematic increase in the rate coefficients with the number of carbon atoms, an approximate value for the average rate coefficient for hydrogen abstraction per CH2 group in alkenes is estimated to be (4.9 ± 0.3) × 10-11 cm3 molecule-1 s-1. Based on these rate coefficients, the contribution of Cl atom reactions towards the degradation of these molecules is found to be comparable to that of OH radical reactions, under MBL conditions. The products identified in gas phase indicate that Cl atom addition occurs mainly at the terminal carbon, leading to the formation of 1-chloro-2-ketones and 1-chloro-2-ols. The major gas phase products from the alkenyl radicals (formed by H atom abstraction) are different positional isomers of long chain enols and enones. A preference for dissociation leading to an allyl radical, resulting in aldehydes, lower by three carbon atoms, is indicated. The observed relative yields suggest that in general, the increased contribution of the reactions of Cl atoms towards degradation of 1-alkenes in NOx free air does not result in an increase in the generation of small aldehydes (carbon number < 4), including chloroethanal, as compared to that in the reaction of 1-butene.

  18. Characterization and catalytic function of Re/sup 0/ and Re/sup 4 +/ in Re/Al/sub 2/O/sub 3/ and PtRe/Al/sub 2/O/sub 3/ catalysts

    SciTech Connect

    Nacheff, M.S.; Kraus, L.S.; Ichikawa, M.; Hoffman, B.M.; Butt, J.B.; Sachtler, W.M.H.

    1987-07-01

    Electron spin resonance (ESR) spectroscopy and CO adsorption measurements have shown that Re/sup 0/ and Re/sup 4 +/ species coexist on the surface of reduced 0.2 wt% Re/Al/sub 2/O/sub 3/ and 0.3-0.2 wt% Pt-Re/Al/sub 2/O/sub 3/ catalysts. The catalysts were prepared by incipient wetness impregnation with metallic salt precursors, calcined in air at 500/sup 0/C, and dried in He at 500/sup 0/C prior to reduction. The Re/sup 4 +/ species, which is stabilized by the Al/sub 2/O/sub 3/ and resists reduction up to 500/sup 0/C, yields an ESR signal which exhibits hyperfine splitting and accounts for less than 20% of the total Re in Re/Al/sub 2/O/sub 3/ and less than 10% of the Re in PtRe/Al/sub 2/O/sub 3/. This species does not chemisorb CO but interacts weakly with O/sub 2/. The Re/sup 0/ does not give rise to a resonance signal, but adsorbs CO strongly. The double bond shift (DBS) of 1-pentene, hydrogenation of 1-pentene, and the skeletal isomerization (SI) of 3,3-dimethyl-1-butene were tested using mild reaction conditions. The results indicate that Re/sup 4 +/ slightly enhances the Broensted acidity in Re/Al/sub 2/O/sub 3/, although this effect is negligible in comparison with the acidity induced by Cl/sup -/ ions. The Re/sup 0/ sites are very active for olefin hydrogenation; however, after presulfiding the Re/Al/sub 2/O/sub 3/, this hydrogenation activity is drastically lowered, but the DBS activity is still high which indicates that surface Re-S species are active for the DBS at the conditions employed. 46 references.

  19. Characterization and Dynamics of Substituted Ruthenacyclobutanes Relevant to the Olefin Cross-Metathesis Reaction

    PubMed Central

    Blake, Garrett; VanderVelde, David G.; Grubbs, Robert H.

    2011-01-01

    The reaction of the phosphonium alkylidene [(H2IMes)RuCl2=CHP(Cy)3)]+ BF4– with propene, 1-butene, and 1-hexene at –45 °C affords various substituted, metathesis-active ruthenacycles. These metallacycles were found to equilibrate over extended reaction times in response to decreases in ethylene concentrations, which favored increased populations of α-monosubstituted and α,α’-disubstituted (both cis and trans) ruthenacycles. On an NMR timescale, rapid chemical exchange was found to preferentially occur between the β-hydrogens of the cis and trans stereoisomers prior to olefin exchange. Exchange on an NMR timescale was also observed between the α- and β-methylene groups of the monosubstituted ruthenacycle (H2IMes)Cl2Ru(CHRCH2CH2) (R = CH3, CH2CH3, (CH2)3CH3). EXSY NMR experiments at –87 °C were used to determine the activation energies for both of these exchange processes. In addition, new methods have been developed for the direct preparation of metathesis-active ruthenacyclobutanes via the protonolysis of dichloro(1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)(benzylidene) bis(pyridine)ruthenium(II) and its 3-bromopyridine analog. Using either trifluoroacetic acid or silica-bound toluenesulfonic acid as the proton source, the ethylene-derived ruthenacyclobutane (H2IMes)Cl2Ru(CH2CH2CH2) was observed in up to 98% yield via NMR at –40 °C. On the basis of these studies, mechanisms accounting for the positional and stereochemical exchange within ruthenacyclobutanes are proposed, as well as the implications of these dynamics towards olefin metathesis catalyst and reaction design are described. PMID:21452876

  20. ANALYSIS OF VAPORS FROM METHYLENE CHLORIDE EXTRACTS OF NUCLEAR GRADE HEPA FILTER FIBERGLASS SAMPLES

    SciTech Connect

    FRYE JM; ANASTOS HL; GUTIERREZ FC

    2012-06-07

    While several organic compounds were detected in the vapor samples used in the reenactment of the preparation of mounts from the extracts of nuclear grade high-efficiency particulate air filter fiberglass samples, the most significant species present in the samples were methylene chloride, phenol, phenol-d6, and 2-fluorophenol. These species were all known to be present in the extracts, but were expected to have evaporated during the preparation of the mounts, as the mounts appeared to be dry before any vapor was collected. These species were present at the following percentages of their respective occupational exposure limits: methylene chloride, 2%; phenol, 0.4%; and phenol-d6, 0.6%. However, there is no established limit for 2-fluorophenol. Several other compounds were detected at low levels for which, as in the case of 2-fluorophenol, there are no established permissible exposure limits. These compounds include 2-chlorophenol; N-nitroso-1-propanamine; 2-fluoro-1,1{prime}-biphenyl; 1,2-dihydroacenaphthylene; 2,5-cyclohexadiene-1,4-dione,2,6-bis(1,1-dimethylethyl); trimethyl oxirane; n-propylpropanamine; 2-(Propylamino)ethanol; 4-methoxy-1-butene; 6-methyl-5-hepten-2-one; and 3,4-dimethylpyridine. Some of these were among those added as surrogates or spike standards as part ofthe Advanced Technologies and Laboratories International, Inc. preparation ofthe extract of the HEPA filter media and are indicated as such in the data tables in Section 2, Results; other compounds found were not previously known to be present. The main inorganic species detected (sulfate, sodium, and sulfur) are also consistent with species added in the preparation of the methylene chloride extract of the high-efficiency particulate air sample.

  1. Bis-butanediol-mercapturic acid (bis-BDMA) as a urinary biomarker of metabolic activation of butadiene to its ultimate carcinogenic species

    PubMed Central

    Tretyakova, Natalia Y.

    2014-01-01

    Human carcinogen 1,3-butadiene (BD) undergoes metabolic activation to 3,4-epoxy-1-butene (EB), hydroxymethylvinyl ketone (HMVK), 3,4-epoxy-1,2-butanediol (EBD) and 1,2,3,4-diepoxybutane (DEB). Among these, DEB is by far the most genotoxic metabolite and is considered the ultimate carcinogenic species of BD. We have shown previously that BD-exposed laboratory mice form 8- to 10-fold more DEB–DNA adducts than rats exposed at the same conditions, which may be responsible for the enhanced sensitivity of mice to BD-mediated cancer. In the present study, we have identified 1,4-bis-(N-acetyl-l-cystein-S-yl)butane-2,3-diol (bis-BDMA) as a novel DEB-specific urinary biomarker. Isotope dilution high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry was employed to quantify bis-BDMA and three other BD-mercapturic acids, 2-(N-acetyl-l-cystein-S-yl)-1-hydroxybut-3-ene/1-(N-acetyl-l-cystein-S-yl)-2-hydroxy-but-3-ene (MHBMA, from EB), 4-(N-acetyl-l-cystein-S-yl)-1,2-dihydroxybutane (DHBMA, from HMVK) and 4-(N-acetyl-l-cystein-S-yl)-1,2,3-trihydroxybutane (THBMA, from EBD), in urine of confirmed smokers, occupationally exposed workers and BD-exposed laboratory rats. Bis-BDMA was formed in a dose-dependent manner in urine of rats exposed to 0–200 p.p.m. BD by inhalation, although it was a minor metabolite (1%) as compared with DHBMA (47%) and THBMA (37%). In humans, DHBMA was the most abundant BD-mercapturic acid excreted (93%), followed by THBMA (5%) and MHBMA (2%), whereas no bis-BDMA was detected. These results reveal significant differences in metabolism of BD between rats and humans. PMID:24531806

  2. SmoXYB1C1Z of Mycobacterium sp. strain NBB4: a soluble methane monooxygenase (sMMO)-like enzyme, active on C2 to C4 alkanes and alkenes.

    PubMed

    Martin, Kiri E; Ozsvar, Jazmin; Coleman, Nicholas V

    2014-09-01

    Monooxygenase (MO) enzymes initiate the aerobic oxidation of alkanes and alkenes in bacteria. A cluster of MO genes (smoXYB1C1Z) of thus-far-unknown function was found previously in the genomes of two Mycobacterium strains (NBB3 and NBB4) which grow on hydrocarbons. The predicted Smo enzymes have only moderate amino acid identity (30 to 60%) to their closest homologs, the soluble methane and butane MOs (sMMO and sBMO), and the smo gene cluster has a different organization from those of sMMO and sBMO. The smoXYB1C1Z genes of NBB4 were cloned into pMycoFos to make pSmo, which was transformed into Mycobacterium smegmatis mc(2)-155. Cells of mc(2)-155(pSmo) metabolized C2 to C4 alkanes, alkenes, and chlorinated hydrocarbons. The activities of mc(2)-155(pSmo) cells were 0.94, 0.57, 0.12, and 0.04 nmol/min/mg of protein with ethene, ethane, propane, and butane as substrates, respectively. The mc(2)-155(pSmo) cells made epoxides from ethene, propene, and 1-butene, confirming that Smo was an oxygenase. Epoxides were not produced from larger alkenes (1-octene and styrene). Vinyl chloride and 1,2-dichloroethane were biodegraded by cells expressing Smo, with production of inorganic chloride. This study shows that Smo is a functional oxygenase which is active against small hydrocarbons. M. smegmatis mc(2)-155(pSmo) provides a new model for studying sMMO-like monooxygenases. PMID:25015887

  3. High throughput HPLC-ESI(-)-MS/MS methodology for mercapturic acid metabolites of 1,3-butadiene: Biomarkers of exposure and bioactivation.

    PubMed

    Kotapati, Srikanth; Esades, Amanda; Matter, Brock; Le, Chap; Tretyakova, Natalia

    2015-11-01

    1,3-Butadiene (BD) is an important industrial and environmental carcinogen present in cigarette smoke, automobile exhaust, and urban air. The major urinary metabolites of BD in humans are 2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene/1-(N-acetyl-L-cystein-S-yl)-2-hydroxybut-3-ene (MHBMA), 4-(N-acetyl-L-cystein-S-yl)-1,2-dihydroxybutane (DHBMA), and 4-(N-acetyl-L-cystein-S-yl)-1,2,3-trihydroxybutyl mercapturic acid (THBMA), which are formed from the electrophilic metabolites of BD, 3,4-epoxy-1-butene (EB), hydroxymethyl vinyl ketone (HMVK), and 3,4-epoxy-1,2-diol (EBD), respectively. In the present work, a sensitive high-throughput HPLC-ESI(-)-MS/MS method was developed for simultaneous quantification of MHBMA and DHBMA in small volumes of human urine (200 μl). The method employs a 96 well Oasis HLB SPE enrichment step, followed by isotope dilution HPLC-ESI(-)-MS/MS analysis on a triple quadrupole mass spectrometer. The validated method was used to quantify MHBMA and DHBMA in urine of workers from a BD monomer and styrene-butadiene rubber production facility (40 controls and 32 occupationally exposed to BD). Urinary THBMA concentrations were also determined in the same samples. The concentrations of all three BD-mercapturic acids and the metabolic ratio (MHBMA/(MHBMA+DHBMA+THBMA)) were significantly higher in the occupationally exposed group as compared to controls and correlated with BD exposure, with each other, and with BD-hemoglobin biomarkers. This improved high throughput methodology for MHBMA and DHBMA will be useful for future epidemiological studies in smokers and occupationally exposed workers. PMID:25727266

  4. High-temperature oxidation chemistry of n-butanol--experiments in low-pressure premixed flames and detailed kinetic modeling.

    PubMed

    Hansen, N; Harper, M R; Green, W H

    2011-12-01

    An automated reaction mechanism generator is used to develop a predictive, comprehensive reaction mechanism for the high-temperature oxidation chemistry of n-butanol. This new kinetic model is an advancement of an earlier model, which had been extensively tested against earlier experimental data (Harper et al., Combust. Flame, 2011, 158, 16-41). In this study, the model's predictive capabilities are improved by targeting isomer-resolved quantitative mole fraction profiles of flame species in low-pressure flames. To this end, a total of three burner-stabilized premixed flames are isomer-selectively analyzed by flame-sampling molecular-beam time-of-flight mass spectrometry using photoionization by tunable vacuum-ultraviolet synchrotron radiation. For most species, the newly developed chemical kinetic model is capable of accurately reproducing the experimental trends in these flames. The results clearly indicate that n-butanol is mainly consumed by H-atom abstraction with H, O, and OH, forming predominantly the α-C(4)H(9)O radical (CH(3)CH(2)CH(2)˙CHOH). Fission of C-C bonds in n-butanol is only predicted to be significant in a similar, but hotter flame studied by Oßwald et al. (Combust. Flame, 2011, 158, 2-15). The water-elimination reaction to 1-butene is found to be of no importance under the premixed conditions studied here. The initially formed isomeric C(4)H(9)O radicals are predicted to further oxidize by reacting with H and O(2) or to decompose to smaller fragments via β-scission. Enols are detected experimentally, with their importance being overpredicted by the model. PMID:21993635

  5. Characterizations of volatile organic compounds during high ozone episodes in Beijing, China.

    PubMed

    An, Jun-lin; Wang, Yue-si; Wu, Fang-kun; Zhu, Bin

    2012-04-01

    Air samples were collected in Beijing from June through August 2008, and concentrations of volatile organic compounds (VOCs) in those samples are here discussed. This sampling was performed to increase understanding of the distributions of their compositions, illustrate the overall characteristics of different classes of VOCs, assess the ages of air masses, and apportion sources of VOCs using principal compound analysis/absolute principal component scores (PCA/APCS). During the sampling periods, the relative abundance of the four classes of VOCs as determined by the concentration-based method was different from that determined by the reactivity approach. Alkanes were found to be most abundant (44.3-50.1%) by the concentration-based method, but aromatic compounds were most abundant (38.2-44.5%) by the reactivity approach. Aromatics and alkenes contributed most (73-84%) to the ozone formation potential. Toluene was the most abundant compound (11.8-12.7%) during every sampling period. When the maximum incremental reactivity approach was used, propene, toluene, m,p-xylene, 1-butene, and 1,2,4-trimethylbenzene were the five most abundant compounds during two sampling periods. X/B, T/B, and E/B ratios in this study were lower than those found in other cities, possibly due to the aging of the air mass at this site. Four components were extracted from application of PCA to the data. It was found that the contribution of vehicle exhaust to total VOCs accounted for 53% of VOCs, while emissions due to the solvent use contributed 33% of the total VOCs. Industrial sources contributed 3% and biogenic sources contributed 11%. The results showed that vehicle exhausts (i.e., unburned vehicle emissions + vehicle internal engine combustion) were dominant in VOC emissions during the experimental period. The solvent use made the second most significant contribution to ambient VOCs.

  6. Quantitation of DNA Adducts Induced by 1,3-Butadiene

    NASA Astrophysics Data System (ADS)

    Sangaraju, Dewakar; Villalta, Peter W.; Wickramaratne, Susith; Swenberg, James; Tretyakova, Natalia

    2014-07-01

    Human exposure to 1,3-butadiene (BD) present in automobile exhaust, cigarette smoke, and forest fires is of great concern because of its potent carcinogenicity. The adverse health effects of BD are mediated by its epoxide metabolites such as 3,4-epoxy-1-butene (EB), which covalently modify genomic DNA to form promutagenic nucleobase adducts. Because of their direct role in cancer, BD-DNA adducts can be used as mechanism-based biomarkers of BD exposure. In the present work, a mass spectrometry-based methodology was developed for accurate, sensitive, and precise quantification of EB-induced N-7-(1-hydroxy-3-buten-2-yl) guanine (EB-GII) DNA adducts in vivo. In our approach, EB-GII adducts are selectively released from DNA backbone by neutral thermal hydrolysis, followed by ultrafiltration, offline HPLC purification, and isotope dilution nanoLC/ESI+-HRMS3 analysis on an Orbitrap Velos mass spectrometer. Following method validation, EB-GII lesions were quantified in human fibrosarcoma (HT1080) cells treated with micromolar concentrations of EB and in liver tissues of rats exposed to sub-ppm concentrations of BD (0.5-1.5 ppm). EB-GII concentrations increased linearly from 1.15 ± 0.23 to 10.11 ± 0.45 adducts per 106 nucleotides in HT1080 cells treated with 0.5-10 μM DEB. EB-GII concentrations in DNA of laboratory rats exposed to 0.5, 1.0, and 1.5 ppm BD were 0.17 ± 0.05, 0.33 ± 0.08, and 0.50 ± 0.04 adducts per 106 nucleotides, respectively. We also used the new method to determine the in vivo half-life of EB-GII adducts in rat liver DNA (2.20 ± 0.12 d) and to detect EB-GII in human blood DNA. To our knowledge, this is the first application of nanoLC/ESI+-HRMS3 Orbitrap methodology to quantitative analysis of DNA adducts in vivo.

  7. [Role of surface-generated gas-phase radicals in heterogeneous catalysis] Final Technical Report, January 1, 1994 - December 31, 2001

    SciTech Connect

    Lunsford, Jack H.

    2002-03-20

    A major theme in this research has been the role of surface-generated gas-phase radicals in heterogeneous catalysis, with emphasis on methyl radicals formed from methane. The activation of methane is of particular interest because of its abundance as a hydrocarbon resource. Previous studies on methyl radicals showed that they are an intermediate in the oxidative coupling of methane to form ethane and subsequently ethylene. More recent research on methyl radicals has focused on their coupling with allyl radicals, derived from propylene, to produce 1-butene and the methylation of ethylene to form propylene. As an extension of the work on methyl radicals, it has been shown that their reaction with vanadium oxide yields surface methoxide ions which either decompose to formaldehyde or react with water to form methanol. The surface and gas phase chemistry of methyl radicals also provided a link to the removal of NOx. In an attempt to explore the validity of a mechanism put forth by Vannice and co-workers, it was shown under this DOE grant that over basic metal oxides methyl radicals indeed react with gas phase NO to form nitrosomethane which is believed to be an intermediate in the selective catalytic reduction (SCR). Over one of these basic oxide catalysts (BaO/MgO), the decomposition of N2O was studied to determine the role of peroxide ions as an intermediate. Hydroxyl radicals also may be formed on surfaces and enter the gas phase where they can promote chain branching reactions during hydrocarbon oxidation. The formation of these radicals during the reaction of water with molecular oxygen over basic oxide catalysts has been studied in detail. A kinetic model provided evidence that these surface generated radicals may play a role in catalytic combustion. Since the hydroxyl radicals may undergo secondary reactions with a surface, this aspect of their chemistry was also explored. In contrast to the low probability of methyl radicals reacting with metal oxide surfaces

  8. Complex Hydrocarbon Chemistry in Interstellar and Solar System Ices Revealed: A Combined Infrared Spectroscopy and Reflectron Time-of-flight Mass Spectrometry Analysis of Ethane (C2H6) and D6-Ethane (C2D6) Ices Exposed to Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Abplanalp, Matthew J.; Kaiser, Ralf I.

    2016-08-01

    The irradiation of pure ethane (C2H6/C2D6) ices at 5.5 K, under ultrahigh vacuum conditions was conducted to investigate the formation of complex hydrocarbons via interaction with energetic electrons simulating the secondary electrons produced in the track of galactic cosmic rays. The chemical modifications of the ices were monitored in situ using Fourier transform infrared spectroscopy (FTIR) and during temperature-programmed desorption via mass spectrometry exploiting a quadrupole mass spectrometer with electron impact ionization (EI-QMS) as well as a reflectron time-of-flight mass spectrometer coupled to a photoionization source (PI-ReTOF-MS). FTIR confirmed previous ethane studies by detecting six molecules: methane (CH4), acetylene (C2H2), ethylene (C2H4), the ethyl radical (C2H5), 1-butene (C4H8), and n-butane (C4H10). However, the TPD phase, along with EI-QMS, and most importantly, PI-ReTOF-MS, revealed the formation of at least 23 hydrocarbons, many for the first time in ethane ice, which can be arranged in four groups with an increasing carbon-to-hydrogen ratio: C n H2n+2 (n = 3, 4, 6, 8, 10), C n H2n (n = 3–10), {{{C}}}n{{{H}}}2n-2 (n = 3–10), and {{{C}}}n{{{H}}}2n-4 (n = 4–6). The processing of simple ethane ices is relevant to the hydrocarbon chemistry in the interstellar medium, as ethane has been shown to be a major product of methane, as well as in the outer solar system. These data reveal that the processing of ethane ices can synthesize several key hydrocarbons such as C3H4 and C4H6 isomers, which ha­ve been found to synthesize polycyclic aromatic hydrocarbons like indene (C9H8) and naphtha­lene (C10H8) in the ISM and in hydrocarbon-rich atmospheres of planets and their moons such as Titan.

  9. OH Radical Reaction Rate Coefficients, Infrared Spectrum, and Global Warming Potential of (CF3)2CFCH═CHF (HFO-1438ezy(E)).

    PubMed

    Papadimitriou, Vassileios C; Burkholder, James B

    2016-08-25

    Rate coefficients, k(T), for the OH radical + (E)-(CF3)2CFCH═CHF ((E)-1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene, HFO-1438ezy(E)) gas-phase reaction were measured using pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) between 214 and 380 K and 50 and 450 Torr (He or N2 bath gas) and with a relative rate method at 296 K between 100 and 400 Torr (synthetic air). Over the range of pressures included in this study, no pressure dependence in k(T) was observed. k(296 K) obtained using the two techniques agreed to within ∼3% with (3.26 ± 0.26) × 10(-13) cm(3) molecule(-1) s(-1) (2σ absolute uncertainty) obtained using the PLP-LIF technique. k(T) displayed non-Arrhenius behavior that is reproduced by (7.34 ± 0.30) × 10(-19)T(2) exp[(481 ± 10)/T) cm(3) molecule(-1) s(-1). With respect to OH reactive loss, the atmospheric lifetime of HFO-1438ezy(E) is estimated to be ∼36 days and HFO-1438ezy(E) is considered a very short-lived substance (VSLS) (the actual lifetime will depend on the time and location of the HFO-1438ezy(E) emission). On the basis of the HFO-1438ezy(E) infrared absorption spectrum measured in this work and its estimated lifetime, a radiative efficiency of 0.306 W m(-2) ppb(-1) (well-mixed gas) was calculated and its 100-year time-horizon global warming potential, GWP100, was estimated to be 8.6. CF3CFO, HC(O)F, and CF2O were identified using infrared spectroscopy as stable end products in the oxidation of HFO-1438ezy(E) in the presence of O2. Two additional fluorinated products were observed and theoretical calculations of the infrared spectra of likely degradation products are presented. The photochemical ozone creation potential of HFO-1438ezy(E) was estimated to be ∼2.15.

  10. Plasma discharge in N2 + CH4 at low pressures: experimental results and applications to Titan.

    PubMed

    Thompson, W R; Henry, T J; Schwartz, J M; Khare, B N; Sagan, C

    1991-01-01

    = allene), and CH2=CH-C triple bond CH (1-buten-3-yne) to be present at mol fractions X > 10(-9), and CH2=CH-C triple bond N (propenenitrile), CH3-CH=CH2 (propene), and CH3-CH2-C triple bond N (propanenitrile) at X > 10(-10) in Titan's atmosphere.

  11. Reaction dynamics of carbon-bearing radicals in circumstellar envelopes of carbon stars.

    PubMed

    Gu, Xibin; Guo, Ying; Zhang, Fangtong; Mebel, Alexander M; Kaiser, Ralf I

    2006-01-01

    Crossed molecular beams experiments on dicarbon molecules, C2(X1sigmag+/a3piu), with unsaturated hydrocarbons acetylene (C2H2(X1sigmag+), ethylene (C2H4(X1Ag)), methylacetylene (CH3CCH(X1A1)), and allene (H2CCCH2 (X1A1)) were carried out at 18 collision energies between 10.6 and 50.3 kJ mol(-1) utilizing a universal crossed beams machine to untangle the reaction dynamics forming hydrogen deficient hydrocarbon radicals in circumstellar envelopes of carbons stars and in cold molecular clouds. We find that all reactions proceed without the entrance barrier through indirect (complex forming) scattering dynamics. Each bimolecular collision is initiated by an addition of the dicarbon molecule to the pi bond of the unsaturated hydrocarbon molecule yielding initially acyclic (triplet) and three- or four-membered cyclic collision complexes (triplet and singlet surface). On the singlet surface, the cyclic structures isomerize to form eventually diacetylene (HCCCCH; C2/C2H2), butatriene (H2CCCCH2; C2/C2H4), methyldiacetylene (CH3CCCCH; C2/CH3CCH), and pentatetraene (H2CCCCCH2; C2/H2CCCH2) intermediates. The latter were found to decompose via atomic hydrogen loss yielding the buta-1,3-diynyl [C4H(X2sigma+) HCCCC], 1-butene-3-yne-2-yl [i-C4H3(X2A') H2CCCCH], penta-2,4-diynyl-1 [C5H3(X2B1) HCCCCCH2], and penta-1,4-diynyl-3 radical [C5H3(X2B1) HCCCHCCH] under single collision conditions. The underlying characteristics of these dicarbon versus atomic hydrogen replacement pathways (indirect scattering dynamics; no entrance barrier; isomerization barriers below the energy of the separated reactants; exoergic reactions) suggest the enormous potential of the dicarbon plus unsaturated hydrocarbon reaction class to form highly hydrogen-deficient carbonaceous molecules in cold molecular clouds and in circumstellar envelopes of carbon stars. The studies therefore present an important advancement in establishing a comprehensive database of reaction intermediates and products involved in

  12. Complex Hydrocarbon Chemistry in Interstellar and Solar System Ices Revealed: A Combined Infrared Spectroscopy and Reflectron Time-of-flight Mass Spectrometry Analysis of Ethane (C2H6) and D6-Ethane (C2D6) Ices Exposed to Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Abplanalp, Matthew J.; Kaiser, Ralf I.

    2016-08-01

    The irradiation of pure ethane (C2H6/C2D6) ices at 5.5 K, under ultrahigh vacuum conditions was conducted to investigate the formation of complex hydrocarbons via interaction with energetic electrons simulating the secondary electrons produced in the track of galactic cosmic rays. The chemical modifications of the ices were monitored in situ using Fourier transform infrared spectroscopy (FTIR) and during temperature-programmed desorption via mass spectrometry exploiting a quadrupole mass spectrometer with electron impact ionization (EI-QMS) as well as a reflectron time-of-flight mass spectrometer coupled to a photoionization source (PI-ReTOF-MS). FTIR confirmed previous ethane studies by detecting six molecules: methane (CH4), acetylene (C2H2), ethylene (C2H4), the ethyl radical (C2H5), 1-butene (C4H8), and n-butane (C4H10). However, the TPD phase, along with EI-QMS, and most importantly, PI-ReTOF-MS, revealed the formation of at least 23 hydrocarbons, many for the first time in ethane ice, which can be arranged in four groups with an increasing carbon-to-hydrogen ratio: C n H2n+2 (n = 3, 4, 6, 8, 10), C n H2n (n = 3-10), {{{C}}}n{{{H}}}2n-2 (n = 3-10), and {{{C}}}n{{{H}}}2n-4 (n = 4-6). The processing of simple ethane ices is relevant to the hydrocarbon chemistry in the interstellar medium, as ethane has been shown to be a major product of methane, as well as in the outer solar system. These data reveal that the processing of ethane ices can synthesize several key hydrocarbons such as C3H4 and C4H6 isomers, which ha­ve been found to synthesize polycyclic aromatic hydrocarbons like indene (C9H8) and naphtha­lene (C10H8) in the ISM and in hydrocarbon-rich atmospheres of planets and their moons such as Titan.

  13. Kinetics and characterization of bismuth molybdate catalysts. 2. Reaction studies over various bimolybdates

    SciTech Connect

    Burban, P.M.; Schuit, G.C.A.; Bischoff, K.B. ); Koch, T.A. Du Pont Experimental Station, Wilmington, DE )

    1990-12-01

    The model reaction, 1-butene to 1,3-butadiene, was studied over various compositions of unsupported bismuth molybdates to rank the catalysts' reactivities. The authors confirmed that {gamma}-Bi{sub 2}MoO{sub 6} doped with bismuth to yield a surface Bi/Mo > 2.0 is unselective: selective catalyst species need a few mole% excess MoO{sub 3}. All catalysts with a surface Bi/Mo {le} 1.5 show selectivities to butadiene greater than 95%. As the amount of MoO{sub 3} increases, reducing the surface Bi/Mo ratio, the activity increases down to Bi/Mo = 1.5, then remains constant down to Bi/Mo = 1, and then decreases steadily down to Bi/Mo = 2/3. Characteristics of the partial oxidation catalysis change drastically going from {gamma}-Bi{sub 2}MoO{sub 6} to {alpha}-Bi{sub 2}MoO{sub 12}catalysts. For the model reaction, Bi{sub 2}MoO{sub 6} + 4% MoO{sub 3}exhibits an E{alpha} = 40 kJ/mol(9.5 kcal/mol) at temperatures above 673 K. This catalyst is completely poisoned by its product butadiene below 673 K, while the inhibition is lifted above this temperature. The authors suggest that the pores of this catalyst, estimated to be 24 nm in diameter, become filled with polybutadiene; the heat of butadiene adsorption was estimated to be 375 kJ/mol. In contrast, {alpha}-Bi{sub 2}MoO{sub 12} is not inhibited by butadiene, and has a lower activity (even calculated per unit surface) with an activation energy of 93 kJ/mol over the entire temperature range 660-713 K, studied. The authors propose models which describe two distinct ensemble effects operative in determining the kinetics over selective {gamma}-Bi{sub 2}MoO{sub 6} and {alpha}-Bi{sub 2}Mo{sub 3}O{sub 12} catalysts.

  14. OH Radical Reaction Rate Coefficients, Infrared Spectrum, and Global Warming Potential of (CF3)2CFCH═CHF (HFO-1438ezy(E)).

    PubMed

    Papadimitriou, Vassileios C; Burkholder, James B

    2016-08-25

    Rate coefficients, k(T), for the OH radical + (E)-(CF3)2CFCH═CHF ((E)-1,3,4,4,4-pentafluoro-3-(trifluoromethyl)-1-butene, HFO-1438ezy(E)) gas-phase reaction were measured using pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) between 214 and 380 K and 50 and 450 Torr (He or N2 bath gas) and with a relative rate method at 296 K between 100 and 400 Torr (synthetic air). Over the range of pressures included in this study, no pressure dependence in k(T) was observed. k(296 K) obtained using the two techniques agreed to within ∼3% with (3.26 ± 0.26) × 10(-13) cm(3) molecule(-1) s(-1) (2σ absolute uncertainty) obtained using the PLP-LIF technique. k(T) displayed non-Arrhenius behavior that is reproduced by (7.34 ± 0.30) × 10(-19)T(2) exp[(481 ± 10)/T) cm(3) molecule(-1) s(-1). With respect to OH reactive loss, the atmospheric lifetime of HFO-1438ezy(E) is estimated to be ∼36 days and HFO-1438ezy(E) is considered a very short-lived substance (VSLS) (the actual lifetime will depend on the time and location of the HFO-1438ezy(E) emission). On the basis of the HFO-1438ezy(E) infrared absorption spectrum measured in this work and its estimated lifetime, a radiative efficiency of 0.306 W m(-2) ppb(-1) (well-mixed gas) was calculated and its 100-year time-horizon global warming potential, GWP100, was estimated to be 8.6. CF3CFO, HC(O)F, and CF2O were identified using infrared spectroscopy as stable end products in the oxidation of HFO-1438ezy(E) in the presence of O2. Two additional fluorinated products were observed and theoretical calculations of the infrared spectra of likely degradation products are presented. The photochemical ozone creation potential of HFO-1438ezy(E) was estimated to be ∼2.15. PMID:27482844

  15. On the chemical kinetics of n-butanol: ignition and speciation studies.

    PubMed

    Karwat, Darshan M A; Wagnon, Scott W; Teini, Paul D; Wooldridge, Margaret S

    2011-05-19

    Direct measurements of intermediates of ignition are challenging experimental objectives, yet such measurements are critical for understanding fuel decomposition and oxidation pathways. This work presents experimental results, obtained using the University of Michigan Rapid Compression Facility, of ignition delay times and intermediates formed during the ignition of n-butanol. Ignition delay times for stoichiometric n-butanol/O(2) mixtures with an inert/O(2) ratio of 5.64 were measured over a temperature range of 920-1040 K and a pressure range of 2.86-3.35 atm and were compared to those predicted by the recent reaction mechanism developed by Black et al. (Combust. Flame 2010, 157, 363-373). There is excellent agreement between the experimental results and model predictions for ignition delay time, within 20% over the entire temperature range tested. Further, high-speed gas sampling and gas chromatography techniques were used to acquire and analyze gas samples of intermediate species during the ignition delay of stoichiometric n-butanol/O(2) (χ(n-but) = 0.025, χ(O(2)) = 0.147, χ(N(2)) = 0.541, χ(Ar) = 0.288) mixtures at P = 3.25 atm and T = 975 K. Quantitative measurements of mole fraction time histories of methane, carbon monoxide, ethene, propene, acetaldehyde, n-butyraldehyde, 1-butene and n-butanol were compared with model predictions using the Black et al. mechanism. In general, the predicted trends for species concentrations are consistent with measurements. Sensitivity analyses and rate of production analyses were used to identify reactions important for predicting ignition delay time and the intermediate species time histories. Modifications to the mechanism by Black et al. were explored based on recent contributions to the literature on the rate constant for the key reaction, n-butanol+OH. The results improve the model agreement with some species; however, the comparison also indicates some reaction pathways, particularly those important to ethene

  16. Transferable Anisotropic United-Atom Force Field Based on the Mie Potential for Phase Equilibrium Calculations: n-Alkanes and n-Olefins.

    PubMed

    Hemmen, Andrea; Gross, Joachim

    2015-09-01

    A new transferable force field parametrization for n-alkanes and n-olefins is proposed in this work. A united-atom approach is taken, where hydrogen atoms are lumped with neighboring atoms to single interaction sites. A comprehensive study is conducted for alkanes, optimizing van der Waals force field parameters in 6 dimensions. A Mie n-6 potential is considered for the van der Waals interaction, where for n-alkanes we simultaneously optimize the energy parameters ϵCH3 and ϵCH2 as well as the size parameters σCH3 and σCH2 of the CH3(sp(3)) and CH2(sp(3)) groups. Further, the repulsive exponent n of the Mie n-6 potential is varied. Moreover, we investigate the bond length toward the terminal CH3 group as a degree of freedom. According to the AUA (anisotropic united-atom) force field, the bond length between the terminal CH3 group and the neighboring interaction site should be increased by Δl compared with the carbon-carbon distance in order to better account for the hydrogen atoms. The parameter Δl is considered as a degree of freedom. The intramolecular force field parametrization is taken from existing force fields. A single objective function for the optimization is defined as squared relative deviations in vapor pressure and in liquid density of propane, n-butane, n-hexane, and n-octane. A similar study is also done for olefins, where the objective function includes 1-butene, 1-hexene, 1-octene, cis-2-pentene, and trans-2-pentene. Molecular simulations are performed in the grand canonical ensemble with transition-matrix sampling where the phase equilibrium properties are obtained with the histogram reweighting technique. The 6-dimensional optimization of strongly correlated parameters is possible, because the analytic PC-SAFT equation of state is used to locally correlate simulation results. The procedure is iterative but leads to very efficient convergence. An implementation is proposed, where the converged result is not affected (disturbed) by the

  17. Pressure Effects on Product Channels of the Allyl Radical Reactions; C3H5+C3H5 and C3H5+CH3

    NASA Astrophysics Data System (ADS)

    Halpern, J. B.; N'Doumi, M.; Fahr, A.

    2011-12-01

    Relatively large hydrocarbon molecules (C4, C6 and larger) have been detected in several planetary environments. The mechanism for the formation of such large molecular species and detailed mechanism for their potential destruction are not well understood and are of considerable current interest. Previously we have studied the kinetics and product channels of small unsaturated hydrocarbon radical (C2 and C3s) reactions relevant to planetary atmospheric modeling. Reactions of C2 radicals (such as vinyl, H2CCH and ethynyl C2H) and C3 radicals (such as propargyl, HCCCH2) can affect the abundances of a large number of stable observable C3, C4, C5, C6 and larger molecules, including linear, aromatic and even poly aromatic molecules. Pressure-dependent product yields have been determined experimentally for the self- and cross-radical reactions performed at 298 K and at pressures between ~4 Torr (0.5 kPa) and 760 Torr (101 kPa). Final reaction products were quantitatively determined using a gas chromatograph with mass spectrometry/flame ionization detection (GC/MS/FID). In some cases complementary computational studies extended the pressure and temperature range of the experiments and provided valuable information on the complex reaction mechanisms. Theses studies provide a systematic framework so that important energetic and structural parameters for radical-radical reactions can be assessed. Here we report recent results for the allyl radical reactions H2CCCH3+ H2CCCH3 and H2CCCH3+CH3. For the allyl radical self-reaction, at high pressures the "head -to-head", combination channel forming 1,5-hexadiene is dominant with a combination/disproportionation = 1,5-hexadiene/propyne ratio of about 24 at 500 Torr (67 kPa, T=298K). At low pressures the ratio is substantially reduced to about 1.2 (at 0.3 kPa) and other major products are observed including allene, propene, 1-butene and propyne.

  18. Characterization of hydrocarbons, halocarbons and carbonyls in the atmosphere of Hong Kong.

    PubMed

    Guo, H; Lee, S C; Louie, P K K; Ho, K F

    2004-12-01

    in winter motor vehicle emissions would be the major sources of the carbonyls. The photochemical reactivity of selected VOCs was estimated in this study. The largest contributors to ozone formation were formaldehyde, toluene, propene, m,p-xylene, acetaldehyde, 1-butene/i-butene, isoprene and n-butane, suggesting that motor vehicles, gasoline evaporation, use of solvents, leakage of LPG, photochemical processes and biogenic emission are sources in the production of ozone. On the other hand, VOCs from vehicles and gasoline evaporation were predominant with respect to reactions with OH radical. PMID:15519381

  19. Light emission from an ambipolar semiconducting polymer field-effect transistor

    NASA Astrophysics Data System (ADS)

    Swensen, James Sherman

    The successful demonstration of light emitting field-effect transistors (LEFETs) has been worked towards for years within the organic electronics community. The belief was held that if an ambipolar FET could be developed with high enough density of both electrons and holes within the channel region of an FET simultaneously, then recombination of those carriers would result in electroluminescence. The challenge to demonstrating such a device centered on the issue of electron transport; why was electron transport not observed for nearly all SCPs in a field-effect transistor? Use of a low dielectric constant material to passivate inorganic dielectrics in order to observe electron transport for semiconducting conjugated polymers in a field-effect transistor was verified. A different material, polypropylene-co-1-butene, was shown to passivate various inorganic insulators to eliminate or reduce trap states such that electron transport can be observed for SCPs. Another challenge to demonstrating an LEFET involved developing a method to deposit a low work function metal as either the source or the drain electrode in the FET structure. In this research, a process was developed in which an SCP FET can be fabricated inside of a nitrogen glove box where one electrode is a high work function metal and the other electrode is a low work function metal with the precision of photolithography using a silicon shadow mask and an angled evaporation technique. As a result, the SCP LED electrodes architecture was successfully transferred to an FET platform as the source and drain electrodes, which we "call two-color electrodes." In summary, by combining the passivation layer technology which allows for electron transport and the silicon shadow mask/angled evaporation technique which gives two color electrodes, ambipolar SCP LEFETs were demonstrated. Transport data show ambipolar behavior. Recombination of electrons and holes result in a narrow zone of light emission within the channel

  20. Synthesis of X-Ray Sensitive Polymers and Their Applications as Resists

    NASA Astrophysics Data System (ADS)

    Davies, Jack Dean

    Aliphatic polycarbonates were synthesized by condensation of the bischloroformate of 2,2,4,4-tetramethyl-1,3-cyclobutanediol with cyclic aliphatic diols. Polycarbonates that lacked flexible methylene units in the backbone processed T _{rm g} > 139 ^circC. Copolycarbonates acted as resists when combined with cobalt(III)-am(m)ine tetraphenylborate complexes which act as photointiators, with tetraphenylborate serving as counter anion. The photoinitiator liberates either ammonia or ethylene diamine base upon UV exposure and the polycarbonate backbone is subject to nucleophilic attack at the carbonyl linkage by the base. Image tone was dependent on the base used. Amine complexes, Co(NH _3)_6^{3+} effected a positive tone due to ammonia induced main chain degradation at the carbonate linkage. Cobalt ethylenediamine complex, Co(en)_3^{3+} , en is ethylenediamine, effected a negative tone. The released ethylenediamine acted as a tetrafunctional crosslinking agent forming carbamate linkages. Resolution studies determined linewidths to 20 mum. The amine complex, under low intensity UV radiation, >0.35 mW/cm^2, and elevated temperatures, >40^circC, promoted vapor developed positive tone images in the resists layer. 1-Butene, 2-methyl-1-pentene, cyclohexene, and norbornene were copolymerized with sulfur dioxide. Thermal characterization revealed that these copolymers possess low T_{rm g}, i.e., <35^circC, and two degradation transitions between 110-200 ^circC. They undergo main chain degradation forming positive tone images when exposed to synchrotron radiation and base development. Sensitivities were determined to be <25 mJ/cm^2 for poly (2-methyl pentene-1 sulfone). This copolymer vapor develops upon exposure of μm thick films to doses >800 mJ/cm ^2. Features to 0.4muM were obtained in this manner using a test mask. Novel polysulfones were prepared by the polymerization of SO_2 with conjugated dienes. Polymerizations were perfonned at -78^circ C in nitropropane as solvent

  1. The pyrolysis of 2-methylfuran: a quantum chemical, statistical rate theory and kinetic modelling study.

    PubMed

    Somers, Kieran P; Simmie, John M; Metcalfe, Wayne K; Curran, Henry J

    2014-03-21

    Due to the rapidly growing interest in the use of biomass derived furanic compounds as potential platform chemicals and fossil fuel replacements, there is a simultaneous need to understand the pyrolysis and combustion properties of such molecules. To this end, the potential energy surfaces for the pyrolysis relevant reactions of the biofuel candidate 2-methylfuran have been characterized using quantum chemical methods (CBS-QB3, CBS-APNO and G3). Canonical transition state theory is employed to determine the high-pressure limiting kinetics, k(T), of elementary reactions. Rice-Ramsperger-Kassel-Marcus theory with an energy grained master equation is used to compute pressure-dependent rate constants, k(T,p), and product branching fractions for the multiple-well, multiple-channel reaction pathways which typify the pyrolysis reactions of the title species. The unimolecular decomposition of 2-methylfuran is shown to proceed via hydrogen atom transfer reactions through singlet carbene intermediates which readily undergo ring opening to form collisionally stabilised acyclic C5H6O isomers before further decomposition to C1-C4 species. Rate constants for abstraction by the hydrogen atom and methyl radical are reported, with abstraction from the alkyl side chain calculated to dominate. The fate of the primary abstraction product, 2-furanylmethyl radical, is shown to be thermal decomposition to the n-butadienyl radical and carbon monoxide through a series of ring opening and hydrogen atom transfer reactions. The dominant bimolecular products of hydrogen atom addition reactions are found to be furan and methyl radical, 1-butene-1-yl radical and carbon monoxide and vinyl ketene and methyl radical. A kinetic mechanism is assembled with computer simulations in good agreement with shock tube speciation profiles taken from the literature. The kinetic mechanism developed herein can be used in future chemical kinetic modelling studies on the pyrolysis and oxidation of 2-methylfuran

  2. Pathway and Surface Mechanism Studies of 1,3-butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts

    SciTech Connect

    William David Schroeder

    2002-05-27

    The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m{sup 2}/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO{sub 3}/(MoO{sub 3} + V{sub 2}O{sub 5}). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V{sup +4} and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of water addition were related to competitive adsorption with various V{sub 2}O{sub 5}-based surface sites, including the vanadyl V=O, corner sharing V-O-V and edge sharing V-O oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions of V{sub 2}O{sub 5}, solid solutions of Mo in V{sub 2}O{sub 5}, V{sub 9}Mo{sub 6}O{sub 40}, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0-42 mol% MoO{sub 3}/(V{sub 2}O{sub 5} + MoO{sub 3}), determined by EDS analysis.

  3. Investigation of potential interferences in the detection of atmospheric ROx radicals by laser-induced fluorescence under dark conditions

    NASA Astrophysics Data System (ADS)

    Fuchs, Hendrik; Tan, Zhaofeng; Hofzumahaus, Andreas; Broch, Sebastian; Dorn, Hans-Peter; Holland, Frank; Künstler, Christopher; Gomm, Sebastian; Rohrer, Franz; Schrade, Stephanie; Tillmann, Ralf; Wahner, Andreas

    2016-04-01

    Direct detection of highly reactive, atmospheric hydroxyl radicals (OH) is widely accomplished by laser-induced fluorescence (LIF) instruments. The technique is also suitable for the indirect measurement of HO2 and RO2 peroxy radicals by chemical conversion to OH. It requires sampling of ambient air into a low-pressure cell, where OH fluorescence is detected after excitation by 308 nm laser radiation. Although the residence time of air inside the fluorescence cell is typically only on the order of milliseconds, there is potential that additional OH is internally produced, which would artificially increase the measured OH concentration. Here, we present experimental studies investigating potential interferences in the detection of OH and peroxy radicals for the LIF instruments of Forschungszentrum Jülich for nighttime conditions. For laboratory experiments, the inlet of the instrument was over flowed by excess synthetic air containing one or more reactants. In order to distinguish between OH produced by reactions upstream of the inlet and artificial signals produced inside the instrument, a chemical titration for OH was applied. Additional experiments were performed in the simulation chamber SAPHIR where simultaneous measurements by an open-path differential optical absorption spectrometer (DOAS) served as reference for OH to quantify potential artifacts in the LIF instrument. Experiments included the investigation of potential interferences related to the nitrate radical (NO3, N2O5), related to the ozonolysis of alkenes (ethene, propene, 1-butene, 2,3-dimethyl-2-butene, α-pinene, limonene, isoprene), and the laser photolysis of acetone. Experiments studying the laser photolysis of acetone yield OH signals in the fluorescence cell, which are equivalent to 0.05 × 106 cm-3 OH for a mixing ratio of 5 ppbv acetone. Under most atmospheric conditions, this interference is negligible. No significant interferences were found for atmospheric concentrations of reactants

  4. A Unique Equation to Estimate Flash Points of Selected Pure Liquids Application to the Correction of Probably Erroneous Flash Point Values

    NASA Astrophysics Data System (ADS)

    Catoire, Laurent; Naudet, Valérie

    2004-12-01

    several flash points have been reported erroneously, whatever the reason, in one or several reference compilations. In the following lists, the currently accepted flash points for bold compounds err, or probably err, on the hazardous side by at least 10 °C and for the nonbolded compounds, the currently accepted flash points err, or probably err, on the nonhazardous side by at least 10 °C: bicyclohexyl, sec-butylamine, tert-butylamine, 2-cyclohexen-1-one, ethanethiol, 1,3-cyclohexadiene, 1,4-pentadiene, methyl formate, acetonitrile, cinnamaldehyde, 1-pentanol, diethylene glycol, diethyl fumarate, diethyl phthalate, trimethylamine, dimethylamine, 1,6-hexanediol, propylamine, methanethiol, ethylamine, bromoethane, 1-bromopropane, tert-butylbenzene, 1-chloro-2-methylpropane, diacetone alcohol, diethanolamine, 2-ethylbutanal, and formic acid. For some other compounds, no other data than the currently accepted flash points are available. Therefore, it cannot be assessed that these flash point data are erroneous but it can be stated that they are probably erroneous. At least, they need experimental re-examination. They are probably erroneous by at least 15 °C: 1,3-cyclopentadiene, di-tert-butyl sulfide, dimethyl ether, dipropyl ether, 4-heptanone, bis(2-chloroethyl)ether, 1-decanol, 1-phenyl-1-butanone, furan, ethylcyclopentane, 1-heptanethiol, 2,5-hexanediol, 3-hexanone, hexanoic acid methyl ester, 4-methyl-1,3-pentadiene, propanoyl chloride, tetramethylsilane, thiacyclopentane, 1-chloro-2-methyl-1-propene, trans-1,3-pentadiene, 2,3-dimethylheptane, triethylenetetramine, methylal, N-ethylisopropylamine, 3-methyl-2-pentene, and 2,3-dimethyl-1-butene.

  5. I. Synthesis, characterization, and base catalysis of novel zeolite supported super-basic materials II. Oxidative dehydrogenation of ethane over reduced heteropolyanion catalysts

    NASA Astrophysics Data System (ADS)

    Galownia, Jonathan M.

    This thesis is composed of two separate and unrelated projects. The first part of this thesis outlines an investigation into the synthesis and characterization of a novel zeolite supported super-base capable of carbon-carbon olefin addition to alkyl aromatics. A zeolite supported basic material capable of such reactions would benefit many fine chemical syntheses, as well as vastly improve the economics associated with production of the high performance thermoplastic polyester polyethylene naphthalate. The thermal decomposition of alkali---metal azides impregnated in zeolite X is investigated as a novel route to the synthesis of a zeolite supported super-base. Impregnation of the alkali---metal azide precursor is shown to result in azide species occluded within the pores of the zeolite support by using high speed, solid-state 23Na MAS and 2D MQMAS NMR, FTIR, and TGA characterization methods. Addition of alkali---metal azides to the zeolite results in redistribution of the extra-lattice cations in the zeolite framework. Thermal decomposition of impregnated azide species produces further cation redistribution, but no neutral metallic clusters are detected by high speed, solid-state 23Na MAS NMR following thermal activation of the materials. Instead, it is possible that inactive ionic clusters are formed. The thermally activated materials do not promote base catalysis for the isomerization of 1-butene, the ethylation of toluene and o-xylene, and the alkenylation of o-xylene with 1,3-butadiene to produce 5-ortho-tolyl-pent-2-ene (5-OTP). The lack of catalytic activity in the materials is attributed to failure of the materials to form neutral metallic clusters during thermal treatment, possibly due to preferential formation of NMR silent ionic clusters. The formation of neutral metallic clusters is found to be insensitive to synthesis technique and activation procedure. It is concluded that the impregnation of alkali---metal azides in zeolite X does not provide a

  6. Investigation of potential interferences in the detection of atmospheric ROx radicals by laser-induced fluorescence under dark conditions

    NASA Astrophysics Data System (ADS)

    Fuchs, H.; Tan, Z.; Hofzumahaus, A.; Broch, S.; Dorn, H.-P.; Holland, F.; Künstler, C.; Gomm, S.; Rohrer, F.; Schrade, S.; Tillmann, R.; Wahner, A.

    2015-11-01

    Direct detection of highly reactive, atmospheric hydroxyl radicals (OH) is widely accomplished by laser-induced fluorescence (LIF) instruments. The technique is also suitable for the indirect measurement of HO2 and RO2 peroxy radicals by chemical conversion to OH. It requires sampling of ambient air into a low pressure cell, where OH fluorescence is detected after excitation by 308 nm laser radiation. Although the residence time of air inside the fluorescence cell is typically only on the order of milliseconds, there is potential that additional OH is internally produced, which would artificially increase the measured OH concentration. Here, we present experimental studies investigating potential interferences in the detection of OH and peroxy radicals for the LIF instruments of Forschungszentrum Jülich for nighttime conditions. For laboratory experiments, the inlet of the instrument was overflown by excess synthetic air containing one or more reactants. In order to distinguish between OH produced by reactions upstream of the inlet and artificial signals produced inside the instrument, a chemical titration for OH was applied. Additional experiments were performed in the simulation chamber SAPHIR where simultaneous measurements by an open-path differential optical absorption spectrometer (DOAS) served as reference for OH to quantify potential artifacts in the LIF instrument. Experiments included the investigation of potential interferences related to the nitrate radical (NO3, N2O5), related to the ozonolysis of alkenes (ethene, propene, 1-butene, 2,3-dimethyl-2-butene, α-pinene, limonene, isoprene), and the laser photolysis of acetone. Experiments studying the laser photolysis of acetone yield OH signals in the fluorescence cell, which are equivalent to 0.05 × 106 cm-3 OH for a mixing ratio of 5 ppbv acetone. Under most atmospheric conditions, this interference is negligible. No significant interferences were found for atmospheric concentrations of reactants

  7. Multinuclear group 4 catalysis: olefin polymerization pathways modified by strong metal-metal cooperative effects.

    PubMed

    McInnis, Jennifer P; Delferro, Massimiliano; Marks, Tobin J

    2014-08-19

    Polyolefins are produced today catalytically on a vast scale, and the manufactured polymers find use in everything from artificial limbs and food/medical packaging to automotive and electrical components and lubricants. Although polyolefin monomers are typically cheap (e.g., ethylene, propylene, α-olefins), the resulting polymer properties can be dramatically tuned by the particular polymerization catalyst employed, and reflect a rich interplay of macromolecular chemistry, materials science, and physics. For example, linear low-density polyethylene (LLDPE), produced by copolymerization of ethylene with linear α-olefin comonomers such as 1-butene, 1-hexene, or 1-octene, has small but significant levels of short alkyl branches (C2, C4, C6) along the polyethylene backbone, and is an important technology material due to outstanding rheological and mechanical properties. In 2013, the total world polyolefin production was approximately 211 million metric tons, of which about 11% was LLDPE. Historically, polyolefins were produced using ill-defined but highly active heterogeneous catalysts composed of supported groups 4 or 6 species (usually halides) activated by aluminum alkyls. In 1963, Karl Ziegler and Giulio Natta received the Nobel Prize for these discoveries. Beginning in the late 1980s, a new generation of group 4 molecule-based homogeneous olefin polymerization catalysts emerged from discoveries by Walter Kaminsky, a team led by James Stevens at The Dow Chemical Company, this Laboratory at Northwestern University, and a host of talented groups in Germany, Italy, Japan, the United Kingdom, and the United States. These new "single-site" catalysts and their activating cocatalysts were far better defined and more rationally tunable in terms of structure, mechanism, thermodynamics, and catalyst activity and selectivity than ever before possible. An explosion of research advances led to new catalysts, cocatalysts, deeper mechanistic understanding of both the

  8. Multinuclear group 4 catalysis: olefin polymerization pathways modified by strong metal-metal cooperative effects.

    PubMed

    McInnis, Jennifer P; Delferro, Massimiliano; Marks, Tobin J

    2014-08-19

    Polyolefins are produced today catalytically on a vast scale, and the manufactured polymers find use in everything from artificial limbs and food/medical packaging to automotive and electrical components and lubricants. Although polyolefin monomers are typically cheap (e.g., ethylene, propylene, α-olefins), the resulting polymer properties can be dramatically tuned by the particular polymerization catalyst employed, and reflect a rich interplay of macromolecular chemistry, materials science, and physics. For example, linear low-density polyethylene (LLDPE), produced by copolymerization of ethylene with linear α-olefin comonomers such as 1-butene, 1-hexene, or 1-octene, has small but significant levels of short alkyl branches (C2, C4, C6) along the polyethylene backbone, and is an important technology material due to outstanding rheological and mechanical properties. In 2013, the total world polyolefin production was approximately 211 million metric tons, of which about 11% was LLDPE. Historically, polyolefins were produced using ill-defined but highly active heterogeneous catalysts composed of supported groups 4 or 6 species (usually halides) activated by aluminum alkyls. In 1963, Karl Ziegler and Giulio Natta received the Nobel Prize for these discoveries. Beginning in the late 1980s, a new generation of group 4 molecule-based homogeneous olefin polymerization catalysts emerged from discoveries by Walter Kaminsky, a team led by James Stevens at The Dow Chemical Company, this Laboratory at Northwestern University, and a host of talented groups in Germany, Italy, Japan, the United Kingdom, and the United States. These new "single-site" catalysts and their activating cocatalysts were far better defined and more rationally tunable in terms of structure, mechanism, thermodynamics, and catalyst activity and selectivity than ever before possible. An explosion of research advances led to new catalysts, cocatalysts, deeper mechanistic understanding of both the

  9. Chromatography and mass spectrometry of prebiological and biological molecules

    NASA Astrophysics Data System (ADS)

    Navale, Vivek

    The detection and identification of prebiological and biological molecules are of importance for understanding chemical and biological processes occurring within the solar system. Molecular mass measurements, peptide mapping, and disulfide bond analysis of enzymes and recombinant proteins are important in the development of therapeutic drugs for human diseases. Separation of hydrocarbons (C1 to C6) and nitriles was achieved by 14%-cyanopropylphenyl-86%- dimethylpolysiloxane (CPPS-DMPS) stationary phase in a narrow bore metal capillary column. The calculation of modeling numbers enabled the differentiation of the C4 hydrocarbon isomers of 1-butene (cis and trans). The modeled retention time values for benzene, toluene, xylene, acetonitrile, propane, and propene nitriles were in good agreement with the measurements. The separation of C2 hydrocarbons (ethane and ethene) from predominantly N2 matrix was demonstrated for the first time on wall coated narrow bore low temperature glassy carbon column. Identification and accurate mass measurements of pepsin, an enzymatic protein with less number of basic amino acid residues were successfully demonstrated by matrix- assisted laser desorption ionization mass spectrometry (MALDI-MS). The molecular mass of pepsin was found to be 34,787 Da. Several decomposition products of pepsin, in m/z range of 3,500 to 4,700 were identified. Trypsin, an important endopeptidase enzyme had a mass of 46829.7 Da. Lower mass components with m/z 8047.5, 7776.6, 5722, 5446.2 and 5185 Da were also observed in trypsin spectrum. Both chemokine and growth factor recombinant proteins were mass analyzed as 8848.1 ± 3.5 and 16178.52 ± 4.1 Da, respectively. The accuracy of the measurements was in the range of 0.01 to 0.02%. Reduction and alkylation experiments on the chemokine showed the presence of six cysteines and three disulfide bonds. The two cysteines of the growth factor contained the free sulfhydryl groups and the accurate average mass of the

  10. The Low Temperature Oxidation of 2,7-Dimethyloctane in a Pressurized Flow Reactor

    NASA Astrophysics Data System (ADS)

    Farid, Farinaz

    n-decane resulted primarily in the formation of ethene near the NTC start, propene and isobutene were the major olefins produced from 2,7-DMO. A comparative analysis of experimental data with respect to a detailed chemical kinetic model for 2,7-DMO was performed and discrepancies were noted. Based on these results, a collaborative effort with Dr. Charles Westbrook (Lawrence Livermore National Laboratory) was initiated to refine the model predictions in the low temperature and NTC regimes. The effort resulted in an updated version of the 2,7-DMO mechanism, improving some of the key features such as calculated CO2 profile and final yields of iso-butene over the studied range of temperature. Fuel pyrolysis in the intermediate temperature regime, 850 -- 1000 K, also was investigated for the first time in the PFR facility. However, preliminary n-decane experiments measured only a small amount of fuel decomposition, indicating that higher temperature operation would be beneficial. The major species produced from n-decane decomposition, in descending order of molar fraction, were ethene, propene, and 1-butene. These results were compared with the predictions of two existing chemical kinetic models and the sources of variations between the experiments and the models as well as among the mechanisms were investigated. At 1000 K, the mechanisms predicted higher levels of fuel depletion and ethene production. Also, while the mechanisms were similar in their predicted pathways for fuel depletion and formation of ethene, inconsistencies were observed in relative contribution of these pathways to the final yields as well as the rate parameter determination for several sensitive reactions with respect to n-decane and ethene. Overall, the research aided in achieving a data set quantifying the oxidation characteristics of 2,7-DMO (and n-decane for comparison) as well as an elucidation of critical reaction pathways based on experimental results. Preliminary pyrolysis experiments were