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1

Reaction rate and isomer-specific product branching ratios of C2H + C4H8: 1-butene, cis-2-butene, trans-2-butene, and isobutene at 79 K.  

PubMed

The reactions of C2H radicals with C4H8 isomers 1-butene, cis-2-butene, trans-2-butene, and isobutene are studied by laser photolysis-vacuum ultraviolet mass spectrometry in a Laval nozzle expansion at 79 K. Bimolecular-reaction rate constants are obtained by measuring the formation rate of the reaction product species as a function of the reactant density under pseudo-first-order conditions. The rate constants are (1.9 ± 0.5) × 10(-10), (1.7 ± 0.5) × 10(-10), (2.1 ± 0.7) × 10(-10), and (1.8 ± 0.9) × 10(-10) cm(3) s(-1) for the reaction of C2H with 1-butene, cis-2-butene, trans-2-butene, and isobutene, respectively. Bimolecular rate constants for 1-butene and isobutene compare well to values measured previously at 103 K using C2H chemiluminescence. Photoionization spectra of the reaction products are measured and fitted to ionization spectra of the contributing isomers. In conjunction with absolute-ionization cross sections, these fits provide isomer-resolved product branching fractions. The reaction between C2H and 1-butene yields (65 ± 10)% C4H4 in the form of vinylacetylene and (35 ± 10)% C5H6 in the form of 4-penten-1-yne. The cis-2-butene and trans-2-butene reactions yield solely 3-penten-1-yne, and no discrimination is made between cis- and trans-3-penten-1-yne. Last, the isobutene reaction yields (26 ± 15)% 3-penten-1-yne, (35 ± 15)% 2-methyl-1-buten-3-yne, and (39 ± 15)% 4-methyl-3-penten-1-yne. The branching fractions reported for the C2H and butene reactions indicate that these reactions preferentially proceed via CH3 or C2H3 elimination rather than H-atom elimination. Within the experimental uncertainties, no evidence is found for the formation of cyclic species. PMID:23701666

Bouwman, Jordy; Fournier, Martin; Sims, Ian R; Leone, Stephen R; Wilson, Kevin R

2013-06-20

2

Scattering of electrons from 1-butene, H2C=CHCH2CH3, and 2-methylpropene, H2C=C(CH3)2, molecules  

NASA Astrophysics Data System (ADS)

We report absolute grand total cross sections (TCSs) for electron scattering from 1-butene (H2C=CHCH2CH3) and 2-methylpropene (H2C=C(CH3)2) molecules, measured at electron impact energies ranging from 1 to 400 eV and from 1 to 350 eV, respectively, using a linear electron-transmission technique. The general shape of cross sections for both butene isomers looks similar. Two structures in each TCS energy curve are discernible: a small peak in the vicinity of 2.3 eV and a pronounced very broad enhancement with the maximum located around 8 eV. The magnitude of TCS for 2-methylpropene appears somewhat higher than that for 1-butene below 20 eV, while above 70 eV the TCS curves practically overlap. In addition, comparison is made of TCSs for an ethylene (H2C=CH2) molecule and its mono and double methyl-substituted derivatives: propene (H2C=CHCH3) and 2-methylpropene.

Mo?ejko, Pawe?; Ptasi?ska-Denga, El?bieta; Szmytkowski, Czes?aw; Zawadzki, Mateusz

2012-07-01

3

Productivity selectivity in the infrared laser induced reaction of trans-2-butene  

SciTech Connect

The infrared multiple-photon photolysis of trans-2-butene was investigated at five CO/sub 2/ wavelengths from 942 to 1031 cm/sup -1/ and at conversions from a few percent to approximately 95%. The reaction products at 50 m Torr and fluences of approximately 125 J/cm/sup 2/ were cis-2-butene, ethylene, ethane, propylene, propyne, 1,3-butadiene, 1-butene, and 2-butyne. Relative product yields of cis-2-butene and propyne varied significantly with both wavelength and conversion. The results of an investigation of the observed product selectivity are presented.

Guckert, J.R.; Carr, R.W.

1986-10-23

4

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

PubMed

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

Arnts, Robert R

2008-10-15

5

Reactions of 1-Butene and cis-2-Butene on Platinum Surfaces:Structure Sensitivity of cis-2-Butene Isomerization  

SciTech Connect

The hydrogenation and isomerization of 1-butene and cis-2-butene molecules are studied on platinum foil and single crystal(111), (100), and the stepped (755) surfaces at 300-350 K. In the presence of hydrogen, 1-butene and cis-2-butene are hydrogenated to butane. In addition, 1-butene is isomerized to cis- and trans-2-butenes,while cis-2-butene is converted to trans-2-butene. With a hydrogen pressure between 7 and 500 Torr, and a butene pressure of 3.5-70 Torr,both butene hydrogenation and isomerization rates exhibit a near-first-order dependence on the hydrogen pressure and a zero-order dependence on the hydrocarbon pressures. For both 1-butene and cis-2-butene molecules, the hydrogenation rates are insensitive to surface structures. The isomerization rate, however, is doubled for cis-2-butene molecules on the stepped platinum surface(Pt(755)).

Yoon, Cheonho; Yang, Michael X.; Somorjai, Gabor A.

1997-12-01

6

Stereoselective photooxidation of trans-2-butene to epoxide by nitrogen dioxide excited with red light in a cryogenic matrix  

SciTech Connect

Reaction was induced between trans-2-butene and nitrogen dioxide by exciting trans-2-butene-NO{sub 2} pairs, isolated in solid Ar at red, yellow, and green wavelengths (NO{sub 2}{sup 2}B{sub 2} {l arrow} {anti X}{sup 2}A{sub 1}). The chemistry was monitored by FT-infrared spectroscopy, and Ar ion and cw dye lasers were used for photolysis. Products formed were 2-butene oxide + NO, the former under complete retention of stereochemistry, and an addition product that was identified by {sup 18}O isotopic substitution as a butyl nitrite radical, reported here for the first time. Analysis of the photolysis-wavelength dependence of the butyl nitrite radical and trans-2-butene oxide (NO) growth kinetics revealed that epoxide + NO is formed along two reaction pathways. The first gives trans-2-butene oxide + NO and butyl nitrite radical upon absorption of a single photon by trans-2-butene-NO{sub 2} pairs (one-photon path). The second path is formation of trans-2-butene oxide + NO by photodissociation of trapped butyl nitrite radical by a (second) red or shorter wavelength photon (two-photon path). Two alternative transients are proposed for the one-photon path, namely a hot butyl nitrite radical and an oxirane biradical, respectively. The wavelength dependence of the product branching along the one-photon path indicates that branching occurs from a vibrationally unrelaxed transient. This suggests that the observed stereochemical integrity originates from insufficient coupling of the stretching and bending vibrations of the transient with torsion around its central C-C bond on the time scale of reaction to epoxide + NO and its stabilization as butyl nitrite radical.

Nakata, Munetaka; Frei, H. (Lawrence Berkeley Lab., CA (USA))

1989-07-05

7

First-principles calculations of adsorption and dehydrogenation of trans-2-butene molecule on Pd(110) surface  

NASA Astrophysics Data System (ADS)

Adsorption and dehydrogenation processes of trans-2-butene molecule on the Pd(110) surface have been studied by density functional theory calculations. Different adsorption configurations of the reactant, the dehydrogenated product, and the most favorable reaction pathway have been determined. The calculated energy barrier agrees well with the value deduced from experiments. It is found that the reactant molecule must undergo a rotation before the C-H bond cleavage, and surface Pd atoms are involved in the dehydrogenation reaction through the formation of the Pd-C-H three-membered metallacycle. Our calculations have not only provided reliable interpretation for various experimental observations but also shed more light on the dynamics of the reaction processes.

Fu, Qiang; Yang, Jinlong; Luo, Yi

2009-10-01

8

Reaction pathways of cis- and trans-2-butene on Mo(110) and C/Mo(110):. selective activation of ? and ? C-H bonds  

NASA Astrophysics Data System (ADS)

The reaction pathways of cis- and trans-2-butene on clean Mo(110) and carbide-modified Mo(110) surfaces have been studied using a combination of temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). The vibrational data reveal that the decomposition pathways of cis- and trans-2-butene are different on clean Mo(110). In the case of cis-2-butene, the olefinic ?(C-H) bonds are cleaved at 80 K to produce surface hydrogen and 2-butyne. In contrast, the initial decomposition of trans-2-butene also involves ?(C-H) bond scission, such that at least one of the methyl groups of the molecule is converted to a CH 2 group at temperatures below 150 K. On carbide-modified Mo(110), the initial decomposition step for both cis- and trans-2-butene involves ?(C-H) bond cleavage to form 2-butyne. This difference in reactivity of Mo(110) and carbide-modified Mo(110) towards the 2-butenes provides experimental evidence that the formation of the carbide overlayer enhances the selective activation of ?(C-H) bonds.

Eng, Joseph; Chen, Jingguang G.

1998-09-01

9

FT-IR product study of the gas-phase Br-initiated oxidation of trans-2-butene under atmospheric conditions between 246 and 298 K  

Microsoft Academic Search

The products of the Br-atom initiated oxidation of trans-2-butene have been studied in a largevolume reaction chamber between 246 and 298 K using in situ FT-IR for the analysis. 3-Bromobutan-2-one, acetaldehyde and acetylbromide were the major products of this oxidation process. Additional products included formaldehyde and hydrogen bromide and evidence was found for the formation of 3-bromobutan-2-hydroperoxide. Decreasing the temperature

A. Bierbach; I. Barnes; K. H. Becker

1997-01-01

10

Oxygen exchange into 2-butanol and hydration of 1-butene do not proceed through a common carbocation intermediate  

SciTech Connect

The acid-catalyzed isomerization of the 4-methyl group of 1,1,1,2,3,3-hexadeuteriated 2-butanol between the 1- and 4-positions occurs faster than dehydration to 2-butene, as measured by hydrogen incorporation from water into the 3-position of 2-butanol. The rate constants for these processes are k/sub isom/ = 1.1 x 10/sup -6/ s/sup -1/ and k/sub hyd/ = 5.6 x 10/sup -7/ s/sup -1/, respectively, in 0.55 M HClO/sub 4/ at 100/sup 0/C. These results require that isomerization occurs by hydride transfer from C-3 to C-2, as well as by the formation and hydration of 2-butene. The 6% initial yield of isomerized product in the acid-catalyzed hydration of (4-/sup 14/C)-1-butene, before there is significant accumulation of 2-butene (Manassen, J.; Klein, F. J. Chem. Soc. 1960, 4023), shows that hydride transfer is also significant in this reaction. Comparison of the product yields from 1-butene and the rate constants for isomerization and oxygen exchange of (4-/sup 14/C)-2-butanol in the earlier work shows that the two reactions do not occur through a common carbocation intermediate. The preferential formation of cis-2-butene from 1-butene and trans-2-butene from 2-butanol confirms this conclusion.

Dietze, P.E.; Jencks, W.P.

1987-04-01

11

Isomerization of 1-butene on silica-alumina: Kinetic modeling and catalyst deactivation  

SciTech Connect

In the study of 1-butene isomerization on a silica-alumina catalyst 448--523 K, cis-2-butene and trans-2-butene are detected. Based on BSTR experimental data and zero-time prediction kinetic models using the Langmuir-Hinshelwood mechanism are assumed to develop kinetic equations for which a triangular reaction scheme is used. In four different mechanisms, one and two active sites take part in the surface reaction as the controlling step and then the deactivation rate determined considering two types of experimental data from BSTR and by measuring weight changes of a catalyst particle from coke deposition in an electrobalance. A coke precursor is assumed formed by reaction of adsorbed molecules (of any butene isomer) and gas-phase molecules. Activity and coke-content-time data allow one to choose a model whose activation energies of the deactivation kinetic parameter are closer in value. Coke is assumed deposited in a monolayer. The model chosen shows a triangular scheme, kinetic equations of the reaction for fresh catalyst with two active sites in the surface reaction, and the deactivation rate according to a coke formation mechanism in which a precursor is formed by reaction of 3 adsorbed molecules and 1 molecule in the gas phase. It accurately fits both BSTR conversion-time data and electrobalance coke-content data. The coke formation mechanism establishes relationships of activity vs. coke content and catalyst acidity which are supported by experimental results.

Garcia-Ochoa, F.; Santos, A. (Univ. Complutense, Madrid (Spain). Dept. de Ingenieria Quimica)

1995-02-01

12

Oxidative dehydrogenation of 1-butene over manganese oxide octahedral molecular sieves  

SciTech Connect

Steady state kinetic studies of the oxidative dehydrogenation of 1-butene to 1,3-butadiene have been carried out on manganese oxide octahedral molecular sieve (OMS) and octahedral layered (OL) materials. Process parameters such as temperature, feed composition of 1-butene and oxygen, and feed flow rates were varied to study their effect on the activity and selectivity toward the oxidative dehydrogenation process. In addition to process parameters, modifications in the catalyst such as the ion-exchange of tunnel cations and framework substitution of manganese cations were also implemented in order to observe their effects on catalytic activity and the selectivity of 1,3-butadiene production. The ion-exchanged OMS and OL materials showed rapid deactivation with time when subjected to reaction mixtures of 1% 1-butene/0.7% oxygen/Ar and 1% 1-butene/1.1% oxygen/Ar at reaction temperatures greater than 400 C. Their selectivity toward 1,3-butadiene were typically from 15--20% (yield of 4--6%). The other products were cis and trans 2-butene and carbon dioxide and water (40--60% selectivity). Much of the oxidation was therefore nonselective. XRD data have shown that there is a phase change of the original precursor to a mixture of Mn{sub 3}O{sub 4}/MnO or plain MnO, in some cases after exposing the catalyst to reaction conditions for about 1--2 h. Framework substitution of some of the manganese with copper (OMS and OL), however, has led to higher yields and selectivities toward 1,3-butadiene. [Cu] OL-1 showed a yield of 11.8% and a maximum selectivity of 26% toward 1,3-butadiene. [Cu] OMS-1 shows a dramatically high selectivity of 36% and a yield of 11% toward 1,3-butadiene. The effect of framework substitution seems to also impede the phase change to Mn{sub 3}O{sub 4} (Hausmannite). The TPR spectra also show an increase in the lattice oxygen peak by about 40 C, in comparison with ion-exchanged OMS. This is sufficient indication that framework substitution of manganese by copper, partially, has enhanced the stability of the catalyst and improved its capacity for selective oxidation.

Krishnan, V.V.; Suib, S.L. [Univ. of Connecticut, Storrs, CT (United States)] [Univ. of Connecticut, Storrs, CT (United States)

1999-06-10

13

The Bond Dissociation Energies of 1-Butene  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

14

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

SciTech Connect

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

Drake, C.A.

1986-08-19

15

Adsorption of oxygen and 1-butene on magnesium ferrite  

SciTech Connect

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

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

1986-08-01

16

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

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Poly-1-butene resins and butene/ethylene copolymers. 177...Surfaces § 177.1570 Poly-1-butene resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers...

2012-04-01

17

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

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Poly-1-butene resins and butene/ethylene copolymers. 177...Surfaces § 177.1570 Poly-1-butene resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers...

2011-04-01

18

Forestomach lesions in rats and mice administered 3-chloro-2-methylpropene by gavage for two years.  

PubMed

The carcinogenicity of 3-chloro-2-methylpropene (CMP), a chemical intermediate and insecticide, was studied because of possible human exposure and because of its structural relationship to vinyl chloride and allyl chloride. CMP in corn oil was administered by gavage to groups of 50 male and 50 female Fischer 344/N rats at 0, 75, or 150 mg/kg body weight and to groups of 50 male and 50 female B6C3F1 mice at 0, 100, or 200 mg/kg body weight, 5 times a week for 103 weeks. The body weights of the two CMP treated groups of rats were 3-15% lower than the controls; the survival rates were similar. The body weights and survival rates of the CMP-exposed male and female mice were not different from the respective controls throughout the study. CMP administration resulted in dose-related increases in the incidence and severity of forestomach basal cell hyperplasia and the incidence of forestomach squamous cell papillomas in both sexes of rats and mice. In the two groups of CMP-exposed male mice the incidences of squamous cell carcinoma of the forestomach were also increased. Invasion or metastasis of the squamous cell carcinomas to other organs was observed in 2 male mice treated at 100 mg/kg and in 3 male mice and one female mouse treated at 200 mg/kg. The data show that CMP is a carcinogen for the forestomach in rats and mice and acts at the tissue site of contact and support genetic toxicity findings that CMP is a direct-acting alkylating agent. PMID:3779651

Chan, P C; Haseman, J K; Boorman, G A; Huff, J; Manus, A G; Cardy, R H

1986-12-01

19

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

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

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

2010-01-01

20

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

SciTech Connect

A process is described for recovering 3-methyl-1-butene from a hydrocarbon stream containing 3-methyl-1-butene and compounds which form azeotropes with 3-methyl-1-butene comprising extractive distillation of the hydrocarbon stream with a solvent mixture comprising dimethylformamide and sulfolane solvent mixture present in an amount ranging from about 0.1 to about 20 times the weight of the hydrocarbon stream. The dimethylformamide in the dimethylformamide/Sulfolane solvent mixture is present in an amount ranging from about 30 weight percent to about 70 weight percent based on the weight of the mixture. This separates insolubles containing the 3-methyl-l-butene as the overhead product stream from the bottoms product containing soluble compounds, the compounds that form azeotropes with 3-methyl-l-butene and the solvent mixture and thereafter recovering the 3-methyl-1-butene from the insolubles.

Drake, C.A.

1986-12-16

21

Poly (1Butene)\\/Clay Nanocomposites: A Crystallization Study  

Microsoft Academic Search

Nanocomposites of poly (1-butene) (PB)\\/clay were prepared by melt intercalation. Organically modified clay was used to facilitate the melt intercalation. The effect of modified layered silicate on crystallization, spherulitic structures and polymorphism of PB was investigated. Isothermal crystallization studies clearly indicate enhancement in crystallization rate by the clay. Incorporation of layered silicate in the polymer disturbs the spherulitic morphology as

Santosh D. Wanjale; J. P. Jog

2003-01-01

22

Crossed-beam slice imaging of Cl reaction dynamics with butene isomers.  

PubMed

We present a crossed-beam imaging study of the reaction of chlorine atoms with several butene isomers. A high-intensity pulsed ablation Cl source is used with DC slice imaging and single-photon ionization detection at 157 nm to record the velocity-flux contour maps for these reactions. The target unsaturated hydrocarbons are 1-butene, trans-2-butene, cis-2-butene, and isobutene (2-methylpropene). Data are obtained at collision energies of ~13.0 kcal·mol(-1). Distinct differences in the scattering distributions and in particular the coupling of angular and translational energy release provide insight into the dynamics of this little-studied class of reactions. We find that these distributions reflect the energetics for competition between addition/elimination and direct abstraction in line with ab initio thermochemical data. A possible role for Cl atom roaming mediating the addition/elimination pathway is suggested. PMID:23721246

Joalland, Baptiste; Van Camp, Richard; Shi, Yuanyuan; Patel, Nitin; Suits, Arthur G

2013-08-15

23

Study of chemisorption and hydrogenation of 1-butene on platinum by temperature-programmed desorption  

SciTech Connect

The temperature-programmed desorption (TPD) chromatograms of 1-butene from platinum black comprised four peaks, A, B, C, and D, with peak maxima at about 265, 390, 580, and higher than 770 K, respectively. Peak A was identified to be 1-butene with a trace amount of n-butane. Peaks B and C were the mixtures of 1-butene and propylene. Peak D was methane. The methane and propylene were formed from chemisorbed 1-butene by decomposition as the temperature was raised during the subsequent TPD. The reactivities of various types of chemisorbed hydrogen previously detected by TPD were also investigated with regard to the hydrogenation of 1-butene. Two types of chemisorbed hydrogen, presumed to be present on the surface in the form of hydrogen atoms chemisorbed on top of platinum atoms and in the bridge form of molecular hydrogen, were found to react with 1-butene.

Tsuchiya, S.; Yoshioka, N.

1984-05-01

24

Mechanism of 1-butene hydration over acidic zeolite and ion-exchange resin catalysts  

Microsoft Academic Search

Vapour-phase hydration of 1-butene at atmospheric pressure above 373 K shows similar features on both H-clinoptilolite and sulphonic acid ion-exchange resin: the initial reaction rate linearly increases with the partial pressure of 1 -butene and passes through a maximum as a function of water pressure. Kinetics was evaluated accordingly. A decrease in the 1-butene isomerization rate indicated that under hydration

Dénes Kalló; R. Magdolna Mihályi

1995-01-01

25

Skeletal isomerization of 1-butene on MCM-22 zeolite catalyst  

SciTech Connect

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 of n-butene conversion, and a maximum of isobutene yield is found at ca. 50% conversion. Besides isobutene, propylene and pentanes, which are formed by dimerization-cracking reactions products. Isobutene also takes part, together with the n-butenes, in the formation of by-products thorough dimerization and/or codimerization processes, which would also lead to a lower isobutene selectivity. Moreover, the yield of isobutene increases with increasing reaction temperature and decreasing 1-butene partial pressure, while the contrary holds for the formation of by-products. On the basis of these results the mechanism of formation of isobutene and the different by-products on MCM-22 is discussed. Finally, the selectivity to isobutene is strongly improved by increasing the Si/Al ratio of the zeolite, which is explained by a decrease of the undesired consecutive reactions when decreasing the density of Broensted acid sites of the zeolite. 24 refs., 6 figs., 6 tabs.

Asensi, M.A.; Corma, A.; Martinez, A. [Universidad Politecnica de Valencia (Spain)] [Universidad Politecnica de Valencia (Spain)

1996-02-01

26

Catalytic cracking process utilizing an iso-olefin enhancer catalyst additive  

SciTech Connect

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

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

1993-08-10

27

Skeletal isomerisation of 1-butene on tungsten oxide catalysts  

SciTech Connect

Several {gamma}-Al{sub 2}O{sub 3}-supported tungsten oxide catalysts have been studied in the skeletal isomerisation of 1-butene. It appears that the presence of small tungsten oxide particles induces skeletal isomerisation. Large particles can be activated by prereduction treatment with hydrogen. It was shown that the selectivity and stability of the catalysts depend strongly on the tungstate loading. A sudden increase in selectivity is observed when dimeric WO{sup 2-}{sub 4} species are formed. A low density of active sites presents deactivation, which is caused by carbonization of the catalyst due to oligomerisation of isobutene. The main by-products, C{sub 3} and C{sub 5} hydrocarbons, arise from the dimerisation and cracking of isobutene. 33 refs., 10 figs., 1 tab.

Gielgens, L.H.; Kampen, M.G.H. van; Broek, M.M. [Leiden Univ. (Netherlands)] [and others] [Leiden Univ. (Netherlands); and others

1995-07-01

28

Computer simulations of the adsorption and diffusion processes of 1-butene in MCM-22 zeolite  

NASA Astrophysics Data System (ADS)

The adsorption and diffusion of 1-butene in purely siliceous MCM-22 zeolite have been studied by the grand canonical Monte Carlo and molecular dynamic simulation. The adsorption behavior of 1-butene was explored in detail from adsorption sites, interaction energies. The mass clouds show that 1-butene can be adsorbed freely in MCM-22 zeolite, and adsorbed preferentially in 10-MR (member rings) channel system with high interaction energy. The diffusion characteristic for 1-butene in two independent channel systems was investigated by using molecular dynamic simulation. The results were obtained by analysis the trajectories of diffusion and the diffusion coefficients, which shows that a large diffusion for 1-butene in both channel systems, especially in the supercage system. The adsorption and the diffusion of the hydrocarbon molecules were affected by the different sizes and structures of 10-MR and 12-MR in MCM-22 zeolite. Moreover, the positions where the molecules are expected to react were revealed.

Zhang, Guo; Zheng, Qing-Chuan; Zhang, Hong-Xing; Liu, Tao; Zhu, Yu-Jun; Fu, Hong-Gang

2009-05-01

29

Reviews: Commercial production and principal trends in the use of 1-butene  

SciTech Connect

1-Butene is an important petrochemical product, the production volume of which is increasing steadily. On the one hand, this trend reflects on the one hand, expanded capacity in a number of processes in which 1-butene is a byproduct (catalytic cracking, ethylene oligomerization); on the other hand, it reflects the expansion of processes aimed directly at 1-butene production. The main consumer of 1-butene is the USA, which accounts for about 40% of the world production volume. In Russia, processes aimed directly at 1-butene production have been set up in three plants, with a production volume of less than 10,000 tonnes/yr. In addition, 1-butene is formed as a byproduct in the process of low-temperature ethylene oligomerization, in amounts up to 10% of the total volume of oligomer production. 1-Butene is finding extensive applications as an initial component in a number of commercial processes for organic synthesis, and also as a monomer and comonomer, where its use is the most promising and where the volume is increasing the most rapidly. Hence it is of interest to examine the trends in Russia and other countries in the use of oligomeric and cooligomeric products.

Kotov, S.V.; Kankaeva, I.N.

1995-01-01

30

Catalytic conversion of methane and propylene to 1-butene  

SciTech Connect

The oxidative cross-coupling of methane with propylene has been studied over several catalysts. A material containing 1.9 wt % Mn and 5 wt % NaCl on SiO{sub 2} was found to be the most effective for this reaction. At 650{degree}C, it was possible to attain selectivities to 1-butene and butadiene of 57% and 8.0%, respectively, at a propylene conversion of 38%. Experiments utilizing {sup 13}CH{sub 4} confirm that methane was indeed involved in the formation of the C{sub 4} products. Methyl radicals derived from CH{sub 4} and allyl radicals derived from C{sub 3}D{sub 6} were simultaneously detected over the catalysts using a matrix isolation electron spin resonance method. These surface-generated radicals enter the gas phase, where most of the coupling is believed to occur. In addition to the cross-coupling reaction, methyl radicals couple to form ethane, and allyl radicals couple to form 1,5-hexadiene. The latter hydrocarbon reacts extensively back to propylene over the catalysts at 650{degree}C. 28 refs., 4 figs., 10 tabs.

Lunsford, J.H.; Rosynek, M.P.; Smith, C.E.; Xu, M.; Yu, Z. [Texas A& M Univ., College Station, TX (United States)

1995-08-17

31

Interaction of 1-butene and n-butane with a sulfate-promoted iron oxide  

SciTech Connect

Interactions of sulfate-promoted iron oxide So{sub 4}{sup 2-} -Fe{sub 2}O{sub 3} with 1-butene and n-butane were investigated by means of infrared spectroscopy and temperature-programmed desorption/reaction coupled with mass spectrometry. By reacting with the sulfate ion, 1-butene adsorbed on SO{sub 4}{sup 2-}-Fe{sub 2}O{sub 3} promoted sulfate decomposition. In contrast, adsorbed n-butane desorbed readily upon heating above 320 K. Implications of these findings in catalysis by this material are discussed.

Lee, J.S.; Yeom, M.H.; Park, D.S. (Pohang Institute of Science and Technology and Research Institute of Industrial Science and Technology (Korea))

1990-12-01

32

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

Microsoft Academic Search

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

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

2003-01-01

33

Comment on ‘Photoelectron and electron momentum spectroscopy of 1-butene at benchmark theoretical levels’  

NASA Astrophysics Data System (ADS)

The claim by Shojaei et al (2011 J. Phys. B: At. Mol. Opt. Phys. 44 235101) that the entropy difference between the cis and gauche conformers of 1-butene changes dramatically upon inclusion of hindered-rotor corrections is shown to be incorrect.

Børve, Knut J.

2012-12-01

34

Synergy effects between ? and ? phases of bismuth molybdates in the selective catalytic oxidation of 1-butene  

Microsoft Academic Search

?+? mixed Bi–Mo–O phases with a large range of composition were prepared by coprecipitation for investigating the existence of synergetic effects between ? and ? phases for the oxidative dehydrogenation of 1-butene.Results from surface characterization show that the surface of the catalysts always has a composition similar to the ? phase but the ? phase grows around ? phase. Mixed

Ana Paula Vieira Soares; Lubjmir Dimitrov Dimitrov; Margarida Corte-Real André de Oliveira; Leonel Hilaire; Manuel Farinha Portela; Robert Karl Grasselli

2003-01-01

35

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

Code of Federal Regulations, 2013 CFR

...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,â...

2013-04-01

36

Phase equilibria of binary and ternary n-alkane solutions in supercritical ethylene, 1-butene, and ethylene + 1-butene: Transition from type A through LCST to U-LCST behavior predicted and confirmed experimentally  

SciTech Connect

Binary phase equilibria of C[sub 20] +, C[sub 30] +, and C[sub 40] + ethylene are correlated with three equations of state, the Redlich-Kwong-Soave (Soave), the generalized van der Waals-Prigogine (vdW-P), and the statistical associating fluid theory (SAFT), with special emphasis on the mixture critical region. The SAFT correlation is found to be the most reliable. SAFT predictive powers are tested on C[sub 26] + ethylene and a new set of experimental data taken in this work for C[sub 36] + 1-butene and C[sub 36] + ethylene + 1-butene. The SAFT predictions are found to be in good agreement with the experimental data. Equally important, the SAFT predictions allow for understanding the continuous transition of phase behavior, from type A (C[sub 36] + 1-butene) through LCST (C[sub 36] + ethylene + 1-butene) to U-LCST (C[sub 36] + ethylene).

Gregg, C.J.; Stein, F.P. (Lehigh Univ., Bethlehem, PA (United States). Dept. of Chemical Engineering); Chen, Shenjer; Radosz, M. (Exxon Research and Engineering Co., Annandale, NJ (United States))

1993-07-01

37

Skeletal isomerization of 1-butene over ferrierite and ZSM-5 zeolites: influence of zeolite acidity  

Microsoft Academic Search

Three ferrierite (FER) and five ZSM-5 (MFI) zeolites with SiO2Al2O3 ratio ranging from 27 to 2000 are tested as catalysts for the skeletal isomerization of 1-butene at 350–450°C and atmospheric total pressure in order to study the influence of acidity and pore structure of zeolite on conversion and selectivity. The catalytic and NH3 temperature-programmed desorption results from FER and MFI

Gon Seo; Hwan Seok Jeong; Suk Bong Hong; Young Sun Uh

1996-01-01

38

Morphology, structure and properties of a poly(1-butene)\\/montmorillonite nanocomposite  

Microsoft Academic Search

A specifically formulated nanocomposite based on isotactic poly(1-butene) (PB) and montmorillonite was studied, by wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and polarized light optical microscopy, investigating the polymorphism of the polymer, and examining the interaction between PB and the silicate. Montmorillonite was found to disrupt the ordered morphology of the polymer, determining

Valerio Causin; Carla Marega; Antonio Marigo; Giuseppe Ferrara; Gulnaz Idiyatullina; Fabiana Fantinel

2006-01-01

39

Surface properties of zirconium oxide and its catalytic activity for isomerization of 1-butene  

Microsoft Academic Search

Surface properties of zirconium oxide and its catalytic activity for isomerization of 1-butene isomerization, and its cis\\/trans selectivity were tested on catalysts calcined at 300°⁻⁹°°sup 0\\/C and correlated to the acidity, measured by IR spectroscopy of adsorbed pyridine; basicity measured by adsorption of COâ or ESR spectroscopy of adsorbed diphenylamine and oxygen; oxidizing sites, measured by ESR spectroscopy of adsorbed

Y. Nakano; T. Iizuka; H. Hattori; K. Tanabe

1979-01-01

40

Hydrogenation of 1-butene and 1,3-butadiene mixtures over Pd\\/ZnO catalysts  

Microsoft Academic Search

Several palladium catalysts supported on ZnO with different loadings and dispersions have been prepared, characterized, pretreated, and tested for the selective hydrogenation of small amounts of 1,3-butadiene in 1-butene. Hydrogen treatment at temperatures above 423 K caused a marked decrease in catalytic activity and a simultaneous increase in selectivity for reduction of butadiene primarily to olefins. Such treatment also caused

A. Sarkany; Z. Zsoldos; L. Guczi; B. Furlong; J. W. Hightower

1993-01-01

41

Effect of molecular weight on the polymorphic transformation of isotactic poly(1-butene)  

Microsoft Academic Search

The effect of molecular weight on the polymorphic transformation of isotactic poly(1-butene)(iPB) under room temperature had been investigated by fourier transform infrared spectroscopy(FT-IR). The phase transformation time, phase transformation rate and phase transformation time difference between phase I and phase II at a given transformation degree were used to analysis the phase transformation kinetics of iPB aging at room temperature.

Aihua He; Chunsheng Xu; Huafeng Shao; Wei Yao; Baochen Huang

2010-01-01

42

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

Microsoft Academic Search

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

Santosh D. Wanjale; Jyoti P. Jog

2006-01-01

43

NTP Toxicology and Carcinogenesis Studies of 3-Chloro-2-methylpropene (Technical grade containing 5% dimethylvinyl chloride) (CAS No. 563-47-3) in F344/N Rats and B6C3F1 Mice (Gavage Studies).  

PubMed

Toxicology and carcinogenesis studies of technical-grade 3-chloro-2-methylpropene (containing 5% dimethylvinyl chloride), a widely used insecticide and a chemical intermediate, were performed on F344/N rats and B6C3F1 mice. In the 13-week studies, 50%-100% mortality occurred in groups of male and female rats receiving 400 mg/kg, male rats receiving 300 mg/kg, and male and female mice receiving 500-1,250 mg/kg. Inflammation and necrosis of the liver were seen in rats and mice, and necrosis of cortical tubules of the kidney was seen in mice. Based on these observations, groups of 50 male and 50 female rats were administered 3-chloro-2-methylpropene in corn oil by gavage at doses of 0, 75, or 150 mg/kg body weight, 5 days per week for 103 weeks, and groups of 50 male and 50 female mice received 3-chloro-2-methylpropene at 0, 100, or 200 mg/kg on the same schedule. In the 2-year studies, the mean body weight of high dose male rats was consistently 10%-15% lower than that of the vehicle control group, and late in the study there was a marginal reduction in survival of high dose male rats. Mean body weights and survival in low dose male rats and in both dosed groups of female rats were comparable to those of their vehicle control groups. Mean body weights of high dose male mice and of both dosed groups of female mice were slightly (5%-9%) lower than those of the vehicle controls, whereas survival in both male and female mice was not affected by 3-chloro-2-methylpropene administration. Dose-related increases in the incidence of forestomach inflammation were observed in male and female mice (male: vehicle control, 0/49; low dose, 9/49; high dose, 7/49; female: vehicle control, 2/50; low dose, 3/48; high dose, 9/44). Increased incidences of forestomach basal cell hyperplasia were observed in rats and mice of each sex. 3-Chloro-2-methylpropene induced forestomach squamous cell papillomas and squamous cell carcinomas in rats and mice as shown in the table. Invasion or metastasis of the squamous cell carcinomas to other organs was observed in two low dose male, three high dose male, and one high dose female mice. Renal tubular cell adenocarcinomas (1/49), renal transitional cell carcinomas (1/49), and transitional cell papillomas (1/49) of the urinary bladder were observed in high dose male rats, and renal tubular cell adenomas (1/50) and renal tubular cell adenocarcinomas (1/50) were seen in low dose male rats. These urinary tract neoplasms were not observed in vehicle controls. The incidences of inflammation of the nasal cavity and of nephropathy/nephrosis were greater in the two dosed groups than in the vehicle control groups of rats and mice of each sex. Negative trends or lower incidences of pheochromocytomas of the adrenal gland and C-cell adenomas or carcinomas (combined) of the thyroid gland were observed in dosed male rats. Negative trends were observed in the incidences of hepatocellular adenomas or carcinomas (combined) in dosed male mice and of hemangiomas or hemangiosarcomas (combined) in dosed female mice. 3-Chloro-2-methylpropene was weakly mutagenic in Salmonella typhimurium strain TA1537 with 10% rat liver S9; results in strain TA100 with 10% Syrian hamster liver S9 or with 10% or 30% rat liver S9 were judged equivocal. Mutagenicity tests with S. typhimurium strains TA1535 and TA98 were negative with or without metabolic activation. 3-Chloro-2-methylpropene was mutagenic in the mouse lymphoma L5178/TK+/- forward mutation assay without exogenous metabolic activation. Cytogenetics tests with cultured Chinese hamster ovary cells were positive for induction of chromosomal aberrations and sister-chromatid exchanges (SCE's) in the absence of rat liver S9. With metabolic activation, SCE levels remained significantly elevated, but the number of chromosomal aberrations was reduced. An audit of the experimental data was conducted for these 2-year carcinogenesis studies on 3-chloro-2-methylpropene. No data discrepancies were found that influenced the final interpretations. Under the conditions of these 2-year gavage studies, d

1986-06-01

44

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

NASA Technical Reports Server (NTRS)

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

Cleaves, Alden P; Sherrick, Mildred E

1946-01-01

45

Adsorption of butane, 2-methylpropane, and 1-butene on activated carbon  

SciTech Connect

Four adsorption isotherms at 278, 288, 293, and 303 K of butane, 2-methylpropane, and 1-butene are obtained on activated carbon. The results at pressures up to 0.8P/P[sub s] are measured on an automated apparatus and correlated by the vacancy solution model of Cochran and Danner. This work aims at determining the influence of a double bond and a branched structure on the adsorption capacity. For their industrial separation by an adsorption process, it is important to have equilibrium data on the same adsorbent and at different temperatures.

Olivier, M.G.; Berlier, K.; Jadot, R. (Faculte Polytechnique de Mons (Belgium). Service de Thermodynamique)

1994-10-01

46

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

Microsoft Academic Search

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

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

47

Potassium promotion of iron oxide dehydrogenation catalysts supported on magnesium oxide: 2. 1-Butene dehydrogenation activity  

SciTech Connect

Potassium promotion of iron oxide catalysts supported on magnesium oxide results in considerably more active and selective 1-butene dehydrogenation catalysts. Upon promotion the activation energy was found to decrease from 194 to 156 kJ/mol. KFeO[sub 2] appeared to be the active phase under dehydrogenation conditions. No reduction of KFeO[sub 2] was observed. KFeO[sub 2] shows high 1-butene dehydrogenation activity, yet is not sufficiently effective to suppress coking entirely. For that purpose the presence of highly dispersed potassium carbonate at the catalyst surface is a prerequisite. Under identical dehydrogenation conditions, a commercial unsupported catalyst, S-105, which contains the more easily reducible KF[sub 11]O[sub 13], is reduced to Fe[sub 3]O[sub 4]. Compared with this unsupported S-105 catalyst, the supported catalysts show significantly higher 1,3-butadiene selectivities at comparable conversion levels, which is to be attributed to the different natures of their respective active phases.

Stobbe, D.E.; Buren, F.R. van (Dow Benelux, Terneuzen (Netherlands)); Dillen, A.J. van.; Geus, J.W. (State Univ. of Utrecht (Netherlands))

1992-06-01

48

Alkylation to form trimethylpentanes from isobutane and 1-butene catalyzed by solid superacids of sulfated metal oxides  

Microsoft Academic Search

The gas-phase alkylation of 1-butene with isobutane was carried out over 0.2g of superacids of sulfated metal oxides, SO4\\/Fe2O3, SO4\\/Al2O3, SO4\\/TiO2, SO4\\/SnO2, and SO4\\/ZrO2, at 0°C with a 10:1 ratio of isobutane to 1-butene in a closed recirculation reactor. The products were pentanes (C5), hexanes (C6), heptanes (C7), and octanes (C8). The highest acid strength of the catalysts was linearly

Kunihiko Satoh; Hiromi Matsuhashi; Kazushi Arata

1999-01-01

49

Electron momentum spectroscopy of 1-butene: a theoretical analysis using molecular dynamics and molecular quantum similarity.  

PubMed

The results of experimental studies of the valence electronic structure of 1-butene by means of electron momentum spectroscopy (EMS) have been reinterpreted on the basis of molecular dynamical simulations in conjunction with the classical MM3 force field. The computed atomic trajectories demonstrate the importance of thermally induced nuclear dynamics in the electronic neutral ground state, in the form of significant deviations from stationary points on the potential energy surface and considerable variations of the C-C-C-C dihedral angle. These motions are found to have a considerable influence on the computed spectral bands and outer-valence electron momentum distributions. Euclidean distances between spherically averaged electron momentum densities confirm that thermally induced nuclear motions need to be fully taken into account for a consistent interpretation of the results of EMS experiments on conformationally flexible molecules. PMID:23902590

Shojaei, S H Reza; Vandenbussche, Jelle; Deleuze, Michael S; Bultinck, Patrick

2013-09-01

50

Gas-phase oxidation of 1-butene using nanoscale TiO{sub 2} photocatalysts  

SciTech Connect

The effects of preparation methods, humidity, and calcination temperatures on the behavior on nanoscale TiO{sub 2} photocatalysts were investigated in this study. Application of these photocatalysts were investigated in this study. Application of these photocatalysts in the gas-phase decomposition of 1-butene demonstrated that the nanoscale catalysts, prepared y the acid-assisted sol-gel technique, showed higher photocatalytic reactivity than commercially available Degussa P-25 TiO{sub 2}, while lower photoactivity was obtained on TiO{sub 2} catalysts prepared without photoactivity was obtained available Degussa P-25 TiO{sub 2}, while lower photoactivity was obtained on TiO{sub 2} catalysts prepared without adding acid to titanium isopropoxide. Experimental results revealed that the oxidation rates of 1-butene decreased exponentially with increasing water concentrations in the flowing stream. However, a trace amount of water vapor was indispensable in maintaining the stability of the catalysts. Proper calcination temperature (300 C) could promote the resistance of catalysts against the poisoning effects of humidity. Higher calcination temperature (400 C) unfavorably lowered the photoactivity due to phase transformation occurring at such a temperature. Amorphous and futile-typed TiO{sub 2} showed less photocatalytic reactivity. XRD patterns and BET measurements indicated that moderate surface areas (from 100 to 160 m{sup 2}/g), appropriate crystallite sizes (5{approximately}6 nm), and crystallinity to anatase were beneficial to the photocavity of TiO{sub 2} catalysts. In situ FTIR studies indicated that catalyst surfaces contained large amounts of chemisorbed water and hydroxyl groups, which are considered to be active sites in photocatalytic reactions. The accumulation of carbonate species on active sites resulted in the deactivation of TiO{sub 2} catalysts under dry conditions. quantum size effects were thought to be responsible for the high photoactivity achieved on the nanoscale TiO{sub 2} catalysts prepared by sol-gel methods.

Cao, L.; Huang, A.; Spiess, F.J.; Suib, S.L.

1999-11-15

51

Palladium salts of heteropolyacids as catalysts in the Wacker oxidation of 1-butene  

SciTech Connect

Palladium salts of heteropolyacids (PdHPAs) of the Keggin series H{sub 3+n}PV{sub n}Mo{sub 12-n}O{sub 40} supported on silica, have been used successfully as catalysts in the gas-phase Wacker oxidation of 1-butene. In such catalysts the palladium reaction centre and the redox component are combined in one complex. At 343 K and atmospheric pressure a high initial butanone yield of more than 0.2 g g{sup -1}{sub cat}h{sup -1}, in combination with a very high butanone selectivity of more than 98%, can be obtained. In the steady state, the activity of the catalyst is more than a factor of 10 lower than the initial activity, due to slow reoxidation of reduced palladium-heteropolyanion complexes. The rate of reoxidation depends on the composition of the HPA, the palladium loading, and the reaction conditions. The reaction order of 0.5 in the O{sub 2} partial pressure indicates the dissociation of dioxygen to be rate determining. The degree of hydration of the HPA appears to be important for the activity and stability of the catalysts. Spent catalysts can be regenerated by an oxidation treatment in air at temperatures around 525 K. Regeneration becomes more difficult with high palladium loading of the catalyst. 8 refs., 8 figs.

Stobbe-Kreemers, A.W.; van der Lans, G.; Makkee, M. [Delft Univ. of Technology (Netherlands)] [and others] [Delft Univ. of Technology (Netherlands); and others

1995-07-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

53

Epoxidation of 1-butene-3-ol over titanium silicalite TS-2 catalyst under autogenic pressure.  

PubMed

Epoxidation of 1-butene-3-ol (1B3O) with 30 wt% hydrogen peroxide over TS-2 catalyst has been studied with methanol as a solvent and at elevated pressure (autogenic). The influence of temperature in the range of 20-120 degrees C, the molar ratio of 1B3O/H(2)O(2) 1:1-5:1, methanol concentration 5-90 wt%, TS-2 catalyst concentration 0.1-5.0 wt% and the reaction time 0.5-5.0 h have been investigated. The process was described by the following functions: the selectivity of transformation to 1,2-epoxybutane-3-ol (1,2EB3) in relation to 1B3O consumed, the selectivity of transformation to organic compounds in relation to H(2)O(2) consumed and the conversions of 1B3O and hydrogen peroxide. The major product of epoxidation is 1,2EB3, a compound with many applications. PMID:18768256

Wróblewska, Agnieszka; Wajzberg, Joanna; Fajdek, Anna; Milchert, Eugeniusz

2009-04-30

54

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

NASA Astrophysics Data System (ADS)

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

Arora, Deepak; Winter, Horst

2010-03-01

55

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

PubMed

The deformation of isotactic poly-1-butene (iPB-1) matrix, during the CO(2) -assisted foaming process, makes the iPB-1 melt crystallize into form I rather than form I', which crystallizes after annealing under high-pressure CO(2) without foaming. The result provides a new strategy to directly obtain porous iPB-1 with stable form I from iPB-1 melt. PMID:21928303

Li, Lei; Liu, Tao; Zhao, Ling

2011-11-15

56

Activity enhancement of mesoporous silica (FSM-16) by modification with iron (II) sulphate for the isomerization of 1-butene  

Microsoft Academic Search

The catalytic activity of mesoporous silica (FSM-16) for the isomerization of 1-butene was remarkably enhanced by modification with iron (II) sulphate. The enhancement of the activity of FSM-16 was attributed to the transformation of the silanol groups on FSM-16 into Brønsted acid sites by the inductive effect of FeSO4 and\\/or sulphate species formed by the decomposition of FeSO4.

J. K. A Dapaah; Y Uemichi; A Ayame; H Matsuhashi; M Sugioka

1999-01-01

57

Correlation between the magnetism of non-stoichiometric zinc ferrites and their catalytic activity for oxidative dehydrogenation of 1-butene  

Microsoft Academic Search

Non-stoichiometric zinc ferrites, which were used as catalysts for the oxidative dehydrogentation of 1-butene, were synthesized by using co-precipitation and hydrothermal methods. Their atom local order was analyzed with Mössbauer spectroscopy and the refinement of the crystalline structures; their macroscopic magnetization was measured by the vibrating sample method. Their magnetic and catalytic properties depended on the synthesis conditions; the analysis

J. A Toledo-Antonio; N Nava; M Mart??nez; X Bokhimi

2002-01-01

58

Phase transition II ? I in isotactic poly-1-butene: wide- and small-angle X-ray scattering measurements  

Microsoft Academic Search

Phase transition II ? I in isotactic poly-1-butene was studied by wide- and small-angle X-ray scattering in order to follow the change of crystallinity and of the characteristic parameters of the lamellar stacks over time. Small-angle X-ray scattering experimental patterns were analyzed by a fitting method with the profiles calculated from some theoretical distribution models of the lamellar thickness. The

Antonio Marigo; Carla Marega; Giuliano Cecchin; Gianni Collina; Giuseppe Ferrara

2000-01-01

59

Active copper species in 1-butene skeletal isomerization: comparison between copper-modified MCM-41 and beta catalysts  

Microsoft Academic Search

The role of copper was studied in the skeletal isomerization of 1-butene over copper-modified mesoporous MCM-41 molecular sieve and Beta zeolite. The Cu–H-MCM-41 and Cu–H-Beta catalysts were synthesized in our laboratory and characterized by XRD, nitrogen adsorption, X-ray fluorescence, FTIR of adsorbed pyridine and direct current plasma atomic emission spectrometry. The oxidation state of copper after oxidation and reduction in

V. Nieminen; N. Kumar; J. Datka; J. Päivärinta; M. Hotokka; E. Laine; T. Salmi; D. Yu. Murzin

2003-01-01

60

New bis(aryloxy)-Ti(IV) complexes and their use for the selective dimerization of ethylene to 1-butene.  

PubMed

New titanium complexes of general formula [(ArO)(n)Ti(Oi-Pr)((4-n))] were synthesized and used as pre-catalysts for the selective dimerization of ethylene to 1-butene. The complexes were prepared in cyclohexane using [Ti(Oi-Pr)(4)] and one or two equivalents of the corresponding phenols (ArOH) at room temperature. In this work, both monodentate and chelating phenols were evaluated. For alkyl-substituted phenols, it was demonstrated that large steric hindrance at both ortho and ortho' positions selectively yielded the mono-substituted complexes [(ArO)Ti(Oi-Pr)(3)]. Substitution at only one of the ortho positions allowed both the mono- and the di-substituted Ti complexes to be isolated. When a heteroatom was introduced on the phenol backbone, di-substitution systematically occurred except with phenols presenting a hemilabile -CH(2)NR(2) group at the ortho position. Upon activation with 3 equiv. of AlEt(3) at 20 bar and 60 °C, all the complexes selectively dimerized ethylene to 1-butene (>86% of butenes among which 99% of 1-butene). An increase of the steric bulk at the ortho position of the ligand or the introduction of a functional group led to decreased activity compared to [Ti(Oi-Pr)(4)]. PMID:22814869

Grasset, Fabien; Cazaux, Jean-Benoît; Magna, Lionel; Braunstein, Pierre; Oliver-Bourbigou, Hélène

2012-09-14

61

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

SciTech Connect

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

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

1982-04-01

62

Comparative catalytic studies on the conversion of 1-butene and n-butane to isobutene over MCM-22 and ITQ-2 zeolites  

Microsoft Academic Search

The catalytic properties of H-MCM-22 and Pt-MCM-22 for the skeletal isomerization of 1-butene and the dehydroisomerization of n-butane were compared with those obtained from their delaminated derivatives, H-ITQ-2 and Pt-ITQ-2. The overall results of our study strongly suggests that the desired 1-butene and n-butane conversions to isobutene in steady state occur mainly near the pore mouth inlets of the sinusoidal

Hye Ja Jung; Sang Soon Park; Chae-Ho Shin; Yong-Ki Park; Suk Bong Hong

2007-01-01

63

Temperature-dependent absorption cross-section measurements of 1-butene (1-C4H8) in VUV and IR  

NASA Astrophysics Data System (ADS)

Vacuum ultraviolet (VUV) and infrared (IR) absorption cross-section measurements of 1-butene (1-C4H8; CH2=CHCH2CH3; Butylene) are reported over the temperature range of 296-529 K. The VUV measurements are performed between 115 and 205 nm using synchrotron radiation as a tunable VUV light source. Fourier Transform Infrared (FTIR) spectroscopy is employed to measure absorption cross-section and band strengths in the IR region between 1.54 and 25 ?m (˜6500-400 cm-1). The measured room-temperature VUV and IR absorption cross-sections are compared with available literature data and are found to be in good agreement. The oscillator strength for the electronic transition (A1A??X1A?) around 150-205 nm is determined to be 0.32±0.01.The gas temperature has a strong effect on both VUV and IR spectra. Measurements made in the VUV region show that the peak value of the band cross-section decreases and the background continuum increases with increasing gas temperature. This behavior is due to a change in the rotational and vibrational population distribution of 1-butene molecule. Similar changes in rotational population are observed in the IR spectra. Moreover, variation of the IR spectra with temperature is used to measure the enthalpy difference between syn and skew conformations of 1-butene and is found to be 0.24±0.03 kcal/mol, which is in excellent agreement with values reported in the literature. The measurements reported in this work will provide the much-needed spectroscopic information for the development of high-temperature quantitative diagnostics in combustion applications and validation of atmospheric chemistry models of extra-solar planets.

Es-sebbar, Et-touhami; Benilan, Yves; Farooq, Aamir

2013-01-01

64

Crystallization of a (1-butene)-ethylene copolymer in phase I directly from the melt in nanocomposites with montmorillonite.  

PubMed

Nanocomposites based on a copolymer of 1-butene and ethylene filled with montmorillonite (Cloisite 15A) were studied, obtaining for the first time crystallization from the melt directly into phase I. The polymorphism of the polymer and the dispersion of the filler in the matrix were investigated. The effect of the compatibilizer (PB-g-MA) on these properties was also singled out. The dramatic increase in the rate of the II --> I phase transition due to montmorillonite was attributed to the alteration in the phase stability diagram of the matrix, due to the introduction of defects and to induction of local pressure on the crystalline domains. PMID:20358902

Marega, Carla; Causin, Valerio; Marigo, Antonio; Saini, Roberta; Ferrara, Giuseppe

2010-05-01

65

High-pressure vapor-liquid equilibria for ethylene + 4-methyl-1-pentane and 1-butene + 1-hexene  

SciTech Connect

Isothermal vapor-liquid equilibria (VLE) for the ethylene + 4-methyl-1-pentene and 1-butene + 1-hexene binary systems were measured by the static method at several temperatures for pressures in the range (0.3 to 8.5) MPa. Representations of VLE data by the Soave and Peng-Robinson cubic equations of state are compared in both modes: predictive and binary parameter adjustment. As the two binary systems behave almost ideally, there is no significant difference between their representation qualities through both equations of state.

Laugier, S. [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France)] [Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Talence (France); Richon, D. [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)] [Ecole Nationale Superieure des Mines de Paris, Fontainebleau (France)

1996-03-01

66

Gas-phase ion-molecule chemistry of fullerene cations and dications with propene, 1-butene and isobutene  

SciTech Connect

The gas-phase ion-molecule reactions of C[sub n][sup +] and C[sub n][sup 2+] (N = 54, 56, 60, and 70) with isobutene were investigated by utilizing a triple quadrupole mass spectrometer. In addition, the ion chemistry of C[sub 60][sup +] and C[sub 60][sup 2+] with propene and 1-butene was investigated. The various ion-molecule reactions observed were highly dependent on the gas cell pressure and the collision energy of the primary ions. The product ions observed were governed primarily by associative and partial charge transfer reactions. The isomeric form of C[sub 4]H[sub 8] as well as the size of the fullerene ion affected the reactions observed. For example, 1-butene readily adds to C[sub 60][sup 2+], while isobutene adducts were not detected. Also, fullerene cations with adjacent five-membered rings (n = 54, 56 and 58) react with isobutene to produce C[sub n](C[sub 4]H[sub 8])[sup +] while C[sub 60][sup 2+] and C[sub 70][sup 2+] do not. 48 refs., 4 figs., 2 tabs.

Stry, J.J.; Garvey, J.F. (State Univ. of New York, Buffalo, NY (United States))

1994-08-25

67

Photoassisted adsorption of allylamine and 1-butene on H:Si(111) studied by surface vibrational spectroscopies.  

PubMed

Ultraviolet photoassisted adsorption of terminally double-bonded molecules, allylamine (CH2=CH-CH2-NH2) and 1-butene (CH2=CH-CH2-CH3), on hydrogen-terminated silicon (111) surface was attempted to obtain adsorbates covalently terminating the surface Si atoms. The adsorption process was monitored by high-resolution electron energy loss spectroscopy, multiple internal infrared reflection-absorption spectroscopy, and Auger electron spectroscopy. Allylamine adsorbates emerged upon delivery of allylamine gas under ultraviolet irradiation. The N-H bonds in allylamine were evidenced to survive over the photoadsorption process by vibrational analysis and by the reaction with ketene. CH3- groups were detected at low coverage, indicating anchoring of the organic moieties by the secondary (sec-) type carbon atoms, which were taken over by the primary (n-) type with increasing coverage. C-D bonds were detected after deposition on deuterium-terminated Si(111) upon incorporation of Si-terminating H into the hydrocarbon part of adsorbates. In the case of 1-butene, not only the C=C end but also the CH3- end of a molecule might attach on Si, resulting in emergence of adsorbates composed of CH2 groups. The newly obtained adsorbates are prospective as a material applied for nanolithography, fine electrochemistry, and nano-biotechnology. PMID:16570980

Yamada, Taro; Noto, Madomi; Shirasaka, Kaoru; Kato, Hiroyuki S; Kawai, Maki

2006-04-01

68

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

NASA Astrophysics Data System (ADS)

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.

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

69

Selective dimerization of styrene to 1,3-diphenyl-1-butene with bis(?-diketonato)palladium\\/boron trifluoride etherate catalyst system  

Microsoft Academic Search

The selective dimerization of styrene to 1,3-diphenyl-1-butene over Pd(?-diketonate)2\\/BF3OEt2 catalyst systems in both “phosphine-free” and “phosphine-modified” fashions has been investigated. For the Pd(acac)2+2PR3+7BF3OEt2 catalyst system the turnover of 75,000mol styrene\\/mol palladium for 7h was reached at 70°C with selectivity to dimers of 93%. Styrene dimers up to 95% consists of trans-1,3-diphenyl-1-butene. Catalytic activity and selectivity can be controlled by varying

Gomboo Myagmarsuren; Vitalii S. Tkach; Fedor K. Shmidt; Mesyef Mohamad; Dmitrii S. Suslov

2005-01-01

70

Investigation of the relationship between the bulk and surface composition of tin and antimony mixed oxide catalysts and the oxidative dehydrogenation of 1-butene to butadiene  

Microsoft Academic Search

The oxidative dehydrogenation of 1-butene to butadiene from a feed of 50Vertical Bar3< air, 45Vertical Bar3< nitrogen, 5Vertical Bar3< 1-butene at 150°⁻⁴°°sup 0\\/C was tested on tin-antimony mixed oxides containing 0-100Vertical Bar3< antimony calcined at 400°⁻¹°°°sup 0\\/C for 16 hr or at 1000°C to constant weight (2-3 weeks, evaporation of excess SbâOâ). A correlation of butadiene selectivity with catalyst structure

H. J. Herniman; D. R. Pyke; R. Reid

1979-01-01

71

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

NASA Astrophysics Data System (ADS)

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

McCready, Erica; Burghardt, Wesley

2013-03-01

72

Selective dimerisation of 1-butene in biphasic mode using buffered chloroaluminate ionic liquid solvents — design and application of a continuous loop reactor  

Microsoft Academic Search

The dimerisation of 1-butene using (cod)Ni(hfacac) 1 as catalyst has been investigated in different chloroaluminate ionic liquids. Systems prepared by buffering an acidic ionic liquid with weak organic bases proved to be very suitable solvents for the reaction. The reaction takes place in biphasic reaction mode with facile catalyst separation and catalyst recycling. The high intrinsic dimer linearity of catalyst

P Wasserscheid; M Eichmann

2001-01-01

73

An Investigation of Gas Phase Ozonolysis Reactions.  

National Technical Information Service (NTIS)

A simple gas phase stopped-flow apparatus has been used to determine the rates and stoichiometry for the reactions of ozone with ethylene, propene, 1-butene, methylpropene, cis-2-butene, and trans-2-butene. Measurements of the intensity of light scattered...

D. G. Williamson

1976-01-01

74

NTP Toxicology and Carcinogenesis Studies of Dimethylvinyl Chloride (1-Chloro-2-Methylpropene) (CAS No. 513-37-1) in F344/N Rats and B6C3F1 Mice (Gavage Studies).  

PubMed

Dimethylvinyl chloride is a clear colorless liquid, which, because of its volatility and flammability at room temperature, is a significant fire hazard. It has a boiling point of 68.1 degrees C (155 degrees F) and a density at 20 degrees C of 0.919 g/ml. Dimethylvinyl chloride is a byproduct in the production of 3-chloro-2-methylpropene by the chlorination of isobutene. It is not known to be produced in the United States for other than laboratory purposes. This chemical was nominated for toxicologic studies because of its reported presence in ambient air in the Baltimore area and was selected for toxicologic characterization because of its structural similarity to the known animal and human carcinogen, vinyl chloride monomer. Toxicology and carcinogenesis studies of dimethylvinyl chloride (96%-98% pure), a structural analog of vinyl chloride monomer, a known human carcinogen, by administered dimethylvinyl chloride in corn oil by gavage to groups of 50 male and 50 female F344/N rats and B6C3F1 mice at doses of 0, 100, or 200 mg/kg body weight 5 days per week for 102 or 103 weeks. The selection of these doses was based on results of 13-week studies, which included depression of body weight at doses of 500 mg/kg or above in rats as well as histopathologic changes intestinal epithelium, bone marrow, hepatocytes, and the testes at doses of 250 mg/kg and above; doses in mice were selected on the basis of histopathologic changes in lymphopoietic cells, liver, pancreatic islets, ovary, testis, and spleen, with changes being most prominent at doses of 500 mg/kg and above. In the 2-year studies, body weights of rats and mice given 100 mg/kg were comparable to those of the vehicle controls except for the last few weeks in mice when body weights were markedly lower than those for the vehicle controls. At 200 mg/kg, the mean body weights of rats and mice were progressively decreased relative to those of vehicle controls, with the significant departure from vehicle controls occurring somewhat earlier in males than in females. Survival of vehicle control rats and mice was comparable to historical values; however, survival of dosed male and female rats was significantly lower than that of vehicle controls, with the incidence of mortality being more severe at the high dose than at the low dose. There were no survivors in the high dose group of male rats after week 85 or in the high dose group of female rats after week 97. Survival was significantly lower among dosed male and female mice compared with vehicle controls. In the absence of toxicological findings that would explain the early deaths, it is assumed that the high incidence of tumors and chemical-related toxicity contributed to the decreased survival of dosed rats and mice. In rats, the severity and incidence of nonneoplastic lesions were minimal; these lesions included necrosis of the duodenum and epithelial hyperplasia at the sites of tumor formation--the nasal cavity, esophagus, and forestomach. In mice, the severity of nonneoplastic lesions was also minimal; the lesions included necrosis of the liver, bone marrow granulocytic hyperplasia, and inflammation of the nasal cavity (small number, females only.) Several types of neoplastic lesions occurred with significantly increased incidences in dosed animals as shown in the following table (see page 11 of Technical Report). Among rats, these lesions included malignant epithelial tumors of the nasal cavity and squamous cell tumors of the oral cavity, esophagus, and forestomach in males and females. The increased number of fibroadenomas of the mammary gland in female rats may have been related to dimethylvinyl chloride administration. The lack of a clear dose-response relationship for certain tumors in rats is considered to be related to the increased number of early deaths observed in the high dose groups. Among dosed mice, there were significantly increased incidences of squamous cell carcinomas of the forestomach (both sexes), squamous cell papillomas of the forestomach (males), and squamous cell carcinomas of the preputial gla

1986-08-01

75

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

SciTech Connect

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

Hamilton, D.C.

1986-10-08

76

A density-functional theory study on double-bond isomerization of 1-butene to cis-2-butene catalyzed by zeolites  

NASA Astrophysics Data System (ADS)

Using density-functional theory, the double-bond isomerization of 1-butene to cis-2-butene over zeolites is investigated with a 3T cluster model simulating zeolite. At the B3LYP/6-31G(d, p) level, the complete geometry optimization and the activation energy calculation are performed. It is found that the OH group of acidic site of zeolite protonates the side C atom of double-bond of 1-butene and simultaneously, the neighboring O atom of the cluster abstracts a hydrogen atom from the butene, restoring the zeolite active site and yielding adsorbed cis-2-butene. The reaction shows a concerted mechanism. The calculated activation barrier is close to the experimental data.

Li, Hui-Ying; Pu, Min; Liu, Kun-Hui; Zhang, Bao-Fang; Chen, Biao-Hua

2005-03-01

77

Temperature dependence of the gas-phase reactions of Cl atoms with propene and 1-butene between 285 < T < 313 K  

NASA Astrophysics Data System (ADS)

Relative rate coefficients for the reactions of chlorine atoms with propene and 1-butene have been measured as a function of temperature (285-313 K) at 1 bar total pressure of air using FTIR as detection technique. Such studies are necessary to model the atmospheric chemistry of these alkenes and their impact on the air quality in areas where Cl chemistry is potentially important such as maritime and heavily polluted environments. The temperature dependence can be adequately described by the simple Arrhenius relationship and the following expressions in units of cm 3 molecule -1 s -1 have been obtained: kpropene = (1.43 ± 0.35) × 10 -14 exp[(2886 ± 73)/ T] and k1-butene = (1.60 ± 0.81) × 10 -13 exp[(2235 ± 152)/ T] (errors are 2 ?).

Ceacero-Vega, Antonio A.; Ballesteros, Bernabé; Albaladejo, José; Bejan, Iustinian; Barnes, Ian

2009-12-01

78

A comparison of the conversion of 1-amino-2-ethylcyclopropane-1-carboxylic acid stereoisomers to 1-butene by pea epicotyls and by a cell-free system  

Microsoft Academic Search

The characteristics of the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene by pea (Pisum sativum L.) epicotyls and by pea epicotyl enzyme are compared. Of the four stereoisomers of 1-amino-2-ethylcyclopropane-1-carboxylic acid (AEC), only (1R,2S)-AEC is preferentially converted to 1-butene in pea epicotyls. This conversion is inhibited by ACC, indicating that butene production from (1R,2S)-AEC and ethylene production from ACC are

Thomas A. McKeon; Shang Fa Yang

1984-01-01

79

Effect of molecular and processing parameters on the flow-induced crystallization of poly-1-butene. Part 1: Kinetics and morphology  

Microsoft Academic Search

In this work the effect of molecular parameters (molecular weight (MW), molecular weight distribution (MWD)) and processing conditions (crystallization temperature, flow conditions) on the isothermal crystallization behavior of three isotactic poly-1-butene (iPB) samples is investigated by means of rheo-optical techniques. The emphasis in this paper will be on the kinetics and the resulting morphology.Turbidity measurements show a strong effect of

Jimmy Baert; Peter Van Puyvelde

2006-01-01

80

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

NASA Astrophysics Data System (ADS)

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

Chin, Chih-Hao; Lee, Shih-Huang

2012-01-01

81

Kinetics of C 2H radical reactions with ethene, propene and 1-butene measured in a pulsed Laval nozzle apparatus at T=103 and 296 K  

Microsoft Academic Search

Low-temperature kinetics of the reactions of C2H radical with ethene (k1), propene (k2), and 1-butene (k3) are studied using a pulsed Laval nozzle supersonic expansion. The C2H decay profiles in the presence of both the alkene reactant and O2 are monitored by the CH(A2?) chemiluminescence tracer method. The rate constants k1, k2, and k3 are measured at T=103K to be

Andrei B. Vakhtin; Dwayne E. Heard; Ian W. M. Smith; Stephen R. Leone

2001-01-01

82

Grafting of diethyl maleate and maleic anhydride onto styrene- b-(ethylene- co-1-butene)- b-styrene triblock copolymer (SEBS)  

Microsoft Academic Search

In this paper a study of the bulk functionalization of styrene-b-(ethylene-co-1-butene)-b-styrene triblock copolymer (SEBS) with diethyl maleate (DEM) or maleic anhydride (MAH) and dicumyl peroxide (DCP) as initiator in a Brabender mixer is described. The determination of the functionalization degree (FD) by NMR analysis indicates that the FD values depend on the feed composition and in particular on the DEM\\/DCP

E. Passaglia; S. Ghetti; F. Picchioni; G. Ruggeri

2000-01-01

83

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

PubMed

We investigated two-body (binary) and three-body (triple) dissociations of ethanedial, propanal, propenal, n-butane, 1-butene, and 1,3-butadiene on the ground potential-energy surfaces using quantum-chemical and Rice-Ramsperger-Kassel-Marcus calculations; most attention is paid on the triple dissociation mechanisms. The triple dissociation includes elimination of a hydrogen molecule from a combination of two separate terminal hydrogen atoms; meanwhile, the rest part simultaneously decomposes to two stable fragments, e.g., C(2)H(4), C(2)H(2), or CO. Transition structures corresponding to the concerted triple dissociation were identified using the B3LYP/6-311G(d,p) level of theory and total energies were computed using the method CCSD(T)/6-311+G(3df, 2p). The forward barrier height of triple dissociation has a trend of ethanedial < propanal < propenal < n-butane < 1-butene < 1,3-butadiene, pertaining to the reaction enthalpy. Ratios of translational energies of three separate fragments could be estimated from the transition structure of triple dissociation. The synchronous concerted dissociation of propanal, propenal, and 1-butene leading to three different types of molecular fragments by breaking nonequivalent chemical bonds is rare. The triple dissociation of propanal, n-butane, 1-butene, and 1,3-butadiene were investigated for the first time. To outline a whole picture of dissociation mechanisms, some significant two-body dissociation channels were investigated for the calculations of product branching ratios. The triple dissociation plays an important role in the three carbonyl compounds, but plays a minor or negligible role in the three hydrocarbons. PMID:22260580

Chin, Chih-Hao; Lee, Shih-Huang

2012-01-14

84

Iron-based dehydrogenation catalysts supported on zirconia. II. The behavior in the dehydrogenation of 1-butene  

SciTech Connect

The behavior of iron oxide-based catalysts supported on zirconia in the dehydrogenation of 1-butene was investigated. Iron oxide-on-zirconia catalysts deactivate during operation due to carbon deposition. It was shown with XRD that solid state reactions between the active phase and the support do not take place in zirconia-supported catalysts: the iron-containing phase after reaction is Fe{sub 3}O{sub 4}. The total amount of carbon deposited onto zirconia-supported catalysts containing only iron oxide as determined with temperature-programmed oxidation is about 2 wt% C after 20 h. It was also shown that a carbon species deposited in narrow pores was present in iron oxide-on-zirconia catalysts. The KFe/ZrO{sub 2} catalysts proved to be more stable than KFe/MgO catalysts: for catalysts containing highly dispersed iron oxide only a slight deactivation was observed after about 100 h on stream. This deactivation is attributed to migration of potassium from the catalyst to the quartz reactor. Catalysts of low loadings (1 wt% Fe, 1 wt% K) or with less well-dispersed iron oxide deactivate in a shorter period of time: an incomplete coverage of the zirconia support leads to deactivation by carbon deposition. The selectivity to butadiene of the KFe/ZrO{sub 2} catalysts is about 60%, which is related to a high production of CO{sub 2}. This is attributed to carbon deposition taking place in the small pores of the zirconia-supported catalysts. The coke is subsequently gasified, probably by the supported potassium carbonate. Eliminating the small pores substantially improved the butadiene selectivity. 14 refs., 13 figs., 1 tab.

Boot, L.A.; Dillen, A.J. van; Geus, J.W. [Utrecht Univ. (Netherlands)] [and others] [Utrecht Univ. (Netherlands); and others

1996-09-15

85

Oxidation of 1-butene on the surface of YBa{sub 2}Cu{sub 3}O{sub 7-x}  

SciTech Connect

Oxidation of 1-C{sub 4}H{sub 8} on YBa{sub 2}Cu{sub 3}O{sub 7-x} catalysts prepared by self-propagating high-temperature synthesis (SHS) (C{sub 1}) and by conventional furnace technology (C{sub 2}) was studied. The ESR experiments show that both C{sub 1} and C{sub 2} samples lose their superconducting properties as the reaction of 1-butene oxidation proceeds. However, sample C{sub 1} retains its catalytic activity in the conversion of butene to butadiene and promotes the deep oxidation reaction, whereas sample C{sub 2} is ineffective in these processes.

Muradyan, A.A.; Manukyan, N.S.; Gazaryan, K.G.; Saakyan, E.F.; Garibyan, T.A. [Institute of Chemical Physics, Erevan (Armenia)

1994-11-01

86

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

SciTech Connect

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

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

1987-03-26

87

Temperature (290-400 K) and pressure (5-900 Torr) dependence of the kinetics of the reactions of chlorine atoms with propene and 1-butene  

NASA Astrophysics Data System (ADS)

Rate constants for reactions of chlorine atoms with propene ( k1) and 1-butene ( k2) were measured relative to that of chlorine atoms with n-butane ( k3) at 295-400 K in 5-900 Torr of N 2 using gas chromatographic analysis. Experiments were also performed using an FTIR smog chamber to measure k1 relative to cyclohexane ( k4) at 290-302 K in 700 Torr of N 2. In contrast to previous studies which reported large negative activation energies, no discernable influence of temperature on the kinetics of these reactions was observed for experiments conducted near ambient temperature and pressure (? Ea(1)? ? 300 cal mole -1, ? Ea(2)? ? 150 cal mole -1).

Kaiser, E. W.; Wallington, T. J.

2011-01-01

88

Copolymerization of ethylene with sterically hindered 3,3-dimethyl-1-butene using a chain-walking pd-diimine catalyst.  

PubMed

In this Communication, the copolymerization of ethylene with a sterically hindered ?-olefin comonomer, ?-trisubstituted 3,3-dimethyl-1-butene (DMB), using a chain-walking Pd-diimine catalyst, [(ArN?C(Me)?(Me)C?NAr)Pd(CH(3) )(N?CMe)]SbF(6) (Ar?2,6-(iPr)(2) C(6) H(3) ) (1) is reported. In spite of its high steric bulkiness in the close proximity of the double bond, appreciable DMB incorporations (up to 3?mol-%) are successfully achieved in the copolymers. The chain microstructure of the copolymers is elucidated, and the effect of DMB incorporation on polymer topology and thermal properties are examined. This work thus demonstrates the high capability of the Pd-diimine catalyst in incorporating sterically encumbered ?-olefins. PMID:21590859

Xiang, Peng; Ye, Zhibin

2010-06-16

89

Polymorphic transformation of isotactic poly(1-butene) in form III upon heating: in situ synchrotron small- and wide-angle X-ray scattering studies.  

PubMed

The phase transformation of form III isotactic poly(1-butene) was investigated as a function of temperature. The polymer was isothermally precipitated from a dilute solution in iso-amyl acetate and observed with real-time synchrotron small- and wide-angle X-ray scattering techniques. The results confirmed that the polymorphic transition of form III was strongly dependent on temperature. The phase transformation from form III to form I' proceeded at a temperature of ca. 80 degrees C. This was accompanied by the presence of two distinctly different lamellar periodicities arising from form III and I' crystals, respectively. The coexistence of form III and I' crystals can persist up to 103 degrees C, followed by melting and recrystallizing into form II crystals. Finally, the reflections resulting from form II crystals disappeared at 118 degrees C. PMID:20402536

Jiang, Zhiyong; Sun, Yingying; Tang, Yujing; Lai, Yuqing; Funari, Sérgio S; Gehrke, Rainer; Men, Yongfeng

2010-05-13

90

Kinetics of C 2H radical reactions with ethene, propene and 1-butene measured in a pulsed Laval nozzle apparatus at T=103 and 296 K  

NASA Astrophysics Data System (ADS)

Low-temperature kinetics of the reactions of C 2H radical with ethene ( k1), propene ( k2), and 1-butene ( k3) are studied using a pulsed Laval nozzle supersonic expansion. The C 2H decay profiles in the presence of both the alkene reactant and O 2 are monitored by the CH(A 2?) chemiluminescence tracer method. The rate constants k1, k2, and k3 are measured at T=103 K to be (1.4±0.4)×10 -10, (2.4±0.6)×10 -10, and (2.6±0.6)×10 -10 cm3 molecule-1 s-1, respectively. Measurements at room temperature (296 K) and previous data suggest a slight negative temperature dependence for all three reactions.

Vakhtin, Andrei B.; Heard, Dwayne E.; Smith, Ian W. M.; Leone, Stephen R.

2001-11-01

91

Enhancement of catalytic activity of calcium X-type zeolite by preadsorption of nitrogen dioxide  

SciTech Connect

Calcium X zeolite was nearly inactive for cis-2-butene isomerization at 100/sup 0/C and 83 mm Hg butene. The initial rates of 1-butene and trans-2-butene formation increased linearly with the amount of preadsorbed nitrogen dioxide. The rates of cis-2-butene and trans-2-butene formation from 1-butene were also proportional to the amount of adsorbed NO/sub 2/. The initial rates of the isomerization reactions decreased with increasing evacuation temperatures (150/sup 0/-800/sup 0/C) of the catalyst. The activity decreased linearly with the amount of added ammonia. A kinetic equation was derived from the pressure and temperature dependence of the isomerization reactions. The isomerization results and IR spectra of the adsorbed NO/sub 2/ suggested that the enhancement of activity is due to the formation of new acidic hydroxyl groups.

Wada, Y.; Otsuka, K.; Morikawa, A.

1980-08-01

92

Isomerization of linear alkenes on Amberlyst 15  

Microsoft Academic Search

The kinetics of the isomerization of 1-butene to cis-2-butene and trans-2-butene, of 1-pentene to cis-2-pentene and trans-2-pentene as well as of 1-hexene to cis-2-hexene and trans-2-hexene on sulfonated copolymer Amberlyst 15 in the gas phase was investigated. The Langmuir–Hinshelwood equations were adjusted to the results of the kinetic experiment using the values of adsorption equilibrium constants of the reactants from

Piotr M. S?omkiewicz

2006-01-01

93

Heterogeneous reactive extraction for secondary butyl alcohol liquid phase synthesis: Microkinetics and equilibria  

Microsoft Academic Search

The reaction kinetics for the liquid phase synthesis of a racemic mixture of the secondary butyl alcohols (SBA) from linear butene isomers (1-butene (1B); cis-2-butene (c2B); trans-2-butene (t2B)) and water (W) using a macroporous sulfonic acid ion exchange resin as catalyst were determined experimentally in a multiphase CSTR in the temperature range 39–433K at 6–8MPa. This range of pressures is

Bernhard Pfeuffer; Ulrich Kunz; Ulrich Hoffmann; Thomas Turek; Detlef Hoell

2011-01-01

94

High selectivity production of propylene from 2-butene: non-degenerate pathways to convert symmetric olefins via olefin metathesis.  

PubMed

The first example of propylene production from 2-butene in promising yield is described by reacting trans-2-butene over tungsten hydrides precursor W-H/Al(2)O(3) at 150 °C and different pressures in a continuous flow reactor. The tungsten carbene-hydride active site operates as a "bi-functional catalyst" through the disfavoured 2-butene isomerisation on W-hydride and 2-butenes/1-butene cross-metathesis on W-carbene. PMID:22395285

Mazoyer, Etienne; Szeto, Kai C; Basset, Jean-Marie; Nicholas, Christopher P; Taoufik, Mostafa

2012-04-14

95

Selective Oxidation of n-Butane and Butenes over Vanadium-Containing Catalysts  

Microsoft Academic Search

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 C4-olefins from n-butane and the selectivity to butadiene

J. M. López Nieto; P. Concepción; A. Dejoz; H. Knoezinger; F. Melo; M. I. Vázquez

2000-01-01

96

Evaluation of Kinetic and Mechanistic Data for Modeling of Photochemical Smog  

Microsoft Academic Search

This review is a critical evaluation of the rate constants, mechanisms, and products of selected atmospheric reactions of hydrocarbons, nitrogen oxides, and sulfur oxides in air. The evaluation considers eight hydrocarbons (n-butane, 2,3-dimethylbutane, ethene, propene, 1-butene, trans-2-butene, toluene, and m-xylene) for which smog chamber irradiations have been carried out under carefully controlled conditions and which have been the subject of

Roger Atkinson; Alan C. Lloyd

1984-01-01

97

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

NASA Astrophysics Data System (ADS)

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

Woon, David E.; Park, Jin-Young

2009-08-01

98

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

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.

Wang, Guangwei; Negishi, Ei-ichi

2013-01-01

99

Comparison of cytogenetic effects of 3,4-epoxy-1-butene and 1,2:3,4-diepoxybutane in mouse, rat and human lymphocytes following in vitro G 0 exposures  

Microsoft Academic Search

To understand better the species differences in carcinogenicity caused by 1,3-butadiene (BD), we exposed G0 lymphocytes (either splenic or peripheral blood) from rats, mice and humans to 3,4-epoxy-1-butene (EB) (20 to 931 ?M) or 1,2:3,4-diepoxybutane (DEB) (2.5 to 320 uM), two of the suspected active metabolites of BD. Short EB exposures induced little measurable cytogenetic damage in either rat, mouse,

Andrew D. Kligerman; David M. DeMarini; Carolyn L. Doerr; Nancy M. Hanley; Velva S. Milholland; Alan H. Tennant

1999-01-01

100

Kinetics and mechanism of the hydration of the equilibrium mixture of 3-methyl-1-buten-3-ol and 3-methyl-2-buten-1-ol with isoprene in aqueous solutions of sulfuric acid  

Microsoft Academic Search

The kinetic relationships of the hydration of an equilibrium mixture of 3-methyl-1-buten-3-ol (dimethylvinylcarbinol, DMVC) and 3-methyl-2-buten-1-ol (dimethylallyl alcohol, DMAA) with isoprene (C5H8) were investigated in aqueous solutions of sulfuric acid from 24.9 to 49.7% at 25°C. Data were obtained on the mechanism of hydration of the equilibrium mixture of DMVC and DMAA with isoprene.

R. S. Ryabova; G. F. Osipova; M. I. Vinnik

1992-01-01

101

Inhibitors of the fungal cell wall. Synthesis of 4-aryl-4- N-arylamine-1-butenes and related compounds with inhibitory activities on ?(1–3) glucan and chitin synthases  

Microsoft Academic Search

As part of our project devoted to the search for antifungal agents, which act via a selective mode of action, we synthesized a series of new 4-aryl- or 4-alkyl-N-arylamine-1-butenes and transformed some of them into 2-substituted 4-methyl-tetrahydroquinolines and quinolines by using a novel three-step synthesis. Results obtained in agar dilution assays have shown that 4-aryl homoallylamines not possessing halogen in

Juan M Urbina; Juan C. G Cortés; Alirio Palma; Silvia N López; Susana A Zacchino; Ricardo D Enriz; Juan C Ribas; Vladimir V Kouznetzov

2000-01-01

102

Reconstruction of Calorimetric Curves from X-ray Diffraction Data during the Melting-Recrystallization Process of Polymers: Simultaneous Calorimetry\\/X-ray Diffraction Measurements of Isotactic Poly(1-butene) in Form III  

Microsoft Academic Search

To understand complex phase behaviors of crystalline or semi-crystalline polymers, it is indispensable to clarify the correlation between the thermal and structural change events. Simultaneous calorimetry\\/X-ray diffraction measurement is one of the powerful methods to clarify such correlation. Isotactic poly(1-butene) (PB-1) exhibits complex phase transformation among the various crystal forms (Forms I, II, III, etc.). Here, we studied the transformation

Hiroshi Takahashi; Kenichiro Shimada; Yuzo Yamamoto; Hiroki Uehara

2012-01-01

103

Reconstruction of Calorimetric Curves from X-ray Diffraction Data during the Melting-Recrystallization Process of Polymers: Simultaneous Calorimetry\\/X-ray Diffraction Measurements of Isotactic Poly(1-butene) in Form III  

Microsoft Academic Search

To understand complex phase behaviors of crystalline or semi-crystalline polymers, it is indispensable to clarify the correlation between the thermal and structural change events. Simultaneous calorimetry\\/X-ray diffraction measurement is one of the powerful methods to clarify such correlation. Isotactic poly(1-butene) (PB-1) exhibits complex phase transformation among the various crystal forms (Forms I, II, III, etc.). Here, we studied the transformation

Hiroshi Takahashi; Kenichiro Shimada; Yuzo Yamamoto; Hiroki Uehara

2011-01-01

104

3-chloro-1-butene: gas-phase molecular structure and conformations as determined by electron diffraction and by molecular mechanics and ab initio calculations  

NASA Astrophysics Data System (ADS)

Gaseous 3-chloro-1-butene has been studied experimentally by electron diffraction (ED) at 20 and 180°C, and at these temperatures, 76(10)% and 62(10)%, respectively, of the most stable conformer i.e. the one having a hydrogen atom eclipsing the double bond, were found. The conformer with the chlorine atom eclipsing the C?C bond was also present. However, from the experimental data it was not possible to establish conclusive evidence for the conformer with an eclipsed CH 3 group. Molecular mechanics (MM) calculations and ab initio calculations using a 4-21 basis set were carried out with complete geometry optimization, and calculated parameters from each of the methods were used in combination with the ED data. Such calculations indicated the existence of all three conformers mentioned above. Least-squares analysis including constraints from the ab initio calculation gave as a result the following molecular structure ( ra distances and ??? ? angles) for the predominant conformer: r(C?C) = 1.337(6) Å, r(=C?C) = 1.503(4) Å, r(C?CH 3) = 1.522 Å, R(C?Cl) = 1.813(4) Å, < r(C?H)> = 1.089(18) Å, ???C?C?C = 122.9(2.1)°, ???C?C?C = 112.6(2.2)°, ????C?C?Cl = 109.9(0.2)°, ???Cl?C?CH 3 = 109.3°. = 121.9° and = 110.0(1.3)°. The torsional angles were then ?(C?C?C?Cl> = -119.4° and ?(C?C?C?CH 3) = 120.3(2.1)°. Error limits are 2? (? includes estimates of systematic errors and correlations), parameters without quoted uncertainties are dependent or were constrained relative to another parameter. Combining the ED data with MM results yielded parameters consistent with those given above.

Schei, S. H.

1984-09-01

105

Alumina-supported bimetallics of palladium alloyed with germanium, tin, lead, or antimony from organometallic precursors. II. Gas-phase hydrogenation of 2-methyl-1-buten-3-yne (valylene) and 2-methyl-1,3-butadiene (isoprene)  

Microsoft Academic Search

A series of PdGe, PdSb, PdSn, and PdPb\\/α-AlâOâ catalysts, prepared by the controlled surface reaction (CSR) technique from organometallic precursors have been tested in the gas-phase hydrogenation of 2-methyl-1-buten-3-yne (valylene) and 2-methyl-1,3-butadiene (isoprene). On catalysts reduced at 573 K, the turnover frequencies for valylene (TON{sub v}) and isoprene (TONâ) hydrogenation were not modified by addition to the 0.09wt% Pd\\/α-AlâOâ base

H. R. Aduriz; P. Bodnariuk; B. Coq; F. Figueras

1991-01-01

106

Population of the 3s state in hydrogen due to H/sup +/, H/sub 2//sup +/ and H/sub 3//sup +/ impact on ethylene, 1-butene and cis-2-butene  

SciTech Connect

Absolute cross sections were measured for capture or dissociation into the 3s state of atomic hydrogen due to impact of 14-28 keV H/sup +/, H/sup +//sub 2/ and H/sup +//sub 3/ ions on ethylene, 1-butene and cis-2-butene. The cross sections obtained for the butene targets were almost identical and support the additive rule for cross sections. Ethylene cross sections were 21% lower than the values predicted by the additive rule, which agrees well with the observed trend toward reduction in total electron capture cross sections for protons on these gases at much higher energies.

Loyd, D.H.; Dawson, H.R.

1983-04-01

107

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

SciTech Connect

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

Ozkan, U.; Gill, R.C.; Smith, M.R. (Ohio State Univ., Columbus (USA))

1989-03-01

108

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

SciTech Connect

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

Gill, R.C.; Ozkan, U.S. (Ohio State Univ., Columbus (USA))

1990-04-01

109

Alumina-supported bimetallics of palladium alloyed with germanium, tin, lead, or antimony from organometallic precursors. II. Gas-phase hydrogenation of 2-methyl-1-buten-3-yne (valylene) and 2-methyl-1,3-butadiene (isoprene)  

SciTech Connect

A series of PdGe, PdSb, PdSn, and PdPb/{alpha}{minus}Al{sub 2}O{sub 3} catalysts, prepared by the controlled surface reaction (CSR) technique from organometallic precursors have been tested in the gas-phase hydrogenation of 2-methyl-1-buten-3-yne (valylene) and 2-methyl-1,3-butadiene (isoprene). On catalysts reduced at 573 K, the turnover frequencies for valylene (TON{sub v}) and isoprene (TON{sub 1}) hydrogenation were not modified by addition to the 0.09wt% Pd/{alpha}{minus}Al{sub 2}O{sub 3} base catalyst of Ge, Sb, Sn, or Pb, up to0.1 wt% (at 293 K: TON{sub v}= 20 s{sup {minus}1} and TON{sub 1} = 33 s{sup {minus}1}). Pd/{alpha}{minus}Al{sub 2}O{sub 3} reduced at 773 K was severely sintered (d{sub TEM} increased from 2.8nm to 12.4nm) and TON{sub v} and TON{sub 1} at 293 K increased to 190 and 283 s{sup {minus}1}, respectively, as a result of an apparent crystal size effect: the reactants adsorb more strongly on the smaller Pd particles. Upon alloying with Ge, Sb, Sn, or Pb and a subsequent reduction at 773 K, a modest decrease of both TON{sub v} (by a factor of 2) and TON{sub 1} (by a factor of 2{minus}5) was observed. At high conversion, both the selectivity to isoprene (S{sub I}) in valylene hydrogenation, and to olefins (S{sub 0}) in isoprene hydrogenation on Pd/{alpha}{minus}Al{sub 2}O{sub 3} were improved upon alloying with Sb, Sn, or Pb (Ge had no effect). In addition, the isomerization of 2-methyl-1-butene and 3-methyl-1-butene (double bond migration reaction) during isoprene hydrogenation was partially suppressed on PdSn and PdPb/{alpha}{minus}Al{sub 2}O{sub 3}. The improvement in selectivities was interpreted in terms of a change in the relative adsorption strength of the reactants and intermediate products over the new bimetallic sites.

Aduriz, H.R.; Bodnariuk, P. (UNS-CONICET, Bahia Blanca (Argentina)); Coq, B.; Figueras, F. (CNRS ENSCM, Montpellier (France))

1991-05-01

110

Comparative DFT study of the adsorption of 1,3-butadiene, 1-butene and 2- cis/trans-butenes on the Pt(1 1 1) and Pd(1 1 1) surfaces  

NASA Astrophysics Data System (ADS)

The interaction of 1,3-butadiene, 1-butene and 2- cis/trans-butenes on the Pt(1 1 1) and Pd(1 1 1) surfaces has been studied with density functional theory methods (DFT). The same most stable adsorption modes have been found on both metal surfaces with similar adsorption energies. For 1,3-butadiene the 1,2,3,4-tetra-? adsorption structure is shown to be the most stable one, in competition with a 1,4-metallacycle-type mode, which is only less stable by 10-12 kJ mol -1. On Pt(1 1 1) these total energy calculations were combined with simulations of the vibrational spectra. This confirms that the 1,2,3,4-tetra-? adsorption is the most probable adsorption structure, but cannot exclude the 1,4-metallacycle as a minority species. Although similar in type and energy, the adsorption on the Pd(1 1 1) surface shows a markedly different geometry, with a smaller molecular distortion upon adsorption. The most stable adsorption structure for the butene isomers is the di-?-mode. Similarly to the case of the 1,3-butadiene, the adsorption geometry is closer to the gas phase one on Pd than on Pt, hence explaining the different spectroscopic results, without the previously assumed requirement of a different binding mode. Moreover the present study has shown that the different selectivity observed on Pt(1 1 1) and Pd(1 1 1) for the hydrogenation reaction of butadiene cannot be satisfactory explained by the single comparison of the relative stabilities of 1,3-butadiene and 1-butene on these metals.

Valcárcel, Ana; Clotet, Anna; Ricart, Josep M.; Delbecq, Françoise; Sautet, Philippe

2004-01-01

111

Gas-phase kinetics of hydroxyl radical reactions with C3H6 and C4H8: product branching ratios and OH addition site-specificity.  

PubMed

Products of the reaction of OH radicals with propene, trans-2-butene, and 1-butene have been investigated in a fast flow reactor, coupled with time-of-flight mass spectrometry, at pressures between 0.8 and 3.0 Torr. The product determination includes H atom abstraction channels as well as site-specific OH addition. The OH radicals are produced by the H + NO(2) ? OH + NO reaction or by the F + H(2)O ? OH + HF reaction, the H or F atoms being produced in a microwave discharge. The gas mixture is ionized using single photon ionization (SPI at 10.54 eV), and products are detected using time-of-flight mass spectrometry (TOF-MS). The H atom abstraction channels are measured to be <2% for OH + propene, 8 ± 3% for OH + 1-butene, and 3 ± 1% for OH + trans-2-butene. Analysis of ion fragmentation patterns leads to 72 ± 16% OH addition to the propene terminal C atom and 71 ± 16% OH addition to the 1-butene terminal C atom. The errors bars represent 95% confidence intervals and include estimated uncertainties in photoionization cross sections. PMID:21141895

Loison, Jean-Christophe; Daranlot, Julien; Bergeat, Astrid; Caralp, Françoise; Mereau, Raphaël; Hickson, Kevin M

2010-12-30

112

Reactions of OH with butene isomers: measurements of the overall rates and a theoretical study.  

PubMed

Reactions of hydroxyl (OH) radicals with 1-butene (k(1)), trans-2-butene (k(2)), and cis-2-butene (k(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(3))(3)-CO-OH, and monitored by narrow-line width ring dye laser absorption of the well-characterized R(1)(5) line of the OH A-X (0, 0) band near 306.7 nm. OH time histories were modeled using a comprehensive C(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. PMID:21388160

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

2011-03-31

113

Unsaturated hydrocarbons adsorbed on low coordinated Pd surface: A periodic DFT study  

NASA Astrophysics Data System (ADS)

In this work, the adsorption of several unsaturated hydrocarbon molecules on a stepped Pd(4 2 2) surface was studied. Using a periodic method based on the Density Functional Theory (DFT) formalism, different adsorption geometries for ethylene, three butene isomers ( cis/ trans-2-butene and 1-butene), acetylene and 2-butyne were investigated. The results were compared with those obtained for a free defect surface as Pd(1 1 1). The 1-butene is more stable on the free defect surface than on Pd(4 2 2). On the stepped surface, the olefins adsorb tilted towards the step and increases, in almost all the cases, the magnitude of the adsorption energy. Conversely, the 3-fold site is the most stable for the alkynes adsorption on the stepped surface, as it was found on Pd(1 1 1). The analysis of the dipole moment change indicate a charge transfer from the double bond of the olefin to the metallic surface, being higher for the Pd(1 1 1) surface. In case of the alkynes, an important back-donation is produced. Except the alkynes and the 1-butene molecule, the results show the preference of ethylene and cis/ trans-2-butene to be adsorbed on the stepped surface. These observations are related with experimental catalytic results.

Belelli, Patricia G.; Ferullo, Ricardo M.; Castellani, Norberto J.

2010-02-01

114

Stabilization and isomerization of radical cations generated by fast electron irradiation of unsaturated organic molecules in a solid argon matrix  

NASA Astrophysics Data System (ADS)

Matrix isolation EPR spectroscopy was used to study the fate of "hot" unsaturated radical cations produced by fast electron irradiation in solid argon. It was found that the radical cations of cis-2-butene, trans-2-butene and ethyl vinyl ether resulting from highly exothermic hole transfer (excess energy>6 eV) underwent effective relaxation in an argon matrix. 1-Butene radical cation exhibits isomerization to cis-2-butene radical cation. The role of molecular structure of organic radical cations in excess energy relaxation is discussed.

Feldman, V. I.; Sukhov, F. F.; Orlov, A. Yu.; Tyulpina, I. V.; Ivanchenko, V. K.

2006-01-01

115

FT-IR studies on light olefin skeletal isomerization catalysis: II. The interaction of C4 olefins and alcohols with HZSM5 zeolite  

SciTech Connect

The catalytic activity of the zeolite HZSM5 in n-butene conversion was investigated under conditions similar to those of a commercial process for skeletal isomerization. The catalyst was found to be very active in n-butene conversion, but selectivity to isobutene was low due to a predominance of cracking, coking, and oligomerization side reactions. The interaction of 1-butene, cis-2-butene, trans-2-butene, isobutene, sec-butanol, and tert-butanol was also investigated by FT-IR spectroscopy in the temperature range 150-673 K. 47 refs., 9 figs., 2 tabs.

Trombetta, M.; Busca, G. [Universita de Genova (Italy)] [Universita de Genova (Italy); Rossini, S. [Snamprogetti, Milan (Italy)] [and others] [Snamprogetti, Milan (Italy); and others

1997-06-01

116

Adsorption of alkanes, alkenes and their mixtures in single-walled carbon nanotubes and bundles  

Microsoft Academic Search

Monte Carlo simulations are employed to calculate pure component adsorption isotherms of linear alkanes (C2–C12), alkenes (C2–C4) and some of their binary mixtures (ethane–ethene, propane–propene, cis-2-butene–trans-2-butene, propene-1-butene) in single-walled carbon nanotubes. The zigzag structures of carbon nanotubes (CNTs) of various diameters [(10,0), (20,0), (30,0) and (40,0)] are used. Furthermore, Henry coefficients and isosteric heats of adsorption are calculated. The dependence

S. Jakobtorweihen; F. J. Keil

2009-01-01

117

Product studies of the atmospherically-important reactions of selected vocs. Final report, 1 January 1995-31 March 1997  

SciTech Connect

The objective of these two combined programs were: (1) To investigate the products of the gas-phase reactions of O3 with propene, 2-methylpropene, cis-2-butene, trans-2-butene, 2-methyl-2-butene and 2,3-dimethyl-2-butene in the presence of sufficient cyclohexane (or other alkane) to scavenge the OH radicals formed. (2) To investigate the products of the gas-phase reactions of the OH radical, and (3) To investigate the products formed from the gas-phase reactions of OH radicals. Experiments were carried out in large volume (5800-7900 liter) Telfon or Teflon-coated environmental chambers, with irradiation being provided (when required) by blacklamps or by a point-source xenon arc.

Atkinson, R.; Arey, J.; Tuazon, E.C.; Aschmann, S.M.; Sasaki, J.

1997-07-01

118

Hydrogenolysis and homologation of 3,3-dimethyl-1-butene on Ru/SiO{sub 2} catalyst: Implications for the mechanism of carbon-carbon bond formation and cleavage on metal surfaces  

SciTech Connect

The reactions of 3,3-dimethyl-1-butene (neohexene) with hydrogen in the presence of zero-valent ruthenium metal particles supported on silica are reported. The predominant reaction is the hydrogenation of neohexene to neohexane. Simultaneous but slower homologation and hydrogenolysis reactions are reported. The homologation and hydrogenolysis reactions run at approximately equal rates, suggesting a mechanistic link between the two processes. The relative quantities of C{sub 1}-C{sub 5} and C{sub 7} products and the variation of these quantities with respect to varying temperature, neohexene/hydrogen ratio, and contact time are reported. The distribution of the primary products, neopentane, isobutene, and methane for hydrogenolysis and 2,2-dimethyl pentane, 2,2,3-trimethyl butane, and 4,4-dimethyl-1-pentene for homologation is discussed in terms of current thought on the mechanism of homologation and hydrogenolysis of alkanes. The most likely and strongly indicated mechanism for the hydrogenolysis of neohexene involves the deinsertion of a methylidene fragment from a ruthenium-neohexyl intermediate which is also an intermediate in the hydrogenation of neohexene. The distribution of C{sub 7} homologation products does not allow one to distinguish between a simple insertion mechanism and a mechanism passing through a metallacyclic intermediate. 19 refs., 10 figs.

Toyir, J.; Leconte, M.; Niccolai, G.P.; Basset, J.M. [Laboratoire de Chimie Organometallique de Surface, Villeurbanne (France)] [Laboratoire de Chimie Organometallique de Surface, Villeurbanne (France)

1995-04-01

119

Gas-phase rate constants for the reaction of NO 3 radicals with a series of cyclic alkenes, 2-ethyl-1-butene and 2,3-dimethyl-1,3-butadiene  

NASA Astrophysics Data System (ADS)

The gas-phase reaction of NO 3 radicals with selected cyclic alkenes has been studied in a flow system at 298±2 K at a total pressure of 6.8 mbar using helium as carrier gas. Rate constants obtained with the relative rate method were: cyclopentene, (3.78±0.47)×10 -13; cyclohexene, (4.91±0.47)×10 -13; cycloheptene, (5.42±0.23)×10 -13; 1-methylcyclohexene, (1.03±0.08)×10 -11; 1,2-dimethylcyclohexene, (5.15±0.34)×10 -11; 2,3-dimethylcyclohexene, (1.54±0.23)×10 -11; methylenecyclopropane, (1.38±0.23)×10 -14; methylenecyclobutane, (4.21±0.39)×10 -13; methylenecyclopentane, (1.52±0.13)×10 -12; methylenecyclohexane, (5.38±0.70)×10 -13; methylenecycloheptane, (1.01±0.13)×10 -12; 3-methylenecyclohexene, (5.72±0.37)×10 -12; ?-pinene, (5.82±0.56)×10 -12; and ?-pinene, (2.81±0.56)×10 -11 cm 3 molecule -1 s -1. The corresponding rate constants for 2-ethyl-1-butene, (4.52±0.39)×10 -13 and 2,3-dimethyl-1,3-butadiene, (1.37±0.15)×10 -12 cm 3 molecule -1 s -1, were determined. The errors (2 ?) contain only the uncertainties from the obtained rate constant ratios.

Kind, I.; Berndt, T.; Böge, O.

1998-05-01

120

Butenes and butadiene in urban air.  

PubMed

Samples of urban air hydrocarbons were taken on specifically made adsorbent cartridges and analysed by gas chromatography after thermal desorption. The four isomeric butenes and 1,3-butadiene were favourably resolved and separated from the abundant alkanes on an aluminium oxide PLOT column. The concentrations of butadiene, reflecting outdoor urban exposure, were in the range of 0.5-5 micrograms/m3. An approximate 1:4 ratio was observed between butadiene and propene which both originate predominantly from vehicle exhaust. The four butenes made up approximately 50% of the propene concentration in exhaust-polluted air, with methylpropene greater than 1-butene greater than trans-2-butene greater than cis-2-butene. Petrol vapour contributed less than exhaust but about five times more to the 2-butenes than to methylpropene and 1-butene. The highest exposure levels of butadiene and butenes were consistently observed in the vicinity of exhaust pipes and petrol-fuelled vehicles. PMID:1384124

Löfgren, L; Petersson, G

1992-05-01

121

Formation of {beta}-hydroxycarbonyls from the OH radical-initiated reactions of selected alkenes  

SciTech Connect

{beta}-Hydroxycarbonyls can be formed from the gas-phase reactions of alkenes with the OH radical, both in the presence and in the absence of NO. To date, because of analytical difficulties, few data have been reported for the formation of this class of compound from the reactions of the OH radical with alkenes. The authors have determined that {beta}-hydroxy-ketones can be readily analyzed by gas chromatography, and in this work they have shown that in 1 atm of air the {beta}-hydroxyalkoxy radicals formed in the reactions of the OH radical with trans-2-butene, trans-3-hexene, 1-butene, and {alpha}-pinene in the presence of NO primarily decompose rather than react with O{sub 2}. Rate constant ratios k{sub d}/k{sub 0{sub 2}} (or lower limits thereof), where k{sub d} and k{sub 0{sub 2}} are respectively the rate constants for the decomposition and the reaction with 0{sub 2} of the intermediate {beta}-hydroxyalkoxy radicals, have been obtained for the reactions of the CH{sub 3}CH(O)CH-(OH)CH{sub 3}, CH{sub 3}CH{sub 2}CH(O)CH{sub 2}OH, and CH{sub 3}CH{sub 2}CH(O)CH(OH)CH{sub 2}-CH{sub 3} radicals at 296 {+-} 2 K and atmospheric pressure. Using the O{sub 3} reactions with the alkenes to generate OH radicals, the reactions of the OH radical to generate OH radicals, the reactions of the OH radical with trans-2-butene, trans-3-hexene, and {alpha}-pinene in the absence of NO lead to the formation of the expected {beta}-hydroxycarbonyls and (at least for trans-2-butene) the {alpha},{beta}-diol.

Aschmann, S.M.; Arey, J.; Atkinson, R.

2000-05-01

122

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

NASA Astrophysics Data System (ADS)

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

Gupta, Pankaj

123

The Photochemical Impact of Oceanic Hydrocarbons on the Atmospheric Marine Boundary Layer over the Gulf of Maine  

NASA Astrophysics Data System (ADS)

The concentrations of nonmethane hydrocarbons (NMHCs), halocarbons, and alkyl nitrates were quantified in situ from the surface air and water aboard the NOAA R/V Ronald H. Brown during the New England Air Quality Study (NEAQS) using gas chromatography with flame ionization and electron capture detection. The highly reactive alkenes, ethene, propene, trans-2-butene, 1-butene, isobutene, cis-2-butene, and isoprene were always supersaturated in the coastal waters. The measured air and water concentrations were used along with air-sea gas exchange relationships to determine the sea-air flux of these alkenes. The fluxes served as input into a photochemical box model to assess the impact of marine hydrocarbons on local photochemistry, specifically ozone formation and destruction, under clean marine conditions. This study helps to establish coastal baseline conditions so that the magnitude of the impact on air quality under polluted condition can be put into context.

Wingenter, O. W.; Haase, K. B.; Harlow, A.; Chen, G.; Williams, E.; Jakoubek, R.; Sive, B. C.

2003-12-01

124

The structures and vibrational frequencies of a series of linear alkenes obtained using the spectroscopic potential SPASIBA  

NASA Astrophysics Data System (ADS)

The potential energy function of SPASIBA has been extended to include linear alkenes, in order to investigate biomolecules related to biological membranes. The parameters of the potential energy function were derived by minimizing the standard deviation between the observed structures, conformational energy differences, vibrational frequencies and the predicted quantities, for a series of linear alkenes, including some deuterated analogs. For several molecules, the dipole moment and moment of inertia were also calculated and compared with experimental data. The test molecules were ethylene, propene, isobutene, cis- and trans-1-butene, cis- and trans-2-butene, trans- and cis-1,3-butadiene, isoprene, trans- and cis-1,3,5-hexatriene, and trans-1,3,5,7-octatetraene. A set of 26 independent force constants was found to be sufficient to describe correctly their structures, potential energy surfaces, and vibrational frequencies. The r.m.s. deviation between the predicted and observed frequencies was about 15 cm -1.

Chhiba, M.; Vergotten, G.

1994-09-01

125

Epoxidation of lower olefins with hydrogen peroxide and titanium silicalite  

SciTech Connect

The epoxidation of lower olefins, catalyzed by titanium silicalite (TS-1) under mild conditions, is reported. The reaction may be performed at near room temperature, in dilute alcoholic or aqueous solutions of hydrogen peroxide. In methanol C[sub 4]-C[sub 8] linear olefins, allyl chloride, and allyl alcohol show fast reaction rates and high selectivities (72-97% on H[sub 2]O[sub 2]). The solvolysis of the oxirane ring and the oxidation of the solvent are the main side reactions. Yields and kinetics are decreased by increasing the chain length or the cross-section of the olefin (n-C[sub n] > n-C[sub n+1], 1-hexene [much gt] cyclohexene), by electron-withdrawing substituents (1-butene > allyl chloride > allyl alcohol), and by solvents in the order methanol > ethanol > t-butanol. The rate of reaction also depends on the position and steric configuration of the double bond and on the branching, as a result of inductive and shape selectivity effects: trans 2-butene < iso-butene < 1-butene < cis 2-butene, 2-methyl-1-butene < 1-pentene, and 3-methyl-1-butene < 2-methyl-1-butene < 2-methyl-2-butene. The epoxidation occurs with retention of configuration. Basic compounds at low concentration do not slow the kinetics, but do improve significantly the yields, up to 97% in the epoxidation of 1-butene. At higher concentrations, TS-1 activity is decreased and eventually inhibited by bases. No effect on kinetics is exerted by tetrapropylammonium hydroxide. Catalytic activity is improved by acids. A heterolytic peracid-like mechanism is envisaged in the oxygen-transfer step. A five-membered cyclic structure, formed by a titanium hydroperoxo moiety Ti-OOH, and a protic molecule ROH at Ti sites, is proposed as the active species. 41 refs., 5 figs., 4 tabs.

Clerici, M.G.; Ingallina, P. (Eniricerche SpA, Milano (Italy))

1993-03-01

126

Oxidative dehydrogenation of 1-butene over Zn?Al ferrites  

Microsoft Academic Search

The aluminum introduction into the zinc ferrite ZnFe2?xAlxO4 in the range 0.0 ? x ? 1.0 was studied. These ferrites were calcined at two temperatures, 550°C and 750°C. X-ray diffraction (XRD) patterns showed that they have a spinel structure with Al3+ replacing Fe3+ in octahedral sites. The crystallite size decreased as the aluminum introduction increased. At high calcination temperature, sintering

J. A. Toledo; P. Bosch; M. A. Valenzuela; A. Montoya; N. Nava

1997-01-01

127

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

Microsoft Academic Search

This paper contains new views about the amorphous and partially ordered phases of the three polymers listed in the title. The discussion is based on information on structure, thermodynamic stability, and large-amplitude molecular motion. Polyethylene is the basic backbone of all alkene polymers, and the other two are the first members of the vinyl polymers which have stereospecifically placed alkyl

Rene J Androsch; Maria Laura Di Lorenzo; Christoph Schick; Bernhard Wunderlich

2010-01-01

128

Reaction mechanisms for the photocatalytic isomerization and hydrogenation of cis-2-butene over TiO sub 2  

SciTech Connect

Photocatalytic isomerization and hydrogenation of cis-2-butene over TiO{sub 2} and water-adsorbed TiO{sub 2} were investigated. The reaction products were 1-butene and trans-2-butene on TiO{sub 2} and were CH{sub 4}, C{sub 2}H{sub 6}, C{sub 3}H{sub 8}, n-C{sub 4}H{sub 10}, 1-butene, and trans-butene on water-adsorbed TiO{sub 2}. The formation amounts of these products were observed as functions of the reaction time and the light intensity. The initial rates (R{sup 0}) in 10{sup {minus}9} mol s{sup {minus}1} units, measured as a function of the relative light intensity (I{sub r}), were R{sup 0} (1-C{sub 4}H{sub 8}) = 6.09I{sub r} + 1.21I{sub r}{sup {1/2}} and R{sup 0}(trans-2-C{sub 4}H{sub 8}) = 3.39I{sub r} + 3.35I{sub r}{sup {1/2}} on TiO{sub 2} and R{sup 0}(CH{sub 4}) = 0.0087I{sub r}, R{sup 0} (C{sub 2}H{sub 6}) = 0.236I{sub r}, R{sup 0}(n-C{sub 4}H{sub 10}) = 0.045I{sub r}, R{sup 0} (1-C{sub 4}H{sub 8}) = 2.23I{sub r}{sup {1/2}}, and R{sup 0}(trans-2-C{sub 4}H{sub 8}) = 2.45I{sub r}{sup {1/2}} on water-adsorbed TiO{sub 2}. No C{sub 3}H{sub 8} as a primary product was found. From these results, it was found that the reaction modes of four kinds exist on the photocatalytic isomerization of cis-2-butene over TiO{sub 2} and the overall isomerization rate on TiO{sub 2} is about 50 times faster as compared with the total hydrogenation rate to CH{sub 4}, C{sub 2}H{sub 6}, and n-C{sub 4}H{sub 10} on water-adsorbed TiO{sub 2} at I{sub r} = 1. Reaction mechanisms in which Ti{sup 3+} and O{sup {minus}} for the isomerization to trans-2-butene depending on I{sub r}; Ti{sup 3+}, O{sup {minus}}, and OH{sup {minus}} for the isomerization to 1-butene depending on I{sub r}; OH for the isomerizations to 1-butene and trans-2-butene depending on I{sub r}{sup {1/2}}; OH and H for the hydrogenolyses to CH{sub 4} and C{sub 2}H{sub 6}; and 2H for the hydrogenation to n-C{sub 4}H{sub 10} are concerned in their formations were postulated.

Kodama, Sukeya; Yagi, Shinji (Univ. of Osaka Prefecture, Sakai (Japan))

1989-06-01

129

Comparison of the kinetics of O([sup 3]P) reactions with the four butenes over wide temperature ranges  

SciTech Connect

Rate coefficients for reactions of ground-state oxygen atoms with isobutene, trans-2-butene, and cis-2-butene have been measured using the high-temperature photochemistry (HTP) technique. The oxygen atoms were generated by flash photolysis of either O[sub 2] or CO[sub 2] and the relative atom concentrations were monitored by resonance fluorescence. We find, in cm[sup 3] molecule[sup [minus]1] s[sup [minus]1] units, for isobutene, k(284-1015 K) = 2.0 x 10[sup [minus]15](T/K)[sup 1.28] exp(543 K/T); trans-2-butene, k(292-1022 K) = 3.9 x 10[sup [minus]17](T/K)[sup 1.87] exp(743 K/T); and cis-2-butene, k(292-1086 K) = 2.4 x 10[sup [minus]17](T/K)[sup 1.94] exp(716 K/T). The 2[sigma] precision limits are around [+-]10%, and the corresponding 2[sigma] accuracy limits are estimated to be about [+-]25%. Conventional transition-state-theory calculations for the electrophilic O-addition to the double bond yield at high temperatures rate coefficients smaller than observed. A method is developed for estimating rate coefficients for H abstraction. When the results are added to those of the addition, good agreement with experiments is attained. The differences between the k(T) expressions for the present three reactions and the corresponding 1-butene reaction are discussed. Based on these observations, a method is presented for estimating rate coefficients for O-atom reactions with higher olefins over wide temperature ranges. 38 refs., 8 figs., 4 tabs.

Adusei, G.Y.; Fontijn, A. (Rensselaer Polytechnic Inst., Troy, NY (United States))

1994-04-07

130

Fourier transform infrared study of butene adsorption and reaction on a silica-supported nickel catalyst  

SciTech Connect

The adsorption of 1-butene, trans-2-butene, cis-2-butene, and 1,1-d/sub 2/-1-butene on a well-characterized silica-supported nickel catalyst was studied using Fourier transform infrared spectroscopy. The resultant hydrocarbon surface species were subjected to vacuum and hydrogen. Reaction products were monitored at temperatures from 28 to 100/sup 0/C. The initial adsorption of each of the n-butenes resulted in similar infrared spectra. The main spectral features are proposed to be associated with two surface species: a weakly adsorbed 2,3-dimetallabutane and a strongly adsorbed 1,1,2- and/or 1,1,3-trimetallabutane. The surface orientations of the initially adsorbed metallabutanes are discussed along with the effect of the surface selection rule on the observed infrared bands. Heating the catalyst under vacuum resulted in the desorption of the 2,3-species to form butane and the further dehydrogenation of other metallabutanes. The addition of hydrogen to the initially adsorbed surface species resulted in the evolution of butane and the partial hydrogenation of the strongly adsorbed metallabutanes. The resultant structures were relatively stable in hydrogen at temperatures to 120/sup 0/C. Evidence was also found for the presence of allylic species during the linear isomerization of the n-butenes. It is proposed that allylic species may be precursors to the formation of the metallabutanes as well as possible intermediates in the isomerization reaction.

Campione, T.J.; Ekerdt, J.G.

1986-11-01

131

Studies of acid-base catalyzed reactions. XIV. Isomerization of butene over La/sub 2/O/sub 3/ and ZnO  

SciTech Connect

The hydrogenation and isomerization of n-butenes have been studied over ZnO and La/sub 2/O/sub 3/. The kinetic data for ZnO showed that 1-butene was the only isomer which hydrogenated at 28/sup 0/C and that the rate of isomerization of 1-butene in the absence of H/sub 2/ was about equal to the rate of isomerization in the presence of H/sub 2/ plus the rate of hydrogenation. Moreover, the H/sub 2/-D/sub 2/ equilibration reaction was strongly inhibited in the presence of butene. In the absence of hydrocarbon, the time for half-reaction was less than 2 min, whereas in the presence of about 150 Torr of cis-2-butene or 1-butene the half-life times were 59 and 61 min, respectively. For La/sub 2/O/sub 3/, hydrogenation of butene did not occur at 60/sup 0/C although C/sub 2/H/sub 4/ reacted at room temperature. In isomerization, the initial selectivity of cis-2-butene towards formation of trans-2-butene increased (from nearly zero) with temperature and tracer experiments indicated that, as with ZnO, the mechanism of isomerization was in ce, Ti, Be, Co, Cu, Mo, Ni, P,f the Pd crystals of about 30 A. Possible mechanisms are discussed for isotope exchange in CO molecules in these catalysts and for the promoting effect of Pd on the activity of CuO.

Goldwasser, J.; Hall, W.K.

1981-09-01

132

[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

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.

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

1999-01-27

133

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

PubMed

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

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

2011-01-15

134

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

SciTech Connect

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

Koval, C.R.; Lopez, L.L.; Kaul, B.B.; Renshaw, S.; Green, K.; DuBois, M.R. [Univ. of Colorado, Boulder, CO (United States)

1995-07-01

135

Adsorption of alkenes on acidic zeolites. Theoretical study based on the electron charge density.  

PubMed

In the present work, experiments on electron density changes in the adsorption process of alkenes on acidic zeolites, in the framework of atoms in molecules theory (AIM), were carried out. Electron densities were obtained at MP2 and B3LYP levels using a 6-31++G(d,p) basis set. This study explores the energetic and the electron density redistributions associated with O-H...pi interactions. The main purpose of this work is to provide an answer to the following questions: (a) Which and how large are the changes induced on the molecular electron distribution by the formation of adsorbed alkenes? (b) Can a reasonable estimate of the adsorption energy of alkenes on the active site of zeolite be solely calculated from an analysis of the electron densities? We have used topological parameters to determine the strength and nature of the interactions in the active site of the zeolite. All the results derived from the electron density analysis show that the stabilization of the adsorbed alkenes follows the order isobutene > trans-2-butene congruent with 1-butene congruent with propene > ethene, reflecting the order of basicity of C=C bonds, i.e., (C(ter)=C(prim)) > (C(sec)=C(sec)) congruent with (C(prim)=C(sec)) > (C(prim)=C(prim)). In addition, we have found a useful set of topological parameters that are good for estimating the adsorption energy in adsorbed alkenes. PMID:19888712

Zalazar, M Fernanda; Duarte, Darío J R; Peruchena, Nélida M

2009-12-10

136

Gas-phase chemistry of the yttrium-imido cation YNH{sup +} with alkenes: {Beta}-hydrogen activation by a d{sup 0} system via a multicentered transition state  

SciTech Connect

The gas-phase chemistry of the yttrium-imido carbon cations with alkenes was studied by using Fourier transform mass spectrometry to explore the chemistry of transition metal ion complexes with low-valence metal centers. The YNH{sup +} species was synthesized by reacting Y{sup +}, generated by laser desorption, with ammonia. The dehydrogenation reaction is exothermic, yielding a lower limit for the imido bond energy of D{degree}(Y{sup +}-NH) > 101 kcal/mol. Due to the electron deficiency of the metal center upon binding to NH, the further reactivity of YNH{sup +} can only be explained by a reaction mechanism involving a multicentered transition state. YNH{sup +} reacts with ethene predominantly by dehydrogenation to produce YC{sub 2}H{sub 3}N{sup +}. Thus, instead of the metathesis reaction involving the cleavage of the 2-aza-1-metallacyclobutane intermediate, a {beta}-hydrogen transfers to the metal center and is then eliminated with a hydrogen from the remaining CH{sub 2} group to complete the reaction. All three linear butenes, 1-butene, cis-2-butene, and trans-2-butene, react very similarly with YNH{sup +}, yielding a variety of product ions with the predominant loss of NH{sub 3} resulting in the formation of YCH{sub 4}H{sub 6}{sup +}. Structural studies on this ion suggest that it is bent metallacyclopent-3-ene, not the butadiene isomer. 34 refs., 1 fig.

Ranatunga, D.R.A.; Hill, Y.D.; Freiser, B.S. [Purdue Univ., West Lafayette, IN (United States)] [Purdue Univ., West Lafayette, IN (United States)

1996-02-20

137

Polynuclear metal complexes as model mixed oxide catalysts: isomerization activity  

SciTech Connect

Supported polynuclear complexes of Cu(II) and M(III) were characterized for isomerization activity using cyclopropane (CP) and methylcyclopropane (MCP) as probe reactions. The objective of this study was to investigate the ligand effect on catalyst reactivity and selectivity when changing the complex central metal ion (cmi, M(III)) from Al to Cr to Fe. For the disappearance of CP, the iron complex showed 25 times the activity of the aluminum complex, whereas the chromium complex was 20 times as active as the aluminum complex. The relative reactivities of the complex toward the MCP reaction were Al/Cr/Fe = 1/29/22. The isomers 1-butene/trans-2-butene/cis-2-butene were produced in the proportions 0.28/0.43/0.29, independent of overall conversion. Selectivity of the MCP reaction was not a function of the cmi. The activity data are convincing evidence of a ligand effect for the central metal ion upon its neighbors in these well-characterized complexes. In addition, the activities of these complexes are compared with those of silica and silica-alumina.

Beckler, R.K.; White, M.G.

1988-04-01

138

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

PubMed

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

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

2011-09-15

139

Adsorption of Alkenes on Acidic Zeolites. Theoretical Study Based on the Electron Charge Density  

NASA Astrophysics Data System (ADS)

In the present work, experiments on electron density changes in the adsorption process of alkenes on acidic zeolites, in the framework of atoms in molecules theory (AIM), were carried out. Electron densities were obtained at MP2 and B3LYP levels using a 6-31++G(d,p) basis set. This study explores the energetic and the electron density redistributions associated with O-H···? interactions. The main purpose of this work is to provide an answer to the following questions: (a) Which and how large are the changes induced on the molecular electron distribution by the formation of adsorbed alkenes? (b) Can a reasonable estimate of the adsorption energy of alkenes on the active site of zeolite be solely calculated from an analysis of the electron densities? We have used topological parameters to determine the strength and nature of the interactions in the active site of the zeolite. All the results derived from the electron density analysis show that the stabilization of the adsorbed alkenes follows the order isobutene > trans-2-butene ? 1-butene ? propene > ethene, reflecting the order of basicity of C?C bonds, i.e., (Cter?Cprim) > (Csec?Csec) ? (Cprim?Csec) > (Cprim?Cprim). In addition, we have found a useful set of topological parameters that are good for estimating the adsorption energy in adsorbed alkenes.

Zalazar, M. Fernanda; Duarte, Darío J. R.; Peruchena, Nélida M.

2009-11-01

140

Adsorption structures of non-aromatic hydrocarbons on silicalite-1 using the single-crystal X-ray diffraction method.  

PubMed

The actual adsorption structures of non-aromatic hydrocarbons on the MFI-type zeolites have not yet been determined. This is due to the presence of twinning, which makes crystallographic analysis difficult. We recently overcame this problem, and now report the various adsorption structures of n-butane, n-pentane, n-hexane, 1-butene, cis and trans-2-butene, 2-butyne and isopentane on silicalite-1 (MFI-type zeolite) as determined via single-crystal X-ray diffraction. The structures were elucidated for both low and high loadings of each guest molecule in order to clarify the adsorption process. The low-loaded structures provide valuable insight into guest-framework interactions and initial adsorption behavior. The n-alkanes are initially adsorbed in the sinusoidal channel, while 2-butyne is adsorbed in the straight channel. In the case of the normal hydrocarbons, the molecular configuration (bent or linear) of the compound determines which channel is the preferred adsorption site. Bent molecules prefer the sinusoidal channel and linear molecules prefer the straight channel. In contrast, isopentane is initially adsorbed at the intersection, since the channels are too narrow to maintain the preferred distance between the framework and the bulky isopentane molecule. In the high-loaded structures, the guest molecules occupy additional sites, such that the normal hydrocarbons are located in both channels and isopentane is found at the intersection and the sinusoidal channel. PMID:24954128

Fujiyama, Shinjiro; Seino, Shintaro; Kamiya, Natsumi; Nishi, Koji; Yoza, Kenji; Yokomori, Yoshinobu

2014-07-01

141

Carbon K-shell electron energy loss spectra of 1- and 2-butenes, trans-1,3-butadiene, and perfluoro-2-butene. Carbon--carbon bond lengths from continuum shape resonances  

SciTech Connect

Electron energy loss spectra of 1-butene, cis-2-butene, trans-2-butene, trans-1,3-butadiene, and perfluoro-2-butene in the region of carbon K-shell (C 1s) excitation and ionization have been recorded under dipole-dominated inelastic electron scattering conditions. The features observed below the C 1s I.P. in the spectra of the butenes and butadiene are assigned to promotions of C 1s electrons to unoccupied valence (..pi..*) and Rydberg orbitals while broad features observed above the edge are assigned to sigma(C--C) and sigma(C--C) shape resonances. These spectra, along with carbon K-shell spectra of other hydrocarbons, are used to demonstrate that there is a quantitative relationship between carbon--carbon bond lengths and the location of sigma shape resonances relative to the C 1s ionization threshold (I.P.). The C 1s spectrum of perfluoro-2-butene demonstrates dramatic potential barrier effects, namely suppression of Rydberg transitions and strong enhancement of sigma(C--C) and sigma(C--F) shape resonances in the region of the C 1s ionization threshold.

Hitchcock, A.P.; Beaulieu, S.; Steel, T.; Stoehr, J.; Sette, F.

1984-05-01

142

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

143

Transition metal-promoted reactions of boron hydrides. 14. A new synthetic route to B-substituted mon-, Di-, and trialkylborazines, B-vinyl-B,B-dialkylborazines, and B-alkylpolyborazylenes via rhodium-catalyzed borazine/olefin hydroboration reactions  

SciTech Connect

The RhH(CO)(PPh[sub 3])[sub 3]-catalyzed reactions of borazine with a variety of olefins, including ethylene, propene, 1-butene, cis- and trans-2-butene, 3,3,3-trifluoropropene, styrene, [alpha]-methylstyrene, and 4-allylanisole, have been found to give the mono-, di-, and tri-B-alkylborazines in excellent yields. The reactions proceed at room temperature, with low catalyst concentrations, and the degree of substitution is controlled by altering the reactant ratios and reaction times. Unsymmetrically substituted tri-B-alkylborazines are produced by the catalyzed reaction of mono- or di-B-substituted borazines with a different olefin. B-Vinyl-B,B-dialkylborazines are prepared by the reaction of di-B-alkylborazines with acetylene in the presence of catalyst. The catalyzed reaction of borazine with 1,3-butadiene gives a mixture of monohydroboration products, but reaction with 1,5-hexadiene yields mono- and dihydroboration products and a (B[sub 3]N[sub 3]H[sub 4])[(CH[sub 2])[sub 6

Fazen, P.J.; Sneddon, L.G. (Univ. of Pennsylvania, Philadelphia, PA (United States))

1994-07-01

144

C2-C10 hydrocarbon emissions from a boreal wetland and forest floor  

NASA Astrophysics Data System (ADS)

Emissions of various C2-C10 hydrocarbons and halogenated hydrocarbons from a boreal wetland and Scots pine forest floor were measured by static chamber technique in south-western Finland. Isoprene was the main non-methane hydrocarbon emitted by the wetland but also small emissions of ethene, propane, propene, 1-butene, 2-methylpropene, butane, pentane and hexane were detected. The isoprene emission from the wetland was observed to follow the commonly used isoprene emission algorithm. The mean emission potential of isoprene was 224 ?g m-2 h-1 for the whole season. This is lower than the emission potentials published earlier and probably least partly due to the cold and cloudy weather during the measurements. No emissions of monoterpenes or halogenated hydrocarbons from the wetland were detected. Highest hydrocarbon emissions from the Scots pine forest floor were measured in spring and autumn. Main emitted compounds were monoterpenes. Isoprene emissions were negligible. Highest monoterpene emissions were measured in spring after the snow had melted. Emissions dropped in the summer and increased again in autumn. The total monoterpene emission rates varied from zero to 373 ?g m-2 h-1. Probable source for these emissions is decaying plant litter. Also small emissions of chloroform (100-800 ng m-2 h-1), ethene, propane, propene, 2-methylpropene, cis-2-butene, pentane, hexane and heptane were detected.

Hellén, H.; Hakola, H.; Pystynen, K.-H.; Rinne, J.; Haapanala, S.

2005-11-01

145

Effect of molecular structure distribution on melting and crystallization behavior of 1-butene\\/ethylene copolymers  

Microsoft Academic Search

Short chain branching (SCB) and methylene sequence length (MSL) distributions were measured by TREF and DSC coupled with successive nucleation\\/annealing (SNA) for a Ziegler–Natta and a metallocene ethylene–butene copolymer. TREF analysis indicated that the copolymer made with Ziegler–Natta catalyst exhibited a broad bimodal SCB distribution, while the polymer made with the metallocene catalysts had a narrow SCB distribution. SNA-DSC analysis

M Zhang; D. T Lynch; S. E Wanke

2001-01-01

146

Catalytic cracking of 1-butene to propene and ethene on MCM-22 zeolite  

Microsoft Academic Search

Catalytic cracking of butene to propene and ethene was investigated over HMCM-22 zeolite. The performance of HMCM-22 zeolite was markedly influenced by time-on-stream (TOS) and reaction conditions. A rapid deactivation during the first 1h reaction, followed by a quasi-plateau in activity, was observed in the process along with significant changes in product distributions, which can be attributed to the fast

Xiangxue Zhu; Shenglin Liu; Yueqin Song; Sujuan Xie; Longya Xu

2005-01-01

147

Synthesis and characterization of ZSM-22 zeolites and their catalytic behavior in 1-butene isomerization reactions  

Microsoft Academic Search

ZSM-22 zeolites, having a Si\\/Al ratio of 45, have been synthesized by sol-gel methods using 1,6-diaminohexane as a templating agent. The structures of these materials have been characterized by X-ray diffraction, transmission electron microscopy and electron diffraction, scanning electron microscopy, and adsorption techniques. Based on these analyses, these materials are determined to be of the Theta-1 structure type. Titration with

M. W. Simon; S. L. Suib; Chi-Lin OYoung

1994-01-01

148

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

PubMed

Reported here is the first ?SR study of the muon (A(?)) and proton (A(p)) ?-hyperfine coupling constants (Hfcc) of muoniated sec-butyl radicals, formed by muonium (Mu) addition to 1-butene and to cis- and trans-2-butene. The data are compared with in vacuo spin-unrestricted MP2 and hybrid DFT/B3YLP calculations reported in the previous paper (I), which played an important part in the interpretation of the data. The T-dependences of both the (reduced) muon, A(?)?(T), and proton, A(p)(T), Hfcc are surprisingly well explained by a simple model, in which the calculated Hfcc from paper I at energy minima of 0 and near ±120° are thermally averaged, assuming an energy dependence given by a basic 2-fold torsional potential. Fitted torsional barriers to A(?)?(T) from this model are similar (~3 kJ/mol) for all muoniated butyl radicals, suggesting that these are dominated by ZPE effects arising from the C?Mu bond, but for A(p)(T) exhibit wide variations depending on environment. For the cis- and trans-2-butyl radicals formed from 2-butene, A(?)?(T) exhibits clear discontinuities at bulk butene melting points, evidence for molecular interactions enhancing these muon Hfcc in the environment of the solid state, similar to that found in earlier reports for muoniated tert-butyl. In contrast, for Mu?sec-butyl formed from 1-butene, there is no such discontinuity. The muon hfcc for the trans-2-butyl radical are seemingly very well predicted by B3LYP calculations in the solid phase, but for sec-butyl from 1-butene, showing the absence of further interactions, much better agreement is found with the MP2 calculations across the whole temperature range. Examples of large proton Hfcc near 0 K are also reported, due to eclipsed C?H bonds, in like manner to C?Mu, which then also exhibit clear discontinuities in A(p)(T) at bulk melting points. The data suggest that the good agreement found between theory and experiment from the B3LYP calculations for eclipsed bonds in the solid phase may be fortuitous. For the staggered protons of the sec-butyl radicals formed, no discontinuities are seen at all in A(p)(T), also demonstrating no further effects of molecular interactions on these particular proton Hfcc. PMID:21395224

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

2011-04-01

149

Comparison of Spring and Summer Hydroxyl Concentrations in the Snowpack at Summit, Greenland  

NASA Astrophysics Data System (ADS)

The concentration of hydroxyl radical in near-surface snowpack at Summit, Greenland (72\\deg34' N, 38\\deg28' W) was estimated during two field campaigns. The first took place in the summer (2003) when hydroxyl radical should be at its peak due to 24 hours of sunlight. The second occurred in the spring (mid-March through April) of 2004, a period when Summit goes from 12 hours of sunlight to near complete sunlight and experiences rapidly changing photochemistry. The experiment consisted of adding a carefully selected mixture of hydrocarbon gases, with a wide variety of radical reactivities, to a UV and visible transparent flow chamber containing undisturbed natural firn. The relative decrease in mixing ratios of these gases allowed estimation of the mixing ratio of hydroxyl radicals in the near- surface snowpack. Hydrocarbon samples were collected in 2L stainless steel canisters and analyzed in Irvine, CA. The residence time of gases in the chamber was characterized by injection of SF6 and monitored by an on-site GC. Graphing the decay of 1-butene, i-butene, cis-2-butene, and trans-2-butene versus their respective rate constants with hydroxyl yields a straight line with a slope equal to -[OH]×? where [OH] is the gaseous hydroxyl concentration in the firn pore spaces and ? is the residence time of the gases in the firn. During the summer of 2003, the calculated OH mixing ratios followed a diurnal cycle. The peak hourly average was 5.0×106 molecules/cm3 between 1PM and 2PM local time. The minimum hourly average was 1.6×106 molecules/cm3 between 8PM and 9PM. Initial results from spring 2004 will be presented, and are expected to show hydroxyl radical concentrations that are significantly lower.

Beyersdorf, A.; Blake, N.; Swanson, A.; Meinardi, S.; Dibb, J.; Blake, D. R.; Rowland, F.

2004-12-01

150

Kinetics of hydrogen abstraction reactions of butene isomers by OH radical.  

PubMed

The rate coefficients of H-abstraction reactions of butene isomers by the OH radical were determined by both canonical variational transition-state theory and transition-state theory, with potential energy surfaces calculated at the CCSD(T)/6-311++G(d,p)//BH&HLYP/6-311G(d,p) level and CCSD(T)/6-311++G(d,p)//BH&HLYP/cc-pVTZ level and quantum mechanical tunneling effect corrected by either the small-curvature tunneling method or the Eckart method. While 1-butene contains allylic, vinylic, and alkyl hydrogens that can be abstracted to form different butene radicals, results reveal that s-allylic H-abstraction channels have low and broad energy barriers, and they are the most dominant channels which can occur via direct and indirect H-abstraction channels. For the indirect H-abstraction s-allylic channel, the reaction can proceed via forming two van der Waals prereactive complexes with energies that are 2.7-2.8 kcal mol(-1) lower than that of the entrance channel at 0 K. Assuming that neither mixing nor crossover occurs between different reaction pathways, the overall rate coefficient was calculated by summing the rate coefficients of the s-allyic, methyl, and vinyl H-abstraction paths and found to agree well with the experimentally measured OH disappearance rate. Furthermore, the rate coefficients of p-allylic H abstraction of cis-2-butene, trans-2-butene, and isobutene by the OH radical were also determined at 300-1500 K, with results analyzed and compared with available experimental data. PMID:20977273

Sun, Hongyan; Law, Chung K

2010-11-18

151

Gaseous alkene biotransformation and enantioselective epoxyalkane formation by Nocardioides sp. strain JS614.  

PubMed

Enantiopure epoxides are valuable intermediates in the synthesis of optically pure biologically active fine chemicals (e.g., pharmaceuticals) that are often difficult to produce by chemical approaches. An attractive alternative is biological synthesis by microorganisms expressing stereoselective enzymes. In this study, we investigated the ability of ethene-grown Nocardioides sp. strain JS614 to produce highly enantio-enriched epoxyalkanes via stereoselective monooxygenase-mediated alkene epoxidation. Ethene-grown JS614 cells transformed propene, 1-butene, and trans-2-butene to their corresponding epoxyalkanes at rates ranging from 27.1 to 44.0 nmol/min mg protein. Chiral gas chromatography analysis revealed that R-1,2-epoxypropane, R-1,2-epoxybutane, and trans-2R,3R-epoxybutane were produced in enantiomeric excess (e.e.) of 98%, 74%, and 82%, respectively. Ethene-grown JS614 cells also preferentially transformed trans-2S,3S-epoxybutane from a racemic mixture, but could not resolve racemic 1,2-epoxypropane. Glucose facilitated increased epoxyalkane production by ethene-grown JS614 cells. However, after 22 h of propene biotransformation with 20 mM glucose, 84% of ethene-grown JS614 cells lost membrane integrity and the remaining live cells were not viable. Propene biotransformation by JS614 was extended beyond 22 h and 54% more epoxypropane was produced when cells were resuspended in fresh buffer + glucose at 8-h intervals. We conclude that JS614 is a promising new biocatalyst for applications that involve enantiopure epoxide production. PMID:19430773

Owens, Carmen R; Karceski, Julie K; Mattes, Timothy E

2009-09-01

152

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

PubMed

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

Swarts, Andrew J; Mapolie, Selwyn F

2014-07-14

153

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

SciTech Connect

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.

Norton, J.R.

1989-01-01

154

Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes  

SciTech Connect

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.

Norton, J.R.

1989-01-01

155

New optimization method for intermolecular potentials: Optimization of a new anisotropic united atoms potential for olefins: Prediction of equilibrium properties  

NASA Astrophysics Data System (ADS)

In this study, we propose a new global procedure to perform optimization of semiempirical intermolecular potential parameters on the basis of a large reference database. To obtain transferable parameters, we used the original method proposed by Ungerer [Ungerer et al., J. Chem. Phys. 112, 5499 (2000)], based on the minimization of a dimensionless error criterion. This method allows the simultaneous optimization of several parameters from a large set of reference data. However, the computational cost of such a method limits its application, because it implies the calculation of an important number of partial derivatives, calculated by finite differences between the results of several different simulations. In this work, we propose a new method to evaluate partial derivatives, in order to reduce the computing time and to obtain more consistent derivatives. This method is based on the analysis of statistical fluctuations during a single simulation. To predict equilibrium properties of olefins, we optimize the Lennard-Jones potential parameters of the unsaturated hydrocarbon groups using the anisotropic united atoms description. The resulting parameters are consistent with those previously determined for linear and branched alkanes. Test simulations have been performed at temperatures ranging from 150 to 510 K for several ?-olefins (ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-octene), several ?-olefins (trans-2-butene, cis-2-butene, trans-2-pentene), isobutene, and butadiene. Equilibrium properties are well predicted, and critical properties can be evaluated with a good accuracy, despite the fact that most of the results constitute pure predictions. It is concluded that the AUA potential, due to a relevant physical meaning, can be transferred to a large range of olefins with good success.

Bourasseau, Emeric; Haboudou, Mehalia; Boutin, Anne; Fuchs, Alain H.; Ungerer, Philippe

2003-02-01

156

Degradation of chlorinated butenes and butadienes in granular iron columns.  

PubMed

Manufacturing facilities for production of chlorobutyl rubber have the potential to release a mixture of at least 5 chlorinated butenes and butadienes including trans-1,4-dichlorobutene-2 (1,4-DCB-2), 3,4-dichlorobutene-1 (3,4-DCB-1), 2,3,4-trichlorobutene-1 (TCB), 2-chlorobutadiene-1,3 (chloroprene) and 2,3-dichlorobutadiene-1,3 (DCBD) into groundwater environment. To evaluate the potential of using granular iron in the remediation of the above contaminants, a series of column experiments were conducted. Degradation of all 5 compounds followed pseudo-first-order kinetics. The three chlorinated butenes degraded much faster (surface area normalized half-lives, t(1/2)', ranged from 1.6 to 5.2 min m2/mL) than the 2 chlorinated butadienes (t(1/2)' ranged from 102 to 197 min m2/mL). All contaminants fully dechlorinated by granular iron to 1,3-butadiene as a common reaction intermediate that then degraded to a mixture of relatively non-harmful end products consisting of 1-butene, cis-2-butene, trans-2-butene and n-butane. Based on the kinetic data, product distributions, and chlorine mass balances, reaction pathways for these compounds are proposed. For the chlorinated butenes, 3,4-DCB-1 and TCB, undergo reductive beta-elimination reactions resulting in 1,3-butadiene and chloroprene intermediates. Dechlorination of 1,4-DCB-2 to 1,3-butadiene occurs through a reductive elimination similar to reductive beta-elimination. For dechlorination of the two chlorinated butadienes, chloroprene and DCBD, dechlorination occurs through a hydrogenolysis pathway. The common non-chlorinated intermediate, 1,3-butadiene, undergoes catalytic hydrogenation resulting in a mixture of butane isomers and n-butane. The results suggest that granular iron is an effective material for treatment of groundwater contaminated with these compounds. PMID:19847707

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

2009-10-01

157

Group 6 metal oxide-carbon aerogels. Their synthesis, characterization and catalytic activity in the skeletal isomerization of 1-butene  

Microsoft Academic Search

Group 6 metal–organic aerogels were prepared by polymerization of a resorcinol–formaldehyde mixture which contained metallic salts of the elements of this group. The aerogels prepared were carbonized both at 773 and 1273K to obtain the corresponding metal oxide–carbon aerogels. All these materials were characterized by different techniques including gas adsorption, mercury porosimetry, XRD, XPS and decomposition of isopropanol to determine

Carlos Moreno-Castilla; Francisco José Maldonado-Hódar; José Rivera-Utrilla; Enrique Rodr??guez-Castellón

1999-01-01

158

Effect of water on silica-supported phosphotungstic acid catalysts for 1-butene double bond shift and alkane skeletal isomerization  

Microsoft Academic Search

The thermal stability, acidity, catalytic activity and regenerability of silica-supported phosphotungstic acid were evaluated in reference to the bulk solid acid. Samples were prepared with 5, 10, and 25wt.% heteropolyacid (HPA) on fumed silica to examine the effect of loading on the properties of supported acid catalysts. X-ray absorption spectroscopy indicated that the supported heteropolyacids did not completely decompose when

Billy B Bardin; Robert J Davis

2000-01-01

159

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

NASA Astrophysics Data System (ADS)

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.

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

1994-01-01

160

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

NASA Astrophysics Data System (ADS)

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.

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

2010-12-01

161

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

162

Synchrotron photoionization mass spectrometry measurements of product formation in low-temperature n-butane oxidation: toward a fundamental understanding of autoignition chemistry and n-C4H9 + O2/s-C4H9 + O2 reactions.  

PubMed

Product formation in the laser-initiated low-temperature (575-700 K) oxidation of n-butane was investigated by using tunable synchrotron photoionization time-of-flight mass spectrometry at low pressure (?4 Torr). Oxidation was triggered either by 351 nm photolysis of Cl2 and subsequent fast Cl + n-butane reaction or by 248 nm photolysis of 1-iodobutane or 2-iodobutane. Iodobutane photolysis allowed isomer-specific preparation of either n-C4H9 or s-C4H9 radicals. Experiments probed the time-resolved formation of products and identified isomeric species by their photoionization spectra. For stable primary products of butyl + O2 reactions (e.g., butene or oxygen heterocycles) bimodal time behavior is observed; the initial prompt formation, primarily due to chemical activation, is followed by a slower component arising from the dissociation of thermalized butylperoxy or hydroperoxybutyl radicals. In addition, time-resolved formation of C4-ketohydroperoxides (C4H8O3, m/z = 104) was observed in the n-C4H9 + O2 and Cl-initiated oxidation experiments but not in the s-C4H9 + O2 measurements, suggesting isomeric selectivity in the combined process of the "second" oxygen addition to hydroperoxybutyl radicals and subsequent internal H-abstraction/dissociation leading to ketohydroperoxide + OH. To further constrain product isomer identification, Cl-initiated oxidation experiments were also performed with partially deuterated n-butanes (CD3CH2CH2CD3 and CH3CD2CD2CH3). From these experiments, the relative yields of butene product isomers (cis-2-butene, trans-2-butene, and 1-butene) from C4H8 + HO2 reaction channels and oxygenated product isomers (2,3-dimethyloxirane, 2-methyloxetane, tetrahydrofuran, ethyloxirane, butanal, and butanone) associated with OH formation were determined. The current measurements show substantially different isomeric selectivity for oxygenated products than do recent jet-stirred reactor studies but are in reasonable agreement with measurements from butane addition to reacting H2/O2 mixtures at 753 K. PMID:24125058

Eskola, Arkke J; Welz, Oliver; Savee, John D; Osborn, David L; Taatjes, Craig A

2013-11-27

163

Shock tube studies on the decomposition of 2-butanol.  

PubMed

The thermal decomposition of 2-butanol have been studied at temperatures of 1045-1221 K and pressures of 1.5-6 bar using the single pulse shock tube technique. Dilute concentrations of 2-butanol have been decomposed in the presence of large quantities of a radical inhibitor. The mechanism for decomposition involves direct elimination of water producing cis- and trans-2-butene, and 1-butene, and C-C bond fission producing ethylene. Acetaldehyde, propionaldehyde, and propene were also observed in much smaller yields from C-C bond fission. The respective unimolecular rate expressions are as follows: k(C(3)H(6)(OH)CH(3) ? cis-CH(3)CH?CHCH(3) + H(2)O) = 10(13.1 ± 0.3) exp(-33414 ± 755 K/T) s(-1); k(C(3)H(6)(OH)CH(3) ? trans-CH(3)CH?CHCH(3) + H(2)O) = 10(13.5 ± 0.3) exp(-33820 ± 755 K/T) s(-1); k(C(3)H(6)(OH)CH(3) ? CH(3)CH(2)CH?CH(2) + H(2)O) = 10(13.6 ± 0.3) exp(-33002 ± 755 K/T) s(-1); k(C(3)H(6)(OH)CH(3) ? C(2)H(5)(•) + (•)CH(OH)CH(3)) = 10(15.9 ± 0.3) exp(-39252 ± 755 K/T) s(-1). These rate expressions are compared with analogous reactions for primary and tertiary butanols. They form a basis for the prediction of those for related systems. Comparison with estimated values used in the simulation of butanol combustion is indicative of the uncertainties in the rate constants that are used in such models. The activation energy of 326 kJ/mol leads to a bond dissociation energy of the CH(OH)CH(3) radical (H-CH(OH)CH(3)) of 400 kJ/mol, in excellent agreement with earlier calculated results from theory and disagreement with the experimental results from iodination studies in the expected range. PMID:22946999

Rosado-Reyes, Claudette M; Tsang, Wing

2012-10-01

164

Ethylene, 1-Butene and Long Chain alpha-Olefin Terpolymerization. A Review on the Polymerization of epsilon -Caprolactone. Rubber Toughening of Polyamides.  

National Technical Information Service (NTIS)

The publication contains the following reports: Ethylene, T-Butene and Long Chain Alpha-Olefin Terpolymerization; A Review on the Polymerization of Epsilon-Caprolactone; and Rubber Toughening of Polyamides.

X. Liu J. V. Seppala P. Mouratidis R. Holsti-Miettinen

1992-01-01

165

Preparation of a blocked isocyanate compound and its grafting onto styrene- b-(ethylene- co-1-butene)- b-styrene triblock copolymer  

Microsoft Academic Search

The ?-caprolactam was used to block the isocyanate group to enhance the storage stability of allyl (3-isocyanate-4-tolyl) carbamate. The spectra of FTIR and NMR showed that blocked allyl (3-isocyanate-4-tolyl) carbamate (BTAI) possesses two chemical functions, an 1-olefin double bond and a blocked isocyanate group. The FTIR spectrum showed BTAI could regenerate isocyanate group at elevated temperature. DSC and TG\\/DTA indicated

Ligang Yin; Yanlong Liu; Zhuo Ke; Jinghua Yin

2009-01-01

166

Preparation of Poly(2-Butene 1,4-Diol Dinitrate) Darstellung von Polybuten(2)-Dioldinitrat (1,4).  

National Technical Information Service (NTIS)

In the search for new stable polymer explosives, attempts were made to synthesize poly 2-butene 1,4-diol dinitrate. The polymerization of four different kinds of starting products was studied: cis or trans 2-butene 1,4-diol; 2-butene 1,4-dinitrate; maleic...

K. M. Bucerius

1972-01-01

167

Moessbauer Spectra of Ferrite Catalysts Used in Oxidative Dehydrogenation.  

National Technical Information Service (NTIS)

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 abou...

W. R. Cares J. W. Hightower

1971-01-01

168

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

SciTech Connect

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.

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

2000-07-12

169

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

NASA Astrophysics Data System (ADS)

The formation of H2O2 and organic peroxides in the reaction of O3 with trans-2-butene and naturally occurring alkenes has been studied using a 31 m3 reaction chamber. H2O2 and organic peroxides were found to be products of the O3 reaction with trans-2-butene, isoprene, ? and ß-pinene, and limonene. Water is necessary for the formation of H2O2 and most of the H2O2 is formed via a route that does not involve HO2 radicals. Our results indicate that the reaction of O3 with natural alkenes may be a significant source of atmospheric H2O2, particularly in forest and rural areas.

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

170

Preparation and properties of plasma polymers containing organometallic (CoTPP) or metal (Be) inclusions  

Microsoft Academic Search

Plasma polymer films have been prepared and characterized for two separate applications: (1) Cobalt (II) meso-tetraphenylporphyrin (CoTPP)-containing trans-2-butene, (T2B) plasma polymers for potential use as fixed site facilitated transport membranes for separation of oxygen and nitrogen, and (2) Beryllium-containing T2B plasma, polymers for potential use as coatings on inertial confinement fusion (ICF) targets that are to be diffusion-filled with deuterium-tritium

Nancy Elaine Barr

2000-01-01

171

Gas-phase oxidation of SO/sub 2/ in the ozone-olefin reactions  

SciTech Connect

Gas-phase oxidation of SO/sub 2/ in the ozone-olefin reactions was studied, and the yield of sulfuric acid aerosol was determined for various types of olefins under atmospheric pressure. No sulfur-containing compounds other than sulfuric acid was detected. Pressure dependence of the yield of H/sub 2/SO/sub 4/ was studied for the first time for trans-2-butene. The yield decreased to zero as the total pressure of air was decreased. This fact supports the contention that only a stabilized Criegee intermediate can undergo bimolecular reactions. Stabilized fractions of CH/sub 2/O0 and CH/sub 3/CHOO in the ozone reaction of ethylene and trans-2-butene under atmospheric pressure are 0.390 +/- 0.053 and 0.185 +/- 0.028, respectively. The yield of H/sub 2/SO/sub 4/ was as low as 0.052 +/- 0.013, 0.032 +/- 0.024, and 0.029 +/- 0.015 for cyclopentane, cyclohexene, and cycloheptene, respectively. The yield of H/sub 2/SO/sub 4/ for ..cap alpha..- and ..beta..-pinene was 0.125 +/- 0.040 and 0.249 +/- 0.024, respectively. The rate constant ratio of decomposition of the initially formed hot Criegee intermediate to its collisional stabilization was obtained to be (3.9 +/- 0.8) x 10/sup 18/ molecules/cm/sup 3/ for trans-2-butene.

Hatakeyama, S.; Kobayashi, H.; Akimoto, H.

1984-09-27

172

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

PubMed

The kinetics of the reactions of the linear butadiynyl radical, C4H (CCCCH), with a variety of unsaturated hydrocarbons have been studied over the temperature range of 39-300 K using a CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, or reaction kinetics in uniform supersonic flow) apparatus combined with the pulsed laser photolysis-laser induced fluorescence technique. The rate coefficients for all the reactions studied are found to all be in excess of 10(-10) cm(3) molecule(-1) s(-1) over the entire temperature range. They can be fitted with the following expressions (valid from 39 K to 300 K, with RMS deviations of the experimental points from the predicted values shown, to which should be added 10% possible systematic error) for reaction of C4H with alkenes: k(C2H4) = (1.95 +/- 0.17) x 10(-10) (T/298 K)(-0.40) exp(9.4 K/T) cm3 molecule(-1) s(-1); k(C3H6) = (3.25 +/- 0.12) x 10(-10) (T/298 K)(-0.84) exp(-48.9 K/T) cm3 molecule(-1) s(-1); k(1-C4H8) = (6.30 +/- 0.35) x 10(-10) (T/298 K)(-0.61) exp(-65.0 K/T) cm3 molecule(-1) s(-1), for reaction of C4H with dienes: k(C3H4) = (3.70 +/- 0.34) x 10(-10) (T/298 K)(-1.18) exp(-91.1 K/T) cm3 molecule(-1) s(-1); k(1,3-C4H6) = (5.37 +/- 0.30) x 10(-10) (T/298 K)(-1.25) exp(-116.8 K/T) cm3 molecule(-1) s(-1), and for reaction of C4H with alkynes: k(C2H2) = (1.82 +/- 0.19) x 10(-10) (T/298 K)(-1.06) exp(-65.9 K/T) cm3 molecule(-1) s(-1); k(C3H4) = (3.20 +/- 0.08) x 10(-10) (T/298 K)(-0.82) exp(-47.5 K/T) cm3 molecule(-1) s(-1); k(1-C4H6) = (3.48 +/- 0.14) x 10(-10) (T/298 K)(-0.65) exp(-58.4 K/T) cm3 molecule(-1) s(-1). Possible reaction mechanisms and product channels are discussed in detail for each of these reactions. Potential implications of these results for models of low temperature chemical environments, in particular cold interstellar clouds and star-forming regions, are considered. PMID:20358064

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

2010-04-21

173

Oxidations of Acyclic Alkenes.  

National Technical Information Service (NTIS)

Rates and products of oxidation were determined for ethylene, propylene, 1-butene, 2-butene, isobutylene, trimethylethylene, 3-methyl-1-butene tetramethylethylene, 2-methyl-1-pentene, 1-hexene, t-butylethylene, neopentylethylene, 1-hexyne, and 3-hexyne at...

D. E. Van Sickle F. R. Mayo R. M. Arluck M. G. Syz

1966-01-01

174

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

NASA Astrophysics Data System (ADS)

Eighteen fluid inclusion volatile peaks have been detected and identified from 1-2 g samples (quartz) by gas chromatography using heated (~105°C) on-line crushing, helium carrier gas, a single porous polymer column (HayeSep R; 10' × 1/8?: 100/120#; Ni alloy tubing), two temperature programme conditions for separate sample aliquots, micro-thermal conductivity (TCD) and photoionization detectors (PID; 11.7 eV lamp), and off-line digital peak processing. In order of retention time these volatile peaks are: N 2, Ar, CO, CH 4, CO 2, C 2H 4, C 2H 6, C 2H 2, COS, C 3H 6, C 3H 8, C 3H 4 (propyne), H 2O (22.7 min at 80°C), SO 2, ± iso- C4H10 ± C4H8 (1-butene) ± CH3SH, C 4H 8 (iso-butylene), (?) C 4H 6 (1,3 butadiene) and ± n- C4H10 ± C4H8 (trans-2-butene) (80 and -70°C temperature programme conditions combined). H 2O is analysed directly. O 2 can be analysed cryogenically between N 2 and Ar, but has not been detected in natural samples to date in this study. H 2S, SO 2, NH 3, HCl, HCN, and H 2 ca nnot be analysed at present. Blanks determined by crushing heat-treated Brazilian quartz (800-900°C/4 h) are zero for 80°C temperature programme conditions, except for a large, unidentified peak at ~64 min, but contain H 2O, CO 2, and some low molecular weight hydrocarbons at -70°C temperature conditions due to cryogenic accumulation from the carrier gas and subsequent elution. TCD detection limits are ~30 ppm molar in inclusions; PID detection limits are ~ 1 ppm molar in inclusions and lower for unsaturated hydrocarbons (e.g., ~0.2 ppm for C 2H 4; ~ 1 ppb for C 2H 2; ~0.3 ppb for C 3H 6). Precisions (1?) are ~ ±1-2% and ~ ± 13% for H 2O in terms of total moles detected; the latter value is equivalent to ±0.6 mol% at the 95 mol% H 2O level. Major fluid inclusion volatile species have been successfully analysed on a ~50 mg fluid inclusion section chip (~7 mm × ~10 mm × ~100 ?m). Initial inclusion volatile analyses of fluids of interpreted magmatic origin from the Cretaceous Boss Mtn. monzogranite stock-related MoS 2 deposit, central British Columbia of ~97 mol% H 2O, ~3% CO 2, ~ 140-150 ppm N 2, and ~16-39 ppm CH 4 (~300-350°C) are reasonable in comparison with high temperature (~400-900°C) volcanic gas analyses from four, active calc-alkaline volcanoes; e.g., the H 2O 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% (often >95%), 88-95% and ~93%, respectively; CO 2 contents are ~3-10%, 1-10%, 3-8%, and ~3.5%. CO 2/N 2 ratios for the Boss Mtn. MoS 2 fluids of ~ 190-220 are in the range for known volcanic gas ratios (e.g., ~ 150- 240; White Island). The ?S content of the Boss Mtn. MoS 2 fluid prior to S loss by sulphide precipitation may have been ~2 mol% since CO 2/?S molar ratios of analysed high-temperature volcanic gases are ~ 1.5. This estimate is supported by ?S contents for White Island, Merapi and Momotombo volcanic gases of ~2%, ~0.5-2.5%, and ~2%. COS has been determined in H 2O-CO 2 fluid inclusions of interpreted magmatic origin from the Boss Mtn. MoS 2 deposit and the Tanco zoned granitic pegmatite, S.E. Manitoba at ~50-100 ppm molar levels, which are consistent with levels in volcanic gases. It appears that low, but significant, concentrations of C 2-C 4 alkanes (~ 1-20 ppm), C 2-C 4 alkenes (~ 1-480 ppb) and alkynes (e.g., C 3H 4) have been detected in magmatically derived fluids (Boss Mtn. MoS 2 deposit; Tanco granitic pegmatite). Significantly higher, low molecular weight hydrocarbon concentrations have been determined in a CH 4-rich (~ 2%), externally derived fluid of possible metamorphic or deep crustal origin trapped as inclusions in metasomatic wall-rock tourmaline adjacent to the Tanco pegmatite (e.g., 300/470 ppm C 2H 6; 50/90 ppm C 3H 8; 3-60 ppm C 2H 4/C 3H 6 n-C 4H 10).

Bray, C. J.; Spooner, E. T. C.

1992-01-01

175

Comportamento Catalitico da Fase Pura Bi2O3.2MoO3 (Beta) para as Reaccoes do Buteno-1 (Catalytic Behaviour of the Pure Beta - Bi2O3.2MoO3 Phase for the Reactions of 1-Butene).  

National Technical Information Service (NTIS)

A survey is given of the most important advances in the field of bismuth-molybdenum oxide catalysts and their applications to olefin oxidation are described. The influence of experimental conditions on the preparation of pure Bi2O3.2MoO3 (beta) are discus...

C. I. C. Pinheiro

1989-01-01

176

A study of the unreduced molybdena-alumina system  

Microsoft Academic Search

The isomerization and metathesis of 1-butene was carried out over a series of molybdena-alumina catalysts (1.0-8.2 wt% Mo) prepared by the adsorption equilibrium method. Catalytic conversion measurements (including the effect of preadsorbed water), tracer experiments (1-butene-d[sub o]+1-butene-d[sub 8]), pyridine adsorption followed by IR spectroscopy, and ESR studies were used as tools for the characterization of the solids. The pyridine adsorption

A. Pantoja; J. Sarrin; L. Gonzalez; O. Noguera; M. J. Perez Zurita; J. L. Galavis; J. Goldwasser

1993-01-01

177

On the pressure dependence of the NO 2 product yield in the reaction of NO 3 radicals with selected alkenes  

NASA Astrophysics Data System (ADS)

An explanation is given for the difference in pressure dependences of the NO 2 product yield in the reactions NO 3- alkene and NO 3- 1.3-alkadiene including styrene. A simple model is used to describe the decomposition over stabilization ratio for the chemically activated intermediate nitrooxy-alkyl radical. It is shown that the resonance stabilization of this radical in the case of conjugated olefins is sufficiently high to account for the difference observed. The model is applied to experimental data from the reactions of NO 3 with trans-2-butene, 2,3-dimethyl-2-butene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and styrene. Kinetic parameters for the decomposition reaction of the intermediate radicals into NO 2 and epoxide are estimated and consequences for their reactions under tropospheric conditions are discussed.

Oizmann, M.; Benter, Th.; Liesner, M.; Schindler, R. N.

178

Diffuse reflectance spectroscopy of visible alkene-O[sub 2] charge-transfer absorptions in zeolite Y and determination of photooxygenation quantum efficiencies  

SciTech Connect

Very large red shifts of charge transfer bands of 2,3-dimethyl-2-butene-O[sub 2], 2-methyl-2-butene-O[sub 2], and trans-2-butene-O[sub 2] complexes in zeolite NaY have been observed by diffuse reflectance spectroscopy. Absorption tails are shifted by over 10 000 cm[sup [minus]1] compared to gas phase, solution or solid oxygen matrix. In zeolite BaY with its divalent counterions, the 2-butene-O[sub 2] absorption is further red shifted by several thousand wavenumbers. This points to stabilization of the excited charge-transfer states by the very strong electrostatic fields inside the zeolite cages as the origin of the observed red shifts. Reaction quantum efficiencies of previously reported selective photooxygenations of these alkenes by visible light are estimated on the basis of these spectra and found to be in the range 0.1-0.3. 26 refs., 4 figs.

Blatter, F.; Moreau, F.; Frei, H. (Lawrence Berkeley Lab., CA (United States))

1994-12-15

179

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

NASA Astrophysics Data System (ADS)

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.

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

2009-10-01

180

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

PubMed

The multipurpose strain E. coli K12 343/113 allows the simultaneous detection of different DNA alterations such as base-pair changes, frameshifts and deletions. The investigations show the detection of mutagenic potency in the mixture which is called photochemical smog, produced by a flow reactor. Responsible for these effects were ozone and hydrocarbon-radicals, but not NOx, hydrocarbons (propene, isobutene, trans-2-butene) and peroxiacetylnitrate (PAN). In the given conditions these mutagenic substances are involved in DNA alterations like base-pair changes and deletions due to the amounts of colonies in the gal+-, MTR-, and arg+-system. No frameshifts could be detected in the nad+-system. PMID:3901606

Nover, H; Botzenhart, K

1985-06-01

181

Rate coefficients for the gas-phase reactions of hydroxyl radicals with furan, 2-methylfuran, 2-ethylfuran and 2,5-dimethylfuran at 300 ± 2 K  

NASA Astrophysics Data System (ADS)

Rate coefficients have been determined for the gas-phase reaction of hydroxyl (OH) radicals with the cyclic ethers furan, 2-methylfuran, 2-ethylfuran and 2,5-dimethylfuran at 300 ± 2 K in 760 Torr of synthetic air using a relative kinetic technique. The rate constants obtained using propene and trans-2-butene as reference compounds are (in units of 10 -11 cm 3 molecule -1 s -1): furan, 4.19 ± 0.21; 2-methylfuran, 6.19 ± 0.30; 2-ethylfuran, 10.77 ± 2.11; 2,5-dimethylfuran, 13.21 ± 0.92. With the exception of furan, this study represents the first determination of the rate coefficients for these cyclic ethers. The relevance of the rate coefficients for the atmospheric chemistry of furan and its derivatives is briefly discussed.

Bierbach, A.; Barnes, I.; Becker, K. H.

182

Reactions of a cationic molybdenum complex with olefins. 2. Oligomerization of 1,1-disubstituted olefins  

SciTech Connect

The oligomerization of 2-methylpropene and of other terminal disubstituted olefins in dichloromethane solution was catalyzed by [(CpMo)[sub 2](S[sub 2]CH[sub 2])([mu]-S)([mu]-SR)]OTf, where R = H, 1, or CMe[sub 3], 2. Oligomers of 2-methylpropene of the formula (C[sub 4]H[sub 8])[sub n], where n = 2-8, were detected, and the major C[sub 8] and C[sub 12] isomers have been identified. The distribution of oligomers was consistent with a carbocationic coupling mechanism. Molybdenum products isolated from the 2-methylpropene coupling reaction were found by mass spectrometry to have the formula [(CpMo)[sub 2](S[sub 2]CH[sub 2])([mu]-S) ([mu]-S(C[sub 4]H[sub 8])[sub n]H)][sup +], where n = 1-3. The role of the molybdenum catalysts as proton donors and as carbenium ion donors has been investigated, and a mechanism for oligomerization has been proposed which also takes into account the known stoichiometric reactions of 1 and 2 with olefins. 16 refs., 1 fig., 2 tabs.

Birnbaum, J.; Dubois, M.R. (Univ. of Colorado, Boulder, CO (United States))

1994-03-01

183

Surface acidity and catalytic behavior of modified zirconium and titanium dioxides  

Microsoft Academic Search

Various modified zirconium and titanium dioxides were examined as catalysts for the following test reactions: the gas phase alkylation of 1-butene with isobutane, the double bond isomerization of 1-butene and the disproportionation of dichlorodifluoromethane. The catalysts were prepared by treatment of the precipitated oxide hydrates with either fluorinating, chlorinating, sulfatizing or phosphating agents.The nature of the acid sites was determined

A. Hess; E. Kemnitz

1997-01-01

184

Isomerization of alkenes during drying over zeolites  

Microsoft Academic Search

We observed that zeolite 5A, a zeolite commonly used for drying, isomerized 1-butene and 1-hexene at room temperature. The activity for 1-butene isomerization on 3A, 4A, 5A and 13X zeolites at temperatures of 300 to 565 K is reported.

David T. Lynch; Sieghard E. Wanke

1994-01-01

185

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)

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.

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

2014-06-01

186

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

National Technical Information Service (NTIS)

For beans, ethylene was the most effective abscission accelerant examined, with decreasing activity shown by propene, carbon monoxide, acetylene, vinyl fluoride, 1-butene, and 1,3-butadiene. Carbon dioxide inhibited abscission, but its effect was overcome...

F. B. Abeles H. E. Gahagan

1968-01-01

187

Hydrocarbon conversion process  

SciTech Connect

1. A combination process is described for producing high octane blending components for gasolines which consists of (a) contacting a mixture of methanol and an olefinic C/sub 4/ cut comprising isobutene, 1-butene, and 2-butenes under etherification conditions to produce methyltertiarybutyl ether and unreacted C/sub 4/ olefinic hydrocarbons, (b) contacting the unreacted C/sub 4/ olefinic hydrocarbons with a molecular sieve to selectively adsorb 2-butenes leaving a stream comprising 1-butene, (c) subjecting at least a portion of the 1-butene stream to skeletal isomerization to form isobutene, (d) subjecting the remainder of the 1-butene stream to double bond isomerization to form 2-butenes, and (e) passing the 2-butenes formed by isomerization and an isoparaffin to alkylation to form alkylate.

Hutson, T. Jr.; Hann, P.D.

1986-04-08

188

Synthesis of (+)-CP-99,994 via Pd(0)-catalyzed asymmetric allylic and homoallylic C-H Diamination of terminal olefin.  

PubMed

This paper describes an asymmetric synthesis of the potent substance P receptor antagonist (+)-CP-99,994 from 4-phenyl-1-butene via Pd(0)-catalyzed asymmetric allylic and homoallylic C-H diamination. PMID:19778085

Fu, Renzhong; Zhao, Baoguo; Shi, Yian

2009-10-01

189

Catalytic activity of some transition metal complexes with lactam ligands  

SciTech Connect

Coordination compounds are widely used in the national economy and in chemical technology as catalysts. The authors studied complexes (I-V) as catalysts of isomerization of 1,4-dichloro-2-butene into 3,4-dichloro-1-butene.

Shestakova, S.I.; Kaplan, G.I.; Sinyukova, S.V. [Research Institute of Chemical Means for Plant Protection, Moscow (Russian Federation)] [and others

1994-08-10

190

Stereospecific Trans Photoaddition of Elementary Iodine to Aliphatic Olefins. Bridged Iodalkyl Radicals.  

National Technical Information Service (NTIS)

Elementary iodine adds readily under illumination to 1-butene, the 2-butenes, and isobutene at -40 to produce colorless crystalline diiodides. Decomposition of these diiodides to starting materials occurs at room temperature.

P. S. Skell R. R. Pavlis

1965-01-01

191

Photoionization mass spectrometer studies of the collisionally stabilized product distribution in the reaction of OH radicals with selected alkenes at 298 K  

Microsoft Academic Search

The reactions of OH radicals with propene, 1-butene, and 1-pentene have been studied in a discharge flow system coupled to a photoionization mass spectrometer. At total pressures near 2 torr a collisionally stabilized OH-alkene adduct was observed in each case. For 1-butene and 1-pentene the radicals arising from abstraction of a hydrogen atom from the alkene by OH were also

H. W. Biermann; G. W. Harris; J. N. Jr. Pitts

1982-01-01

192

Intermediates of hydrogenation of conjugated dienes and of the isomerization of n-butenes on CDO catalyst  

SciTech Connect

Product distributions obtained in the deuteration of butadiene (55% 1-butene, 45% cis-2-butene), isoprene, and 1,3-pentene and in the isomerization of 1-butene and cis-2-butene in a recycle reactor at room temperature suggested that hydrogenation and double-bond migration proceed via a common intermediate, the m-allyl anion, and that the m-allyl intermediate is reactive for 1,2- and 1,4-addition.

Okuhara, T.; Tanaka, K.

1980-01-01

193

Sulfonated polymeric dispersant compositions for subterranean well drilling, completion, and cementing  

SciTech Connect

A fluid is described, comprising: a mixture of a drilling fluid and a cement slurry; and a dispersant copolymer comprising a first monomer and a second monomer, wherein said first monomer comprises maleic anhydride and wherein said second monomer is selected from the group consisting of sulfonated ethene, sulfonated propene, sulfonated 1-butene, sulfonated 2-butene, sulfonated 1-pentene, sulfonated 2-penetene, sulfonated 2-methyl-1-butene, sulfonated 2-methyl-2-butene, sulfonated 3-methyl-1-butene, sulfonated cyclopentene, sulfonated cyclohexene, sulfonated 1-hexene, sulfonated 2-hexene, sulfonated 3-hexene, sulfonated 2-methyl-1-pentene, sulfonated 2-methyl-2-pentene, sulfonated 2-methyl-3-pentene, sulfonated 3-methyl-1-pentene, sulfonated 3-methyl-2-pentene, sulfonated 4-methyl-1-pentene, sulfonated 3,-dimethyl-1-butene, sulfonated 2,3-dimethyl-1-butene, sulfonated 2,3-dimethyl-2-butene, sulfonated 2-ethyl-1-butene, sulfonated 1,3-butadiene, sulfonated 1,3-pentadiene, sulfonated 1,4-pentadiene, sulfonated 2-methyl-1,3-butadiene, sulfonated 2,3,-dimethyl-1,3-butadiene, sulfonated 2-ethyl-butadiene, sulfonated 2-methyl-1,3-pentadiene, sulfonated 3-methyl-1,3-pentadiene, sulfonated 4-methyl-1,3-pentadiene, sulfonated 2-methyl-1,4-pentadiene, sulfonated 3-methyl-1,4-pentadiene, sulfonated 4-methyl-1,4-pentadiene, sulfonated 1,3-hexadiene, sulfonated 2,4-hexadiene, and sulfonated 1,3,5-hexatriene.

Bloys, J.B.; Morgan, R.F.

1993-06-22

194

Influence of process variables on the continuous alkylation of isobutane with 2-butene on superacid sulfated zirconia catalysts  

SciTech Connect

Two sulfated zirconia catalysts have been prepared by impregnation of zirconium hydroxide with H{sub 2}SO{sub 4} 0.3 N and 1 N. Both samples showed superacid sites as shown by a desorption temperature peak in the NH{sub 3} TPD at ca. 813 K. The activity and selectivity of these catalysts have been studied for the alkylation of isobutane with trans-2 butene in a computer-controlled continuous fixed bed reactor coupled with a sampling system which allows to make differential analysis of the products from very short reaction times. In this way, the influence of the main process variables, i.e, time on stream, reaction temperature, olefin WHSV, and isoparaffin/olefin ratio, on the 2-butene conversation and product distribution has been investigated. Cracking of larger carbocations and alkylation of isobutane with 2-butene to give trimethylpentanes were the predominant reactions occurring on the superacid catalyst in the initial stages of the reaction. The alkylation/cracking ratio increased when decreasing reaction temperature. A fast catalyst decay with time on stream was also observed, and this was accompanied by an increase in the oligomerization of butene. 23 refs., 5 figs., 4 tabs.

Corma, A.; Martinez, A.; Martinez, C. [Instituto de Tecnologia Quimica, Valencia (Spain)] [Instituto de Tecnologia Quimica, Valencia (Spain)

1994-09-01

195

Isobutane/2-butene alkylation on ultrastable Y zeolites: Influence of zeolite unit cell size  

SciTech Connect

The alkylation reaction of isobutane with trans-2-butene has been carried out on a series of steam-dealuminated Y zeolites with unit cell sizes ranging from 2.450 to 2.426 nm. A fixed-bed reactor connected to an automatized multiloop sampling system allowed differential product analysis from very short (1 min or less) to longer times on stream. A maximum in the initial 2-butene conversion was found on samples with unit cell sizes between 2.435 and 2.450 nm. However, the TMP/DMH ratio, i.e., the alkylation-to-oligomerization ratio, continuously increased with zeolite unit cell size. The concentration of reactants in the pores, the strength distribution of Bronsted acid sites, and the extent of hydrogen transfer reactions, which in turn depend on the framework Si/Al ratio of a given zeolite, were seen to affect activity and product distribution of the catalysts. Finally, the influence of these factors on the aging characteristics of the samples was also discussed. 17 refs., 7 figs., 4 tabs.

Corma, A.; Martinez, A.; Martinez, C. (Instituto de Tecnologia Quimica, Valencia (Spain))

1994-03-01

196

Production of OH radicals from the reactions of C 4-C 6 internal alkenes and styrenes with ozone in the gas phase  

NASA Astrophysics Data System (ADS)

OH formation from the ozonolysis reactions of seven internal alkenes with 4-6 carbons, styrene, trans- ?-methyl styrene, and ?-methyl styrene was studied using complementary techniques. A small-ratio relative-rate technique in which small quantities of OH tracers are added to monitor OH formation yields provided the following results: trans-2-butene, 0.64±0.12; cis-2-butene, 0.33±0.05; trans-2-pentene, 0.46±0.08; cis-2-pentene, 0.29±0.06; trans-3-hexene, 0.53±0.08; cis-3-hexene, 0.36±0.07; and 2-methyl-2-butene, 0.98±0.24. For styrene, trans- ?-methyl styrene, and ?-methyl styrene, OH yields of 0.07±0.04, 0.22±0.09, and 0.23±0.12 were measured, respectively. A second method, which monitors product formation from the OH reaction with 2-butanol was used to derive OH formation yields from 2,3-dimethyl-2-butene, 2-methyl-2-butene and cis-2-pentene, and provided yields of 0.91±0.14, 0.80±0.12, and 0.27±0.07, respectively. The results are briefly discussed in terms of the relationship between structures of these alkenes and OH formation.

Orzechowska, Grazyna E.; Paulson, Suzanne E.

197

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

198

Moessbauer spectra of ferrite catalysts used in oxidative dehydrogenation  

NASA Technical Reports Server (NTRS)

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.

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

1971-01-01

199

Evaluation of Fluidized Beds for Mass Production of IFE Targets  

SciTech Connect

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

Huang, H.; Vermillion, B.A.; Brown, L.C.; Besenbruch, G.E.; Goodin, D.T.; Stemke, R.W.; Stephens, R.B. [General Atomics (United States)

2005-01-15

200

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

SciTech Connect

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

Norton, J.R.

1994-04-25

201

Infrared multiphoton dissociation of two perfluorobutenes  

SciTech Connect

Photofragment translational spectroscopy was used to examine the infrared multiphoton dissociation of octafluoro-1-butene and octafluoro-2-butene. The predominant unimolecular reaction in octafluoro-1-butene at moderate laser fluences is cleavage of a carbon{endash}carbon single bond to give the products CF{sub 3} and C{sub 3}F{sub 5}. The two other reactions that take place are CF{sub 2} elimination and the formation of equal weight fragments with the chemical composition C{sub 2}F{sub 4}; both reactions take place via a diradical intermediate. Dissociation of octafluoro-1-butene to the resonance stabilized perfluoroallyl radical is suggested to account for the favoring of simple bond rupture. These three reaction pathways were also observed in octafluoro-2-butene dissociation, however, the branching fraction is different than from octafluoro-1-butene. In octafluoro-2-butene all three channels occur with roughly equal probability. The reactions involving CF{sub 2} loss and C{sub 2}F{sub 4} formation in octafluoro-2-butene are thought to proceed through the same diradical intermediate as in octafluoro-1-butene, necessitating a 1,2-fluorine migration. {copyright} {ital 1997 American Institute of Physics.}

Longfellow, C.A.; Berrie, C.L.; Suits, A.G.; Lee, Y.T. [Chemical Sciences Division, Lawrence Berkeley Laboratory, and Department of Chemistry, University of California, Berkeley, California 94720 (United States)] [Chemical Sciences Division, Lawrence Berkeley Laboratory, and Department of Chemistry, University of California, Berkeley, California 94720 (United States)

1997-11-01

202

Hydrogenolysis and homologation of linear and branched pentenes on Ru/SiO/sub 2/ catalysts: implication in the mechanism of C-C bond formation and cleavage on metal surfaces  

SciTech Connect

Hydrogenolysis and homologation of 1-pentene to butenes and hexenes take place simultaneously and at the same rate over a Ru/SiO/sub 2/ catalysts at 110/sup 0/C, suggesting that these two reactions are mechanistically related. /sup 13/C labeling experiments indicate that C-C cleavage occurs at the double bond of 1-pentene-1-/sup 13/C leading to unlabeled 1-butene and labeled hexenes. The product distribution in the hydrogenolysis of 1-pentene, 2-pentenes, 3-methyl-1-butene, 2-methyl-2-butene, and 2-methyl-1-butene is accounted for by a carbene-olefin mechanism, which can therefore be considered as a reasonable common path for the formation and cleavage of carbon-carbon bonds on metal surfaces.

Rodriguez, E.; Leconte, M.; Basset, J.M.; Tanaka, K.; Tanaka, K.I.

1988-01-06

203

Hydrogenation of lower alkenes and conjugated diene catalyzed by Ga2O3  

NASA Astrophysics Data System (ADS)

Hydrogenation of lower alkenes such as ethylene, propylene, and 1-butene proceeded over gallium oxide (Ga2O3). The rate of the hydrogenation was faster in the order of ethylene ? propylene > 1-butene over Ga2O3. Ga2O3 also showed the activity for hydrogenation of 1,3-butadiene where 1,4-addition of hydrogen to 1,3-butadiene mainly took place to give 2-butenes as main products. The formation rate of hydrogenated products depended on the amounts of H2 and alkenes adsorbed on Ga2O3. This implies that the hydrogenation proceeds on the basis of the Langmui-Hinshelwood mechanism.

Shishido, Tetsuya; Kuno, Hirotaka; Teramura, Kentaro; Tanaka, Tsunehiro

2012-06-01

204

Novel multimetallic hydroisomerization catalysts  

SciTech Connect

Recent work in this laboratory with supported multimetallic catalysts has resulted in the discovery of a class of catalysts with unique selectivity and activity for the hydroisomerization of 1-butene, as well as the hydrogenation of butadiene. Specifically, it was found that catalysts particles are composed of three metallic components, one from the third row of the periodic table, one from the first row of rare earths, and a platinum group metal, have higher activity and are far more selective for 1-butene isomerization than any single metal catalyst, including commercial catalysts widely used for selective hydrogenation. 19 refs., 3 figs., 2 tabs.

Not Available

1994-04-01

205

Catalytic hydrogenation in the liquid phase. Part 1. Hydrogenation of isoprene catalysed by palladium, palladium-gold and palladium-silver catalysts  

Microsoft Academic Search

The hydrogenation of isoprene (2-methyl-1,3-butadiene) proceeds at 273 K in EtOH solvent in the presence of Pd catalysts to give the three possible methylbutene isomers with high selectivity (? 98%): their proportions, which remain constant until all the isoprene has reacted, are approximately 2-methyl-2-butene, 50%; 3-methyl-1-butene and 2-methyl-1-butene, each 25%. However especially with PdCaCo3, PdBaSO4 and PdC the proportion of

Geoffrey C. Bond; Alan F. Rawle

1996-01-01

206

Role of rare earth cations in Y zeolite for hydrocarbon cracking.  

PubMed

Reaction kinetics data were collected for isobutane conversion over a series of ultra stable Y (USY) zeolite catalysts with and without rare earth cations and subjected to various extents of dealumination by steaming. We conducted these reaction studies at low temperatures (523-573 K) using isobutane feed streams containing known levels of isobutylene (100-400 ppm) so that the kinetics were controlled by bimolecular hydride transfer and oligomerization/beta-scission processes with little or no participation of monomolecular initiation reactions. These experimental conditions led to stable catalyst performance with the main products of isobutane conversion being propane, n-butane, and isopentane, with smaller amounts of propylene, trans-2-butene, and cis-2-butene. The rates of formation of these products per Brønsted acid site (as counted by pyridine adsorption) depended exponentially on Brønsted acid site density, regardless of whether the catalyst contained rare earth cations. Kinetic modeling showed an exponential dependence of hydride transfer and oligomerization/ beta-scission reaction rates on Brønsted acid site density which translated into composite activation energies for these reactions having a linear relationship with site density. Based on results in the literature from theoretical calculations, we suggest that increasing Brønsted acid site density in zeolite Y leads to larger zeolite elasticity, increased stabilization of cationic transition states, and lower composite activation barriers for hydride transfer and beta-scission steps. The role of rare earth cations, therefore, is to ensure the retention of high Brønsted acid site density under hydrothermal conditions, such as in fluid catalytic cracking (FCC) regenerators, where steam would dealuminate the Y zeolite framework and reduce this site density. It is for this reason that hydride transfer reaction rates are high in the presence of rare earth cations and lead to higher yields of less olefinic gasoline during FCC. PMID:16851208

Sanchez-Castillo, Marco A; Madon, Rostam J; Dumesic, James A

2005-02-17

207

Visible-light-induced photochemistry of 2,3-dimethyl-2-butene N[sub 2]O[sub 4] charge-transfer complexes in solid inert matrices at 75 K  

SciTech Connect

Continuous-wave laser-induced photochemistry of 2,3-dimethyl-2-butene (DMB)[center dot]s-N[sub 2]O[sub 4] complexes embedded in solid CO[sub 2] and solid Xe at 75 K was observed at wavelengths as long as 488 nm (s: symmetric form (O[sub 2]N-NO[sub 2])). The chemistry was monitored by Fourier transform infrared and UV-visible spectroscopy. Products identified by [sup 15]N and [sup 18]O isotope substitution were 2,3-dimethyl-3-nitroso-2-butyl nitrate (major), 2,3-dimethyl-3-nitro-2-butyl nitrite, and a-N[sub 2]O[sub 3] (both minor). A mechanism is proposed that is distinct from that previously suggested for thermal alkene + N[sub 2]O[sub 4] chemistry in solution and liquid N[sub 2]O[sub 4]. UV-visible spectra of DMB[center dot]s-N[sub 2]O[sub 4], 2-methyl-2-butene[center dot]s-N[sub 2]O[sub 4], and trans-2-butene[center dot]s-N[sub 2]O[sub 4] complexes in solid CO[sub 2] revealed intense new absorptions with maxima at 360, 338, and 296 nm, respectively. These are assigned to charge-transfer transitions. The DMB[center dot]s-N[sub 2]O[sub 4] charge-transfer band extends to 550 nm and is responsible for the observed photochemistry. 23 refs., 5 figs., 1 tab.

Blatter, F.; Frei, H. (Lawrence Berkeley Lab., CA (United States))

1993-02-11

208

The role of transition metal promoters on sulfated zirconia catalysts for low-temperature butane isomerization  

SciTech Connect

The low temperature isomerization of butane to isobutane was catalyzed by sulfated zirconia promoted with transition metals like Fe, Mn, and Pt. At 323 K, the Fe,Mn-promoted sample exhibited the usual induction period to a highly active state, followed by rapid deactivation. At the same conditions, a Pt-promoted catalyst also showed an induction period but was followed by a period of unusually stable activity, even in the absence of dihydrogen. The mechanism of the isomerization reaction, evaluated by using {sup 13}C-labeled butane over Fe,Mn-promoted at 323 K and unpromoted sulfated zirconia at 473 K, was found to be intermolecular. Because the formation of a C{sub 8} intermediate in a bimolecular pathway most likely involves the reaction of olefins, the effect of adding trans-2-butene to the butane feed was investigated. The increase in isomerization activity that accompanied butene addition was consistent with a mechanism in which butene is protonated by acid sites of the catalyst to initiate a chain reaction that eventually produces isobutane. Since the calculated chain length (moles isobutane formed/moles butene added) was similar for all of the materials studied, the acidities of the catalysts appear to be unaffected by the presence of transition metals. Therefore, the role of transition metal promoters in sulfated zirconia is to increase the surface concentration of intermediate butenes that subsequently react to form isobutane. Due to the very different stabilities of the promoted catalysts at low temperatures, the authors speculate that the Fe,Mn-promoted sample forms butene non-catalytically whereas the Pt-promoted sample forms butene catalytically. 46 refs., 8 figs., 4 tabs.

Tabora, J.E.; Davis, R.J. [Univ. of Virginia, Charlottesville, VA (United States)

1996-08-01

209

Nonchelated d0 zirconium-alkoxide-alkene complexes.  

PubMed

The reaction of Cp'2Zr(O(t)Bu)Me (Cp' = C5H4Me) and [Ph3C][B(C6F5)4] yields the base-free complex [Cp'2Zr(O(t)Bu)][B(C6F5)4] (6), which exists as Cp'2Zr(O(t)Bu)(ClR)+ halocarbon adducts in CD2Cl2 or C6D5Cl solution. Addition of alkenes to 6 in CD2Cl2 solution at low temperature gives equilibrium mixtures of Cp'2Zr(O(t)Bu)(alkene)+ (12a-l), 6, and free alkene. The NMR data for 12a-l are consistent with unsymmetrical alkene bonding and polarization of the alkene C=C bond with positive charge buildup at C(int) and negative charge buildup at C(term). These features arise due to the lack of d-pi* back-bonding. Equilibrium constants for alkene coordination to 6 in CD2Cl2 at -89 degrees C, K(eq) = [12][6](-1)[alkene](-1), vary in the order: vinylferrocene (4800 M(-1)) > ethylene (7.0) approximately alpha-olefins > cis-2-butene (2.2) > trans-2-butene (<0.1). Alkene coordination is inhibited by sterically bulky substituents on the alkene but is greatly enhanced by electron-donating groups and the beta-Si effect. Compounds 12a-l undergo two dynamic processes: reversible alkene decomplexation via associative substitution of a CD2Cl2 molecule, and rapid rotation of the alkene around the metal-(alkene centroid) axis. PMID:16787081

Stoebenau, Edward J; Jordan, Richard F

2006-06-28

210

Preparation and properties of plasma polymers containing organometallic (CoTPP) or metal (Be) inclusions  

NASA Astrophysics Data System (ADS)

Plasma polymer films have been prepared and characterized for two separate applications: (1) Cobalt (II) meso-tetraphenylporphyrin (CoTPP)-containing trans-2-butene, (T2B) plasma polymers for potential use as fixed site facilitated transport membranes for separation of oxygen and nitrogen, and (2) Beryllium-containing T2B plasma, polymers for potential use as coatings on inertial confinement fusion (ICF) targets that are to be diffusion-filled with deuterium-tritium fuel. A membrane formed by incorporating CoTPP into a T2B plasma polymer matrix exhibited pressure dependent permeability behavior typical of fixed site facilitated transport. This behavior is adequately described by a dual mode sorption model proposed by Fredrickson and Helfand. This model incorporates four diffusion coefficients describing transport behavior in membranes exhibiting both Langmuir and Henry mode diffusion as well as transport between the two modes. Preparation of the films and application of the Fredrickson and Helfand model to the pressure dependent permeability behavior are described. Beryllium-containing plasma polymer films were prepared by evaporating beryllium (Be) into a T2B plasma. The Be content in these films varied from zero to one hundred weight percent (pure evaporated Be). Multi-layered films of evaporated Be and T2B plasma polymer were also deposited using the same reactor configuration. Permeability to hydrogen in 1 mum thick films was 1.36 barrers and 0.13 barrers, respectively, at 55°C which would allow diffusion filling with deuterium-tritium fuel of ICF targets coated with these materials. However, oxygen contents greater than 26.5 weight percent for each of these films rendered them unusable as coatings for ICF targets.

Barr, Nancy Elaine

211

Evidence for reductive elimination of H2 in the decomposition of primary arsines  

NASA Astrophysics Data System (ADS)

The decomposition of o-CH3C6H4AsD2 ( o-tolyl AsD2) in the gas phase at 900K gives toluene with 0-3 D atoms in the methyl group and/or D on the ortho carbon. These experimental data, together with calculations carried out in the PM3 system show that the only low energy pathway for decomposition of o-tolylAsD2 involves loss of D2 followed by reaction of o-tolylAs with intact o-tolylAsD2 to give o-tolylAsD•. o-tolylAsD• can reductively eliminate toluene or can undergo a rearrangement to o-HDAsC6H4CH2• for which the calculated free energy of activation at 900K is very similar to that for reductive elimination, hence explaining the multiple deuteriation of the methyl group of toluene. Calculations on the decomposition oftBuAsH2 show that this too decomposes by loss of H2 to givetBuAs with a very low free energy of activation.tBuAs decomposes via ?-H abstraction to 2-methylpropene and AsH. There is no unimolecular process with a low free energy of activation that leads to 2-methylpropane, so it is proposed that this product arises mainly from bimolecular H transfer fromtBuAsH2 totBuAs to givetBuAsH• which can lose 2-methylpropene ortBu•.tBu• abstracts H from an AsH species to give 2-methylpropane. A number of experimental results on the decomposition oftBuAsH2 are rationalized in terms of these mechanistic pathways.

Foster, Douglas F.; Glidewell, Christopher; Woolley, Gordon R.; Cole-Hamilton, David J.

1995-11-01

212

Identification of novel aroma-active thiols in pan-roasted white sesame seeds.  

PubMed

Screening for aroma-active compounds in an aroma distillate obtained from freshly pan-roasted sesame seeds by aroma extract dilution analysis revealed 32 odorants in the FD factor range of 2-2048, 29 of which could be identified. The highest FD factors were found for the coffee-like smelling 2-furfurylthiol, the caramel-like smelling 4-hydroxy-2,5-dimethyl-3(2H)-furanone, the coffee-like smelling 2-thenylthiol (thiophen-2-yl-methylthiol), and the clove-like smelling 2-methoxy-4-vinylphenol. In addition, 9 odor-active thiols with sulfurous, meaty, and/or catty, black-currant-like odors were identified for the first time in roasted sesame seeds. Among them, 2-methyl-1-propene-1-thiol, (Z)-3-methyl-1-butene-1-thiol, (E)-3-methyl-1-butene-1-thiol, (Z)-2-methyl-1-butene-1-thiol, (E)-2-methyl-1-butene-1-thiol, and 4-mercapto-3-hexanone were previously unknown as food constituents. Their structures were confirmed by comparing their mass spectra and retention indices as well as their sensory properties with those of synthesized reference compounds. The relatively unstable 1-alkene-1-thiols represent a new class of food odorants and are suggested as the key contributors to the characteristic, but quickly vanishing, aroma of freshly ground roasted sesame seeds. PMID:20491509

Tamura, Hitoshi; Fujita, Akira; Steinhaus, Martin; Takahisa, Eisuke; Watanabe, Hiroyuki; Schieberle, Peter

2010-06-23

213

Cut C/sub 4/ recovery costs  

SciTech Connect

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

Strigle, R.F.; Fukuyo, K.

1986-06-01

214

Methods for the determination of molecular mobility of adsorbed molecules based on high resolution NMR  

Microsoft Academic Search

Based on the increased resolution achieved in NMR on adsorbed molecules, various methods are proposed to determine the mobility of adsorbed species. 1H NMR linewidths are shown to reflect intramolecular dipolar relaxation and can therefore be used for mobility estimates. This method is applicable to extremely low loadings. Thus we measured a significant decrease in molecular mobility for 1-butene adsorbed

U. Schwerk; D. Michel

1996-01-01

215

Studies of vanadium-phosphorus-oxygen selective oxidation catalysts by sup 31 P and sup 51 V NMR spin-echo and volume susceptibility measurements  

SciTech Connect

The purpose of this work is to characterize the vanadium-phosphorous oxide (V-P-O) catalysts for the selective oxidation of n-butane and 1-butene to maleic anhydride. The utility of solid state nuclear magnetic resonance as an analytical tool in this investigation lies in its sensitivity to the electronic environment surrounding the phosphorous and vanadium nuclei, and proximity of paramagnetic species. Spin-echo mapping NMR of {sup 31}p and {sup 51}v and volume magnetic susceptibility measurements were used as local microscopic probes of the presence of V{sup 5+}, V{sup 4+}, V{sup 3+} species in the model compounds: {beta}-VOPO{sub 4}, {beta}-VOPO{sub 4} treated with n-butane/1-butene, (VO){sub 2}P{sub 2}O{sub 7} treated with n-butane/1-butene; and industrial catalysts with P/V (phosphorus to vanadium) ratio of 0.9, 1.0 and 1.1, before and after treatment with n-butane and 1-butene. The NMR spectra provide a picture of how the oxidation states of vanadium are distributed in these catalysts. 73 refs., 32 figs., 8 tabs.

Li, Juan.

1991-10-01

216

In-Site Polarization Modulated FTIR and Differential Electrochemical Mass Spectroscopy.  

National Technical Information Service (NTIS)

We recently report the electrochemical promotion of the heterogeneously catalyzed isomerization of 1-butene to cis- and trans-butene with p values of 38 and 46, respectively. at the remarkably low temperature of 70 Deg C using Nafion as the electrolyte in...

E. S. Smotkin

2000-01-01

217

Femtosecond lasers for mass spectrometry: proposed application to catalytic hydrogenation of butadiene.  

PubMed

Mass spectra from the interaction of intense, femtosecond laser pulses with 1,3-butadiene, 1-butene, and n-butane have been obtained. The proportion of the fragment ions produced as a function of intensity, pulse length, and wavelength was investigated. Potential mass spectrometry applications, for example in the analysis of catalytic reaction products, are discussed. PMID:22068546

Kelly, Orla; Duffy, Martin J; King, Raymond B; Belshaw, Louise; Williams, Ian D; Sá, Jacinto; Calvert, Chris R; Greenwood, Jason B

2012-01-01

218

Hydrocarbon conversion processes  

SciTech Connect

This patent describes process to produce methyl-tert-butyl-ether by reacting isobutene and methanol in an ether forming zone in the presence of a catalyst under ether forming conditions. The process comprises: passing an isobutane containing stream and steam into contact with a reforming catalyst comprising a catalyst base and a Group VIII metal in an isomerization and reforming zone at a temperature in the range of 950{sup 0}F to 1150{sup 0}F, to convert at least some of the isobutane to isobutene; withdrawing a reaction effluent from the isomerization and reforming zone; passing at least a portion of the reaction effluent into an ether forming zone and reacting therein isobutene with methanol in the presence of an ether forming catalyst to form an methyl-tert-butyl-ether, withdrawing methyl-tert-butyl-ether containing effluent from the ether forming zone and passing the effluent to a separation zone, separating in the separation zone and ether containing effluent into a methyl-tert-butyl-ether containing product stream a 1-butene containing stream, and a 2-butene containing byproduct stream, passing the 1-butene containing stream into the isomerization and reforming zone and into contact with the reforming catalyst such as to convert at least a portion of the 1-butene in the 1-butene containing stream and form 2-butene which is withdrawn from the separation zone as the by-product stream.

Brinkmeyer, F.M.; Rohr, D.F.

1989-09-12

219

Relation between adsorption and catalysis in the case of NiO and Co 3O 4  

NASA Astrophysics Data System (ADS)

Reversed flow-inverse gas chromatography is a quick, precise and effective methodology to characterize physicochemical properties of adsorbents. This is extended to the experimental measurement of the adsorption energy distribution function as well as of the differential energy of adsorption due to lateral interactions of molecules adsorbed on two catalysts, namely Co 3O 4 and NiO. Thus, the nature and the strength of the adsorbate-adsorbent and adsorbate-adsorbate interactions are extracted in order to give detailed answers to the questions: (a) where are the molecules on the heterogeneous surface and (b) which is the nature of the surface chemical bonds? Thus, adsorption of 1-butene was found to take place immediately and irreversibly. It holds a deep relation between adsorption and catalysis of 1-butene over these catalysts. As a consequence, the adsorption of 1-butene in the presence of hydrogen leads to isobutane and/or n-butane, depending on the temperature. It can be seen from the adsorption/desorption kinetic constants that the adsorption of 1-butene on Co 3O 4 is one order higher than over NiO. This fact in connection with the bigger activation energy and the lower kinetic coefficients concerning hydrogenation reaction over NiO shows that Co 3O 4 is a better catalyst for this kind of catalysis.

Arvaniti, I.; Netos, V.; Siokos, V.; Metaxa, E.; Kalantzopoulou, F. Roubani

2010-06-01

220

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

SciTech Connect

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

Augustine, R.L.

1991-11-07

221

Systematic preparation of selective heterogeneous catalysts  

SciTech Connect

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

Augustine, R.L.

1991-11-07

222

Selective oxidation using catalyst electrodes supported on solid electrolyte  

Microsoft Academic Search

The major oxygenated products of the selective oxidation of 1-butene by using a catalyst electrode were maleic anhydride on V2O5\\/YSZ\\/Ag and butadiene on MoO3?Bi2O3?Ag\\/YSZ\\/Ag. Their selectivities were enhanced as compared with the non-electrochemical system.

Seung-Doo Park; Ji-Hoon Jung; Suk-In Hong

1996-01-01

223

Organic chemistry in the oceans of Titan  

Microsoft Academic Search

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

F. Raulin

1987-01-01

224

In vitro antifungal activity of new series of homoallylamines and related compounds with inhibitory properties of the synthesis of fungal cell wall polymers  

Microsoft Academic Search

The synthesis, in vitro antifungal evaluation and SAR studies of 101 compounds of the 4-aryl-, 4-alkyl-, 4-pyridyl or -quinolinyl-4-N-arylamino-1-butenes series and related compounds, are reported here. Active structures showed to inhibit (1,3)-?-d-glucan and mainly chitin synthases, enzymes that catalyze the synthesis of the major fungal cell wall polymers.

Leonor Y Vargas M; Mar??a V Castelli; Vladimir V Kouznetsov; Juan M Urbina G; Silvia N López; Maximiliano Sortino; Ricardo D Enriz; Juan C Ribas; Susana Zacchino

2003-01-01

225

59 FR- National Emission Standards for Hazardous Air Pollutants for Certain Source Categories; Final...  

Federal Register 2010, 2011, 2012, 2013

...542756 II Dichlorotetrafluoro- 1320372 V ethane. Dichloro-1-butene (3,4...concentration of either TOC (minus methane and ethane) or organic HAP shall be calculated according...Concentration of TOC (minus methane and ethane), dry basis, parts per million by...

1994-04-22

226

A Practical, Two-Step Synthesis of 2-Substituted 1,3-Butadienes  

PubMed Central

A two-step procedure for preparing 2-alkyl-1,3-butadienes is described. Cuprate addition to commercially available 1,4-dibromo-2-butene yields 3-alkyl-4-bromo-1-butene, a product of SN2? substitution. Dehydrohalogenation gives 2-alkyl-1,3-butadienes.

Sen, Sushmita; Singh, Swapnil; Sieburth, Scott McN.

2009-01-01

227

Effect of structure on the rate constants for reaction of NO3 radicals with a series of linear and branched C5-C7 1-alkenes at 296 ± 2 K.  

PubMed

Rate constants for the gas-phase reactions of NO3 radicals with 13 linear and branched C5-C7 1-alkenes, CH2?CHR, where R = alkyl, have been measured at 296 ± 2 K and atmospheric pressure of air by a relative rate method. 1-Butene was used as the reference compound, and the rate constants obtained (in units of 10(-14) cm(3) molecule(-1) s(-1)) were as follows: 1-pentene, 1.50 ± 0.07; 1-hexene, 1.80 ± 0.08; 1-heptene, 2.06 ± 0.14; 3-methyl-1-butene, 1.39 ± 0.04; 3-methyl-1-pentene, 1.39 ± 0.03; 4-methyl-1-pentene, 1.52 ± 0.04; 3,3-dimethyl-1-butene, 1.54 ± 0.03; 3-methyl-1-hexene, 1.65 ± 0.08; 4-methyl-1-hexene, 1.86 ± 0.08; 5-methyl-1-hexene, 2.14 ± 0.08; 3,3-dimethyl-1-pentene, 1.44 ± 0.07; 3,4-dimethyl-1-pentene, 1.49 ± 0.10; and 4,4-dimethyl-1-pentene, 1.37 ± 0.06; where the indicated errors are two least-squares standard deviations and do not include uncertainties in the rate constant for the reference compound 1-butene. These rate constants increase along the series 1-butene < 1-pentene < 1-hexene < 1-heptene, and this is attributed to inductive effects. For a given carbon number, the rate constants depend on the position and degree of branching, and the observed trend of measured rate constants with position and degree of branching in the alkyl substituent group R correlates well with steric hindrance as calculated by McGillen et al. ( Phys. Chem. Chem. Phys. 2008 , 10 , 1757 ). PMID:21306140

Aschmann, Sara M; Atkinson, Roger

2011-03-01

228

C4H8[radical sign]+ isomerizations by theory  

NASA Astrophysics Data System (ADS)

Structures, energies and reaction coordinates for much of the C4H8[radical sign]+ potential surface were obtained by ab initio and density functional theories. Most C4H8[radical sign]+ isomers are demonstrated to be mutually accessible below the threshold for the lowest energy dissociation, consistent with inferences from earlier experimental data. The "virtual intermediates" (point that reactions pass through corresponding to a conventional structure but lacking a corresponding potential minimum) CH3+CHCH2CH2[radical sign] and +CH2CH(CH3)CH2[radical sign] are found to be very important in C4H8[radical sign]+ rearrangements. CH3+CHCH2CH2[radical sign] is accessed from the 1-butene cation by a 1,4- and a 1,2-H-shift, the 2-butene cation by a 1,2-H-shift and the 1-methylcyclopropane cation by ring opening. All reactions through CH3+CHCH2CH2[radical sign] begin or end with a 1,2-H-shift going to or from the 1-butene ion. The 1-butene cation appears to form rather than the more stable 2-butene cation because the minimum energy pathways down from higher energy transition states go to the 1-butene cation side of the transition state that connects the 1-butene and the 2-butene ions. Perhaps charge localization on the CH carbon directs these pathways to the 1-butene cation by a carbocation-like rearrangement. Predicted competition between 1,3- and consecutive 1,2-transfers across double bonds, despite 1,2-shifts being energetically strongly favored over 1,3-shifts in other systems, is another interesting feature of C4H8[radical sign]+ reactions. The lowest energy isomerization found in this work was a 1,5-H-shift in the 1-pentene ion. In contrast to CH3+CH CH2CH2[radical sign], CH3+CHCH2CH2CH2[radical sign] appears to inhabit a potential energy minimum, albeit a shallow one. The order of the critical energies for different ring sized transfers is 1,4 > 1,3 [congruent with] 1,2 > 1,5 in the CnH2n[radical sign]+ ions examined, differing from the order 1,3 > 1,4 > 1,2 > 1,5 established for other homologous series of aliphatic radical cations.

Hudson, Charles E.; Wang, David; McAdoo, David J.

2004-08-01

229

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

PubMed

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

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

2013-12-01

230

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

NASA Astrophysics Data System (ADS)

We use 1-methylallyl radical (CH3CH=CH-CH2· ? CH3C·H-CH=CH2·) as a model of allylic radicals generated during combustion of unsaturated diesel fuel molecules. The chemically activated isomerization of 1-methylallyl generated in the highly exothermic (˜35 kcal/mol) OH + trans-2-butene reaction was considered by using RRKM/Master Equation calculations from 0.01 to 100 atm and from 300 to 700 K. Density functional theory (DFT) with the M05-2X, M06-2X and B3LYP functionals are used for structures, energies, vibrational frequencies, anharmonic constants, and the torsional potentials of methyl rotations. The cis:trans ratio formed upon quenching the radicals were, as might be expected, dependent on the functional, but, were even more sensitive when an vibrations were treated as anharmonic. The fraction of cis- 1-methylallyl is significant, if not dominant at 300 -700 K and 0.01 -10 atm. Sensitivity studies were carried out to determine the dependence of the cis:trans ratio on the extent of chemical activation, treatment of the K-rotor as active or inactive, and the rate of collisional energy transfer. All these parameters significantly influence the cis:trans ratio. The 1,5 H-migration reaction of 3-hydroperoxy-1-propylperoxy radical (HOOCH2CH2CH2OO·) is a important as a model of a critical propagation step in diesel autoignition from alkanes or molecules with long alkyl tails. Its product may be the meta-stable alpha,gamma-dihydroperoxypropyl radical or, if unstable, OH + 3-hydroperoxypropanal. To study the possibly different tunneling effects of the two possible products, the quantum mechanical rate constants, including tunneling, are directly determined using semi-classical transition state theory (SCTST) at 200 K to 1700 K. Small-curvature tunneling (SCT) is to compute tunneling corrections to classical rate constants. The two reactions do not have obvious tunneling differences at above 700 K. Below 700 K, SCTST tunneling corrections are significantly higher than SCT corrections, for reasons which are poorly understood. The anharmonic, tunneling, and variational corrections to the TST rate constant are combined together as a total correction for transition state theory rate constants, resulting in rate constants ˜10 times larger at 500-1700 K than that by standard transition state theory with harmonic treatment of vibrations. The pressure-dependent rate constant are calculated using RRKM/Master Equation methods.

Sha, Yuan

231

Studies of NO sub 3 radical reactions with some atmospheric organic compounds at low pressures  

SciTech Connect

Rate constants for the reactions of NO{sub 3} with trans-2-butene (1), isoprene (2), {alpha}-pinene (3), and acetaldehyde (4) have been measured as a function of temperature at low pressures in a fast flow system with LIF detection of the NO{sub 3} reactant and NO{sub 2} product. Rate constants for reaction 1 were found to be independent of pressure from 0.44 to 4.5 Torr, and the Arrhenius plot was curved. The data were fit by the four-parameter equation, k{sub 1} (T = 204-378 K) = (1.78 {plus minus} 0.36) {times} 10{sup {minus}12} exp(-(530 {plus minus} 100)/T) + (1.28 {plus minus} 0.26) {times} 10{sup {minus}14} exp((570 {plus minus} 110)/T) (where all the error limits are the 95% confidence levels including a factor for systematic error, and the units are cm{sup 3} molecule{sup {minus}1} s{sup {minus}1}). The data for isoprene were fit by a normal Arrhenius equation, k{sub 2} (T = 251-381 K) = (3.03 {plus minus} 0.45) {times} 10{sup {minus}12} exp(-(450 {plus minus} 70)/T). The Arrhenius plots for {alpha}-pinene and acetaldehyde were linear, and the fits gave k{sub 3} (T = 261-384 K) = (1.19 {plus minus} 0.31) {times} 10{sup {minus}12} exp((490 {plus minus} 70)/T) and k{sub 4} (T = 264-374 K) = (1.44 {plus minus} 0.18) {times} 10{sup {minus}12} exp(({minus}1860 {plus minus} 300)/T). The efficiencies for the conversion of NO{sub 3} to NO{sub 2} were determined for reactions of trans-3-butene and isoprene at low pressures and room temperature in He, N{sub 2}, and O{sub 2} carrier gases, and at 360 K in 1 Torr of He. The measured yields of NO{sub 2} decreased with increasing size of the organic reactant, with increasing pressure, with decreasing temperature, and with increasing deactivation efficiency of the carrier gas.

Dlugokencky, E.J.; Howard, C.J. (National Oceanic and Atmospheric Administration, Boulder, CO (USA))

1989-02-09

232

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

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.

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

2005-07-15

233

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

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.

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

2005-07-15

234

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

Microsoft Academic Search

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

Arjan J. van den Wijngaard; Jaap Kingma; Dick B. Janssen

1998-01-01

235

Age-Dependent Discrimination between Stereoisomers of 1-Amino-2-Ethylcyclopropane-1-Carboxylic Acid in Carnation Petals 1  

PubMed Central

The ability of carnation petals (Dianthus caryophyllus L. cv White Sim) of different ages to convert the cis and trans isomers of 1-amino-2-ethylcyclopropane-1-carboxylic acid (AEC) to 1-butene was studied. Young petals, which produce ethylene at a low rate, convert both cis- and trans-AEC to 1-butene with low efficiency and at equal rates. In senescing petals, the rate of conversion of cis-AEC remains low, but there is a marked increase in the rate of trans-AEC conversion. Thus there is a clear evidence of stereodiscrimination between the isomers. Stimulating the rate of senescence by treatment with either 1-aminocyclopropane-1-carboxylic acid or ethylene further increases the rate of trans-AEC conversion. Delaying of petal senescence by silver thiosulphate or aminooxyacetic acid inhibits the rise in trans-AEC conversion.

Adam, Zach; Mayak, Shimon

1986-01-01

236

The Activation of Hydrocarbon CH Bonds over Transition Metal Oxide Catalysts: A FTIR Study of Hydrocarbon Catalytic Combustion over MgCr 2O 4  

Microsoft Academic Search

The interaction of light hydrocarbons (methane, ethane, propane, propene, n-butane, isobutane, 1-butene, benzene, and toluene) with the oxidized surface of the spinel MgCr2O4 (an active hydrocarbon combustion catalyst) has been investigated by FTIR spectroscopy in the temperature range 300-773 K. This interaction results in the reduction of the catalyst and the production of oxygen-containing adsorbed species. These species have been

E. Finnocchio; G. Busca; V. Lorenzelli; R. J. Willey

1995-01-01

237

Mechanistic studies of isopentane activation over solid acid catalysts. HD exchange with USY zeolite, amorphous silica-alumina and Amberlyst-15  

Microsoft Academic Search

The mechanism of activation of isopentane on USY zeolite, amorphous silica-alumina and Amberlyst-15 catalysts was studied by H-D exchange. Only the zeolite showed exchange with the isopentane at 373 K. The addition of 10% of 2-methyl-1-butene to the isopentane accelerates the exchange with USY zeolite and promotes a small exchange with amorphous silica-alumina and Amberlyst-15. Nevertheless, the selectivity was different.

Claudio J. A. Mota; Sonia C. Menezes; Leonardo Nogueira; W. Bruce Kover

1996-01-01

238

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

PubMed Central

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

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

1968-01-01

239

The effect of supported MoOX structures on the reaction pathways of propene formation in the metathesis of ethylene and 2-butene.  

PubMed

The kind of surface MoOX structures on Al2O3-SiO2 was found to determine propene selectivity in the metathesis of ethylene and 2-butene. Compared to isolated tetrahedral MoOX species, their polymerized octahedral counterparts show significantly lower activity for isomerisation of 2- to 1-butene thus hindering non-selective metathesis of these butenes. In addition, they reveal higher ability to engage ethylene in propene formation. PMID:24819240

Hahn, T; Kondratenko, E V; Linke, D

2014-07-17

240

Kinetics of n-butylbenzene dehydrocyclization over chromia-alumina  

SciTech Connect

The kinetics of dehydrogenation, cyclization, and isomerization steps in n-butylbenzene dehydrocyclization over precoked chromia-alumina has been investigated at 683--783 K. Apparent kinetic parameters of a pseudohomogeneous model were calculated from the initial-rate and integral-rate data measured with n-butylbenzene and 4-phenyl-1-butene in an isothermal fixed-bed reactor. Dehydrocyclization was shown to proceed by dehydrogenation of n-butylbenzene to n-butenylbenzenes, by their cyclization, and by dehydrogenation of the cyclic products to methylindenes and naphthalene. Direct cyclization of n-butylbenzene was of little importance over the precoked catalyst. According to the initial-rate data, dehydrogenation to n-butenylbenzenes followed an apparent order of 0.5 and the kinetic parameters seemed to be applicable also at higher conversions. The primary dehydrogenation products were 1-phenyl-1-butenes, and a surface model based on hydrogen abstraction from the {alpha}-carbon has been discussed. The initial cyclization rates measured with 4-phenyl-1-butene were appreciably lower than those observed in integral-rate experiments. The discrepancy was tentatively explained by the higher reactivity of 1-phenyl-1-butenes, which are the main constituents of the n-butenylbenzene fraction at longer contact times. High conversion runs with n-butylbenzene also showed that methylindenes and -indans were partly dealkylated and probably polymerized. The apparent orders ranged from 1 to 1.5 for 1,6-cyclization and from 0.5 to 0.8 for 1,5-cyclization. Skeletal isomerization of n-butylbenzene to sec-butyl- and sec-butenylbenzenes was rapidly subsided during coking, and on the coked catalyst at 783 K the reaction followed an apparent order of {minus}0.5.

Laatikainen, M.; Vahteristo, K.; Saukkonen, S.; Lindstroem, M. [Lappeenranta Univ. of Technology (Finland). Dept. of Chemical Technology] [Lappeenranta Univ. of Technology (Finland). Dept. of Chemical Technology

1996-07-01

241

Cyanocobalamin Enables Activated Sludge Bacteria to Dechlorinate Hexachloro-1,3-butadiene to Nonchlorinated Gases  

Microsoft Academic Search

The ability of activated sludge obtained from a local wastewater treatment plant to dechlorinate hexachloro-1,3-butadiene (HCBD) in the presence of either acetate or lactate and cyanocobalamin was investigated. Results from headspace analysis indicated complete dechlorination of HCBD by the accumulation of fully dechlorinated C4 gases (1-buten-3-yne, 1,3-butadiene, and 1,3-butadiyne). Dechlorination products were not observed in the control cultures without cyanocobalamin.

D. L. James; R. Cord-Ruwisch; D. Schleheck; M. J. Lee; M. Manefield

2008-01-01

242

Investigation of the ozonolysis of short chained alkenes in the atmosphere simulation chamber SAPHIR  

NASA Astrophysics Data System (ADS)

Reaction rate coefficients and product yields in the gas-phase reaction of O3 with the short-chained alkenes ethene, propene, 1-butene, isobutene, (E)-butene, and (Z)-butene were determined in the atmosphere simulation chamber SAPHIR. In a first set of experiments reaction rate coefficients were acquired in an absolute reaction rate study from the measured concentration-time profiles of ozone and the alkenes with side reactions being suppressed by adding a radical scavenger. The rate coefficients obtained agree well with literature data; for all alkenes but (E)-butene the deviation was less than 10%. In a second set of experiments OH yields were derived from the additional alkene turnover in the absence of a radical scavenger. In contrast to other studies the OH yields determined in the dry chamber (propene: 0.10 ± 0.07; 1-butene: 0.00 ± 0.08, isobutene: 0.30 ± 0.14, (Z)-butene: 0.18 ± 0.09, and (E)-butene: 0.70 ± 0.12) differed from the yields obtained under humid conditions (propene: 0.30 ± 0.08, 1-butene: 0.30 ± 0.09, isobutene: 0.80 ± 0.10, (Z)-butene: 0.40 ± 0.05, and (E)-butene: 0.60 ± 0.12). The only exception was ethene ozonolysis where no OH production was observed. HO2 yields (propene: 1.50 ± 0.75, 1-butene: 1.60 ± 0.80, and isobutene: 2.00 ± 1.00) were estimated from the additional ozone turnover compared to the experiments where radicals were scavenged. Yields of HO2 were compared to the yields obtained from direct HO2 observation by Laser-Induced Fluorescence Spectroscopy (LIF). Furthermore, the yields of the stable ozonolysis products CO, acetaldehyde, and formaldehyde were acquired by monitoring the concentration time profile of the respective compound.

Wegener, R.; Brauers, T.; Hofzumahaus, A.; Holland, F.; Koppmann, R.; Rodríguez Bares, S.; Rohrer, F.; Rupp, L.; Tillmann, R.; Wahner, A.; Hansel, A.; Wisthaler, A.

2006-12-01

243

Simulation chamber investigation of the reactions of ozone with short-chained alkenes  

Microsoft Academic Search

Reaction rate coefficients and product yields in the gas phase reaction of O3 with the short-chained alkenes ethene, propene, 1-butene, isobutene, (E)-butene, and (Z)-butene were determined by Simulation of Atmospheric Photochemistry in a Large Reaction Chamber (SAPHIR). In a first set of experiments, reaction rate coefficients were acquired in an absolute reaction rate study from the measured concentration time profiles

Robert Wegener; Theo Brauers; Ralf Koppmann; Sonia Rodríguez Bares; Franz Rohrer; Ralf Tillmann; Andreas Wahner; Armin Hansel; Armin Wisthaler

2007-01-01

244

Simulation chamber investigation of the reactions of ozone with short-chained alkenes  

NASA Astrophysics Data System (ADS)

Reaction rate coefficients and product yields in the gas phase reaction of O3 with the short-chained alkenes ethene, propene, 1-butene, isobutene, (E)-butene, and (Z)-butene were determined by Simulation of Atmospheric Photochemistry in a Large Reaction Chamber (SAPHIR). In a first set of experiments, reaction rate coefficients were acquired in an absolute reaction rate study from the measured concentration time profiles of ozone and the alkenes with side reactions being suppressed by adding a radical scavenger. The rate coefficients obtained agree well with literature data; for all but one alkene, the deviation was less than 10%. In a second set of experiments, OH yields were derived from the additional alkene turnover in the absence of a radical scavenger. In contrast to other studies, the OH yields determined in the dry chamber (propene, 0.10 ± 0.07; 1-butene, 0.00 ± 0.08, isobutene, 0.30 ± 0.14; (Z)-butene, 0.18 ± 0.09; and (E)-butene, 0.70 ± 0.12) differed from the yields obtained under humid conditions (propene, 0.30 ± 0.08; 1-butene, 0.30 ± 0.09; isobutene, 0.80 ± 0.10; (Z)-butene, 0.40 ± 0.05; and (E)-butene, 0.60 ± 0.12). The only exception was ethene ozonolysis, where no OH production was observed. HO2 yields (propene, 1.50 ± 0.75; 1-butene, 1.60 ± 0.80; and isobutene, 2.00 ± 1.00) estimated from the additional ozone turnover compared to the experiments where radicals were not scavenged are reported here for the first time. Furthermore, the yields of the stable ozonolysis products CO, acetaldehyde, and formaldehyde were acquired by monitoring the concentration time profile of the respective compound.

Wegener, Robert; Brauers, Theo; Koppmann, Ralf; RodríGuez Bares, Sonia; Rohrer, Franz; Tillmann, Ralf; Wahner, Andreas; Hansel, Armin; Wisthaler, Armin

2007-07-01

245

Eichinvariante Berechnung des Diamagnetismus und der chemischen Verschiebung  

Microsoft Academic Search

The procedure derived in1–4 was used to calculate the magnetic susceptibilities of a series of unsaturated hydrocarbons (propene, isobutene, 1-butene, cyclohexene, butadiene,trans-1,3,5-hexatriene). The difference d? between the measured and computed susceptibilities of these molecules is discussed. The discussion shows, that there is no correlation existing between the difference d? and the presumed delocalisation effects.

Marianne Nofz; Hans-Georg Bartel; Jens Rainer Lochmann; Werner Haberditzl

1982-01-01

246

Investigation of the ozonolysis of short chained alkenes in the atmosphere simulation chamber SAPHIR  

Microsoft Academic Search

Reaction rate coefficients and product yields in the gas-phase reaction of O3 with the short-chained alkenes ethene, propene, 1-butene, isobutene, (E)-butene, and (Z)-butene were determined in the atmosphere simulation chamber SAPHIR. In a first set of experiments reaction rate coefficients were acquired in an absolute reaction rate study from the measured concentration-time profiles of ozone and the alkenes with side

R. Wegener; T. Brauers; A. Hofzumahaus; F. Holland; R. Koppmann; S. Rodríguez Bares; F. Rohrer; L. Rupp; R. Tillmann; A. Wahner; A. Hansel; A. Wisthaler

2006-01-01

247

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

Microsoft Academic Search

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

V. Vandepitte; W. Verstraete

1995-01-01

248

Effects of chlorine and chlorine dynamics during silver-catalyzed epoxidation of butadiene  

Microsoft Academic Search

Silver catalysts that have been modified by Cl addition are more stable with respect to thermal runaway during reaction and exhibit higher activity and selectivity for formation of 3,4-epoxy-1-butene. The Cl effect for activity enhancement is most likely electronic in nature and involves subsurface Cl, although a similar role for surface Cl cannot be excluded. Selectivity enhancement and thermal stability

John R. Monnier; Jerome L. Stavinoha; Gary W. Hartley

2004-01-01

249

Isomorphous substitution in ZSM-22 zeolite. The role of zeolite acidity and crystal size during the skeletal isomerization of n-butene  

Microsoft Academic Search

The influence of acid-site density, acid strength and crystal size on the skeletal isomerization of 1-butene using Al-, Ga-, and Fe-ZSM-22 zeolites with different Si\\/T ratios has been investigated. The highest isobutene selectivity (90% selectivity at 40% conversion) was found with the Fe-ZSM-22 which has milder acid sites. The fact that some iron comes out from the zeolite framework during

M. A Asensi; A Corma; A Mart??nez; M Derewinski; J Krysciak; S. S Tamhankar

1998-01-01

250

Hydrogenative regeneration of a Pt\\/LaY zeolite catalyst deactivated in the isobutane\\/ n-butene alkylation  

Microsoft Academic Search

The formation of carbonaceous deposits during the alkylation of isobutane with 1-butene was investigated on a La-Y zeolite catalyst loaded with 0.4wt.% of platinum in a continuous-flow stirred tank reactor at 75°C in the liquid phase. By combined elemental analysis and UV–vis spectroscopy, the amount and the nature of the coke deposits were found to change significantly with time-on-stream. Olefins

Raoul Klingmann; Rouven Josl; Yvonne Traa; Roger Gläser; Jens Weitkamp

2005-01-01

251

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

ERIC Educational Resources Information Center

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

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

2010-01-01

252

Comparative study of the catalytic properties of ferrierite zeolite exchanged with alkaline earth metals in the skeletal isomerization of n -butene  

Microsoft Academic Search

Ferrierite zeolites ion exchanged with alkaline earth cations (Mg2+, Sr2+, Ba2+) were prepared and examined as catalysts for the skeletal isomerization of 1-butene. The samples were characterized by XRD,\\u000a atomic absorption spectroscopy, ammonia TPD, FT-IR, BET\\/pore size distribution and pyridine chemisorption. The acidity studies\\u000a indicated that acid strength increases in the order H+>Mg2+>Sr2+>Ba2+, therefore, the number of weak acid sites

P. Cañizares; A. Carrero

2000-01-01

253

Reaction probe study of the dual surface structure of graphite-supported Fe-Rh catalysts  

Microsoft Academic Search

As part of a continuing effort to characterize the structure of base-metal noble-metal bimetallic catalyst particles the catalytic chemistry of graphite-supported iron-rhodium particles was tested after two different pretreatments. Specifically, the activity of the catalyst for 1-butene isomerization\\/hydrogenation was tested after oxidation and (1) low-temperature (375 K) hydrogen reduction and (2) high-temperature (675 K) reduction. It was found that the

H. Durr; J. Phillips

1990-01-01

254

Thin palladium membrane microreactors with oxidized porous silicon support and their application  

NASA Astrophysics Data System (ADS)

We microfabricated a MEMS (micro electro mechanical system)-based thin palladium (Pd) membrane microreactor with oxidized porous silicon (PS) support. The membranes were characterized by permeation experiments with hydrogen, nitrogen and helium at temperatures ranging from 200 °C to 250 °C. The hydrogen flux through the Pd membrane with a thickness of 340 nm was 0.112 mol m-2 s-1 at 250 °C and a partial pressure difference of 212 kPa. H2/N2 and H2/He selectivity was about 44 and 10 at 250 °C, respectively. The thermal isolation of the Pd membrane, which was heated by an integrated microheater, was realized by using the oxidized PS ring. We also carried out the hydrogenation of 1-butene at 250 °C using the developed microreactor. The conversion of 1-butene of 100% was obtained at low flow rate of 1-butene. The results show that microreactors have a potential to be used in hydrogen purification and hydrogenation.

Ye, Shu-Ying; Tanaka, Shuji; Esashi, Masayoshi; Hamakawa, Satoshi; Hanaoka, Takaaki; Mizukami, Fujio

2005-11-01

255

FTIR studies of reactions between the nitrate radical and chlorinated butenes  

SciTech Connect

The products formed in the reactions between the nitrate radical and 2-chloro-1-butene, 3-chloro-1-butene, 1-chloro-2-butene, and 2-chloro-2-butene were studied by FTIR spectroscopy. The experiments were performed in synthetic air in a glass/Teflon reactor and using N{sub 2}O{sub 5} as the NO{sub 3} source. The principal products formed with chlorobutenes, where the chlorine atom was substituted at a carbon participating in the double bond, were acid chlorides, aldehydes, and NO{sub 2}. The products formed from chlorobutenes with the chlorine atom substituted at a carbon next to the double bond were aldehydes, chlorinated carbonyl nitrate compounds, and NO{sub 2}. The reaction rate constant for the initial reaction step for 2-chloro-1-butene was determined to be 1.73 ({plus minus} 0.31) {times} 10{sup {minus}14} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1} at 299 K by using a fast-flow system.

Waengberg, I.; Ljungstroem, E. (Univ. of Goeteborg and Chalmers Univ. of Technology (Sweden)); Hjorth, J.; Ottobrini, G. (Commission of the European Communities Joint Research Center, Ispra (Italy))

1990-10-18

256

Studies of acidic sites on boralities by temperature-programmed desorption (TPD) of NH[sub 3], C[sub 2]H[sub 4], and 1-C[sub 4]H[sub 8  

SciTech Connect

The acidity of [Al]-ZSM-5 is considerably strong leading to isomerization, dimerization, cracking, and coking reactions that may take place concurrently. Fine-tuning the acidity of ZSM-5 by incorporating boron into the zeolite framework is a goal of this research. From the position of boron in the periodic table, it would be expected that the substitution of aluminum with boron in the framework of pentasil zeolites would weaken the acidic strength of the zeolites. Ammonia, 1-butene, and ethylene have been used as probe molecules to study the acidic sites of zeolites. These results show that three types of acidic sites are present on boron-containing zeolites, i.e., one inactive for reactions of 1-butene, another active for dimerization of 1-butene, and a final one responsible for isomerization of butene. Framework aluminum plays an important role in adsorption of butene or ethylene molecules on boron/aluminium ZSM-5. Butene or ethylene adsorption appears to be nonlinear with the number of acidic sites, and aluminum appears to activate the adsorption of butene or ethylene on boron acidic sites. 20 refs., 10 figs., 5 tabs.

Xu, Wen-Qing; Suib, S.L.; O'Young, Chi-Lin (Univ. of Connecticut, Storrs, CT (United States))

1993-11-01

257

Adsorption and reaction of 1,3-butadiene on Pt(1 1 1) and Sn/Pt(1 1 1) surface alloys  

NASA Astrophysics Data System (ADS)

Temperature-programmed desorption (TPD), Auger electron spectroscopy (AES), and low-energy electron diffraction (LEED) were used to study the chemistry of 1,3-butadiene (H 2C dbnd CHCH dbnd CH 2, C 4H 6) on Pt(1 1 1) and p(2 × 2)-Sn/Pt(1 1 1) and (?3 × ?3)R30°-Sn/Pt(1 1 1) surface alloys. All chemisorbed 1,3-butadiene completely dehydrogenated to H 2 and surface carbon on Pt(1 1 1). Alloying Sn on Pt(1 1 1) can completely inhibit this decomposition and 1,3-butadiene reversibly adsorbs and desorbs from the two Sn/Pt(1 1 1) alloys under UHV conditions. The desorption activation energy of 1,3-butadiene on the (2 × 2) and (?3 × ?3)R30°-Sn/Pt(1 1 1) surface alloys is 88 and 75 kJ/mol, respectively. These values are good estimates of the adsorption energies, and also place lower limits on the activation energy barrier for dissociating vinylic C-H bonds on the (2 × 2) and ?3 surface alloys. Even though 1,3-butadiene is much more strongly chemisorbed than 1-butene (H 2C dbnd CHCH 2CH 3, C 4H 8) on the (2 × 2)-Sn/Pt(1 1 1) alloy, 1,3-butadiene is less reactive than 1-butene because there are no allylic ?-CH bonds in 1,3-butadiene as there are in 1-butene.

Zhao, Haibo; Koel, Bruce E.

2004-11-01

258

OH yields in the gas-phase reactions of ozone with alkenes  

SciTech Connect

Hydroxyl radical yields are reported for the gas-phase ozonolyses of a range of alkenes. 1,3,5-Trimethylbenzene was employed as an OH tracer, and the diminution in its concentration was used to calculate OH yields by both a simple analytical kinetic expression and a numerically integrated model. The following OH yields were obtained, relative to alkene consumed: ethene (0.14), propene (0.32), 2-methylpropene (0.60), 2,3-dimethyl-2-butene (0.89), isoprene (0.44), {beta}-pinene (0.24), and {alpha}-pinene (0.83). A structure activity relationship (SAR) is presented for the estimation of OH yields based on structural moieties and reaction branching ratios. Reaction stoichiometries ({Delta}[alkene]/{Delta}[ozone]) are also reported, along with primary carbonyl yields measured in the presence and absence of excess SO{sub 2}, both under OH-free conditions. Reaction stoichiometries are shown to be correlated with alkene OH yields, and the mechanistic implications of this observation are discussed. The fractional increase in primary carbonyl yield in the presence of excess SO{sub 2} is shown to be inversely related to the OH yield and is interpreted as a measure of the fraction of the vibrationally excited Criegee intermediate that is stabilized in air at a pressure of 1 atm.

Rickard, A.R.; Johnson, D.; McGill, C.D.; Marston, G.

1999-09-23

259

A study of the unreduced molybdena-alumina system  

SciTech Connect

The isomerization and metathesis of 1-butene was carried out over a series of molybdena-alumina catalysts (1.0-8.2 wt% Mo) prepared by the adsorption equilibrium method. Catalytic conversion measurements (including the effect of preadsorbed water), tracer experiments (1-butene-d[sub o]+1-butene-d[sub 8]), pyridine adsorption followed by IR spectroscopy, and ESR studies were used as tools for the characterization of the solids. The pyridine adsorption experiments showed an increase in the number of acid sites as well as in the acid strength with increasing metal loading. The catalytic measurements showed a related increase in the rate of isomerization as the %Mo is increased. The cis/trans ratios decreased with increasing molybdenum loading, suggesting an increase in the acid strength of the remaining alumina hydroxyl groups. The results suggest a Broensted acid mechanism for the isomerization reaction over catalysts with molybdenum loading [ge] 3.9% Mo. The 1.0% molybdena-alumina catalyst behaved totally different. The results suggest a [pi]-allylic mechanism operative on the unperturbed alumina surface. The rate of formation of ethylene and propylene (products of metathesis) increased dramatically with increasing molybdenum loading. The catalysts evacuated at 500[degrees]C were considerably more active for the metathesis transformations than after evacuation at 500[degrees]C and/or after contacting the catalyst with the olefin. No Mo(V) signal was observed for the 1.0% Mo catalyst. The results suggest that the more easily reducible the catalyst is, the easier it would be to effect olefin metathesis. 35 refs., 4 figs., 6 tabs.

Pantoja, A.; Sarrin, J.; Gonzalez, L.; Noguera, O.; Perez Zurita, M.J.; Galavis, J.L.; Goldwasser, J. (Escuela de Quimica, Caracas (Venezuela))

1993-07-01

260

Effects of SEBS-g-BTAI on the morphology, structure and mechanical properties of PA6\\/SEBS blends  

Microsoft Academic Search

Styrene-b-(ethylene-co-1-butene)-b-styrene (SEBS) triblock copolymer functionalized with ?-caprolactam blocked allyl (3-isocyanate-4-tolyl) carbamate (SEBS-g-BTAI) was used to toughen polyamide 6 (PA6) via reactive blending. Compared to the PA6\\/SEBS blends, mechanical properties such as tensile strength, Young’s modulus, especially Izod notched strength of PA6\\/SEBS-g-BTAI blends were improved distinctly. Both rheological and FTIR results indicated a new copolymer formed by the reaction of end

Ligang Yin; Jinghua Yin; Dean Shi; Shifang Luan

2009-01-01

261

Effects of compressed unsaturated hydrocarbon gases on yeast growth.  

PubMed

The effect of compressed unsaturated hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated by microcalorimetry. The growth thermograms showed that unsaturated hydrocarbon gases inhibited yeast growth. As an approach to determining the comparative toxicity of unsaturated hydrocarbon gases, we determined the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP). On the basis of the IP(50) and MIP values, the inhibitory potency of the gases increased in the order ethylene < propylene < 1-butene. Additionally, scanning electron microscopy showed that cells treated with unsaturated hydrocarbon gases were damaged, including invagination of the cell surface. PMID:20233377

Kawachi, Satoshi; Arao, Toshiaki; Suzuki, Yoshihisa; Tamura, Katsuhiro

2010-02-01

262

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

NASA Astrophysics Data System (ADS)

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

Miyamoto, Daisuke; Ichikuni, Nobuyuki; Shimazu, Shogo

2007-02-01

263

New synthesis of (11Z,13Z)-11,13-hexadecadienal, the female sex pheromone of the navel orangeworm.  

PubMed

(11Z,13Z)-11,13-hexadecadienal, the female sex pheromone of the navel orangeworm (Amyelois transitella), was synthesized from commercially available 10-bromo-1-decanol in a 27% overall yield (8 steps). The synthesis was achieved by using 10-iododecanal, trimethylsilylacetylene and (Z)-1-bromo-1-butene as the key building blocks, employing Sonogashira-Hagihara coupling and Brown's hydroboration-protonolysis as the key reactions. The terminal formyl group was installed in the earlier stage of the synthesis rather than in the final step. This procedure enabled the multi-gram-scale preparation of this economically important pheromone. PMID:19966474

Mori, Kenji

2009-12-01

264

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

SciTech Connect

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

Miyamoto, Daisuke; Ichikuni, Nobuyuki; Shimazu, Shogo [Department of Applied Chemistry and Biotechnology, Chiba University, Chiba 263-8522 (Japan)

2007-02-02

265

Determining Conformational Preference for Molecules by Electron Momentum Spectroscopy  

NASA Astrophysics Data System (ADS)

Many molecules can rotate internally around one or more bonds so that during 360°'s rotation, they will change between unstable and relative stable conformers. The internal rotation of molecules can lead to much different electron density distributions for certain molecular orbitals (MOs). By comparing the measured electron momentum profiles with the calculated ones, the relative stability of different conformers of 1-butene has been determined, demonstrating that the electron momentum spectroscopy (EMS) is a feasible experimental method to study the conformational preference of molecules.

Chen, Xiangjun; Wu, Fang; Yan, Mi; Shan, Xu; Xu, Kezun

2007-09-01

266

Ultra-fast laser pulses provide an ion source for highly selective mass spectroscopy  

NASA Astrophysics Data System (ADS)

The mass spectra of two isomers of butane, 1-butene and cis-2-butene, interacting with linearly polarized Ti:sapphire laser pulses, were compared. It was demonstrated that the difference between the two spectra are much more pronounced than the corresponding spectra prepared by 100 eV electron ionization ion source. In addition, the difference could be varied by changing the peak laser intensity. The observation suggests potential application of dissociative multiphoton ionization by ultrafast laser pulses as a source for high performance mass spectroscopy.

Mehdi Sharifi, S.; Talebpour, A.; Chin, S. L.

2008-06-01

267

Homo-polymerization of alpha-olefins and co-polymerization of higher alpha-olefins with ethylene in the presence of CpTiCl2(OC6H4X-p)/MAO catalysts (X = CH3, Cl).  

PubMed

Cyclopentadienyl-titanium complexes containing -OC6H4X ligands (X = Cl,CH3) activated with methylaluminoxane (MAO) were used in the homo-polymerization of ethylene, propylene, 1-butene, 1-pentene, 1-butene, and 1-hexene, and also in co-polymerization of ethylene with the alpha-olefins mentioned. The -X substituents exhibit different electron donor-acceptor properties, which is described by Hammett's factor (sigma). The chlorine atom is electron acceptor, while the methyl group is electron donor. These catalysts allow the preparation of polyethylene in a good yield. Propylene in the presence of the catalysts mentioned dimerizes and oligomerizes to trimers and tetramers at 25 degrees C under normal pressure. If the propylene pressure was increased to 7 atmospheres,CpTiCl2(OC6H4CH3)/MAO catalyst at 25 degrees gave mixtures with different contents of propylene dimers, trimers and tetramers. At 70 degrees C we obtained only propylene trimer. Using the catalysts with a -OC(6)H(4)Cl ligand we obtained atactic polymers with M(w) 182,000 g/mol (at 25 degrees C) and 100,000 g/mol (at 70 degrees C). The superior activity of the CpTiCl2(OC6H4Cl)/MAO catalyst used in polymerization of propylene prompted us to check its activity in polymerization of higher alpha-olefins (1-butene, 1-pentene, 1-hexene)and in co-polymerization of these olefins with ethylene. However, when homo-polymerization was carried out in the presence of this catalyst no polymers were obtained. Gas chromatography analysis revealed the presence of dimers. The activity of the CpTiCl2(OC6H4Cl)/MAO catalyst in the co-polymerization of ethylene with higher alpha-olefins is limited by the length of the co-monomer carbon chain. Hence, the highest catalyst activities were observed in co-polymerization of ethylene with propylene (here a lower pressure of the reagents and shorter reaction time were applied to obtain catalytic activity similar to that for other co-monomers). For other co-monomers the activity of the catalyst decreases as follows: propylene >1-butene > 1-pentene > 1-hexene. In the case of co-polymerization of ethylene with propylene, besides an increase in catalytic activity, an increase in the average molecular weight M(w) of the polymer was observed. Other co- monomers used in this study caused a decrease of molecular weight. A significant increase in molecular weight distribution (M(w)/M(n)) evidences a great variety of polymer chains formed during the reaction. PMID:18007336

Skupinski, W; Nicinski, K; Jamanek, D; Wieczorek, Z

2005-01-01

268

Cobalt-catalyzed dimerization of alpha-olefins to give linear alpha-olefin products.  

PubMed

[Cp*P(OMe)3CoCH2CH3]+ [BarF]-, generated by the addition of HBArF to Cp*P(OMe)3Co(ethene), catalyzes the oligomerization of 1-hexene to give dimers and trimers. When a deficit of the acid is used, linear alpha-olefin dimers are produced at the expense of trimeric products: e.g., 1-butene, 1-hexene, and 1-octene give 1-octene, 1-dodecene, and 1-hexadecene, respectively. PMID:16332061

Broene, Richard D; Brookhart, Maurice; Lamanna, William M; Volpe, Anthony F

2005-12-14

269

Catalytic activity of rare-earth itaconates in the dehydrohalogenation of chloroolefins  

SciTech Connect

The most promising method for obtaining chloroprene is the liquid-phase dehydrohalogenation of dichloroolefins. The catalysts for the process include systems of a basic type, particularly oxides and some complex salts of rare earths supported on Al/sub 2/O/sub 3/. In this report the results of an investigation of the dehydrohalogenation of 3,4-dichloro-1-butene in the presence of the protonated itaconates of samarium, gadolinium, and erbium deposited on Al/sub 2/O/sub 3/ from water are presented.

Usov, Y.N.; Chekurovskaya, E.D.; Vaistub, T.G.; Krasovskaya, T.A.

1983-02-01

270

Heat Capacity and Other Thermodynamic Properties of Linear Macromolecules. VII. Other Carbon Backbone Polymers  

Microsoft Academic Search

The heat capacity of poly-1-butene, poly-1-pentene, poly-1-hexene, polyisobutylene, poly(4-methyl-1-pentene), polybutadiene, cis-1, 4-poly(2-methylbutadiene), polycyclopentene, poly(vinyl fluoride), poly(vinylidene fluoride), polytrifluoroethylene, polytetrafluoroethylene, poly(vinyl chloride), poly(vinylidene chloride), polychlorotrifluoroethylene, poly(vinyl alcohol), poly(vinyl acetate), poly(?-methylstyrene), poly(o-methylstyrene), poly(o-chlorostyrene) and a series of poly(vinyl benzoate)s is reviewed on the basis of 62 measurements reported in the literature. A set of recommended data has been derived for each polymer.

Umesh Gaur; Brent B. Wunderlich; Bernhard Wunderlich

1983-01-01

271

Monte Carlo simulations of vapor–liquid–liquid equilibrium of some ternary petrochemical mixtures  

Microsoft Academic Search

The aim of this study was to determine the capability and accuracy of Monte Carlo simulations to predict ternary vapor–liquid–liquid equilibrium (VLLE) for some industrial systems. Hence, Gibbs ensemble Monte Carlo simulations in the isobaric–isothermal (NpT) and isochoric–isothermal (NVT) ensembles were performed to determine vapor–liquid–liquid equilibrium state points for three ternary petrochemical mixtures: methane\\/n-heptane\\/water (1), n-butane\\/1-butene\\/water (2) and n-hexane\\/ethanol\\/water (3).

Suren Moodley; Kim Bolton; Deresh Ramjugernath

2010-01-01

272

Selective oxidation of n-butane to maleic anhydride over model vanadium-phosphorus oxide catalysts  

SciTech Connect

The selective oxidation of n-butane to maleic anhydride was studied using two model vanadium-phosphorus-oxygen catalysts, ..beta..-VOPO/sub 4/ and (VO)/sub 2/P/sub 2/O/sub 7/. Detailed synthesis and characterization of these phases are reported, demonstrating that synthesis of the pure compounds is very sensitive to preparation procedures. New information regarding the reaction pathway is presented with the detection of 1-butene, 2-butenes, and 1,3-butadiene as potential reaction pathway intermediates. 43 references, 42 figures, 18 tables.

Moser, T.P.

1985-03-01

273

Mass spectrometer composition probe for batch cell studies of supercritical fluid phase equilibria  

SciTech Connect

A batch cell coupled with a mass spectrometer (MS) composition probe is demonstrated for the first time for measuring high-pressure fluid-phase equilibria at temperatures up to 200 C and pressures up to 600 bar. Compared to gas chromatography (GC), this MS composition probe requires a much smaller sample that is taken from the cell into the spectrometer. Its application is illustrated for 1-butene + ethylene. The apparatus is also tested on two additional systems, supercritical carbon dioxide + decane and supercritical propane + polyisobutene.

Chen, Sheanjer; Randelman, R.E.; Seldomridge, R.L.; Radosz, M. (Exxon Research and Engineering Co., Annandale, NJ (United States))

1993-04-01

274

Density Fluctuations in Crystallizing Polymers: Fact or Fiction?  

NASA Astrophysics Data System (ADS)

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

Baert, Jimmy; van Puyvelde, Peter

2008-07-01

275

Protonation Sites and Dissociation Mechanisms of t-Butylcarbamates in Tandem Mass Spectrometric Assays for Newborn Screening  

PubMed Central

Structures of tert-butylcarbamate ions in the gas phase and methanol solution were studied for simple secondary and tertiary carbamates as well as for carbamate-containing products and internal standards for lysosomal enzyme assays used in newborn screening of a ?-galactosidase A deficiency (GLA, Fabry disease), mucopolysaccharidosis I (Hurler disease), and mucopolysaccharidosis II (Hunter disease). Protonation of simple t-butylcarbamates can occur at the carbonyl group which is the preferred site in the gas phase. Protonation in methanol solution is more favorable if occurring at the carbamate nitrogen atom. Protonation of more complex t-butylcarbamates occurs at amide and carbamate carbonyl groups, and the ions are stabilized by intramolecular hydrogen bonding which is affected by solvation. Tertiary carbamates containing aminophenol amide groups were calculated to have substantially greater gas-phase basicities than secondary carbamates containing coumarin amide groups. The main diagnostically important ion dissociation by elimination of 2-methylpropene (isobutylene, i-C4H8) and carbon dioxide is shown by experiment and theory to proceed in two steps. Energy-resolved collision-induced dissociation of the Hurler’s disease enzymatic product ion, which is a coumarin-diamine linker-t-butylcarbamate conjugate (3a+), indicated separate energy thresholds for the loss of i-C4H8 and CO2. Computational investigation of the potential energy surface along two presumed reaction pathways indicated kinetic preference for the migration of a t-butyl hydrogen atom to the carbamate carbonyl resulting in the isobutylene loss. The consequent loss of CO2 required further proton migrations that had to overcome energy barriers.

Spacil, Zdenek; Hui, Renjie; Gelb, Michael H.; Turecek, Frantisek

2011-01-01

276

Determination of the adsorption model of alkenes and alcohols on sulfonic copolymer by inverse gas chromatography.  

PubMed

The determination of a number of adsorption sites on sulfonated styrene-divinylbenzene copolymer for alkenes (propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, isobutene, 2-methyl-1-butene, 2-methyl-2-butene, 2-methyl-1-pentene, 2-methyl-2-pentene and 2-methyl-2-hexene) and alcohols (methanol, ethanol and n-propanol, n-butanol, 2-butanol and tert-butanol) was performed by the saturation copolymer with vapors of adsorbate, by removing the excess of adsorbate from copolymer by blowing the inert gas through copolymer bed and by the desorption of adsorbed alcohol in the programmed increase of temperature. The adsorption measurements were performed on sulfonated ion-exchange resin (Amberlyst 15) with different concentrations of the acid group, which means with a varying number of adsorption sites. The following adsorption models for alkenes were suggested: the first in which one molecule of alkene is adsorbed by two sulfonic groups, for linear alcohols, the second in which one sulfonic group can adsorb one molecule of alcohol and for non-linear alcohols the third where one molecule of alcohol is adsorbed by two or more sulfonic groups. PMID:15116927

S?omkiewicz, P M

2004-04-23

277

Preparation of mesoporous alumina particles by spray pyrolysis and application to double bond migration of 2-butene.  

PubMed

The objective of the present study is to investigate the catalytic performance of mesoporous alumina that were prepared via spray pyrolysis for double bond migration from 2-butene to 1-butene. The mesoporous alumina particles were prepared via spray pyrolysis by changing the types of organic surfactants and Al precursors. The texture and acidic properties of mesoporous alumina were analyzed through N2 adsorption, SEM, ammonia-temperature programmed desorption, and FT-IR of adsorbed pyridine. The morphologies and texture properties of the mesoporous alumina were found to have been strongly influenced by the combination of the Al precursor and the structure-directing agents. The mesoporous alumina samples had two kinds of acidic sites: a Lewis acid site and a H-bonded weak acid site. 1-Butene was produced selectively through double bond migration of 2-butene over all of the mesoporous alumina catalysts. The catalyst prepared by using a chloride compound as an aluminium precursor and CTAC as a structure-directing agent showed the highest activity in the double bond migration of 2-butene, which was attributed to its large surface area and an overall high amount of acid sites. PMID:22121707

Song, Ki Chang; Kim, Joo Hyun; Kim, Jin Han; Jung, Kyeong Youl; Park, Young-Kwon; Jeon, Jong-Ki

2011-07-01

278

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

NASA Astrophysics Data System (ADS)

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

Hosier, Ian; Alamo, Rufina

2003-03-01

279

Hydrogenation of 1,3-Butadiene on Platinum Surfaces of DifferentStructures  

SciTech Connect

1,3-butadiene hydrogenation is studied on platinum foil and Pt(111), Pt(100), Pt(755) single-crystal surfaces at 300-375 K. The results are compared with the data of alkene hydrogenation reactions. Similar to the hydrogenation kinetics of butenes, 1,3-butadiene hydrogenation exhibits near zeroth-order dependence on hydrocarbon and near first-order dependence on hydrogen pressure. With the same hydrocarbon (3.5-70 Torr) and hydrogen (14-140 Torr) pressure, the rate of 1,3-butadiene hydrogenation is one order of magnitude lower than for the rates for n-butenes. The hydrogenation products include 1-butene, trans- and cis-2-butene, and n-butane. The reaction selectivity is independent of reactant mixture and platinum surface structure, but changes slightly as a function of reaction temperature. The butene product distribution is determined by surface reaction kinetics. While 1-butene is thermodynamically less stable than trans- and cis-2-butene, it is the major butene product in 1,3-butadiene hydrogenation.

Yoon, Cheonho; Yang, M.X.; Somorjai, G.A.

1997-05-01

280

The effect of hydrocarbon structure and chain length on the low-temperature hydrogenation activity on Ni/Pt(1 1 1) bimetallic surfaces  

NASA Astrophysics Data System (ADS)

The reaction pathways of 1-hexene have been investigated on Ni/Pt(1 1 1) surfaces at different Ni coverages using Temperature Programmed Desorption (TPD) and Auger Electron Spectroscopy (AES). A low-temperature self-hydrogenation pathway to produce hexane is detected at the monolayer Ni coverage at 247 K. In addition to self-hydrogenation, 1-hexene also undergoes dehydrogenation to produce trace amount of hexadiene, dehydro-cyclization to produce benzene, and complete decomposition to produce atomic carbon and hydrogen. The presence of pre-adsorbed hydrogen on the surface increases the production of hexane by a factor of ˜5.5, while causing little change in the other reaction pathways. Furthermore, the reaction pathways of 1-butene, cyclohexene, and benzene were compared on the monolayer Ni/Pt(1 1 1) surface to determine the effect of chain length and molecular structure on the low-temperature hydrogenation pathway. The comparison indicates that the two C 6 alkenes, 1-hexene and cyclohexene, show similar self-hydrogenation activity; in contrast, self-hydrogenation does not occur for 1-butene. The hydrogenation of all three alkenes occurs readily in the presence of pre-adsorbed hydrogen on the monolayer Ni/Pt(1 1 1) surface, while the hydrogenation of benzene does not occur even in the presence of pre-adsorbed hydrogen.

Murillo, Luis E.; Khan, Neetha A.; Chen, Jingguang G.

2005-12-01

281

Investigation of conformational changes of organic molecules sorbed in zeolites by proton magnetic resonance spectroscopy  

NASA Astrophysics Data System (ADS)

An appreciable increase in spectral resolution in the 1H nuclear magnetic resonance (NMR) spectra of small organic molecules adsorbed in well-crystallized zeolites is obtained by the application of the magic angle spinning (MAS) technique, which allows to observe slight changes in the proton chemical shifts and to measure well-resolved two-dimensional (2D) NMR spectra. The behavior of 1-butene adsorbed in NaX zeolite is studied by analyzing proton chemical shifts at various temperatures and measuring intramolecular proton-proton distances by means of 1H NOESY NMR spectroscopy. Drastic changes in the NMR line shape of the protons belonging to the terminal group =CH2 are found at varying temperatures (230-340 K) and pore filling factors (between ~0.05 and 4 molecules per large cavity). There is clear evidence that 1-butene molecules interacting with the exchangeable Na+ cations in NaX zeolites reveal a change in the conformation in comparison to those in the bulk phase.

Michel, Dieter; Pampel, André; Roland, Jörg

2003-11-01

282

Coke formation and its effects on shape selective adsorptive and catalytic properties of ferrierite  

SciTech Connect

Channels or cavities of ferrierite are blocked by carbonaceous deposits (coke) which are formed during butene treatments. The pore blocking inside ferrierite/alumina catalysts affects the yield and selectivity to isobutylene in the catalytic reaction of butene isomerization. Pore size distribution experiments show that the blocking of 10-member ring channels (4.2 x 5.4 A) and 8-member ring channels (3.5 x 4.8 A) of ferrierite by coke reduces the channel size smaller than that of the nitrogen molecule (4.09 A). TPD data show that ammonia uptake for coked samples of different times on stream is decreased from about 62% to 35% of that for the fresh sample. Uptakes for more bulky molecules such as 1-butene (2.99 x 4.71 A) and isobutylene (3.28 x 4.14 A) are severely reduced by coke formation (< 9% of 1-butene and isobutylene uptakes for the fresh sample). About 76.9% of the coke formed after 18 h is deposited inside the micropores (< 10 A) of ferrierite/alumina. Modification of pore shapes through such coke deposition favors reactions involving small molecules, such as butene isomerization to isobutylene. 45 refs., 12 figs., 4 tabs.

Xu, W.Q.; Yin, Y.G.; Suib, S.L. (Univ. of Connecticut, Storrs, CT (United States)); O'Young, C.L. (Texaco Inc., Beacon, NY (United States))

1995-01-12

283

Gas-phase kinetics of hydroxyl radical reactions with alkenes: experiment and theory.  

PubMed

Reactions of the hydroxyl radical with propene and 1-butene are studied experimentally in the gas phase in a continuous supersonic flow reactor over the range 50?T/K?224. OH radicals are produced by pulsed laser photolysis of H(2)O(2) at 266 nm in the supersonic flow and followed by laser-induced fluorescence in the (1, 0) A(2)?(+)?X(2)?(3/2) band at about 282 nm. These reactions are found to exhibit negative temperature dependences over the entire temperature range investigated, varying between (3.1-19.2) and (4.2-28.6)×10(-11) cm(3) molecule(-1) s(-1) for the reactions of OH with propene and 1-butene, respectively. Quantum chemical calculations of the potential energy surfaces are used as the basis for energy- and rotationally resolved Rice-Ramsperger-Kassel-Marcus calculations to determine the rate constants over a range of temperatures and pressures. The negative temperature dependences of the rate constants are explained by competition between complex redissociation and passage to the adducts by using a model with two transition states. The results are compared and contrasted with earlier studies and discussed in terms of their potential relevance to the atmosphere of Saturn. PMID:20839269

Daranlot, Julien; Bergeat, Astrid; Caralp, Françoise; Caubet, Philippe; Costes, Michel; Forst, Wendell; Loison, Jean-Christophe; Hickson, Kevin M

2010-12-17

284

Kinetics of the heterogeneously catalyzed formation of tert-amyl ethyl ether  

SciTech Connect

In this work, the kinetics and equilibrium of the heterogeneously catalyzed liquid-phase formation of tert-amyl ethyl ether (TAEE) were studied. The catalyst used was a commercial sulfonic acid ion-exchange resin (Amberlyst 16W). The experiments were carried out in a continuous stirred-tank reactor, measuring stationary reaction rates. The measured reaction rates were fitted to three kinetic models; homogeneous, Eley-Rideal type, and Langmuir-Hinshelwood type. Of these, the Langmuir-Hinshelwood type model described the experimental results best. This model is based on single-site adsorption of every component, with the surface reaction being the rate-limiting step. The activation energies for the formation of tert-amyl ethyl ether from 2-methyl-1-butene were 90 and from 2-methyl-2-butene 108 kJ/mol. For the isomerization of 2-methyl-1-butene to 2-methyl-2-butene, an activation energy of 82 kJ/mol was obtained.

Linnekoski, J.A.; Krause, A.O. [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Industrial Chemistry] [Helsinki Univ. of Technology, Espoo (Finland). Lab. of Industrial Chemistry; Rihko, L.K. [Neste Oy, Porvoo (Finland). Technology Center] [Neste Oy, Porvoo (Finland). Technology Center

1997-02-01

285

Type II isopentenyl diphosphate isomerase: probing the mechanism with alkyne/allene diphosphate substrate analogues.  

PubMed

Isopentenyl diphosphate isomerase (IDI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the basic five-carbon building blocks of isoprenoid molecules. Two structurally unrelated classes of IDIs are known. Type I IPP isomerase (IDI-1) utilizes a divalent metal in a protonation-deprotonation reaction. In contrast, the type II enzyme (IDI-2) requires reduced flavin, raising the possibility that the reaction catalyzed by IDI-2 involves the net addition or abstraction of a hydrogen atom. As part of our studies of the mechanism of isomerization for IDI-2, we synthesized allene and alkyne substrate analogues for the enzyme. These molecules are predicted to be substantially less reactive toward proton addition than IPP and DMAPP but have similar reactivities toward hydrogen atom addition. This prediction was verified by calculations of gas-phase heats of reaction for addition of a proton and of a hydrogen atom to 1-butyne (3) and 1,2-butadiene (4) to form the 1-buten-2-yl carbocation and radical, respectively, and related affinities for 2-methyl-1-butene (5) and 2-methyl-2-butene (6) using G3MP2B3 and CBS-QB3 protocols. Alkyne 1-OPP and allene 2-OPP were not substrates for Thermus thermophilus IDI-2 or Escherichia coli IDI-1 but instead were competitive inhibitors. The experimental and computational results are consistent with a protonation-deprotonation mechanism for the enzyme-catalyzed isomerization of IPP and DMAPP. PMID:20560533

Sharma, Nagendra K; Pan, Jian-Jung; Poulter, C Dale

2010-07-27

286

Palladium-Mediated Hydrogenation of Unsaturated Hydrocarbons with Hydrogen Gas Released during Anaerobic Cellulose Degradation  

PubMed Central

Among five hydrogenation catalysts, palladium on charcoal was the most reactive one when suspended in anaerobic culture medium, and Lindlar catalyst (Pd on CaCO3) was the most reactive one when suspended in the gas phase of culture tubes. Palladium on charcoal in the culture medium (40 to 200 mg 10 ml?1) completely inhibited growth of Neocallimastix frontalis and partly inhibited Ruminococcus albus. Lindlar catalyst (40 to 200 mg per tube) suspended in a glass pouch above the culture medium did not affect the rate of cellulose degradation or the ratio of fermentation products by these organisms. Acetylene added to tubes containing Lindlar catalyst in pouches, and either of the two organisms in monoculture or coculture with Methanospirillum hungatei, was reduced to ethylene and then ethane, followed by hydrogen production. Similar results were obtained with 1-pentene. Neither acetylene nor 1-pentene affected cellulose degradation but both inhibited methanogenesis. In the presence of Lindlar catalyst and propylene or 1-butene, fermenter-methanogen cocultures continued to produce methane at the same rate as controls and no olefin reduction occurred. Upon addition of bromoethanesulfonic acid, methanogenesis stopped and olefin reduction took place followed by hydrogen evolution. In a gas mixture consisting of propylene, 1-butene, and 1-pentene, the olefins were reduced at rates which decreased with increasing molecular size. These results demonstrate the technical feasibility of combining in one reactor the volatile fatty acid production by anaerobic digestion with chemical catalyst-mediated reductions, using the valuable by-product hydrogen.

Mountfort, Douglas O.; Kaspar, Heinrich F.

1986-01-01

287

Catalytic activity of zirconium phosphate and some derived phases in the dehydration of alcohols and isomerization of butenes  

SciTech Connect

The catalytic activity of ..cap alpha..-Zr(HPO/sub 4/)/sub 2/ x H/sub 2/O prepared by different methods and of phases derived from it by heating between 200 and 1100/sup 0/C or by ion exchange with Na/sup +/, Cs/sup +/, or Ag/sup +/, has been investigated by means of different acid-catalyzed test reactions, namely, isopropanol, 1- or 2-butanol dehydration, and 1-butene isomerization. The active centers of both Zr(HPO/sub 4/)/sub 2/ and ZrP/sub 2/O/sub 7/ phases are mainly the surface Broensted sites, as indicated by the strong decrease or annihilation of their catalytic activity after surface Cs/sup +/ poisoning. An explanation of the low residual activity detected for same samples is given. As deduced from the products of 1-butene isomerization, the acidic sites are generally of medium strength. However, on heating between 350 and 700/sup 0/C, when partial or total condensation of hydrogen phosphate to P-O-P groups occurs (with progressive formation of the layered pyrophosphate phase) they transform into sites of medium-high strength.

La Ginestra, A.; Patrono, P.; Berardelli, M.L.; Galli, P.; Ferragina, C.; Massucci, M.A.

1987-02-01

288

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

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

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

289

Near-threshold absolute photoionization cross-sections of some reaction intermediates in combustion  

NASA Astrophysics Data System (ADS)

The use of photoionization mass spectrometry for the development of quantitative kinetic models for the complex combustion chemistry of both conventional hydrocarbon fuels and oxygenated biofuels requires near-threshold measurements of absolute photoionization cross-sections for numerous reaction intermediates. Near-threshold absolute cross-sections for molecular and dissociative photoionization for 20 stable reaction intermediates (methane, ethane, propane, n-butane, cyclopropane, methylcyclopentane, 1-butene, cis-2-butene, isobutene, 1-pentene, cyclohexene, 3,3-dimethyl-1-butene, 1,3-hexadiene, 1,3-cyclohexadiene, methyl acetate, ethyl acetate, tetrahydrofuran, propanal, 1-butyne, 2-butyne) are presented. Previously measured total photoionization cross-sections for 9 of these molecules are in good agreement with the present results. The measurements are performed with photoionization mass spectrometry (PIMS) using a monochromated VUV synchrotron light source with an energy resolution of 40 meV (fwhm) comparable to that used for flame-sampling molecular beam PIMS studies of flame chemistry and reaction kinetics.

Wang, Juan; Yang, Bin; Cool, Terrill A.; Hansen, Nils; Kasper, Tina

2008-02-01

290

Kinetic model for the etherification of isoamylenes with methanol  

SciTech Connect

The kinetics of the formation of tert-amyl methyl ether (TAME; 2-methoxy-2-methylbutane) was investigated in a batch reactor, using a commercial ion-exchange resin (Amberlyst 16) as catalyst. The effect of the methanol/isoamylene ratio on the etherification rate was measured at temperatures between 333 and 353 K. The initial rates of isomerization of 2-methyl-1-butene to 2-methyl-2-butene and the etherification of 2-methyl-1-butene to TAME were measured in the absence of 2-methyl-2-butene in the feed. The initial rate of etherification was found to be 2.3--2.7 times that of isomerization. The experimental results were best described by kinetic equations, which were based on a mechanism where the alcohol and the ether adsorbed on the catalyst surface and the isoamylenes reacted from the bulk liquid phase. The kinetic equations were written in terms of activities, using the UNIQUAC method for activity coefficient calculation. The activation energy was determined to be 81.6 kJ/mol for the isomerization and 72.6 kJ/mol for the etherification of 2M1B to TAME and 94.1 kJ/mol for the etherification of 2M2B. The experimental results were in good agreement with the results simulated by the proposed model.

Rihko, L.K. [Neste Oy, Porvoo (Finland)] [Neste Oy, Porvoo (Finland); Kiviranta-Paeaekkoenen, P.K.; Krause, A.O.I. [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Chemical Engineering] [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Chemical Engineering

1997-03-01

291

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

SciTech Connect

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

Wenig, R.W.

1987-06-01

292

Type II Isopentenyl Diphosphate Isomerase: Probing the Mechanism with Alkyne/Allene Diphosphate Substrate Analogues†  

PubMed Central

Isopentenyl diphosphate isomerase (IDI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the basic five-carbon building blocks of isoprenoid molecules. Two structurally unrelated classes of IDI are known. Type I IPP isomerase (IDI-1) utilizes a divalent metal in a protonation-deprotonation reaction. In contrast, the type II enzyme (IDI-2) requires reduced flavin, raising the possibility that the reaction catalyzed by IDI-2 involves the net addition/abstraction of a hydrogen atom. As part of our studies of the mechanism of isomerization for IDI-2, we synthesized allene and alkyne substrate analogues for the enzyme. These molecules are predicted to be substantially less reactive toward proton addition than IPP and DMAPP, but have similar reactivities toward hydrogen atom addition. This prediction was verified by calculations of gas phase heats of reaction for addition of a proton and of a hydrogen atom to 1-butyne (3) and 1,2-butadiene (4) to form the 1-buten-2-yl carbocation and radical, respectively, and related affinities for 2-methyl-1-butene (5) and 2-methyl-2-butene (6) using G3MP2B3 and CBS-QB3 protocols. Alkyne 1-OPP and allene 2-OPP were not substrates for Thermus thermophilus IDI-2 or Escherichia coli IDI-1, but instead were competitive inhibitors. The experimental and computational results are consistent with a protonation-deprotonation mechanism for the enzyme-catalyzed isomerization of IPP and DMAPP.

Sharma, Nagendra K.; Pan, Jian-Jung; Poulter, C. Dale

2010-01-01

293

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

294

Corona discharge of Titan's troposphere.  

PubMed

The atmosphere of Titan is constantly bombarded by galactic cosmic rays and Saturnian magnetospheric electrons causing the formation of free electrons and primary ions, which are then stabilized by ion cluster formation and charging of aerosols. These charged particles accumulate in drops in cloud regions of the troposphere. Their abundance can substantially increase by friction, fragmentation or collisions during convective activity. Charge separation occurs with help of convection and gravitational settling leading to development of electric fields within the cloud and between the cloud and the ground. Neutralization of these charge particles leads to corona discharges which are characterized by low current densities. These electric discharges could induce a number of chemical reactions in the troposphere and hence it is of interest to explore such effects. We have therefore, experimentally studied the corona discharge of a simulated Titan's atmosphere (10% methane and 2% argon in nitrogen) at 500 Torr and 298 K by GC-FTIR-MS techniques. The main products have been identified as hydrocarbons (ethane, ethyne, ethene, propane, propene + propyne, cyclopropane, butane, 2-methylpropane, 2-methylpropene, n-butene, 2-butene, 2,2-dimethylpropane, 2-methylbutane, 2-methylbutene, n-pentane, 2,2-dimethylbutane, 2-methylpentane, 3-methylpentane, n-hexane, 2,2-dimethylhexane, 2,2-dimethylpentane, 2,2,3-trimethylbutane, 2,3-dimethylpentane and n-heptane), nitriles (hydrogen cyanide, cyanogen, ethanenitrile, propanenitrile, 2-methylpropanenitrile and butanenitrile) and an uncharacterized film deposit. We present their trends of formation as a function of discharge time in an ample interval and have derived their initial yields of formation. These results clearly demonstrate that a complex organic chemistry can be initiated by corona processes in the lower atmosphere. Although photochemistry and charged particle chemistry occurring in the stratosphere can account for many of the observed hydrocarbon species in Titan, the predicted abundance of ethene is to low by a factor of 10 to 40. While some ethene will be produced by charged-particle chemistry, its production by corona processes and subsequent diffusion into the stratosphere appears to be an adequate source. Because little UV penetrates to the lower atmosphere to destroy the molecules formed there, the corona-produced species may be long-lived and contribute significantly to the composition of the lower atmosphere and surface. PMID:11541341

Navarro-Gonzalez, R; Ramirez, S I

1997-01-01

295

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

NASA Astrophysics Data System (ADS)

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.

Santiso, Erik E.; Buongiorno Nardelli, Marco; Gubbins, Keith E.

2008-01-01

296

Tetrahydrothiophene desulfurization on Co-Mo/. gamma. -Al sub 2 O sub 3 : A temporal analysis of products (TAP) investigation  

SciTech Connect

The catalytic reactions of tetrahydrothiophene, thiophene, 1-butene, 1,3-butadiene, and n-butane with hydrogen were studied at low pressure over a commercial cobalt molybdate catalyst. The formation sequence of tetrahydrothiophene desulfurization products was monitored with submilli-second time resolution using the temporal analysis of products (TAP) transient microreactor technique. The TAP experiments showed that butene and were the only hydrocarbon desulfurization products formed, although rapid dehydrogenation to thiophene was also observed. The exceptional time resolution of the TAP spectrometer provided evidence that the butene formed could not be accounted for by a mechanism involving butadiene hydrogenation. The results suggested a desulfurization mechanism for tetrahydrothiophene wherein C{sub 4} hydrocarbon formation proceeds via a surface butene thiolate intermediate produced by a single {beta}-hydride elimination of the intermediate, while rapid C-S bond hydrogenolysis involving surface hydrogen is responsible for butene formation.

Moser, W.R.; Rossetti, G.A. Jr. (Worcester Polytechnic Institute, MA (USA)); Gleaves, J.T.; Ebner, J.R. (Monsanto Chemical Co., St. Louis, MO (USA))

1991-01-01

297

Modeling alkene chemistry using condensed mechanisms for conditions relevant to southeast Texas, USA  

NASA Astrophysics Data System (ADS)

Alkenes are important in photochemical smog formation in southeast Texas due to their high emissions, especially from industrial sources in and around Houston, and their high reactivities. Therefore, properly characterizing the chemistry of alkenes in condensed mechanisms used in regional photochemical models is important in understanding the formation of ozone and other photochemical air pollutants in Houston. The performance of three versions of the SAPRC condensed chemical mechanism family, for predicting ozone and radical formation, was compared. Simulations were compared to environmental chamber data and ambient data. The analyses showed that separately modeling individual alkenes reactions (especially propene for southeast Texas) has the potential to lead to more accurate simulations of alkene chemistry. Caution must be exercised in un-lumping, however. Testing with different formulations of the 1-butene + O 3 reaction demonstrated the complexity and interconnectedness in choices of stoichiometric parameters for un-lumped species and the extent to which lumped mechanisms are un-lumped.

Heo, Gookyoung; Kimura, Yosuke; McDonald-Buller, Elena; Carter, William P. L.; Yarwood, Greg; Allen, David T.

2010-12-01

298

A DFT study on the double bond migration of butene catalyzed by ionic pair of 1-ethyl-3-methyl-imidazolium fluoride  

NASA Astrophysics Data System (ADS)

The double bond migration of butene catalyzed by 1-ethyl-3-methyl-imidazolium fluoride (EmimF) has been studied using quantum chemical method. The geometries of reactant, transition state and product for the isomerization have been optimized by density functional theory (DFT) at the B3PW91/6-31G(d,p), 6-311++G(d,p) and aug-cc-PVDZ levels. The computed results show that the 4-H atom on imidazole ring of EmimF has a good catalytic activity to the double bond migration of butene and the catalytic reaction of 1-butene to 2-butene is a synergetic and elementary process. The apparent activation energy of isomerization is about 197 kJ/mol.

Pu, Min; Chen, Biao-Hua; Wang, Hai-Xia

2005-07-01

299

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

SciTech Connect

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.)

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

2008-01-01

300

MEMS-based thin palladium membrane microreactors  

NASA Astrophysics Data System (ADS)

We microfabricated a MEMS (Micro Electro Mechanical System) based thin palladium (Pd) membrane microreactor with oxidized porous silicon (PS) support. The membranes were characterized by permeation experiments with hydrogen, nitrogen, and helium at temperature ranging from 200°C to 250°C. The hydrogen flux through the Pd membrane with a thickness of 340 nm was 0.112 mol m -2 s -1 at 250°C and a partial pressure difference of 110 kPa. H II/N II and H II/He selectivity was about 46 and 10 at 250°C, respectively. The thermal isolation of the Pd membrane, which was heated by an integrated microheater, was realized by using the oxidized PS. We also carried out the hydrogenation of 1-butene at 250°C using the developed microreactor. The results of long term test of about three months suggest that Pd membrane microreactor has a potential to be used in practical applications.

Ye, S.-Y.; Tanaka, S.; Esashi, M.; Hamakawa, S.; Hanaoka, T.; Mizukami, F.

2006-01-01

301

Highly efficient dimerization of ethylene by (imido)vanadium complexes containing (2-anilidomethyl)pyridine ligands: notable ligand effect toward activity and selectivity.  

PubMed

(Imido)vanadium(V) complexes containing the (2-anilidomethyl)pyridine ligand, V(NR)Cl(2)[2-ArNCH(2)(C(5)H(4)N)] (R = 1-adamantyl (Ad), cyclohexyl (Cy), phenyl), exhibit remarkably high catalytic activities (e.g. TOF = 2 730 000 h(-1) (758 s(-1)) by V(NAd)Cl(2)[2-(2,6-Me(2)C(6)H(3))NCH(2)(C(5)H(4)N)) for ethylene dimerization in the presence of MAO, affording 1-butene exclusively (selectivity 90.4 to >99%). The steric bulk of the imido ligand plays an important role in the selectivity (polymerization vs dimerization), and the electronic nature directly affects the catalytic activity (activity: R = Ad > Cy > Ph). PMID:20218571

Zhang, Shu; Nomura, Kotohiro

2010-04-01

302

Extraction and Partial Characterization of the Ethylene-Forming Enzyme from Apple Fruit 1  

PubMed Central

Ethylene-forming enzyme (EFE) was isolated from apple (Malus domestica Borkh. cv Golden Delicious) fruit tissue. The enzyme activity in the homogenate is associated with the pellet fraction and can be solubilized with Triton X-100 or polyvinylpolypyrrolidone. The solubilized enzyme system resembles the in vivo system in that it exhibits a low Km (17 micromolar) for its substrate 1-aminocyclopropane-1-carboxylic acid (ACC), is stereospecific toward 2-ethyl-ACC stereoisomers for 1-butene production, and is inhibited by cobalt ions and ?-aminoisobutyric acid. Intact preclimacteric fruits treated with exogenous ethylene showed a marked increase in in vivo EFE activity and this increase was accompanied by a parallel increase in in vitro EFE activity. These results support the notion that the isolated EFE represents the authentic in vivo activity.

Fernandez-Maculet, J. Carlos; Yang, Shang Fa

1992-01-01

303

Ethylene polymerisation and oligomerisation with arene-substituted phenoxy-imine complexes of titanium: investigation of multi-mechanism catalytic behaviour.  

PubMed

A range of unsubstituted (1,2) and 6-substituted (3-5) ortho-phenoxy-imine ligands have been prepared and converted to their silyl ether derivatives (6-10). Reaction of silyl ethers with TiCl(4)(thf)(2) in the case of the unsubstituted species yields bis-ligated complexes while the substituted species react cleanly to yield complexes of the form [Ti(O^NR)Cl(3)(thf)]. In most cases the complexes have been characterised by X-ray crystallography. Testing of the complexes for ethylene oligomerisation and polymerisation has been undertaken employing alkylaluminium co-catalysts (AlEt(3), MAO). In all cases the predominant product formed is polyethylene however careful analysis of the liquid phase reveals a complex process by which 1-butene is most likely formed via Cossee mechanism while 1-hexene results from a metallacyclic process. PMID:23396556

Suttil, James A; McGuinness, David S; Gardiner, Michael G; Evans, Stephen J

2013-03-28

304

Optimization of temperature-time sequences in reaction-regeneration cycles--Application to the isomerization of cis-butene  

SciTech Connect

The isomerization of cis-butene on a silica-alumina catalyst, in successive and uninterrupted reaction-regeneration cycles, in an isothermal integral fixed-bed reactor, has been simulated and experimentally studied. In the program for simulation, the following kinetic equations were used: the main reaction, deactivation, and reactivation. The simultaneous optimization of reaction and regeneration steps, with the aim of maximizing the apparent production rate of 1-butene or trans-butene, has been studied. The reaction was operated following a temperature-time sequence. The regeneration consisted of the combination of a step of stripping treatment with an inert gas and of a step of coke combustion. The results of simulation have been experimentally proven in automated reaction-regeneration equipment, in which the optimum conditions of both steps have been used.

Gayubo, A.G.; Arandes, J.M.; Aguayo, A.T.; Olazar, M.; Bilbao, J. (Univ. del Pais Vasco, Bilbao (Spain). Dept. de Ingenieria Quimica)

1993-11-01

305

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

NASA Astrophysics Data System (ADS)

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

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

2004-02-01

306

Recent Progress in Electron Impact Experiments in Hefei  

NASA Astrophysics Data System (ADS)

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.

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

2009-05-01

307

Precision Polyolefin Structure: Modeling Polyethylene Containing Methyl and Ethyl Branches  

NASA Astrophysics Data System (ADS)

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

Rojas, Giovanni; Wagener, Kenneth B.

308

Fischer-tropsch slurry phase process variations to understand wax formation: Quarterly report for period July 1, 1988 to September 30, 1988  

SciTech Connect

A precipitated iron catalyst without any alkali promoters was studied for 2000 hours on stream in a slurry reactor. Reaction conditions were 230 to 260/degree/C (mostly 260/degree/C), 0.77 to 1.92 MPa, H/sub 2//CO feed ratios of 0.5 to 2.0 and CO + H/sub 2/ conversions of 10% to 65%. A Schulz-Flory carbon number distribution with two chain growth probabilities was required to describe the product. Effects of operating variables on 1-butene/n-butane ratio, methane and oxygenate selectivities, and ..cap alpha../sub 1/ and ..cap alpha../sub 2/ are reported. Kinetic models for secondary reactions of 1-alkenes were developed. Addition of potassium t-butoxide to the reactor substantially shifted both distributions to heavier products. 19 refs., 17 figs., 4 tabs.

Donnelly, T.; Satterfield, C.N.

1988-01-01

309

Enantioselective hydrogenation of olefins with homogeneous Ziegler-Natta catalysts  

SciTech Connect

Styrene, 2-methyl-1-pentene, 2-phenyl-1-butene, and cis- and trans-2-hexene have been hydrogenated in the presence of catalysts derived from (Al(CH{sub 3})-O){sub n} and (-)-(ethylenebis(4,5,6,7-tetrahydro-1(R)-indenyl))zirconium derivatives. {alpha}-Olefins are readily polymerized with this catalytic system; in the presence of hydrogen, hydrogenated monomers can be obtained depending on the hydrogen pressure. Terminal olefins substituted in the 2- or 3-positions and internal olefins are not polymerized but undergo hydrogenation. Styrene is hydrogenated at 12 turnovers/min at 20 atm of H{sub 2} at 25{degree}C with this catalytic system. The catalytic deuteriation of styrene with ((-)-(EBTHI)ZrX, X = (R)-1,1{prime}-bi-2-naphtholate) 2 yields (-)-(R)-1,2-dideuterioethylbenzene in 93% yield with an optical purity of 65%, indicating that the (Re) enantioface of styrene is deuterated preferentially.

Waymouth, R. (Stanford Univ., CA (USA)); Pino, P. (Swiss Federal Institute of Technology, Zurich (Switzerland))

1990-06-06

310

Copper(I)-homoscorpionate catalysts for the preferential, kinetically controlled cis cyclopropanation of alpha-olefins with ethyl diazoacetate.  

PubMed

In situ prepared copper catalysts Tp(X)Cu (Tp(X) = homoscorpionate) catalyze the olefin cyclopropanation reaction using ethyl diazoacetate as the carbene source. Very high values of both activity and diastereoselectivity toward the cis isomer have been obtained for styrene, alpha-methylstyrene, 1-hexene, 1-octene, vinyl acetate, n-butyl vinyl ether, 2,5-dimethyl-2,4-hexadiene, and 3,3-dimethyl-1-butene. The effect of the temperature in the diastereoselectivity was almost negligible within the range -10 to +30 degrees C. Kinetic studies have allowed us to propose that the homoscorpionate ligand might act in a dihapto form during the catalytic process. This transformation seems to operate under kinetic control, where the formation of the cis isomer would govern the reaction rate. PMID:11829605

Díaz-Requejo, M Mar; Caballero, Ana; Belderraín, Tomás R; Nicasio, M Carmen; Trofimenko, Swiatoslaw; Pérez, Pedro J

2002-02-13

311

CCMR: Quantum Mechanical Studies of Naphthoannulation  

NSDL National Science Digital Library

The reactivity of polycyclic aromatic hydrocarbon has been known to be significant in the development of new methods for synthesizing compounds. The purpose of this project was to investigate the properties that affect the efficiency of the synthesis of naphthalene ring systems. The focus was on determining the possible transition states for the naphthoannulation cyclization. In this study, the naphthoannulation reaction of 1,1Â-(2-ethyl-1-buten-3- ynylidenene)bis-benzene to form [4]-helicene has been investigated using the B3LYP/6-31G* method as implemented in GAUSSIAN 03. Computational chemistry was used to examine the energies, cyclization barriers, and the frequencies of naphthoannulation similar systems.

Nuez, Betsy

2004-08-17

312

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

NASA Astrophysics Data System (ADS)

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

Zabeti, Parham

313

Solid acid catalysts from clays: preparation of mesoporous catalysts by chemical activation of metakaolin under acid conditions.  

PubMed

Natural kaolin was treated at 850 or 950 degrees C in air flow to give respectively the metakaolin samples MK8 and MK9. The obtained materials were successively treated at 90 degrees C with a 1 M solution of H(2)SO(4), for various time lengths. The acid treatment of MK8 was found to give a high surface area microporous material with good catalytic properties related to the high density of acid sites, while MK9 gave an ordered mesoporous material with a low density of acid sites. The materials were characterized by several techniques, X-ray powder diffraction, thermogravimetric analysis, N(2) physisorption, scanning electron microscopy, and temperature-programmed desorption of ammonia. The 1-butene isomerization was used as test reaction to evaluate the acidity of the samples. PMID:17451736

Lenarda, M; Storaro, L; Talon, A; Moretti, E; Riello, P

2007-07-15

314

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

SciTech Connect

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

Santoro, R.J.

1989-02-15

315

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

316

Reactions of free radicals with ? 3-allylpalladium(II) complexes: cyclohexyl radicals  

Microsoft Academic Search

Allyl palladium complexes of the types [(?3-allyl)PdCl]2, (?3-allyl)PdCl(PPh3) and [(?3-allyl)Pd(PPh3)2]Cl (allyl=C3H5, 1-MeC3H4, 2-MeC3H4, 1-PhC3H4, 2-PhC3H4) react with cyclohexyl radicals derived from the visible light photolysis of (c-hex)Co(DMG)2(py). The reactions proceed via initial attack of the free radical at the metal center, followed by ?-hydrogen elimination and subsequent reductive elimination of propene, 1-butene, isobutene, 3-phenylpropene and 2-phenylpropene, respectively. The 3-phenylpropene can

Simon J. Reid; Michael C. Baird

2004-01-01

317

Formation of low K material utilizing process having readily cleaned by-products  

US Patent & Trademark Office Database

Nano-porous low dielectric constant films are deposited utilizing materials having reactive by-products readily removed from a processing chamber by plasma cleaning. In accordance with one embodiment, an oxidizable silicon containing compound is reacted with an oxidizable non-silicon component having thermally labile groups, in a reactive oxygen ambient and in the presence of a plasma. The deposited silicon oxide film is annealed to form dispersed microscopic voids or pores that remain in the nano-porous silicon. Oxidizable non-silicon components with thermally labile groups that leave by-products readily removed from the chamber, include but are not limited to, limonene, carene, cymene, fenchone, vinyl acetate, methyl methacrylate, ethyl vinyl ether, tetrahydrofuran, furan, 2,5 Norbornadiene, cyclopentene, cyclopentene oxide, methyl cyclopentene, 2-cyclopentene-1-one, and 1-butene.

2009-03-10

318

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

DOEpatents

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.

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

2006-10-10

319

Aluminum coordination and active sites on aluminas, Y zeolites and pillared layered silicates  

SciTech Connect

Our work has been deployed in four directions, namely, (1) Study of the distribution of aluminum within three possible kinds of coordination shells: four-fold (IV), five-fold (V), and six-fold (VI), in aluminas and dealuminated zeolites by high-resolution solid state NMR or magic angle NMR. Besides the classical one pulse spectra, nutation spectra have been studied. (2) Study of the electron deficient sites by electron paramagnetic resonance (EPR) of probe molecules on aluminas and decationated zeolites. Electron deficient sites are considered as Lewis sites. (3) Study of the model isomerization reaction 1 butene {yields} 2 cis or trans butene on the aluminas characterized in 1 and 2. (4) Synthesis of a silicate lattice in which silicon has been partially replaced by aluminum. The chosen silicate is that of the zeolite (fibrous) sepiolite. It has been characterized as indicated in 1 and 2.

Fripiat, J.J.

1991-01-01

320

Aluminum coordination and active sites on aluminas, Y zeolites and pillared layered silicates. Progress report, June 1, 1990--January 31, 1992  

SciTech Connect

Our work has been deployed in four directions, namely, (1) Study of the distribution of aluminum within three possible kinds of coordination shells: four-fold (IV), five-fold (V), and six-fold (VI), in aluminas and dealuminated zeolites by high-resolution solid state NMR or magic angle NMR. Besides the classical one pulse spectra, nutation spectra have been studied. (2) Study of the electron deficient sites by electron paramagnetic resonance (EPR) of probe molecules on aluminas and decationated zeolites. Electron deficient sites are considered as Lewis sites. (3) Study of the model isomerization reaction 1 butene {yields} 2 cis or trans butene on the aluminas characterized in 1 and 2. (4) Synthesis of a silicate lattice in which silicon has been partially replaced by aluminum. The chosen silicate is that of the zeolite (fibrous) sepiolite. It has been characterized as indicated in 1 and 2.

Fripiat, J.J.

1991-12-31

321

Aluminum coordination and active sites on aluminas, Y zeolites and pillared layered silicates  

SciTech Connect

This report covers the activity of the laboratory over 15 months, from June 1, 1990 until August 31, 1991. Our work has been deployed in four directions, namely, (1) Study of the distribution of aluminum within three possible kinds of coordination shells: four-fold (4), five-fold(5), and six-fold(6), in aluminas and dealuminated zeolites by high-resolution solid state NMR or MAS NMR. Besides the classical one pulse spectra, nutation spectra have been studied. (2) Study of the electron deficient sites by electron paramagnetic resonance (EPR) of probe molecules on aluminas and decationated zeolites. Electron deficient sites are considered as Lewis sites. (3) Study of the model isomerization reaction 1 butene {yields} 2 cis or trans butene on the aluminas characterized in (1) and (2). (4) Synthesis of a silicate lattice in which silicon has been partially replaced by aluminum. The chosen silicate is that of zeolitic (fibrous) sepiolite.

Fripiat, J.J.

1991-01-01

322

Aluminum coordination and active sites on aluminas, Y zeolites and pillared layered silicates. Progress report, June 1, 1990--August 31, 1991  

SciTech Connect

This report covers the activity of the laboratory over 15 months, from June 1, 1990 until August 31, 1991. Our work has been deployed in four directions, namely, (1) Study of the distribution of aluminum within three possible kinds of coordination shells: four-fold (4), five-fold(5), and six-fold(6), in aluminas and dealuminated zeolites by high-resolution solid state NMR or MAS NMR. Besides the classical one pulse spectra, nutation spectra have been studied. (2) Study of the electron deficient sites by electron paramagnetic resonance (EPR) of probe molecules on aluminas and decationated zeolites. Electron deficient sites are considered as Lewis sites. (3) Study of the model isomerization reaction 1 butene {yields} 2 cis or trans butene on the aluminas characterized in (1) and (2). (4) Synthesis of a silicate lattice in which silicon has been partially replaced by aluminum. The chosen silicate is that of zeolitic (fibrous) sepiolite.

Fripiat, J.J.

1991-12-31

323

Time-resolved gas chromatography applied to submonolayer adsorption. Modeling and experimental approach  

NASA Astrophysics Data System (ADS)

The reversed-flow inverse gas chromatographic method was used to study the local adsorption parameters of the action of five hydrocarbons on one hand, namely, ethane, ethene, ethyne, propene and 1-butene and of ozone, on the other, on two known and widely used oxides, CaO and SiO 2, respectively. Five physicochemical parameters concerning adsorption have been obtained for each of 20 heterogeneous systems studied, namely local adsorption energy, local adsorption isotherm, local monolayer capacity, probability density function for adsorption energies and energies from lateral interactions. Thus, the RF-IGC method is engaged to provide a new pathway for heterogeneous surface characterization, which is the basis of many scientific investigations and technological applications.

Metaxa, E.; Agelakopoulou, T.; Bassiotis, I.; Margariti, S.; Siokos, V.; Roubani-Kalantzopoulou, F.

2007-04-01

324

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

325

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

SciTech Connect

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

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

1980-10-16

326

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

SciTech Connect

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

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

1987-10-22

327

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

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

328

Response surface optimization and identification of isothiocyanates produced from broccoli sprouts.  

PubMed

Isothiocyanates (ITCs) are proved as one of natural anticarcinogenic compounds, which are produced from the decomposition of glucosinolates by myrosinase. The present study optimized the enzymolysis conditions (pH, addition of EDTA and ascorbic acid) for ITCs production from glucosinolates in broccoli sprouts using response surface methodology. ITCs production was clearly enhanced by a suitable pH, addition content of EDTA and ascorbic acid. The optimal enzymolysis conditions were determined to be adding EDTA 0.02 mmol and 0.16 mg ascorbic acid to 4 ml of the homogenized phosphate-citrate buffer solution (pH 4.00). ITCs profiles were identified and seven kinds of individual ITCs were detected, among which sulforaphane accounted the most. Four kinds of individual ITCs including isobutyl isothiocyanate, 4-isothiocyanato-1-butene, 1-isothiocyanato-3-methyl-butane and 1-isothiocyanato-butane are firstly reported in broccoli sprouts. PMID:23870863

Guo, Qianghui; Guo, Liping; Wang, Zhiying; Zhuang, Yan; Gu, Zhenxin

2013-12-01

329

The elimination of water from a conformationally complex alcohol: A computational study of the gas phase dehydration of n-butanol  

NASA Astrophysics Data System (ADS)

Relative stabilities of the 14 conformers of n-butanol were calculated at the CCSD(T)/cc-pVTZ//MP2/6-311G(d,p) level. The three most stable structures found, TGt, TGg and TGg' ( trans (T or t) and gauche (G or g) with respect to the CC-CC, CC-CO and CC-OH dihedral angles, respectively) lie within 0.14 kcal/mol, ? H(0 K), with the TGt being favoured thermodynamically (the ZPVE corrections were found at the MP2 level). The rotational isomerizations to the other conformers were examined, in particular those involved in the elimination of water. The elimination of H 2O from n-butanol involving the formation of the corresponding carbene, 1-butene, methylcyclopropane and cyclobutane, 1,1-, 1,2-, 1,3- and 1,4-elimination, respectively, was systematically investigated. The 1,2-H 2O loss occurring from the TGg' conformer and involving a four-center transition state has been found to be thermodynamically and kinetically the most favoured route. This elimination which leads to the 1-butene olefin isomer is endothermic by 8.25 kcal/mol, ? H(0 K), with an associated activation enthalpy at 0 K of 67.26 kcal/mol at the CCSD(T)/cc-pVTZ//MP2/6-311G(d,p) level (relative to the TGt conformer). The respective CBS-QB3 estimates are 7.84 and 67.88 kcal/mol.

Moc, Jerzy; Simmie, John M.; Curran, Henry J.

2009-06-01

330

Pressure and Temperature Dependence of the Reaction of Vinyl Radical with Alkenes III: Measured Rates and Predicted Product Distributions for Vinyl + Butene  

NASA Astrophysics Data System (ADS)

This work reports experimental and theoretical first-order rate constants for the reaction of vinyl radical with C4H8 alkenes: 1-butene, 2-butene, and isobutene. The experiments are performed over a temperature range of 300 to 700 K at 100 Torr. Vinyl radicals (H2C?CH) were generated by laser photolysis of vinyl iodide (C2H3I) at 266 nm, and time-resolved absorption spectroscopy was used to probe vinyl radicals at 423.2 and 475 nm. Weighted Arrhenius fits to the experimental rate coefficients for 1-butene (k1), 2-butene (k2), and isobutene (k3) yield k1 = (1.3 ± 0.3) × 10-12 cm3 molecules-1 s-1 exp[-(2200 ± 120) K/T]; k2 = (1.7 ± 0.3) × 10-12 cm3 molecules-1 s-1 exp[-(2610 ± 120) K/T]; and k3 = (1.0 ± 0.1) × 10-12 cm3 molecules-1 s-1 exp[-(2130 ± 50) K/T], respectively. C6H11 potential energy surfaces (PESs) for each system were calculated using the G3 method. RRKM/ME simulations were performed for each system to predict pressure-dependent rate coefficients and branching fractions for the major channels. A generic rate rule for vinyl addition to various alkenes is recommended; a similar rate rule for the abstraction of H atoms by vinyl from alkenes is also provided. Some of the vinyl addition reactions exhibit anomalous Evans-Polanyi plots similar to those reported for previous methyl addition reactions.

Goldsmith, C. Franklin; Ismail, Huzeifa; Green, William H.

2009-07-01

331

Temperature-dependent ozonolysis kinetics of selected alkenes in the gas phase: an experimental and structure-activity relationship (SAR) study.  

PubMed

The kinetics of the reactions of ozone with several alkenes have been measured at atmospheric pressure between 217 and 301 K using EXTRA (EXTreme RAnge chamber). This work represents the first kinetic determinations of the system and focuses on the temperature-dependence of alkene ozonolysis, which is an important tropospheric process impacting upon climate and human health, yet few studies have investigated these reactions as a function of temperature. Temperature-dependent rate coefficients have been established for 3,3-dimethyl-1-butene, 2,4,4-trimethyl-1-pentene and 4-methyl-1-pentene at 217-301 K and atmospheric pressure. The derived Arrhenius expressions are as follows: k = (2.68+2.23-1.23) x 10-15 exp[-(16.29 +/- 1.20/RT)], k = (7.31+9.39-4.05) x 10-15 exp[-(15.33 +/- 1.84/RT)] and k = (5.21+2.85-1.85) x 10-15 exp[-(15.66 +/- 0.87/RT)] cm3 molecule-1 s-1 for 3,3-dimethyl-1-butene, 2,4,4-trimethyl-1-pentene and 4-methyl-1-pentene, respectively.A strong linear correlation has been observed between a simple structure-activity relationship (SAR) and the activation energy, Ea, possessing an R2 value of 0.90. However, no significant correlation was observed for the A-factor. Notwithstanding, with accurate predictions of the SAR for Ea and log k298, values for the A-factor can be retrieved, and hence the prediction of k at any temperature. The newly acquired data agree well with the original SAR and suggest that the factors controlling the rate of ozonolysis reaction are captured accurately by the SAR index. PMID:20449384

Leather, Kimberley E; McGillen, Max R; Percival, Carl J

2010-03-28

332

Stereospecific Conversion of 1-Aminocyclopropanecarboxylic Acid to Ethylene by Plant Tissues 1  

PubMed Central

Inasmuch as the molecule of 1-aminocyclopropanecarboxylic acid (ACC) possesses reflective symmetry but lacks rotational symmetry, the two chemically alike methylene groups can be distinguished by a stereospecific enzyme. To determine whether ACC conversion to ethylene by plant tissues proceeds in a stereospecific fashion, the four stereoisomers of 1-amino-2-ethylcyclopropanecarboxylic acid (AEC) were administered to postclimacteric apple (Malus sylvestris Mill., var. Golden Delicious), excised preclimacteric cantaloupe (Cucumis melo L., var. reticulatis Naud cv. PMR-45), and etiolated mung bean (Vigna radiata L., Wilczek, var. Berken) hypocotyls. In each case (1R,2S)-AEC was the preferred substrate yielding 1-butene. In contrast, all AEC isomers were converted equally well to butene by chemical oxidation using NaOCl. Both ACC and AEC appear to be substrates for the same enzyme since both reactions are inhibited in parallel by N2 or Co2+, both reactions are induced in parallel by excision, and when both substrates are present simultaneously each will act as an inhibitor with respect to the other. The aforementioned observations indicate that ACC is stereospecifically converted to ethylene. For AEC to be the most active precursor of 1-butene, the ethyl substituent should be trans to the carboxyl group and the pro-(S) methylene group should be unsubstituted. This observation leads to the suggestion that the enzyme interacts with amino, carboxyl, and pro-(S) methylene groups, a configuration corresponding to a l-amino acid. This view is consistent with the observation that the l-forms of alanine and methionine inhibit the conversion of ACC to ethylene more than the corresponding d-amino acids in the mung bean hypocotyl system.

Hoffman, Neil E.; Yang, Shang Fa; Ichihara, Akitama; Sakamura, Sadao

1982-01-01

333

Binding of molecular oxygen and alkenes to coordinatively unsaturated bipyridinium metal complexes in the gas phase  

NASA Astrophysics Data System (ADS)

Unsaturated metal complexes have vacant sites for binding and may promote insertion reactions. Rate coefficients were determined for the formation of adduct ions in ion-molecule reactions between M(bipy)22+ (M = Cr, Ru, or Os; bipy = bipyridine) and dioxygen, propane, ethene, propene, and 1-butene in the cell of a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Together with estimated capture rate coefficients, these lead to efficiencies for adduct formation. Efficiencies for O2 adduct formation are small, which is indicative of a weak binding between the metal and dioxygen. The efficiency was independent of pressure, and consequently radiative emission must be responsible for cooling of the excited adducts, M(bipy)2(O2)2+*. The efficiency for addition of alkenes to Ru(bipy)22+ is higher. Reactions between Ru(bipy)2(alkene)2+ and alkene were investigated. In the case of ethene, simple addition occurred to give the Ru(bipy)2(ethene)22+ ion. In contrast, reactions with propene and 1-butene produced the ions Ru(bipy)2(C2H3)(alkene)2+ and Ru(bipy)2(C3H5)(alkene)2+ which are indicative of alkene activation. In the ion-molecule reaction between Ru(bipy)22+ and propene, a small abundance of the bis(allyl) complex, Ru(bipy)(allyl)22+, was also observed. The assignment of the products and elucidation of the detailed reaction mechanisms is based on collisional activation and supported by experiments with deuterium-labeled propene.

Nielsen, Steen Brøndsted; Øiestad, Åse Marit L.; Bojesen, Gustav; Uggerud, Einar

2005-06-01

334

Relationships between microstructure and surface acidity of Ti-Si mixed oxide catalysts  

SciTech Connect

The surface acidities and reactivities of titania, silica, and a series of Ti-Si mixed oxides have been investigated with a variety of surface-sensitive techniques, including temperature-programmed desorption/reaction of ammonia and 2-propanol, IR spectroscopy of adsorbed ammonia, and catalytic reaction of 1-butene. Results from TPD, TPR, and IR spectroscopy indicated that total acidity and relative acid strength decreased as silica was incorporated into titania. However, the areal rate of 1-butene isomerization was almost four times greater over a titania-rich mixed oxide than over pure titania. Infrared spectroscopy of adsorbed ammonia revealed that all of the acid sites on pure titania were of the Lewis type, whereas about 80% of the sites on the mixed oxides were of the Broensted type. Therefore, the enhancement of butene isomerization activity over titania-rich mixed oxides was attributed to the Broensted acid sites that were not present on pure titania. The appearance of Broensted acidity in titania-rich mixed oxides was due to the local charge imbalance associated with tetrahedrally coordinated silica chemically mixing with the octahedral titania matrix. In silica-rich mixed oxides, Ti substituted isomorphously for Si in the tetrahedral silica matrix, thus eliminating the local charge imbalance that caused Broensted acidity. The molar ratio of NH{sub 3(ads)}/Ti for a silica-rich mixed oxide was approximately 0.3, which was nearly the same as the fraction of nontetrahedrally coordinated Ti in the sample. 33 refs., 7 figs., 2 tabs.

Liu, Z.; Tabora, J.; Davis, R.J. [Univ. of Virginia, Charlottesville, VA (United States)] [Univ. of Virginia, Charlottesville, VA (United States)

1994-09-01

335

Species and soot concentration measurements in a methane/air nonpremixed flame doped with C4 hydrocarbons  

SciTech Connect

The fuel in a co-flowing methane/air nonpremixed flame was doped with 7400 ppm of 1,3-butadiene, 1-butene, isobutene, and n-butane. Temperature, mole fractions of 24 stable C1 to C12 hydrocarbons, and soot volume fraction were measured along the centerline of the five resulting flames. The additives significantly increased the concentrations of aromatic species and of soot. The specific changes could be reasonably explained by conversion of the additives to aromatic ring precursors, but not by effects of the additives on temperature and H atom concentrations. Isobutene and 1-butene generated the highest concentrations of C4 products. However, several pathways readily interconvert C3 and C4 species, such that increases in both C3 and C4 species were observed for almost every additive. Recombination of propargyl radicals (C{sub 3}H{sub 3}) appears to be responsible for most aromatic ring formation on the centerline of these flames. Reactions of acetylene with n-C{sub 4}H{sub 5} and/or n-C{sub 4}H{sub 3} may also contribute in the 1.3-butadiene-doped flame. Benzene appears to be in partial equilibrium with acetylene in the upper half of the flames. The kinetic processes that establish this equilibrium are most likely ring fragmentation reactions in one direction and acetylene addition to n-C{sub 4}H{sub 3} in the other. The probable source of the n-C{sub 4}H{sub 3} is acetylene addition to C{sub 2}H, with the strong temperature-dependence of C{sub 2}H concentrations responsible for limiting this process to the upper half of the flames. Production of one-ring aromatic species is an important rate-limiting step to soot formation in these flames.

Mcenally, C.S.; Pfefferle, L.D. [Yale Univ., New Haven, CT (United States)] [Yale Univ., New Haven, CT (United States)

1998-10-01

336

Pressure and temperature dependence of the reaction of vinyl radical with alkenes III: measured rates and predicted product distributions for vinyl + butene.  

PubMed

This work reports experimental and theoretical first-order rate constants for the reaction of vinyl radical with C(4)H(8) alkenes: 1-butene, 2-butene, and isobutene. The experiments are performed over a temperature range of 300 to 700 K at 100 Torr. Vinyl radicals (H(2)C horizontal lineCH) were generated by laser photolysis of vinyl iodide (C(2)H(3)I) at 266 nm, and time-resolved absorption spectroscopy was used to probe vinyl radicals at 423.2 and 475 nm. Weighted Arrhenius fits to the experimental rate coefficients for 1-butene (k(1)), 2-butene (k(2)), and isobutene (k(3)) yield k(1) = (1.3 +/- 0.3) x 10(-12) cm(3) molecules(-1) s(-1) exp[-(2200 +/- 120) K/T]; k(2) = (1.7 +/- 0.3) x 10(-12) cm(3) molecules(-1) s(-1) exp[-(2610 +/- 120) K/T]; and k(3) = (1.0 +/- 0.1) x 10(-12) cm(3) molecules(-1) s(-1) exp[-(2130 +/- 50) K/T], respectively. C(6)H(11) potential energy surfaces (PESs) for each system were calculated using the G3 method. RRKM/ME simulations were performed for each system to predict pressure-dependent rate coefficients and branching fractions for the major channels. A generic rate rule for vinyl addition to various alkenes is recommended; a similar rate rule for the abstraction of H atoms by vinyl from alkenes is also provided. Some of the vinyl addition reactions exhibit anomalous Evans-Polanyi plots similar to those reported for previous methyl addition reactions. PMID:19624112

Goldsmith, C Franklin; Ismail, Huzeifa; Green, William H

2009-11-26

337

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

NASA Astrophysics Data System (ADS)

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

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

2005-10-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

339

Inhibitory potency of 4-carbon alkanes and alkenes toward CYP2E1 activity.  

PubMed

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

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

2014-04-01

340

Selective oxidation of C*4* hydrocarbons over (VO)*2*P*2*O*7 catalyst: Nature of the redox mechanism  

SciTech Connect

For selective oxidation of n-butane to maleic anhydride, (VO)[sub 2]P[sub 2]O[sub 7] has been identified as the most active and selective V-P-0 phase. A three stage solid state procedure was used to synthesize a (VO)[sub 2]P[sub 2]O[sub 7] catalyst labeled with [sup 18]O. Spectroscopy, etc. pointed to a highly site-specific [sup 18]O labeling. Anaerobic pulse micro-reactor studies using C[sub 4] hydrocarbons (n-butane, 1-butene) as reactants were conducted with this labeled catalyst. [sup 18]O incorporation into oxygenated products was determined by mass spectrometry. A comparison between the [sup 18]O content of products to those in various catalyst lattice sites allowed to associate specific surface layer reactive sites with the different mechanistic steps in the selective and nonselective pathways. These studies further revealed that n-butane is irreversibly chemisorbed and activated at the vanadyl dimer sites in a highly specific manner. Oxygen insertion at nearby V-O/[sup P]-V sites leads to form a furan-like surface species, which undergoes additional oxygen addition at P-O-V sites forming maleic anhydride. More than one nonselective pathways were evident: either by the direct combustion of n-butane, involving its cracking at V=O sites; or by the consecutive oxidation of the reaction intermediates and maleic anhydride. Reactivity of a site was found to be dependent on the nature of the hydrocarbon feed. Thus, the initial interaction of n-butane was found to be fundamentally different from 1-butene. Quantitative measurements showed that participation of the bulk oxygen is limited, and the redox mechanism is thus limited to a few near surface monolayers.

Kamat, S.N.

1992-09-09

341

Selective oxidation of C*4* hydrocarbons over (VO)*2*P*2*O*7 catalyst: Nature of the redox mechanism  

SciTech Connect

For selective oxidation of n-butane to maleic anhydride, (VO){sub 2}P{sub 2}O{sub 7} has been identified as the most active and selective V-P-0 phase. A three stage solid state procedure was used to synthesize a (VO){sub 2}P{sub 2}O{sub 7} catalyst labeled with {sup 18}O. Spectroscopy, etc. pointed to a highly site-specific {sup 18}O labeling. Anaerobic pulse micro-reactor studies using C{sub 4} hydrocarbons (n-butane, 1-butene) as reactants were conducted with this labeled catalyst. {sup 18}O incorporation into oxygenated products was determined by mass spectrometry. A comparison between the {sup 18}O content of products to those in various catalyst lattice sites allowed to associate specific surface layer reactive sites with the different mechanistic steps in the selective and nonselective pathways. These studies further revealed that n-butane is irreversibly chemisorbed and activated at the vanadyl dimer sites in a highly specific manner. Oxygen insertion at nearby V-O/{sup P}-V sites leads to form a furan-like surface species, which undergoes additional oxygen addition at P-O-V sites forming maleic anhydride. More than one nonselective pathways were evident: either by the direct combustion of n-butane, involving its cracking at V=O sites; or by the consecutive oxidation of the reaction intermediates and maleic anhydride. Reactivity of a site was found to be dependent on the nature of the hydrocarbon feed. Thus, the initial interaction of n-butane was found to be fundamentally different from 1-butene. Quantitative measurements showed that participation of the bulk oxygen is limited, and the redox mechanism is thus limited to a few near surface monolayers.

Kamat, S.N.

1992-09-09

342

Characterization of Dispersed Heteropoly Acid on Mesoporous Zeolite Using Solid-State P-31 NMR Spin-Lattice Relaxation  

SciTech Connect

Dispersion and quantitative characterization of supported catalysts is a grand challenge in catalytic science. In this paper, heteropoly acid H3PW12O40 (HPA) is dispersed on mesoporous zeolite silicalite-1 derived from hydrothermal synthesis using carbon black nanoparticle templates, and the catalytic activity is studied for 1-butene isomerization. The HPAs supported on conventional zeolite and on mesoporous zeolite exhibit very different activities and thus provide good model systems to investigate the structure dependence of the catalytic properties. The HPA on mesoporous silicalite-1 shows enhanced catalytic activity for 1-butene isomerization, while HPA on conventional silicalite-1 exhibits low activity. To elucidate the structural difference, supported HPA catalysts are characterized using a variety of techniques, including 31P magic angle spinning nuclear magnetic resonance, and are shown to contain a range of species on both mesoporous and conventional zeolites. However, contrary to studies reported in the literature, conventional NMR techniques and chemical shifts alone do not provide sufficient information to distinguish the dispersed and aggregated surface species. The dispersed phase and the nondispersed phase can only be unambiguously and quantitatively characterized using spin-lattice relaxation NMR techniques. The HPA supported on mesoporous zeolite contains a fast relaxation component related to the dispersed catalyst, giving a much higher activity, while the HPA supported on conventional zeolite has essentially only the slow relaxation component with very low activity. The results obtained from this work demonstrate that the combination of spinning sideband fitting and spin-lattice relaxation techniques can provide detailed structural information on not only the Keggin structure for HPA but also the degree of dispersion on the support.

Zhu, Kake; Hu, Jian Z.; She, Xiaoyan; Liu, Jun; Nie, Zimin; Wang, Yong; Peden, Charles HF; Kwak, Ja Hun

2009-09-01

343

Characterization of dispersed heteropoly Acid on mesoporous zeolite using solid-state 31P NMR spin-lattice relaxation.  

PubMed

Dispersion and quantitative characterization of supported catalysts is a grand challenge in catalytic science. In this paper, heteropoly acid H(3)PW(12)O(40) (HPA) is dispersed on mesoporous zeolite silicalite-1 derived from hydrothermal synthesis using carbon black nanoparticle templates, and the catalytic activity is studied for 1-butene isomerization. The HPAs supported on conventional zeolite and on mesoporous zeolite exhibit very different activities and thus provide good model systems to investigate the structure dependence of the catalytic properties. The HPA on mesoporous silicalite-1 shows enhanced catalytic activity for 1-butene isomerization, while HPA on conventional silicalite-1 exhibits low activity. To elucidate the structural difference, supported HPA catalysts are characterized using a variety of techniques, including (31)P magic angle spinning nuclear magnetic resonance, and are shown to contain a range of species on both mesoporous and conventional zeolites. However, contrary to studies reported in the literature, conventional NMR techniques and chemical shifts alone do not provide sufficient information to distinguish the dispersed and aggregated surface species. The dispersed phase and the nondispersed phase can only be unambiguously and quantitatively characterized using spin-lattice relaxation NMR techniques. The HPA supported on mesoporous zeolite contains a fast relaxation component related to the dispersed catalyst, giving a much higher activity, while the HPA supported on conventional zeolite has essentially only the slow relaxation component with very low activity. The results obtained from this work demonstrate that the combination of spinning sideband fitting and spin-lattice relaxation techniques can provide detailed structural information on not only the Keggin structure for HPA but also the degree of dispersion on the support. PMID:19601683

Zhu, Kake; Hu, Jianzhi; She, Xiaoyan; Liu, Jun; Nie, Zimin; Wang, Yong; Peden, Charles H F; Kwak, Ja Hun

2009-07-22

344

Pressure dependence and branching ratios in the decomposition of 1-pentyl radicals: shock tube experiments and master equation modeling.  

PubMed

The decomposition and intramolecular H-transfer isomerization reactions of the 1-pentyl radical have been studied at temperatures of 880 to 1055 K and pressures of 80 to 680 kPa using the single pulse shock tube technique and additionally investigated with quantum chemical methods. The 1-pentyl radical was generated by shock heating dilute mixtures of 1-iodopentane and the stable products of its decomposition have been observed by postshock gas chromatographic analysis. Ethene and propene are the main olefin products and account for >97% of the carbon balance from 1-pentyl. Also produced are very small amounts of (E)-2-pentene, (Z)-2-pentene, and 1-butene. The ethene/propene product ratio is pressure dependent and varies from about 3 to 5 over the range of temperatures and pressures studied. Formation of ethene and propene can be related to the concentrations of 1-pentyl and 2-pentyl radicals in the system and the relative rates of five-center intramolecular H-transfer reactions and ? C-C bond scissions. The 3-pentyl radical, formed via a four-center intramolecular H transfer, leads to 1-butene and plays only a very minor role in the system. The observed (E/Z)-2-pentenes can arise from a small amount of beta C-H bond scission in the 2-pentyl radical. The current experimental and computational results are considered in conjunction with relevant literature data from lower temperatures to develop a consistent kinetics model that reproduces the observed branching ratios and pressure effects. The present experimental results provide the first available data on the pressure dependence of the olefin product branching ratio for alkyl radical decomposition at high temperatures and require a value of = (675 ± 100) cm(-1) for the average energy transferred in deactivating collisions in an argon bath gas when an exponential-down model is employed. High pressure rate expressions for the relevant H-transfer reactions and ? bond scissions are derived and a Rice Ramsberger Kassel Marcus/Master Equation (RRKM/ME) analysis has been performed and used to extrapolate the data to temperatures between 700 and 1900 K and pressures of 10 to 1 × 10(5) kPa. PMID:22356429

Awan, Iftikhar A; Burgess, Donald R; Manion, Jeffrey A

2012-03-22

345

Experimental study of the hydrothermal reactivity of organic acids and acid anions: II. Acetic acid, acetate, and valeric acid  

NASA Astrophysics Data System (ADS)

Organic acids and acid anions occur in substantial concentrations in many aqueous geologic fluids and are thought to take part in a variety of geochemical processes ranging from the transport of metals in ore-forming fluids to the formation of natural gas to serving as a metabolic energy source for microbes in subsurface habitats. The widespread occurrence of organic acids and their potential role in diverse geologic processes has led to numerous experimental studies of their thermal stability, yet there remain substantial gaps in our knowledge of the factors that control the rates and reaction pathways for the decomposition of these compounds under geologic conditions. In order to address some of these uncertainties, a series of laboratory experiments were conducted to examine the behavior of organic acids and acid anions under hydrothermal conditions in the presence of minerals. Reported here are results of experiments where aqueous solutions of acetic acid, sodium acetate, or valeric acid ( n-pentanoic acid) were heated at 325°C, 350 bars in the presence of the mineral assemblages hematite + magnetite + pyrite, pyrite + pyrrhotite + magnetite, and hematite + magnetite. The results indicate that aqueous acetic acid and acetate decompose by a combination of two reaction pathways: decarboxylation and oxidation. Both reactions are promoted by minerals, with hematite catalyzing the oxidation reaction while magnetite catalyzes decarboxylation. The oxidation reaction is much faster, so that oxidation dominates the decomposition of acetic acid and acetate when hematite is present. In contrast to previous reports that acetate decomposed more slowly than acetic acid, we found that acetate decomposed at slightly faster rates than the acid in the presence of minerals. Although longer-chain monocarboxylic acids are generally thought to decompose by decarboxylation, valeric acid appeared to decompose primarily by "deformylation" to 1-butene plus formic acid. Subsequent decomposition of 1-butene and formic acid generated a variety of short-chain (?C 4) hydrocarbons and moncarboxylic acids as well as CO 2. Valeric acid decomposition proceeded more rapidly (by a factor of 2) in the presence of hematite-magnetite-pyrite than with the other mineral assemblages, with the greater reaction rate apparently attributable to the effects of fluid chemistry. Valeric acid was observed to decompose at a substantially faster rate than acetic acid under similar conditions. The results suggest that decomposition of aqueous monocarboxylic acids may make a significant contribution to the conversion of petroleum to light hydrocarbons in natural gas and thermal fluids.

McCollom, Thomas M.; Seewald, Jeffrey S.

2003-10-01

346

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

SciTech Connect

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

Moser, T.P.

1987-06-01

347

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

NASA Astrophysics Data System (ADS)

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

Brooke, George M., IV

348

Organic chemistry in the oceans of Titan  

NASA Astrophysics Data System (ADS)

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.

Raulin, F.

349

Interactions in random copolymers  

NASA Astrophysics Data System (ADS)

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

Marinov, Toma; Luettmer-Strathmann, Jutta

2002-04-01

350

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

SciTech Connect

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

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

2004-12-22

351

Molecular products from the thermal degradation of glutamic acid.  

PubMed

The thermal behavior of glutamic acid was investigated in N2 and 4% O2 in N2 under flow reactor conditions at a constant residence time of 0.2 s, within a total pyrolysis time of 3 min at 1 atm. The identification of the main pyrolysis products has been reported. Accordingly, the principal products for pyrolysis in order of decreasing abundance were succinimide, pyrrole, acetonitrile, and 2-pyrrolidone. For oxidative pyrolysis, the main products were succinimide, propiolactone, ethanol, and hydrogen cyanide. Whereas benzene, toluene, and a few low molecular weight hydrocarbons (propene, propane, 1-butene, and 2-butene) were detected during pyrolysis, no polycyclic aromatic hydrocarbons (PAHs) were detected. Oxidative pyrolysis yielded low molecular weight hydrocarbon products in trace amounts. The mechanistic channels describing the formation of the major product succinimide have been explored. The detection of succinimide (major product) and maleimide (minor product) from the thermal decomposition of glutamic acid has been reported for the first time in this study. Toxicological implications of some reaction products (HCN, acetonitrile, and acyrolnitrile), which are believed to form during heat treatment of food, tobacco burning, and drug processing, have been discussed in relation to the thermal degradation of glutamic acid. PMID:23875713

Kibet, Joshua K; Khachatryan, Lavrent; Dellinger, Barry

2013-08-14

352

A cryogen-free refrigerating preconcentration device for the measurement of C2 to C4 hydrocarbons in ambient air.  

PubMed

A cryogen-free refrigerating preconcentration device for the enrichment of trace amounts of highly volatile organic compounds in the atmosphere prior to analysis has been designed and evaluated. The device consists of a microtrap housed in an insulated box, which is cooled by a conventional refrigeration unit. Experimental parameters, including adsorbent mass, trapping temperature, and thermal desorption temperature, were optimized. The on-line coupling of the device to a GC allows sufficient enrichment and separation of C2 to C4 hydrocarbons in less than 40 min without a second cryotrap. The target compounds analysis showed good linearity (correlation coefficients >0.99) and repeatability (relative standard deviation <5%). Detection limits for the 10 volatile organic compounds ranged from 14 ppt to 52 ppt, under the conditions of a 500 mL sampling volume and -10 °C trapping temperature. Real air sample measurements were conducted at an urban site, and five VOCs including ethane, ethene, propane, propene and 1-butene were detected and quantified. PMID:21076785

Peng, Hong; Wang, Jianwei; Shen, Zheng; Wu, Dapeng; Guan, Yafeng

2011-02-01

353

Mechanisms of thiophene hydrodesulfurization on model molybdenum catalysts  

SciTech Connect

Hydrodesulfurization (HDS) activities and selectivities were measured for thiophene, tetrahydrothiophene (THT), and 1-butanethiol on silica-supported molybdenum catalysts at a pressure of 1 atm and temperatures ranging from 530 to 795 K. The model catalysts, which were previously characterized, feature isolated molybdenum atoms in the +2, +4, and +6 oxidation states and molybdenum dimers with each molybdenum atom in the +4 oxidation state. Silica-supported MoS{sub 2} was used for reference. Activities for thiophene and THT HDS correlate with oxidation state. Mo(II) is most active among dispersed catalysts. 1-Butanethiol activities were much larger than thiophene or THT activities and were roughly equal on all dispersed catalysts. Apparent activation energies of 43.4 and 48.5 kJ/mol were determined for thiophene HDS on Mo(II) and MoS{sub 2}/SiO{sub 2}, respectively. Dihydrothiophene, THT and 1-butanethiol were formed in thiophene HDS over Mo(II) and MoS{sub 2}/SiO{sub 2}. The major products of thiophene and THT HDS were 1-butene, 2-butene, and n-butene. Butadiene, i-butane, i-butene, methane, ethane, ethene, propane, and propene were formed in small amounts. Butadiene is thought to be the initial product of thiophene and THT desulfurization and undergoes subsequent hydrogenation and isomerization to yield the observed products. A common mechanism for HDS of thiophene and THT with 2,5-DHT as an intermediate is discussed.

Sullivan, D.L.; Ekerdt, J.G. [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering] [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering

1998-08-15

354

DFT and CASPT2 study on the mechanism of ethylene dimerization over Cr(II)OH+ cation.  

PubMed

In this work, the ethylene coordination and dimerization mechanism over Cr(II)OH(+) cation were systematically investigated using density functional theory (DFT) and complete active space second-order perturbation theory (CASPT2). It was found that Cr(II)OH(+) cation can coordinate with up to four ethylene molecules which gives seven possible stable Cr(II)OH(+)·(C(2)H(4))(n) (n = 1-4) ?-complexes. We investigated whether ethylene dimerization over Cr(II)OH(+) cation proceeds through either a carbene mechanism or a metallacycle mechanism. The potential energy surfaces were characterized using four different functionals (M06L, BLYP, B3LYP, and M06). It was found that the potential energy profiles calculated at the M06 level agreed well with the CASPT2 energy profiles. Since the intermediates involved in the proposed catalytic cycles showed different ground spin states, a reaction pathway involving a spin crossing between two potential energy surfaces was observed. The minimum-energy crossing points (MECPs) that connect the two potential energy surfaces were successfully located. The two-state metallacycle reaction pathway with the formation of chromacyclopentane as the rate-determining step was found to be energetically more favorable than the carbene reaction pathway. 1-Butene was formed from the chromacyclopentane by a two-step reductive elimination pathway through a chromium(IV) hydride intermediate. PMID:21648399

Liu, Zhen; Zhong, Lei; Yang, Yun; Cheng, Ruihua; Liu, Boping

2011-07-21

355

Temperature-programmed desorption investigation of the adsorption and reaction of butene isomers on Pt(111) and ordered Pt-Sn surface alloys  

SciTech Connect

The influence of alloyed Sn on the chemistry of C{sub 4} butene isomers, including 1-butene, cis-2-butene, and isobutene, chemisorbed on Pt(111) was investigated by temperature-programmed desorption (TPD), Auger electron spectroscopy (AES), and low-energy electron diffraction (LEED). Pt-Sn alloy chemistry was probed by investigation of two ordered surface alloys formed when Sn atoms were incorporated within the topmost layer on a Pt(111) substrate. All three butenes undergo decomposition on Pt(111) during TPD which accounts for 50-60% of the chemisorbed monolayer. Alloying Sn into the surface causes a large reduction in the reactivity of the surface, and the fraction of the chemisorbed layer which decomposes is decreased to 3-7% on the (2 x 2) alloy, and no decomposition occurs on the ({radical}3 x {radical}3)R30{degree} alloy. The strong reduction of decomposition on these two surface alloys may be due to the elimination of adjacent pure Pt 3-fold hollow sites. No large changes occur in the coverage of chemisorbed monolayer of butenes in the presence of up to 33% of a monolayer of alloyed Sn, showing that the adsorption ensemble requirement for chemisorption of these alkenes on Pt(111) and the two Sn/Pt(111) alloys is at most a few Pt atoms. 39 refs., 15 figs., 1 tab.

Tsai, Y.L.; Koel, B.E. [Univ. of Southern California, Los Angeles, CA (United States)] [Univ. of Southern California, Los Angeles, CA (United States)

1997-04-10

356

Synthesis of butene-ethylene and hexene-butene-ethylene copolymers from ethylene via tandem action of well-defined homogeneous catalysts  

SciTech Connect

Recent progress in the chemistry of well-defined organometallic catalysts has made a significant impact in the manufacture of polyolefins. An ever-growing menu of metal-ligand combinations exists to control the activity, copolymerization aptitude, and stereoselectivity of the catalytic site. The authors recently reported the use of tandem catalysis to produce branched chain polyethylene from a single feedstock of ethylene. Mixtures of (C{sub 5}H{sub 5}B-OEt){sub 2}ZrCl{sub 2} (1) and [({eta}{sup 5}-C{sub 5}Me{sub 4})SiMe{sub 2}({eta}{sup 1}-NCMe{sub 3})]TiCl{sub 2} (2) produce branched polyethylene from ethylene when activated with methylaluminoxane (MAO). In this process, 1/MAO produces linear 1-alkenes which insert into the growing polyethylene chain at the 2/MAO site. In this paper the authors report how such a tandem catalysis system can be created for the synthesis of poly(ethylene-co-1-butene) or polyethylene with ethyl and butyl branches.

Komon, Z.J.A.; Bu, X.; Bazan, G.C.

2000-03-01

357

[Characteristics of volatile organic compounds during haze episode in Foshan city].  

PubMed

Volatile Organic Compounds (VOCs) in Foshan City were investigated in December 6 to 30 2008. The concentrations of VOCs in haze days were significantly higher than those in no-haze days. Toluene (68.93 microg x m(-3) +/- 37.78 microg x m(-3)) was the most abundant compound of VOCs in haze days and i-pentane (20.59 microg x m(-3) +/- 14.28 microg x m(-3)) was the most abundant compound in no-haze days, respectively. During haze episodes, the diurnal variations of alkanes and alkynes were not significantly; however, alkenes and aromatic hydrocarbon decreased significantly at noon. During no-haze episodes, the diurnal variations patterns of VOCs were stable. Propylene-equivalent concentrations in haze days were significantly higher than those in no-haze days, toluene was the most abundant compound of Propylene-equivalent concentration in haze days, followed by propene and ethene; propene was the most abundant compound in no-haze days, followed by ethene and 1-butene. High concentration of benzene (18.1 microg x m(-3)) in haze days posed a great health threat to public in Foshan city. Both diurnal variation of VOCs and measured ratios indicated vehicular emissions acted as the main sources of most VOCs and other sources like solvent application also contributed to VOCs (benzene and toluene). PMID:22468516

Ma, Yong-Liang; Tan, Ji-Hua; He, Ke-Bin; Cheng, Yuan; Yang, Fu-Mo; Yu, Yong-Chang; Tan, Yun-Hua; Wang, Jie-Wen

2011-12-01

358

Pyrolytic product characteristics of biosludge from the wastewater treatment plant of a petrochemical industry.  

PubMed

Biosludge was produced from the wastewater treatment plant of a petrochemical industry. The element compositions of pyrolytic residues, CO, CO(2), NOx, SOx, total hydrocarbons and detailed volatile organic compounds of pyrolytic gas, and C, H, N, S content and compositions in biofuel were determined in this study. Generally, 75-80% water content in sludge cakes and about 65-70% weight of water vapor and volatile compounds were volatilized during the drying process. Propene, propane, 1-butene, n-butane, isobutene, toluene and benzene were the major volatile organic compounds (VOCs) of the pyrolytic gas, and the concentrations for most of the top 20 VOC species were greater than 5 ppm. C(5)-C(9) compounds contributed 60% by weight of biofuel; 4-hydroxy-4-methyl-2-pentanone was the highest species, accounting for 28-53% of biofuel at various pyrolytic temperatures. Based on the dried residues, there was 8.5-13% weight in pyrolytic residues, 62-82% weight in liquid products (water and crude oil) and 5.8-30% weight in the gas phase after pyrolytic processing at 500-800 degrees C. Finally, 1.5-2.5 wt% liquid fuel was produced after the distillation process. The pyrolytic residues could be reused, the pyrolytic liquid product could be used as a fuel after distillation, and the pyrolytic gas could be recycled in the pyrolytic process to achieve non-toxic discharge and reduce the cost of sludge disposal. PMID:19570608

Lin, Kuo-Hsiung; Hsu, Hui-Tsung; Ko, Ya-Wen; Shieh, Zhu-Xin; Chiang, Hung-Lung

2009-11-15

359

Identification of a tomato gene for the ethylene-forming enzyme by expression in yeast.  

PubMed Central

The ethylene-forming enzyme (EFE), which catalyzes the last step in the biosynthesis of the plant hormone ethylene, has never been purified and no molecular probes are available. Recently, a putative cDNA clone for tomato EFE (pTOM13) has been identified by inhibiting ethylene synthesis with an antisense gene expressed in transgenic plants. A direct test of its function has been made by expression of a pTOM13 gene in Saccharomyces cerevisiae. After cloning artefacts were discovered in the 5' region of the cDNA, a corrected cDNA (pRC13) was created by the fusion of the 5' end of a genomic clone to the 3' end of the cDNA and expressed in S. cerevisiae. Cultures of transformed yeast converted 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene, whereas control cells did not. This EFE activity displays similar characteristics to EFE found in plant tissue: it converts the trans isomer of the ACC analogue 1-amino-2-ethylcyclopropane-1-carboxylic acid to 1-butene in preference to the cis isomer, and it is strongly inhibited by cobaltous ions and 1,10-phenanthroline. Furthermore, information gained from the activity of effectors on yeast EFE activity supports the hypothesis that EFE is one of a group of hydroxylase enzymes. Images

Hamilton, A J; Bouzayen, M; Grierson, D

1991-01-01

360

Selective photooxidation of small alkenes by O[sub 2] with red light in zeolite Y  

SciTech Connect

Upon loading number of UV photons per unit a and O[sub 2] into zeolite NaY, photochemistry was observed at wavelengths as long as 760 nm. Similarly, photoexcitation of trans- or cis-2-butene and O[sub 2] in this zeolite resulted in chemical reaction at a threshold wavelength of 600 nm. Reactions were initiated either with filtered tungsten-source light or the emission of a CW dye laser and typically conducted at -50[degree]C. Products identified by FT-infrared spectroscopy were 2,3-dimethyl-3-hydroperoxy-l-butene (>90%) and acetone in the case of DMB + O[sub 2]. trans- or cis-2-butene + O[sub 2] gave exclusively 3-hydroperoxy-1-butene. This constitutes the first synthesis of this hydroperoxide by direct photolysis of 2-butene-O[sub 2] pairs. Laser reaction excitation spectra in the 500-700-nm region revealed a continuous absorption for both the DMB[center dot]O[sub 2] and the 2-butene-O[sub 2] systems. It is attributed to a charge-transfer transition. Comparison with corresponding absorption spectra in conventional media shows that the excited alkene-O[sub 2] charge-transfer states are stabilized by electrostatic interactions with the zeolite NaY environment by 12 000cm[sup [minus]1]. Substantially less stabilization was observed in high-silica faujasite. 50 refs., 10 figs., 2 tabs.

Blatter, F.; Frei, H. (Lawrence Berkeley Lab., CA (United States))

1994-03-09

361

Reaction of niobium and tantalum neutral clusters with low pressure, unsaturated hydrocarbons in a pickup cell: From dehydrogenation to Met-Car formation  

NASA Astrophysics Data System (ADS)

Neutral niobium and tantalum clusters (Nbn and Tan) are generated by laser ablation and supersonic expansion into a vacuum and are reacted in a pickup cell with various low pressure (~1 mTorr) unsaturated hydrocarbons (acetylene, ethylene, propylene, 1-butene, 1,3-butadiene, benzene, and toluene) under nearly single collision conditions. The bare metal clusters and their reaction products are ionized by a 193 nm laser and detected by a time of flight mass spectrometer. Partially and fully dehydrogenated products are observed for small (n<=m) and large (n>=m) neutral metal clusters, respectively, with m ranging from 2 to 5 depending on the particular hydrocarbon. In addition to primary, single collision products, sequential addition products that are usually fully dehydrogenated are also observed. With toluene used as the reactant gas, carbon loss products are observed, among which Nb8C12 and Ta8C12 are particularly abundant, indicating that the Met-Car molecule M8C12 can be formed from the neutral metal cluster upon two collisions with toluene molecules. The dehydrogenation results for low pressure reactions are compared with those available from previous studies employing flow tube (high pressure) reactors. Low pressure and high pressure cluster ion reactions are also compared with the present neutral metal cluster reactions. Reactions of unsaturated hydrocarbons and metal surfaces are discussed in terms of the present neutral cluster results.

He, S.-G.; Xie, Y.; Dong, F.; Bernstein, E. R.

2006-10-01

362

The influence of overlap interactions on chemical reactions in confinement  

NASA Astrophysics Data System (ADS)

Chemical reactions are often carried out in nano-structured materials due to their large surface area per unit mass. It is, however, difficult to understand fully the role of the nano-structure in many reactions due to the superposition of multiple effects. Such effects include: the reduced dimensionality of the system, the heterogeneity of the pore surfaces, the selective adsorption of reactants/products, catalytic effects, and transport limitations. Experimental studies often show many of these effects at the same time, making the results difficult to interpret. In this work we present results of density functional theory calculations illustrating the influence of overlap interactions (shape-catalytic effects) on chemical reactions. In particular, we show the effect of confinement in small pores on the rates of rotational isomerizations of n-butane, 1-butene and 1,3-butadiene. We find that the rates of these transitions change as the double exponential of the pore size in the molecular sieving limit. These results are a first step towards an integrated model for the design of catalytic materials.

Santiso, Erik E.; Gubbins, Keith E.; George, Aaron M.; Buongiorno Nardelli, Marco

2007-03-01

363

Exploring between the extremes: conversion-dependent kinetics of phosphite-modified hydroformylation catalysis.  

PubMed

The kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a rhodium monophosphite catalyst has been studied in detail. Time-dependent concentration profiles covering the entire olefin conversion range were derived from in situ high-pressure FTIR spectroscopic data for both, pure organic components and catalytic intermediates. These profiles fit to Michaelis-Menten-type kinetics with competitive and uncompetitive side reactions involved. The characteristics found for the influence of the hydrogen concentration verify that the pre-equilibrium towards the catalyst substrate complex is not established. It has been proven experimentally that the hydrogenolysis of the intermediate acyl complex remains rate limiting even at high conversions when the rhodium hydride is the predominant resting state and the reaction is nearly of first order with respect to the olefin. Results from in situ FTIR and high-pressure (HP) NMR spectroscopy and from DFT calculations support the coordination of only one phosphite ligand in the dominating intermediates and a preferred axial position of the phosphite in the electronically saturated, trigonal bipyramidal (tbp)-structured acyl rhodium complex. PMID:22689302

Kubis, Christoph; Selent, Detlef; Sawall, Mathias; Ludwig, Ralf; Neymeyr, Klaus; Baumann, Wolfgang; Franke, Robert; Börner, Armin

2012-07-01

364

The skeletal isomerization of n-butene over ferrierite catalysts  

NASA Astrophysics Data System (ADS)

The catalytic properties of H-ferrierite zeolites, prepared by hydrothermal and dry-state synthesis, were compared in the skeletal isomerization of 1-butene. The activity was found to be strongly influenced by the presence of extra-framework Al (EFAl) species in the zeolite micropores and by the carbonaceous deposit formed during the reaction. The dynamics of mass transport in the zeolite crystallites were studied by the frequency-response (FR) method using acetylene, propane, n- and i-butane as probe molecules. The selectivity of n-butene conversion showed correlation with the dynamics of the n-butane sorption process. Either the diffusion or the sorption was the rate-controlling slowest step of n-butane mass transport, depending on the amount and the distribution of the EFAl species in the sample. In the catalyst sample, free of EFAl, the transport was found to be controlled by the rate of sorption. At an EFAl content of about 0.5-1.0 EFAl/unit cell the diffusion resistance of the micropores governed the n-butane transport rate.

Onyestyák, Gy; Valyon, J.; Pál-Borbély, G.; Rees, L. V. C.

2002-08-01

365

Effect of hydrocarbon chain length and cyclization on the adsorption strength of unsaturated hydrocarbons on Pt/3d bimetallic surfaces  

NASA Astrophysics Data System (ADS)

Pt-based 3d bimetallic surfaces are known to display higher activities and/or selectivities for various important surface reactions. They exhibit properties that can be entirely different from the parent metal surfaces. Various linear and cyclic unsaturated hydrocarbons were examined over a range of Pt bimetallic surfaces in the present work to help understand the influence of the adsorbate structure and the electronic structure of bimetallic surface on their adsorption properties and reactivity. Density functional theory (DFT) calculations were performed to study the binding of these molecules on the 3d-Pt(1 1 1) surface (over-layer structure) and Pt-3d-Pt (subsurface) structure. The effect of hydrocarbon chain length as well as cyclization was also studied on these surfaces. The DFT results for linear alkenes (1-butene, 1-pentene, 1-hexene) showed that the binding energies of these molecules decreased as the d-band centers moved away from the Fermi level, for 3d as well as 5d surfaces. Cyclohexene adsorption and reactivity were also studied using both theory and experiments. Cyclohexene adsorbed in a boat-type configuration and bonded weakly to the surface as compared to 1-hexene. Benzene adsorption was investigated on the bridge as well as the hollow adsorption sites. Benzene bonded more weakly than 1-hexene and cyclohexene on the subsurface Pt-3d-Pt(1 1 1) bimetallic structures.

Goda, A. M.; Neurock, M.; Barteau, M. A.; Chen, J. G.

2008-07-01

366

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

PubMed

Small alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) were used to probe the gas-phase reactivity of doubly charged actinide cations, An(2+) (An = Th, Pa, U, Np, Pu, Am, Cm), by means of Fourier transform ion cyclotron resonance mass spectrometry. Different combinations of doubly and singly charged ions were observed as reaction products, comprising species formed via metal-ion induced eliminations of small molecules, simple adducts and ions resulting from electron, hydride or methide transfer channels. Th(2+), Pa(2+), U(2+) and Np(2+) preferentially yielded doubly charged products of hydrocarbon activation, while Pu(2+), Am(2+) and Cm(2+) reacted mainly through transfer channels. Cm(2+) was also capable of forming doubly charged products with some of the hydrocarbons whereas Pu(2+) and Am(2+) were not, these latter two ions conversely being the only for which adduct formation was observed. The product distributions and the reaction efficiencies are discussed in relation to the electronic configurations of the metal ions, the energetics of the reactions and similar studies previously performed with doubly charged lanthanide and transition metal cations. The conditions for hydrocarbon activation to occur as related to the accessibility of electronic configurations with one or two 5f and/or 6d unpaired electrons are examined and the possible chemical activity of the 5f electrons in these early actinide ions, particularly Pa(2+), is considered. PMID:21850292

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

2011-11-01

367

Characterization of functionalized polyolefins by high-temperature two-dimensional liquid chromatography.  

PubMed

High-temperature two-dimensional liquid chromatography (HT 2D-LC) was developed for the separation and characterization of functional polyolefins. Therefore, the key experimental parameters, namely the injection volume, the mobile phase composition, the flow rate in SEC and the time and phase of sampling into the second dimension, were systematically varied and their influence on the resolution of separation were studied. The HPLC separation of ethylene-vinylacetate waxes was realized using silica gel as stationary phase and a solvent gradient decalin?cyclohexanone, while SEC separations were realized in the chromatographic system polystyrene divinyl benzene column/1,2,4-trichlorobenzene. By choosing suitable experimental parameters, the run time needed for one complete 2D-LC analysis of a polymer sample was shortened from about 200 min to 100 min. However, the developed method failed to adsorb polypropylene and ethylene/1-butene copolymers grafted with 13 or 3 mol.% of methyl methacrylate respectively. Using porous graphite as a stationary phase and a solvent gradient 1-decanol?1,2,4-trichlorobenzene as mobile phase 2D-LC separations of both grafted polyolefins were realized. PMID:23474199

Ginzburg, Anton; Macko, Tibor; Malz, Frank; Schroers, Michael; Troetsch-Schaller, Irene; Strittmatter, Jan; Brüll, Robert

2013-04-12

368

Hydrocarbon source signatures in Houston, Texas: Influence of the petrochemical industry  

NASA Astrophysics Data System (ADS)

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

Jobson, B. T.; Berkowitz, C. M.; Kuster, W. C.; Goldan, P. D.; Williams, E. J.; Fesenfeld, F. C.; Apel, E. C.; Karl, T.; Lonneman, W. A.; Riemer, D.

2004-12-01

369

VOC concentration profiles in an ozone non-attainment area: A case study in an urban and industrial complex metroplex in southern Taiwan  

NASA Astrophysics Data System (ADS)

VOCs are important precursors of the atmospheric ozone formation species. This study investigated the airborne concentrations of 52 VOCs at two air quality monitoring stations, Daliao and Tzouying, during wintertime in southern Taiwan. Airborne VOCs samples were taken in stainless steel canisters four times per day and analyzed via gas chromatography/mass spectrometry. Maximum increment reactivity (MIR) was used to evaluate the ozone formation potential in this ozone non-attainment region. Toluene, propane, isopentane, propene, n-butane, n-pentane and isoprene contributed 78-79% of the 52 VOCs in Daliao. Toluene, 1-butene, isopentane, propene, propane, n-undecane, and n-butane contributed 71-77% of the 52 VOCs in Tzouying. The VOCs concentrations were higher in Daliao due to the high toluene emissions from a paint plant and a solvent plant in the nearby industrial district. The 24-h VOC concentrations averaged 25 ppb higher in Tzouying than in Daliao. The ozone formation potential of airborne VOCs was 1687-2730 and 1717-2261 ?g-O 3/g-VOCs in Daliao and Tzouying, respectively. Ozone concentrations in Tzouying were 44 ppb higher than in Daliao during the 1200-1600 sampling period.

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

370

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

NASA Astrophysics Data System (ADS)

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 n/Ni 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 1Ni 3(1 1 1) surface, di-?-cis and 1,2,3,4-tetra-? adsorption structures are the most stable for non-spin polarized (NSP) and spin polarized (SP) levels of calculation, respectively. Conversely, on Pd 3Ni 1(1 1 1) surface, the 1,2,3,4-tetra-? 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 1Ni 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).

Gómez, Guillermina; Belelli, Patricia G.; Cabeza, Gabriela F.; Castellani, Norberto J.

2010-12-01

371

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

SciTech Connect

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

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

2000-01-25

372

Substrate-induced crystallization of n-paraffins on oriented polyolefins  

NASA Astrophysics Data System (ADS)

n-Paraffins of n-C 20H 42 to n-C 50 H 102 were epitaxially crystallized on oriented polyolefins; polyethylene, polypropylene, poly-1-butene and poly-4-methyl-1-pentene. In most cases, n-paraffin crystals were epitaxially grown on the substrate surface with the (001) basal plane parallel to it, maintaining a two-dimensional lattice coincidence with the polymer substrate. The epitaxial modes with this orientation were classified into the following three types irrespective of the polymers: (1) (001) p?SS, <110> p?FA, (2) (001) p?SS, [010] p?FA, (3) (001) p?SS, <110> p??gaFA , where p, SS and FA denote n-paraffin crystals, substrate surface and fiber axis of the polymers, respectively. The angle ? depends on the kind of polymer substrate. n-Paraffins longer than n-C 40H 82 were laid down in parallel on the polypropylene substrate with their axes at a 46° angle with respect to the substrate fiber axis.

Kawaguchi, Akiyoshi; Okihara, Takumi; Ohara, Masayoshi; Tsuji, Masaki; Katayama, Ken-ichi; Petermann, Jürgen

1989-04-01

373

Ethylene polymerization on a SiH4-modified Phillips catalyst: detection of in situ produced ?-olefins by operando FT-IR spectroscopy.  

PubMed

Ethylene polymerization on a model Cr(II)/SiO(2) Phillips catalyst modified with gas phase SiH(4) leads to a waxy product containing a bimodal MW distribution of ?-olefins (M(w) < 3000 g mol(-1)) and a highly branched polyethylene, LLDPE (M(w) ? 10(5) g mol(-1), T(m) = 123 °C), contrary to the unmodified catalyst which gives a linear and more dense PE, HDPE (M(w) = 86,000 g mol(-1) (PDI = 7), T(m) = 134 °C). Pressure and temperature resolved FT-IR spectroscopy under operando conditions (T = 130-230 K) allows us to detect ?-olefins, and in particular 1-hexene and 1-butene (characteristic IR absorption bands at 3581-3574, 1638 and 1598 cm(-1)) as intermediate species before their incorporation in the polymer chains. The polymerization rate is estimated, using time resolved FT-IR spectroscopy, to be 7 times higher on the SiH(4)-modified Phillips catalyst with respect to the unmodified one. PMID:22231639

Barzan, Caterina; Groppo, Elena; Quadrelli, Elsje Alessandra; Monteil, Vincent; Bordiga, Silvia

2012-02-21

374

Hemiterpene glucosides and other constituents from Spiraea canescens.  

PubMed

Five glycosides, 2-(trans-cinnamoyloxy-methyl)-1-butene-4-O-beta-D-glucopyranoside (1), 4-(6'-O-trans-cinnamoyl)-(2-hydroxymethyl-4-hydroxy-butenyl-beta-D-glucopyranoside (2), 6''-O-trans-p-coumaroyl-(4-hydroxybenzoyl)-beta-D-glucopyranoside (3), 6'-O-(4-methoxy-trans-cinnamoyl) alpha/beta-D-glucopyranose (4) 6'-O-(4''-methoxy-trans-cinnamoyl)-kaempferol-3-beta-D-glucopyranoside (7) along with six known compounds, (+)-isolariciresinol 3a-O-beta-D-glucopyranoside (8) (+)-lyoniresinol 3a-O-beta-D-glucopyranoside (9), apigenin 7-O-beta-D-glucopyranoside (10), quercetin 3-O-beta-D-glucopyranoside (11), 6'-O-cinnamoyl-alpha/beta-D-glucopyranose (6) 6'-O-p-coumaroyl-alpha/beta-D-glucopyranose (5) were isolated from the whole plant of Spiraea canescens. Some of these compounds showed potent radical scavenging activity in relevant non-physiological assays. Their structures were determined by NMR spectroscopic and CID mass spectrometric techniques. PMID:19747701

Choudhary, M Iqbal; Naheed, Nadra; Abbaskhan, Ahmed; Ali, Sajjad; Atta-ur-Rahman

2009-01-01

375

Explanation of Drawability of Semicrystalline Polymers in Terms of ?_c-Relaxation Chain Mobility  

NASA Astrophysics Data System (ADS)

A new explanation of the varying drawability of semicrystalline polymers is presented. It is based on NMR evidence of ?-relaxation-associated helical jumps and chain diffusion through the crystallites of polyethylene (PE) and several similarly " alpha-mobile" polymers, which include isotactic polypropylene (iPP), poly(ethylene oxide) (PEO), poly(oxymethylene) (POM), and poly(tetrafluoroethylene) (PTFE). As an example, our recent direct detection of the 180^o flips of PE chains by two-dimensio nal exchange NMR will be presented. The chain motion provides a mechanism by which these ?-mobile polymers can reorganize their morphology completely when drawn to draw ratios > 30, without melting. A second class of polymers, including nylons, poly(ethylene terephthalate) (PET), isotactic polystyrene (iPS), syndiotactic polypropylene (sPP), and poly(1-butene) in form-I lack a crystalline ?-relaxation and the associated chain mobility. Therefore, these polymers are "locked in" by their crystallites and drawability is limited, arising mostly from deformation of the amorphous regions. The new viewpoint is the first to explain which polymers are drawable to high draw ratios, given a sufficiently low level of entanglements.

Schmidt-Rohr, K.; Hu, W.

1998-03-01

376

Characteristics of atmospheric carbonyls and VOCs in Forest Park in South China.  

PubMed

The diurnal variation of atmospheric carbonyls and VOCs in a forest in south China were studied in summer 2004. Twenty kinds of carbonyls and eight kinds of VOCs were identified and quantified. Formaldehyde and acetaldehyde were the two most abundant carbonyls, while the most abundant VOCs were isoprene, followed by o-xylene. Most C(3)-C(10) carbonyls had higher concentrations from 09:00 to 15:00, and their levels were lower during night-time and often reached the lowest in early morning. Formaldehyde and acetaldehyde, however, showed two high levels in their diurnal patterns partly due to their different sources and sinks. The VOCs had different diurnal patterns compared to most carbonyls. The highest concentrations were observed from 03:00 to 06:00 for 1-butene, from 06:00 to 12:00 for isoprene, and from 12:00 to 15:00 for alpha-pinene. The highest levels for aromatic hydrocarbons occurred during midnight and the lowest in late afternoon. According to the study, emissions from vegetation and photo-oxidation of gas-phase hydrocarbons were the main sources for some carbonyls and VOCs in this region. Other compounds, such as formaldehyde, acetaldehyde and BTEX, showed anthropogenic sources. PMID:17564801

Yu, Yingxin; Wen, Sheng; Lü, Huixiong; Feng, Yanli; Wang, Xinming; Sheng, Guoying; Fu, Jiamo

2008-02-01

377

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

PubMed

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

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

2009-11-15

378

Kinetic and thermodynamic selectivity of intermolecular C-H activation at [Tp'Rh(PMe3)]. How does the ancillary ligand affect the metal-carbon bond strength?  

PubMed

Tp'Rh(PMe3)(CH3)H was synthesized as a precursor to produce the coordinatively unsaturated fragment [Tp'Rh(PMe3)], which reacts with benzene, mesitylene, 3,3-dimethyl-1-butene, 2-methoxy-2-methylpropane, 2-butyne, acetone, pentane, cyclopentane, trifluoroethane, fluoromethane, dimethyl ether, and difluoromethane at ambient temperature to give only one product in almost quantitative yield in each case. All of the complexes Tp'Rh(PMe3)(R)H were characterized by NMR spectroscopy, and their halogenated derivatives were fully characterized by NMR spectroscopy, elemental analysis, and X-ray crystallography. The active species [Tp'Rh(PMe3)] was also able to activate the alkynyl C-H bond of terminal alkynes to give activation products of the type Tp'Rh(PMe3)(C?CR)H (R = t-Bu, SiMe3, hexyl, CF3, Ph, p-MeOC6H4, and p-CF3C6H4). The measured relative rhodium-carbon bond strengths display two linear correlations with the corresponding carbon-hydrogen bond strengths, giving a slope of 1.54 for ?-unsubstituted hydrocarbons and a slope of 1.71 for substrates with ?-substitution. Similar trends of energy correlations were established by DFT calculated metal-carbon bond strengths for the same groups of substrates. PMID:24128081

Jiao, Yunzhe; Morris, James; Brennessel, William W; Jones, William D

2013-10-30

379

Fischer-Tropsch synthesis in slurry-reactor systems. Quarterly report, February 1, 1982-April 30, 1982  

SciTech Connect

A detailed report on our analytical methods has now been prepared entitled A stirred autoclave apparatus for study of the Fischer-Tropsch synthesis in a slurry-bed. II. Analytical procedures, by George A. Huff, Jr., Charles N. Satterfield, and Martin H. Wolf. Studies with the fused iron catalyst at 285/sup 0/C showed noticeable deactivation over a four-hour period, with a value of ..cap alpha.. = 0.66 based on light-gas analysis. This compares with values of 0.67 to 0.73 found over the same catalyst at 263/sup 0/C to 232/sup 0/C. Scouting studies with an unpromoted Co/kieselguhr catalyst showed a 23% loss of activity over the course of the run. Values of ..cap alpha.. are much more sensitive to degree of conversion on this catalyst than that found with iron. Studies in which ethylene or 1-butene was added to synthesis gas showed no effect on ..cap alpha.. over the fused iron catalyst, contrary to the results reported by Dwyer and Somorjai.

Satterfield, C.N.; Bartos, T.; Huff, G.A. Jr.; Stenger, H.

1982-01-01

380

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

SciTech Connect

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

Gomez-Cazalilla, M. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Merida-Robles, J.M. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Gurbani, A. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, 28049 Madrid (Spain); Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Jimenez-Lopez, A. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain)], E-mail: ajimenezl@uma.es

2007-03-15

381

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

NASA Astrophysics Data System (ADS)

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

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

2003-11-01

382

Rate coefficients at 298 K and 1 atm for the tropospheric degradation of a series of C6, C7 and C8 biogenic unsaturated alcohols initiated by Cl atoms  

NASA Astrophysics Data System (ADS)

Rate coefficients for the gas-phase reactions of Cl atoms with a series of unsaturated biogenic alcohols at 298 ± 3 K and 1 atm have been measured by the relative technique in an environmental chamber with in situ FTIR detection of reactants. The rate coefficients obtained using 1-butene and isobutene as reference compounds were (in units of 10-10 cm3 molecule-1 s-1): k1((E)-2-hexen-1-ol) = (3.49 ± 0.82), k2((E)-3-hexen-1-ol) = (3.42 ± 0.79), k3 ((Z)-3-hexen-1-ol) = (2.94 ± 0.72), k4((Z)-3-hepten-1-ol) = (3.80 ± 0.86) and k5((Z)-3-octen-1-ol) = (4.13 ± 0.68). This work constitutes the first kinetic study of the reactions cited above. The rate coefficients are compared with those for other unsaturated alcohols and a correlation between the reactivity of unsaturated alcohols toward Cl atoms and the energy of the HOMO of the unsaturated alcohols is presented. Based on the obtained results, the atmospheric lifetimes of the unsaturated alcohols have been estimated and possible atmospheric implications assessed.

Gibilisco, Rodrigo G.; Bejan, Iustinian; Barnes, Ian; Wiesen, Peter; Teruel, Mariano A.

2014-09-01

383

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

DOEpatents

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

Dumesic, James A. (Verona, WI); Ruiz, Juan Carlos Serrano (Madison, WI); West, Ryan M. (Madison, WI)

2012-04-03

384

New chiral P-N ligands for the regio- and stereoselective Pd-catalyzed dimerization of styrene.  

PubMed

Two new chiral, enantiomerically pure, hybrid P-N ligands, namely (2R,5S)-2-phenyl-3-(2-pyridyl)-1,3-diaza-2-phosphanicyclo[3,3,0]octan-4-one (1) and (2R,5S)-2-phenyl-3-(2-pyridyl)-1,3-diaza-2-phosphanicyclo[3,3,0]octane (2), have been synthesized starting from L-proline. The two ligands differ in the presence or not of a carbonyl group in the diazaphosphane ring. Their coordination chemistry towards Pd(II) was studied by reacting them with [Pd(CH?)Cl(cod)]. A different behaviour was observed: ligand 2 shows the expected bidentate chelating behaviour leading to the mononuclear Pd-complex, while ligand 1 acts as a terdentate ligand giving a dinuclear species. The corresponding cationic derivatives were obtained from the palladium neutral complexes, both as mono- and dinuclear derivatives, and tested as precatalysts for styrene dimerization, yielding E-1,3-diphenyl-1-butene regio- and stereoselectively as the sole product. A detailed analysis of the catalytic behaviour is reported. PMID:21343886

Fanfoni, Lidia; Meduri, Angelo; Zangrando, Ennio; Castillon, Sergio; Felluga, Fulvia; Milani, Barbara

2011-01-01

385

Characterization of non-methane hydrocarbons emitted from open burning of wheat straw and corn stover in China  

NASA Astrophysics Data System (ADS)

Field measurements were conducted to determine the characteristics of non-methane hydrocarbons (NMHCs) emitted from open burning of wheat straw and maize stover, two major agricultural residues in China. The headfire ignition technique was used with sampling downwind from the agricultural fire. Fifty-two NMHC species were quantified using gas chromatography/mass spectrometry. A carbon mass balance method was used to determine NMHC emission factors. The emission factors of the total speciated NMHCs from wheat straw and maize stover are 1690 ± 580 mg kg-1 and 1590 ± 430 mg kg-1, respectively. Propane, n-pentane, 2,3-dimethylbutane, 2-methylpentane, propene, benzene and toluene are the main species, together accounting for 55.3%-68.0% of the total NMHCs. On the basis of measured emission factors and the published maximum incremental reactivity values for NMHCs, we estimated the ozone forming potential (OFP) of speciated NMHCs. The results indicate that propene, 1-butene, isoprene, toluene and m,p-xylene have high OFP values and account for about 50% of the total OFP. Alkenes played the most important role in potential ozone formation, followed by aromatics and alkanes.

Li, Xinghua; Wang, Shuxiao; Duan, Lei; Hao, Jiming

2009-10-01

386

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

PubMed

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

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

2013-02-01

387

Semi-quantitative immunohistochemical analysis of male rat-specific alpha2u-globulin accumulation for chemical toxicity evaluation.  

PubMed

We purified male rat urinary alpha(2u)-globulin, prepared the antibody in rabbits, and improved an immunohistochemical detection method using this antibody for male rat-specific alpha(2u)-globulin accumulation appearing as hyaline droplets in the kidneys. Our prepared antibody reacted specifically with alpha(2u)-globulin in both immunohistochemical and Western blotting analyses, furthermore, and the graded immuno-reactivities on the slide were well associated with computational image analyzing results. Using this method, we retrospectively analyzed the renal sections from the toxicity studies of 12 nephrotoxic chemicals, which had already been conducted under the Japanese Existing Chemicals Survey Program. We demonstrated that the hyaline droplets induced by treatment with 10 chemicals (1,4-dibromobenzene, dicyclopentadiene, 3,4-dimethylaniline, 1,4-dicyanobenzene, tetrahydrothiophene-1,1-dioxide, 1,3-dicyanobenzene, acenaphthene, 3,4-dichloro-1-butene, 3a,4,7,7a-tetrahydro-1H-indene and 3,5,5-trimethylhexan-1-ol) were directly associated with alpha(2u)-globulin accumulation. This immunohistochemical method is convenient for applying, even retrospectively, paraffin sections from general toxicity studies and could be useful for qualifying male rat-specific hyaline droplets consisting of alpha(2u)-globulin and renal risk in humans. PMID:16538042

Hamamura, Masao; Hirose, Akihiko; Kamata, Eiichi; Katoku, Koshiro; Kuwasaki, Emiko; Oshikata, Takafumi; Nakahara, Yutaka; Ema, Makoto; Hasegawa, Ryuichi

2006-02-01

388

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

PubMed

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

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

2013-08-01

389

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

390

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

PubMed

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

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

2007-03-01

391

Emissions of C2 - C12 hydrocarbons in the Hsuehshan tunnel, Taiwan.  

PubMed

The concentrations of 56 hydrocarbons from C2 to C12 were measured simultaneously in the southbound bore, the northbound bore and the exhaust air shafts of the Hsuehshan tunnel near Yilan, Taiwan for 12 days during 2007 and 2008. A total of 60 integrated air samples were collected using stainless steel canisters and analyzed using GC/FID and GC/MS. The five most abundant species in all samples were ethylene, acetylene, isopentane, propylene and toluene. The exit/entrance ratios of total non-methane hydrocarbons (NMHC) concentration were 7.8 and 4.8 for the southbound and northbound bores, respectively. Furthermore, the exhaust from the vertical shafts affects air quality in the neighborhood. The most abundant species of emission rate (ER) was toluene (21.93-42.89 mg/sec), followed by isopentane, ethylene, propylene and 1-butene, with ER ranging from 2.50 to 9.31 mg/sec. The species in the three exhaust air shafts showed that the reactivities of these emissions are similar to those of vehicle emissions. Notably, the control of emissions in the vertical shafts of the vehicle tunnel will be important in the future. PMID:22066217

Lai, Chia-Hsiang; Peng, Yen-Ping

2011-01-01

392

Explosive photodissociation of methane induced by ultrafast intense laser  

SciTech Connect

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.

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

393

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

SciTech Connect

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

Kim, C.

1992-04-01

394

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

SciTech Connect

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

Kim, C.

1992-04-01

395

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

SciTech Connect

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

Fripiat, J.J.

1994-02-01

396

Direct oxidation of hydrocarbons in a solid-oxide fuel cell  

NASA Astrophysics Data System (ADS)

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.

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

2000-03-01

397

Direct oxidation of hydrocarbons in a solid-oxide fuel cell  

PubMed

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

Park; Vohs; Gorte

2000-03-16

398

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

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

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

2013-07-01

399

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

SciTech Connect

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

Lashier, M.E.; Schrader, G.L. (Iowa State Univ., Ames (USA))

1991-03-01

400

Explosive photodissociation of methane induced by ultrafast intense laser  

NASA Astrophysics Data System (ADS)

A new type of molecular fragmentation induced by femtosecond intense laser at the intensity of 2×1014 W/cm2 is reported. For the parent molecule of methane, ethylene, n-butane, and 1-butene, fluorescence from H (n=3-->2), CH (A 2?, B 2?-, and C 2?+-->X 2?), or C2 (d 3?g-->a 3?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-->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.

Kong, Fanao; Luo, Qi; Xu, Huailiang; Sharifi, Mehdi; Song, Di; Chin, See Leang

2006-10-01

401

Amylenes Do Not Lead to Bacterial Mutagenicity in Contrast to Structurally Related Epoxides  

PubMed Central

Amylenes are unsaturated hydrocarbons (C5H10), such as 1-pentene, 2-pentene, 2-methyl-but-1-en (3-methyl-1-butene), 2-methyl-but-2-en (isopentene), and 3-methyl-but-1-en. We investigated bacterial mutagenicity of 1-pentene, 2-pentene, and 3-methyl-but-1-en in the Ames test. 2-Pentene was investigated as racemate and as pure diastereomers. We included the methyltransferase deficient Salmonella Typhimurium strain YG7108 and the application of a gas-tight preincubation to reduce the risk of false negative results. 1,2-Epoxypentane which may arise from 1-pentene was used as positive control. None of the investigated amylenes showed mutagenic effects, whereas 1,2-epoxypentane was mutagenic exceeding 100??g per plate. An exceptional high reverse mutation in the negative control plates in the experiments with 1,2-epoxypentane was obviously caused by evaporation into the incubator which was shown by placing the control plates in a separate apparatus. No differences were seen upon use of YG7108 and its parent strain TA1535. In conclusion, 1,2-epoxypentane is most probably not a substrate of the deleted bacterial methyltransferases. The comparison of the bacterial mutagenicity of the investigated amylenes and 1,2-epoxipentane suggests that epoxidation of amylenes in the S9-mix does not proceed effectively or is counterbalanced by detoxifying reactions. The assessment of mutagenic effects of short chained aliphatic epoxides can be underestimated due to the evaporation of these compounds.

Westphal, Gotz A.; Tushaus, Carolin; Monse, Christian; Rosenkranz, Nina; Bruning, Thomas; Bunger, Jurgen

2014-01-01

402

Induction of unscheduled DNA synthesis in HeLa cells by allylic compounds.  

PubMed

Thirteen allylic compounds, mostly with close structural relationship, were tested for their ability to induce unscheduled DNA synthesis (UDS) in HeLa cells and mutations in the Ames test; 11 induced UDS in dose dependence. Allyl isothiocyanate was negative in UDS (borderline in the Ames test) and acrolein (positive in the Ames test) proved toxic to HeLa cells, therefore UDS measurement was excluded. In general, positive qualitative and quantitative correlation between UDS, Ames test and alkylating properties (as measured in the 4-nitrobenzyl-pyridine test, NBP) were found. Among structural analogs and typical allylic compounds with various leaving groups, the amount of induced DNA repair at equimolar concentrations decreased in the same order as the mutagenic and alkylating activities in the other 2 test systems: 1,3-dichloropropene (cis) greater than 1,3-dichloropropene (trans) greater than 2,3-dichloro-1-propene; 1-chloro-2-butene greater than 3-chloro-1-butene greater than 3-chloro-2-methyl-1-propene greater than allyl chloride; allyl-methane-sulfonate greater than -iodide greater than -bromide greater than -chloride. PMID:6627227

Schiffmann, D; Eder, E; Neudecker, T; Henschler, D

1983-10-01

403

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

SciTech Connect

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

Fuentes-Perujo, D. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Santamaria-Gonzalez, J. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Merida-Robles, J. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Jimenez-Lopez, A. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Maireles-Torres, P. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain)]. E-mail: maireles@uma.es; Moreno-Tost, R. [Instituto de Catalisis y Petroleoquimica, CSIC, c/ Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain); Mariscal, R. [Instituto de Catalisis y Petroleoquimica, CSIC, c/ Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

2006-07-15

404

Electron-scattering cross sections for 1-pentene, H2C=CH-(CH2)2CH3, molecules  

NASA Astrophysics Data System (ADS)

Cross sections, both experimental and theoretical, are reported for electron scattering from 1-pentene (C5H10) molecules. Absolute grand-total cross sections (TCSs) were measured at electron impact energies ranging from 1 to 300 eV, using a linear electron-transmission technique. The dominant behaviour of the experimental TCS energy function is a distinct asymmetric enhancement with the maximum located around 6.5 eV. Discernible are also three weak TCS structures: a small peak in the vicinity of 1.8 eV and two broad shoulders located between 10 and 30 eV. The additivity rule was employed to calculate the elastic cross section (ECS) from 20 to 3000 eV, while the binary-encounter-Bethe approach was used for the computation of the ionization cross section (ICS), from the threshold up to 3000 eV. Within 30 and 300 eV, the sum of computed cross sections (ECS+ICS) quite reasonably reproduces the experimental TCS values. Comparison is also made between the experimental TCS energy curve for 1-pentene (H2C=CH-(CH2)2CH3) and those measured for the ethylene (H2C=CH2) molecule and its substituted derivatives: propene (H2C=CH-CH3) and 1-butene (H2C=CH-CH2CH3).

Szmytkowski, Czes?aw; Mo?ejko, Pawe?; Zawadzki, Mateusz; Ptasi?ska-Denga, El?bieta

2013-03-01

405

Orientation Control of Molecular Chains in Polymers Using Atomic Force Microscopy  

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

406

Modeling molecular weight development of gas-phase {alpha}-olefin copolymerization  

SciTech Connect

A comprehensive kinetic model developed for molecular weight calculations of ethylene and {alpha}-olefin copolymerizations in the context of a terminal model accounts for multiple-type active centers of the catalyst, detailed elementary chemical reactions, and catalyst composition. The moments of copolymer chain distributions are defined considering molecular weights of comonomer units so that copolymer molecular weight averages can be directly calculated for those moments. A double Z-transformation is introduced for the derivation of differential equations of the moments. Model simulations are carried out based on ethylene and 1-butene copolymerizations in a gas-phase fluidized-bed reactor. Polydispersity of accumulated copolymer depends on catalyst composition and kinetic characteristics of the catalyst. For a catalyst with specified kinetic characteristics, the polydispersity depends on the mole fraction of each type of active center. For a catalyst with two types of active centers; the maximum polydispersity of copolymer occurs at 50 wt.% of the total copolymer if polydispersities of the copolymers generated at each active site are the same. Polydispersity of accumulated copolymer is sensitive to propagation reactions and chain transfer to hydrogen reactions. Differences in chain transfer to cocatalyst and monomers and in spontaneous deactivation rates for different types of active centers may play minor roles in controlling molecular weight development in the presence of hydrogen. This model can be used for catalyst composition design, simulation of commercial olefin copolymerization processes, and kinetic parameter estimation.

Xie, T.; McAuley, K.B.; Hsu, J.C.C.; Bacon, D.W. [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Chemical Engineering] [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Chemical Engineering

1995-05-01

407

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

SciTech Connect

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

Shapiro, P.J.; Bunel, E.; Schaefer, W.P.; Bercaw, J.E. (California Institute of Technology, Pasadena (USA))

1990-03-01

408

Conformational Analysis of 1-ALKENE Secondary Ozonides by Means of Matrix Isolation FTIR Spectroscopy  

NASA Astrophysics Data System (ADS)

An ability of ozone to break double C=C bond in olefins is known for more than five decades. Understanding of those reactions is very important in atmospheric chemistry. During different steps of the reaction the primary ozonide (POZ), carbonyl oxide (COX) and the secondary ozonide (SOZ) are formed. Fate of the reaction depends on many parameters such as type of radical, conformation of alkene, temperature of the reaction and environmental effects. Despite of numerous studies of the reaction by different spectroscopic techniques the precise mechanism of the reaction is still unknown. It is experimentally observed that the SOZ is more stable than POZ. Stability of the SOZ depends on the size and configuration of the radical. Unfortunately, it is not much known about the spatial structures of the SOZ'es. The aim of this study is to define the geometrical structures and stability of the different conformers of the 1-butene and 1-heptene secondary ozonides by combined analysis of the matrix isolation FTIR spectral data with the results of Density Functional Theory (DFT) calculations.

Sablinskas, Valdas; Strazdaite, Simona; Ceponkus, Justinas

2009-06-01

409

Synthesis of novel acid electrolytes for phosphoric acid fuel cells  

NASA Astrophysics Data System (ADS)

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

Adcock, James L.

1988-11-01

410

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

NASA Astrophysics Data System (ADS)

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

Peng, Ping

2005-03-01

411

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

SciTech Connect

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.

Adcock, J.L.

1988-11-01

412

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)

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.

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

413

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

414

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

PubMed

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), hydroxymethyl vinyl ketone (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 nonsmokers, 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 nonsmokers (19-27 per group). The new method has excellent sensitivity (LOQ, 1 ng/mL urine) and achieves accurate quantitat