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

  1. Electron collisions with 1-butene and 2-methylpropene molecules

    NASA Astrophysics Data System (ADS)

    Lopes, A. R.; Freitas, T. C.; Bettega, M. H. F.

    2015-07-01

    In this paper we report integral and differential cross sections for the elastic scattering of low-energy electrons by C4H8 isomers, namely 1-butene and 2-methylpropene. The scattering cross sections were obtained using the Schwinger multichannel method with pseudopotentials, in the static-exchange and in the static-exchange plus polarization approximations, for energies of the incident electron ranging from 0.5 eV to 15 eV. Our calculations indicate that the 1-butene molecule has a resonance in the A? symmetry at around 2.1 eV, in agreement with the experimental data of 2.3 eV as reported by Mozejko et al (2012 J. Phys. B 45 145203). The 2-methylpropene molecule has a resonance in the B2 symmetry, located at around 2.8 eV and also in good agreement with the experimental results of Mozejko et al around 2.4 eV. We also report differential cross sections around the energy of the broad structure present in the integral cross sections of both molecules, and discuss their oscillatory behavior in terms of the type of the molecular chain.

  2. Metabolism of 2-methylpropene (isobutylene) by the aerobic bacterium Mycobacterium sp. strain ELW1.

    PubMed

    Kottegoda, Samanthi; Waligora, Elizabeth; Hyman, Michael

    2015-03-01

    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

  3. Reduction of biogenic VOC sampling losses from ozone via trans-2-butene addition.

    PubMed

    Arnts, Robert R

    2008-10-15

    The continuous addition of trans-2-butene to air containing ozone-reactive volatile and semivolatile organic compounds prior to sampling on Tenax-TA adsorbent was found to be an effective means of removing ozone and reducing analyte losses of ozone reactive biogenic volatile organic compounds (BVOCs). To allow sufficient time for ozone scavenging to occur, the reacting mixture is passed through a heated (40 degrees C) coil of Sulfinert (Restek Corp., Bellefonte, PA) treated stainless steel tubing. The method was evaluated using a test mixture consisting of terpenes, terpenoid alcohols, and sesquiterpenes at part per trillion (pptv) levels in air in the presence of 100 parts per billion (ppbv) of ozone. The continuous addition of trans-2-butene to produce 600 ppm (ppmv) was found to be completely effective in controlling VOC losses on Tenax-TA as long as (1) sufficient time is allowed for the ozone scavenging to occur before the VOCs are adsorbed and (2) analyte enrichment on the adsorbentdoes not approach the hydroxyl radical scavenging capacity of the trans-2-butene. A manganese dioxide (MnO2) coated copper screen ozone scrubber was also tested and found to be of very limited utility. PMID:18983090

  4. Study of intradrystalline diffusion in zeolites communication 3. Kinetics of adsorption of trans-2-butene by NaA and NaMgA zeolites

    SciTech Connect

    Broddak, R.; Dubinin, M.M.; Falko, L.A.; Gorlov, V.A.; Kuhlmann, B.; Scholner, E.; Voloshchuk, A.M.

    1985-09-10

    This article studies the kinetics of adsorption of trans-2-butene by NaA zeolite with a varying crystal size, microcrystalline granulated NaA zeolite using granules of different sizes, and microcrystalline powdered Na/sub 8/Mg/sub 2/A zeolite. It is shown that the rate of adsorption is determined by the intracrystalline diffusion and that the effect of transfer in the transport pores and the final rate of dissipation of the heat of adsorption can be neglected. In adsorption of trans-2-butene by Na/sub 8/Mg/sub 2/A zeolite with a stepwise change in the pressure of the adsorbate, the kinetic curves are satisfactorily described by an internal diffusion equation for the kinetics of isothermal adsorption. The kinetics of adsorption were studied at 303 degrees K from the one-component vapor phase on a vacuum adsorption setup using quartz spring balance.

  5. 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.

  6. Anhydrous ferric chloride as an alkylation catalyst: The condensation of 2-methylpropene and benzene, preparation and identification of several fractions.

    E-print Network

    Mommessin, Pierre Robert

    1950-01-01

    'O x O O? o o ~O O I O O M M M ( O ? O C'l O --O I I + 1 O O I' DI. '&CUSSIQN Comparison o& the by-products formed by the condensation o. 2-methylpropene . . 'th benzene in the presence of anhydro:s ferric chloride - it!! those... . mer. CONCLUSIONS 1. When benzene is alkylated with 2-methylpropene in the presence of ferric chloride the following hydrocarbons can be identified among the products of the reaction: t-butylbenzene, t-amylbenzene, t-hexylbenzene, l-isopropy1-3-t...

  7. Application of the margin of exposure (MoE) approach to substances in food that are genotoxic and carcinogenic - example: 1-methylcyclopropene and its impurities (1-chloro-2-methylpropene and 3-chloro-2-methylpropene).

    PubMed

    Renwick, Andrew; Leblanc, Jean-Charles; Setzer, R Woodrow

    2010-01-01

    The chlorinated impurities of 1-methylcyclopropene possess weak mutagenicity and are carcinogenic in rodent bioassays. Dose-response modelling of the data for 1-chloro-2-methylpropene gave a BMDL10 for nasal carcinomas in male rats of 11 mg/kg-bw/day (after correction for the 5 days/week dosage schedule). No human exposure data are available and theoretical estimates had to be used to calculate the MoE. The MoEs ranged from 40,000 to 100,000,000 depending on the assumptions used in the exposure estimation. PMID:19786060

  8. Skeletal Isomerization of 1Butene on MCM-22 Zeolite Catalyst

    Microsoft Academic Search

    M. A. Asensi; A. Corma; A. Mart??nez

    1996-01-01

    The skeletal isomerization of 1-butene has been studied on two MCM-22 zeolite catalysts synthesized with different Si\\/Al ratios, i.e., 15 and 47, under a wide range of operating conditions. Product yields are a function ofn-butene conversion, and a maximum of isobutene yield is found at ca. 50% conversion. Besides isobutene, propylene and pentenes, which are formed by dimerization-cracking reactions, are

  9. Photodegradation of isotactic poly(1-butene): Multiscale characterization

    Microsoft Academic Search

    Lubomir Benicek; Lenka Chvatalova; Martin Obadal; Roman Cermak; Vincent Verney; Sophie Commereuc

    2011-01-01

    The effect of photodegradation in isotactic poly(1-butene) (PB-1) have\\u000a been investigated using rheology, differential scanning calorimetry and\\u000a infrared spectroscopy. Two commercially available grades of PB-1 with\\u000a different average molecular weight were chosen. Specimens prepared by\\u000a compression moulding were UV irradiated in the interval from 0 to 70 h.\\u000a UV-induced changes in molecular structure have been followed by\\u000a evolution of rheological

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...characteristic infrared spectra. (ii) Viscosity. Poly-1-butene resins and the...ethylene copolymers have an intrinsic viscosity 1.0 to 3.2 as determined by ASTM method...Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers,”...

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...characteristic infrared spectra. (ii) Viscosity. Poly-1-butene resins and the...ethylene copolymers have an intrinsic viscosity 1.0 to 3.2 as determined by ASTM method...Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers,”...

  12. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...characteristic infrared spectra. (ii) Viscosity. Poly-1-butene resins and the...ethylene copolymers have an intrinsic viscosity 1.0 to 3.2 as determined by ASTM method...Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers,”...

  13. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...characteristic infrared spectra. (ii) Viscosity. Poly-1-butene resins and the...ethylene copolymers have an intrinsic viscosity 1.0 to 3.2 as determined by ASTM method...Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers,”...

  14. 21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...characteristic infrared spectra. (ii) Viscosity. Poly-1-butene resins and the...ethylene copolymers have an intrinsic viscosity 1.0 to 3.2 as determined by ASTM method...Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers,”...

  15. Effect of molecular weight on the flow-induced crystallization of isotactic poly(1-butene)

    Microsoft Academic Search

    Stefano Acierno; Blandina Palomba; Henning H. Winter; Nino Grizzuti

    2003-01-01

    Turbidity measurements were used to characterize the effect of shear flow on the crystallization kinetics of several isotactic poly(1-butene) samples of different molecular weight (MW). Polymer melts were rapidly cooled below the nominal crystallization temperature, and subjected to a shear flow of varying shear rate but constant total deformation. While the quiescent crystallization was found to be essentially MW-independent, a

  16. Crystallization and phase transformation kinetics of poly(1-butene)\\/MWCNT nanocomposites

    Microsoft Academic Search

    Santosh D. Wanjale; Jyoti P. Jog

    2006-01-01

    Poly(1-butene)\\/MWCNT nanocomposites were prepared by simple melt processing technique. Crystallization, crystal-to-crystal phase transformation and spherulitic morphology were studied using differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and optical microscopy (OM). The non-isothermal crystallization exhibited higher values of Zt derived from Avrami theory and lower values of F(T) obtained from Avrami–Ozawa analysis, while the isothermal crystallization revealed a significant

  17. Physical characterization of poly(1Butene), hydrogenated terpenic resin, and their mixtures

    Microsoft Academic Search

    A. Vitale; E. Turati; M. Gallazzi; A. Seves; A. Bonfatti; G. Testa

    1999-01-01

    The physical and thermal characterizations of films of poly(1-butene) (PB-1) with an oligomer terpenic-based resin (Clearon P125), glassy at room temperature, were examined by optical microscopy, differential scanning calorimetry (DSC), and differential mechanical thermal analysis (DMTA). The Theological behavior of the molten mixtures was also examined. The results indicate that the Clearon P125 and PB-1 results in a one-phase system

  18. Investigation of the reaction of trimethylstannyl anionoids with 4-bromo-3,3-dimethyl-1-butene 

    E-print Network

    Sanchez, Robert Michael

    1985-01-01

    Page 15 16 20 22 VII 26 VIII 29 IX 29 32 XI 33 XI I XIII XIV 44 XVI XVI I 63 XVII I XIX LIST OF TABLES Table Mechanistic Components in the Reaction of Trimethyltinscdium with Alkyl Ha 1 ides in THF at 0 C. page Reaction of 6-Halo...-I-heptenes with Sodium Trirrethyltin in THF. 24 IV Reaction of Sodium Trimethyltin with 4-Bromo- 3, 3-dimethyl-1-butene in THF Reaction of Sodium Trisethyltin with 4-Bromo- 3, 3-dimethyl-l-butene in THF under Dilute Conditions 47 49 VI VII VIII Reaction...

  19. Skeletal isomerization of 1-butene on 12-tungstophosphoric acid supported on zirconia

    Microsoft Academic Search

    E. López-Salinas; J. G. Hernández-Cortéz; Ma. A. Cortés-Jácome; J. Navarrete; Ma. E. Llanos; A. Vázquez; H. Armendáriz; T. López

    1998-01-01

    A series of 0–25wt% H3[W12PO40] (TPA) impregnated on freshly precipitated Zr(OH)4 were prepared. The solids were characterized by a Hammett indicator method, specific surface area and pore size measurements, pyridine adsorption FTIR and later tested as catalysts in the isomerization of 1-butene. Maximum acid strength of 5–20wt% TPA\\/ZrO2 calcined at 673K is H0=?9.3, but dried samples (393K) showed near superacid

  20. Mass spectrum of the 1-butene-3-yne-2-yl radical (i-C4H3; X2A')

    NASA Astrophysics Data System (ADS)

    Guo, Ying; Gu, Xibin; Kaiser, Ralf I.

    2006-03-01

    The crossed molecular beams method has been applied to produce the 1-butene-3-yne-2-yl radical, i-C4H3(X2A') under single collision conditions via the reaction of dicarbon molecules with ethylene. We recorded time-of-flight spectra of the radical at the center-of-mass angle (28.0°) of the parent ion (m/z = 51; C4H3+) and of the fragments at m/z = 50 (C4H2+), m/z = 49 (C4H+), m/z = 48 (C4+), m/z = 39 (C3H3+), m/z = 38 (C3H2+), m/z = 37 (C3H+), and m/z = 36 (C3+). This yielded relative intensity ratios of I(m/z = 51):I(m/z = 50):I(m/z = 49):I(m/z = 48):I(m/z = 39):I(m/z = 38):I(m/z = 37):I(m/z = 36) = 0.47 +/- 0.01:0.94 +/- 0.01:1.0:0.07 +/- 0.02:0.31 +/- 0.01:0.23 +/- 0.02:0.24 +/- 0.01:0.12 +/- 0.01 at 70 eV electron impact energy. Upper limits at mass-to-charge ratios between 27 and m/z = 24 and m/z = 14-12 were derived to be 0.02 +/- 0.01. Note that the intensity of the 13C isotopic peak of the 1-butene-3-yne-2-yl radical at m/z = 52 (13C12C3H3+) is about 0.04 +/- 0.01 relative to m/z = 51. Employing linear scaling methods, the absolute electron impact ionization cross section of the 1-butene-3-yne-2-yl radical was computed to be 7.8 +/- 1.6 × 10-16 cm2. These data can be employed to monitor the 1-butene-3-yne-2-yl radical in oxygen-poor combustion flames and in the framework of prospective explorations of planetary atmospheres (Jupiter, Saturn, Uranus, Neptune, Pluto) and of their moons (Titan, Triton, Oberon) in situ via matrix interval arithmetic assisted mass spectrometry.

  1. 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, ?-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.

  2. Vapour–liquid equilibrium for the 1-butene + methanol, + ethanol, + 2-propanol, + 2-butanol and + 2-methyl-2-propanol systems at 326 K

    Microsoft Academic Search

    Marko Laakkonen; Juha-Pekka Pokki; Petri Uusi-Kyyny; Juhani Aittamaa

    2003-01-01

    A total pressure measurement approach leading to pTz data, that is treated using the method of Barker (1953) to provide pTxy data, has been used to determine isothermal vapour–liquid equilibria for five binary systems 1-butene+methanol, + ethanol, + 2-propanol, + 2-butanol and + 2-methyl-2-propanol at 326K. Error analysis of the measured results has been presented. All systems exhibited positive deviation

  3. AlCl3-Promoted Facile E-to-Z Isomerization Route to (Z)-2-Methyl-1-buten-1,4-ylidene Synthons for Highly Efficient and Selective (Z)-Isoprenoid Synthesis

    PubMed Central

    Wang, Guangwei; Negishi, Ei-ichi

    2013-01-01

    Zr-catalyzed methylalumination of 3-butyn-1-ols followed by AlCl3-promoted stereoisomerization at 50 °C for 6 h provides 4-iodo-3-methyl-3-buten-1-ols 2b and 6 of ?98 Z configuration in 87 and 67% yields, respectively. (Z)-1,4-Diiodo-2-methyl-1-butene (1b) obtainable by iodination of 2b is a valuable synthon for efficient and selective syntheses of (Z)-alkene containing isoprenoids. PMID:24307863

  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. Sum frequency generation vibrational spectroscopy of 1,3-butadiene hydrogenation on 4 nm Pt@SiO2, Pd@SiO2, and Rh@SiO2 core-shell catalysts.

    PubMed

    Krier, James M; Michalak, William D; Cai, Xiaojun; Carl, Lindsay; Komvopoulos, Kyriakos; Somorjai, Gabor A

    2015-01-14

    1,3-Butadiene (1,3-BD) hydrogenation was performed on 4 nm Pt, Pd, and Rh nanoparticles (NPs) encapsulated in SiO2 shells at 20, 60, and 100 °C. The core-shells were grown around polyvinylpyrrolidone (PVP) coated NPs (Stöber encapsulation) prepared by colloidal synthesis. Sum frequency generation (SFG) vibrational spectroscopy was performed to correlate surface intermediates observed in situ with reaction selectivity. It is shown that calcination is effective in removing PVP, and the SFG signal can be generated from the metal surface. Using SFG, it is possible to compare the surface vibrational spectrum of Pt@SiO2 (1,3-BD is hydrogenated through multiple paths and produces butane, 1-butene, and cis/trans-2-butene) to Pd@SiO2 (1,3-BD favors one path and produces 1-butene and cis/trans-2-butene). In contrast to Pt@SiO2 and Pd@SiO2, SFG and kinetic experiments of Rh@SiO2 show a permanent accumulation of organic material. PMID:25272243

  6. 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

    2011-01-01

    Reactions of hydroxyl (OH) radicals with 1-butene (k{sub 1}), trans-2-butene (k{sub 2}), and cis-2-butene (k{sub 3}) 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, (CH{sub 3}){sub 3}?CO?OH, and monitored by narrow-line width ring dye laser absorption of the well-characterized R{sub 1}(5) line of the OH A?X (0, 0) band near 306.7 nm. OH time histories were modeled using a comprehensive C{sub 5} 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.

  7. Anhydrous ferric chloride as an alkylation catalyst: The condensation of 2-methylpropene and benzene, preparation and identification of several fractions. 

    E-print Network

    Mommessin, Pierre Robert

    1950-01-01

    ". . Ch!. :?. Soc. , Ql, 35(1 (ig2o) PHOCEDI'HE Two stages could be distinguished in the proce- dure: the preparati . n of the arh-'drous ferric chloride and the condensation of benzene with 2-methyipropene. I, PHEPAHATIO!' OI' AH!D'DHOUS I'CHIC C...:!c chloride was sublimed into the flask and the side arm was sealed a, ca' culated amount of anhy- drous benzene wa "- introduces! t'. rough the tos of the con!e?scr (10) from the senar;tory i'u?s el (11). The ferric chloride-be?ze. ' e mixture was stir...

  8. [Os{sub 2}(CO){sub 8}({mu}{sub 2}-{eta}{sup 1},{eta}{sup 1}-propene)] and related complexes as vibrational models for alkenes chemisorbed on single-crystal metal surfaces

    SciTech Connect

    Anson, C.E.; Sheppard, N.; Bender, B.R.; Norton, J.R.

    1999-01-27

    The FTIR spectra of [Os{sub 2}(CO){sub 8}({mu}{sub 2}-{eta}{sup 1},{eta}{sup 1}-C{sub 2}H{sub 3}CH{sub 3})] and of its methyl-d{sub 3} and d{sub 6} isotopologues have been measured and assigned. Comparison of these vibrational data with previously published EELS and RAIRS studies of propene chemisorbed on Pt(111) and Ni(111) at low temperatures indicates that, on these surfaces, the propene species are chemisorbed via a ({mu}{sub 2}-P{eta}{sup 1},{eta}{sup 1}-C{sub 2}H{sub 3}CH{sub 3}) bonding mode. However, differences in the intensity patterns between the spectra of the adsorbed species compared with that of the model compound imply additional twisting or tilting with respect to the surface. Assignment of the FTIR spectra of the corresponding 1-butene and trans-2-butene complexes [Os{sub 2}(CO){sub 8}({mu}{sub 2}-{eta}{sup 1},{eta}{sup 1}-C{sub 2}H{sub 3}C{sub 2}H{sub 5})] and [Os{sub 2}(CO){sub 8}({mu}{sub 2}{eta}{sup 1},{eta}{sup 1}-CH{sub 3}C{sub 2}H{sub 2}CH{sub 3})] indicates similar bonding modes for chemisorbed 1-butene and trans-2-butene on Pt(111). Infrared data for the mononuclear propene complex [Os(CO){sub 4}({eta}{sup 2}-C{sub 2}H{sub 3}CH{sub 3})], on the other hand, are in good agreement with published EEL data for propene on Ru(0001) and Rh(111), indicating that at low temperatures on these surfaces, propene is chemisorbed as a methyl-substituted metallacyclopropane-like species. These bonding modes are analogous to those established for low-temperature ethene chemisorption on these surfaces.

  9. Effects of Beijing Olympics control measures on reducing reactive hydrocarbon species.

    PubMed

    Min, Shao; Bin, Wang; Sihua, Lu; Bin, Yuan; Ming, Wang

    2011-01-15

    Stringent air-quality control measures were implemented for the 2008 Beijing Olympic Games. This large-scale manmade experiment provided an opportunity to evaluate the effectiveness of measures to reduce the reactivity of hydrocarbons (HCs) from emission sources, which is important for ground-level ozone abatement. Photochemical initial concentrations (PICs), i.e., the levels of HCs from sources before undergoing chemical reactions, were calculated from ambient measurements. PICs obtained using the ratio method for HCs and the sequential reaction model for alkyl nitrates were in good agreement. Propene, 1-butene, iso-butene, trans-2-butene, cis-2-butene, trans-2-pentene, and m,p-xylene were identified as key reactive species in terms of their photochemical consumptions and correspondent ozone formation potentials (OFPs). During the Olympics and Paralympics, the PICs of these seven species were reduced by 27-66%, contributing 20% to the reduction in total PICs and 60% to the reduction in total OFP compared with June levels. Source apportionments from the chemical mass balance model indicated that gasoline vehicle exhaust was the predominant contributor to the key reactive species (45-78%). Reductions of gasoline vehicle exhaust during the Olympics and Paralympics explained 53-77% and 59-68% of the reductions in PICs of the key reactive HCs and total OFP, respectively. PMID:21128631

  10. 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.

  11. Equilibrium and Fixed Bed Adsorption of 1?Butene, Propylene and Propane Over 13X Zeolite Pellets

    Microsoft Academic Search

    Nabil Lamia; Luc Wolff; Philibert Leflaive; Pedro Sá Gomes; Carlos A. Grande; Alírio E. Rodrigues

    2008-01-01

    Propylene?propane separation is one of the most difficult and demanding energetic operation currently practiced using cryogenic distillation. Extensive studies on various alternatives showed that cyclic adsorption processes, and particularly pressure swing adsorption (PSA), might be an option to replace the traditional distillation. In spite of the promising results of the PSA process, much attention is currently being paid to the

  12. Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes. Progress report, April 1, 1988--March 31, 1989

    SciTech Connect

    Norton, J.R.

    1989-01-01

    We have obtained a neutron diffraction data set for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). While the structure is still being solved, it is already clear that the hybridization at both of the ethylene carbons is sp{sup 3}. Our first interpretation of our liquid crystal NMR results had suggested a very acute H-C-H angle. We have also obtained {sup 13}C liquid crystal data for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). Liquid crystal NMR ({sup 13}C as well as {sup 1}H) spectra have been obtained for Os(CO){sub 4}(C{sub 2}H{sub 4}) and its solution structure determined, in order to test our methodology on a molecule with a rigid structure. The normal modes of Os(CO){sub 4}({mu}-C{sub 2}H{sub 4}) and its deuterated and {sup 13}C-labelled isotopomers have been completely assigned. A partial vibrational analysis of Os{sub 2}(CO){sub 8}({mu}-propene), Os{sub 2}(CO){sub 8}(trans-2-butene), and Os{sub 2}(CO){sub 8}(1-butene) has been completed. We have prepared Os(CO){sub 4}({mu}-CH{sub 2}CH{sub 2}CH{sub 2}) and its 3,3-dideuterio analog. In the course of this work the reaction of Na{sub 2}Os(CO){sub 4} with a number of 1,3-propanediol derivatives has been examined. 1,3-Propanediol ditosylate afforded much better yields of the osmacycle than did either the ditriflate or diiodide. 2,2-Dideutero-1,3-propanediol ditosylate was used to prepare the deuterium-labelled osmacyclobutane.

  13. Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes

    SciTech Connect

    Norton, J.R.

    1989-01-01

    We have obtained a neutron diffraction data set for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). While the structure is still being solved, it is already clear that the hybridization at both of the ethylene carbons is sp{sup 3}. Our first interpretation of our liquid crystal NMR results had suggested a very acute H-C-H angle. We have also obtained {sup 13}C liquid crystal data for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). Liquid crystal NMR ({sup 13}C as well as {sup 1}H) spectra have been obtained for Os(CO){sub 4}(C{sub 2}H{sub 4}) and its solution structure determined, in order to test our methodology on a molecule with a rigid structure. The normal modes of Os(CO){sub 4}({mu}-C{sub 2}H{sub 4}) and its deuterated and {sup 13}C-labelled isotopomers have been completely assigned. A partial vibrational analysis of Os{sub 2}(CO){sub 8}({mu}-propene), Os{sub 2}(CO){sub 8}(trans-2-butene), and Os{sub 2}(CO){sub 8}(1-butene) has been completed. We have prepared Os(CO){sub 4}({mu}-CH{sub 2}CH{sub 2}CH{sub 2}) and its 3,3-dideuterio analog. In the course of this work the reaction of Na{sub 2}Os(CO){sub 4} with a number of 1,3-propanediol derivatives has been examined. 1,3-Propanediol ditosylate afforded much better yields of the osmacycle than did either the ditriflate or diiodide. 2,2-Dideutero-1,3-propanediol ditosylate was used to prepare the deuterium-labelled osmacyclobutane.

  14. The synthesis and application of novel Ni(II) N-alkyl dipyridylaldiminato complexes as selective ethylene oligomerisation catalysts.

    PubMed

    Swarts, Andrew J; Mapolie, Selwyn F

    2014-07-14

    A series of N-alkyl 2,2'-dipyridylamine ligands of general formula (2-C5H3NR)2NR', (a): R = H, R' = Me; (b): R = H, R' = benzyl; (c): R = H, R' = methylcyclohexyl; (d): R = H, R' = neopentyl; (e): R = Me, R' = Me) were prepared by a modified method involving base-mediated N-alkylation with the respective alkyl halide. Reaction of the ligands, a-e, with NiCl2(DME) allowed for the isolation of ?-Cl Ni(ii) complexes: [Ni(?-Cl){a}Cl]2 (1a); [Ni(?-Cl){b}Cl]2 (1b); [Ni(?-Cl){c}Cl]2 (1c); [Ni(?-Cl){d}Cl]2 (1d) and [Ni(?-Cl){e}Cl]2 (1e). The complexes were characterised by FT-IR spectroscopy, magnetic susceptibility measurements, mass spectrometry, elemental analyses and in the case of 1a, SCD analysis. In the case of complex 1e, an acid-mediated hydrolysis process was identified. The product of hydrolysis, the protonated ligand and a tetrachloronickelate salt (1e-A), was characterised by SCD analysis. Activation of 1a-1e with alkyl aluminium reagents generated highly active catalysts for the oligomerisation of ethylene, with activities of up to 864 kgoligomers molNi(-1) h(-1) and high selectivity toward the formation of butenes. In general, trans 2-butene was observed as the major isomer, with the exception of 1e. In the case of 1e, the selectivity for 1-butene was 98%, thereby demonstrating the significant effect that the introduction of a low degree of steric pressure in the coordination sphere of the catalyst has on selectivity. PMID:24848302

  15. Fluid inclusion volatile analysis by gas chromatography with photoionization/micro-thermal conductivity detectors: Applications to magmatic MoS sub 2 and other H sub 2 O-CO sub 2 and H sub 2 O-CH sub 4 fluids

    SciTech Connect

    Bray, C.J.; Spooner, E.T.C. (Univ. of Toronto, Ontario (Canada))

    1992-01-01

    Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated on-line crushing, helium carrier gas, a single porous polymer column, two temperature programmed conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID), and off-line digital peak processing. In order of retention time these volatile peaks are: N{sub 2}, Ar, CO, CH{sub 4}, CO{sub 2}, C{sub 2}H{sub 4}, C{sub 2}H{sub 6}, C{sub 2}H{sub 2}, COS, C{sub 3}H{sub 6}, C{sub 3}H{sub 8}, C{sub 3}H{sub 4} (propyne), H{sub 2}O, SO{sub 2} {plus minus} iso-C{sub 4}H{sub 10} {plus minus} C{sub 4}H{sub 8} (1-butene) {plus minus} CH{sub 3}SH, C{sub 4}H{sub 8} (iso-butylene), ( ) C{sub 4}H{sub 6} (1,3 butadiene), and {plus minus} n-C{sub 4}H{sub 10} {plus minus}C{sub 4}H{sub 8} (trans-2-butene). H{sub 2}O is analyzed directly. O{sub 2} can be analyzed cryogenically between N{sub 2} and Ar, but has not been detected in natural samples to date in this study. Initial inclusion volatile analyses of fluids of interpreted magmatic origin from the Cretaceous Boss Mtn. monzogranite stock-related MoS{sub 2} deposit, central British Columbia of 97 mol% H{sub 2}O, 3% CO{sub 2}, 140-150 ppm N{sub 2}, and 16-39 ppm CH{sub 4} are reasonable in comparison with high temperature volcanic gas analyses from four, active calc-alkaline volcanoes, e.g., the H{sub 2}O contents of volcanic gases from the White Island (New Zealand), Mount St. Helens (Washington, USA), Merapi (Bali, Indonesia), and Momotombo (Nicaragua) volcanoes are 88-95%, > 90%, 88-95% and 93%, respectively; CO{sub 2} contents are 3-10%, 1-10%, 3-8%, and 3.5%. It appears that low, but significant concentrations of alkanes, alkenes, and alkynes have been detected in magmatically derived fluids.

  16. 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.

  17. Effects of biomass burning on summertime nonmethane hydrocarbon concentrations in the Canadian wetlands

    NASA Technical Reports Server (NTRS)

    Blake, D. R.; Smith, T. W., Jr.; Chen, T.-Y.; Whipple, W. J.; Rowland, F. S.

    1994-01-01

    Approximately 900 whole air samples were collected and assayed for selected C2-C10 hydrocarbons and seven halocarbons during the 5-week Arctic Boundary Layer Expedition (ABLE) 3B conducted in eastern Canadian wetland areas. In more than half of the 46 vertical profiles flown, enhanced nonmethane hydrocarbon (NMHC) concentrations attributable to plumes from Canadian forest fires were observed. Urban plumes, also enhanced in many NMHCs, were separately identified by their high correlation with elevated levels of perchloroethene. Emission factors relative to ethane were determined for 21 hydrocarbons released from Canadian biomass burning. Using these data for ethane, ethyne, propane, n-butane, and carbon monoxide enhancements from the literature, global emissions of these four NMHCs were estimated. Because of its very short atmospheric lifetime and its below detection limit background mixing ratio, 1,3-butadiene is an excellent indicator of recent combustion. No statistically significant emissions of nitrous oxide, isoprene, or CFC 12 were observed in the biomass-burning plumes encountered during ABLE 3B. The presence of the short-lived biogenically emitted isoprene at altitudes as high as 3000 m implies that mixing within the planetary boundary layer (PBL) was rapid. Although background levels of the longer-lived NMHCs in this Canadian region increase during the fire season, isoprene still dominated local hydroxyl radical photochemistry within the PBL except in the immediate vicinity of active fires. The average biomass-burning emission ratios for hydrocarbons from an active fire sampled within minutes of combustion were, relative to ethane, ethene, 2.45; ethyne 0.57; propane, 0.25; propene, 0.73; propyne, 0.06; n-butane, 0.09; i-butane, 0.01; 1-butene, 0.14; cis-2-butene, 0.02; trans-2-butene, 0.03; i-butylene, 0.07; 1,3-butadiene, 0.12; n-pentane, 0.05; i-pentane, 0.03; 1-pentene, 0.06; n-hexane, 0.05; 1-hexene, 0.07; benzene, 0.37; toluene, 0.16.

  18. Evaluation of non-methane hydrocarbon (NMHC) emissions based on an ambient air measurement in Tokyo area, Japan

    NASA Astrophysics Data System (ADS)

    Matsunaga, Sou N.; Chatani, Satoru; Morikawa, Tazuko; Nakatsuka, Seiji; Suthawaree, Jeeranut; Tajima, Yosuke; Kato, Shungo; Kajii, Yoshizumi; Minoura, Hiroaki

    2010-12-01

    Non-methane hydrocarbons (NMHCs) are known to have an important role on air quality due to their high reactivity. NMHC analysis has been performed on 148 ambient air samples collected at five different sites in the Kanto area (Tokyo metropolitan area and surrounding six prefectures) of Japan in summer and winter of 2008, and fifty NMHCs have been determined and quantified. A field measurement campaign has been conducted at one of the busiest intersections in Tokyo metropolitan area in winter of 2008. NMHC emissions are evaluated through comparison of distributions of individual NMHCs emitted from motor vehicles, which are estimated from the measurements, with those determined from the current emissions inventory. The comparison revealed that the measured distributions of acetylene, ethylene and toluene showed a good agreement with those estimated from the emissions inventory (the values estimated from the measurements are a factor of 1.5, 0.56 and 2.3 larger than the emissions inventory in median, respectively), however, propane and isobutane are found to be significantly underestimated in the emissions inventory (the measured values were a factor of 18 and 5.1 larger than the emissions inventory, respectively). The significant underestimate of propane can be explained by that the current emissions inventory does not consider emissions from liquefied propane gas (LPG) fueled vehicles. However, for isobutane, reasons for the underestimate are still unclear. Another field measurement has been conducted in summer of 2008, where the air samples have been collected at three different sites on the ground and by a helicopter as well. Remarkable high concentrations of 1-butene and cis- and trans-2-butenes have been sporadically observed in the samples collected at Urayasu in the coastal area of Tokyo bay. Calculated propylene equivalent (PE) concentrations of butenes revealed that those have a significantly important role in ozone formation when the air plume is affected by emissions from their emission sources. The PE concentrations of butenes varied from 0.1 to 39 ppbC, and accounted for 1.5-75% of total PE concentrations at Urayasu. Most of the continuous air quality monitoring stations does not record concentrations of individual hydrocarbons, therefore, the importance of reactive and low concentration hydrocarbon such as butenes might be overlooked in the current emissions inventory and/or air quality model. In this paper, the reliability of NMHC emissions is evaluated based on the field measurements. Their possible impacts on air quality in the Kanto area are discussed as well, based on the calculated propylene equivalent concentrations.

  19. Mechanism of carbon-carbon bond formation in the reaction of 1,2-disubstituted alkenes with a cationic bridging methylidyne iron complex

    SciTech Connect

    Casey, C.P.; Meszaros, M.W.; Marder, S.R.; Fagan, P.J.

    1984-06-13

    Two independent lines of evidence are presented to establish that the reaction of ((C/sub 5/H/sub 5/)/sub 2/(CO)/sub 2/Fe/sub 2/(..mu..-CO)(..mu..-CH))/sup +/PF/sub 6//sup -/ cis-2-butene and trans-2-butene, and 1-methyl cyclohexane, occurs by hydrocarbation followed by equilibration. 9 references.

  20. Transferable Potentials for Phase Equilibria. 4. United-Atom Description of Linear and Branched Alkenes and Alkylbenzenes

    SciTech Connect

    WICK,COLLIN D.; MARTIN,MARCUS G.; SIEPMANN,J. ILJA

    2000-07-12

    The Transferable Potentials for Phase Equilibria-United Atom (TraPPE-UA) force field for hydrocarbons is extended to alkenes and alkylbenzenes by introducing the following pseudo-atoms: CH{sub 2}(sp{sup 2}), CH(sp{sup 2}), CH(aro), R-C(aro) for the link to aliphatic side chains, and C(aro) for the link of two benzene rings. In this united-atom force field, the nonbonded interactions of the hydrocarbon pseudo-atoms are solely governed by Lennard-Jones 12-6 potentials, and the Lennard-Jones well depth and size parameters for the new pseudo-atoms were determined by fitting to the single-component vapor-liquid phase equilibria of a few selected model compounds. Configurational-bias Monte Carlo simulations in the NVT version of the Gibbs ensemble were carried out to calculate the single-component vapor-liquid coexistence curves for ethene, propene, 1-butene, trans- and cis-2-butene. 2-methylpropene, 1,5-hexadiene, 1-octene, benzene, toluene, ethylbenzene, propylbenzene, isopropylbenzene, o-, m-, and p-xylene, and naphthalene. The phase diagrams for the binary mixtures of (supercritical) ethene/n-heptane and benzene/n-pentane were determined from simulations in the NpT Gibbs ensemble. Although the TraPPE-UA force field is rather simple and makes use of relatively few different pseudo-atoms, its performance, as judged by comparisons to other popular force fields and available experimental data, is very satisfactory.

  1. 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...

  2. Carbene reactions produced by recoil excitation methods 

    E-print Network

    Lowery, Kirby

    1968-01-01

    by irradiation of samples in the presence of two competitors. Using ethylene as the standard in each case and using other olefins such as propylene, l-butene, isobutylene, cis-2-butene, and trans-2- butene, Tang and Rowland showed that the reactivity... Company in 99. 9! purity. The other gases used were obtained from The Matheson Company in research grade. Propane, isobutylene, methyl bromide, and methyl chloride had purity of greater than 99. 5X. Ethyl chloride, ethylene, isobutylene, pro- 13...

  3. Kinetics of nonisothermal adsorption by biporous adsorbents. Communication 6. Description of kinetic adsorption curves with account of the temperature dependence of the intracrystalline diffusion coefficients

    SciTech Connect

    Broddak, R.; Voloshchuk, A.M.; Gorlov, V.A.; Dubinin, M.M.; Kochirzhik, M.

    1987-01-10

    An analytical description has been given of the kinetic adsorption curves with account of the influence of the change in adsorbent temperature due to the evolution of heat and adsorption on the coefficient of intracrystalline diffusion of the adsorbate. The deviation of the experimental kinetic curves for the adsorption of trans-2-butene by finely crystalline NaA zeolite from those calculated from the equation of isothermal diffusion is due to the influence of temperature on the coefficient of intracrystalline diffusion.

  4. Polybutenes

    ERIC Educational Resources Information Center

    Daniels, D. J.; And Others

    1973-01-01

    Discusses the use of aluminum chloride and other Friedel-Crafts type catalysts to polymerize 2-methylpropene and the application of such products in industry and agriculture. Includes a laboratory experiment on the polybutene preparation suitable for high school purposes. (CC)

  5. Vibrational C-H overtone spectroscopy and bond distances of butenes dissolved in liquid Xe

    NASA Astrophysics Data System (ADS)

    Lopez-Calvo, Alfredo; Diez-y-Riega, Helena; Manzanares, Carlos E.

    2009-10-01

    Vibrational overtone spectra of isobutene, cis-2-butene, and trans-2-butene dissolved in liquid xenon at 163 K, have been recorded between 5000 and 16500 cm -1. Spectral regions for the first four overtones were measured using a Fourier transform spectrophotometer. The fifth overtone (? ? = 6) spectra were recorded with a double beam (pump-probe) thermal lens technique. Band deconvolution allowed isolation of individual transitions. Local-mode parameters were calculated for C-H oscillators in solution and compared with gas phase local-mode parameters. Density functional theory calculations were done to obtain C-H bond lengths and vibrational frequencies for the three butene isomers. Frequency shifts (? ?) with respect to gas phase results are attributed to changes in harmonic frequency and anharmonicity of the particular C-H bond of the sample dissolved in the inert liquid solvent.

  6. 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.

  7. Efficient large (ca. 40 g) laboratory scale preparation of ( S)- and ( R)-valine tert-butyl esters

    Microsoft Academic Search

    Victor P. Krasnov; Galina L. Levit; Iraida M. Bukrina; Alexander M. Demin; Oleg N. Chupakhin; Ji Uk Yoo

    2002-01-01

    A large laboratory scale (ca. 40 g) method for the preparation of enantiomerically pure (S)- and (R)-valine tert-butyl esters has been developed. The method involves three steps: preparation of N-TFA-valines, preparation of valine tert-butyl esters using 2-methylpropene in dioxane in the presence of sulfuric acid, and isolation of the target compounds as the acetate derivative. The overall yield is up

  8. H2SO4 formation from the gas-phase reaction of stabilized Criegee Intermediates with SO2: Influence of water vapour content and temperature

    NASA Astrophysics Data System (ADS)

    Berndt, Torsten; Jokinen, Tuija; Sipilä, Mikko; Mauldin, Roy L.; Herrmann, Hartmut; Stratmann, Frank; Junninen, Heikki; Kulmala, Markku

    2014-06-01

    The importance of gas-phase products from alkene ozonolysis other than OH radicals, most likely stabilized Criegee Intermediates (sCI), for the process of atmospheric SO2 oxidation to H2SO4 has been recently discovered. Subjects of this work are investigations on H2SO4 formation as a function of water vapour content (RH = 2-65%) and temperature (278-343 K) starting from the ozonolysis of trans-2-butene and 2,3-dimethyl-2-butene (TME). H2SO4 production other than via the OH radical reaction was attributed to the reaction of SO2 with sCI, i.e. acetaldehyde oxide arising from trans-2-butene ozonolysis and acetone oxide from TME. Measurements have been conducted in an atmospheric pressure flow tube using NO3--CI-APi-TOF mass spectrometry for H2SO4 detection. The sCI yields derived from H2SO4 measurements at 293 K were 0.49 ± 0.22 for acetaldehyde oxide and 0.45 ± 0.20 for acetone oxide. Our findings indicate a H2SO4 yield from sCI + SO2 of unity or close to unity. The deduced rate coefficient ratio for the reaction of sCI with H2O and SO2, k(sCI + H2O)/k(sCI + SO2), was found to be strongly dependent on the structure of the Criegee Intermediate, for acetaldehyde oxide at 293 K: (8.8 ± 0.4)·10-5 (syn- and anti-conformer in total) and for acetone oxide: <4·10-6. H2SO4 formation from sCI was pushed back with rising temperature in both reaction systems most probably due to an enhancement of sCI decomposition. The ratio k(dec)/k(sCI + SO2) increased by a factor of 34 (acetone oxide) increasing the temperature from 278 to 343 K. In the case of acetaldehyde oxide the temperature effect is less pronounced. The relevance of atmospheric H2SO4 formation via sCI + SO2 is discussed in view of its dependence on the structure of the Criegee Intermediate.

  9. Supporting Information Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2011

    E-print Network

    Stoltz, Brian M.

    stannane 50,3 4-iodo-2-methyl-1-butene (54),4 and vinyl boronate ester 565 were prepared according to known gas. Tetrahydrofuran was distilled directly over benzophenone and sodium, or else was dried by passage

  10. Conjugation of isoprene monoepoxides with glutathione, catalyzed by ?, ?, ? and ?-class glutathione S-transferases of rat and man

    Microsoft Academic Search

    Jan J. P Bogaards; Joke C Venekamp; Florence G. C Salmon; Peter J van Bladeren

    1999-01-01

    In the present study, the enzymatic conjugation of the isoprene monoepoxides 3,4 epoxy-3-methyl-1-butene (EPOX-I) and 3,4-epoxy-2-methyl-1-butene (EPOX-II) with glutathione was investigated, using purified glutathione S-transferases (GSTs) of the ?, ?, ? and ?-class of rat and man. HPLC analysis of incubations of EPOX-I and EPOX-II with [35S]glutathione (GSH) showed the formation of two radioactive fractions for each isoprene monoepoxide. The

  11. Synthesis and biological activity of new conformationally restricted analogues of pepstatin.

    PubMed

    Szewczuk, Z; Rebholz, K L; Rich, D H

    1992-01-01

    A new statine derivative, 3-hydroxy-4-amino-5-mercaptopentanoic acid; cysteinylstatine (CySta), was synthesized and used to prepare a series of conformationally restricted analogues of pepstatin (Iva-Val-Val-Sta-Ala-Sta) in which the conformational constraint was introduced via a bis-sulfide connecting the appropriately substituted residues in the P1 and the P3 inhibitor side chains. The precursor peptide, Iva-Cys-Val-CySta-Ala-Iaa, was synthesized and alkylated with a series of dibromoalkanes and alkenes to produce the cyclic structures. This strategy permitted the carbon atom spacing between the P1 and the P3 inhibitor side chains to be systematically varied so as to produce inhibitors with 15-, 16-, and 17-membered ring systems. Additional non-cyclic analogues were synthesized as controls by alkylating the bisthiol intermediates with methyl iodide. The inhibitory potency of the analogues were determined against porcine pepsin and penicillopepsin by using standard enzyme kinetic assays. The cyclic inhibitor were found to be potent inhibitors of both aspartic proteases; inhibitor that contained a trans-2-butene link between the two sulfur atoms was found to be the most potent inhibitor with a Ki less than 1 nM against pepsin and 3.94 nM against penicillopepsin. This series of compounds illustrates a new type of conformational restriction that can be used to probe for the bioactive conformation of peptides. PMID:1478780

  12. 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. [Pittsford Mendon High School, NY (United States)

    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.

  13. 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.

  14. 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.

  15. An extended baseline examination of indoor VOCs in a city of low ambient pollution: Perth, Western Australia

    NASA Astrophysics Data System (ADS)

    Maisey, S. J.; Saunders, S. M.; West, N.; Franklin, P. J.

    2013-12-01

    This study of indoor air quality reports VOC concentrations in 386 suburban homes located in Perth Western Australia, a city of low ambient pollution and temperate climate. Details of indoor VOC concentrations, temperature, relative humidity, and information on house characteristics and occupant activities were collected during the sampling periods. The concentration of VOCs observed in typical homes was low and individual compounds rarely exceeded 5 ?g m-3. Median individual VOC concentrations ranged from 0.06 ?g m-3 for 1,1,1 trichloroethane and butyl ether to 26.6 ?g m-3 for cis/trans 2-butene. Recently renovated homes had higher concentrations of VOCs than non renovated homes, including ?VOCs (p = 0.026), ?BTEX (p = 0.03), ?xylene (p = 0.013), toluene (p = 0.05), cyclohexane (p = 0.039), and propyl benzene (p = 0.039). Statistical analyses showed house age and attached garages were not significant factors for any of the VOCs tested. The concentrations of indoor VOCs in Perth were lower than overseas observations and those reported in recent Australian studies, with inferences made to differences in the climate and the occupant behaviour. The results are a baseline profile of indoor VOCs over the period 2006-2011, in an Australian city of low population density and of generally low ambient pollution.

  16. Hydrocarbation: addition of the C-H bond of a cataionic bridging iron-methylidyne complex to alkenes

    SciTech Connect

    Casey, C.P.; Fagan, P.J.

    1982-09-08

    A slurry of the red iron-methylidyne complex, (cis-Cp/sub 2/Fe/sub 2/(CO)/sub 2/(..mu..-CO)(..mu..-CH))/sup +/PF/sub 6//sup -/, Cp=eta-C/sub 5/H/sub 5/), in dichloromethane was stirred under an ethylene atmosphere and warmed from -78/sup 0/C to room temperature, a maroon crystalline product was formed. Evaporation of the solvent in vacuo followed by recrystallization of the product from acetone-ether produced (cis-Cp/sub 2/Fe/sub 2/(CO)/sub 2/(..mu..-CO)(..mu..-CCH/sub 2/-CH/sub 3/))/sup +/PF/sub 6//sup -/. The reaction was monitored by HNMR spectroscopy. The time for 50% conversion was ca 15 min at -20 C. No detectable intermediates or side reactions were noted. Reactions of the complex with propylene, 2-methylpropene, hexenes, and cycloalkenes are discussed.

  17. Association of chemically induced forestomach cell proliferation and carcinogenesis.

    PubMed

    Ghanayem, B I; Maronpot, R R; Matthews, H B

    1986-09-01

    A number of chemicals have been shown to cause malignant neoplasms in the forestomach of Fischer 344 rats when administered chronically by gavage. The present study was designed to identify early forestomach lesions following 2-week repeated gavage administration of some of these forestomach carcinogens. In this manner, we attempted to examine the hypothesis that early cell proliferation is associated with repetitive gavage administration of these chemicals. Groups of 8 or more male F344 rats received 1 of 6 reported forestomach carcinogens (ethyl acrylate (EtAc), diglycidyl resorcinol ether(DGRE), 1,2-dibromoethane (DBE), 1,2-dibromo-3-chloro-propane (DBCP), 1-chloro-2-methylpropene (dimethylvinyl chloride, DMVC) and 3-chloro-2-methylpropene (CMP)), 1 of 2 structurally related chemicals (methyl methacrylate (MMA) and dichloroethane (DCE)) which were negative in chronic carcinogenicity studies or the vehicle (corn oil) alone 5 days/week for 2 weeks. Histopathologic examination of forestomachs of rats killed 24 h after the last dose indicated no significant difference in the incidence or severity of epithelial cell proliferation in the rat forestomach between the vehicle control group and the 2 negative control groups. In contrast, the incidence and severity of epithelial cell proliferation of the rat forestomach in every group treated with a forestomach carcinogen was significantly higher than the incidence in the vehicle or negative control groups. These results suggest that early epithelial cell proliferation of the forestomach may be associated with at least some chemicals that induce forestomach neoplasia following chronic administration by gavage. PMID:3768853

  18. 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...

  19. 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.

  20. 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.

  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 standard for benzene in China. PMID:24640890

  2. Hydrosilylation of n-alkenes and allyl chloride over platinum supported on styrene–divinylbenzene copolymer

    Microsoft Academic Search

    Agata Wawrzy?czak; Micha? Dutkiewicz; Jacek Guli?ski; Hieronim Maciejewski; Bogdan Marciniec; Ryszard Fiedorow

    2011-01-01

    Catalytic performance of styrene–divinylbenzene copolymer-supported platinum catalyst of high crosslinking degree and high surface area was studied in reactions of hydrosilylation of allyl chloride, 1-octene and 1-butene. The catalyst has shown considerably greater stability of catalytic activity than classical active carbon-supported catalyst. In experiments on repeated use of catalysts, the decrease in catalytic activity for hydrosilylation of liquid double bond-containing

  3. Heats of formation and steric hindrance in three hydrocarbon polymers 

    E-print Network

    Hayes, Claude William

    1966-01-01

    (ethylene), poly(propylene), and poly(1- butene) have been measured and heats of formation comparedtovalues predicted by bond energy schemes. Heats of polymerization have 27 been derived using previous heat of combustion data (by flame calorimetry) on monomers... of polymerization are calculated using the 12 entropies of polymerization of Dainton and Ivin. Heats and Gibbs energy of polymerization show that in unbranched a'-olefins both of the reaction-potential terms lower gradually and asymptotically to a constant...

  4. Homolytic carbon to phosphorus bond scission of some phosphonates catalyzed by bacterial carbon-phosphorus lyase

    Microsoft Academic Search

    V. Vandepitte; W. Verstraete

    1995-01-01

    The production of volatile degradation products of phosphonates was monitored to investigate the mechanism involved in the biodegradation of propylphosphonic acid and phenylphosphonic acid byRhizobium sp MMM101a. The biodegradation of propylphosphonic acid gave rise to the production, in decreasing order, of propane, methane, ethane, 1-butene, propene, isobutene, butane and ethene. The formation of these degradation products was strongly reduced by

  5. Kinetic measurements on elementary fossil fuel combustion reactions over wide temperature ranges

    SciTech Connect

    Fontijn, A.

    1991-01-01

    The goals of this work are to provide accurate data on the temperature dependence of the kinetics of elementary combustion reactions (i) for use by combustion modelers, and (ii) to gain a better fundamental understanding of, and hence predictive ability for, the chemistry involved. In this reporting period our work on the O + Hcl reaction was published, experimental work on the O + benzene and O + 1-butene reactions was completed, and measurements on the O + isobutene reaction were initiated.

  6. Oxidative dehydrogenation of C 4 hydrocarbons over VMgO catalyst — kinetic investigations

    Microsoft Academic Search

    Angeliki A. Lemonidou

    2001-01-01

    The oxidative dehydrogenation (ODH) of n-butane, butenes and butadiene over VMgO catalyst containing 30wt.% V2O5 was investigated. Reactivity of hydrocarbons in ODH decreases in the order 2-butenes>1-butene>n-butane?butadiene. Butenes are easily converted, exhibiting a 64% selectivity to butadiene while a small part 5% is isomerized. The intermediate products (butenes, butadiene and carbon monoxide) were added to the feed in order to

  7. The hydrocarbon emission rates of tea-leafed willow ( Salix phylicifolia), silver birch ( Betula pendula) and European aspen ( Populus tremula)

    Microsoft Academic Search

    Hannele Hakola; Janne Rinne; Tuomas Laurila

    1998-01-01

    The monoterpene, isoprene, and light hydrocarbon emission rates of tea-leafed willow (Salix phylicifolia), aspen (Populus tremula), and silver birch (Betula pendula) were measured during the growing season 1996 in the boreal vegetation zone using a dynamic flow-through technique. All tree species had significant (2.8–10?gg (dry weight)-1h-1) monoterpene emission rates when leaves were young in May. In addition, willow emitted 1-butene,

  8. Theoretical investigations of the thermochemistry, structures, and internal rotation of conjugated polyynes

    Microsoft Academic Search

    Peter D. Jarowski

    2006-01-01

    Chapter 1 discusses the thermochemistry of conjugated double and triple bonds. The conjugation stabilization energies of dienes and diynes are considerably larger than estimates based on heat of hydrogenation differences between 1,3-butadiyne and 1-butyne as well as between 1,3-butadiene and 1-butene. Such comparisons do not take into account the counterbalancing hyperconjugative stabilization of the partially hydrogenated products by their ethyl

  9. Replacing precious metals with carbide catalysts for hydrogenation reactions

    DOE PAGESBeta

    Ruijun, Hou [Tsinghua Univ., Beijing (China). Beijing Key Lab. of Green Chemical Reaction Engineering and Technology; Columbia Univ., New York, NY (United States); Chen, Jingguang G. [Columbia Univ., New York, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States); Chang, Kuan [Tsinghua Univ., Beijing (China). Beijing Key Lab. of Green Chemical Reaction Engineering and Technology; Wang, Tiefeng [Tsinghua Univ., Beijing (China). Beijing Key Lab. of Green Chemical Reaction Engineering and Technology

    2015-04-01

    Molybdenum carbide (Mo?C and Ni/Mo?C) catalysts were compared with Pd/SiO? for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO?, Mo?C 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 Mo?C could be completely regenerated by H? treatment at 723 K for the three molecules. The Ni modified Mo?C 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 Mo?C catalysts, 8.6%Ni/Mo?C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO?. Compared to Pd/SiO?, both Mo?C and Ni/Mo?C 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.

  10. 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

  11. Replacing precious metals with carbide catalysts for hydrogenation reactions

    DOE PAGESBeta

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

    2015-04-01

    Molybdenum carbide (Mo?C and Ni/Mo?C) catalysts were compared with Pd/SiO? for the hydrogenation of several diene molecules, 1,3- butadiene, 1,3- and 1,4-cyclohexadiene (CHD). Compared to Pd/SiO?, Mo?C 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 Mo?C could be completely regenerated by H? treatment at 723 K for the three molecules. The Ni modified Mo?C 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 Mo?C catalysts, 8.6%Ni/Mo?C showed the highest selectivity to 1-butene, which was even higher selectivity than that over Pd/SiO?. Compared to Pd/SiO?, both Mo?C and Ni/Mo?C 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

  12. A glutathione S-transferase with activity towards cis-1, 2-dichloroepoxyethane is involved in isoprene utilization by Rhodococcus sp. strain AD45.

    PubMed

    van Hylckama Vlieg, J E; Kingma, J; van den Wijngaard, A J; Janssen, D B

    1998-08-01

    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

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

    NASA Astrophysics Data System (ADS)

    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 (kOH) for the reaction under investigation was then obtained and compared with the only available data at this temperature.

  14. 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 (kOH) for the reaction under investigation was then obtained and compared with the only available data at this temperature. PMID:25933898

  15. Conversion of methanol to light olefins on SAPO-34: kinetic modeling and reactor design 

    E-print Network

    Al Wahabi, Saeed M. H.

    2005-02-17

    -pentene...................................62 Figure IV-8. Single event rate coefficients for elementary cracking steps. Curve (a): 2,2-diMe-4-hexyl R+ into 1-butene and 2-Me-2- propyl R+. Curve (b): 2,2,4-triMe-4-pentyl R+ into isobutylene and 2-Me-2....3 Total 100.0 100.0 Olefins Yields, wt% Ethylene 6.1 0.8 Propylene 21.0 4.9 Isobutylene 5.1 1.9 Total butylenes 14.3 8.1 II.3 Paraffins Dehydrogenation Propane dehydrogenation technology has gained importance in recent years due...

  16. Fischer-Tropsch synthesis in the slurry phase on iron catalysts 

    E-print Network

    Brown, Russell Floyd

    1986-01-01

    conductivity 40 minutes '0 O 0 0 0 o 2 0 '0 Ll 9 2 H 8. A o g Q Ni Valve Snitch Propane Propylene Iso-butane N-Butane I-Butane Isobutylene ~ Trans-2-butane Ctg-2-butane Valve Suicch Ethylene Ethane Valve Snitch 0 2 N CH... Propylene Propane 1-Butene n-Butane 1-Pentene n-Pentane 1-Hexene n-Hexane CO+CHg C02 Start Air Ocl 0 I CI '0 O 0 I 0 9 I 0 P 0 0 0 'a I '0 0 Q. 0 ttethanol Acetaldehyde C& Aldehyde/Ketone 1-Propanol Ethanol Water 1-Butanol...

  17. Histrionicotoxins: Roentgen-Ray Analysis of the Novel Allenic and Acetylenic Spiroalkaloids Isolated from a Colombian Frog, Dendrobates histrionicus

    Microsoft Academic Search

    John W. Daly; Isabella Karle; Charles W. Myers; Takashi Tokuyama; James A. Waters; Bernhard Witkop

    1971-01-01

    The structures and absolute configuration of two unique alkaloids isolated from the Colombian frog, Dendrobates histrionicus, have been elucidated by Roentgen-ray (x-ray) crystallography. Histrionicotoxin is (2pR, 6S, 7pS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis -2-penten-4-ynyl)-1-azaspiro[5.5] undecane, while in dihydro-isohistrionicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent. Dendrobates histrionicus exhibits remarkable interpopulational variations in amounts and composition of skin toxins,

  18. The catalytic oxidation of propylene: investigation of catalyst activity. 

    E-print Network

    Woodham, John Frank

    1953-01-01

    as that of the stabilised oatalyst, The work of Brettonj Wan and &odge (6) involved the oxidation of n-butanes 1-butenes 2-butene~ isobutylenes and Ip5 butadiene in the vapor phase over various silver and silver oxide catalysts and over vanadium pentoxide catalyst... of carbon dioxide and water. The study of the oxidation of the four-oarbon hydrocarbons over vanadium pentoxide catalyst is of considerable interest sinoe it is one of the few systematio studies recorded in the literature cf the oxidation oi' a group...

  19. The biotransformation of isoprene and the two isoprene monoepoxides by human cytochrome P450 enzymes, compared to mouse and rat liver microsomes

    Microsoft Academic Search

    Jan J. P. Bogaards; Joke C. Venekamp; Peter J. van Bladeren

    1996-01-01

    The metabolism of isoprene was investigated with microsomes derived from cell lines expressing human CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, or CYP3A4. The formation of epoxide metabolites was determined by gas Chromatographic analysis. CYP2E1 showed the highest rates of formation of the isoprene monoepoxides 3,4-epoxy-3-methyl-1-butene (EPOX-I) and 3,4-epoxy-2-methyl-1-butène (EPOX-II), followed by CYP2B6. CYP2E1 was the only enzyme showing detectable

  20. Figure A1 Time-series of N1 fan speed (% of maximum) and exhaust gas temperature for experiments conducted (a) 4% load, (b) 7% (c) 30% and (d) 85% engine loads. Warm-up and

    E-print Network

    Meskhidze, Nicholas

    ,3,5-trimethylbenzene 14.4 1.0 2-ethyltoluene 12.6 34.2 1,2,4- trimethylbenzene/tert- butylbenzene 41.9 7.4 1.9 hexylbenzene 16.6 a ARO2 1,2,4,5- tetramethylbenzene 27.2 a propene 696.2 6.3 1-butene 194.6 2.2 1-pentene 91,2,3-trimethylbenzene 47.0 1.7 1,3-diethylbenzene 10.2 1.8 1,4-diethylbenzene 46.7 1.9 1,2-diethylbenzene 10.9 1

  1. Ring-expansion reactions in the thermal decomposition of tert-butyl-1,3-cyclopentadiene.

    PubMed

    McGivern, W Sean; Manion, Jeffrey A; Tsang, Wing

    2006-11-30

    The thermal decomposition of tert-butyl-1,3-cyclopentadiene has been investigated in single-pulse shock-tube studies at shock pressures of 182-260 kPa and temperatures of 996-1127 K. Isobutene (2-methylpropene), 1,3-cyclopentadiene, and toluene were observed as the major stable products in the thermolysis of dilute mixtures of the substrate in the presence of a free-radical scavenger. Hydrogen atoms were also inferred to be a primary product of the decomposition and could be quantitatively determined on the basis of products derived from the free-radical scavenger. Of particular interest is the formation of toluene, which involves the expansion of the ring from a five- to a six-membered system. The overall reaction mechanism is suggested to include isomerization of the starting material; a molecular elimination channel; and C-C bond fission reactions, with toluene formation occurring via radical intermediates formed in the latter pathway. These radical intermediates are analogous to those believed to be important in soot formation reactions occurring during combustion. Molecular and thermodynamic properties of key species were determined from G3MP2B3 quantum chemistry calculations and are reported. The temperature dependence of the product spectrum was fit with a detailed chemical kinetic model, and best-fit kinetic parameters were derived using a Nelder-Mead simplex minimization algorithm. Our mechanism and rate constants are consistent with and provide experimental support for the H-atom-assisted routes to the conversion of fulvene to benzene that have been proposed in the literature on the basis of theoretical investigations. PMID:17125296

  2. Determination Of The Barriers To Internal Rotation Of Some Molecules With Two C3v Rotors By Far Infrared Fourier Transform Infrared (FTIR) Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rizzolo, J. J.; Guirgis, G.; Durig, J. R.

    1981-10-01

    Many molecules with two internal C3v rotors have been shown to have "rich" far infrared spectra. Barriers calculated in early studies used approximation methods derived from theoretical work done in the field of microwave spectroscopy. At most, only two Fourier coefficients of the potential function could be determined which allowed interpretation and assignment of only a few of the usually large number of spectral features found in the far infrared region. It is apparent that this approach of treating the semi-rigid model, based on the use of tabulated perturbation sums, is not at all sufficient to explain the commonly very "rich" torsional far infrared spectra. These early methods were not capable of extracting all of the information about the potential functions of these molecules. In a recent series of papers, we have demonstrated how far infrared interferometry and laser Raman spectroscopy may be combined with modern computing techniques to determine three or more Fourier coefficients of the potential function in two variables and to interpret most or all of the features observed in the far infrared spectral region of such two-top molecules. We have recorded the far infrared spectra of dimethylsulfide, dimethylselenide, 1-chloro-2-methylpropene, cis-dimethyloxirane, and trans-dimethyloxirane on a far infrared interferometer at a resolution of 0.25 cm-1. A large amount of torsional data have been obtained and the observed transitions have been assigned on the basis of the semi-rigid model. The barriers to internal rotation have been calculated and, for several of the molecules, both the cosine-cosine and sine-sine coupling terms have been obtained.

  3. Beta-H transfer from the metallacyclobutane: a key step in the deactivation and byproduct formation for the well-defined silica-supported rhenium alkylidene alkene metathesis catalyst.

    PubMed

    Leduc, Anne-Marie; Salameh, Alain; Soulivong, Daravong; Chabanas, Mathieu; Basset, Jean-Marie; Copéret, Christophe; Solans-Monfort, Xavier; Clot, Eric; Eisenstein, Odile; Böhm, Volker P W; Röper, Michael

    2008-05-14

    The surface complex [([triple bond]SiO)Re([triple bond]CtBu)(=CHtBu)(CH2tBu)] (1) is a highly efficient propene metathesis catalyst with high initial activities and a good productivity. However, it undergoes a fast deactivation process with time on stream, which is first order in active sites and ethene. Noteworthy, 1-butene and pentenes, unexpected products in the metathesis of propene, are formed as primary products, in large amount relative to Re (>1 equiv/Re), showing that their formation is not associated with the formation of inactive species. DFT calculations on molecular model systems show that byproduct formation and deactivation start by a beta-H transfer trans to the weak sigma-donor ligand (siloxy) at the metallacyclobutane intermediate having a square-based pyramid geometry. This key step has an energy barrier slightly higher than that calculated for olefin metathesis. After beta-H transfer, the most accessible pathway is the insertion of ethene in the Re-H bond. The resulting pentacoordinated trisperhydrocarbyl complex rearranges via either (1) alpha-H abstraction yielding the unexpected 1-butene byproduct and the regeneration of the catalyst or (2) beta-H abstraction leading to degrafting. These deactivation and byproduct formation pathways are in full agreement with the experimental data. PMID:18402448

  4. Trace gas emissions from laboratory biomass fires measured by open-path Fourier transform infrared spectroscopy: Fires in grass and surface fuels

    NASA Astrophysics Data System (ADS)

    Goode, Jon G.; Yokelson, Robert J.; Susott, Ronald A.; Ward, Darold E.

    1999-09-01

    The trace gas emissions from six biomass fires, including three grass fires, were measured using a Fourier transform infrared (FTIR) spectrometer coupled to an open-path, multipass cell (OP-FTIR). The quantified emissions consisted of carbon dioxide, nitric oxide, water vapor, carbon monoxide, methane, ammonia, ethylene, acetylene, isobutene, methanol, acetic acid, formic acid, formaldehyde, and hydroxyacetaldehyde. By including grass fires in this study we have now measured smoke composition from fires in each major vegetation class. The emission ratios of the oxygenated compounds, formaldehyde, methanol, and acetic acid, were 1-2% of CO in the grass fires, similar to our other laboratory and field measurements but significantly higher than in some other studies. These oxygenated compounds are important, as they affect O3 and HOx chemistry in both biomass fire plumes and the free troposphere. The OP-FTIR data and the simultaneously collected canister data indicated that the dominant C4 emission was isobutene (C4H8) and not 1-butene. The rate constant for the reaction of isobutene with the OH radical is 60% larger than that of 1-butene. We estimate that 67±9% of the fuel nitrogen was volatilized with the major nitrogen emissions, ammonia, and nitric oxide, accounting for 22±8%.

  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. Intercomparison of Hantzsch and fiber-laser-induced-fluorescence formaldehyde measurements

    NASA Astrophysics Data System (ADS)

    Kaiser, J.; Li, X.; Tillmann, R.; Acir, I.; Holland, F.; Rohrer, F.; Wegener, R.; Keutsch, F. N.

    2014-06-01

    Two gas-phase formaldehyde (HCHO) measurement techniques, a modified commercial wet-chemical instrument based on Hantzsch fluorimetry and a custom-built instrument based on fiber laser-induced fluorescence (FILIF), were deployed at the atmospheric simulation chamber SAPHIR (Simulation of Atmospheric PHotochemistry In a large Reaction Chamber) to compare the instruments' performances under a range of conditions. Thermolysis of para-HCHO and ozonolysis of 1-butene were used as HCHO sources, allowing for calculations of theoretical HCHO mixing ratios. Calculated HCHO mixing ratios are compared to measurements, and the two measurements are also compared. Experiments were repeated under dry and humid conditions (RH < 2% and RH > 60%) to investigate the possibility of a water artifact in the FILIF measurements. The ozonolysis of 1-butene also allowed for the investigation of an ozone artifact seen in some Hantzsch measurements in previous intercomparisons. Results show that under all conditions the two techniques are well correlated (R2 ? 0.997), and linear regression statistics show measurements agree with within stated uncertainty (15% FILIF + 5% Hantzsch). No water or ozone artifacts are identified. While a slight curvature is observed in some Hantzsch vs. FILIF regressions, the potential for variable instrument sensitivity cannot be attributed to a single instrument at this time. Measurements at low concentrations highlight the need for a secondary method for testing the purity of air used in instrument zeroing and the need for further FILIF White cell outgassing experiments.

  7. Volatile organic compound constituents from an integrated iron and steel facility.

    PubMed

    Tsai, Jiun-Horng; Lin, Kuo-Hsiung; Chen, Chih-Yu; Lai, Nina; Ma, Sen-Yi; Chiang, Hung-Lung

    2008-09-15

    This study measured the volatile organic compound (VOC) constituents of four processes in an integrated iron and steel industry; cokemaking, sintering, hot forming, and cold forming. Toluene, 1,2,4-trimethylbenzene, isopentane, m,p-xylene, 1-butene, ethylbenzene, and benzene were the predominant VOC species in these processes. However, some of the chlorinated compounds were high (hundreds ppbv), i.e., trichloroethylene in all four processes, carbon tetrachloride in the hot forming process, chlorobenzene in the cold forming process, and bromomethane in the sintering process. In the sintering process, the emission factors of toluene, benzene, xylene, isopentane, 1,2,4-trimethylbenzene, and ethylbenzene were over 9 g/tonne-product. In the vicinity of the manufacturing plant, toluene, isopentane, 1,2,4-trimethylbenzene, xylene and ethylbenzene were high. Toluene, 1,2,4-trimethylbenzene, xylene, 1-butene and isopentane were the major ozone formation species. Aromatic compounds were the predominant VOC groups, constituting 45-70% of the VOC concentration and contributing >70% to the high ozone formation potential in the stack exhaust and workplace air. The sequence of VOC concentration and ozone formation potential was as follows: cold forming>sintering>hot forming>cokemaking. For the workplace air, cokemaking was the highest producer, which was attributed to the fugitive emissions of the coke oven and working process release. PMID:18289777

  8. 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.

  9. Radiation-induced effects in polymers and related compounds. Final report

    SciTech Connect

    Silverman, J.

    1980-04-01

    The report is divided into two sections. The first section covers progress during the final contract period April 1, 1978-October 31, 1979; it covers work performed in conjunction with the objectives of the contract, some of which was recently completed. The second section is a general summary of the contract activities and accomplishments over the 19 year period covered by AEC-ERDA-DOE support. Studies completed or still in progress since April 1, 1979 are: ESR measurements on alkyl single crystals; work on polymer composites; studies on styrene-polyethylene grafts; experiments on the use of torque rheometry as a means of measuring the effects of ionizing radiation on polymers; investigations on the melting and crystallization behavior of irradiated polymers; and pulse radiolysis of poly(1-butene) and polyethylene.

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

    DOEpatents

    Thoma, Steven G. (Albuquerque, NM); Nenoff, Tina M. (Albuquerque, NM)

    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.

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

    SciTech Connect

    Steen, E. van; Schnobel, M.; O`Connor, C.T. [Univ. of Cape Town, Rondebosch (South Africa)

    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.

  12. A remarkable shape-catalytic effect of confinement on the rotational isomerization of small hydrocarbons

    SciTech Connect

    Santiso, Erik E [ORNL; Gubbins, Keith E [ORNL; Buongiorno Nardelli, Marco [ORNL

    2008-01-01

    As part of an effort to understand the effect of confinement by porous carbons on chemical reactions, we have carried out density functional theory calculations on the rotational isomerization of three four-membered hydrocarbons: n-butane, 1-butene, and 1,3-butadiene. Our results show that the interactions with the carbon walls cause a dramatic change on the potential energy surface for pore sizes comparable to the molecular dimensions. The porous material enhances or hinders reactions depending on how similar is the shape of the transition state to the shape of the confining material. The structure of the stable states and their equilibrium distributions are also drastically modified by confinement. Our results are consistent with a doubly exponential behavior of the reaction rates as a function of pore size, illustrating how the shape of a catalytic support can dramatically change the efficiency of a catalyst. (51 refs.)

  13. Recent Progress in Electron Impact Experiments in Hefei

    NASA Astrophysics Data System (ADS)

    Zhu, Lin-Fan; Chen, Xiang-Jun; Shan, Xu; Xu, Ke-Zun

    2009-05-01

    Using a new-built high-resolution multichannel (e,2 e) spectrometer and a fast high-resolution electron energy loss spectrometer, the electron momentum spectra for some molecules and the electron energy loss spectra for noble atoms were measured at an impact energy of 2500 eV. Then the orbital assignments and the spin-orbit interactions for the outer valence molecular orbitals, as well as the dynamic behaviors for the valence excitation process of noble atoms, were investigated. In addition, the recent experiment on 1-butene shows that electron momentum spectroscopy is feasible to determine the Boltzmann-weighted abundances and thus to predict the relative stability for different conformers.

  14. Histrionicotoxins: Roentgen-Ray Analysis of the Novel Allenic and Acetylenic Spiroalkaloids Isolated from a Colombian Frog, Dendrobates histrionicus

    PubMed Central

    Daly, John W.; Karle, Isabella; Myers, Charles W.; Tokuyama, Takashi; Waters, James A.; Witkop, Bernhard

    1971-01-01

    The structures and absolute configuration of two unique alkaloids isolated from the Colombian frog, Dendrobates histrionicus, have been elucidated by Roentgen-ray (x-ray) crystallography. Histrionicotoxin is (2pR, 6S, 7pS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis-2-penten-4- ynyl)-1-azaspiro[5.5] undecane, while in dihydro-isohistrionicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent. Dendrobates histrionicus exhibits remarkable interpopulational variations in amounts and composition of skin toxins, in behavior, and in phenotypic characters, aspects of which are illustrated in a color plate. The histrionico-toxins are the third class of alkaloids isolated from the defensive skin secretions of Neotropical (Dendrobatidae) frogs. Images PMID:5288773

  15. Histrionicotoxins: roentgen-ray analysis of the novel allenic and acetylenie spiroalkaloids isolated from a Colombian frog, Dendrobates histrionicus.

    PubMed

    Daly, J W; Karle, I; Myers, C W; Tokuyama, T; Waters, J A; Witkop, B

    1971-08-01

    The structures and absolute configuration of two unique alkaloids isolated from the Colombian frog, Dendrobates histrionicus, have been elucidated by Roentgen-ray (x-ray) crystallography. Histrionicotoxin is (2pR, 6S, 7pS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis-2-penten-4- ynyl)-1-azaspiro[5.5] undecane, while in dihydro-isohistrionicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent. Dendrobates histrionicus exhibits remarkable interpopulational variations in amounts and composition of skin toxins, in behavior, and in phenotypic characters, aspects of which are illustrated in a color plate. The histrionico-toxins are the third class of alkaloids isolated from the defensive skin secretions of Neotropical (Dendrobatidae) frogs. PMID:5288773

  16. Infrared Laser Generation Of Heterogeneous Catalysts And Laser-Induced Reactions At Catalytic Surfaces

    NASA Astrophysics Data System (ADS)

    Danen, Wayne C.; Cheng, , Sheng-San; Iyer, Pradeep K.; Chiou, Shane-Jaw

    1984-05-01

    It has been demonstrated that continuous wave infrared CO2 laser radiation can be util-ized to rapidly produce active catalysts from inert precursors. The activity and selectiv-ity of Ca0 produced from Ca(OH)2 for the isomerization of 1-butene to cis- and trans-2-but-ene is discussed. Variation of the laser irradiation time produces catalytic activity and selectivity qualitatively similar to that resulting from conventional calcination at different temperatures. Pulsed infrared laser-induced reactions at catalytic surfaces are also discussed with emphasis on the dehydrobromination of 2-bromopropane and ethylene elimination from glycine ethyl ester hydrochloride at BaSO4 , A1PO4, and similar surfaces. Correlations are made of the extent of reaction with various experimental parameters including nature of the catalyst, laser frequency, laser fluence, number of laser pulses, and reagent-catalyst ratio.

  17. Platinacycloalkane complexes containing [P,N] bidentate ligands: synthesis and decomposition studies.

    PubMed

    Mahamo, Tebello; Moss, John R; Mapolie, Selwyn F; Smith, Gregory S; Slootweg, J Chris; Lammertsma, Koop

    2014-04-14

    A new series of platinacyclopentanes (2a-2f) and platinacycloheptanes (3a-3f) of the type [Pt(N^P)(CH2)n] (n = 4, 6) were obtained by the reaction of [Pt(COD)(CH2)n] with the appropriate iminophosphine ligand (1a-1f). These complexes were characterised using a variety of spectroscopic and analytical techniques. X-ray structure analysis of complex 2a revealed a slightly distorted square planar geometry around platinum as a consequence of the ring strain imposed by the [P,N] chelate ring formed and the metallocycloalkane. Thermal decomposition analyses of the platinacycloalkanes revealed that the platinacyclopentanes are markedly stable, with the decomposition reaction requiring temperatures higher than 100 °C to occur. The major products obtained from the thermal decomposition reactions were 1-butene (for platinacyclopentanes) and 1-hexene (for platinacycloheptanes). PMID:24549177

  18. Theoretical and kinetic study of the reaction of ethyl methyl ketone with HO2 for T = 600-1600 K. Part II: addition reaction channels.

    PubMed

    Zhou, Chong-Wen; Mendes, Jorge; Curran, Henry J

    2013-06-01

    The temperature and pressure dependence of the addition reaction of ethyl methyl ketone (EMK) with HO2 radical has been calculated using the master equation method employing conventional transition state theory estimates for the microcanonical rate coefficients in the temperature range of 600-1600 K. Geometries, frequencies, and hindrance potentials were obtained at the B3LYP/6-311G(d,p) level of theory. A modified G3(MP2,CC) method has been used to calculate accurate electronic energies for all of the species involved in the reactions. The rigid-rotor harmonic oscillator approximation has been used for all of the vibrations except for the torsional degrees of freedom which are being treated as 1D hindered rotors. Asymmetric Eckart barriers were used to model tunneling effect in a one-dimensional reaction coordinate through saddle points. Our calculated results show that the four reaction channels forming 1-buten-2-ol + HO2 radical (R5), 2-buten-2-ol + HO2 radical (R10), acetic acid + ethylene + OH radical (R13), and 2-methyl-2-oxetanol + OH radical (R15) are the dominant channels. When the temperature is below 1000 K, the reaction R15 forming the cyclic ether, 2-methyl-2-oxetanol, is dominant while the reaction R13 forming acetic acid + ethylene + OH radical becomes increasingly dominant at temperatures above 1000 K. The other two channels forming 1-buten-2-ol, 2-buten-2-ol, and HO2 radical are not dominant but are still important product channels over the whole temperature range investigated here. No pressure dependence has been found for the reaction channels forming 2-methyl-2-oxetanol + OH radical and acetic acid + ethylene + OH radical. A slightly negative pressure dependence has been found for the reaction channels producing the two butenols. Rate constants for the four important reaction channels at 1 atm (in cm(3) mol(-1) s(-1)) are k(R5) = 2.67 × 10(15) × T(-1.32)exp(-16637/T), k(R10) = 1.62 × 10(8) × T(0.57)exp(-13142/T), k(R13) = 2.29 × 10(17) × T(-1.66)exp(-18169/T), and k(R15) = 6.17 × 10(-2) × T(3.35)exp(-10136/T). A comparison of the total rate constants for the addition of HO2? radical to EMK and that for H-atom abstraction by HO2? radical from EMK has also been carried out. We find that the abstraction reaction channels are dominant over the entire temperature range of 600-1600 K. PMID:23590522

  19. Conjugation of isoprene monoepoxides with glutathione, catalyzed by alpha, mu, pi and theta-class glutathione S-transferases of rat and man.

    PubMed

    Bogaards, J J; Venekamp, J C; Salmon, F G; van Bladeren, P J

    1999-01-01

    In the present study, the enzymatic conjugation of the isoprene monoepoxides 3,4 epoxy-3-methyl-1-butene (EPOX-I) and 3,4-epoxy-2-methyl-1-butene (EPOX-II) with glutathione was investigated, using purified glutathione S-transferases (GSTs) of the alpha, mu, pi and theta-class of rat and man. HPLC analysis of incubations of EPOX-I and EPOX-II with [35S]glutathione (GSH) showed the formation of two radioactive fractions for each isoprene monoepoxide. The structures of the EPOX-I and EPOX-II GSH conjugates were elucidated with 1H-NMR analysis. As expected, two sites of conjugation were found for both isoprene epoxides. EPOX-II was conjugated more efficiently than EPOX-I. In addition, the mu and theta class glutathione S-transferases were much more efficient than the alpha and pi class glutathione S-transferases, both for rat and man. Because the mu- and theta-class glutathione S-transferases are expressed in about 50 and 40-90% of the human population, respectively, this may have significant consequences for the detoxification of isoprene monoepoxides in individuals who lack these enzymes. Rat glutathione S-transferases were more efficient than human glu tathione S-transferases: rat GST T1-1 showed about 2.1-6.5-fold higher activities than human GST T1-1 for the conjugation of both EPOX-I and EPOX-II, while rat GST M1-1 and GST M2-2 showed about 5.2-14-fold higher activities than human GST M1a-1a. Most of the glutathione S-transferases showed first order kinetics at the concentration range used (50-2000 microM). In addition to differences in activities between GST-classes, differences between sites of conjugation were found. EPOX-I was almost exclusively conjugated with glutathione at the C4-position by all glutathione S-transferases, with exception of rat GST M1-1, which also showed significant conjugation at the C3-position. This selectivity was not observed for the conjugation of EPOX-II. Incubations with EPOX-I and EPOX-II and hepatic S9 fractions of mouse, rat and man, showed similar rates of GSH conjugation for mouse and rat. Compared to mouse and rat, human liver S9 showed a 25-50-fold lower rate of GSH conjugation. PMID:10190541

  20. The biotransformation of isoprene and the two isoprene monoepoxides by human cytochrome P450 enzymes, compared to mouse and rat liver microsomes.

    PubMed

    Bogaards, J J; Venekamp, J C; van Bladeren, P J

    1996-12-20

    The metabolism of isoprene was investigated with microsomes derived from cell lines expressing human CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, or CYP3A4. The formation of epoxide metabolites was determined by gas chromatographic analysis. CYP2E1 showed the highest rates of formation of the isoprene monoepoxides 3,4-epoxy-3-methyl-1-butene (EPOX-I) and 3,4-epoxy-2-methyl-1-butene (EPOX-II), followed by CYP2B6. CYP2E1 was the only enzyme showing detectable formation of the diepoxide of isoprene, 2-methyl-1,2:3,4-diepoxybutane. Both isoprene monoepoxides were oxidized by CYP2E1 to the diepoxide at similar enzymatic rates. In order to determine the relative role of CYP2E1 in hepatic metabolism, isoprene as well as the two monoepoxides were also incubated with a series of ten human liver microsomal preparations in the presence of the epoxide hydrolase inhibitor cyclohexene oxide. The obtained activities were correlated with activities towards specific substrates for CYP1A2, CYP2A6, CYP2C9, CYP2D6, CYP2E1 and CYP3A. The results were supportive for those obtained with single human P450 enzymes. Isoprene (monoepoxide) metabolism sowed a significant correlation with CYP2E1 activity, determined as chlorzoxazone 6-hydroxylation. CYP2E1 is therefore the major enzyme involved in hepatic metabolism of isoprene and the isoprene monoepoxides in vitro. To investigae species differences with regard to the role of epoxide hydrolase in the metabolism of isoprene monoepoxides, the epoxidation of isoprene by human liver microsomes was compared to that of mouse and rate liver microsomes. The amounts of monoepoxides formed as a balance between epoxidation and hydrolysis, was measured in incubations with and without the epoxide hydrolase inhibitor cyclohexene oxide. Inhibition of epoxide hydrolase resulted in similar rates of monoepoxide formation in mouse, rat and man. Without inhibitor, however, the total amount of monoepoxides present at the end of the incubation period was twice as high for mouse liver microsomes than for rat and even 15 times as high as for human liver microsomes. Thus, differences in epoxide hydrolase activity between species may be of crucial importance for the toxicity of isoprene in the various species. PMID:9021169

  1. Competitive hydrogenation of butadiene and butene on palladium and platinum catalysts

    SciTech Connect

    Ouchaib, T.; Massardier, J. Renouprez, A. (Institut de Recherche sur la Catalyse, Villeurbanne (France))

    1989-10-01

    In a recent study of the selective hydrogenation of butadiene to butenes, the reactivity of palladium (in the form of single crystals and of supported catalysts) was compared with that of platinum. The reactivity of single-crystal faces with (111) orientation is comparable to that of SiO{sub 2}-supported catalysts. The argument put forward to explain the comparatively lower activity of platinum was its lower hydrogen coverage under a given pressure, in the presence of the hydrocarbons, arising from a heat of adsorption smaller than that on palladium (respectively 67 and 85 kJ/mol). Concerning its poorer selectivity toward butenes, the reason invoked was a similar heat of adsorption for butadiene and butenes: the olefinic intermediate compound remains partly on the surface and the reaction proceeds to butane. A powerful kinetic method which is able to provide direct evidence for this different adsorption of dienes and butenes would be the competitive hydrogenation of these two molecules. However, to distinguish between the ethylenic hydrocarbon formed during the reaction and the molecules already present in the reactants, the experiments were performed according to the sequence: competitive hydrogenation of a butadiene-propene mixture followed by the hydrogenation of a 1-butene-propene mixture. This paper describes a study which confirms that the reason for the selectivity of palladium (after stabilization of the catalyst) can be attributed unambiguously to its capacity of adsorbing a diene more strongly than an alkene molecule.

  2. 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 ?(2)-L-type ligand. This functionality is exemplified by two ?(2)-N-?(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 ?-interactions in catalytic applications, this work should open new opportunities for ligand design involving the 1,4-azaborine motif as an arene substitute. PMID:24838444

  3. Fluid loss agents for oil well cementing composition

    SciTech Connect

    Savoly, A.; Villa, J.L.; Garvey, C.M.; Resnick, A.L.

    1987-06-23

    This patent describes a method of cementing a conduit in a borehole penetrating an earthen formation by introducing a cementing composition into the space. The cementing composition comprises: water; hydraulic cement; a water dispersible fluid loss additive comprised of a terpolymer of (1) from about 10 to about 75 weight percent of an acid selected from the group consisting of 2-acrylamido-2 methylpropane sulfonic acid, sodium vinyl sulfonate and vinyl benzene sulfonate; (2) from about 10 to 76 weight percent of a nonionic monomer selected from the group consisting of acrylamide, N,N-dimethylacrylamide, N-vinyl pyrrolidone, N-vinyl acetamide and dimethylamino ethyl methacrylate; and (3) from about 1 to 60 weight percent of an unsaturated polybasic acid selected from the group consisting of itaconic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, dimethylmuconic acid and 1-butene 2,3,4-tricarboxylic acid, the polymer having an average molecular weight of between about 200,000 and about 1,000,000 being in its free acid or partially or completely neutralized form and being at least water dispersible.

  4. Direct oxidation of hydrocarbons in a solid-oxide fuel cell

    PubMed

    Park; Vohs; Gorte

    2000-03-16

    The direct electrochemical oxidation of dry hydrocarbon fuels to generate electrical power has the potential to accelerate substantially the use of fuel cells in transportation and distributed-power applications. Most fuel-cell research has involved the use of hydrogen as the fuel, although the practical generation and storage of hydrogen remains an important technological hurdle. Methane has been successfully oxidized electrochemically, but the susceptibility to carbon formation from other hydrocarbons that may be present or poor power densities have prevented the application of this simple fuel in practical applications. Here we report the direct, electrochemical oxidation of various hydrocarbons (methane, ethane, 1-butene, n-butane and toluene) using a solid-oxide fuel cell at 973 and 1,073 K with a composite anode of copper and ceria (or samaria-doped ceria). We demonstrate that the final products of the oxidation are CO2 and water, and that reasonable power densities can be achieved. The observation that a solid-oxide fuel cell can be operated on dry hydrocarbons, including liquid fuels, without reforming, suggests that this type of fuel cell could provide an alternative to hydrogen-based fuel-cell technologies. PMID:10749204

  5. Direct oxidation of hydrocarbons in a solid-oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Park, Seungdoo; Vohs, John M.; Gorte, Raymond J.

    2000-03-01

    The direct electrochemical oxidation of dry hydrocarbon fuels to generate electrical power has the potential to accelerate substantially the use of fuel cells in transportation and distributed-power applications. Most fuel-cell research has involved the use of hydrogen as the fuel, although the practical generation and storage of hydrogen remains an important technological hurdle. Methane has been successfully oxidized electrochemically, but the susceptibility to carbon formation from other hydrocarbons that may be present or poor power densities have prevented the application of this simple fuel in practical applications. Here we report the direct, electrochemical oxidation of various hydrocarbons (methane, ethane, 1-butene, n-butane and toluene) using a solid-oxide fuel cell at 973 and 1,073 K with a composite anode of copper and ceria (or samaria-doped ceria). We demonstrate that the final products of the oxidation are CO2 and water, and that reasonable power densities can be achieved. The observation that a solid-oxide fuel cell can be operated on dry hydrocarbons, including liquid fuels, without reforming, suggests that this type of fuel cell could provide an alternative to hydrogen-based fuel-cell technologies.

  6. Contribution of carbonyl photochemistry to aging of atmospheric secondary organic aerosol.

    PubMed

    Mang, Stephen A; Henricksen, Dana K; Bateman, Adam P; Andersen, Mads P Sulbaek; Blake, Donald R; Nizkorodov, Sergey A

    2008-09-11

    The photodegradation of secondary organic aerosol (SOA) material by actinic UV radiation was investigated. SOA was generated via the dark reaction of ozone and d-limonene, collected onto quartz-fiber filters, and exposed to wavelength-tunable radiation. Photochemical production of CO was monitored in situ by infrared cavity ring-down spectroscopy. A number of additional gas-phase products of SOA photodegradation were observed by gas chromatography, including methane, ethene, acetaldehyde, acetone, methanol, and 1-butene. The absorption spectrum of SOA material collected onto CaF2 windows was measured and compared with the photolysis action spectrum for the release of CO, a marker for Norrish type-I photocleavage of carbonyls. Both spectra had a band at approximately 300 nm corresponding to the overlapping n --> pi* transitions in nonconjugated carbonyls. The effective extinction coefficient of freshly prepared SOA was estimated to be on the order of 15 L mol(-1) cm(-1) at 300 nm, implying one carbonyl group in every SOA constituent. The absorption by the SOA material slowly increased in the visible and near-UV during storage of SOA in open air in the dark, presumably as a result of condensation reactions that increased the degree of conjugation in the SOA constituents. These observations suggest that photolysis of carbonyl functional groups represents a significant sink for monoterpene SOA compounds in the troposphere, with an estimated lifetime of several hours over the continental United States. PMID:18700731

  7. Probing the mechanisms of enantioselective hydrogenation of simple olefins with chiral rhodium catalysts in the presence of anions

    PubMed

    Buriak; Klein; Herrington; Osborn

    2000-01-01

    The strong influence of various anions upon the hydrogenation of 2-phenyl-1-butene, catalyzed by chiral rhodium catalysts was investigated. Both sulfonates and halides exert large increases in the enantioselectivity when [Rh[(-)-bdpp](NBD)]ClO4 (bdpp = 2,4-bis(diphenylphosphino)pentane, NBD = 2,5-norbornadiene) is used as the catalyst precursor at high pressures (70 atm) of dihydrogen in nonpolar solvents. A dihydride mechanism similar to that for Wilkinson's catalyst [RhCl(PPh3)3] was shown to be operating at both high- and low-pressure conditions through a combination of catalytic studies, 31P, 1H and parahydrogen-induced polarization (PHIP) NMR experiments. With sulfonate and in neat methanol, however, a mechanistic switch takes place from a dihydride route (dihydrogen addition before olefin binding) at high pressure to an unsaturate route (olefin binding before dihydrogen addition) at low pressures (<30 atm). Olefin isomerization is inhibited by halide addition, but occurs with sulfonate and in neat methanol through what is most likely a pi-allyl mechanism. A detailed understanding of the effects of addition of these anions is crucial for development of new classes of catalysts capable of efficient enantioselective reduction of prochiral olefins lacking a secondary polar binding group. PMID:10747398

  8. Substrate range and enantioselectivity of epoxidation reactions mediated by the ethene-oxidising Mycobacterium strain NBB4.

    PubMed

    Cheung, Samantha; McCarl, Victoria; Holmes, Andrew J; Coleman, Nicholas V; Rutledge, Peter J

    2013-02-01

    Mycobacterium strain NBB4 is an ethene-oxidising micro-organism isolated from estuarine sediments. In pursuit of new systems for biocatalytic epoxidation, we report the capacity of strain NBB4 to convert a diverse range of alkene substrates to epoxides. A colorimetric assay based on 4-(4-nitrobenzyl)pyridine) has been developed to allow the rapid characterisation and quantification of biocatalytic epoxide synthesis. Using this assay, we have demonstrated that ethene-grown NBB4 cells epoxidise a wide range of alkenes, including terminal (propene, 1-butene, 1-hexene, 1-octene and 1-decene), cyclic (cyclopentene, cyclohexene), aromatic (styrene, indene) and functionalised substrates (allyl alcohol, dihydropyran and isoprene). Apparent specific activities have been determined and range from 2.5 to 12.0 nmol min(-1) per milligram of cell protein. The enantioselectivity of epoxidation by Mycobacterium strain NBB4 has been established using styrene as a test substrate; (R)-styrene oxide is produced in enantiomeric excesses greater than 95%. Thus, the ethene monooxygenase of Mycobacterium NBB4 has a broad substrate range and promising enantioselectivity, confirming its potential as a biocatalyst for alkene epoxidation. PMID:22410742

  9. 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

  10. Explosive photodissociation of methane induced by ultrafast intense laser

    SciTech Connect

    Kong Fanao; Luo Qi; Xu Huailiang; Sharifi, Mehdi; Song Di; Chin, See Leang [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Department of Physics, Engineering Physics and Optics, Laval University, Quebec G1K 7P4, Canada and Center for Optics, Photonics, and Laser, Laval University, Quebec G1K 7P4 (Canada); Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Department of Physics, Engineering Physics and Optics, Laval University, Quebec G1K 7P4 (Canada) and Center for Optics, Photonics, and Laser, Laval University, Quebec G1K 7P4 (Canada)

    2006-10-07

    A new type of molecular fragmentation induced by femtosecond intense laser at the intensity of 2x10{sup 14} W/cm{sup 2} is reported. For the parent molecule of methane, ethylene, n-butane, and 1-butene, fluorescence from H (n=3{yields}2), CH (A {sup 2}{delta}, B {sup 2}{sigma}{sup -}, and C {sup 2}{sigma}{sup +}{yields}X {sup 2}{pi}), or C{sub 2} (d {sup 3}{pi}{sub g}{yields}a {sup 3}{pi}{sub u}) is observed in the spectrum. It shows that the fragmentation is a universal property of neutral molecule in the intense laser field. Unlike breaking only one or two chemical bonds in conventional UV photodissociation, the fragmentation caused by the intense laser undergoes vigorous changes, breaking most of the bonds in the molecule, like an explosion. The fragments are neutral species and cannot be produced through Coulomb explosion of multiply charged ion. The laser power dependence of CH (A{yields}X) emission of methane on a log-log scale has a slope of 10{+-}1. The fragmentation is thus explained as multiple channel dissociation of the superexcited state of parent molecule, which is created by multiphoton excitation.

  11. Synthesis of novel acid electrolytes for phosphoric acid fuel cells. Final report, May 1985-October 1988

    SciTech Connect

    Adcock, J.L.

    1988-11-01

    Construction of a 40-millimole-per-hour-scale aerosol direct-fluorination reactor was completed June 26, 1986. 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 GRI contractors for synthesis of perfluorinated sulfur(VI) and phosphorous(V) acids.

  12. 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. PMID:23865448

  13. An operando FTIR spectroscopic and kinetic study of carbon monoxide pressure influence on rhodium-catalyzed olefin hydroformylation.

    PubMed

    Kubis, Christoph; Sawall, Mathias; Block, Axel; Neymeyr, Klaus; Ludwig, Ralf; Börner, Armin; Selent, Detlef

    2014-09-01

    The influence of carbon monoxide concentration on the kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a phosphite-modified rhodium catalyst has been studied for the pressure range p(CO)=0.20-3.83?MPa. Highly resolved time-dependent concentration profiles of the organometallic intermediates were derived from IR spectroscopic data collected in situ for the entire olefin-conversion range. The dynamics of the catalyst and organic components are described by enzyme-type kinetics with competitive and uncompetitive inhibition reactions involving carbon monoxide taken into account. Saturation of the alkyl-rhodium intermediates with carbon monoxide as a cosubstrate occurs between 1.5 and 2?MPa of carbon monoxide pressure, which brings about a convergence of aldehyde regioselectivity. Hydrogenolysis of the acyl intermediate is fast at 30?°C and low pressure of p(CO)=0.2?MPa, but is of minus first order with respect to the solution concentration of carbon monoxide. Resting 18-electron hydrido and acyl complexes that correspond to early and late rate-determining states, respectively, coexist as long as the conversion of the substrate is not complete. PMID:25081298

  14. Methods used to simplify optical and X-ray mask fabrication processes

    SciTech Connect

    Novembre, A.E. [AT& T Bell Laboratories, Murray Hill, NJ (United States)

    1993-12-31

    An improvement in the method used to fabricate 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) as the pattern delineation material. The controller monitors in real-time the resist development process and uses this information to obtain resist feature dimensions to within {+-}0.05 {mu}m of their targeted size. Evaluation of resist materials suitable for use in a subtractive x-ray mask process has identified the co-polymer poly(trimethylsilylmethyl methacrylate-co-chloromethylstyrene) P(SI-CMS) as providing substantial process latitude, {le}0.20 {mu}m resolution, and a significant reduction in etch rate in the Cl{sub 2}-O{sub 2} plasma used in part to pattern the x-ray mask. Further comparisons in the process simplification of this material to other established resists will be presented.

  15. Structure determination and sensory analysis of bitter-tasting 4-vinylcatechol oligomers and their identification in roasted coffee by means of LC-MS/MS.

    PubMed

    Frank, Oliver; Blumberg, Simone; Kunert, Christof; Zehentbauer, Gerhard; Hofmann, Thomas

    2007-03-01

    Aimed at elucidating intense bitter-tasting molecules in coffee, various bean ingredients were thermally treated in model experiments and evaluated for their potential to produce bitter compounds. As caffeic acid was found to generate intense bitterness reminiscent of the bitter taste of a strongly roasted espresso-type coffee, the reaction products formed were screened for bitter compounds by means of taste dilution analysis, and the most bitter tastants were isolated and purified. LC-MS/MS as well as 1-D/2-D NMR experiments enabled the identification of 10 bitter compounds with rather low recognition threshold concentrations ranging between 23 and 178 micromol/L. These bitter compounds are the previously unreported 1,3-bis(3',4'-dihydroxyphenyl) butane, trans-1,3-bis(3',4'-dihydroxyphenyl)-1-butene, and eight multiply hydroxylated phenylindanes, among which five derivatives are reported for the first time. In addition, the occurrence of each of these bitter compounds in a coffee brew was verified by means of LC-MS/MS (ESI-) operating in the multiple reaction monitoring (MRM) mode. The structures of these bitter compounds show strong evidence that they are generated by oligomerization of 4-vinylcatechol released from caffeic acid moieties upon roasting. PMID:17269788

  16. Organic chemistry in the oceans of Titan

    NASA Astrophysics Data System (ADS)

    Raulin, F.

    On Titan, most of the organics present in the atmosphere must condense in the lower stratosphere and be solid near the surface, except methane, ethane, propane, propene and 1-butene which must be liquid and could form oceans containing large fractions of dissolved N2. Chemical evolution on Titan must have followed a way very different from the terrestrial one, involving physical chemical processes in a cryogenic apolar solvent mainly composed of CH4-C2H6-N2, in place of organic chemistry in water. Systematic study of the volumic mass and solubility of organics in such a cryogenic mixture of various compositions, at 94K, is presented, using thermodynamic modelling. The results suggest that the oceans of Titan could be free of any "icebergs" of organic compounds. These oceans could be very rich in dissolved organics, with relatively high concentrations, in the range 1 - 10-6M. In addition, the concentration of several of the organic solutes should be constant, buffered by a bottom layer of the corresponding compound in the solid phase.

  17. Speciated VOC emission inventory and spatial patterns of ozone formation potential in the Pearl River Delta, China.

    PubMed

    Zheng, Junyu; Shao, Min; Che, Wenwei; Zhang, Lijun; Zhong, Liuju; Zhang, Yuanhang; Streets, David

    2009-11-15

    The Pearl River Delta region (PRD) of China has long suffered from severe ground-level ozone pollution. Knowledge of the sources of volatile organic compounds (VOCs) is essential for ozone chemistry. In this work, a speciated VOC emission inventory was established on the basis of updated emissions and local VOC source profiles. The top 10 species, in terms of ozone formation potentials (OFPs), consisted of isoprene, mp-xylene, toluene, ethylene, propene, o-xylene, 1,2,4-trimethylbenzene, 2-methyl-2-butene, 1-butene, and alpha-pinene. These species contributed only 35.9% to VOCs emissions but accounted for 64.1% of the OFP in the region. The spatial patterns of the VOC source inventory agreed well with city-based source apportionment results, especially for vehicle emissions and industry plus VOC product-related emissions. Mapping of the OFPs and measured ozone concentrations indicated that the formation of higher ozone in the south and southeast of the PRD region differed from that in the Conghua area, a remote area in the north of the PRD. We recommend that the priorities for the control of VOC sources include motorcycles, gasoline vehicles, and solvent use because of their larger OFP contributions. PMID:20028055

  18. Synthesis and antitumor activity of 10-alkyl-10-deazaminopterins. A convenient synthesis of 10-deazaminopterin.

    PubMed

    DeGraw, J I; Brown, V H; Tagawa, H; Kisliuk, R L; Gaumont, Y; Sirotnak, F M

    1982-10-01

    Requirements for large-scale synthesis of the potent antitumor drug 10-deazaminopterin have led to development of a facile synthesis of this compound and its 10-alkyl analogues. The lithium diisopropyl amide generated dianions of appropriate p-alkylbenzoic acids were alkylated with 3-methoxyallyl chloride. The resulting 4-(p-carboxyphenyl)-1-methoxy-1-butenes were brominated at pH 7-8 to afford the 2-bromo-4-(p-carboxyphenyl)butyraldehydes. Condensation with 2,4,5,6-tetraminopyrimidine and subsequent in situ oxidation of the resulting dihydropteridines yielded crystalline 10-alkyl-10-deaza-4-amino-4-deoxypteroic acids. The pteroic acids were coupled with diethyl glutamate via the mixed anhydride method, followed by saponification at room temperature, to give the target 10-deazaminopterins. The 10-alkyl compounds were approximately equipotent to 10-deazaminopterin as growth inhibitors of folate-dependent bacteria. Their abilities to inhibit Lactobacillus casei and L1210 derived dihydrofolate reductases were also similar. Transport properties in vitro were suggestive of an improved therapeutic index for the 10-alkyl analogues. Against L1210 in mice, the percent increase in life span at the LD10 dosage was +151% (methotrexate), +178% (10-deazaminopterin), +235% (10-methyl analogue), and +211% (10-ethyl analogue). 10,10-Dimethyl-10-deazaminopterin was less effective at an equimolar dosage, but the ILS at the maximum dose tested (72 mg/kg) was +135%. It was far less toxic than the other analogues possibly because of enhanced clearance. PMID:7143361

  19. [Characteristics of VOCs and their photochemical reactivity in autumn in Nanjing northern suburb].

    PubMed

    Li, Yong-Yu; Zhu, Bin; An, Jun-Lin; Gao, Jin-Hui; Xia, Li; Zhang, Xiang-Zhi; Qin, Wei; Tang, Li-Li

    2013-08-01

    A continuous observation campaign was carried out with the GC5000 volatile organics online monitoring system and the EMS system for one month in November 2011 in the northern suburb of Nanjing, and 56 VOC components and reactive gases (NO(x), CO and O3) were measured. The results showed that the VOC hourly averaged volume fraction in Nanjing northern suburb was about 48.17 x 10(-9), and the minimum value of VOCs occurred at 16:00. The diurnal variation showed a bimodal characteristic, indicating the significant impact of motor vehicle emission. The VOC concentration and O3 concentration exhibited negative correlation in the daytime. The average OH consumption rate of VOCs was approximately 3.26 x 10(-12) cm3 x (molecule x s)(-1), and the largest incremental reactivity was about 3.26 mol x mol(-1); Alkenes contributed the largest-parts of the OH consumption rate (L(OH)) and the ozone formation potential (OFP), followed by aromatics. Although alkanes were the most abundant components of VOCs in the atmosphere, it is not the main contributor of L(OH) and OFP. The key active components in VOCs were ethylene, propylene, 1-butene, m,p-xylene and isoprene, etc. The dominant factor of ozone formation was VOCs in this observation. PMID:24191532

  20. 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 ?g 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 present in the fine mode, except during the wet period where it peaked in the coarse mode. Isoprene SOA tracers showed an average concentration of 250 ng m-3 during the dry period versus 157 ng m-3 during the transition period and 52 ng m-3 during the wet period. Malic acid and the 2-methyltetrols exhibited a different size distribution pattern: while the 2-methyltetrols were mainly associated with the fine mode during all periods, malic acid was prevalent in the fine mode only during the dry and transition periods, while it was dominant in the coarse mode during the wet period, consistent with different formation processes. The sum of arabitol, mannitol, and erythritol in the PM2.5 fraction of the HVDS samples during the dry, transition, and wet periods was, on average, 54 ng m-3, 34 ng m-3, and 27 ng m-3, respectively, and revealed minor day/night variation. The mass size distributions of arabitol and mannitol during all periods showed similar patterns and an association with the coarse mode, consistent with their primary origin. The results show that even under the heavy smoke conditions of the dry period a natural background with contributions from bioaerosols and isoprene SOA can be revealed. The enhancement in isoprene SOA in the dry season is mainly attributed to an increased acidity of the aerosols and a decreased wet deposition.

  1. 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 of C-C and C-H bond ruptures, cyclization, decyclization, and complex decompositions are discussed in terms of energetics and structural properties. The pressure dependence of the product yields were computed and dominant reaction paths in this chemically activated system were determined. Both modeling and experiment suggest that the observed pressure dependence of [1-C4H8]/[C4H10] is due to decomposition of the chemically activated combination adduct 1-C4H8* in which the weaker allylic C-C bond is broken: H2C=CHCH2CH3 yields C3H5 + CH3. This reaction occurs even at moderate pressures of approx.200 Torr (26 kPa) and becomes more significant at lower pressures. The additional products detected at lower pressures are formed from secondary radical-radical reactions involving allyl, methyl, ethyl, and vinyl radicals. The modeling studies have extended the predictions of product distributions to different temperatures (200-700 K) and a wider range of pressures (10(exp -3) - 10(exp 5) Torr). These calculations indicate that the high-pressure [1-C4H8]/[C4H10] yield ratio is 1.3 +/- 0.1.

  2. Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

    NASA Astrophysics Data System (ADS)

    Murillo, Luis E.

    Studies of bimetallic systems are of great interest in catalysis due to the novel properties that they often show in comparison with the parent metals. The goals of this dissertation are: (1) to expand the studies of self-hydrogenation and hydrogenation reactions on bimetallic surfaces under ultra high vacuum conditions (UHV) using different hydrocarbon as probe molecules; (2) to attempt to correlate the surface science findings with supported catalyst studies under more realistic conditions; and (3) to investigate the competitive hydrogenation of C=C versus C=O bonds on Pt(111) modified by different 3d transition metals. Hydrogenation studies using temperature programmed desorption (TPD) on Ni/Pt(111) bimetallic surfaces have demonstrated an enhancement in the low temperature hydrogenation activity relative to that of clean Pt(111). This novel hydrogenation pathway can be achieved under UHV conditions by controlling the structures of the bimetallic surfaces. A low temperature hydrogenation activity of 1-hexene and 1-butene has been observed on a Pt-Ni-Pt(111) subsurface structure, where Ni atoms are mainly present on the second layer of the Pt(111) single crystal. These results are in agreement with previous studies of self-hydrogenation and hydrogenation of cyclohexene. However, a much higher dehydrogenation activity is observed in the reaction of cyclohexene to produce benzene, demonstrating that the hydrocarbon structure has an effect on the reaction pathways. On the other hand, self-hydrogenation of 1-butene is not observed on the Pt-Ni-Pt(111) surface, indicating that the chain length (or molecular weight) has a significant effect on the selfhydrogenation activity. The gas phase reaction of cyclohexene on Ni/Pt supported on alumina catalysts has also shown a higher self-hydrogenation activity in comparison with the same reaction performed on supported monometallic catalysts. The effects of metal loading and impregnation sequence of the metal precursors are also discussed. Chemisorption, TPD, FTIR using a batch reactor for the self-hydrogenation of cyclohexene and CO adsorbed on the bimetallic surfaces were carried out to correlate surface science findings with experiments on supported bimetallic catalysts. To expand the studies on the effect of bimetallic structures on hydrogenation reactions, molecules with multiple functional groups such as alpha,beta-unsaturated aldehydes were also investigated. Studies of selective hydrogenation of a,ss-unsaturated aldehydes toward the desired unsaturated alcohols are of interest for the production of fine chemicals and pharmaceuticals. In these compounds, competitive hydrogenation of the C=C and C=O bonds occurs. TPD and HREELS experiments of acrolein (CH2=CH-CH=O) on Pt-based bimetallic surfaces are performed to investigate their effects on the hydrogenation activity of the C-O bond. The production of the desired unsaturated alcohol, allyl alcohol, has been observed for the first time on Pt-Ni-Pt(111) under UHV conditions. However, the propionaldehyde yield is five times higher than the allyl alcohol yield. Thus, a preferential isomerization reaction of allyl alcohol to propionaldehyde is very likely to occur on the Pt-Ni-Pt(111) surface as observed on the desorption studies of allyl alcohol on this surface. The hydrogenation of acrolein is also carried out under UHV conditions on other 3d-transition metal/Pt(111) surfaces such as Co/Pt(111), Fe/Pt(111), and Cu/Pt(111). So far, the highest activity and allyl alcohol yield are found on the Pt-Ni-Pt(111) surface with pre-adsorbed hydrogen.

  3. Competitive chain transfer by [beta]-hydrogen and [beta]-methyl elimination for the model Ziegler-Natta olefin polymerization system [Me[sub 2]Si([eta][sup 5]-C[sub 5]Me[sub 4])[sub 2

    SciTech Connect

    Hajela, S.; Bercaw, J.E. (California Inst. of Technology, Pasadena, CA (United States))

    1994-04-01

    The reaction of OpSc(H)(PMe[sub 3]) (Op = (([eta][sup 5]-C[sub 6]Me[sub 4])[sub 2]SiMe[sub 2])) with isobutene produces OpSc(CH[sub 3])(PMe[sub 3]) along with isobutene, 2-methylpentane, isobutene, 2-methyl-1-pentene, propane, and n-pentane. These products arise from a series of reactions involving olefin insertion, [beta]-CH[sub 3] and (faster) [beta]-H elimination which proceed until only the 2-methyl-1-alkenes (C[sub 4]H[sub 8], C[sub 6]H[sub 12], etc.) and the predominant organoscandium product OpSc(CH[sub 3])(PMe[sub 3]) remain. A transient observed in the reaction sequence has been unambiguously characterized as OpSc(CH[sub 2]CH[sub 2]CH[sub 3])(PMe[sub a]). Slower [sigma] bond metathesis involving the methyl C-H bonds of PMe[sub 3] and the Sc-C bonds of the scandium alkyls accounts for the observation of saturated alkanes 2-methylalkanes (C[sub 4]H[sub 10], C[sub 6]H[sub 14], etc.), normal alkanes (C[sub 3]H[sub 8],C[sub 5]H[sub 12], etc.), and a minor organoscandium product OpScCh[sub 2]Pme[sub 2] in the product mixture. [beta]-Ethylmigration is not observed for the closely related 2-ethylbutyl derivative, OpSc(CH[sub 2]CH(C[sub 2]H[sub 5])CH[sub 2]CH[sub 3])(PMe[sub 3]), obtained from reaction of 2-ethyl-1-butene with OpSc(H)(PMe[sub 3]). 28 refs., 2 figs., 1 tab.

  4. Influence of relative humidity and ozone on the sampling of volatile organic compounds on carbotrap/carbosieve adsorbents.

    PubMed

    Palluau, Fabienne; Mirabel, Philippe; Millet, Maurice

    2007-04-01

    By using a dynamic dilution system, the atmospheric measurement of 11 selected toxics VOCs (ethylene, acetylene, propene, 1-butene, 1,3-butadiene, 1-pentene, 1-hexene, benzene, toluene, ethylbenzene, m+p-xylene) from the list WHO of 1996 and TO-14 method of US EPA by preconcentration by thermal desorption (TD), analysis by gas chromatography (GC), identification and quantification with a flame ionisation detector (FID) was developed and validated in term of metrology, especially the techniques of sampling of these VOCs with adsorbents cartridges "Air Toxics" when used with an "UMEG sampler" equipped in the inlet with a nafion membrane. In particular the influence of climatic conditions (temperature and relative humidity) and the influence of chemical factors like ozone, on the representativity of sampling were studied. Experiments made with various humidities showed that the addition of a nafion membrane in the inlet of the sampling system was required. Without this membrane, losses of compounds were observed for RH >50%. With this membrane, storage for 2 weeks in a refrigerator, as for canisters, did not induce a loss of compounds. No significative decrease of concentrations of the studied VOCs after 14 days storage, which are known to react with ozone, were observed with an ozone concentrations of 55 ppb. One explanation is that nafion membrane, placed in the inlet of the sampler, will neutralize ozone before entering the sampling tubes. This observation is in accordance with literature which states that the sampling of VOCs on Carbotrap cartridges without ozone scrubber induce a loss of compounds. PMID:16897502

  5. 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.

  6. Quantitative analysis of trihydroxybutyl mercapturic acid, a urinary metabolite of 1, 3-butadiene, in humans

    PubMed Central

    Kotapati, Srikanth; Matter, Brock A.; Grant, Amy L.; Tretyakova, Natalia Y.

    2011-01-01

    1,3-butadiene (BD)* is a known human carcinogen present in cigarette smoke and in automobile exhaust, leading to widespread exposure of human populations. BD requires cytochrome P450-mediated metabolic activation to electrophilic species, e.g. 3,4-epoxy-1-butene (EB), hydroxymethylvinylketone (HMVK), and 3,4-epoxy-1,2-diol (EBD), which form covalent adducts with DNA. EB, HMVK, and EBD can be conjugated with glutathione and ultimately excreted in urine as monohydroxybutenyl mercapturic acid (MHBMA), dihydroxybutyl mercapturic acid (DHBMA), and trihydroxybutyl mercapturic acid (THBMA), respectively, which can serve as biomarkers of BD exposure and metabolic processing. While MHBMA and DHBMA have been found in smokers and non-smokers, THBMA has not been previously detected in humans. In the present work, an isotope dilution HPLC-ESI?-MS/MS methodology was developed and employed to quantify THBMA in urine of known smokers and non-smokers (19–27 per group). The new method has excellent sensitivity (LOQ, 1 ng/mL urine) and achieves accurate quantitation using a small sample volume (100 µl). Mean urinary THBMA concentrations in smokers and non-smokers were found to be 21.6 and 13.7 ng/mg creatinine, respectively, suggesting that there are sources of THBMA other than exposure to tobacco smoke in humans, as is also the case for DHBMA. However, THBMA concentrations are significantly greater in urine of smokers than that of non-smokers (p < 0.01). Furthermore, THBMA amounts in human urine declined 25–50 % following smoking cessation, suggesting that smoking is an important source of this metabolite in humans. The HPLC-ESI?-MS/MS methodology developed in the present work will be useful for future epidemiological studies of BD exposure and metabolism. PMID:21749114

  7. Synthesis, characterization, and thiophene desulfurization activity of unsupported {gamma}-Mo{sub 2}N macrocrystalline catalysts

    SciTech Connect

    Markel, E.J.; Burdick, S.E.; Leaphart, M.E. II [Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering] [Univ. of South Carolina, Columbia, SC (United States). Dept. of Chemical Engineering; Roberts, K.L. [North Carolina A and T State Univ., Greensboro, NC (United States). Dept. of Chemical Engineering] [North Carolina A and T State Univ., Greensboro, NC (United States). Dept. of Chemical Engineering

    1999-02-15

    Macrocrystals of {gamma}-Mo{sub 2}N were synthesized by temperature-programmed reaction of macrocrystalline MoO{sub 3} and NH{sub 3} or N{sub 2}/H{sub 2} mixtures. X-ray diffraction analyses indicate macrocrystalline Mo{sub 2}N is an aggregate of particles in crystallographic alignment with diameters ranging from 4.6 to 18 nm, depending on synthesis conditions. Scanning tunneling microscopy (STM) supports these observed diameters. Based on diffraction data and surface area measurements, it is concluded that the particles in each sample are found with a range of diameters, each flattened in the [200] direction with either an amorphous surface phase or polycrystalline interior. The highest crystal BET surface area achieved is 44 m{sup 2}/g. TGA was used to monitor the temperature-programmed reaction of MoO{sub 3} and N{sub 2}/H{sub 2} mixtures. The lowest reduction temperatures were observed in syntheses employing high H{sub 2} concentrations and slow temperature ramping rates. The rate of the Mo{sub 2}N macrocrystal synthesis reaction was observed to be slower than the equivalent powder reaction, which could possibly be attributed to the effects of solid-state diffusion. The specific thiophene hydrodesulfurization (HDS) activity (units of mol/s m{sup 2}) of the Mo{sub 2}N macrocrystalline catalyst at 673 K was found to be higher than the powder form by a factor of 2.5. Weight-specific HDS activities and reaction product fractions over Mo{sub 2}N macrocrystal and powder catalysts were roughly the same. An analysis of reaction products over a range of conversions indicates thiophene desulfurizes to form predominantly 1-butene with smaller amounts of other C{sub 4} hydrocarbons also present.

  8. The adsorption of 1,3-butadiene on Pd/Ni multilayers: The interplay between spin polarization and chemisorption strength

    SciTech Connect

    Gomez, Guillermina [Grupo de Materiales y Sistemas Cataliticos, Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, Bahia Blanca B8000CPB (Argentina); Belelli, Patricia G., E-mail: pbelelli@plapiqui.edu.a [CONICET (Argentina); Cabeza, Gabriela F.; Castellani, Norberto J. [CONICET (Argentina)

    2010-12-15

    The adsorption of 1,3-butadiene (BD) on the Pd/Ni(1 1 1) multilayers has been studied using the VASP method in the framework of the density functional theory (DFT). The adsorption on two different configurations of the Pd{sub n}/Ni{sub m}(1 1 1) systems were considered. The most stable adsorption sites are dependent on the substrate composition and on the inclusion or not of spin polarization. On Pd{sub 1}Ni{sub 3}(1 1 1) surface, di-{pi}-cis and 1,2,3,4-tetra-{sigma} adsorption structures are the most stable for non-spin polarized (NSP) and spin polarized (SP) levels of calculation, respectively. Conversely, on Pd{sub 3}Ni{sub 1}(1 1 1) surface, the 1,2,3,4-tetra-{sigma} adsorption structure is the most stable for both NSP and SP levels, respectively. The magnetization of the Pd atoms strongly modifies the adsorption energy of BD and its most stable adsorption mode. On the other hand, as a consequence of BD adsorption, the Pd magnetization decreases. The smaller adsorption energies of BD and 1-butene on the Pd{sub 1}Ni{sub 3}(1 1 1) surface than on Pd(1 1 1) can be associated to the strained Pd overlayer deposited on Ni(1 1 1). -- Graphical Abstract: The adsorption of 1,3-butadiene on Pd/Ni(1 1 1) multilayers was theoretically studied. The most stable adsorption site depends on the substrate composition and on the inclusion of spin polarization. Display Omitted

  9. 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.

  10. Reaction of tributyl phosphite with oxidized iron: surface and tribological chemistry.

    PubMed

    Gao, Feng; Furlong, Octavio; Kotvis, Peter V; Tysoe, Wilfred T

    2004-08-31

    The surface chemistry of a model lubricant additive, tributyl phosphite (TBPi), is investigated on Fe3O4 in ultrahigh vacuum. A portion of the TBPi desorbs molecularly following adsorption at approximately 200 K, the remainder decomposing either by C-O bond scission to form 1-butyl species or by P-O bond cleavage to form butoxy species. Adsorbed butyl species either undergo beta-hydride elimination to desorb 1-butene or decompose to deposit carbon and hydrogen on the surface. The resulting adsorbed hydrogen reacts with the oxide to desorb water or with the butoxy species to form 1-butanol. Butoxy species are stable up to approximately 600 K at which temperature they also undergo beta-hydride elimination to form butanal and the released hydrogen reacts with other butoxy species to form 1-butanol. Only a small amount of carbon is deposited onto the surface following adsorption at approximately 200 K, which then desorbs as CO above approximately 750 K. Adsorbing TBPi at 300 K results in the deposition of more carbon and an Auger depth profile reveals that the carbon is located predominantly on the surface, while the phosphorus is rather uniformly distributed throughout the oxide film. This result is in accord with previous near-edge X-ray absorption fine structure measurements, which show the formation of phosphates and polyphosphate glasses. The resulting tribological film appears to be composed of a relatively hard polyphosphate glass formed by rapid diffusion of POx species into the oxide, covered by a low shear strength graphitic layer. PMID:15323502

  11. 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.

  12. 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

  13. 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.

  14. 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 2?, 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.

  15. Laser absorption diagnostic for measuring acetylene concentrations in shock tubes

    NASA Astrophysics Data System (ADS)

    Stranic, Ivo; Hanson, Ronald K.

    2014-07-01

    A fixed-wavelength direct absorption laser diagnostic for high-temperature measurements of acetylene concentration was developed. The diagnostic, based on a tunable continuous wave distributed feedback diode laser, was optimized primarily for studying chemical kinetics behind reflected shock waves. The center wavelength (3335.55 cm-1) of the tunable diagnostic was typically set at the peak of the 3300 cm-1 absorption band of acetylene at high temperatures. The absorption spectrum of acetylene diluted in argon was characterized using scanned-wavelength direct absorption measurements from 1070 to 1720 K and 0.8 to 4.0 atm. Line fitting of the measured absorption spectra was not possible due to the large number of transitions overlapped by pressure broadening that contribute to the spectrum. Instead, empirical fits for the peak absorption coefficient and its corresponding wavelength as a function of temperature and pressure were generated. Furthermore, in order to allow for characterization of interference absorption in kinetic studies, empirical fits for the acetylene absorption coefficient in the region around the primary absorption feature were developed. Absorption coefficient measurements of propyne and 1-butyne, which may be the primary interference candidates, reveal that their absorption coefficients are constant in the wavelength range of interest, and are much smaller than those of acetylene. Therefore, the acetylene concentration in the presence of these interfering species can be inferred using two-color techniques. The utility of the acetylene diagnostic was demonstrated by measuring acetylene mole fraction time-histories during the pyrolysis of propene and 1-butene.

  16. Photochemical cycloaddition reactions of cyanoacetylene and dicyanoacetylene

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Guillemin, J. C.

    1990-01-01

    Photolysis of cyanoacetylene with 185- or 206-nm light yields 1,3,5-tricyanobenzene while 254-nm radiation yields a mixture of tetracyanocyclooctatetraenes, 1,2,4- and 1,3,5-tricyanobenzene. A polymer of cyanoacetylene is the major photoproduct. 1,3,5-Tricarbomethoxybenzene was the only photoproduct identified from the irradiation of methyl propiolate at 254 nm. Mono-, di-, and tricyanobenzenes are formed by irradiation of mixtures of acetylene and cyanoacetylene at 185, 206, and 254 nm along with trace amounts of cyclooctatetraenes. No photoadducts were detected on photolysis of mixtures of cyanoacetylene and CO or HCN. The tetracyanocyclooctatetraene structures were established by UV, MS, and NMR analyses. The 1H NMR of the product mixture exhibited a singlet at delta 7.028 consistent with either 1 or 2 and two singlets at delta 6.85 and 6.91 assigned to 3. Photolysis of mixtures of dicyanoacetylene and acetylene with either 185- or 206-nm light yielded 1,2-dicyanobenzene and (E,Z)-1-buten-3-yne-1,4-dicarbonitrile. These products were also obtained using 254-nm light along with a mixture of tetracyanocyclooctatetraenes. The same three singlets were observed in this product mixture as were observed in the tetracyanocyclooctatetraenes obtained from cyanoacetylene. From this observation it was concluded that the delta 7.02 signal is due to 2 and not 1. The photolysis of cyanoacetylene and dicyanoacetylene in the presence of ethylene with 185-nm light yields 1-cyanocylobutene and 1,2-dicyanocyclobutene, respectively. 2-Cyanobutadiene and 2,3-dicyanobutadiene are the photoproducts with 254-nm light. Reaction pathways are proposed to explain these findings.

  17. 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, or the larger molecular structures for which it is a known pyrolysis/combustion intermediate (e.g. cellulose, coals, 2,5-dimethylfuran). PMID:24496403

  18. NanoLC/ESI+ HRMS3 quantitation of DNA adducts induced by 1,3-butadiene.

    PubMed

    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(+)-HRMS(3) 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 10(8) nucleotides in HT1080 cells treated with 0.5-10 ?M EB. 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 10(8) nucleotides, respectively [corrected]. 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(+)-HRMS(3) Orbitrap methodology to quantitative analysis of DNA adducts in vivo. PMID:24867429

  19. 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.

  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 ?m 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 using t-butyl hydroperoxide as initiator. The T_{rm g} of these polymers are >70 ^circC with similar degradation transitions seen for the poly (olefin sulfone) copolymers. These polymers are soluble in a common solvent, nitromethane. Poly(hexadiene -1,3 sulfone) acted as a positive tone resist when exposed to synchrotron radiation and developed in nitropropane. Sensivities <50 mJ/cm^2 were determined for this polymer, vapor development was not achieved. Resolution studies revealed line widths to 0.25 muM, the feature limits of the test mask used.

  1. The Stable Carbon Isotope Ratio Analysis of Atmospheric Non-Methane Hydrocarbons in Los Angeles, California

    NASA Astrophysics Data System (ADS)

    Gotoh, A. A.; Tyler, S. C.; Meinardi, S.; Gervais, K.; Blake, D. R.

    2003-12-01

    Los Angeles type photochemical air pollution is caused by non-methane hydrocarbons (NMHCs) reacting with hydroxyl radicals and nitrous oxides in the presence of light. To create more effective control strategies in reducing such air pollution, it is essential to have both a better understanding of the complex photochemical processes of NMHCs and the sources of these compounds. From the past successful studies of other atmospheric trace gases such as methane and carbon monoxide, we expect that the stable carbon ratio (13C/12C, reported as a ? 13C value) of each of these hydrocarbons will also reflect the ? 13C value of the source material and/or provide formation on chemical loss processes that fractionate C isotopes. We have developed a NMHC preconcentrator system which enables us to measure ? 13C values using a continuous-flow gas chromatography combustion isotope ratio mass spectrometer (cf-GC/C/IRMS). Our system is similar to the successful design pioneered in Rudolph et al. (1997), but is custom designed by our laboratory. Stable carbon isotope measurements of any of the C2-C5 NMHCs in field and/or lab studies are scarce to date. Our system allows us to report on ? 13C measurements of ethane, ethene, ethyne, propane, propene, n-butane, i-butane, 1-butene, n-pentane, i-pentane, and methyl chloride. To see if we can learn the specific sources contributing to the emissions of a given NMHC within a region by comparing isotopic signatures of its potential sources to ? 13C measurements of it within the local air mass, urban air samples were collected in 3 different cities of Los Angeles County, California, USA, during the summer of 2003 and analyzed for the concentrations and ? 13C values of NMHCs. To our knowledge, this is the first ? 13C analysis of ambient NMHCs conducted in the United States. We report the results of the ? 13C analyses and concentration measurements for selected NMHC species from the urban air samples, and their implications for the local atmospheric chemistry of Los Angeles Basin.

  2. 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 ?M 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.

  3. Capillary HPLC-Accurate Mass MS/MS Quantitation of N7-(2, 3, 4-trihydroxybut-1-yl)-guanine Adducts of 1,3-Butadiene in Human Leukocyte DNA

    PubMed Central

    Sangaraju, Dewakar; Villalta, Peter; Goggin, Melissa; Agunsoye, Maria O.; Campbell, Colin; Tretyakova, Natalia

    2013-01-01

    1,3-butadiene (BD) is a high volume industrial chemical commonly used in polymer and rubber production. It is also present in cigarette smoke, automobile exhaust, and urban air, leading to widespread exposure of human populations. Upon entering the body, BD is metabolized to electrophilic epoxides, 3,4-epoxy-1-butene (EB), diepoxybutane (DEB), and 3,4-epoxy-1,2-diol (EBD), which can alkylate DNA nucleobases. The most abundant BD epoxide, EBD, modifies the N7-guanine positions in DNA to form N7-(2, 3, 4-trihydroxybut-1-yl) guanine (N7-THBG) adducts, which can be useful as biomarkers of BD exposure and metabolic activation to DNA-reactive epoxides. In the present work, a capillary HPLC- high resolution ESI+-MS/MS (HPLC-ESI+-HRMS/MS) methodology was developed for accurate, sensitive, and reproducible quantification of N7-THBG in cell culture and in human white blood cells. In our approach, DNA is subjected to neutral thermal hydrolysis to release N7-guanine adducts from the DNA backbone, followed by ultrafiltration, solid phase extraction, and isotope dilution HPLC-ESI+-HRMS/MS analysis on an Orbitrap Velos mass spectrometer. Following method validation, N7-THBG was quantified in human fibrosarcoma (HT1080) cells treated with ?molar concentrations of DEB and in DNA isolated from blood of smokers, nonsmokers, individuals participating in a smoking cessation program, and occupationally exposed workers. N7-THBG concentrations increased linearly from 31.4?± 4.84 to 966.55 ± 128.05 adducts per 109 nucleotides in HT1080 cells treated with 1 -100 ?M DEB. N7-THBG amounts in leukocyte DNA of non-smokers, smokers, and occupationally exposed workers were 7.08 ± 5.29, 8.20 ± 5.12, and 9.72 ± 3.80 adducts per 109 nucleotides, respectively, suggesting the presence of an endogenous or environmental source for this adduct. The availability of sensitive HPLC-ESI+-HRMS/MS methodology for BD-induced DNA adducts in humans will enable future population studies of inter-individual and ethnic differences in BD bioactivation to DNA-reactive epoxides. PMID:23937706

  4. 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 growth factor protein was 16175.6 Da. MALDI analysis of trypsin digest of Myeloid progenitor inhibitory factor chemokine verified the disulfide bridging among cysteine residues. Several partially digested trypsin and V8 peptides were detected that verified significant portions of the primary structure of the chemokine. Mass difference amounting to the loss of a single amino acid, serine was also identified. The cyanogen bromide (CNBr) treated chemokine produced three peptides 7051, 6910.1 and 1492 Da. The analysis of Keratinocyte growth factor (KGF) peptide mixtures showed suppression effects during the MALDI ionization process. Several partially digested peptides with mass values 3214, 9980, 10325 and 10497 Da were identified. Direct MALDI-MS analysis of cyanogen bromide treated KGF molecule demonstrated the formation of peptides with mass 7567.3, 4992.6 and 3118.6 Da. The high sensitivity of MALDI-MS provided a rapid method for confirming the fidelity of gene expression in the host system. The present work showed that the combined methods of chromatography and mass spectrometry are efficient means for identification and characterization of prebiological and biological molecules.

  5. 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

    A simple empirical equation is presented for the estimation of closed-cup flash points for pure organic liquids. Data needed for the estimation of a flash point (FP) are the normal boiling point (Teb), the standard enthalpy of vaporization at 298.15 K [?vapH°(298.15 K)] of the compound, and the number of carbon atoms (n) in the molecule. The bounds for this equation are: -100?FP(°C)?+200; 250?Teb(K)?650; 20??vap H°(298.15 K)/(kJ mol-1)?110; 1?n?21. Compared to other methods (empirical equations, structural group contribution methods, and neural network quantitative structure-property relationships), this simple equation is shown to predict accurately the flash points for a variety of compounds, whatever their chemical groups (monofunctional compounds and polyfunctional compounds) and whatever their structure (linear, branched, cyclic). The same equation is shown to be valid for hydrocarbons, organic nitrogen compounds, organic oxygen compounds, organic sulfur compounds, organic halogen compounds, and organic silicone compounds. It seems that the flash points of organic deuterium compounds, organic tin compounds, organic nickel compounds, organic phosphorus compounds, organic boron compounds, and organic germanium compounds can also be predicted accurately by this equation. A mean absolute deviation of about 3 °C, a standard deviation of about 2 °C, and a maximum absolute deviation of 10 °C are obtained when predictions are compared to experimental data for more than 600 compounds. For all these compounds, the absolute deviation is equal or lower than the reproductibility expected at a 95% confidence level for closed-cup flash point measurement. This estimation technique has its limitations concerning the polyhalogenated compounds for which the equation should be used with caution. The mean absolute deviation and maximum absolute deviation observed and the fact that the equation provides unbiaised predictions lead to the conclusion that 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.

  6. 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, ?-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 ?-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 homogeneous and heterogeneous systems, macromolecules with dramatically altered properties, and large-scale industrial processes. It is noteworthy that many metalloenzymes employ multiple active centers operating in close synergistic proximity to achieve high activity and selectivity. Such enzymes were the inspiration for the research discussed in this Account, focused on the properties of multimetallic olefin polymerization catalysts. Here we discuss how modifications in organic ligand architecture, metal···metal proximity, and cocatalyst can dramatically modify polyolefin molecular weight, branch structure, and selectively for olefinic comonomer enchainment. We first discuss bimetallic catalysts with identical group 4 metal centers and then heterobimetallic systems with either group 4 or groups 4 + 6 catalytic centers. We compare and contrast the polymerization properties of the bimetallic catalysts with their monometallic analogues, highlighting marked cooperative enchainment effects and unusual polymeric products possible via the proximate catalytic centers. Such multinuclear olefin polymerization catalysts exhibit the following distinctive features: (1) unprecedented levels of polyolefin branching; (2) enhanced enchainment selectivity for linear and encumbered ?-olefin comonomers; (3) enhanced polyolefin tacticity and molecular weight; (4) unusual 1,2-insertion regiochemistry for styrenic monomers; (5) modified chain transfer kinetics, such as M-polymer ?-hydride transfer to the metal or incoming monomer; (6) LLDPE synthesis with a single binuclear catalyst and ethylene. PMID:25075755

  7. Tautomerism and metal complexation of 2-acylmethyl-2-oxazolines: a combined synthetic, spectroscopic, crystallographic and theoretical treatment.

    PubMed

    Jones, Roderick C; Herasymchuk, Khrystyna; Mahdi, Tayseer; Petrov, Anna; Resanovi?, Sanja; Vaughan, Douglas G; Lough, Alan J; Quail, J Wilson; Koivisto, Bryan D; Wylie, R Stephen; Gossage, Robert A

    2013-06-01

    A synthetic, structural and theoretical investigation into the solid-state, solution and gas phase structure(s) of six 2-acylmethyl-4,4-dimethyl-2-oxazolines is reported. Four of these materials, viz.?-[(4,5-dihydro-4,4-dimethyl-2-oxazolyl)methylene]benzenemethanol (3a), ?-[(4,5-dihydro-4,4-dimethyl-2-oxazolyl)methylene]-(4-nitrobenzene)methanol (3b), 1-(4,5-dihydro-4,4-dimethyl-2-oxazolyl)-3,3-dimethyl-1-buten-2-ol (3d) and (E)-1-phenyl-2-((3aR)-3,3a,8,8a-tetrahydro-2H-indeno[1,2-d]oxazol-2-ylidene)ethanone (3f) have been characterised in the solid-state by single crystal X-ray diffraction studies. These data represent the first solid-state structural studies of this class of compounds and details the first synthesis and full characterisation of chiral derivative 3f. All four of these materials are shown to exist in the solid phase in the enamine tautomeric form (e.g., 3a is best described as 2-[4,4-dimethyl-2-oxazolidinylidene]-1-phenylethanone) and it is suggested (NMR, IR) that this isomeric form is likely also retained in solution (e.g., CDCl3) as the more stable isomer. An investigation of the relative gas phase stabilities of the three possible (i.e., the (Z)-enol, keto and enamine) isomers of all five compounds by DFT at the B3LYP/6-311G(d) level of theory confirms the latter as the most stable form. The energy differences between the enamine and keto tautomers have been calculated to be the lowest for derivative 3d. These results are compared and contrasted with the previously reported NMR studies of such compounds which have identified the keto form as being a minor (albeit solution) tautomer. Equilibrium solution tautomer distributions for 3d are found to be solvent dependent. The protonated form of 3a, isolated as the HSO4(-) salt (i.e.4a), has been further characterised in the solid state by single crystal X-ray diffraction. These data represent the first example of a protonated oxazoline to be structurally elucidated and confirms that upon protonation, the keto (oxazoline) tautomer is the energetically favoured form in the solid-state. This observation is further supported by DFT studies for the gas phase protonated forms of such materials. Further DFT (B3LYP/6-311G(d)) calculations employing the SM8 or SMD solvation models were then applied to address the observed solution isomeric distribution for 3d; these results corroborate the gas phase theoretical treatment and also yield values that predict the higher solution stability of the enamine form as observed, although they fail to account for the existence of the keto form as a minor solution state tautomer. To access the availability of an enol-form, via hypothetical de-protonation to the enolate, compound 3a was treated with hydrated Cu(NO3)2 in EtOH solution. The resulting isolated green-coloured product (5), the first metal derivative of this entire class of ligands, is best described (IR, X-ray diffraction) as a coordinated enolate complex, i.e., Cu(3a-H)2. Complex 5 crystallizes in the P21/c space group with four molecules in the unit cell. The coordination geometry around the formal Cu(2+) metal centre is determined to be highly distorted square planar in nature (?4 = 0.442). TD-DFT is used to give a reasonable explanation for the intensity of the absorbance band observed in the visible region for solutions of 5. These latter experiments strongly suggest that the title class of compounds may have considerable potential as ligands in coordination chemistry and/or metal-mediated catalysis. PMID:23591452