- Catalytic dealkylation of phosphates with binuclear boron compounds
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The Salen(tBu) ligand and its derivatives were used to prepare binuclear boron complexes. These compounds have the formula, L(BBr2)2 (L = Salpen(tBu) and Salben(tBu)). These are formed from the reaction of the corresponding L[B(OMe)2]2 with BBr3. They represent a new type of binuclear boron compound. These compounds are active towards the dealkylation of many phosphates. They are also catalytically active with a stoichiometric amount of BBr3 to trimethylphosphate. Copyright
- Keizer, Timothy S.,De Pue, Lauren J.,Parkin, Sean,Atwood, David A.
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- Effect of 1-Butanol upon SN2 Reactions in Cationic Micelles. A Quantitative Treatment
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Observed first-order rate constants for reaction of methyl naphthalene-2-sulfonate (2-MeONs) with Br- in cetyltrimethylammonium and cetyltriethylammonium bromides (CTABr and CTEABr) are decreased by addition of 1-butanol.The inhibition can be treated quantitatively in terms of a pseudophase model in which the rate constant at the micellar surface follows the mole ratio of bound Br- to micellized surfactant and bound 1-BuOH.The second-order rate constants in the micellar pseudophase, kM, are independent of in the range 0-0.9 M.Conductometry and NMR line widths of 81Br- show that the alcohol reduces micellar binding of Br-, and spectral absorbance shows that binding of 2-MeONs is also reduced.
- Bertoncini, Clelia R. A.,Nome, Faruk,Cerichelli, Giorgio,Bunton, Clifford A.
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- Concentration and medium micellar kinetic effects caused by morphological transitions
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The reaction methyl naphthalene-2-sulfonate + Br- was investigated in several alkanediyl-α-ω-bis(dodecyldimethylammonium) bromide, 12-s-12,2Br- (with s = 2, 3, 4, 5, 6, 8, 10, 12), micellar solutions in the absence and in the presence of various additives. The additives were 1,2-propylene glycol, which remains in the bulk phase, N-decyl N-methylglucamide, MEGA10, which forms mixed micelles with the dimeric surfactants, and 1-butanol, which distributes between the aqueous and micellar phases. Information about the micellar reaction media was obtained by using conductivity and fluorescence measurements. In all cases, with the exception of water-1,2-prop 12-5-12,2Br- micellar solutions, with 30% weight percentage of the organic solvent, a sphere-to-rod transition takes place upon increasing surfactant concentration. In order to quantitatively explain the experimental data within the whole surfactant concentration range, a kinetic equation based on the pseudophase kinetic model was considered, together with the decrease in the micellar ionization degree accompanying micellar growth. However, theoretical predictions did not agree with the experimental kinetic data for surfactant concentrations above the morphological transition. An empirical kinetic equation was proposed in order to explain the data. It contains a parameter b which is assumed to account for the medium micellar kinetic effects caused by the morphological transition. The use of this empirical equation permits the quantitative rationalization of the kinetic micellar effects in the whole surfactant concentration range.
- Graciani, Maria Del Mar,Rodriguez, Amalia,Martin, Victoria Isabel,Fernandez, Gaspar,Moya, Maria Luisa
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- The selective high-yield conversion of methane using iodine-catalyzed methane bromination
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Methyl bromide is used as feed in a process that converts it to gasoline. It is prepared by the gas-phase reaction of CH4 with Br2, a reaction that produces, besides the desired CH3Br, large amounts of CH2Br2. The latter cokes the catalyst used for gasoline production. The separation of CH2Br2 by distillation makes gasoline production too expensive. It is therefore important to increase the selectivity of the bromination reaction. We show that a small amount of I 2 catalyzes the reaction CH2Br2 + CH 4 → 2CH3Br, which leads to higher CH4 conversion and higher selectivity to CH3Br. These findings are promising for developing a low-cost integrated bromine-iodine based dual-halogen pathway to convert stranded natural gas into fuels and chemicals.
- Ding, Kunlun,Metiu, Horia,Stucky, Galen D.
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- An Activated TiC–SiC Composite for Natural Gas Upgrading via Catalytic Oxyhalogenation
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Alkane oxyhalogenation has emerged as an attractive catalytic route for selective natural gas functionalization to important commodity chemicals, such as methyl halides or olefins. However, few systems have been shown to be active and selective in these reactions. Here, we identify a novel and highly efficient TiC–SiC composite for methane and ethane oxyhalogenation. Detailed characterization elucidates the kinetics and mechanism of the selective activation under reaction conditions to yield TiO2–TiC–SiC. This catalyst outperforms bulk TiO2, one of the best reported catalysts, reaching up to 85 % selectivity and up to 3 times higher titanium-specific space-time-yield of methyl halides or ethylene. This is attributed to the fact that the active TiO2 phase generated in situ is embedded in the thermally conductive SiC matrix, facilitating heat dissipation thus improving selectivity control.
- Zichittella, Guido,Puértolas, Bego?a,Siol, Sebastian,Paunovi?, Vladimir,Mitchell, Sharon,Pérez-Ramírez, Javier
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- Kinetic Study of CH3 + HBr and CH3 + Br Reactions by Laser Photolysis-Transient Absorption over 1-100 Bar Pressure Range
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Reactions of methyl radicals with hydrogen bromide CH3 + HBr -> CH4 + Br (1) and bromine atoms CH3 + Br -> CH3Br (2) were studied using excimer laser photolysis-transient UV spectroscopy at 297 +/- 3 K over the 1-100 bar buffer gas (He) pressure range. Methyl radicals were produced by 193 nm (ArF) laser photolysis of acetone, (CH3)2CO, and methyl bromide, CH3Br. Temporal profiles of methyl radicals were monitored by UV absorption at 216.51 nm (copper hollow cathode lamp with current boosting). The yield of acetyl radicals in photolysis of acetone at 193 nm was found to be less than 5 percent at 100 bar He based on the transient absorptions at 222.57 and 224.42 nm. The measured rate constants for reaction 1 are k1 = (2.9 +/-0.7)E-12, (3.8 +/- 1.5)E-12, and (3.4 +/- 1.3)E-12 cm3 molecule-1 s-1 at the buffer gas (He) pressures of 1.05, 11.2, and 101 bar, respectively. The rate data obtained in this study confirmed high values of the previous (low pressure) measurements and ruled out the possibility of interference of excited species. The measured rate constant is independent of pressure within the experimental error. The rate constant of reaction of methyl radicals with bromine atoms (2) was determined relative to the rate constant of methyl radical self reaction, CH3 + CH3 -> C2H6 (3) in experiments with photolysis of CH3Br: k2/k3 = 0.92 +/- 0.32, 1.15 +/- 0.30, and 1.65 +/- 0.26 at 1.05, 11.2, and 101 bar He, respectively. On the basis of the literature data for reaction 3, this yields k2 = (5.8 +/- 2.2)E-11, (7.4 +/- 2.2)E-11, (10.7 +/- 2.3)E-11, and (11.9 +/- 2.5) E-11 cm3 molecule-1 s-1 at 1 .05, 1 1.2, 101 bar (He), and in the high-pressure limit, respectively.
- Krasnoperov, Lev N.,Mehta, Kashyap
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- Kinetics of methoxy-NNO-Azoxymethane hydrolysis in strong acids
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The kinetics of methoxy-NNO-azoxymethane (I) hydrolysis in concentrated solutions of strong acids (HBr, HCl, HClO4, and H2SO 4) has been investigated by a manometric method. The gas evolution rate is described by the equation corresponding to two consecutive first-order reactions, with the rate constant of the second reaction considerably exceeding the rate constant of the first reaction, i.e., k 2 {ie17-1} k 1. The temperature dependences of k 1 (s-1) in 47.59% HBr in the temperature range from 60 to 90°C and in 64.16% H 2SO4 between 80 and 130°C are described by Arrhenius equations with IogA= 12.7 ± 1.5 and 13.6 ± 1.4 and E a = 115 ± 10 and 137 ± 10 kJ/mol, respectively. The parameters of the Arrhenius equation for the rate constant k 2 for the reaction in 64.16% H2SO4 between 80 and 130°C are IogA= 9.1 ± 2.5 and E a = 91 ± 18 kJ/mol. An analysis of the UV spectra of compound I in concentrated H2SO4 shows that I is a weak base (pKBH+ ≈ - 6). The rate-determining step of the hydrolysis of I is the attack of the nucleophile on the carbon atom of the MeO group of the protonated molecule of I. The resulting methyldiazene dioxide decomposes via a complicated mechanism to evolve N2, NO, and N2O. The pseudo-first-order rate constant k 1 of the reaction at 80°C depends strongly on the acid concentration and on the type of nucleophile (Br-, Cl-, or H2O). The relationship between k 1 and the rate constant k of the bimolecular nucleophilic substitution reaction (SN2) is given by the linear equation log [k1/(CH + CNu)] = m ≠ mX 0 + log (k/KBH+), where CH + and C Nu are the concentrations of H+ and nucleophile, respectively; X 0 is the excess acidity; and m and m are coefficients. The Swain-Scott equation log (kNu/kH2 O) = ns, where n is the nucleophilicity factor and s is the substrate constant (s = 0.72), is applicable to the rate constants k of the S N2 reactions of the protonated molecule of I with Br-, Cl-, and H2O.
- Zyuzin,Lempert
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- Study of the bromide ion reaction with methyl naphthalene-2-sulfonate in water-DMSO TTAB micellar solutions
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The reaction of bromide ions with methyl naphthalene-2-sulfonate (MeNS) has been investigated in water-dimethyl sulfoxide, DMSO, tetradecyltrimethylammonium bromide, TTAB, micellar solutions, with the weight percentage of DMSO up to 50%. In order to quantitatively rationalize the micellar kinetic effects observed, conductivity, surface tension, and steady-state fluorescence measurements were used to get information about the micellar reaction media. Results showed that changes caused by the addition of different amounts of DMSO to TTAB aqueous micellar solutions are made evident from the kinetic micellar effects, these being a helpful tool to obtain information on the micellar reaction media in the presence of the added organic solvent. Copyright
- Moya, Maria Luisa,Rodriguez, Amalia,Munoz, Maria,Del Mar Graciani, Maria,Fernandez, Gaspar
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- Kinetics of Reactions of Halogenated Methyl Radicals with Hydrogen Iodide
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The kinetics of the reactions of CH2I, CH2Br, CH2Cl, and CHCl2 with HI were studied in a tubular reactor coupled to a photoionization mass spectrometer.Rate constants were measured as a function of temperature (typically between 294 and 552 K) to determine Arrhenius parameters.For these and other R + HI reactions studied to date (i.e., those involving aklyl radicals), a linear free energy relationship was dicovered which correlates the large differences in reactivity among all these R + HI reactions with the inductive effect of the substitutent atoms or groups on the central carbon atom.
- Seetula, Jorma A.,Gutman, David
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- Trialkylammonium salt degradation: Implications for methylation and cross-coupling
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Trialkylammonium (most notably N,N,N-trimethylanilinium) salts are known to display dual reactivity through both the aryl group and the N-methyl groups. These salts have thus been widely applied in cross-coupling, aryl etherification, fluorine radiolabelling, phase-transfer catalysis, supramolecular recognition, polymer design, and (more recently) methylation. However, their application as electrophilic methylating reagents remains somewhat underexplored, and an understanding of their arylation versus methylation reactivities is lacking. This study presents a mechanistic degradation analysis of N,N,N-trimethylanilinium salts and highlights the implications for synthetic applications of this important class of salts. Kinetic degradation studies, in both solid and solution phases, have delivered insights into the physical and chemical parameters affecting anilinium salt stability. 1H NMR kinetic analysis of salt degradation has evidenced thermal degradation to methyl iodide and the parent aniline, consistent with a closed-shell SN2-centred degradative pathway, and methyl iodide being the key reactive species in applied methylation procedures. Furthermore, the effect of halide and non-nucleophilic counterions on salt degradation has been investigated, along with deuterium isotope and solvent effects. New mechanistic insights have enabled the investigation of the use of trimethylanilinium salts in O-methylation and in improved cross-coupling strategies. Finally, detailed computational studies have helped highlight limitations in the current state-of-the-art of solvation modelling of reaction in which the bulk medium undergoes experimentally observable changes over the reaction timecourse. This journal is
- Assante, Michele,Baillie, Sharon E.,Juba, Vanessa,Leach, Andrew G.,McKinney, David,Reid, Marc,Washington, Jack B.,Yan, Chunhui
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p. 6949 - 6963
(2021/06/02)
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- Carbon-Supported Bimetallic Ruthenium-Iridium Catalysts for Selective and Stable Hydrodebromination of Dibromomethane
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Catalysts based on individual precious metals on carbon- and oxide-based carriers have shown remarkably selective behavior in the hydrodebromination of CH2Br2 to CH3Br, an important transformation within halogen-mediated methane upgrading processes. However, the high susceptibility of the active phase to coking and to sintering, which cannot be overcome by controlling the nuclearity of the metal species, hinders their practical implementation. Herein, a platform of carbon-supported Ir?Ru catalysts with distinct metal ratios at comparable metal nanoparticle size (ca. 1.0 nm) was adopted to systematically study the effects of a second metal on reactivity and stability. Catalytic tests reveal ruthenium-doped iridium nanoparticles as the first system that combines high CH3Br selectivity (up to 93 %) with unprecedented stability, outperforming any of the previously reported catalysts. This superior performance was rationalized by the intimate interaction between the two metals, forming ruthenium-poor surface alloys, which enable suppressing deactivation mechanisms as well as over hydrogenation/coking pathways.
- Bonchev, Hristo,Mitchell, Sharon,Pérez-Ramírez, Javier,Saadun, Ali J.
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- Nuclearity and Host Effects of Carbon-Supported Platinum Catalysts for Dibromomethane Hydrodebromination
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The identification of the active sites and the derivation of structure-performance relationships are central for the development of high-performance heterogeneous catalysts. Here, a platform of platinum nanostructures, ranging from single atoms to nanoparticles of ≈4?nm supported on activated- and N-doped carbon (AC and NC), is employed to systematically assess nuclearity and host effects on the activity, selectivity, and stability in dibromomethane hydrodebromination, a key step in bromine-mediated methane functionalization processes. For this purpose, catalytic evaluation is coupled to in-depth characterization, kinetic analysis, and mechanistic studies based on density functional theory. Remarkably, the single atom catalysts achieve exceptional selectivity toward CH3Br (up to 98%) when compared to nanoparticles and any previously reported system. Furthermore, the results reveal unparalleled specific activity over 1.3–2.3?nm-sized platinum nanoparticles, which also exhibit the highest stability. Additionally, host effects are found to markedly affect the catalytic performance. Specifically, on NC, the activity and CH3Br selectivity are enhanced, but significant fouling occurs. On the other hand, AC-supported platinum nanostructures deactivate due to sintering and bromination. Simulations and kinetic fingerprints demonstrate that the observed reactivity patterns are governed by the H2 dissociation abilities of the catalysts and the availability of surface H-atoms.
- Saadun, Ali J.,Kaiser, Selina K.,Ruiz-Ferrando, Andrea,Pablo-García, Sergio,Büchele, Simon,Fako, Edvin,López, Núria,Pérez-Ramírez, Javier
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- Functionalization of RhIII-Me Bonds: Use of capping Arene Ligands to Facilitate Me-X Reductive Elimination
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We show how to improve the yield of MeX from CH4 activation catalysts from 12% to 90% through the use of capping arene ligands. Four (FP)RhIII(Me)(TFA)2 {FP = capping arene ligands, including 8,8′-(1,2-phenylene)diquinoline (6-FP), 8,8′-(1,2-naphthalene)diquinoline (6-NPFP), 1,2-bis(N-7-azaindolyl)benzene (5-FP), and 1,2-bis(N-7-azaindolyl)naphthalene (5-NPFP)} complexes. These complexes and (dpe)RhIII(Me)(TFA)2 (dpe = 1,2-di-2-pyridylethane) were synthesized and tested for their performance in reductive elimination of MeX (X = TFA or halide). The FP ligands were used with the goal of blocking a coordination site to destabilize the RhIII complexes and facilitate MeX reductive elimination. On the basis of single-crystal X-ray diffraction studies, the 6-FP and 6-NPFP ligated Rh complexes have Rh-arene distances shorter than those of the 5-FP and 5-NPFP Rh complexes; thus, it is expected that the Rh-arene interactions are weaker for the 5-FP complexes than for the 6-FP complexes. Consistent with our hypothesis, the 5-FP and 5-NPFP RhIII complexes demonstrate improved performance (from 12% to ~60% yield) in the reductive elimination of MeX. The reductive elimination of MeX from (FP)RhIII(Me)(TFA)2 can be further improved by the use of chemical oxidants. For example, the addition of 2 equiv of AgOTf leads to 87(2)% yield of MeTFA and can be achieved in CD3CN at 90 °C using (5-FP)Rh(Me)(TFA)2.
- Gu, Shunyan,Chen, Junqi,Musgrave, Charles B.,Gehman, Zo? M.,Habgood, Laurel G.,Jia, Xiaofan,Dickie, Diane A.,Goddard, William A.,Gunnoe, T. Brent
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p. 1889 - 1906
(2021/05/29)
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- Hydrodehalogenation of alkyl halides catalyzed by a trichloroniobium complex with a redox active α-diimine ligand
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A high-valent d0 niobium(v) complex, (α-diimine)NbCl3 (1), bearing a dianionic redox-active α-diimine ligand served as a catalyst for a hydrodehalogenation reaction of alkyl halides in the presence of PhSiH3. During the catalytic reaction, the redox-active α-diimine ligand allowed the complex to reversibly release and accept one-electron through switching its coordination mode between a dianionic folded form and a monoanionic planar one.
- Nishiyama, Haruka,Hosoya, Hiromu,Parker, Bernard F.,Arnold, John,Tsurugi, Hayato,Mashima, Kazushi
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p. 7247 - 7250
(2019/07/02)
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- A Very Strong Methylation Agent: [Me2Cl][Al(OTeF5)4]
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A new chloronium-containing salt, [Me2Cl][Al(OTeF5)4], was synthesized on multigram scale by means of a simple one-pot procedure. The isolated product can be handled at room temperature and used as a strong electrophilic methylation agent. This is demonstrated by the methylation of the very weak bases P(CF3)3, PF3, MeI, and MeBr.
- H?mmerling, Sebastian,Thiele, Günther,Steinhauer, Simon,Beckers, Helmut,Müller, Carsten,Riedel, Sebastian
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supporting information
p. 9807 - 9810
(2019/06/24)
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- Versatile Method for the Simultaneous Synthesis of Two Ionic Liquids, Otherwise Difficult to Obtain, with High Atom Economy
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A new synthetic approach and full spectral (NMR, IR, MS) and ion chromatographic characterization (IC) of nitrogen-based ionic liquids bearing allyl- or ethyl- substituent and triflate, tosylate, methyl sulfate or methanesulfonate anion has been presented. On a sample of 16 new ionic liquids, the versatility of the anion exchange method has been proven. In the metathesis reactions that have been carried out, the halide anion was exchanged in ionic liquid with an alkyl sulfonate based anion using alkylating agents. The results obtained using ion chromatographic analysis on the newly synthesized compounds have been discussed. Also, the utilization of a gaseous methyl halide by-product, obtained in the metathesis reaction and otherwise difficult to synthesize, has been presented. This approach ensured high atom economy of the overall process, which makes the proposed methodology sustainable and eco-friendly.
- Szpecht, Andrea,Zajac, Adrian,Zielinski, Dawid,Maciejewski, Hieronim,Smiglak, Marcin
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p. 972 - 983
(2019/08/06)
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- Synthesis, antibacterial and antitumor activity of methylpyridinium salts of pyridoxine functionalized 2-amino-6-sulfanylpyridine-3,5-dicarbonitriles
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A library of 29 2-amino-6-sulfanylpyridine-3,5-dicarbonitriles functionalized with a pyridoxine moiety was synthesized using a three-component one-pot reaction of aldehyde derivative of pyridoxine, malononitrile, and thiophenol. The obtained bipyridine structures were converted into methylpyridinium salts. Several compounds demonstrated expressed antibacterial activity with MICs (minimum inhibitory concentrations) in the range of 0.5–4 μg/mL against the three studied Gram-positive strains and 8–64 μg/mL against the Gram-negative E. coli strain, which was comparable or better than the activity of the reference antimicrobial agents. At the same time, all the synthesized compounds were inactive against the Gram-negative P. aeruginosa. Several compounds also demonstrated high cytotoxic activity against the studied tumor cells, but without selectivity for the normal HSF (human foreskin fibroblast) cells. Despite the preliminary character of the performed biological studies, the obtained results make the obtained structural chemotype a promising starting point for the design of physiologically active compounds.
- Grigor’ev, Arthur A.,Shtyrlin, Nikita V.,Gabbasova, Raylya R.,Zeldi, Marina I.,Yu. Grishaev, Denis,Gnezdilov, Oleg I.,Balakin, Konstantin V.,Nasakin, Oleg E.,Shtyrlin, Yurii G.
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p. 2288 - 2304
(2018/08/29)
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- Photodecomposition and thermal decomposition in methylammonium halide lead perovskites and inferred design principles to increase photovoltaic device stability
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Hybrid lead halide perovskites have emerged as promising active materials for photovoltaic cells. Although superb efficiencies have been achieved, it is widely recognized that long-term stability is a key challenge intimately determining the future development of perovskite-based photovoltaic technology. Herein, we present reversible and irreversible photodecomposition reactions of methylammonium lead iodide (MAPbI3). Simulated sunlight irradiation and temperature (40-80 °C) corresponding to solar cell working conditions lead to three degradation pathways: (1) CH3NH2 + HI (identified as the reversible path), (2) NH3 + CH3I (the irreversible or detrimental path), and (3) a reversible Pb(0) + I2(g) photodecomposition reaction. If only the reversible reactions (1) and (3) take place and reaction (2) can be avoided, encapsulated MAPbI3 can be regenerated during the off-illumination timeframe. Therefore, to further improve operational stability in hybrid perovskite solar cells, detailed understanding of how to mitigate photodegradation and thermal degradation processes is necessary. First, encapsulation of the device is necessary not only to avoid contact of the perovskite with ambient air, but also to prevent leakage of volatile products released from the perovskite. Second, careful selection of the organic cations in the compositional formula of the perovskite is necessary to avoid irreversible reactions. Third, selective contacts must be as chemically inert as possible toward the volatile released products. Finally, hybrid halide perovskite materials are speculated to undergo a dynamic formation and decomposition process; this can gradually decrease the crystalline grain size of the perovskite with time; therefore, efforts to deposit highly crystalline perovskites with large crystal sizes may fail to increase the long-term stability of photovoltaic devices.
- Juarez-Perez, Emilio J.,Ono, Luis K.,Maeda, Maki,Jiang, Yan,Hawash, Zafer,Qi, Yabing
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supporting information
p. 9604 - 9612
(2018/05/31)
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- One-Pot Conversion of Methane to Light Olefins or Higher Hydrocarbons through H-SAPO-34-Catalyzed in Situ Halogenation
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Methane was converted to light olefins (ethene and propene) or higher hydrocarbons in a continuous flow reactor below 375 °C over H-SAPO-34 catalyst via an in situ halogenation (chlorination/bromination) protocol. The reaction conditions can be efficiently tuned toward selective monohalogenation of methane to methyl halides or their in situ oligomerization to higher hydrocarbons. The presence of C5+ hydrocarbons in the reaction products clearly indicates that by using a properly engineered catalyst under optimized reaction conditions, hydrocarbons in the gasoline range can be produced. This approach has significant potential for feasible application in natural gas refining to gasoline and materials under moderate operational conditions.
- Batamack, Patrice T. D.,Mathew, Thomas,Prakash, G. K. Surya
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p. 18078 - 18083
(2017/12/26)
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- Reactive polymer zwitterions: Sulfonium sulfonates
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Sulfonium sulfonate, or sulfothetin, zwitterionic monomers were synthesized by ring-opening of 1,3-propanesultone with dialkyl sulfides containing styrenic or methacrylic moieties. Reversible addition-fragmentation chain-transfer polymerization of these m
- Santa Chalarca, Cristiam F.,Emrick, Todd
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- The performance and mechanism for the catalytic oxidation of dibromomethane (CH2Br2) over Co3O4/TiO2 catalysts
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Brominated hydrocarbons are a typical pollutant in exhaust gas from the synthesis process of Purified Terephthalic Acid (PTA), and may cause various environmental problems once emitted into the atmosphere. Dibromomethane (DBM) was employed as the model compound in this study, and a series of Co3O4/TiO2 catalysts with various Co contents were prepared for the catalytic oxidation of DBM. The prepared catalysts were characterized by XRD, BET, SEM, TEM, XPS, H2-TPR and NH3-TPD. Among the prepared catalysts, CoTi-5 (5 wt% Co/TiO2) showed the highest catalytic activity, with T90 at about 346 °C, which was mainly attributed to the enrichment of well-dispersed Co3O4 and the high surface Co3+/Co2+ ratio, as it could provide more surface active sites and active oxygen species. The kinetic study showed that the reaction order of DBM was pseudo first-order and the reaction order of oxygen was approximately zero-order. A plausible DBM reaction mechanism over Co3O4/TiO2 catalysts was also proposed based on the results of in situ FTIR and the analysis of gas products by GC-MS. The reaction process started with the adsorption on surface oxygen vacancies, breakage of C-Br bonds and partial dissociation of C-H bonds with the formation of intermediate species, and then the intermediate species were further oxidized to form CO and CO2.
- Mei, Jian,Zhao, Songjian,Xu, Haomiao,Qu, Zan,Yan, Naiqiang
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p. 31181 - 31190
(2016/04/08)
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- A new catalytic process for the synthesis of para-xylene through benzene methylation with CH3Br
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A new process for the generation of para-xylene (p-xylene) through benzene alkylation with CH3Br has been proposed for the first time. CH 3Br is prepared by the catalytic bromination of methane (the main component of natural gas), and benzene can be prepared from methane dehydroaromatization. Over the optimized P2O5-ZnO/HZSM-5 catalyst, benzene conversion is 43.6% and p-xylene selectivity is 91.2% at 475 °C, and the molar ratio of p-xylene in the liquid product is 28.7%. The relationship between the acidity and the catalytic efficiency of the modified H-ZSM-5 samples was investigated. It is found that isomerization of p-xylene occurs on the strong acid sites rather than on the weak acid sites, and benzene conversion is subject to the influence of strong acid sites.
- Zhang, Ying-Ying,Li, Yue-Fang,Chen, Lang,Au, Chak-Tong,Yin, Shuang-Feng
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- Synthesis of HZSM-5@silicalite-1 core-shell composite and its catalytic application in the generation of p-xylene by methylation of toluene with methyl bromide
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A core-shell HZSM-5@silicalite-1 composite was synthesized by overgrowing silicalite-1 on the external surface of HZSM-5, and was characterized by XRD, SEM, TEM, NH3-TPD, 1,3,5-triisopropylbenzene (TIPB) cracking and N2 adsorption-desorption techniques. When used as a catalyst for the formation of p-xylene through toluene methylation with methyl bromide, the HZSM-5@silicalite-1 composite exhibits para-selectivity of up to 76% with no evidence of deactivation in an on stream period of 3 h. The excellent catalytic performance is attributed to the inactive silicalite-1 shell that extends the diffusion path length of xylenes while having the acid sites on the external surface of HZSM-5 fully covered. the Partner Organisations 2014.
- Deng, Yi-Qiang,Zhou, Wei-Fang,Lv, Hao-Ming,Zhang, Ying-Ying,Au, Chak-Tong,Yin, Shuang-Feng
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p. 37296 - 37301
(2014/11/12)
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- A new catalytic process for the synthesis of para-xylene through benzene methylation with CH3Br
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A new process for the generation of para-xylene (p-xylene) through benzene alkylation with CH3Br has been proposed for the first time. CH3Br is prepared by the catalytic bromination of methane (the main component of natural gas), and benzene can be prepared from methane dehydroaromatization. Over the optimized P2O5-ZnO/HZSM-5 catalyst, benzene conversion is 43.6% and p-xylene selectivity is 91.2% at 475 °C, and the molar ratio of p-xylene in the liquid product is 28.7%. The relationship between the acidity and the catalytic efficiency of the modified H-ZSM-5 samples was investigated. It is found that isomerization of p-xylene occurs on the strong acid sites rather than on the weak acid sites, and benzene conversion is subject to the influence of strong acid sites.
- Zhang, Ying-Ying,Li, Yue-Fang,Chen, Lang,Au, Chak-Tong,Yin, Shuang-Feng
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supporting information
p. 6 - 10
(2015/03/18)
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- Processes and Systems for Separate, Parallel Methane and Higher Alkanes' Bromination
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Process and systems for alkane bromination and, in one or more embodiments, to separate, parallel methane and higher alkanes bromination in a bromine-based process. An embodiment discloses a bromine-based process for converting alkanes to liquid hydrocarbons that includes alkanes bromination, the process comprising: brominating a methane stream comprising methane and having less than about 2 mol % of ethane to form methane bromination products comprising brominated methane and a first fraction of hydrogen bromide; separately brominating a C2+ alkane stream comprising an alkane having 2 or more carbon atoms to form C2+ methane bromination products comprising brominated alkanes having 2 or more carbon atoms and a second fraction of hydrogen bromide; and catalytically reacting at least a portion of the brominated methane and the brominated alkanes to form higher molecular hydrocarbons.
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Paragraph 0055
(2013/05/08)
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- METHOD OF PRODUCING ALCOHOLS
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A method of making alcohols involves forming of alcohol esters from liquid alkane halides and a solution of metallic salts of organic acids to produce gaseous alcohol esters for reaction with magnesium or metal hydroxides to form the alcohol and the metal salt of the organic acids. In an improvement method, liquid phase alcohol esters instead of gaseous alcohol esters are produced from liquid alkane halides and a solution of metal salts of organic acids whose alkane esters are less soluble in water than that of the alkane halide and treating of the alcohol ester formed with magnesium or metal hydroxides to form the alcohol and the metal salt of the organic acids.
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Paragraph 0035
(2013/08/28)
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- Structure and phase analysis of one-pot hydrothermally synthesized FePO4-SBA-15 as an extremely stable catalyst for harsh oxy-bromination of methane
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FePO4-SBA-15 (OP) was directly synthesized via a one-pot hydrothermal technique, using Fe(NO3)3 and H 3PO4 as the precursors. FePO4/SBA-15 (IMP) was also prepared as a reference, using an impregnation method and commercially available SBA-15 as the support. The yielding samples were employed to catalyze the harsh oxy-bromination of methane (OBM) reaction, showing similar initial catalytic performances. The fresh and spent samples after catalytic reaction were thoroughly characterized by N2-physisoption, inductively coupled plasma, wide- and small-angle X-ray diffraction, transmission electron microscopy, diffuse reflectance UV-vis spectroscopy, temperature-programmed oxidation, and room temperature 57Fe M?ssbauer spectroscopy. It was found that the FePO4 was in good crystalline in the OP sample while it was in amorphous for the IMP catalyst. Despite this difference, both FePO4 phases in the fresh samples were transformed into Fe 7(PO4)6 and Fe2P2O 7 in the spent ones. Furthermore, the OP catalyst showed excellent stability in a period of 1000 h time-on-stream performance without apparent deposition of cokes. The losses of P and Fe after the catalytic evaluation were only 9.5% and 15.5%, respectively, while the ratio of P/Fe remained close to 1.0. N2-adsorption and TEM observations confirmed that the mesoporous pores were extremely stable under the harsh reaction ambience, which might play a crucial role in the stability test.
- Wang, Runqin,Lin, Ronghe,Ding, Yunjie,Liu, Jia,Wang, Junhu,Zhang, Tao
-
p. 235 - 243
(2013/03/29)
-
- Oxidative reactivity of (N2S2)PdRX complexes (R = Me, Cl; X = Me, Cl, Br): Involvement of palladium(III) and palladium(IV) intermediates
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A series of (N2S2)PdRX complexes (N2S2 = 2,11-dithia[3.3](2,6) pyridinophane; R = X = Me, 1; R = Me, X = Cl, 2; R = Me, X = Br, 3; R = X = Cl, 4) were synthesized, and their structural and electronic properties were investigated. X-ray crystal structures
- Luo, Jia,Rath, Nigam P.,Mirica, Liviu M.
-
supporting information
p. 3343 - 3353
(2013/07/19)
-
- A versatile diphosphine ligand: Cis and trans chelation or bridging, with self association through hydrogen bonding
-
The diphosphine ligand, N,N′-bis(2-diphenylphosphinoethyl) isophthalamide, dpipa, contains two amide groups and can form cis or trans chelate complexes or cis,cis or trans,trans bridged complexes. The amide groups are likely to be involved in intramolecular or intermolecular hydrogen bonding. This combination of properties of the ligand dpipa leads to very unusual structural properties of its complexes, which often exist as mixtures of monomers and dimers in solution. In the complex [Au2(μ-dpipa) 2]Cl2, the ligands adopt the trans,trans bridging mode, with linear gold(I) centers, and the amide groups hydrogen bond to the chloride anions. In [Pt2Cl4(μ-dpipa)2], the ligands adopt the cis,cis bridging mode, with square planar platinum(II) centers, and the amide groups form intermolecular hydrogen bonds to the chloride ligands to form a supramolecular one-dimensional polymer. Both the monomeric and dimeric complexes [PtMe2(dpipa)] and [Pt2Me4(μ- dpipa)2] have cis-PtMe2 units with cis chelating or cis,cis bridging dpipa ligands respectively; each forms a supramolecular dimer through hydrogen bonding between amide groups and each contains an unusual NH···Pt interaction. An attempted oxidative addition reaction with methyl iodide gave the complex [PtIMe(dpipa)], which contains trans chelating dpipa, while a reaction with bromine gave a disordered complex with approximate composition [Pt2Me3Br5(μ- dpipa)2], which contains trans,trans bridging dpipa ligands.
- Nasser, Nasser,Borecki, Aneta,Boyle, Paul D.,Puddephatt, Richard J.
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p. 7051 - 7060
(2013/07/25)
-
- Transformation of methane to propylene: A two-step reaction route catalyzed by modified CeO2 nanocrystals and zeolites
-
Propylene from methane: The transformation of methane to propylene has been realized in a two-step route via CH3Cl or CH3Br. CeO 2 serves as an efficient and stable catalyst for the oxidative chlorination and bromination of methane to CH3Cl and CH 3Br. In the second step, a modified zeolite is highly a selective and stable catalyst for the conversion of CH3Cl or CH3Br into propylene. Copyright
- He, Jieli,Xu, Ting,Wang, Zhihui,Zhang, Qinghong,Deng, Weiping,Wang, Ye
-
supporting information; experimental part
p. 2438 - 2442
(2012/04/23)
-
- Diverse C-C bond-forming reactions of bis(carbene)platinum(II) complexes
-
The platinum(0) complex Pt(PPh3)4 catalyzes coupling of the carbene ligands of (CO)5Cr{C(OMe)(p-MeOC6H 4)} (1). The stable bis(carbene)platinum(II) complexes Cl 2Pt{C(OMe)(Me)}2
- Klet, Rachel C.,Labinger, Jay A.,Bercaw, John E.
-
p. 6652 - 6657
(2012/11/07)
-
- Metal ions do not play a direct role in the formation of carbon-carbon triple bonds during reduction of trihaloalkyls by CrII or V II
-
Carbyne radicals: Reactions of trihaloalkyl compounds with Cr2+ or V2+ in aqueous solutions yield alkynes and other products. Stepwise halogen abstractions from the trihaloalkyls form alkyl carbyne triradicals in solution. These radicals undergo coupling reactions, producing triply bonded alkyne molecules (see scheme). This process is not metal-assisted and does not occur in the coordination sphere of the metal ions.
- Levy, Ophir,Bino, Avi
-
supporting information
p. 15944 - 15947
(2013/02/23)
-
- CONVERSION OF HYDROGEN BROMIDE TO ELEMENTAL BROMINE
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A method is provided for converting hydrogen bromide to elemental bromine. A portion of an initial hydrogen bromide-rich gas is thermally oxidized at a thermal oxidation temperature to produce a first fraction of elemental bromine and a remainder of the initial hydrogen bromide-rich gas. At least a portion of the remainder of the initial hydrogen bromide-rich gas is catalytically oxidized at a lower catalytic oxidation temperature to produce a second fraction of elemental bromine.
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Page/Page column 25
(2011/02/18)
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- PROCESSES FOR CONVERTING GASEOUS ALKANES TO LIQUID HYDROCARBONS USING MICROCHANNEL REACTOR
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A process for converting gaseous alkanes to olefins, higher molecular weight hydrocarbons or mixtures thereof wherein a gaseous feed containing alkanes may be thermally or catalytically reacted with a dry bromine vapor to form alkyl bromides and hydrogen bromide. Poly-brominated alkanes present in the alkyl bromides may be further reacted with methane over a suitable catalyst to form mono-brominated species. The mixture of alkyl bromides and hydrogen bromide may then be reacted over a suitable catalyst at a temperature sufficient to form olefins, higher molecular weight hydrocarbons or mixtures thereof and hydrogen bromide. Various methods and reactions are disclosed to remove the hydrogen bromide from the higher molecular weight hydrocarbons, to generate bromine from the hydrogen bromide for use in the process, to store and subsequently release bromine for use in the process, and to selectively form mono-brominated alkanes in the bromination step. One or more of the reactions of the processes of the present invention may be conducted in a microchannel reactor.
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Page/Page column 69-71
(2012/01/06)
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- AN INTEGRATED PROCESS TO PRODUCE C4+ HYDROCARBONS WITH REMOVAL OF BROMINATED ORGANIC IMPURITIES
-
The present invention provides an integrated process for producing aromatic hydrocarbons and/or C4+ non-aromatic hydrocarbons from low molecular weight alkanes, which includes contacting the low molecular weight alkanes with a halogen and coupling the monohaloalkanes to form aromatic hydrocarbons and/or C4+ non-aromatic hydrocarbons.
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Page/Page column 19
(2010/12/17)
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- AN INTEGRATED PROCESS TO COPRODUCE AROMATIC HYDROCARBONS AND ETHYLENE AND PROPYLENE
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An integrated process for producing aromatic hydrocarbons and ethylene and/or propylene and optionally other lower olefins from low molecular weight hydrocarbons, preferably methane, which comprises: (a) contacting at least one low molecular weight alkane, preferably methane, with a halogen, preferably bromine. under process conditions sufficient to produce a monohaloalkane, preferably monobromomethane, (b) reacting the monohaloalkane in the presence of a coupling catalyst to produce aromatic hydrocarbons and C2+ alkanes, (c) separating the aromatic hydrocarbons from the product mixture of step (b) to produce aromatic hydrocarbons, and (d) cracking at least part of the C2+ alkanes in an alkane cracking system to produce ethylene and/or propylene and optionally other lower olefins.
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Page/Page column 20
(2010/04/28)
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- INTEGRATED PROCESS TO COPRODUCE AROMATIC HYDROCARBONS AND ETHYLENE AND PROPYLENE
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An integrated process for producing aromatic hydrocarbons and ethylene and/or propylene and optionally other lower olefins from low molecular weight hydrocarbons, preferably methane, which comprises: (a) contacting one or more low molecular weight alkanes, preferably methane, with a halogen, preferably bromine, under process conditions sufficient to produce a monohaloalkane, preferably monobromomethane, (b) reacting a first portion of the monohaloalkane in the presence of a coupling catalyst under process conditions sufficient to produce aromatic hydrocarbons and C2-5 alkanes, (c) separating the aromatic hydrocarbons from the product mixture of step (b) to produce aromatic hydrocarbons, (d) reacting a second portion of the monohaloalkane in the presence of a coupling catalyst under process conditions sufficient to produce ethylene and/or propylene.
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Page/Page column 8
(2010/09/18)
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- Rate coefficients for the reactions CH3 + Br2 (224-358 K), CH3CO + Br2 (228 and 298 K), and Cl + Br 2 (228 and 298 K)
-
Rate coefficients for the reactions of CH3 + Br2 (k2), CH3CO + Br2 (k3), and Cl + Br2 (k5) were measured using the laser-pulsed photolysis method combined with detection of the product Br atoms using resonance fluorescence. For the reactions involving organic radicals, the rate coefficients were observed to increase with decreasing temperature and within the temperature range explored, were adequately described by Arrhenius-like expressions: k2 (224-358 K) = 1.83×10-11 exp(252/T) and k3 (228-298 K) = 2.92×10-11 exp(361/T) cm 3 molecule-1 s1. The total, temperature-independent uncertainty for each reaction (including possible systematic errors in Br2 concentration measurement) was estimated as ~7% for k2 and 10% for k3. Accurate data on k5 was obtained at 298 K, with a value of 1.88×10-10 cm3 molecule-1 s-1 obtained (with an associated error of 6%). A limited data set at 228 K suggests that k5 is, within experimental uncertainty, independent of temperature.
- Khamaganov,Crowley
-
experimental part
p. 575 - 585
(2011/04/26)
-
- PROCESS FOR CONVERTING HYDROCARBON FEEDSTOCKS WITH ELECTROLYTIC AND PHOTOELECTROCATALYTIC RECOVERY OF HALOGENS
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A method for converting a hydrocarbon feedstock into higher hydrocarbons is provided comprising reacting a hydrocarbon feedstock with a molecular halogen to form alkyl halides; reacting at least a portion of the alkyl halide in the presence of a catalyst to form higher hydrocarbons and a hydrogen halide; and converting at least a portion of the hydrogen halide into the molecular halogen via photoelectrocatalysis. Additional methods are also provided.
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Page/Page column 33
(2010/11/05)
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- CONTINUOUS PROCESS FOR CONVERTING NATURAL GAS TO LIQUID HYDROCARBONS
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A method comprising: providing a first halogen stream; providing a first alkane stream; reacting at least a portion of the first halogen stream with at least a portion of the first alkane stream in a first reaction vessel to form a first halogenated stream; providing a second alkane stream comprising C2 and higher hydrocarbons; providing a second halogen stream; and reacting at least a portion of the second halogen stream with at least a portion of the second alkane stream in a second reaction vessel to form a second halogenated stream.
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Page/Page column 66-67
(2010/04/03)
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- Halomethane biosynthesis: Structure of a SAM-dependent halide methyltransferase from arabidopsis thaliana
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It's a gas ! The structure of the halomethane-producing halo/thiocyanate methyltransferase enzyme from plants has been determined. The halide ion and the methyl group of S-adenosyl-L-methionine (SAM) were modeled into the active site (see picture; chloride: green sphere; SAM: C green, O red, S yellow, N blue), which indicated their predisposition for reaction. (Figure Presented)
- Schmidberger, Jason W.,James, Agata B.,Edwards, Robert,Naismith, James H.,O'Hagan, David
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supporting information; experimental part
p. 3646 - 3648
(2010/08/19)
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- CONVERSION OF METHANE INTO C3?C13 HYDROCARBONS
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A process for converting methane into C3?C13 hydrocarbons is provided including the steps of reacting methane with oxygen and HBr/H2O over a first catalyst in a first reactor to methane bromides and converting the methane bromides into C3?C13 hydrocarbons and HBr over a second catalyst in a second reactor. The process may further include recovering HBr produced in the second reactor and recylcing it into the first reactor.
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Page/Page column 3
(2009/07/10)
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- HYDROGENATION OF MULTI-BROMINATED ALKANES
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Methods and systems for the hydrogenation of multi-brominated alkanes are provided herein. An embodiment of the present invention comprises a method, the method comprising: reacting at least hydrogen and multi-brominated alkanes in the presence of a catalyst to form a hydrogenated stream comprising brominated alkanes having fewer bromine substituents than the multi-brominated alkanes reacted with the hydrogen. Embodiments of the method further may comprise forming brominated alkanes. Embodiments of the method further may comprising forming product hydrocarbons from brominated alkanes.
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Page/Page column 13
(2009/12/27)
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- Vapor generation of inorganic anionic species after aqueous phase alkylation with trialkyloxonium tetrafluoroborates
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Aqueous phase reaction of trialkyloxonium tetrafluoroborates, R 3O+BF4- (R=Me, Et) has been tested in the alkylation of simple inorganic anionic substrates such as halogen ions, cyanide, thiocyanate, sulphide an
- D'Ulivo, Alessandro,Pagliano, Enea,Onor, Massimo,Pitzalis, Emanuela,Zamboni, Roberto
-
experimental part
p. 6399 - 6406
(2010/04/06)
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- Conversion of CHF3 to CH2=CF2 via reaction with CH4 and CaBr2
-
Reaction of CHF3 and CH4 over CaBr2 was investigated at 400-900°C as a potential route for transforming the highly potent greenhouse gas, CHF3, into the valuable product CH 2=CF2. The homogeneous reaction of CHF3 with CH4 was also studied to assist in understanding the chemistries involved. Compared to the gas phase reaction, the addition of CaBr2 as a reactant increases the conversion of CHF3 and CH4 significantly at low temperatures while to a lesser extent at higher temperatures. In the absence of CaBr2, besides the target product, CH2=CF2, a large amount of C2F4 forms. On addition of CaBr2, the rate of formation of C 2F4 drops dramatically to near zero, while the rate of formation of CH2=CF2 increases considerably at temperatures below 880°C. Experimental and theoretical studies suggest that CHF3 strongly interacts with CaBr2, resulting in the fluorination of CaBr2 to CaF2, the release of active Br species results in the selective formation of CBrF3. The subsequent reactions involving Br, methane, and CBrF3 play a major role in the observed enhanced yield of CH2=CF2.
- Han, Wenfeng,Yu, Hai,Kennedy, Eric M.,Mackie, John C.,Dlugogorski, Bogdan Z.
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p. 5795 - 5799
(2008/12/22)
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- OXIDATION OF ALKYLARENES IN EXPANDED LIQUID REACTION MIXTURE
-
A C8-C2O alkylarene is converted to an arene carboxylic acid in an oxidation reactor by reacting the alkylarene with oxygen under oxidation conditions in the presence of an MC catalyst or bromine-free oxidation catalyst in a volumetrically expanded liquid reaction mixture in which a preferred solvent comprises a homogeneous phase of a monocarboxylic acid and carbon dioxide under elevated pressure, carbon dioxide partial pressure and temperature conditions.
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Page/Page column 18-20; 21-24
(2008/12/06)
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- Catalytic cleavage of phosphate ester bonds by boron chelates
-
Novel chemical compounds are disclosed having the general formula L{YXm}n, wherein X is selected from the Group 13 elements, Y is a halide, and L is a chelating ligand containing at least one binding atom contacting the Group 13 element, the atom being selected from the group consisting of C, N, O, and S, and m and n are integers having a value of at least 1. L may be a Schiff base type ligand, such as a salen ligand. The compositions of the present invention may be bidentate, quadridentate, or greater. The compositions may be used in dealkylation of phosphate esters or ethers. Advantageously, the methods of the present invention may be rendered catalytic.
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Page/Page column 5; 6
(2008/06/13)
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- SN2 reaction of a sulfonate ester in the presence of alkyltriphenylphosphonium bromides and mixed cationic-cationic systems
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The effects of alkyltriphenylphosphonium bromides (CnTPB, n = 10, 12, 14, 16) on the rates of SN2 reactions of methyl 4-nitrobenzenesulfonate and bromide ion have been studied. Observed first-order rate constants are significantly higher than those found for other cationic surfactants for the same reaction. The results have been analyzed by the pseudophase model of micellar kinetics and show true micellar catalysis in the sense that second-order micellar rate constants are higher than the second-order rate constants in water, An attempt has also been made to investigate mixed cationic-cationic surfactant systems with respect to observed rates and pseudophase regression parameters. In addition, modeling of some cationic head groups has illustrated possible differences in head group charges and counterion interactions that may prove kinetically relevant. Copyright
- Mohareb, Michael M.,Ghosh, Kallol K.,Orlova, Galina,Palepu, Rama M.
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p. 281 - 290
(2007/10/03)
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- Kinetics of the reaction of methyl 4-nitrobenzenesulfonate + Br- in ethanol amine based surfactants
-
The kinetics of the reaction of methyl 4-nitrobenzenesulfonate + Br - ions has been studied in ethanol amine based (alkyldimethylethanolammonium bromide and alkyldiethylethanolammonium bromide) surfactant solutions. The observed first-order rate constants increase monotonically with surfactant concentration, with hydrophobic chain length and with head group bulk in a manner similar to other quaternary ammonium surfactants. The results were analyzed using the pseudophase model of micellar rate effects in conjunction with a Langmuir form to describe micellar binding of bromide ion. An attempt to estimate activation parameters of the reaction from temperature variance of micellar pseudophase rate constants has also been made.
- Mohareb, Michael M.,Ghosh, Kallol K.,Palepu, Rama M.
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p. 303 - 308
(2008/02/07)
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- Process for the production of carboxylic acids
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A process for the production of a carboxylic acid or its ester by catalytic liquid phase oxidation of a corresponding precursor in acetic acid as solvent, said process comprising: (i) forming a reaction medium comprising acetic acid, oxidation catalyst, p
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Page/Page column 4
(2008/06/13)
-
- Methyl halide process
-
A process is provided for the production of a methyl halide by reacting carbon monoxide, hydrogen, and hydrogen halide over a catalyst to give methyl halide and carbon dioxide. The reaction is carried out under anhydrous conditions by using a ratio of carbon monoxide to hydrogen of 2-2.5:1. The catalyst contains a metal from the group copper and zinc. High conversion and yields are obtained in the process.
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Page/Page column 3
(2008/06/13)
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- Using Kamlet-Taft solvent descriptors to explain the reactivity of anionic nucleophiles in ionic liquids
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In this paper, we report the effect of ionic liquids on substitution reactions using a variety of anionic nucleophiles. We have combined new studies of the reactivity of polyatomic anions, acetate, trifuoroacetate, cyanide, and thiocyanide, with our previous studies of the halides in [C4C 1Py][Tf2N], [C4C1py][TfO], and [C4C1im][Tf2N] (where [C4C 1im]+ is 1-butyl-3-methylimidazolium and [C 4C1py]+ is 1-butyl-1-methylpyrrolidinium) and compared their reactivities, k2, to the same reactions in the molecular solvents dichloromethane, dimethylsulfoxide, and methanol. The Kamlet-Taft solvent descriptors (α, β, π*) have been used to analyze the rates of the reactions, which were found to have a strong inverse dependency on the α value of the solvent. This result is attributed to the ability of the solvent to hydrogen bond to the nucleophile, so reducing its reactivity. The Eyring activation parameters (ΔH? and ΔS?), while confirming the reaction mechanism, do not offer obvious correlations with the Kamlet-Taft solvent descriptors.
- Crowhurst, Lorna,Falcone, Ruben,Lancaster, N. Llewellyn,Llopis-Mestre, Veronica,Welton, Tom
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p. 8847 - 8853
(2007/10/03)
-
- Cleavage of phosphate ester bonds by use of novel group 13 chelate compounds
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A novel chemical compound has a general formula (LX)nY wherein X is selected from a group consisting of a group 13 element other than boron, Y is selected from a group consisting of a halide, a chlorate, a sulfate and a nitrate and L is a chelating ligand containing two nitrogen and two oxygen donor groups where n=1 or 2.
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Page/Page column 9-10
(2008/06/13)
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- Process for converting gaseous alkanes to liquid hydrocarbons
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A process for converting gaseous alkanes to liquid hydrocarbons wherein a gaseous feed containing alkanes is reacted with a dry bromine vapor to form alkyl bromides and hydrobromic acid vapor. The mixture of alkyl bromides and hydrobromic acid are then reacted over a synthetic crystalline alumino-silicate catalyst, such as a ZSM-5 zeolite, at a temperature of from about 150° C. to about 400° C. so as to form higher molecular weight hydrocarbons and hydrobromic acid vapor. Hydrobromic acid vapor is removed from the higher molecular weight hydrocarbons. A portion of the propane and butane is removed from the higher molecular weight hydrocarbons and reacted with the mixture of alkyl bromides and hydrobromic acid over the synthetic crystalline alumino-silicate catalyst to form C5+ hydrocarbons.
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Page/Page column 7
(2008/06/13)
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